Insulin-Like Growth Factors (IGFs) as Autocrine/Paracrine Regulators in the Porcine Ovarian Follicle
Our laboratory was attracted to ovarian growth factors as a potential mechanism for regulating the growth and development of the ovarian follicle. At the time we began our studies, it was known that peptide growth factors were potent mitogens for granulosa cells of the pig and other species (1,2). In addition, insulin at high concentrations was known to influence granulosa cell growth and differentiation (3), but effects of IGFs on ovarian cells had not been shown. In the process of investigating the hormonal regulation of the growth-related enzyme ornithine decarboxylase, we discovered that the IGF multiplication stimulating activity (MSA, rat IGF-II) was an extremely potent stimulator of this activity in porcine granulosa cells and was considerably more potent than insulin (4,5). As reviewed below, the characterization of IGF effects on granulosa cell replication and the interaction of the insulin-like factors with other growth factors on these responses has continued to be an interest of our laboratory. In addition, studies from our group (6), as well as more numerous data from others represented at this symposium, indicated that the IGFs had stimulatory effects on the cytodifferentiation of ovarian cells. Accordingly recent studies have focused on the relative importance of the growth-promoting and steroidogenic effects of insulin-like factors on porcine granulosa cells.
KeywordsGranulosa Cell Progesterone Secretion Porcine Granulosa Cell Porcine Ovary Multiplication Stimulate Activity
Unable to display preview. Download preview PDF.
- 5.Hammond JM, Yoshida K, Veldhuis JD, Rechler MM, Knight AB. Intrafollicular role of somatomedins: comparison with effects of insulin. In: Greenwald GS, Terranova P, eds. Factors regulating ovarian function. New York: Raven Press, 1983:197–201.Google Scholar
- 7.Tissue growth factors. Daughaday WH, ed. Clinics in endocrinology and metabolism; vol 13, no 1. Philadelphia: WB Saunders Company, 1984.Google Scholar
- 14.Mondschein JS, Canning SF, Hammond JM. Effects of transforming growth factor beta on the production of immunoreactive insulin-like growth factor-I and progesterone and on 3H-thymidine incorporation in porcine granulosa cell cultures. Endocrinology 1988 (in press).Google Scholar
- 16.Hernandez ER, Hoyt E, Van Wyk JJ, Adashi EY. The somatomedin-C/insulin-like growth factor-I (Sm-C/IGF-I) gene is expressed in the rat ovary. Annual Meeting of the Endocrine Society, 1987.Google Scholar
- 22.Hammond JM, Hsu C-J, Mondschein JS, Canning SF. Paracrine and autocrine functions of growth factors in the ovarian follicle. J Anim Sci 1988; 66:21–31.Google Scholar
- 24.Mondschein JS, Canning SF, Hammond JM. Profiles of immunoreactive (i) insulin-like growth factors (IGFs) -I and -II in porcine follicular fluid (FF) and granulosa cell conditioned medium (GCCM) [Abstract]. Biol Reprod 1988; 38(suppl 1):191.Google Scholar
- 28.Bryan KA, Hammond JM, Canning S, et al. Reproductive and growth responses of gilts to exogenous porcine pituitary growth hormone. J Anim Sci 1988 (in press).Google Scholar