Pregnancy-associated changes in the endocrine pancreas of normoglycaemic streptozotocin-treated Wistar rats

The effect of pregnancy on pancreatic insulin content and relative B-cell volume has been studied in normoglycaemic Wistar rats treated with streptozotocin 14 days before mating. A single intravenous injection of streptozotocin (30 mg/kg body weight) caused a significant reduction of pancreatic insulin content and B-cell volume. The islet insulin content was 60% of control values. However, pregnancy-associated adaptation was preserved in these streptozotocin-treated animals. Plasma insulin levels, pancreatic insulin and B-cell volume were significantly enhanced compared with non-pregnant rats investigated on the same date. The incorporation of [3H]-thymidine into islets from pregnant rats (day 10.5) was higher than that in islets isolated from non-pregnant animals. After delivery insulin content and B-cell volume returned to pre-pregnant values. Also during a longer period after streptozotocin treatment (156 days), no measurable enhancement of B-cell volume and pancreatic insulin content was observed indicating the unresponsiveness of residual B cells to compensate spontaneously for the loss despite persisting normoglycaemia.