摘除松果体对踏转轮运动昼夜节律及脑内c-fos表达的影响

目的　探讨松果体调节昼夜节律的作用机制。方法　在持续黑暗条件下 ,2 4h记录大鼠的踏转轮运动 ,观察其昼夜节律性变化 ,同时用免疫细胞化学方法 ,检测视交叉上核 (SCN)中光诱导的Fos蛋白的表达。结果　摘除松果体后 ,踏转轮运动白天少黑夜多的昼夜节律消失 ,Fos蛋白表达减少 ;补充褪黑素后能使之恢复。褪黑素 1(ML 1)受体拮抗剂Luzindole也能使踏转轮运动的昼夜节律消失和Fos蛋白表达减少。而ML 2受体拮抗剂Prazosin则不能。结论　松果体通过分泌褪黑素作用于SCN中的ML 1受体 ,从而调节踏转轮运动的昼夜节律性

Effects of Pinealectomy on the Wheel-Running Circadian Rhythm and c-fos Expression in Suprachiasmatic Nucleus

Objective To explore the mechanism of regulation of pineal body on circadian rhythm.Methods Under constant dark condition the wheelrunning activity was recorded in rats during 24 h to examine the circadian change. The Fos protein expression in suprachiasmatic nucleus induced by illumination was examined immunocytochemically.Results After pinealectomy the wheelrunning circadian rhythm, characterized by more activities in the subjective night than in the subjective day, disappeared and the Fos protein expression decreased. These effects of pinealectomy were recovered by administration of melatonin. The wheelrunning circadian rhythm also disappeared and the Fos protein expression also decreased after injection of melatonin1 receptor antagonist Luzindole, but that effects were not observed after injection of melatonin2 receptor antagonist Prazosin.Conclusion The regulatory effect of pineal body on wheelrunning circadian rhythm is mediated by the melatonin released, which, in turn, interacted with melatonin1 receptor in suprachiasmatic nucleus.