Mechanistic studies of cAMP effectors in cocaine addiction

项目摘要 可卡因成瘾在美国和世界范围内是一个巨大的医疗和经济负担。那里 目前还没有FDA批准的治疗可卡因成瘾的药物。反复暴露于 包括可卡因在内的滥用诱导中脑边缘系统中cAMP依赖性信号传导的上调， 开始向上瘾过渡。cAMP有三种直接效应物：蛋白激酶A（PKA）、交换蛋白 由cAMP（Epac）激活和超极化激活的环核苷酸门控（HCN）通道。多 已经做了工作来表征药物强化调节中的cAMP-PKA信号通路 和成瘾行为。然而，很少有研究涉及“其他”cAMP效应物如何调节细胞内的cAMP水平。 滥用药物对细胞和行为的影响。在我们之前的NIH资助期间，我们提供了第一个 Epac 2介导的可卡因诱导的兴奋性和抑制性突触可塑性调节的证据 腹侧被盖区（VTA）的多巴胺神经元和条件性位置偏爱。药物自- 行政管理对滥用责任具有高度的面子和预测有效性，是滥用责任的黄金标准。 研究滥用药物的强化作用。然而，Epac是否以及如何调节可卡因自身- 管理仍然未知。在我们以前资助的赠款期间和我们的初步工作的基础上， 研究中，R 01更新的长期目标是测试Epac和HCN通过不同但不同的方式起作用的假设。 调节多巴胺能传递和可卡因诱导的长期可塑性的补充机制， 这些机制有助于可卡因强化和寻求行为。使用病毒介导的 敲除、条件敲除、快速扫描循环伏安法（FSCV）、电生理学和可卡因自身 我们将通过三个具体目标来检验这一假设。在目标一和二中，我们将瓦解该地区- 以及腹侧被盖区和延髓核中Epac 2参与可卡因的细胞类型特异性机制 强化和寻求行为。在目标III中，我们将确定可卡因自我给药- 腹侧被盖区多巴胺神经元中HCN 2通道诱导的、cAMP介导的适应有助于可卡因 加固.这些详细的机制研究有望提供第一个证据，表明这些不足- 研究了中脑边缘多巴胺系统中的cAMP效应器调节强化的可卡因自我给药， 药物寻求

Project Summary Cocaine addiction is a substantial medical and economic burden in the U.S. and worldwide. There currently are no FDA-approved medications for treating cocaine addiction. Repeated exposure to drugs of abuse including cocaine induces the upregulation of cAMP-dependent signaling in the mesolimbic system that initiates the transition to addiction. cAMP has three direct effectors: protein kinase A (PKA), exchange proteins activated by cAMP (Epac), and hyperpolarization-activated cyclic nucleotide-gated (HCN) channels. Much work has been done to characterize the cAMP-PKA signaling pathway in the regulation of drug reinforcement and addictive behavior. However, few studies have addressed how the “other” cAMP effectors regulate the cellular and behavioral effects of drugs of abuse. During our prior NIH funding period, we provided the first evidence for Epac2-mediated modulation of cocaine-induced excitatory and inhibitory synaptic plasticity in dopamine neurons of the ventral tegmental area (VTA) and conditioned place preference. Drug self- administration has a high degree of face and predictive validity for abuse liability and is the gold standard for studying the reinforcing effects of drugs of abuse. However, whether and how Epac regulates cocaine self- administration remains unknown. Building on work from our previously funded grant period and our preliminary studies, the long-term goal of this R01 renewal is to test the hypothesis that Epac and HCN act via distinct but complementary mechanisms to regulate dopaminergic transmission and cocaine-induced long-term plasticity, and that these mechanisms contribute to cocaine reinforcement and seeking behavior. Using viral-mediated knockdown, conditional knockouts, fast-scan cyclic voltammetry (FSCV), electrophysiology, and cocaine self- administration, we will test this hypothesis via three Specific Aims. In Aims I and II, we will unravel the region- and cell type-specific mechanisms whereby Epac2 in the VTA and nucleus accumbens contribute to cocaine reinforcement and seeking behavior, respectively. In Aim III, we will determine how cocaine self-administration- induced, cAMP-mediated adaptations in HCN2 channels in VTA dopamine neurons contribute to cocaine reinforcement. These detailed, mechanistic studies are expected to provide first evidence that these under- studied cAMP effectors in the mesolimbic dopamine system regulate reinforced cocaine self-administration and drug seeking.