(12) INTERNATIONAL APPLICATION PUBLISHED UNDER THE PATENT COOPERATION TREATY (PCT) (19) World Intellectual Property Organization International Bureau (10) International Publication Number (43) International Publication Date 11 February 2010 (11.02.2010) WO 2010/015037 Al

(51) International Patent Classification: (74) Agents: MUTIMER, Helen, P. et al; Davies Collison A61K 31/4184 (2006.01) A61P 25/16 (2006.01) Cave, 1 Nicholson Street, Melbourne, VIC 3000 (AU). A61K 31/4741 (2006.01) A61P 25/00 (2006.01) (81) Designated States (unless otherwise indicated, for every A61K 31/198 (2006.01) kind of national protection available): AE, AG, AL, AM, (21) International Application Number: AO, AT, AU, AZ, BA, BB, BG, BH, BR, BW, BY, BZ, PCT/AU2009/001012 CA, CH, CL, CN, CO, CR, CU, CZ, DE, DK, DM, DO, DZ, EC, EE, EG, ES, FI, GB, GD, GE, GH, GM, GT, (22) International Filing Date: HN, HR, HU, ID, IL, IN, IS, JP, KE, KG, KM, KN, KP, 7 August 2009 (07.08.2009) KR, KZ, LA, LC, LK, LR, LS, LT, LU, LY, MA, MD, (25) Filing Language: English ME, MG, MK, MN, MW, MX, MY, MZ, NA, NG, NI, NO, NZ, OM, PE, PG, PH, PL, PT, RO, RS, RU, SC, SD, (26) Publication Language: English SE, SG, SK, SL, SM, ST, SV, SY, TJ, TM, TN, TR, TT, (30) Priority Data: TZ, UA, UG, US, UZ, VC, VN, ZA, ZM, ZW. 61/087,497 !August 2008 (08.08.2008) US (84) Designated States (unless otherwise indicated, for every (71) Applicant (for all designated States except US): kind of regional protection available): ARIPO (BW, GH, HOWARD FLOREY INSTITUTE [AU/AU]; Gate 11, GM, KE, LS, MW, MZ, NA, SD, SL, SZ, TZ, UG, ZM, Royal Parade, The University of Melbourne, Parkville, ZW), Eurasian (AM, AZ, BY, KG, KZ, MD, RU, TJ, Victoria 3010 (AU). TM), European (AT, BE, BG, CH, CY, CZ, DE, DK, EE, ES, FI, FR, GB, GR, HR, HU, IE, IS, IT, LT, LU, LV, (72) Inventors; and MC, MK, MT, NL, NO, PL, PT, RO, SE, SI, SK, SM, (75) Inventors/Applicants (for US only): AUMANN, Timo¬ TR), OAPI (BF, BJ, CF, CG, CI, CM, GA, GN, GQ, GW, thy, Douglas [AU/AU]; Gate 11, Royal Parade, The Uni ML, MR, NE, SN, TD, TG). versity of Melbourne, Parkville, Victoria 3010 (AU). HORNE, Malcolm [AU/AU]; Gate 11, Royal Parade, Published: The University of Melbourne, Parkville, Victoria 3010 — with international search report (Art. 21(3)) (AU).

(54) Title: THERAPEUTIC METHODS AND COMPOSITIONS

(57) Abstract: The present invention is generally directed to the field of neurological therapy. More particularly, the present in vention contemplates therapeutic protocols for neurological conditions associated with dopamine deficiency including pharmaceu tical compositions for use in such therapeutic protocols. THERAPEUTIC METHODS AND COMPOSITIONS

This application is associated with and claims priority from United States Patent Application No. 61/087,497, filed on 8 August, 2008, the entire contents of which, are incorporated herein by reference.

FIELD

The present invention is generally directed to the field of neurological therapy. More particularly, the present invention contemplates therapeutic protocols for neurological conditions associated with abnormal levels of dopamine including pharmaceutical compositions for use in such therapeutic protocols.

BACKGROUND

Reference to any prior art in this specification is not, and should not be taken as, an acknowledgement or any form of suggestion that this prior art forms part of the common general knowledge in any country.

Dopamine is a hormone and neurotransmitter occurring in a wide variety of animals, including both vertebrates and invertebrates. In the brain, dopamine functions as a neurotransmitter, activating the five types of dopamine receptor, Dl, D2, D3, D4 and D5, and their variants. Dopamine is produced in several areas of the brain, including the substantia nigra and hypothalamus.

Dopamine is associated with many neurological activities, including having important roles in behavior and cognition, motor activity, motivation and reward, regulation of milk production, sleep, mood, attention and learning. Dopaminergic neurons (i.e., neurons whose primary neurotransmitter is dopamine) are present in the ventral tegmental area (VTA) of the midbrain, substantia nigra pars compacta, arcuate nucleus of the hypothalamus, olfactory bulb and retina. Accordingly, abnormal levels of dopamine (i.e. either too much or too little) has a major impact on the health of an individual.

For example, based on its neurological pleiotrophy, dopamine deficiency is associated with such symptoms as resting tremor, rigidity, bradykinesia (slowing of physical movement), postural instability, physical fatigue, overt fatigue and lethargy, negative behavioral feelings, concentration deficit, weight gain, addictive behavior, reduced libido and/or impotence, depression, alcoholism and attention deficit and hyperactivity disorder (ADHD).

One disease associated with dopamine deficiency is Parkinson's disease (also known as "Parkinson disease" or "PD"). PD is a chronic and progressive degenerative disorder of the central nervous system that impairs movement, speech and other functions.

PD is characterized by motor symptoms including muscle rigidity, tremor, bradykinesia and, in extreme cases, a loss of physical movement (akinesia). Non-motor symptoms include pain/discomfort, anxiety, depression, slowness of thinking, memory deficits, tiredness, disturbed sleep, constipation, bladder problems, sexual difficulties, speech and swallowing difficulties. The primary motor symptoms are the result of decreased stimulation of the motor cortex by the basal ganglia, normally caused by the insufficient formation and action of dopamine, which is produced in the dopaminergic neurons of the brain, particularly those in the substantia nigra.

PD is a chronic disorder that requires broad-based management including patient and family education, support group services, general wellness maintenance, exercise and nutrition. At present, there is no cure for PD, but medications or surgery can provide some relief from the motor symptoms, at least in the short- to medium-terms (5-10 years on average). Neurological disease and disorders contribute immense distress to families and potential injuries to patients, and represent a major cost burden to the community and the healthcare system.

There is a need to further develop therapeutic protocols to treat neurological disease conditions such as those associated with dopamine deficiency. SUMMARY

Throughout this specification and the claims which follow, unless the context requires otherwise, the word "comprise", and variations such as "comprises" and "comprising", will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps.

The present invention relates generally to neurological therapy, and in particular the treatment or prevention of neurological conditions which include neurological diseases and disorders as well as neurodegenerative conditions associated with abnormal levels of dopamine. By "abnormal" dopamine levels it is meant a deficiency or elevation in the level of dopamine. This is generally determined relative to a subject regarded as healthy i.e. with no symptoms of a neurological disorder. It may also be determined by a standardized control based in the measurement of a range of subjects over time. In cases where there is a deficiency in the level of dopamine, the present invention contemplates promoting recruitment of new dopaminergic cells. Examples of nneurological diseases and conditions associated with a dopamine deficiency contemplated for treatment herein include Parkinson's Disease (PD), dystonia, Tourettes syndrome, restless legs, certain psychoses, attention deficit and hyperactivity disorder (ADHD), cognition disorders, motor control disorders, abnormal lactation, sleep disorders, memory deficit, attention deficit, problem solving deficit, learning deficit, abnormal moods, social disorders, abnormal libido, anhedonia and eating disorders.

In cases where there is an elevated level of dopamine, the present invention provides for decreasing the number of dopaminergic cells. Such neurological diseases and conditions associated with enhanced levels of dopamine include schizophrenia, drug addiction, obsessive compulsive disorder, mania and certain psychoses.

Accordingly, the present invention is directed, in one aspect, to a method for treating or preventing a neurological disease or disorder associated with decreased dopamine levels in a subject, the method comprising administering to the subject an agent which modulates neuronal cell excitability, thereby increasing dopaminergic cells. Also contemplated herein is the use of an agent which modulates neuronal excitability in the manufacture of a medicament for treating a neurological condition, and in particular, a neurological condition associated with dopamine deficiency. "Modulates" refers to targeting different cell surface molecules to either decrease or increase neuronal excitability thereby altering the number of dopaminergic cells.

The present invention also contemplates a method of preventing or treating a neurological condition associated with enhanced levels of dopamine, the method comprising administering to a subject an agent which modulates neuronal cell excitability, thereby decreasing the number of dopaminergic cells. Also contemplated is the use of an agent which modulates neuronal excitability in the manufacture of a medicament for treating a neurological condition, and in particular, a neurological condition associated with enhanced levels of dopamine.

Generally, the subject is one in need of therapy. However, the treatment of subjects considered "at risk" of developing symptoms of a neurological condition as well as the treatment of asymptomatic subjects are encompassed by the present invention. Therapeutic protocols contemplated herein may also be provided in conjunction with behavioral modification protocols.

In a particular embodiment, the neuronal cell to be the subject of excitation modulation is from the substantia nigra pars compacta (SNc). Hence, the present invention is further directed to a method for treating a subject with abnormal levels of dopamine, the method comprising administering to the subject an agent which modulates excitability of a cell and in particular neurons in the SNc.

Agents which modulate the excitability of a neuron contemplated for use herein include agonists and antagonists specific for: calcium-activated potassium (Kca) channels

(including KCa2.1, Kca2.2, Kca2.3, KCa3.1, also referred to as SK channels), voltage- activated calcium (Cay) channels (including Cayl.l, Cay 1.2, Cayl.3, Cay 1.4, Caγ2.1, γ γ γ Ca 2.2, Ca 2.3, Cav3.1, Ca 3.2, Ca 3.3), ATP-sensitive potassium (KATP) channels, G protein-coupled inwardly rectifying potassium (GIRK) channels, glutamate receptors

(including AMPA, NMDA and GIuRs), GABA receptors (including GABAA and GABAB) and acetylcholine (ACh) receptors (including nicotinic and muscarinic).

In a particular aspect, agents which specifically target small-conductance calcium- activated potassium (Kca) channels (including Kca2.1, Kca2.2, Kca2.3, Kca3.1), also referred to as "SK channels" are contemplated for use in the methods and compositions of the present invention.

In a further embodiment there is provided a method for treating a disease or disorder associated with a dopamine deficiency, the method comprising administering to a subject an SK channel agonist.

In a particular embodiment, the SK channel agonists are selected from NS309, zoxazolamine, chlorzoxazone, and a benzimidazolone or benzothiazole such as EBIO or a derivative thereof as defined by Formula I.

In one embodiment, a method of increasing dopaminergic cells in a site deficient in dopamine producing cells is provided, the method comprising administering a SK specific agonist to a subject.

In a further aspect, a method for decreasing the number of dopaminergic cells is provided, the method comprising administering o a subject an SK channel antagonist. Examples of SK channel antagonists include, tamapin, apamin, UCL 1848, leiurotoxin, UCL 1684, PO5, Leu-Dab7, Tsk, dequalinium, NS8593, UCL 1407, atracurium, tubocurarine, pancuronium, N-methyl-laudanosine, trifluperazine, bicuculline methiodide, gallamine, chlorpromazine, carbamazepine, cyproheptadiene, imipramine, tacrine, armitryptyline, 4- AP, decamethonium, hexamethonium and TEA. In a related aspect, there is provided a method for decreasing the number of dopaminergic cells in a subject, the method comprising administering to a subject an antagonist or agonist of GABAA receptors or an agonist or antagonist of L-type voltage-activated calcium channels.

Examples of GABAA receptor agonists include gaboxadol, isoguvacine, isonipecotic acid, muscimol, CL-218,872 (highly αl-selective agonist), bretazenil (subtype-selective partial agonist), QH-ii-066 (full agonist highly selective for α5 subtype) , THIP, GABA, and β- alanine.

Examples of GABAA receptor antagonists include bicuculline, gabazine, SR-95531, SR- 95103, TPMPA, picrotoxin and pentylenetetrazol.

Examples of L-type voltage-activated calcium channel agonists include BayK8644, elocalcitol, FPL-641 76 and Dehydrodidemnin B.

Examples of L-type voltage-activated calcium channel antagonists include isradipine, dihydropyridines, phenylalkylamines,benzothiazapines and calcicludines.

The present invention further relates to the use of the above-mentioned agents in the manufacture of a medicament in a therapeutic protocol for the treatment or prophylaxis of a neurological condition.

The present invention extends to therapeutic protocols combining the administration of an agent which modulates the excitability of a neuron with the administration of, for example, levodopa, carbidopa, benserazide, co-careldopa, sinemet, parcopa, co-beneldopa, madopar, duodopa, tolcapone, entacapone, bromocriptine, pergolide, pramipexole, ropinirole, cabergoline, apomorphine, lisuride, selegiline and/or rasagiline and/or functional derivatives thereof. Combination therapy involving an agent which modulates the excitability of a neuron with behavioural modification protocols to assist in controlling the condition being treated in the subject is also contemplated herein.

Pharmaceutical compositions comprising agents which modulate the excitability of a neuron also form part of the present invention. BRIEF DESCRIPTION OF THE FIGURES

Figure 1 is a graphical representation showing changes in number of tyrosine hydroxylase immunopositive (TH+, black bars) and immunonegative (TH-, white bars) SNc cells 5 following infusions of "intrinsic" ion-channel agonists or antagonists directly into SNc. A Schematic diagram of the method. Ion-channel or receptor agonists or antagonists (or vehicle) were infused continuously for 2 weeks into SNc or striatum on the left side of the brain in 8-week old mice using ALZET® osmotic minipumps connected to surgically implanted cannulae. Stereological estimates of the total numbers of TH+ and TH- cells 0 (glia were excluded on the basis of soma diameter <5µm) in the left (infused) and right (control) SNc were then made by an observer unaware of the treatment received. B Low- power photomicrograph of a histological section through the left and right SNc following TH immunohistochemistry and Nissl counterstain. The in situ location of the tip of the cannula above the left SNc can be seen. C High-power photomicrograph of a histological 5 section through SNc following TH immunohistochemistry and Nissl counterstain. Examples of TH+, TH- and glial cells (gl) are indicated. D Mean (±SE) change in number of SNc cells (left SNc minus right SNc) in mice receiving the different treatments.

