Abstract

Background

PR-dependent changes in behavior

Effects of mating stimulation on PRs

Discussion and Conclusions

References

Discussion
Board

Progestin receptors (PRs) are involved in the regulation of physiology and behavior. While PRs are regulated in the brain by estradiol and progesterone, their concentrations and activity are also regulated by afferent input, including input from mating stimulation. Mating stimuli increase the expression of sexual receptivity in female rats apparently, like progesterone, via activation of PRs. However, we have also suggested that, like progesterone, mating stimulation may cause down-regulation of PRs. In an experiment to test this idea, estradiol plus progesterone-treated rats were either mated or not. While progesterone itself down-regulates PRs, mating potentiated the down-regulation of PRs in some brain areas, not others. As maintenance of high levels of PRs is essential to maintenance of sexual receptivity, this down-regulation may be causally related to the process by which mating causes heat abbreviation. In an experiment to test the idea that afferent input from mating stimulation activates PRs by a manner similar to progesterone, we observed that progesterone causes rapid changes in PR-immunostaining, while mating stimulation does not. This suggests that mating stimulation activates PRs by a mechanism independent of that of progesterone. The possibility that effects of mating stimulation, including genital stimuli, on the brain may be mediated partly by regulation of PRs will be discussed.

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Presentation Number SAblaustein0486
Keywords: estradiol, progesterone, receptors, lordosis, genital