GABAergic Mechanisms in the Modulation of Binge-Like Ethanol Intake in Mice

描述（由申请人提供）：乙醇（酒精）依赖是一种慢性复发的行为/大脑障碍，其特征是无法自我调节酒精摄入。大脑区域内调节乙醇强化特性的神经适应（即基因表达的变化）可能与酒精摄入失控或酗酒有关。我们将研究前、后腹侧被盖区（VTA）、伏隔核（NAcc）壳和内侧前额叶皮层（mPFC）的gaba能系统。有证据表明，这些结构中的gaba能系统至少在调节乙醇自我给药方面有一定的作用，但这些结构在调节自愿酗酒样乙醇摄入方面的作用尚未得到检验。目前的研究目标是：1)利用最近开发的有限通路小鼠模型，研究gaba能受体系统在前、后VTA、NAcc壳和mPFC中的作用，以及2)确定GABAA亚基、GABAB亚型或其他gaba相关基因在上述脑结构中的表达是否会因每天的酗酒样乙醇摄入而改变。在目的1和2中，小鼠将在评估狂饮样乙醇摄入之前立即接受左吡坦或4,5,6,7-四氢异恶唑-[5,4- c]吡啶-3-醇（THIP）的前或后腔内vta， - nacc壳或- mpfc显微注射，已知分别靶向突触和突触外GABAA受体，或巴氯芬（GABAB受体的激动剂）。我们预测这些药物的显微注射将减少大脑特定区域的行为。在目的3中，我们将使用实时聚合酶链反应（PCR）和Western blot技术检测狂饮样乙醇摄入相关的gaba相关mRNA表达在VTA前部和后部、NAcc壳和mPFC中的变化。我们预计酗酒样的乙醇摄入会改变这些结构中某些GABAA亚基、GABAB亚型和其他gaba相关转录物的表达。所提出的工作将有助于我们对VTA， NAcc和mPFC中gaba能回路参与狂欢样乙醇摄入调节的一般知识。我们希望这将促进我们对与人类酒精滥用和依赖相关的神经生物学因素的理解，并最终导致开发更好的药物工具来治疗酒精中毒。拟议的工作将有助于我们了解腹侧被盖区、伏隔核和前额叶皮层中GABA回路参与维持酗酒样乙醇摄入的一般知识。它将促进我们对与人类从偶然饮酒到酒精滥用和依赖过渡相关的神经生物学因素的理解，并可能最终导致更好的酒精中毒药物治疗策略。

DESCRIPTION (provided by applicant): Ethanol (alcohol) dependence is a chronic relapsing behavioral/brain disorder characterized by an inability to self-regulate alcohol intake. Neuroadaptation (i.e., changes in gene expression) within brain regions that mediate ethanol's reinforcing properties may be associated with loss of control over ethanol intake, or binge drinking. We will investigate the GABAergic systems of the anterior and posterior ventral tegmental area (VTA), nucleus accumbens (NAcc) shell, and medial prefrontal cortex (mPFC). Evidence suggests that the GABAergic systems in each of these structures has at least some role in the modulation of ethanol self-administration, but the role of these structures in the modulation of voluntary binge-like ethanol intake has not been examined. The goals of the current proposal are to 1) investigate the role of GABAergic receptor systems in the anterior and posterior VTA, NAcc shell, and mPFC in the modulation of binge-like ethanol intake using a recently developed limited access mouse model, and to 2) ascertain whether GABAA subunit, GABAB subtype, or other GABA-associated gene expression in the above brain structures is altered by daily binge-like ethanol intake using the same mouse model. In aims 1 and 2, mice will receive anterior or posterior intra-VTA, -NAcc shell, or -mPFC microinjections of zolpidem or 4,5,6,7-tetrahydroisoxazolo-[5,4- c]pyridin-3-ol (THIP), known to target synaptic and extrasynaptic GABAA receptors respectively, or baclofen, an agonist at GABAB receptors, immediately prior to assessment of binge-like ethanol intake. We predict that microinjection of these drugs will reduce the behavior in a brain region specific manner. In aim 3, binge-like ethanol intake-associated changes in GABA-related mRNA expression will be examined in the anterior and posterior VTA, NAcc shell, and mPFC using real-time polymerase chain reaction (PCR) and Western blot. We expect that binge-like ethanol intake will alter the expression of certain GABAA subunits, GABAB subtypes, and other GABA-associated transcripts in these structures. The proposed work will contribute to our general knowledge concerning the involvement of GABAergic circuits in the VTA, NAcc, and mPFC in the modulation of binge-like ethanol intake. We hope it will advance our understanding of the neurobiological factors associated with alcohol abuse and dependence in humans and ultimately lead to the development of better pharmacological tools in the treatment of alcoholism. PUBLIC HEALTH RELEVANCE The proposed work will contribute to our general knowledge concerning the involvement of GABA circuits in the ventral tegmental area, nucleus accumbens, and prefrontal cortex in the maintenance of binge-like ethanol intake. It will advance our understanding of the neurobiological factors associated with the transition from casual alcohol use to alcohol abuse and dependence in humans, and may ultimately lead to better pharmacological treatment strategies for alcoholism.