静寂突触介导的边缘下区皮质到伏隔核壳部谷氨酸能投射通路可塑性在雷米芬太尼戒断期中的变化

Silent synapses are thought to be immature glutamatergic synapses containing stable NMDA receptors (NMDARs), while AMPA receptors (AMPARs) are either absent or highly labile. Exposure to cocaine induces the generation of silent synapses in NAcSh in rats. It has been reported that NR2B-containing NMDA receptors (NMDAR) is involved in morphine addiction. However, it is still unknown whether silent synapses mediate opiate addiction. The present project is designed to measure the levels of silent synapses in the glutamatergic project from infralimbic cortex (IL)to shell compartment of nucleus accumbens (NAcSh) 1 day and 45 days, respectively, after intravenous self-administration of remifentanil, a selective agonist of u-opioid receptors. Optogenetics, whole-cell patch clamp, stereotaxic microinjections of virus (AAV-ChR2-YFP) and neuropharmacological strategies will be applied. After establishment of the opiate addiction model in rats by self-administration of remifentanil combining the extinction test in early and later withdrawal periods, the changes of silent synapses in the IL-NASh projection will be evaluated, and the involvement of NR2B-containing NMDARs in the upregulated level of silent synapses will be explored. This project will illustrate the involvement of silent synapses in different time course of opiate addiction in the cellular and synaptic levels. Our results may provide new targets at the certain neural pathway in preventing and treating opiate addiction.

静寂突触是含有稳定的NMDAR而AMPAR缺乏或高度不稳定的谷氨酸能突触。可卡因成瘾可诱发大鼠伏隔核壳部（NAcSh）形成静寂突触。吗啡成瘾与含NR2B的NMDAR有关，而阿片类药物成瘾机制是否有静寂突触参与，尚未见报道。本课题利用光遗传学技术、全细胞膜片钳记录、脑部微量注射和神经药理学等手段，在边缘下区皮质（IL）注射整合光敏感通道ChR2和黄色荧光蛋白YFP的腺病毒（AAV-ChR2-YFP），选用代谢快的u阿片受体激动剂雷米芬太尼，经静脉自身给药训练模拟阿片成瘾，测试戒断第1天和戒断第45天大鼠对药物的渴求水平；评估相应时程中，大鼠IL-NAcSh谷氨酸能投射通路中静寂突触水平的变化；探讨静寂突触的产生是否与含NR2B的NMDAR有关；在细胞和突触水平上明确阿片类药物戒断不同时间的机制，阐明静寂突触在阿片类药物成瘾中的作用。研究成果将为药物成瘾的防治提供具有神经通路特异性的新靶点。

本课题利用光遗传学技术、全细胞膜片钳记录、脑部微量注射和神经药理学等手段，在边缘下区皮质（IL）微量注射整合光敏感通道ChR2和黄色荧光蛋白YFP的腺病毒（AAV-ChR2-YFP），经静脉自身给药吗啡，在细胞和突触水平上明确阿片戒断不同时间与静寂突触的关系，阐明静寂突触在吗啡成瘾中的作用。研究成果将为药物成瘾的防治提供具有神经通路特异性的新靶点。.1. 大鼠在IL脑区注射表达ChR2的AAV后21 d，进行吗啡自给药训练。吗啡戒断45 d时的鼻触有效给药次数明显高于戒断1 d组。这一结果表明，吗啡戒断45 d大鼠对于线索诱发的药物渴求程度比戒断1 d明显增加。.2. 吗啡戒断1 d大鼠，在伏隔核壳部 (nucleus accumbens, NAcsh)的中等棘状神经元，经最小强度的激光刺激，可记录到静寂突触，且明显高于对照组。戒断45 d后静寂突触回到基线水平，与生理盐水组相比无明显差别。.3. 在戒断45 d大鼠脑表面灌流NR2B拮抗剂Ro256981，可使NAcsh的中等棘状神经元上静寂突触回到基线水平，与生理盐水组比较无明显差别。表明吗啡慢性戒断期（戒断45 d）静寂突触的成熟与NR2B亚型有关。. 以上结果表明，IL-NAc的谷氨酸能投射通路所介导的静寂突触参与吗啡戒断急性期和慢性期的形成，静寂突触的产生和含NR2B亚型的NMDA受体有关。