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Uusi-Oukari M, Korpi ER. GABAergic mechanisms in alcohol dependence. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2024; 175:75-123. [PMID: 38555121 DOI: 10.1016/bs.irn.2024.03.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/02/2024]
Abstract
The target of alcohol's effect on the central nervous system has been sought for more than 50 years in the brain's GABA system. The behavioral and emotional effects of alcohol in humans and rodents are very similar to those of barbiturates and benzodiazepines, and GABAA receptors have been shown to be one of the sites of alcohol action. The mechanisms of GABAergic inhibition have been a hotspot of research but have turned out to be complex and controversial. Genetics support the involvement of some GABAA receptor subunits in the development of alcohol dependence and in alcohol use disorders (AUD). Since the effect of alcohol on the GABAA system resembles that of a GABAergic positive modulator, it may be possible to develop GABAergic drug treatments that could substitute for alcohol. The adaptation mechanisms of the GABA system and the plasticity of the brain are a big challenge for drug development: the drugs that act on GABAA receptors developed so far also may cause adaptation and development of additional addiction. Human polymorphisms should be studied further to get insight about how they affect receptor function, expression or other factors to make reasonable predictions/hypotheses about what non-addictive interventions would help in alcohol dependence and AUD.
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Affiliation(s)
- Mikko Uusi-Oukari
- Integrative Physiology and Pharmacology, Institute of Biomedicine, University of Turku, Turku, Finland
| | - Esa R Korpi
- Department of Pharmacology, Faculty of Medicine, University of Helsinki, Helsinki, Finland.
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2
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Crofton EJ, O'Buckley TK, Bohnsack JP, Morrow AL, Herman MA. Divergent Population-Specific Effects of Chronic Ethanol Exposure on Excitability and Inhibitory Transmission in Male and Female Rat Central Amygdala. J Neurosci 2023; 43:7056-7068. [PMID: 37657933 PMCID: PMC10586533 DOI: 10.1523/jneurosci.0717-23.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2023] [Revised: 08/09/2023] [Accepted: 08/26/2023] [Indexed: 09/03/2023] Open
Abstract
The central nucleus of the amygdala (CeA) is implicated in alcohol use disorder (AUD) and AUD-associated plasticity. The CeA is a primarily GABAergic nucleus that is subdivided into lateral and medial compartments with genetically diverse subpopulations. GABAA receptors are heteromeric pentamers with subunits conferring distinct physiological characteristics. GABAA receptor signaling in the CeA has been implicated in ethanol-associated plasticity; however, population-specific changes in inhibitory signaling and subunit expression remain unclear. Here, we combined electrophysiology with single-cell gene expression analysis of population markers and GABAA receptor subunits to examine population-specific changes in inhibitory control in male and female rats following chronic ethanol exposure. We found that chronic ethanol exposure and withdrawal produced global changes in GABAA receptor subunit expression at the transcript and protein levels, increased excitability in female CeA neurons, and increased inhibitory synaptic transmission in male CeA neurons. When we examined CeA neurons at the single-cell level we found heterogenous populations, as previously reported. We observed ethanol-induced increases in excitability only in somatostatin neurons in the CeA of females, decreases in excitability only in the protein kinase C delta (PKCd) population in males, and ethanol-induced increases in inhibitory transmission in male PKCd and calbindin 2-expressing CeA neurons. There were no population-specific differences in GABAA receptor (Gabr) subunits in males but reduced GabrA5 expression in female somatostatin neurons. Collectively, these findings suggest that defined CeA populations display differential ethanol sensitivity in males and females, which may play a role in sex differences in vulnerability to AUD or expression of AUD pathology.SIGNIFICANCE STATEMENT The CeA is involved in the effects of ethanol in the brain; however, the population-specific changes in CeA activity remain unclear. We used recordings of CeA neuronal activity and single-cell gene expression to examine population-specific changes in inhibitory control in male and female rats following chronic ethanol exposure and found sex- and population-specific effects of chronic ethanol exposure and withdrawal. Specifically, female CeA neurons displayed increased excitability in the somatostatin CeA population, whereas male CeA neurons displayed increased inhibitory control in both PKCd and calbindin populations and decreased excitability in the PKCd population. These findings identify CeA populations that display differential sensitivity to ethanol exposure, which may contribute to sex differences in vulnerability to alcohol use disorder.
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Affiliation(s)
- Elizabeth J Crofton
- Departments of Psychiatry
- Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
- Bowles Center for Alcohol Studies, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
- Department of Psychology and Neuroscience, Emmanuel College, Boston, Massachusetts 02115
| | - Todd K O'Buckley
- Bowles Center for Alcohol Studies, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
| | - John P Bohnsack
- Departments of Psychiatry
- Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
- Bowles Center for Alcohol Studies, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
| | - A Leslie Morrow
- Departments of Psychiatry
- Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
- Bowles Center for Alcohol Studies, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
| | - Melissa A Herman
- Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
- Bowles Center for Alcohol Studies, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
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3
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Xiao T, Chen Y, Boisvert A, Cole M, Kimbrough A. Chronic Intermittent Ethanol Vapor Exposure Paired with Two-Bottle Choice to Model Alcohol Use Disorder. J Vis Exp 2023:10.3791/65320. [PMID: 37427930 PMCID: PMC11164185 DOI: 10.3791/65320] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/11/2023] Open
Abstract
Alcohol use disorder (AUD) is a chronic alcohol-related disorder that typically presents as uncontrolled drinking and preoccupation with alcohol. A key component of AUD research is using translationally relevant preclinical models. Over the past several decades, a variety of animal models have been used to study AUD. One prominent model of AUD is the chronic intermittent ethanol vapor exposure (CIE) model, which is a well-established approach for inducing alcohol dependence in rodents through repeated cycles of ethanol exposure via inhalation. To model AUD in mice, the CIE exposure is paired with a voluntary two-bottle choice (2BC) of alcohol drinking and water to measure the escalation of alcohol drinking. The 2BC/CIE procedure involves alternating weeks of 2BC drinking and CIE, which repeat until the escalation of alcohol drinking is achieved. In the present study, we outline the procedures for performing 2BC/CIE, including the daily use of the CIE vapor chamber, and provide an example of escalated alcohol drinking in C57BL/6J mice using this approach.
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Affiliation(s)
- Tiange Xiao
- Department of Basic Medical Sciences, College of Veterinary Medicine, Purdue University
| | - Yueyi Chen
- Department of Basic Medical Sciences, College of Veterinary Medicine, Purdue University
| | - Alyssa Boisvert
- Department of Basic Medical Sciences, College of Veterinary Medicine, Purdue University
| | | | - Adam Kimbrough
- Department of Basic Medical Sciences, College of Veterinary Medicine, Purdue University; Purdue Institute for Integrative Neuroscience; Weldon School of Biomedical Engineering, Purdue University; Purdue Institute of Inflammation, Immunology, and Infectious Disease;
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Munier J, Shen S, Rahal D, Hanna A, Marty V, O'Neill P, Fanselow M, Spigelman I. Chronic intermittent ethanol exposure disrupts stress-related tripartite communication to impact affect-related behavioral selection in male rats. Neurobiol Stress 2023; 24:100539. [PMID: 37131490 PMCID: PMC10149313 DOI: 10.1016/j.ynstr.2023.100539] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2022] [Revised: 04/12/2023] [Accepted: 04/16/2023] [Indexed: 05/04/2023] Open
Abstract
Alcohol use disorder (AUD) is characterized by loss of intake control, increased anxiety, and susceptibility to relapse inducing stressors. Both astrocytes and neurons contribute to behavioral and hormonal consequences of chronic intermittent ethanol (CIE) exposure in animal models. Details on how CIE disrupts hypothalamic neuro-glial communication, which mediates stress responses are lacking. We conducted a behavioral battery (grooming, open field, reactivity to a single, uncued foot-shock, intermittent-access two-bottle choice ethanol drinking) followed by Ca2+ imaging in ex-vivo slices of paraventricular nucleus of the hypothalamus (PVN) from male rats exposed to CIE vapor or air-exposed controls. Ca2+ signals were evaluated in response to norepinephrine (NE) with or without selective α-adrenergic receptor (αAR) or GluN2B-containing N-methyl-D-aspartate receptor (NMDAR) antagonists, followed by dexamethasone (DEX) to mock a pharmacological stress response. Expectedly, CIE rats had altered anxiety-like, rearing, grooming, and drinking behaviors. Importantly, NE-mediated reductions in Ca2+ event frequency were blunted in both CIE neurons and astrocytes. Administration of the selective α1AR antagonist, prazosin, reversed this CIE-induced dysfunction in both cell types. Additionally, the pharmacological stress protocol reversed the altered basal Ca2+ signaling profile of CIE astrocytes. Signaling changes in astrocytes in response to NE were correlated with anxiety-like behaviors, such as the grooming:rearing ratio, suggesting tripartite synaptic function plays a role in switching between exploratory and stress-coping behavior. These data show how CIE exposure causes persistent changes to PVN neuro-glial function and provides the groundwork for how these physiological changes manifest in behavioral selection.
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Affiliation(s)
- J.J. Munier
- Laboratory of Neuropharmacology, Section of Biosystems & Function, School of Dentistry, UCLA, United States
- Corresponding author.
| | - S. Shen
- Laboratory of Neuropharmacology, Section of Biosystems & Function, School of Dentistry, UCLA, United States
| | - D. Rahal
- Edna Bennett Pierce Prevention Research Center, The Pennsylvania State University, United States
| | - A. Hanna
- Laboratory of Neuropharmacology, Section of Biosystems & Function, School of Dentistry, UCLA, United States
| | - V.N. Marty
- Laboratory of Neuropharmacology, Section of Biosystems & Function, School of Dentistry, UCLA, United States
| | - P.R. O'Neill
- Hatos Center for Neuropharmacology, Department of Psychiatry & Biobehavioral Sciences, David Geffen School of Medicine, UCLA, United States
| | - M.S. Fanselow
- Department of Psychology, College of Life Sciences, Department of Psychiatry & Biobehavioral Science, David Geffen School of Medicine, UCLA, United States
| | - I. Spigelman
- Laboratory of Neuropharmacology, Section of Biosystems & Function, School of Dentistry, UCLA, United States
- Corresponding author. Laboratory of Neuropharmacology, Section of Biosystems & Function, School of Dentistry, UCLA, 10833 Le Conte Avenue, 63-078 CHS, Los Angeles, CA, 90095-1668, United States.
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Bach EC, Ewin SE, Heaney CF, Carlson HN, Ortelli OA, Almonte AG, Chappell AM, Raab-Graham KF, Weiner JL. Chemogenetic inhibition of a monosynaptic projection from the basolateral amygdala to the ventral hippocampus selectively reduces appetitive, but not consummatory, alcohol drinking-related behaviours. Eur J Neurosci 2023; 57:1241-1259. [PMID: 36840503 PMCID: PMC10931538 DOI: 10.1111/ejn.15944] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2022] [Revised: 01/16/2023] [Accepted: 02/20/2023] [Indexed: 02/26/2023]
Abstract
Alcohol use disorder (AUD) and anxiety/stressor disorders frequently co-occur and this dual diagnosis represents a major health and economic problem worldwide. The basolateral amygdala (BLA) is a key brain region that is known to contribute to the aetiology of both disorders. Although many studies have implicated BLA hyperexcitability in the pathogenesis of AUD and comorbid conditions, relatively little is known about the specific efferent projections from this brain region that contribute to these disorders. Recent optogenetic studies have shown that the BLA sends a strong monosynaptic excitatory projection to the ventral hippocampus (vHC) and that this circuit modulates anxiety- and fear-related behaviours. However, it is not known if this pathway influences alcohol drinking-related behaviours. Here, we employed a rodent operant self-administration regimen that procedurally separates appetitive (e.g. seeking) and consummatory (e.g., drinking) behaviours, chemogenetics and brain region-specific microinjections, to determine if BLA-vHC circuitry influences alcohol and sucrose drinking-related measures. We first confirmed prior optogenetic findings that silencing this circuit reduced anxiety-like behaviours on the elevated plus maze. We then demonstrated that inhibiting the BLA-vHC pathway significantly reduced appetitive drinking-related behaviours for both alcohol and sucrose while having no effect on consummatory measures. Taken together, these findings provide the first indication that the BLA-vHC circuit may regulate appetitive reward seeking directed at alcohol and natural rewards and add to a growing body of evidence suggesting that dysregulation of this pathway may contribute to the pathophysiology of AUD and anxiety/stressor-related disorders.
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Affiliation(s)
- Eva C Bach
- Department of Physiology and Pharmacology, Wake Forest School of Medicine, Winston-Salem, North Carolina, USA
| | - Sarah E Ewin
- Department of Physiology and Pharmacology, Wake Forest School of Medicine, Winston-Salem, North Carolina, USA
| | - Chelcie F Heaney
- Department of Physiology and Pharmacology, Wake Forest School of Medicine, Winston-Salem, North Carolina, USA
| | - Hannah N Carlson
- Department of Physiology and Pharmacology, Wake Forest School of Medicine, Winston-Salem, North Carolina, USA
| | - Olivia A Ortelli
- Department of Physiology and Pharmacology, Wake Forest School of Medicine, Winston-Salem, North Carolina, USA
| | - Antoine G Almonte
- Department of Physiology and Pharmacology, Wake Forest School of Medicine, Winston-Salem, North Carolina, USA
| | - Ann M Chappell
- Department of Physiology and Pharmacology, Wake Forest School of Medicine, Winston-Salem, North Carolina, USA
| | - Kimberly F Raab-Graham
- Department of Physiology and Pharmacology, Wake Forest School of Medicine, Winston-Salem, North Carolina, USA
| | - Jeffrey L Weiner
- Department of Physiology and Pharmacology, Wake Forest School of Medicine, Winston-Salem, North Carolina, USA
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Ornelas LC, Boero G, Van Voorhies K, O’Buckley TK, Besheer J, Morrow AL. Pharmacological administration of 3α,5α-THP into the nucleus accumbens core increases 3α,5α-THP expression and reduces alcohol self-administration. ALCOHOL, CLINICAL & EXPERIMENTAL RESEARCH 2023; 47:459-469. [PMID: 36587947 PMCID: PMC10234128 DOI: 10.1111/acer.15008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/26/2022] [Revised: 11/16/2022] [Accepted: 12/23/2022] [Indexed: 01/03/2023]
Abstract
BACKGROUND Alcohol affects multiple circuits in the brain, mainly disrupting the delicate balance between inhibitory γ-aminobutyric acid (GABA) transmission and excitatory glutamate signaling in brain areas involved in reward circuits. These include the amygdala, nucleus accumbens (Acb), and ventral tegmental area (VTA). This action impairs circuits that regulate behavioral control of craving and alcohol seeking and intake. Studies in both rodent models and postmortem human brain of patients with alcohol use disorder (AUD) have highlighted the association between the loss of GABAergic inhibition and the development of addiction. The neurosteroid (3α,5α)-3-hydroxypregnan-20-one (3α,5α-THP) is a potent positive modulator of GABAA receptors. Chronic alcohol consumption reduces 3α,5α-THP levels, resulting in decreased GABA inhibition. We previously demonstrated that enhancing neurosteroid biosynthesis by overexpression of the cholesterol side-chain cleavage enzyme P450scc decreased alcohol intake in male alcohol-preferring rats (P-rats). While most of the evidence of alcohol-induced alterations comes from studies in male subjects, some data show that females are more vulnerable to alcohol's effects than males. METHODS In this study, we investigated the ability of 3α,5α-THP direct infusions in two brain regions that contribute to alcohol reinforcement, the VTA and Acb core (AcbC), to regulate alcohol self-administration in female P-rats. RESULTS Administration of 3α,5α-THP into the AcbC increased 3α,5α-THP-positive cell expression in this area and reduced alcohol self-administration. By contrast, 3α,5α-THP infusion into the VTA did not significantly affect alcohol self-administration, though trends for a reduction were found. CONCLUSIONS Our results show that local increases in 3α,5α-THP in the AcbC may alter mesolimbic activity that drives a reduction in alcohol self-administration.
