Effect of diabetes, insulin, starvation, and refeeding on the level of rat hepatic fructose 2,6-bisphosphate.

The influence of alloxan diabetes and starvation for 72 h on the level of rat hepatic fructose 2,6-biphosphate was investigated. Both diabetes and starvation decreased the level to 10% of the value found in livers of normal, fed rats (10 nmol/g liver). The activity of the enzyme responsible for the synthesis of fructose 2,6-bisphosphate, 6-phosphofructo 2-kinase, was also decreased in livers of diabetic rats. Insulin administration for 24 h to diabetic rats restored the level of fructose 2,6-bisphosphate to normal. Refeeding a high carbohydrate diet for 24 h to starved rats resulted in fructose, 2,6-biphosphate levels that were 2.5-fold higher than that in livers of fed rats. The level of fructose 2,6-bisphosphate in diabetes and starvation, and after refeeding correlates as well with the rate of glycolysis and gluconeogenesis in these states and thereby provides further support for its role in regulating hepatic carbohydrate metabolism.