Perinatal hormones and genital anesthetization: Effects on masculine sexual behavior of rats

Abstract

Masculine copulatory behavior was evaluated in male and female rats under normal testing conditions and after application of a topical anesthetic to the penis or clitoris. Males had been castrated at birth or at 27 days of age. Females had received either testosterone propionate or control injections during the first 26 days of life. Genital anesthetization prevented the occurrence of intromission and ejaculation patterns in all groups. The masculine sexual behavior observed under conditions of genital anesthetization was comparable across groups, with the exception that females, when tested under these conditions, exhibited lower mount-bout frequencies than did males. However, these differences were not apparent when sexual behavior was evaluated in unanesthetized animals. Females also exhibited longer latencies to mount under anesthetization as compared with control testing conditions. When these differences in latency were taken into consideration, the differences in mount-bout frequency were not apparent. Males that remained intact during development showed shorter latencies to initiate copulatory behavior and more mounts per mount bout as compared with all other groups. The results are interpreted as being consistent with the hypothesis that genital factors account for sex differences observed for androgen-stimulated copulatory behavior in rats.