Effect of alloxan and insulin on carbohydrate metabolism in rat brain.

8 and 24 hours after alloxan administration, diabetic rat brain shows decreased glycogen content, significantly increased FDP, triose phosphates, pyruvate and lactate levels, a large rise in glucose and a 27% activation of anaerobic lactate production from glycogen. 48 hours after alloxan administration there is a recovery of glycogen and a fall in lactate levels. ATP and AMP levels are unchanged 8 and 24 hours after alloxan administration but the former is increased and the latter decreased 48 hours posttreatment. Insulin given to rats 8 hours after alloxan treatment reverses glycogen, FDP, triose phosphates, pyruvate and lactate levels seen in the diabetic rat brain. In addition the increament in glucose is reduced by half and the rate of anaerobic lactate formation from glycogen is restored to control values. G-6-P levels, unaffected by alloxan or insulin alone, are significantly lowered in animals which received insulin after alloxan. Phosphorylase, HK, PFK, ALD, GAPDH, PK, LDH and Glycogen synthetase activities are not modified in rat brain by administration of alloxan or insulin or both.