Prepubertal genital grooming and penile erections in relation to sexual behavior of rats

The development of genital grooming (GG) and spontaneous penile erections (SPE) was evaluated in socially housed male rats from 25 to 47 days of age, and their sexual behavior was tested from 42 to 74 days of age. GG was the first behavior that appeared (27 days of age) prior to SPE (44 days of age). The values of frequency and duration of GG and SPE showed a gradual increase as puberty was reached. The mean age in which copulatory responses were first observed were: 54.5 days of age for mounts, 55 days of age for intromission and 59 days of age for ejaculation. The proportion of GG bouts that were followed by SPE showed a gradual increase throughout the recording days. A high correlation was found between the early onset and higher frequency of GG and an early onset of sexual behavior. Similarly, higher frequency and/or longer duration of SPE were correlated with an early onset and a better performance of sexual behavior. These results are consistent with previous studies, which suggest an important role of GG on the manifestation of sexual behavior; moreover, considering the high correlation between the occurrence of SPE and sexual behavior, it is possible that, as GG, SPE play an important role in the readiness of adult male rats for reproduction.