Effects of Insulin on Local Cerebral Glucose Utilization in the Rat

The effects of hyperinsulinemia on local cerebral glucose utilization were studied by the quantitative autoradiographic 2-[14C]deoxyglucose method in normal conscious rats under steady-state normoglycemic conditions. Hyperinsulinemia and a steady state of normoglycemia were achieved and maintained during the experimental period by a continuous intravenous (i.v.) infusion of insulin given simultaneously with a programmed i.v. infusion of D-glucose. Hyperinsulinemia under normoglycemic conditions did not change the average rate of glucose utilization in the brain as a whole, but significant increases in local glucose utilization were found selectively in the ventromedial, dorsomedial, and anterior hypothalamic nuclei. The results suggest that a known anatomical pathway linking the dorsomedial and anterior nuclei with the ventromedial nucleus of the hypothalamus may be physiologically activated in response to hyperinsulinemia.