Reproductive behavior and physiology of nulliparous female rats after sexual experience

There is an extensive literature suggesting that following sexual experience male mammals show chronic elevation of sexual behavior and growth of reproductive organs and glands. An hypothesis was examined in the present research that a similar pattern of changes would be revealed in females after sexual contact without the confounding influences of pregnancy and parturition. Initiatially virgin gonadally intact (Experiment I) and ovariectomized/hormone-injected (Experiment 1) female rats received precisely controlled interactions either with intact males to gain copulatory experience or with castrated males to gain social experience without copulating. Subsequently, females from each condition were observed during behavioral estrus with unfamiliar males, and all females were sacrificed the following day. Behavioral results were similar for the two experiments and failed to support the hypothesis. It was the virgin, rather than the experienced female, which solicited a male more frequently and aggressively rejected his approaches less often. Moreover, the male exhibited more and faster intromissions and ejaculations with inexperienced than with experienced females. Physiological analyses of ovaries, uteri, utero-tubal junctions, vaginae, clitorides and preputials suggested subtle quantitative and qualitative changes after sexual contact, but only in intact females and without any clear pattern of changes. Conclusions were that the striking modifications in behavior are centrally mediated in the female and are unlike those observed in the sexually experienced male. Nevertheless, the consequence for fecundity may be the same for both genders.