A central nervous system component of epinephrine hyperglycemia

Abstract

At least half the hyperglycemic response (in hepatic venous blood) to intravenous epinephrine was found to be dependent on the integrity of the medulla oblongata caudal to the cerebellar peduncles. Transection of the medulla at the level of the fovea inferior unmasked a vagus-mediated hypoglycemic response to epinephrine. Changes in blood glucose concentration after epinephrine administration were independent of blood pressure and the base-line blood glucose levels. Microinjections of epinephrine into the floor of the fourth ventricle initiated an immediate hyperglycemic response without affecting blood pressure. It is concluded that only half the hyperglycemic response to epinephrine is due to direct peripheral action of epinephrine. The balance of the response is initiated by epinephrine-sensitive receptors in a hyperglycemic center in the floor of the fourth ventricle.