Studies in wild house mice. II. Testosterone and aggression

Area of Science:

• Behavioral Endocrinology
• Animal Behavior Genetics
• Neuroendocrinology

Background:

• Individual differences in aggression are common in wild house mice.
• Testosterone is a key hormone influencing aggressive behaviors.
• Understanding the genetic basis of behavioral variation requires physiological insights.

Purpose of the Study:

• To investigate the relationship between testosterone levels and attack latency in genetically distinct wild house mice.
• To elucidate the physiological mechanisms underlying individual differences in aggression.
• To explore the role of early-life testosterone exposure on adult aggressive behavior.

Main Methods:

• Surgical castration was performed on genetically diverse wild house mice.
• Subsequent testosterone therapy was administered to assess dose-response effects.
• Attack latency was measured as an indicator of aggressive behavior.

Main Results:

• Individual variation in attack latency correlated with baseline plasma testosterone levels in a dose-response manner.
• Responsiveness to testosterone, particularly during pre-puberty, significantly influenced attack latency.
• In fast-attacking mice, mature attack latency was maintained independently of testosterone; this was not observed in reluctant attackers.

Conclusions:

• Both baseline testosterone levels and early-life testosterone sensitivity contribute to individual differences in mouse aggression.
• The maintenance of aggressive behavior in adulthood is differentially regulated by testosterone depending on an individual's baseline attack propensity.
• Findings provide crucial physiological data for future research into the genetic underpinnings of behavioral variation.