Active immunization of boars against gonadotrop in releasing hormone. I. Effects on reproductive parameters

Sexually mature boars were actively immunized against gonadotropin releasing hormone (GnRH) to characterize endocrine and gametogenic changes associated with immunoneutralization of endogenous GnRH. Injections of GnRH conjugated to bovine serum albumin (BSA) given five times over 24 wk induced production of antibodies against GnRH in all animals (n=5). Active immunization against GnRH reduced serum concentrations of testosterone (P<0.05) and luteinizing hormone (LH) (P<0.05), testes volume (P<0.01), paired testis weights (P<0.05), paired epididymis weights (P<0.05), sperm per testis (P<0.01) and seminiferous tubule diameters (P<0.001) when compared with controls (n=4). These results indicate that both steroidogenic and spermatogenic functions are impaired in testes of mature boars actively immunized against GnRH.