Suppressive effect of L-dopa on human prolactin release during sleep.

Immunoreactive plasma human prolactin (HPr) and human growth hormone (HGH) concentrations were measured in six normal young men with polygraphic sleep monitoring during normal sleep and during sleep in which l-dihydroxyphenylalanine (l-DOPA) was infused intravenously at a rate of 0.8 to 1.0 mg/min. The intravenous infusion of l-DOPA significantly suppressed the episodic release of HPr during sleep and the occurrence of rapid eye movement (REM) sleep. However, HGH release during sleep was not remarkably influenced by l-DOPA. These results suggest that central catecholaminergic neural mechanisms are related to both sleep-related HPr release and REM sleep, but do not play an important role in sleep-related HGH release.