Continuous light paradoxically reduces catecholamine-induced melatonin production

Exposure of rats to continuous light for 14 days reduced the stimulation of melatonin content in the pineal gland produced by either isoproterenol administration or exposure to darkness. Since continuous light has been reported to enhance many intermediate biochemical events leading to the synthesis of melatonin, these results demonstrate the importance of examining the endproduct of an organ when evaluating the physiological significance of biochemical changes in model biological systems.