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Vázquez-Ágredos A, Valero M, Aparicio-Mescua T, García-Rodríguez R, Gámiz F, Gallo M. Adolescent alcohol exposure modifies adult anxiety-like behavior and amygdala sensitivity to alcohol in rats: Increased c-Fos activity and sex-dependent microRNA-182 expression. Pharmacol Biochem Behav 2024; 238:173741. [PMID: 38437922 DOI: 10.1016/j.pbb.2024.173741] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/11/2023] [Revised: 02/12/2024] [Accepted: 02/29/2024] [Indexed: 03/06/2024]
Abstract
Adolescent binge alcohol drinking is a serious health concern contributing to adult alcohol abuse often associated with anxiety disorders. We have used adolescent intermittent ethanol (AIE) administration as a model of binge drinking in rats in order to explore its long-term effect on the basolateral amygdala (BLA) responsiveness to alcohol and anxiety-like behavior. AIE increased the number of BLA c-Fos positive cells in adult Wistar rats and anxiety-like behavior assessed by the open field test (OFT). Additionally, in adult female rats receiving AIE BLA over expression of miR-182 was found. Therefore, our results indicate that alcohol consumption during adolescence can lead to enduring changes in anxiety-like behavior and BLA susceptibility to alcohol that may be mediated by sex-dependent epigenetic changes. These results contribute to understanding the mechanisms involved in the development of alcohol use disorders (AUD) and anxiety-related disorders.
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Affiliation(s)
- Ana Vázquez-Ágredos
- Department of Psychobiology, Institute of Neurosciences (CIBM), University of Granada, Granada, Spain.
| | - Marta Valero
- Department of Psychology, University of Jaén, Jaén, Spain
| | - Teresa Aparicio-Mescua
- Department of Psychobiology and Centre of Investigation of Mind, Brain, and Behavior (CIMCYC), Faculty of Psychology, University of Granada, Granada, Spain
| | - Raquel García-Rodríguez
- Department of Psychobiology, Institute of Neurosciences (CIBM), University of Granada, Granada, Spain
| | - Fernando Gámiz
- Department of Psychobiology, Institute of Neurosciences (CIBM), University of Granada, Granada, Spain
| | - Milagros Gallo
- Department of Psychobiology, Institute of Neurosciences (CIBM), University of Granada, Granada, Spain; Instituto de Investigación Biosanitaria (IBS), University of Granada, Granada, Spain
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Xiao T, Roland A, Chen Y, Guffey S, Kash T, Kimbrough A. A role for circuitry of the cortical amygdala in excessive alcohol drinking, withdrawal, and alcohol use disorder. Alcohol 2024:S0741-8329(24)00034-X. [PMID: 38447789 DOI: 10.1016/j.alcohol.2024.02.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2023] [Revised: 01/30/2024] [Accepted: 02/26/2024] [Indexed: 03/08/2024]
Abstract
Alcohol use disorder (AUD) poses a significant public health challenge. Individuals with AUD engage in chronic and excessive alcohol consumption, leading to cycles of intoxication, withdrawal, and craving behaviors. This review explores the involvement of the cortical amygdala (CoA), a cortical brain region that has primarily been examined in relation to olfactory behavior, in the expression of alcohol dependence and excessive alcohol drinking. While extensive research has identified the involvement of numerous brain regions in AUD, the CoA has emerged as a relatively understudied yet promising candidate for future study. The CoA plays a vital role in rewarding and aversive signaling and olfactory-related behaviors and has recently been shown to be involved in alcohol-dependent drinking in mice. The CoA projects directly to brain regions that are critically important for AUD, such as the central amygdala, bed nucleus of the stria terminalis, and basolateral amygdala. These projections may convey key modulatory signaling that drives excessive alcohol drinking in alcohol-dependent subjects. This review summarizes existing knowledge on the structure and connectivity of the CoA and its potential involvement in AUD. Understanding the contribution of this region to excessive drinking behavior could offer novel insights into the etiology of AUD and potential therapeutic targets.
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Affiliation(s)
- Tiange Xiao
- Purdue University, Department of Basic Medical Sciences, College of Veterinary Medicine
| | - Alison Roland
- Bowles Center for Alcohol Studies, University of North Carolina School of Medicine, Chapel Hill, NC, USA; Department of Pharmacology, University of North Carolina School of Medicine, Chapel Hill, NC, USA
| | - Yueyi Chen
- Purdue University, Department of Basic Medical Sciences, College of Veterinary Medicine
| | - Skylar Guffey
- Purdue University, Department of Basic Medical Sciences, College of Veterinary Medicine
| | - Thomas Kash
- Bowles Center for Alcohol Studies, University of North Carolina School of Medicine, Chapel Hill, NC, USA; Department of Pharmacology, University of North Carolina School of Medicine, Chapel Hill, NC, USA
| | - Adam Kimbrough
- Purdue University, Department of Basic Medical Sciences, College of Veterinary Medicine; Purdue Institute for Integrative Neuroscience; Purdue University, Weldon School of Biomedical Engineering; Purdue Institute of Inflammation, Immunology, and Infectious Disease.
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3
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Braunscheidel K, Okas M, Woodward JJ. Toluene alters the intrinsic excitability and excitatory synaptic transmission of basolateral amygdala neurons. Front Neurosci 2024; 18:1366216. [PMID: 38595974 PMCID: PMC11002899 DOI: 10.3389/fnins.2024.1366216] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2024] [Accepted: 01/31/2024] [Indexed: 04/11/2024] Open
Abstract
Introduction Inhalant abuse is an important health issue especially among children and adolescents who often encounter these agents in the home. Research into the neurobiological targets of inhalants has lagged behind that of other drugs such as alcohol and psychostimulants. However, studies from our lab and others have begun to reveal how inhalants such as the organic solvent toluene affect neurons in key addiction related areas of the brain including the ventral tegmental area, nucleus accumbens and medial prefrontal cortex. In the present study, we extend these findings and examine the effect of toluene on electrophysiological responses of pyramidal neurons in the basolateral amygdala BLA, a region important for generating emotional and reward based information needed to guide future behavior. Methods Whole-cell patch-clamp electrophysiology recordings of BLA pyramidal neurons in rat brain slices were used to assess toluene effects on intrinsic excitability and excitatory glutamatergic synaptic transmission. Results Acute application of 3 mM but not 0.3 mM toluene produced a small but significant (~20%) increase in current-evoked action potential (AP) firing that reversed following washout of the toluene containing solution. The change in firing during exposure to 3 mM toluene was accompanied by selective changes in AP parameters including reduced latency to first spike, increased AP rise time and decay and a reduction in the fast after-hyperpolization. To examine whether toluene also affects excitatory synaptic signaling, we expressed channelrhodopsin-2 in medial prefrontal cortex neurons and elicited synaptic currents in BLA neurons via light pulses. Toluene (3 mM) reduced light-evoked AMPA-mediated synaptic currents while a lower concentration (0.3 mM) had no effect. The toluene-induced reduction in AMPA-mediated BLA synaptic currents was prevented by the cannabinoid receptor-1 antagonist AM281. Discussion These findings are the first to demonstrate effects of acute toluene on BLA pyramidal neurons and add to existing findings showing that abused inhalants such as toluene have significant effects on neurons in brain regions involved in natural and drug induced reward.
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Affiliation(s)
| | | | - John J. Woodward
- Department of Neuroscience, Medical University of South Carolina, Charleston, SC, United States
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Chronic Intermittent Ethanol Exposure Dysregulates Nucleus Basalis Magnocellularis Afferents in the Basolateral Amygdala. eNeuro 2022; 9:ENEURO.0164-22.2022. [PMID: 36280288 PMCID: PMC9668348 DOI: 10.1523/eneuro.0164-22.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2022] [Revised: 07/22/2022] [Accepted: 08/25/2022] [Indexed: 12/24/2022] Open
Abstract
Nucleus basalis magnocellularis (NBM) cholinergic projections to the basolateral amygdala (BLA) regulate the acquisition and consolidation of fear-like and anxiety-like behaviors. However, it is unclear whether the alterations in the NBM-BLA circuit promote negative affect during ethanol withdrawal (WD). Therefore, we performed ex vivo whole-cell patch-clamp electrophysiology in both the NBM and the BLA of male Sprague Dawley rats following 10 d of chronic intermittent ethanol (CIE) exposure and 24 h of WD. We found that CIE exposure and withdrawal enhanced the neuronal excitability of NBM putative "cholinergic" neurons. We subsequently used optogenetics to directly manipulate NBM terminal activity within the BLA and measure cholinergic modulation of glutamatergic afferents and BLA pyramidal neurons. Our findings indicate that CIE and withdrawal upregulate NBM cholinergic facilitation of glutamate release via activation of presynaptic nicotinic acetylcholine receptors (AChRs). Ethanol withdrawal-induced increases in NBM terminal activity also enhance BLA pyramidal neuron firing. Collectively, our results provide a novel characterization of the NBM-BLA circuit and suggest that CIE-dependent modifications to NBM afferents enhance BLA pyramidal neuron activity during ethanol withdrawal.
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Mineur YS, Garcia-Rivas V, Thomas MA, Soares AR, McKee SA, Picciotto MR. Sex differences in stress-induced alcohol intake: a review of preclinical studies focused on amygdala and inflammatory pathways. Psychopharmacology (Berl) 2022; 239:2041-2061. [PMID: 35359158 PMCID: PMC9704113 DOI: 10.1007/s00213-022-06120-w] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/04/2022] [Accepted: 03/14/2022] [Indexed: 02/06/2023]
Abstract
Clinical studies suggest that women are more likely than men to relapse to alcohol drinking in response to stress; however, the mechanisms underlying this sex difference are not well understood. A number of preclinical behavioral models have been used to study stress-induced alcohol intake. Here, we review paradigms used to study effects of stress on alcohol intake in rodents, focusing on findings relevant to sex differences. To date, studies of sex differences in stress-induced alcohol drinking have been somewhat limited; however, there is evidence that amygdala-centered circuits contribute to effects of stress on alcohol seeking. In addition, we present an overview of inflammatory pathways leading to microglial activation that may contribute to alcohol-dependent behaviors. We propose that sex differences in neuronal function and inflammatory signaling in circuits centered on the amygdala are involved in sex-dependent effects on stress-induced alcohol seeking and suggest that this is an important area for future studies.
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Affiliation(s)
- Yann S Mineur
- Department of Psychiatry, Yale University, 34 Park Street, 3Rd Floor Research, New Haven, CT, 06508, USA
| | - Vernon Garcia-Rivas
- Department of Psychiatry, Yale University, 34 Park Street, 3Rd Floor Research, New Haven, CT, 06508, USA
| | - Merrilee A Thomas
- Department of Psychiatry, Yale University, 34 Park Street, 3Rd Floor Research, New Haven, CT, 06508, USA
| | - Alexa R Soares
- Department of Psychiatry, Yale University, 34 Park Street, 3Rd Floor Research, New Haven, CT, 06508, USA
- Yale Interdepartmental Neuroscience Program, New Haven, CT, USA
| | - Sherry A McKee
- Department of Psychiatry, Yale University, 34 Park Street, 3Rd Floor Research, New Haven, CT, 06508, USA
| | - Marina R Picciotto
- Department of Psychiatry, Yale University, 34 Park Street, 3Rd Floor Research, New Haven, CT, 06508, USA.
- Yale Interdepartmental Neuroscience Program, New Haven, CT, USA.
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Price ME, McCool BA. Structural, functional, and behavioral significance of sex and gonadal hormones in the basolateral amygdala: A review of preclinical literature. Alcohol 2022; 98:25-41. [PMID: 34371120 DOI: 10.1016/j.alcohol.2021.08.001] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Revised: 07/12/2021] [Accepted: 08/03/2021] [Indexed: 12/16/2022]
Abstract
The basolateral amygdala (BLA) is intimately involved in the development of neuropsychiatric disorders such as anxiety and alcohol use disorder (AUD). These disorders have clear sex biases, with women more likely to develop an anxiety disorder and men more likely to develop AUD. Preclinical models have largely confirmed these sex-specific vulnerabilities and emphasize the effects of sex hormones on behaviors influenced by the BLA. This review will discuss sex differences in BLA-related behaviors and highlight potential mechanisms mediated by altered BLA structure and function, including the composition of GABAergic interneuron subpopulations, glutamatergic pyramidal neuron morphology, glutamate/GABA neurotransmission, and neuromodulators. Further, sex hormones differentially organize dimorphic circuits during sensitive developmental periods (organizational effects) and initiate more transient effects throughout adulthood (activational effects). Current literature indicates that estradiol and allopregnanolone, a neuroactive progestogen, generally reduce BLA-related behaviors through a variety of mechanisms, including activation of estrogen receptors or facilitation of GABAA-mediated inhibition, respectively. This enhanced GABAergic inhibition may protect BLA pyramidal neurons from the excitability associated with anxiety and alcohol withdrawal. Understanding sex differences and the effects of sex hormones on BLA structure and function may help explain sex-specific vulnerabilities in BLA-related behaviors and ultimately improve treatments for anxiety and AUD.
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Abstract
PURPOSE A growing body of evidence has implicated the endocannabinoid (eCB) system in the acute, chronic, and withdrawal effects of alcohol/ethanol on synaptic function. These eCB-mediated synaptic effects may contribute to the development of alcohol use disorder (AUD). Alcohol exposure causes neurobiological alterations similar to those elicited by chronic cannabinoid (CB) exposure. Like alcohol, cannabinoids alter many central processes, such as cognition, locomotion, synaptic transmission, and neurotransmitter release. There is a strong need to elucidate the effects of ethanol on the eCB system in different brain regions to understand the role of eCB signaling in AUD. SEARCH METHODS For the scope of this review, preclinical studies were identified through queries of the PubMed database. SEARCH RESULTS This search yielded 459 articles. Clinical studies and papers irrelevant to the topic of this review were excluded. DISCUSSION AND CONCLUSIONS The endocannabinoid system includes, but is not limited to, cannabinoid receptors 1 (CB1), among the most abundantly expressed neuronal receptors in the brain; cannabinoid receptors 2 (CB2); and endogenously formed CB1 ligands, including arachidonoylethanolamide (AEA; anandamide), and 2-arachidonoylglycerol (2-AG). The development of specific CB1 agonists, such as WIN 55,212-2 (WIN), and antagonists, such as SR 141716A (rimonabant), provide powerful pharmacological tools for eCB research. Alcohol exposure has brain region-specific effects on the eCB system, including altering the synthesis of endocannabinoids (e.g., AEA, 2-AG), the synthesis of their precursors, and the density and coupling efficacy of CB1. These alcohol-induced alterations of the eCB system have subsequent effects on synaptic function including neuronal excitability and postsynaptic conductance. This review will provide a comprehensive evaluation of the current literature on the synaptic interactions of alcohol exposure and eCB signaling systems, with an emphasis on molecular and physiological synaptic effects of alcohol on the eCB system. A limited volume of studies has focused on the underlying interactions of alcohol and the eCB system at the synaptic level in the brain. Thus, the data on synaptic interactions are sparse, and future research addressing these interactions is much needed.
