Optogenetic Analysis of Different Forms of Aversion-Resistant Ethanol Intake

描述（由申请人提供）：人类酗酒者经历复发和强迫性酒精寻求的主要时期，尽管有不利的经济，社会和身体后果，酒精摄入仍然存在。虽然强迫症是通过促进复发和持续饮酒来治疗酒精中毒的主要临床障碍，但实际上对驱动酒精摄入强迫性方面的分子和神经机制一无所知。人类研究表明，强迫行为可能受到额叶皮质区的调节，额叶皮质区将谷氨酸能输入发送到丘脑核核心（NAcore），而NAcore谷氨酸受体信号传导对于许多动机，成瘾和习惯性行为的表达至关重要。尤其是岛叶皮层，它与产生促进成瘾的强烈冲动有关，至少对尼古丁来说是这样。在这里，这个提议的主要目标是一组探索性的大鼠实验，解决是否有一个共同的分子电路（胰岛素输入NAcore和激活NAcore NMDA受体）驱动不同形式的厌恶抗性乙醇摄入，这可能会模拟人类强迫性酒精摄入的某些方面。我们假设，部分基于广泛的初步数据，这一共同的分子回路促进厌恶抵抗乙醇的摄入，无论摄入模式（从瓶子里喝乙醇，操作性杠杆按压乙醇）或与乙醇配对的厌恶刺激的感觉方式（奎宁的味道，足电击的体感）。因此，具体目标1在体内使用最先进的光遗传学技术来检查抑制Insula-to-NAcore输入是否在不同形式的厌恶抗性乙醇摄入期间类似地减少乙醇摄入。特别是，我们使用盐视紫红质，一种光激活的抑制蛋白，可以在特定的大脑区域内病毒表达，以选择性地调节轴突末梢。此外，我们的体外电生理学实验发现在Insula-to-NAcore输入下NMDAR功能增强，因此具体目标2检查了NAcore内NMDAR的药理学阻断是否也抑制了不同摄入模型和与乙醇配对的不同厌恶刺激的厌恶抗性乙醇摄入。我们还研究了是否Insula-NAcore输入和NAcore NMDAR介导的摄入时，乙醇是不公开配对的厌恶刺激。NAcore的谷氨酸能输入可能在厌恶性酒精摄入的表达中发挥核心作用，我们使用光遗传学结合颅内药理学可能提供有关强迫性酒精摄入的分子机制的关键和治疗相关信息。

DESCRIPTION (provided by applicant): Human alcoholics undergo major periods of relapse and compulsive alcohol seeking, where alcohol intake persists despite adverse economic, social, and physical consequences. Although compulsion represents a major clinical hurdle to treatment of alcoholism by promoting relapse and continued alcohol intake, virtually nothing is known about molecular and neuronal mechanisms that drive compulsive aspects of alcohol intake. Human studies suggest that compulsive behavior may be regulated by frontal cortical areas that send glutamatergic inputs to the nucleus accumbens core (NAcore), and NAcore glutamate receptor signaling is critical for the expression of many motivated, addictive, and perhaps habitual behaviors. The Insular cortex in particular is implicated in generating strong drives that promote addiction, at least for nicotine. Here, the major goal of this proposal is an exploratory set of rat experiments addressing whether a common molecular circuit (Insula inputs to the NAcore and activation of NAcore NMDA receptors) drives different forms of aversion-resistant ethanol intake, which may model some aspects of human compulsive alcohol intake. We hypothesize, based in part on extensive preliminary data, that this common molecular circuit promotes aversion-resistant ethanol intake regardless of intake model (drinking ethanol from a bottle, operant lever pressing for ethanol) or the sensory modality of the aversive stimulus paired with ethanol (taste for quinine, somatosensory for footshock). Thus, Specific Aim 1 uses state-of-the- art optogenetic techniques in vivo to examine whether inhibiting Insula-to-NAcore inputs similarly reduces ethanol intake during the different forms of aversion-resistant ethanol intake. In particular, we use halorhodopsin, a light-activated inhibitory protein than can be viraly expressed within a particular brain region to selectively modulate axon terminals. Also, our in vitro electrophysiology experiments find enhanced NMDAR function under Insula-to-NAcore inputs, and thus Specific Aim 2 examines whether pharmacological block of NMDARs within the NAcore also inhibits aversion-resistant ethanol intake with different intake models and different aversive stimuli paired with ethanol. We also examine whether Insula-NAcore inputs and NAcore NMDARs mediate intake when ethanol is not overtly paired with an aversive stimuli. Glutamatergic inputs to the NAcore likely play a central role in the expression of aversion-resistant alcohol intake, and our use of optogenetics in combination with intracranial pharmacology is likely to provide critical and therapeutically relevant information about molecular mechanisms underlying compulsive alcohol intake.