DOCSLIB.ORG

Physiological Roles of Endogenous Neurosteroids at Α2 Subunit-Containing GABAA Receptors

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Physiological Roles of Endogenous Neurosteroids at Α2 Subunit-Containing GABAA Receptors Physiological roles of endogenous neurosteroids at α2 subunit-containing GABAA receptors Elizabeth Jane Durkin A thesis submitted to University College London for the degree of Doctor of Philosophy October 2012 Department of Neuroscience, Physiology and Pharmacology University College London Gower Street London WC1E 6BT Declaration 2 Declaration I, Elizabeth Durkin, confirm that the work presented in this thesis is my own. Where information has been derived from other sources, I confirm that this has been indicated in the thesis Abstract 3 Abstract Neurosteroids are important endogenous modulators of the major inhibitory neurotransmitter receptor in the brain, the γ-amino-butyric acid type A (GABAA) receptor. They are involved in numerous physiological processes, and are linked to several central nervous system disorders, including depression and anxiety. The neurosteroids allopregnanolone and allo-tetrahydro-deoxy-corticosterone (THDOC) have many effects in animal models (anxiolysis, analgesia, sedation, anticonvulsion, antidepressive), suggesting they could be useful therapeutic agents, for example in anxiety, stress and mood disorders. Neurosteroids potentiate GABA-activated currents by binding to a conserved site within α subunits. Potentiation can be eliminated by hydrophobic substitution of the α1Q241 residue (or equivalent in other α isoforms). Previous studies suggest that α2 subunits are key components in neural circuits affecting anxiety and depression, and that neurosteroids are endogenous anxiolytics. It is therefore possible that this anxiolysis occurs via potentiation at α2 subunit-containing receptors. To examine this hypothesis, α2Q241M knock-in mice were generated, and used to define the roles of α2 subunits in mediating effects of endogenous and injected neurosteroids. Biochemical and imaging analyses indicated that relative expression levels and localization of GABAA receptor α1-α5 subunits were unaffected, suggesting the knock- in had not caused any compensatory effects. Electrophysiological characterization of cells in hippocampal and nucleus accumbens brain slices revealed faster-decaying inhibitory synaptic transmission in α2Q241M mice. Furthermore, the response to applied THDOC was markedly reduced compared to wild-type cells. α2 subunits therefore formed a major component of synaptic GABAA receptors in these areas. The α2Q241M knock-ins showed greater anxiety levels in two classical rodent anxiety paradigms (light-dark box and elevated plus maze), consistent with endogenous neurosteroids mediating anxiolysis via α2-type GABAA receptors. In addition, the anxiolytic response to injected THDOC is impaired by the α2Q241M mutation, which would identify the α2 isoform as an appropriate target for generating receptor subtype- selective neurosteroid therapeutics for anxiety disorders. Acknowledgements 4 Acknowledgements I will forever be indebted to the many people who have helped me along my PhD journey, especially to Prof. Trevor Smart, for allowing me to work on such a challenging and exciting project, and for his unending support, guidance and enduring positivity. This project would not have been possible without the financial support of the MRC, and helpful advice from my thesis committee, Stuart Cull-Candy, Stephen Nurrish and Antonella Riccio. Thank you to Mike Lumb, for generating the transgenic mouse strain, together with Steve Moss and GenOway. For generously providing lab space and loaning me the equipment necessary for the behavioural analyses, I am grateful to Clare Stanford and Stephen Hunt. I would also like to thank Clare, and members of her lab, especially Ruth Weir and Ewelina Grabowska, for teaching me behavioural techniques, and helping me interpret results from these experiments. Thank you also to Martin Stocker for allowing access to his microtome. Thanks to all members of the Smart lab, past and present, for creating an excellent environment to work in, and being a great source of fun and of encouragement through the inevitable experimental difficulties. I would particularly like to thank Damian and Phil, for their excellent teaching and support, and for being on hand whenever my rig misbehaved! Also, thanks to Saad for sharing his imaging expertise, and PhD pep talks. I would also like to take this opportunity to thank all of the Durkin ‘clan’ – above all, Mum, Dad, Rob, Billy and Pat – for reminding me that there is life outside of my PhD, and whose love and support has given me the drive to make it through my academic career to date. I am particularly grateful to my PhD buddies who have shared in this rollercoaster ride, especially Sinead and Kasia, who have always been there for a chat over coffee. Finally, the biggest of thanks is owed to Stuart for his patience, constant encouragement, and excellent curries! Contents 5 Contents Declaration .................................................................................................................................................. 2 Abstract ....................................................................................................................................................... 3 Acknowledgements .................................................................................................................................... 4 List of Figures ............................................................................................................................................. 8 List of Tables............................................................................................................................................... 