Induction of male mating behavior in androgen-insensitive (tfm) and Normal (King-Holtzman) male rats: effect of testosterone propionate, estradiol benzoate, and dihydrotestosterone

Castrated androgen-insensitive rats exhibited mounting and intromission patterns in response to testosterone propionate (TP), estradiol benzoate (EB), or EB combined with dihydrotestosterone (DHT) treatment in adulthood. Treatment with DHT alone was ineffective in stimulating male mating behavior in the mutant rats. Since androgen-insensitive rats, like normal males, have the potential to show mounting behavior following hormone treatment in adulthood, the neural substrate underlying this behavior must be masculinized during development. The effectiveness of gonadal hormones in activating the entire copulatory sequence in castrated littermate males (King-Holtzman) was also examined. TP treatment induced mating behavior in the control rats. DHT also stimulated the complete copulatory pattern, although it was not as effective as TP. The administration of EB, however, did not induce ejaculation in control rats. These results do not support the hypothesis that the activation of male mating behavior by testosterone requires its metabolite estrogen (aromatization hypothesis).