Effects of medroxyprogesterone acetate on social behavior in female rhesus macaques (Macaca mulatta) depend on male breeding season introductions.

BackgroundAlthough medroxyprogesterone acetate (MPA) is used commonly as a contraceptive in women and female non-human primates, its effects on social behavior remain unclear. This study examined whether MPA treatment and introduction of new adult males during the breeding season influence the social behaviors of group-housed adult female rhesus macaques.MethodsSubjects were 12 MPA-treated and 12 matched case-control females. Aggressive, affiliative, and sexual behaviors were measured.ResultsMPA-treated females showed less affiliative and sexual behavior compared to matched controls during the breeding season. MPA treatment was associated with decreased aggression emitted toward and received from females during the breeding season.ConclusionMPA treatment is associated with differences in social behavior of female rhesus macaques during the breeding season, when normal hormonal cycles are attenuated by the treatment, but there is no indication that MPA-treated females bring an additional risk for more aggression during the male introduction and breeding season.