Activation of male-typical aggression by testosterone but not its metabolites in C57BL/6J female mice.

Ovariectomized adult C57BL/6J mice were exposed to androgens, estrogens, or combined androgen-estrogen treatments and tested for the display of male-typical aggressive behavior toward olfactory bulbectomized stimulus males. Among the androgenic treatments (testosterone, dihydrotestosterone, or methyltrienolone) only testosterone, which, in contrast to the other androgens, can be aromatized, activated fighting behavior. In the second experiment, estradiol benzoate (EB) was totally ineffective as an aggression-promoting compound. Lastly, combined EB+dihydrotestosterone also did not induce male-like aggression. These data suggest that T itself may be capable of promoting aggression without undergoing aromatization or 5 alpha-reduction.