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.