Local Cerebral Glucose Utilization is Increased in Acutely Adrenalectomized Rats

The quantitative autoradiographic deoxyglucose method was used to study the effects of acute adrenalectomy on local cerebral glucose utilization in conscious albino rats. Five hours following removal of the adrenal glands, glucose utilization was increased (4-55%) throughout the brain, particularly in the locus ceruleus, hypothalamic paraventricular nucleus, hippocampus, median eminence and anterior lobe of the pituitary gland. These structures are involved in the regulation of corticotropin-releasing factor, vasopressin, and adrenocorticotropic hormone. Treatment with dexamethasone (0.25 mg/kg i.m.) substantially reduced or prevented the stimulatory effects of adrenalectomy on cerebral glucose metabolism. These results demonstrate: (1) the existence of a negative feedback loop between the brain and adrenal glands in which corticosteroids exert an inhibitory action on glucose utilization of brain regions participating in adrenotropic regulation, and (2) a general inhibitory action of glucocorticoids on cerebral metabolism.