Expression of basic fibroblast growth factor, endothelial mitogenic activity, and angiotensin II type-1 receptors in the ovine placenta during the third trimester of pregnancy

To evaluate expression of basic fibroblast growth factor (FGF), endothelial mitogenic activity, and angiotensin II type-1 receptors (AT1r), as well as the role of angiotensin II (ANG II) in regulating basic FGF production/secretion, placentae were obtained from ewes on Days 110, 120, 130, and 142 of pregnancy and were separated into fetal cotyledonary (GOT) and intercotyledonary (ICOT), as well as maternal caruncular (CAR) and intercaruncular (ICAR) components. Using immunohistochemistry, basic FGF and AT1r were found for the most part to be colocalized in all placental components, primarily in epithelium, stroma, endothelium, and vascular smooth muscle. Changes in basic FGF levels in placental explant-conditioned media were observed in fetal, but not maternal, components. In GOT, basic FGF levels increased 2.4-fold (r(2) = 0.48, p < 0.04) from Day 110 to 130 and then declined at term. In ICOT, basic FGF levels increased 6.4-fold (r(2) = 0.33, p < 0.05) from Day 110 to 142. The rank order of averaged basic FGF levels was COT > CAR > ICOT = ICAR (p < 0.05). Endothelial mitogenic activity of conditioned media was observed in COT from Day 130 pregnant ewes (232.5 +/- 38.7% of control; p < 0.05) but not in other components, and it was neutralized by a basic FGF antibody. ANC II did not alter basic FGF levels in any placental component. Thus, throughout the third trimester, 1) basic FGF and AT1r are present in placentae, 2) both basic FGF levels and endothelial mitogenic activity in COT increase, 3) basic FGF levels are associated with endothelial mitogenic activity of COT, and 4) ANC II has no effect on production/secretion of basic FGF by the placenta.