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Affiliation(s)
- Sarah A Wolfe
- Department of Molecular Medicine, Scripps Research Institute, La Jolla, California
| | - Valentina Vozella
- Department of Molecular Medicine, Scripps Research Institute, La Jolla, California
| | - Marisa Roberto
- Department of Molecular Medicine, Scripps Research Institute, La Jolla, California
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8
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McCool BA. Ethanol modulation of cortico-basolateral amygdala circuits: Neurophysiology and behavior. Neuropharmacology 2021; 197:108750. [PMID: 34371080 DOI: 10.1016/j.neuropharm.2021.108750] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2021] [Revised: 07/22/2021] [Accepted: 08/05/2021] [Indexed: 12/19/2022]
Abstract
This review highlights literature relating the anatomy, physiology, and behavioral contributions by projections between rodent prefrontal cortical areas and the basolateral amygdala. These projections are robustly modulated by both environmental experience and exposure to drugs of abuse including ethanol. Recent literature relating optogenetic and chemogenetic dissection of these circuits within behavior both compliments and occasionally challenges roles defined by more traditional pharmacological or lesion-based approaches. In particular, cortico-amygdala circuits help control both aversive and reward-seeking. Exposure to pathology-producing environments or abused drugs dysregulates the relative 'balance' of these outcomes. Modern circuit-based approaches have also shown that overlapping populations of neurons within a given brain region frequently govern both aversion and reward-seeking. In addition, these circuits often dramatically influence 'local' cortical or basolateral amygdala excitatory or inhibitory circuits. Our understanding of these neurobiological processes, particularly in relation to ethanol research, has just begun and represents a significant opportunity.
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Affiliation(s)
- Brian A McCool
- Department of Physiology & Pharmacology, Wake Forest School of Medicine, Winston-Salem, NC, USA.
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9
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Przybysz KR, Gamble ME, Diaz MR. Moderate adolescent chronic intermittent ethanol exposure sex-dependently disrupts synaptic transmission and kappa opioid receptor function in the basolateral amygdala of adult rats. Neuropharmacology 2021; 188:108512. [PMID: 33667523 PMCID: PMC10500544 DOI: 10.1016/j.neuropharm.2021.108512] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2020] [Revised: 02/22/2021] [Accepted: 02/23/2021] [Indexed: 02/04/2023]
Abstract
Adolescent alcohol exposure is associated with many consequences in adulthood, including altered affective and reward-related behaviors. However, the long-term neurological disruptions underlying these behaviors are not fully understood. Shifts in the excitatory/inhibitory balance in the basolateral amygdala (BLA) relate to the expression of these behaviors and changes to BLA physiology are seen during withdrawal immediately following adolescent ethanol exposure, but no studies have examined whether these changes persist long-term. The kappa opioid receptor (KOR) neuromodulatory system mediates negative affective behaviors, and alterations of this system are implicated in behavioral changes following adult and adolescent chronic ethanol exposure. In the BLA, the KOR system undergoes functional changes across development, but whether BLA KOR function is disrupted by adolescent ethanol exposure is unknown. In this study, male and female Sprague-Dawley rats were exposed to a vapor model of moderate adolescent chronic intermittent ethanol (aCIE) and assessed for long-term effects on GABAergic and glutamatergic neurotransmission within the adult BLA and KOR modulation of these systems. aCIE exposure increased presynaptic glutamate transmission in females but had no effect in males or on GABA transmission in either sex. Additionally, aCIE exposure disrupted male KOR modulation of GABA release, with no effects in females or on glutamate transmission. These data suggest that aCIE produces sex-dependent and long-term changes to BLA physiology and KOR function. This is the first study to examine these persistent adaptations following adolescent alcohol exposure and opens a broad avenue for future investigation into other adolescent ethanol-induced disruptions of these systems.
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Affiliation(s)
- Kathryn R Przybysz
- Department of Psychology, Center for Development and Behavioral Neuroscience, Binghamton University, Binghamton, NY, 13902, United States; Developmental Exposure Alcohol Research Center, Binghamton University, Binghamton, NY, 13902, United States
| | - Meredith E Gamble
- Department of Psychology, Center for Development and Behavioral Neuroscience, Binghamton University, Binghamton, NY, 13902, United States; Developmental Exposure Alcohol Research Center, Binghamton University, Binghamton, NY, 13902, United States
| | - Marvin R Diaz
- Department of Psychology, Center for Development and Behavioral Neuroscience, Binghamton University, Binghamton, NY, 13902, United States; Developmental Exposure Alcohol Research Center, Binghamton University, Binghamton, NY, 13902, United States.
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Sizer SE, Parrish BC, McCool BA. Chronic Ethanol Exposure Potentiates Cholinergic Neurotransmission in the Basolateral Amygdala. Neuroscience 2020; 455:165-176. [PMID: 33385490 DOI: 10.1016/j.neuroscience.2020.12.014] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Revised: 12/10/2020] [Accepted: 12/11/2020] [Indexed: 01/10/2023]
Abstract
Chronic intermittent ethanol (CIE) exposure dysregulates glutamatergic and GABAergic neurotransmission, facilitating basolateral amygdala (BLA) pyramidal neuron hyperexcitability and the expression of anxiety during withdrawal. It is unknown whether ethanol-induced alterations in nucleus basalis magnocellularis (NBM) cholinergic projections to the BLA mediate anxiety-related behaviors through direct modulation of GABA and glutamate afferents. Following 10 days of CIE exposure and 24 h of withdrawal, we recorded GABAergic and glutamatergic synaptic responses in BLA pyramidal neurons with electrophysiology, assessed total protein expression of cholinergic markers, and quantified acetylcholine and choline concentrations using a colorimetric assay. We measured α7 nicotinic acetylcholine receptor (nAChR) dependent modulation of presynaptic function at distinct inputs in AIR- and CIE-exposed BLA coronal slices as a functional read-out of cholinergic neurotransmission. CIE/withdrawal upregulates the endogenous activity of α7 nAChRs, facilitating release at both GABAergic' local' interneuron and glutamatergic synaptic responses to stria terminalis (ST) stimulation, with no effect at GABAergic lateral paracapsular cells (LPCs). CIE caused a three-fold increase in BLA acetylcholine concentration, with no changes in α7 nAChR or cholinergic marker expression. These data illustrate that α7 nAChR-dependent changes in presynaptic function serve as a proxy for CIE-dependent alterations in synaptic acetylcholine levels. Thus, cholinergic projections appear to mediate CIE-induced alterations at GABA/glutamate inputs.
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Affiliation(s)
- Sarah E Sizer
- Department of Physiology and Pharmacology, Piedmont Triad Community Research Center (PTCRC), Wake Forest School of Medicine, 115 S Chestnut Street, Winston-Salem, NC 27101, USA.
| | - Brian C Parrish
- Department of Physiology and Pharmacology, Piedmont Triad Community Research Center (PTCRC), Wake Forest School of Medicine, 115 S Chestnut Street, Winston-Salem, NC 27101, USA.
| | - Brian A McCool
- Department of Physiology and Pharmacology, Piedmont Triad Community Research Center (PTCRC), Wake Forest School of Medicine, 115 S Chestnut Street, Winston-Salem, NC 27101, USA.
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11
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Abstract
Chronic alcohol consumption results in alcohol use disorder (AUD). Interestingly, however, sudden alcohol withdrawal (AW) after chronic alcohol exposure also leads to a devastating series of symptoms, referred to as alcohol withdrawal syndromes. One key feature of AW syndromes is to produce phenotypes that are opposite to AUD. For example, while the brain is characterized by a hypoactive state in the presence of alcohol, AW induces a hyperactive state, which is manifested as seizure expression. In this review, we discuss the idea that hippocampal neurogenesis and neural circuits play a key role in neuroadaptation and establishment of allostatic states in response to alcohol exposure and AW. The intrinsic properties of dentate granule cells (DGCs), and their contribution to the formation of a potent feedback inhibitory loop, endow the dentate gyrus with a "gate" function, which can limit the entry of excessive excitatory signals from the cortex into the hippocampus. We discuss the possibility that alcohol exposure and withdrawal disrupts structural development and circuitry integration of hippocampal newborn neurons, and that this altered neurogenesis impairs the gate function of the hippocampus. Failure of this gate function is expected to alter the ratio of excitatory to inhibitory (E/I) signals in the hippocampus and to induce seizure expression during AW. Recent functional studies have shown that specific activation and inhibition of hippocampal newborn DGCs are both necessary and sufficient for the expression of AW-associated seizures, further supporting the concept that neurogenesis-induced neuroadaptation is a critical target to understand and treat AUD and AW-associated seizures.
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Affiliation(s)
- Sreetama Basu
- Department of Neurosciences, Cleveland Clinic, Cleveland, OH, USA
| | - Hoonkyo Suh
- Department of Neurosciences, Cleveland Clinic, Cleveland, OH, USA
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12
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Klenowski PM, Fogarty MJ, Drieberg-Thompson JR, Bellingham MC, Bartlett SE. Reduced Inhibitory Inputs On Basolateral Amygdala Principal Neurons Following Long-Term Alcohol Consumption. Neuroscience 2020; 452:219-227. [PMID: 33212222 DOI: 10.1016/j.neuroscience.2020.10.039] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2020] [Revised: 10/27/2020] [Accepted: 10/28/2020] [Indexed: 12/16/2022]
Abstract
Recent studies have shown that manipulating basolateral amygdala (BLA) activity can affect alcohol consumption, particularly following chronic and/or long-term intake. Although the mechanisms underlying these effects remain unclear, the BLA is highly sensitive to emotional stimuli including stress and anxiety. Negative emotional states facilitate alcohol craving and relapse in patients with alcohol use disorders. Consequently, the aim of this study was to determine the effect of long-term (10 weeks) alcohol drinking on synaptic activity in BLA principal neurons. We utilized an intermittent drinking paradigm in rats, which facilitated escalating, binge-like alcohol intake over the 10 week drinking period. We then recorded spontaneous excitatory and inhibitory postsynaptic currents of BLA principal neurons from long-term alcohol drinking rats and aged-matched water drinking controls. Excitatory postsynaptic current properties from long-term alcohol drinking rats were unchanged compared to those from age-matched water drinking controls. Conversely, we observed significant reductions of inhibitory postsynaptic current amplitude and frequency in long-term ethanol drinking rats compared to age-matched water drinking controls. These results highlight substantive decreases in basal inhibitory synaptic activity of BLA principal neurons following long-term alcohol consumption. A loss of inhibitory control in the BLA could explain the high incidence of compulsive drinking and stress- or anxiety-induced relapse in patients with alcohol use disorders.
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Affiliation(s)
- Paul M Klenowski
- Brudnick Neuropsychiatric Research Institute, Department of Neurobiology, University of Massachusetts Medical School, Worcester, MA 01605, USA.
| | - Matthew J Fogarty
- Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, MN, USA; School of Biomedical Biosciences, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Joy R Drieberg-Thompson
- School of Biomedical Biosciences, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Mark C Bellingham
- School of Biomedical Biosciences, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Selena E Bartlett
- Translational Research Institute, Queensland University of Technology, Brisbane 4102, Australia.
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13
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McGinnis MM, Parrish BC, McCool BA. Withdrawal from chronic ethanol exposure increases postsynaptic glutamate function of insular cortex projections to the rat basolateral amygdala. Neuropharmacology 2020; 172:108129. [PMID: 32418906 DOI: 10.1016/j.neuropharm.2020.108129] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2020] [Revised: 04/09/2020] [Accepted: 05/03/2020] [Indexed: 12/28/2022]
Abstract
A key feature of alcohol use disorder (AUD) is negative affect during withdrawal, which often contributes to relapse and is thought to be caused by altered brain function, especially in circuits that are important mediators of emotional behaviors. Both the agranular insular cortex (AIC) and the basolateral amygdala (BLA) regulate emotions and are sensitive to ethanol-induced changes in synaptic plasticity. The AIC and BLA are reciprocally connected; and the effects of chronic ethanol exposure on this circuit have yet to be explored. Here, we use a combination of optogenetics and electrophysiology to examine the pre- and postsynaptic changes that occur to AIC-BLA synapses following withdrawal from 7- or 10-days of chronic intermittent ethanol (CIE) exposure. While CIE/withdrawal did not alter presynaptic glutamate release probability from AIC inputs, withdrawal from 10, but not 7, days of CIE increased AMPA receptor-mediated postsynaptic function at these synapses. Additionally, NMDA receptor-mediated currents evoked by electrical stimulation of the external capsule, which contains AIC afferents, were also increased during withdrawal. Notably, a single subanesthetic dose of ketamine administered at the onset of withdrawal prevented the withdrawal-induced increases in both AMPAR and NMDAR postsynaptic function. Ketamine also prevented the withdrawal-induced increases in anxiety-like behavior measured using the elevated zero maze. Together, these findings suggest that chronic ethanol exposure increases postsynaptic function within the AIC-BLA circuit and that ketamine can prevent ethanol withdrawal-induced alterations in synaptic plasticity and negative affect.
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Affiliation(s)
- Molly M McGinnis
- Department of Physiology and Pharmacology, Wake Forest School of Medicine, Winston-Salem, NC, 27157, USA
| | - Brian C Parrish
- Department of Physiology and Pharmacology, Wake Forest School of Medicine, Winston-Salem, NC, 27157, USA
| | - Brian A McCool
- Department of Physiology and Pharmacology, Wake Forest School of Medicine, Winston-Salem, NC, 27157, USA.
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14
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Chronic Ethanol Differentially Modulates Glutamate Release from Dorsal and Ventral Prefrontal Cortical Inputs onto Rat Basolateral Amygdala Principal Neurons. eNeuro 2020; 7:ENEURO.0132-19.2019. [PMID: 31548367 PMCID: PMC7070451 DOI: 10.1523/eneuro.0132-19.2019] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2019] [Revised: 05/12/2019] [Accepted: 08/23/2019] [Indexed: 11/25/2022] Open
Abstract
The medial prefrontal cortex (mPFC) and the basolateral amygdala (BLA) have strong reciprocal connectivity. Projections from the BLA to the mPFC can drive innate, anxiety-related behaviors, but it is unclear whether reciprocal projections from the mPFC to BLA have similar roles. Here, we use optogenetics and chemogenetics to characterize the neurophysiological and behavioral alterations produced by chronic ethanol exposure and withdrawal on dorsal mPFC (dmPFC) and ventral mPFC (vmPFC) medial prefrontal cortical terminals in the BLA. We exposed adult male Sprague Dawley rats to chronic intermittent ethanol (CIE) using vapor chambers, measured anxiety-like behavior on the elevated zero maze, and used electrophysiology to record glutamatergic and GABAergic responses in BLA principal neurons. We found that withdrawal from a 7 d CIE exposure produced opposing effects at dmPFC (increased glutamate release) and vmPFC (decreased glutamate release) terminals in the BLA. Chemogenetic inhibition of dmPFC terminals in the BLA attenuated the increased anxiety-like behavior we observed during withdrawal. These data demonstrate that chronic ethanol exposure and withdrawal strengthen the synaptic connections between the dmPFC and BLA but weakens the vmPFC–BLA pathway. Moreover, facilitation of the dmPFC–BLA pathway during withdrawal contributes to anxiety-like behavior. Given the opposing roles of dmPFC–BLA and vmPFC–BLA pathways in fear conditioning, our results suggest that chronic ethanol exposure simultaneously facilitates circuits involved in the acquisition of and diminishes circuits involved with the extinction of withdrawal-related aversive behaviors.
