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

描述(由申请人提供)：酒精中毒是一种毁灭性的、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影响。这种疾病最有害的方面之一是极高的复发率，从50%到90%不等，这取决于依赖的个人寻求的治疗形式。因此，旨在预防复发的研究在减轻酒精中毒方面是高度优先的。压力是依赖者复发的最常见原因，足以导致人类和啮齿动物对酒精的渴望和寻求。紧张的经历或戒酒会激活下丘脑-垂体-肾上腺(HPA)轴，并导致糖皮质激素(人类的皮质醇和啮齿类动物的皮质酮，CORT)的释放。高水平的皮质醇结合并激活大脑和外周的糖皮质激素受体，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发挥作用。已有研究表明，饮酒和戒断均可诱导皮质醇释放和随后的GRs激活，且戒断后皮质醇释放量与戒断症状的严重程度成正比。GRS的药理激活也被证明增加了对酒精的偏好，而GR拮抗剂则降低了酒精偏好。因此，GRs在戒断-复发循环中可能是一把双刃剑，既是戒酒过程中与戒酒相关的负面影响的中介，也是戒酒过程中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在大脑中起作用的特定电路远不清楚。大脑中两个高表达GRs的区域是杏仁中央核(CEA)和终纹床核(BNST)，它们与戒酒行为和应激源后的酒精复吸密切相关。我们的实验室和其他人已经证明，CEA和BNST有助于对压力做出情感反应。这些区域对于压力诱导的酒精寻求的恢复至关重要，而针对CEA的GR拮抗剂使恢复变得迟钝。GRs也因其改变神经元兴奋性和可塑性的能力而广为人知。我们的实验室通过对长时程增强(LTP)诱导的检测，证明了应激和酒精处理能够改变BNST内的突触可塑性。我们已经证明，皮质醇的重复系统激活改变了BNST中LTP的诱导，可能是通过该区域内的GRs。在这项建议中，CEA和BNST GRs在酒精偏好、戒断焦虑和酒精注射后LTP诱导中的作用将通过联合使用携带Floted GR基因的小鼠和区域递送慢病毒Cre重组酶的小鼠来检验这些区域内GR的特异性基因缺失。

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.