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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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Turco CV, Arsalan SO, Nelson AJ. The Influence of Recreational Substance Use in TMS Research. Brain Sci 2020; 10:E751. [PMID: 33080965 PMCID: PMC7603156 DOI: 10.3390/brainsci10100751] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2020] [Revised: 10/13/2020] [Accepted: 10/15/2020] [Indexed: 12/30/2022] Open
Abstract
(1) Background: Transcranial magnetic stimulation (TMS) approaches are widely used to study cortical and corticospinal function. However, responses to TMS are subject to significant intra-and inter-individual variability. Acute and chronic exposure to recreational substances alters the excitability of the sensorimotor system and may contribute to the variability in TMS outcome measures. The increasing prevalence of recreational substance use poses a significant challenge for executing TMS studies, but there is a lack of clarity regarding the influence of these substances on sensorimotor function. (2) Methods: The literature investigating the influence of alcohol, nicotine, caffeine and cannabis on TMS outcome measures of corticospinal, intracortical and interhemispheric excitability was reviewed. (3) Results: Both acute and chronic use of recreational substances modulates TMS measures of excitability. Despite the abundance of research in this field, we identify knowledge gaps that should be addressed in future studies to better understand the influence of these substances on TMS outcomes. (4) Conclusions: This review highlights the need for TMS studies to take into consideration the history of participant substance use and to control for acute substance use prior to testing.
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Affiliation(s)
| | | | - Aimee J. Nelson
- Department of Kinesiology, McMaster University, Hamilton, ON L8S 4L8, Canada; (C.V.T.); (S.O.A.)
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Barker JS, Hines RM. Regulation of GABA A Receptor Subunit Expression in Substance Use Disorders. Int J Mol Sci 2020; 21:ijms21124445. [PMID: 32580510 PMCID: PMC7352578 DOI: 10.3390/ijms21124445] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Revised: 06/17/2020] [Accepted: 06/19/2020] [Indexed: 01/02/2023] Open
Abstract
The modulation of neuronal cell firing is mediated by the release of the neurotransmitter GABA (γ-aminobuytric acid), which binds to two major families of receptors. The ionotropic GABAA receptors (GABAARs) are composed of five distinct subunits that vary in expression by brain region and cell type. The action of GABA on GABAARs is modulated by a variety of clinically and pharmacologically important drugs such as benzodiazepines and alcohol. Exposure to and abuse of these substances disrupts homeostasis and induces plasticity in GABAergic neurotransmission, often via the regulation of receptor expression. Here, we review the regulation of GABAAR subunit expression in adaptive and pathological plasticity, with a focus on substance use. We examine the factors influencing the expression of GABAAR subunit genes including the regulation of the 5′ and 3′ untranslated regions, variations in DNA methylation, immediate early genes and transcription factors that regulate subunit expression, translational and post-translational modifications, and other forms of receptor regulation beyond expression. Advancing our understanding of the factors regulating GABAAR subunit expression during adaptive plasticity, as well as during substance use and withdrawal will provide insight into the role of GABAergic signaling in substance use disorders, and contribute to the development of novel targeted therapies.
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Devaud LL, Alavi M, Jensen JP, Helms ML, Nipper MA, Finn DA. Sexually divergent changes in select brain proteins and neurosteroid levels after a history of ethanol drinking and intermittent PTSD-like stress exposure in adult C57BL/6J mice. Alcohol 2020; 83:115-125. [PMID: 30529168 DOI: 10.1016/j.alcohol.2018.12.001] [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: 09/10/2018] [Revised: 11/30/2018] [Accepted: 12/03/2018] [Indexed: 11/25/2022]
Abstract
Human studies reported that the number of past-year stressors was positively related to current drinking patterns, including binge drinking. In animal models, exposure to predator odor stress (PS), considered a model of traumatic stress, consistently increased ethanol intake. Recently, we reported that repeated PS significantly increased ethanol intake and had a synergistic interaction with prior binge drinking (binge group) in male but not in female C57BL/6J mice, when compared to mice without prior binge exposure (control group). The current studies utilized plasma and dissected prefrontal cortex (PFC) and hippocampal tissue from these animals and from age-matched naïve mice (naïve group). Western blots assessed relative protein levels of P450scc (an enzyme involved in the first step of steroidogenesis), of GABAA receptor α2 and α4 subunits, and of two proteins involved in synaptic plasticity - ARC (activity-regulated cytoskeletal protein) and synaptophysin. Gas chromatography-mass spectrometry simultaneously quantified 10 neurosteroid levels in plasma. A history of ethanol drinking and PS exposure produced brain regional and sex differences in the changes in proteins examined as well as in the pattern of neurosteroid levels versus (vs.) values in naïve mice. For instance, P450scc levels were significantly increased only in binge and control female PFC and hippocampus vs. naïve mice. Some neurosteroid levels were significantly altered by binge treatment in both males and females, whereas others were only significantly altered in males. These sexually divergent changes in neurosteroid and protein levels add to evidence for sex differences in the neurochemical systems influenced by traumatic stress and a history of ethanol drinking.
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Matthews DB, Schneider A, Kastner A, Scaletty S, Szenay R. I can't drink what I used to: The interaction between ethanol and the aging brain. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2019; 148:79-99. [PMID: 31733668 DOI: 10.1016/bs.irn.2019.09.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The population of most countries is increasing and the United Nations predicts that by the year 2050 those over the age of 60 years old will increase from 900 million individuals to approximately 2.1 billion individuals (United Nations, 2015). The increase in the number of older individuals will place a strain on many national health care systems making it important to investigate behaviors in the aged that may negatively impact general health in this demographic. Recent work has shown that older adults consume alcohol, often at levels that exceed the legal limit of intoxication. Unfortunately, consumption of high levels of ethanol in the older population is associated with many health consequences and may negatively impact the brain. Given ethical constraints found in many biomedical studies, animal models are needed to investigate the possible negative impact of high ethanol use in aged populations. However, few studies have investigated the effect of ethanol exposure in aged animals compared to ethanol exposure in younger animals and consequently the impact of ethanol in the aged population is not well understood. The current review summarizes initial work establishing the impact of ethanol in aged animals. The reviewed research studies support the working hypothesis that ethanol exposure produces significantly greater effects in aged animals compared to younger animals on many, if not all, behavioral tasks. In addition, the review proposes several initial, promising avenues of research to explore the neurobiological mechanisms that underly greater effects on ethanol-induced ataxia, cognition and sleep time. It is hoped that this effort will not only lead to a better understanding of behaviors impacted by ethanol in aged animals, but also improve the understanding brain mechanisms of the reported increased sensitivity to ethanol in the aged population.
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Affiliation(s)
- Douglas B Matthews
- Department of Psychology, University of Wisconsin-Eau Claire, Eau Claire, WI, United States.
| | - Amelia Schneider
- Department of Psychology, University of Wisconsin-Eau Claire, Eau Claire, WI, United States
| | - Abigail Kastner
- Department of Psychology, University of Wisconsin-Eau Claire, Eau Claire, WI, United States
| | - Samantha Scaletty
- Department of Psychology, University of Wisconsin-Eau Claire, Eau Claire, WI, United States
| | - Rachel Szenay
- Department of Psychology, University of Wisconsin-Eau Claire, Eau Claire, WI, United States
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You C, Vandegrift BJ, Zhang H, Lasek AW, Pandey SC, Brodie MS. Histone Deacetylase Inhibitor Suberanilohydroxamic Acid Treatment Reverses Hyposensitivity to γ-Aminobutyric Acid in the Ventral Tegmental Area During Ethanol Withdrawal. Alcohol Clin Exp Res 2018; 42:2160-2171. [PMID: 30103280 PMCID: PMC6214766 DOI: 10.1111/acer.13870] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2018] [Accepted: 08/08/2018] [Indexed: 12/24/2022]
Abstract
Background The ventral tegmental area (VTA) is important for alcohol‐related reward and reinforcement. Mouse VTA neurons are hyposensitive to γ‐aminobutyric acid (GABA) during ethanol (EtOH) withdrawal, and GABA responsiveness is normalized by in vitro treatment with histone deacetylase inhibitors (HDACi). The present study examined the effect of a systemically administered HDACi, suberanilohydroxamic acid (SAHA) on GABA sensitivity, and related molecular changes in VTA neurons during withdrawal after chronic EtOH intake in rats. Methods Sprague Dawley male adult rats were fed with Lieber‐DeCarli diet (9% EtOH or control diet) for 16 days. Experimental groups included control diet‐fed and EtOH diet‐fed (0‐ or 24‐hour withdrawal) rats treated with either SAHA or vehicle injection. Single‐unit recordings were used to measure the response of VTA neurons to GABA. Immunohistochemistry was performed to examine levels of HDAC2, acetylated histone H3 lysine 9 (acH3K9), and GABAA receptor α1 and α5 subunits in the VTA; quantitative polymerase chain reaction was performed to examine the mRNA levels of HDAC2 and GABAA receptor subunits. Results VTA neurons from the withdrawal group exhibited GABA hyposensitivity. In vivo SAHA treatment 2 hours before sacrifice normalized the sensitivity of VTA neurons to GABA. EtOH withdrawal was associated with increased HDAC2 and decreased acH3K9 protein levels; SAHA treatment normalized acH3K9 levels. Interestingly, no significant change was observed in the mRNA levels of HDAC2. The mRNA levels, but not protein levels, of GABAA receptor α1 and α5 subunits were increased during withdrawal. Conclusions Withdrawal from chronic EtOH exposure results in a decrease in GABA‐mediated inhibition, and this GABA hyposensitivity is normalized by in vivo SAHA treatment. Disruption of signaling in the VTA produced by alteration of GABA neurotransmission could be 1 neuroadaptive physiological process leading to craving and relapse. These results suggest that HDACi pharmacotherapy with agents like SAHA might be an effective treatment for alcoholism.