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Agoglia AE, Zhu M, Ying R, Sidhu H, Natividad LA, Wolfe SA, Buczynski MW, Contet C, Parsons LH, Roberto M, Herman MA. Corticotropin-Releasing Factor Receptor-1 Neurons in the Lateral Amygdala Display Selective Sensitivity to Acute and Chronic Ethanol Exposure. eNeuro 2020; 7:ENEURO.0420-19.2020. [PMID: 32041742 PMCID: PMC7059189 DOI: 10.1523/eneuro.0420-19.2020] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2019] [Revised: 01/15/2020] [Accepted: 01/28/2020] [Indexed: 12/19/2022] Open
Abstract
The lateral amygdala (LA) serves as the point of entry for sensory information within the amygdala complex, a structure that plays a critical role in emotional processes and has been implicated in alcohol use disorders. Within the amygdala, the corticotropin-releasing factor (CRF) system has been shown to mediate some of the effects of both stress and ethanol, but the effects of ethanol on specific CRF1 receptor circuits in the amygdala have not been fully established. We used male CRF1:GFP reporter mice to characterize CRF1-expressing (CRF1+) and nonexpressing (CRF1-) LA neurons and investigate the effects of acute and chronic ethanol exposure on these populations. The CRF1+ population was found to be composed predominantly of glutamatergic projection neurons with a minority subpopulation of interneurons. CRF1+ neurons exhibited a tonic conductance that was insensitive to acute ethanol. CRF1- neurons did not display a basal tonic conductance, but the application of acute ethanol induced a δ GABAA receptor subunit-dependent tonic conductance and enhanced phasic GABA release onto these cells. Chronic ethanol increased CRF1+ neuronal excitability but did not significantly alter phasic or tonic GABA signaling in either CRF1+ or CRF1- cells. Chronic ethanol and withdrawal also did not alter basal extracellular GABA or glutamate transmitter levels in the LA/BLA and did not alter the sensitivity of GABA or glutamate to acute ethanol-induced increases in transmitter release. Together, these results provide the first characterization of the CRF1+ population of LA neurons and suggest mechanisms for differential acute ethanol sensitivity within this region.
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Affiliation(s)
- Abigail E Agoglia
- Department of Pharmacology, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
- Bowles Center for Alcohol Studies, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
| | - ManHua Zhu
- Neuroscience Curriculum, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
| | - Rose Ying
- Department of Pharmacology, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
- Bowles Center for Alcohol Studies, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
| | - Harpreet Sidhu
- Department of Neuroscience, The Scripps Research Institute, La Jolla, California 92037
| | - Luis A Natividad
- University of Texas at Austin, College of Pharmacy - Division of Pharmacology and Toxicology, Austin, TX 78712
| | - Sarah A Wolfe
- Department of Neuroscience, The Scripps Research Institute, La Jolla, California 92037
| | - Matthew W Buczynski
- School of Neuroscience, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061
| | - Candice Contet
- Department of Neuroscience, The Scripps Research Institute, La Jolla, California 92037
| | - Loren H Parsons
- Department of Neuroscience, The Scripps Research Institute, La Jolla, California 92037
| | - Marisa Roberto
- Department of Neuroscience, The Scripps Research Institute, La Jolla, California 92037
| | - Melissa A Herman
- Department of Pharmacology, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
- Bowles Center for Alcohol Studies, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599
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16
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Brain-wide functional architecture remodeling by alcohol dependence and abstinence. Proc Natl Acad Sci U S A 2020; 117:2149-2159. [PMID: 31937658 DOI: 10.1073/pnas.1909915117] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Alcohol abuse and alcohol dependence are key factors in the development of alcohol use disorder, which is a pervasive societal problem with substantial economic, medical, and psychiatric consequences. Although our understanding of the neurocircuitry that underlies alcohol use has improved, novel brain regions that are involved in alcohol use and novel biomarkers of alcohol use need to be identified. The present study used a single-cell whole-brain imaging approach to 1) assess whether abstinence from alcohol in an animal model of alcohol dependence alters the functional architecture of brain activity and modularity, 2) validate our current knowledge of the neurocircuitry of alcohol abstinence, and 3) discover brain regions that may be involved in alcohol use. Alcohol abstinence resulted in the whole-brain reorganization of functional architecture in mice and a pronounced decrease in modularity that was not observed in nondependent moderate drinkers. Structuring of the alcohol abstinence network revealed three major brain modules: 1) extended amygdala module, 2) midbrain striatal module, and 3) cortico-hippocampo-thalamic module, reminiscent of the three-stage theory. Many hub brain regions that control this network were identified, including several that have been previously overlooked in alcohol research. These results identify brain targets for future research and demonstrate that alcohol use and dependence remodel brain-wide functional architecture to decrease modularity. Further studies are needed to determine whether the changes in coactivation and modularity that are associated with alcohol abstinence are causal features of alcohol dependence or a consequence of excessive drinking and alcohol exposure.
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McCool BA, McGinnis MM. Adolescent Vulnerability to Alcohol Use Disorder: Neurophysiological Mechanisms from Preclinical Studies. Handb Exp Pharmacol 2020; 258:421-442. [PMID: 31595414 DOI: 10.1007/164_2019_296] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Adolescent alcohol use in human populations dramatically increases the likelihood of adult alcohol use disorder. This adolescent vulnerability is recapitulated in preclinical models which provide important opportunities to understand basic neurobiological mechanisms. We provide here an overview of GABAergic and glutamatergic neurotransmission and our current understanding of the sensitivity of these systems to adolescent ethanol exposure. As a whole, the preclinical literature suggests that adolescent vulnerability may be directly related to region-specific neurobiological processes that continue to develop during adolescence. These processes include the activity of intrinsic circuits within diverse brain regions (primarily represented by GABAergic neurotransmission) and activity-dependent regulation of synaptic strength at glutamatergic synapses. Furthermore, GABAergic and glutamatergic neurotransmission within regions/circuits that regulate cognitive function, emotion, and their integration appears to be the most vulnerable to adolescent ethanol exposure. Finally, using documented behavioral differences between adolescents and adults with respect to acute ethanol, we highlight additional circuits and regions for future study.
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Affiliation(s)
- Brian A McCool
- Department of Physiology and Pharmacology, Wake Forest School of Medicine, Winston-Salem, NC, USA.
| | - Molly M McGinnis
- Department of Physiology and Pharmacology, Wake Forest School of Medicine, Winston-Salem, NC, USA
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Effects of Ethanol Exposure and Withdrawal on Neuronal Morphology in the Agranular Insular and Prelimbic Cortices: Relationship with Withdrawal-Related Structural Plasticity in the Nucleus Accumbens. Brain Sci 2019; 9:brainsci9080180. [PMID: 31357611 PMCID: PMC6721441 DOI: 10.3390/brainsci9080180] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2019] [Revised: 07/22/2019] [Accepted: 07/22/2019] [Indexed: 12/21/2022] Open
Abstract
The present study investigated the effects of chronic intermittent ethanol exposure and withdrawal on dendritic morphology and spine density in the agranular insular and prelimbic cortices. Adult male Sprague–Dawley rats were passively exposed to vaporized ethanol (~37 mg/L; 12 h/day) or air (control) for ten consecutive days. Dendritic length, branching, and spine density were quantified in layer II/III pyramidal neurons 24 hours or seven days following the final ethanol exposure. Compared to unexposed control animals there were structural alterations on neurons in the prelimbic cortex, and to a lesser extent the agranular insular cortex. The most prominent ethanol-related differences were the transient increases in dendritic length and branching in prelimbic neurons at 24 h post-cessation, and increased mushroom-shaped spines at seven days post-cessation. The results obtained in the prelimbic cortex are the opposite of those previously reported in the nucleus accumbens core (Peterson, et al. 2015), suggesting that these regions undergo distinct functional adaptations following ethanol exposure and withdrawal.
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Abstract
Ethanol produces intoxication through actions on numerous molecular and cellular targets. Adaptations involving these and other targets contribute to chronic drug actions that underlie continued and problematic drinking. Among the mechanisms involved in these ethanol actions are alterations in presynaptic mechanisms of synaptic transmission, including presynaptic protein function and excitation-secretion coupling. At synapses in the central nervous system (CNS), excitation-secretion coupling involves ion channel activation followed by vesicle fusion and neurotransmitter release. These mechanisms are altered by presynaptic neurotransmitter receptors and prominently by G protein-coupled receptors (GPCRs). Studies over the last 20-25 years have revealed that acute ethanol exposure alters neurotransmitter secretion, with especially robust effects on synapses that use the neurotransmitter gamma-aminobutyric acid (GABA). Intracellular signaling pathways involving second messengers such as cyclic AMP and calcium are implicated in these acute ethanol actions. Ethanol-induced release of neuropeptides and small molecule neurotransmitters that act on presynaptic GPCRs also contribute to presynaptic potentiation at synapses in the amygdala and hippocampus and inhibition of GABA release in the striatum. Prolonged exposure to ethanol alters neurotransmitter release at many CNS GABAergic and glutamatergic synapses, and changes in GPCR function are implicated in many of these neuroadaptations. These presynaptic neuroadaptations appear to involve compensation for acute drug effects at some synapses, but "allostatic" effects that result in long-term resetting of synaptic efficacy occur at others. Current investigations are determining how presynaptic neuroadaptations contribute to behavioral changes at different stages of alcohol drinking, with increasing focus on circuit adaptations underlying these behaviors. This chapter will discuss the acute and chronic presynaptic effects of ethanol in the CNS, as well as some of the consequences of these effects in amygdala and corticostriatal circuits that are related to excessive seeking/drinking and ethanol abuse.
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Affiliation(s)
- David M Lovinger
- Laboratory for Integrative Neuroscience, Division of Intramural Clinical and Biological Research, National Institute on Alcohol Abuse and Alcoholism, Bethesda, MD, USA.
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20
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Ewin SE, Morgan JW, Niere F, McMullen NP, Barth SH, Almonte AG, Raab-Graham KF, Weiner JL. Chronic Intermittent Ethanol Exposure Selectively Increases Synaptic Excitability in the Ventral Domain of the Rat Hippocampus. Neuroscience 2018; 398:144-157. [PMID: 30481568 DOI: 10.1016/j.neuroscience.2018.11.028] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2018] [Revised: 10/15/2018] [Accepted: 11/17/2018] [Indexed: 12/17/2022]
Abstract
Many studies have implicated hippocampal dysregulation in the pathophysiology of alcohol use disorder (AUD). However, over the past twenty years, a growing body of evidence has revealed distinct functional roles of the dorsal (dHC) and ventral (vHC) hippocampal subregions, with the dHC being primarily involved in spatial learning and memory and the vHC regulating anxiety- and depressive-like behaviors. Notably, to our knowledge, no rodent studies have examined the effects of chronic ethanol exposure on synaptic transmission along the dorsal/ventral axis. To that end, we examined the effects of the chronic intermittent ethanol vapor exposure (CIE) model of AUD on dHC and vHC synaptic excitability. Adult male Long-Evans rats were exposed to CIE or AIR for 10 days (12 h/day; targeting blood ethanol levels of 175-225 mg%) and recordings were made 24 h into withdrawal. As expected, this protocol increased anxiety-like behaviors on the elevated plus-maze and successive alleys test. Extracellular recordings revealed marked CIE-associated increases in synaptic excitation in the CA1 region that were exclusively restricted to the ventral domain of the hippocampus. Western blot analysis of synaptoneurosomal fractions revealed that the expression of two proteins that regulate synaptic strength, GluA2 and SK2, were dysregulated in the vHC, but not the dHC, following CIE. Together, these findings suggest that the ventral CA1 region may be particularly sensitive to the maladaptive effects of chronic ethanol exposure and provide new insight into some of the neural substrates that may contribute to the negative affective state that develops during withdrawal.
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Affiliation(s)
- Sarah E Ewin
- Department of Physiology and Pharmacology, Wake Forest School of Medicine, Winston-Salem, NC 27157, USA
| | - James W Morgan
- Department of Physiology and Pharmacology, Wake Forest School of Medicine, Winston-Salem, NC 27157, USA
| | - Farr Niere
- Department of Physiology and Pharmacology, Wake Forest School of Medicine, Winston-Salem, NC 27157, USA
| | - Nate P McMullen
- Department of Physiology and Pharmacology, Wake Forest School of Medicine, Winston-Salem, NC 27157, USA
| | - Samuel H Barth
- Department of Physiology and Pharmacology, Wake Forest School of Medicine, Winston-Salem, NC 27157, USA
| | - Antoine G Almonte
- Department of Physiology and Pharmacology, Wake Forest School of Medicine, Winston-Salem, NC 27157, USA
| | - Kimberly F Raab-Graham
- Department of Physiology and Pharmacology, Wake Forest School of Medicine, Winston-Salem, NC 27157, USA
| | - Jeffrey L Weiner
- Department of Physiology and Pharmacology, Wake Forest School of Medicine, Winston-Salem, NC 27157, USA.
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21
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The center of the emotional universe: Alcohol, stress, and CRF1 amygdala circuitry. Alcohol 2018; 72:61-73. [PMID: 30220589 DOI: 10.1016/j.alcohol.2018.03.009] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2018] [Revised: 03/15/2018] [Accepted: 03/27/2018] [Indexed: 12/15/2022]
Abstract
The commonalities between different phases of stress and alcohol use as well as the high comorbidity between alcohol use disorders (AUDs) and anxiety disorders suggest common underlying cellular mechanisms governing the rewarding and aversive aspects of these related conditions. As an integrative center that assigns emotional salience to a wide variety of internal and external stimuli, the amygdala complex plays a major role in how alcohol and stress influence cellular physiology to produce disordered behavior. Previous work has illustrated the broad role of the amygdala in alcohol, stress, and anxiety. However, the challenge of current and future studies is to identify the specific dysregulations that occur within distinct amygdala circuits and subpopulations and the commonalities between these alterations in each disorder, with the long-term goal of identifying potential targets for therapeutic intervention. Specific intra-amygdala circuits and cell type-specific subpopulations are emerging as critical targets for stress- and alcohol-induced plasticity, chief among them the corticotropin releasing factor (CRF) and CRF receptor 1 (CRF1) system. CRF and CRF1 have been implicated in the effects of alcohol in several amygdala nuclei, including the basolateral (BLA) and central amygdala (CeA); however, the precise circuitry involved in these effects and the role of these circuits in stress and anxiety are only beginning to be understood.
