Effect of maternal food restriction on circulating insulin and glucagon levels and on liver insulin and glucagon binding sites of fetal and suckling rats

Abstract

Food was restricted in pregnant and nursing rats in order to evaluate the effect of malnutrition on insulin and glucagon metabolism in fetal and suckling rats. Food restriction of the mothers induced a loss of body and liver weights in their offspring, which was more pronounced in suckling than in fetal rats. A significant decrease of circulating insulin and glucagon levels in fetal and suckling rats from food restricted mothers (FRM) was also observed. In liver membranes insulin binding was higher in control, fetal and suckling rats than in adult animals, but maternal food restriction decreased insulin binding to liver membranes of suckling rats, and no changes between control and fetuses from FRM were observed. By contrast, glucagon binding was higher in adult than in younger control animals; however maternal food restriction had no effect on glucagon binding to liver membranes of fetal rats, although they produced an increase in 10 day-old suckling rats. The modifications in insulin and glucagon binding reflect changes in the number of receptors, but not in the affinity constants. The time courses of insulin and glucagon association to liver membranes were unaffected by the development or by the nutritional status of the animals. Degradation of insulin and glucagon by liver membranes was significantly lower in young rats and in rats from FRM, but this does not seem to be responsible for the differences observed in binding. No significant differences in the degradation of insulin and glucagon receptors between different groups of liver membranes were found.(ABSTRACT TRUNCATED AT 250 WORDS)