Changes in female sexual behavior of old female rats: comparison between exit method and non-exit method.

The female sexual behavior including proceptivity, receptivity and sociosexual behavior of preferential approach to males was tested in 12 young adult female rats aged from 6 to 7 months and in 59 old female rats aged from 18 to 21 months with the exit method and the traditional non-exit method. The percentage of rats displaying a high lordosis quotient (LQ) and that of rats showing solicitation were lower in old females than in young females tested either with the non-exit method or the exit method. Only with the non-exit method were the mount frequency per minute of male rats toward old females of the high-LQ group and the solicitation score of old female rats lower as compared to young females. The incidence of preferential approach of the female rats, whether young or old, toward intact young males and their time spent in the compartment of intact young males were not different, however, the frequency of old female rats to visit the arena of intact young males was lower than that of young females. In summary, the major age-related changes in female sexual behavior, the low percentage of rats displaying high LQ and of rats showing solicitation, are quite robust and environmentally independent.