Ethanol Regulation of Neuronal Nicotinic Receptor Expression in Reward Circuitry

描述（由申请方提供）：神经元烟碱乙酰胆碱受体是由内源性神经递质乙酰胆碱（ACh）以及烟草的高度成瘾成分尼古丁激活的配体门控阳离子通道。神经元nAChR在多巴胺能中皮层边缘通路（“奖励”通路）中的表达对于尼古丁的奖励特性是必要的，但它们也与酒精的强化作用有关。乙醇，像所有滥用的药物一样，增加了多巴胺（DA）在脑桥核中的释放，这与强化有关。阻断nAChRs阻止DA释放，并抑制运动刺激和乙醇自我给药。酒精如何与nAChRs相互作用以促进强化？有趣的是，乙醇已被提出增加ACh释放的腹侧被盖区，从而增加DA能神经元中表达的nAChR的活性。此外，乙醇已被证明可以直接增强或抑制乙酰胆碱受体对乙酰胆碱的反应，这取决于受体的亚基组成。总之，这些数据表明，长期暴露于乙醇可能会长期激活nAChR。由于已知尼古丁对nAChR的慢性激活调节表达，我们假设乙醇也有可能调节nAChR的表达。在目的1中，我们将利用定量真实的时间RT-PCR来分析急性或慢性乙醇暴露后涉及成瘾的关键小鼠脑区中所有12个神经元nAChR基因的mRNA表达变化。定量免疫印迹也将用于测量nAChR蛋白表达与酒精暴露的变化。目标2将采用生物物理方法测量关键中脑区域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确定在奖励回路中由乙醇调节的nAChR亚型，而且还将为酒精戒断治疗提供潜在的分子靶点。 公共卫生相关性：酒精中毒是世界上第三大可预防死亡原因。该项目的目标是了解酒精如何调节神经元烟碱乙酰胆碱受体的表达和功能，这些受体是酒精和尼古丁成瘾特性的关键蛋白质。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，以及确定酒精戒断治疗的分子靶点。

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.