孕酮对吗啡精神依赖大鼠相关脑区中强啡肽A水平的影响

目的:观察孕酮对于吗啡所致奖赏效应及相关脑区中强啡肽A水平的影响。方法:建立吗啡条件性位置偏爱(CPP)模型,采用放射免疫法测定大鼠不同脑区中强啡肽A(dynorphinA,DynA)的含量。结果:与生理盐水对照组比较,5mg·kg-1吗啡可诱导大鼠产生稳定的CPP效应(P<0·01),15mg·kg-1孕酮本身不产生CPP效应,但能抑制吗啡CPP效应的获得。与生理盐水对照组比较,吗啡CPP形成时,下丘脑和额叶皮质中的DynA水平显著降低(P<0·05)。与吗啡组比较,合用15mg·kg-1孕酮可使下丘脑和额叶皮质中DynA水平显著升高(P<0·05),而在海马、伏隔核和中脑内未见显著性变化。结论:孕酮可以有效抑制吗啡CPP效应,其机制可能与其逆转吗啡诱导的相关脑区中的DynA水平的变化有关。

EFFECTS OF PROGESTERONE ON MORPHINE-INDUCED PSYCHOLOGICAL DEPENDENCE AND LEVELS OF DYNORPHIN A IN RAT BRAIN

Objective:To investigate the effects of progesterone on morphine rewarding effect and levels of dynorphin A (DynA) in rat brain. Methods:Conditioned place preference (CPP) test was used to investigate morphine rewarding effect,and radioimmunoassay (RIA) was established to determine the levels of DynA in rat brain. Results:Compared with NS control group,morphine 5 mg·kg-1 successfully induced the formation of CPP (P<0.01). Progesterone 15 mg·kg-1 was not able to induce CPP effect itself,but abolished the morphine CPP effect. Compared with NS control group,the levels of DynA following morphine administration decreased in hypothalamus and frontal cortex (P<0.05). Compared with morphine group,the levels of DynA increased by co-administration with 15 mg·kg-1 progesterone in hypothalamus and frontal cortex (P<0.05). Conclusion:It is speculated that progesterone could attenuate morphine induced CPP effectively. The effect of progesterone on morphine induced CPP could be conduced through its action on DynA.