Alcohol Regulation of Synaptic and Extrasynaptic GluN2B-NMDA Receptors in BNST

描述（由申请人提供）：酒精中毒是一种进行性复发性疾病，尽管目前的治疗，复发率为50-90%。开发新的治疗策略需要了解酒精中毒的神经生物学基础。复发的主要来源是与酒精戒断相关的负面影响（即焦虑和抑郁）。终纹床核（bed nucleus of the stria terminalis，BNST）是一个与酒精戒断相关的负面影响有关的大脑区域。BNST的长期适应通过神经递质谷氨酸和NMDA受体（NMDAR）发生。在BNST中，我最近的工作表明，酒精的急性和慢性作用是由特定的NMDAR亚基（GluN 2B）引起的。此外，慢性酒精导致通过这些GluN 2B-NMDAR在突触外位置的传输增加。通过突触外GluN 2B-NMDARs的信号传导与许多病理条件有关;然而，慢性酒精后GluN 2B-NMDARs上调和重新定位的机制尚不清楚。在这个提议中，我将使用一种新的，高度特异性的发现为基础的蛋白质组学方法，结合电生理和生物化学技术，以确定酒精诱导的变化GluN 2B相互作用蛋白在突触和突触外的位置。初步研究表明，慢性酒精可能会改变突触内连接NMDAR和信号伴侣的蛋白质（Homer，GKAP，Shank，mGlur 5和PSD蛋白）。我建议，这些蛋白质的不稳定，慢性酒精允许重新定位的GluN 2B-NMDAR（目的1）。mGluR 5是另一种谷氨酸受体，已显示其调节BNST中的可塑性。这些受体也是已知的后可塑性（NMDAR的可塑性）的介质，并且在其他区域中发育亚基从GluN 2A转变为GluN 2B。因此，mGluR 5信号传导是慢性酒精后GluN 2B-NMDAR增强的强有力候选者（目的2）。虽然了解成年人的这些关键神经适应是关键，但临床数据表明，酒精依赖的最强预测因素是 青少年饮酒基础研究发现，酒精对青少年和成年人的影响有许多不同;其中之一是在慢性酒精戒断期间长期的负面影响。皮质和海马（BNST输入）在青春期经历NMDAR丰度下降和NMDAR亚基组成（GluN 2B至2A）的变化。相反，BNST似乎保留高GluN 2B到成年。BNST中这些差异发展轨迹的交叉可能会导致独特的调节 兴奋性传递和可塑性。因此，本提案的独立（R 00）阶段将研究青春期酒精驱动的NMDAR组成、定位和信号传导的动态调节。

DESCRIPTION (provided by applicant): Alcoholism is a progressive relapsing disorder, with relapse rates from 50-90% in spite of current treatments. The development of new treatment strategies requires an understanding of the neurobiological underpinnings of alcoholism. A primary source of relapse is the negative affect (i.e. anxiety and depression) associated with alcohol withdrawal. The bed nucleus of the stria terminalis, BNST, is a brain region implicated in this negative affect associated with alcohol withdrawal. Long-term adaptations in the BNST occur through the neurotransmitter glutamate and the NMDA receptor (NMDAR). In the BNST, my recent work illustrates that the acute and chronic actions of alcohol are caused by a particular NMDAR subunit (GluN2B). Further, chronic alcohol leads to an increase in transmission through these GluN2B-NMDARs at extrasynaptic locations. Signaling through extrasynaptic GluN2B-NMDARs has been connected to a number of pathological conditions; however, the mechanisms underlying the upregulation and relocation of GluN2B-NMDARs after chronic alcohol are unknown. In this proposal, I will be using a novel, highly specific discovery-based proteomic approach in conjunction with electrophysiological and biochemical techniques to identify alcohol-induced changes in GluN2B interacting proteins in synaptic and extrasynaptic locations. Preliminary work suggests that chronic alcohol may alter proteins that link NMDARs and signaling partners within the synapse (Homer, GKAPs, Shank, mGlur5, and PSD proteins). I propose that destabilization of these proteins by chronic alcohol allows for the relocalization o GluN2B-NMDARs (Aim 1). mGluR5 is another glutamate receptor that has been shown to modulate plasticity in the BNST. These receptors are also known mediators of metaplasticity (plasticity of NMDARs) and the developmental subunit shifts from GluN2A to GluN2B in other regions. Therefore, mGluR5 signaling is a strong candidate for the enhancement of GluN2B-NMDARs following chronic alcohol (Aim 2). While understanding these critical neuroadaptations in adults is key, clinical data demonstrates that the strongest predictor for alcohol dependence is adolescent alcohol use. Basic research finds many differential effects of alcohol between adolescents and adults; one of these being prolonged negative affect during withdrawal from chronic alcohol. The cortex and hippocampus (BNST inputs) undergo declines in NMDAR abundance and shifts in NMDAR subunit composition (GluN2B to 2A) during adolescence. In contrast, the BNST seems to retain high GluN2B into adulthood. This intersection of these differential developmental trajectories within the BNST is likely to culminate in unique regulation of excitatory transmission and plasticity during adolescence. Therefore, the independent (R00) phase of this proposal will investigate alcohol-driven dynamic regulation of NMDAR composition, localization, and signaling during adolescence.