Methamphetamine regulates the dopamine transporter via an intracellular mechanism

 描述（由申请人提供）：甲基苯丙胺滥用是一个主要的公共卫生问题，没有有效的治疗策略或FDA批准的药物治疗。甲基苯丙胺成瘾被认为是一种慢性疾病，其根源在于这种精神兴奋剂引起的许多神经生物学适应。可以说，治疗甲基苯丙胺滥用的最大希望在于确定这些神经元适应的潜在分子机制，以产生开发靶向治疗的机会。这项工作的长期目标是确定这些潜在的分子机制。多巴胺转运蛋白（DAT）是精神兴奋剂（如甲基苯丙胺和可卡因）的主要靶点。通过抑制多巴胺转运蛋白的摄取，这些药物能够增加细胞外多巴胺浓度，从而调节多巴胺相关行为。然而，通常不被认识到的是，甲基苯丙胺是多巴胺转运蛋白的底物，也是sigma 1受体（sigma 1 R）的高亲和力配体，sigma 1 R是一种细胞内伴侣蛋白。我们的初步研究结果表明：1）sigma 1 R在中脑多巴胺能神经元的索马和树突中表达，2）sigma 1 R与DAT共定位并相互作用，3）sigma 1 R激动剂或甲基苯丙胺均可增加DAT/sigma 1 R的共定位和相互作用。和4）共同施用σ 1 R激动剂影响多巴胺摄取、多巴胺流出和多巴胺能神经元的兴奋性的甲基苯丙胺调节。在这个应用程序中，我们将测试的总体假设，甲基苯丙胺多巴胺转运蛋白功能的调节部分依赖于甲基苯丙胺诱导的增加sigma 1 R/DAT相互作用及其功能的后果。我们将集中于确定DAT/sigma 1 R相互作用的机制（目标1），DAT/sigma 1 R相互作用的细胞定位（目标2），以及这种相互作用的功能后果（目标3）。如果像我们假设的那样，与sigma 1 R的相互作用代表了介导甲基苯丙胺调节DAT的主要细胞内机制，那么我们将确定一个治疗甲基苯丙胺成瘾和其他涉及多巴胺神经传递失调的精神疾病的可能靶点。

 DESCRIPTION (provided by applicant): Methamphetamine abuse is a major public health problem with no effective treatment strategies or FDA-approved pharmacotherapies. Methamphetamine addiction is thought to be a chronic disease rooted in numerous neurobiological adaptations induced by this psychostimulant. Arguably, the greatest promise for the treatment of methamphetamine abuse lies in determining the underlying molecular mechanisms of these neuronal adaptations to generate the opportunity of developing targeted therapies. The long-term goal of this work is to identify these underlying molecular mechanisms. The dopamine transporter (DAT) is the primary target for psychostimulants such as methamphetamine and cocaine. By inhibiting dopamine transporter uptake, these drugs are able to increase extracellular dopamine concentration, which modulates dopamine-associated behaviors. However, what is not often recognized is that methamphetamine is a substrate for the dopamine transporter and a high affinity ligand at the sigma-1 receptor (sigma1R), an intracellular chaperon protein. Our preliminary data suggest that: 1) the sigma1R is expressed in the soma and dendrites of midbrain dopaminergic neurons; 2) the sigma1R is co-localized and interacts with the DAT; 3) the administration of either a sigma1R agonist or methamphetamine increases the co-localization and interaction of DAT/sigma1R; and 4) co-administration of a sigma1R agonist influences methamphetamine-regulation of dopamine uptake, dopamine efflux, and the excitability of dopaminergic neurons. In this application we will test the overarching hypothesis that methamphetamine regulation of dopamine transporter function relies in part on methamphetamine-induced increases in sigma1R/DAT interactions and their functional consequences. We will focus on determining the mechanism of DAT/sigma1R interaction (how Aim1), the cellular localization of DAT/sigma1R interaction (where, Aim 2), and the functional consequence of this interaction (what, Aim 3). If, as we postulate, the interaction with the sigma1R represents a main intracellular mechanism for mediating methamphetamine-regulation of DAT, then we will have identified a possible target for treating methamphetamine addiction and other psychiatric diseases involving dysregulation of dopamine neurotransmission.