IGF-IR Signal Transduction Protein Content and Its Activation by IGF-I in Human Placentas: Relationship with Gestational Age and Birth Weight

mol/L for 15, 30, and 60 minutes.The IGF-IR content was higher in T-SGA compared to T-AGA placentas, and the IRS-1 content was higher in PT-placentas compared with their respective T-placentas. The effect of IGF-I on the phosphorylated forms of IGF-IR was increased in T-SGA (150%) and PT-SGA (300%) compared with their respective AGA placentas. In addition, AKT serine phosphorylation was higher in PT-SGA compared to PT-AGA and T-SGA placentas (90% and 390% respectively).The higher protein content and response to IGF-I of IGF-IR, IRS-1, and AKT observed in SGA placentas may represent a compensatory mechanism in response to fetal growth restriction