Social approach to pain in laboratory mice

Abstract It has been recently demonstrated that pain behavior in the mouse can be modulated by the presence of a conspecific, but what remains unclear is whether such pain behavior can serve the function of soliciting social approach. Using a novel social approach paradigm, we tested mice in various dyadic or triadic conditions, including “jailed” mice—some in pain via intraperitoneal injection of 0.9% acetic acid—and test mice free to approach or avoid the jailed mice. We observed a sex-specific effect whereby female, but not male, test mice approached a familiar same-sex conspecific in pain more frequently than an unaffected familiar or unfamiliar, but affected, conspecific. Despite a substantial literature emphasizing oxytocin's role in affiliative and pair-bonding behavior, this effect was also observed in female mice lacking the oxytocin receptor, suggesting that pain-related social approach may not be mediated by oxytocin. Furthermore, we found that the frequency of contact by the test mouse was neg...