'Roid rage in rats? Testosterone effects on aggressive motivation, impulsivity and tyrosine hydroxylase

► We tested effects of chronic, high-dose testosterone on aggressive motivation and impulsivity in male rats. ► Testosterone did not enhance motivation for aggression, but did increase fighting. ► Testosterone reduced impulsivity in a delay-discounting test for food reward. ► Testosterone selectively reduced levels of tyrosine hydroxylase in caudate-putamen.