Disruption of sexual behavior in socially isolated adult male rats

The effect of social isolation on adult male sexual behavior was investigated. Seven Sprague—Dawley-derived male rats were placed in individual cages when 63 days old. An additional seven remained in an all-male colony cage. When 258 days old, the sexual behavior of all 14 males was tested. The sexual behavior of the isolated rats was disrupted. In the first two tests none of the isolated males exhibited either intromission or ejaculation, whereas six out of the seven non-isolated males both intromitted and ejaculated. For most of the isolated males, the disruption was reversible; by test 15, five of the seven were performing indistinguishably from nonisolated males. These data indicate that social isolation of adult males disrupts sexual behavior.