Molecular regulation of CeA glutamate and binge drinking

描述（由申请人提供）：在美国，酗酒是最普遍的酒精中毒形式，但酗酒的神经生物学还没有得到很好的理解。我的实验室的大量功能数据表明，酒精诱导伏隔核（NAC）外壳内mGluR5/Homer2通路活性（通过PI3K和PKC5）的增加对狂饮小鼠模型中的饮酒倾向很重要。NAC外壳与扩展的杏仁核亚回路的其他成员具有相同的细胞结构、解剖和功能特征，包括杏仁核中央核（CeA）——一个与酒精中毒的神经生物学高度相关的大脑区域。在慢性饮酒模型中，Homer2在CeA中富集，其水平与mGluR1/5一致上调。初步的功能数据表明，正如在NAC外壳中观察到的那样，抑制CeA mGluR5和PI3K的活性可以减少小鼠的狂饮，这一发现与现有的CeA PKC5敲除后减少有限通道酒精摄入量的报告一致。这些数据还表明，mglur5介导的信号通过CeA内的PI3K和PKC5介导，在酗酒的调节中也发挥了重要作用，可能还有酗酒的遗传易感性。该项目将扩展这些最近的观察结果，并采用我们的行为药理学和遗传学方法的结合来测试一个总体假设，即特发性或酒精诱导的mglur介导的信号的增加，通过其1q亚基到PKC5和23亚基到PI3K，在扩展的杏仁核结构中，特别是CeA，对暴饮暴食的表现和遗传易感性很重要。本提案的目的1将采用药理学和遗传学方法相结合的方法来验证特定假设，即CeA内通过mGluR5-Homer2-PI3K和mGluR5-Homer2-PKC5途径的完整信号传导对于维持小鼠过量酒精摄入是必要和/或充分的。目的2将这些功能研究与酗酒史对扩展杏仁核结构及其前额皮质互联区域内mglur5介导的信号通路的表达和激活状态的短期和长期影响联系起来。目的3将使用几种动物模型，将基础和酒精刺激的mglur5 - homer2激酶途径激活与酗酒的遗传倾向联系起来。预计获得的结果将大大增加我们对扩展杏仁核中mGluR/ homer2介导的信号调节过度饮酒的维持和易感性的作用的理解。这些知识将指出酒精诱导的mGluR5/ homer介导的突触后谷氨酸传递在扩展的杏仁核结构和它们的前额叶皮层相互连接中的调节的改变是调节酗酒倾向的关键神经适应性，这与理解酒精中毒易感性及其谷氨酸靶向药物治疗具有高度相关性。

DESCRIPTION (provided by applicant): Binge alcohol drinking is the most prevalent form of alcoholism within the United States yet the neurobiology of binge drinking is not well-understood. A significant body of functional data from my laboratory demonstrates that alcohol-induced increases in mGluR5/Homer2 pathway activity (via PI3K and PKC5) within the nucleus accumbens (NAC) shell as important for the propensity to consume alcohol in murine models of binge alcohol drinking. The NAC shell shares cytoarchitectural, anatomical and functional features with other members of the extended amygdala subcircuit, including the central nucleus of the amygdala (CeA) - a brain region highly implicated in the neurobiology of alcoholism. Homer2 is enriched in the CeA and its levels are up-regulated in concert with those of mGluR1/5 in models of chronic alcohol drinking. Preliminary functional data indicates that, as observed for the NAC shell, inhibiting CeA mGluR5, as well as PI3K, activity reduces binge alcohol drinking in mice, a finding consistent with existing reports for a reduction in limited access alcohol intake upon CeA PKC5 knock-down. Such data point to an important role also for mGluR5-mediated signaling through both PI3K and PKC5 within the CeA in the regulation of, and perhaps genetic vulnerability to, binge drink. This project will expand upon these recent observations and employ our combination of behavioral pharmacological and genetic approaches to test the over-arching hypothesis that idiopathic or alcohol-induced increases in mGluR-mediated signaling through its 1q subunit to PKC5 and its 23 subunit to PI3K within extended amygdala structures, notably the CeA, is important for the manifestation of, and genetic vulnerability to, binge alcohol drinking. Aim 1 of this proposal will employ a combination of pharmacological and genetic approaches to test the specific hypothesis that intact signaling through the mGluR5-Homer2-PI3K and mGluR5-Homer2-PKC5 pathways within the CeA is necessary and/or sufficient for maintaining excessive alcohol intake in mice. Aim 2 will relate these functional studies to the short- and long-term effects of a history of binge drinking upon the expression and activational state of mGluR5-mediated signaling pathways within extended amygdala structures and their prefrontal cortical interconnected regions. Aim 3 will relate basal and alcohol-stimulated mGluR5-Homer2-kinase pathway activation to genetic propensity to binge drink, using several animal models. It is anticipated that the results obtained will greatly increase our understanding of the role for mGluR/Homer2-mediated signaling within the extended amygdala regulates the maintenance of, and vulnerability to, excessive alcohol drinking. Such knowledge will point to alcohol-induced alterations in mGluR5/Homer-mediated regulation of post-synaptic aspects of glutamate transmission within extended amygdala structures and their prefrontal cortical interconnections as critical neuroadaptations regulating the propensity to binge drink, which has high relevance for understanding of alcoholism vulnerability and its treatment with glutamate-targeting pharmacotherapies. PUBLIC HEALTH RELEVANCE: Repeated alcohol administration induces persistent, maladaptive changes in the excitatory neurotransmitter glutamate within the extended amygdala and some of these neuroadaptations are central to maintaining excessive alcohol drinking behavior. Thus, an understanding of the molecular mechanisms involved in the capacity of repeated bouts of binge alcohol drinking upon the postsynaptic mechanisms mediating extended amygdala glutamate transmission will assist in the identification of novel therapeutic targets for the treatment of alcoholism, as well as assist in screening "at risk" individuals or predicting individual treatment outcomes. To this end, this project will employ a combination of behavioral, genetic and immunological approaches to characterize the short- and long-term influences of binge drinking upon mGluR5-mediated signaling within the extended amygdala and its relation to binge drinking vulnerability.