Oxytocin receptor control social information about fear expression of others in mice

The social functions of oxytocin are diverse, and the specific aspects of information processing involved in emotional contagion remain unclear. We compared some fear-related behaviors among oxytocin receptor knockout mice and oxytocin-receptor-reduced mice with that of wild-type mice. In the observational fear assay, which reflects fear emotional contagion, mice that observed other individuals receiving electric shocks exhibited vicarious freezing. Mice with reduced or knockout oxytocin receptor expression showed reduced vicarious freezing. In the emotional discrimination assay, which reflects the ability to perceive others' emotional cues, we compared approach and scent-sniffing behaviors toward fear and emotionally neutral individuals. While wild-type mice were able to detect the fear emotion of others, mice with reduced or knocked-out oxytocin receptors showed reduced discrimination ability. In the fear behavior assays, which do not present social cues, we did not find these differences in oxytocin receptor expression in the brain. These findings indicate that oxytocin plays a role in emotional contagion by perceiving the emotions of others.