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Affiliation(s)
- Laura C. Ornelas
- Bowles Center for Alcohol Studies, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
| | - Giorgia Boero
- Bowles Center for Alcohol Studies, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
| | - Kalynn Van Voorhies
- Bowles Center for Alcohol Studies, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
| | - Todd K. O’Buckley
- Bowles Center for Alcohol Studies, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
| | - Joyce Besheer
- Bowles Center for Alcohol Studies, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
- Department of Psychiatry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
| | - A. Leslie Morrow
- Bowles Center for Alcohol Studies, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
- Department of Psychiatry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
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7
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Gimenez-Gomez P, Le T, Martin GE. Modulation of neuronal excitability by binge alcohol drinking. Front Mol Neurosci 2023; 16:1098211. [PMID: 36866357 PMCID: PMC9971943 DOI: 10.3389/fnmol.2023.1098211] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2022] [Accepted: 01/19/2023] [Indexed: 02/16/2023] Open
Abstract
Drug use poses a serious threat to health systems throughout the world. The number of consumers rises every year being alcohol the drug of abuse most consumed causing 3 million deaths (5.3% of all deaths) worldwide and 132.6 million disability-adjusted life years. In this review, we present an up-to-date summary about what is known regarding the global impact of binge alcohol drinking on brains and how it affects the development of cognitive functions, as well as the various preclinical models used to probe its effects on the neurobiology of the brain. This will be followed by a detailed report on the state of our current knowledge of the molecular and cellular mechanisms underlying the effects of binge drinking on neuronal excitability and synaptic plasticity, with an emphasis on brain regions of the meso-cortico limbic neurocircuitry.
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Affiliation(s)
- Pablo Gimenez-Gomez
- Department of Neurobiology, University of Massachusetts Chan Medical School, Worcester, MA, United States
- The Brudnick Neuropsychiatric Research Institute, Worcester, MA, United States
| | - Timmy Le
- Department of Neurobiology, University of Massachusetts Chan Medical School, Worcester, MA, United States
- The Brudnick Neuropsychiatric Research Institute, Worcester, MA, United States
- Graduate Program in Neuroscience, Morningside Graduate School of Biomedical Sciences, UMass Chan Medical School, Worcester, MA, United States
| | - Gilles E. Martin
- Department of Neurobiology, University of Massachusetts Chan Medical School, Worcester, MA, United States
- The Brudnick Neuropsychiatric Research Institute, Worcester, MA, United States
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8
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Gatta E, Camussi D, Auta J, Guidotti A, Pandey SC. Neurosteroids (allopregnanolone) and alcohol use disorder: From mechanisms to potential pharmacotherapy. Pharmacol Ther 2022; 240:108299. [PMID: 36323379 PMCID: PMC9810076 DOI: 10.1016/j.pharmthera.2022.108299] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2022] [Revised: 10/14/2022] [Accepted: 10/17/2022] [Indexed: 11/06/2022]
Abstract
Alcohol Use Disorder (AUD) is a multifaceted relapsing disorder that is commonly comorbid with psychiatric disorders, including anxiety. Alcohol exposure produces a plethora of effects on neurobiology. Currently, therapeutic strategies are limited, and only a few treatments - disulfiram, acamprosate, and naltrexone - are available. Given the complexity of this disorder, there is a great need for the identification of novel targets to develop new pharmacotherapy. The GABAergic system, the primary inhibitory system in the brain, is one of the well-known targets for alcohol and is responsible for the anxiolytic effects of alcohol. Interestingly, GABAergic neurotransmission is fine-tuned by neuroactive steroids that exert a regulatory role on several endocrine systems involved in neuropsychiatric disorders including AUD. Mounting evidence indicates that alcohol alters the biosynthesis of neurosteroids, whereas acute alcohol increases and chronic alcohol decreases allopregnanolone levels. Our recent work highlighted that chronic alcohol-induced changes in neurosteroid levels are mediated by epigenetic modifications, e.g., DNA methylation, affecting key enzymes involved in neurosteroid biosynthesis. These changes were associated with changes in GABAA receptor subunit expression, suggesting an imbalance between excitatory and inhibitory signaling in AUD. This review will recapitulate the role of neurosteroids in the regulation of the neuroendocrine system, highlight their role in the observed allostatic load in AUD, and develop a framework from mechanisms to potential pharmacotherapy.
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Affiliation(s)
- Eleonora Gatta
- Center for Alcohol Research in Epigenetics, Department of Psychiatry, Psychiatric Institute, University of Illinois at Chicago, USA
| | - Diletta Camussi
- Center for Alcohol Research in Epigenetics, Department of Psychiatry, Psychiatric Institute, University of Illinois at Chicago, USA
| | - James Auta
- Center for Alcohol Research in Epigenetics, Department of Psychiatry, Psychiatric Institute, University of Illinois at Chicago, USA
| | - Alessandro Guidotti
- Center for Alcohol Research in Epigenetics, Department of Psychiatry, Psychiatric Institute, University of Illinois at Chicago, USA
| | - Subhash C Pandey
- Center for Alcohol Research in Epigenetics, Department of Psychiatry, Psychiatric Institute, University of Illinois at Chicago, USA; Jesse Brown Veterans Affairs Medical Center Chicago, IL 60612, USA.
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Imbriani P, Sciamanna G, El Atiallah I, Cerri S, Hess EJ, Pisani A. Synaptic effects of ethanol on striatal circuitry: therapeutic implications for dystonia. FEBS J 2022; 289:5834-5849. [PMID: 34217152 PMCID: PMC9786552 DOI: 10.1111/febs.16106] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2021] [Revised: 05/21/2021] [Accepted: 07/02/2021] [Indexed: 12/30/2022]
Abstract
Alcohol consumption affects motor behavior and motor control. Both acute and chronic alcohol abuse have been extensively investigated; however, the therapeutic efficacy of alcohol on some movement disorders, such as myoclonus-dystonia or essential tremor, still does not have a plausible mechanistic explanation. Yet, there are surprisingly few systematic trials with known GABAergic drugs mimicking the effect of alcohol on neurotransmission. In this brief survey, we aim to summarize the effects of EtOH on striatal function, providing an overview of its cellular and synaptic actions in a 'circuit-centered' view. In addition, we will review both experimental and clinical evidence, in the attempt to provide a plausible mechanistic explanation for alcohol-responsive movement disorders, with particular emphasis on dystonia. Different hypotheses emerge, which may provide a rationale for the utilization of drugs that mimic alcohol effects, predicting potential drug repositioning.
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Affiliation(s)
- Paola Imbriani
- Department of Systems MedicineUniversity of Rome ‘Tor Vergata’Italy,IRCCS Fondazione Santa LuciaRomeItaly
| | - Giuseppe Sciamanna
- Department of Systems MedicineUniversity of Rome ‘Tor Vergata’Italy,IRCCS Fondazione Santa LuciaRomeItaly
| | - Ilham El Atiallah
- Department of Systems MedicineUniversity of Rome ‘Tor Vergata’Italy,IRCCS Fondazione Santa LuciaRomeItaly
| | | | - Ellen J. Hess
- Departments of Pharmacology and Chemical Biology and NeurologyEmory UniversityAtlantaGAUSA
| | - Antonio Pisani
- IRCCS Mondino FoundationPaviaItaly,Department of Brain and Behavioral SciencesUniversity of PaviaItaly
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10
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Floris G, Asuni GP, Talani G, Biggio F, Pisu MG, Zanda MT, Contu L, Maciocco E, Serra M, Follesa P. Increased Voluntary Alcohol Consumption in Mice Lacking GABA B(1) Is Associated With Functional Changes in Hippocampal GABA A Receptors. Front Behav Neurosci 2022; 16:893835. [PMID: 35755407 PMCID: PMC9218813 DOI: 10.3389/fnbeh.2022.893835] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2022] [Accepted: 05/09/2022] [Indexed: 11/26/2022] Open
Abstract
Gamma-aminobutyric acid type B receptor (GABABR) has been extensively involved in alcohol use disorders; however, the mechanisms by which this receptor modulates alcohol drinking behavior remain murky. In this study, we investigate alcohol consumption and preference in mice lacking functional GABABR using the 2-bottle choice paradigm. We found that GABAB(1), knockout (KO), and heterozygous (HZ) mice drank higher amounts of an alcoholic solution, preferred alcohol to water, and reached higher blood alcohol concentrations (BACs) compared to wild-type (WT) littermates. The GABABR agonist GHB significantly reduced alcohol consumption in the GABAB(1) HZ and WT but not in the KO mice. Next, because of a functional crosstalk between GABABR and δ-containing GABAA receptor (δ-GABAAR), we profiled δ subunit mRNA expression levels in brain regions in which the crosstalk was characterized. We found a loss of the alcohol-sensitive GABAAR δ subunit in the hippocampus of the GABAB(1) KO alcohol-naïve mice that was associated with increased ɣ2 subunit abundance. Electrophysiological recordings revealed that these molecular changes were associated with increased phasic inhibition, suggesting a potential gain of synaptic GABAAR responsiveness to alcohol that has been previously described in an animal model of excessive alcohol drinking. Interestingly, voluntary alcohol consumption did not revert the dramatic loss of hippocampal δ-GABAAR occurring in the GABAB(1) KO mice but rather exacerbated this condition. Finally, we profiled hippocampal neuroactive steroids levels following acute alcohols administration in the GABAB(1) KO and WT mice because of previous involvement of GABABR in the regulation of cerebral levels of these compounds. We found that systemic administration of alcohol (1.5 g/kg) did not produce alcohol-induced neurosteroid response in the GABAB(1) KO mice but elicited an expected increase in the hippocampal level of progesterone and 3α,5α-THP in the WT controls. In conclusion, we show that genetic ablation of the GABAB(1) subunit results in increased alcohol consumption and preference that were associated with functional changes in hippocampal GABAAR, suggesting a potential mechanism by which preference for alcohol consumption is maintained in the GABAB(1) KO mice. In addition, we documented that GABAB(1) deficiency results in lack of alcohol-induced neurosteroids, and we discussed the potential implications of this finding in the context of alcohol drinking and dependence.
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Affiliation(s)
- Gabriele Floris
- Department of Life and Environment Sciences, Section of Neuroscience and Anthropology, University of Cagliari, Cagliari, Italy
| | - Gino Paolo Asuni
- Department of Life and Environment Sciences, Section of Neuroscience and Anthropology, University of Cagliari, Cagliari, Italy
| | - Giuseppe Talani
- Institute of Neuroscience-Cagliari, National Research Council, Cagliari, Italy
| | - Francesca Biggio
- Department of Life and Environment Sciences, Section of Neuroscience and Anthropology, University of Cagliari, Cagliari, Italy
| | | | - Mary Tresa Zanda
- Center for Substance Abuse Research, Lewis Katz School of Medicine, Temple University, Philadelphia, PA, United States
| | - Liliana Contu
- Department of Life and Environment Sciences, Section of Neuroscience and Anthropology, University of Cagliari, Cagliari, Italy
| | - Elisabetta Maciocco
- Institute of Neuroscience-Cagliari, National Research Council, Cagliari, Italy
| | - Mariangela Serra
- Department of Life and Environment Sciences, Section of Neuroscience and Anthropology, University of Cagliari, Cagliari, Italy
| | - Paolo Follesa
- Department of Life and Environment Sciences, Section of Neuroscience and Anthropology, University of Cagliari, Cagliari, Italy
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11
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Alcohol Use Disorder: Neurobiology and Therapeutics. Biomedicines 2022; 10:biomedicines10051192. [PMID: 35625928 PMCID: PMC9139063 DOI: 10.3390/biomedicines10051192] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2022] [Revised: 05/18/2022] [Accepted: 05/20/2022] [Indexed: 02/04/2023] Open
Abstract
Alcohol use disorder (AUD) encompasses the dysregulation of multiple brain circuits involved in executive function leading to excessive consumption of alcohol, despite negative health and social consequences and feelings of withdrawal when access to alcohol is prevented. Ethanol exerts its toxicity through changes to multiple neurotransmitter systems, including serotonin, dopamine, gamma-aminobutyric acid, glutamate, acetylcholine, and opioid systems. These neurotransmitter imbalances result in dysregulation of brain circuits responsible for reward, motivation, decision making, affect, and the stress response. Despite serious health and psychosocial consequences, this disorder still remains one of the leading causes of death globally. Treatment options include both psychological and pharmacological interventions, which are aimed at reducing alcohol consumption and/or promoting abstinence while also addressing dysfunctional behaviours and impaired functioning. However, stigma and social barriers to accessing care continue to impact many individuals. AUD treatment should focus not only on restoring the physiological and neurological impairment directly caused by alcohol toxicity but also on addressing psychosocial factors associated with AUD that often prevent access to treatment. This review summarizes the impact of alcohol toxicity on brain neurocircuitry in the context of AUD and discusses pharmacological and non-pharmacological therapies currently available to treat this addiction disorder.
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12
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Ashton MK, Rueda AVL, Ho AM, Noor Aizin NABM, Sharma H, Dodd PR, Stadlin A, Camarini R. Sex differences in GABA A receptor subunit transcript expression are mediated by genotype in subjects with alcohol-related cirrhosis of the liver. GENES, BRAIN, AND BEHAVIOR 2022; 21:e12785. [PMID: 35301805 PMCID: PMC9744570 DOI: 10.1111/gbb.12785] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/16/2021] [Revised: 11/17/2021] [Accepted: 11/18/2021] [Indexed: 11/29/2022]
Abstract
Male and female human subjects show contrasting propensities to misuse drugs of addiction, including alcohol. These differences lead to different psychological and neurological consequences, such as the likelihood of developing dependence. The pattern and extent of brain damage in alcohol-use disorder cases also varies with comorbid disease. To explore mechanisms that might underlie these outcomes, we used autopsy tissue to determine mRNA transcript expression in relation to genotype for two GABAA receptor subunit genes. We used quantitative Real-Time PCR to measure GABRA6 and GABRA2 mRNA concentrations in dorsolateral prefrontal and primary motor cortices of alcohol-use disorder subjects and controls of both sexes with and without liver disease who had been genotyped for these GABAA receptor subunit genes. Cirrhotic alcohol-use disorder cases had significantly higher expression of GABRA6 and GABRA2 transcripts than either controls or non-cirrhotic alcohol-use disorder cases. Differences were observed between sexes, genotypes and brain regions. We show that sex differences in subjects with GABRA6 and GABRA2 variants may contribute to differences in susceptibility to alcohol-use disorder and alcohol-induced cirrhosis.
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Affiliation(s)
- Madeline K. Ashton
- School of Chemistry and Molecular BiosciencesThe University of QueenslandBrisbaneQueenslandAustralia
| | - André V. L. Rueda
- School of Chemistry and Molecular BiosciencesThe University of QueenslandBrisbaneQueenslandAustralia
- Departamento de Farmacologia, ICBUniversidade de São PauloSão PauloBrazil
| | - Ada M.‐C. Ho
- School of Chemistry and Molecular BiosciencesThe University of QueenslandBrisbaneQueenslandAustralia
- Department of Psychiatry and PsychologyMayo ClinicRochesterMinnesotaUSA
| | - Noradibah Arina Binte M. Noor Aizin
- School of Chemistry and Molecular BiosciencesThe University of QueenslandBrisbaneQueenslandAustralia
- Vela Research Singapore Pte LtdThe KendallSingapore
| | - Hansa Sharma
- School of Chemistry and Molecular BiosciencesThe University of QueenslandBrisbaneQueenslandAustralia
| | - Peter R. Dodd
- School of Chemistry and Molecular BiosciencesThe University of QueenslandBrisbaneQueenslandAustralia
| | | | - Rosana Camarini
- Departamento de Farmacologia, ICBUniversidade de São PauloSão PauloBrazil
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13
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Engin E. GABA A receptor subtypes and benzodiazepine use, misuse, and abuse. Front Psychiatry 2022; 13:1060949. [PMID: 36713896 PMCID: PMC9879605 DOI: 10.3389/fpsyt.2022.1060949] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/04/2022] [Accepted: 12/29/2022] [Indexed: 01/14/2023] Open
Abstract
Benzodiazepines have been in use for over half a century. While they remain highly prescribed, their unfavorable side-effect profile and abuse liability motivated a search for alternatives. Most of these efforts focused on the development of benzodiazepine-like drugs that are selective for specific GABAA receptor subtypes. While there is ample evidence that subtype-selective GABAA receptor ligands have great potential for providing symptom relief without typical benzodiazepine side-effects, it is less clear whether subtype-selective targeting strategies can also reduce misuse and abuse potential. This review focuses on the three benzodiazepine properties that are relevant to the DSM-5-TR criteria for Sedative, Hypnotic, or Anxiolytic Use Disorder, namely, reinforcing properties of benzodiazepines, maladaptive behaviors related to benzodiazepine use, and benzodiazepine tolerance and dependence. We review existing evidence regarding the involvement of different GABAA receptor subtypes in each of these areas. The reviewed studies suggest that α1-containing GABAA receptors play an integral role in benzodiazepine-induced plasticity in reward-related brain areas and might be involved in the development of tolerance and dependence to benzodiazepines. However, a systematic comparison of the contributions of all benzodiazepine-sensitive GABAA receptors to these processes, a mechanistic understanding of how the positive modulation of each receptor subtype might contribute to the brain mechanisms underlying each of these processes, and a definitive answer to the question of whether specific chronic modulation of any given subtype would result in some or all of the benzodiazepine effects are currently lacking from the literature. Moreover, how non-selective benzodiazepines might lead to the maladaptive behaviors listed in DSM and how different GABAA receptor subtypes might be involved in the development of these behaviors remains unexplored. Considering the increasing burden of benzodiazepine abuse, the common practice of benzodiazepine misuse that leads to severe dependence, and the current efforts to generate side-effect free benzodiazepine alternatives, there is an urgent need for systematic, mechanistic research that provides a better understanding of the brain mechanisms of benzodiazepine misuse and abuse, including the involvement of specific GABAA receptor subtypes in these processes, to establish an informed foundation for preclinical and clinical efforts.