Treatments were as follows from left to right: vehicle (n = 21); SK agonist lOOµM 1-EBIO (SKt, n = 5); SK agonist 30µM riluzole (SKf, n = 5); SK antagonist 30OnM apamin (SK|, O n = 5); L-type agonist 10OnM FPL64176 (L-typef, n = 5); L-type antagonist l OµM

nimodipine (L-type J0 n = 4); high (3OmM) extracellular potassium (K+T, n = 4); high (3OmM) extracellular potassium plus 30OnM apamin (K+t & SKj, n = 3). Note that separate groups of vehicle infused mice were run concurrently with each treatment type (SK agents, L-type agents, high K+ etc.) throughout this study and no statistically 5 significant differences between left and right SNc (z-test) were detected in numbers of TH+, TH- or total (TH+ & TH-) cells in any vehicle-treated group; vehicle groups have therefore been pooled in this and subsequent figures. Numbers of TH+ (black) and TH- (white) cells are statistically significantly (* = p<0.01 z-test) altered in the infused (left) SNc relative to the control (right) SNc in every treatment group except for the pooled 0 vehicle group and TH+ in the apamin-treated group (SK ). The number of total cells (TH+ & TH-, gray) is not statistically significantly (p>0.01 z-test) altered in the infused (left) SNc relative to the control (right) SNc in every treatment group except for the pooled nimodipine-treated group (L-typej). There was a trend for K+f & SKj to have greater effects than K+f alone but these were not significantly different (ns = ρ>0.05, t-tests).

Figure 2 is graphical representation showing Changes in number of tyrosine hydroxylase immunopositive (TH+, black bars) and immunonegative (TH-, white bars) SNc cells following infusions of "extrinsic" ion-channel (GABAA) agonists or antagonists directly into SNc or following disruption of afferent feedback pathways to SNc cells originating from the striatum (Quinolinic Acid or QA lesions). A Photomicrographs of the left (a & c) and right (b & d) striatum 2-weeks following QA injection into right striatum showing marked striatal cell loss. Regions outlined with squares in a & b are shown at higher power in c & d, respectively. B Mean (±SE) change in number of SNc cells in mice receiving the different treatments. Treatments were as follows from left to right: vehicle (n

= 21); GABAA agonist 20µM muscimol (GABAAf, n = 4); GABAA antagonist lOOµM picrotoxin (GABAAj, n = 5); sham (saline) striatal lesion (sham, n = 3); QA striatal lesions (lesion, n = 6). The decrease in number of TH+ (black) cells in the treated versus internal control SNc is significant (* = p<0.01, z-test) in every treatment group except for the vehicle infusion and sham lesion groups. The changes in number of TH- (white) cells are significant for the GABAA agonist and antagonist only. The changes in number of total cells (TH+ & TH-, gray) is significant in every treatment group except for vehicle and GABAAt (GABAAt is significant at the p<0.05 level).

Figure 3 is a graphical representation showing a 1-EBIO infusion into SNc for 2 weeks almost completely restores the normal number of tyrosine hydroxylase-positive (dopaminergic) neurons following their degeneration in a 6-OHDA mouse model of Parkinson's disease. 6-OHDA was injected into the left SNc of 8-week old male mice. Two weeks later, once ~50% of SNc dopaminergic neurons had degenerated, vehicle, lOOuM 1-EBIO or 20OuM 1-EBIO was infused into the same left SNc for a further 2 weeks via a micro-osmotic pump. At the end of the drug administration period vehicle infused mice exhibited an average ~50% reduction in the normal number of SNc dopaminergic neurons on the left side. lOOuM 1-EBIO had no significant effect compared with vehicle but 200 uM 1-EBIO significantly (t-test, p=0.29 20OuM vs. vehicle) increased the number of dopaminergic cells, almost back to normal (100%) levels.

Figure 4 is a graphical representation showing a systemically administered riluzole for 2 weeks has no beneficial effect on the number of tyrosine hydroxylase-positive (dopaminergic) neurons following their degeneration in a 6-OHDA mouse model of Parkinson's disease. 6-OHDA was injected into the left SNc of 8-week old male mice. Two weeks later, once -50% of SNc dopaminergic neurons had degenerated, vehicle, 3uM riluzole or 3OuM riluzole was administered to the mice in their drinking water for a further 2 weeks. At the end of the drug administration period vehicle infused mice exhibited an average -50% reduction in the normal number of SNc dopaminergic neurons on the left side. Neither 3uM nor 3OuM riluzole had a significant effect compared with vehicle. DETAILED DESCRIPTION

The singular forms "a", "an" and "the" include herein plural aspects unless the context clearly indicates otherwise. Thus, for example, reference to "a neurological condition" includes a single neurological condition, as well as two or more conditions; reference to "an agent" includes a single agent, as well as two or more agents; reference to "the invention" includes single or multiple aspects of an invention.

The present invention is directed to the treatment or prophylaxis of neurological conditions. More particularly, the present invention contemplates the treatment or prevention of a neurological condition associated with abnormal levels of dopamine. The present invention is predicated, in part, on the determination that modulating the excitability of a neuron through different cell surface molecules results in an increase or decrease in the number of dopaminergic cells. Reference to a "condition" includes a disease or a disorder as well as a neurodegenerative condition. Hence, in neurological conditions characterized or exacerbated by a dopamine deficiency, the present invention contemplates the administration of agents which modulate neuronal cell excitability to increase the number of dopaminergic cells. In conditions characterized by or exacerbated by elevated levels of dopamine, the present invention provides the administration of agents which modulate neuronal cell excitability to decrease the number of dopaminergic cells.

A method is in one embodiment provided therefore, for treating or preventing a neurological disease or disorder associate with dopamine deficiency in a subject, the method comprising administering to a subject an agent which modulates neuronal cell excitability, thereby increasing the number of dopaminergic cells.

In another aspect there is provided a method of treating or preventing a neurological condition associated with elevated levels of dopamine in a subject, the method comprising administering to the subject an agent which modulates neuronal cell excitability thereby decreasing the number of dopaminergic cells. Related to this embodiment is the use of an agent which modulates neuronal excitability in the manufacture of a medicament for treating a neurological condition, and in particular a neurological condition associated with abnormal levels of dopamine.

The subject being treated may be in need of such treatment or may be "at risk" of developing a neurological condition. The subject may have symptoms or may be asymptomatic of a neurological condition. The subject may also be provided with behavioral modification protocols.

Examples of neurological diseases and disorders associated with dopamine deficiency contemplated herein include, Parkinson's Disease (PD), dystonia, Tourettes syndrome, restless legs, psychosis, attention deficit and hyperactivity disorder (ADHD), cognition disorders, motor control disorders, abnormal lactation, sleep disorders, memory deficit, attention deficit, problem solving deficit, learning deficit, abnormal moods, social disorders, abnormal libido, anhedonia and eating disorders.

Examples of neurological diseases and conditions associated with enhanced levels of dopamine contemplated for treatment herein include schizophrenia, drug addiction, obsessive compulsive disorder, mania and psychosis.

Reference to an "agent" should be understood as a reference to any proteinaceous or non- proteinaceous molecule derived from natural, recombinant or synthetic sources. Useful sources for agents may be identified by a variety of techniques including inter alia, the screening of natural molecular libraries, chemical molecule libraries, phage display libraries and in vitro based libraries. The agents may also be nucleic acid molecules. Furthermore, the agents may be immunoglobulins such as antibodies or fragments or synthetic or modified forms thereof. An "immunoglobulin" includes an immunoglobulin new antigen receptor (IgNAR) from cartilaginous fish such as sharks (see WO2005/1 18629). The terms "agent", "compound", "active agent", "pharmaceutically active agent", "medicament", "active" and "drug" may be used interchangeably herein to refer to any agent that induces a desired pharmacological and/or physiological effect. Such effects include decreasing or increasing neuronal excitability and/or altering the number of dopaminergic cells. The terms also encompass pharmaceutically acceptable and pharmacologically active ingredients of those active agents specifically mentioned herein including, but not limited to, salts, esters, amides, prodrugs, active metabolites, analogs, and the like. When the terms "agent", "compound", "active agent", "pharmacologically active agent", "medicament", "active", and "drug" are used, it is to be understood that this includes the active agentper se as well as pharmaceutically acceptable, pharmacologically active salts, ester, amides, prodrugs, metabolites, analogs, etc.

Particular agents which decrease neuronal excitability include agents which act upon channels and receptors expressed on neuronal cells to directly decrease the level of excitability of the neuron. Conversely, the agent may act indirectly to decrease the level of excitability of the neuron by initiating a cascade of cellular events, the downstream effects of which result in decreased neuronal excitability.

Included within the agents which modulate neuronal excitability are, for example agonists and antagonists of: calcium-activated potassium (Kca) channels (including Kca2.1, Kca2.2, γ Kca2.3, Kca3.1), voltage-activated calcium (Cav) channels (including Ca l.1, Ca l.2, γ Ca l.3, Cavl.4, Cav 2.1, Cav 2.2, Cav 2.3, Cav 3.1, Cav 3.2, Cav 3.3), ATP-sensitive potassium (KATP) channels, G protein-coupled inwardly rectifying potassium (GIRK) channels, glutamate receptors (including AMPA, NMDA and GIuRs), GABA receptors (including GABAA d GABAB) and acetylcholine (ACh) receptors (including nicotinic and muscarinic).

In a particular embodiment there is provided a method for treating a disease or disorder associated with a dopamine deficiency in a subject, the method comprising administering to the subject an SK channel agonist. In one aspect, the agent is one which agonises calcium-activated potassium (Kc ) channels

including KCa2.1 (also known as SKl, SKCaI or KCNNl), KCa2.2 (also known as SK2,

SKCa2 or KCNN2), KCa2.3 (also known as SK3, SKCa3 or KCNN3) and KCa3.1 (also known as SK4, IKl, IKCaI or Gardos channel). Such agents include, without being

limited to EBIO, DCEBIO 5NS309, zoxazolamine, Cyclohexyl-[2-(3,5-dimethyl-pyrazol-l- yl)-6-methyl-pyrimidin-4-yl]-amine (CyPPA) and their pharmaceutically acceptable salts thereof.

An "SK specific agonist" is defined as one which, at one or more doses, has proportionally more activity through SK channels affecting cell excitability than on any other known or unknown ion-channel or receptor affecting cell excitability. "Activity" in certain aspects means it recruits more SNc dopaminergic cells when administered to normal mice or a mouse model of Parkinson's disease than riluzole. For example 1-EBIO is a more "specific" SK channel agonist than riluzole because, when administered to normal mice or mice in which SNc dopaminergic cells have been depleted (e.g. using the 6-OHDA mouse model of Parkinson's disease), it increases the number of SNc dopaminergic cells more so than riluzole.

In certain aspects, an SK agonist has:

1. At least 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99 or 100% of its activity through SK channels; and/or 2. At least 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99 or 100% of the its activity is blocked by the administration of a specific SK channel antagonist such as apamin.

The specificity of agents for SK channel activity can be measured by placing an electrode inside a cell in which a number of different ion-channels and receptors, including SK channels, are functionally expressed, e.g. SNc dopaminergic cells. Currents passing into and out of the cell through each individual ion-channel or receptor can then be isolated using either controlled voltage steps or exposure to ligands known to specifically activate or inhibit each individual ion-channel or receptor. An agent to be tested would then be applied to the cell and the change in current passing through each individual ion-channel or receptor measured. For example, to measure SK specific current the membrane potential can be stepped from -7OmV +3OmV for 100 ms, then stepped to -9OmV for 1 second. The current thus measured largely comprises current passing through SK channels. SK channel current can be further isolated by applying the SK channel specific antagonist apamin and repeating the above voltage step protocol. The current blocked by apamin will be equal to the current passing through SK channels in the absence of apamin.

SK channel agonists include, without being limited to, NS309, zoxazolamine, chlorzoxazone, and a benzimidazolone or benzothiazole such as EBIO or a derivative thereof as defined by Formula I.

Therefore, in one aspect, the present invention provides a method for increasing dopaminergic cells in a site deficient in dopaminergic cells, the method comprising administering a SK specific agonist.

In a related aspect, the administration of the SK channel specific agonists results in migration or recruitment of dopaminergic cells, such as neurons, to the site of the brain deficient in dopamine. This is in contrast to known treatments of dopamine deficient diseases or disorders where either dopamine per se is administered, or the therapeutic treatment is administered as a neuroprotective.

Accordingly, one aspect of the present invention is directed to a method of inducing migration of dopaminergic cells to a site deficient in dopamine producing cells comprising administering a SK specific agonist. A related aspect is directed to a method of recruiting dopaminergic cells to an area deficient in dopamine producing cells comprising administering to a subject a SK specific agonist.

In a further embodiment the present invention provides for a method of stimulating synthesis of dopamine in resident non-dopaminergic cells, such as neurons, comprising the administration of the SK specific agonists.

In one aspect, the SK specific agonist is a Kca2.3 specific agonist.

In an embodiment of the present invention, the agent is EBIO or a pharmaceutically acceptable salt or derivative thereof. Thus, in certain embodiments of the invention, the agent is a benzimidazolone compound defined by Formula (I):

wherein R and R2 are independently selected from hydrogen, hydroxy, optionally substituted alkyl, optionally substituted cycloalkyl, optionally substituted cycloalkyl, optionally substituted alkenyl, optionally substituted alkynyl, optionally substituted acyl, optionally substituted phenyl, optionally substituted -(CH^xphenyl, optionally substituted alkoxy, optionally substituted cycloalkoxy, optionally substituted alkenyloxy, optionally substituted alkynyloxy, optionally substituted acyloxy, optionally substituted phenoxy and optionally substituted -O(CH2)xphenyl; each R3 is independently selected from alkyl, alkenyl, alkynyl, cycloalkyl, hydroxyalkyl alkoxyalkyl, alkoxy, alkoxyalkoxy, cycloalkoxy, halo, haloalkyl, haloalkoxy, hydroxy, thio, sulfonyl, sulfonamido, sulfonate, NH2, alkylamino, dialkylamino, acylamino, diacylamino, nitro, cyano, acyl, acyloxy, -CO2H, -CO2alkyl, -CONH2, -C(O)NHalkyl, - C(O)Ndialkyl aminoalkyl, thioalkyl, carboxyalkyl, carboxyesteralkyl, amidoalkyl, acylalkyl, nitroalkyl, phenyl, -(CH2)xphenyl phenoxy -O(CH 2)xphenyl,

C(O)(CH2)xphenyl, -OC(O)CO 2phenyl, -CO2-(CH2)xphenyl, -NHphenyl, -NH-

(CH2)xphenyl, -C(O)NHphenyl, -C(O)NH(CH2)xphenyl, wherein alkyl, alkenyl, alkynyl, cycloalkyl and phenyl, alone or as part of a group, may be further substituted one or more times by one or more optional substituents, or any 2 adjacent R3 groups together form a Cj-

C4 alkylene group or -0-(CH )S-O- or -NR'-(CH 2)S-NR'- group, wherein s is 1 or 2 and each R' is independently H or Ci--6alkyl; x is an integer from 1 to 6; n is an integer from 0 to 4; or a pharmaceutically acceptable salt, solvate and prodrug thereof.