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22
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Oxytocin and vasopressin modulation of social anxiety following adolescent intermittent ethanol exposure. Psychopharmacology (Berl) 2018; 235:3065-3077. [PMID: 30141056 PMCID: PMC6456069 DOI: 10.1007/s00213-018-5003-8] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/13/2018] [Accepted: 08/16/2018] [Indexed: 02/08/2023]
Abstract
RATIONALE Adolescent intermittent ethanol exposure (AIE) produces lasting, sex-specific social anxiety-like alterations in male, but not female rats. Oxytocin (OXT) and vasopressin (AVP) brain systems play opposite roles in regulating social preference/avoidance, with OXT increasing approach to, and AVP increasing avoidance of social stimuli. OBJECTIVES To test the hypothesis that social anxiety-like alterations seen in adult males after AIE are associated with a shift in the balance between OXT and AVP toward AVP, effectiveness of pharmacological activation of the OXT system and blockade of endogenous activity at AVP receptors for reversing AIE-induced social anxiety-like alterations was assessed, along with examination of the effects of AIE on OXT, vasopressin V1a, and V1b receptor (OXT-R, V1a-R, and V1b-R) surface expression in the hypothalamus. METHODS Sprague-Dawley male and female rats were given 4 g/kg ethanol (AIE) or water intragastrically every 48 h for a total of 11 exposures during postnatal days (P) 25-45. On P70-72, animals were given a social interaction test following administration of a selective OXT-R agonist WAY-267464, selective V1a-R antagonist SR-49059, or V1b-R antagonist SSR-149415, and hypothalamic tissue was collected. RESULTS Social anxiety-like behavior was induced by AIE in males but not females, and was selectively reversed by the selective OXT-R agonist and V1b-R antagonist, but not V1a-R antagonist. AIE was also found to decrease OXT-R, but increase V1b-R neuronal surface expression relative to water-exposed controls in the hypothalamus of males, but not females. CONCLUSIONS These findings demonstrate that AIE induces changes in OXT-R and AVP-R surface expression in the hypothalamus along with social anxiety-like alterations in male rats. These social anxiety-like alterations can be reversed either by activation of the OXT system or by suppression of the AVP system, data that support the hypothesis that social anxiety-like alterations induced by adolescent alcohol exposure in male rats are associated at least in part with an OXT/AVP imbalance.
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23
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Lovinger DM, Abrahao KP. Synaptic plasticity mechanisms common to learning and alcohol use disorder. ACTA ACUST UNITED AC 2018; 25:425-434. [PMID: 30115764 PMCID: PMC6097767 DOI: 10.1101/lm.046722.117] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2018] [Accepted: 06/21/2018] [Indexed: 11/24/2022]
Abstract
Alcohol use disorders include drinking problems that span a range from binge drinking to alcohol abuse and dependence. Plastic changes in synaptic efficacy, such as long-term depression and long-term potentiation are widely recognized as mechanisms involved in learning and memory, responses to drugs of abuse, and addiction. In this review, we focus on the effects of chronic ethanol (EtOH) exposure on the induction of synaptic plasticity in different brain regions. We also review findings indicating that synaptic plasticity occurs in vivo during EtOH exposure, with a focus on ex vivo electrophysiological indices of plasticity. Evidence for effects of EtOH-induced or altered synaptic plasticity on learning and memory and EtOH-related behaviors is also reviewed. As this review indicates, there is much work needed to provide more information about the molecular, cellular, circuit, and behavioral consequences of EtOH interactions with synaptic plasticity mechanisms.
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Affiliation(s)
- David M Lovinger
- Laboratory for Integrative Neuroscience, Division of Intramural Clinical and Biological Research, National Institute on Alcohol Abuse and Alcoholism, Bethesda, Maryland 20892, USA
| | - Karina P Abrahao
- Laboratory for Integrative Neuroscience, Division of Intramural Clinical and Biological Research, National Institute on Alcohol Abuse and Alcoholism, Bethesda, Maryland 20892, USA
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24
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Alexander NJ, Rau AR, Jimenez VA, Daunais JB, Grant KA, McCool BA. SNARE Complex-Associated Proteins in the Lateral Amygdala of Macaca mulatta Following Long-Term Ethanol Drinking. Alcohol Clin Exp Res 2018; 42:1661-1673. [PMID: 29944190 DOI: 10.1111/acer.13821] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2018] [Accepted: 06/21/2018] [Indexed: 02/07/2023]
Abstract
BACKGROUND Recent work with long-term ethanol (EtOH) self-administration in nonhuman primate models has revealed a complex array of behavioral and physiological effects that closely mimic human alcohol abuse. Detailed neurophysiological analysis in these models suggests a myriad of pre- and postsynaptic neurobiological effects that may contribute to the behavioral manifestations of long-term EtOH drinking. The molecular mechanisms regulating presynaptic effects of this chronic EtOH exposure are largely unknown. To this end, we analyzed the effects of long-term EtOH self-administration on the levels of presynaptic SNARE complex proteins in Macaca mulatta basolateral amygdala, a brain region known to regulate both aversive and reward-seeking behaviors. METHODS Basolateral amygdala samples from control and EtOH-drinking male and female monkeys were processed. Total basolateral amygdala protein was analyzed by Western blotting using antibodies directed against both core SNARE and SNARE-associated proteins. We also performed correlational analyses between protein expression levels and a number of EtOH drinking parameters, including lifetime grams of EtOH consumed, preference, and blood alcohol concentration. RESULTS Significant interactions or main effects of sex/drinking were seen for a number of SNARE core and SNARE-associated proteins. Across the range of EtOH-drinking phenotypes, SNAP25 and Munc13-1 proteins levels were significantly different between males and females, and Munc13-2 levels were significantly lower in animals with a history of EtOH drinking. A separate analysis of very heavy-drinking individuals revealed significant decreases in Rab3c (females) and complexin 2 (males). CONCLUSIONS Protein expression analysis of basolateral amygdala total protein from controls and animals following long-term EtOH self-administration suggests a number of alterations in core SNARE or SNARE-associated components that could dramatically alter presynaptic function. A number of proteins or multiprotein components were also correlated with EtOH drinking behavior, which suggest a potentially heritable role for presynaptic SNARE proteins.
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Affiliation(s)
- Nancy J Alexander
- Department of Physiology & Pharmacology, Wake Forest School of Medicine, Winston-Salem, North Carolina
| | - Andrew R Rau
- Department of Behavioral Neuroscience, Oregon National Primate Research Center, Oregon Health Sciences University, Portland, Oregon
| | - Vanessa A Jimenez
- Department of Behavioral Neuroscience, Oregon National Primate Research Center, Oregon Health Sciences University, Portland, Oregon
| | - James B Daunais
- Department of Physiology & Pharmacology, Wake Forest School of Medicine, Winston-Salem, North Carolina
| | - Kathleen A Grant
- Department of Behavioral Neuroscience, Oregon National Primate Research Center, Oregon Health Sciences University, Portland, Oregon
| | - Brian A McCool
- Department of Physiology & Pharmacology, Wake Forest School of Medicine, Winston-Salem, North Carolina
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25
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Touchette JC, Maertens JJ, Mason MM, O'Rourke KY, Lee AM. The nicotinic receptor drug sazetidine-A reduces alcohol consumption in mice without affecting concurrent nicotine consumption. Neuropharmacology 2018; 133:63-74. [PMID: 29355641 PMCID: PMC5858984 DOI: 10.1016/j.neuropharm.2018.01.019] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2017] [Revised: 01/09/2018] [Accepted: 01/13/2018] [Indexed: 01/01/2023]
Abstract
Alcohol and nicotine addiction are frequently co-morbid. The nicotinic acetylcholine receptors (nAChRs) are critical for both alcohol and nicotine addiction mechanisms, since nAChR drugs that reduce nicotine consumption have been shown to also reduce alcohol consumption. Sazetidine-A, a pre-clinical nAChR drug with agonist and desensitizing effects at α4β2 and α7 nAChRs, has been reported to reduce alcohol consumption and nicotine self-administration in rats when administered at high doses. However, this effect has not been replicated in mice. In this study, we examined the effect of sazetidine-A on alcohol and nicotine consumption in male and female mice utilizing voluntary oral consumption procedures previously developed in our lab. We found that sazetidine-A (1 mg/kg, i.p) reduced overnight alcohol consumption, but did not affect nicotine consumption when presented either alone or concurrently with alcohol. Sazetidine-A did not reduce water or saccharin consumption at any dose tested. In a chronic co-consumption experiment in which either alcohol or nicotine was re-introduced after one week of forced abstinence, sazetidine-A attenuated post-abstinence consumption of alcohol but not nicotine. Sazetidine-A also significantly reduced alcohol consumption in an acute, binge drinking-in-the-dark procedure. Finally, we tested the effect of sazetidine-A on alcohol withdrawal, and found that sazetidine-A significantly reduced handling-induced convulsions during alcohol withdrawal. Collectively, these data suggest a novel role for the nAChR targets of sazetidine-A in specifically mediating alcohol consumption, separate from the involvement of nAChRs in mediating nicotine consumption. Delineation of this pathway may provide insight into novel therapies for the treatment of alcohol use disorders.
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Affiliation(s)
| | - Jamie J Maertens
- Department of Pharmacology, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Margaret M Mason
- Department of Pharmacology, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Kyu Y O'Rourke
- Department of Pharmacology, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Anna M Lee
- Department of Pharmacology, University of Minnesota, Minneapolis, MN, 55455, USA.
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Siciliano CA, Karkhanis AN, Holleran KM, Melchior JR, Jones SR. Cross-Species Alterations in Synaptic Dopamine Regulation After Chronic Alcohol Exposure. Handb Exp Pharmacol 2018; 248:213-238. [PMID: 29675581 PMCID: PMC6195853 DOI: 10.1007/164_2018_106] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Alcohol use disorders are a leading public health concern, engendering enormous costs in terms of both economic loss and human suffering. These disorders are characterized by compulsive and excessive alcohol use, as well as negative affect and alcohol craving during abstinence. Extensive research has implicated the dopamine system in both the acute pharmacological effects of alcohol and the symptomology of alcohol use disorders that develop after extended alcohol use. Preclinical research has shed light on many mechanisms by which chronic alcohol exposure dysregulates the dopamine system. However, many of the findings are inconsistent across experimental parameters such as alcohol exposure length, route of administration, and model organism. We propose that the dopaminergic alterations driving the core symptomology of alcohol use disorders are likely to be relatively stable across experimental settings. Recent work has been aimed at using multiple model organisms (mouse, rat, monkey) across various alcohol exposure procedures to search for commonalities. Here, we review recent advances in our understanding of the effects of chronic alcohol use on the dopamine system by highlighting findings that are consistent across experimental setting and species.
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Affiliation(s)
- Cody A Siciliano
- The Picower Institute for Learning and Memory, Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology (MIT), Cambridge, MA, USA
| | - Anushree N Karkhanis
- Department of Physiology and Pharmacology, Wake Forest School of Medicine, Winston-Salem, NC, USA
| | - Katherine M Holleran
- Department of Physiology and Pharmacology, Wake Forest School of Medicine, Winston-Salem, NC, USA
| | - James R Melchior
- Department of Physiology and Pharmacology, Wake Forest School of Medicine, Winston-Salem, NC, USA
| | - Sara R Jones
- Department of Physiology and Pharmacology, Wake Forest School of Medicine, Winston-Salem, NC, USA.
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27
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Morales M, McGinnis MM, Robinson SL, Chappell AM, McCool BA. Chronic Intermittent Ethanol Exposure Modulation of Glutamatergic Neurotransmission in Rat Lateral/Basolateral Amygdala is Duration-, Input-, and Sex-Dependent. Neuroscience 2017; 371:277-287. [PMID: 29237566 DOI: 10.1016/j.neuroscience.2017.12.005] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2017] [Revised: 11/30/2017] [Accepted: 12/04/2017] [Indexed: 01/27/2023]
Abstract
The basolateral amygdala (BLA) controls numerous behaviors, like anxiety and reward seeking, via the activity of glutamatergic principal neurons. These BLA neurons receive excitatory inputs primarily via two major anatomical pathways - the external capsule (EC), which contains afferents from lateral cortical structures, and the stria terminalis (ST), containing synapses from more midline brain structures. Chronic intermittent ethanol (CIE) exposure/withdrawal produces distinct alterations in these pathways. Specifically, 10 days of CIE (via vapor inhalation) increases presynaptic function at ST synapses and postsynaptic function at EC synapses. Given that 10-day CIE/withdrawal also increases anxiety-like behavior, we sought to examine the development of these alterations at these inputs using an exposure time-course in both male and female rats. Specifically, using 3, 7, and 10 days CIE exposure, we found that all three durations increase anxiety-like behavior in the elevated plus maze. At BLA synapses, increased presynaptic function at ST inputs required shorter exposure durations relative to post-synaptic alterations at EC inputs in both sexes. But, synaptic alterations in females required longer ethanol exposures compared to males. These data suggest that presynaptic alteration at ST-BLA afferents is an early neuroadaptation during repeated ethanol exposures. And, the similar patterns of presynaptic-then-postsynaptic facilitation across the sexes suggest the former may be required for the latter. These cooperative interactions may contribute to the increased anxiety-like behavior that is observed following CIE-induced withdrawal and may provide novel therapeutic targets to reverse withdrawal-induced anxiety.
