Kir 3 Channel Subunits in Drug Abuse with GABAB Agonists

我们建议研究日益流行的特制药物--羟基丁酸的急性作用。 (GHb)腹侧被盖区神经元(中脑边缘多巴胺系统)。GHB的作用是 通过GABAB类型的G蛋白偶联受体(GPCRs)介导，激活下游效应器， 如G蛋白门控的内向整流钾(Kir3或GIRK)通道。我们假设具体的 GIRK通道组合在介导GABAg受体急性奖赏效应中的主要作用 中脑边缘多巴胺系统的激动剂。我们将(1)阐明G蛋白信号转导的调节作用 (2)评价GIRK通道的作用 亚基(GIRK1、GIRK2和GIRK3)对GABAB受体偶联效率的影响 VTA的GABA神经元，以及(3)决定VTA的单通道特性和组装规则 VTA中的异构体GIRK通道。我们将使用双管齐下的方法--系统级别的方法 涉及膜片钳记录和双光子成像的急性脑片来自野生型，GIRK- 以及一种细胞方法，涉及膜片钳记录和先进的 异种细胞和培养神经元中表达的GIRK通道的成像技术 VTA。总之，这些研究将揭示GIRK通道背后的细胞和分子事件 并阐明GIRK通道在脑内的作用。 确定GHB及相关药物在大脑中的疗效。 与公共卫生相关。毒品滥用是美国和世界范围内的问题，影响着数百万人。毒品问题 滥用会带来强烈的奖赏感，这可能会导致重复服药、依赖和 上瘾。上瘾的特征是对无法控制的渴望做出反应而复发。最初的回报 影响和欲望都与中脑边缘多巴胺系统的激活有关。这个 在过去的几年里，滥用羟基丁酸的情况急剧增加。通过解开GIRK通道在 调节GHB的作用，我们可能揭示直接激活这些通道的新药的靶点或 将耦合效率改为GPCRs。这种方法可能会将GIRK通道建立为强大的药物 治疗成瘾的靶点。

We propose to study the acute effects of the increasingly popular designer drug gamma-hydroxy butyric acid (GHB) on neurons in the ventral tegmental area (mesolimbic dopamine system). The actions of GHB are mediated through G protein-coupled receptors (GPCRs)of the GABAB type, activating downstream effectors, such as G protein-gated inwardly rectifying potassium (Kir3 or GIRK) channels. We hypothesize that specific combinations of GIRK channels play a primary role in mediating acute rewarding effects of GABAg receptor agonists on mesolimbic dopamine system. We will (1) elucidate the role of regulator of G-protein signaling (RGS) proteins in modulating the coupling efficiency of GABAB receptors, (2) asses the role of GIRK channel subunits (GIRK1, GIRK2, and GIRK3) on setting the coupling efficiency of GABAB receptors in dopamine and GABA neurons of the VTA, and (3) determine single-channel properties and rules of assembly of heteromeric GIRK channels in the VTA. We will use a two-pronged approach ¿ a systems level approach involving patch-clamp recordings and two-photon imaging in acute brain slices from wild-type, GIRK- deficient, and transgenic mice; and a cellular approach, involving patch-clamp recordings and advanced imaging techniques from GIRK channels expressed in heterologous cells and in cultured neurons of the VTA. Together, these studies will reveal the cellular and molecular events underlying GIRK channel assembly and coupling to GABAs receptors in the brain, as well as elucidate the role of GIRK channels in determining the efficacy of GHB and related drugs in the brain. Public health relevance. Drug abuse is a USand world-wide problem affecting millions of people. Drugs of abuse impart strong sensations of reward, which may lead to repetitive drug administration, dependence and addiction. Addiction is characterized by relapse in response to uncontrollable cravings. The initial rewarding effects as well as the cravings are associated with the activation of the mesolimbic dopamine system. The abuse of GHB has increased dramatically over the last few years. By unraveling the role of GIRK channels in mediating GHB actions, we may reveal targets for new drugs that either directly activate these channels or alter the coupling efficiency to GPCRs. Such an approach may establish GIRK channels as formidable drug targets for treating addiction.