Cocaine-induced adaptations in inhibitory signaling in VTA dopamine neurons

 描述（由申请人提供）：药物成瘾是一种慢性复发性疾病，影响美国2000多万人，其定义为强迫寻求和服用药物。我们成功治疗成瘾的能力受到我们对潜在生物机制的有限知识的阻碍。我们实验室工作的一个长期目标是更好地了解与成瘾有关的关键神经元群体中药物诱导适应的机制和相关性。为此，我们最近描述了一个短暂的可卡因诱导的抑制G蛋白依赖性抑制信号的多巴胺（DA）神经元的腹侧被盖区（VTA），在mesocorticolimbic系统的关键元素。这种新的可卡因诱导的适应需要激活D2/3 DA受体（D2/3R），并涉及G蛋白门控内向整流K（GIRK/Kir 3）+通道的内化，这是抑制性反馈途径的关键因素，通常在中皮质边缘系统中调节DA神经传递。我的项目的主要目标是更好地了解可卡因诱导的VTA DA神经元中GIRK依赖性信号转导抑制的机制和神经生理学影响（AIM 1），并确定DA神经元中GIRK通道操纵对可卡因诱导的奖励相关行为的影响（AIM 2）。我的工作假设是可卡因诱导的腹侧被盖区细胞外DA水平的增加导致腹侧被盖区DA神经元的急性D2 R和GIRK依赖性抑制，以及随后在这种细胞类型中发现的独特GIRK通道（GIRK 2/GIRK 3异聚体）的内化。可卡因诱导的VTA DA神经元中GIRK依赖性信号传导的抑制随后促进了随后药物暴露的DA传递增强，以及促进和支持成瘾相关行为的长期适应的发展。我建议使用跨学科的方法，包括脑切片电生理学，体外快速扫描循环伏安法和行为分析，与药理学和神经元特异性遗传操作的GIRK依赖性信号在小鼠中测试这个工作假设的关键要素。该项目的成功完成将扩大我们对药物成瘾基础的抑制性细胞信号传导机制的理解，并将对GIRK通道操纵用于治疗或预防成瘾的潜在效用进行初步评估。

 DESCRIPTION (provided by applicant): Drug addiction is a chronically relapsing disorder affecting more than 20 million people in the United States and is defined by compulsion to seek and take drug. Our ability to successfully treat addiction is hindered by our limited knowledge of the underlying biological mechanisms. A long-term goal of work in our lab is to better understand the mechanisms and relevance underlying drug-induced adaptations in key neuron populations implicated in addiction. Toward this end, we recently described a transient cocaine-induced suppression of G protein-dependent inhibitory signaling in dopamine (DA) neurons of the ventral tegmental area (VTA), a key element in the mesocorticolimbic system. This novel cocaine-induced adaptation required activation of D2/3 DA receptors (D2/3R) and involved the internalization of G protein-gated inwardly rectifying K (GIRK/Kir3) + channels, a key contributor to inhibitory feedback pathways that normally temper DA neurotransmission in the mesocorticolimbic system. The key goals of my project are to better understand the mechanisms and neurophysiological impact underlying the cocaine-induced suppression of GIRK-dependent signaling in VTA DA neurons (AIM 1), and to determine the impact of GIRK channel manipulation in DA neurons to cocaine- induced reward-related behavior (AIM 2). My working hypothesis is that the cocaine-induced increase in extracellular DA levels in the VTA leads to the acute D2R- and GIRK-dependent inhibition of VTA DA neurons, and subsequent internalization of the unique GIRK channel (GIRK2/GIRK3 heteromer) found in this cell type. The cocaine-induced suppression of GIRK-dependent signaling in VTA DA neurons then facilitates enhanced DA transmission with subsequent drug exposure, and the development of long-term adaptations that promote and support addiction-related behaviors. I propose to test key elements of this working hypothesis using an interdisciplinary approach including brain slice electrophysiology, in vitro fast scan cyclic voltammetry, and behavioral analysis, in tandem with pharmacologic and neuron-specific genetic manipulations of GIRK- dependent signaling in mice. Successful completion of this project will expand our understanding of inhibitory cell signaling mechanisms that underlie drug addiction and will provide an initial assessment of the potential utility of GIRK channel manipulation for the treatment or prevention of addiction.