title: Light suppression of melatonin in the squirrel monkey (Saimiri sciureus).
abstract: This study examined plasma melatonin levels and the suppressant effect of light on melatonin production in the squirrel monkey. Monkeys were maintained on a 12:12 light-dark cycle (LD 12:12) with lights on from 07:00 to 19:00. Plasma levels of melatonin were determined by gas chromatography negative chemical ionization mass spectrometry. Melatonin levels at 00:00 (99.5 +/- 18.9 pg/ml) were significantly higher than at 02:00 (57.21 +/- 7.7 pg/ml; Student's t = 2.859; P less than or equal to 0.021). Baseline values at 02:00 were compared with levels at the same time of day after exposure to 2 hours of 200 lux of light (30.6 +/- 13.1 pg/ml), which caused an average suppression of 54.8% in melatonin levels. One animal did not show light suppression. Results indicated that the squirrel monkey suppressant response to light, as well as baseline values of melatonin, varied between animals.
authors.affiliation: Department of Animal Physiology and California Primate Research Center, University of California, Davis 95616.
authors.forename: T M
authors.initials: TM
authors.lastname: Hoban
authors.forename: A J
authors.initials: AJ
authors.lastname: Lewy
authors.forename: C A
authors.initials: CA
authors.lastname: Fuller
mesh_terms: D000818:Animals; D002940:Circadian Rhythm; D008401:Gas Chromatography-Mass Spectrometry; D008027:Light; D008297:Male; D008550:Melatonin / Q000097:blood* / Q000378:metabolism / Q000528:radiation effects; D012453:Saimiri
chemical_list: D008550:Melatonin