Resistance of androgen-mediated aggressive behavior in mice to flutamide, an antiandrogen.

Flutamide (FTA), an anti-androgenic compound, inhibited the effects of methyltestosterone (MT) on the weight of the ventral prostate, seminal vesicles and levator ani in male castrate mice. Castration prevented the development of aggressive behavior in mice isolated for 3 weeks. While chronic administration of MT to castrate isolated mice returned the incidence of fighting behavior to control values, chronic administration of FTA + MTdid not significantly reduce the incidence of fighting as compared to castrate + MT values. These results suggest that the mechanism for androgen stimulation of secondary sex organ weight may differ from that involved in the development and maintenance of aggression resulting from isolation.