title: Effect of active immunization of heifers against inhibin on plasma FSH concentrations, ovarian follicular development and ovulation rate.
abstract: To study the effects of immunoneutralization of endogenous inhibin on gonadotrophin secretion and ovarian function, prepubertal heifers (n = 6) were actively immunized against a synthetic peptide replica of the N-terminal sequence of bovine inhibin alpha subunit (bI alpha(1-29)Tyr30) coupled to ovalbumin. In contrast to ovalbumin-immunized controls (n = 6), bI alpha(1-29)Tyr30-immunized heifers had detectable inhibin antibody titres (% binding to 125I-labelled bovine inhibin at 1:2000 dilution of plasma) of 17 +/- 3% (S.E.M.) at puberty, rising to 31 +/- 5% by the end of the study period 7 months later. Neither age (immunized: 295 +/- 8 days; controls: 300 +/- 5 days) nor body weight (immunized: 254 +/- 13 kg; controls 251 +/- 9 kg) at onset of puberty differed between groups. Although the difference did not reach statistical significance, mean plasma FSH concentrations recorded in inhibin-immunized heifers remained 35-40% higher than in controls throughout the 12-week period leading up to puberty (P = 0.14) and during nine successive oestrous cycles studied after puberty (P = 0.10). Plasma LH concentrations did not differ between groups at any time during the study. Inhibin immunization had no effect on oestrous cycle length (immunized: 19.8 +/- 0.5 days; controls: 19.9 +/- 0.5 days).(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: AFRC Institute of Grassland and Environmental Research, Hurley, Maidenhead, Berkshire, U.K.
authors.forename: R G
authors.initials: RG
authors.lastname: Glencross
authors.forename: E C
authors.initials: EC
authors.lastname: Bleach
authors.forename: B J
authors.initials: BJ
authors.lastname: McLeod
authors.forename: A J
authors.initials: AJ
authors.lastname: Beard
authors.forename: P G
authors.initials: PG
authors.lastname: Knight
mesh_terms: D000818:Animals; D002417:Cattle; D003338:Corpus Luteum / Q000033:anatomy & histology; D004971:Estrus / Q000502:physiology; D005260:Female; D005640:Follicle Stimulating Hormone / Q000097:blood*; D007265:Inhibins / Q000276:immunology / Q000502:physiology*; D006080:Ovarian Follicle / Q000502:physiology*; D010053:Ovary / Q000000981:diagnostic imaging; D010060:Ovulation / Q000502:physiology*; D011863:Radioimmunoassay; D012741:Sexual Maturation / Q000502:physiology; D014463:Ultrasonography; D014611:Vaccination
chemical_list: D007265:Inhibins; D005640:Follicle Stimulating Hormone