Role of gonadotropins and insulin in controlling steroidogenesis and growth of antral bovine follicles in perifusion culture

• Published in: Theriogenology Vol. 28; no. 4; pp. 503 - 512
• Main Authors: Peluso, J.J., Hirschel, M.D.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.10.1987
• Subjects: bovine; follicle; FSH; insulin; bovine; FSH; insulin; LH; follicle
• ISSN: 0093-691X; 1879-3231
• DOI: 10.1016/0093-691X(87)90255-X

Bovine follicles (2 to 4 mm in diameter) were isolated from the ovaries of 4-to 6-mo-old Holstein calves and placed in perifusion culture. Groups of 6 to 8 follicles/flask were cultured for 4 or 21 h with 1) no hormones; 2) tonic follicle-stimulating hormone (FSH) (10 ng/ml) and luteinizing hormone (LH) pulses (4 ng/ml) once every 4 h; 3) insulin (200 I.U./l); or 4) tonic FSH, LH pulses and insulin. After 0, 4 and 21 h of perifusion culture, each follicle was incubated in 1 ml of medium containing 3(H)-thymidine for 1 h. The 3(H)-thymidine incorporated into DNA of the follicle as well as the amount of estradiol-17 (E2) and testosterone (T) secreted into the medium were determined. Follicles treated with or without gonadotropins secreted higher levels of E2 and T after 4 h of perifusion compared to the 0 h controls. This elevated secretion rate was not maintained and 3(H)-thymidine incorporation was not increased over 0 h control values after 21 h of culture. Insulin suppressed the T secretion after 4 h in culture and increased 3(H)-thymidine incorporation at both 4 and 21 h of culture. After 21 h of culture, the gonadotropin and insulin treatment also enhanced 3(H)-thymidine incorporation. These results demonstrate that insulin is more mitogenic than the gonadotropin treatment tested, suggesting that insulin or insulin-like factors may play a physiological role in the growth of bovine follicles in vivo.