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Affiliation(s)
- Elif Engin
- Stress Neurobiology Laboratory, Division of Basic Neuroscience, McLean Hospital, Belmont, MA, United States.,Department of Psychiatry, Harvard Medical School, Boston, MA, United States
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14
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Belelli D, Hales TG, Lambert JJ, Luscher B, Olsen R, Peters JA, Rudolph U, Sieghart W. GABA A receptors in GtoPdb v.2021.3. IUPHAR/BPS GUIDE TO PHARMACOLOGY CITE 2021; 2021. [PMID: 35005623 DOI: 10.2218/gtopdb/f72/2021.3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The GABAA receptor is a ligand-gated ion channel of the Cys-loop family that includes the nicotinic acetylcholine, 5-HT3 and strychnine-sensitive glycine receptors. GABAA receptor-mediated inhibition within the CNS occurs by fast synaptic transmission, sustained tonic inhibition and temporally intermediate events that have been termed 'GABAA, slow' [45]. GABAA receptors exist as pentamers of 4TM subunits that form an intrinsic anion selective channel. Sequences of six α, three β, three γ, one δ, three ρ, one ε, one π and one θ GABAA receptor subunits have been reported in mammals [278, 235, 236, 283]. The π-subunit is restricted to reproductive tissue. Alternatively spliced versions of many subunits exist (e.g. α4- and α6- (both not functional) α5-, β2-, β3- and γ2), along with RNA editing of the α3 subunit [71]. The three ρ-subunits, (ρ1-3) function as either homo- or hetero-oligomeric assemblies [359, 50]. Receptors formed from ρ-subunits, because of their distinctive pharmacology that includes insensitivity to bicuculline, benzodiazepines and barbiturates, have sometimes been termed GABAC receptors [359], but they are classified as GABA A receptors by NC-IUPHAR on the basis of structural and functional criteria [16, 235, 236]. Many GABAA receptor subtypes contain α-, β- and γ-subunits with the likely stoichiometry 2α.2β.1γ [168, 235]. It is thought that the majority of GABAA receptors harbour a single type of α- and β - subunit variant. The α1β2γ2 hetero-oligomer constitutes the largest population of GABAA receptors in the CNS, followed by the α2β3γ2 and α3β3γ2 isoforms. Receptors that incorporate the α4- α5-or α 6-subunit, or the β1-, γ1-, γ3-, δ-, ε- and θ-subunits, are less numerous, but they may nonetheless serve important functions. For example, extrasynaptically located receptors that contain α6- and δ-subunits in cerebellar granule cells, or an α4- and δ-subunit in dentate gyrus granule cells and thalamic neurones, mediate a tonic current that is important for neuronal excitability in response to ambient concentrations of GABA [209, 272, 83, 19, 288]. GABA binding occurs at the β+/α- subunit interface and the homologous γ+/α- subunits interface creates the benzodiazepine site. A second site for benzodiazepine binding has recently been postulated to occur at the α+/β- interface ([254]; reviewed by [282]). The particular α-and γ-subunit isoforms exhibit marked effects on recognition and/or efficacy at the benzodiazepine site. Thus, receptors incorporating either α4- or α6-subunits are not recognised by 'classical' benzodiazepines, such as flunitrazepam (but see [356]). The trafficking, cell surface expression, internalisation and function of GABAA receptors and their subunits are discussed in detail in several recent reviews [52, 140, 188, 316] but one point worthy of note is that receptors incorporating the γ2 subunit (except when associated with α5) cluster at the postsynaptic membrane (but may distribute dynamically between synaptic and extrasynaptic locations), whereas as those incorporating the δ subunit appear to be exclusively extrasynaptic. NC-IUPHAR [16, 235, 3, 2] class the GABAA receptors according to their subunit structure, pharmacology and receptor function. Currently, eleven native GABAA receptors are classed as conclusively identified (i.e., α1β2γ2, α1βγ2, α3βγ2, α4βγ2, α4β2δ, α4β3δ, α5βγ2, α6βγ2, α6β2δ, α6β3δ and ρ) with further receptor isoforms occurring with high probability, or only tentatively [235, 236]. It is beyond the scope of this Guide to discuss the pharmacology of individual GABAA receptor isoforms in detail; such information can be gleaned in the reviews [16, 95, 168, 173, 143, 278, 216, 235, 236] and [9, 10]. Agents that discriminate between α-subunit isoforms are noted in the table and additional agents that demonstrate selectivity between receptor isoforms, for example via β-subunit selectivity, are indicated in the text below. The distinctive agonist and antagonist pharmacology of ρ receptors is summarised in the table and additional aspects are reviewed in [359, 50, 145, 223]. Several high-resolution cryo-electron microscopy structures have been described in which the full-length human α1β3γ2L GABAA receptor in lipid nanodiscs is bound to the channel-blocker picrotoxin, the competitive antagonist bicuculline, the agonist GABA (γ-aminobutyric acid), and the classical benzodiazepines alprazolam and diazepam [198].
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15
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Jin S, Cao Q, Yang F, Zhu H, Xu S, Chen Q, Wang Z, Lin Y, Cinar R, Pawlosky RJ, Zhang Y, Xiong W, Gao B, Koob GF, Lovinger DM, Zhang L. Brain ethanol metabolism by astrocytic ALDH2 drives the behavioural effects of ethanol intoxication. Nat Metab 2021; 3:337-351. [PMID: 33758417 PMCID: PMC8294184 DOI: 10.1038/s42255-021-00357-z] [Citation(s) in RCA: 50] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Accepted: 02/04/2021] [Indexed: 02/08/2023]
Abstract
Alcohol is among the most widely used psychoactive substances worldwide. Ethanol metabolites such as acetate, thought to be primarily the result of ethanol breakdown by hepatic aldehyde dehydrogenase 2 (ALDH2), contribute to alcohol's behavioural effects and alcoholism. Here, we show that ALDH2 is expressed in astrocytes in the mouse cerebellum and that ethanol metabolism by astrocytic ALDH2 mediates behavioural effects associated with ethanol intoxication. We show that ALDH2 is expressed in astrocytes in specific brain regions and that astrocytic, but not hepatocytic, ALDH2 is required to produce ethanol-derived acetate in the mouse cerebellum. Cerebellar astrocytic ALDH2 mediates low-dose ethanol-induced elevation of GABA levels, enhancement of tonic inhibition and impairment of balance and coordination skills. Thus, astrocytic ALDH2 controls the production, cellular and behavioural effects of alcohol metabolites in a brain-region-specific manner. Our data indicate that astrocytic ALDH2 is an important, but previously under-recognized, target in the brain to alter alcohol pharmacokinetics and potentially treat alcohol use disorder.
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Affiliation(s)
- Shiyun Jin
- Laboratory for Integrative Neuroscience, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, MD, USA
- Department of Anesthesiology, Second Affiliated Hospital, Anhui Medical University, Hefei, PR China
| | - Qi Cao
- Department of Diagnostic Radiology and Nuclear Medicine, University of Maryland, School of Medicine, Baltimore, MD, USA
| | - Fanghan Yang
- Laboratory for Integrative Neuroscience, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, MD, USA
| | - Hongying Zhu
- Department of Neuroscience, University of Science and Technology of China, Hefei, PR China
| | - Su Xu
- Department of Diagnostic Radiology and Nuclear Medicine, University of Maryland, School of Medicine, Baltimore, MD, USA
| | - Qi Chen
- Department of Neuroscience, University of Science and Technology of China, Hefei, PR China
| | - Ziyi Wang
- Department of Neuroscience, University of Science and Technology of China, Hefei, PR China
| | - Yuhong Lin
- Laboratory for Liver Diseases, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, MD, USA
| | - Resat Cinar
- Laboratory of Physiologic Studies, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, MD, USA
| | - Robert J Pawlosky
- Laboratory for Metabolic Control, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, MD, USA
| | - Ye Zhang
- Department of Anesthesiology, Second Affiliated Hospital, Anhui Medical University, Hefei, PR China
| | - Wei Xiong
- Department of Neuroscience, University of Science and Technology of China, Hefei, PR China
| | - Bin Gao
- Laboratory for Liver Diseases, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, MD, USA
| | - George F Koob
- National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD, USA
| | - David M Lovinger
- Laboratory for Integrative Neuroscience, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, MD, USA
| | - Li Zhang
- Laboratory for Integrative Neuroscience, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, MD, USA.
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16
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Chronic alcohol disrupts hypothalamic responses to stress by modifying CRF and NMDA receptor function. Neuropharmacology 2020; 167:107991. [PMID: 32059962 DOI: 10.1016/j.neuropharm.2020.107991] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2019] [Revised: 01/07/2020] [Accepted: 02/05/2020] [Indexed: 01/23/2023]
Abstract
The chronic inability of alcoholics to effectively cope with relapse-inducing stressors has been linked to dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis and corticotropin-releasing factor (CRF) signaling. However, the cellular mechanisms responsible for this dysregulation are yet to be identified. After exposure of male Sprague Dawley rats to chronic intermittent ethanol (CIE; 5-6 g/kg orally for 35 doses over 50 days) or water, followed by 40-60 days of protracted withdrawal, we investigated CIE effects on glutamatergic synaptic transmission, stress-induced plasticity, CRF- and ethanol-induced NMDAR inhibition using electrophysiological recordings in parvocellular neurosecretory cells (PNCs) of the paraventricular nucleus. We also assessed CIE effects on hypothalamic mRNA expression of CRF-related genes using real-time polymerase chain reaction, and on HPA axis function by measuring stress-induced increases in plasma adrenocorticotropic hormone, corticosterone, and self-grooming. In control rats, ethanol-mediated inhibition of NMDARs was prevented by CRF1 receptor (CRFR1) blockade with antalarmin, while CRF/CRFR1-mediated NMDAR blockade was prevented by intracellularly-applied inhibitor of phosphatases PP1/PP2A, okadaic acid, but not the selective striatal-enriched tyrosine protein phosphatase inhibitor, TC-2153. CIE exposure increased GluN2B subunit-dependent NMDAR function of PNCs. This was associated with the loss of both ethanol- and CRF-mediated NMDAR inhibition, and loss of stress-induced short-term potentiation of glutamatergic synaptic inputs, which could be reversed by intracellular blockade of NMDARs with MK801. CIE exposure also blunted the hormonal and self-grooming behavioral responses to repeated restraint stress. These findings suggest a cellular mechanism whereby chronic alcohol dysregulates the hormonal and behavioral responses to repetitive stressors by increasing NMDAR function and decreasing CRFR1 function.
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17
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Bandiera S, Almeida FB, Hansen AW, Pulcinelli RR, Caletti G, de Paula LF, Nin MS, Fontella FU, Almeida RF, Tannhauser Barros HM, Gomez R. Combined use of alcohol and cigarette increases locomotion and glutamate levels in the cerebrospinal fluid without changes on GABAA or NMDA receptor subunit mRNA expression in the hippocampus of rats. Behav Brain Res 2020; 380:112444. [DOI: 10.1016/j.bbr.2019.112444] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2019] [Revised: 11/18/2019] [Accepted: 12/18/2019] [Indexed: 10/25/2022]
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18
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Morrow AL, Boero G, Porcu P. A Rationale for Allopregnanolone Treatment of Alcohol Use Disorders: Basic and Clinical Studies. Alcohol Clin Exp Res 2020; 44:320-339. [PMID: 31782169 PMCID: PMC7018555 DOI: 10.1111/acer.14253] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2019] [Accepted: 11/19/2019] [Indexed: 12/17/2022]
Abstract
For many years, research from around the world has suggested that the neuroactive steroid (3α,5α)-3-hydroxypregnan-20-one (allopregnanolone or 3α,5α-THP) may have therapeutic potential for treatment of various symptoms of alcohol use disorders (AUDs). In this critical review, we systematically address all the evidence that supports such a suggestion, delineate the etiologies of AUDs that are addressed by treatment with allopregnanolone or its precursor pregnenolone, and the rationale for treatment of various components of the disease based on basic science and clinical evidence. This review presents a theoretical framework for understanding how endogenous steroids that regulate the effects of stress, alcohol, and the innate immune system could play a key role in both the prevention and the treatment of AUDs. We further discuss cautions and limitations of allopregnanolone or pregnenolone therapy with suggestions regarding the management of risk and the potential for helping millions who suffer from AUDs.
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Affiliation(s)
- A. Leslie Morrow
- Department of Psychiatry, Department of Pharmacology, Bowles Center for Alcohol Studies, University of North Carolina at Chapel Hill, School of Medicine, Chapel Hill, NC 27599
| | - Giorgia Boero
- Department of Psychiatry, Department of Pharmacology, Bowles Center for Alcohol Studies, University of North Carolina at Chapel Hill, School of Medicine, Chapel Hill, NC 27599
| | - Patrizia Porcu
- Neuroscience Institute, National Research Council of Italy (CNR), Cagliari, Italy
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Roberts AJ, Khom S, Bajo M, Vlkolinsky R, Polis I, Cates-Gatto C, Roberto M, Gruol DL. Increased IL-6 expression in astrocytes is associated with emotionality, alterations in central amygdala GABAergic transmission, and excitability during alcohol withdrawal. Brain Behav Immun 2019; 82:188-202. [PMID: 31437534 PMCID: PMC6800653 DOI: 10.1016/j.bbi.2019.08.185] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/15/2019] [Revised: 08/16/2019] [Accepted: 08/17/2019] [Indexed: 01/14/2023] Open
Abstract
Accumulating evidence from preclinical and clinical studies has implicated a role for the cytokine IL-6 in a variety of CNS diseases including anxiety-like and depressive-like behaviors, as well as alcohol use disorder. Here we use homozygous and heterozygous transgenic mice expressing elevated levels of IL-6 in the CNS due to increased astrocyte expression and non-transgenic littermates to examine a role for astrocyte-produced IL-6 in emotionality (response to novelty, anxiety-like, and depressive-like behaviors). Our results from homozygous IL-6 mice in a variety of behavioral tests (light/dark transfer, open field, digging, tail suspension, and forced swim tests) support a role for IL-6 in stress-coping behaviors. Ex vivo electrophysiological studies of neuronal excitability and inhibitory GABAergic synaptic transmission in the central nucleus of the amygdala (CeA) of the homozygous transgenic mice revealed increased inhibitory GABAergic signaling and increased excitability of CeA neurons, suggesting a role for astrocyte produced IL-6 in the amygdala in exploratory drive and depressive-like behavior. Furthermore, studies in the hippocampus of activation/expression of proteins associated with IL-6 signal transduction and inhibitory GABAergic mechanisms support a role for astrocyte produced IL-6 in depressive-like behaviors. Our studies indicate a complex and dose-dependent relationship between IL-6 and behavior and implicate IL-6 induced neuroadaptive changes in neuronal excitability and the inhibitory GABAergic system as important contributors to altered behavior associated with IL-6 expression in the CNS.
