Ethanol Regulation of Neuronal Nicotinic Receptor Expression in Reward Circuitry

描述(申请人提供)：神经性烟碱型乙酰胆碱受体是由内源性神经递质乙酰胆碱(ACh)激活的配基门控阳离子通道，以及烟草中高度成瘾的成分尼古丁。神经元nAChRs在多巴胺能中皮质边缘通路(奖赏通路)的表达是尼古丁奖赏特性所必需的，但它们也与酒精的增强作用有关。像所有滥用药物一样，乙醇会增加伏隔核多巴胺(DA)的释放，这与强化有关。阻断nAChRs可阻止DA的释放，并抑制运动刺激和乙醇自身给药。酒精如何与nAChRs相互作用以促进强化？有趣的是，乙醇被认为可以增加VTA中ACh的释放，从而增加DAR能神经元中表达的nAChRs的活性。此外，乙醇已被证明直接增强或抑制nAChR对ACh的反应，这取决于受体的亚单位组成。总而言之，这些数据表明，长期接触乙醇可能会慢性激活nAChRs。由于已知尼古丁对nAChRs的慢性激活可以调节nAChR的表达，我们假设乙醇也有可能调节nAChR的表达。在目标1中，我们将利用实时定量RT-PCR分析急性或慢性酒精暴露后与成瘾有关的小鼠大脑关键区域中所有12个神经元nAChR基因的mRNA表达变化。定量免疫印迹也将被用来测量酒精暴露后nAChR蛋白表达的变化。在目标2中，将利用生物物理方法来测量关键中脑区急性或慢性乙醇暴露时nAChR功能的变化。我们预计，这项研究的结果不仅将识别酒精在奖赏回路中调节的nAChR亚型，而且还将导致潜在的酒精戒断治疗的分子靶点。 与公共卫生相关：酒精中毒是世界上可预防的死亡的第三大原因。拟议项目的目标是了解酒精如何调节神经元烟碱型乙酰胆碱受体的表达和功能，这是与酒精和尼古丁的成瘾特性密切相关的关键蛋白质。从这个项目中获得的见解应该有助于阐明酒精中毒的分子机制，以及确定酒精戒断疗法的分子靶点。

DESCRIPTION (provided by applicant): Neuronal nicotinic acetylcholine receptors are ligand-gated cation channels activated by the endogenous neurotransmitter, acetylcholine (ACh), as well as the highly addictive component of tobacco, nicotine. Expression of neuronal nAChRs in the dopaminergic mesocorticolimbic pathways (the 'reward' pathways) are necessary for nicotine's rewarding properties, but they have also been implicated in the reinforcing effects of alcohol. Ethanol, like all drugs of abuse, increases dopamine (DA) release in nucleus accumbens which is associated with reinforcement. Blocking nAChRs prevents DA release, and inhibits both locomotor stimulation and ethanol self-administration. How may alcohol interact with nAChRs to contribute to reinforcement? Interestingly, ethanol has been proposed to increase ACh release in the VTA thereby increasing the activity of nAChRs expressed in DAergic neurons. In addition, ethanol has been shown to directly either potentiate or inhibit the nAChR response to ACh depending on the subunit composition of the receptor. Together, these data suggest that chronic exposure to ethanol may chronically activate nAChRs. Since it is known that chronic activation of nAChRs by nicotine modulates expression, we hypothesize that ethanol has the potential to regulate nAChR expression, as well. In Aim 1, we will utilize quantitative real time RT-PCR to analyze mRNA expression changes in all 12 neuronal nAChR genes in key mouse brain areas implicated in addiction after acute or chronic ethanol exposure. Quantitative immunoblotting will also be used to measure changes in nAChR protein expression with alcohol exposure. A biophysical approach will be utilized in Aim 2 to measure changes in nAChR function with acute or chronic ethanol exposure in key midbrain areas. We anticipate that the results from this study will not only identify nAChR subtypes regulated by ethanol in reward circuitry, but also lead to a potential molecular target for alcohol cessation therapeutics. PUBLIC HEALTH RELEVANCE: Alcoholism is the third largest cause of preventable mortality in the world. The goal of the proposed project is to understand how alcohol may regulate expression and function of neuronal nicotinic acetylcholine receptors, key proteins critically involved in the addictive properties of both alcohol and nicotine. The insights gained from this project should help elucidate the molecular mechanism underlying alcoholism, as well as identify molecular targets for alcohol cessation therapeutics.