title: Low and high concentrations of gonadotropins differentially regulate hormone production by theca interna and granulosa cells from bovine preovulatory follicles.
abstract: Mammalian preovulatory follicles produce primarily estradiol and androgens before the preovulatory gonadotropin surge. In cattle, the LH/FSH surge triggers a rapid decrease in estradiol and androgen production and a dramatic increase in progesterone and oxytocin biosynthesis. It is unclear how changes in gonadotropin concentrations in vivo regulate this follicular/luteal phase shift in hormone production. To address this question, theca interna and granulosa cells were isolated from preovulatory follicles of Holstein heifers approximately 24 h before the expected time of the LH/FSH surge and cultured in defined medium containing insulin (1 microgram/ml), with varying doses of LH or FSH (0, 1, 2, 4, 8, 16, 32, 64, or 128 ng/ml). Media were collected and replaced every 24 h for 3 days, and assayed for androstenedione and progesterone in theca interna cultures, and for estradiol, progesterone and oxytocin in granulosa cell cultures. After the first day of culture (24-72 h), only very low doses of LH (2 or 4 ng/ml) enhanced (p < 0.05) androstenedione secretion by theca interna cultures above control levels, whereas progesterone secretion was increased by a wide range of LH concentrations (p < 0.05), with maximal progesterone secretion at high doses of LH. Likewise, after the first day of culture (24-72 h), estradiol secretion by granulosa cells was stimulated only by low doses of FSH and was inhibited at higher concentrations relative to control cultures (p < 0.05), whereas the production of oxytocin and progesterone was enhanced maximally by high concentrations of FSH (p < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Department and Section of Physiology, Cornell University, Ithaca, New York 14853, USA.
authors.forename: A K
authors.initials: AK
authors.lastname: Berndtson
authors.forename: S E
authors.initials: SE
authors.lastname: Vincent
authors.forename: J E
authors.initials: JE
authors.lastname: Fortune
mesh_terms: D000735:Androstenedione / Q000096:biosynthesis / Q000378:metabolism; D000818:Animals; D002417:Cattle; D002478:Cells, Cultured; D003470:Culture Media; D004958:Estradiol / Q000096:biosynthesis / Q000378:metabolism; D005260:Female; D005640:Follicle Stimulating Hormone / Q000008:administration & dosage* / Q000494:pharmacology; D006107:Granulosa Cells / Q000187:drug effects / Q000378:metabolism*; D006728:Hormones / Q000096:biosynthesis*; D007700:Kinetics; D007986:Luteinizing Hormone / Q000008:administration & dosage* / Q000494:pharmacology; D006080:Ovarian Follicle / Q000378:metabolism*; D010060:Ovulation; D010121:Oxytocin / Q000096:biosynthesis / Q000378:metabolism; D011374:Progesterone / Q000096:biosynthesis / Q000378:metabolism; D013799:Theca Cells / Q000187:drug effects / Q000378:metabolism*
chemical_list: D003470:Culture Media; D006728:Hormones; D000735:Androstenedione; D011374:Progesterone; D004958:Estradiol; D010121:Oxytocin; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone