褪黑素对大鼠中脑导水管周围灰质内阿片肽释放的影响

本文采用推挽灌流技术、放射免疫测定法,观察褪黑素（ｍｅｌａｔｏｎｉｎ,ＭＥＬ）对大鼠中脑导水管周围灰质（ＰＡＧ）推挽灌流液中β－内啡肽（β－Ｅｐ）、亮氨酸脑啡肽（Ｌ－ＥＫ）含量的影响,以探讨ＭＥＬ镇痛效应的中枢机制。结果显示,给药组大鼠腹腔注射（ｉｐ）ＭＥＬ１１０ｍｇ／ｋｇ后３０－５０ｍｉｎ,ＰＡＧ灌流液中β－Ｅｐ含量显著增加,而Ｌ－ＥＫ含量未见显著变化;在推挽灌流同时用５０℃热水刺激甩尾法测定痛

Melatonin influences the release of endogenous opioid peptides in rat periaqueductal gray

The present study was undertaken to explore central mechanisms underlying the analgesic effect of melatonin. Push-pull perfusion technique and radioimmunoassay were used to observe the changes in the contents of beta-endorphin (beta-Ep) and leucine-enkephalin (L-EK) in the perfusate from the rat periaqueductal gray (PAG) after administration of melatonin. 30 50 min after an intraperitoneal injection of melatonin (110 mg/kg), the beta-Ep content in the perfusate was increased significantly, while the L-EK content was not changed. Pain threshold was measured using the warm water tail-flick test during the push-pull perfusion of the PAG. It was found that the rat pain threshold was increased significantly 40 min after the intraperitoneal injection of melatonin (110 mg/kg). The results suggest that melatonin may promote the release of beta-Ep in the PAG, which may be one of the mechanisms of the analgesic effect of melatonin.