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Affiliation(s)
- Chang You
- Department of Physiology and Biophysics , University of Illinois at Chicago, Chicago, Illinois.,Center for Alcohol Research in Epigenetics , Department of Psychiatry, University of Illinois at Chicago, Chicago, Illinois
| | - Bertha J Vandegrift
- Department of Physiology and Biophysics , University of Illinois at Chicago, Chicago, Illinois.,Center for Alcohol Research in Epigenetics , Department of Psychiatry, University of Illinois at Chicago, Chicago, Illinois
| | - Huaibo Zhang
- Center for Alcohol Research in Epigenetics , Department of Psychiatry, University of Illinois at Chicago, Chicago, Illinois.,Jesse Brown VA Medical Center , Chicago, Illinois
| | - Amy W Lasek
- Center for Alcohol Research in Epigenetics , Department of Psychiatry, University of Illinois at Chicago, Chicago, Illinois
| | - Subhash C Pandey
- Center for Alcohol Research in Epigenetics , Department of Psychiatry, University of Illinois at Chicago, Chicago, Illinois.,Jesse Brown VA Medical Center , Chicago, Illinois
| | - Mark S Brodie
- Department of Physiology and Biophysics , University of Illinois at Chicago, Chicago, Illinois.,Center for Alcohol Research in Epigenetics , Department of Psychiatry, University of Illinois at Chicago, Chicago, Illinois
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Finn DA, Helms ML, Nipper MA, Cohen A, Jensen JP, Devaud LL. Sex differences in the synergistic effect of prior binge drinking and traumatic stress on subsequent ethanol intake and neurochemical responses in adult C57BL/6J mice. Alcohol 2018; 71:33-45. [PMID: 29966824 PMCID: PMC10957143 DOI: 10.1016/j.alcohol.2018.02.004] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2017] [Revised: 01/26/2018] [Accepted: 02/22/2018] [Indexed: 12/13/2022]
Abstract
Alcohol-use disorders (AUDs) are characterized by repeated episodes of binge drinking. Based on reports that exposure to predator odor stress (PS) consistently increases ethanol intake, the present studies examined whether prior binge drinking differentially altered responsivity to PS and subsequent ethanol intake in male and female mice, when compared to mice without prior binge exposure. Initial studies in naïve male and female C57BL/6J mice confirmed that 30-min exposure to dirty rat bedding significantly increased plasma corticosterone (CORT) levels and anxiety-related behavior, justifying the use of dirty rat bedding as PS in the subsequent drinking studies. Next, separate groups of male and female C57BL/6J mice received seven binge ethanol sessions (binge) or drank water (controls), followed by a 1-month period of abstinence. Then, 2-bottle choice ethanol intake (10% or 10E vs. water, 23 h/day) was measured in lickometer chambers for 4 weeks. After baseline intake stabilized, exposure to intermittent PS (2×/week × 2 weeks) significantly enhanced ethanol intake after the 2nd PS in male, but not female, binge mice vs. baseline and vs. the increase in controls. However, in a subgroup of females (with low baselines), PS produced a similar increase in 10E intake in control and binge mice vs. baseline. Analysis of lick behavior determined that the enhanced 10E intake in binge male mice and in the female low baseline subgroup was associated with a significant increase in 10E bout frequency and 10E licks throughout the circadian dark phase. Thus, PS significantly increased 10E intake and had a synergistic interaction with prior binge drinking in males, whereas PS produced a similar significant increase in 10E intake in the low baseline subgroup of binge and control females. Plasma CORT levels were increased significantly in both binge and control animals after PS. CORT levels at 24-h withdrawal from daily 10E intake were highest in the groups with elevated 10E licks (i.e., binge males and control females). At 24-h withdrawal, protein levels of GABAA receptor α1 subunit, corticotropin releasing factor receptor 1, and glucocorticoid receptor in prefrontal cortex (PFC) and hippocampus (HC) were differentially altered in the male and female mice vs. levels in separate groups of age-matched naïve mice, with more changes in HC than in PFC and in females than in males. Importantly, the sexually divergent changes in protein levels in PFC and HC add to evidence for sex differences in the neurochemical systems influenced by stress and binge drinking, and argue for sex-specific pharmacological strategies to treat AUD.
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Affiliation(s)
- Deborah A Finn
- Department of Behavioral Neuroscience, Oregon Health & Sciences University, Portland, OR, United States; VA Portland Health Care System, Portland, OR, United States.
| | - Melinda L Helms
- Department of Behavioral Neuroscience, Oregon Health & Sciences University, Portland, OR, United States
| | - Michelle A Nipper
- Department of Behavioral Neuroscience, Oregon Health & Sciences University, Portland, OR, United States
| | - Allison Cohen
- VA Portland Health Care System, Portland, OR, United States
| | - Jeremiah P Jensen
- Department of Behavioral Neuroscience, Oregon Health & Sciences University, Portland, OR, United States
| | - Leslie L Devaud
- School of Pharmacy, Pacific University, Hillsboro, OR, United States
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Gruol DL, Huitron-Resendiz S, Roberts AJ. Altered brain activity during withdrawal from chronic alcohol is associated with changes in IL-6 signal transduction and GABAergic mechanisms in transgenic mice with increased astrocyte expression of IL-6. Neuropharmacology 2018; 138:32-46. [PMID: 29787738 DOI: 10.1016/j.neuropharm.2018.05.024] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2018] [Revised: 04/25/2018] [Accepted: 05/17/2018] [Indexed: 10/16/2022]
Abstract
Interleukin-6 (IL-6) is an important neuroimmune factor that is increased in the brain by alcohol exposure/withdrawal and is thought to play a role in the actions of alcohol on the brain. To gain insight into IL-6/alcohol/withdrawal interactions and how these interactions affect the brain, we are studying the effects of chronic binge alcohol exposure on transgenic mice that express elevated levels of IL-6 in the brain due to increased astrocyte expression (IL-6 tg) and their non-transgenic (non-tg) littermate controls. IL-6/alcohol/withdrawal interactions were identified by genotypic differences in spontaneous brain activity in electroencephalogram (EEG) recordings from the mice, and by Western blot analysis of protein activation or expression in hippocampus obtained from the mice after the final alcohol withdrawal period. Results from EEG studies showed frequency dependent genotypic differences in brain activity during withdrawal. For EEG frequencies that were affected by alcohol exposure/withdrawal in both genotypes, the nature of the effect was similar, but differed across withdrawal cycles. Differences between IL-6 tg and non-tg mice were also observed in Western blot studies of the activated form of STAT3 (phosphoSTAT3), a signal transduction partner of IL-6, and subunits of GABAA receptors (GABAAR). Regression analysis revealed that pSTAT3 played a more prominent role during withdrawal in the IL-6 tg mice than in the non-tg mice, and that the role of GABAAR alpha-5 and GABAAR alpha-1 in brain activity varied across genotype and withdrawal. Taken together, our results suggest that IL-6 can significantly impact mechanisms involved in alcohol withdrawal.
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Affiliation(s)
- Donna L Gruol
- Neuroscience Department, The Scripps Research Institute, La Jolla, CA, 92037, USA.
| | | | - Amanda J Roberts
- Animal Models Core Facility, The Scripps Research Institute, La Jolla, CA, 92037, USA
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Yu YH, Lee K, Sin DS, Park KH, Park DK, Kim DS. Altered functional efficacy of hippocampal interneuron during epileptogenesis following febrile seizures. Brain Res Bull 2017; 131:25-38. [DOI: 10.1016/j.brainresbull.2017.02.009] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2016] [Revised: 02/17/2017] [Accepted: 02/23/2017] [Indexed: 12/22/2022]
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Roberto M, Varodayan FP. Synaptic targets: Chronic alcohol actions. Neuropharmacology 2017; 122:85-99. [PMID: 28108359 DOI: 10.1016/j.neuropharm.2017.01.013] [Citation(s) in RCA: 106] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2016] [Revised: 12/23/2016] [Accepted: 01/14/2017] [Indexed: 01/02/2023]
Abstract
Alcohol acts on numerous cellular and molecular targets to regulate neuronal communication within the brain. Chronic alcohol exposure and acute withdrawal generate prominent neuroadaptations at synapses, including compensatory effects on the expression, localization and function of synaptic proteins, channels and receptors. The present article reviews the literature describing the synaptic effects of chronic alcohol exposure and their relevance for synaptic transmission in the central nervous system. This review is not meant to be comprehensive, but rather to highlight the effects that have been observed most consistently and that are thought to contribute to the development of alcohol dependence and the negative aspects of withdrawal. Specifically, we will focus on the major excitatory and inhibitory neurotransmitters in the brain, glutamate and GABA, respectively, and how their neuroadaptations after chronic alcohol exposure contributes to alcohol reinforcement, dependence and withdrawal. This article is part of the Special Issue entitled "Alcoholism".
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Skorput AGJ, Yeh HH. Chronic Gestational Exposure to Ethanol Leads to Enduring Aberrances in Cortical Form and Function in the Medial Prefrontal Cortex. Alcohol Clin Exp Res 2016; 40:1479-88. [PMID: 27242215 DOI: 10.1111/acer.13107] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2015] [Accepted: 04/23/2016] [Indexed: 11/29/2022]
Abstract
BACKGROUND Exposure to ethanol (EtOH) in utero alters the disposition of tangentially migrating GABAergic interneurons in the fetal brain. The medial ganglionic eminence (MGE) gives rise to a large portion of cortical GABAergic interneurons, including the parvalbumin-expressing interneurons that shape and contribute to inhibitory/excitatory (I/E) balance of the intracortical circuit. Here, we investigated in the mouse medial prefrontal cortex (mPFC) the hypothesis that low levels of maternal EtOH consumption from closure of the neural tube embryonic day (E) 9.5 until birth result in an enduring interneuronopathy. METHODS Pregnant mice were subjected to a 2% w/w EtOH consumption regimen starting at neural tube closure and ending at parturition. Neurogenesis in the MGE was assessed by 5-bromo-2-deoxyuridine (BrdU) immunofluorescence at E12.5. The count and distribution of parvalbumin-expressing interneurons were determined in adult animals, and patch clamp electrophysiology was performed to determine GABAergic function and I/E balance. Open-field behavior in adult mice was assessed to determine whether the EtOH-exposed cohort displayed a lasting alteration in exploratory behavior. RESULTS In embryos exposed to EtOH in utero, we found increased BrdU labeling in the MGE, pointing to increased neurogenesis. Adult mice prenatally exposed to EtOH were hyperactive, and this was associated with an increase in parvalbumin-expressing GABAergic interneurons in the mPFC. In addition, prenatal EtOH exposure altered the balance between spontaneous inhibitory and excitatory synaptic input and attenuated GABAergic tone in layer V mPFC pyramidal neurons in juvenile mice. CONCLUSIONS These findings underscore that altered migration of GABAergic interneurons contributes to the EtOH-induced aberration of cortical development and that these effects persist into adulthood as altered cortical form and function.
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Affiliation(s)
- Alexander G J Skorput
- Department of Neuroscience, University of Minnesota Medical School Twin Cities, Minneapolis, Minnesota
| | - Hermes H Yeh
- Department of Physiology and Neurobiology, Geisel School of Medicine at Dartmouth, Dartmouth-Hitchcock Medical Center, Lebanon, New Hampshire
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12
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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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14
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Van Skike CE, Diaz-Granados JL, Matthews DB. Chronic intermittent ethanol exposure produces persistent anxiety in adolescent and adult rats. Alcohol Clin Exp Res 2015; 39:262-71. [PMID: 25684048 DOI: 10.1111/acer.12617] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2014] [Accepted: 10/28/2014] [Indexed: 11/27/2022]
Abstract
BACKGROUND Ethanol (EtOH) dependence and tolerance in the adult are marked by increased function of NMDA receptors and decreased function of GABAA receptors, which coincide with altered receptor subunit expression in specific brain regions. Adolescents often use EtOH at levels greater than adults, yet the receptor subunit expression profiles following chronic intermittent EtOH (CIE) exposure in adolescents are not known. Persistent age-dependent changes in receptor subunit alterations coupled with withdrawal-related anxiety may help explain the increase in alcohol abuse following adolescent experimentation with the drug. METHODS Adolescent and adult rats received 10 intraperitoneal administrations of 4.0 g/kg EtOH or saline every 48 hours. At either 24 hours or 12 days after the final exposure, anxiety-like behavior was assessed on the elevated plus maze and tissue was collected. Western blotting was used to assess changes in selected NMDA and GABAA receptor subunits in whole cortex and bilateral hippocampus. RESULTS CIE exposure yields a persistent increase in anxiety-like behavior in both age groups. However, selected NMDA and GABAA receptor subunits were not differentially altered by this CIE exposure paradigm in adolescents or adults. CONCLUSIONS CIE exposure produced persistent anxiety-like behavior, which has important implications for alcohol cessation. Given the reported behavioral and neuropeptide expression changes in response to this dose of EtOH, it is important for future work to consider the circumstances under which these measures are altered by EtOH exposure.
