The in vivo effects of fibroblast growth factor and epidermal growth factor on the secretion of oestradiol, androstenedione and progesterone by the autotransplanted ovary in the ewe

Abstract

An experiment was conducted to determine the effects of epidermal growth factor (EGF) and fibroblast growth factor (FGF), infused into the ovarian artery, on the secretion of ovarian steroids during the mid-luteal phase in ewes with an autotransplanted ovary. The infusion of EGF (5 micrograms/h) for 12 h suppressed the secretion of oestradiol and androstenedione during the infusion and for up to 30 h after the infusion. The secretion of progesterone tended to be lower immediately after the infusion (not significant) but had recovered by 24 h after the end of the infusion and then increased significantly (P < 0.05) to rates higher than in control animals. There were no effects of the infusion of EGF on the characteristics of pulsatile LH secretion. FSH concentrations increased 24 h after the end of the infusion probably as an indirect consequence of the changes in oestradiol secretion and not as a consequence of a direct effect of EGF on the hypothalamo-pituitary axis although this latter possibility cannot be unequivocally eliminated. The infusion of FGF (1.5 microgram/h) for 12 h also suppressed the secretion of oestradiol and androstenedione during and for up to 30 h after the infusion. The infusion of FGF had no detectable effect on the secretion of progesterone or the characteristics of pulsatile LH secretion. FSH concentrations increased steadily during the infusion but declined rapidly to below pre-infusion concentrations after the end of the infusion. These data provide tentative in vivo evidence for paracrine and autocrine effects of EGF and FGF on follicular and luteal function in sheep.

The effect of monosaccharide sugars and pyruvate on the differentiation and metabolism of sheep granulosa cells in vitro

“…One of the most widely studied of these alternate pathways is the hexosamine signalling pathway which, via the input of glucose and production of glucosamine-6-phosphate, is able to sense and respond to nutritional fluctuations by altering specific gene expression (Marshall et al 1991, Obici & Rossetti 2003, Curi et al 2005. While the hexosamine pathway has mainly been studied in muscle and fat, it has been shown to be an important pathway in energy metabolism of cumulus-oocyte complexes (Thompson 2006), and genes shown to be responsive to increased glucose via the hexosamine pathway, such as leptin (Wang et al 1998, McClain et al 2000, basic fibroblast growth factor (McClain et al 1992) and transforming growth factor-a (McClain et al 1992), have been shown to modulate ovarian steroidogenesis (Campbell et al 1994, Scaramuzzi & Downing 1995, Spicer & Francisco 1997, Kendall et al 2004). In addition, systemic infusion of glucosamine has been shown to stimulate follicular development in a similar manner to that seen following glucose infusion (Munoz-Gutierrez et al 2002), demonstrating that the hexosamine signalling pathway can induce changes in the ovine ovary and implying glucose may elicit its effects via this pathway.…”

Regulation of serine protease inhibitor-E2 and plasminogen activator expression and secretion by follicle stimulating hormone and growth factors in non-luteinizing bovine granulosa cells in vitro

“…Fibroblast growth factor 2 (FGF-2) stimulated granulosa cell proliferation Bialecki, 1978, 1979) and inhibited FSH-induced estrogen production (Baird and Hsueh, 1986;Vernon and Spicer, 1994;Yamoto et al, 1993). Epidermal growth factor (EGF) promotes cell proliferation (Skinner and Coffey, 1988) and has been associated with a loss of differentiated function such as estradiol production in vitro (Boland and Gosden, 1994;Hsueh et al, 1981;Mason et al, 1990) and in vivo (Scaramuzzi and Downing, 1995).…”

Interactions Between Follicle-Stimulating Hormone and Growth Factors in Modulating Secretion of Steroids and Inhibin-Related Peptides by Nonluteinized Bovine Granulosa Cells1

“…Exposure of granulosa cells to EGF/TGF␣ promotes cell proliferation [26] associated with a loss of differentiated function, exemplified by a marked reduction in E 2 production in vitro [27][28][29][30] and in vivo [31]. Theca cells have been identified as a key site of TGF␣ expression in the bovine ovary and evidence suggests that TGF␣ of thecal origin exerts a local paracrine action on neighboring granulosa cells to modulate their proliferation and responsiveness to gonadotropins and other regulatory factors [26,32].…”