Clonidine lowers α-MSH-like immunoreactivity in human plasma

Abstract

In a group of seven healthy subjects, the effects of acute intravenous administration of clonidine, a selective α2 receptor stimulator, on plasma α-MSH-LI concentrations were measured. In comparison with saline, clonidine (0.075 mg) significantly reduced α-MSH-LI concentrations, with a maximum fall between 30 and 60 min., followed by a return to basal concentrations at 120 min.; no significant variations in plasma ACTH and cortisol were seen. The precise mechanism of this effect is unclear. Our study suggests that separate regulatory mechanisms exist for the secretion of POMC related peptides in the corticotroph and melanotroph cells of the human pituitary gland.