Asymmetry in progestin receptor levels and sexual behavior in female rats

There are reports of hemispheric asymmetry in the control of sexual receptivity by the hypothalamus in the female rat. In the present study, we investigated whether there is an asymmetry in the distribution of progestin receptors in the hypothalamus, and whether the asymmetry in distribution is associated with receptivity as indicated by lordosis quotients. Degree of hemispheric asymmetry in hypothalamic progestin receptor (PR) levels was associated with higher lordosis quotients regardless of the direction of asymmetry. In a second study, as in the first study, degree (and not direction) of asymmetry of PR levels in the hypothalamus was associated with receptive behavior. In addition, the results suggest a possible link between left-biased asymmetry in frontal cortical PR levels and proceptive behavior. These studies are the first evidence of relationships between hemispheric asymmetry in progestin receptor levels and behavior.