Relationships between medial hypothalamic alpha 2-receptor binding, norepinephrine, and circulating glucose.

These experiments examine the dependence of medial hypothalamic alpha 2-receptor binding on the availability of circulating glucose. Food deprivation and tolbutamide-induced hypoglycemia both diminished alpha 2-binding. These binding results were highly correlated with serum glucose levels. Prevention of tolbutamide hypoglycemia by concomitant injections of dextrose blocked the effects on alpha 2-binding. Injection of norepinephrine into the medial hypothalamic sites that normally elicit feeding behavior elevated serum glucose. These results suggest a homeostasis for control of glucose in a hypothalamic feeding system.