Chronic Ethanol Effects on CNS Opiate Receptors

慢性乙醇对中枢神经系统阿片受体的影响

基本信息

批准号：
6506027
负责人：
LINDA C SALAND
金额：
$ 7.5万
依托单位：
UNIVERSITY OF NEW MEXICO
依托单位国家：
美国
项目类别：
财政年份：
2002
资助国家：
美国
起止时间：
2002-08-01 至 2004-07-31
项目状态：
已结题

项目摘要

DESCRIPTION (provided by applicant): Chronic ethanol consumption and its continued reinforcement is an ongoing major health and societal problem. In the Central nervous system, the reinforcement of ethanol intake has been linked to enhanced release of endogenous opiates which act at opiate receptors. A non-selective opiate antagonist drug, naltrexone, is approved for humans to reduce ethanol consumption, craving and relapse. Use of the more selective delta receptor antagonist, naltriben, in animals and human trials, suggests that delta receptors are important in use and abuse of alcohol. However, mechanisms by which endogenous opiates and opiate receptors lead to continued ethanol consumption remain unclear. This proposal outlines the use of both histochemical and pharmacologic techniques to study mechanisms which may link chronic ethanol consumption to modulation of the delta opiate receptor, in a rat animal model. The major hypothesis to be tested is that immunoreactive delta opiate receptor expression in the forebrain and midbrain regions is increased during chronic ethanol intake, and the change in expression is accompanied by a reduction in functional coupling of the receptor to G proteins. Changes in delta receptor expression may affect neuronal intracellular signaling pathways in those brain areas to maintain ethanol consumption. Aim #1: To localize and quantify levels of delta opiate receptor subtype in the nucleus accumbens (NA) of the forebrain, and the midbrain ventral tegmental area (VTA), as well as other brain regions, in rats chronically exposed to ethanol. Confocal microscopy will be used, together with computer-assisted quantification, for immunofluorescent-labeled delta opiate receptors, with comparisons to mu receptor expression. We will compare neurons in brain areas of control and ethanol-consuming animals, and in animals which have been withdrawn from ethanol. Aim #2: To determine if chronic ethanol consumption affects functional coupling of delta receptors to second messenger systems in neurons of the NA and VTA, as well as other brain areas, with comparisons to mu receptor coupling. We will use a recently developed method with [35S]-GTPgammaS, whereby receptor-linked G-protein activation can be measured directly with autoradiographic techniques on sections of the brain areas. The direct effects of delta or mu opiate ligands can be examined to determine if they are functionally linked to G-proteins in the neurons of the selected brain areas. By using both quantitative immunohistochemical methods, and functional coupling studies, to examine the interactions of delta receptor ligands in animals after chronic ethanol consumption, it will be possible to determine receptor subtype-specific effects of chronic ethanol. It will also be possible to study the functional changes that may occur in the receptors after withdrawal from consumption. A future potential may be then to target delta receptors for treating chronic alcoholism.

描述（由申请人提供）：慢性乙醇消耗及其持续增强是一个持续的重大健康和社会问题。在中枢神经系统中，乙醇摄入的增强与在阿片受体作用的内源性鸦片释放的增强有关。一种非选择性的鸦片拮抗剂Naltrexone被批准用于减少乙醇消耗，渴望和复发。在动物和人类试验中，使用更有选择性的三角洲受体拮抗剂Naltriben表明，三角洲受体在使用和滥用酒精方面很重要。然而，内源性阿片类药物和阿片受体导致持续消耗的机制尚不清楚。该建议概述了在大鼠动物模型中使用组织化学和药理技术来研究机制，这些机制可能将慢性乙醇的消耗与调节的慢性乙醇消耗联系起来。要检验的主要假设是，在慢性乙醇摄入过程中，前脑和中脑区域中的免疫反应性三角洲鸦片受体表达增加，并且表达的变化伴随着受体与G蛋白的功能偶联的降低。增量受体表达的变化可能会影响这些大脑区域中神经元内信号通路以维持乙醇的消耗。目标＃1：在前脑的伏隔核（Na）中定位和量化Delta鸦片受体亚型的水平，中脑腹腹侧段区域（VTA）以及其他大脑区域以及其他大鼠在长期暴露于乙醇的大鼠中。共聚焦显微镜将与计算机辅助定量一起用于免疫荧光标记的三角洲鸦片受体，并与MU受体表达进行比较。我们将比较在控制和乙醇消耗动物的大脑区域以及已从乙醇中撤回的动物中的神经元。目标＃2：确定慢性乙醇消耗是否会影响Delta受体与NA和VTA神经元以及其他大脑区域的第二质体系统的功能耦合，并与MU受体耦合进行了比较。我们将使用[35S] -GTPGAMMAS的最近开发的方法，通过该方法，可以通过对大脑区域部分的放射自显影技术直接测量受体连接的G蛋白激活。可以检查三角洲或omu鸦片配体的直接作用，以确定它们是否在选定大脑区域的神经元中与G蛋白具有功能相关。通过使用两种定量免疫组织化学方法和功能耦合研究，以检查慢性乙醇消耗后动物中三角体受体配体的相互作用，可以确定可以确定慢性乙醇的受体亚型特异性作用。还可以研究退出消耗后受体可能发生的功能变化。那么，未来的潜力可能是针对三角洲受体来治疗慢性酒精中毒的。