Recovery of sexual activity with experience in aged male mice.

Aged CBF1 male mice that have been housed in isolation for prolonged periods of time often fail to show any sexual behavior when exposed acutely to receptive females. To separate the potential effects of social isolation from those of aging, the sexual responsiveness of aged males was tested both before and after a series of five-day pairings with young females. About one-half of the old males showed a complete recovery of their sexual responsiveness following these repeated pairings. Other aged males showed only a partial recovery and still others remained totally unresponsive. Changes in physical endurance, testicular steroid titer and arousability are posed as possible bases for those instances of sexual recovery that were observed.