Alcohol-related suppression of GIRK channel activity in the basal amygdala: a link to plasticity of glutamatergic neurotransmission and withdrawal-associated behavior?

项目总结 酒精中毒和戒酒的反复循环促进了大脑中调节情绪的区域的适应， 学习和目标导向的行为。这些适应被认为促进了高度的焦虑、认知 缺陷和渴望-酒精使用障碍(AUD)的特征，共同促进强迫性药物- 寻求行为，增加复发的易感性，并阻碍适应行为的发展， 可以支持节欲。尽管AUD的治疗选择有限，但临床前和临床数据 引起了人们对GABAB受体(GABABR)的兴趣，将其作为治疗干预的潜在靶点 减少食欲，减少酒精摄入量。这个项目的重点是乙醇诱导的 杏仁基底核GABR依赖信号的适应性--焦虑的关键底物 学习与奖励和令人厌恶的经历有关。使用两种不同的酒精暴露模型 反复的中毒循环，我们发现躯体树突状细胞GABR依赖的信号在 最后一次酒精暴露后3-4天，测量小鼠BA的主要神经元。改编的是 杏仁外侧核的主神经元或内侧前额叶/前额叶的锥体神经元中未见 大脑皮层，也不是由重复的可卡因引起的。这种适应归因于对G蛋白门控的抑制 向内纠正K(GIRK)通道活动，这是焦虑相关行为和联想的已知决定因素 学习。这个项目的目标是了解显著的特征和机制，以及 乙醇抑制GIRK通道活性的神经生理学和行为学意义 BA主神经元。两个相互关联的目的是：(1)阐明乙醇的潜在机制-- 诱导抑制GIRK通道活性。拟议的研究将采用体外技术 电生理学、免疫电子显微镜和神经元特异性病毒操作来验证这一假说 乙醇对BA主神经元GIRK通道活性的抑制是通过 GIRK3亚基依赖的GIRK通道内化。(2)了解下游 GIRK通道可塑性的神经生理学和行为学意义。拟议的研究将探索 抑制BA主神经元GIRK通道活性的意义，验证了它的假设 足以在离散的BA投射中激发谷氨酸能神经传递的适应性。同时， 适应焦虑相关行为、联想(恐惧)学习和自愿学习的后果 在病毒基因抑制GIRK后，将在乙醇天真的小鼠中评估乙醇的消耗 BA主神经元的通道活动。摘要：该项目充分利用了 经验丰富的团队，以及定制研究工具的可用性，以调查之前未描述的 酒精诱导的神经适应对焦虑相关行为和联想的已知影响 学习。该项目的成功完成可能会为旨在治疗AUD的干预措施产生新的目标。

PROJECT SUMMARY Repeated cycles of alcohol intoxication and withdrawal foster adaptations in brain regions that regulate mood, learning, and goal-directed behavior. These adaptations are thought to promote heightened anxiety, cognitive deficits, and craving – hallmarks of alcohol use disorder (AUD) that collaborate to promote compulsive drug- seeking behavior, increase relapse susceptibility, and impede the development of adaptive behaviors that could support abstinence. Although treatment options for AUD are limited, preclinical and clinical data have generated interest in the GABAB receptor (GABABR) as a potential target for therapeutic interventions aimed at diminishing craving and reducing alcohol intake. The focus of this project is on an ethanol-induced adaptation in GABABR-dependent signaling in the basal amygdala – a key substrate of anxiety as well as learning related to rewards and aversive experiences. Using two distinct ethanol exposure models that yield repeated cycles of intoxication, we found that somatodendritic GABABR-dependent signaling is suppressed in principal neurons of the mouse BA, as measured 3-4 days after the last ethanol exposure. The adaptation is not seen in principal neurons of the lateral amygdala or pyramidal neurons of the medial prefrontal/prelimbic cortex, nor is it evoked by repeated cocaine. The adaptation is attributable to a suppression of G protein-gated inwardly rectifying K+ (GIRK) channel activity, a known determinant of anxiety-related behavior and associative learning. The goal of this project is to understand the salient features and mechanisms, as well as neurophysiological and behavioral implications, of the ethanol-induced suppression of GIRK channel activity in BA principal neurons. The two interrelated AIMs are to: (1) Elucidate mechanisms underlying the ethanol- induced suppression of GIRK channel activity. Proposed studies will employ techniques in ex vivo electrophysiology, immunoelectron microscopy, and neuron-specific viral manipulations to test the hypothesis that the ethanol-induced suppression of GIRK channel activity in BA principal neurons is mediated by the GIRK3 subunit-dependent internalization of GIRK channels. (2) Understand the downstream neurophysiological and behavioral implications of GIRK channel plasticity. Proposed studies will probe the implications of the suppression of GIRK channel activity in BA principal neurons, testing the hypothesis that it is sufficient to provoke adaptations in glutamatergic neurotransmission in discrete BA projections. In parallel, the consequences of the adaptation to anxiety-related behavior, associative (fear) learning, and voluntary ethanol consumption will be evaluated in ethanol-naïve mice, following viral genetic suppression of GIRK channel activity in BA principal neurons. Summary: This project leverages the complementary expertise of an experienced team, and the availability of custom research tools, to investigate a previously undescribed ethanol-induced neuroadaptation involving a known influence on anxiety-related behavior and associative learning. Successful completion of this project may yield new targets for interventions designed to treat AUD.