Progesterone and estradiol secretion by porcine luteal cells is influenced by individual and combined treatment with prostaglandins E2 and F2a throughout the estrus cycle

The present experiments were conducted to test whether the ratio of PGE(2):PGF(2 alpha) affects steroid secretion by porcine luteal cells. We examined the effect of separate and combined treatment with PGE(2) and PGF(2 alpha) on progesterone and estradiol secretion. Luteal cells were collected at three different stages of the luteal phase (1-3 days after ovulation; 10-12 days after ovulation and 14-16 days after ovulation). PGE, alone in a dose dependent manner increased progesterone production by cells collected from mature corpora lutea. On the other hand, PGF(2 alpha) in a dose dependent manner decreased progesterone secretion by cells of the same origin. Progesterone secretion by cells isolated from mature and regressing corpora lutea and treated with both prostaglandins increased in comparison to PGF(2 alpha)-treated cultures. However, in cells collected from regressing corpora lutea PGE(2) and PGF(2 alpha) in a ratio of 2:1 and 4:1 increased estradiol production when compared to control and both ratios increased estradiol secretion in comparison to PGF(2 alpha)-treated cells. These data 1) confirm the luteotropic effect of PGE(2) and the luteolytic effect of PGF(2 alpha); 2) demonstrate that when the ratio of PGE(2) to PGF(2 alpha) changed from 1:1 to 2:1 or 4:1 cells were protected against the inhibitory effects of PGF(2 alpha), on progesterone secretion by cells collected during the mid- and late luteal phase; and 3) suggest that elevated estradiol production by luteal cells, isolated during late luteal phase, under the influence of increased doses of PGE(2) may serve as an additional source of estradiol to blastocysts, during early pregnancy in the pig. (C) 1999 Elsevier Science Inc. All rights reserved.