Effects of Melatonin on c-fos Expression in Suprachiasmatic Nucleus in Rats

Objective To investigate the effects of exogenous melatonin(MT) on the c-fos expression in suprachiasmatic nucleus (SCN) of rats. Methods MT was injected to rats subcutaneously at different times of a day under normal light-dark (LD=12∶12) condition and constant darkness (DD). Circadian changes of the c-fos expression in SCN were examined. Results The expression of c-fos in SCN showed a circadian rhythm under LD as well as DD. In the LD group, the circadian rhythm changed more evidently than that in the DD group. In both the LD and DD group, the mesors of circadian rhythm increased significantly compared with the control group. Conclusion Exogenous MT could induce the c-fos expression in SCN of rats and change the circadian rhythm of the c-fos activity.