Learned aversion to the odors of male mice: Effects on agonistic behavior

Abstract

Intact and castrate male mice were subjected to avoidance training using the urine of intact and castrate donors as stimuli. Both intacts and castrates learned to discriminate between the odors, with such learning modifying their spontaneous responsiveness to such odors in an open field in the predicted direction. This result suggests that the previously reported lack of responsiveness in castrates [15] was not due to a simple sensory deficit. A second experiment determined that increasing the relative aversion exhibited by intact subjects to the odors of intact donors also increased the subject's aggression directed at a castrate opponent swabbed with such odors. Modification of castrates' responsivity had no such effect on their aggression. This indicated that replacing the responsivity to aggression-related odors which is lost following castration, is not equivalent to replacing the hormone. The results are discussed with regard to possible hormonal effects on the social significance of olfactory cues to the recipient animal.