Epinephrine as a potent releaser of immunoreactive beta-endorphin in rats

The intravenous infusion of catecholamines to rats induced a dose dependent increase of immunoreactive beta-endorphin (beta-Endi) in plasma. The ED50 values of 1-epinephrine and 1-isoproterenol were 110 and 100 ng/kg X min respectively. 1-Propranolol, but not d-propranolol prevented the effect of 1-epinephrine. Infusion of 100 ng/kg X min of 1-epinephrine increased plasma epinephrine to 11 pmol/ml, a concentration that can occur during stress. We conclude that circulating catecholamines can stimulate beta-Endi secretion via a beta-adrenergic receptor mechanism and may play a role in the response of beta-Endi to stress.