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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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16
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Stankiewicz AM, Goscik J, Dyr W, Juszczak GR, Ryglewicz D, Swiergiel AH, Wieczorek M, Stefanski R. Novel candidate genes for alcoholism--transcriptomic analysis of prefrontal medial cortex, hippocampus and nucleus accumbens of Warsaw alcohol-preferring and non-preferring rats. Pharmacol Biochem Behav 2015; 139:27-38. [PMID: 26455281 DOI: 10.1016/j.pbb.2015.10.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/13/2015] [Revised: 10/06/2015] [Accepted: 10/06/2015] [Indexed: 11/29/2022]
Abstract
OBJECTIVE Animal models provide opportunity to study neurobiological aspects of human alcoholism. Changes in gene expression have been implicated in mediating brain functions, including reward system and addiction. The current study aimed to identify genes that may underlie differential ethanol preference in Warsaw High Preferring (WHP) and Warsaw Low Preferring (WLP) rats. METHODS Microarray analysis comparing gene expression in nucleus accumbens (NAc), hippocampus (HP) and medial prefrontal cortex (mPFC) was performed in male WHP and WLP rats bred for differences in ethanol preference. RESULTS Differential and stable between biological repeats expression of 345, 254 and 129 transcripts in NAc, HP and mPFC was detected. Identified genes and processes included known mediators of ethanol response (Mx2, Fam111a, Itpr1, Gabra4, Agtr1a, LTP/LTD, renin-angiotensin signaling pathway), toxicity (Sult1c2a, Ces1, inflammatory response), as well as genes involved in regulation of important addiction-related brain systems such as dopamine, tachykinin or acetylcholine (Gng7, Tac4, Slc5a7). CONCLUSIONS The identified candidate genes may underlie differential ethanol preference in an animal model of alcoholism. COMMENT Names of genes are written in italics, while names of proteins are written in standard font. Names of human genes/proteins are written in all capital letters. Names of rodent genes/proteins are written in capital letter followed by small letters.
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Affiliation(s)
- Adrian M Stankiewicz
- Department of Animal Behaviour, Institute of Genetics and Animal Breeding, Polish Academy of Sciences, 05-552 Jastrzebiec, Poland
| | - Joanna Goscik
- Software Department, Faculty of Computer Science, Bialystok University of Technology, 15-351 Bialystok, Poland
| | - Wanda Dyr
- Department of Pharmacology and Physiology of the Nervous System, Institute of Psychiatry and Neurology, 02-957 Warsaw, Poland
| | - Grzegorz R Juszczak
- Department of Animal Behaviour, Institute of Genetics and Animal Breeding, Polish Academy of Sciences, 05-552 Jastrzebiec, Poland
| | - Danuta Ryglewicz
- First Department of Neurology, Institute of Psychiatry and Neurology, 02-957 Warsaw, Poland
| | - Artur H Swiergiel
- Department of Animal and Human Physiology, Faculty of Biology, University of Gdansk, 80-308 Gdansk, Poland; Department of Pharmacology, Toxicology and Neuroscience, Louisiana State University Health Sciences Center, Shreveport, LA71130, USA.
| | - Marek Wieczorek
- Department of Neurobiology, Faculty of Biology and Environmental Protection, University of Lodz, 90-236 Lodz, Poland
| | - Roman Stefanski
- Department of Pharmacology and Physiology of the Nervous System, Institute of Psychiatry and Neurology, 02-957 Warsaw, Poland
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17
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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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18
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Miczek KA, DeBold JF, Hwa LS, Newman EL, de Almeida RMM. Alcohol and violence: neuropeptidergic modulation of monoamine systems. Ann N Y Acad Sci 2015; 1349:96-118. [PMID: 26285061 DOI: 10.1111/nyas.12862] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Neurobiological processes underlying the epidemiologically established link between alcohol and several types of social, aggressive, and violent behavior remain poorly understood. Acute low doses of alcohol, as well as withdrawal from long-term alcohol use, may lead to escalated aggressive behavior in a subset of individuals. An urgent task will be to disentangle the host of interacting genetic and environmental risk factors in individuals who are predisposed to engage in escalated aggressive behavior. The modulation of 5-hydroxytryptamine impulse flow by gamma-aminobutyric acid (GABA) and glutamate, acting via distinct ionotropic and metabotropic receptor subtypes in the dorsal raphe nucleus during alcohol consumption, is of critical significance in the suppression and escalation of aggressive behavior. In anticipation and reaction to aggressive behavior, neuropeptides such as corticotropin-releasing factor, neuropeptide Y, opioid peptides, and vasopressin interact with monoamines, GABA, and glutamate to attenuate and amplify aggressive behavior in alcohol-consuming individuals. These neuromodulators represent novel molecular targets for intervention that await clinical validation. Intermittent episodes of brief social defeat during aggressive confrontations are sufficient to cause long-lasting neuroadaptations that can lead to the escalation of alcohol consumption.
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Affiliation(s)
- Klaus A Miczek
- Departments of Pharmacology, Psychiatry, and Neuroscience, Tufts University, Boston, Massachusetts.,Department of Psychology, Tufts University, Medford, Massachusetts
| | - Joseph F DeBold
- Department of Psychology, Tufts University, Medford, Massachusetts
| | - Lara S Hwa
- Department of Psychology, Tufts University, Medford, Massachusetts
| | - Emily L Newman
- Department of Psychology, Tufts University, Medford, Massachusetts
| | - Rosa M M de Almeida
- Department of Psychology, LPNeC, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil
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19
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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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20
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Skorput AGJ, Yeh HH. Effects of ethanol exposure in utero on Cajal-Retzius cells in the developing cortex. Alcohol Clin Exp Res 2015; 39:853-62. [PMID: 25845402 DOI: 10.1111/acer.12696] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2014] [Accepted: 01/31/2015] [Indexed: 11/28/2022]
Abstract
BACKGROUND Prenatal exposure to ethanol exerts teratogenic effects on the developing brain. Here, we tested the hypothesis that exposure to ethanol in utero alters the disposition of Cajal-Retzius cells that play a key role in orchestrating proliferation, migration, and laminar integration of cortical neurons in the embryonic cortex. METHODS Pregnant Ebf2-EGFP mice, harboring EGFP-fluorescent Cajal-Retzius cells, were subjected to a 2% w/w ethanol consumption regimen starting at neural tube closure and lasting throughout gestation. Genesis of Cajal-Retzius cells was assessed by means of 5-bromo-2-deoxyuridine (BrdU) immunofluorescence at embryonic day 12.5, their counts and distribution were determined between postnatal day (P)0 and P4, patch clamp electrophysiology was performed between P2 and P3 to analyze GABA-mediated synaptic activity, and open-field behavioral testing was conducted in P45-P50 adolescents. RESULTS In Ebf2-EGFP embryos exposed to ethanol in utero, we found increased BrdU labeling and expanded distribution of Cajal-Retzius cells in the cortical hem, pointing to increased genesis and proliferation. Postnatally, we found an increase in Cajal-Retzius cell number in cortical layer I. In addition, they displayed altered patterning of spontaneous GABA-mediated synaptic barrages and enhanced GABA-mediated synaptic activity, suggesting enhanced GABAergic tone. CONCLUSIONS These findings, together, underscore that Cajal-Retzius cells contribute to the ethanol-induced aberration of cortical development and abnormal GABAergic neurotransmission at the impactful time when intracortical circuits form.
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Affiliation(s)
- Alexander G J Skorput
- Department of Physiology and Neurobiology, Geisel School of Medicine at Dartmouth, Dartmouth-Hitchcock Medical Center, Lebanon, New Hampshire
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21
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Bhandage AK, Jin Z, Bazov I, Kononenko O, Bakalkin G, Korpi ER, Birnir B. GABA-A and NMDA receptor subunit mRNA expression is altered in the caudate but not the putamen of the postmortem brains of alcoholics. Front Cell Neurosci 2014; 8:415. [PMID: 25538565 PMCID: PMC4257153 DOI: 10.3389/fncel.2014.00415] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2014] [Accepted: 11/15/2014] [Indexed: 01/16/2023] Open
Abstract
Chronic consumption of alcohol by humans has been shown to lead to impairment of executive and cognitive functions. Here, we have studied the mRNA expression of ion channel receptors for glutamate and GABA in the dorsal striatum of post-mortem brains from alcoholics (n = 29) and normal controls (n = 29), with the focus on the caudate nucleus that is associated with the frontal cortex executive functions and automatic thinking and on the putamen area that is linked to motor cortices and automatic movements. The results obtained by qPCR assay revealed significant changes in the expression of specific excitatory ionotropic glutamate and inhibitory GABA-A receptor subunit genes in the caudate but not the putamen. Thus, in the caudate we found reduced levels of mRNAs encoding the GluN2A glutamate receptor and the δ, ε, and ρ2 GABA-A receptor subunits, and increased levels of the mRNAs encoding GluD1, GluD2, and GABA-A γ1 subunits in the alcoholics as compared to controls. Interestingly in the controls, 11 glutamate and 5 GABA-A receptor genes were more prominently expressed in the caudate than the putamen (fold-increase varied from 1.24 to 2.91). Differences in gene expression patterns between the striatal regions may underlie differences in associated behavioral outputs. Our results suggest an altered balance between caudate-mediated voluntarily controlled and automatic behaviors in alcoholics, including diminished executive control on goal-directed alcohol-seeking behavior.
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Affiliation(s)
- Amol K Bhandage
- Molecular Physiology and Neuroscience, Biomedical Center, Uppsala University Uppsala, Sweden
| | - Zhe Jin
- Molecular Physiology and Neuroscience, Biomedical Center, Uppsala University Uppsala, Sweden
| | - Igor Bazov
- Pharmacology, Institute of Biomedicine, University of Helsinki Helsinki, Finland
| | - Olga Kononenko
- Pharmacology, Institute of Biomedicine, University of Helsinki Helsinki, Finland
| | - Georgy Bakalkin
- Pharmacology, Institute of Biomedicine, University of Helsinki Helsinki, Finland
| | - Esa R Korpi
- Department of Pharmaceutical Bioscience (Biological Research on Drug Dependence), Biomedical Center, Uppsala University Uppsala, Sweden
| | - Bryndis Birnir
- Molecular Physiology and Neuroscience, Biomedical Center, Uppsala University Uppsala, Sweden
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22
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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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23
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Melroy WE, Stephens SH, Sakai JT, Kamens HM, McQueen MB, Corley RP, Stallings MC, Hopfer CJ, Krauter KS, Brown SA, Hewitt JK, Ehringer MA. Examination of genetic variation in GABRA2 with conduct disorder and alcohol abuse and dependence in a longitudinal study. Behav Genet 2014; 44:356-67. [PMID: 24687270 DOI: 10.1007/s10519-014-9653-y] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2013] [Accepted: 03/15/2014] [Indexed: 02/06/2023]
Abstract
Previous studies have shown associations between single nucleotide polymorphisms (SNPs) in gamma aminobutyric acid receptor alpha 2 (GABRA2) and adolescent conduct disorder (CD) and alcohol dependence in adulthood, but not adolescent alcohol dependence. The present study was intended as a replication and extension of this work, focusing on adolescent CD, adolescent alcohol abuse and dependence (AAD), and adult AAD. Family based association tests were run using Hispanics and non-Hispanic European American subjects from two independent longitudinal samples. Although the analysis provided nominal support for an association with rs9291283 and AAD in adulthood and CD in adolescence, the current study failed to replicate previous associations between two well replicated GABRA2 SNPs and CD and alcohol dependence. Overall, these results emphasize the utility of including an independent replication sample in the study design, so that the results from an individual sample can be weighted in the context of its reproducibility.
