Testosterone, puberty, and the pattern of male aggression in Syrian hamsters.

The interaction between testosterone and pubertal development on aggression in the male Syrian hamster (Mesocricetus auratus) was examined in two experiments. First, gonad-intact prepubertal and adult male hamsters were tested for aggression using the resident-intruder paradigm with an age- and weight-matched intruder. Prepubertal males engaged in a greater number of attacks and had longer attack durations than adults. In the second experiment, prepubertal and adult males were castrated and treated with either a 0-, 2.5-, or 5-mg pellet of testosterone, and their aggression was assessed using the resident-intruder paradigm. Prepubertal males again showed shorter attack latencies and greater attack durations compared to adult males across all levels of testosterone. Testosterone treatment did not significantly affect these behaviors before or after pubertal development. We conclude that (a) pubertal development is associated with a decline in aggression in the male Syrian hamster, and (b) a developmental shift in behavioral sensitivity or responsiveness to testosterone does not underlie the pubertal decrease in aggression.