As used herein, the term "alkyl" or "alk", used either alone or in compound words denotes straight chain, or branched alkyl, in certain embodiments Ci- Oalkyl, e.g. C O or Ci-6. Examples of straight chain and branched alkyl include methyl, ethyl, ^-propyl, isopropyl, «-butyl, sec-butyl, /-butyl, n-pentyl, 1,2-dimethylpropyl, 1,1-dimethyl-propyl, hexyl, 4- methylpentyl, 1-methylpentyl, 2-methylpentyl, 3-methylpentyl, 1,1-dimethylbutyl, 2,2- dimethylbutyl, 3,3-dimethylbutyl, 1,2-dimethylbutyl, 1,3-dimethylbutyl, 1,2,2,- trimethylpropyl, 1,1,2-trimethylpropyl, heptyl, 5-methylhexyl, 1-methylhexyl, 2,2- dimethylpentyl, 3,3-dimethylpentyl, 4,4-dimethylpentyl, 1,2-dimethylpentyl, 1,3- dimethylpentyl, 1,4-dimethyl-pentyl, 1,2,3-trimethylbutyl, 1,1,2-trimethylbutyl, 1,1,3- trimethylbutyl, octyl, 6-methylheptyl, 1-methylheptyl, 1,1,3,3-tetramethylbutyl, nonyl, 1-, 2-, 3-, 4-, 5-, 6- or 7-methyl-octyl, 1-, 2-, 3-, 4- or 5-ethylheptyl, 1-, 2- or 3-ρropylhexyl, decyl, 1-, 2-s 3-, A-, 5-, 6-, 7- and 8-methylnonyl, 1-, 2-, 3-, 4-, 5- or 6-ethyloctyl, 1-, 2-5 3- or 4-propylheptyl, undecyl, 1-, 2-, 3-, 4-, 5-, 6-, 7-, 8- or 9-methyldecyl, 1-, 2-, 3-, A-, 5-, 6- or 7-ethylnonyl, 1-, 2-s 3-, 4- or 5-propylocytl, X-, 2- or 3-butylheptyl, 1-pentylhexyl, dodecyl, 1-, 2-, 3-, A-, 5-, 6-, 7-, 8-, 9- or 10-methylundecyl, 1-, 2-, 3-, A-, 5-, 6-, 7- or 8- ethyldecyl, 1-, 2-, 3-, 4-, 5- or 6-propylnonyl, 1-, 2-, 3- or 4-butyloctyl, 1-2-pentylheptyl and the like. Where an alkyl group is referred to generally as "propyl", butyl" etc, it will be understood that this can refer to any of straight or branched isomers where appropriate. An alkyl group may be optionally substituted by one or more optional substituents as herein defined.

The term "cycloalkyl" includes any of mono or bicyclic, including fused, saturated hydrocarbon resides. Particular examples include cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclononyl, cyclodecyl and and decalinyl. A cycloalkyl group may be optionally substituted by one or more optional substituents as herein defined.

The term "alkenyl" as used herein denotes groups formed from straight chain or branched hydrocarbon residues containing at least one carbon to carbon double bond including ethylenically mono-, di- or poly-unsaturated alkyl groups as previously defined, in one aspect C2-20 alkenyl (e.g. C -I0 or C2-6). Examples of alkenyl include vinyl, allyl, 1- methylvinyl, butenyl, iso-butenyl, 3-methyl-2-butenyl, 1-pentenyl, 1-hexenyl, 3-hexenyl, 1-heptenyl, 3-heptenyl, 1-octenyl, 1-nonenyl, 2-nonenyl, 3-nonenyl, 1-decenyl, 3-decenyl, 1,3-butadienyl, l-4,pentadienyl, 1,3-hexadienyl and 1,4-hexadienyl. An alkenyl group may be optionally substituted by one or more optional substituents as herein defined.

As used herein the term "alkynyl" denotes groups formed from straight chain or branched hydrocarbon residues containing at least one carbon-carbon triple bond including ethynically mono-, di- or poly- unsaturated alkyl groups as previously defined. Unless the number of carbon atoms is specified the term can refers to C2-20 alkynyl (e.g. C2- io or C2-6). Examples include ethynyl, 1-propynyl, 2-propynyl, and butynyl isomers, and pentynyl isomers. An alkynyl group may be optionally substituted by one or more optional substituents as herein defined.

Terms written as "[groupjoxy" refer to a particular group when linked by oxygen, for example, the terms "alkoxy", "alkenoxy", "alkynoxy" and "aryloxy" and "acyloxy" respectively denote alkyl, alkenyl, alkynyl, aryl and acyl groups as hereinbefore defined when linked by an oxygen atom. Terms written as "[group]thio" refer to a particular group when linked by sulfur, for example, the terms "alkylthio", "alkenylthio", alkynylthio" and "arylthio" respectively denote alkyl, alkenyl, alkynyl, aryl groups as hereinbefore defined when linked by a sulfur atom. Similarly, a term written as "[groupA]groupB" is intended to refer to a groupA when linked by a divalent form of groupB, for example,

"hydroxyalkyl" is a hydroxy group when linked by an alkylene group, such as HO-CH -.

The term "halogen" ("halo") denotes fluorine, chlorine, bromine or iodine (fluoro, chloro, bromo or iodo).

The term "acyl" either alone or in compound words denotes a group C(O)-R, wherein R is hydrogen (formyl) or an alkyl, cycloalkyl, alkenyl, alkynyl, phenyl, or a -(CH2)xphenyl (where x is 1-6) residue. Examples of acyl include formyl, straight chain or branched alkanoyl (e.g. Ci-20) such as, acetyl, propanoyl, butanoyl, 2-methylpropanoyl, pentanoyl, 2,2-dimethylpropanoyl, hexanoyl, heptanoyl, octanoyl, nonanoyl, decanoyl, undecanoyl, dodecanoyl, tridecanoyl, tetradecanoyl, pentadecanoyl, hexadecanoyl, heptadecanoyl, octadecanoyl, nonadecanoyl and icosanoyl; cycloalkylcarbonyl such as cyclopropylcarbonyl cyclobutylcarbonyl, cyclopentylcarbonyl and cyclohexylcarbonyl; benzoyl, phenylacetyl, phenylpropanoyl, phenylbutanoyl, phenylisobutylyl, phenylpentanoyl and phenylhexanoyl. The R residue may be optionally substituted as described herein.

The term "carboxy ester" is used here in its broadest sense as understood in the art and includes groups having the formula -CO2R, wherein R may be selected from groups including alkyl, alkenyl, alkynyl, cycloalkyl, phenyl and (CH2)xphenyl, where x is 1-6.

Some examples of carboxy ester include -C0 2C ]-2oalkyl, such as CO2Ci-6alkyl, -

CO2phenyl, and -CO2 CH2phenyl. The R residue may be optionally substituted as described herein. The term "sulfonyl", either alone or in a compound word, refers to a group S(O) -R3 wherein R is selected from hydrogen, alkyl, cycloalkyl, alkenyl, alkynyl, phenyl, acyl, and benzyl. Some examples of R include hydrogen, Ci.2oalkyl, phenyl and benzyl.

The term "sulfonamide", or "sulfonamyl" of "sulfonamido", either alone or in a compound word, refers to a group S(O) NRR wherein each R is independently selected from hydrogen, alkyl, cycloalkyl, alkenyl, alkynyl, phenyl, acyl, and benzyl. Examples of R include hydrogen, Ci-2oalkyl, phenyl and benzyl. In an embodiment at least one R is hydrogen. In another form, both R are hydrogen.

The term "sulfonate" refers to a group SO3R wherein each R is independently selected from hydrogen (sulfonic acid), alkyl, cycloalkyl, alkenyl, alkynyl, phenyl, acyl, and benzyl

Some examples of R include hydrogen, Ci-2oalkyl, phenyl and benzyl.

The term "thio" is intended to include groups of the formula "-SR" wherein R can be hydrogen (thiol), alkyl, cycloalkyl, alkenyl, alkynyl, phenyl, acyl, and benzyl. Examples of R include hydrogen, C1-2oalkyl, phenyl and benzyl.

The term, "amino" includes groups of the formula -NRARB wherein RΛ and RB may be any group independently selected from hydrogen, hydroxyl, alkyl, alkoxyalkyl, alkoxyalkoxy, alkenyl, alkynyl, phenyl, benzyl, cycloalkyl, and acyl, each of which may be optionally substituted. RA and RB, together with the nitrogen to which they are attached, may also form a monocyclic, or polycyclic ring system e.g. a 3-10 membered ring, particularly, 5-6 and 9-10 membered systems. Examples of "amino" include -NH2, -NHalkyl (e.g. -NHCi -

20alkyl), -NHalkoxyalkyl, -NHphenyl), -NHbenzyl, -NHacyl (e.g. -NHC(O)C i-20alkyl, -

NHC(O)phenyl), -Ndialkyl (wherein each alkyl, for example C1-20, may be the same or different, eg NMe 2, NEt2, NPr2 and N'Pr2). Reference to groups written as "[group]amino" is intended to reflect the nature of the RA and RB groups. For example, "alkylamino" refers to -NRARB where one of RA or RB is alkyl and the other is hydrogen. nDialkylamino" refers to -NRARB where RA and RB are each (independently) an alkyl group. 1 2 In some embodiments, R and R are independently selected from hydrogen, Ci-6alkyl (e.g methyl, ethyl or propyl), haloCi_6alkyl (e.g trifluoromethyl), C2-6alkenyl, C2-6alkynyl, C3. ecycloalkyl, phenyl, benzyl (x 1), C(O)CI-6alkyl (e.g C(O)Me, C(O)Et, C(O)Pr) C(O)phenyl, and the "oxy" versions thereof, i.e. when linked via oxygen. In other embodiments of ~(CH2)xphenyl and O(CH2)xphenyl, x is 2, 3, 4, 5 or 6.

3 Some non-limiting examples of R groups contemplated herein include: Ci-6alkyl (such as methyl, ethyl, propyl, butyl), C2-6alkenyl, C2-6alkynl, C3-6cycloalkyl (such as cyclopropyl, cyclobutyl, cyclopentyl or cyclohexyl), hydroxyCi -6alkyl, (such as hydroxymethyl, hydroxyethyl, hydroxypropyl), Ci-6alkoxyCi -6alkyl (such as methoxymethyl, methoxyethyl, methoxypropyl, ethoxymethyl, ethoxyethyl, ethoxypropyl),

(such as methoxy, ethoxy, propoxy, butoxy), C].6alkocyC .6 alkoxy (such as methoxymethoxy, methoxyethoxy, methoxypropoxy, ethoxymethoxy, ethoxyethoxy, ethoxypropoxy, propoxymethoxy, propoxyethoxy, propoxypropoxy) C3-C6cycloalkoxy

(cyclopropoxy, cyclobutoxy, cyclopentoxyl, cyclohexyloxy), F, Cl, Br, I, haloCi -6alkyl (such as chloromethyl, difluoromethyl, trifluoromethyl, trichloromethyl, tribromomethyl), haloC 1-6alkoxy, hydroxy, thio (-SH), -SO2C]-6alkyl, -SO2phenyl, -SO3H, -SO3C]-6alkyl, -

SO NH2, phenyl, benzyl, phenoxy, benzyloxy, NH2, -NHCi. 6alkyl, (such as methylamino, ethylamino, propylamino ), -NH(Ci-6alkyI)2 (such as dimethylamino, diethylamino, dipropylamino), -NHC(O)C i-6alkyl (such as -NHC(O)CH 3), -N(C(O)C i-6alkyl)2 (such as

N(C(O)CH 3)2), -NHphenyl, nitro (NO2), cyano (CN) 5 formyl, -C(O)-alkyl (e.g. -C(O)Ci -

6alkyl5 such as acetyl), O-C(O)-alkyl (e.g. -OC(O)C i-6alkyl, such as acetyloxy), benzoyl, benzoyloxy, CO2H5 CO2Ci-6alkyl (such as methyl ester, ethyl ester, propyl ester, butyl ester), C0 2phenyl, C0 2benzyl, CONH2, C(O)NHphenyl, C(O)NHbenzyl 5 C(O)NHC 1-

6alkyl (such as methyl amide, ethyl amide, propyl amide, butyl amide) C(O)N(C i-6alkyI)2),

H2NCi -6alkyl-, Ci-6alkylHN-Ci. 6alkyl-5 (C1-6alkyl)2N-Ci -6alkyl-), HSC 1-6alkyl-, HO2CC1-

6alkyl-, C1-6alkyl0 2CC1-6alkyl-, H2N(O)CC 1-6alkyl-, H(C 1-6alkyl)N(O)CCi -6alkyl-, OHCC 1-

alkyl-, C 1-6alkyl(O)CCi -6alkyl-), O2NC 6alkyl-, or and 2 adjacent R3 groups together form C3-C4 alkylene, 0-CH 2-O or O-(CH2)2-O (wherein phenyl or benzyl, alone or as part of a group, may be further substituted one or more times by one or more C1-6alkyl, halo, hydroxy, hydroxyCi. 6alkyl, C1-6alkoxy, Ci.6alkoxyCi -6alkyl, Ci-6alkoxyCi -6alkoxy, haloCj. alkyl, haloC 1-6alkoxy, cyano, nitro, OC(O)C, -6alkyl, NH2 NHC). 6alkyl, NHC(O)C ]-6alkyl andNC 1-6alkylCi -6alkyl).

In an embodiment, n is 0 or 1. In another embodiments, n is 2, 3 or 4.

As used herein, "optionally substituted" means that a group may be unsubstituted or substituted with one or more, same or different, substituents. Optional substitutents contemplated herein include: Ci^alkyl (such as methyl, ethyl, propyl (n- and /-), butyl(n-, sec- and t-)), C3-6cycloalkyl (such as cyclopropyl, cyclobutyl, cyclopentyl or cyclohexyl), hydroxyCi -6alkyl, (such as hydroxymethyl, hydroxyethyl, hydroxypropyl), C1-6alkoxyCi.

