Neuroendocrine control of basal insulin secretion in man: a study with bromocriptine, clonidine and naloxone.

The effects of bromocriptine (CB-154, 2.5 mg po), clonidine (0.05 mg im) and naloxone (0.4 mg im), as well as the interaction between naloxone and CB-154 or clonidine on basal insulin secretion were studied in 6 normal men. Clonidine, naloxone and CB-154 plus naloxone lowered insulin plasma levels; CB-154 alone caused only a slight reduction, whereas clonidine plus naloxone did not affect insulin secretion. These results prove the existence of a complex neuroendocrine control of basal insulin secretion through dopaminergic, adrenergic and opiate mechanisms; they also suggest that the opiate inhibitory control of insulin release may be dissociated from the dopaminergic one, but may interact with the adrenergic one.