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Affiliation(s)
- Whitney E Melroy
- Institute for Behavioral Genetics, University of Colorado, Boulder, CO, USA
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Altered localization of the δ subunit of the GABAA receptor in the thalamus of α4 subunit knockout mice. Neurochem Res 2013; 39:1104-17. [PMID: 24352815 DOI: 10.1007/s11064-013-1202-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2013] [Revised: 11/05/2013] [Accepted: 11/13/2013] [Indexed: 10/25/2022]
Abstract
The α4 subunit of the GABAA receptor (GABAAR) is highly expressed in the thalamus where receptors containing the α4 and δ subunits are major mediators of tonic inhibition. The α4 subunit also exhibits considerable plasticity in a number of physiological and pathological conditions, raising questions about the expression of remaining GABAAR subunits when the α4 subunit is absent. Immunohistochemical studies of an α4 subunit knockout (KO) mouse revealed a substantial decrease in δ subunit expression in the ventrobasal nucleus of the thalamus as well as other forebrain regions where the α4 subunit is normally expressed. In contrast, several subunits associated primarily with phasic inhibition, including the α1 and γ2 subunits, were moderately increased. Intracellular localization of the δ subunit was also altered. While δ subunit labeling was decreased within the neuropil, some labeling remained in the cell bodies of many neurons in the ventrobasal nucleus. Confocal microscopy demonstrated co-localization of this labeling with an endoplasmic reticulum marker, and electron microscopy demonstrated increased immunogold labeling near the endoplasmic reticulum in the α4 KO mouse. These results emphasize the strong partnership of the δ and α4 subunit in the thalamus and suggest that the α4 subunit of the GABAAR plays a critical role in trafficking of the δ subunit to the neuronal surface. The findings also suggest that previously observed reductions in tonic inhibition in the α4 subunit KO mouse are likely to be related to alterations in δ subunit expression, in addition to loss of the α4 subunit.
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Hyposensitivity to gamma-aminobutyric acid in the ventral tegmental area during alcohol withdrawal: reversal by histone deacetylase inhibitors. Neuropsychopharmacology 2013; 38:1674-84. [PMID: 23474591 PMCID: PMC3717553 DOI: 10.1038/npp.2013.65] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/31/2012] [Revised: 02/01/2013] [Accepted: 02/21/2013] [Indexed: 11/08/2022]
Abstract
Putative dopaminergic (pDAergic) ventral tegmental area (VTA) neurons have an important role in alcohol addiction. Acute ethanol increases the activity of pDAergic neurons, and withdrawal from repeated ethanol administration produces a decreased sensitivity of pDAergic VTA neurons to GABA. Recent studies show that behavioral changes induced by chronic alcohol are reversed by inhibitors of histone deacetylases (HDACs). Whether HDAC-induced histone modifications regulate changes in GABA sensitivity of VTA pDAergic neurons during withdrawal is unknown. Here, we investigated modulation of withdrawal-induced changes in GABA sensitivity of pDAergic VTA neurons by HDAC inhibitors (HDACi), and also measured the levels of HDAC2, histone (H3-K9) acetylation, and GABA-Aα1 receptor (GABA (A-α1) R) subunit in VTA during ethanol withdrawal. Mice were injected intraperitoneally (ip) with either ethanol (3.5 g/kg) or saline twice daily for 3 weeks. In recordings from pDAergic VTA neurons in brain slices from ethanol-withdrawn mice, sensitivity to GABA (50-500 μM) was reduced. In brain slices from ethanol-withdrawn mice incubated with the HDACi SAHA (vorinostat) or trichostatin A (TSA) for 2 h, the hyposensitivity of pDAergic VTA neurons to GABA was significantly attenuated. There was no effect of TSA or SAHA on GABA sensitivity of pDAergic VTA neurons from saline-treated mice. In addition, ethanol withdrawal was associated with an increase in levels of HDAC2 and a decrease in histone (H3-K9) acetylation and levels of GABA (A-α1) R subunits in the VTA. Therefore, blockade of upregulation of HDAC2 by HDACi normalizes GABA hyposensitivity of pDAergic neurons developed during withdrawal after chronic ethanol treatment, which suggests the possibility that inhibition of HDACs can reverse ethanol-induced neuroadaptational changes in reward circuitry.
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Abstract
Ethanol (EtOH) has effects on numerous cellular molecular targets, and alterations in synaptic function are prominent among these effects. Acute exposure to EtOH activates or inhibits the function of proteins involved in synaptic transmission, while chronic exposure often produces opposing and/or compensatory/homeostatic effects on the expression, localization, and function of these proteins. Interactions between different neurotransmitters (e.g., neuropeptide effects on release of small molecule transmitters) can also influence both acute and chronic EtOH actions. Studies in intact animals indicate that the proteins affected by EtOH also play roles in the neural actions of the drug, including acute intoxication, tolerance, dependence, and the seeking and drinking of EtOH. This chapter reviews the literature describing these acute and chronic synaptic effects of EtOH and their relevance for synaptic transmission, plasticity, and behavior.
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Affiliation(s)
- David M Lovinger
- Laboratory for Integrative Neuroscience, NIAAA, 5625 Fishers Lane, Room TS-13A, Rockville, MD 20852, USA.
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Jin Z, Bazov I, Kononenko O, Korpi ER, Bakalkin G, Birnir B. Selective Changes of GABA(A) Channel Subunit mRNAs in the Hippocampus and Orbitofrontal Cortex but not in Prefrontal Cortex of Human Alcoholics. Front Cell Neurosci 2012; 5:30. [PMID: 22319468 PMCID: PMC3249692 DOI: 10.3389/fncel.2011.00030] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2011] [Accepted: 12/14/2011] [Indexed: 11/13/2022] Open
Abstract
Alcohol dependence is a common chronic relapsing disorder. The development of alcohol dependence has been associated with changes in brain GABA(A) channel-mediated neurotransmission and plasticity. We have examined mRNA expression of the GABA(A) channel subunit genes in three brain regions in individuals with or without alcohol dependence using quantitative real-time PCR assay. The levels of selective GABA(A) channel subunit mRNAs were altered in specific brain regions in alcoholic subjects. Significant increase in the α1, α4, α5, β1, and γ1 subunit mRNAs in the hippocampal dentate gyrus region, and decrease in the β2 and δ subunit mRNAs in the orbitofrontal cortex were identified whereas no changes in the dorsolateral prefrontal cortex were detected. The data increase our understanding of the role of GABA(A) channels in the development of alcohol dependence.
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Affiliation(s)
- Zhe Jin
- The Division of Molecular Physiology and Neuroscience, Department of Neuroscience, Uppsala University Uppsala, Sweden
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28
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Quoilin C, Didone V, Tirelli E, Quertemont E. Chronic ethanol exposure during adolescence alters the behavioral responsiveness to ethanol in adult mice. Behav Brain Res 2011; 229:1-9. [PMID: 22227505 DOI: 10.1016/j.bbr.2011.12.039] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2011] [Revised: 12/22/2011] [Accepted: 12/25/2011] [Indexed: 11/26/2022]
Abstract
Alcohol exposure during early adolescence is believed to durably alter the behavioral properties of ethanol, increasing the likelihood of later alcohol-related disorders. The aim of the present experiments was to characterize changes in the behavioral effects of ethanol in adult female Swiss mice after a chronic ethanol exposure during adolescence, extending from postnatal day 28 to postnatal day 42. After a chronic ethanol exposure during adolescence (daily injections of 0, 2.5 or 4 g/kg ethanol for 14 consecutive days), adult mice were tested at postnatal day 63. The locomotor stimulant effects of ethanol, together with ethanol sensitization were tested in experiment 1. In experiment 2, the sedative effects of ethanol were assessed with the loss of righting reflex procedure. Finally, in experiment 3, the anxiolytic effects of ethanol were tested with the light/dark box test. Adult mice chronically exposed to ethanol during adolescence showed a lower basal locomotor activity, but higher locomotor stimulant effects of ethanol than non-exposed mice. Additionally, these adult mice developed higher rates of ethanol sensitization after chronic re-exposure to ethanol in adulthood. Adult mice exposed to ethanol during adolescence also had a stronger tolerance to the sedative effects of high ethanol doses, although they showed no evidence of changes in the anxiolytic effects of ethanol. These results are in agreement with the thesis that chronic alcohol consumption during adolescence, especially in high amounts, increases the risk of later alcohol-related disorders.
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Affiliation(s)
- Caroline Quoilin
- Département Psychologie, Cognition et Comportement, Université de Liège, Belgium
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Suryanarayanan A, Liang J, Meyer EM, Lindemeyer AK, Chandra D, Homanics GE, Sieghart W, Olsen RW, Spigelman I. Subunit Compensation and Plasticity of Synaptic GABA(A) Receptors Induced by Ethanol in α4 Subunit Knockout Mice. Front Neurosci 2011; 5:110. [PMID: 21977012 PMCID: PMC3178803 DOI: 10.3389/fnins.2011.00110] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2011] [Accepted: 08/29/2011] [Indexed: 12/29/2022] Open
Abstract
There is considerable evidence that ethanol (EtOH) potentiates γ-aminobutyric acid type A receptor (GABAAR) action, but only GABAARs containing δ subunits appear sensitive to low millimolar EtOH. The α4 and δ subunits co-assemble into GABAARs which are relatively highly expressed at extrasynaptic locations in the dentate gyrus where they mediate tonic inhibition. We previously demonstrated reversible- and time-dependent changes in GABAAR function and subunit composition in rats after single-dose EtOH intoxication. We concluded that early tolerance to EtOH occurs by over-activation and subsequent internalization of EtOH-sensitive extrasynaptic α4βδ-GABAARs. Based on this hypothesis, any highly EtOH-sensitive GABAARs should be subject to internalization following exposure to suitably high EtOH doses. To test this, we studied the GABAARs in mice with a global deletion of the α4 subunit (KO). The dentate granule cells of these mice exhibited greatly reduced tonic currents and greatly reduced potentiation by acutely applied EtOH, whereas synaptic currents showed heightened sensitivity to low EtOH concentrations. The hippocampus of naive KO mice showed reduced δ subunit protein levels, but increased α2, and γ2 levels compared to wild-type (WT) controls, suggesting at least partial compensation by these subunits in synaptic, highly EtOH-sensitive GABAARs of KO mice. In WT mice, cross-linking and Western blot analysis at 1 h after an EtOH challenge (3.5 g/kg, i.p.) revealed increased intracellular fraction of the α1, α4, and δ, but not α2, α5, or γ2 subunits. By contrast, we observed significant internalization of α1, α2, δ, and γ2 subunits after a similar EtOH challenge in KO mice. Synaptic currents from naïve KO mice were more sensitive to potentiation by zolpidem (0.3 μM, requiring α1/α2, inactive at α4/5 GABAARs) than those from naïve WT mice. At 1 h after EtOH, synaptic currents of WT mice were unchanged, whereas those of KO mice were significantly less sensitive to zolpidem, suggesting decreases in functional α1/2βγ GABAARs. These data further support our hypothesis that EtOH intoxication induces GABAAR plasticity via internalization of highly EtOH-sensitive GABAARs.
