Metabolic alterations in normal and streptozotocin-diabetic rats in vivo: influence of prolonged starvation.

We studied the influence of prolonged starvation on carbohydrate metabolism in streptozotocin-diabetic rats compared with normal rats. In streptozotocin (STZ)-diabetic rats, the plasma glucose concentration decreased gradually during prolonged starvation, while it did not change in normal rats. In normal rats, glycogen depletion in the liver occurred within 24 hr of starvation, while in STZ-diabetic rats, glycogen content did not change even after 72 hr of starvation. Impaired glucose tolerance and glycogen deposition in response to oral administration of glucose were observed in STZ-diabetic rats compared with normal animals. STZ-diabetic animals generally had lower glycogen synthase and phosphorylase activities compared with normal rats during starvation. In normal animals, there is a significant correlation between the plasma concentration of free fatty acids and 3-hydroxybutyrate. On the basis of these findings, metabolic alterations in chemically-induced diabetic animals were discussed.