Effect of IGF-1 on placental prostanoid production

Prostanoids play an important role throughout all of pregnancy and during the initiation and progress of labor. The human placenta, at term, produces large quantities of prostanoids, yet little is known of the steps regulating their biosynthesis. In these studies, the effect of IGF-I on the release of placental prostanoids was investigated. The basal release of prostaglandin E (PGE), prostaglandin F (PGF), thromboxane (TxB2) and 6-keto-prostaglandin F1 alpha (6-keto-PGF1 alpha) increased from the fifth hour in culture, while the release of 13, 14-dihydro-15-keto-PGF2 alpha (PGFM) remained constant and hCG release decreased. The addition of IGF-I (10(-8) M) to the perfusing medium effected an inhibition of TxB2 and PGF within two and one-half hours of exposure. However, the release of PGE, PGFM, 6-keto-PGF1 alpha or hCG was not altered by IGF-I. Because both TxB2 and PGF are vaso-constrictors, we have proposed that IGF-I may enhance vasodilation in the placenta. Therefore, IGF-I may allow increased blood flow, thus affecting the maintenance of pregnancy and supply of nutrients for the growth of the fetus.