Effects of naloxone on the insulin and GH responses to alpha-adrenergic stimulation with clonidine.

To find if endorphins can influence hormonal responses mediated by noradrenergic pathways, we examined the effects of naloxone, an opiate receptor blocker, on the GH and insulin responses to clonidine, a drug which acts by stimulation of alpha-adrenergic receptors. Intravenous clonidine (0.15 mg in 10 min) induced a significant fall of plasma insulin and a marked increase of plasma GH. Intravenous naloxone (bolus of 1.6 mg followed by 50 micrograms/min) did not change the insulin response to clonidine, and seemed to induce only a slight delay in the GH response.