目的 :研究褪黑素对吗啡依赖大鼠复吸行为的抑制作用。方法 :以剂量递增法连续皮下注射 (sc)吗啡 6d建立吗啡诱导的大鼠条件性位置偏爱 (CPP)模型 ,d7用生理盐水替代吗啡训练大鼠 10d ,以使形成的CPP逐渐消退。单次sc 4mg·kg- 1 吗啡以唤起消退的CPP的恢复。部分大鼠在注射吗啡前 30min分别腹腔注射 (ip)褪黑素 2 0、4 0和 80mg·kg- 1 进行治疗。结果 :与吗啡依赖组相比 ,在sc 4mg·kg- 1 吗啡引燃刺激前 30min应用褪黑素 4 0和 80mg·kg- 1 急性治疗 ,可以使大鼠在伴药箱的停留时间明显缩短 ,(P <0 0 5、P <0 0 1) ;而褪黑素 2 0mg·kg- 1 急性治疗亦使大鼠在伴药箱的停留时间缩短 ,但无统计学意义 ,P >0 0 5。结论 :褪黑素在一定程度上可以抑制吗啡引燃的吗啡依赖大鼠的复吸行为 Objective: To study the inhibitory effect of melatonin on relapsing behavior in morphine dependent rats. METHODS: Morphine-induced conditioned place preference (CPP) model was established by continuous subcutaneous injection of morphine (morphine) for 6 days. D7 was replaced by morphine for 10 days in rats. The formation of CPP gradually subsided. Single sc 4 ​​mg · kg -1 morphine to evoke recovery of extinct CPP. Some rats were treated with ip melatonin 20, 40 and 80 mg · kg-1 respectively 30 min before morphine injection. Results: Compared with the morphine dependent group, acute treatment with 40 mg and 80 mg · kg -1 of melatonin 30 min before the start of sc 4 ​​mg · kg -1 morphine stimulation could shorten the residence time of the rats in the companion box (P <0.01, P <0.01). However, the acute treatment with 20 mg · kg-1 of melatonin also shortened the stay time of rats in the companion box with no significant difference (P> 0 0) 5. Conclusion: Melatonin can inhibit the relapse behavior of morphine-dependent rats induced by morphine to some extent