GLUTAMATE RECEPTORS AND OPIOID DEPENDENCE: MOLECULES, CIRCUITS AND BEHAVIOR

描述(申请人提供)：阿片类药物依赖的特征是在终止药物暴露后出现的负面生理和心理症状。由于这些症状可以通过持续使用药物来缓解或避免，依赖导致了成瘾的循环。虽然对依赖的神经基础知之甚少，但有证据表明，中央杏仁核(CEA)中的功能性离子型(NMDA和AMPA)谷氨酸受体在这种阿片类药物依赖的可塑性中发挥着关键作用。在PI的当前研究科学家发展奖期间进行的研究表明，Cre-loxP技术可用于删除CEA神经元中的NMDA-NR1(NR1)受体亚单位基因，并防止吗啡戒断诱导的厌恶，而不影响身体症状。本提案的目的是通过检验以下全球假设来扩展这些发现：中央杏仁核NMDA受体在与阿片类药物依赖相关的条件性厌恶和AMPA受体可塑性中发挥关键作用。这一假说将通过以下具体目标来解决：目标1将检验CEA敲除NR1将产生对阿片类药物戒断厌恶的特定抑制的假说。目的2验证阿片受体(OR)和离子型谷氨酸受体共同定位于CEA神经元的树突和树突(即突触后)的假说。目的3验证急性阿片类药物暴露可影响AMPA-GluR2受体亚单位在CEA神经元突触后部位转运的假说，这一过程可被局部NR1基因缺失所抑制。为了解决这些假设，将在阿片依赖模型的背景下使用最先进的技术，包括空间-时间敲除方法和受体贩运的定量超微结构分析。这些研究应该阐明与吗啡使用相关的行为可塑性和神经可塑性所涉及的关键分子和细胞内过程的作用，从而扩大我们对阿片类药物依赖的神经遗传学和神经解剖学底物的了解。尽管阿片类药物具有临床疗效，但它们的滥用和成瘾倾向是公共卫生问题的一个重要来源。长期使用阿片类药物似乎会在边缘大脑区域参与一个复杂的信号分子网络，特别是谷氨酸受体，这些区域会产生与正常学习和记忆有关的神经变化。利用最先进的分子药理学和神经解剖学技术，这项提议将确定谷氨酸受体在阿片类药物依赖的特定大脑通路中的作用。通过阐明调节依赖不良后果的神经生物学过程，我们可能会提供必要的关键信息，以开发减少这些有害行为的药物干预措施。

DESCRIPTION (provided by applicant): Opioid dependence is characterized by negative physiological and psychological symptoms that arise following termination of drug exposure. Since these symptoms can be relieved or avoided by continued drug use, dependence contributes to the cycle of addiction. While the neural substrates of dependence are poorly understood, evidence is emerging that functional ionotropic (NMDA and AMPA) glutamate receptors in the central amygdala (CeA) play a critical role in this form of opioid-dependent plasticity. Studies conducted during the PI's current Research Scientist Development Award have shown that Cre-loxP technology can be used to delete the NMDA-NR1 (NR1) receptor subunit gene in CeA neurons and prevent morphine withdrawal-induced aversion, without affecting physical symptoms. The goal of the present proposal is to expand on these findings by testing the following global hypothesis: Central amygdala NMDA receptors play critical roles in both conditioned aversion and AMPA receptor plasticity associated with opioid dependence. This hypothesis will be addressed by the following Specific Aims: Aim 1 will test the hypothesis that CeA knockout of NR1 will produce a specific inhibition of opioid withdrawal aversion. Aim 2 will examine the hypothesis that mu-opioid receptors (OR) and ionotropic glutamate receptors are co-localized in dendrites and dendritic spines (i.e. postsynaptically) in CeA neurons. Aim 3 will test the hypothesis that acute opioid exposure can affect the trafficking of the AMPA-GluR2 receptor subunit at postsynaptic sites in CeA neurons, a process that can be inhibited by local NR1 gene deletion. To address these hypotheses, state-of-the-art technology, including spatial-temporal knockout methods and quantitative ultrastructural analysis of receptor trafficking, will be employed within the context of models of opioid dependence. These studies should elucidate the role of key molecules and intracellular processes involved in both behavioral and neural plasticity associated with morphine use, thus expanding our knowledge of the neurogenetic and neuroanatomical substrates of opioid dependence. Despite the clinical efficacy of opioids, their abuse and addictive liability are a significant source of public health problems. Chronic use of opioids appear to engage a complex network of signaling molecules, particularly glutamate receptors, in limbic brain regions that produce neural changes similar to those involved in normal learning and memory. Using state of the art molecular pharmacological and neuroanatomical techniques, this proposal will identify the role of glutamate receptors in opioid dependence in specific brain pathways. By elucidating the neurobiological processes that mediate the adverse consequences of dependence, we may provide critical information needed to develop pharmacological interventions for reducing these deleterious actions.