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Updated: Aug 19, 2026
Assessment of Sexual Behavior of Male Mice
Published on: March 5, 2020
Individual differences in the attack behavior of male mice: a function of attack stimulus and hormonal state
Abstract:
Male CFW mice were tested for fighting behavior directed against olfactory bulbectomized male mice and against lactating female mice. Some males were tested with each stimulus type before and after castration. Some males were tested first following castration and then after testosterone treatment. All gonadally intact males attacked bulbectomized males and 25% attacked lactating females. After castration 81% attacked males on at least one occasion and 62% began to attack lactating females, although individual differences in the pattern of post-castration behavior were large. Individual differences in attack behavior were also large in males whose first tests followed castration. Of these, 60% attacked both stimuli. Following testosterone treatment, attack against males increased while attack against females was inhibited. Hormonal stimulation reduced individual differences in behavior and increased males' discrimination between the two types of stimuli.
Insights
Castration increased aggression in male mice towards other males and females, but testosterone treatment later inhibited female-directed aggression. Hormonal changes influenced fighting behavior and stimulus discrimination in male mice.
Area of Science:
- Neuroscience
- Behavioral Endocrinology
- Animal Behavior
Background:
- Aggression is a complex behavior influenced by hormones.
- The role of androgens in modulating aggression is well-established.
- Understanding hormonal influences on aggression is crucial for behavioral studies.
Purpose of the Study:
- To investigate the effects of castration and testosterone replacement on male mouse aggression.
- To examine behavioral responses to different social stimuli (bulbectomized males vs. lactating females).
- To analyze hormonal impacts on individual differences and stimulus discrimination in fighting behavior.
Main Methods:
- Male CFW mice were subjected to behavioral testing for fighting.
- Stimulus targets included olfactory bulbectomized male mice and lactating female mice.
- Experimental conditions involved testing before and after castration, and after testosterone treatment.
Main Results:
- Gonadally intact males attacked bulbectomized males; some attacked lactating females.
- Castration increased attack rates towards both male and female stimuli, with significant individual variation.
- Testosterone treatment increased male-directed aggression while inhibiting female-directed aggression.
- Hormonal manipulation reduced individual behavioral differences and enhanced stimulus discrimination.
Conclusions:
- Hormonal status significantly modulates aggression and social discrimination in male mice.
- Testosterone plays a key role in maintaining male-directed aggression and inhibiting female-directed aggression.
- The study highlights the dynamic interplay between hormones, behavior, and social context.
