Ethanol and mGluR2 signaling

项目摘要 目前的NIAAA战略计划要求努力确定酒精的新分子作用和新的补救措施， 减轻酒精影响的大脑区域。不断变化的研究工具成倍地加速了我们的研究 了解受酒精使用和共病情感障碍影响的大脑区域和回路。然而，在这方面， 努力了解这些受影响的神经活动改变的分子机制， 各地区落后了。为了填补这一空白，我们将探索一种以前未知的分子机制 由此酒精调节前额皮质（PFC）中的脑胆固醇导致异常mGluR 2 慢性间歇性乙醇（CIE）暴露的啮齿动物模型中的功能和谷氨酸传递。这 因此，调节可能导致饮酒和焦虑样行为，通常在患者中观察到 酒精使用障碍（AUD）使用CIE啮齿动物模型，我们表明，CIE增加谷氨酸释放， 前额叶皮层沿着饮酒和焦虑样行为的增加。此外，我们和其他人报告说， PFC神经元投射到皮层下区域（例如BLA或NAc）的消融消除了这些行为。因此，在本发明中， PFC是调节依赖相关神经和行为活动的关键中枢。但 CIE诱导PFC中谷氨酸传递中断的分子机制仍然存在 难以捉摸。我们的初步数据强烈表明mGluR 2参与该区域：a）CIE空间分离 B）CIE消除了mGluR 2对Gαo亚基的抑制，并减少了mGluR 2对Gαi/o的刺激; Gβγ介导的PFC神经元突触前谷氨酸释放和突触后内在兴奋性; c）CIE 损害mGluR 2对焦虑样行为的抑制。mGluR 2功能的这种缺陷可能由以下因素控制： 膜胆固醇我们发现CIE通过增强PFC中的胆固醇含量， 胆固醇合成酶HMG-CoA还原酶（HMGCR）的活性。重要的是，降低，CIE- 依赖性mGluR 2功能可通过离体胆固醇去除逆转， 胆固醇添加到幼稚组织。我们假设阻断胆固醇增加会减弱CIE- 依赖性破坏mGluR 2介导的G蛋白活化、神经生理学和依赖性相关 行为。我们将使用CRISPR/Cas9，细胞，电生理和行为方法来测试我们的 假说.该提案在概念上和技术上都具有创新性和重要性，在很大程度上探讨了 CIE暴露对胆固醇调节mGluR 2功能的潜在影响被忽视， 谷氨酸传输和类似焦虑的行为。

Project Summary Current NIAAA strategic plan calls for efforts to identify novel molecular actions of alcohol and new remedies to mitigate alcohol-impacted brain regions. Ever-changing research tools have exponentially accelerated our understanding of brain regions and circuits affected by alcohol use and comorbid affective disorders. However, efforts towards the understanding of molecular mechanisms for altered neural activity in these impacted regions have lagged behind. To fill in this gap, we will explore a previously unknown molecular mechanism whereby ethanol modulation of brain cholesterol in the prefrontal cortex (PFC) leads to aberrant mGluR2 function and glutamate transmission in a rodent model of chronic intermittent ethanol (CIE) exposure. This modulation may thus contribute to alcohol drinking and anxiety-like behavior, commonly observed in patients with alcohol use disorder (AUD). Using a CIE rodent model, we show that CIE increases glutamate release in the PFC along with increased alcohol drinking and anxiety-like behavior. Further, we and others report that ablation of PFC neuron projection to subcortical regions (e.g. BLA or NAc) abolishes these behaviors. Thus, the PFC is a critical hub for regulating dependence-related neural and behavioral activity. However, the molecular mechanisms underlying CIE-induced disruption of glutamate transmission in the PFC remain elusive. Our preliminary data strongly suggest mGluR2 involvement in this region: a) CIE spatially segregates mGluR2 from Gαo subunit and reduces mGluR2 stimulation of Gαi/o; b) CIE abolishes mGluR2 inhibition of Gβγ-mediated presynaptic glutamate release and postsynaptic intrinsic excitability of PFC neurons; and c) CIE impairs mGluR2 inhibition of anxiety-like behavior. Such a deficit in mGluR2 function may be governed by membrane cholesterol. We found that CIE drastically increases cholesterol content in the PFC by enhancing the activity of HMG-CoA-reductase (HMGCR), a cholesterol synthesis enzyme. Importantly, reduced, CIE- dependent mGluR2 function can be reversed by ex vivo cholesterol removal and mimicked by ex vivo cholesterol addition to naïve tissue. We hypothesize that blockade of cholesterol increase will attenuate CIE- dependent disruption of mGluR2-mediated G-protein activation, neurophysiology and dependence-related behaviors. We will use CRISPR/Cas9, cellular, electrophysiological and behavioral approaches to test our hypothesis. The proposal is conceptually and technically innovative and significant, investigating a largely overlooked and potentially impactful effect of CIE exposure on cholesterol modulation of mGluR2 function, glutamate transmission and anxiety-like behavior.