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Affiliation(s)
- Amanda J. Roberts
- Animal Models Core Facility, The Scripps Research Institute, La Jolla, CA 92037 U.S.A
| | - Sophia Khom
- Neuroscience Department, The Scripps Research Institute, La Jolla, CA 92037 U.S.A
| | - Michal Bajo
- Neuroscience Department, The Scripps Research Institute, La Jolla, CA 92037 U.S.A
| | - Roman Vlkolinsky
- Neuroscience Department, The Scripps Research Institute, La Jolla, CA 92037 U.S.A
| | - Ilham Polis
- Animal Models Core Facility, The Scripps Research Institute, La Jolla, CA 92037 U.S.A
| | - Chelsea Cates-Gatto
- Animal Models Core Facility, The Scripps Research Institute, La Jolla, CA 92037 U.S.A
| | - Marisa Roberto
- Neuroscience Department, The Scripps Research Institute, La Jolla, CA 92037 U.S.A
| | - Donna L. Gruol
- Neuroscience Department, The Scripps Research Institute, La Jolla, CA 92037 U.S.A,Corresponding Author: Dr. Donna L. Gruol, Neuroscience Department, SP30-1522, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, Phone: (858) 784-7060, Fax: (858) 784-7393,
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20
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Gao F, Chen D, Ma X, Sudweeks S, Yorgason JT, Gao M, Turner D, Eaton JB, McIntosh JM, Lukas RJ, Whiteaker P, Chang Y, Steffensen SC, Wu J. Alpha6-containing nicotinic acetylcholine receptor is a highly sensitive target of alcohol. Neuropharmacology 2019; 149:45-54. [PMID: 30710570 PMCID: PMC7323585 DOI: 10.1016/j.neuropharm.2019.01.021] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2018] [Revised: 01/01/2019] [Accepted: 01/17/2019] [Indexed: 02/05/2023]
Abstract
Alcohol use disorder (AUD) is a serious public health problem that results in tremendous social, legal and medical costs to society. Unlike other addictive drugs, there is no specific molecular target for ethanol (EtOH). Here, we report a novel molecular target that mediates EtOH effects at concentrations below those that cause legally-defined inebriation. Using patch-clamp recording of human α6*-nicotinic acetylcholine receptor (α6*-nAChR) function when heterologously expressed in SH-EP1 human epithelial cells, we found that 0.1-5 mM EtOH significantly enhances α6*-nAChR-mediated currents with effects that are dependent on both EtOH and nicotine concentrations. EtOH exposure increased both whole-cell current rising slope and decay constants. This EtOH modulation was selective for α6*-nAChRs since it did not affect α3β4-, α4β2-, or α7-nAChRs. In addition, 5 mM EtOH also increased the frequency and amplitude of dopaminergic neuron transients in mouse brain nucleus accumbens slices, that were blocked by the α6*-nAChR antagonist, α-conotoxin MII, suggesting a role for native α6*-nAChRs in low-dose EtOH effects. Collectively, our data suggest that α6*-nAChRs are sensitive targets mediating low-dose EtOH effects through a positive allosteric mechanism, which provides new insight into mechanisms involved in pharmacologically-relevant alcohol effects contributing to AUD.
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Affiliation(s)
- Fenfei Gao
- Department of Pharmacology, Shantou University Medical College, Shantou, Guangdong, 51504, China; Division of Neurobiology, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, AZ, 85013, USA
| | - Dejie Chen
- Division of Neurobiology, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, AZ, 85013, USA; Department of Neurology, Yunfu People's Hospital, Yunfu, Guangdong, 527300, China
| | - Xiaokuang Ma
- Department of Pharmacology, Shantou University Medical College, Shantou, Guangdong, 51504, China; Division of Neurobiology, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, AZ, 85013, USA
| | - Sterling Sudweeks
- Department of Physiology and Developmental Biology, Brigham Young University, Provo, UT, 84602, USA
| | - Jordan T Yorgason
- Department of Psychology and Neuroscience, Brigham Young University, Provo, UT, 84602, USA
| | - Ming Gao
- Division of Neurobiology, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, AZ, 85013, USA
| | - Dharshaun Turner
- Division of Neurobiology, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, AZ, 85013, USA
| | - Jason Brek Eaton
- Division of Neurobiology, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, AZ, 85013, USA
| | - J Michael McIntosh
- George E. Wahlen Veterans Affairs Medical Center, Salt Lake City, UT, USA 84108, USA
| | - Ronald J Lukas
- Division of Neurobiology, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, AZ, 85013, USA
| | - Paul Whiteaker
- Division of Neurobiology, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, AZ, 85013, USA
| | - Yongchang Chang
- Division of Neurobiology, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, AZ, 85013, USA
| | - Scott C Steffensen
- Department of Psychology and Neuroscience, Brigham Young University, Provo, UT, 84602, USA
| | - Jie Wu
- Department of Pharmacology, Shantou University Medical College, Shantou, Guangdong, 51504, China; Division of Neurobiology, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, AZ, 85013, USA; Department of Neurology, Yunfu People's Hospital, Yunfu, Guangdong, 527300, China.
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21
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Melón LC, Nasman JT, John AS, Mbonu K, Maguire JL. Interneuronal δ-GABA A receptors regulate binge drinking and are necessary for the behavioral effects of early withdrawal. Neuropsychopharmacology 2019; 44:425-434. [PMID: 30089884 PMCID: PMC6300562 DOI: 10.1038/s41386-018-0164-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/23/2018] [Revised: 07/16/2018] [Accepted: 07/20/2018] [Indexed: 12/12/2022]
Abstract
Extensive evidence points to a role for GABAergic signaling in the amygdala in mediating the effects of alcohol, including presynaptic changes in GABA release, suggesting effects on GABAergic neurons. However, the majority of studies focus solely on the effects of alcohol on principal neurons. Here we demonstrate that δ-GABAARs, which have been suggested to confer ethanol sensitivity, are expressed at a high density on parvalbumin (PV) interneurons in the basolateral amygdala (BLA). Thus, we hypothesized that δ-GABAARs on PV interneurons may represent both an initial pharmacological target for alcohol and a site for plasticity associated with the expression of various behavioral maladaptations during withdrawal from binge drinking. To investigate this, we used a mouse model of voluntary alcohol intake (Drinking-in-the-Dark-Multiple Scheduled Access) to induce escalating heavy binge drinking and anxiety-like behavior in mice. This pattern of intake was associated with increased δ protein expression on parvalbumin positive interneurons in both the BLA and hippocampus. Loss of δ-GABAARs specifically in PV interneurons (PV:δ-/-) increased binge drinking behavior, reduced sensitivity to alcohol-induced motor incoordination, enhanced sensitivity to alcohol-induced hyperlocomotion and blocked the expression of withdrawal from binge drinking. This study is the first to demonstrate a role for δGABAARs specifically in PV-expressing interneurons in modulating binge alcohol intake and withdrawal-induced anxiety.
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Affiliation(s)
- Laverne C. Melón
- 0000 0000 8934 4045grid.67033.31Department of Neuroscience, Tufts University School of Medicine, Boston, MA 02111 USA
| | - James T. Nasman
- 0000 0000 8934 4045grid.67033.31Building Diversity in Biomedical Sciences, Tufts University School of Medicine, Boston, MA 02111 USA
| | - Ashley St. John
- 0000 0000 8934 4045grid.67033.31Building Diversity in Biomedical Sciences, Tufts University School of Medicine, Boston, MA 02111 USA
| | - Kenechukwu Mbonu
- 0000 0000 8934 4045grid.67033.31Building Diversity in Biomedical Sciences, Tufts University School of Medicine, Boston, MA 02111 USA
| | - Jamie L. Maguire
- 0000 0000 8934 4045grid.67033.31Department of Neuroscience, Tufts University School of Medicine, Boston, MA 02111 USA
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Nipper MA, Jensen JP, Helms ML, Ford MM, Crabbe JC, Rossi DJ, Finn DA. Genotype Differences in Sensitivity to the Anticonvulsant Effect of the Synthetic Neurosteroid Ganaxolone during Chronic Ethanol Withdrawal. Neuroscience 2018; 397:127-137. [PMID: 30513375 DOI: 10.1016/j.neuroscience.2018.11.045] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2018] [Revised: 11/26/2018] [Accepted: 11/28/2018] [Indexed: 01/05/2023]
Abstract
Sensitivity to anticonvulsant effects of the γ-aminobutyric acidA receptor-active neurosteroid allopregnanolone (ALLO) during ethanol withdrawal varies across genotypes, with high sensitivity in genotypes with mild withdrawal and low sensitivity in genotypes with high withdrawal. The present studies determined whether the resistance to ALLO during withdrawal in mouse genotypes with high handling-induced convulsions (HICs) during withdrawal could be overcome with use of ganaxolone (GAN), the metabolically stable derivative of ALLO. In separate studies, male and female Withdrawal Seizure-Prone (WSP-1) and DBA/2J (D2) mice were exposed to air (controls) or 72-h ethanol vapor and then were scored for HICs during withdrawal (hourly for the first 12 h, then at hours 24 and 25). After the HIC scoring at hours 5 and 9, mice were injected with 10 mg/kg GAN or vehicle. Area under the HIC curve (AUC) for hours 5-12 was analyzed. In control WSP-1 mice, GAN significantly reduced AUC by 52% (males) and 63% (females), with effects that were absent or substantially reduced during withdrawal. In contrast, GAN significantly reduced AUC in both control and ethanol-withdrawing male and female D2 mice. AUC was decreased by 81% (males) and 70% (females) in controls and by 35% (males) and 21% (females) during withdrawal. The significant anticonvulsant effect of GAN during withdrawal in D2 but not WSP-1 mice suggests that different mechanisms may contribute to ALLO insensitivity during withdrawal in these two genotypes. Importantly, the results in D2 mice suggest that GAN may be a useful treatment for ethanol withdrawal-induced seizures.
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Affiliation(s)
- Michelle A Nipper
- Department of Behavioral Neuroscience, Oregon Health & Science University, Portland, OR 97239, United States.
| | - Jeremiah P Jensen
- Department of Behavioral Neuroscience, Oregon Health & Science University, Portland, OR 97239, United States
| | - Melinda L Helms
- Department of Behavioral Neuroscience, Oregon Health & Science University, Portland, OR 97239, United States
| | - Matthew M Ford
- Department of Behavioral Neuroscience, Oregon Health & Science University, Portland, OR 97239, United States; Division of Neuroscience, Oregon National Primate Research Center, Oregon Health & Science University, Beaverton, OR 97006, United States
| | - John C Crabbe
- Department of Behavioral Neuroscience, Oregon Health & Science University, Portland, OR 97239, United States; Portland Alcohol Research Center, VA Portland Health Care System, Portland, OR 97239, United States
| | - David J Rossi
- Department of Behavioral Neuroscience, Oregon Health & Science University, Portland, OR 97239, United States; Department of Integrative Physiology and Neuroscience, Washington State University, Pullman, WA 99164, United States
| | - Deborah A Finn
- Department of Behavioral Neuroscience, Oregon Health & Science University, Portland, OR 97239, United States; Portland Alcohol Research Center, VA Portland Health Care System, Portland, OR 97239, United States
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23
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Gravielle MC. Regulation of GABAA receptors by prolonged exposure to endogenous and exogenous ligands. Neurochem Int 2018; 118:96-104. [DOI: 10.1016/j.neuint.2018.05.015] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2018] [Revised: 05/22/2018] [Accepted: 05/30/2018] [Indexed: 02/08/2023]
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24
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Olsen RW. GABA A receptor: Positive and negative allosteric modulators. Neuropharmacology 2018; 136:10-22. [PMID: 29407219 PMCID: PMC6027637 DOI: 10.1016/j.neuropharm.2018.01.036] [Citation(s) in RCA: 185] [Impact Index Per Article: 30.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2017] [Revised: 01/23/2018] [Accepted: 01/25/2018] [Indexed: 12/11/2022]
Abstract
gamma-Aminobutyric acid (GABA)-mediated inhibitory neurotransmission and the gene products involved were discovered during the mid-twentieth century. Historically, myriad existing nervous system drugs act as positive and negative allosteric modulators of these proteins, making GABA a major component of modern neuropharmacology, and suggesting that many potential drugs will be found that share these targets. Although some of these drugs act on proteins involved in synthesis, degradation, and membrane transport of GABA, the GABA receptors Type A (GABAAR) and Type B (GABABR) are the targets of the great majority of GABAergic drugs. This discovery is due in no small part to Professor Norman Bowery. Whereas the topic of GABABR is appropriately emphasized in this special issue, Norman Bowery also made many insights into GABAAR pharmacology, the topic of this article. GABAAR are members of the ligand-gated ion channel receptor superfamily, a chloride channel family of a dozen or more heteropentameric subtypes containing 19 possible different subunits. These subtypes show different brain regional and subcellular localization, age-dependent expression, and potential for plastic changes with experience including drug exposure. Not only are GABAAR the targets of agonist depressants and antagonist convulsants, but most GABAAR drugs act at other (allosteric) binding sites on the GABAAR proteins. Some anxiolytic and sedative drugs, like benzodiazepine and related drugs, act on GABAAR subtype-dependent extracellular domain sites. General anesthetics including alcohols and neurosteroids act at GABAAR subunit-interface trans-membrane sites. Ethanol at high anesthetic doses acts on GABAAR subtype-dependent trans-membrane domain sites. Ethanol at low intoxicating doses acts at GABAAR subtype-dependent extracellular domain sites. Thus GABAAR subtypes possess pharmacologically specific receptor binding sites for a large group of different chemical classes of clinically important neuropharmacological agents. This article is part of the "Special Issue Dedicated to Norman G. Bowery".
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Affiliation(s)
- Richard W Olsen
- Department of Molecular & Medical Pharmacology, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA.
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25
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Histone deacetylases mediate GABA A receptor expression, physiology, and behavioral maladaptations in rat models of alcohol dependence. Neuropsychopharmacology 2018; 43. [PMID: 29520058 PMCID: PMC5983537 DOI: 10.1038/s41386-018-0034-8] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Alcohol use disorders are chronic debilitating diseases characterized by severe withdrawal symptoms that contribute to morbidity and relapse. GABAA receptor (GABAAR) adaptations have long been implicated in the chronic effects of alcohol and contribute to many withdrawal symptoms associated with alcohol dependence. In rodents, GABAAR hypofunction results from decreases in Gabra1 expression, although the underlying mechanism controlling Gabra1 expression after chronic ethanol exposure is still unknown. We found that chronic ethanol exposure using either ethanol gavage or two-bottle choice voluntary access paradigms decreased Gabra1 expression and increased Hdac2 and Hdac3 expression. Administration of the HDAC inhibitor trichostatin A (TSA) after chronic ethanol exposure prevents the decrease in Gabra1 expression and function as well as the increase in Hdac2 and Hdac3 expression in both the cortex and the medial prefrontal cortex (mPFC). Chronic ethanol exposure and withdrawal, but not acute ethanol exposure or acute withdrawal, cause a selective upregulation of HDAC2 and HDAC3 associated with the Gabra1 promoter that accompanies a decrease in H3 acetylation of the Gabra1 promoter and the reduction in GABAAR α1 subunit expression. TSA administration prevented each of these molecular events as well as behavioral manifestations of ethanol dependence, including tolerance to zolpidem-induced loss of righting reflex, reduced open-arm time in the elevated plus maze, reduced center-time and locomotor activity in the open-field assay, and TSA reduced voluntary ethanol consumption. The results show how chronic ethanol exposure regulates the highly prominent GABAAR α1 subunit by an epigenetic mechanism that represents a potential treatment modality for alcohol dependence.
