ELEVATING MATERNAL INSULIN-LIKE GROWTH FACTOR-I IN MICE AND RATS ALTERS THE PATTERN OF FETAL GROWTH BY REMOVING MATERNAL CONSTRAINT

Abstract

Fetal growth is normally constrained by maternal factors. This constraint is demonstrated by the usual inverse linear relationship between litter size and mean fetal weight. Cross-breeding experiments between mice of lines selected for high or low plasma insulin-like growth factor (IGF-I) levels suggested that elevations in maternal IGF-I abolish (P When high or low IGF-I line mice embryos were transplanted into a normal line of mice, the expected negative relationship (P Thus both endogenous and exogenous elevations in maternal IGF-I indirectly promote fetal growth either by altering nutrient delivery to the placenta or by affecting placental function.