Glucagon and fetal growth in the rat

Abstract

Increased size is characteristic of the offspring of diabetic mothers and there is evidence that hyperglycemia itself may have a similar effect in the rat. Glucagon, the second known pancreatic hormone, causes a hyperglycemia through its enhancement of hepatic glycogenolysis. The effect of the regular administration of glucagon to the mother during the last part of pregnancy in the rat has, therefore, been investigated with 300 μg of crystalline glucagon injected subcutaneously at 9:00 a.m. and 3:00 p.m. from day 17 to day 21 of pregnancy. Maternal weight gain was decreased, along with daily food intake, when compared to saline-injected pregnant rats. The glucagon failed to produce a persistent hyperglycemia. A significant decrease in mean weight of the pups in the glucagon-treated group could not be attributed to the reduction of maternal food intake alone, for these pups were also significantly lighter than those from rats pair-fed with the glucagon-treated animals. This failure of weight gain may have been due to an increase in metabolic rate and caloric demand that glucagon can produce. Glucagon had only a temporary effect on blood glucose; it acutely reduced the maternal liver glycogen but had little effect on placental glycogen.