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26
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Chen J, He Y, Wu Y, Zhou H, Su LD, Li WN, Olsen RW, Liang J, Zhou YD, Shen Y. Single Ethanol Withdrawal Regulates Extrasynaptic δ-GABA A Receptors Via PKCδ Activation. Front Mol Neurosci 2018; 11:141. [PMID: 29755316 PMCID: PMC5932167 DOI: 10.3389/fnmol.2018.00141] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2017] [Accepted: 04/09/2018] [Indexed: 11/23/2022] Open
Abstract
Alcohol (ethanol, EtOH) is one of the most widely abused drugs with profound effects on brain function and behavior. GABAA receptors (GABAARs) are one of the major targets for EtOH in the brain. Temporary plastic changes in GABAARs after withdrawal from a single EtOH exposure occur both in vivo and in vitro, which may be the basis for chronic EtOH addiction, tolerance and withdrawal symptoms. Extrasynaptic δ-GABAAR endocytosis is implicated in EtOH-induced GABAAR plasticity, but the mechanisms by which the relative abundance and localization of specific GABAARs are altered by EtOH exposure and withdrawal remain unclear. In this study, we investigated the mechanisms underlying rapid regulation of extrasynaptic δ-GABAAR by a single EtOH withdrawal in cultured rat hippocampal neurons. Thirty-minutes EtOH (60 mM) exposure increased extrasynaptic tonic current (Itonic) amplitude without affecting synaptic GABAAR function in neurons. In contrast, at 30 min after withdrawal, Itonic amplitude and responsiveness to acute EtOH were both reduced. Similar results occurred in neurons with okadaic acid (OA) or phorbol 12,13-dibutyrate (PDBu) exposure. Protein kinase C (PKC) inhibition prevented the reduction of Itonic amplitude and the tolerance to acute EtOH, as well as the reduction of GABAAR-δ subunit abundance induced by a single EtOH withdrawal. Moreover, EtOH withdrawal selectively increased PKCδ level, whereas PKCδ inhibition specifically rescued the EtOH-induced alterations in GABAAR-δ subunit level and δ-GABAAR function. Together, we provided strong evidence for the important roles of PKCδ in the rapid regulation of extrasynaptic δ-GABAAR induced by a single EtOH withdrawal.
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Affiliation(s)
- Juan Chen
- Department of Neurobiology, Institute of Neuroscience, Key Laboratory of Medical Neurobiology of the Ministry of Health of China, Zhejiang University School of Medicine, Hangzhou, China
| | - Yang He
- Department of Neurobiology, Institute of Neuroscience, Key Laboratory of Medical Neurobiology of the Ministry of Health of China, Zhejiang University School of Medicine, Hangzhou, China
| | - Yan Wu
- Department of Neurobiology, Institute of Neuroscience, Key Laboratory of Medical Neurobiology of the Ministry of Health of China, Zhejiang University School of Medicine, Hangzhou, China
| | - Hang Zhou
- Department of Neurobiology, Institute of Neuroscience, Key Laboratory of Medical Neurobiology of the Ministry of Health of China, Zhejiang University School of Medicine, Hangzhou, China
| | - Li-Da Su
- Neuroscience Care Unit, Second Affiliated Hospital of Zhejiang University School of Medicine, Hangzhou, China
| | - Wei-Nan Li
- Department of Neurobiology, Institute of Neuroscience, Key Laboratory of Medical Neurobiology of the Ministry of Health of China, Zhejiang University School of Medicine, Hangzhou, China
| | - Richard W Olsen
- Department of Molecular & Medical Pharmacology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, United States
| | - Jing Liang
- Titus Family Department of Clinical Pharmacy, USC School of Pharmacy, University of Southern California, Los Angeles, CA, United States
| | - Yu-Dong Zhou
- Department of Neurobiology, Institute of Neuroscience, Key Laboratory of Medical Neurobiology of the Ministry of Health of China, Zhejiang University School of Medicine, Hangzhou, China
| | - Yi Shen
- Department of Neurobiology, Institute of Neuroscience, Key Laboratory of Medical Neurobiology of the Ministry of Health of China, Zhejiang University School of Medicine, Hangzhou, China
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27
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The Cerebellar GABA AR System as a Potential Target for Treating Alcohol Use Disorder. Handb Exp Pharmacol 2018; 248:113-156. [PMID: 29736774 DOI: 10.1007/164_2018_109] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
In the brain, fast inhibitory neurotransmission is mediated primarily by the ionotropic subtype of the gamma-aminobutyric acid (GABA) receptor subtype A (GABAAR). It is well established that the brain's GABAAR system mediates many aspects of neurobehavioral responses to alcohol (ethanol; EtOH). Accordingly, in both preclinical studies and some clinical scenarios, pharmacologically targeting the GABAAR system can alter neurobehavioral responses to acute and chronic EtOH consumption. However, many of the well-established interactions of EtOH and the GABAAR system have been identified at concentrations of EtOH ([EtOH]) that would only occur during abusive consumption of EtOH (≥40 mM), and there are still inadequate treatment options for prevention of or recovery from alcohol use disorder (AUD, including abuse and dependence). Accordingly, there is a general acknowledgement that more research is needed to identify and characterize: (1) neurobehavioral targets of lower [EtOH] and (2) associated brain structures that would involve such targets in a manner that may influence the development and maintenance of AUDs.Nearly 15 years ago it was discovered that the GABAAR system of the cerebellum is highly sensitive to EtOH, responding to concentrations as low as 10 mM (as would occur in the blood of a typical adult human after consuming 1-2 standard units of EtOH). This high sensitivity to EtOH, which likely mediates the well-known motor impairing effects of EtOH, combined with recent advances in our understanding of the role of the cerebellum in non-motor, cognitive/emotive/reward processes has renewed interest in this system in the specific context of AUD. In this chapter we will describe recent advances in our understanding of cerebellar processing, actions of EtOH on the cerebellar GABAAR system, and the potential relationship of such actions to the development of AUD. We will finish with speculation about how cerebellar specific GABAAR ligands might be effective pharmacological agents for treating aspects of AUD.
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28
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Abrahao KP, Salinas AG, Lovinger DM. Alcohol and the Brain: Neuronal Molecular Targets, Synapses, and Circuits. Neuron 2017; 96:1223-1238. [PMID: 29268093 PMCID: PMC6566861 DOI: 10.1016/j.neuron.2017.10.032] [Citation(s) in RCA: 247] [Impact Index Per Article: 35.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2017] [Revised: 09/30/2017] [Accepted: 10/27/2017] [Indexed: 12/13/2022]
Abstract
Ethanol is one of the most commonly abused drugs. Although environmental and genetic factors contribute to the etiology of alcohol use disorders, it is ethanol's actions in the brain that explain (1) acute ethanol-related behavioral changes, such as stimulant followed by depressant effects, and (2) chronic changes in behavior, including escalated use, tolerance, compulsive seeking, and dependence. Our knowledge of ethanol use and abuse thus relies on understanding its effects on the brain. Scientists have employed both bottom-up and top-down approaches, building from molecular targets to behavioral analyses and vice versa, respectively. This review highlights current progress in the field, focusing on recent and emerging molecular, cellular, and circuit effects of the drug that impact ethanol-related behaviors. The focus of the field is now on pinpointing which molecular effects in specific neurons within a brain region contribute to behavioral changes across the course of acute and chronic ethanol exposure.
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Affiliation(s)
- Karina P Abrahao
- Laboratory for Integrative Neuroscience, Division of Intramural Clinical and Biological Research, National Institute on Alcohol Abuse and Alcoholism, NIH, Bethesda, MD 20892, USA
| | - Armando G Salinas
- Laboratory for Integrative Neuroscience, Division of Intramural Clinical and Biological Research, National Institute on Alcohol Abuse and Alcoholism, NIH, Bethesda, MD 20892, USA
| | - David M Lovinger
- Laboratory for Integrative Neuroscience, Division of Intramural Clinical and Biological Research, National Institute on Alcohol Abuse and Alcoholism, NIH, Bethesda, MD 20892, USA.
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29
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Olsen RW, Liang J. Role of GABA A receptors in alcohol use disorders suggested by chronic intermittent ethanol (CIE) rodent model. Mol Brain 2017; 10:45. [PMID: 28931433 PMCID: PMC5605989 DOI: 10.1186/s13041-017-0325-8] [Citation(s) in RCA: 71] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2017] [Accepted: 09/05/2017] [Indexed: 11/10/2022] Open
Abstract
GABAergic inhibitory transmission is involved in the acute and chronic effects of ethanol on the brain and behavior. One-dose ethanol exposure induces transient plastic changes in GABAA receptor subunit levels, composition, and regional and subcellular localization. Rapid down-regulation of early responder δ subunit-containing GABAA receptor subtypes mediating ethanol-sensitive tonic inhibitory currents in critical neuronal circuits corresponds to rapid tolerance to ethanol's behavioral responses. Slightly slower, α1 subunit-containing GABAA receptor subtypes mediating ethanol-insensitive synaptic inhibition are down-regulated, corresponding to tolerance to additional ethanol behaviors plus cross-tolerance to other GABAergic drugs including benzodiazepines, anesthetics, and neurosteroids, especially sedative-hypnotic effects. Compensatory up-regulation of synaptically localized α4 and α2 subunit-containing GABAA receptor subtypes, mediating ethanol-sensitive synaptic inhibitory currents follow, but exhibit altered physio-pharmacology, seizure susceptibility, hyperexcitability, anxiety, and tolerance to GABAergic positive allosteric modulators, corresponding to heightened alcohol withdrawal syndrome. All these changes (behavioral, physiological, and biochemical) induced by ethanol administration are transient and return to normal in a few days. After chronic intermittent ethanol (CIE) treatment the same changes are observed but they become persistent after 30 or more doses, lasting for at least 120 days in the rat, and probably for life. We conclude that the ethanol-induced changes in GABAA receptors represent aberrant plasticity contributing critically to ethanol dependence and increased voluntary consumption. We suggest that the craving, drug-seeking, and increased consumption in the rat model are tied to ethanol-induced plastic changes in GABAA receptors, importantly the development of ethanol-sensitive synaptic GABAA receptor-mediating inhibitory currents that participate in maintained positive reward actions of ethanol on critical neuronal circuits. These probably disinhibit nerve endings of inhibitory GABAergic neurons on dopamine reward circuit cells, and limbic system circuits mediating anxiolysis in hippocampus and amygdala. We further suggest that the GABAA receptors contributing to alcohol dependence in the rat and presumably in human alcohol use disorders (AUD) are the ethanol-induced up-regulated subtypes containing α4 and most importantly α2 subunits. These mediate critical aspects of the positive reinforcement of ethanol in the dependent chronic user while alleviating heightened withdrawal symptoms experienced whenever ethanol is absent. The speculative conclusions based on firm observations are readily testable.
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Affiliation(s)
- Richard W. Olsen
- Department of Molecular and Medical Pharmacology, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095 USA
| | - Jing Liang
- Department of Molecular and Medical Pharmacology, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095 USA
- Titus Family Department of Clinical Pharmacy, School of Pharmacy, University of Southern California, Los Angeles, CA 90089 USA
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30
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Martenson JS, Yamasaki T, Chaudhury NH, Albrecht D, Tomita S. Assembly rules for GABA A receptor complexes in the brain. eLife 2017; 6:27443. [PMID: 28816653 PMCID: PMC5577914 DOI: 10.7554/elife.27443] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2017] [Accepted: 08/04/2017] [Indexed: 12/15/2022] Open
Abstract
GABAA receptor (GABAAR) pentamers are assembled from a pool of 19 subunits, and variety in subunit combinations diversifies GABAAR functions to tune brain activity. Pentamers with distinct subunit compositions localize differentially at synaptic and non-synaptic sites to mediate phasic and tonic inhibition, respectively. Despite multitudes of theoretical permutations, limited subunit combinations have been identified in the brain. Currently, no molecular model exists for combinatorial GABAAR assembly in vivo. Here, we reveal assembly rules of native GABAAR complexes that explain GABAAR subunit subcellular distributions using mice and Xenopus laevis oocytes. First, α subunits possess intrinsic signals to segregate into distinct pentamers. Second, γ2 is essential for GABAAR assembly with Neuroligin-2 (NL2) and GARLHs, which localize GABAARs at synapses. Third, δ suppresses α6 synaptic localization by preventing assembly with GARLHs/NL2. These findings establish the first molecular model for combinatorial GABAAR assembly in vivo and reveal an assembly pathway regulating GABAAR synaptic localization.
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Affiliation(s)
- James S Martenson
- Department of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, United States.,Department of Neuroscience, Program in Cellular Neuroscience, Neurodegeneration and Repair, Interdepartmental Neuroscience Program, Yale University School of Medicine, New Haven, United States
| | - Tokiwa Yamasaki
- Department of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, United States.,Department of Neuroscience, Program in Cellular Neuroscience, Neurodegeneration and Repair, Interdepartmental Neuroscience Program, Yale University School of Medicine, New Haven, United States
| | - Nashid H Chaudhury
- Department of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, United States.,Department of Neuroscience, Program in Cellular Neuroscience, Neurodegeneration and Repair, Interdepartmental Neuroscience Program, Yale University School of Medicine, New Haven, United States
| | - David Albrecht
- Department of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, United States.,Department of Neuroscience, Program in Cellular Neuroscience, Neurodegeneration and Repair, Interdepartmental Neuroscience Program, Yale University School of Medicine, New Haven, United States
| | - Susumu Tomita
- Department of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, United States.,Department of Neuroscience, Program in Cellular Neuroscience, Neurodegeneration and Repair, Interdepartmental Neuroscience Program, Yale University School of Medicine, New Haven, United States
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31
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Decreased surface expression of the δ subunit of the GABA A receptor contributes to reduced tonic inhibition in dentate granule cells in a mouse model of fragile X syndrome. Exp Neurol 2017; 297:168-178. [PMID: 28822839 DOI: 10.1016/j.expneurol.2017.08.008] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2017] [Revised: 07/21/2017] [Accepted: 08/15/2017] [Indexed: 11/22/2022]
Abstract
While numerous changes in the GABA system have been identified in models of Fragile X Syndrome (FXS), alterations in subunits of the GABAA receptors (GABAARs) that mediate tonic inhibition are particularly intriguing. Considering the key role of tonic inhibition in controlling neuronal excitability, reduced tonic inhibition could contribute to FXS-associated disorders such as hyperactivity, hypersensitivity, and increased seizure susceptibility. The current study has focused on the expression and function of the δ subunit of the GABAAR, a major subunit involved in tonic inhibition, in granule cells of the dentate gyrus in the Fmr1 knockout (KO) mouse model of FXS. Electrophysiological studies of dentate granule cells revealed a marked, nearly four-fold, decrease in tonic inhibition in the Fmr1 KO mice, as well as reduced effects of two δ subunit-preferring pharmacological agents, THIP and DS2, supporting the suggestion that δ subunit-containing GABAARs are compromised in the Fmr1 KO mice. Immunohistochemistry demonstrated a small but statistically significant decrease in δ subunit labeling in the molecular layer of the dentate gyrus in Fmr1 KO mice compared to wildtype (WT) littermates. The discrepancy between the large deficits in GABA-mediated tonic inhibition in granule cells in the Fmr1 KO mice and only modest reductions in immunolabeling of the δ subunit led to studies of surface expression of the δ subunit. Cross-linking experiments followed by Western blot analysis demonstrated a small, non-significant decrease in total δ subunit protein in the hippocampus of Fmr1 KO mice, but a four-fold decrease in surface expression of the δ subunit in these mice. No significant changes were observed in total or surface expression of the α4 subunit protein, a major partner of the δ subunit in the forebrain. Postembedding immunogold labeling for the δ subunit demonstrated a large, three-fold, decrease in the number of symmetric synapses with immunolabeling at perisynaptic locations in Fmr1 KO mice. While α4 immunogold particles were also reduced at perisynaptic locations in the Fmr1 KO mice, the labeling was increased at synaptic sites. Together these findings suggest that, in the dentate gyrus, altered surface expression of the δ subunit, rather than a decrease in δ subunit expression alone, could be limiting δ subunit-mediated tonic inhibition in this model of FXS. Finding ways to increase surface expression of the δ subunit of the GABAAR could be a novel approach to treatment of hyperexcitability-related alterations in FXS.