9 List of Abbreviations ................................................................................................................................ 10 Chapter 1: Introduction ............................................................................................................................ 12 1.1. GABAA receptors ............................................................................................................................... 12 1.1.1. GABAA receptor composition and function ............................................................................................ 13 1.1.2. GABAA receptor modulation: trafficking ................................................................................................. 18 1.1.3. GABAA receptor modulation: ligands and post-translational modification .............................................. 21 1.2. Neurosteroid physiology and pharmacology .................................................................................. 27 1.2.1. Endogenous neurosteroids: synthesis and roles ................................................................................... 27 1.2.2. Neurosteroid binding to GABAA receptors ............................................................................................. 30 1.2.3. Physiological modulation of GABAA receptors by neurosteroids ........................................................... 32 1.2.4. Neurosteroids: therapeutic potential ...................................................................................................... 34 1.3. Neurosteroids and GABAA receptors in anxiety ............................................................................. 35 1.3.1. The HPA axis and neurosteroids as endogenous anxiolytics ................................................................ 35 1.3.2. Defining the GABAA receptor α subunits that are important in anxiety and anxiolysis ........................... 37 1.4. Neurosteroids and GABAA receptors in depression ...................................................................... 39 1.4.1. Roles for GABAA receptors in depression ............................................................................................. 39 1.4.2. Roles for neurosteroids as antidepressants .......................................................................................... 43 1.4.3. The nucleus accumbens in reward and depression .............................................................................. 44 1.5. Thesis Aims........................................................................................................................................ 46 Q241M 1.5.1. Generation of an α2 knock-in mouse ............................................................................................. 46 Q241M 1.5.2. Electrophysiological characterisation of α2 mice ........................................................................... 46 Q241M 1.5.3. Behavioural characterisation of α2 mice ........................................................................................ 47 1.5.4. Summary of thesis aims ........................................................................................................................ 47 Chapter 2: Materials and Methods .......................................................................................................... 49 2.1. Materials ............................................................................................................................................. 49 2.1.1. Reagents .............................................................................................................................................. 49 2.1.2. Antibodies ............................................................................................................................................. 49 2.2. Animals ..............................................................................................................................................
Load more

Recommended publications
  • 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.
    [Show full text]
  • Exploring the Activity of an Inhibitory Neurosteroid at GABAA Receptors
    1 Exploring the activity of an inhibitory neurosteroid at GABAA receptors Sandra Seljeset A thesis submitted to University College London for the Degree of Doctor of Philosophy November 2016 Department of Neuroscience, Physiology and Pharmacology University College London Gower Street WC1E 6BT 2 Declaration I, Sandra Seljeset, confirm that the work presented in this thesis is my own. Where information has been derived from other sources, I can confirm that this has been indicated in the thesis. 3 Abstract The GABAA receptor is the main mediator of inhibitory neurotransmission in the central nervous system. Its activity is regulated by various endogenous molecules that act either by directly modulating the receptor or by affecting the presynaptic release of GABA. Neurosteroids are an important class of endogenous modulators, and can either potentiate or inhibit GABAA receptor function. Whereas the binding site and physiological roles of the potentiating neurosteroids are well characterised, less is known about the role of inhibitory neurosteroids in modulating GABAA receptors. Using hippocampal cultures and recombinant GABAA receptors expressed in HEK cells, the binding and functional profile of the inhibitory neurosteroid pregnenolone sulphate (PS) were studied using whole-cell patch-clamp recordings. In HEK cells, PS inhibited steady-state GABA currents more than peak currents. Receptor subtype selectivity was minimal, except that the ρ1 receptor was largely insensitive. PS showed state-dependence but little voltage-sensitivity and did not compete with the open-channel blocker picrotoxinin for binding, suggesting that the channel pore is an unlikely binding site. By using ρ1-α1/β2/γ2L receptor chimeras and point mutations, the binding site for PS was probed.
