Sexual behavior of aging male rats is stimulated by oxytocin.

The effect of oxytocin on male sexual behavior was investigated in sexually normal or sexually sluggish 20-month-old rats. Rats were tested seven times, at weekly intervals, for copulatory behavior in the presence of receptive females. Oxytocin (0.1 microgram), injected intraperitoneally 60 min before the eighth test, significantly shortened the mount, intromission and ejaculation latencies and post-ejaculation intervals, the effect being proportionately greater in the sexually sluggish rats. These data confirm that oxytocin plays a facilitatory role in mating behavior and suggest that it may prove useful in conditions of copulatory inadequacy.