Preoptic lesions, sexual behavior, and spontaneous ejaculation in the rat

Abstract.— A possible relation between sexual behavior and spontaneous ejaculation was studied in the male rat. Electrolytic lesions in the preoptic area completely abolished sexual behavior without affecting the frequency of spontaneous ejaculation. It is therefore suggested that this latter process is controlled independently of sexual behavior and sexual excitability.     

Effects of female odors on the sexual behavior of male hamsters

A series of experiments was undertaken to investigate the effects of removal of several scent glands and scent-producing organs of female hamsters on the copulatory performance of male hamsters. In the first experiment it was shown that males engage in less copulatory activity toward females lacking vaginal secretions than toward females with these odors. Eliminating visual cues by observing pairs under infrared illumination did not change the performance of males toward these two kinds of females. The results of Experiment 2 indicated the importance of flank, ear, and Harderian glands as well as vaginal secretions--males showed the highest levels of copulatory behavior toward females with a full complement of odors and the lowest levels toward those lacking three of four sources of scent. Similar results were obtained in the third experiment in which anesthetized females were used as stimulus animals to increase the importance of chemical cues and to reduce variability due to the behavior of females. The sexual behavior of males was greatest toward females with all sources of scent present, lower toward those lacking vaginal secretions, and still lower toward those lacking vaginal secretions and other sources of odors. In the fourth experiment we asked whether any one of the nonvaginal scent glands was particularly important in stimulating male sexual behavior, but we found no differences in male performance toward females that lacked vaginal secretions or that in addition lacked one of the other scent glands. In the fifth experiment males displayed higher levels of sexual behavior toward vaginectomized females than toward vaginectomized females that had been deodorized by a cleaning procedure, again indicating the importance of nonvaginal odors in stimulating copulatory performance. Thus these experiments demonstrate the importance of vaginal secretions in the sexual arousal of male hamsters, a role for nonvaginal odors in sexual arousal of males, and the lack of necessity of these odors for male copulatory behavior. These results have implications for theories of olfactory communication in mammals and for interpretations of experiments in which lesions of the olfactory system lead to deficits in male copulatory performance.     

Isolation-induced facilitation of male sexual behavior in mice

Sexual performance of male mice housed individually or in groups of 3 or 12 was compared. Experiment 1 examined naive males presented at weekly intervals with ovariectomized, estrogen-primed, progesterone-treated females. Performance in isolates was consistently superior and reached an asymptote that was twice that of grouped animals. Reversal of housing conditions reversed performance. Experiment 2 varied intervals of isolation among subjects, finding facilitation at several intervals. Experiment 3 compared animals under different population densities. Density did not alter the effects of isolation and grouping. In all experiments, additional tests with target males indicated that aggressive and sexual performance were moderately correlated and responded similarly to parametric manipulations. These results parallel and extend studies of isolation-induced aggression.