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32
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Simonsen C, Boddum K, von Schoubye NL, Kloppenburg A, Sønderskov K, Hansen SL, Kristiansen U. Anticonvulsive evaluation of THIP in the murine pentylenetetrazole kindling model: lack of anticonvulsive effect of THIP despite functional δ-subunit-containing GABA A receptors in dentate gyrus granule cells. Pharmacol Res Perspect 2017; 5. [PMID: 28805971 PMCID: PMC5684853 DOI: 10.1002/prp2.322] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2017] [Revised: 04/20/2017] [Accepted: 04/21/2017] [Indexed: 12/29/2022] Open
Abstract
THIP (4,5,6,7‐tetrahydroisoxazolo[5,4‐c]pyridin‐3‐ol) is a GABAA receptor agonist with varying potencies and efficacies at γ‐subunit‐containing receptors. More importantly, THIP acts as a selective superagonist at δ‐subunit‐containing receptors (δ‐GABAARs) at clinically relevant concentrations. Evaluation of THIP as a potential anticonvulsant has given contradictory results in different animal models and for this reason, we reevaluated the anticonvulsive properties of THIP in the murine pentylenetetrazole (PTZ) kindling model. As loss of δ‐GABAAR in the dentate gyrus has been associated with several animal models of epilepsy, we first investigated the presence of functional δ‐GABAA receptors. Both immunohistochemistry and Western blot data demonstrated that δ‐GABAAR expression is not only present in the dentate gyrus, but also the expression level was enhanced in the early phase after PTZ kindling. Whole‐cell patch‐clamp studies in acute hippocampal brain slices revealed that THIP was indeed able to induce a tonic inhibition in dentate gyrus granule cells. However, THIP induced a tonic current of similar magnitude in the PTZ‐kindled mice compared to saline‐treated animals despite the observed upregulation of δ‐GABAARs. Even in the demonstrated presence of functional δ‐GABAARs, THIP (0.5–4 mg/kg) showed no anticonvulsive effect in the PTZ kindling model using a comprehensive in vivo evaluation of the anticonvulsive properties.
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Affiliation(s)
- Charlotte Simonsen
- Faculty of Health and Medical Sciences, Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark
| | - Kim Boddum
- Faculty of Health and Medical Sciences, Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark.,Faculty of Health and Medical Sciences, Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Nadia L von Schoubye
- Faculty of Health and Medical Sciences, Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark.,Faculty of Health and Medical Sciences, Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Alissa Kloppenburg
- Faculty of Health and Medical Sciences, Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark
| | - Kasper Sønderskov
- Faculty of Health and Medical Sciences, Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark
| | - Suzanne L Hansen
- Faculty of Health and Medical Sciences, Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark
| | - Uffe Kristiansen
- Faculty of Health and Medical Sciences, Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark
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Lindemeyer AK, Shen Y, Yazdani F, Shao XM, Spigelman I, Davies DL, Olsen RW, Liang J. α2 Subunit-Containing GABA A Receptor Subtypes Are Upregulated and Contribute to Alcohol-Induced Functional Plasticity in the Rat Hippocampus. Mol Pharmacol 2017; 92:101-112. [PMID: 28536106 DOI: 10.1124/mol.116.107797] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2016] [Accepted: 05/05/2017] [Indexed: 12/20/2022] Open
Abstract
Alcohol (EtOH) intoxication causes changes in the rodent brain γ-aminobutyric acid receptor (GABAAR) subunit composition and function, playing a crucial role in EtOH withdrawal symptoms and dependence. Building evidence indicates that withdrawal from acute EtOH and chronic intermittent EtOH (CIE) results in decreased EtOH-enhanced GABAAR δ subunit-containing extrasynaptic and EtOH-insensitive α1βγ2 subtype synaptic GABAARs but increased synaptic α4βγ2 subtype, and increased EtOH sensitivity of GABAAR miniature postsynaptic currents (mIPSCs) correlated with EtOH dependence. Here we demonstrate that after acute EtOH intoxication and CIE, upregulation of hippocampal α4βγ2 subtypes, as well as increased cell-surface levels of GABAAR α2 and γ1 subunits, along with increased α2β1γ1 GABAAR pentamers in hippocampal slices using cell-surface cross-linking, followed by Western blot and coimmunoprecipitation. One-dose and two-dose acute EtOH treatments produced temporal plastic changes in EtOH-induced anxiolysis or withdrawal anxiety, and the presence or absence of EtOH-sensitive synaptic currents correlated with cell surface peptide levels of both α4 and γ1(new α2) subunits. CIE increased the abundance of novel mIPSC patterns differing in activation/deactivation kinetics, charge transfer, and sensitivity to EtOH. The different mIPSC patterns in CIE could be correlated with upregulated highly EtOH-sensitive α2βγ subtypes and EtOH-sensitive α4βγ2 subtypes. Naïve α4 subunit knockout mice express EtOH-sensitive mIPSCs in hippocampal slices, correlating with upregulated GABAAR α2 (and not α4) subunits. Consistent with α2, β1, and γ1 subunits genetically linked to alcoholism in humans, our findings indicate that these new α2-containing synaptic GABAARs could mediate the maintained anxiolytic response to EtOH in dependent individuals, rat or human, contributing to elevated EtOH consumption.
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Affiliation(s)
- A Kerstin Lindemeyer
- Department of Molecular and Medical Pharmacology (A.K.L., Y.S., F.Y., R.W.O., J.L.), and Department of Neurobiology (X.M.S.), David Geffen School of Medicine at University of California at Los Angeles, and Division of Oral Biology and Medicine, School of Dentistry (I.S.), University of California and Titus Family Department of Clinical Pharmacy, University of Southern California School of Pharmacy (D.L.D., J.L.), Los Angeles, California
| | - Yi Shen
- Department of Molecular and Medical Pharmacology (A.K.L., Y.S., F.Y., R.W.O., J.L.), and Department of Neurobiology (X.M.S.), David Geffen School of Medicine at University of California at Los Angeles, and Division of Oral Biology and Medicine, School of Dentistry (I.S.), University of California and Titus Family Department of Clinical Pharmacy, University of Southern California School of Pharmacy (D.L.D., J.L.), Los Angeles, California
| | - Ferin Yazdani
- Department of Molecular and Medical Pharmacology (A.K.L., Y.S., F.Y., R.W.O., J.L.), and Department of Neurobiology (X.M.S.), David Geffen School of Medicine at University of California at Los Angeles, and Division of Oral Biology and Medicine, School of Dentistry (I.S.), University of California and Titus Family Department of Clinical Pharmacy, University of Southern California School of Pharmacy (D.L.D., J.L.), Los Angeles, California
| | - Xuesi M Shao
- Department of Molecular and Medical Pharmacology (A.K.L., Y.S., F.Y., R.W.O., J.L.), and Department of Neurobiology (X.M.S.), David Geffen School of Medicine at University of California at Los Angeles, and Division of Oral Biology and Medicine, School of Dentistry (I.S.), University of California and Titus Family Department of Clinical Pharmacy, University of Southern California School of Pharmacy (D.L.D., J.L.), Los Angeles, California
| | - Igor Spigelman
- Department of Molecular and Medical Pharmacology (A.K.L., Y.S., F.Y., R.W.O., J.L.), and Department of Neurobiology (X.M.S.), David Geffen School of Medicine at University of California at Los Angeles, and Division of Oral Biology and Medicine, School of Dentistry (I.S.), University of California and Titus Family Department of Clinical Pharmacy, University of Southern California School of Pharmacy (D.L.D., J.L.), Los Angeles, California
| | - Daryl L Davies
- Department of Molecular and Medical Pharmacology (A.K.L., Y.S., F.Y., R.W.O., J.L.), and Department of Neurobiology (X.M.S.), David Geffen School of Medicine at University of California at Los Angeles, and Division of Oral Biology and Medicine, School of Dentistry (I.S.), University of California and Titus Family Department of Clinical Pharmacy, University of Southern California School of Pharmacy (D.L.D., J.L.), Los Angeles, California
| | - Richard W Olsen
- Department of Molecular and Medical Pharmacology (A.K.L., Y.S., F.Y., R.W.O., J.L.), and Department of Neurobiology (X.M.S.), David Geffen School of Medicine at University of California at Los Angeles, and Division of Oral Biology and Medicine, School of Dentistry (I.S.), University of California and Titus Family Department of Clinical Pharmacy, University of Southern California School of Pharmacy (D.L.D., J.L.), Los Angeles, California
| | - Jing Liang
- Department of Molecular and Medical Pharmacology (A.K.L., Y.S., F.Y., R.W.O., J.L.), and Department of Neurobiology (X.M.S.), David Geffen School of Medicine at University of California at Los Angeles, and Division of Oral Biology and Medicine, School of Dentistry (I.S.), University of California and Titus Family Department of Clinical Pharmacy, University of Southern California School of Pharmacy (D.L.D., J.L.), Los Angeles, California
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Centanni SW, Burnett EJ, Trantham-Davidson H, Chandler LJ. Loss of δ-GABA A receptor-mediated tonic currents in the adult prelimbic cortex following adolescent alcohol exposure. Addict Biol 2017; 22:616-628. [PMID: 26804056 DOI: 10.1111/adb.12353] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2015] [Revised: 10/29/2015] [Accepted: 11/24/2015] [Indexed: 11/30/2022]
Abstract
Delayed maturation of the adolescent prefrontal cortex may render it particularly vulnerable to insults, including those associated with drugs of abuse. Using a rat model of binge alcohol exposure, the present study examined the effect of adolescent intermittent ethanol (AIE) exposure during postnatal days 28-42 on γ-aminobutyric acid (GABA)ergic neurotransmission in the prelimbic cortex. In control rats, patch-clamp electrophysiology in acute slices obtained at different postnatal ages revealed a developmental increase in the GABAA receptor-mediated tonic current in layer V pyramidal neurons but no change in layers II/III when measured in the adult. In slices from AIE-exposed rats, the amplitude of the tonic current was significantly reduced compared with controls when tested at postnatal days 45, 60 and 90-120. This AIE-induced reduction in tonic current was found to reflect attenuation of currents mediated by δ-subunit containing receptors. Consistent with this, facilitation of the tonic current by bath application of either ethanol or allopregnanolone was attenuated in slices from AIE-exposed adult rats compared with control rats. However, expression of this facilitation as a percent of the amplitude of the total current mediated by δ-GABAA receptors revealed that AIE did not alter their sensitivity to either agonist. Lastly, immunohistochemistry and Western blot analysis revealed no change in the expression of δ-GABAA subunits or their surface expression. Taken together, these studies reveal that AIE exposure results in persistent deficits in δ-GABAA tonic currents in the adult prelimbic cortex that may contribute to deficits in decision-making and behavioral control in adulthood.
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Affiliation(s)
- Samuel W. Centanni
- Department of Neuroscience; Medical University of South Carolina; Charleston SC USA
| | - Elizabeth J. Burnett
- Department of Neuroscience; Medical University of South Carolina; Charleston SC USA
| | | | - L. Judson Chandler
- Department of Neuroscience; Medical University of South Carolina; Charleston SC USA
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Suryanarayanan A, Carter JM, Landin JD, Morrow AL, Werner DF, Spigelman I. Role of interleukin-10 (IL-10) in regulation of GABAergic transmission and acute response to ethanol. Neuropharmacology 2016; 107:181-188. [PMID: 27016017 PMCID: PMC5076550 DOI: 10.1016/j.neuropharm.2016.03.027] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2016] [Revised: 03/08/2016] [Accepted: 03/21/2016] [Indexed: 12/27/2022]
Abstract
Mounting evidence indicates that ethanol (EtOH) exposure activates neuroimmune signaling. Alterations in pro-inflammatory cytokines after acute and chronic EtOH exposure have been heavily investigated. In contrast, little is known about the regulation of neurotransmission and/or modulation by anti-inflammatory cytokines in the brain after an acute EtOH exposure. Recent evidence suggests that interleukin-10 (IL-10), an anti-inflammatory cytokine, is upregulated during withdrawal from chronic EtOH exposure. In the present study, we show that IL-10 is increased early (1 h) after a single intoxicating dose of EtOH (5 g/kg, intragastric) in Sprague Dawley rats. We also show that IL-10 rapidly regulates GABAergic transmission in dentate gyrus neurons. In brain slice recordings, IL-10 application dose-dependently decreases miniature inhibitory postsynaptic current (mIPSC) area and frequency, and decreases the magnitude of the picrotoxin sensitive tonic current (Itonic), indicating both pre- and postsynaptic mechanisms. A PI3K inhibitor LY294002 (but not the negative control LY303511) ablated the inhibitory effects of IL-10 on mIPSC area and Itonic, but not on mIPSC frequency, indicating the involvement of PI3K in postsynaptic effects of IL-10 on GABAergic transmission. Lastly, we also identify a novel neurobehavioral regulation of EtOH sensitivity by IL-10, whereby IL-10 attenuates acute EtOH-induced hypnosis. These results suggest that EtOH causes an early release of IL-10 in the brain, which may contribute to neuronal hyperexcitability as well as disturbed sleep seen after binge exposure to EtOH. These results also identify IL-10 signaling as a potential therapeutic target in alcohol-use disorders and other CNS disorders where GABAergic transmission is altered.
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Affiliation(s)
- A Suryanarayanan
- Department of Pharmaceutical Sciences, University of the Sciences, Philadelphia College of Pharmacy, Philadelphia, PA 19104, USA.
| | - J M Carter
- Department of Psychology, Center for Development and Behavioral Neuroscience, Binghamton University, Binghamton, NY 13902, USA
| | - J D Landin
- Department of Psychology, Center for Development and Behavioral Neuroscience, Binghamton University, Binghamton, NY 13902, USA
| | - A L Morrow
- Departments of Psychiatry and Pharmacology, University of North Carolina School of Medicine, Chapel Hill, NC 27599, USA
| | - D F Werner
- Department of Psychology, Center for Development and Behavioral Neuroscience, Binghamton University, Binghamton, NY 13902, USA
| | - I Spigelman
- Division of Oral Biology & Medicine, School of Dentistry, 63-078 CHS, University of California, Los Angeles, Los Angeles, CA 90095, USA.
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36
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Carlson SL, Bohnsack JP, Morrow AL. Ethanol Regulation of Synaptic GABAA α4 Receptors Is Prevented by Protein Kinase A Activation. J Pharmacol Exp Ther 2016; 357:10-6. [PMID: 26857960 DOI: 10.1124/jpet.115.230417] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2015] [Accepted: 01/28/2016] [Indexed: 02/06/2023] Open
Abstract
Ethanol alters GABAA receptor trafficking and function through activation of protein kinases, and these changes may underlie ethanol dependence and withdrawal. In this study, we used subsynaptic fraction techniques and patch-clamp electrophysiology to investigate the biochemical and functional effects of protein kinase A (PKA) and protein kinase C (PKC) activation by ethanol on synaptic GABAA α4 receptors, a key target of ethanol-induced changes. Rat cerebral cortical neurons were grown for 18 days in vitro and exposed to ethanol and/or kinase modulators for 4 hours, a paradigm that recapitulates GABAergic changes found after chronic ethanol exposure in vivo. PKA activation by forskolin or rolipram during ethanol exposure prevented increases in P2 fraction α4 subunit abundance, whereas inhibiting PKA had no effect. Similarly, in the synaptic fraction, activation of PKA by rolipram in the presence of ethanol prevented the increase in synaptic α4 subunit abundance, whereas inhibiting PKA in the presence of ethanol was ineffective. Conversely, PKC inhibition in the presence of ethanol prevented the ethanol-induced increases in synaptic α4 subunit abundance. Finally, we found that either activating PKA or inhibiting PKC in the presence of ethanol prevented the ethanol-induced decrease in GABA miniature inhibitory postsynaptic current decay τ1, whereas inhibiting PKA had no effect. We conclude that PKA and PKC have opposing effects in the regulation of synaptic α4 receptors, with PKA activation negatively modulating, and PKC activation positively modulating, synaptic α4 subunit abundance and function. These results suggest potential targets for restoring normal GABAergic functioning in the treatment of alcohol use disorders.
