AMYGDALA AMPA GLUR2 DELETION AND OPIOID DEPENDENCE

描述（由申请人提供）：阿片类药物依赖是长期使用阿片类药物的主要并发症，会导致成瘾综合症。除了避免戒断症状外，戒断相关线索的体验也可能在吸毒行为中发挥重要作用。因此，阐明介导长期阿片类药物使用不良后果的神经生物学过程，特别是涉及厌恶学习的作用，可能为管理成瘾性疾病提供关键信息。有证据表明，杏仁核中央核 (CeA) 中的离子型 AMPA 型谷氨酸受体可能是阿片类药物依赖的重要分子底物。 AMPA-GluR2 (GluR2) 受体亚基是 AMPA 受体的主要组成部分，决定钙渗透性，与药物依赖性有关，并在 CeA 中表达。表达 AMPA 受体的 GluR2 的活性受到 NMDA 型谷氨酸受体的调节，这些受体本身就是神经和行为适应性的既定分子底物。尽管有这些发现，但没有直接证据表明 CeA 中的 GluR2 基因表达对于阿片类药物依赖的表达是必需的。本申请的主要目标是开发 AMPA-GluR2 受体亚基的时空缺失，以测试中央杏仁核神经元中 GluR2 的突触后表达对于阿片类药物戒断诱导的条件性位置厌恶 (CPA) 所必需的假设。该假设将通过局部显微注射表达 Cre 重组酶的亲神经性腺相关病毒载体，在 floxed GluR2 小鼠的中央杏仁核神经元中产生 GluR2 突触后缺失来进行研究。局部基因缺失的可行性将通过光和电子免疫组织化学以及原位杂交进行测试。 CeA GluR2 缺失的表型效应将通过行为测量来确定，包括戒断诱导的条件性地方厌恶。该项目预计将增强我们对神经元谷氨酸受体基因表达在阿片类药物依赖中的作用的理解，特别是基于 AMPA-GluR2 的小分子或基因治疗的可能价值。尽管阿片类药物具有临床疗效，但其滥用和成瘾倾向是公共卫生问题的重要根源。阿片类药物可能通过激活杏仁核谷氨酸受体产生持久作用，杏仁核谷氨酸受体是在神经可塑性以及学习和记忆中发挥重要作用的分子。利用最先进的分子神经药理学技术，该提案将确定杏仁核中 AMPA 型谷氨酸受体 GluR2 亚基在阿片类药物依赖性方面的作用。通过阐明介导依赖性不良后果的神经生物学过程，我们可以提供开发药物干预措施以减少这些有害行为所需的关键信息。

DESCRIPTION (provided by applicant): Opioid dependence is a major complication of chronic opioid use that contributes to the syndrome of addiction. In addition to the avoidance of withdrawal symptoms, experience of withdrawal-associated cues may also play an important role in drug taking behavior. Thus, elucidating the neurobiological processes that mediate the adverse consequences of chronic opioid use, particularly involving the role of aversive learning, may provide critical information for managing addictive disease. There is evidence that ionotropic AMPA-type glutamate receptors in the central nucleus of the amygdala (CeA) may be important molecular substrates of opioid dependence. The AMPA-GluR2 (GluR2) receptor subunit is a major component of AMPA receptors, determines calcium permeability, has been implicated in drug dependence, and is expressed in the CeA. The activity of GluR2 expressing AMPA receptors is modulated by NMDA-type glutamate receptors, which are themselves, established molecular substrates of neural and behavioral adaptability. Despite these findings, there is no direct evidence that GluR2 gene expression in the CeA is necessary for the expression of opioid dependence. The primary goal of this application is to develop a spatial-temporal deletion of the AMPA-GluR2 receptor subunit to test the hypothesis that postsynaptic expression of GluR2 in central amygdala neurons is necessary for opioid withdrawal- induced conditioned place aversion (CPA). This hypothesis will be investigated by producing a postsynaptic deletion of GluR2 in central amygdala neurons of floxed GluR2 mice via local microinjection of a neurotropic adenoassociated viral vector expressing Cre recombinase. The viability of local gene deletion will be tested by light and electron immunohistochemistry and in situ hybridization. The phenotypic effects of CeA GluR2 deletion will be determined by behavioral measurements, including withdrawal-induced conditioned place aversion. This project is expected to enhance our understanding of the role of neuronal glutamate receptor gene expression in opioid dependence, particularly with respect to the possible value of AMPA-GluR2 based small molecule or gene therapeutics. Despite the clinical efficacy of opioids, their abuse and addictive liabilities are significant sources of public health problems. Opioids may produce their long-lasting effects by activating amygdala glutamate receptors, molecules that play important roles in neural plasticity, as well as learning and memory. Using state of the art molecular neuropharmacological techniques, this proposal will identify the role of the AMPA-type glutamate receptor GluR2 subunit in the amygdala with respect to opioid dependence. 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.