褪黑素对吗啡依赖大鼠复吸行为的影响

目的 建立大鼠条件性位置偏爱模型(CPP),探讨褪黑素对吗啡依赖大鼠复吸行为的影响。方法连续6d按剂量递增法于大鼠皮下注射吗啡,诱导实验组和吗啡对照组大鼠CPP形成,然后用盐水替代吗啡皮下注射大鼠10d,使CPP逐渐消退后,再用吗啡4mg/kg单次引燃注射激发消退的条件性位置偏爱复燃,3个实验组分别在注射吗啡前30min腹腔注射褪黑素20mg/、40mg/kg和80mg/kg,分别观察各组大鼠行为。结果 经6d吗啡训练后,实验组和吗啡对照组大鼠在伴药箱的停留时间显著延长,吗啡诱导的大鼠CPP形成;停用吗啡后,经10d的生理盐水注射,吗啡诱导的大鼠CPP逐渐消退;吗啡4mg/kg单次引燃注射使大鼠消退的CPP恢复,而实验组可以剂量依赖性地减弱大鼠CPP恢复。结论 吗啡诱导大鼠CPP形成,褪黑素在一定程度抑制吗啡依赖大鼠的复吸行为。

Effect of melatonin on reinstatement of relapse behavior in morphine-dependent Rat

Objective To establish the conditioned place preference (CPP) model in rats and to explore the effects of melatonin (MT) on relapse behavior in morphine-dependent rats. Methods After morphine was administered via subcutaneous injection with gradually increasing doses for 6 days to induce morphine CPP in morphine control and treatment groups, the rats were subjected to saline instead of morphine for 10 days to extinct the previous CPP. The rats were then given a single priming injection of morphine 4 mg/kg to reinstate the CPP. Three treatment groups were treated with melatonin (20mg/kg, 40mg/kg and 80mg/kg, ip) prior to priming injection of morphine. The behaviors of rats were observed. Results After training with injection of morphine for 6 days, there were marked increases in time spent in the drug-paired compartment in morphine control and treatment groups and the morphine CPP was established. The morphine CPP disappeared following a 10 day drug-free period and appeared again after given a single injection of morphine 4 mg/kg. During the relapse phase, acute treatment with melatonin 30 min before priming injection of morphine had dose-dependent effects to attenuate the reacquisition of the place preference induced by morphine. Conclusion Morphine could induce the CPP in rats. MT could partly inhibit reinstatement of relapse behavior to morphine in morphine-dependent rats.