Increased binding of epidermal growth factor to placental membranes of intrauterine growth restricted fetal rats

Abstract

To examine the relationship between nutrient supply and fetal and placental growth, we examined epidermal growth factor (EGF) binding to membranes prepared from placentas of growth-restricted fetal rats. Intrauterine growth retardation was accomplished by unilateral ligation of the uterine artery; fetal rats on the contralateral uterine horn served as controls. Fetal growth restriction was accompanied by decreased placental wt at 19 and 20 day's gestation and significantly decreased placental glycogen content at 20 and 21 days, 30% and 15%, respectively. Placental DNA content and protein/DNA ratios were similar in the growth-restricted and control groups. Specific binding of 125I-EGF was increased in growth-restricted placentas at 19 and 20 days' gestation by 32% and 16%, respectively. 125I-EGF binding at 20-21 days increased linearly with the extent of placental growth restriction. Competitive binding experiments yielded linear Scatchard plots with an increased receptor density in growth-restricted placenta at 19 and 20 days' gestation, 74% and 60%, respectively. Binding affinities for the EGF receptor were similar in the two groups. The increased binding of EGF to membranes prepared from growth-restricted fetal rats may serve to enhance nutrient uptake under conditions of decreased uterine blood flow.