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性行为/大脑障碍，其特征是无法自我调节酒精摄入量。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）、中脑核（NAcc）壳和内侧前额叶皮质（mPFC）的GABA能系统。有证据表明，GABA能系统在这些结构中的每一个至少有一定的作用，在乙醇自我管理的调制，但这些结构的作用，在调制自愿狂欢样乙醇摄入量尚未检查。本研究的目的是：1）使用最近开发的有限接近小鼠模型，研究前腹侧被盖区和后腹侧被盖区、NAcc壳和mPFC中GABA能受体系统在调节暴食样乙醇摄入中的作用，以及2）确定GABAA亚基、GABAB亚型、或其它GABA相关基因在上述脑结构中的表达通过使用相同的小鼠模型每日狂饮样乙醇摄入而改变。在目标1和2中，小鼠将在评估暴食样乙醇摄入前即刻接受前部或后部VTA、-NAcc壳或-mPFC内微量注射唑吡坦或4，5，6，7-四氢异恶唑并-[5，4- c]吡啶-3-醇（THIP）（已知分别靶向突触和突触外GABAA受体）或巴氯芬（GABAB受体激动剂）。我们预测，这些药物的显微注射将减少在大脑区域的特定方式的行为。在目标3中，将使用实时聚合酶链反应（PCR）和蛋白质印迹法在前后VTA、NAcc壳和mPFC中检查酗酒样乙醇摄入相关的GABA相关mRNA表达变化。我们预计，酒精摄入量将改变某些GABAA亚基，GABAB亚型，和其他GABA相关的转录在这些结构的表达。拟议的工作将有助于我们的一般知识有关的GABA能电路参与腹侧被盖区，NAcc，和mPFC的调制狂欢样乙醇摄入量。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治疗酒精中毒的药理学工具。公共卫生相关性-拟议的工作将有助于我们的一般知识，涉及GABA电路在腹侧被盖区，nucleus tubebens，和前额皮质在维持酗酒样乙醇摄入。它将促进我们对人类从偶尔饮酒到酒精滥用和依赖的过渡相关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.