Molecular Changes in Mesolimbic Dopamine Signaling with Psychostimulants

药物成瘾是美国的一个主要健康问题，尽管我们对成瘾的神经化学变化的理解有了重大进展，但仍需要开发新的方法并确定新的靶点，以阐明药物成瘾的分子基础。在这个R21的建议，这一基本需求将通过整合小鼠行为模型的精神兴奋剂成瘾与电生理，分子和细胞技术，以调查两种新的蛋白质参与精神兴奋剂成瘾，G蛋白门控钾（GIRK）通道和排序连接蛋白27（SNX27）的作用。GIRK通道先前已经涉及中脑边缘多巴胺途径中的药物功效。SNX27已被证明与GIRK通道直接相关，导致质膜上通道的下调。在甲基苯丙胺致敏小鼠腹侧被盖区（VTA）多巴胺神经元中，GABAB受体激活GIRK通道介导的抑制是否减少仍然是一个重要的未回答的问题。此外，尚不清楚刺激剂诱导的SNX27增加是否发生在对甲基苯丙胺致敏的小鼠的VTA中，这可能参与GIRK通道的下调。为了解决这些问题，（1）将在对照和甲基苯丙胺致敏小鼠中测量腹侧被盖区多巴胺神经元中的GIRK通道电流，以及（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通道在精神兴奋剂成瘾模型中的潜在相互作用有可能加强与药物成瘾相关的健康研究。目前用于成瘾的药物治疗未能解决成瘾的根本原因，并且缺乏目前的药理学治疗。确定成瘾中的关键蛋白质和神经回路的变化可能会导致开发治疗成瘾的新药物疗法。本提案中提出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，直接有益于人类健康。公共卫生相关性：大脑药物奖励中心的神经元连接随着长期使用药物而改变，导致成瘾和依赖。这项资助的目的是了解更多关于长期使用甲基苯丙胺改变了哪些蛋白质，并探索钾通道信号是否改变。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.