Rationale

Epigenetic regulation has been implicated in the incubation of drug craving (the time-dependent increase in drug seeking after prolonged withdrawal from drug self-administration). There is little information available on the role of microRNAs in incubation of heroin craving.

Objective

This study aimed to investigate the roles and mechanisms of miR-181a and methyl CpG binding protein 2 (MeCP2) in the nucleus accumbens (NAc) in incubation of heroin seeking.

Methods

MiRNA sequencing was used to predict potential miRNAs, and miRNA profiles were performed in the NAc after 1 day or 14 days after withdrawal from heroin self-administration. Following 14 days of heroin self-administration, rats were injected of lentiviral vectors into the NAc and evaluated for the effects of overexpression of miR-181a or knockdown of MeCP2 on non-reinforced heroin seeking after 14 withdrawal days.

Results

Lever presses during the heroin-seeking tests were higher after 14 withdrawal days than after 1 day (incubation of heroin craving). miR-181a expression in NAc was lower after 14 withdrawal days than after 1 day, and meCP2 expression in NAc was higher after 14 days than after 1 day. Luciferase activity assay showed that the 3′UTR of MeCP2 is directly regulated by miR-181a. Overexpression of miR-181a in NAc decreased heroin seeking after 14 withdrawal days and decreased MeCP2 mRNA and protein expression. Knockdown of MeCP2 expression in NAc by LV-siRNA-MeCP2 also decreased heroin seeking after 14 withdrawal days.

Conclusions

Results indicate that incubation of heroin craving is mediated in part by time-dependent decreases in NAc miR181a expression that leads to time-dependent increases in MeCP2 expression. Our data suggest that NAc miR-181a and MeCP2 contribute to incubation of heroin craving.

中文翻译：

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伏伏核microRNA-181a和MeCP2在雄性大鼠海洛因渴望培养中的作用

基本原理

表观遗传学调控与药物渴望的孵化有关（长期退出药物自我给药后，寻求药物的时间依赖性增加）。关于微RNA在海洛因渴望培养中的作用的信息很少。

客观的

本研究旨在调查伏隔核（NAc）中miR-181a和甲基CpG结合蛋白2（MeCP2）在寻找海洛因的过程中的作用和机制。

方法

使用miRNA测序来预测潜在的miRNA，并在退出海洛因自用后1天或14天后在NAc中进行miRNA谱分析。自服用海洛因14天后，将大鼠慢病毒载体注射到NAc中，并评估停药14天后miR-181a的过表达或MeCP2敲低对非增强型海洛因的影响。

结果

戒断14天后，海洛因搜寻试验中的杠杆压力高于1天（孵化海洛因后的渴望）。停药14天后，NAc中的miR-181a表达低于1天，而14天后NAc中的meCP2表达高于1天。萤光素酶活性分析表明，MeCP2的3'UTR受miR-181a直接调控。在停药14天后，NAc中miR-181a的过表达减少了海洛因的寻找，并降低了MeCP2 mRNA和蛋白质的表达。LV-siRNA-MeCP2抑制NAc中的MeCP2表达也减少了14天停药后的海洛因搜寻。

结论

结果表明，海洛因渴望的孵化部分是由NAc miR181a表达的时间依赖性降低介导的，该时间依赖性降低导致MeCP2表达的时间依赖性增加。我们的数据表明，NAc miR-181a和MeCP2有助于培养海洛因渴望。