Chemical castration with cyproterone acetate (Androcur®) and sexual behavior in the laboratory-housed male stumptailed maceque (Macaca arctoides)

Seven pairs of stumptailed monkeys were tested twice weekly (30-min behavior tests) and female-male interactions scored while males received IM injections of CA for 12 weeks, or oil vehicle. Paris served as their own controls. CA was injected in increasing doses: 6 weeks, 100 mg/week/♂, 2 weeks 150 mg/week/♂, 4 weeks 210 mg/week/♂. Serum testosterone levels were significantly lowered during CA, whereas serum cortisol was not affected by CA. Testis size also decreased with CA. Male sexual behavior (frequency of mounts and ejaculations) was increased significantly with CA. Sexual motivation, as measured by latency to first mount and to first ejaculation was not affected. During CA treatment the males became more social: they significantly groomed their female partner longer. This study also revealed striking intra-pair consistencies and inter-pair differences. It is concluded that cyproterone acetate does not diminish libido and potency in the male stumptailed monkey. It is discussed that in the human male CA probably does exert its sexual inhibition through anxyolitic-tranquilizing action, rather than through its hormonal action.