    [Show full text]
  • Antinociceptive Activity of a Neurosteroid Tetrahydrodeoxycorticosterone (5Cx-Pregnan-3Cx-21-Diol-20-One) and Its Possible Mechanism(S) of Action
    Indian Journal of Experimental Biology Vol. 39, December 2001, pp. 1299-1301 Antinociceptive activity of a neurosteroid tetrahydrodeoxycorticosterone (5cx-pregnan-3cx-21-diol-20-one) and its possible mechanism(s) of action P K Mediratta, M Gambhir, K K Sharma & M Ray Department of Pharmacology, University College of Medical Sciences and GTB Hospital, Delhi II 0095, India Fax: 91-11-2299495; E-mail: [email protected]/[email protected] Received 9 Apri/2001; revised 2 July 2001 The present study investigates the effects of a neurosteroid tetrahydrodeoxycorticosterone (5a-pregnan-3a-21-diol-20- one) in two experimental models of pain sensitivity in mice. Tetrahydrodeoxycorticosterone (2.5, 5 mg!kg, ip) dose dependently decreased the licking response in formalin test and increased the tail flick latency (TFL) in tail flick test. Bicuculline (2 mg/kg, ip), a GABAA receptor antagonist blocked the antinociceptive effect of tetrahydrodeoxy­ corticosterone in TFL test but failed to modulate licking response in formalin test. Naloxone (I mglkg, ip), an opioid antagonist effectively attenuated the analgesic effect of tetrahydrodeoxycorticosterone in both the models. Tetrahydrodeoxycorticosterone pretreatment potentiated the anti nociceptive response of morphine, an opioid compound and nimodipine, a calcium channel blocker in formalin as well as TFL test. Thus, tetrahydrodeoxycorticosterone exerts an analgesic effect, which may be mediated by modulating GABA-ergic and/or opioid-ergic mechanisms and voltage-gated calcium channels. It is now well known that some of the steroids like Allopregnanolone has been shown to exhibit progesterone can act on central nervous system (CNS) antinociceptive effect against an aversive thermal to produce a number of endocrine and behavioral stimulus 10 and in a rat mechanical visceral pain 11 effects.
    [Show full text]
  • Research in Anxiety Disorders: from the Bench to the Bedside Matthew Garner A,⁎, Hanns Möhler B, Dan J
    NEUPSY-10154; No of Pages 10 ARTICLE IN PRESS European Neuropsychopharmacology (2009) xx, xxx–xxx www.elsevier.com/locate/euroneuro REVIEW ARTICLE Research in anxiety disorders: From the bench to the bedside Matthew Garner a,⁎, Hanns Möhler b, Dan J. Stein c, Thomas Mueggler d, David S. Baldwin a a University of Southampton, UK b University of Zurich, Switzerland c University of Cape Town, South Africa d University and ETH of Zurich, Switzerland Received 13 January 2009; accepted 30 January 2009 KEYWORDS Abstract Anxiety; Treatment; The development of ethologically based behavioural animal models has clarified the anxiolytic Imaging; properties of a range of neurotransmitter and neuropeptide receptor agonists and antagonists, Cognition with several models predicting efficacy in human clinical samples. Neuro-cognitive models of human anxiety and findings from fMRI suggest dysfunction in amygdala-prefrontal circuitry underlies biases in emotion activation and regulation. Cognitive and neural mechanisms involved in emotion processing can be manipulated pharmacologically, and research continues to identify genetic polymorphisms and interactions with environmental risk factors that co-vary with anxiety-related behaviour and neuro-cognitive endophenotypes. This paper describes findings from a range of research strategies in anxiety, discussed at the recent ECNP Targeted Expert Meeting on anxiety disorders and anxiolytic drugs. The efficacy of existing pharmacological treatments for anxiety disorders is discussed, with particular reference to drugs modulating serotonergic, noradrenergic and gabaergic mechanisms, and novel targets including glutamate, CCK, NPY, adenosine and AVP. Clinical and neurobiological predictors of active treatment and placebo response are considered. © 2009 Published by Elsevier B.V. Anxiety symptoms are common in the community, and typically persist for many years, and are associated with anxiety disorders are common in primary and secondary significant personal distress, reduced quality of life, medical care settings (King et al., 2008).
