The neurosteroids, progesterone and 3α,5α-THP, enhance sexual motivation, receptivity, and proceptivity in female rats

Data are reviewed concerning the display of solicitation behaviors in the estrous female rat, including precopulatory hopping, darting, and ear wiggling, and the pacing of copulatory contacts through patterns of approach toward and withdrawal from a sexually active male rat. Observations made under semi-natural and laboratory conditions suggest that solicitation behaviors determine the types and amounts of coital stimuli received by the female. Solicitation behaviors as regulators of cervical-vaginal stimulation play a primary role in ensuring the activation of the neuroendocrine reflex are responsible for prolongation of ovarian corpora luteal function. Despite solicitation behaviors' importance for reproductive success, few studies have examined the neural and endocrine mechanisms involved in the display of those aspects of solicitation behavior which influence the patterning of coital stimuli received by the female. The present review suggests that two elements of pacing behavior, the ability to discriminate between varying intensities of coital stimulation and the active patterning of approach/withdrawal which controls receipt of that stimulation, are constituent parts of solicitation behaviors readily amenable to experimental investigation.

The possibility that female-paced coital behavior induces a reward state of sufficient intensity and duration to induce conditioning was evaluated by the conditioned-place-preference paradigm. Ovariectomized female rats, treated with estradiol benzoate and progesterone, regulated (paced) their coital interactions with a stud male through a 2-compartment chamber in which only the female could freely move from one compartment to the other. The females that paced their coital interactions showed a clear place preference. In contrast, no change in preference was observed in the females that could not pace their coital contacts. The change in preference in the females that paced their coital interactions was similar to that produced by an injection of morphine (1 mg/kg). These results suggest that coital interactions in females can induce a reward state when the females can control the pace of the sexual interaction.