Effect of active immunization of heifers against inhibin on plasma FSH concentrations, ovarian follicular development and ovulation rate.
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)
Glencross
R G
RG
AFRC Institute of Grassland and Environmental Research, Hurley, Maidenhead, Berkshire, U.K.
Bleach
E C
EC
McLeod
B J
BJ
Beard
A J
AJ
Knight
P G
PG
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
D007265:Inhibins; D005640:Follicle Stimulating Hormone