MENDON�A, M.T.; Auburn University: Flutamide and fadrazole are ineffective in blocking the expression of male mating behavior in big brown bats.

Male big brown bats mate in late fall and upon arousal from hibernation conditions throughout the winter, a time when testes are regressed and plasma testosterone levels are relatively low. Over the last several years, we have been exploring the relative effects of sex steroids and temperature change on the expression of mating behavior in the big brown bat, Eptesicus fuscus. We have found the gonadectomy has little effect on the expression of male mating behavior whereas exposure to hibernation conditions potentiates the expression of mating upon subsequent arousal from hibernation. To further test the degree to which male mating behavior is influenced by androgens, we conducted a series of experiments in which we administered either flutamide (an anti-androgen), fadrazole (an aromatase inhibitor), or blank Silastic capsules to both gonadectomized and intact males over a period of two weeks and observed their subsequent mating behavior while implanted. In some of the experiments, we then removed the capsules, observed the subsequent behavior, and then re-administered the same treatments. Male mating behavior was not significantly decreased by either flutamide or fadrazole treatment indicating that male mating behavior in this species is relatively independent of the activational effects of androgens.