Analysis of B-Subunit-Dependent GABA a Receptor Modulation And
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Valerenic Acid Potentiates and Inhibits GABAA Receptors: Molecular Mechanism and Subunit Specificity
ARTICLE IN PRESS + MODEL Neuropharmacology xx (2007) 1e10 www.elsevier.com/locate/neuropharm Valerenic acid potentiates and inhibits GABAA receptors: Molecular mechanism and subunit specificity S. Khom a, I. Baburin a, E. Timin a, A. Hohaus a, G. Trauner b, B. Kopp b, S. Hering a,* a Department of Pharmacology and Toxicology, University of Vienna, Althanstrasse 14, A-1090 Vienna, Austria b Department of Pharmacognosy, University of Vienna, Althanstrasse 14, A-1090 Vienna, Austria Received 8 December 2006; received in revised form 11 April 2007; accepted 30 April 2007 Abstract Valerian is a commonly used herbal medicinal product for the treatment of anxiety and insomnia. Here we report the stimulation of chloride currents through GABAA receptors (IGABA) by valerenic acid (VA), a constituent of Valerian. To analyse the molecular basis of VA action, we expressed GABAA receptors with 13 different subunit compositions in Xenopus oocytes and measured IGABA using the two-microelectrode voltage-clamp technique. We report a subtype-dependent stimulation of IGABA by VA. Only channels incorporating b2 or b3 subunits were stimulated by VA. Replacing b2/3 by b1 drastically reduced the sensitivity of the resulting GABAA channels. The stimulatory effect of VA on a1b2 receptors was substantially reduced by the point mutation b2N265S (known to inhibit loreclezole action). Mutating the corresponding residue of b1 (b1S290N) induced VA sensitivity in a1b1S290N comparable to a1b2 receptors. Modulation of IGABA was not significantly dependent on incorporation of a1, a2, a3 or a5 subunits. VA displayed a significantly lower efficiency on channels incorporating a4 subunits. IGABA modulation by VA was not g subunit dependent and not inhibited by flumazenil (1 mM). -
GABA Receptors
D Reviews • BIOTREND Reviews • BIOTREND Reviews • BIOTREND Reviews • BIOTREND Reviews Review No.7 / 1-2011 GABA receptors Wolfgang Froestl , CNS & Chemistry Expert, AC Immune SA, PSE Building B - EPFL, CH-1015 Lausanne, Phone: +41 21 693 91 43, FAX: +41 21 693 91 20, E-mail: [email protected] GABA Activation of the GABA A receptor leads to an influx of chloride GABA ( -aminobutyric acid; Figure 1) is the most important and ions and to a hyperpolarization of the membrane. 16 subunits with γ most abundant inhibitory neurotransmitter in the mammalian molecular weights between 50 and 65 kD have been identified brain 1,2 , where it was first discovered in 1950 3-5 . It is a small achiral so far, 6 subunits, 3 subunits, 3 subunits, and the , , α β γ δ ε θ molecule with molecular weight of 103 g/mol and high water solu - and subunits 8,9 . π bility. At 25°C one gram of water can dissolve 1.3 grams of GABA. 2 Such a hydrophilic molecule (log P = -2.13, PSA = 63.3 Å ) cannot In the meantime all GABA A receptor binding sites have been eluci - cross the blood brain barrier. It is produced in the brain by decarb- dated in great detail. The GABA site is located at the interface oxylation of L-glutamic acid by the enzyme glutamic acid decarb- between and subunits. Benzodiazepines interact with subunit α β oxylase (GAD, EC 4.1.1.15). It is a neutral amino acid with pK = combinations ( ) ( ) , which is the most abundant combi - 1 α1 2 β2 2 γ2 4.23 and pK = 10.43. -
Dynamic Regulation of the GABAA Receptor Function by Redox Mechanisms S
Supplemental material to this article can be found at: http://molpharm.aspetjournals.org/content/suppl/2016/07/20/mol.116.105205.DC1 1521-0111/90/3/326–333$25.00 http://dx.doi.org/10.1124/mol.116.105205 MOLECULAR PHARMACOLOGY Mol Pharmacol 90:326–333, September 2016 Copyright ª 2016 by The American Society for Pharmacology and Experimental Therapeutics MINIREVIEW—A LATIN AMERICAN PERSPECTIVE ON ION CHANNELS Dynamic Regulation of the GABAA Receptor Function by Redox Mechanisms s Daniel J. Calvo and Andrea N. Beltrán González Laboratorio de Neurobiología Celular y Molecular, Instituto de Investigaciones en Ingeniería Genética y Biología Molecular Downloaded from ¨Dr. Héctor N. Torres¨ (INGEBI), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Ciudad Autónoma de Buenos Aires, Argentina (D.J.C., A.N.B.G.) Received May 15, 2016; accepted July 14, 2016 ABSTRACT molpharm.aspetjournals.org Oxidizing and reducing agents, which are currently involved normally present in neurons and glia or are endogenously in cell metabolism