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 (original) (raw)

We examined the effects of maternal dietary protein restriction on fetal growth and expression of IGF-I and-11, 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 proteinrestricted 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 < 0.001). Their serum and liver IGF-I concentrations and liver IGF-I mRNA concentrations were also reduced by 60, 80, and 50%, respectively. Serum IGFBP-3 was reduced by 60% in protein-restricted dams within 1 to 2 h after delivery (p < 0.001 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 < 0.01). Their plasma and liver IGF-I concentrations were 30 and 60% lower, respectively, whereas , liver IGF-I mRNA abundance was reduced by 50% (p < 0.01). In contrast, neonatal plasma IGF-I1 and liver IGF-I1 mRNA concentrations wen: not significantly affected by the maternal protein malnutrition. Also, the plasma levels of IGFBP were not altered in the growlh-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 malnutritior~ is associated with reduced neonatal expression of the IGF-I gene without obvious changes in IGF-I1 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. (Pediutr Res 37: 3 3 4 4 2 , 1 9 9 5) Abbreviations IGFBP, IGF binding protein GH, growth hormone ANOVA, analysis of variance IUGR, intrauterine growth retardation BW, body weight