CONICET | Buscador de Institutos y Recursos Humanos

The insulin like growth factor II (IGF II) has well known mitogenic effects. Knock out fetuses from IGF II are lighter, while fetuses overexpressing IGF II are heavier than their controls. Maternal to fetal transport across the placenta provides glucose, lipids and other supplies. Many placental enzymes, transporters and specific channels modulate fetal acquisition of nutrients. The lipolytic enzymes lipoprotein lipase (LPL) and endothelium lipase (EL) are relevant regulators of lipid transfer through the placenta. Objectives: To study the effect of fetal IGF II administration on fetal growth and placental lipases expression. Methods: Female rats were submitted to a surgical procedure on days 19, 20 and 21 of pregnancy, and their fetuses injected with vehicle or IGF II (2 and 0.02 ng per fetus per day). Fetuses were obtained at term through cesarean section. Placentas, fetuses and fetal organs were weighed and placental expression of LPL and EL was measured by RT-PCR. Results: IGF II administration induced an increase on fetal weight (p<0.05) by 10% compared to controls. IGF II also induced weight increase in many fetal organs as liver (p<0.05), kidneys (p<0.05), pancreas (p<0.01), intestine (p<0.01) and stomach (p<0.0005) but did not affect the weight of lungs and heart. Placental weight was unchanged. Placental expression of EL (p<0.01) was upregulated by 147% and that of LPL was unchanged. Conclusion: IGF II promotes the growth of several but not all fetal organs. This increase may be the result of specific mitogenic effects. The IGF-II effect on EL is novel in general and may result in an increased maternal to fetal lipid transfer to sustain augmented fetal growth under conditions of elevated fetal IGF-II levels