Possible Contribution of Melatonin to the Timing of the Luteinizing Hormone Surge

Abstract
To the Editor: Marshall and Kelch were asked during the discussion that followed their seminar (Dec. 4 issue)1 about factors in the central nervous system that may contribute to the timing of the luteinizing hormone (LH) surge. Dr. Marshall replied that "some central mechanism in the rat clearly increases either the frequency or the amount of GnRH [gonadotropin-releasing hormone] secreted in the early evening. There is no evidence of such a daily signal in humans." On the contrary, such a factor has been clearly demonstrated in many mammals and may also apply to humans.Melatonin, the hormone secreted by the . . .