哌替啶镇痛作用的昼夜节律

对小鼠采用4种光照方案以及热板测痛法,证明生理基础痛阈和哌替啶的镇痛效力均有明显的光暗差异,在标准光照周期中,二者的峰值均出现于黑暗时相,光照可使痛阈降低。摘除松果体后,上述昼夜节律消失。给小鼠注射褪黑激素后小剂量哌替啶的镇痛作用增强。这些结果提示,哌替啶镇痛作用的昼夜节律受松果体褪黑激素的调节,并可能与其促进内源性阿片肽的释放有关。

The Diel Rhythm of Pethidine--induced Analgesia in Mice

Under alternating standard light--dark cycle (L: D=12: 12), diel rhythms in baseline pain threshold and pethidine-induced analgesia were observed in mice. Darkness increased and lighting decreased the pain threshold with the crest and trough occurring at mid-dark and mid-light phases. Daynight variations in both basal and pethidine--induced analgesia were abolished by pinealectomy in mice kept under standard lighting. Melatonin (100mg/kg, ip) inhibited the responses to painful stimuli in hot plate tests. In pinealectomized mice, the pretreatment with a low dose (5mg/kg, ip) melatonin potentiated significantly the level of analgesia induced by pethidine (10rog/kg), and that of melatonin was decreased by naloxone. The results suggest that the pineal gland and melatonin are involved in regu- lating pethidine--elicited diel rhythm and may contribute to the activation of endogenous opioid peptides secretion.