海洛因作用不同时程诱导大鼠CPP及海洛因依赖大鼠VTA区CREB磷酸化研究

目的:观察不同时程注射海洛因对诱导大鼠条件位置偏爱(conditioned place preference,CPP)行为的影响及其海洛因依赖后大鼠VTA区CREB磷酸化的研究。方法:雄性SD大鼠32只(体重180～220 g),随机分为四组:海洛因依赖8 d组及其对照组,海洛因依赖10 d组及其对照组,每组8只。海洛因依赖组连续腹膜腔注射海洛因每日10 mg/kg,8 d和10 d,对照组注射等量的生理盐水,于训练结束的次日进行CPP检测。模型建立成功后,8 d组大鼠采用Western blot检测VTA区CREB磷酸化的表达。结果:(1)与相应的对照组比较,每日10mg/kg海洛因8、10 d组在伴药箱停留时间均明显延长(P<0.05),而两组大鼠在伴药箱停留时间比较差异无统计学意义。但8 d组更为省药、省时且大鼠无死亡。(2)与对照组比较,海洛因依赖8 d组大鼠VTA区CREB蛋白磷酸化增多(P<0.05)。结论:(1)两种时程均可成功建立大鼠CPP模型,但每日10 mg/kg海洛因8 d组建立的模型更为合适。(2)慢性海洛因给药大鼠VTA区CREB蛋白磷酸化增多。

Differential duration of heroin action for induction of conditioned place preference and changes of CREB phosphorylation in the VTA of heroin dependent rat

Objective: To observe the effects of different time-course of heroin injection on the behaviour of conditioned place preference(CPP) in rats and the change of expression of cAMP response element-binding protein(CREB) phosphorylation in the ventral tegmental area(VTA) of heroin dependent rats.Methods: Thirty-two adult male Sprague-Dawley rats(180-220 g) were randomly divided into 4 groups(n=8):8 days heroin dependent group and its control,and 10 days heroin dependent group and its control.The rats in heroin dependent groups received intraperiatoneal injections of heroin 10 mg/kg/d for 8 days and 10 days,respectively,to induce CPP.Normal saline was injected into rats of the control groups in the same way.The time spent in the drug-paired compartment was observed on the next day after last injecion and training for CPP.In 8 days heroin dependent group,the expression of phosphorylate CREB(P-CREB) in the ventral tegmental area was evaluated by using Western blot.Results:(1) Compared with the corresponding control groups,the time spent in the drug-paired compartments significantly increased in the groups receiving 10 mg/kg 8 d and 10 mg/kg 10 d(P<0.05).However,there were no obvious differences between these two heroin dependent groups.It appears that,in 8 days heroin dependent group,less time consumption and less drug was required.In addition,there were no animal death in 8 days heroin dependent group.(2) In 8 days heroin dependent group,p-CREB level in the VTA was significantly increased than that in its control group.Conclusion:(1) These two different time-course of heroin injections successfully induce the CPP model.But,the injections of heroin 10 mg/kg/d for 8 days is a more appropriate method to establish the CPP model;(2) Chronic treatment with heroin enhanced the CREB phosphorylation in rat VTA neurons.