mGluR-Homer interactions in excessive drinking

目前关于酒精中毒的理论认为，酒精诱导的边缘结构内的神经适应 大脑，包括伏隔核(NAC)，有助于从娱乐饮酒过渡 过度饮酒。最近，第1组代谢性谷氨酸受体(MGluR)- 相关的支架蛋白Hmer 2被认为是一种活性的和必要的细胞介质 酒精诱导的小鼠神经可塑性。组成性表达的荷马蛋白促进组1 mGluR- 刺激细胞内信号和突触后密度内聚集第1组mGluR，共定位 这些受体与其他与突触可塑性有关的蛋白，如PI3K(磷脂酰肌醇-3) 激酶)。Hmer-2基因缺失降低NAC中G1mGluRs的功能和表达 Hmer 2基因敲除(KO)小鼠的避免饮酒和不耐受的行为表型类似于 1组mGluRs的药理阻断所致。总而言之，这些观察结果 提示第1组mGluR-Hmer信号是过量饮酒的重要细胞介质 消费。为了直接检验这一假说，这项提议将采用体内药理学和遗传学 表征NAC内第1组mGluR-Hmer信号在调节中作用的方法 程序高酒精消耗量(SHAC)小鼠模型(AIM)内过度饮酒 1)。免疫组织化学和免疫印迹方法将被用来确定Hmer 2的作用 N调节持续过度饮酒对NAc突触构筑的影响 神经元，以及mGluR-Hmer信号复合体的形成、亚细胞定位和功能 (目标2)。最后，将过量饮酒的遗传变异与mGluR-Hmer-PI3K表达联系起来 和NAC内的信号，免疫印迹总蛋白含量和膜定位 MGluR-Hmer-PI3K信号级联的成员将在小鼠品系之间进行选择性比较 为高SHAC和SLAC(预定低酒精消耗量)表型而培育。这些研究的结果 研究将进一步加深我们对细胞机制的理解，这些机制涉及调节从 娱乐性过度饮酒，并提供对酒精中毒的病因及其 治疗。

Current theories of alcoholism posit that alcohol-induced neuroadaptations within limbic structures in the brain, including the nucleus accumbens (NAC), contribute to the transition from recreational alcohol drinking to excessivealcohol consumption. Recently, the Group 1 metabotropic glutamate receptor (mGluR)- associated scaffolding protein Homer2 was identified as an active and necessary cellular mediator of alcohol-induced neural plasticity in mice. Constitutively expressed Homer proteins facilitate Group 1 mGluR- stimulated intracellular signaling and cluster Group 1 mGluRs within the postsynaptic density, co-localizing these receptorswith other proteins implicated in synaptic plasticity, such as PI3K (phosphatiylionsitol-3 kinase). Homer2 deletion reduces the function and the expression of Group 1 mGluRs in the NAC in vivo and the alcohol-avoiding and -intolerant behavioral phenotype of Homer2 knock-out (KO) mice resembles that produced by the pharmacological blockade of Group 1 mGluRs. Collectively, these observations suggest that Group 1 mGluR-Homer signaling is an important cellular mediator of excessive alcohol consumption. To test this hypothesis directly, this proposal will employ in vivo pharmacological and genetic approaches to characterizethe role for Group 1 mGluR-Homer signaling within the NAC in regulating excessive alcohol consumption within the scheduled high alcohol consumption (SHAC) murine model (Aim 1). Immunohistochemical and immunoblotting approaches will be employed to determine the role for Homer2 n regulating the effects of sustained, excessivealcohol consumption upon the synaptic architecture of NAC neurons, as well as the formation, subcellular localization and function of mGluR-Homer signaling complexes (Aim 2). Finally, to relate genetic variance in excessive alcohol drinking to mGluR-Homer-PI3K expression and signaling within the NAC, immunoblotting the total protein content and membrane localization of members of the mGluR-Homer-PI3K signaling cascade will be compared between mouse lines selectively bred for high SHAC and SLAC (Scheduled Low Alcohol Consumption) phenotypes. The results of these studies will further our understanding of the cellular mechanisms involved in regulating the transition from recreational to excessive alcohol drinking and provide greater insight into the etiology of alcoholism and its treatment.