    [Show full text]
  • Brain Imaging
    Publications · Brochures Brain Imaging A Technologist’s Guide Produced with the kind Support of Editors Fragoso Costa, Pedro (Oldenburg) Santos, Andrea (Lisbon) Vidovič, Borut (Munich) Contributors Arbizu Lostao, Javier Pagani, Marco Barthel, Henryk Payoux, Pierre Boehm, Torsten Pepe, Giovanna Calapaquí-Terán, Adriana Peștean, Claudiu Delgado-Bolton, Roberto Sabri, Osama Garibotto, Valentina Sočan, Aljaž Grmek, Marko Sousa, Eva Hackett, Elizabeth Testanera, Giorgio Hoffmann, Karl Titus Tiepolt, Solveig Law, Ian van de Giessen, Elsmarieke Lucena, Filipa Vaz, Tânia Morbelli, Silvia Werner, Peter Contents Foreword 4 Introduction 5 Andrea Santos, Pedro Fragoso Costa Chapter 1 Anatomy, Physiology and Pathology 6 Elsmarieke van de Giessen, Silvia Morbelli and Pierre Payoux Chapter 2 Tracers for Brain Imaging 12 Aljaz Socan Chapter 3 SPECT and SPECT/CT in Oncological Brain Imaging (*) 26 Elizabeth C. Hackett Chapter 4 Imaging in Oncological Brain Diseases: PET/CT 33 EANM Giorgio Testanera and Giovanna Pepe Chapter 5 Imaging in Neurological and Vascular Brain Diseases (SPECT and SPECT/CT) 54 Filipa Lucena, Eva Sousa and Tânia F. Vaz Chapter 6 Imaging in Neurological and Vascular Brain Diseases (PET/CT) 72 Ian Law, Valentina Garibotto and Marco Pagani Chapter 7 PET/CT in Radiotherapy Planning of Brain Tumours 92 Roberto Delgado-Bolton, Adriana K. Calapaquí-Terán and Javier Arbizu Chapter 8 PET/MRI for Brain Imaging 100 Peter Werner, Torsten Boehm, Solveig Tiepolt, Henryk Barthel, Karl T. Hoffmann and Osama Sabri Chapter 9 Brain Death 110 Marko Grmek Chapter 10 Health Care in Patients with Neurological Disorders 116 Claudiu Peștean Imprint 126 n accordance with the Austrian Eco-Label for printed matters.