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Affiliation(s)
- Melissa Morales
- Department of Physiology & Pharmacology, Wake Forest University School of Medicine, Winston-Salem, NC 27103, USA.
| | - Molly M McGinnis
- Department of Physiology & Pharmacology, Wake Forest University School of Medicine, Winston-Salem, NC 27103, USA
| | - Stacey L Robinson
- Department of Physiology & Pharmacology, Wake Forest University School of Medicine, Winston-Salem, NC 27103, USA
| | - Ann M Chappell
- Department of Physiology & Pharmacology, Wake Forest University School of Medicine, Winston-Salem, NC 27103, USA
| | - Brian A McCool
- Department of Physiology & Pharmacology, Wake Forest University School of Medicine, Winston-Salem, NC 27103, USA
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Moaddab M, Mangone E, Ray MH, McDannald MA. Adolescent Alcohol Drinking Renders Adult Drinking BLA-Dependent: BLA Hyper-Activity as Contributor to Comorbid Alcohol Use Disorder and Anxiety Disorders. Brain Sci 2017; 7:brainsci7110151. [PMID: 29135933 PMCID: PMC5704158 DOI: 10.3390/brainsci7110151] [Citation(s) in RCA: 9] [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: 08/30/2017] [Revised: 10/31/2017] [Accepted: 11/10/2017] [Indexed: 01/01/2023] Open
Abstract
Adolescent alcohol drinking increases the risk for alcohol-use disorder in adulthood. Yet, the changes in adult neural function resulting from adolescent alcohol drinking remain poorly understood. We hypothesized that adolescent alcohol drinking alters basolateral amygdala (BLA) function, making alcohol drinking BLA-dependent in adulthood. Male, Long Evans rats were given voluntary, intermittent access to alcohol (20% ethanol) or a bitter, isocaloric control solution, across adolescence. Half of the rats in each group received neurotoxic BLA lesions. In adulthood, all rats were given voluntary, intermittent access to alcohol. BLA lesions reduced adult alcohol drinking in rats receiving adolescent access to alcohol, but not in rats receiving adolescent access to the control solution. The effect of the BLA lesion was most apparent in high alcohol drinking adolescent rats. The BLA is essential for fear learning and is hyper-active in anxiety disorders. The results are consistent with adolescent heavy alcohol drinking inducing BLA hyper-activity, providing a neural mechanism for comorbid alcohol use disorder and anxiety disorders.
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Affiliation(s)
- Mahsa Moaddab
- Department of Psychology, Boston College, Chestnut Hill, MA 02467, USA.
| | - Elizabeth Mangone
- Department of Psychology, Boston College, Chestnut Hill, MA 02467, USA.
| | - Madelyn H Ray
- Department of Psychology, Boston College, Chestnut Hill, MA 02467, USA.
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Olsen RW, Liang J. Role of GABA A receptors in alcohol use disorders suggested by chronic intermittent ethanol (CIE) rodent model. Mol Brain 2017; 10:45. [PMID: 28931433 PMCID: PMC5605989 DOI: 10.1186/s13041-017-0325-8] [Citation(s) in RCA: 58] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2017] [Accepted: 09/05/2017] [Indexed: 11/10/2022] Open
Abstract
GABAergic inhibitory transmission is involved in the acute and chronic effects of ethanol on the brain and behavior. One-dose ethanol exposure induces transient plastic changes in GABAA receptor subunit levels, composition, and regional and subcellular localization. Rapid down-regulation of early responder δ subunit-containing GABAA receptor subtypes mediating ethanol-sensitive tonic inhibitory currents in critical neuronal circuits corresponds to rapid tolerance to ethanol's behavioral responses. Slightly slower, α1 subunit-containing GABAA receptor subtypes mediating ethanol-insensitive synaptic inhibition are down-regulated, corresponding to tolerance to additional ethanol behaviors plus cross-tolerance to other GABAergic drugs including benzodiazepines, anesthetics, and neurosteroids, especially sedative-hypnotic effects. Compensatory up-regulation of synaptically localized α4 and α2 subunit-containing GABAA receptor subtypes, mediating ethanol-sensitive synaptic inhibitory currents follow, but exhibit altered physio-pharmacology, seizure susceptibility, hyperexcitability, anxiety, and tolerance to GABAergic positive allosteric modulators, corresponding to heightened alcohol withdrawal syndrome. All these changes (behavioral, physiological, and biochemical) induced by ethanol administration are transient and return to normal in a few days. After chronic intermittent ethanol (CIE) treatment the same changes are observed but they become persistent after 30 or more doses, lasting for at least 120 days in the rat, and probably for life. We conclude that the ethanol-induced changes in GABAA receptors represent aberrant plasticity contributing critically to ethanol dependence and increased voluntary consumption. We suggest that the craving, drug-seeking, and increased consumption in the rat model are tied to ethanol-induced plastic changes in GABAA receptors, importantly the development of ethanol-sensitive synaptic GABAA receptor-mediating inhibitory currents that participate in maintained positive reward actions of ethanol on critical neuronal circuits. These probably disinhibit nerve endings of inhibitory GABAergic neurons on dopamine reward circuit cells, and limbic system circuits mediating anxiolysis in hippocampus and amygdala. We further suggest that the GABAA receptors contributing to alcohol dependence in the rat and presumably in human alcohol use disorders (AUD) are the ethanol-induced up-regulated subtypes containing α4 and most importantly α2 subunits. These mediate critical aspects of the positive reinforcement of ethanol in the dependent chronic user while alleviating heightened withdrawal symptoms experienced whenever ethanol is absent. The speculative conclusions based on firm observations are readily testable.
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Affiliation(s)
- Richard W. Olsen
- Department of Molecular and Medical Pharmacology, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095 USA
| | - Jing Liang
- Department of Molecular and Medical Pharmacology, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095 USA
- Titus Family Department of Clinical Pharmacy, School of Pharmacy, University of Southern California, Los Angeles, CA 90089 USA
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30
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Luessen DJ, Sun H, McGinnis MM, McCool BA, Chen R. Chronic intermittent ethanol exposure selectively alters the expression of Gα subunit isoforms and RGS subtypes in rat prefrontal cortex. Brain Res 2017; 1672:106-112. [PMID: 28736108 DOI: 10.1016/j.brainres.2017.07.014] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2017] [Revised: 07/17/2017] [Accepted: 07/18/2017] [Indexed: 10/19/2022]
Abstract
Chronic alcohol exposure induces pronounced changes in GPCR-mediated G-protein signaling. Recent microarray and RNA-seq analyses suggest associations between alcohol abuse and the expression of genes involved in G-protein signaling. The activity of G-proteins (e.g. Gαi/o and Gαq) is negatively modulated by regulator of G-protein signaling (RGS) proteins which are implicated in drugs of abuse including alcohol. The present study used 7days of chronic intermittent ethanol exposure followed by 24h withdrawal (CIE) to investigate changes in mRNA and protein levels of G-protein subunit isoforms and RGS protein subtypes in rat prefrontal cortex, a region associated with cognitive deficit attributed to excessive alcohol drinking. We found that this ethanol paradigm induced differential expression of Gα subunits and RGS subtypes. For example, there were increased mRNA and protein levels of Gαi1/3 subunits and no changes in the expression of Gαs and Gαq subunits in ethanol-treated animals. Moreover, CIE increased the mRNA but not the protein levels of Gαo. Additionally, a modest increase in Gαi2 mRNA level by CIE was accompanied by a pronounced increase in its protein level. Interestingly, we found that CIE increased mRNA and protein levels of RGS2, RGS4, RGS7 and RGS19 but had no effect on the expression of RGS5, RGS6, RGS8, RGS12 or RGS17. Changes in the expression of Gα subunits and RGS subtypes could contribute to the functional alterations of certain GPCRs following chronic ethanol exposure. The present study suggests that RGS proteins may be potential new targets for intervention of alcohol abuse via modification of Gα-mediated GPCR function.
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Affiliation(s)
- D J Luessen
- Department of Physiology & Pharmacology, Wake Forest School of Medicine, Winston Salem, NC 27157, USA
| | - H Sun
- Department of Physiology & Pharmacology, Wake Forest School of Medicine, Winston Salem, NC 27157, USA
| | - M M McGinnis
- Department of Physiology & Pharmacology, Wake Forest School of Medicine, Winston Salem, NC 27157, USA
| | - B A McCool
- Department of Physiology & Pharmacology, Wake Forest School of Medicine, Winston Salem, NC 27157, USA
| | - R Chen
- Department of Physiology & Pharmacology, Wake Forest School of Medicine, Winston Salem, NC 27157, USA.
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31
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Lindemeyer AK, Shen Y, Yazdani F, Shao XM, Spigelman I, Davies DL, Olsen RW, Liang J. α2 Subunit-Containing GABA A Receptor Subtypes Are Upregulated and Contribute to Alcohol-Induced Functional Plasticity in the Rat Hippocampus. Mol Pharmacol 2017; 92:101-112. [PMID: 28536106 DOI: 10.1124/mol.116.107797] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2016] [Accepted: 05/05/2017] [Indexed: 12/20/2022] Open
Abstract
Alcohol (EtOH) intoxication causes changes in the rodent brain γ-aminobutyric acid receptor (GABAAR) subunit composition and function, playing a crucial role in EtOH withdrawal symptoms and dependence. Building evidence indicates that withdrawal from acute EtOH and chronic intermittent EtOH (CIE) results in decreased EtOH-enhanced GABAAR δ subunit-containing extrasynaptic and EtOH-insensitive α1βγ2 subtype synaptic GABAARs but increased synaptic α4βγ2 subtype, and increased EtOH sensitivity of GABAAR miniature postsynaptic currents (mIPSCs) correlated with EtOH dependence. Here we demonstrate that after acute EtOH intoxication and CIE, upregulation of hippocampal α4βγ2 subtypes, as well as increased cell-surface levels of GABAAR α2 and γ1 subunits, along with increased α2β1γ1 GABAAR pentamers in hippocampal slices using cell-surface cross-linking, followed by Western blot and coimmunoprecipitation. One-dose and two-dose acute EtOH treatments produced temporal plastic changes in EtOH-induced anxiolysis or withdrawal anxiety, and the presence or absence of EtOH-sensitive synaptic currents correlated with cell surface peptide levels of both α4 and γ1(new α2) subunits. CIE increased the abundance of novel mIPSC patterns differing in activation/deactivation kinetics, charge transfer, and sensitivity to EtOH. The different mIPSC patterns in CIE could be correlated with upregulated highly EtOH-sensitive α2βγ subtypes and EtOH-sensitive α4βγ2 subtypes. Naïve α4 subunit knockout mice express EtOH-sensitive mIPSCs in hippocampal slices, correlating with upregulated GABAAR α2 (and not α4) subunits. Consistent with α2, β1, and γ1 subunits genetically linked to alcoholism in humans, our findings indicate that these new α2-containing synaptic GABAARs could mediate the maintained anxiolytic response to EtOH in dependent individuals, rat or human, contributing to elevated EtOH consumption.
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Affiliation(s)
- A Kerstin Lindemeyer
- Department of Molecular and Medical Pharmacology (A.K.L., Y.S., F.Y., R.W.O., J.L.), and Department of Neurobiology (X.M.S.), David Geffen School of Medicine at University of California at Los Angeles, and Division of Oral Biology and Medicine, School of Dentistry (I.S.), University of California and Titus Family Department of Clinical Pharmacy, University of Southern California School of Pharmacy (D.L.D., J.L.), Los Angeles, California
| | - Yi Shen
- Department of Molecular and Medical Pharmacology (A.K.L., Y.S., F.Y., R.W.O., J.L.), and Department of Neurobiology (X.M.S.), David Geffen School of Medicine at University of California at Los Angeles, and Division of Oral Biology and Medicine, School of Dentistry (I.S.), University of California and Titus Family Department of Clinical Pharmacy, University of Southern California School of Pharmacy (D.L.D., J.L.), Los Angeles, California
| | - Ferin Yazdani
- Department of Molecular and Medical Pharmacology (A.K.L., Y.S., F.Y., R.W.O., J.L.), and Department of Neurobiology (X.M.S.), David Geffen School of Medicine at University of California at Los Angeles, and Division of Oral Biology and Medicine, School of Dentistry (I.S.), University of California and Titus Family Department of Clinical Pharmacy, University of Southern California School of Pharmacy (D.L.D., J.L.), Los Angeles, California
| | - Xuesi M Shao
- Department of Molecular and Medical Pharmacology (A.K.L., Y.S., F.Y., R.W.O., J.L.), and Department of Neurobiology (X.M.S.), David Geffen School of Medicine at University of California at Los Angeles, and Division of Oral Biology and Medicine, School of Dentistry (I.S.), University of California and Titus Family Department of Clinical Pharmacy, University of Southern California School of Pharmacy (D.L.D., J.L.), Los Angeles, California
| | - Igor Spigelman
- Department of Molecular and Medical Pharmacology (A.K.L., Y.S., F.Y., R.W.O., J.L.), and Department of Neurobiology (X.M.S.), David Geffen School of Medicine at University of California at Los Angeles, and Division of Oral Biology and Medicine, School of Dentistry (I.S.), University of California and Titus Family Department of Clinical Pharmacy, University of Southern California School of Pharmacy (D.L.D., J.L.), Los Angeles, California
| | - Daryl L Davies
- Department of Molecular and Medical Pharmacology (A.K.L., Y.S., F.Y., R.W.O., J.L.), and Department of Neurobiology (X.M.S.), David Geffen School of Medicine at University of California at Los Angeles, and Division of Oral Biology and Medicine, School of Dentistry (I.S.), University of California and Titus Family Department of Clinical Pharmacy, University of Southern California School of Pharmacy (D.L.D., J.L.), Los Angeles, California
| | - Richard W Olsen
- Department of Molecular and Medical Pharmacology (A.K.L., Y.S., F.Y., R.W.O., J.L.), and Department of Neurobiology (X.M.S.), David Geffen School of Medicine at University of California at Los Angeles, and Division of Oral Biology and Medicine, School of Dentistry (I.S.), University of California and Titus Family Department of Clinical Pharmacy, University of Southern California School of Pharmacy (D.L.D., J.L.), Los Angeles, California
| | - Jing Liang
- Department of Molecular and Medical Pharmacology (A.K.L., Y.S., F.Y., R.W.O., J.L.), and Department of Neurobiology (X.M.S.), David Geffen School of Medicine at University of California at Los Angeles, and Division of Oral Biology and Medicine, School of Dentistry (I.S.), University of California and Titus Family Department of Clinical Pharmacy, University of Southern California School of Pharmacy (D.L.D., J.L.), Los Angeles, California
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Patkar OL, Belmer A, Holgate JY, Tarren JR, Shariff MR, Morgan M, Fogarty MJ, Bellingham MC, Bartlett SE, Klenowski PM. The antihypertensive drug pindolol attenuates long-term but not short-term binge-like ethanol consumption in mice. Addict Biol 2017; 22:679-691. [PMID: 27273539 DOI: 10.1111/adb.12359] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2015] [Revised: 11/03/2015] [Accepted: 12/02/2015] [Indexed: 12/15/2022]
Abstract
Alcohol dependence is a debilitating disorder with current therapies displaying limited efficacy and/or compliance. Consequently, there is a critical need for improved pharmacotherapeutic strategies to manage alcohol use disorders (AUDs). Previous studies have shown that the development of alcohol dependence involves repeated cycles of binge-like ethanol intake and abstinence. Therefore, we used a model of binge-ethanol consumption (drinking-in-the-dark) in mice to test the effects of compounds known to modify the activity of neurotransmitters implicated in alcohol addiction. From this, we have identified the FDA-approved antihypertensive drug pindolol, as a potential candidate for the management of AUDs. We show that the efficacy of pindolol to reduce ethanol consumption is enhanced following long-term (12 weeks) binge-ethanol intake, compared with short-term (4 weeks) intake. Furthermore, pindolol had no effect on locomotor activity or consumption of the natural reward sucrose. Because pindolol acts as a dual beta-adrenergic antagonist and 5-HT1A/1B partial agonist, we examined its effect on spontaneous synaptic activity in the basolateral amygdala (BLA), a brain region densely innervated by serotonin and norepinephrine-containing fibres. Pindolol increased spontaneous excitatory post-synaptic current frequency of BLA principal neurons from long-term ethanol-consuming mice but not naïve mice. Additionally, this effect was blocked by the 5-HT1A/1B receptor antagonist methiothepin, suggesting that altered serotonergic activity in the BLA may contribute to the efficacy of pindolol to reduce ethanol intake following long-term exposure. Although further mechanistic investigations are required, this study demonstrates the potential of pindolol as a new treatment option for AUDs that can be fast-tracked into human clinical studies.
