吗啡戒断期基底脑桥核到小脑颗粒细胞环路特异性谷氨酸能突触传递的变化

Cerebellar granule cells (GR) and basal ganglia (BPN) neural circuits play an important role in regulating addiction-related behaviors. NMDA receptors (NMDARs) and μ opiate receptors are proposed to be involved in re-establishing the homeostasis during and after opioid exposure. Our very recent data showed that morphine chronic exposure down regulatedμopiate receptor function whereas upregulated NMDAR function. However, the exact mechanisms are still unknown. The present project is designed to measure the changes of EPSCs in the BPN-GR glutamatergic projection 1 day and 14 days, respectively, after intravenous self-administration of morphine. 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 mice by self-administration of morphine combining the extinction test in early and later withdrawal periods, the changes of EPSCs in the BPN-GC projection will be evaluated, and the involvement of μopiate receptors and NMDARs as well as the relationship in between will be explored. This project will illustrate the involvement of cerebellar GR in different time course of opiate addiction in the cellular and synaptic levels. Our results may provide new targets to the clinics for the presentation and treatment of opiate addiction.

小脑颗粒细胞（GR）与基底脑桥核（BPN）神经环路对于药物成瘾行为具有重要的调控作用。NMDA受体(NMDAR)与μ阿片受体共同参与阿片类药物成瘾的稳态调节过程。我们前期研究发现，吗啡急性戒断使苔状纤维（MF）到GR兴奋性传导通路中μ阿片受体功能降低，NMDAR功能增强，但具体作用机制，尚未明确。因此本项目拟利用光遗传学技术、全细胞膜片钳记录、脑部微量注射等手段，在BPN区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），经吗啡自身给药训练模拟阿片成瘾，测试在戒断第1天和戒断第14天，小鼠对药物的渴求水平；评估吗啡戒断不同时间，BPN-GR投射通路中EPSCs的变化；探讨在相应时程中，μ阿片受体对NMDAR介导的BPN-GR兴奋性突触传递的调节作用，比较μ阿片受体和NMDAR在吗啡戒断中的时间依赖性变化。研究成果将为研究吗啡成瘾机制提供新靶点。

小脑颗粒细胞（GR）与基底脑桥核（BPN）神经环路对于药物成瘾行为具有重要的调控作用。NMDA受体(NMDAR)与μ阿片受体共同参与阿片类药物成瘾的稳态调节过程。我们前期研究发现，吗啡急性戒断使苔状纤维（MF）到GR兴奋性传导通路中μ阿片受体功能降低，NMDAR功能增强，但具体作用机制，尚未明确。因此本项目拟利用光遗传学技术、全细胞膜片钳记录、脑部微量注射等手段，在BPN区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），经吗啡自身给药训练模拟阿片成瘾，测试在戒断第1天和戒断第14天，小鼠对药物的渴求水平；结果发现，吗啡戒断14天小鼠对于线索诱发的药物渴求程度与戒断1 天相比明显增加。而通过膜片钳实验评估吗啡戒断不同时间，对BPN-GR的投射通路中NMDA受体电流的影响发现，吗啡戒断1天时NMDA受体电流幅值明显下降，戒断14天时恢复。而μ阿片受体则在戒断1天时出现耐受，戒断14天恢复正常。表明在BPN-GR环路中，伴随μ阿片受体耐受的内稳态重建中上调的NMDAR功能在μ阿片受体耐受逐渐消除的过程中持续存在，从而阻碍了小脑在吗啡戒断晚期的稳态重建，导致吗啡戒断晚期的相关症状。本研究为小脑参与药物成瘾机制以及吗啡成瘾的防治提供具有神经通路特异性和受体特异性的新靶点。