Testosterone rapidly affects the expression of copulatory behavior in house mice (Mus musculus).

Male mammals reflexively release an endogenous pulse of testosterone in response to either a female or her urinary pheromones. Two experiments examined the hypothesis that such pulses have quick-acting effects upon the expression of reproductive behavior in male house mice. In Experiment 1, 30 min after exposure to female urine, males exhibited significantly reduced latency to mount a receptive female (when they should have been expressing an endogenous testosterone pulse). In Experiment 2, gonadally intact males received a simulated testosterone pulse via a subcutaneous injection of 500 microg of testosterone propionate. At 60 min after injection, males mounted a receptive female significantly more quickly than if they had not received such an injection. These experiments provide evidence that elevations in testosterone titers above baseline can, under certain conditions, rapidly alter the expression of male-typical behaviors.