The Role of BK Channel Composition in Alcohol Tolerance and Consumption

描述（由申请人提供）：行为耐受性是暴露于大多数滥用药物的标志。其特征在于随着时间的推移药物作用降低，通过改变药物的代谢，或功能性地，尽管浓度不变，但药物的作用降低。事实上，人类急性行为耐受性的增强可以作为未来酗酒可能性的标志。大电导钾离子通道（BK）已越来越多地被认为是酒精作用的重要靶点，无论是在药物的致醉作用中，还是在对药物的适应（耐受性）中。该提议基于令人兴奋的新数据，该数据将BK通道β 4亚基鉴定为酒精耐受性和消耗的重要介质，并提供了一种动物模型来检查分子和行为耐受性与消耗之间的关系。我们将利用基因工程小鼠，其中β 4亚基存在或“敲除”。在目标1中，我们检验了BK β 4通过涉及激酶和相关信号通路的机制影响急性耐受的假设。电生理学实验将探讨激酶在BK急性耐受性表达系统和纹状体神经元中的作用，这在药物奖励和成瘾中很重要。在目标2中，我们测试了假设（基于初步数据），即β 4对快速耐受的影响不会像急性耐受那样明显。这些研究将利用电生理学、分子生物学和成像技术，并将在分子、细胞和行为水平上进行探索。目标2将包括对β 4在发现中的作用的研究，在我们的初步数据中描述了纹状体神经元中，有一个“开关”，在酒精暴露3至6小时后被激活，这从根本上改变了酒精戒断后耐受的持续时间。这对酒精依赖的发展有影响，因为它是饮酒习惯的一个功能。最后，在目标3中，我们检验了beta4对酒精消费的影响将反映对行为参数（如酒精偏好和奖励）的影响的假设，这两个参数都已知会影响消费。将使用“在黑暗中饮用”（DID）范例的两瓶选择变体来测量β 4 KO和WT小鼠中乙醇相对于水的偏好。此外，我们将使用条件性位置偏好（CPP）试验测量WT和β 4 KO小鼠中乙醇的奖励特性。总之，这些实验将有助于确定β 4亚基和急性耐受性在饮酒动机行为中的作用。 公共卫生相关性：酗酒是公共卫生竞技场中最重要的问题之一。酒精使用后产生的耐受性可能与药物依赖和成瘾的发展有关。在这项提案中，我们追求令人兴奋的新数据，这些数据表明BK通道β 4亚基蛋白在控制酒精耐受性和消费中的作用。

DESCRIPTION (provided by applicant): Behavioral tolerance is a hallmark of exposure to most drugs of abuse. It is characterized by reduced drug effects over time, either via altered metabolism of the drug, or functionally, whereby the effects of the drug decrease in spite of unaltered concentration. Indeed, the presence of enhanced acute behavioral tolerance in humans can serve as a marker for the likelihood of a future development of alcoholism. The large conductance potassium ion channel (BK) has become increasingly recognized as an important target of alcohol action, both in the intoxicating actions of the drug, as well as in adaptation to the drug (tolerance). This proposal is based upon exciting new data which identifies the BK channel beta4 subunit as an important mediator of alcohol tolerance and consumption, and provides an animal model to examine the relationship between molecular and behavioral tolerance, and consumption. We will make use of genetically engineered mice, in which the beta4 subunit is either present or "knocked out". In Aim 1, we test the hypothesis that BK beta4 influences acute tolerance via a mechanism involving kinases and associated signaling pathways. Electrophysiological experiments will probe the role of kinases in BK acute tolerance in expression systems and in neurons of the striatum, which is important in drug reward and addiction. In Aim 2, we test the hypothesis (based upon preliminary data) that beta4's influence on rapid tolerance will not be as pronounced as in acute tolerance. These studies will utilize electrophysiological, molecular biology, and imaging techniques, and will probe at the molecular, cellular, and behavioral levels. Aim 2 will include studies on the role of beta4 in the finding, described in our preliminary data that in striatal neurons, there is a "switch" which is activated after 3 to 6 hrs of alcohol exposure, which radically changes the duration of tolerance after alcohol withdrawal. This has implications for the development of alcohol dependency as a function of drinking habits. Finally, in Aim 3, we test the hypothesis that beta4's influence on alcohol consumption will reflect influences on behavioral parameters such as alcohol preference and reward, both known to influence consumption. A two bottle choice variant of the "drinking in the dark" (DID) paradigm will be utilized to measure ethanol vs. water preference in beta4 KO and WT mice. In addition, we will measure the rewarding properties of ethanol in WT and beta4 KO mice using a conditioned place preference (CPP) assay. Together, these experiments will help identify the role of the beta4 subunit and acute tolerance in motivational behaviors underlying alcohol consumption. PUBLIC HEALTH RELEVANCE: Alcoholism represents one of the most important problems in the public health arena. Tolerance, which develops with alcohol use, may be related to the development of drug dependency and addiction. In this proposal, we pursue exciting new data which indicates a role for the BK channel beta4 subunit protein in the control of alcohol tolerance and consumption.