ESTROGEN PRODUCTION BY BOVINE BINUCLEATE AND MONONUCLEATE TROPHOBLASTIC CELLS IN-VITRO

The bovine placenta has long been known as a source of steroid hormone s. We performed three experiments to compare production of estrogens b y bovine mononucleate and binucleate trophoblastic cells and examined effects of cortisol, progesterone, pregnenolone, testosterone, and and rostenedione. In the first experiment, binucleate trophoblastic cells were purified by unit gravity sedimentation from six enzymatically dis persed placentas between 150 and 180 days of gestation. Cells (8 x 10( 5)/ml) were incubated first at 37 degrees C for 6 h with Medium 199 al one (M199/6h) or with 10(-7) M cortisol (cortisol/6h). Medium then was replaced with 10(-7) M progesterone, 10(-7) M pregnenolone, 10(-7) M testosterone, or M199, and a second incubation was conducted for 4 h. Estradiol production did not differ between cells incubated for the fi rst 6 h in M199 vs. cortisol and was not affected by progesterone or p regnenolone. Testosterone increased (p < 0.05) estradiol production. E strone production did not differ between cells incubated for the first 6 h in M199 vs. cortisol; estrone production was not affected by eith er progesterone, pregnenolone, or testosterone. Mononucleate as well a s binucleate cells were purified from placentas between 165 and 180 da ys of gestation and used in two other experiments. In the first of the se, enriched populations of binucleate and mononucleate cells were inc ubated first for 6 h with Medium 199 (M199) or 10(-7) M cortisol. Medi um then was replaced with 10(-7) M testosterone, 10(-7) M androstenedi one, or M199 and incubation continued for 4 h. Mononucleate cells prod uced more estrone than did binucleate cells during the first G-h incub ation (p < 0.05); cortisol did not affect this production. Estrone pro duction by mononucleate cells was not affected by testosterone or andr ostenedione. Estradiol production by cells incubated for the first 6 h was not different between treatments or cell types. Testosterone incr eased estradiol production by binucleate cells (P < 0.05), but not mon onucleate cells. In the third in this series of experiments, binucleat e and mononucleate cells were incubated for 10 continuous hours with M 199, progesterone, or pregnenolone. Estrone production by mononucleate cells was not affected by progesterone or pregnenolone. However, estr one production was greater by mononucleate than by binucleate cells (p < 0.05). Estradiol production was not different among treatments or c ell types. These data show that bovine mononucleate and binucleate tro phoblastic cells produced estradiol and estrone in vitro. Cortisol, pr ogesterone, and pregnenolone (10(-7) M) did not affect estradiol or es trone production; and exogenous testosterone (10(-7) M) facilitated es tradiol production by binucleate, but not mononucleate, cells. Our res ults suggest that the aromatase, but not the 17 alpha-hydroxylase, ste roidogenic pathway is functional in trophoblastic cells isolated from second trimester bovine placentas.