title: Melatonin regulation in humans with color vision deficiencies.
abstract: Light can induce an acute suppression and/or circadian phase shift of plasma melatonin levels in subjects with normal color vision. It is not known whether this photic suppression requires an integrated response from all photoreceptors or from a specialized subset of photoreceptors. To determine whether normal cone photoreceptor systems are necessary for light-induced melatonin suppression, we tested whether color vision-dificient human subjects experience light-induced melatonin suppression. In 1 study, 14 red-green color vision-deficient subjects and 7 normal controls were exposed to a 90-min, 200-lux, white light stimulus from 0200-0330 h. Melatonin suppression was observed in the controls (t = -7.04; P < 0.001), all color vision-deficient subjects (t = -4.76; P < 0.001), protanopic observers (t = -6.23; P < 0.005), and deuteranopic observers (t = -3.48; P < 0.05), with no significant difference in the magnitude of suppression between groups. In a second study, 6 red/green color vision-deficient males and 6 controls were exposed to a broad band green light stimulus (120 nm with lambda max 507 nm; mean +/- SEM, 305 +/- 10 lux) or darkness from 0030-0100 h. Hourly melatonin profiles (2000-1000 h) were not significantly different in onset, offset, or duration between the two groups. Melatonin suppression was also observed after exposure to the green light source at 0100 h (color vision deficient: t = -2.3; df = 5; P < 0.05; controls: t = -3.61; df = 5; P < 0.01) and 0115 h (color vision deficient: t = -2.74; df = 5; P < 0.05; controls: t = -3.57; df = 5; P < 0.01). These findings suggest that a normal trichromatic visual system is not necessary for light-mediated neuroendocrine regulation.
authors.affiliation: Department of Neurology, Jefferson Medical College, Philadelphia, Pennsylvania 19107, USA.
authors.forename: F L
authors.initials: FL
authors.lastname: Ruberg
authors.forename: D J
authors.initials: DJ
authors.lastname: Skene
authors.forename: J P
authors.initials: JP
authors.lastname: Hanifin
authors.forename: M D
authors.initials: MD
authors.lastname: Rollag
authors.forename: J
authors.initials: J
authors.lastname: English
authors.forename: J
authors.initials: J
authors.lastname: Arendt
authors.forename: G C
authors.initials: GC
authors.lastname: Brainard
mesh_terms: D000328:Adult; D002940:Circadian Rhythm / Q000528:radiation effects; D003117:Color Vision Defects / Q000097:blood*; D003624:Darkness; D005260:Female; D006801:Humans; D008027:Light; D008297:Male; D008550:Melatonin / Q000037:antagonists & inhibitors / Q000097:blood*; D009490:Neurosecretory Systems / Q000503:physiopathology / Q000528:radiation effects; D009994:Osmolar Concentration; D012016:Reference Values
chemical_list: D008550:Melatonin