Effects of Maternal Protein Malnutrition on Fetal Growth, Plasma Insulin-like Growth Factors, Insulin-like Growth Factor Binding Proteins, and Liver Insulin-like Growth Factor Gene Expression in the Rat

摘要

We examined the effects of maternal dietary protein restriction on fetal growth and expression of IGF-I and -II, and IGF-binding proteins (IGFBP). We sought to dissociate the respective effects of maternal protein versus calorie restriction on growth indices and IGF synthesis by the neonates of protein-restricted dams. Pregnant Wistar rats (six to eight per group) fed a low (5%) protein diet throughout gestation had impaired body weight gain compared with controls fed a normal (20%) protein diet (by 45%, p p versus controls), although IGFBP-1, -2, and -4 were not significantly affected by the dietary protein intake. In pups of protein-restricted dams, the mean body and liver weight at birth was 15–20% less than that observed in the progeny from normal protein-fed dams (p p < 0.01). In contrast, neonatal plasma IGF-II and liver IGF-II mRNA concentrations were not significantly affected by the maternal protein malnutrition. Also, the plasma levels of IGFBP were not altered in the growth-retarded pups. Maternal protein restriction did not affect fetal and placental growth, plasma and liver IGF-I levels, and liver IGF-I mRNA abundance in 20-d-old fetuses. We conclude that intrauterine growth retardation caused by maternal protein malnutrition is associated with reduced neonatal expression of the IGF-I gene without obvious changes in IGF-II gene expression and plasma IGFBP concentrations. These results support the emerging evidence that IGF-I may play a role in the regulation of fetal growth and development.