Prostaglandins alter the abundance of messenger ribonucleic acid for steroidogenic enzymes in cultured porcine granulosa cells

The effects of prostaglandin F2 alpha (PGF2 alpha) and prostaglandin E2 (PGE2) on the accumulation of progesterone and mRNA for the steroidogenic enzymes 3 beta-hydroxysteroid dehydrogenase (3 beta-HSD) and cytochrome P450 side-chain cleavage (P450(scc)) were determined in luteinized granulosa cells. These cells were aspirated from 3-5-mm follicles of prepubertal pigs and cultured 48 h with 10% serum and then 48 h under serum-free conditions. Cells were then incubated with medium (control), ovine LH (20 ng/ml), (bu)cAMP (0.5 mM) and doses of PGF2 alpha (0.08-2.0 micrograms/ml) or PGE2 (0.1-1.0 micrograms/ml), or combinations of PGF2 alpha (0.1-1.0 micrograms/ml) or PGE2 (0.1-1.0 micrograms/ml) with and without 20 ng/ml LH. Cultures were terminated after 12 h of incubation, and the abundance of mRNA for 3 beta-HSD and P450(scc) was determined by hybridization with specific cDNA probes. Parallel cultures were terminated at 24 h for analysis of progesterone in the medium by RIA. The results demonstrated that LH and (bu)2cAMP elevated progesterone by 3- to 6-fold and the accumulation of mRNA for 3 beta-HSD by 1.5 to 3.5 or 4-fold and for P450(scc) by 2-4-fold. PGF2 alpha reduced the basal level of progesterone accumulation, as well as the steady-state concentrations of mRNA for both 3 beta-HSD and P450(scc). PGF2 alpha interfered with LH and (bu)2cAMP induction of 3 beta-HSD and P450(scc) message, and this interference was dependent on the PGF2 alpha dose employed. PGE2 alone increased the accumulation of progesterone, as well as the message for 3 beta-HSD and P450(scc) PGE2 overcame the abrogation by PGF2 alpha of LH-induced synthesis of progesterone and transcription of 3 beta-HSD and P450(scc). It is concluded that PGF2 alpha regulates ovarian cell function, at least in part, by reducing the transcription of the rate-limiting steroidogenic enzyme P450(scc) and the progesterone synthetic enzyme 3 beta-HSD.