AMPA Receptor Trafficking and Cocaine Reinstatement

可卡因滥用是美国的一个主要公共卫生问题。在最新的全国性研究中， 12岁以上的可卡因使用者估计为160万人，占总数的0.7%。 人口近年来，广泛的研究表明，可卡因成瘾与 神经适应和随之而来的奖励学习病理学。长期接触可卡因会导致 谷氨酸能突触的改变，包括谷氨酸释放、基因和蛋白质表达的变化， 和突触可塑性。进一步阐明这些变化背后的机制以及它们如何导致损失， 故态复萌是这次拨款申请的目标。更具体地说，利用体外切片生理学和 体内现场记录表明，重复暴露于可卡因导致长期 延髓核（NAc）内的抑郁症。尽管这种效应背后的确切机制是 学习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症所必需的。在K99阶段获得的其他证据 资金表明，阻断长期抑郁症，无论是通过增强内吞作用，通过删除 锚定蛋白谷氨酸受体相互作用蛋白（GRIP），或破坏内吞作用，利用 转基因小鼠缺乏AMPA受体GluA 2亚基上的PKC磷酸化位点，导致 寻求药物行为的恢复增加。为赠款的ROO阶段提出的目标将扩大 基于这些发现，研究AMPA受体运输在应激诱导的恢复中的作用。这将 使用上述两种小鼠品系完成，并检查如何操纵AMPA 内吞作用改变应激诱导的行为以及生理学。补助金的目的没有一个 自最初提交K99以来发生了变化，但K99阶段的一个目标已被切换为 已经完成的ROO阶段的目标，如研究策略部分所讨论的。

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 lo relapse is the goal of this grant application. More specifically, work utilizing both in vitro slice physiology and in vivo field recordings indicate that 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. Additional evidence obtained during the K99 phase of funding indicates that blocking long-term depression, either via potentiating endocytosis via deletion of the anchoring protein glutamate receptor interacting protein (GRIP), or disrupting endocytosis, utilizing a transgenic mouse lacking the PKC phosphorylation site on the AMPA receptor GluA2 subunit, leads to increased reinstatement of drug seeking behavior. Aims proposed for the ROO phase of the grant will expand upon these findings to examine the role AMPA receptor trafficking in stress-induced reinstatement. This will be acomplished using the two lines of mice described above and examining how manipulating AMPA endocytosis alters stress-induced behaviors as well as physiology. None of the aims of the grant have changed since the original K99 submission, however one aim from the K99 phase has been switched with an already-completed aim from the ROO phase, as discussed in the Research Strategy section.