title: Active immunization against follistatin and its effect on FSH, follicle development and superovulation in heifers.
abstract: Ovaries of heifers were examined daily by transrectal ultrasonography for one interovulatory interval before initiation of immunizations (control cycle, n = 14), and again after the fifth immunization with a sham-vaccine (Freund's adjuvant only; n = 7) or a recombinant porcine follistatin-vaccine (1 mg per vaccination; n = 7) to study the effect of follistatin on follicle dynamics. After the fifth immunization, 4 heifers had a follistatin antibody titer of > or = 1:3200, while the remaining 3 heifers had a titer of only 1:400. At wave emergence, the total number of follicles and the number of small follicles (3 to 5 mm) were higher (P < 0.05) in the follistatin group than in the control and sham groups. In addition, high-titer heifers had a greater (P < 0.05) number of follicles (total and small) per day than low-titer heifers. Plasma concentration of FSH remained unchanged after sham- or follistatin-immunization. Sham- and follistatin-vaccinated heifers were then given half the standard superovulatory dose of Folltropin (200 mg of FSH) 14 d after the sixth immunization. More ovulations were detected in follistatin- (10.9 +/- 2.4) than sham- (5.0 +/- 0.8) vaccinated heifers (P < 0.05). Moreover, heifers with a high titer had more ovulations (P < 0.02) than heifers with a low titer (15.0 +/- 2.5 vs 5.3 +/- 1.2). The number of ova-embryos classified as fertilized:unfertilized and transferable:discarded, and quality of the embryos were similar between sham and follistatin groups. By 80 d after the last immunization, when antibody titers were undetectable in the follistatin group, there was no difference in superovulatory response between sham (6.7 +/- 1.6) and follistatin (7.6 +/- 1.6) groups. In summary, follistatin immunization was associated with an increase in the number of small follicles at the time of wave emergence and a greater response to superovulatory treatment. The results suggest that effects of follistatin on follicular dynamics were not mediated through changes in pituitary secretion of FSH.
authors.affiliation: Department of Veterinary Anatomy, University of Saskatchewan, Saskatoon, Canada.
authors.forename: J
authors.initials: J
authors.lastname: Singh
authors.forename: G M
authors.initials: GM
authors.lastname: Brogliatti
authors.forename: C R
authors.initials: CR
authors.lastname: Christensen
authors.forename: G P
authors.initials: GP
authors.lastname: Adams
mesh_terms: D000818:Animals; D000906:Antibodies / Q000097:blood; D002417:Cattle / Q000502:physiology*; D003338:Corpus Luteum / Q000502:physiology; D004622:Embryo, Mammalian / Q000502:physiology; D005260:Female; D005640:Follicle Stimulating Hormone / Q000097:blood*; D038681:Follistatin; D006023:Glycoproteins / Q000276:immunology* / Q000502:physiology; D007315:Insemination, Artificial / Q000662:veterinary; D006080:Ovarian Follicle / Q000502:physiology*; D013480:Superovulation; D014611:Vaccination
chemical_list: D000906:Antibodies; D038681:Follistatin; D006023:Glycoproteins; D005640:Follicle Stimulating Hormone