title: Porcine follicular fluid protein(s) inhibit rat ovary granulosa cell steroidogenesis.
abstract: We examined the effect of an isolated fraction of follicular fluid, termed follicle regulatory protein, on the production of estrogen, progesterone, and 20 alpha-dihydroprogesterone by cultured rat ovarian granulosa cells. We found a stepwise decrease in estrogen production with an increasing concentration of follicle regulatory protein (9 to 300 micrograms/ml) when the cells were stimulated by 6.25 ng/ml of ovine follicle-stimulating hormone, but the addition of a saturating dose of ovine follicle-stimulating hormone (50 ng/ml) prevented the inhibitory effect of follicle regulatory protein on estrogen production. Follicle regulatory protein inhibited progesterone production at both low and saturating levels of ovine follicle-stimulating hormone. We examined whether cholesterol substrate in the form of high-density lipoprotein or low-density lipoprotein could overcome the follicle regulatory protein inhibition of progesterone and 20 alpha-dihydroprogesterone production stimulated by follicle-stimulating hormone. At all concentrations of high-density and low-density lipoprotein, 75 micrograms/ml of follicle regulatory protein inhibited progesterone production by 80% to 90%. In the case of 20 alpha-dihydroprogesterone, the presence of high-density and low-density lipoprotein accentuated the inhibitory effect of follicle regulatory protein. These results demonstrate that the effects of follicle regulatory protein on ovarian steroidogenesis depend on: the concentration of gonadotropin, the concentration of follicle regulatory protein, and the availability of cholesterol substrate.
mesh_terms: D004092:20-alpha-Dihydroprogesterone / Q000096:biosynthesis; D000818:Animals; D004965:Estrogen Antagonists / Q000494:pharmacology*; D004967:Estrogens / Q000096:biosynthesis; D005260:Female; D005640:Follicle Stimulating Hormone / Q000494:pharmacology; D006107:Granulosa Cells / Q000187:drug effects / Q000378:metabolism*; D036341:Intercellular Signaling Peptides and Proteins; D008075:Lipoproteins, HDL / Q000494:pharmacology; D008077:Lipoproteins, LDL / Q000494:pharmacology; D010455:Peptides / Q000494:pharmacology*; D011374:Progesterone / Q000037:antagonists & inhibitors / Q000096:biosynthesis; D051381:Rats; D012756:Sheep; D013552:Swine
chemical_list: D004965:Estrogen Antagonists; D004967:Estrogens; D036341:Intercellular Signaling Peptides and Proteins; D008075:Lipoproteins, HDL; D008077:Lipoproteins, LDL; D010455:Peptides; C018355:intraovarian peptides; D004092:20-alpha-Dihydroprogesterone; D011374:Progesterone; D005640:Follicle Stimulating Hormone