Insulin-like growth factor-I receptors in ovarian granulosa cells: effect of follicle size and hormones.
The objectives of the present studies were to determine if the numbers of IGF-I receptors in bovine granulosa cells differed with size of follicle and to determine if growth factors and hormones affected the number of IGF-I receptors in granulosa cells. Granulosa cells from small (1-5 mm) and large (> or = 8 mm) follicles were cultured for 2-4 days in 10% FCS and then assessed for levels of IGF-I receptors. Numbers of IGF-I receptors were 15-fold greater in granulosa cells from large than small follicles. In addition, bFGF (5 and 50 ng/ml) decreased whereas estradiol (1 microgram/ml), FSH (10 ng/ml) and EGF (10 and 100 ng/ml) increased the number of IGF-I receptors in granulosa cells from small follicles. These hormones had no effect on the number of IGF-I receptors in granulosa cells from large follicles. In conclusion, granulosa cells from large follicles have a greater number of IGF-I receptors than cells from small follicles, and thus, it appears that granulosa cells acquire a greater number of IGF-I receptors during the process of differentiation.
Spicer
L J
LJ
Department of Animal Science, Oklahoma State University, Stillwater 74078.
Alpizar
E
E
Vernon
R K
RK
D000818:Animals; D002417:Cattle; D002452:Cell Count; D002478:Cells, Cultured; D004815:Epidermal Growth Factor / Q000494:pharmacology; D004958:Estradiol / Q000494:pharmacology; D005260:Female; D016222:Fibroblast Growth Factor 2 / Q000494:pharmacology; D005640:Follicle Stimulating Hormone / Q000494:pharmacology; D006107:Granulosa Cells / Q000187:drug effects / Q000378:metabolism*; D006080:Ovarian Follicle / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D011869:Radioligand Assay; D017526:Receptor, IGF Type 1 / Q000187:drug effects / Q000378:metabolism*
D016222:Fibroblast Growth Factor 2; D004958:Estradiol; D004815:Epidermal Growth Factor; D005640:Follicle Stimulating Hormone; D017526:Receptor, IGF Type 1