Maternal diabetes induces upregulation of hepatic insulin-like growth factor binding protein-1 MRNA expression, growth retardation and developmental delay at the same stage of rat fetal development.

Since maternal diabetes is associated with fetal growth abnormalities in humans and rats, effects of maternal diabetes on fetal expression of genes regulating growth are of interest. Increased expression of Insulin-Like Growth Factor Binding Protein-I (IGFBP-1) is associated with several examples of growth retardation and is upregulated in response to diabetes. As we have shown previously, IGFBP-1 expression is upregulated in gestational day (GD) 14 rat fetuses in response to maternal diabetes. Here we analyze the effect of streptozotocin-induced maternal diabetes on IGFBP-1 mRNA expression during GD12-16 of rat fetal development, using in situ hybridization. IGFBP-1 mRNA was more abundant in GD12-14 fetal livers from diabetic dams than in livers of age-matched controls. This upregulation is not due to the approximately 1-day fetal developmental delay associated with maternal diabetes, as there is no gross difference in the level of IGFBP-1 mRNA in GD13 vs GD12 or GD14 vs GD13 control fetal livers. At GD15-16, however, we detected little difference in IGFBP-1 expression between experimental and control fetuses. This transient period of maternal diabetes-stimulated IGFBP-1 mRNA expression (GD12-14) is coincident with the sensitive period for maternal diabetes-induced defects in fetal growth and development, suggesting that IGFBP-1 is involved in the regulation of fetal growth and development in response to the maternal condition.