Environmental influences on masculine sexual behavior in mice

Retention of masculine copulatory behaviors following castration varies among B6D2F1 male mice. In the present study, we examined the effect of test environment and the amount of behavioral testing after castration, on retention of copulatory responses in castrated B6D2F1 male mice. Results showed that weekly behavioral testing after castration was not necessary for the retention of ejaculatory reflexes. However, the test environment had a major effect. Following castration, 26% of the males completely stopped showing ejaculatory responses when tested in the test arenas. When these males were tested in their home cages, 75% achieved at least one ejaculatory response in four home cage tests. Castrated males that continued to copulate in the test arena situation also achieved ejaculatory reflexes in their home cages. These results indicate that for some B6D2F1 males, the retention of sexual behaviors after castration is influenced by environmental factors.