6alkyl (such as methoxymethyl, methoxyethyl, methoxypropyl, ethoxymethyl, ethoxyethyl, ethoxypropyl), Ci-6alkoxy, (such as methoxy, ethoxy, propoxy, butoxy), C ]-6alkocyCi_6 alkoxy (such as methoxymethoxy, methoxyethoxy, methoxypropoxy, ethoxymethoxy, ethoxyethoxy, ethoxypropoxy, propoxymethoxy, propoxyethoxy, propoxypropoxy) C3- Cgcycloalkoxy (cyclopropoxy, cyclobutoxy, cyclopentoxyl, cyclohexyloxy), F, Cl, Br, I, haloC 1-6alkyl (such as chloromethyl, difluoromethyl, trifluoromethyl, trichloromethyl, θ tribromomethyl), haloC ealkoxy, hydroxy, thio (-SH), -S 2C1-6alkyl, -S0 2phenyl, -SO H,

-SO3C1-6alkyI5 -SO2NH2, phenyl, benzyl, phenoxy, benzyloxy, NH2, -NHC^alkyl, (such as methylamino, ethylamino, propylamino ), -NH(Ci-6alkyI)2 (such as dimethylamino, diethylamino, dipropylamino), -NHC(O)C .6alkyl (such as -NHC(O)CH 3), -N(C(O)Ci.

6alkyl)2 (such as -N(C(O)CH 3)2), -NHphenyl, nitro (NO2), cyano (CN), formyl, -C(O)- alkyl (e.g. -C(O)C 1-6alkyl, such as acetyl), O-C(O)-alkyl (e.g. -OC(O)C i-6alkyl, such as acetyloxy), benzoyl, benzoyloxy, CO H CO2Ci-6alkyl (such as methyl ester, ethyl ester, propyl ester, butyl ester), C0 2phenyl, -C0 2benzyl, -CONH2, -C(O)NHphenyl, -

C(O)NHbenzyl, -C(O)NHC i- alkyl (such as methyl amide, ethyl amide, propyl amide, butyl amide) -C(O)N(C 1-6alkyl)2), H2NCi -6alkyl-, d-ealkylKN-d- alkyl-, (d- 6alkyl)2N-d- i- ealkyl-), HSC 1-6alkyl-, HO2CC 6alkyl-, C1-6alkyl0 2CC1-6alkyl-, H2N(O)CC i-6alkyl-, H(C 1-

6alkyl)N(O)CCi -6alkyl-, OHCCi. 6alkyl-, C1-6alkyl(O)CC 1-6alkyl-, O2NCi -6alkyl-, or and 2 adjacent R3 groups together form C3-C4 alkylene, 0-CH 2-O or O-(CH2)2-O, (and wherein phenyl or benzyl, alone or as part of a group, may be further substituted one or more times by one or more Ci-6alkyl, halo, hydroxy, hydroxyCi 6alkyl, Ci-6alkoxy, Ci-6alkoxyCi. 6alkyl, Ci.6alkoxyC 1-6alkoxy, haloC 1-6alkyl, haloCi -6alkoxy, cyano, nitro, -OC(O)C]^alkyl,

-NH2, -NHC 1-6alkyl, -NHC(O)Cj.6alkyl and

In further embodiments, optional substituents are selected from: Ci_6alkyl, halo, hydroxy, hydroxyC 1-6alkyl, Ci^alkoxy, Ci.6alkoxyC] -6alkyl, Ci-6alkoxyCi -6alkoxy, haloCi. 6alkyl, haloCi -6alkoxy, cyano, nitro, OC(O)Ci -6alkyl, -NH2, -NHCi -6alkyl, -NHC(O)C J-6alkyl and

-N(Ci -6alkyl)C 1-6alkyl.

Exemplary compounds of Formula (I) include EIBO (l-ethyl-2-benzimidazolone), DCEIBO (5,6-dichloro-l-ethyl-2-benzimidazolone), l-benzhydryl-2-benzimidazolone, 4,5-dimethyl-2-benzimidazolone, 4-chloro-6 trifluoro-2-benzimidazolone, 4-methyl-2- benzimidazolone, 5,6-dimethyl-2-benzimidazolone, 5-azo-2-benzimidazolone, 5-carboxy- 2-benzimidazolone, 5-carboxy-2-benzimidazolone methyl ester, 5-chloro-2- benzimidazolone, 5-cyano-22-benzimidazolone, 5-fluoro-2-benzimidazolone, 5-methoxy- 2-benzimidazolone, 5-methyl-2-benzimidazolone, 5-trifluoro-2-benzimidazolone, 5- sulfonic acid-2-benzimidazolone, 5-ethoxy-2-benzimidazolone, 5-hydroxy-2- benzimidazolone, 5-fluoro-2-benzimidazolone, 5-bromo-2-benzimidazolone 5 5-acetyl-2- benzimidazolone, 5,6-dimethyl-2-benzimidazolone, l,5-dimethyl-2-benzimidazolone, 4,6- dichloro-2-benzimidazolone, 4,5,6-trichloro-2-benzimidazolone and 4,5-dichloro-l,3- ethyl-2-benzimidazolone.

It will also be recognised that certain compounds of formula (I) may possess asymmetric centres and are therefore capable of existing in more than one stereoisomeric form, such as enantiomers and diastereomers. The invention thus also relates to optically active compounds and compounds in substantially pure isomeric form at one or more asymmetric centres, e.g., enantiomers having greater than about 90% ee, such as about 95% or 97% ee or greater than 99% ee, as well as mixtures, including racemic mixtures, thereof. Such isomers may be prepared by asymmetric synthesis, for example using chiral intermediates, enzymes, or mixtures may be resolved by conventional methods, e.g., chromatography, recrystallization, or use of a resolving agent. The present invention also relates to prodrugs of formula (I). Any compound that is a prodrug of a compound of formula (I) is within the scope and spirit of the invention. The term "prodrug" is used in its broadest sense and encompasses those derivatives that are converted in vivo, either enzymatically or hydrolytically, to the compounds of the invention. Such derivatives would readily occur to those skilled in the art, and include, for example, compounds where a free thiol or hydroxy group is converted into an ester, such as phosphonate, sulphonate and carboxy esters, such as an acetate, or thioester or where a free amino group is converted into an amide such as a carboxy, phosphonate or sulphonate amide. Procedures for acylating the compounds of the invention, for example to prepare ester and amide prodrugs, are well known in the art and may include treatment of the compound with an appropriate carboxylic acid, anhydride or chloride in the presence of a suitable catalyst or base. Esters of carboxylic acid (carboxy) groups are also contemplated.

Suitable esters C1-6alkyl esters; C -6alkoxymethyl esters, for example methoxymethyl or ethoxymethyl; Ci-6alkanoyloxymethyl esters, for example, pivaloyloxymethyl; phthalidyl esters; C3-8cycloalkoxycarbonylCi -6alkyl esters, for example, 1- cyclohexylcarbonyloxy ethyl; l,3-dioxolen-2-onylmethyl esters, for example, 5-methyl-l,3- dioxolen-2-onylmethyl; and Q-ealkoxycarbonyloxyethyl esters, for example, 1- methoxycarbonyloxy ethyl. Prodrugs of amino functional groups include amides (see, for example, Kyncl et al Adv Bio Sci 20:369, 1979), enamines (see, for example, Caldwell et al J Pharm Sci 60:1810, 1971), Schiff bases (see, for example, United States Patent No. 2,923,661 and Smyth et al. Antimicrob Agents Chemother 19:1004, 1981), oxazolidines (see, for example, johansen et al. J Pharm Sci 72:1294, 1983), Mannich bases (see, for example, Bundgaard et al J Pharm Sci 69:44, 1980, and Gottstein et al J Am Chem Soc 57:1 198, 1959), hydroxymethyl derivatives (see, for example, Bansal et al J Pharm Sci 70, 855, 1981) and N-(acyloxy)alkyl derivatives and carbamates (see, for example, Bodor et al J Med Chem 23:469, 1980, Firestone et al J Med Chem 27:1037, 1984, Kreiger et al. J Med Chem 10:960, 1967, United States Patent No. 5,684,018 and Alexander et al J Med Chem 31:, 318-322, 1988). Other conventional procedures for the selection and preparation of suitable prodrugs are known in the art and are described, for example, in WO 00/23419; Bundgaard Design of Prodrugs Ed., Elsevier Science Publishers, 1985; Widder K Methods in Enzymology 42:309-396 1985; Krogsgaard and Bundgaard A Textbook of Drug Design and Development, Eds, 5:113-191, 1991; Advanced Drug Delivery Reviews, 8:1-38, 1992; Bundgaard et al Journal of Pharmaceutical Sciences

77V285, 1988, Kakeya et al Chem Pharm Bull 32692, 1984, and The Organic Chemistry of Drug Design and Drug Action 5:352-401, 1992.

Suitable pharmaceutically acceptable salts of compounds of formula (I) include, but are not limited to salts of pharmaceutically acceptable inorganic acids such as hydrochloric, sulphuric, phosphoric nitric, carbonic, boric, sulfamic, and hydrobromic acids, or salts of pharmaceutically acceptable organic acids such as acetic, propionic, butyric, tartaric, maleic, hydroxymaleic, fumaric, maleic, citric, lactic, mucic, gluconic, benzoic, succinic, adipic, oxalic, phenylacetic, methanesulphonic, toluenesulphonic, benezenesulphonic, salicyclic sulphanilic, aspartic, glutamic, edetic, stearic, palmitic, oleic, lauric, pantothenic, tannic, ascorbic, fendizoic, 4-4'-methylenebis-3-hydroxy-2 -naphthoic acid, o-(p- hydroxybenzoyl)benzoic, 4'-4"-dihydroxytriphenylmethane-2-carboxylic acid and valeric acids. Base salts include, but are not limited to, those formed with pharmaceutically acceptable cations, such as sodium, potassium, lithium, calcium, magnesium, ammonium and alkylammonium. Basic nitrogen-containing groups may be quaternised with such agents as lower alkyl halide, such as methyl, ethyl, propyl, and butyl chlorides, bromides and iodides or dialkyl sulfates such as dimethyl and diethyl sulfate.

The compounds of the invention may be in crystalline form either as the free compounds or as solvates and it is intended that both forms are within the scope of the present invention. The term "solvate" refers to a complex or aggregate formed by one or more molecules of a solute, ie compounds contemplated by the invention, and one or more molecules of a solvent. Suitable solvents are well understood in the art and include for example, of water, ie to form hydrates, and common organic solvents such as alcohols (methanol, ethanol, isopropanol) and acetic acid. Methods of solvation are generally known within the art, for example, recrystallization from an appropriate solvent.

Compounds of Formula (I) may be purchased from commercial sources or prepared using methods known and analogous to those described in the art for the preparation of benzimidazolones, such as described in British Patent No. 1363 735, United States Patent No. 6,624,186 and European Patent No. 526 434 and the references cited therein. It will be recognised that during the processes for the preparation of compounds contemplated by the present invention, it may be necessary or desirable to protect certain functional groups which may be reactive or sensitive to the reaction or transformation conditions undertaken

(e.g. OH (including diols), NH , CO2H, SH, C=O). Suitable protecting groups for such functional groups are known in the art and may be used in accordance with standard practice. As used herein, the term "protecting group", refers to an introduced functionality which temporarily renders a particular functional group inactive under certain conditions. Such protecting groups and methods for their installation and subsequent removal at an appropriate stage are described in Protective Groups in Organic Chemistry, 3rd Edition, T.W.Greene and P. G. Wutz, John Wiley and Sons, 1999, the entire contents of which are incorporated herein by reference. Exemplary forms of protected groups include:

for amino (NH2) - carbamates (such as Cbz, Boc, Fmoc), benzylamines, acetamides (e.g. acetamide, trifluoroacetamide); for carbonyl - acetals, ketals, dioxanes, dithianes, and hydrazones; for hydroxy —ethers (e.g. alkyl ethers, alkoxylalkyl ethers, allyl ethers, silyl ethers, benzyl ethers, tetrahydropyranyl ethers), carboxylic acid esters, acetals (e.g. acetonide and benzylidene acetal); for thio (SH) -ethers (e.g. alkyl ethers, benzyl ethers), esters; and

for CO2H - esters (e.g. alkyl esters, benzyl esters).

Therefore, in a further aspect, the present invention provides a method for decreasing dopaminergic cells in a site having an elevated level of dopamine, the method comprising administering a SK specific antagonist, thereby decreasing the number of dopaminergic cells.

In a related aspect, the administration of SK channel specific antagonists results in a loss of dopaminergic cells, such as neurons, in the site of the brain having enhanced levels of dopamine. In a further aspect, a method for decreasing the number of dopaminergic cells is provided, the method comprising administering to a subject an SK channel antagonist. Examples of SK channel antagonists include, tamapin, apamin, UCL 1848, leiurotoxin, UCL 1684, PO5, Leu-Dab7, Tsk, dequalinium, NS8593, UCL 1407, atracurium, tubocurarine, pancuronium, N-methyl-laudanosine, trifluperazine, bicuculline methiodide, gallamine, chlorpromazine, carbamazepine, cyproheptadiene, imipramine, tacrine, armitryptyline, 4- AP, decamethonium, hexamethonium and TEA.

In a related aspect, there is provided a method for treating a disease or disorder associated with enhanced levels of dopamine, the method comprising administering to a subject a GABAA agonist or antagonist.

GABAA agonists contemplated for use in the methods and compositions of the present invention include, without being limited to, gaboxadol, isoguvacine, isonipecotic acid, muscimol, CL-2 18,872 (highly αl -selective agonist), bretazenil (subtype-selective partial agonist), QH-ii-066 (full agonist highly selective for α5 subtype) , THIP, GABA, and β- alanine.

GABAA antagonists contemplated for use in the methods and compositions of the present invention include, without being limited to, bicuculline, gabazine, SR-95531, SR-95103, TPMPA, picrotoxin and pentylenetetrazol.

In a further aspect, there is provided a method for treating a disease or disorder associated with enhanced levels of dopamine, the method comprising administering to a subject a L- type voltage-activated calcium channel agonist or antagonist.

L-type voltage-activated calcium channel agonist contemplated for use in the compositions and methods of the present invention include BayK8644, elocalcitol, FPL-64176 and Dehydrodidemnin B. L-type voltage-activated calcium channel antagonist contemplated for use in the compositions and methods of the present invention include isradipine, dihydropyridines, phenylalkylamines,benzothiaza ρines and calcicludines.

