杏仁核调控阿片类药物成瘾记忆再巩固的DNA甲基化机制

Drug-related positive and aversive memories are hypothesized to underlie the high relapse rate in addiction. Upon retrieval, established memories enter a transiently state called reconsolidation, which is important for the persistent maintain of addiction memories. Recent evidence indicate that gene expression play a critical role in reconsolidation, but the underlying mechanisms remain poorly understood. The DNA methylation, a stable epigenetic modification, may persistently influence gene expression and may be crucial for persistent nature of addiction memory. Therefore, focus on amygdala, one of the most important brain region for the reconsolidation of drug-related memories, the present proposal seeks to test this idea. We will use conditioned place preference and conditioned place aversion model to examine the effects of DNA methylation in the different subregions of amygdala on the reconsolidation of opiate-related memories. In addition, electrophysiological method will be used to reveal the role of synaptic plasticity in this process. Moreover, we will test if PP1 and PP2B were the target genes of DNA methylation. The present investigation will not only advance our understanding of opiate addiction but also expand our comprehension of the neural mechanisms of drug addiction memory longstanding.

药物成瘾相关的正性和负性情绪记忆长期存在，这被认为是成瘾高复吸率的内在原因。成瘾记忆提取后的再巩固过程是记忆长久保持的重要加工阶段。已有研究表明再巩固需要基因转录的长时程改变，但其调控机制还不清楚。DNA甲基化是一种较稳定的表观遗传学修饰，可能持续影响基因的转录和表达，从而调控成瘾记忆的再巩固。本研究拟从这一假设出发，选择调控成瘾记忆再巩固的关键脑区杏仁核，以大鼠条件位置偏爱和条件位置厌恶为行为模型，比较研究杏仁核不同亚区的DNA甲基化在调控成瘾正性和负性情绪记忆再巩固中功能的异同，并利用膜片钳技术，研究DNA甲基化影响成瘾记忆再巩固的突触可塑性机制，此外还将利用分子生物学和生物化学的方法，探索蛋白磷酸酶基因PP1和PP2B是否是DNA甲基化的靶基因。从而为认识药物成瘾记忆再巩固的分子机制提供新证据，为防治药物成瘾提供新的思路。

药物成瘾相关的正性和负性情绪记忆长期存在，这被认为是成瘾高复吸率的内在原因。成瘾记忆提取后的再巩固过程是记忆长久保持的重要加工阶段。已有研究表明再巩固需要基因转录的长时程改变，但其调控机制还不清楚。本课题以大鼠条件位置偏爱和条件位置厌恶为行为模型，结合行为药理、分子生物学、DNA甲基化检测、病毒转染过表达等方法，比较研究杏仁核不同亚区的DNA甲基化在调控成瘾正性和负性情绪记忆再巩固中功能的异同，并探索催化DNA甲基化的关键酶以及修饰的靶基因。研究结果发现：（1）抑制岛叶AI（而非GI）亚区中的DNA甲基化破坏吗啡戒断相关负性情绪记忆再巩固；（2）抑制基底外侧杏仁核（BLA，而非中央杏仁核，或伏隔核）中的DNA甲基化破坏吗啡奖赏记忆再巩固；（3）BLA中DNMT3a和DNMT3b在吗啡奖赏记忆再巩固过程中显著上调，基因GNAS的启动子区域甲基化水平显著上调，GNAS转录水平下调，过表达GNAS破坏再巩固。以上结果提示，基底外侧杏仁核中，DNMT3a和DNMT3b诱导的DNA甲基化可能通过下调GNAS的转录调控吗啡相关的奖赏记忆的再巩固过程。DNA甲基化可能是阿片类药物成瘾记忆再巩固的关键机制。