Growth factors and steroidogenesis in the bovine placenta

The control of placental hormone biosynthesis is critical during gestation, since their coordinated action is essential for the normal progress of pregnancy. Hormonal synthesis regulation in placenta is still not elucidated and differs from that observed in other steroidogenic tissues since specific tropic hormones have not yet been identified. Cellular localization of growth factors in the placenta, including VEGF, EGVEGF and bFGF, points that these factors have additional roles in the organ besides their well known modulation on cell proliferation and angiogenesis. In vitro experiments bring new evidence that growth factors play regulatory roles modulating processes related to steroid hormone secretion in the placenta. Importance of local estrogen function has been highlighted and a key enzyme for its synthesis is aromatase cytochrome P450. The objective of this review was to describe some aspects of placental steroidogenesis, mainly focusing on aromatase cytochrome P450 steroidogenic enzyme expression and growth factors as others potential modulators of hormonal synthesis in the organ.