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

描述(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，特征是无法自我调节酒精摄入量。调节酒精强化特性的大脑区域内的神经适应(即基因表达的变化)可能与失去对酒精摄入量的控制或酗酒有关。我们将研究前腹被盖区(VTA)、伏核(NAcc)壳和内侧前额叶皮质(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发挥了一定的作用，但这些结构在调节自愿暴饮式乙醇摄取中的作用尚未得到研究。本研究的目标是：1)利用最近建立的小鼠限制性酒精摄入模型，研究前脑和后脑VTA、NAcc壳和mPFC中GABA能受体系统在调节暴饮性酒精摄入中的作用；2)利用相同的小鼠模型，确定上述脑结构中的GABAA亚单位、GABAB亚型或其他GABA相关基因的表达是否会因每天暴饮性酒精摄入而改变。在AIMS 1和AIMS 2中，小鼠将在评估暴饮式酒精摄入之前立即接受前部或后部VTA内、-NAcc壳或-mPFC微量注射唑吡坦或4，5，6，7-四氢异恶唑-[5，4-c]吡啶-3-醇(THIP)，已知分别靶向突触和突触外GABAA受体，或GABAB受体激动剂巴氯芬。我们预测，微量注射这些药物将以一种特定于大脑区域的方式减少行为。在目标3中，将使用实时聚合酶链式反应(PCR)和Western印迹技术检测VTA、NAcc壳和mPFC中GABA相关基因表达的暴饮式酒精摄入相关变化。我们预计，暴饮暴食的酒精摄入将改变这些结构中某些GABAA亚单位、GABAB亚型和其他GABA相关转录本的表达。这项拟议的工作将有助于我们了解GABA能通路在VTA、NAcc和mPFC调节狂欢样乙醇摄入中的作用。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，并最终导致开发出更好的治疗酒精中毒的药理学工具。

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.