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Affiliation(s)
- Stephen L Carlson
- Departments of Psychiatry and Pharmacology, Bowles Center for Alcohol Studies, University of North Carolina School of Medicine, Chapel Hill, North Carolina
| | - John Peyton Bohnsack
- Departments of Psychiatry and Pharmacology, Bowles Center for Alcohol Studies, University of North Carolina School of Medicine, Chapel Hill, North Carolina
| | - A Leslie Morrow
- Departments of Psychiatry and Pharmacology, Bowles Center for Alcohol Studies, University of North Carolina School of Medicine, Chapel Hill, North Carolina
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Abstract
This review centers on the discoveries made during more than six decades of neuroscience research on the role of gamma-amino-butyric acid (GABA) as neurotransmitter. In doing so, special emphasis is directed to the significant involvement of Canadian scientists in these advances. Starting with the early studies that established GABA as an inhibitory neurotransmitter at central synapses, we summarize the results pointing at the GABA receptor as a drug target as well as more recent evidence showing that GABAA receptor signaling plays a surprisingly active role in neuronal network synchronization, both during development and in the adult brain. Finally, we briefly address the involvement of GABA in neurological conditions that encompass epileptic disorders and mental retardation.
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Werner DF, Porcu P, Boyd KN, O'Buckley TK, Carter JM, Kumar S, Morrow AL. Ethanol-induced GABAA receptor alpha4 subunit plasticity involves phosphorylation and neuroactive steroids. Mol Cell Neurosci 2016; 72:1-8. [PMID: 26805653 DOI: 10.1016/j.mcn.2016.01.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2015] [Revised: 12/11/2015] [Accepted: 01/09/2016] [Indexed: 10/22/2022] Open
Abstract
GABAA receptors containing α4 subunits are widely implicated in acute ethanol sensitivity, and their spatial and temporal regulation prominently contributes to ethanol-induced neuroplasticity in hippocampus and cortex. However, it is unknown if α4-containing GABAA receptors in the thalamus, an area of high α4 expression, display similar regulatory patterns following ethanol administration, and if so, by which molecular mechanisms. In the current study, thalamic GABAA receptor α4 subunit levels were increased following a 6-week-, but not a 2-week chronic ethanol diet. Following acute high-dose ethanol administration, thalamic GABAA receptor α4 subunit levels were regulated in a temporal fashion, as a decrease was observed at 2h followed by a delayed transient increase. PKCγ and PKCδ levels paralleled α4 temporal expression patterns following ethanol exposure. Initial decreases in α4 subunit expression were associated with reduced serine phosphorylation. Delayed increases in expression were not associated with a change in phosphorylation state, but were prevented by inhibiting neuroactive steroid production with the 5α-reductase inhibitor finasteride. Overall, these studies indicate that thalamic GABAA receptor α4 subunit expression following acute and chronic ethanol administration exhibits similar regulatory patterns as other regions and that transient expression patterns following acute exposure in vivo are likely dependent on both subunit phosphorylation state and neuroactive steroids.
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Affiliation(s)
- David F Werner
- Bowles Center for Alcohol Studies, University of North Carolina School of Medicine, Chapel Hill, NC 27599-7178, USA; Department of Psychology, Center for Development and Behavioral Neuroscience, Binghamton University - State University of New York, Binghamton, NY 13902, USA.
| | - Patrizia Porcu
- Bowles Center for Alcohol Studies, University of North Carolina School of Medicine, Chapel Hill, NC 27599-7178, USA; Department of Psychiatry, University of North Carolina School of Medicine, Chapel Hill, NC 27599-7178, USA; Neuroscience Institute, National Research Council of Italy (CNR), Cagliari, Italy
| | - Kevin N Boyd
- Bowles Center for Alcohol Studies, University of North Carolina School of Medicine, Chapel Hill, NC 27599-7178, USA
| | - Todd K O'Buckley
- Bowles Center for Alcohol Studies, University of North Carolina School of Medicine, Chapel Hill, NC 27599-7178, USA
| | - Jenna M Carter
- Department of Psychology, Center for Development and Behavioral Neuroscience, Binghamton University - State University of New York, Binghamton, NY 13902, USA
| | - Sandeep Kumar
- Bowles Center for Alcohol Studies, University of North Carolina School of Medicine, Chapel Hill, NC 27599-7178, USA; Department of Psychiatry, University of North Carolina School of Medicine, Chapel Hill, NC 27599-7178, USA
| | - A Leslie Morrow
- Bowles Center for Alcohol Studies, University of North Carolina School of Medicine, Chapel Hill, NC 27599-7178, USA; Department of Psychiatry, University of North Carolina School of Medicine, Chapel Hill, NC 27599-7178, USA; Department of Pharmacology, University of North Carolina School of Medicine, Chapel Hill, NC 27599-7178, USA
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Staples MC, Mandyam CD. Thinking after Drinking: Impaired Hippocampal-Dependent Cognition in Human Alcoholics and Animal Models of Alcohol Dependence. Front Psychiatry 2016; 7:162. [PMID: 27746746 PMCID: PMC5043052 DOI: 10.3389/fpsyt.2016.00162] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/15/2016] [Accepted: 09/13/2016] [Indexed: 12/05/2022] Open
Abstract
Alcohol use disorder currently affects approximately 18 million Americans, with at least half of these individuals having significant cognitive impairments subsequent to their chronic alcohol use. This is most widely apparent as frontal cortex-dependent cognitive dysfunction, where executive function and decision-making are severely compromised, as well as hippocampus-dependent cognitive dysfunction, where contextual and temporal reasoning are negatively impacted. This review discusses the relevant clinical literature to support the theory that cognitive recovery in tasks dependent on the prefrontal cortex and hippocampus is temporally different across extended periods of abstinence from alcohol. Additional studies from preclinical models are discussed to support clinical findings. Finally, the unique cellular composition of the hippocampus and cognitive impairment dependent on the hippocampus is highlighted in the context of alcohol dependence.
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Affiliation(s)
- Miranda C Staples
- Committee on the Neurobiology of Addictive Disorders, The Scripps Research Institute , La Jolla, CA , USA
| | - Chitra D Mandyam
- Committee on the Neurobiology of Addictive Disorders, The Scripps Research Institute , La Jolla, CA , USA
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Follesa P, Floris G, Asuni GP, Ibba A, Tocco MG, Zicca L, Mercante B, Deriu F, Gorini G. Chronic Intermittent Ethanol Regulates Hippocampal GABA(A) Receptor Delta Subunit Gene Expression. Front Cell Neurosci 2015; 9:445. [PMID: 26617492 PMCID: PMC4637418 DOI: 10.3389/fncel.2015.00445] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2015] [Accepted: 10/26/2015] [Indexed: 12/26/2022] Open
Abstract
Chronic ethanol consumption causes structural and functional reorganization in the hippocampus and induces alterations in the gene expression of gamma-aminobutyric acid type A receptors (GABAARs). Distinct forced intermittent exposure models have been used previously to investigate changes in GABAAR expression, with contrasting results. Here, we used repeated cycles of a Chronic Intermittent Ethanol paradigm to examine the relationship between voluntary, dependence-associated ethanol consumption, and GABAAR gene expression in mouse hippocampus. Adult male C57BL/6J mice were exposed to four 16-h ethanol vapor (or air) cycles in inhalation chambers alternated with limited-access two-bottle choice between ethanol (15%) and water consumption. The mice exposed to ethanol vapor showed significant increases in ethanol consumption compared to their air-matched controls. GABAAR alpha4 and delta subunit gene expression were measured by qRT-PCR at different stages. There were significant changes in GABAAR delta subunit transcript levels at different time points in ethanol-vapor exposed mice, while the alpha4 subunit levels remained unchanged. Correlated concurrent blood ethanol concentrations suggested that GABAAR delta subunit mRNA levels fluctuate depending on ethanol intoxication, dependence, and withdrawal state. Using a vapor-based Chronic Intermittent Ethanol procedure with combined two-bottle choice consumption, we corroborated previous evidences showing that discontinuous ethanol exposure affects GABAAR delta subunit expression but we did not observe changes in alpha4 subunit. These findings indicate that hippocampal GABAAR delta subunit expression changes transiently over the course of a Chronic Intermittent Ethanol paradigm associated with voluntary intake, in response to ethanol-mediated disturbance of GABAergic neurotransmission.
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Affiliation(s)
- Paolo Follesa
- Department of Life and Environmental Sciences, University of Cagliari Cagliari, Italy
| | - Gabriele Floris
- Department of Life and Environmental Sciences, University of Cagliari Cagliari, Italy
| | - Gino P Asuni
- Department of Life and Environmental Sciences, University of Cagliari Cagliari, Italy
| | - Antonio Ibba
- Department of Public Health, Clinical and Molecular Medicine, University of Cagliari Cagliari, Italy
| | - Maria G Tocco
- Department of Public Health, Clinical and Molecular Medicine, University of Cagliari Cagliari, Italy
| | - Luca Zicca
- Department of Public Health, Clinical and Molecular Medicine, University of Cagliari Cagliari, Italy
| | | | - Franca Deriu
- Department of Biomedical Sciences, University of Sassari Sassari, Italy
| | - Giorgio Gorini
- Department of Life and Environmental Sciences, University of Cagliari Cagliari, Italy
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Korpi ER, den Hollander B, Farooq U, Vashchinkina E, Rajkumar R, Nutt DJ, Hyytiä P, Dawe GS. Mechanisms of Action and Persistent Neuroplasticity by Drugs of Abuse. Pharmacol Rev 2015; 67:872-1004. [DOI: 10.1124/pr.115.010967] [Citation(s) in RCA: 101] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
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Raible DJ, Frey LC, Del Angel YC, Carlsen J, Hund D, Russek SJ, Smith B, Brooks-Kayal AR. JAK/STAT pathway regulation of GABAA receptor expression after differing severities of experimental TBI. Exp Neurol 2015; 271:445-56. [PMID: 26172316 PMCID: PMC5969808 DOI: 10.1016/j.expneurol.2015.07.001] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2015] [Revised: 06/22/2015] [Accepted: 07/04/2015] [Indexed: 01/07/2023]
Abstract
Synaptic inhibition in the adult brain is primarily mediated by the γ-aminobutyric acid (GABA) type A receptor (GABA(A)R). The distribution, properties, and dynamics of these receptors are largely determined by their subunit composition. Alteration of subunit composition after a traumatic brain injury (TBI) may result in abnormal increased synaptic firing and possibly contribute to injury-related pathology. Several studies have shown that the Janus Kinase/Signal Transducer and Activator of Transcription (JAK/STAT) signaling pathway can alter GABA(A)R subunit expression. The present study investigated changes in JAK/STAT pathway activation after two different severities of experimental TBI in the mouse using the controlled cortical impact (CCI) model. It also investigated whether modulating the activation of the JAK/STAT pathway after severe controlled cortical impact (CCI-S) with a JAK/STAT inhibitor (WP1066) alters post-traumatic epilepsy development and/or neurological recovery after injury. Our results demonstrated differential changes in both the activation of STAT3 and the expression of the GABA(A)R α1 and γ2 subunit levels that were dependent on the severity of the injury. The change in the GABA(A)R α1 subunit levels appeared to be at least partly transcriptionally mediated. We were able to selectively reverse the decrease in GABA(A)R α1 protein levels with WP1066 treatment after CCI injury. WP1066 treatment also improved the degree of recovery of vestibular motor function after injury. These findings suggest that the magnitude of JAK/STAT pathway activation and GABA(A)R α1 subunit level decrease is dependent on injury severity in this mouse model of TBI. In addition, reducing JAK/STAT pathway activation after severe experimental TBI reverses the decrease in the GABA(A)R α1 protein levels and improves vestibular motor recovery.
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Affiliation(s)
- Daniel J Raible
- Neuroscience Program, University of Colorado, Anschutz Medical Campus, Aurora, CO, United States.
| | - Lauren C Frey
- Department of Neurology, University of Colorado School of Medicine, Aurora, CO, United States.
| | - Yasmin Cruz Del Angel
- Division of Neurology, Department of Pediatrics, University of Colorado School of Medicine, Aurora, CO, United States.
| | - Jessica Carlsen
- Division of Neurology, Department of Pediatrics, University of Colorado School of Medicine, Aurora, CO, United States.
| | - Dana Hund
- Division of Neurology, Department of Pediatrics, University of Colorado School of Medicine, Aurora, CO, United States.
| | - Shelley J Russek
- Department of Pharmacology and Experimental Therapeutics, Boston University School of Medicine, Boston, MA, United States.
| | - Bret Smith
- Department of Physiology, College of Medicine, University of Kentucky, MS508 Chandler Medical Center, 800 Rose Street, Lexington, KY 40536, United States.
| | - Amy R Brooks-Kayal
- Neuroscience Program, University of Colorado, Anschutz Medical Campus, Aurora, CO, United States; Department of Neurology, University of Colorado School of Medicine, Aurora, CO, United States; Division of Neurology, Department of Pediatrics, University of Colorado School of Medicine, Aurora, CO, United States; Children's Hospital Colorado, Aurora, CO, United States.
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Bekdash RA, Harrison NL. Downregulation of Gabra4 expression during alcohol withdrawal is mediated by specific microRNAs in cultured mouse cortical neurons. Brain Behav 2015; 5:e00355. [PMID: 26357588 PMCID: PMC4559018 DOI: 10.1002/brb3.355] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/17/2015] [Revised: 03/27/2015] [Accepted: 04/25/2015] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND Alcohol abuse and dependence are a serious public health problem. A large number of alcohol-regulated genes, (ARGs) are known to be influenced by alcohol use and withdrawal (AW), and recent evidence suggests that neuroadaptation to alcohol may be due in part to epigenetic changes in the expression of ARGs. Gabra4, which encodes the α4 subunit of GABAA receptors (GABAARs), is one of a number of ARGs that show remarkable plasticity in response to alcohol, being rapidly upregulated by acute alcohol exposure. This study addressed the effects of AW on changes in the expression of Gabra4 and related genes that encode other subunits of GABAARs, and the potential regulation of Gabra4 by microRNAs. METHODS We studied gene and microRNAs expression, using RT-PCR and microRNA microarray in cultured cortical neurons treated with alcohol, which was then removed in order to simulate AW in vitro. We also used microRNA mimics or inhibitors, and a promoter-reporter construct carrying the 3'UTR of Gabra4. RESULTS Eleven hours after removal of alcohol, Gabra4 was downregulated, with a modest increase in the expression of Gabrg2, but no change in the expression of Gabra1, Gabrd, or Gabrb2. microRNA profiling in neurons undergoing AW revealed upregulation in the expression of miR-155, miR-186, miR-24, and miR-375 after 8 h of AW. Transfection with molecular mimics of miR-186, miR-24, or miR-375 also downregulated Gabra4 expression, whereas transfection with the corresponding inhibitors of these microRNAs normalized Gabra4 expression in AW neurons to the level measured in control neurons. Promoter-reporter experiments supported the idea that miR-155, miR-186, miR-24, miR-27b, or miR-375 bind to the 3'UTR of Gabra4 and thereby inhibit protein production. CONCLUSIONS Our data suggest that AW decreases Gabra4 expression, and that this may be mediated in part by the induction of specific microRNAs in cortical neurons during AW.
