Self-injurious behavior is decreased by cyproterone acetate in adult male rhesus (Macaca mulatta)

Self-injurious behavior (SIB) presents a serious problem in laboratory maca ques that cannot be socially housed for scientific reasons and among instit utionalized children and adults where it is often associated with different forms of brain dysfunction. We have experienced limited success in reducin g SIE in macaques by enhancing their environment with enrichment devices. P sychotropic drugs also help, but problems are associated with their use. Be cause sexual and aggressive behavioral problems in men have been treated wi th progestational drugs, we tested the efficacy of cyproterone acetate (CA, 5-10 mg/kg/week) on reducing SIE in 8 singly housed, adult male rhesus mac aques. The main findings were: (1) SIE and other atypical behaviors were si gnificantly reduced during CA treatment; (2) serum testosterone was signifi cantly reduced during CA treatment; (3) cerebral spinal fluid (CSF) levels of 5HIAA and HVA, metabolites of serotonin and dopamine, respectively, decl ined significantly during CA treatment; (4) the duration of SIE positively correlated with levels of 5HIAA in CSF; but (5) sperm counts were not reduc ed during treatment. Thus, CA was a partially effective treatment (3 months ) for adult mate macaques whose behavioral problems include SIE. In summary , CA reduced SIE, overall aggression, serum testosterone, CSF 5HIAA, and CS F HVA. We hypothesized that the progestin activity of CA represses the hypo thalamic gonadal axis and decreases testosterone, which in turn decreases S IE. In addition, we speculate that the decrease in 5HIAA and HVA in CSF may have been caused by progestins decreasing the activity of MAO. Therefore, the reduction of SIE may also be related to an increase in the availability of active monoamines in the CNS. (C) 1999 Academic Press.