and signaling pathways, can regulate fast generated in these cells under physiologic states or during inhibitory neurotransmission mediated by GABA receptors in the oxidative stress (e.g., hydrogen peroxide, superoxide and hy- nervous system. A number of in vitro studies have shown that droxyl radicals, nitric oxide, ascorbic acid, and glutathione), diverse redox compounds, including redox metabolites and induce potentiating or inhibiting actions on different native and reactive oxygen and nitrogen species, modulate phasic and recombinant GABAA receptor subtypes. Based on these results, it tonic responses mediated by neuronal GABAA receptors through is thought that redox signaling might represent a homeostatic both presynaptic and postsynaptic mechanisms. -
Anxiety Disorders and GABA Neurotransmission: a Disturbance of Modulation
Journal name: Neuropsychiatric Disease and Treatment Article Designation: REVIEW Year: 2015 Volume: 11 Neuropsychiatric Disease and Treatment Dovepress Running head verso: Nuss Running head recto: Anxiety and modulation open access to scientific and medical research DOI: http://dx.doi.org/10.2147/NDT.S58841 Open Access Full Text Article REVIEW Anxiety disorders and GABA neurotransmission: a disturbance of modulation Philippe Nuss1,2 Abstract: Lines of evidence coming from many branches of neuroscience indicate that anxiety 1Department of Psychiatry, Hôpital St disorders arise from a dysfunction in the modulation of brain circuits which regulate emotional Antoine, AP-HP, 2UMR 7203, INSERM responses to potentially threatening stimuli. The concept of anxiety disorders as a disturbance ERL 1057 – Bioactive Molecules of emotional response regulation is a useful one as it allows anxiety to be explained in terms Laboratory, Pierre and Marie Curie University, Paris, France of a more general model of aberrant salience and also because it identifies avenues for devel- oping psychological, behavioral, and pharmacological strategies for the treatment of anxiety disorder. These circuits involve bottom-up activity from the amygdala, indicating the presence of potentially threatening stimuli, and top-down control mechanisms originating in the prefron- tal cortex, signaling the emotional salience of stimuli. Understanding the factors that control cortical mechanisms may open the way to identification of more effective cognitive behavioral strategies for managing anxiety disorders. The brain circuits in the amygdala are thought to For personal use only. comprise inhibitory networks of γ-aminobutyric acid-ergic (GABAergic) interneurons and this neurotransmitter thus plays a key role in the modulation of anxiety responses both in the normal and pathological state. -
Neonatal Clonazepam Administration Induced Long-Lasting Changes in GABAA and GABAB Receptors
International Journal of Molecular Sciences Article Neonatal Clonazepam Administration Induced Long-Lasting Changes in GABAA and GABAB Receptors Hana Kubová 1,* , Zde ˇnkaBendová 2,3 , Simona Moravcová 2,3 , Dominika Paˇcesová 2,3, Luisa Rocha 4 and Pavel Mareš 1 1 Institute of Physiology, Academy of Sciences of the Czech Republic, 14220 Prague, Czech Republic; [email protected] 2 Faculty of Science, Charles University, 12800 Prague, Czech Republic; [email protected] (Z.B.); [email protected] (S.M.); [email protected] (D.P.) 3 National Institute of Mental Health, 25067 Klecany, Czech Republic 4 Pharmacobiology Department, Center of Research and Advanced Studies, Mexico City 14330, Mexico; [email protected] * Correspondence: [email protected]; Tel.: +420-2-4106-2565 Received: 31 March 2020; Accepted: 28 April 2020; Published: 30 April 2020 Abstract: Benzodiazepines (BZDs) are widely used in patients of all ages. Unlike adults, neonatal animals treated with BZDs exhibit a variety of behavioral deficits later in life; however, the mechanisms underlying these deficits are poorly understood. This study aims to examine whether administration of clonazepam (CZP; 1 mg/kg/day) in 7–11-day-old rats affects Gama aminobutyric acid (GABA)ergic receptors in both the short and long terms. Using RT-PCR and quantitative autoradiography, we examined the expression of the selected GABAA receptor subunits (α1, α2, α4, γ2, and δ) and the GABAB B2 subunit, and GABAA, benzodiazepine, and GABAB receptor binding 48 h, 1 week, and 2 months after treatment discontinuation. Within one week after CZP cessation, the expression of the α2 subunit was upregulated, whereas that of the δ subunit was downregulated in both the hippocampus and cortex. -
