Role of nicotinic receptors in inhibitory GABA neurons on alcohol reward and behavior

项目摘要 过度饮酒每年造成9.8%的可预防死亡，而酗酒的成本 每年25亿美元的医疗和经济支出。尽管酗酒代价高昂， 过去十年来，消费量大幅增加。FDA批准的只有3种 减少酒精使用的药物疗法，在实现和维持戒酒方面的效果都很低， 强调需要更有效的治疗酒精滥用。发展的主要障碍之一 更好的治疗酒精滥用的方法是大量的细胞和分子机制， 奖励最近的研究表明，酒精的奖赏特性取决于它与 烟碱乙酰胆碱受体（nAChRs）在奖赏途径中的作用。中脑奖赏回路中的nAChRs 刺激多巴胺（DA）释放，介导酒精奖励。α4亚基特别重要， 酒精成瘾，因为靶向该亚基的药物疗法减少了人类的酒精消耗， 动物模型此外，α4基因敲除小鼠的酒精消耗量和DA释放减少， 减少他们对nAChR药物的酒精消耗。α4 nAChR存在于几种细胞类型中 在腹侧被盖区（VTA），包括DA投射神经元和局部GABA神经元，它们提供 DA神经元的抑制性张力。最近的研究表明，腹侧被盖区GABA神经元是重要的介质， 奖励行为，因为激活这些神经元破坏蔗糖消费和条件的地方厌恶。 酒精增加DA神经元放电频率，从而影响酒精奖励行为。酒精也 调节VTA GABA神经元的活性，但nAChRs在这一过程中的作用尚未研究。 目前该领域的方法不能探测α4 nAChR在单个细胞群中的作用， 抑制性GABA神经元上的nAChRs调节酒精奖赏的机制仍然未知。 为了解决这一知识缺口，我们开发了一种有条件的病毒基因递送策略， VTA GABA神经元内α4亚基选择性敲低。该提案的目的是定义 腹侧被盖区GABA神经元α4 nAChR亚单位在饮酒和奖赏中的作用我们假设 腹侧被盖区GABA神经元中含有α4亚单位的nAChRs通过以下途径降低酒精奖赏和消耗： 抑制DA神经元兴奋性。该项目的具体目标包括：1）确定α4的作用 nAChR亚单位在VTA GABA神经元在自愿饮酒小鼠;和2）确定的作用， 腹侧被盖区GABA神经元α4 nAChR亚单位在DA神经元激活和主观奖赏中的作用 酒精这一提议将为α4 nAChR亚基在以下方面的作用提供新的重要信息： 调节酒精奖励。通过识别酒精奖赏中重要的细胞类型和nAChR亚基， 这项研究的结果将为临床前酒精的开发和精制提供有价值的见解 戒烟药物，从而帮助解决美国最大的公共卫生问题之一。

PROJECT SUMMARY Excessive consumption of alcohol contributes to 9.8% of preventable deaths annually, and alcohol abuse costs $2.5 billion each year in healthcare and economic expenses. Despite the high costs of alcohol abuse, consumption has increased significantly over the past decade. There are only 3 FDA-approved pharmacotherapies to reduce alcohol use, all with low efficacy in achieving and maintaining abstinence, highlighting the need for more effective treatments for alcohol abuse. One of the major barriers to developing better treatments for alcohol abuse is the multitude of cellular and molecular mechanisms underlying alcohol reward. Recent studies indicate the rewarding properties of alcohol are dependent upon its interaction with nicotinic acetylcholine receptors (nAChRs) in reward pathways. nAChRs in the midbrain reward circuit stimulate dopamine (DA) release, which mediates alcohol reward. The α4 subunit is of particular interest in alcohol addiction, as pharmacotherapies targeting this subunit decrease alcohol consumption in human and animal models. Additionally, α4 knockout mice show reduced alcohol consumption and DA release, and do not reduce their alcohol consumption in response to nAChR drugs. α4 nAChRs are found within several cell types in the ventral tegmental area (VTA), including DA projection neurons and local GABA neurons, which provide inhibitory tone to DA neurons. Recent studies demonstrate that VTA GABA neurons are critical mediators of reward behaviors, as activating these neurons disrupts sucrose consumption and conditions a place aversion. Alcohol increases DA neuron firing frequency, which influences alcohol reward behavior. Alcohol also modulates the activity of VTA GABA neurons, but the role of nAChRs in this process has not been studied. Current approaches in the field cannot probe the role of α4 nAChRs in individual cell populations, and the mechanism through which nAChRs on inhibitory GABA neurons modulate alcohol reward remains unknown. To address this gap in knowledge, we have developed a conditional viral gene delivery strategy that initiates knockdown of the α4 subunit selectively within VTA GABA neurons. The goal of this proposal is to define the role of the α4 nAChR subunit in VTA GABA neurons in alcohol consumption and reward. We hypothesize that nAChRs containing the α4 subunit in VTA GABA neurons decreases alcohol reward and consumption through inhibition of DA neuron excitability. The specific aims of this project include: 1) determine the role of the α4 nAChR subunit in VTA GABA neurons in voluntary alcohol consumption in mice; and 2) determine the role of the α4 nAChR subunit in VTA GABA neurons in the DA neuron-activating and subjective rewarding properties of alcohol. This proposal will provide novel and important information about the role of the α4 nAChR subunit in modulating alcohol reward. By identifying important cell types and nAChR subunits in alcohol reward, the results of this study will provide valuable insight into the development and refinement of preclinical alcohol cessation drugs and thus help address one of the largest public health problems in America.