LIGHT-INDUCED SUPPRESSION OF NOCTURNAL SEROTONIN N-ACETYLTRANSFERASE ACTIVITY IN CHICK PINEAL-GLAND AND RETINA - A WAVELENGTH COMPARISON

Effects of white and monochromatic (blue-434 nm, green-548 nm, and red -614 nm) lights on the nighttime retinal and pineal NAT activity were examined in chicks. The potency of the tested lights to suppress NAT a ctivity was similar for the retina and pineal gland, with a following rank order: white > green > blue greater than or equal to red. The stu died tissues of chick were far less sensitive to pulses of monochromat ic light than the rat pineal gland. The potency of light to decrease p ineal NAT activity of rat was: white > green >> blue > red. Zn chicks, the suppression of the nocturnal NAT activity produced by a short 5-m in pulse of monochromatic light was completely reversible in the pinea l gland, and partially reversible in the retina. Our data suggest the existence of some differences between birds and mammals in terms of se nsitivity and mechanisms involved in the light-induced suppression of melatonin biosynthesis.