Role of NR2B Subunit in Glutamate Signaling and Anxiety during Ethanol Withdrawal

项目摘要/摘要：众所周知，酒精中毒是一种慢性复发性疾病。随着酒精使用过渡到依赖，动机驱动力从最初的正强化（乙醇的愉悦效应）到后来的负强化（乙醇的戒断/负面影响）。在戒断过程中，调节依赖性受试者复发的一种行为是焦虑。因此，了解在戒断过程中导致焦虑的机制对酒精中毒的治疗至关重要。特别涉及焦虑和压力调节的区域是延伸杏仁核（终纹床核; BNST和杏仁核中央核; CeA）.这些核团已被证明调节对焦虑刺激的反应和压力诱导的吸毒复发，因此，对理解乙醇依赖性至关重要.存在于延伸杏仁核中的一种神经递质系统对乙醇的影响特别敏感，这是谷氨酸。多条证据表明，急性乙醇给药相关剂量选择性抑制谷氨酸通过NMDA受体（NMDAR）的传输。此外，乙醇似乎对含有NR 2B（也称为GluN 2B）亚基的NMDAR的选择性更敏感。虽然急性乙醇后NMDAR功能受到抑制，但更多的慢性乙醇给药根据评估的区域增强或抑制谷氨酸传输。多项研究表明，乙醇对NMDAR的这些影响发生在延伸杏仁核（BNST和CeA）区域。在CeA，急性乙醇抑制NMDAR，而慢性乙醇处理增强这种抑制。此外，NR 2B拮抗剂能够阻断急性和慢性乙醇处理的这种乙醇诱导的抑制。在BNST中，急性乙醇抑制NMDAR反应，慢性乙醇暴露以NR 2B相关方式增强其功能。由于杏仁核的这些区域对于焦虑的调节至关重要，因此这些区域中谷氨酸传递的中断可能有助于乙醇戒断诱导焦虑的产生。评估NR 2B在乙醇作用中的特定作用的主要复杂性是NMDAR的复杂药理学。这些问题可以通过使用NR 2B的条件性和病毒敲除（KO）两者来规避。本提案将评价急性乙醇后抑制NMDAR功能和慢性治疗后增强/抑制NMDAR功能（目标1）中NR 2B（条件性和病毒性KO NR 2B）的需求。此外，这项工作将评估NR 2B亚基的作用，与条件和病毒科斯，在基础和戒断诱导焦虑从慢性乙醇暴露（目标2）。

Project Summary/Abstract: Alcoholism is known to be a chronic relapsing disorder. As alcohol use transitions to dependence, there is a shift in the motivational drive from being initially influenced by positive reinforcement (pleasurable effects from ethanol) to later reliance on negative reinforcement (withdrawal/negative affect from ethanol). One behavior that modulates relapse in dependent subjects during withdrawal is anxiety. Therefore, understanding the mechanisms that contribute to anxiety during withdrawal is critically important to the treatment of alcoholism. A region that is particularly involved in the modulation of anxiety and stress is the extended amygdala (bed nucleus of the stria terminalis; BNST and central nucleus of the amygdala; CeA).These nuclei have been shown to modulate responses to anxiogenic stimuli and stress- induced relapse to drug taking and, therefore, critical to the understanding of ethanol dependence. One neurotransmitter system present in the extended amygdala that is particularly susceptible to the effects of ethanol is glutamate. Multiple lines of evidence have illustrated that acute ethanol administration at pharmacologically relevant doses selectively inhibits glutamate transmission through the NMDA receptor (NMDAR). Further, ethanol also seems to be selectivity more sensitive to NMDARs that contain NR2B (also referred to as the GluN2B) subunit. While there is an inhibition of NMDAR function following acute ethanol, more chronic ethanol administrations either enhance or inhibit glutamate transmission depending on the region evaluated. Several studies have demonstrated that these effects of ethanol on NMDARs occur in regions of the extended amygdala (BNST and CeA). In the CeA, acute ethanol inhibited NMDARs, while chronic ethanol treatment enhanced this inhibition. Further, a NR2B antagonist was able to block this ethanol induced inhibition from acute and chronic ethanol treatment. In the BNST, acute ethanol inhibits NMDAR responses and chronic ethanol exposure enhances their function in an NR2B related manner. Since these regions of the extended amygdala are critical for the modulation of anxiety, it is possible the disrupted glutamate transmission in these regions could contribute to the production of ethanol withdrawal-induced anxiety. The major complication in evaluating the specific role of NR2B in ethanol's effects is the complex pharmacology of NMDARs. These problems can be circumvented with the use of both a conditional and viral knock-out (KO) of NR2B. This proposal will evaluate the requirement of NR2B (with conditional and viral KO of NR2B) in the inhibition of NMDAR function following acute ethanol and the enhancement/inhibition of NMDAR function following chronic treatment (Aim 1). Further, this work will assess the role of the NR2B subunit, with conditional and viral KOs, in basal and withdrawal induced anxiety from chronic ethanol exposure (Aim 2).