Synergistic effects of growth hormone and insulin‐like growth factor‐I on differentiation and replication of cultured human luteinized granulosa cells

Abstract

These results indicate a synergistic effect of IGF-I and GH on differentiation and replication of human granulosa cells, and thus support a role of both GH and IGF-I in regulation of ovarian function.

Growth hormone: roles in female reproduction

“…This possibility is indicated by the greater proportion of bovine oocytes manifesting the markers of cytoplasmic maturation (for instance, the ability to decondense sperm chromatin and form sperm asters (Hyttel et al 1989)) in GH-treated cell populations (Izadyar et al 1997(Izadyar et al , 1998. Nuclear maturation is similarly enhanced by GH, since GH-treated bovine oocytes complete meiosis I faster and undergo zygote cleavage and blastocyst formation more frequently than untreated oocytes (Van der Westerlaken et al 1994, Izadyar et al 1996, 1998. This effect of GH is dependent upon cAMP and the presence of cumulus cells but is IGF-Iindependent (Bevers et al 1989, Zuelke & Brackett 1993, Izadyar et al 1997, 1998, Kolle et al 1998.…”

“…Nuclear maturation is similarly enhanced by GH, since GH-treated bovine oocytes complete meiosis I faster and undergo zygote cleavage and blastocyst formation more frequently than untreated oocytes (Van der Westerlaken et al 1994, Izadyar et al 1996, 1998. This effect of GH is dependent upon cAMP and the presence of cumulus cells but is IGF-Iindependent (Bevers et al 1989, Zuelke & Brackett 1993, Izadyar et al 1997, 1998, Kolle et al 1998. GHR mRNA and protein are, moreover, not detected in oocytes from secondary or tertiary follicles of the bovine ovary (Kolle et al 1998); thus, direct actions at the oocyte itself appear unlikely.…”

“…The paucity of IGF-I in human follicles (Mason et al 1990, Ovesen et al 1994, even those treated with GH, would suggest that IGF-I does not mediate steroidogenic effects of GH in humans. Indeed, IGF-I independence is also indicated by the synergistic effect of GH and IGF-I/ IGF-II on oestradiol production in human (Ovesen 1998) granulosa cells. However, IGF-I antibodies significantly inhibit GH effects on oestradiol production in human granulosa cells (Barreca et al 1993).…”

“…The folliculogenic effect of GH, at least in human luteinized granulosa cells, is dependent upon FSH and independent of IGF-I (Ovesen et al 1994, Ovesen 1998). …”

Presumptive Mediators of Growth Hormone Action on Insulin-Like Growth Factor I Release by Porcine Ovarian Granulosa Cells

“…Most in vivo effects of GH are accompa-nied by an increase in insulin-like growth factor I (IGF-I) concentrations in the blood [7][8][9][10] and follicular fluid [7,9]. In vitro, GH is able to amplify gonadotrophin action, stimulate follicular growth and steroidogenesis, and promote the replication of granulosa cells [11][12][13]. It also stimulates IGF-I release from cultured granulosa cells and follicles in a range of species [14][15][16][17] and from the perfused rabbit ovary [11].…”