Modulation of Plasticity and Alcohol Preference by GRs within the BNST and CeA

描述（由申请人提供）：酗酒是一种毁灭性的、代价高昂的疾病，在美国大约每12个成年人中就有一个受到它的折磨。这种疾病最有害的方面之一是复发率极高，根据依赖个体寻求的治疗形式，复发率在50-90%之间。因此，旨在预防复发的研究是减轻酒精中毒的重中之重。压力是依赖个体复发的最常见原因，而且足以导致人类和啮齿动物对酒精的渴望和寻求。压力经历或戒酒激活下丘脑垂体肾上腺轴（HPA）并导致糖皮质激素（人类的皮质醇和啮齿动物的皮质酮，CORT）的释放。高水平的CORT结合并激活大脑和外周的糖皮质激素受体（gr），然后作为转录因子启动或抑制大量应激反应基因的转录，并通过假定的膜分隔机制起作用。研究表明，酒精摄入和戒断均诱导CORT的释放和随后GRs的激活，并且酒精戒断后CORT的释放量与戒断症状的严重程度成正比。GR的药理激活也被证明可以增加对酒精的偏好，而GR拮抗剂可以降低对酒精的偏好。因此，GRs在戒断-复发循环中可能是一把双刃剑，它既是与戒断相关的负面影响的调解者，也是戒断期间酒精渴望的关键参与者。然而，尽管系统性GR激活在酒精偏好和戒断中的重要性是显而易见的，但GR在大脑中起作用的具体回路却远不清楚。杏仁核中央核（CeA）和终纹床核（BNST）是高表达GRs的两个大脑区域，它们在酒精戒断行为和应激源后的酒精寻求复发中起关键作用。我们的实验室和其他人已经表明，CeA和BNST有助于对压力的情感反应。这些区域对于应激诱导的酒精寻求恢复至关重要，而针对CeA的GR拮抗剂会减弱恢复。GRs也因其改变神经元兴奋性和可塑性的能力而闻名。我们的实验室通过对长期增强（LTP）诱导的研究表明，压力和酒精管理能够改变BNST内的突触可塑性。我们已经证明，CORT的反复系统性激活改变了BNST中LTP的诱导，可能是通过该区域内的gr。在本研究中，CeA和BNST GRs在酒精偏好、戒断焦虑和LTP诱导中的作用，以及酒精给药后的LTP诱导，将通过结合使用含有固定GR基因的小鼠和慢病毒crer -重组酶的区域递送，在这些区域中特异性地缺失GR来研究。

DESCRIPTION (provided by applicant): Alcoholism is a devastating and costly disease that afflicts approximately one out of every twelve adults in the United States. One of the most pernicious aspects of this disease is the extremely high relapse rate ranging from 50-90%, depending on the form of treatment a dependent individual seeks. Thus, research aimed at the prevention of relapse is of high priority in the alleviation of alcoholism. Stress is the most commonly cited reason for relapse in dependent individuals, and is sufficient to cause alcohol craving and seeking in humans and rodents. A stressful experience or withdrawal from alcohol activates the hypothalamic pituitary adrenal (HPA) axis and leads to the release of glucocorticoids (cortisol in humans and corticosterone in rodents, CORT). The high levels of CORT bind to and activate glucocorticoid receptors (GRs) in the brain and periphery, which then act as transcription factors to initiate or repress the transcription of a large number of stress-responsive genes as well as acting through putative membrane-delimited mechanisms. It has been shown that alcohol consumption and withdrawal both induce the release of CORT and subsequent activation of GRs, and the amount of CORT release following alcohol withdrawal is directly proportional to the severity of withdrawal symptoms. Pharmacological activation of GRs has also been demonstrated to increase preference for alcohol while GR antagonists decrease alcohol preference. Thus, GRs may act as a double-edged sword in the withdrawal-relapse cycle by serving as mediators of the negative affect associated with withdrawal as well being key players in alcohol craving during withdrawal. However, while the importance of systemic GR activation in alcohol preference and withdrawal are apparent, the specific circuitry through which GR is acting in the brain is far less clear. Two brain regions that highly express GRs and are critically involved in alcohol withdrawal behavior and relapse to alcohol seeking following a stressor are the central nucleus of the amygdala (CeA) and the bed nucleus of the stria terminalis (BNST). Our lab and others have shown that the CeA and the BNST contribute to affective responses to stress. These areas are crucial for stress-induced reinstatement of alcohol seeking, and GR antagonist directed at the CeA blunts reinstatement. GRs are also well known for their ability to alter neuronal excitability and plasticity. Our lab has demonstrated tha stress and alcohol administration are capable of altering synaptic plasticity within the BNST through the examination of long-term potentiation (LTP) induction. We have shown that repeated systemic activation of CORT alters the induction of LTP in the BNST, potentially through GRs within the region. In this proposal, the role of CeA and BNST GRs on alcohol preference, withdrawal anxiety, and LTP induction basally and following alcohol administration will be examined through specific genetic deletion of GR within each of these regions through combined use of mice harboring a floxed GR gene and regional delivery of lentiviral Cre-recombinase.