Chronic alcohol and the neurocircuitry of aversion

 描述（由申请人提供）：酒精的积极（奖励）特性有助于持续使用酒精，而其消极（厌恶）特性则有助于限制消费。依赖性与对乙醇的厌恶特性比其奖励特性更大的耐受性有关，这被认为是促进持续消费的原因。头内侧被盖核（RMTg）对中脑边缘多巴胺神经元施加抑制性控制，并在滥用药物的厌恶特性的信号传导中起关键作用。前额叶皮层的前边缘（PrL）亚区与RMTg有几个关键的功能相似之处，包括促进厌恶学习和对厌恶刺激的反应。尽管有这些相似之处，从PrL到RMTg的预测在很大程度上被忽视，仍然是一个开放的调查领域。该K99/R 00提案包括基于候选人（Elizabeth Burnett博士）的初步数据的全面培训和研究计划，这些数据确定了RMTg在传递酒精厌恶特性信号中的作用。在该奖项的指导K99阶段，Burnett博士将接受尖端实验室技术的培训，包括切片电生理学，光遗传学，突触形态分析和病毒介导的跨突触追踪。这些技术将增强她在酒精滥用和依赖的细胞和分子方法以及行为模型方面的现有专业知识。在候选人的指导团队的指导下，其中包括主要导师（Judson钱德勒博士）和共同导师（John Woodward博士），候选人将通过测试一个新的假设来扩展她目前的研究，即酒精诱导的PrL-RMTg途径的可塑性在慢性乙醇暴露的功能后果中发挥作用。目的1将使用体内光遗传学结合操作性行为测试来研究在依赖诱导的递增和厌恶抗性乙醇摄入期间选择性激活PrL-RMTg通路的效果。目的二：利用全细胞膜片钳切片电生理学和体外光遗传学技术研究慢性乙醇暴露对PrL-RMTg内突触可塑性的影响。目的3将通过使用病毒介导的跨突触逆行追踪鉴定突触到投射到RMTg的PrL神经元上的神经元来定义PrL-RMTg的扩展的神经回路。根据这一目标的实验也将确定这些新确定的二阶RMTg输入慢性乙醇暴露的参与，通过测量cFos诱导这些神经元在撤退。这些研究的结果将为PrL-RMTg途径在促进酒精消费升级中的作用提供新的见解。提高我们对参与调节酒精消费的厌恶成分的神经回路的理解可能有助于发现治疗酒精使用障碍的新治疗靶点。Burnett博士将在该奖项的指导K99阶段接受的培训将促进她的职业发展，而在该奖项的R 00阶段获得的成果将成为Burnett博士独立研究计划的基础。

 DESCRIPTION (provided by applicant): Continued alcohol use is facilitated by alcohol's positive (rewarding) properties, whereas its negative (aversive) properties serve to limit consumption. Dependence is associated with greater tolerance to ethanol's aversive properties than its rewarding properties, which is thought to promote continued consumption. The rostromedial tegmental nucleus (RMTg) exerts inhibitory control over mesolimbic dopamine neurons and is critically involved in signaling the aversive properties of drugs of abuse. The prelimbic (PrL) subregion of the prefrontal cortex shares several critical functional similarities with the RMTg including facilitating aversion learning and responding to aversive stimuli. Despite these similarities, the projection from the PrL to the RMTg has been largely ignored and remains an open area of investigation. This K99/R00 proposal comprises a comprehensive training and research plan based upon the candidate's (Dr. Elizabeth Burnett) preliminary data identifying a role for the RMTg in signaling the aversive properties of alcohol. During the mentored K99 phase of the award, Dr. Burnett will receive training in cutting-edge laboratory techniques including slice electrophysiology, optogenetics, analysis of synaptic morphology, and virally-mediated trans-synaptic tracing. These techniques will augment her existing expertise in cellular and molecular approaches and behavioral models of alcohol abuse and dependence. Under the guidance of the candidate's mentoring team, which includes the primary mentor (Dr. Judson Chandler) and co-mentor (Dr. John Woodward), the candidate will expand her current studies by testing a novel hypothesis that alcohol-induced plasticity in the PrL-RMTg pathway plays a role in the functional consequences of chronic ethanol exposure. Aim 1 will investigate the effect of selective activation of the PrL-RMTg pathway during dependence-induced escalated and aversion-resistant ethanol intake using in vivo optogenetics in combination with operant behavioral testing. Aim 2 will use whole-cell patch-clamp slice electrophysiology and in vitro optogenetics to examine the effect of chronic ethanol exposure on synaptic plasticity within the PrL-RMTg. Aim 3 will define the PrL-RMTg's expanded neurocircuitry by identifying neurons that synapse onto PrL neurons projecting to the RMTg using virally-mediated trans- synaptic retrograde tracing. Experiments under this aim will also determine the involvement of these newly identified second-order RMTg inputs in chronic ethanol exposure by measuring cFos induction in these neurons during withdrawal. The results of these studies will provide new insights into the role of the PrL-RMTg pathway in promoting escalated alcohol consumption. Improving our understanding of the neurocircuitry involved in mediating the aversive component(s) of alcohol consumption may help uncover new therapeutic targets for the treatment of alcohol use disorders. The training Dr. Burnett will receive during the mentored K99 phase of the award will facilitate her career development and the results obtained during the R00 phase of the award will form the foundation of Dr. Burnett's independent research program.