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Affiliation(s)
- Omkar L. Patkar
- Translational Research Institute Queensland University of Technology Brisbane Australia
- Institute of Health and Biomedical Innovation (IHBI) Queensland University of Technology Brisbane Australia
| | - Arnauld Belmer
- Translational Research Institute Queensland University of Technology Brisbane Australia
- Institute of Health and Biomedical Innovation (IHBI) Queensland University of Technology Brisbane Australia
| | - Joan Y. Holgate
- Translational Research Institute Queensland University of Technology Brisbane Australia
- Institute of Health and Biomedical Innovation (IHBI) Queensland University of Technology Brisbane Australia
| | - Josephine R. Tarren
- Translational Research Institute Queensland University of Technology Brisbane Australia
- Institute of Health and Biomedical Innovation (IHBI) Queensland University of Technology Brisbane Australia
| | - Masroor R. Shariff
- Translational Research Institute Queensland University of Technology Brisbane Australia
- Institute of Health and Biomedical Innovation (IHBI) Queensland University of Technology Brisbane Australia
| | - Michael Morgan
- Translational Research Institute Queensland University of Technology Brisbane Australia
- Institute of Health and Biomedical Innovation (IHBI) Queensland University of Technology Brisbane Australia
| | - Matthew J. Fogarty
- School of Biomedical Sciences The University of Queensland Brisbane Australia
| | - Mark C. Bellingham
- School of Biomedical Sciences The University of Queensland Brisbane Australia
| | - Selena E. Bartlett
- Translational Research Institute Queensland University of Technology Brisbane Australia
- Institute of Health and Biomedical Innovation (IHBI) Queensland University of Technology Brisbane Australia
| | - Paul M. Klenowski
- Translational Research Institute Queensland University of Technology Brisbane Australia
- Institute of Health and Biomedical Innovation (IHBI) Queensland University of Technology Brisbane Australia
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Varodayan FP, Bajo M, Soni N, Luu G, Madamba SG, Schweitzer P, Roberto M. Chronic alcohol exposure disrupts CB 1 regulation of GABAergic transmission in the rat basolateral amygdala. Addict Biol 2017; 22:766-778. [PMID: 26786379 DOI: 10.1111/adb.12369] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2015] [Revised: 11/18/2015] [Accepted: 12/14/2015] [Indexed: 01/08/2023]
Abstract
The basolateral nucleus of the amygdala (BLA) is critical to the pathophysiology of anxiety-driven alcohol drinking and relapse. The endogenous cannabinoid/type 1 cannabinoid receptor (eCB/CB1 ) system curbs BLA-driven anxiety and stress responses via a retrograde negative feedback system that inhibits neurotransmitter release, and BLA CB1 activation reduces GABA release and drives anxiogenesis. Additionally, decreased amygdala CB1 is observed in abstinent alcoholic patients and ethanol withdrawn rats. Here, we investigated the potential disruption of eCB/CB1 signaling on GABAergic transmission in BLA pyramidal neurons of rats exposed to 2-3 weeks intermittent ethanol. In the naïve rat BLA, the CB1 agonist WIN 55,212-2 (WIN) decreased GABA release, and this effect was prevented by the CB1 antagonist AM251. AM251 alone increased GABA release via a mechanism requiring postsynaptic calcium-dependent activity. This retrograde tonic eCB/CB1 signaling was diminished in chronic ethanol exposed rats, suggesting a functional impairment of the eCB/CB1 system. In contrast, acute ethanol increased GABAergic transmission similarly in naïve and chronic ethanol exposed rats, via both presynaptic and postsynaptic mechanisms. Notably, CB1 activation impaired ethanol's facilitation of GABAergic transmission across both groups, but the AM251-induced and ethanol-induced facilitation of GABA release was additive, suggesting independent presynaptic sites of action. Collectively, the present findings highlight a critical CB1 influence on BLA GABAergic transmission that is dysregulated by chronic ethanol exposure and, thus, may contribute to the alcohol-dependent state.
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Affiliation(s)
- Florence P. Varodayan
- Committee on the Neurobiology of Addictive Disorders; The Scripps Research Institute (TSRI); La Jolla CA USA
| | - Michal Bajo
- Committee on the Neurobiology of Addictive Disorders; The Scripps Research Institute (TSRI); La Jolla CA USA
| | - Neeraj Soni
- Committee on the Neurobiology of Addictive Disorders; The Scripps Research Institute (TSRI); La Jolla CA USA
- Faculty of Health and Medical Sciences; University of Copenhagen (UCPH); Denmark
| | - George Luu
- Committee on the Neurobiology of Addictive Disorders; The Scripps Research Institute (TSRI); La Jolla CA USA
| | - Samuel G. Madamba
- Committee on the Neurobiology of Addictive Disorders; The Scripps Research Institute (TSRI); La Jolla CA USA
| | - Paul Schweitzer
- Committee on the Neurobiology of Addictive Disorders; The Scripps Research Institute (TSRI); La Jolla CA USA
| | - Marisa Roberto
- Committee on the Neurobiology of Addictive Disorders; The Scripps Research Institute (TSRI); La Jolla CA USA
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Beattie MC, Maldonado-Devincci AM, Porcu P, O'Buckley TK, Daunais JB, Grant KA, Morrow AL. Voluntary ethanol consumption reduces GABAergic neuroactive steroid (3α,5α)3-hydroxypregnan-20-one (3α,5α-THP) in the amygdala of the cynomolgus monkey. Addict Biol 2017; 22:318-330. [PMID: 26625954 DOI: 10.1111/adb.12326] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2015] [Revised: 08/31/2015] [Accepted: 10/04/2015] [Indexed: 01/27/2023]
Abstract
Neuroactive steroids such as (3α,5α)3-hydroxypregnan-20-one (3α,5α-THP, allopregnanolone) enhance the gamma-aminobutyric acid (GABA)-ergic effects of ethanol and modulate excessive drinking in rodents. Moreover, chronic ethanol consumption reduces 3α,5α-THP levels in human plasma, rat hippocampus and mouse limbic regions. We explored the relationship between 3α,5α-THP levels in limbic brain areas and voluntary ethanol consumption in the cynomolgus monkey following daily self-administration of ethanol for 12 months and further examined the relationship to hypothalamic-pituitary-adrenal (HPA) axis function prior to ethanol exposure. Monkeys were subjected to scheduled induction of ethanol consumption followed by free access to ethanol or water for 22 h/day over 12 months. Immunohistochemistry was performed using an anti-3α,5α-THP antibody. Prolonged voluntary drinking resulted in individual differences in ethanol consumption that ranged from 1.2 to 4.2 g/kg/day over 12 months. Prolonged ethanol consumption reduced cellular 3α,5α-THP immunoreactivity by 13 ± 2 percent (P < 0.05) in the lateral amygdala and 17 ± 2 percent (P < 0.05) in the basolateral amygdala. The effect of ethanol was most pronounced in heavy drinkers that consumed ≥3 g/kg ≥ 20 percent of days. Consequently, 3α,5α-THP immunoreactivity in both the lateral and basolateral amygdala was inversely correlated with average daily ethanol intake (Spearman r = -0.87 and -0.72, respectively, P < 0.05). However, no effect of ethanol and no correlation between drinking and 3α,5α-THP immunoreactivity were observed in the basomedial amygdala. 3α,5α-THP immunoreactivity following ethanol exposure was also correlated with HPA axis function prior to ethanol exposure. These data indicate that voluntary ethanol drinking reduces amygdala levels of 3α,5α-THP in non-human primates and that amygdala 3α,5α-THP levels may be linked to HPA axis function.
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Affiliation(s)
- Matthew C. Beattie
- Department of Psychiatry and Pharmacology, Bowles Center for Alcohol Studies; University of North Carolina at Chapel Hill; Chapel Hill NC USA
| | - Antoniette M. Maldonado-Devincci
- Department of Psychiatry and Pharmacology, Bowles Center for Alcohol Studies; University of North Carolina at Chapel Hill; Chapel Hill NC USA
| | - Patrizia Porcu
- Department of Psychiatry and Pharmacology, Bowles Center for Alcohol Studies; University of North Carolina at Chapel Hill; Chapel Hill NC USA
- Neuroscience Institute; National Research Council of Italy (CNR); Italy
| | - Todd K. O'Buckley
- Department of Psychiatry and Pharmacology, Bowles Center for Alcohol Studies; University of North Carolina at Chapel Hill; Chapel Hill NC USA
| | - James B. Daunais
- Department of Physiology and Pharmacology; Wake Forest School of Medicine; Winston Salem NC USA
| | - Kathleen A. Grant
- Division of Neuroscience, Oregon National Primate Research Center; Oregon Health and Science University; Beaverton OR USA
| | - A. Leslie Morrow
- Department of Psychiatry and Pharmacology, Bowles Center for Alcohol Studies; University of North Carolina at Chapel Hill; Chapel Hill NC USA
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Skelly MJ, Ariwodola OJ, Weiner JL. Fear conditioning selectively disrupts noradrenergic facilitation of GABAergic inhibition in the basolateral amygdala. Neuropharmacology 2016; 113:231-240. [PMID: 27720769 DOI: 10.1016/j.neuropharm.2016.10.003] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2016] [Revised: 09/26/2016] [Accepted: 10/03/2016] [Indexed: 10/20/2022]
Abstract
Inappropriate fear memory formation is symptomatic of many psychopathologies, and delineating the neurobiology of non-pathological fear learning may provide critical insight into treating these disorders. Fear memory formation is associated with decreased inhibitory signaling in the basolateral amygdala (BLA), and disrupted noradrenergic signaling may contribute to this decrease. BLA noradrenergic neurotransmission has been implicated in fear memory formation, and distinct adrenoreceptor (AR) subtypes modulate excitatory and inhibitory neurotransmission in this region. For example, α1-ARs promote GABA release from local inhibitory interneurons, while β3-ARs potentiate neurotransmission at lateral paracapsular (LPC) GABAergic synapses. Conversely, β1/2-ARs amplify excitatory signaling at glutamatergic synapses in the BLA. As increased BLA excitability promotes fear memory formation, we hypothesized that fear learning shifts the balanced regional effects of noradrenergic signaling toward excitation. To test this hypothesis, we used the fear-potentiated startle paradigm in combination with whole cell patch clamp electrophysiology to examine the effects of AR activation on BLA synaptic transmission following fear conditioning in male Long-Evans rats. We first demonstrated that inhibitory neurotransmission is decreased at both local and LPC synapses following fear conditioning. We next measured noradrenergic facilitation of BLA inhibitory signaling at local and LPC synapses using α1-and β3-AR agonists (1 μM A61603 and 10 μM BRL37344), and found that the ability of these agents to facilitate inhibitory neurotransmission is disrupted following fear conditioning. Conversely, we found that fear learning does not disrupt noradrenergic modulation of glutamatergic signaling via a β1/2-AR agonist (1 μM isoproterenol). Taken together, these studies suggest that fear learning increases BLA excitability by selectively disrupting the inhibitory effects of noradrenaline.
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Affiliation(s)
- M J Skelly
- Department of Physiology and Pharmacology, Wake Forest University School of Medicine, Medical Center Boulevard, Winston-Salem, NC 27157, USA
| | - O J Ariwodola
- Department of Physiology and Pharmacology, Wake Forest University School of Medicine, Medical Center Boulevard, Winston-Salem, NC 27157, USA
| | - J L Weiner
- Department of Physiology and Pharmacology, Wake Forest University School of Medicine, Medical Center Boulevard, Winston-Salem, NC 27157, USA.
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McKim TH, Shnitko TA, Robinson DL, Boettiger CA. Translational Research on Habit and Alcohol. CURRENT ADDICTION REPORTS 2016; 3:37-49. [PMID: 26925365 DOI: 10.1007/s40429-016-0089-8] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Habitual actions enable efficient daily living, but they can also contribute to pathological behaviors that resistant change, such as alcoholism. Habitual behaviors are learned actions that appear goal-directed but are in fact no longer under the control of the action's outcome. Instead, these actions are triggered by stimuli, which may be exogenous or interoceptive, discrete or contextual. A major hallmark characteristic of alcoholism is continued alcohol use despite serious negative consequences. In essence, although the outcome of alcohol seeking and drinking is dramatically devalued, these actions persist, often triggered by environmental cues associated with alcohol use. Thus, alcoholism meets the definition of an initially goal-directed behavior that converts to a habit-based process. Habit and alcohol have been well investigated in rodent models, with comparatively less research in non-human primates and people. This review focuses on translational research on habit and alcohol with an emphasis on cross-species methodology and neural circuitry.
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Affiliation(s)
- Theresa H McKim
- University of North Carolina at Chapel Hill, Department of Psychology and Neuroscience, Davie Hall, CB #3270, Chapel Hill, NC 27599
| | - Tatiana A Shnitko
- University of North Carolina at Chapel Hill, Bowles Center for Alcohol Studies, CB #7178, Chapel Hill, NC 27599
| | - Donita L Robinson
- University of North Carolina at Chapel Hill, Department of Psychiatry, Bowles Center for Alcohol Studies, CB #7178, Chapel Hill, NC 27599
| | - Charlotte A Boettiger
- Biomedical Research Imaging Center, Bowles Center for Alcohol Studies, Davie Hall, CB #3270, Chapel Hill, NC 27599
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Acute and chronic ethanol exposure differentially regulate CB1 receptor function at glutamatergic synapses in the rat basolateral amygdala. Neuropharmacology 2015; 108:474-84. [PMID: 26707595 DOI: 10.1016/j.neuropharm.2015.12.005] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2015] [Revised: 11/02/2015] [Accepted: 12/08/2015] [Indexed: 01/03/2023]
Abstract
The endogenous cannabinoid (eCB) system has been suggested to play a key role in ethanol preference and intake, the acute effects of ethanol, and in the development of withdrawal symptoms following ethanol dependence. Ethanol-dependent alterations in glutamatergic signaling within the lateral/basolateral nucleus of the amygdala (BLA) are critical for the development and expression of withdrawal-induced anxiety. Notably, the eCB system significantly regulates both glutamatergic and GABAergic synaptic activity within the BLA. Chronic ethanol exposure significantly alters eCB system expression within regions critical to the expression of emotionality and anxiety-related behavior, including the BLA. Here, we investigated specific interactions between the BLA eCB system and its functional regulation of synaptic activity during acute and chronic ethanol exposure. In tissue from ethanol naïve-rats, a prolonged acute ethanol exposure caused a dose dependent inhibition of glutamatergic synaptic activity via a presynaptic mechanism that was occluded by CB1 antagonist/inverse agonists SR141716a and AM251. Importantly, this acute ethanol inhibition was attenuated following 10 day chronic intermittent ethanol vapor exposure (CIE). CIE exposure also significantly down-regulated CB1-mediated presynaptic inhibition at glutamatergic afferent terminals but spared CB1-inhibition of GABAergic synapses arising from local inhibitory-interneurons. CIE also significantly elevated BLA N-arachidonoylethanolamine (AEA or anandamide) levels and decreased CB1 receptor protein levels. Collectively, these data suggest a dynamic regulation of the BLA eCB system by acute and chronic ethanol.