Neurochemical Mechanisms Underlying Alcohol Withdrawal
Neurochemical Mechanisms Underlying Alcohol Withdrawal John Littleton, MD, Ph.D. More than 50 years ago, C.K. Himmelsbach first suggested that physiological mechanisms responsible for maintaining a stable state of equilibrium (i.e., homeostasis) in the patient’s body and brain are responsible for drug tolerance and the drug withdrawal syndrome. In the latter case, he suggested that the absence of the drug leaves these same homeostatic mechanisms exposed, leading to the withdrawal syndrome. This theory provides the framework for a majority of neurochemical investigations of the adaptations that occur in alcohol dependence and how these adaptations may precipitate withdrawal. This article examines the Himmelsbach theory and its application to alcohol withdrawal; reviews the animal models being used to study withdrawal; and looks at the postulated neuroadaptations in three systems—the gamma-aminobutyric acid (GABA) neurotransmitter system, the glutamate neurotransmitter system, and the calcium channel system that regulates various processes inside neurons. The role of these neuroadaptations in withdrawal and the clinical implications of this research also are considered. KEY WORDS: AOD withdrawal syndrome; neurochemistry; biochemical mechanism; AOD tolerance; brain; homeostasis; biological AOD dependence; biological AOD use; disorder theory; biological adaptation; animal model; GABA receptors; glutamate receptors; calcium channel; proteins; detoxification; brain damage; disease severity; AODD (alcohol and other drug dependence) relapse; literature review uring the past 25 years research- science models used to study with- of the reasons why advances in basic ers have made rapid progress drawal neurochemistry as well as a research have not yet been translated Din understanding the chemi- reluctance on the part of clinicians to into therapeutic gains and suggests cal activities that occur in the nervous consider new treatments. -
Bicuculline and Gabazine Are Allosteric Inhibitors of Channel Opening of the GABAA Receptor
The Journal of Neuroscience, January 15, 1997, 17(2):625–634 Bicuculline and Gabazine Are Allosteric Inhibitors of Channel Opening of the GABAA Receptor Shinya Ueno,1 John Bracamontes,1 Chuck Zorumski,2 David S. Weiss,3 and Joe Henry Steinbach1 Departments of 1Anesthesiology and 2Psychiatry, Washington University School of Medicine, St. Louis, Missouri 63110, and 3University of Alabama at Birmingham, Neurobiology Research Center and Department of Physiology and Biophysics, Birmingham, Alabama 35294-0021 Anesthetic drugs are known to interact with GABAA receptors, bicuculline only partially blocked responses to pentobarbital. both to potentiate the effects of low concentrations of GABA and These observations indicate that the blockers do not compete to directly gate open the ion channel in the absence of GABA; with alphaxalone or pentobarbital for a single class of sites on the however, the site(s) involved in direct gating by these drugs is not GABAA receptor. Finally, at receptors containing a1b2(Y157S)g2L known. We have studied the ability of alphaxalone (an anesthetic subunits, both bicuculline and gabazine showed weak agonist steroid) and pentobarbital (an anesthetic barbiturate) to directly activity and actually potentiated responses to alphaxalone. These activate recombinant GABAA receptors containing the a1, b2, and observations indicate that the blocking drugs can produce allo- g2L subunits. Steroid gating was not affected when either of two steric changes in GABAA receptors, at least those containing this mutated b2 subunits [b2(Y157S) and b2(Y205S)] are incorporated mutated b2 subunit. We conclude that the sites for binding ste- into the receptors, although these subunits greatly reduce the roids and barbiturates do not overlap with the GABA-binding site. -
Molecular Mechanisms of Antiseizure Drug Activity at GABAA Receptors