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Affiliation(s)
- Asha Suryanarayanan
- Division of Oral Biology and Medicine, School of Dentistry, University of California Los Angeles, CA, USA
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Turkmen S, Backstrom T, Wahlstrom G, Andreen L, Johansson IM. Tolerance to allopregnanolone with focus on the GABA-A receptor. Br J Pharmacol 2011; 162:311-27. [PMID: 20883478 DOI: 10.1111/j.1476-5381.2010.01059.x] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Many studies have suggested a relationship between stress, sex steroids, and negative mental and mood changes in humans. The progesterone metabolite allopregnanolone is a potent endogenous ligand of the γ-amino butyric acid -A (GABA-A) receptor, and the most discussed neuroactive steroid. Variations in the levels of neuroactive steroids that influence the activity of the GABA-A receptor cause a vulnerability to mental and emotional pathology. There are physiological conditions in which allopregnanolone production increases acutely (e.g. stress) or chronically (e.g. menstrual cycle, pregnancy), thus exposing the GABA-A receptor to high and continuous allopregnanolone concentrations. In such conditions, tolerance to allopregnanolone may develop. We have shown that both acute and chronic tolerances can develop to the effects of allopregnanolone. Following the development of acute allopregnanolone tolerance, there is a decrease in the abundance of the GABA-A receptor α4 subunit and the expression of the α4 subunit mRNA in the ventral-posteriomedial nucleus of the thalamus. Little is known about the mechanism behind allopregnanolone tolerance and its effects on assembly of the GABA-A receptor composition. The exact mechanism of the allopregnanolone tolerance phenomena remains unclear. The purpose of this review is to summarize certain aspects of current knowledge concerning allopregnanolone tolerance and changes in the GABA-A receptors.
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Affiliation(s)
- Sahruh Turkmen
- Department of Obstetrics & Gynaecology, Sundsvall County Hospital, Sweden.
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31
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Sanna E, Talani G, Obili N, Mascia MP, Mostallino MC, Secci PP, Pisu MG, Biggio F, Utzeri C, Olla P, Biggio G, Follesa P. Voluntary Ethanol Consumption Induced by Social Isolation Reverses the Increase of α(4)/δ GABA(A) Receptor Gene Expression and Function in the Hippocampus of C57BL/6J Mice. Front Neurosci 2011; 5:15. [PMID: 21347217 PMCID: PMC3039156 DOI: 10.3389/fnins.2011.00015] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2010] [Accepted: 01/25/2011] [Indexed: 11/20/2022] Open
Abstract
Post-weaning social isolation (SI) is a model of prolonged mild stress characterized by behavioral and neurochemical alterations. We used SI in C57BL/6J mice to investigate the effects of ethanol (EtOH) in the free-choice drinking paradigm on gene expression and function of γ-aminobutyric acid type A receptors (GABAARs) and the role of neuroactive steroids in the actions of EtOH in the hippocampus. SI stress induced a marked reduction in hippocampal 3α-hydroxy-5α-pregnan-20-one (3α,5α-TH PROG) and was associated with molecular and functional changes of the GABAAR. The gene expression of the α4 and δ subunits was increased in the hippocampus of SI C57BL/6J mice; the expression of the γ2 subunit was decreased whereas that of the α1 did not change. Patch-clamp recordings in dentate gyrus (DG) granule cells obtained from SI C57BL/6J mice revealed a greater enhancement of tonic currents induced by α-(4,5,6,7-tetrahydroisoxazolo[5,4-c] pyridin-3-ol (THIP) compared to that in control C57BL/6J mice. These neurochemical, molecular and functional changes observed in SI C57BL/6J mice were associated with an increased EtOH intake and EtOH preference. Nevertheless, the increase in EtOH consumption did not restore the reduction in hippocampal 3α,5α-TH PROG induced by SI. EtOH self-administration blocked the changes in gene expression of the α4 subunit but not those of the δ and γ2 subunits induced by SI. In addition, EtOH self-administration did not block the SI-induced changes in GABAAR-mediated tonic inhibition in hippocampal granule cells but increased the frequency of basal GABAergic sIPSCs in DG granule cells. We conclude that self-administration of EtOH selectively abolishes the increase of α4 subunit but not other neurochemical, molecular, and functional modifications induced by SI prolonged mild stress.
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Affiliation(s)
- Enrico Sanna
- Section of Neuroscience, Department of Experimental Biology, Center of Excellence for the Neurobiology of Dependence, University of Cagliari Monserrato, Cagliari, Italy
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Van Skike CE, Botta P, Chin VS, Tokunaga S, McDaniel JM, Venard J, Diaz-Granados JL, Valenzuela CF, Matthews DB. Behavioral effects of ethanol in cerebellum are age dependent: potential system and molecular mechanisms. Alcohol Clin Exp Res 2010; 34:2070-80. [PMID: 20860615 DOI: 10.1111/j.1530-0277.2010.01303.x] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
BACKGROUND Adolescent rats are less sensitive to the motor-impairing effects of ethanol than adults. However, the cellular and molecular mechanisms underlying this age-dependent effect of ethanol have yet to be fully elucidated. METHOD Male rats of various ages were used to investigate ethanol-induced ataxia and its underlying cellular correlates. In addition, Purkinje neurons from adolescent and adult rats were recorded both in vivo and in vitro. Finally, protein kinase C (PKCγ) expression was determined in 3 brain regions in both adolescent and adult rats. RESULTS The present multi-methodological investigation confirms that adolescents are less sensitive to the motor-impairing effects of ethanol, and this differential effect is not because of differential blood ethanol levels. In addition, we identify a particular cellular correlate that may underlie the reduced motor impairment. Specifically, the in vivo firing rate of cerebellar Purkinje neurons recorded from adolescent rats was insensitive to an acute ethanol challenge, while the firing rate of adult cerebellar Purkinje neurons was significantly depressed. Finally, it is demonstrated that PKCγ expression in the cortex and cerebellum mirrors the age-dependent effect of ethanol: adolescents have significantly less PKCγ expression compared to adults. CONCLUSIONS Adolescents are less sensitive than adults to the motor-impairing effects of ethanol, and a similar effect is seen with in vivo electrophysiological recordings of cerebellar Purkinje neurons. While still under investigation, PKCγ expression mirrors the age effect of ethanol and may contribute to the age-dependent differences in the ataxic effects of ethanol.
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Affiliation(s)
- Candice E Van Skike
- Department of Psychology and Neuroscience, Baylor University Addictions Research Consortium, Waco, Texas, USA
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Takahashi A, Kwa C, DeBold JF, Miczek KA. GABA(A) receptors in the dorsal raphé nucleus of mice: escalation of aggression after alcohol consumption. Psychopharmacology (Berl) 2010; 211:467-77. [PMID: 20589493 PMCID: PMC2992972 DOI: 10.1007/s00213-010-1920-x] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/26/2010] [Accepted: 06/11/2010] [Indexed: 11/28/2022]
Abstract
RATIONALE The dorsal raphé nucleus (DRN), the origin for serotonin (5-HT) in forebrain areas, has been implicated in the neural control of escalated aggression. Gamma aminobutyric acid type-A (GABA(A)) and type-B (GABA(B)) receptors are expressed in the DRN and modulate 5-HT neuronal activity, and both play a role in the behavioral effect of alcohol. OBJECTIVE The purpose of this study is to examine the interaction between drugs acting on GABA receptors in the DRN and alcohol in their effects on aggressive behaviors. METHOD Male CFW mice, housed with a female, were trained to self-administer ethanol (1.0 g/kg) or water via an operant conditioning panel in their home cage. Immediately after they drank either ethanol or water, the animals were microinfused with a GABAergic drug into the DRN, and their aggressive behaviors were assessed 10 min later. Muscimol (0.006 nmol), a GABA(A) receptor agonist, escalated alcohol-heightened aggression but had no effect in the absence of ethanol. This effect of muscimol was prominent in the animals that showed alcohol-heightened aggression, but not the animals that reduced or did not change aggressive behavior after ethanol infusion compared to water. On the other hand, the GABA(B) agonist baclofen (0.06 nmol) increased aggressive behavior similarly in both water and ethanol conditions. Antagonists of the GABA(A) and GABA(B) receptors, bicuculline (0.006 nmol) and phaclofen (0.3 nmol) respectively, did not suppress heightened-aggressive behavior induced by ethanol self-administration. CONCLUSION GABA(A) receptors in the DRN are one of the neurobiological targets of alcohol-heightened aggression. Activation of the GABA(B) receptors in the DRN also produced escalated aggression, but that is independent of the effect of alcohol.
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Affiliation(s)
- Aki Takahashi
- Department of Psychology, Tufts University, Bacon Hall, 530 Boston Ave, Medford, MA 02155, USA,
| | - Carolyn Kwa
- Department of Psychology, Tufts University, Bacon Hall, 530 Boston Ave, Medford, MA 02155, USA,
| | - Joseph F. DeBold
- Department of Psychology, Tufts University, Bacon Hall, 530 Boston Ave, Medford, MA 02155, USA,
| | - Klaus A. Miczek
- Department of Psychology, Tufts University, Bacon Hall, 530 Boston Ave, Medford, MA 02155, USA,
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Young BW, Sengelaub DR, Steinmetz JE. MK-801 administration during neonatal ethanol withdrawal attenuates interpositus cell loss and juvenile eyeblink conditioning deficits. Alcohol 2010; 44:359-69. [PMID: 20598489 DOI: 10.1016/j.alcohol.2009.12.002] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2009] [Revised: 12/17/2009] [Accepted: 12/30/2009] [Indexed: 02/06/2023]
Abstract
Binge-level doses of ethanol have been demonstrated to severely disrupt the cerebellum and cerebellum-dependent tasks when administered to rodent subjects during the early postnatal period. N-methyl-d-aspartic acid (NMDA) receptor-mediated excitotoxicity associated with ethanol withdrawal has been implicated as a significant component contributing to neurotoxic effects resulting from early ethanol exposure, and studies using MK-801 (dizocilpine) have reported protection from ethanol-induced damage. The present study examined whether the administration of MK-801 during ethanol withdrawal would ameliorate ethanol-associated cell death in the interpositus nucleus of the cerebellum and behavioral deficits in a cerebellar dependent task. Long Evans rat pups were treated with ethanol (5.25 g/kg) in a binge-like manner on postnatal day 6 using intragastric intubation. Subjects then received an injection of MK-801 (0.5mg/kg) or vehicle during withdrawal, 30h after ethanol exposure. Rats were then trained on an eyeblink classical conditioning task as juveniles (40 days of age), and cerebellar interpositus nucleus numbers were assessed after conditioning. Ethanol-exposed subjects exhibited reductions in neuronal populations and behavioral deficits during eyeblink conditioning. However, MK-801 administration significantly attenuated observed deficiencies, suggesting a protective effect resulting from MK-801 treatment during ethanol withdrawal. These results support the role of NMDA receptor-mediated excitotoxicity as a component mechanism by which ethanol produces teratogenicity. Additionally, our findings support previous reports that have shown correlations between dependent measures of eyeblink classical-conditioning behavior and unbiased cell counts in the interpositus nucleus.
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Affiliation(s)
- Brandt W Young
- Department of Physiology, Northwestern University, Chicago, IL, USA.
