title: Systemic concentrations of endogenous and exogenous FSH in anoestrous ewes superstimulated with folltropin-V.
abstract: The synchronization of follicular waves with medroxyprogesterone acetate (MAP) and oestradiol-17beta (E(2)-17beta) prior to ovarian superstimulation in anoestrous ewes reduces the variability in superovulatory responses by an unknown mechanism. Follicle stimulating hormone (FSH) is a primary promoter of antral follicular development, but the relevance of circulating FSH concentrations to the superovulation performance in ewes has not been examined. Eighteen anoestrous Rideau Arcott ewes (May-June) were superovulated with Folltropin-V (porcine FSH), with (n = 8; treated ewes) or without (n = 10; control ewes) a single i.m. dose of 350 microg of E(2)-17beta, given on the sixth day of a 14-day treatment with MAP-releasing intravaginal sponges (60 mg). The superovulatory treatment, begun 6 days after E(2)-17beta injection, consisted of six i.m. applications of Folltropin-V given twice daily (at 08:00 and 16:00 h), followed by an i.m. injection of GnRH (50 microg). Blood samples collected every 8 h throughout the 3-day treatment, were analysed by radioimmunoassays for concentrations of ovine and porcine FSH, using species-specific standards and primary antibodies. Serum concentrations of oFSH were greater (p < 0.05) in the controls compared to treated ewes at 40, 64 and 72 h and the variability in mean oFSH concentrations was greater (p < 0.05) in control ewes at 40, 48, 64 and 72 h after the 1(st) Folltropin-V injection. There were no differences (p > 0.05) between the two groups in serum concentrations of pFSH. Significant correlations were recorded between the number of corpora lutea (CL) and oFSH concentrations at 8 h (r = 0.72, p < 0.05), 16 h (r=0.63, p < 0.05) and 64 h (r = 0.84, p < 0.01) after the 1(st) Folltropin-V injection. The total number of recovered embryos was positively correlated to oFSH concentrations at 56 h (r = 0.69, p < 0.05). We concluded that changes in endogenous FSH concentrations during ovarian superstimulation with pFSH might contribute to the variability in superovulatory responses in ewes.
authors.affiliation: Department of Biomedical Sciences, Ontario Veterinary College, University of Guelph, Guelph, Ontario, Canada. pmbart@uoguelph.ca
authors.forename: P M
authors.initials: PM
authors.lastname: Bartlewski
authors.forename: K J
authors.initials: KJ
authors.lastname: Fuerst
authors.forename: B D
authors.initials: BD
authors.lastname: Alexander
authors.forename: W A
authors.initials: WA
authors.lastname: King
mesh_terms: D000282:Administration, Intravaginal; D000780:Anestrus; D000818:Animals; D001947:Breeding; D003338:Corpus Luteum / Q000033:anatomy & histology; D004624:Embryo Transfer / Q000662:veterinary; D047108:Embryonic Development; D004958:Estradiol / Q000008:administration & dosage; D005260:Female; D005640:Follicle Stimulating Hormone / Q000008:administration & dosage* / Q000097:blood*; D007987:Gonadotropin-Releasing Hormone / Q000008:administration & dosage; D034461:Luteinization; D017258:Medroxyprogesterone Acetate / Q000008:administration & dosage; D006080:Ovarian Follicle / Q000033:anatomy & histology; D011247:Pregnancy; D012756:Sheep / Q000378:metabolism*; D013480:Superovulation / Q000097:blood*; D013552:Swine
chemical_list: D007987:Gonadotropin-Releasing Hormone; D004958:Estradiol; D005640:Follicle Stimulating Hormone; D017258:Medroxyprogesterone Acetate