Regulation of steroid synthesis and metabolism in isolated binucleate cells of the placenta in sheep and goats.

Binucleate cells of sheep and goat fetal placentae comprise about one-fifth of the trophectodermal layer at the feto-maternal interface. When isolated and incubated in vitro they produce the steroids that are synthesized by the placenta in vivo (progesterone in sheep, 5 beta-pregnane-3 alpha,20 alpha diol in goats). This study demonstrates that progesterone synthesis in binucleate cell preparations in sheep was increased by prostaglandin (PG) E-2, nordihydroguaiaracetic acid (NDGA) and methylisobutylxanthine, but reduced by indomethacin, whereas in goats only NDGA produced any effect (an increase). None of the other compounds tested (luteinizing hormone, follicle stimulating hormone, prolactin, dibutyryl cAMP, A23187 or phorbolmyristic acetate) had any effect. Sheep binucleate cells also produced PGE-2 from arachidonic acid. These results suggest that, in sheep, products of both the cyclooxygenase (producing PGE-2) and lipoxygenase (inhibited by NDGA) pathways of arachidonic acid metabolism have regulatory roles in placental steroid synthesis, but only the lipoxygenase pathway is relevant in goats.