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35
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Kumar S, Suryanarayanan A, Boyd KN, Comerford CE, Lai MA, Ren Q, Morrow AL. Ethanol reduces GABAA alpha1 subunit receptor surface expression by a protein kinase Cgamma-dependent mechanism in cultured cerebral cortical neurons. Mol Pharmacol 2010; 77:793-803. [PMID: 20159950 DOI: 10.1124/mol.109.063016] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Prolonged ethanol exposure causes central nervous system hyperexcitability that involves a loss of GABAergic inhibition. We previously demonstrated that long-term ethanol exposure enhances the internalization of synaptic GABA(A) receptors composed of alpha1beta2/3gamma2 subunits. However, the mechanisms of ethanol-mediated internalization are unknown. This study explored the effect of ethanol on surface expression of GABA(A) alpha1 subunit-containing receptors in cultured cerebral cortical neurons and the role of protein kinase C (PKC) beta, gamma, and epsilon isoforms in their trafficking. Cultured neurons were prepared from rat pups on postnatal day 1 and maintained for 18 days. Cells were exposed to ethanol, and surface receptors were isolated by biotinylation and P2 fractionation, whereas functional analysis was conducted by whole-cell patch-clamp recording of GABA- and zolpidem-evoked responses. Ethanol exposure for 4 h decreased biotinylated surface expression of GABA(A) receptor alpha1 subunits and reduced zolpidem (100 nM) enhancement of GABA-evoked currents. The PKC activator phorbol-12,13-dibutyrate mimicked the effect of ethanol, and the selective PKC inhibitor calphostin C prevented ethanol-induced internalization of these receptors. Ethanol exposure for 4 h also increased the colocalization and coimmunoprecipitation of PKCgamma with alpha1 subunits, whereas PKCbeta/alpha1 association and PKCepsilon/alpha1 colocalization were not altered by ethanol exposure. Selective PKCgamma inhibition by transfection of selective PKCgamma small interfering RNAs blocked ethanol-induced internalization of GABA(A) receptor alpha1 subunits, whereas PKCbeta inhibition using pseudo-PKCbeta had no effect. These findings suggest that ethanol exposure selectively alters PKCgamma translocation to GABA(A) receptors and PKCgamma regulates GABA(A) alpha1 receptor trafficking after ethanol exposure.
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Affiliation(s)
- Sandeep Kumar
- Department of Psychiatry, Bowles Center for Alcohol Studies, University of North Carolina School of Medicine, Chapel Hill, NC 27599, USA
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36
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Uusi-Oukari M, Korpi ER. Regulation of GABA(A) receptor subunit expression by pharmacological agents. Pharmacol Rev 2010; 62:97-135. [PMID: 20123953 DOI: 10.1124/pr.109.002063] [Citation(s) in RCA: 152] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The gamma-aminobutyric acid (GABA) type A receptor system, the main fast-acting inhibitory neurotransmitter system in the brain, is the pharmacological target for many drugs used clinically to treat, for example, anxiety disorders and epilepsy, and to induce and maintain sedation, sleep, and anesthesia. These drugs facilitate the function of pentameric GABA(A) receptors that exhibit widespread expression in all brain regions and large structural and pharmacological heterogeneity as a result of composition from a repertoire of 19 subunit variants. One of the main problems in clinical use of GABA(A) receptor agonists is the development of tolerance. Most drugs, in long-term use and during withdrawal, have been associated with important modulations of the receptor subunit expression in brain-region-specific manner, participating in the mechanisms of tolerance and dependence. In most cases, the molecular mechanisms of regulation of subunit expression are poorly known, partly as a result of neurobiological adaptation to altered neuronal function. More knowledge has been obtained on the mechanisms of GABA(A) receptor trafficking and cell surface expression and the processes that may contribute to tolerance, although their possible pharmacological regulation is not known. Drug development for neuropsychiatric disorders, including epilepsy, alcoholism, schizophrenia, and anxiety, has been ongoing for several years. One key step to extend drug development related to GABA(A) receptors is likely to require deeper understanding of the adaptational mechanisms of neurons, receptors themselves with interacting proteins, and finally receptor subunits during drug action and in neuropsychiatric disease processes.
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Affiliation(s)
- Mikko Uusi-Oukari
- Department of Pharmacology, Drug Development and Therapeutics, University of Turku, Itainen Pitkakatu 4, 20014 Turku, Finland.
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Fleming RL, Manis PB, Morrow AL. The effects of acute and chronic ethanol exposure on presynaptic and postsynaptic gamma-aminobutyric acid (GABA) neurotransmission in cultured cortical and hippocampal neurons. Alcohol 2009; 43:603-18. [PMID: 20004338 DOI: 10.1016/j.alcohol.2009.10.006] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2009] [Revised: 10/07/2009] [Accepted: 10/07/2009] [Indexed: 01/04/2023]
Abstract
Decades after ethanol was first described as a gamma-aminobutyric acid (GABA) mimetic, the precise mechanisms that produce the acute effects of ethanol and the physiological adaptations that underlie ethanol tolerance and dependence remain unclear. Although a substantial body of evidence suggests that ethanol acts on GABAergic neurotransmission to enhance inhibition in the central nervous system, the precise mechanisms underlying the physiological effects of both acute and chronic ethanol exposure are still under investigation. We have used in vitro ethanol exposure followed by recording of miniature inhibitory postsynaptic currents (mIPSCs) to determine whether acute or chronic ethanol exposure directly alters synaptic GABA(A) receptor (GABA(A)R) function or GABA release in cultured cortical and hippocampal neurons. Acute ethanol exposure slightly increased the duration of mIPSCs in hippocampal neurons but did not alter mIPSC kinetics in cortical neurons. Acute ethanol exposure did not change mIPSC frequency in either hippocampal or cortical neurons. One day of chronic ethanol exposure produced a transient decrease in mIPSC duration in cortical neurons but did not alter mIPSC kinetics in hippocampal neurons. Chronic ethanol exposure did not change mIPSC frequency in either hippocampal or cortical neurons. Chronic ethanol exposure also did not produce substantial cross-tolerance to a benzodiazepine in either hippocampal or cortical neurons. The results suggest that ethanol exposure in vitro has limited effects on synaptic GABA(A)R function and action potential-independent GABA release in cultured neurons and that ethanol exposure in cultured cortical and hippocampal neurons may not reproduce all the effects that occur in vivo and in acute brain slices.
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Kumar S, Porcu P, Werner DF, Matthews DB, Diaz-Granados JL, Helfand RS, Morrow AL. The role of GABA(A) receptors in the acute and chronic effects of ethanol: a decade of progress. Psychopharmacology (Berl) 2009; 205:529-64. [PMID: 19455309 PMCID: PMC2814770 DOI: 10.1007/s00213-009-1562-z] [Citation(s) in RCA: 342] [Impact Index Per Article: 22.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/17/2008] [Accepted: 04/30/2009] [Indexed: 12/12/2022]
Abstract
The past decade has brought many advances in our understanding of GABA(A) receptor-mediated ethanol action in the central nervous system. We now know that specific GABA(A) receptor subtypes are sensitive to ethanol at doses attained during social drinking while other subtypes respond to ethanol at doses attained by severe intoxication. Furthermore, ethanol increases GABAergic neurotransmission through indirect effects, including the elevation of endogenous GABAergic neuroactive steroids, presynaptic release of GABA, and dephosphorylation of GABA(A) receptors promoting increases in GABA sensitivity. Ethanol's effects on intracellular signaling also influence GABAergic transmission in multiple ways that vary across brain regions and cell types. The effects of chronic ethanol administration are influenced by adaptations in GABA(A) receptor function, expression, trafficking, and subcellular localization that contribute to ethanol tolerance, dependence, and withdrawal hyperexcitability. Adolescents exhibit altered sensitivity to ethanol actions, the tendency for higher drinking and longer lasting GABAergic adaptations to chronic ethanol administration. The elucidation of the mechanisms that underlie adaptations to ethanol exposure are leading to a better understanding of the regulation of inhibitory transmission and new targets for therapies to support recovery from ethanol withdrawal and alcoholism.
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Affiliation(s)
- Sandeep Kumar
- Department of Psychiatry, Bowles Center for Alcohol Studies, University of North Carolina School of Medicine, 3027 Thurston-Bowles Building, CB #7178, Chapel Hill, NC 27599-7178, USA
| | - Patrizia Porcu
- Department of Psychiatry, Bowles Center for Alcohol Studies, University of North Carolina School of Medicine, 3027 Thurston-Bowles Building, CB #7178, Chapel Hill, NC 27599-7178, USA
| | - David F. Werner
- Department of Psychiatry, Bowles Center for Alcohol Studies, University of North Carolina School of Medicine, 3027 Thurston-Bowles Building, CB #7178, Chapel Hill, NC 27599-7178, USA
| | | | | | - Rebecca S. Helfand
- Department of Psychology and Neuroscience, Baylor University, Waco, TX, USA
| | - A. Leslie Morrow
- Department of Psychiatry, Bowles Center for Alcohol Studies, University of North Carolina School of Medicine, 3027 Thurston-Bowles Building, CB #7178, Chapel Hill, NC 27599-7178, USA, Department of Pharmacology, Bowles Center for Alcohol Studies, University of North Carolina School of Medicine, 3027 Thurston-Bowles Building, CB #7178, Chapel Hill, NC 27599-7178, USA
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Enoch MA. The role of GABA(A) receptors in the development of alcoholism. Pharmacol Biochem Behav 2008; 90:95-104. [PMID: 18440057 DOI: 10.1016/j.pbb.2008.03.007] [Citation(s) in RCA: 164] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/20/2007] [Revised: 02/29/2008] [Accepted: 03/05/2008] [Indexed: 11/18/2022]
Abstract
Alcoholism is a common, heritable, chronic relapsing disorder. GABA(A) receptors undergo allosteric modulation by ethanol, anesthetics, benzodiazepines and neurosteroids and have been implicated in the acute as well as the chronic effects of ethanol including tolerance, dependence and withdrawal. Medications targeting GABA(A) receptors ameliorate the symptoms of acute withdrawal. Ethanol induces plasticity in GABA(A) receptors: tolerance is associated with generally decreased GABA(A) receptor activation and differentially altered subunit expression. The dopamine (DA) mesolimbic reward pathway originating in the ventral tegmental area (VTA), and interacting stress circuitry play an important role in the development of addiction. VTA GABAergic interneurons are the primary inhibitory regulators of DA neurons and a subset of VTA GABA(A) receptors may be implicated in the switch from heavy drinking to dependence. GABA(A) receptors modulate anxiety and response to stress; important elements of sustained drinking and relapse. The GABA(A) receptor subunit genes clustered on chromosome 4 are highly expressed in the reward pathway. Several recent studies have provided strong evidence that one of these genes, GABRA2, is implicated in alcoholism in humans. The influence of the interaction between ethanol and GABA(A) receptors in the reward pathway on the development of alcoholism together with genetic and epigenetic vulnerabilities will be explored in this review.
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MESH Headings
- Alcohol Drinking/genetics
- Alcohol Drinking/psychology
- Alcoholism/drug therapy
- Alcoholism/genetics
- Alcoholism/physiopathology
- Animals
- Chromosomes, Human, Pair 4/genetics
- Chromosomes, Human, Pair 4/physiology
- Chromosomes, Human, Pair 5/genetics
- Chromosomes, Human, Pair 5/physiology
- Dopamine/physiology
- Gene Expression Regulation/physiology
- Humans
- Neuronal Plasticity/physiology
- Receptors, GABA-A/chemistry
- Receptors, GABA-A/drug effects
- Receptors, GABA-A/genetics
- Receptors, GABA-A/physiology
- Receptors, Presynaptic/drug effects
- Reward
- Steroids/physiology
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Affiliation(s)
- Mary-Anne Enoch
- Laboratory of Neurogenetics, National Institute on Alcohol Abuse and Alcoholism, NIH, Bethesda, MD, USA.
