Melatonin, The Pineal Gland and Circadian Rhythms.

This research tests the null hypothesis that the restricted phase of melatonin sensitivity in rats is at least partially due to a coincidence of the time at which exogenous melatonin is administered and the time at which endogenous melatonin begins to rise. Results suggest that the cerebral moiety responding to melatonin presumably the SCN responds to it quantally within a very restricted phase, and that this effect is independent of the pineal gland. Pinealectomy had no effect on the binding pattern, affinity or capacity within either the SCN or the pars tuberalis.