Effect of cyproheptadine on the spontaneous diurnal variations of plasma ACTH-cortisol and ACTH-GH secretion induced by l-dopa.

Cyproheptadine administration resulted in marked reduction and complete inhibition of the GH and ACTH-cortisol responses to L-dopa in a group of healthy subjects. If this drug acts by antagonizing serotonin, as assumed, this study suggests that serotonin is also involved in L-dopa induced GH and ACTH release.