In another aspect, the agent is an antagonist of voltage-activated calcium (Cay) channels including Caγ l.1 (also known as αl S or L-type), Caγ l.2 (also known as αl C or L-type), Cavl.3 (also known as αlD or L-type), Caγ l.4 (also known as αlF or L-type), Caγ2.1 (also known as αlA or P/Q-type), Caγ2.2 (also known as αlB or N-type), Caγ2.3 (also known as αl E or R-type), Caγ3.1 (also known as αl G or T-type), Caγ3.2 (also known as αlH or T-type), Caγ3.3 (also known as all or T-type). Such agents include, without being limited to, amlodipine besylate, cilnidipine, diltiazem hydrochloride, isradipine, loperamide hydrochloride, nifedipine, niguldipine hydrochloride, nimodipine, nitrendipine, SR33805 and verapamil hydrochloride, ω-Conotoxin GVIA, ω-Conotoxin MVIIC, Mibefradill dihydrochloride, NNC 55-0396 dihydrochloride, Ruthenium Red and their pharmaceutically acceptable salts and derivatives thereof.

In another aspect, the agent is an agonist of voltage-activated calcium (Cay) channels including Caγ l.1 (also known as αl S or L-type), Ca l.2 (also known as αl C or L-type), Cavl.3 (also known as αlD or L-type), Caγ l.4 (also known as αlF or L-type), Caγ2.1 (also known as αlA or P/Q-type), Caγ2.2 (also known as αlB or N-type), Caγ2.3 (also known as αl E or R-type), Caγ3.1 (also known as αl G or T-type), Caγ3.2 (also known as αlH or T-type), Caγ3.3 (also known as all or T-type). Such agents include, without being limited to, Bay K8644, dihydropyridine, nifedipine and FPL-64176.

In a related aspect, the agents used in the methods of the present invention include agonists specific for ATP-sensitive potassium (KATP) channels. Such agents include, without being limited to, cromakalim, diazoxide, glimepiride, levcromakalim, minoxidil, nicorandil, P1075, pinacidil, Y-26763, Y-27152 and ZM 226600, and their pharmaceutically acceptable salts or derivatives thereof. In a related aspect, the agents of the present invention include antagonists specific for ATP-sensitive potassium (KATP) channels. Such agents include, without being limited to, gyburide, tetraphenylphosphonium, 5-Hydroxydecanoate (5-HD), glibenclamide and imidazolines.

In another aspect, the agents of the present invention also include agonists specific for G- protein coupled inwardly rectifying potassium (GIRK) channels. Such an agents includes, without being limited to, tenidap, and its pharmaceutically acceptable salts or derivatives thereof.

In another aspect, the agents of the present invention also include antagonists specific for G-protein coupled inwardly rectifying potassium (GIRK) channels. Such agents include, without being limited to, delta-opioid receptor antagonists and tertiapin-Q.

In yet another aspect, the agents of the present invention are antagonists specific for glutamate receptors. Examples of glutamate receptors include, without being limited to, AMPA, Kainate, NMDA, Group I metabotropic, Group II metabotropic and Group III metabotropic glutamate receptors.

In yet another aspect, the agents of the present invention are agonists specific for glutamate receptors. Such agents include, without being limited to, 3,5-dihydroxyphenylglycine, eglumegad, Biphenylindanone A, DCG-IV and L-AP4.

In still a further aspect, the agents of the present invention include agonists specific for kainate receptors. Such agents include, without being limited to, ATPA, domoic acid, 5- lodowillardiine, kainic acid and SYM 2081, and their pharmaceutically acceptable salts or derivatives thereof.

In still a further aspect, the agents of the present invention include antagonists specific for kainate receptors. Such agents include, without being limited to, ACET, CNQX, DNQX and Philanthotoxin. In another aspect, the agents of the present invention include antagonists specific for AMPA/kainate receptors. Such agents include, without being limited to, CNQX, DNQX Evans blue, NBQX, SYM 2206, UBP 282 and ZK 200775 and their pharmaceutically acceptable salts or derivatives thereof.

In another aspect, the agents of the present invention include agonists specific for AMPA/kainate receptors. Such agents include, without being limited to, CIP-A, Cyclothiazide, (±)-AMPA hydrobromide, L-(+)-2-Amino-6~phosphonohexanoic acid, ATPA, Domoic acid, Quisqualic acid and Kainic acid.

In an additional aspect, the agents of the present invention encompass antagonists specific for NMDA receptors, such as AP5, AP7, 4-carboxyphenylglycine, CPG 37849, CPG 39551, CGS 19755, chlorpheg, co 101244 hydrochloride, CCP, CPP-ene, LY 235959, PMPA, PPDA, PPPA, Ro 04-5595 hydrochloride, Ro 25-6981 maleate, SDZ 220-040, SDZ 220-581, ACBC, CGP 78608 hydrochloride, 7-Chlorokynurenic acid, CNQX, 5,7- dichlorokynurenic acid, felbamate, gavestinel, HA-996, L-689,560, L-701,252, L-701,324, l-(l,2-diphenylethyl)piperidine 1, IEM 1460, loperamide hydrochloride, memantine hydrochloride, norketamine hydrochloride, remacemide hydrochloride, arcaine sulphate, eliprodil, N-(4-hydroxyphenlacetyl)spermXXX, N-(4-hydroxyphenlacetyl)spermXXX, ifenprodil hemitartrate and synthalin sulfate, and their pharmaceutically acceptable salts or derivatives thereof.

In an additional aspect, the agents of the present invention encompass agonists specific for NMDA receptors. Such agents include, without being limited to, L-aspartic acid, ibotenate, glutamate, aspartate, D-serine and N-phthalamoyl-L-glutamic acid.

In still further aspects, the agent is an antagonist specific for Group I metabotrophic glutamate receptors. Such agents include, without being limited to, ACDPP hydrochloride, AIDA, AP3, Bay 36-7620, 3-Carboxy-4-hydroxy ρhenylglycine, 4-Carboxy-3- hydroxyphenylglycine, 4-Carboxyphenylglycine, CPCCOEt, E4CPG, Fenobam, HexylHBO, JNJ 16259685, LY 367385, 3-MATIDA, MCPG, MPEP hydrochloride,

MPMQ hydrochloride, PHCCC5 SIB 1757, SIB 1893, YM 298198 hydrochloride, Desmethyl-YM 298198, DMeOB and ACPT-II, and their pharmaceutically acceptable salts or derivatives thereof.

In still further aspects, the agent is an agonist specific for Group I metabotrophic glutamate receptors. Such agents include, without being limited to, 3,5-dihydroxyphenylglycine, L- glutamate, ibotenic acid and CHPG.

In yet another aspect, the agent is an antagonist specific for Group II metabotrophic glutamate receptors. Such agents include, without being limited to, APICA, E4CPG,

EGLU, LY 341495, MCPG 5 MSPG and MTPG, and their pharmaceutically acceptable salts or derivatives thereof.

In yet another aspect, the agent is an agonist specific for Group II metabotrophic glutamate receptors. Such agents include, without being limited to, DCG-IV, (S)- and (R)-2-Amino- 4-(4-hydroxy[l,2,5]thiadiazol-3-yl)butyric Acid, L-glutamate, (1S,3S)-1- aminocyclopentane-1, 3-dicarboxylate ((I S,3S)-ACPD) and (2S, I 1R, 2'R, 3'R)-2-(2',3'- dicarboxy cyclopropyl)glycine (DCG-IV) .

In another aspect, the agent is an antagonist specific for Group III metabotrophic glutamate receptors. Such agents include, without being limited to, CPPG, LY 341495, MAP4, MPPG, MSOP, MSPG and UBPl 112, and their pharmaceutically acceptable salts or derivatives thereof.

In another aspect, the agent is an agonist specific for Group III metabotrophic glutamate receptors. Such agents include, without being limited to, L-AP4, L-glutamate and ACPR-I .

In a related aspect, the agent is an antagonist specific for nicotinic acetylcholine (Ach) receptors, including, DMAB-anabaseine dihydrochloride, Benzoquinonium dibromide, alpha-Bungarotoxin, Chlorisondamine diiodide, Dihydro-beta-erythroidine hydrobromide, Methyllycaconitine citrate, MG 624, Pancuronium dibromide, TMPH hydrochloride and Catestatin, and their pharmaceutically acceptable salts or derivatives thereof.

In a related aspect, the agent is an agonist specific for nicotinic acetylcholine (Ach) receptors. Such agents include, without being limited to, dimethylphenylpiperazinium (DMPP), nicotine, epibatidine, suxamethonium, varenicline and choline.

In a further aspect, the agent is an antagonist specific for muscarinic acetylcholine (Ach) receptors. Such agents include, without being limited to, AF-DX 116, AF-DX 384, AQ- RA 741, 4-DAMP, DAU 5884 hydrochloride, Dimethindene maleate, Ipratropium bromide, J 104129 fumarate, Nitrocaramiphen hydrochloride, PD 102807, Pirenzepine dihydrochloride, Scopolamine hydrobromide, Telenzepine dihydrochloride, Tropicamide, W-84 dibromide and Zamifenacin fumarate, and their pharmaceutically acceptable salts or derivatives thereof.

In a further aspect, the agent is an agonist specific for muscarinic acetylcholine (Ach) receptors. Such agents include, without being limited to, acetylcholine, oxotremorine, muscarine, carbachol, McNA343, and methacholine.

The amount of agent used is an effective amount meaning it is used in an amount effective to modulate neuronal excitability.

The amount of agent administered means an amount necessary to at least partially attain the desired physiological effect or to delay the onset or inhibit progression or halt altogether the onset or progression of a particular dopamine related condition of the subject to be treated, the taxonomic group of the individual to be treated, the degree of protection desired, the assessment of the medical situation, and other relevant factors. It is expected that the amount will fall in a relatively broad range that can be determined through routine trials. In particular, as indicated above, the amount of agent includes an amount which ameliorates at least to some extent symptoms of a neurological condition, especially neurological conditions associated with an abnormal level of dopamine such as a dopamine deficiency or elevation in dopamine levels.

Particular agents which modulate neuronal excitability include agents which act upon channels and receptors expressed on neuronal cells to directly alter the level of excitability of the neuron. Conversely, the agent may act indirectly to modulate the level of excitability of the neuron by initiating a cascade of cellular events, the downstream effects of which result in a change in neuronal excitability.

As used herein, the terms "treating" or "treatment" encompass the administration of an agent which modulates neuronal excitability to a subject having a neurological disease or disorder and/or which results in an amelioration or decrease in one or more of the symptoms associated with a neurological condition.

In one aspect, the terms "treating" or "treatment" encompass the administration of an agent which modulates neuronal excitability, thereby increasing levels of dopamine, to a subject having a neurological disease or disorder and/or which results in the amelioration or decrease in one or more symptoms associated with a neurological condition associated with decreased levels of dopamine. Such symptoms may include, for example, resting tremor, rigidity, bradykinesia, postural instability, physical fatigue, overt fatigue and lethargy, negative behavioral feelings, concentration deficit, weight gain, addictive behavior and reduced libido and/or impotence, depression, alcoholism and ADHD. Treatment may also include the regeneration, generation, recruitment or migration of dopaminergic neurons and in particular neurons within the substantia nigra pars compacta (SNc).

In a further aspect, the terms "treating" or "treatment" encompass the administration of an agent which modulates neuronal excitability, thereby decreasing levels of dopamine, to a subject having a neurological disease or disorder and/or which results in the amelioration or decrease in one or more symptoms associated with a neurological condition associated with elevated levels of dopamine. The term "prevention" as used herein may refer to a delay in the onset of physical manifestations of a disease associated with abnormal levels of dopamine. Prevention may also include a decrease or delay in the onset of pathology associated with a syndrome associated with abnormal levels of dopamine, such as depigmentation of the substantia nigra and intracellular inclusion bodies.

"Dopamine deficiency" is defined as a decrease in levels of dopamine compared to controls. Dopamine deficiency may be measured via either direct measurements of dopamine levels in a subject, or by the onset or presence of symptoms associated with a dopamine deficiency.

"Enhanced levels of dopamine" is defined as an increase in levels of dopamine compared to controls. Enhanced levels of dopamine may be measured via either direct measurements of dopamine levels in a subject, or by the onset or presence of symptoms associated with enhanced levels of dopamine.

The term "subject" as used herein refers to an animal, particularly a mammal and more particularly a primate including a lower primate and even more particularly, a human who can benefit from the methods of the present invention. A subject may also be referred to as a patient, individual, target person etc. Genetic testing of embryos in utero may also identify subjects at risk of developing a neurological disease or condition. A subject, regardless of whether human, non-human animal or embryo, may be referred to as an individual, subject, animal, patient, host or recipient. The present invention, therefore, has both human and veterinary applications. For convenience, an "animal" specifically includes livestock animals such as cattle, horses, sheep, pigs, camelids, goats and donkeys. With respect to horses, these include horses used in the racing industry as well as those used recreationally or in the livestock industry.

The present invention extends to any subject which is already exhibiting symptoms associated with dopamine deficiency, such as, for example, resting tremor, rigidity, bradykinesia, postural instability, physical fatigue, overt fatigue and lethargy, negative behavioral feelings, concentration deficit, weight gain, addictive behavior and reduced libido and/or impotence, depression, alcoholism and ADHD. In a related aspect, the subject may have a family history, genetic trait or predisposition to the development of a dopamine deficient disease or disorder, and accordingly, may be administered doses of an agent which decreases neuronal cell excitability so as to maintain normal or pre- symptomatic levels of dopamine, or dopaminergic cells, including cells in the SNc.

The present invention also extends to any subject which is already exhibiting symptoms associated with enhanced levels of dopamine.

Examples of laboratory test animals include mice, rats, rabbits, guinea pigs and hamsters. Rabbits and rodent animals, such as rats and mice, provide a convenient test system or animal model, as do primates and lower primates.

The terms "disease", "disorder", "abnormality" may be used interchangeably to refer to a condition characterized by an abnormal level of dopamine produced by the subject.

A decrease or reduction in neuronal excitability refers to increased polarization of a neuron's membrane potential and/or decreased rate of action potential discharge by a neuron and can be measured using several techniques which would be known by one of skill in the art. Such techniques include, without being limited to, inserting the tip of an electrode inside a cell or using a voltage sensitive dye to measure the electrical potential difference between the inside and outside of the cell (i.e. potential across the membrane), placing the tip of an electrode outside but near to a cell to measure its rate of action potential discharge.

