Oxytocin secretion is stimulated by changes in glucose metabolism

Previous studies have shown that infusion of oxytocin into normal dogs increased plasma levels of insulin and glucagon. These responses were accompanied by increased rates of glucose production and overall glucose uptake. The purpose of the present study was to determine whether, conversely, changes in glucose metabolism would result in changes in oxytocin secretion. In normal dogs, injection of insulin (0.1 U/kg/iv) resulted in increased secretion of oxytocin which coincided with the hypoglycemic nadir, and the oxytocin levels remained elevated for the remaining 60 min, during which time plasma glucose levels were returning to normal. In dogs made diabetic with streptozocin, injection of insulin (1 U/kg/iv) evoked increased oxytocin secretion which began as the plasma glucose levels were falling from the control value of 400 mg/dl to about 170 mg/dl; the oxytocin levels remained above initial values for at least 90 min, during which period plasma glucose returned to normal glycemic values. In normal dogs, infusion of 2-deoxyglucose, which causes intracellular glucopenia, caused a prompt and sustained increase in plasma oxytocin levels. The data suggest that abrupt decreases in availability of glucose in the central nervous system, as induced experimentally by administration of 2-deoxyglucose or by a rapid fall in peripheral glucose levels, evokes secretion of oxytocin.