Immunization of rats and sheep against granulosa cell-inhibitory factor from bovine follicular fluid increases the number of large follicles in rats and the ovulation rate in sheep

Abstract

Granulosa cell-inhibitory factor (GCIF), a low molecular weight factor from bovine follicular fluid, inhibits the proliferation of bovine granulosa cells in vitro and the growth of large follicles in rats in vivo. In this study the effects of (1) immunization of rats against GCIF on follicular growth and (2) immunization of sheep against GCIF on ovulation rate were studied. The ability of antiserum from sheep immunized against GCIF to reduce the inhibitory effect of GCIF on bovine granulosa cell proliferation in culture was also examined. Immunization of rats against GCIF increased the number of large follicles (P < 0.001) but decreased the number of small follicles (P < 0.05) per ovary. Ovarian mass (P < 0.05) and uterine wet (P < 0.05) and dry (P < 0.01) masses were increased in immunized rats. Immunization of sheep against GCIF, followed by boosting over two breeding seasons, increased ovulation rate (P < 0.01). Addition of antiserum from sheep immunized against GCIF reduced or abolished the inhibitory effect of GCIF on granulosa cell proliferation (P < 0.01). These data provide further evidence that GCIF has an important role in controlling follicle growth and ovulation in vivo.

Effect of a partially purified 30.1 kDa ovine follicular fluid protein on ovine follicle and ovarian somatic cell growth, and oocyte maturation in vitro

“…There were also changes in the relative rate of synthesis of specific proteins during oocyte maturation that was independent of follicle size from which the oocytes were collected (Lequarrea et al 2005). Changes in the capacity of granulosa cells to metabolize androgens to oestrogens have been suggested to be a physiologically significant mechanism for determining the maturational fate of individual follicles (Hynes et al 1999). In contrast, the present study indicated that the 30.1 kDa protein decreased cumulus expansion and total protein content of oocytes.…”

“…A 28-kDa protein secreted from granulosa cells was found to increase cumulus expansion but had no effect on overall protein synthesis by oocytes (Rabahi et al 1993). Treatment of granulosa cells with FSH, the major stimulator of follicular maturation, induced high concentrations of aromatase enzymes, which convert androgens to oestrogens (Hynes et al 1999). The oFFP was inhibitory for cumulus, granulosa and oviductal cell proliferation in vitro.…”

“…Therefore, any factors that modulate the effects of these hormones on granulosa cells could play a role in the selection of a dominant follicle. Changes in the capacity of granulosa cells to metabolize androgens to oestrogens have been suggested to be a physiologically significant mechanism for determining the maturational fate of individual follicles (Hynes et al 1999). Treatment of granulosa cells with FSH, the major stimulator of follicular maturation, induced high concentrations of aromatase enzymes, which convert androgens to oestrogens (Hynes et al 1999).…”

“…To test the hypothesis that the effect of the oFFP on follicular somatic cells was mediated by the FSH or other potent stimulators of granulosa cell growth (epidermal growth factor, EGF; insulin-like growth factor-I, IGF-I; Hynes et al 1999), the granulosa cells (1.0 · 10 5 cells per culture drop) were cultured in eight media: (1) TCM-199 + BSA (0.3%)-control, (2) TCM-199 + BSA (0.3%) + FSH (0.5 lg L )1 ), (3) TCM-199 + BSA (0.3%) + oFFP (500 ng L )1 ), (4) TCM-199 + BSA (0.3%) + FSH (0.5 lg L )1 ) + oFFP (500 ng L )1 ), (5) TCM-199 + BSA (0.3%) + EGF (10 ng L )1 ) + IGF-I (10 ng L )1 ), (6) TCM-199 + BSA (0.3%) + EGF (10 ng L )1 ) + IGF-I (10 ng L )1 ) + oFFP (500 ng L )1 ), (7) TCM-199 + BSA (0.3%) + EGF (10 ng L )1 ) + IGF-I (10 ng L )1 ) + FSH (0.5 lg L )1 ), (8) TCM-199 + BSA (0.3%) + EGF (10 ng L )1 ) + IGF-I (10 ng L )1 ) + FSH (0.5 lg L )1 ) + oFFP (500 ng L )1 ). The granulosa cells were cultured for 2 days, harvested and then counted in a haemocytometer.…”

Mouse Ovarian Follicles Secrete Factors Affecting the Growth and Development of Like-Sized Ovarian Follicles In Vitro1

“…Subsequently, steroid-free ovine follicular fluid was shown to lower steroid secretion from the ovary, with an associated decrease in P450 arom and inhibin-activin ␤ b subunit [12,24]. Granulosa cell-inhibitory factor (GCIF), a factor obtained from steroid-free bovine follicular fluid, has been shown to inhibit rat and bovine follicle growth and development [13,14], whereas immunization of sheep against GCIF increased the ovulation rate [25]. Similar factors have been reported both in the pig [26] and the rat [27].…”