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

项目摘要： 明确的神经适应发生作为酒精使用障碍的结果，潜在的衰弱的健康 与疾病相关的风险和社会问题。虽然GABA能、谷氨酸能和 多巴胺能神经传递强烈牵连，精确的神经机制，导致 酒精摄入和偏好的增强的易感性尚未得到很好的理解。因此，目前 除了心理治疗、解毒治疗外，可用于对抗酒精中毒的治疗方法很少，而且没有特异性。 以及恶心、呕吐药物，但没有治疗该疾病的药理学靶点。最近 研究已经发现由醛脱氢酶1a 1介导的非典型GABA合成 （ALDH 1a 1）和共同释放多巴胺能中脑神经元，我们已经收集了有力的证据， 表明这种替代性GABA合成途径随着血液酒精水平的降低而减少， 与酗酒有关方法上的进步现在提供了直接审查和 剖析GABA通路在急性和慢性酒精暴露中的作用。在这个提议中，我们假设 中脑多巴胺神经元共同释放的多巴胺和GABA之间的平衡对于 突触后纹状体棘状投射神经元（SPNs）。此外，酒精和/或其代谢产物抑制 多巴胺能GABA通过损害GABA非典型合成，最终扰乱共同释放的GABA 多巴胺神经元在背侧纹状体，并导致酒精摄入的敏感性增强， 偏好我们将使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、调节和释放的特定通路。通过 纹状体多巴胺末梢的光遗传学激活和全细胞膜片钳识别原理 纹状体细胞，我们的实验将提供一个高分辨率的评估多巴胺能神经元的功能， 正常和增强酒精摄入和偏好条件下的GABA能。结合成像， 电生理学，光遗传学，生物化学和行为分析，该提案提供了一个独特的，多， 多方面的方法来研究多巴胺和GABA共同释放在基底神经节，以及机制， 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）检查细胞类型特异性缺失是否 多巴胺神经元中的ALDH 1a 1导致酒精偏好增强; 2）查明机制 潜在的抑制共同释放的GABA的酒精;和3）研究酒精调制的功能 GABA和多巴胺之间的相互作用。我们的新的初步发现和研究中提出的 这项拨款将填补我们对多巴胺能神经元中GABA合成的知识空白， 新的窗口，我们了解突触机制的基础上增加酒精摄入量， 优先，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.