Mechanisms of Estrogen Action in Enhancing Behavioral Responses to Cocaine

描述(由申请者提供)：女性对可卡因上瘾的速度更快，性激素雌激素被认为通过增强可卡因的行为效应而促进了这一过程。这个项目的目标是在分子水平上了解雌激素如何增加对可卡因的行为反应。这项建议中概述的方法是使用与可卡因成瘾有关的两种行为指标-条件性位置偏爱和敏化来研究雌性小鼠雌激素受体和相关信号分子的功能。雌激素受体作用于细胞核，调节基因表达。两种类型的核雌激素受体ER和ER在控制与可卡因成瘾相关的行为的大脑区域中表达。然而，目前尚不清楚这些雌激素受体或其靶基因中的哪一个能增强对可卡因的行为反应。第一组实验的目标是利用特定的激活剂或抑制RNA，确定促进可卡因行为反应的雌激素受体类型。第二个目标中提出的实验将测试一个候选的雌激素调节基因alk是否通过使用一种ALK蛋白活性的小分子抑制剂来中介雌激素在增加可卡因敏感性和条件性位置偏爱方面的作用。最后一组拟议的实验将详细研究ER和相关的转录调节蛋白LMO4调控神经元ALK基因表达的分子机制，方法是测试这些蛋白在雌激素存在和不存在的情况下与ALK启动子的结合。这些研究将为深入了解大脑中受雌激素调控的与可卡因成瘾相关的行为相关的新分子途径提供洞察力。此外，ALK基因编码一种受体酪氨酸激酶，可用于药物开发。更好地了解雌激素靶基因及其在大脑中调控的分子机制将导致更好的策略，以区别对待女性和男性的可卡因成瘾。

DESCRIPTION (provided by applicant): Females progress more rapidly to cocaine addiction and the sex hormone estrogen is thought to contribute to this process by enhancing the behavioral effects of cocaine. The goal of this project is to understand on a molecular level how estrogen increases behavioral responses to cocaine. The approach outlined in this proposal is to study the function of estrogen receptors and associated signaling molecules in female mice using two behavioral measures related to cocaine addiction, conditioned place preference and sensitization. Estrogen receptors act in the nucleus of cells to regulate gene expression. Two types of nuclear estrogen receptors, ER¿ and ¿, are expressed in brain regions that control behaviors related to cocaine addiction. However, it is currently not known which of these estrogen receptors or their target genes enhances behavioral responses to cocaine. The goal of the first set of experiments is to determine the estrogen receptor type that promotes behavioral responses to cocaine, using specific activators or inhibitory RNAs. The experiments proposed in the second aim will test if a candidate estrogen-regulated gene, Alk, mediates the effect of estrogen in increasing cocaine sensitization and conditioned place preference, by using a small-molecule inhibitor of ALK protein activity. The last set of proposed experiments will examine in detail the molecular mechanisms of regulation of Alk gene expression in neurons by ER¿ and the associated transcriptional regulatory protein LMO4, by testing binding of these proteins at the Alk promoter in the presence and absence of estrogen. These studies will provide insight into a new molecular pathway in the brain regulated by estrogen that is relevant to behaviors related to cocaine addiction. Moreover, the Alk gene encodes a receptor tyrosine kinase that is amenable to drug development. A greater understanding of estrogen target genes and the molecular mechanisms of their regulation in the brain will lead to better strategies for differentially treating cocaine addiction in women and men.