View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by Elsevier - Publisher Connector Seizure 22 (2013) 589–600 Contents lists available at SciVerse ScienceDirect Seizure jou rnal homepage: www.elsevier.com/locate/yseiz Review Molecular mechanisms of antiseizure drug activity at GABAA receptors L. John Greenfield Jr.* Dept. of Neurology, University of Arkansas for Medical Sciences, 4301W. Markham St., Slot 500, Little Rock, AR 72205, United States A R T I C L E I N F O A B S T R A C T Article history: The GABAA receptor (GABAAR) is a major target of antiseizure drugs (ASDs). A variety of agents that act at Received 6 February 2013 GABAARs s are used to terminate or prevent seizures. Many act at distinct receptor sites determined by Received in revised form 16 April 2013 the subunit composition of the holoreceptor. For the benzodiazepines, barbiturates, and loreclezole, Accepted 17 April 2013 actions at the GABAAR are the primary or only known mechanism of antiseizure action. For topiramate, felbamate, retigabine, losigamone and stiripentol, GABAAR modulation is one of several possible Keywords: antiseizure mechanisms. Allopregnanolone, a progesterone metabolite that enhances GABAAR function, Inhibition led to the development of ganaxolone. Other agents modulate GABAergic ‘‘tone’’ by regulating the Epilepsy synthesis, transport or breakdown of GABA. GABAAR efficacy is also affected by the transmembrane Antiepileptic drugs chloride gradient, which changes during development and in chronic epilepsy. This may provide an GABA receptor Seizures additional target for ‘‘GABAergic’’ ASDs. GABAAR subunit changes occur both acutely during status Chloride channel epilepticus and in chronic epilepsy, which alter both intrinsic GABAAR function and the response to GABAAR-acting ASDs. -
Characterisation of GABAA Receptors and Cation-Chloride Cotransporters in the Uterus and Their Role in Pre-Term Labour
Characterisation of GABAA receptors and cation-chloride cotransporters in the uterus and their role in pre-term labour Melissa Linda Sutherland December 2017 Supervisors: Dr. Amy V. Poole, Dr. Jennifer A. Fraser, Dr. Claire Garden. A thesis submitted in partial fulfilment of the requirements of Edinburgh Napier University, for the award of Master by Research Declaration It is hereby declared that this thesis is the result of the author’s original research. It has been composed by the author and has not been previously submitted for examination, which has led to the award of a degree or professional qualification. Signed: Date: Contents page Abbreviations .............................................................................................. 1 Acknowledgements ................................................................................... 3 Abstract ......................................................................................................... 4 CHAPTER 1. Introduction ......................................................................... 5 1.1-aminobutyric acid (GABA) .............................................................. 5 1.2 GABA receptor structure and function .......................................... 5 Figure 1.1 Schematic diagram of the GABAA subunit and receptor ......................................................................................................... 6 1.3 GABAARs role in development central nervous system .......................................................................................................... -
Ion Channels
UC Davis UC Davis Previously Published Works Title THE CONCISE GUIDE TO PHARMACOLOGY 2019/20: Ion channels. Permalink https://escholarship.org/uc/item/1442g5hg Journal British journal of pharmacology, 176 Suppl 1(S1) ISSN 0007-1188 Authors Alexander, Stephen PH Mathie, Alistair Peters, John A et al. Publication Date 2019-12-01 DOI 10.1111/bph.14749 License https://creativecommons.org/licenses/by/4.0/ 4.0 Peer reviewed eScholarship.org Powered by the California Digital Library University of California S.P.H. Alexander et al. The Concise Guide to PHARMACOLOGY 2019/20: Ion channels. British Journal of Pharmacology (2019) 176, S142–S228 THE CONCISE GUIDE TO PHARMACOLOGY 2019/20: Ion channels Stephen PH Alexander1 , Alistair Mathie2 ,JohnAPeters3 , Emma L Veale2 , Jörg Striessnig4 , Eamonn Kelly5, Jane F Armstrong6 , Elena Faccenda6 ,SimonDHarding6 ,AdamJPawson6 , Joanna L Sharman6 , Christopher Southan6 , Jamie A Davies6 and CGTP Collaborators 1School of Life Sciences, University of Nottingham Medical School, Nottingham, NG7 2UH, UK 2Medway School of Pharmacy, The Universities of Greenwich and Kent at Medway, Anson Building, Central Avenue, Chatham Maritime, Chatham, Kent, ME4 4TB, UK 3Neuroscience Division, Medical Education Institute, Ninewells Hospital and Medical School, University of Dundee, Dundee, DD1 9SY, UK 4Pharmacology and Toxicology, Institute of Pharmacy, University of Innsbruck, A-6020 Innsbruck, Austria 5School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, BS8 1TD, UK 6Centre for Discovery Brain Science, University of Edinburgh, Edinburgh, EH8 9XD, UK Abstract The Concise Guide to PHARMACOLOGY 2019/20 is the fourth in this series of biennial publications. The Concise Guide provides concise overviews of the key properties of nearly 1800 human drug targets with an emphasis on selective pharmacology (where available), plus links to the open access knowledgebase source of drug targets and their ligands (www.guidetopharmacology.org), which provides more detailed views of target and ligand properties. -
