Sutin E L, Kilduff T S
Department of Psychiatry, Stanford University School of Medicine, CA 94305.
Brain Res Mol Brain Res. 1992 Oct;15(3-4):281-90. doi: 10.1016/0169-328x(92)90119-v.
Recent work has suggested that immediate early genes are involved in the phase-shifting response of the circadian pacemaker to light. In mammals, the endogenous pacemaker is located in the suprachiasmatic nucleus (SCN). We report here a systematic examination of the expression of the immediate early genes fos, NGFI-A, and NGFI-B in the rat SCN, in basal and light-stimulated conditions across the circadian cycle. The photic induction of all three genes examined was found to be gated by the circadian system with maximal induction observed during the mid to late subjective night. The photic-induced expression of NGFI-B in the SCN was considerably less than that of NGFI-A, despite previous observations suggesting greater induction of NGFI-B by membrane depolarization. The levels of immediate early gene expression induced by light do not directly correspond to the magnitude of previously reported light-induced phase-shifts of the activity rhythm. The results also suggest that fos may undergo a circadian rhythm of expression in the rat SCN.
近期研究表明，即刻早期基因参与了昼夜节律起搏器对光的相移反应。在哺乳动物中，内源性起搏器位于视交叉上核（SCN）。我们在此报告一项关于大鼠SCN中即刻早期基因fos、NGFI - A和NGFI - B在昼夜周期的基础状态和光刺激条件下表达的系统研究。结果发现，所检测的这三个基因的光诱导受昼夜节律系统调控，在主观夜的中晚期观察到最大诱导。尽管先前有观察表明膜去极化对NGFI - B的诱导作用更强，但SCN中光诱导的NGFI - B表达远低于NGFI - A。光诱导的即刻早期基因表达水平与先前报道的光诱导活动节律相移的幅度并不直接对应。结果还表明，fos在大鼠SCN中可能存在表达的昼夜节律。