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40
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Eva C, Mele P, Collura D, Nai A, Pisu MG, Serra M, Biggio G. Modulation of neuropeptide Y and Y1 receptor expression in the amygdala by fluctuations in the brain content of neuroactive steroids during ethanol drinking discontinuation in Y1R/LacZ transgenic mice. J Neurochem 2007; 104:1043-54. [PMID: 18036156 DOI: 10.1111/j.1471-4159.2007.05077.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Previous studies have shown that GABAergic neuroactive steroids increase Y1 receptor (Y1R) gene expression in the amygdala of Y1R/LacZ transgenic mice, harbouring the murine Y1R gene promoter linked to a LacZ reporter gene. As ethanol is known to increase GABAergic neuroactive steroids, we investigated the relationship between fluctuations in the brain content of neuroactive steroids induced by chronic voluntary ethanol consumption or ethanol discontinuation and both the level of neuropeptide Y (NPY) immunoreactivity and Y1R gene expression in the amygdala of Y1R/LacZ transgenic mice. Ethanol discontinuation (48 h) after voluntary consumption of consecutive solutions of 3%, 6%, 10% and 20% (v/v) ethanol over 4 weeks produced an anxiety-like behaviour as measured by elevated plus maze. Voluntary ethanol intake increased the cerebrocortical concentration of the progesterone metabolite 3alpha-hydroxy-5alpha-pregnan-20-one (3alpha,5alpha-TH PROG) that returned to control level 48 h after discontinuation of ethanol intake. Ethanol discontinuation significantly decreased NPY immunoreactivity and concomitantly increased Y1R/LacZ transgene expression in the amygdala, whereas chronic ethanol intake failed to affect these parameters. The 5alpha-reductase inhibitor finasteride prevented both the increase in the cerebrocortical concentration of 3alpha,5alpha-TH PROG apparent after 4 weeks of ethanol intake and the changes in NPY immunoreactivity and transgene expression induced by ethanol discontinuation. Data suggest that 3alpha,5alpha-TH PROG plays an important role in the changes in NPY-Y1R signalling in the amygdala during ethanol discontinuation.
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Affiliation(s)
- Carola Eva
- Dipartimento di Anatomia, Farmacologia e Medicina Legale, Sezione di Farmacologia, Università di Torino, Torino, Italy, and Neuroscience Institute of Torino, Università di Torino, Torino, Italy.
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41
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Liang J, Suryanarayanan A, Abriam A, Snyder B, Olsen RW, Spigelman I. Mechanisms of reversible GABAA receptor plasticity after ethanol intoxication. J Neurosci 2007; 27:12367-77. [PMID: 17989301 PMCID: PMC6673253 DOI: 10.1523/jneurosci.2786-07.2007] [Citation(s) in RCA: 128] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2007] [Revised: 09/18/2007] [Accepted: 09/19/2007] [Indexed: 11/21/2022] Open
Abstract
The time-dependent effects of ethanol (EtOH) intoxication on GABA(A) receptor (GABA(A)R) composition and function were studied in rats. A cross-linking assay and Western blot analysis of microdissected CA1 area of hippocampal slices obtained 1 h after EtOH intoxication (5 g/kg, gavage), revealed decreases in the cell-surface fraction of alpha4 and delta, but not alpha1, alpha5, or gamma2 GABA(A)R subunits, without changes in their total content. This was accompanied (in CA1 neuron recordings) by decreased magnitude of the picrotoxin-sensitive tonic current (I(tonic)), but not miniature IPSCs (mIPSCs), and by reduced enhancement of I(tonic) by EtOH, but not by diazepam. By 48 h after EtOH dosing, cell-surface alpha4 (80%) and gamma2 (82%) subunit content increased, and cell-surface alpha1 (-50%) and delta (-79%) and overall content were decreased. This was paralleled by faster decay of mIPSCs, decreased diazepam enhancement of both mIPSCs and I(tonic), and paradoxically increased mIPSC responsiveness to EtOH (10-100 mm). Sensitivity to isoflurane- or diazepam-induced loss of righting reflex was decreased at 12 and 24 h after EtOH intoxication, respectively, suggesting functional GABA(A)R tolerance. The plastic GABA(A)R changes were gradually and fully reversible by 2 weeks after single EtOH dosing, but unexplainably persisted long after withdrawal from chronic intermittent ethanol treatment, which leads to signs of alcohol dependence. Our data suggest that early tolerance to EtOH may result from excessive activation and subsequent internalization of alpha4betadelta extrasynaptic GABA(A)Rs. This leads to transcriptionally regulated increases in alpha4 and gamma2 and decreases in alpha1 subunits, with preferential insertion of the newly formed alpha4betagamma2 GABA(A)Rs at synapses.
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Affiliation(s)
- Jing Liang
- Division of Oral Biology and Medicine, School of Dentistry, and
- Department of Molecular and Medical Pharmacology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California 90095
| | - Asha Suryanarayanan
- Department of Molecular and Medical Pharmacology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California 90095
| | - Alana Abriam
- Division of Oral Biology and Medicine, School of Dentistry, and
| | - Bradley Snyder
- Division of Oral Biology and Medicine, School of Dentistry, and
| | - Richard W. Olsen
- Department of Molecular and Medical Pharmacology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California 90095
| | - Igor Spigelman
- Division of Oral Biology and Medicine, School of Dentistry, and
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Beckley EH, Fretwell AM, Tanchuck MA, Gililland KR, Crabbe JC, Finn DA. Decreased anticonvulsant efficacy of allopregnanolone during ethanol withdrawal in female Withdrawal Seizure-Prone vs. Withdrawal Seizure-Resistant mice. Neuropharmacology 2007; 54:365-74. [PMID: 18045626 DOI: 10.1016/j.neuropharm.2007.10.006] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2007] [Revised: 09/11/2007] [Accepted: 10/14/2007] [Indexed: 10/22/2022]
Abstract
The GABAergic neurosteroid allopregnanolone (ALLO) has been repeatedly shown to have an increased anticonvulsant effect during ethanol withdrawal in rats and in C57BL/6J mice. In contrast, the seizure prone DBA/2J inbred strain and the Withdrawal Seizure-Prone (WSP) selected line exhibited decreased sensitivity to ALLO's anticonvulsant effect during ethanol withdrawal, with no change in sensitivity in the Withdrawal Seizure-Resistant (WSR) line. To date, only male mice have been tested. Thus, the present study examined ALLO sensitivity during ethanol withdrawal in female WSP and WSR mice, since females display less severe physical symptoms of withdrawal and have higher circulating ALLO levels than males. Female WSP and WSR mice were exposed to ethanol vapor or air for 72h. During peak ethanol withdrawal, separate groups of mice were injected with vehicle or ALLO (0, 3.2, 10, or 17mg/kg, i.p.) prior to the timed tail vein infusion of pentylenetetrazol (PTZ). ALLO injection significantly increased the threshold dose for onset to PTZ-induced convulsions, indicating an anticonvulsant effect, in female WSP and WSR mice. During ethanol withdrawal, sensitivity to ALLO's anticonvulsant effect was slightly increased in female WSR mice but was significantly decreased in female WSP mice. This line difference in sensitivity to ALLO during ethanol withdrawal in female mice was similar to that in the male mice. Notably, all seizure prone genotypes tested to date displayed tolerance to the anticonvulsant effect of ALLO during ethanol withdrawal, suggesting that decreased sensitivity of GABA(A) receptors to ALLO may contribute to the increased ethanol withdrawal phenotype.
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Affiliation(s)
- Ethan H Beckley
- Department of Behavioral Neuroscience, Oregon Health & Science University, Portland, OR, USA
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43
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Biggio G, Concas A, Follesa P, Sanna E, Serra M. Stress, ethanol, and neuroactive steroids. Pharmacol Ther 2007; 116:140-71. [PMID: 17555824 PMCID: PMC3000046 DOI: 10.1016/j.pharmthera.2007.04.005] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2007] [Accepted: 04/06/2007] [Indexed: 12/27/2022]
Abstract
Neurosteroids play a crucial role in stress, alcohol dependence and withdrawal, and other physiological and pharmacological actions by potentiating or inhibiting neurotransmitter action. This review article focuses on data showing that the interaction among stress, ethanol, and neuroactive steroids may result in plastic molecular and functional changes of GABAergic inhibitory neurotransmission. The molecular mechanisms by which stress-ethanol-neuroactive steroids interactions can produce plastic changes in GABA(A) receptors have been studied using different experimental models in vivo and in vitro in order to provide useful evidence and new insights into the mechanisms through which acute and chronic ethanol and stress exposure modulate the activity of GABAergic synapses. We show detailed data on a) the effect of acute and chronic stress on peripheral and brain neurosteroid levels and GABA(A) receptor gene expression and function; b) ethanol-stimulated brain steroidogenesis; c) plasticity of GABA(A) receptor after acute and chronic ethanol exposure. The implications of these new mechanistic insights to our understanding of the effects of ethanol during stress are also discussed. The understanding of these neurochemical and molecular mechanisms may shed new light on the physiopathology of diseases, such as anxiety, in which GABAergic transmission plays a pivotal role. These data may also lead to the need for new anxiolytic, hypnotic and anticonvulsant selective drugs devoid of side effects.
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Affiliation(s)
- Giovanni Biggio
- Department of Experimental Biology, Center of Excellence for the Neurobiology of Dependence, University of Cagliari, Cagliari, Italy.
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Gorin-Meyer RE, Wiren KM, Tanchuck MA, Long SL, Yoneyama N, Finn DA. Sex differences in the effect of finasteride on acute ethanol withdrawal severity in C57BL/6J and DBA/2J mice. Neuroscience 2007; 146:1302-15. [PMID: 17428611 PMCID: PMC1963463 DOI: 10.1016/j.neuroscience.2007.02.051] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2007] [Revised: 02/19/2007] [Accepted: 02/23/2007] [Indexed: 11/25/2022]
Abstract
The neurosteroid allopregnanolone (ALLO) is a potent positive modulator of GABAA receptors that can modulate ethanol (EtOH) withdrawal. The 5alpha-reductase inhibitor finasteride can block the formation of ALLO and other GABAergic neurosteroids and also reduce certain effects of EtOH. Treatment with finasteride during chronic EtOH exposure decreased EtOH withdrawal severity and blood EtOH concentrations (BECs), suggesting an additional effect of finasteride on EtOH pharmacokinetics. Thus, the purpose of the present study was to determine the effect of finasteride on acute EtOH withdrawal severity, to minimize the effect of finasteride on EtOH metabolism. Male and female C57BL/6J and DBA/2J mice received a pretreatment of finasteride (50 mg/kg i.p.) or vehicle 24 h prior to an injection of EtOH (4 g/kg i.p.) or saline. Handling-induced convulsions (HICs) were scored at baseline, and then over a 24 h period after EtOH or saline injection. In another experiment, plasma estradiol and corticosterone levels were assessed at selected time points (0, 2, 8, and 24 h). In a final study, retro-orbital blood samples were collected at 30, 60, 120, and 240 min post-EtOH administration to access finasteride's effects on EtOH clearance parameters. Pretreatment with finasteride increased acute EtOH withdrawal severity in female C57BL/6J and DBA/2J mice but decreased withdrawal severity in male mice of both strains. Finasteride did not alter BECs, EtOH clearance, estradiol, or corticosterone concentrations in a manner that appeared to contribute to the sex difference in finasteride's effect on acute EtOH withdrawal severity. These findings suggest that male and female C57BL/6J and DBA/2J mice differ in their sensitivity to changes in ALLO or other GABAergic neurosteroid levels during acute EtOH withdrawal. Sex differences in the modulation of GABAergic 5alpha-reduced steroids may be an important consideration in understanding and developing therapeutic interventions in alcoholics.
