AMPA Receptor Trafficking and Cocaine Reinstatement

描述(申请人提供)：可卡因滥用是美国的一个主要公共卫生问题。在最新的国家研究中，12岁以上目前吸食可卡因的人数估计为160万，占总人口的0.7%。近年来，广泛的研究表明，可卡因成瘾与神经适应和随后的奖赏学习病理有关。慢性可卡因暴露会导致谷氨酸能突触的改变，包括谷氨酸释放、基因和蛋白表达以及突触可塑性的变化。进一步阐明这些变化背后的机制以及它们如何导致复发是本次赠款申请的目标。更具体地说，利用体外切片生理学和体内现场记录的研究表明，反复暴露于可卡因会导致伏隔核(NAC)内长期抑郁的减少。尽管这种作用的确切机制尚不清楚，但来自学习和记忆领域的现有证据表明，PKC介导的AMPA受体内吞作用是长期抑郁所必需的。我们的初步结果表明，利用AMPA受体GluA2亚单位上缺乏PKC磷酸化位点的转基因小鼠来阻断这种内吞作用，可以增加寻找药物行为的恢复。建议拨款的指导部分的具体目的是使用这种遗传小鼠来探索可卡因恢复的分子机制。目的1利用膜片钳电生理学研究可卡因相关信号促进细胞复燃的机制。Aim 2将这项工作扩展到包括压力诱导的可卡因寻求恢复。为资助的独立(R00)阶段提出的AIMS将进一步调查AMPA受体贩运的个别成分，检查新的PKC亚型PKM？在线索和应激诱导恢复的能力中的作用。因此，拟议实验的总体目标是确定AMPA受体运输在可卡因诱导的突触可塑性变化中的作用，以及这些可塑性变化是否是两种不同形式的可卡因恢复所必需的，这是一种复发的动物模型。到目前为止，我在可卡因成瘾领域的研究给了我在行为和分子方法方面的坚实基础。然而，在该奖项的K99阶段期间提议的电生理学方面的专门培训将拓宽我的知识基础，并允许我在未来的职业生涯中采取真正的多学科方法。此外，这个培训和个性化研究项目将很好地服务于我，因为我正在为未来的学术终身教职职位做准备。

DESCRIPTION (provided by applicant): Cocaine abuse is a major public health problem in the United States. In the latest national study, the number of people over the age of 12 who are current cocaine users is estimated at 1.6 million, or 0.7% of the total population. In recent years extensive research has demonstrated that cocaine addiction is associated with neuroadaptations and consequent pathology of reward learning. Chronic cocaine exposure leads to alterations in glutamatergic synapses, including changes in glutamate release, gene and protein expression, and synaptic plasticity. Further elucidating the mechanisms underlying these changes and how they lead to relapse is the goal of this grant application. More specifically, work utilizing both in vitro slice physiology and in vivo field recordings indicate tat repeated exposure to cocaine leads to a decrease in long-term depression within the nucleus accumbens (NAc). Although the exact mechanisms underlying this effect are unclear, existing evidence from the learning and memory field indicates that PKC-mediated AMPA receptor endocytosis is necessary for long-term depression. Our preliminary results show that blocking this endocytosis, utilizing a transgenic mouse lacking the PKC phosphorylation site on the AMPA receptor GluA2 subunit, leads to increased reinstatement of drug seeking behavior. The specific aims for the mentored component of the proposed grant are designed to use this genetic mouse to probe the molecular mechanisms underlying cocaine reinstatement. Aim 1 focuses on delineating the mechanisms responsible for reinstatement promoted by cocaine-associated cues using patch clamp electrophysiology. Aim 2 expands this work to include stress- induced reinstatement of cocaine seeking. Aims proposed for the independent (R00) phase of the grant will investigate further the individual components of AMPA receptor trafficking, examining the role of the novel PKC isoform, PKM?, in the ability of cues and stress to elicit reinstatement. Thus, the overall goal of the proposed experiments is to determine the role of AMPA receptor trafficking in cocaine-induced changes in synaptic plasticity and whether these changes in plasticity are required for two distinct forms of cocaine reinstatement, an animal model of relapse. My research so far in the field of cocaine addiction has given me a solid foundation in behavioral and molecular approaches. However, the specialized training proposed in electrophysiology during the K99 phase of this award will broaden my knowledge base and allow for a truly multi-disciplinary approach in my future career. Furthermore, this training and individualized research project will serve me well as I prepare for a future academic tenure-track position.