Aging and sociosexual behavior in the male rat

Senescent and young rats have been studied in a copulatory test and sociosexual approach test. The copulatory test was applied to investigate age-dependent changes in the copulatory capacity in the rat. The sociosexual approach test was used to describe motivational aspects of this behavior. Latencies, frequencies and durations of copulatory behaviors in the copulatory test and visits to various incentive animals in the approach test have been measured. Senescent rats had longer latencies and less frequencies of copulatory behaviors. In the approach test they showed less visits to the estrous female. Data were also subjected to a correlational analysis in order to relate the findings of the two tests. It is concluded that aged male rats differ from young ones in organizing their behavior in relation to time, are less social and have a less pronounced social preference pattern. In addition, the coherence between various elements of copulatory behavior was less in the senescent rat than in the young male rat, whereas the social approach patterns are more coherent in the aged male.