Glucose Metabolism in Brains of Diabetic Rats

Metabolism of glucose-U-14C was studied in brains of rats 1) 2 days after alloxan treatment,2) 2 hr after D-mannoheptulose injection, or 3) 21/2 hr after evisceration (including pancreatectomy) followed by infusion with glucose (50 mg/100 g/hr). Glucose concentrations were 3 times normal in blood and 6 times normal in brains in these rats. Uptake of radioactive glucose in brain during the first 15 min after its injection was greater in 1) and 2) than in normal rats (blood glucose equivalent in brain was 11.9 and 9.9 μmoles/g in 1) and 2) compared to 6.52 in normal rats). The percentages of brain 14C found in glucose were greatly increased in 1) and 2) but the amount of glucose which was converted to glutamate, other amino acids and lactate was similar to that in normal rats. In 3), glucose concentrations were high in blood and brain but brainuptake of glucose was no greater than in normal rats. The percentage of brain 14C in glucose was high in 3) but the conversion of glucose to its metabolites in brain was greatly reduced. Thus, the liver, noted for gluconeogenesis in diabetic animals, also appears to stimulate glucose uptake and metabolism in brain. (Endocrinology85: 428,1969)