INHIBIN PRODUCTION BY MACAQUE GRANULOSA-CELLS FROM PREVULATORY AND PERIOVULATORY FOLLICLES - REGULATION BY GONADOTROPINS AND PROSTAGLANDIN-E2

Although inhibin (IN) is secreted by granulosa cells (GC) of preovulatory follicles, the major source of immunoreactive IN circulating during the primate ovarian cycle is the corpus luteum. The aims of this study were (1) to investigate culture conditions for optimal IN production by luteinized GC (LGC) from rhesus monkeys and (2) to compare IN and progesterone (P) production by nonluteinized GC (NGC) and LGC in response to putative agonists. Animals were treated for up to 9 days with human menopausal gonadotropins to promote the development of multiple preovulatory follicles. GC were obtained from large follicles before (NGC) or 27 h after (LGC) an ovulatory injection of hCG. For Aim 1, cells were cultured in Hams F- 10 medium +/- hCG (100 ng/ml) with or without the addition of insulin/transferrin/selenium, 10% fetal bovine serum, or 10% Serum-Plus (JRH Biosciences, Lenexa, KS). Medium was changed on Days 1, 2, 4, 6, and 8; and IN and P concentrations were determined by RIA. Basal (unstimulated) IN production by LGC was enhanced and maintained for 6-8 days in the presence of serum, but rapidly declined in the absence of serum. In contrast, basal P secretion declined regardless of exposure to serum. Human GC consistently increased (p < 0.05) IN production only in the presence of serum but stimulated (p < 0.05) P production under all conditions. For Aim 2, cells were cultured for 4 days in Ham's F- 10 medium + 10% macaque serum +/- hCG (100 ng/ml), hFSH (100 ng/ml), prostaglandin E2(PGE2; 14-mu-m), or dibutyryl(db)-cAMP (5 mM). On Day 1, IN secretion by NGC and LGC was similar, but IN production, particularly by NGC, declined during the culture period. PGE2 and db-cAMP increased (p < 0.05) IN production by both NGC and LGC more than 3-fold. FSH was a less potent (< 2-fold) stimulator (p < 0.05) of IN secretion by both NGC and LGC. Human CG had no effect on NGC, but increased (p < 0.05) IN production by LGC similarly to FSH. However, hCG increased (p < 0.05) P production by both NGC and LGC. Thus, in vitro IN production by macaque GC is dependent upon culture conditions and is stimulated by various cAMP-dependent agonists. Whereas IN production by NGC from preovulatory follicles is regulated by FSH, secretion by LGC of the developing corpus luteum is also under LH control. In addition, locally produced prostaglandins may be potent stimulators of IN secretion by granulosa/luteal cells in the primate ovary. Finally, the ability of cAMP-dependent agonists to stimulate P secretion did not necessarily correlate with enhanced IN production by macque GC.