Optogenetic dissection of neural circuits underlying alcohol drinking behaviors

描述（由申请人提供）：酒精使用障碍造成了巨大的全球医疗负担，因此必须确定用于预防和治疗的新治疗靶点。酒精的一个有趣现象是人类个体中发生的消费变化：有些人以受控的方式饮酒而不产生依赖性，而另一些人则严重成瘾。为了理解这种饮酒变异现象，我建议利用小鼠模型来研究明显不同的饮酒行为的神经生理学基础。在C57 BL/6 J小鼠中，一种通常用于研究高酒精饮酒行为的近交系小鼠品系，我发现了一个稳定的低酒精饮酒群体。这种小鼠模型为我提供了一个独特的机会，研究神经生理学机制，这些机制是遗传相同的小鼠品系中低度和高度饮酒行为的基础，而无需挑战可变的基因背景相互作用。已知酒精使用障碍进展的标志是腹侧被盖区（VTA）中的多巴胺（DA）神经元的功能障碍，腹侧被盖区是编码药物刺激的显著性的关键区域。腹侧被盖区将功能多样的DA投射发送到两个高度参与药物奖励和动机的神经基底--中脑核（NAc）和内侧前额叶皮层（mPFC）。在我的初步研究中，我证明了所有腹侧被盖区DA神经元的体内放电活动和爆发活动在低C57 BL/6 J饮酒者中高于高饮酒和EtOH naïve小鼠。此外，光遗传学模拟在先前高饮酒的TH-Cre小鼠中观察到的VTA DA活性的增加减少了饮酒行为。由于越来越多的证据表明，腹侧被盖区DA神经元的功能多样性的基础上，他们的目标神经投射网站，我假设，根据我的初步研究结果，个人饮酒差异在遗传相同的小鼠产生的投射特异性（NAc与mPFC）神经元的改变腹侧被盖区DA神经元在饮酒。本课题将采用系统的方法研究C57 BL/6 J小鼠腹侧被盖区DA神经元在产生不同饮酒行为中的神经回路功能作用。为了表征低度和高度饮酒小鼠之间的投射特异性神经元改变，我将在体外电生理研究期间使用逆行荧光珠来区分腹侧被盖区DA神经元（目的1）。然后，我将使用创新的电路特异性光遗传学技术来模拟在腹侧被盖区神经元中观察到的已识别的神经生理学改变，以驱动特定的饮酒行为（目的2）。本研究将探讨腹侧被盖区多巴胺能神经元放电的神经适应性，并探讨其在个体饮酒行为中的作用。此外，这种提出的最先进的神经回路解剖将提供新的见解，以确定更有效的治疗酒精使用障碍的靶点。

DESCRIPTION (provided by applicant): Alcohol-use disorders create a substantial global healthcare burden and it is imperative to identify novel therapeutic targets for their prevention and treatment. An interesting phenomenon with alcohol is the variability of consumption that occurs within individuals of the human population: some individuals drink alcohol in a controlled manner without developing dependence while others develop severe alcohol addiction. To understand this phenomenon of alcohol drinking variability, I propose to utilize a mouse model to investigate the neurophysiological basis of evidently distinct alcohol drinking behaviors. In C57BL/6J mice, an inbred mouse strain typically used to study high alcohol drinking behaviors, I have found a stable low alcohol drinking population. This mouse model provides me with a unique opportunity to investigate the neurophysiological mechanisms that underlie low and high alcohol drinking behaviors in a genetically identical mouse line without the challenge of variable gene background interactions. It is known that a hallmark of the progression of alcohol-use disorders is the dysfunction of dopamine (DA) neurons in the ventral tegmental area (VTA), an area critical to encoding the salience of drug stimuli. The VTA sends functionally diverse DA projections to two neural substrates highly involved in drug reward and motivation - the nucleus accumbens (NAc) and the medial prefrontal cortex (mPFC). In my preliminary studies, I demonstrate that the in vivo firing activity and burst activity of all VTA DA neurons are higher in low C57BL/6J alcohol drinkers compared to high alcohol drinking and EtOH naïve mice. Furthermore, optogenetically mimicking this observed increase of VTA DA activity in previously high drinking TH-Cre mice reduced alcohol drinking behaviors. Because of the increasing body of evidence suggesting functional diversity of VTA DA neurons based on their target neural projection site, I hypothesize, based on my preliminary findings, that individual drinking differences in genetically identical mice arise from projection-specific (NAc versus mPFC) neuronal alterations of VTA DA neurons during alcohol consumption. My project will use a systematic approach to investigate the neural circuit functional roles VTA DA neurons have in generating different alcohol-drinking behaviors in C57BL/6J mice. To characterize projection-specific neuronal alterations between low and high alcohol drinking mice, I will use retrograde fluorescent beads to differentiate VTA DA neurons during in vitro electrophysiological investigations (Aim 1). I will then use innovative, circuit-specific optogenetic techniques to mimi the identified neurophysiological alterations observed in VTA neurons in order to drive specific alcohol drinking behaviors (Aim 2). This project will identify the neuroadaptations of VTA DA neuron firing underlying individual alcohol drinking behaviors. Furthermore, this proposed state-of-the-art neural circuit dissection will provide novel insight to identify more effective therapeuic target sites for alcohol-use disorders.