Effects of fetal hypoinsulinemia on fetal hepatic insulin binding in the rat

Abstract

Fetal hepatic insulin binding was studied in term fetal rats born to control mothers, mothers fasted for 48 h and mothers made hyperinsulinemic by the chronic, exogenous administration of insulin for 5 days prior to term. Maternal hyperinsulinemia was associated with fetal hypoglycemia and an approx. 70% reduction in fetal plasma insulin. Fetuses from these mothers exhibited an increase in hepatic insulin binding as indicated by a significant change in Scatchard analyses. No significant effect on fetal hepatic insulin binding by Scatchard analysis was seen with maternal fasting, despite a modest decrease in fetal plasma insulin. However, analysis of all animals showed that high-affinity fetal hepatic insulin binding and specific 125I-insulin binding were inversely correlated with fetal plasma insulin concentration. These results indicate that fetal rat liver, similar to adult rat liver, responds to a decrease in circulating insulin to below normal concentrations with an increase in insulin receptor binding.