The selective pair bond between adult male and female mate is one of the strongest driving forces of social behaviors in monogamous animals, including human beings. Previous reports suggest that posttraumatic stress disorder (PTSD) is associated with partner separation or divorce probably due to the impairment of social cognitive processes, however, the molecular and cellular mechanisms underlying this phenomenon are unknown. Prairie voles (Microtus ochrogaster) are monogamous rodents that exhibit a partner preference after the formation of a pair bond and provide a useful model to understand the neuronal mechanisms of social bonding. A single prolonged stress (SPS) paradigm, which is composed of restraint, forced swimming, and ether anesthesia, is one of the rodent models proposed for PTSD. Here we analyzed the effect of the SPS paradigm on the pair bonding of prairie voles.
Adult male voles were given the SPS paradigm at the experimental day 0. An open field test at the day 7 did not show significant difference between SPS voles and control voles in anxiety. The male vole was cohabitated with a female vole from day 8 to day 14. On day 14, significant partner preference was detected in control voles by a partner preference test, whereas SPS voles showed no preference to his partner. Neuropeptides such as vasopressin and oxytocin play crucial roles in pair bonding. Hence, we are proceeding to analyze the immunoreactivities of arginine-vasopressin and oxytocin in the paraventricular nucleus and supraoptic nucleus after the SPS paradigm, and will report the results at the meeting.