Alcohol disrupts the balance between dopamine and GABA co-released by midbrain dopamine neurons

项目总结： 明显的神经适应是酒精使用障碍的结果，这是虚弱健康的基础 与疾病相关的风险和社会问题。而γ-氨基丁酸能、谷氨酸能和 多巴胺能神经传递被强烈地牵连，这是导致 酒精摄入量和偏好的易感性增加还不是很清楚。因此，当前 与酒精中毒作斗争的治疗方法很少，而且没有特效性--除了心理治疗、戒毒 以及引起恶心、呕吐的药物，目前还没有治疗这种疾病的药理靶点。近期 研究发现乙醛脱氢酶1a1介导的非典型GABA合成 (ALDH1A1)和多巴胺能中脑神经元的共同释放，我们收集了强有力的证据 这表明这种替代的GABA合成途径随着血液中酒精水平的降低而减弱 与酗酒有关。方法学的进步现在提供了直接检查和 剖析这种GABA途径在急性和慢性酒精暴露中的作用。在这个提案中，我们假设 中脑多巴胺神经元共同释放的多巴胺和GABA之间的平衡对 突触后纹状体棘投射神经元(SPN)。此外，酒精和/或其代谢产物抑制 多巴胺能GABA通过损害GABA的非正则合成，最终扰乱共同释放的GABA 通过背侧纹状体中的多巴胺神经元，并导致酒精摄入量和 偏好。我们将利用转基因小鼠和病毒注射直接检查 多巴胺神经元和参与GABA合成、调制和释放的特定通路。通过 纹状体和全细胞膜片钳识别原理中多巴胺终末的光发生激活 纹状体细胞，我们的实验将提供高分辨率的多巴胺能功能的评估 GABA能在正常和增加酒精摄入量和偏爱条件下。与成像相结合， 电生理学、光遗传学、生物化学和行为分析，这一提议提供了一种独特的、多学科的 小平面方法研究多巴胺和GABA在基底节的共同释放及其机制 长期酗酒会改变这种形式的神经递质释放。 基于我们令人信服的初步发现，我们的目标是1)检查细胞类型特定的缺失 多巴胺神经元中ALDH1A1的表达导致酒精偏好增强；2)精确定位其机制 酒精对共释放的GABA的抑制作用；3)研究酒精对脑功能的调节 纹状体中GABA和多巴胺之间的相互作用。我们的新的初步发现和在 这笔赠款将填补我们在多巴胺能神经元中合成GABA方面的知识空白，并创造一个 了解酒精摄入量增加和酒精摄入增加背后的突触机制的新窗口 偏好，为治疗或预防酒精使用障碍提供更好的工具和更早的目标。

Project Summary: Clear neuroadaptations occur as a result of alcohol use disorders, underlying the debilitating health risks and social problems associated with the disease. While changes in GABAergic, glutamatergic and dopaminergic neurotransmission are strongly implicated, the precise neurological mechanisms that cause enhanced susceptibility of alcohol intake and preference are not yet well understood. As a result, current treatments available to combat alcoholism are sparse and nonspecific— besides psychotherapy, detoxification and nausea-inducing, emetic drugs, there are no pharmacological targets for treating the disease. Recent studies have uncovered non-canonical GABA synthesis mediated by aldehyde dehydrogenase 1a1 (ALDH1a1) and co-release from dopaminergic midbrain neurons, and we have gathered strong evidence suggesting that this alternative GABA synthesis pathway is diminished with blood alcohol levels that are associated with binge drinking. Methodological advances now provide the opportunity to directly examine and dissect the role of this GABA pathway in acute and chronic alcohol exposure. In this proposal, we hypothesize that the balance between co-released dopamine and GABA by midbrain dopamine neurons is critical for postsynaptic striatal spiny projection neurons (SPNs). In addition, alcohol and/or its metabolic product inhibit dopaminergic GABA by impairing GABA non-canonical synthesis, ultimately perturbing the co-released GABA by dopamine neurons in the dorsal striatum, and lead to enhancement in susceptibility of alcohol intake and preference. We will employ the use of genetically modified mice and virus injections to directly examine dopamine neurons and the specific pathways involved in GABA synthesis, modulation and release. By optogenetic activation of dopamine terminals in the striatum and whole-cell patch clamp on identified principle striatal cells, our experiments will provide a high-resolution assessment of the function of dopaminergic GABAergic in normal and enhanced alcohol intake and preference conditions. Combined with imaging, electrophysiology, optogenetics, biochemistry and behavioral analysis, this proposal provides a unique, multi- faceted approach to study dopamine and GABA co-release in the basal ganglia, and the mechanisms by which chronic binge drinking alters this form of neurotransmitter release. Based on our compelling preliminary findings, we aim to 1) examine whether cell-type specific deletion of ALDH1a1 in dopamine neurons leads to enhanced alcohol preference; 2) pinpoint the mechanism underlying the inhibition of co-released GABA by alcohol; and 3) investigate alcohol modulation of functional interplay between GABA and dopamine in the striatum. Our novel initial findings and the studies proposed in this grant will close the gaps in our knowledge about GABA synthesis in dopaminergic neurons and create a new window into our understanding of synaptic mechanisms underlying enhanced alcohol intake and preference, providing better tools and earlier targets for the treatment or prevention of alcohol use disorders.