Optogenetic Analysis of Different Forms of Aversion-Resistant Ethanol Intake

描述(由申请人提供)：人类酗酒者经历了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，酒精摄入量仍持续存在。尽管强迫通过促进复发和持续饮酒而成为治疗酒精中毒的主要临床障碍，但几乎对驱动酒精摄入强迫方面的分子和神经机制知之甚少。人类研究表明，强迫行为可能由额叶皮质区域调节，额叶皮质区域向伏隔核核心(NAcore)发送谷氨酸能输入，而NAcore谷氨酸受体信号对许多动机、成瘾或习惯性行为的表达至关重要。尤其是岛叶皮质，与产生促进成瘾的强烈驱动力有关，至少对尼古丁是如此。在这里，这项提议的主要目标是一组探索性的大鼠实验，研究共同的分子回路(脑岛输入NAcore和激活NAcore NMDA受体)是否会驱动不同形式的抗厌恶酒精摄入，这可能会模拟人类强迫性酒精摄入的某些方面。我们假设，部分基于大量的初步数据，这种共同的分子回路促进了抗厌恶酒精的摄入，而不管摄入模式(从瓶子里喝乙醇，操纵杆按下乙醇)，或者厌恶刺激与乙醇配对的感觉形式(对奎宁的味道，对足部电击的体感)。因此，特定目标1在体内使用最先进的光遗传学技术来检查在不同形式的抗厌恶酒精摄入过程中，抑制岛到NAcore的输入是否同样减少了乙醇的摄入。特别是，我们使用卤视紫质，一种光激活的抑制蛋白，可以在特定的大脑区域病毒表达，以选择性地调节轴突终末。此外，我们的体外电生理学实验发现，在岛到NAcore的输入下，NMDAR功能增强，因此特定目的2检查了NAcore内NMDAR的药理阻断是否也抑制了不同摄取模式和不同厌恶刺激与乙醇配对的抗厌恶乙醇摄入。我们还研究了当乙醇没有明显地与厌恶的刺激配对时，是否岛-NAcore输入和NAcore NMDAR调节摄取。NAcore的谷氨酸能输入可能在抗厌恶酒精摄入的表达中发挥核心作用，我们将光遗传学与颅内药理学相结合，可能为强迫性酒精摄入的分子机制提供关键的和治疗相关的信息。

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.