吗啡精神依赖大鼠VTA髓鞘不同时程结构变化

The structural changes of myelin of VTA in morphine dependent rats during the different phase

目的观察不同时程吗啡精神依赖大鼠中脑腹侧被盖区(VTA)髓鞘的结构变化。方法将SD大鼠分为6组:吗啡依赖10天组,吗啡依赖10天对照组,吗啡依赖30天组,吗啡依赖30天对照组,脱毒组,脱毒对照组。剂量递增法于大鼠背部皮下注射吗啡,并用条件位置偏爱法观察吗啡精神依赖效应。应用透射电镜对各组大鼠VTA的髓鞘进行观察。结果吗啡依赖10天组大鼠VTA髓鞘板层开始松解,扭曲变形,排列较紊乱,部分结构已经肿胀变性,板层内有空泡形成,但未见脱髓鞘改变;吗啡注射30天组和脱毒组大鼠VTA髓鞘变薄、溶解,并可见典型的脱髓鞘改变;自然戒断20天组,大鼠的精神依赖行为虽然已经消失,但其髓鞘的损伤仍未修复。结论吗啡精神依赖大鼠VTA髓鞘呈进程性损伤,该损伤可能是阿片类药物成瘾后产生吗啡精神依赖的病理学基础之一。

Objective To investigate the structural changes of myelin sheath of ventral tegmental area（VTA） in morphine dependent rats with the different phase.Methods SD rats were divided into 6 groups： 10-days morphine dependent group and its control,30-days morphine dependent group and its control,detoxification group and its control.The rats were injected morphine subcutaneous on increasing dosage and then observed with conditioned place preference（CPP）.The electron microscope was used to study the histomorphologic changes of myelin sheath in VTA.Results In 10-days morphine dependent rats,the lamellar myelin of VTA began to release and distort,and some has been swelled and vacuolated,but there was no demyelination.In 30-days morphine dependent group and detoxification group rats,the myelin of VTA was thinning,dissolved,and typical changes of demyelination.In the detoxification group rats,to withdraw for 20 days,the psychological dependence has disappeared,but the damaged myelin did not get well.Conclusions The myelin was progressive damage in morphine dependent rats,and histomorphologic changes of myelin sheath in VTA might contribute to the development of morphine dependence.