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Interactions between ethanol and the endocannabinoid system at GABAergic synapses on basolateral amygdala principal neurons. Alcohol 2015; 49:781-94. [PMID: 26603632 DOI: 10.1016/j.alcohol.2015.08.006] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2015] [Revised: 08/11/2015] [Accepted: 08/25/2015] [Indexed: 12/30/2022]
Abstract
The basolateral amygdala (BLA) plays crucial roles in stimulus value coding, as well as drug and alcohol dependence. Ethanol alters synaptic transmission in the BLA, while endocannabinoids (eCBs) produce presynaptic depression at BLA synapses. Recent studies suggest interactions between ethanol and eCBs that have important consequences for alcohol drinking behavior. To determine how ethanol and eCBs interact in the BLA, we examined the physiology and pharmacology of GABAergic synapses onto BLA pyramidal neurons in neurons from young rats. Application of ethanol at concentrations relevant to intoxication increased, in both young and adult animals, the frequency of spontaneous and miniature GABAergic inhibitory postsynaptic currents, indicating a presynaptic site of ethanol action. Ethanol did not potentiate sIPSCs during inhibition of adenylyl cyclase while still exerting its effect during inhibition of protein kinase A. Activation of type 1 cannabinoid receptors (CB1) in the BLA inhibited GABAergic transmission via an apparent presynaptic mechanism, and prevented ethanol potentiation. Surprisingly, ethanol potentiation was also prevented by CB1 antagonists/inverse agonists. Brief depolarization of BLA pyramidal neurons suppressed GABAergic transmission (depolarization-induced suppression of inhibition [DSI]), an effect previously shown to be mediated by postsynaptic eCB release and presynaptic CB1 activation. A CB1-mediated suppression of GABAergic transmission was also produced by combined afferent stimulation at 0.1 Hz (LFS), and postsynaptic loading with the eCB arachidonoyl ethanolamide (AEA). Both DSI and LFS-induced synaptic depression were prevented by ethanol. Our findings indicate antagonistic interactions between ethanol and eCB/CB1 modulation at GABAergic BLA synapses that may contribute to eCB roles in ethanol seeking and drinking.
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Ortiz V, Giachero M, Espejo PJ, Molina VA, Martijena ID. The effect of Midazolam and Propranolol on fear memory reconsolidation in ethanol-withdrawn rats: influence of d-cycloserine. Int J Neuropsychopharmacol 2015; 18:pyu082. [PMID: 25617327 PMCID: PMC4360226 DOI: 10.1093/ijnp/pyu082] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
BACKGROUND Withdrawal from chronic ethanol facilitates the formation of contextual fear memory and delays the onset to extinction, with its retrieval promoting an increase in ethanol consumption. Consequently, manipulations aimed to reduce these aversive memories, may be beneficial in the treatment of alcohol discontinuation symptoms. Related to this, pharmacological memory reconsolidation blockade has received greater attention due to its therapeutic potential. METHODS Here, we examined the effect of post-reactivation amnestic treatments such as Midazolam (MDZ, 3 mg/kg i.p) and Propranolol (PROP, 5 mg/kg i.p) on contextual fear memory reconsolidation in ethanol- withdrawn (ETOH) rats. Next, we examined whether the activation of N-methyl-D-aspartate (NMDA) receptors induced by d-cycloserine (DCS, 5 mg/kg i.p., a NMDA partial agonist) before memory reactivation can facilitate the disruptive effect of PROP and MDZ on fear memory in ETOH rats. RESULTS We observed a resistance to the disruptive effect of both MDZ and PROP following memory reactivation. Although intra-basolateral amygdala (BLA; 1.25 ug/side) and systemic PROP administration attenuated fear memory in DCS pre-treated ETOH rats, DCS/MDZ treatment did not affect memory in these animals. Finally, a decrease of both total and surface protein expression of the α1 GABAA receptor (GABAA-R) subunit in BLA was found in the ETOH rats. CONCLUSIONS Ethanol withdrawal facilitated the formation of fear memory resistant to labilization post-reactivation. DCS administration promoted the disruptive effect of PROP on memory reconsolidation in ETOH rats. The resistance to MDZ's disruptive effect on fear memory reconsolidation may be, at least in part, associated with changes in the GABAA-R composition induced by chronic ethanol administration/withdrawal.
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Affiliation(s)
| | | | | | | | - Irene Delia Martijena
- IFEC-CONICET, Departamento de Farmacología, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Córdoba, Argentina (Ms Ortiz, Dr Giachero, Mr Espejo, PharmD, Drs Molina and Martijena)
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Peterson VL, McCool BA, Hamilton DA. Effects of ethanol exposure and withdrawal on dendritic morphology and spine density in the nucleus accumbens core and shell. Brain Res 2014; 1594:125-35. [PMID: 25452024 DOI: 10.1016/j.brainres.2014.10.036] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2014] [Revised: 10/15/2014] [Accepted: 10/18/2014] [Indexed: 12/24/2022]
Abstract
Exposure to drugs of abuse can result in profound structural modifications on neurons in circuits involved in addiction that may contribute to drug dependence, withdrawal and related processes. Structural alterations on medium spiny neurons (MSNs) of the nucleus accumbens (NAc) have been observed following exposure to and withdrawal from a variety of drugs; however, relatively little is known about the effects of alcohol exposure and withdrawal on structural alterations of NAc MSNs. In the present study male rats were chronically exposed to vaporized ethanol for 10 days and underwent 1 or 7 days of withdrawal after which the brains were processed for Golgi-Cox staining and analysis of dendritic length, branching and spine density. MSNs of the NAc shell and core underwent different patterns of changes following ethanol exposure and withdrawal. At 1 day of withdrawal there were modest reductions in the dendritic length and branching of MSNs in both the core and the shell compared to control animals exposed only to air. At 7 days of withdrawal the length and branching of shell MSNs was reduced, whereas the length and branching of core MSNs were increased relative to the shell. The density of mature spines was increased in the core at 1 day of withdrawal, whereas the density of less mature spines was increased in both regions at 7 days of withdrawal. Collectively, these observations indicate that MSNs of the NAc core and shell undergo distinct patterns of structural modifications following ethanol exposure and withdrawal suggesting that modifications in dendritic structure in these regions may contribute differentially to ethanol withdrawal.
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Affiliation(s)
- Veronica L Peterson
- Department of Psychology, University of New Mexico, Albuquerque, NM 87131, USA
| | - Brian A McCool
- Department of Physiology and Pharmacology, Wake Forest School of Medicine, Winston-Salem, NC 27157, USA
| | - Derek A Hamilton
- Department of Psychology, University of New Mexico, Albuquerque, NM 87131, USA; Department of Neurosciences, University of New Mexico, Albuquerque, NM 87131, USA.
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Lindemeyer AK, Liang J, Marty VN, Meyer EM, Suryanarayanan A, Olsen RW, Spigelman I. Ethanol-induced plasticity of GABAA receptors in the basolateral amygdala. Neurochem Res 2014; 39:1162-70. [PMID: 24710789 PMCID: PMC4121120 DOI: 10.1007/s11064-014-1297-z] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2013] [Revised: 03/24/2014] [Accepted: 03/26/2014] [Indexed: 12/25/2022]
Abstract
Acute and chronic ethanol (EtOH) administration is known to affect function, surface expression, and subunit composition of γ-aminobutyric acid (A) receptors (GABAARs) in different parts of the brain, which is believed to play a major role in alcohol dependence and withdrawal symptoms. The basolateral amygdala (BLA) participates in anxiety-like behaviors including those induced by alcohol withdrawal. In the present study we assessed the changes in cell surface levels of select GABAAR subunits in the BLA of a rat model of alcohol dependence induced by chronic intermittent EtOH (CIE) treatment and long-term (>40 days) withdrawal and investigated the time-course of such changes after a single dose of EtOH (5 g/kg, gavage). We found an early decrease in surface expression of α4 and δ subunits at 1 h following single dose EtOH treatment. At 48 h post-EtOH and after CIE treatment there was an increase in α4 and γ2, while α1, α2, and δ surface expression were decreased. To relate functional changes in GABAARs to changes in their subunit composition we analyzed miniature inhibitory postsynaptic currents (mIPSCs) and the picrotoxin-sensitive tonic current (Itonic) 48 h after EtOH intoxication. The Itonic magnitude and most of the mIPSC kinetic parameters (except faster mIPSC decay) were unchanged at 48 h post-EtOH. At the same time, Itonic potentiation by acute EtOH was greatly reduced, whereas mIPSCs became significantly more sensitive to potentiation by acute EtOH. These results suggest that EtOH intoxication-induced GABAAR plasticity in the BLA might contribute to the diminished sedative/hypnotic and maintained anxiolytic effectiveness of EtOH.
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Affiliation(s)
- A. Kerstin Lindemeyer
- Department of Molecular and Medical Pharmacology, David Geffen School of Medicine, University of California, Los Angeles, CA, USA
| | - Jing Liang
- Department of Molecular and Medical Pharmacology, David Geffen School of Medicine, University of California, Los Angeles, CA, USA; Division of Oral Biology and Medicine, School of Dentistry, University of California, 10833 Le Conte Avenue, 63-078 CHS, Los Angeles, CA 90095-1668, USA
| | - Vincent N. Marty
- Division of Oral Biology and Medicine, School of Dentistry, University of California, 10833 Le Conte Avenue, 63-078 CHS, Los Angeles, CA 90095-1668, USA
| | - Edward M. Meyer
- Division of Oral Biology and Medicine, School of Dentistry, University of California, 10833 Le Conte Avenue, 63-078 CHS, Los Angeles, CA 90095-1668, USA
| | - Asha Suryanarayanan
- Department of Molecular and Medical Pharmacology, David Geffen School of Medicine, University of California, Los Angeles, CA, USA; Division of Oral Biology and Medicine, School of Dentistry, University of California, 10833 Le Conte Avenue, 63-078 CHS, Los Angeles, CA 90095-1668, USA
| | - Richard W. Olsen
- Department of Molecular and Medical Pharmacology, David Geffen School of Medicine, University of California, Los Angeles, CA, USA
| | - Igor Spigelman
- Division of Oral Biology and Medicine, School of Dentistry, University of California, 10833 Le Conte Avenue, 63-078 CHS, Los Angeles, CA 90095-1668, USA
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Trudell JR, Messing RO, Mayfield J, Harris RA. Alcohol dependence: molecular and behavioral evidence. Trends Pharmacol Sci 2014; 35:317-23. [PMID: 24865944 DOI: 10.1016/j.tips.2014.04.009] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2014] [Revised: 04/18/2014] [Accepted: 04/30/2014] [Indexed: 10/25/2022]
Abstract
Alcohol dependence is a complex condition with clear genetic factors. Some of the leading candidate genes code for subunits of the inhibitory GABAA and glycine receptors. These and related ion channels are also targets for the acute actions of alcohol, and there is considerable progress in understanding interactions of alcohol with these proteins at the molecular and even atomic levels. X-ray structures of open and closed states of ion channels combined with structural modeling and site-directed mutagenesis have elucidated direct actions of alcohol. Alcohol also alters channel function by translational and post-translational mechanisms, including phosphorylation and protein trafficking. Construction of mutant mice with either deletion of key proteins or introduction of alcohol-resistant channels has further linked specific proteins with discrete behavioral effects of alcohol. A combination of approaches, including genome wide association studies in humans, continues to advance the molecular basis of alcohol action on receptor structure and function.
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Affiliation(s)
- James R Trudell
- Department of Anesthesia, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Robert O Messing
- Waggoner Center for Alcohol and Addiction Research, The University of Texas at Austin, Austin, TX 78712, USA
| | - Jody Mayfield
- Waggoner Center for Alcohol and Addiction Research, The University of Texas at Austin, Austin, TX 78712, USA
| | - R Adron Harris
- Waggoner Center for Alcohol and Addiction Research, The University of Texas at Austin, Austin, TX 78712, USA.
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Liang J, Lindemeyer AK, Suryanarayanan A, Meyer EM, Marty VN, Ahmad SO, Shao XM, Olsen RW, Spigelman I. Plasticity of GABA(A) receptor-mediated neurotransmission in the nucleus accumbens of alcohol-dependent rats. J Neurophysiol 2014; 112:39-50. [PMID: 24694935 DOI: 10.1152/jn.00565.2013] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Chronic alcohol exposure-induced changes in reinforcement mechanisms and motivational state are thought to contribute to the development of cravings and relapse during protracted withdrawal. The nucleus accumbens (NAcc) is a key structure of the mesolimbic dopaminergic reward system and plays an important role in mediating alcohol-seeking behaviors. Here we describe the long-lasting alterations of γ-aminobutyric acid type A receptors (GABA(A)Rs) of medium spiny neurons (MSNs) in the NAcc after chronic intermittent ethanol (CIE) treatment, a rat model of alcohol dependence. CIE treatment and withdrawal (>40 days) produced decreases in the ethanol and Ro15-4513 potentiation of extrasynaptic GABA(A)Rs, which mediate the picrotoxin-sensitive tonic current (I(tonic)), while potentiation of synaptic receptors, which give rise to miniature inhibitory postsynaptic currents (mIPSCs), was increased. Diazepam sensitivity of both I(tonic) and mIPSCs was decreased by CIE treatment. The average magnitude of I(tonic) was unchanged, but mIPSC amplitude and frequency decreased and mIPSC rise time increased after CIE treatment. Rise-time histograms revealed decreased frequency of fast-rising mIPSCs after CIE treatment, consistent with possible decreases in somatic GABAergic synapses in MSNs from CIE rats. However, unbiased stereological analysis of NeuN-stained NAcc neurons did not detect any decreases in NAcc volume, neuronal numbers, or neuronal cell body volume. Western blot analysis of surface subunit levels revealed selective decreases in α1 and δ and increases in α4, α5, and γ2 GABA(A)R subunits after CIE treatment and withdrawal. Similar, but reversible, alterations occurred after a single ethanol dose (5 g/kg). These data reveal CIE-induced long-lasting neuroadaptations in the NAcc GABAergic neurotransmission.