An increase in neuronal excitability refers to decreased polarization of a neuron's membrane potential and/or increased rate of action potential discharge by a neuron and can be measured using several techniques which would be known by one of skill in the art. Such techniques include, without being limited to, inserting the tip of an electrode inside a cell or using a voltage sensitive dye to measure the electrical potential difference between the inside and outside of the cell (i.e. potential across the membrane), placing the tip of an electrode outside but near to a cell to measure its rate of action potential discharge.

As used herein, the term "neuronal cell" refers to a cell of the nervous system which is electrically excitable. In another aspect, the neuron is selected from dopaminergic cells, or precursors thereof. Dopaminergic cells are cells that can synthesize the neurotransmitter dopamine. Dopaminergic precursor cells are cells that have the potential to synthesize the neurotransmitter dopamine. Dopamine precursor cells express dopaminergic developmental markers including, but not limited to, Lmxlb, Pitx-3, Engrailed 1 & 2 and/or Nurr-1. Dopaminergic precursor cells may also be mature cells expressing neurotransmitters other than dopamine that can be induced to express dopamine. Such cells include, but are not limited to, catecholamine (adrenaline, noradrenaline) producing cells and GABA producing cells. In one aspect, the neurons or dopaminergic neurons are in the SNc.

The present invention is further directed to a method for increasing dopamine production in a neuron by modulating the excitability of the neuron. In one aspect, the dopamine production may be increased in any part of the brain. In a related aspect, dopamine production is increased in dopaminergic neurons. In a further aspect, the dopaminergic neurons are within the SNc, Hippocampus, Cerebral cortex, Ventral tegmental nucleus (AlO), Retrorubral field (A8), Retina, Hypothalamus, Olfactory bulb, Preoptic areas, Tuberohypophyseal, Incertohypothalamic, and Medullary periventricular area.

Hence the present invention extends to a method for facilitating dopamine production in a subject or within particular neurons in a subject, the method comprising administering to the subject an effective amount of an agent which modulates neuronal excitability. Particular neurons include neurons within the SNc. The present invention further contemplates a method for ameliorating the symptoms of dopamine deficiency in a subject, the method comprising administering to the subject an effective amount of an agent which modulates neuronal excitability.

Also contemplated by the present invention is a method for treating a dopamine deficient disease or disorder comprising administering an agent which modulates neuronal excitability in conjunction with one or more of levodopa, carbidopa, benserazide, co- careldopa, sinemet, parcopa, co-beneldopa, madopar, duodopa, tolcapone, entacapone, bromocriptine, pergolide, pramipexole, ropinirole, cabergoline, apomorphine, lisuride, selegiline and rasagiline. Combination therapy may also be in conjunction with behavioural modification protocols for subjects suffering from diseases or disorders, especially those which have a dopamine deficiency component.

The present invention is further directed to a method for decreasing dopamine production by modulating the excitability of the neuron. In one aspect, the dopamine production may be decreased in any part of the brain. In a related aspect, dopamine production is decreased in dopaminergic neurons. In a further aspect, the dopaminergic neurons are within the SNc, Hippocampus, Cerebral cortex, Ventral tegmental nucleus (AlO), Retrorubral field (A8), Retina, Hypothalamus, Olfactory bulb, Preoptic areas, Tuberohypophyseal, Incertohypothalamic, and Medullary periventricular area,

Hence, the present invention extends to a method for reducing dopamine production in a subject or within particular neurons in a subject, the method comprising administering to the subject an effective amount of an agent which modulates neuronal excitability. Particular neurons include neurons within the SNc.

The present invention further contemplates a method for ameliorating the symptoms of enhanced levels of dopamine in a subject, the method comprising administering to the subject an effective amount of an agent which modulates neuronal excitability. Also contemplated by the present invention is a method for treating a disease or disorder associated with enhanced levels of dopamine comprising administering an agent which modulates neuronal excitability in conjunction with one or more of known drugs which are used to treat diseases or disorders associated with enhanced levels of dopamine. Combination therapy may also be in conjunction with behavioural modification protocols for subjects suffering from diseases or disorders, especially those which have an enhanced level of dopamine.

By "in-conjunction" is meant simultaneous administration in the same formulation or in two different formulations via the same or different routes or sequential administration by the same or different routes. The term "in conjunction" also includes the use of two or more agents in the same therapeutic protocol. By "sequential" administration is meant a time difference of from seconds, minutes, hours or days between the administration of the two types of molecules. These molecules may be administered in any order.

As used herein "administering" or "administration" of an agent refers to the delivery of an agent to a desired area of the subject. In a particular aspect, the agents of the present invention are administered directly to the area of the brain where the neurons in a normal subject produce normal levels of dopamine. These levels would be sufficient to maintain dopamine at levels which prevent the onset of signs or symptoms of disease which are indicative of the development of abnormal levels of dopamine. Such signs or symptoms include, without being limited to, Bradykinesia, loss of postural reflexes, tremor, rigidity, autonomic failure, sleep disturbance, disturbed impulse control. In addition, pre-clinical signs or pathology may be prevented or diminished. Such pre-clinial signs include Lewy bodies in susceptible neurons from regions including the SNc, the gut, locus ceruleus and cerebral cortex in addition to loss or death of neurons in these areas.

Conveniently, the amelioration of symptoms of a neurological condition, and in particular a neurological condition associated with abnormal levels of dopamine is relative to a control subject. A control subject may be a subject to which an agent described herein is not administered or to whom a placebo is administered or a subject which produces abnormally low levels of dopamine which are associated with one or more of the typical symptoms of dopamine deficiency or enhanced levels of dopamine.

Delivery of the agents may be via any mechanism which allows the agent to cross the blood brain barrier (BBB)5 so as to deliver the agent to those cells or areas in the brain in which dopamine production would treat or prevent the onset of a dopamine deficient disease or disorder. Agents may also be conjugated to targeting moieties to target particular areas of the brain or particular cells within the brain.

Such delivery methods include, without being limited to, disruption of the BBB, either by osmotic means or biochemically by the use of vasoactive substances such as bradykinin. For example, systemic delivery of an SK agonist together with bradykinin or a bradykinin B agonist.

Also contemplated as a means for delivering the agents of the present invention across the BBB is the use of endogenous transport systems, including carrier mediated transporters such as glucose and amino acid carriers; receptor-mediated transcytosis; active efflux transporters and retrograde transport.

Also available are chemistry based strategies relying on lipid-mediated drug transport.

In addition, lipophilic and hydrophobic molecules of low molecular weight which cross the BBB can also be used to transport the agents of the present invention to the brain.

Also contemplated is the delivery of agents using the olfactory and trigeminal pathways to the brain. The neural connections between the nasal mucosa and the brain provide a unique pathway for noninvasive delivery of therapeutic agents to the central nervous system, including the brain.

The olfactory neural pathway provides both intraneuronal and extraneuronal pathways into the brain. The intraneuronal pathway involves axonal transport and requires hours to days for drugs to reach different brain regions. The extraneuronal pathway relies on bulk flow transport through perineural channels which deliver drug directly to the brain parenchymal

tissue or to the cerebrospinal fluid (CSF)5 or to both. This extraneuronal pathway allows therapeutic agents to reach the brain within minutes. Intranasal delivery of agents to the CSF is, therefore, contemplated.

Using intranasal delivery, it has been demonstrated that peptides/proteins, DNA plasmids, small molecules can be delivered to the brain.

Also contemplated as delivery means are invasive and pharmacological methods. Invasive delivery strategies include, for example, mechanical procedures, such as implantation of an intraventricular catheter, followed by pharmaceutical infusion into the ventricular compartment.

Another invasive strategy for delivering therapeutic compounds to the central nervous system is by intracartoid infusion of highly concentrated osmotically active substances, such as mannitol or arabinose. Their high local concentration causes shrinkage of capillary endothelial cells in the vasculature of the brain, resulting in a transient opening of the tight junctions which enable molecules to traverse the BBB.

Another pharmacological method for delivering the subject agents across the BBB is to covalently couple the agent to a peptide for which a specific receptor-mediated transcytosis system exists. For example, it is possible to attach an agent of the present invention to insulin to be transported across the BBB by insulin receptor-mediated transcytosis. Upon entry into the brain interstitial space, the agent is then released from the transport vector (insulin) to interact with its own receptor. Other methods include, for example, coupling the agent to a monoclonal antibody specific for a marker present on the surface of a target cell population. For example, the agent could be coupled to a monoclonal antibody to the transferrin receptor. Also contemplated by the present invention are methods of treating a disease or disorder associated with a dopamine deficiency by modifying the neuronal cells, either in vivo or ex vivo, to increase the expression of one or more of SK channels, KATP channels, GIRK channels, GABA receptors, or decrease the level of expression of voltage-activated calcium channels, glutamate receptors, nicotinic ACh receptors and/or muscarinic ACh receptors.

Further contemplated by the present invention are methods of treating a disease or disorder associated with enhanced levels of dopamine by modifying the neuronal cells, either in vzvo or ex vivo, to decrease the expression of one or more of SK channels, KATP channels, GIRK channels, GABA receptors, or increase the level of expression of voltage-activated calcium channels, glutamate receptors, nicotinic ACh receptors and/or muscarinic ACh receptors.

Methods suitable for increasing the level of expression include, a nucleic acid molecule specific for one of the channels or receptors defined herein may be ligated to an expression vector capable of expression in a prokaryotic cell (e.g. E.colf) or a eukaryotic cell (e.g. yeast cells, fungal cells, nsect cells, mammalian cells or plant cells). The nucleic acid molecules may be ligated or fused or otherwise associated with a nucleic acid molecule encoding another entity such as, for example, a nucleic acid molecule which is specific for a neuronal marker. It may also comprise additional nucleotide sequence information fused, linked or otherwise associated with it either at the 3' or 5' terminal portions or at both the 3' and 5' terminal portions. The nucleic acid molecule may also be part of a vector such as an expression vector.

Methods suitable for decreasing the expression of a gene associated with, for example, a particular channel or receptor include the use of sense and anti-sense molecules, single- stranded and double-stranded RNA molecules, RNAi, neutralizing antibodies, or the like. Also contemplated by the present invention is the use of an agent which modulates neuronal excitability in the manufacture of a medicament for the treatment of a neurological disease or disorder associated with abnormal levels of dopamine.

Use of an agent which modulates neuronal excitability in the manufacture of a medicament for the treatment of a disease or disorder associated with a dopamine deficiency is also contemplated. Such agents include, for example, SK channel agonists.

In a particular aspect, the present invention is directed to the use of an agent which modulates neuronal excitability in the manufacture of a medicament for treating Parkinson's Disease. Such agents include, for example, SK channel agonists.

Further contemplated by the present invention is the use of an agent which modulates neuronal excitability in the manufacture of a medicament for the treatment of a neurological disease or disorder associated with enhanced levels of dopamine. Such agents include, for example, SK channel antagonists, GABAA receptor agonists and antagonists and L-type calcium activated agonists or antagonists,

Use of an agent which modulates neuronal excitability in the manufacture of a medicament for the treatment of a disease or disorder associated with enhanced levels of dopamine is also contemplated.

In a particular aspect, the present invention is directed to the use of an agent which modulates neuronal excitability in the manufacture of a medicament for treating Schizophrenia. Such agents include, for example, SK channel antagonists, GABAA receptor agonists and antagonists and L-type calcium activated agonists or antagonists.

The present invention is further described by the following non-limiting Examples. Materials and methods described below are used in the Examples. (a) Animals and animal models

All animals used for experiments were age-matched (8 week old), male, C57BL6J mice. All mice were housed in standard mouse boxes. They were kept in a constant 12 hour light-dark cycle (light 7am to 7pm). Standard laboratory mouse chow and water were available to mice ad libitum.

(i) Animal models

Animal models of Parkinson's disease involve administering one of a number of different neurotoxins that selectively injure or kill dopamine neurons in the substantia nigra pars compacta (SNc) of the brain. Conveniently, animals of choice include mice, rats and monkeys. Neurotoxins include 6-hydroxy-dopamine (6-OHDA), l-methyl-4-phenyl- 1,2,3,6-tetrahydropyridine (MPTP) and the insecticide/piscicide/pesticide rotenone. These neurotoxins are delivered systemically or by direct injection into the brain.

(ii) In vitro models

Dopamine neurons are grown in a dish in the laboratory from cells that have been isolated from the brain or other regions of the body. These dopamine cell cultures can also be exposed to the above neurotoxins to cause death or injury to dopaminergic cells.

(b) Drug delivery

Drugs (or vehicle) were infused directly into the substantia nigra pars compacta (SNc) on the left side of the brain using a micro-osmotic pump attached to a brain infusion kit (an example is ALZET [reg trade mark] Model 1002), e.g. Figure IA. The brain infusion kit comprised a length (2-3cm) of l mm inner diameter polyethylene tubing attached to a stainless steel cannula, the tip of which was implanted in the SNc (see Surgery section below), e.g. Figure IB. The pump system delivered the drug solution constantly at a rate of ~0.25µl per hour for 14 days. (c) Surgery

The micro-osmotic pump and attached brain infusion kit were prefϊ lled with drug solution (Table 1) one day before surgery and incubated overnight in sterile physiological saline solution at 370C to ensure they were delivering the drug at the time of implantation. Mice were anaesthetized with 0.1 ml/1 Og body weight chloral hydrate (5% w/v in sterile PBS) and placed in a stereotaxic headframe. The skin overlying the SNc was incised and retracted and a 2mm diameter hole was drilled in the skull at stereotaxic coordinates Bregma -3mm, lateral 1.5mm (left side of the brain). The cannula was inserted vertically into the brain through this hole to a depth of 4mm below the brain's surface and glued to the skull with dental cement. The osmotic pump attached to the cannula was inserted into a subcutaneous pocket created in the mid-scapular regions of the animal's back. The skin was then sutured over the pump, cannula and connecting polyethylene tubing. The animal was removed from the frame, given analgesic (Meloxicam, 3 mg/kg s.c.) and placed under a heat-lamp until it recovered from the anaesthetic.

(d) Agents

TABLE 1 (e) Immunohistochemistry

After 2 weeks of drug infusion, animals were given an overdose of anesthetic (Lethabarb) and intracardially perfused with heparinized phosphate buffered saline (PBS) at 37°c followed by 4% v/v paraformaldehyde (1.15ml x body weight in grams). Brains were removed and placed in 30% v/v sucrose in PBS for 2-3 days. Frozen coronal sections (16µm) were cut serially through the SNc on both sides of the brain with a cryostat, mounted on gelatinized microscope slides and stored at -80°C.

