Molecular Changes in Mesolimbic Dopamine Signaling with Psychostimulants

描述(申请人提供)：吸毒成瘾是美国的一个主要健康问题。尽管我们在了解成瘾的神经化学变化方面取得了重大进展，但仍有必要开发新的方法和确定新的靶点，以阐明吸毒成瘾的分子基础。在这份R21提案中，这一基本需求将通过将心理刺激成瘾的小鼠行为模型与电生理学、分子和细胞技术相结合来研究与心理刺激成瘾有关的两种新蛋白-G蛋白门控钾通道(GIRK)和分类连接蛋白27(SNX27)-的作用。GIRK通道此前已被认为与中脑边缘多巴胺通路的药效有关。SNX27被证明直接与GIRK通道结合，导致质膜上通道的下调。甲基苯丙胺致敏的小鼠腹侧被盖区(VTA)的多巴胺能神经元是否减轻了GABAB受体激活GIRK通道的抑制作用仍是一个重要的未解之谜。此外，目前尚不清楚兴奋剂诱导的SNX27的增加是否发生在对甲基苯丙胺敏感的小鼠的VTA中，这可能与GIRK通道的下调有关。为了解决这些问题，(1)将在对照组和甲基苯丙胺敏感的小鼠中测量VTA的多巴胺神经元中的GIRK通道电流，(2)免疫组织化学研究将确定蛋白质水平是否发生变化。SNX27与GIRK通道在心理刺激成瘾模型中的潜在相互作用有可能加强与健康相关的药物成瘾研究。目前的成瘾药物治疗未能解决成瘾的根本原因，目前缺乏药物治疗。识别成瘾中的关键蛋白质和神经回路的变化可能会导致治疗成瘾的新药物疗法的发展。这项提议中提议的工作将提供一个直接的分子药物靶点来治疗根本原因，而不是成瘾的症状，直接造福于人类健康。与公共健康相关：随着长期使用药物，大脑药物奖励中心的神经元连接发生变化，导致成瘾和依赖。这项资助的目标是更多地了解长期使用甲基苯丙胺会改变哪些蛋白质，并探索钾通道信号是否会改变。这些实验的结果可能有助于确定治疗药物成瘾的新治疗策略。

DESCRIPTION (provided by applicant): Drug addiction is a major health problem in the U.S. Although there have been significant advances in our understanding the neurochemical changes in addiction, there is a need to develop new approaches and to identify novel targets for elucidating the molecular underpinnings of drug addiction. In this R21 proposal, this fundamental need will be addressed by integrating a mouse behavioral model for psychostimulant addiction with electrophysiological, molecular and cellular techniques to investigate the role of two novel proteins implicated in psychostimulant addiction, G protein-gated potassium (GIRK) channels and sorting nexin 27 (SNX27). GIRK channels have been implicated previously in drug efficacy in the mesolimbic dopamine pathway. SNX27 has been shown to associate directly with GIRK channels, leading to down-regulation of channels on the plasma membrane. Whether inhibition mediated by GABAB receptor activation of GIRK channels is reduced in dopamine neurons of the ventral tegmental area (VTA) from mice sensitized to methamphetamine remains an important unanswered question. Furthermore, it is unknown if a stimulant-induced increase in SNX27, which could be involved in the down-regulation of GIRK channels, occurs in the VTA of mice sensitized to methamphetamine. To address these, (1) GIRK channel currents in the dopamine neurons of the VTA will be measured in control and methamphetamine-sensitized mice, and (2) immunohistochemical studies will determine whether changes in protein levels occur. The potential interaction of SNX27 with GIRK channels in a model of psychostimulant addiction has the potential to enhance health-related research on drug addiction. Current drug treatments for addiction fail to address the underlying causes of addiction and current pharmacological treatments are lacking. Identifying key proteins and changes in neural circuitry in addiction could lead to the development of novel pharmacological therapies for treating addiction. The proposed work in this proposal will provide a direct molecular pharmaceutical target to treat the underlying cause, rather than the symptoms of addiction, directly benefiting human health. PUBLIC HEALTH RELEVANCE: Neuronal connections in the drug reward center of the brain change with chronic use of drugs, leading to addiction and dependence. The goal of this grant is to learn more about which proteins are changed by chronic use of methamphetamines and to also explore whether potassium channel signaling is altered. Results from these experiments may help identify novel therapeutic strategies for treating drug addiction.