a6 subunit-containing nicotinic receptors in alcohol consumption and reward

描述(申请人提供)：饮酒是世界上导致过早死亡的第三大风险因素[1]。对推动饮酒的作用机制的洞察将导致更好的戒酒疗法。酒精已被证明可以激活中皮质边缘通路中的多巴胺能神经元，这是由所有其他已知的滥用药物激活的主要大脑奖励回路。具体地说，烟碱型乙酰胆碱受体(NAChRs)与饮酒和奖赏有关。神经元nAChRs是五聚体配体门控离子通道，有12个不同的亚基被识别(α2-α10，β2-β4)。亚基组成决定了受体的生物物理和药理学特性。参与酒精消费和奖赏的nAChRs的亚基组成目前尚不清楚。此前，我们的实验室已经表明，包含Alpha4亚单位(Alpha4*nAChRs)的nAChRs与酒精消费和奖励密切相关。此外，初步数据表明，与饮酒和奖赏相关的nAChRs也可能含有阿尔法6亚单位。有趣的是，α6 nAChR亚单位基因CHRNA6的多态性与饮酒者大量饮酒有关[12]。α6亚单位也在腹侧被盖区(VTA)的DA能神经元中高表达，VTA是中皮质边缘通路的一部分。因此，我推测α6*nAChRs参与了酒精消费和奖赏，以及DAR能VTA神经元的激活。为了验证这一假设，我将使用药理学、遗传学、电生理学和行为分析。在目标1中，我将在小鼠中脑切片中使用生物物理方法来验证阿尔法6*nAChRs在乙醇诱导的VTA DA能神经元激活中起关键作用的假设。在目标2中，我将使用在黑暗中饮酒和有条件的场所偏好来分别衡量饮酒量和奖励。这些分析将结合大脑区域选择性地注入α6nAChR拮抗剂和不表达CHRNA6的遗传小鼠模型来进行。预计这些实验的结果将为急性饮酒和奖励背后的分子机制提供见解。

DESCRIPTION (provided by applicant): Alcohol consumption is the third largest risk factor for premature mortality in the world [1]. Insights into the mechanism of action that drives consumption will lead to better drinking cessation therapies. Alcohol has been shown to activate dopaminergic (DAergic) neurons within the mesocorticolimbic pathway, the major brain reward circuit activated by all other known drugs of abuse. Specifically, nicotinic acetylcholine receptor (nAChRs) have been implicated in alcohol consumption and reward. Neuronal nAChRs are pentameric ligand gated ion channels, with twelve distinct subunits identified (alpha2-alpha10, beta2-beta4). The subunit composition determines the biophysical and pharmacological properties of the receptor. Subunit composition of nAChRs involved in alcohol consumption and reward are currently unknown. Previously, our lab has shown that nAChRs that contain the alpha4 subunit (alpha 4* nAChRs) are critically involved in alcohol consumption and reward. In addition, preliminary data suggests that nAChRs involved in alcohol consumption and reward may also contain the alpha 6 subunit. Interestingly, there are polymorphisms in the alpha 6 nAChR subunit gene, CHRNA6, associated with heavy alcohol consumption in human drinkers [12]. The alpha 6 subunit is also highly expressed in DAergic neurons in the ventral tegmental area (VTA), which is part of the mesocorticolimbic pathway. Thus, I hypothesize that alpha 6* nAChRs are involved in alcohol consumption and reward, as well as activation of DAergic VTA neurons. To test this hypothesis, I will use pharmacology, genetics, electrophysiology and behavioral assays. In Aim 1, I will use biophysical approaches in mouse midbrain slices to test the hypothesis that alpha 6* nAChRs play a critical role in ethanol-induced activation of VTA DAergic neurons. In Aim 2, I will use drinking- in-the-dark and conditioned place preference to measure alcohol consumption and reward, respectively. These assays will be done in combination with brain region-selective infusions of alpha 6 nAChR antagonists and genetic mouse models that do not express CHRNA6. It is anticipated that the results from these experiments will provide insights into the molecular mechanism underlying acute alcohol consumption and reward.