Effects of insulin, insulin-like growth factor I, and gonadotropins on bovine granulosa cell proliferation, progesterone production, estradiol production, and(or) insulin-like growth factor I production in vitro.
The objectives of the present studies were to determine the effect of insulin, insulin-like growth factor I (IGF-I), testosterone, and FSH on proliferation, progesterone production, and(or) estradiol production of bovine granulosa cells. In addition, existence of IGF-I mRNA in granulosa cells and in vitro IGF-I production by granulosa cells were assessed. Cells from small (1 to 5 mm) and large (> or = 8 mm) follicles were collected from cattle and cultured for either 3 or 4 d. When cells from small follicles were cultured, insulin (.1 to 10 micrograms/mL) and IGF-I (100 to 400 ng/mL) increased (P < .05) cell numbers compared with controls. Insulin alone or IGF-I alone increased (P < .05) progesterone production per cell by severalfold on d 4. In cells from both sizes of follicles, insulin (1 microgram/mL), in the presence of FSH, increased estradiol production per cell. In contrast, IGF-I (100 ng/mL) inhibited estradiol production by cells from small follicles and stimulated estradiol production by cells from large follicles. Insulin-like growth factor II (100 ng/mL) and insulin at higher doses (> or = 5 micrograms/mL) had no effect on estradiol production by cells from small and large follicles. Granulosa cells contained four IGF-I mRNA transcripts and produced IGF-I in vitro. These results support the hypothesis that insulin and IGF-I may have direct local effects on bovine ovarian function, and that these effects are influenced by dose and size of follicle.
Department of Animal Science, Oklahoma State University, Stillwater 74078.
L J
LJ
Spicer
E
E
Alpizar
S E
SE
Echternkamp
D000818:Animals; D002417:Cattle / Q000502:physiology*; D002452:Cell Count / Q000662:veterinary; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D004958:Estradiol / Q000096:biosynthesis; D005260:Female; D005640:Follicle Stimulating Hormone / Q000494:pharmacology; D006107:Granulosa Cells / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D007328:Insulin / Q000494:pharmacology*; D007334:Insulin-Like Growth Factor I / Q000096:biosynthesis / Q000235:genetics / Q000494:pharmacology*; D011374:Progesterone / Q000096:biosynthesis; D012333:RNA, Messenger / Q000032:analysis; D013739:Testosterone / Q000494:pharmacology
D007328:Insulin; D012333:RNA, Messenger; D013739:Testosterone; D011374:Progesterone; D004958:Estradiol; D007334:Insulin-Like Growth Factor I; D005640:Follicle Stimulating Hormone