Social environment enrichment enhances prosocial behavior in male mice via the oxytocin signaling and neuronal plasticity

The rearing environment plays a key role in maintaining physical and mental health in both animals and humans. Numerous studies have proven that physical environment enrichment during adolescence has a positive effect on brain development. However, there is relatively little research on the influence of social environment on adolescents. The companion rotation model (the number of interaction objects is constant, while animals in the same cage are changed) was used to study the influence of social environment enrichment on social behavior. This study discovered that companion rotation can enhance the prosocial behavior of C57BL/6 mice. Meanwhile, the number of active oxytocin neurons in paraventricular nucleus and supraoptic nucleus, the expression levels of oxytocin receptor mRNA in medial prefrontal cortex, and the density of dendritic spines in medial prefrontal cortex, nucleus accumbens, and medial amygdala are all increased. Taken together, these results suggest that companion rotation from adolescence to early adulthood can improve prosocial behavior in male mice by modulating the oxytocin system and changing morphology of dendritic spines.