Rats are often described as having a promiscuous mating strategy, yet through simple Pavlonian conditioning paradigms, where neutral odors are paired with sexual reward states, rats can develop conditioned sexual partner preferences, where they prefer to solicit, copulate, and mate with scented familiar partners over unscented unfamiliar ones. We have previously shown that ovariectomized female rats, hormonally primed, do not need odors if they are paired with the same male for their first 10 paced sexual experiences: They are able to recognize their partner male based on primary cues alone and will display mate guarding behavior in the presence of a competitor female. Rats who mate guard also show a significant induction of fos within oxytocin and vasopressin neurons in the supraoptic and paraventricular nuclei.  In this study we peripherally administered oxytocin and vasopressin to female rats, hypothesizing that it would facilitate the onset of mate guarding after a single copulation trial alone.  Consistent with our hypothesis, female rats treated with 5ug/kg of oxytocin or vasopressin displayed mate-guarding behaviors after 1 trial alone.  Mate-guarding behaviors were expressed differently within each treatment group.  Females that received oxytocin treatment were intromitted more frequently than competitor females, which was due to a significant increase in presenting behavior.  Females that were treated with vasopressin positioned their body in between the male and competitor female, where as the competitor females showed significantly less of this behavior.  These results tell us that oxytocin and vasopressin are key players in conditioned mate guarding behavior in female rats.  Also, these data suggest that these two neuropeptides play distinctly different roles in mediating this behavior.  

Funded by the Canadian Institutes for Health Research (CIHR)