    [Show full text]
  • Radiotracers for SPECT Imaging: Current Scenario and Future Prospects
    Radiochim. Acta 100, 95–107 (2012) / DOI 10.1524/ract.2011.1891 © by Oldenbourg Wissenschaftsverlag, München Radiotracers for SPECT imaging: current scenario and future prospects By S. Adak1,∗, R. Bhalla2, K. K. Vijaya Raj1, S. Mandal1, R. Pickett2 andS.K.Luthra2 1 GE Healthcare Medical Diagnostics, John F Welch Technology Center, Bangalore, India 560066 2 GE Healthcare Medical Diagnostics, The Grove Centre, White Lion Road, Amersham, HP7 9LL, UK (Received October 4, 2010; accepted in final form July 18, 2011) Nuclear medicine / 99m-Technetium / 123-Iodine / ton emission computed tomography (SPECT or less com- Oncological imaging / Neurological imaging / monly known as SPET) and positron emission tomogra- Cardiovascular imaging phy (PET). Both techniques use radiolabeled molecules to probe molecular processes that can be visualized, quanti- fied and tracked over time, thus allowing the discrimination Summary. Single photon emission computed tomography of healthy from diseased tissue with a high degree of con- (SPECT) has been the cornerstone of nuclear medicine and today fidence. The imaging agents use target-specific biological it is widely used to detect molecular changes in cardiovascular, processes associated with the disease being assessed both at neurological and oncological diseases. While SPECT has been the cellular and subcellular levels within living organisms. available since the 1980s, advances in instrumentation hardware, The impact of molecular imaging has been on greater under- software and the availability of new radiotracers that are creating a revival in SPECT imaging are reviewed in this paper. standing of integrative biology, earlier detection and charac- The biggest change in the last decade has been the fusion terization of disease, and evaluation of treatment in human of CT with SPECT, which has improved attenuation correction subjects [1–3].
    [Show full text]
  • Neurosteroid Metabolism in the Human Brain
    European Journal of Endocrinology (2001) 145 669±679 ISSN 0804-4643 REVIEW Neurosteroid metabolism in the human brain Birgit Stoffel-Wagner Department of Clinical Biochemistry, University of Bonn, 53127 Bonn, Germany (Correspondence should be addressed to Birgit Stoffel-Wagner, Institut fuÈr Klinische Biochemie, Universitaet Bonn, Sigmund-Freud-Strasse 25, D-53127 Bonn, Germany; Email: [email protected]) Abstract This review summarizes the current knowledge of the biosynthesis of neurosteroids in the human brain, the enzymes mediating these reactions, their localization and the putative effects of neurosteroids. Molecular biological and biochemical studies have now ®rmly established the presence of the steroidogenic enzymes cytochrome P450 cholesterol side-chain cleavage (P450SCC), aromatase, 5a-reductase, 3a-hydroxysteroid dehydrogenase and 17b-hydroxysteroid dehydrogenase in human brain. The functions attributed to speci®c neurosteroids include modulation of g-aminobutyric acid A (GABAA), N-methyl-d-aspartate (NMDA), nicotinic, muscarinic, serotonin (5-HT3), kainate, glycine and sigma receptors, neuroprotection and induction of neurite outgrowth, dendritic spines and synaptogenesis. The ®rst clinical investigations in humans produced evidence for an involvement of neuroactive steroids in conditions such as fatigue during pregnancy, premenstrual syndrome, post partum depression, catamenial epilepsy, depressive disorders and dementia disorders. Better knowledge of the biochemical pathways of neurosteroidogenesis and
    [Show full text]
  • Site-Specific Effects of Neurosteroids on GABA(A) Receptor Activation and Desensitization
    Washington University School of Medicine Digital Commons@Becker Open Access Publications 2020 Site-specific effects of neurosteroids on GABA(A) receptor activation and desensitization Yusuke Sugasawa Washington University School of Medicine in St. Louis Wayland W.L. Cheng Washington University School of Medicine in St. Louis John R. Bracamontes Washington University School of Medicine in St. Louis Zi-Wei Chen Washington University School of Medicine in St. Louis Lei Wang Washington University School of Medicine in St. Louis See next page for additional authors Follow this and additional works at: https://digitalcommons.wustl.edu/open_access_pubs Recommended Citation Sugasawa, Yusuke; Cheng, Wayland W.L.; Bracamontes, John