Responses of pancreatic b cells to alloxan and streptozotocin in the guinea pig

Abstract

Guinea pigs injected with streptozotocin were significantly hyper-glycemic on day 1 after injection but only mildly so on day 14. However, serum insulin levels were significantly depressed on day 14; at this time the animals had lost 25% of their initial body weights and were severely glycosuria. The volume fraction of immunostainable B cells in the pancreas was reduced to one third of control values by day 1 after injection and remained at this level by day 14. Animals that received alloxan were slightly hyperglycemic on day 1 but not on day 14. Both serum insulin and volume fraction of B cells in the pancreas were reduced by 70% on day 1 but had returned to control levels by day 14. Body weights for this group were equivalent to controls at both time points. These data indicate that (1) streptozotocin treatment of guinea pigs causes a diabetes-like condition characterized by insulin deficiency, pancreatic B cell loss, glycosuria, and weight loss, which are not reversed in the first 2 weeks after injection, whereas hyperglycemia is only transitory; (2) alloxan also produces a diabetes-like condition early after injection, but all signs of diabetes disappear within 2 weeks, by which time serum insulin levels and the volume fraction of B cells in the pancreas have returned to normal. The experimental results suggest that regeneration of islet B cells following destruction by alloxan may be the primary cause of the recovery of alloxan-injected guinea pigs from the effects of the drug, whereas the persistence of insulin deficiency is consistent with an absence of islet B cell regeneration in the streptozotocin-treated animals. © 1986 Raven Press, New York.