EFFECTS OF INTERMITTENT GLUCOSE INFUSIONS IN PREGNANT RATS ON THE FUNCTIONAL DEVELOPMENT OF THE FOETAL PANCREATIC B-CELLS

Abstract

SUMMARY During the last 5 days of gestation, pregnant rats were infused intravenously with a glucose solution daily for 2 h. The total amount of glucose administered per day was 3–4 g/kg body weight. This dose significantly raised the maternal serum glucose levels by 56 ± 17 mg/100 ml on day 17 of gestation and by 39 ± 15 mg/100 ml on day 21. Saline infusions into pregnant rats caused no significant alterations of the blood glucose concentrations. On day 21 of gestation, foetuses were delivered by Caesarean section and the insulin release was determined in vitro by incubating pieces of foetal pancreas first at a low glucose concentration (0·4 mg/ml) for 30 min and then at a high glucose concentration (3·0 mg/ml) for a subsequent 30-min period. It was found that the foetal body weights were significantly lower in the glucose-infused group when compared with the foetal body weights from an untreated control group. The pancreatic insulin content and serum glucose levels of the foetuses when killed did not show any significant difference between the glucose-infused and control groups. In agreement with previous observations a high concentration of glucose failed to affect the insulin secretion in vitro from the pancreases of foetuses of untreated or saline-infused mothers in the control groups. By contrast, in the offspring of glucose-infused mothers, the pancreatic glands responded to the high glucose concentration in vitro with a significantly enhanced rate of insulin release. These findings suggest that the development of the B-cell function before birth may be influenced even by minor, short-term increases in the maternal blood glucose levels. The pregnant rat, intermittently infused with glucose, may serve as a useful model for further studies on the effects of maternal carbohydrate disturbances on B-cell development in the offspring.