R.; Chen, Zi-Wei; Wang, Lei; Germann, Allison L.; Pierce, Spencer R.; Senneff, Thomas C.; Krishnan, Kathiresan; Reichert, David E.; Covey, Douglas F.; Akk, Gustav; and Evers, Alex S., ,"Site-specific effects of neurosteroids on GABA(A) receptor activation and desensitization." Elife.,. (2020). https://digitalcommons.wustl.edu/open_access_pubs/9682 This Open Access Publication is brought to you for free and open access by Digital Commons@Becker. It has been accepted for inclusion in Open Access Publications by an authorized administrator of Digital Commons@Becker. For more information, please contact [email protected]. Authors Yusuke Sugasawa, Wayland W.L. Cheng, John R. Bracamontes, Zi-Wei Chen, Lei Wang, Allison L. Germann, Spencer R. Pierce, Thomas C. Senneff, Kathiresan Krishnan, David E. Reichert, Douglas F. Covey,
    [Show full text]
  • An Open-Label Study to Evaluate Switching from an SSRI Or SNRI To
    Annals of Clinical Psychiatry, 19[1]:25–30, 2007 Copyright © American Academy of Clinical Psychiatrists ISSN: 1040-1237 print / 1547-3325 online DOI: 10.1080/10401230601163535 AnUACP Open-Label Study to Evaluate Switching from an SSRI or SNRI to Tiagabine to Alleviate Antidepressant- Induced Sexual Dysfunction in Generalized Anxiety Disorder THOMASEffect of Tiagabine on sexual dysfunction in GAD L. SCHWARTZ, MD Department of Psychiatry, SUNY Upstate Medical University, Syracuse, NY, USA GEORGE S. NASRA, MD Unity Behavioral Health, Rochester, NY, USA ADAM K. ASHTON, MD Department of Psychiatry, SUNY Buffalo School of Medicine, Buffalo, NY, USA DAVID KANG, MD, HARI KUMARESAN, MD, MARK CHILTON, MS, and FRANCESCA BERTONE, BA Department of Psychiatry, SUNY Upstate Medical University, Syracuse, NY, USA Background. This study investigated tiagabine monotherapy in subjects with generalized anxiety disorder (GAD) who had been switched from selective serotonin reuptake inhibitors (SSRIs) or serotonin-norepinephrine reuptake inhibitors (SNRIs) as a result of antidepressant-induced sexual dysfunction. Methods. Adults with DSM-IV GAD, an adequate therapeutic response (≥50% decrease in Hamilton Rating Scale for Anxiety [HAM-A] total score) to SSRI or SNRI and sexual dysfunction were switched to open-label tiagabine 4–12 mg/day for 14 weeks. Assessments included the HAM-A, Hospital Anxiety & Depression Scale (HADS) and the Arizona Sexual Experiences Scale (ASEX); assessments were made at baseline and at Weeks 4, 8, and 14. Results. Twenty six subjects were included in the analysis. Tiagabine showed no worsening in baseline symptoms of GAD, with non-significant changes from baseline in mean HAM-A total scores and HADS Anxiety and Depression subscale scores.
    [Show full text]
  • Maintenance of Melanocyte Stem Cell Quiescence by GABA-A Signaling in Larval
    Genetics: Early Online, published on August 23, 2019 as 10.1534/genetics.119.302416 1 1 Maintenance of melanocyte stem cell quiescence by GABA-A signaling in larval 2 zebrafish 3 4 James R. Allen1*, James B. Skeath1, Stephen L. Johnson1† 5 6 1Department of Genetics, Washington University School of Medicine, St. Louis, Missouri, 7 63110, USA 8 9 *Corresponding Author 10 † Deceased 11 Dedication: This paper is dedicated to the late Dr. Stephen L. Johnson. 12 13 14 15 16 17 18 19 20 21 22 23 Copyright 2019. 2 1 2 3 Running Title: GABA-A inhibits zebrafish pigmentation 4 Key Words: GABA, melanocyte, GABA-A receptors, quiescence, zebrafish, 5 pigmentation, inhibition, CRISPR 6 Corresponding Author: 7 Department of Genetics, Room 6315 Scott McKinley Research Building, 4523 Clayton 8 Avenue, Washington University School of Medicine, St. Louis, MO, 63110 9 Ph: 314-362-05351, E-mail: [email protected] 10 11 12 13 14 15 16 17 18 19 20 21 22 23 3 1 Abstract: 2 In larval zebrafish, melanocyte stem cells (MSCs) are quiescent, but can be recruited to 3 regenerate the larval pigment pattern following melanocyte ablation. Through 4 pharmacological experiments, we found that inhibition of GABA-A receptor function, 5 specifically the GABA-A rho subtype, induces excessive melanocyte production in larval 6 zebrafish. Conversely, pharmacological activation of GABA-A inhibited melanocyte 7 regeneration. We used CRISPR-Cas9 to generate two mutant alleles of gabrr1, a subtype 8 of GABA-A receptors. Both alleles exhibited robust melanocyte overproduction, while 9 conditional overexpression of gabrr1 inhibited larval melanocyte regeneration.
