Effects of prostaglandin F₂α on agonist-induced progesterone production in cultured bovine luteal cells

The present study examines the effects of prostaglandin F(2α) (PGF(2α)) on basal and agonist-stimulated progesterone (P₄) production utilizing long-term, serum-free cultures of bovine luteal cells. During the first 24 h of culture, PGF(2α) had no significant effect on P₄ production, and was unable to inhibit either luteinizing hormone (LH)- or dibutyryl cAMP (dbcAMP)-stimulated increases in P₄. Treatment with PGF(2α) on Day 1 produced a moderate, nonsignificant (P>0.05) inhibition of cholera toxin (CT)- and forskolin (FKN)-stimulated P₄ synthesis. Beyond Day 1 of culture (Days 3-11), PGF(2α) continued to have no significant effect on basal P₄ production, but suppressed all stimulatory effects of LH, dbcAMP, CT and FKN. Treatment with indomethacin inhibited prostaglandin synthesis by the cultured cells and also elevated levels of P₄ from Days 3 to 11 of culture. Concurrent treatment with PGF(2α) suppressed the steroidogenic effect of indomethacin. From these studies it was concluded that in cultured bovine luteal cells, PGF(2α) does not affect basal P₄ production, but is able to inhibit agonist-stimulated P₄ production at a site beyond the accumulation of cAMP. This inhibitory effect is not apparent during the first 24 h of culture, but appears after Day 1 and persists throughout the remaining 10 days of the culture period.