Hooked on Benzodiazepines: GABAA Receptor Subtypes and Addiction
Review Hooked on benzodiazepines: GABAA receptor subtypes and addiction Kelly R. Tan1, Uwe Rudolph2 and Christian Lu¨ scher1,3 1 Department of Basic Neurosciences, Medical Faculty, University of Geneva, CH-1211 Geneva, Switzerland 2 Laboratory of Genetic Neuropharmacology, McLean Hospital and Department of Psychiatry, Harvard Medical School, Belmont, MA 02478, USA 3 Clinic of Neurology, Department of Clinical Neurosciences, Geneva University Hospital, CH-1211 Geneva, Switzerland Benzodiazepines are widely used clinically to treat anxi- ment approaches even more difficult. The knowledge of how ety and insomnia. They also induce muscle relaxation, BDZs induce addiction might help in the development of control epileptic seizures, and can produce amnesia. anxiolytics and hypnotics with lower addictive liability. Moreover, benzodiazepines are often abused after chron- All addictive drugs, as well as natural rewards, increase ic clinical treatment and also for recreational purposes. dopamine (DA) levels in the mesolimbic dopamine (DA) Within weeks, tolerance to the pharmacological effects system, also termed the reward system (Box 2). Several can develop as a sign of dependence. In vulnerable indi- landmark studies with monkeys have shown that DA viduals with compulsive drug use, addiction will be diag- neurons play a role in signaling ‘reward error prediction’, nosed. Here we review recent observations from animal and thus are involved in learning processes related to models regarding the cellular and molecular basis that reward and intrinsic value. Specifically, DA neurons are might underlie the addictive properties of benzodiaze- excited following the presentation of an unexpected re- pines. These data reveal how benzodiazepines, acting ward. Once this reward becomes predictable (by an experi- through specific GABAA receptor subtypes, activate mid- mentally controlled cue), DA neurons shift their phasic brain dopamine neurons, and how this could hijack the activation from the reward to the cue. -
The Effect of Chronic Alcohol Abuse on the Benzodiazepine Receptor
f Ps al o ych rn ia u tr o y J Journal of Psychiatry Shushpanova et al., J Psychiatry 2016, 19:3 DOI: 10.4172/2378-5756.1000365 ISSN: 2378-5756 Research Article OpenOpen Access Access The Effect of Chronic Alcohol Abuse on the Benzodiazepine Receptor System in Various Areas of the Human Brain Shushpanova TV1*, Bokhan NA2, Lebedeva VF2, Solonskii AV1 and Udut VV3 1Department of Clinical Neuroimmunology and Neurobiology, Mental Health Research Institute, Russia 2Department of Addictive Disorders, Mental Health Research Institute, Russia 3Department of Molecular and Clinical Pharmacology, Research Institute of Pharmacology and Regenerative Medicine, Russia Abstract Objective: Alcohol abuse induces neuroadaptive changes in the functioning of neurotransmitter systems in the brain. Decrease of GABAergic neurotransmission found in alcoholics and persons with a high risk of alcohol dependence. Benzodiazepine receptor (BzDR) is allosterical modulatory site on GABA type A receptor complex (GABAAR), that modulate GABAergic function and may be important in mechanisms regulating the excitability of the brain processes involved in the alcohol addiction. The purpose of this study was to investigate the effects of chronic alcohol abuse on the BzDR in various areas of the human brain. Materials and Methods: Investigation of BzDR properties were studied in synaptosomal and mitochondrial membrane fractions from different brain areas of alcohol abused patients and non-alcoholic persons by radioreceptor assay with using selective ligands: [3H] flunitrazepam and [3H] PK-11195. Brain samples obtained at autopsy urgent. In total 126 samples of human brain areas were obtained to study radioreceptor binding, including a study group and control group. Results: Comparative study of kinetic parameters (Kd, Bmax) of [3H] flunitrazepam and [3H] PK-11195 binding with membrane fractions in studding brain samples was showed that affinity of BzDR was decreased and capacity increased in different areas of human brain under influence of alcohol abuse.