Dopamine neurons within the SNc were identified using tyrosine hydroxylase (TH) immunohistochemistry, e.g. Figures IB,C. Mounted slides were incubated in 10% formalin for 2 min and then in a blocking solution of 3% v/v normal goat serum (NGS), Triton X- 100 and PBS for 30 min. Sections were then incubated for 48 hrs at 4°c in mouse anti-TH primary antibody (Chemicon, 1:1500 in NGS, Triton X-100, PBS). This was followed by incubation in a biotinylated secondary antibody (DAKO, goat, anti-rabbit IgG, 1:1000) for 2 hrs at room temperature and in 1:5000 avidin peroxidase (Sigma) for 1 hr. Finally, sections were incubated for 20 min with cobalt and nickel intensified 3, 3 diaminobenzidine tetrahydrochloride (DAB). Hydrogen peroxide (3.0% v/v, 3.3 µL/mL) was added to the DAB solution for a further 5 min. Washes (3 x 5 min) in PBS were performed between each step. Sections were then counterstained with neutral red (10 min), dehydrated in a series of alcohol solutions (50-100% ethanol), cleared (X-3B) and coverslipped.

(f) Estimation of the total number of TH-positive and TH-negative neurons in SNc

The SNc was identified by the spatial distribution of TH-positive cells together with clear anatomical landmarks/boundaries which separate TH-positive cells in SNc from those in surrounding nuclei (i.e. ventral tegmental area (VTA) and retrorubral field (A8)). TH- positive and TH-negative neurons within SNc were identified by the presence and absence of TH immunoreactivity, respectively (Figure 1C). Only neurons were counted, glial cells were excluded on the basis of soma size. Cell numbers were estimated using an unbiased stereological method. Briefly, a counting frame (45 x 35 µm = 1575 µm2) was randomly positioned within the boundaries of SNc and the numbers of TH-positive and TH-negative neurons within this frame were counted. The frame was then moved a regular, predetermined interval (x = 140 µm, y = 140 µm), derived by means of a grid program (Stereo Investigator, MicroBrightField, VT, USA), within SNc and the numbers of cells counted again. This was repeated many times throughout the 3 dimensional extent of SNc. The total numbers of TH-positive and TH-negative neurons in SNc were calculated from this unbiased sample. (g) Data analysis

The mean and standard error of the total number of TH-positive and TH-negative neurons in SNc by treatment were calculated. Statistical comparisons (t-tests) were made between each drug and its vehicle control.

(h) Results

Neuronal excitability regulates the number of TH+ SNc cells

Membrane potential changes in SNc DAergic neurons are driven by membrane conductances (ion-channels or receptors) that can be broadly categorized as either "intrinsic" or "extrinsic". Intrinsic conductances drive membrane potential in the absence of influence from other cells. For example, the spontaneous pacemaker oscillations (~3- 5Hz) in the membrane potential of SNc DAergic neurons persist even after all extrinsic cellular influences have been removed. This pacemaker activity is mostly driven by interplay between Ca2+ entry through voltage-activated Ca2+ channels (T-, L-, and P/Q- type, and small-conductance, Ca2+-activated potassium (SK) channels. Each depolarizing phase usually evokes a single Na action potential resulting in the characteristic tonic discharge of these neurons. On the other hand extrinsic conductances are driven by stimuli extrinsic to the cell, most notably synaptic conductances, which, on SNc DAergic neurons, are mostly inhibitory or GABAergic (60-80%) rather than excitatory or glutamatergic.

It has been demonstrated that chronic (2-week) pharmacological manipulations of SK channels on SNc neurons in 8-week old mice alter the numbers of TH+ and TH- SNc cells in a manner consistent with bidirectional changes in TH expression in these cells. Specifically, SK channel agonists (1-EBIO or riluzole) resulted in more TH+ and less TH- SNc cells, without changing the total number of cells (TH+ & TH- combined). On the other hand, an SK channel antagonist (apamin) resulted in less TH+ and more TH- SNc cells, again with no net change in total number of cells. These data have been plotted in Figure ID for comparison. A correlation between the excitability (rate of action potential discharge) of SNc neurons and TH expression was also shown. Thus, it was unclear whether these changes were due to altered SK channel function per se, or to its downstream effects on neuronal excitability. If neuronal excitability was responsible, modulating ion-channels or receptors other than SK channels ought to also alter the numbers of TH+ and TH- SNc cells or TH expression in these cells.

L-type voltage-activated Ca2+ channel drugs were infused directly into SNc for 2 weeks. Infusion of the L-type Ca2+ channel agonist FPL64176 (10OnM, Tocris) resulted in a similar effect to SK channel inhibition. The number of TH+ SNc cells decreased by -14% (-750 cells less than the -5500 TH+ cells present in vehicle-infused mice) and the number of TH- SNc cells increased by an equal amount (Figure ID), i.e. an apparent decrease in TH expression to below detectable levels in ~750 cells. While infusion of the L-type Ca2+ channel antagonist nimodipine (lOµM, Tocris) had a similar although much larger effect on the number of TH+ cells, reducing them by -2300 or -40%, there was not an equal but opposite increase in the number of TH- cells. Instead, L-type Ca2+ channel blockade reduced the number of TH- cells by -450 (Figure ID). In other words, L-type Ca2+ channel blockade for 2 weeks depleted both TH+ and TH- SNc cells.

Next altered SNc neuronal excitability was altered independent of any specific ion-channel or receptor by infusing 3OmM K into SNc for 2 weeks. The effect was similar to SK channel inhibition and L-type Ca2+ channel facilitation, namely a decrease in number of TH+ cells (-350) and an increase in number of TH- cells (-350), with no change in total (TH+ & TH-) cell number (Figure ID). In addition, 3OmM K+ infused together with 30OnM apamin (SK antagonist) tended to bring about larger changes in TH+ and TH- SNc cell numbers than 3OmM K+ alone, although this difference was not significant (p = 0.567 (TH+) & p 0.094 (TH-), t-test, Figure ID).

Extrinsic conductances also regulate the number of TH+ SNc cells

The above data suggests that neuronal excitability can regulate the numbers of TH+ and TH- SNc cells, possibly by affecting TH expression in these cells. If this is the case then any ion-channel or receptor affecting SNc cell excitability, including those mediating synaptic input to these cells ("extrinsic" conductances), should also regulate the numbers of TH+ and TH- SNc cells.

This was tested by infusing the GABAA receptor agonist muscimol (20µM, Tocris) into the left SNc for 2 weeks. The number of TH+ cells decreased (-1200) and the number of TH- cells increased (-500), but to a lesser extent, with an insignificant (p>0.01) decrease in the total (TH+ & TH-) number of SNc cells (Figure 2B). The GABA A receptor antagonist picrotoxin (lOOµM, Tocris) also decreased TH+ cells, more so than muscimol (-1800; Figure 2B) but without a concomitant increase in TH- cells; indeed TH- cells decreased by -400 (Figure 2B).

1-EBIO infusion into a mouse model of Parkinson 's disease almost completely restores the normal number of SNc dopaminergic cells

Next, it was tested whether chronic (2 week) infusion of an SK channel agonist, 1-EBIO, into a mouse model of Parkinson's disease would increase the number of SNc dopaminergic cells. Eight-week old mice were administered 6-OHDA into the left SNc, enough to selectively kill -50% of the normal number of SNc dopaminergic cells. Once the cells had died (2 weeks later), vehicle, lOOµM or 200µM 1-EBIO was infused into the left SNc for a further 2 weeks before the mice were killed and the number of SNc dopaminergic cells in the left SNc were compared with those in the right (control) SNc. Vehicle infused mice exhibited a -50% reduction, on average, in number of dopaminergic cells, similar to what occurs in Parkinson's disease patients (figure 3 left column). In contrast, mice infused with 200µM 1-EBIO exhibited only a -20% reduction, on average, in number of dopaminergic cells, which is a statistically significant improvement (figure 3 right column). lOOµM 1-EBIO made no difference, on average, but a few mice showed marked improvement (figure 3 middle column). The ability of a non-specific SK channel agonist, riluzole, to restore the number of SNc dopaminergic cells using the same experimental protocol was also tested. Riluzole has been contemplated for use as a Parkinson's disease therapeutic, but as a neuroprotective agent (i.e. to prevent death of SNc dopaminergic neurons in the first place) as opposed to a neurorestorative agent, as contemplated here. It also has activity on non-SK ion-channels and receptors affecting the excitability of SNc neurons (e.g. voltage-activated sodium channels and NMDA receptors), and as such may not be as effective as more specific SK channel agonists like 1-EBIO. Indeed direct comparison between riluzole and 1-EBIO infusions into SNc in normal mice showed 1-EBIO is indeed more effective than riluzole in increasing the number of SNc dopaminergic cells (figure ID). Systemic administration of 3µM riluzole or 30µM riluzole did not increase the number of SNc dopaminergic cells following their loss in the 6-OHDA mouse model of Parkinson's disease (figure 4).

(i) Summary and conclusions

(1) Chronically inhibiting SK function in SNc neurons for 2 weeks with apamin leads to a decrease in the number of SNc dopaminergic cells. (2) Chronically facilitating SK function in SNc neurons for 2 weeks with 1-EBIO leads to an increase in the number of SNc dopaminergic cells. (3) Chronically facilitating Cayl .1 function in SNc neurons for 2 weeks leads to a decrease in the number of SNc dopaminergic cells.

(4) Chronically inhibiting Cay1.1 function in SNc neurons for 2 weeks leads to a decrease in the number of SNc dopaminergic cells. (5) Chronically increasing SNc neuronal excitability non-specifically (high K+) for 2 weeks, i.e. not via any particular ion-channel or receptor, decreases the number of SNc dopaminergic cells and this effect is additive to that produced via inhibiting SK channels. (6) Chronic local administration of 1-EBIO almost completely restores the normal number of SNc dopaminergic cells in a mouse model of Parkinson's disease. (7) Chronic systemic administration of riluzole does not restore the number of SNc dopaminergic cells in a mouse model of Parkinson's disease. These data show that ion-channels or receptors that alter the excitability of neurons in SNc play a causal role in setting the number of SNc dopamine cells and therefore the amount of dopamine in this part of the brain. Specifically, facilitation of SK channel activity leads to an increase in the number of SNc dopamine cells whereas a decrease in number of SNc dopamine cells results from SK channel inhibition, L-type channel facilitation, L-type channel inhibition, non-specific increase in cell excitability (high K+), GABA A receptor facilitation or GABA A receptor inhibition.

As such, these ion-channels and receptors represent novel therapeutic targets for treating neurological disorders associated with abnormal levels of dopamine. Also, drugs, or their derivatives, that facilitate or inhibit the function of these ion-channels and receptors represent novel therapeutics for treating neurological disorders associated with abnormal levels of dopamine.

The present invention is further described by the following non-limiting Examples. EXAMPLE 1 Alleviation of the motor symptoms of SNc dopamine cell loss in rodent models of Parkinson 's disease

Dopamine neurons, either in vivo or in vitro, are exposed to one of the neurotoxins. After a delay to allow time for dopamine neurons to die, a drug that facilitates SK channel function (e.g. 1-EBIO) is provided to the cells. Following treatment the cells are assayed for expression of tyrosine hydroxylase (TH, a rate limiting enzyme in dopamine synthesis) using a marker for TH (e.g. immunohistochemical).

A rotation assay is used to assay dopamine expression behaviourally (Glick et al Biochem Pharmacol 23(22):3223-5, 1974; Kelly PH Brain Res 100(1) 63-9, 1975; Reavill et al Biochem Pharmacol 32(5):S65-70, 1983; Olds et al Synapse 59(8):532-44, 2006). An animal is injected systemically with amphetamine, which causes SNc neurons to release dopamine, or apomorphine, which is a dopamine receptor agonist. The animal is then placed on the ground and the number of times it rotates left and right are counted. An animal with more dopamine neurons or dopamine receptors on one side of the brain relative to the other will tend to turn one way more than the other and the greater the difference, the more the animal will turn. Therefore, by injecting a neurotoxin directly into SNc on one side of the brain only and later treating that same SNc with the test compound (e.g. 1-EBIO) the ability of that compound to restore SNc dopamine cells and alleviate the symptoms of this cell loss can be assessed. The advantage of this test is rotational behaviour that is monitored in the same animal repeatedly over time.

Those skilled in the art will appreciate that the invention described herein is susceptible to variations and modifications other than those specifically described. It is to be understood that the invention includes all such variations and modifications. The invention also includes all of the steps, features, compositions and compounds referred to, or indicated in this specification, individually or collectively, and any and all combinations of any two or more of said steps or features. BIBLIOGRAPHY

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WO 00/23419 CLAIMS

1. A method of treating or preventing a neurological condition associated with abnormal levels of dopamine, said method comprising administering to a subject a therapeutically effective amount of an agent which modulates neuronal cell excitability.

2. The method according to Claim 1, wherein the neurological condition is a disease or condition associated with dopamine deficiency.

3. The method according to any one of Claim 2, wherein the condition is selected from the group consisting of: Parkinson's Disease (PD), dystonia, Tourettes syndrome, restless legs, certain psychoses, ADHD, cognition disorders, motor control disorders, abnormal lactation, sleep disorders, memory deficit, attention deficit, problem solving deficit, learning deficit, abnormal moods, social disorders, abnormal libido, anhedonia and eating disorders.

4. The method according to Claim 1, wherein the neurological condition is a disease or condition associated with elevated levels of dopamine.

5. The method according to Claim 4, wherein the neurological condition is selected from the group consisting of schizophrenia, drug addiction, obsessive compulsive disorder, mania and certain psychoses.

6. The method according to Claim 1, wherein the agent is an agonist specific for SK channels.

7. The method of Claim 6, wherein the agonist specific for SK channels is selected from the group of chemicals known as NS309, zoxazolamine, chlorzoxazone, and a benzimidazolone or benzothiazole such as EBIO or a derivative thereof as defined by Formula I or pharmaceutically acceptable salts thereof. 8. The method according to any one of Claims 2 to 3 and 6 to 7, wherein the agent is co-administered with an agent used to treat Parkinson's disease.

9. The method according to Claim 8, wherein the agent used to treat Parkinson's disease is selected from the group consisting of: levodopa, carbidopa, benserazide, co- careldopa, sinemet, parcopa, co-beneldopa, niadopar, duodopa, tolcapone, entacapone, bromocriptine, pergolide, pramipexole, ropinirole, cabergoline, apomorphine, lisuride, selegiline, rasagiline.