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Affiliation(s)
- Jing Liang
- Division of Oral Biology and Medicine, School of Dentistry, University of California, Los Angeles, California; Department of Molecular and Medical Pharmacology, David Geffen School of Medicine, University of California, Los Angeles, California
| | - A Kerstin Lindemeyer
- Department of Molecular and Medical Pharmacology, David Geffen School of Medicine, University of California, Los Angeles, California
| | - Asha Suryanarayanan
- Division of Oral Biology and Medicine, School of Dentistry, University of California, Los Angeles, California
| | - Edward M Meyer
- Division of Oral Biology and Medicine, School of Dentistry, University of California, Los Angeles, California
| | - Vincent N Marty
- Division of Oral Biology and Medicine, School of Dentistry, University of California, Los Angeles, California
| | - S Omar Ahmad
- Doisy College of Health Sciences, Saint Louis University, St. Louis, Missouri; and
| | - Xuesi Max Shao
- Department of Neurobiology, David Geffen School of Medicine, University of California, Los Angeles, California
| | - Richard W Olsen
- Department of Molecular and Medical Pharmacology, David Geffen School of Medicine, University of California, Los Angeles, California
| | - Igor Spigelman
- Division of Oral Biology and Medicine, School of Dentistry, University of California, Los Angeles, California;
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McCool BA, Christian DT, Fetzer JA, Chappell AM. Lateral/basolateral amygdala serotonin type-2 receptors modulate operant self-administration of a sweetened ethanol solution via inhibition of principal neuron activity. Front Integr Neurosci 2014; 8:5. [PMID: 24523680 PMCID: PMC3906593 DOI: 10.3389/fnint.2014.00005] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2013] [Accepted: 01/09/2014] [Indexed: 11/13/2022] Open
Abstract
The lateral/basolateral amygdala (BLA) forms an integral part of the neural circuitry controlling innate anxiety and learned fear. More recently, BLA dependent modulation of self-administration behaviors suggests a much broader role in the regulation of reward evaluation. To test this, we employed a self-administration paradigm that procedurally segregates “seeking” (exemplified as lever-press behaviors) from consumption (drinking) directed at a sweetened ethanol solution. Microinjection of the nonselective serotonin type-2 receptor agonist, alpha-methyl-5-hydroxytryptamine (α-m5HT) into the BLA reduced lever pressing behaviors in a dose-dependent fashion. This was associated with a significant reduction in the number of response-bouts expressed during non-reinforced sessions without altering the size of a bout or the rate of responding. Conversely, intra-BLA α-m5HT only modestly effected consumption-related behaviors; the highest dose reduced the total time spent consuming a sweetened ethanol solution but did not inhibit the total number of licks, number of lick bouts, or amount of solution consumed during a session. In vitro neurophysiological characterization of BLA synaptic responses showed that α-m5HT significantly reduced extracellular field potentials. This was blocked by the 5-HT2A/C antagonist ketanserin suggesting that 5-HT2-like receptors mediate the behavioral effect of α-m5HT. During whole-cell patch current-clamp recordings, we subsequently found that α-m5HT increased action potential threshold and hyperpolarized the resting membrane potential of BLA pyramidal neurons. Together, our findings show that the activation of BLA 5-HT2A/C receptors inhibits behaviors related to reward-seeking by suppressing BLA principal neuron activity. These data are consistent with the hypothesis that the BLA modulates reward-related behaviors and provides specific insight into BLA contributions during operant self-administration of a sweetened ethanol solution.
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Affiliation(s)
- Brian A McCool
- Department of Physiology and Pharmacology, Wake Forest School of Medicine, Winston-Salem NC, USA
| | - Daniel T Christian
- Department of Physiology and Pharmacology, Wake Forest School of Medicine, Winston-Salem NC, USA
| | - Jonathan A Fetzer
- Department of Physiology and Pharmacology, Wake Forest School of Medicine, Winston-Salem NC, USA
| | - Ann M Chappell
- Department of Physiology and Pharmacology, Wake Forest School of Medicine, Winston-Salem NC, USA
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Abstract
This chapter provides an overview of current knowledge on the molecular and clinical aspects of chronic alcohol effects on the central nervous system. This drug is almost ubiquitous, widely enjoyed socially, but produces a diverse spectrum of neurologic disease when abused. Acutely, alcohol interacts predominantly with γ-aminobutyric acid-A (GABA-A) and N-methyl-d-aspartate (NMDA) receptors, but triggers diverse signaling events within well-defined neural pathways. These events result in adaptive changes in gene expression that ultimately produce two major states: addiction and toxicity. Epigenetic modifications of chromatin could lead to long-lived or even transgenerational changes in gene expression, thus producing aspects of the heritability of alcohol use disorders (AUD) and long-term behaviors such as recidivism. The diverse clinical syndromes produced by chronic alcohol actions in the central nervous system reflect the molecular pathology and predominantly involve aspects of tolerance/withdrawal, selective vulnerability (manifest as central pontine myelinolysis, Marchiafava-Bignami disease), and additional environmental factors (e.g., thiamine deficiency in Wernicke-Korsakoff's syndrome). Additionally, deleterious aspects of chronic alcohol on signaling, synaptic transmission, and cell toxicity lead to primary alcoholic dementia. Genetically determined aspects of myelin structure and alcohol actions on myelin gene expression may be a prominent molecular mechanism resulting in a predisposition to, or causation of, AUD and multiple other neurologic complications of chronic alcohol. The dramatic progress made in understanding molecular actions of alcohol holds great promise for our eventual treatment or prevention of AUD and neurologic complications resulting from chronic alcohol abuse.
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Affiliation(s)
- B N Costin
- Virginia Commonwealth University Alcohol Research Center and Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, VA, USA
| | - M F Miles
- Virginia Commonwealth University Alcohol Research Center, Department of Pharmacology and Toxicology, Center for Study of Biological Complexity and Department of Neurology, Virginia Commonwealth University, Richmond, VA, USA.
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46
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Carvajal F, Sanchez-Amate MDC, Lerma-Cabrera JM, Cubero I. Effects of a single high dose of Chlorpyrifos in long-term feeding, ethanol consumption and ethanol preference in male Wistar rats with a previous history of continued ethanol drinking. J Toxicol Sci 2014; 39:425-35. [DOI: 10.2131/jts.39.425] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Affiliation(s)
- Francisca Carvajal
- Department of Psychology, Universidad Autónoma de Chile
- Department of Psychology, Universidad de Almería
| | | | - José Manuel Lerma-Cabrera
- Department of Psychology, Universidad Autónoma de Chile
- Department of Psychology, Universidad de Almería
| | - Inmaculada Cubero
- Department of Psychology, Universidad Autónoma de Chile
- Department of Psychology, Universidad de Almería
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Locomotor sensitization to ethanol impairs NMDA receptor-dependent synaptic plasticity in the nucleus accumbens and increases ethanol self-administration. J Neurosci 2013; 33:4834-42. [PMID: 23486954 DOI: 10.1523/jneurosci.5839-11.2013] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Although alcoholism is a worldwide problem resulting in millions of deaths, only a small percentage of alcohol users become addicted. The specific neural substrates responsible for individual differences in vulnerability to alcohol addiction are not known. In this study, we used rodent models to study behavioral and synaptic correlates related to individual differences in the development of ethanol locomotor sensitization, a form of drug-dependent behavioral plasticity associated with addiction vulnerability. Male Swiss Webster mice were treated daily with saline or 1.8 g/kg ethanol for 21 d. Locomotor activity tests were performed once a week for 15 min immediately after saline or ethanol injections. After at least 11 d of withdrawal, cohorts of saline- or ethanol-treated mice were used to characterize the relationships between locomotor sensitization, ethanol drinking, and glutamatergic synaptic transmission in the nucleus accumbens. Ethanol-treated mice that expressed locomotor sensitization to ethanol drank significantly more ethanol than saline-treated subjects and ethanol-treated animals resilient to this form of behavioral plasticity. Moreover, ethanol-sensitized mice also had reduced accumbal NMDA receptor function and expression, as well as deficits in NMDA receptor-dependent long-term depression in the nucleus accumbens core after a protracted withdrawal. These findings suggest that disruption of accumbal core NMDA receptor-dependent plasticity may represent a synaptic correlate associated with ethanol-induced locomotor sensitization and increased propensity to consume ethanol.
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48
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Silberman Y, Ariwodola OJ, Weiner JL. β1-adrenoceptor activation is required for ethanol enhancement of lateral paracapsular GABAergic synapses in the rat basolateral amygdala. J Pharmacol Exp Ther 2012; 343:451-9. [PMID: 22904357 DOI: 10.1124/jpet.112.196022] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Ethanol (EtOH) potentiation of GABAergic neurotransmission in the basolateral amygdala (BLA) may contribute to the acute anxiolytic effects of this drug. Previous studies have shown that BLA pyramidal neurons receive GABAergic input from two distinct sources: local interneurons and a cluster of GABAergic cells termed lateral paracapsular (LPCS) interneurons. It is noteworthy that whereas EtOH enhances local GABAergic synapses via a presynaptic increase in GABA release, EtOH potentiation of LPCS inhibition is mediated via a distinct mechanism that requires adrenoceptor (AR) activation. Here, we sought to further characterize the interaction between the AR system and EtOH enhancement of LPCS GABAergic synapses by using in vitro electrophysiology techniques in male Sprague-Dawley rats. Exogenous norepinephrine (NE) enhanced LPCS-evoked inhibitory postsynaptic currents (eIPSCs) via the activation of β-ARs, because this effect was blocked by propranolol. EtOH potentiation of LPCS eIPSCs was also blocked by propranolol and significantly reduced by NE pretreatment, suggesting that NE and EtOH may enhance LPCS inhibition via a common mechanism. EtOH enhancement of LPCS eIPSCs was significantly reduced by a selective β1-, but not β2- or β3-, AR antagonist, and both EtOH and NE potentiation of LPCS IPSCs was blocked by postsynaptic disruption of cAMP signaling. These data suggest that EtOH enhances LPCS synapses via a postsynaptic β1-AR, cAMP-dependent cascade. Because enhancement of LPCS inhibition can reduce anxiety-like behaviors, these findings shed light on a novel mechanism that may play a role in some of the anxiolytic effects of EtOH that are thought to contribute to the development and progression of alcoholism.
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Affiliation(s)
- Yuval Silberman
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
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Ros-Simó C, Ruiz-Medina J, Valverde O. Behavioural and neuroinflammatory effects of the combination of binge ethanol and MDMA in mice. Psychopharmacology (Berl) 2012; 221:511-25. [PMID: 22139453 DOI: 10.1007/s00213-011-2598-4] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/31/2011] [Accepted: 11/21/2011] [Indexed: 01/22/2023]
Abstract
RATIONALE Binge drinking is a common pattern of alcohol consumption among young people. Binge drinkers are especially susceptible to brain damage when other substances are co-administered, in particular, 3,4-methylendioxymethamphetamine (MDMA). OBJECTIVE To evaluate the behavioural consequences of voluntary binge ethanol consumption, alone and in combination to MDMA. Also, to elucidate the effects of the combined consumption of these two drugs on neuroinflammation. MATERIALS AND METHODS Adolescent mice received MDMA (MDMA-treated mice), ethanol (ethanol-treated mice group) or both (ethanol plus MDMA-treated mice). Drinking in the dark (DID) procedure was used as a model of binge. Body temperature, locomotor activity, motor coordination, anxiety-like and despair behaviour in adolescent mice were evaluated 48 h, 72 h, and 7 days after the treatments. Also, neuroinflammatory response to these treatments was measured in the striatum. RESULTS The hyperthermia observed in MDMA-treated mice was abolished by pre-exposition to ethanol. Ethanol plus MDMA-treated mice showed lower locomotor activity. Ethanol-treated mice showed motor coordination impairment and increased despair behaviour. Anxiety-like behaviour was only seen in animals that were treated with both drugs. Contrarily, neuroinflammation was mostly seen in animals treated only with MDMA. CONCLUSIONS Ethanol and MDMA co-administration increases the neurobehavioural changes induced by the consumption of each one of these drugs. However, as ethanol consumption did not increase neuroinflammatory responses induced by MDMA, other mechanisms, mediated by ethanol, are likely to account for this effect and need to be evaluated.
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Affiliation(s)
- Clara Ros-Simó
- Grup de Recerca en Neurobiologia del Comportament, Departament de Ciències Experimentals i de la Salut, Universitat Pompeu Fabra, Parc de Recerca Biomèdica de Barcelona, Dr Aiguader 88, 08003 Barcelona, Spain
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Christian DT, Alexander NJ, Diaz MR, Robinson S, McCool BA. Chronic intermittent ethanol and withdrawal differentially modulate basolateral amygdala AMPA-type glutamate receptor function and trafficking. Neuropharmacology 2012; 62:2430-9. [PMID: 22387532 DOI: 10.1016/j.neuropharm.2012.02.017] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2011] [Revised: 02/15/2012] [Accepted: 02/16/2012] [Indexed: 12/19/2022]
Abstract
The amygdala plays a critical role in the generation and expression of anxiety-like behaviors including those expressed following withdrawal (WD) from chronic intermittent ethanol (CIE) exposure. In particular, the BLA glutamatergic system controls the expression of both innate and pathological anxiety. Recent data suggests that CIE and WD may functionally alter this system in a manner that closely parallels memory-related phenomena like long-term potentiation (LTP). We therefore specifically dissected CIE/WD-induced changes in glutamatergic signaling using electrophysiological and biochemical approaches with a particular focus on the plasticity-related components of this neurotransmitter system. Our results indicate that cortical glutamatergic inputs arriving at BLA principal via the external capsule undergo predominantly post-synaptic alterations in AMPA receptor function following CIE and WD. Biochemical analysis revealed treatment-dependent changes in AMPA receptor surface expression and subunit phosphorylation that are complemented by changes in total protein levels and/or phosphorylation status of several key, plasticity-associated protein kinases such as calcium/calmodulin-dependent protein kinase II (CaMKII) and protein kinase C (PKC). Together, these data show that CIE- and WD-induced changes in BLA glutamatergic function both functionally and biochemically mimic plasticity-related states. These mechanisms likely contribute to long-term increases in anxiety-like behavior following chronic ethanol exposure.
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Affiliation(s)
- Daniel T Christian
- Department of Physiology and Pharmacology, Wake Forest School of Medicine, Winston-Salem, NC, USA
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