title: Some perturbations that disturb the circadian melatonin rhythm.
abstract: The circadian melatonin rhythm is highly reproducible and generally not easily altered. The few perturbations that are capable of significantly changing either the amplitude or the pattern of the 24-h melatonin rhythm are summarized herein. Aging alters cyclic melatonin production by decreasing the amplitude of the nocturnal melatonin peak in all species in which it has been studied. The best known acute suppressor of nocturnal melatonin is light exposure. The brightness of light required to acutely depress pineal melatonin production is species dependent; of the visible wavelengths, those in the blue range (approximately 500-520 nm) seem most effective in suppressing melatonin production. Nonvisible, nonionizing radiation in the extremely low frequency range (e.g., 60 Hz) seems also capable of altering pineal melatonin synthesis. Hormones have relatively little influence on the circadian production of melatonin, although either adrenalectomy or hypophysectomy does attenuate the amplitude of the melatonin cycle. Exercise at the time of high melatonin production rapidly depresses pineal concentrations of the indole without influencing its synthesis; the mechanism of this suppression remains unknown.
authors.affiliation: Department of Cellular and Structural Biology, University of Texas Health Science Center, San Antonio 78284-7762.
authors.forename: R J
authors.initials: RJ
authors.lastname: Reiter
authors.forename: B A
authors.initials: BA
authors.lastname: Richardson
mesh_terms: D000375:Aging / Q000378:metabolism*; D000818:Animals; D001191:Arylamine N-Acetyltransferase / Q000378:metabolism; D002940:Circadian Rhythm / Q000502:physiology*; D003624:Darkness; D006801:Humans; D007016:Hypophysectomy; D008027:Light; D008550:Melatonin / Q000097:blood / Q000378:metabolism*; D005082:Physical Exertion; D010870:Pineal Gland / Q000502:physiology* / Q000528:radiation effects
chemical_list: D001191:Arylamine N-Acetyltransferase; D008550:Melatonin