Streptozotocin alters pancreatic beta-cell responsiveness to glucose within six hours of injection into rats.

A 24-hour glycaemic profile following streptozotocin (80 mg/kg. i.p.) injection was investigated in fasted rats. The most prominent changes in blood glucose were hyperglycaemia associated with low levels of plasma insulin after two hours followed by hypoglycaemia associated with high levels of plasma insulin after six hours; subsequently hyperglycaemia progressively developed and this was associated with decreasing levels of plasma insulin. Further probing revealed that at two hours after streptozotocin injection, the pancreatic beta-cells could not respond to an oral glucose load while, at six hours after, there was an apparent return of beta-cell responsiveness, but subsequently beta-cell responsiveness was progressively lost and histological examination revealed cellular damage. From these results, it is concluded that within six hours of injection, streptozotocin initiates pancreatic beta-cell damage which leads to the development of diabetes mellitus.