Effects of oestradiol-17β, progesterone or bovine follicular fluid on the plasma concentrations of FSH and LH in ovariectomized Booroola ewes which were homozygous carriers or non-carriers of a fecundity gene

• Published in: Journal of reproduction & fertility Vol. 87; no. 2; p. 573
• Main Authors: McNatty, K P, Hudson, N L, Collins, F, Fisher, M, Health, D A, Henderson, K M
• Format: Journal Article
• Language: English
• Published: England Society for Reproduction and Fertility 01-11-1989
• Subjects: Animals; Estradiol - pharmacology; Female; Fertility; Follicle Stimulating Hormone - blood; Follicular Fluid - physiology; Gonadal Steroid Hormones - pharmacology; Gonadotropins, Pituitary - blood; Homozygote; Hypothalamo-Hypophyseal System - drug effects; Luteinizing Hormone - blood; Ovariectomy; Progesterone - pharmacology; Sheep - genetics
• ISSN: 1470-1626; 0022-4251; 1741-7899
• DOI: 10.1530/jrf.0.0870573

The plasma concentrations of FSH and LH were measured in ovariectomized Booroola FF and ++ ewes before and after treatment
with subcutaneous implants of oestradiol-17β (0, 2 or 8 cm Silastic capsules; 5 ewes/genotype per dose) or progesterone (0,
1 or 3 Silastic envelopes; 5 ewes/genotype per dose) or subcutaneous injections of steroid-free bovine follicular fluid (bFF;
0, 0·5, 1·0, 2·5 or 5 ml; 4 ewes/genotype per dose). During the first 50 h after implantation of oestradiol or progesterone,
or the first 24 h after bFF treatment, the FSH and LH concentrations in plasma were not different between the genotypes although
there were significant effects of the steroids and bFF with respect to dose ( P < 0·05). At 6 days after steroid implantation, no gene-specific effects were noted for the plasma concentrations of FSH although
significant effects of dose of oestradiol ( P < 0·01) but not progesterone were noted. Also at 6 days after steroid implantation, no gene-specific differences in the pulsatile
patterns (i.e. peak frequency or amplitude) of plasma LH concentrations were noted although there were significant effects
of steroid dose ( P < 0·05) on frequency and/or amplitude.
It is concluded that the higher ovulation-rate in FF than ++ Booroola ewes is unlikely to be due to gene-specific differences
in the sensitivity of the hypothalamic– pituitary axis to ovarian hormones.
Keywords: Booroola ewes; oestradiol-17β; progesterone; bovine follicular fluid; FSH; LH; ovariectomy