Gonadotropic regulation of prostaglandin production by ovarian follicular cells of the pig

Prepubertal gilts were treated with 750 IU pregnant mare's serum gonadotropin (PMSG) and 72 h later with 500 IU human chorionic gonadotropin (hCG) to induce follicular growth and ovulation. Dispersed granulosa cells (GC) and theca interna cells (TC) from follicles of gilts 72 h (GC-72 and TC-72, respectively) and 108 h (GC-108 and TC-108 h, respectively) after PMSG treatment were cultured for 0, 12, 24, and 36 h in medium with or without luteinizing hormone (LH), dibutyryl cyclic adenosine 3',5'-monophosphate Bu)2cAMP), calcium ionophore (A23187), and/or arachidonic acid (AA), and the production of prostaglandin E2 (PGE) and prostaglandin F2 alpha (PGF) was measured by radioimmunoassay. TC-72 was the principal source of PGs 72 h after PMSG. At 108 h, the production of PGE and PGF by GC was increased 10- and 30-fold, respectively, whereas corresponding increases by TC were 2-fold. LH and A23187 significantly stimulated PGE and PGF production by both GC-72 and TC-72, but only thecal PG production was stimulated by (Bu)2cAMP. LH had minimal or no effect on PG production by GC-108 and TC-108, but A23187 (GC-108, TC-108) and (Bu)2cAMP (TC-108) were stimulatory. Basal PG production by GC-72, GC-108, and TC-108 was stimulated by AA. However, production by GC and TC cultured in medium containing AA and LH, A23187, or (Bu)2cAMP was not different from that produced by AA alone. These findings suggested that GC and TC can synthesize PGs in vitro, but AA availability is rate-limiting in GC. After exposure to hCG in vivo, the capacity of both cell types to produce PGs is increased but is limited by AA availability.(ABSTRACT TRUNCATED AT 250 WORDS)