Progesterone and estradiol secretion by porcine luteal cells is influenced by individual and combined treatment with prostaglandins E 2 and F 2a throughout the estrus cycle

Abstract

The present experiments were conducted to test whether the ratio of PGE 2:PGF 2α affects steroid secretion by porcine luteal cells. We examined the effect of separate and combined treatment with PGE 2 and PGF 2α 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 2 alone in a dose dependent manner increased progesterone production by cells collected from mature corpora lutea. On the other hand, PGF 2α 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 2α-treated cultures. However, in cells collected from regressing corpora lutea PGE 2 and PGF 2α 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 2α-treated cells. These data 1) confirm the luteotropic effect of PGE 2 and the luteolytic effect of PGF 2α; 2) demonstrate that when the ratio of PGE 2 to PGF 2α changed from 1:1 to 2:1 or 4:1 cells were protected against the inhibitory effects of PGF 2α 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.