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Affiliation(s)
- Rola A Bekdash
- Department of Anesthesiology, Columbia UniversityNew York, New York, 10032
| | - Neil L Harrison
- Department of Anesthesiology, Columbia UniversityNew York, New York, 10032
- Department of Pharmacology, Columbia UniversityNew York, New York, 10032
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Olsen RW. Allosteric ligands and their binding sites define γ-aminobutyric acid (GABA) type A receptor subtypes. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 2015; 73:167-202. [PMID: 25637441 DOI: 10.1016/bs.apha.2014.11.005] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
GABAA receptors (GABA(A)Rs) mediate rapid inhibitory transmission in the brain. GABA(A)Rs are ligand-gated chloride ion channel proteins and exist in about a dozen or more heteropentameric subtypes exhibiting variable age and brain regional localization and thus participation in differing brain functions and diseases. GABA(A)Rs are also subject to modulation by several chemotypes of allosteric ligands that help define structure and function, including subtype definition. The channel blocker picrotoxin identified a noncompetitive channel blocker site in GABA(A)Rs. This ligand site is located in the transmembrane channel pore, whereas the GABA agonist site is in the extracellular domain at subunit interfaces, a site useful for low energy coupled conformational changes of the functional channel domain. Two classes of pharmacologically important allosteric modulatory ligand binding sites reside in the extracellular domain at modified agonist sites at other subunit interfaces: the benzodiazepine site and the high-affinity, relevant to intoxication, ethanol site. The benzodiazepine site is specific for certain GABA(A)R subtypes, mainly synaptic, while the ethanol site is found at a modified benzodiazepine site on different, extrasynaptic, subtypes. In the transmembrane domain are allosteric modulatory ligand sites for diverse chemotypes of general anesthetics: the volatile and intravenous agents, barbiturates, etomidate, propofol, long-chain alcohols, and neurosteroids. The last are endogenous positive allosteric modulators. X-ray crystal structures of prokaryotic and invertebrate pentameric ligand-gated ion channels, and the mammalian GABA(A)R protein, allow homology modeling of GABA(A)R subtypes with the various ligand sites located to suggest the structure and function of these proteins and their pharmacological modulation.
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Affiliation(s)
- Richard W Olsen
- Department of Molecular & Medical Pharmacology, David Geffen School of Medicine at UCLA, Los Angeles, California, USA.
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Nakamura Y, Darnieder LM, Deeb TZ, Moss SJ. Regulation of GABAARs by phosphorylation. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 2015; 72:97-146. [PMID: 25600368 PMCID: PMC5337123 DOI: 10.1016/bs.apha.2014.11.008] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
γ-Aminobutyric acid type A receptors (GABAARs) are the principal mediators of fast synaptic inhibition in the brain as well as the low persistent extrasynaptic inhibition, both of which are fundamental to proper brain function. Thus unsurprisingly, deficits in GABAARs are implicated in a number of neurological disorders and diseases. The complexity of GABAAR regulation is determined not only by the heterogeneity of these receptors but also by its posttranslational modifications, the foremost, and best characterized of which is phosphorylation. This review will explore the details of this dynamic process, our understanding of which has barely scratched the surface. GABAARs are regulated by a number of kinases and phosphatases, and its phosphorylation plays an important role in governing its trafficking, expression, and interaction partners. Here, we summarize the progress in understanding the role phosphorylation plays in the regulation of GABAARs. This includes how phosphorylation can affect the allosteric modulation of GABAARs, as well as signaling pathways that affect GABAAR phosphorylation. Finally, we discuss the dysregulation of GABAAR phosphorylation and its implication in disease processes.
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Snelling C, Tanchuck-Nipper MA, Ford MM, Jensen JP, Cozzoli DK, Ramaker MJ, Helms M, Crabbe JC, Rossi DJ, Finn DA. Quantification of ten neuroactive steroids in plasma in Withdrawal Seizure-Prone and -Resistant mice during chronic ethanol withdrawal. Psychopharmacology (Berl) 2014; 231:3401-14. [PMID: 24871700 PMCID: PMC4134998 DOI: 10.1007/s00213-014-3618-y] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/23/2013] [Accepted: 05/08/2014] [Indexed: 12/22/2022]
Abstract
RATIONALE The rapid membrane actions of neuroactive steroids, particularly via an enhancement of γ-aminobutyric acidA receptors (GABAARs), participate in the regulation of central nervous system excitability. Prior evidence suggests an inverse relationship between endogenous GABAergic neuroactive steroid levels and behavioral changes in excitability during ethanol withdrawal. OBJECTIVES Previously, we found that ethanol withdrawal significantly decreased plasma allopregnanolone (ALLO) levels, a potent GABAergic neuroactive steroid, and decreased GABAAR sensitivity to ALLO in Withdrawal Seizure-Prone (WSP) but not in Withdrawal Seizure-Resistant (WSR) mice. However, the effect of ethanol withdrawal on levels of other endogenous GABAAR-active steroids is not known. METHODS After validation of a gas chromatography-mass spectrometry method for the simultaneous quantification of ten neuroactive steroids, we analyzed plasma from control male WSP-1 and WSR-1 mice and during ethanol withdrawal. RESULTS We quantified levels of nine neuroactive steroids in WSP-1 and WSR-1 plasma; levels of pregnanolone were not detectable. Basal levels of five neuroactive steroids were higher in WSR-1 versus WSP-1 mice. Ethanol withdrawal significantly suppressed five neuroactive steroids in WSP-1 and WSR-1 mice, including ALLO. CONCLUSIONS Due to lower basal levels of some GABAAR-active steroids in WSP-1 mice, a withdrawal-induced decrease in WSP-1 mice may have a greater physiological consequence than a similar decrease in WSR-1 mice. Because WSP-1 mice also exhibit a reduction in GABAAR sensitivity to neuroactive steroids during withdrawal, it is possible that the combined decrease in neuroactive steroids and GABAAR sensitivity during ethanol withdrawal in WSP-1 mice represents a neurochemical substrate for severe ethanol withdrawal.
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Affiliation(s)
- Christopher Snelling
- Department of Behavioral Neuroscience, Oregon Health & Science University, Portland, OR
| | | | - Matthew M. Ford
- Department of Behavioral Neuroscience, Oregon Health & Science University, Portland, OR
- Division of Neuroscience, Oregon National Primate Research Center, Oregon Health & Science University, Beaverton, OR
| | - Jeremiah P. Jensen
- Department of Behavioral Neuroscience, Oregon Health & Science University, Portland, OR
| | - Debra K. Cozzoli
- Department of Behavioral Neuroscience, Oregon Health & Science University, Portland, OR
| | - Marcia J. Ramaker
- Department of Behavioral Neuroscience, Oregon Health & Science University, Portland, OR
| | - Melinda Helms
- Department of Behavioral Neuroscience, Oregon Health & Science University, Portland, OR
| | - John C. Crabbe
- Department of Behavioral Neuroscience, Oregon Health & Science University, Portland, OR
- Portland Alcohol Research Center, Department of Veterans Affairs Medical Center, Portland OR
| | - David J. Rossi
- Department of Behavioral Neuroscience, Oregon Health & Science University, Portland, OR
| | - Deborah A. Finn
- Department of Behavioral Neuroscience, Oregon Health & Science University, Portland, OR
- Portland Alcohol Research Center, Department of Veterans Affairs Medical Center, Portland OR
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Arbo BD, Andrade S, Osterkamp G, Gomez R, Ribeiro MFM. Effect of low doses of progesterone in the expression of the GABA(A) receptor α4 subunit and procaspase-3 in the hypothalamus of female rats. Endocrine 2014; 46:561-7. [PMID: 24366640 DOI: 10.1007/s12020-013-0126-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/21/2013] [Accepted: 11/13/2013] [Indexed: 11/26/2022]
Abstract
Progesterone is a steroid which regulates neural function, thereby modulating neurotransmission, cell survival, and behavior. Previous studies by our group have shown that chronic administration of low doses of progesterone in diestrus II female rats has an antidepressant-like effect in the forced swimming test (FST). Depression is associated with the several neurotransmitters systems, including GABA and serotonin, and with neurodegeneration and cell death in some brain circuits. The aim of this study was to verify the effect of progesterone on the protein expression of the GABA(A) receptor α4 subunit, serotonin transporter (SERT), Akt, extracellular signal-regulated kinase (Erk), and caspase-3 in the hypothalamus of diestrus II female rats exposed to the FST. Female rats were treated with a daily injection of progesterone (0.4 mg/kg) or vehicle, during two complete oestrous cycles. On the day of the experiment, the animals were euthanized 30 min after the FST, the hypothalamus was dissected and protein expression of GABA(A) receptor α4 subunit, SERT, Akt, Erk, and caspase-3 was evaluated. Progesterone increased the expression of GABA(A) receptor α4 subunit but did not change the expression of SERT. Progesterone decreased the expression of procaspase-3 in the hypothalamus without changing the activation of Akt and Erk in this structure. In summary, our results suggest that progesterone acts to increase the expression of the GABA(A) receptor α4 subunit and decrease the expression of procaspase-3 in the hypothalamus of female rats. Such effects may be involved in the antidepressant-like effect of progesterone in female rats exposed to the FST.
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Affiliation(s)
- Bruno D Arbo
- Laboratório de Interação Neuro-Humoral, Department of Physiology, ICBS-Universidade Federal do Rio Grande do Sul (UFRGS), Rua Sarmento Leite, 500, Porto Alegre, RS, 90050-170, Brazil,
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Liang J, Olsen RW. Alcohol use disorders and current pharmacological therapies: the role of GABA(A) receptors. Acta Pharmacol Sin 2014; 35:981-93. [PMID: 25066321 PMCID: PMC4125717 DOI: 10.1038/aps.2014.50] [Citation(s) in RCA: 86] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2014] [Accepted: 05/16/2014] [Indexed: 12/18/2022] Open
Abstract
Alcohol use disorders (AUD) are defined as alcohol abuse and alcohol dependence, which create large problems both for society and for the drinkers themselves. To date, no therapeutic can effectively solve these problems. Understanding the underlying mechanisms leading to AUD is critically important for developing effective and safe pharmacological therapies. Benzodiazepines (BZs) are used to reduce the symptoms of alcohol withdrawal syndrome. However, frequent use of BZs causes cross-tolerance, dependence, and cross-addiction to alcohol. The FDA-approved naltrexone and acamprosate have shown mixed results in clinical trials. Naltrexone is effective to treat alcohol dependence (decreased length and frequency of drinking bouts), but its severe side effects, including withdrawal symptoms, are difficult to overcome. Acamprosate showed efficacy for treating alcohol dependence in European trials, but two large US trials have failed to confirm the efficacy. Another FDA-approved medication, disulfiram, does not diminish craving, and it causes a peripheral neuropathy. Kudzu is the only natural medication mentioned by the National Institute on Alcohol Abuse and Alcoholism, but its mechanisms of action are not yet established. It has been recently shown that dihydromyricetin, a flavonoid purified from Hovenia, has unique effects on GABAA receptors and blocks ethanol intoxication and withdrawal in alcoholic animal models. In this article, we review the role of GABAA receptors in the treatment of AUD and currently available and potentially novel pharmacological agents.
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Affiliation(s)
- Jing Liang
- Department of Molecular & Medical Pharmacology, David Geffen School of Medicine, University of California, Los Angeles, CA, USA
| | - Richard W Olsen
- Department of Molecular & Medical Pharmacology, David Geffen School of Medicine, University of California, Los Angeles, CA, USA
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Olsen RW. Analysis of γ-aminobutyric acid (GABA) type A receptor subtypes using isosteric and allosteric ligands. Neurochem Res 2014; 39:1924-41. [PMID: 25015397 DOI: 10.1007/s11064-014-1382-3] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2014] [Revised: 06/30/2014] [Accepted: 07/02/2014] [Indexed: 11/30/2022]
Abstract
The GABAA receptors (GABAARs) play an important role in inhibitory transmission in the brain. The GABAARs could be identified using a medicinal chemistry approach to characterize with a series of chemical structural analogues, some identified in nature, some synthesized, to control the structural conformational rigidity/flexibility so as to define the 'receptor-specific' GABA agonist ligand structure. In addition to the isosteric site ligands, these ligand-gated chloride ion channel proteins exhibited modulation by several chemotypes of allosteric ligands, that help define structure and function. The channel blocker picrotoxin identified a noncompetitive channel blocker site in GABAARs. This ligand site is located in the transmembrane channel pore, whereas the GABA agonist site is in the extracellular domain at subunit interfaces, a site useful for low energy coupled conformational changes of the functional channel domain. Also in the trans-membrane domain are allosteric modulatory ligand sites, mostly positive, for diverse chemotypes with general anesthetic efficacy, namely, the volatile and intravenous agents: barbiturates, etomidate, propofol, long-chain alcohols, and neurosteroids. The last are apparent endogenous positive allosteric modulators of GABAARs. These binding sites depend on the GABAAR heteropentameric subunit composition, i.e., subtypes. Two classes of pharmacologically very important allosteric modulatory ligand binding site reside in the extracellular domain at modified agonist sites at other subunit interfaces: the benzodiazepine site, and the low-dose ethanol site. The benzodiazepine site is specific for certain subunit combination subtypes, mainly synaptically localized. In contrast, the low-dose (high affinity) ethanol site(s) is found at a modified benzodiazepine site on different, extrasynaptic, subtypes.
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Affiliation(s)
- Richard W Olsen
- Department of Molecular and Medical Pharmacology, David Geffen School of Medicine at UCLA, Room CHS 23-120, 650 Young Drive South, Los Angeles, CA, 90095-1735, USA,
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Lindemeyer AK, Liang J, Marty VN, Meyer EM, Suryanarayanan A, Olsen RW, Spigelman I. Ethanol-induced plasticity of GABAA receptors in the basolateral amygdala. Neurochem Res 2014; 39:1162-70. [PMID: 24710789 PMCID: PMC4121120 DOI: 10.1007/s11064-014-1297-z] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2013] [Revised: 03/24/2014] [Accepted: 03/26/2014] [Indexed: 12/25/2022]
Abstract
Acute and chronic ethanol (EtOH) administration is known to affect function, surface expression, and subunit composition of γ-aminobutyric acid (A) receptors (GABAARs) in different parts of the brain, which is believed to play a major role in alcohol dependence and withdrawal symptoms. The basolateral amygdala (BLA) participates in anxiety-like behaviors including those induced by alcohol withdrawal. In the present study we assessed the changes in cell surface levels of select GABAAR subunits in the BLA of a rat model of alcohol dependence induced by chronic intermittent EtOH (CIE) treatment and long-term (>40 days) withdrawal and investigated the time-course of such changes after a single dose of EtOH (5 g/kg, gavage). We found an early decrease in surface expression of α4 and δ subunits at 1 h following single dose EtOH treatment. At 48 h post-EtOH and after CIE treatment there was an increase in α4 and γ2, while α1, α2, and δ surface expression were decreased. To relate functional changes in GABAARs to changes in their subunit composition we analyzed miniature inhibitory postsynaptic currents (mIPSCs) and the picrotoxin-sensitive tonic current (Itonic) 48 h after EtOH intoxication. The Itonic magnitude and most of the mIPSC kinetic parameters (except faster mIPSC decay) were unchanged at 48 h post-EtOH. At the same time, Itonic potentiation by acute EtOH was greatly reduced, whereas mIPSCs became significantly more sensitive to potentiation by acute EtOH. These results suggest that EtOH intoxication-induced GABAAR plasticity in the BLA might contribute to the diminished sedative/hypnotic and maintained anxiolytic effectiveness of EtOH.
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Affiliation(s)
- A. Kerstin Lindemeyer
- Department of Molecular and Medical Pharmacology, David Geffen School of Medicine, University of California, Los Angeles, CA, USA
| | - Jing Liang
- Department of Molecular and Medical Pharmacology, David Geffen School of Medicine, University of California, Los Angeles, CA, USA; Division of Oral Biology and Medicine, School of Dentistry, University of California, 10833 Le Conte Avenue, 63-078 CHS, Los Angeles, CA 90095-1668, USA
| | - Vincent N. Marty
- Division of Oral Biology and Medicine, School of Dentistry, University of California, 10833 Le Conte Avenue, 63-078 CHS, Los Angeles, CA 90095-1668, USA
| | - Edward M. Meyer
- Division of Oral Biology and Medicine, School of Dentistry, University of California, 10833 Le Conte Avenue, 63-078 CHS, Los Angeles, CA 90095-1668, USA
| | - Asha Suryanarayanan
- Department of Molecular and Medical Pharmacology, David Geffen School of Medicine, University of California, Los Angeles, CA, USA; Division of Oral Biology and Medicine, School of Dentistry, University of California, 10833 Le Conte Avenue, 63-078 CHS, Los Angeles, CA 90095-1668, USA
| | - Richard W. Olsen
- Department of Molecular and Medical Pharmacology, David Geffen School of Medicine, University of California, Los Angeles, CA, USA
| | - Igor Spigelman
- Division of Oral Biology and Medicine, School of Dentistry, University of California, 10833 Le Conte Avenue, 63-078 CHS, Los Angeles, CA 90095-1668, USA
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