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Affiliation(s)
- Rebecca E. Gorin-Meyer
- Department of Behavioral Neuroscience, Oregon Health & Science University, Portland, OR 97239
| | - Kristine M. Wiren
- Portland Alcohol Research Center, Department of Veterans Affairs Medical Research, Oregon Health & Science University, Portland, OR 97239
- Department of Behavioral Neuroscience, Oregon Health & Science University, Portland, OR 97239
| | - Michelle A. Tanchuck
- Department of Behavioral Neuroscience, Oregon Health & Science University, Portland, OR 97239
| | - Season L. Long
- Department of Behavioral Neuroscience, Oregon Health & Science University, Portland, OR 97239
| | - Naomi Yoneyama
- Department of Behavioral Neuroscience, Oregon Health & Science University, Portland, OR 97239
| | - Deborah A. Finn
- Portland Alcohol Research Center, Department of Veterans Affairs Medical Research, Oregon Health & Science University, Portland, OR 97239
- Department of Behavioral Neuroscience, Oregon Health & Science University, Portland, OR 97239
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Mitrirattanakul S, López-Valdés HE, Liang J, Matsuka Y, Mackie K, Faull KF, Spigelman I. Bidirectional alterations of hippocampal cannabinoid 1 receptors and their endogenous ligands in a rat model of alcohol withdrawal and dependence. Alcohol Clin Exp Res 2007; 31:855-67. [PMID: 17386072 DOI: 10.1111/j.1530-0277.2007.00366.x] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
BACKGROUND The hippocampus is strongly implicated in memory processes and contains high concentrations of both cannabinoid receptors and their endogenous ligands. Chronic alcohol consumption impairs a variety of cognitive and performance tasks, including memory and learning. As the activation of cannabinoid receptors by their endogenous ligands modulates hippocampal neurotransmission, we hypothesized that the impaired memory and learning in alcoholism may be due to alterations in the hippocampal endocannabinoid system. METHODS We used the rat chronic intermittent ethanol (CIE) model for alcohol withdrawal and dependence which involves intermittent episodes of ethanol intoxication (60 doses) and withdrawal (approximating binge drinking episodes in humans). We measured the levels of cannabinoid 1 receptor (CB1R) protein (Western blot using a C-terminal-directed antibody), CB1R mRNA (real-time RT-PCR), CB1R localization (immunocytochemistry), tissue levels of the endocannabinoids N-arachidonoylethanolamine/anandamide (AEA) and 2-arachidonoylglycerol (2-AG), and function (patch-clamp recordings of depolarization-induced suppression of inhibition (DSI), as well as effects of CB1R agonist WIN 55,212-2 on inhibitory currents) in the hippocampus of CIE rats and their saline-treated controls. RESULTS Results were obtained in saline and CIE-treated rats after 2 and 40 days of withdrawal (DW) from their respective treatments. In 2 DW CIE rats, CB1R mRNA and protein levels were decreased by 27% (p<0.05) compared with saline controls. Surprisingly, in 40 DW CIE rats, CB1R mRNA increased by 100% and protein increased by 21%, confirmed by immunohistochemistry. Hippocampal [2-AG] increased in both 2 and 40 DW CIE rats; [AEA] increased only at 40 DW. Hippocampal DSI of CIE rats was significantly reduced at 2 DW but not at 40 DW. The CB1R agonist WIN 55,212-2 (0.5 microM) produced a significantly greater decrease in the frequency of spontaneous inhibitory currents from saline-treated rats compared with CIE rats at 2 DW, but not at 40 DW. CONCLUSIONS These data demonstrate that CIE treatment and withdrawal transiently down-regulates hippocampal CB1 Rs followed by a long-term up-regulation, including increased levels of endogenous cannabinoids. These findings are consistent with our hypothesis and suggest that long-term up-regulation of hippocampal CB1Rs may contribute to the long-term cognitive impairments in alcoholism. The data further suggest that the effectiveness of CB1R blockade in decreasing alcohol consumption may be greater after protracted abstinence from alcohol.
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Affiliation(s)
- Somsak Mitrirattanakul
- Division of Oral Biology & Medicine, School of Dentistry, University of California, Los Angeles, California 90095-1668, USA
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Follesa P, Biggio F, Talani G, Murru L, Serra M, Sanna E, Biggio G. Neurosteroids, GABAA receptors, and ethanol dependence. Psychopharmacology (Berl) 2006; 186:267-80. [PMID: 16163526 DOI: 10.1007/s00213-005-0126-0] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/20/2005] [Accepted: 06/21/2005] [Indexed: 11/26/2022]
Abstract
RATIONALE Changes in the expression of type A receptors for gamma-aminobutyric acid (GABA) represent one of the mechanisms implicated in the development of tolerance to and dependence on ethanol. The impact of such changes on the function and pharmacological sensitivity of GABAA receptors (GABAARs) has remained unclear, however. Certain behavioral and electrophysiological actions of ethanol are mediated by an increase in the concentration of neuroactive steroids in the brain that results from stimulation of the hypothalamic-pituitary-adrenal (HPA) axis. Such steroids include potent modulators of GABAAR function. OBJECTIVES We have investigated the effect of ethanol exposure and withdrawal on subunit expression and receptor function evaluated by subunit selective compounds, as well as the effects of short-term exposure to ethanol on both neurosteroid synthesis and GABAAR function, in isolated neurons and brain tissue. RESULTS Chronic treatment with and subsequent withdrawal from ethanol alter the expression of genes for specific GABAAR subunits in cultured rat neurons, and these changes are associated with alterations in receptor function and pharmacological sensitivity to neurosteroids, zaleplon, and flumazenil. Acute ethanol exposure increases the amount of 3alpha-hydroxy-5alpha-pregnan-20-one (allopregnanolone) in hippocampal slices by a local action independent of the activity of the HPA axis. This effect of ethanol was associated with an increased amplitude of GABAAR-mediated miniature inhibitory postsynaptic currents recorded from CA1 pyramidal neurons in such slices. CONCLUSIONS Chronic ethanol exposure elicits changes in the subunit composition of GABAARs, which, in turn, likely contribute to changes in receptor function associated with the altered pharmacological and behavioral sensitivity characteristic of ethanol tolerance and dependence. Ethanol may also modulate GABAAR function by increasing the de novo synthesis of neurosteroids in the brain in a manner independent of the HPA axis. This latter mechanism may play an important role in the central effects of ethanol.
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Affiliation(s)
- Paolo Follesa
- Department of Experimental Biology Bernardo Loddo, University of Cagliari, Cagliari, 09123, Italy
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Liang J, Zhang N, Cagetti E, Houser CR, Olsen RW, Spigelman I. Chronic intermittent ethanol-induced switch of ethanol actions from extrasynaptic to synaptic hippocampal GABAA receptors. J Neurosci 2006; 26:1749-58. [PMID: 16467523 PMCID: PMC6793625 DOI: 10.1523/jneurosci.4702-05.2006] [Citation(s) in RCA: 137] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Alcohol withdrawal syndrome (AWS) symptoms include hyperexcitability, anxiety, and sleep disorders. Chronic intermittent ethanol (CIE) treatment of rats with subsequent withdrawal of ethanol (EtOH) reproduced AWS symptoms in behavioral assays, which included tolerance to the sleep-inducing effect of acute EtOH and its maintained anxiolytic effect. Electrophysiological assays demonstrated a CIE-induced long-term loss of extrasynaptic GABAA receptor (GABAAR) responsiveness and a gain of synaptic GABAAR responsiveness of CA1 pyramidal and dentate granule neurons to EtOH that we were able to relate to behavioral effects. After CIE treatment, the alpha4 subunit-preferring GABAAR ligands 4,5,6,7 tetrahydroisoxazolo[5,4-c]pyridin-3-ol, La3+, and Ro15-4513 (ethyl-8-azido-5,6-dihydro-5-methyl-6-oxo-4H-imidazo[1,5alpha][1,4]benzodiazepine-3-carboxylate) exerted decreased effects on extrasynaptic currents but had increased effects on synaptic currents. Electron microscopy revealed an increase in central synaptic localization of alpha4 but not delta subunits within GABAergic synapses on the dentate granule cells of CIE rats. Recordings in dentate granule cells from delta subunit-deficient mice revealed that this subunit is not required for synaptic GABAAR sensitivity to low [EtOH]. The profound alterations in EtOH sensitivity and alpha4 subunit localization at hippocampal GABAARs of CIE rats suggest that such changes in these and other relevant brain circuits may contribute to the development of tolerance to the sleep-inducing effects and long-term dependence on alcohol.
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Olsen RW, Liang J, Cagetti E, Spigelman I. Plasticity of GABAA receptors in brains of rats treated with chronic intermittent ethanol. Neurochem Res 2006; 30:1579-88. [PMID: 16362777 DOI: 10.1007/s11064-005-8836-6] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/23/2005] [Indexed: 10/25/2022]
Abstract
The study of alcohol dependence mechanisms has been aided by work in rodents, where regimens of intermittent chronic administration with repeated episodes of intoxication and withdrawal can be coupled with controlled timing of in vitro studies and the possibility of relating them to behavior. The chronic intermittent ethanol (CIE) model in the rat has been found to be a good model of human alcohol dependence, showing persistent signs of withdrawal and self-administration. Studies in CIE rats suggest that plastic changes in GABA-mediated inhibition involving the GABAA receptor system may be responsible for the behavioral alterations. Here we summarize a combination of evidence that the alcoholic rat CIE model demonstrates changes in GABAA receptor subunit levels, in receptor localization, and in physiology and pharmacology, leading to alterations in behavior that contribute to the hyperexcitable alcohol withdrawal state (anxiety, insomnia, seizure susceptibility) and alcohol dependence.
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Affiliation(s)
- Richard W Olsen
- Department of Molecular and Medical Pharmacology, Geffen School of Medicine at UCLA, Room CHS 23-120, 650 Young Drive South, Los Angeles, CA 90095-1735, USA.
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Sheela Rani CS, Ticku MK. Comparison of chronic ethanol and chronic intermittent ethanol treatments on the expression of GABA(A) and NMDA receptor subunits. Alcohol 2006; 38:89-97. [PMID: 16839855 DOI: 10.1016/j.alcohol.2006.05.002] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2006] [Revised: 05/09/2006] [Accepted: 05/10/2006] [Indexed: 10/24/2022]
Abstract
We examined the mRNA and protein levels of GABA(A) and NMDA receptor (NMDAR) subunits in cultured mouse cortical neurons following exposure to chronic ethanol (CE) or chronic intermittent ethanol (CIE), and after 5 days of withdrawal. With respect to GABA(A) receptor mRNA, both treatments decreased the levels of alpha1 and alpha2 subunits, and increased the level of alpha4. However, only CE treatment caused parallel changes in the protein levels; alpha2 and alpha4 protein levels did not change after CIE. Both treatments did not alter beta2 and beta3 mRNA levels, but they increased beta2/3 protein levels. The gamma2 subunit mRNA levels decreased with both treatments, but protein levels did not change. Most of the changes returned to control levels after withdrawal, except for the gamma2 subunit protein, which was lower than controls. In the case of NMDAR subunit, both treatments greatly increased the levels of NR2B mRNA, but barely altered NR1 mRNA and polypeptide levels. CIE treatment caused a relatively higher increase in NR2B protein, and this was the only sustained increase after long-term withdrawal. Taken together, our results show that CIE regimen has less pronounced effects on GABA(A) receptor expression, but increases NR2B expression more dramatically than CE treatment in cultured cortical neurons. These differential effects on subunit expression may result in altered receptor structure and function as a result of ethanol exposure.
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Affiliation(s)
- C S Sheela Rani
- Department of Pharmacology, The University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, San Antonio, TX 78229-3900, USA.
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