    [Show full text]
  • Neurochemical and Behavioral Features in Genetic Absence Epilepsy and in Acutely Induced Absence Seizures
    Hindawi Publishing Corporation ISRN Neurology Volume 2013, Article ID 875834, 48 pages http://dx.doi.org/10.1155/2013/875834 Review Article Neurochemical and Behavioral Features in Genetic Absence Epilepsy and in Acutely Induced Absence Seizures A. S. Bazyan1 and G. van Luijtelaar2 1 Institute of Higher Nervous Activity and Neurophysiology, Russian Academy of Science, Russian Federation, 5A Butlerov Street, Moscow 117485, Russia 2 Biological Psychology, Donders Centre for Cognition, Donders Institute for Brain, Cognition and Behavior, Radboud University Nijmegen, P.O. Box 9104, 6500 HE Nijmegen, The Netherlands Correspondence should be addressed to G. van Luijtelaar; [email protected] Received 21 January 2013; Accepted 6 February 2013 Academic Editors: R. L. Macdonald, Y. Wang, and E. M. Wassermann Copyright © 2013 A. S. Bazyan and G. van Luijtelaar. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The absence epilepsy typical electroencephalographic pattern of sharp spikes and slow waves (SWDs) is considered to be dueto an interaction of an initiation site in the cortex and a resonant circuit in the thalamus. The hyperpolarization-activated cyclic nucleotide-gated cationic Ih pacemaker channels (HCN) play an important role in the enhanced cortical excitability. The role of thalamic HCN in SWD occurrence is less clear. Absence epilepsy in the WAG/Rij strain is accompanied by deficiency of the activity of dopaminergic system, which weakens the formation of an emotional positive state, causes depression-like symptoms, and counteracts learning and memory processes.
    [Show full text]
  • Alcohol and Brain Damage in Adults with Reference to High-Risk Groups
    CR185 Alcohol and brain damage in adults With reference to high-risk groups © 2014 Royal College of Psychiatrists For full details of reports available and how to obtain them, contact the Book Sales Assistant at the Royal College of Psychiatrists, 21 Prescot Street, COLLEGE REPORT London E1 8BB (tel. 020 7235 2351; fax 020 3701 2761) or visit the College website at http://www.rcpsych.ac.uk/publications/collegereports.aspx Alcohol and brain damage in adults With reference to high-risk groups College report CR185 The Royal College of Psychiatrists, the Royal College of Physicians (London), the Royal College of General Practitioners and the Association of British Neurologists May 2014 Approved by the Policy Committee of the Royal College of Psychiatrists: September 2013 Due for review: 2018 © 2014 Royal College of Psychiatrists College Reports constitute College policy. They have been sanctioned by the College via the Policy Committee. For full details of reports available and how to obtain them, contact the Book Sales Assistant at the Royal College of Psychiatrists, 21 Prescot Street, London E1 8BB (tel. 020 7235 2351; fax 020 7245 1231) or visit the College website at http://www.rcpsych. ac.uk/publications/collegereports.aspx The Royal College of Psychiatrists is a charity registered in England and Wales (228636) and in Scotland (SC038369). | Contents List of abbreviations iv Working group v Executive summary and recommendations 1 Lay summary 6 Introduction 12 Clinical definition and diagnosis of alcohol-related brain damage and related
    [Show full text]