Serum anti-Müllerian hormone dynamics in mares following immunocontraception with anti-zona pellucida or -GnRH vaccines

• Published in: Theriogenology 2018-01, Vol.106, p.214-220
• Main Authors: Joonè, C.J., Schulman, M.L., Fosgate, G.T., Claes, A.N.J., Gupta, S.K., Botha, A.E., Human, A., Bertschinger, H.J.
• Format: Article
• Language: English
• Subjects: Animals; Anoestrus; Anti-Mullerian Hormone - blood; Anti-Mullerian Hormone - metabolism; Contraception; Contraception, Immunologic - veterinary; Female; Gonadotropin-Releasing Hormone - immunology; Horse; Horses - blood; Horses - physiology; Ovarian function; Ovary; Vaccines, Contraceptive - immunology; Zona Pellucida - immunology
• ISSN: 0093-691X; 1879-3231
• DOI: 10.1016/j.theriogenology.2017.10.004

Circulating anti-Müllerian hormone concentration (AMH) is positively correlated to the number of small growing follicles in the mare and may reflect ovarian function. Dynamics of AMH during immunocontraception have not previously been investigated. This study aimed to compare serum AMH in mares following treatment with native porcine zona pellucida (pZP), recombinant pZP3 and pZP4 (reZP) or gonadotrophin releasing hormone (GnRH) vaccines, and saline-treated controls. Stored sera collected during two previous studies examining ovarian activity in mares during zona pellucida (ZP) or GnRH immunocontraception were analysed for serum AMH. Data were compared among treatment groups using mixed-effects linear regression and one-way ANOVA with post hoc testing. Correlations between AMH and previously reported clinical variables were estimated using Spearman's rho. Mares immunized against GnRH showed variable but detectable AMH throughout successive breeding and non-breeding seasons that were not significantly different to unvaccinated control mares. Mares treated with pZP demonstrated marked, reversible suppression of AMH. Mares immunized using reZP showed an intermediate effect. In the ZP study, AMH was positively correlated to serum progesterone concentrations, mean ovarian volumes and antral follicle counts, whereas no correlations between AMH and serum progesterone concentrations, mean ovarian volumes, or the presence of one or more follicles ≥20 mm in diameter were detected in the GnRH study. In conclusion, marked suppression of AMH during pZP immunocontraception, but not during GnRH immunocontraception, suggested enhanced suppression of ovarian follicular development and, or follicular function during pZP immunocontraception. Serum AMH concentrations may provide a novel tool for the assessment of ovarian function during ZP-based immunocontraception. •Anti-Müllerian hormone (AMH) concentration has not previously been assessed during immunocontraception in the mare.•Measurement of AMH provides data that contributes to our understanding of these vaccines’ mechanisms of action.•Mares immunized with native porcine zona pellucida (pZP) vaccine showed a temporary, profound suppression of AMH.•In contrast, mares immunized against GnRH showed little change in AMH over time.•Measurement of AMH may provide an alternative method for monitoring of ovarian function during pZP immunocontraception.