Passive immunization against prostatic 'inhibin' peptide as a male contraceptive

Passive immunization of adult male hamsters for 12 weeks against peptide (As-PIP), a sperm coating antigen, resulted in selective elevation of the blood levels of FSH, impairment of spermatogenesis, and complete infertility when males were mated with normal cycling females. Passive immunization of male marmosets with As-PIP for 8 weeks was also effective and was reversible, without causing any obvious change in mating behaviour. These preliminary studies in hamsters and marmosets indicate that antibodies to a prostatic 'inhibin' peptide represent a promising new approach to male contraception.