10. The method according to Claim 1, wherein the agent is an antagonist specific for SK channels.

11. The method of Claim 10, wherein the antagonist specific for SK channels is selected from the group of tamapin, apamin, UCL 1848, leiurotoxin, UCL 1684, PO5, Leu- Dab7, Tsk, dequalinium, NS8593, UCL 1407, atracurium, tubocurarine, pancuronium, N- methyl-laudanosine, trifluperazine, bicuculline methiodide, gallamine, chlorpromazine, carbamazepine, cyproheptadiene, imipramine, tacrine, armitryptyline, 4-AP, decamethonium, hexamethonium and TEA.

12. The method according to Claim 1, wherein the agent is a GABAA receptor agonist or antagonist.

13. The method according to Claim 12, wherein the GABAA receptor agonist is selected from gaboxadol, isoguvacine, isonipecotic acid, muscimol, CL-2 18,872 (highly αl -selective agonist), bretazenil (subtype-selective partial agonist), QH-ii-066 (full agonist highly selective for α5 subtype) , THIP, GABA, and β-alanine.

14. The method according to Claim 12, wherein the GABA A receptor antagonist is selected from bicuculline, gabazine, SR-95531, SR-95103, TPMPA, picrotoxin and pentylenetetrazol. 15. The method according to Claim 1, wherein the agent is an L-type voltage activated calcium channel agonist or antagonist.

16. The method according to Claim 15, wherein the L-type voltage activated calcium channel agonist is selected from BayK8644, elocalcitol, FPL-64176 and Dehydrodidemnin B.

17. The method according to Claim 15, wherein the L-type voltage activated calcium channel antagonist is selected from isradipine, dihydropyridines, phenylalkylamines,benzothiazaρines and calcicludines.

18. Use of an agent which modulates neuronal excitability in the manufacture of a medicament for treating a neurological condition.

19. Use of Claim 18, wherein the neurological condition is associated with dopamine deficiency.

20. Use of Claim 19, wherein in the neurological condition is selected from the group consisting of Parkinson's Disease (PD), dystonia, Tourettes syndrome, restless legs, psychosis, ADHD, cognitive disorders, motor control disorders, abnormal lactation, sleep disorders, memory deficit, attention deficit, problem solving deficit, learning deficit, abnormal mood, social disorders, abnormal libido, anhedonia and eating disorders.

21. Use of Claim 18, wherein the neurological condition is a disease or condition associated with elevated levels of dopamine.

22. Use of Claim 21, wherein the neurological condition is selected from the group consisting of schizophrenia, drug addiction, obsessive compulsive disorder, mania and certain psychoses. 23. Use according to any one of Claims 19 to 20, wherein the agent is an agonist specific for SK channels.

24. Use of Claim 23, wherein the agonist specific for SK channels is selected from the group of chemicals known as NS309, zoxazolamine, chlorzoxazone, and a benzimidazolone or benzothiazole such as EBIO or a derivative thereof as defined by Formula I or pharmaceutically acceptable salts thereof.

25. Use according to any one of Claims 19 to 20 and 23 to 24, wherein the agent is co¬ administered with an agent used to treat Parkinson's disease.

26. Use of Claim 25, wherein the agent used to treat Parkinson's disease is selected from the group consisting of: levodopa, carbidopa, benserazide, co-careldopa, sinemet, parcopa, co-beneldopa, madopar, duodopa, tolcapone, entacapone, bromocriptine, pergolide, pramipexole, ropinirole, cabergoline, apomorphine, lisuride, selegiline, rasagiline.

27. Use according to Claim 18, wherein the agent is an antagonist specific for SK channels.

28. Use of Claim 27, wherein the antagonist specific for SK channels is selected from the group of tamapin, apamin, UCL 1848, leiurotoxin, UCL 1684, PO5, Leu-Dab7, Tsk, dequalinium, NS8593, UCL 1407, atracurium, tubocurarine, pancuronium, N-methyl- laudanosine, trifluperazine, bicuculline methiodide, gallamine, chlorpromazine, carbamazepine, cyproheptadiene, imipramine, tacrine, armitryptyline, 4-AP, decamethonium, hexamethonium and TEA.

29. Use of Claim 18, wherein the agent is a GABAA receptor agonist or antagonist.

30. Use of Claim 29, wherein the GABAA receptor agonist is selected from gaboxadol, isoguvacine, isonipecotic acid, muscimol, CL-21 8,872 (highly αl-selective agonist), bretazenil (subtype-selective partial agonist), QH-ii-066 (full agonist highly selective for α5 subtype) , THIP, GABA, and β-alanine.

31. Use of Claim 29, wherein the GABAA receptor antagonist is selected from bicuculline, gabazine, SR-95531, SR-95103, TPMPA, picrotoxin and pentylenetetrazol.

32. Use of Claim 18, wherein the agent is an L-type voltage activated calcium channel agonist or antagonist.

33. Use of Claim 32, wherein the L-type voltage activated calcium channel agonist is selected from BayK8644, elocalcitol, FPL-64176 and Dehydrodidemnin B.

34. Use of Claim 32, wherein the L-type voltage activated calcium channel antagonist is selected from isradipine, dihydropyridines, phenylalkylamines,benzothiazapines and calcicludines.

35. A method of inducing migration of dopaminergic cells to a site deficient in dopamine producing cells comprising administering a SK specific agonist.

36. A method of recruiting dopaminergic cells to an area deficient in dopamine producing cells comprising administering to a subject a SK specific agonist.

37. A method of stimulating synthesis of dopamine in resident non-dopaminergic cells, such as neurons, comprising the administration of the SK specific agonists.

INTERNATIONAL SEARCH REPORT International application No. PCT/AU2009/001012

A. CLASSIFICATION OF SUBJECT MATTER Int. Cl. A61K 31/4184 (2006.01) A61K 31/4741 (2006.01) A61K 31/198 (2006.01) A61P 25/16 (2006.01) A61P 25/00 (2006.01) According to International Patent Classification (IPC) or to both national classification and IPC

B. FIELDS SEARCHED

Minimum documentation searched (classification system followed by classification symbols)

Documentation searched other than minimum documentation to the extent that such documents are included in the fields searched

Electronic data base consulted during the international search (name of data base and, where practicable, search terms used) DWPI, EPODOC, Medline (neuron, dopaminergic, SK channel (and like terms), SK channel agonist (and specific examples), SK channel antagonist (and specific examples), Parkinson's Disease, dystonia, Tourettes, attention deficit hyperactivity disorder, anhedonia, schizophrenia, drug addiction, OCD, stimulate, migrate, recruit)

C. DOCUMENTS CONSIDERED TO BE RELEVANT

Category* Citation of document, with indication, where appropriate, of the relevant passages Relevant to claim No. WO 2004/035056 A l (NEUROSEARCH A/S) 29 April 2004 X See abstract, page 3 and page 17 1-3, 8-11, 18- 20, 25-28

WO 2007/107442 A2 (UNTVERSITE DE LIEGE) 27 September 2007 X See abstract, pages 13 and page 14 * 1-5, 10, 1 1 18-22, 27, 28

WO 2007/1 10363 A l (NEUROSEARCH A/S) 4 October 2007 X See abstract, page 12, lines 27-32 and page 13, lines 7 and 2 1 1-6, 10, 11 18-23, 27, 28 WO 2008/058536 A l (NEUROSEARCH A/S) 22 May 2008 X See abstract, page 2, lines 8-14 and page 13, line 26- page 14, line 20 1-6, 10, 11 18-23, 27, 28

X Further documents are listed in the continuation of Box C X See patent family annex

* Special categories of cited documents: "A" document defining the general state of the art which is "T" later document published after the international filing date or priority date and not in not considered to be of particular relevance conflict with the application but cited to understand the principle or theory underlying the invention "E" earlier application or patent but published on or after the "X" document of particular relevance; the claimed invention cannot be considered novel international filing date or cannot be considered to involve an inventive step when the document is taken alone "L" document which may throw doubts on priority claim(s) "Y" document of particular relevance, the claimed invention cannot be considered to or which is cited to establish the publication date of involve an inventive step when the document is combined with one or more other another citation or other special reason (as specified) such documents, such combination being obvious to a person skilled in the art "d" document referring to an oral disclosure, use, exhibition o r other means "& '' document member of the same patent family "P" document published prior to the international filing date but later than the priority date claimed Date of the actual completion of the international search Date of mailing of the international search report Q n p j onnn 14 October 2009 Name and mailing address of the ISA/AU Authorized officer Sarah Henderson AUSTRALIAN PATENT OFFICE PO BOX 200, WODEN ACT 2606, AUSTRALIA AUSTRALIAN PATENT OFFICE E-mail address: [email protected] (ISO 9001 Quality Certified Service) Facsimile No. +61 2 6283 7999 Telephone No : +61 2 6283 2614 INTERNATIONAL SEARCH REPORT International application No. PCT7AU2009/001012 C (Continuation). DOCUMENTS CONSIDERED TO BE RELEVANT

Category* Citation of document, with indication, where appropriate, of the relevant passages Relevant to claim No. WO 2008/003752 Al (NEUROSEARCH A/S) 10 January 2008 See abstract, page 2, lines 10-14 and page 13, line 26- page 14, line 9 1-6, 10, 11, 18-23, 27, 28

WO 2008/054435 A2 (THE REGENTS OF THE UNIVERSITY OF CALIFORNIA) 8 May 2008 X See abstract, page 3, lines 4-14 and page 4, lines 15-28 1, 2, 4-7, 18, 21-24 Aumann, T.D. et al., "SK channel function regulates the dopamine phenotype of neurons in the substantia nigra pars compacta", Experimental Neurology, 15 July 2008 (published online), Vol. 213, pages 419-430 See abstract 37

Hallworth, N.E. et al., "Apamin-Sensitive Small Conductance Calcium-Activated Potassium Channels, through their Selective Coupling to Voltage-Gated Calcium Channels, Are Critical Determinants of the Precision, Pace, and Pattern of Action Potential Generation in Rat Subthalamic Nucleus Neurons In Vitro", 2003, Journal of Neuroscience, Vol. 23, No. 20, pages 7525-7542 INTERNATIONAL SEARCH REPORT International application No. PCT7AU2009/001012

Box No. II Observations where certain claims were found unsearchable (Continuation of item 2 of first sheet)

This international search report has not been established in respect of certain claims under Article 17(2)(a) for the following reasons: 1. I Claims Nos.: because they relate to subject matter not required to be searched by this Authority, namely:

2. Claims Nos.: because they relate to parts of the international application that do not comply with the prescribed requirements to such an extent that no meaningful international search can be carried out, specifically:

3. ] Claims Nos.: because they are dependent claims and are not drafted in accordance with the second and third sentences of Rule 6.4(a)

Box No. Ill Observations where unity of invention is lacking (Continuation of item 3 of first sheet)

This International Searching Authority found multiple inventions in this international application, as follows: See supplementary sheet

1. As all required additional search fees were timely paid by the applicant, this international search report covers all searchable claims. 2 I I As all searchable claims could be searched without effort justifying additional fees, this Authority did not invite payment of additional fees. As only some of the required additional search fees were timely paid by the applicant, this international search report D covers only those claims for which fees were paid, specifically claims Nos.:

4. X No required additional search fees were timely paid by the applicant. Consequently, this international search report is restricted to the invention first mentioned in the claims; it is covered by claims Nos.: 1-5, 8, 9, 18-22, 25, 26 (partially) and 6, 7, 10, 11, 23, 24, 27, 28, 35, 36, 37 (in full)

Remark on Protest The additional search fees were accompanied by the applicant's protest and, where applicable, the payment of a protest fee.

The additional search fees were accompanied by the applicant's protest but the applicable protest fee was not paid within the time limit specified in the invitation

I I No protest accompanied the payment of additional search fees. INTERNATIONAL SEARCH REPORT Infernational application No PCT/AU2009/001012 Supplemental Box (To be used when the space in any of Boxes I to IV is not sufficient) Continuation of Box No: III The international application does not comply with the requirements of unity of invention because it does not relate to one invention or to a group of inventions so linked as to from a single general inventive concept. In coming to this conclusion the International Searching Authority has found that there are different inventions as follows:

1. Claims 1-5, 8, 9, 18-22, 25, 26 (partially) and 6, 7, 10, 11, 23, 24, 27, 28, 35, 36, 37 (in full) are directed to a method of treating neurological condition associated with abnormal levels of dopamine via the SK channel, a method of inducing migration of dopaminergic cells or recruiting dopaminergic cells or stimulating synthesis of dopamine by administration of SK specific agonists.

2 Claims 1-5, 8, 9, 18-22, 25, 26 (partially) and J2-14, 29-31 (in full) are directed to a method of treating a neurological condition associated with abnormal levels of dopamine via the GABAA receptor

3 Claims 1-5, 8, 9, 18-22, 25, 26 (partially) and 15-17, 32-34 (in full) are to a method of treating a neurological condition associated with abnormal levels of dopamine via the L-type voltage activated calcium channel.

PCT Rule 13.2, first sentence, states that unity of invention is only fulfilled when there is a technical relationship among the claimed inventions involving one or more of the same or corresponding special technical features. PCT Rule 13.2, second sentence, defines a special technical feature as a feature which makes a contribution over the prior art. In the above groups of claims, the only feature common to all of the claims and which provides a technical relationship among them is the use of an agent that modulates the excitability of a neuronal cell. However this concept is not novel in the light of the following citation

Ji, H et al., SK Ca2+-activated K+ channel ligands alter the firing pattern of dopamine-containing neurons in vivo. Neuroscience. 2006 Jun 30, Vol.40, No.2, pages 623-33.

Therefore, there is no special technical feature present in the claims and the requirements for unity of invention are consequently not satisfied a posteriori. INTERNATIONAL SEARCH REPQRT International application No. Information on patent family members PCT7AU2009/001012

This Annex lists the known "A" publication level patent family members relating to the patent documents cited in the above-mentioned international search report. The Australian Patent Office is in no way liable for these particulars which are merely given for the purpose of information.

Patent Document Cited in Patent Family Member - ' Search Report

WO 2004035056 AU 2003271548 WO 2007107442 EP 1998775 US 2009093517 WO 2007110363 EP 2001853 US 2009099208 WO 2008058536 EP 2083821 WO 2008003752 EP 2041096 wo 2008054435 NONE

Due to data integration issues this family listing may not include 10 digit Australian applications filed since May 2001. END OF ANNEX