Implications of the gut microbiota in vulnerability to the social avoidance effects of chronic social defeat in male mice

Appreciable evidence suggests that perturbations within the gut microbiome and the immune system may play a key role in the pathogenesis of depression stemming from earlier stressful experiences. In the present investigation we examined whether microbial changes in cecum contents were associated with social avoidance behaviors, a feature of depression, and pro-inflammatory variations among socially stressed mice. Male C57BL/6 mice experienced social defeat or a control condition once a day for 10 consecutive days. Social avoidance behaviors were examined three weeks after the last defeat or control episode and blood, brain, and cecum contents were collected 24 h afterward for the determination of corticosterone, pro-inflammatory cytokines, and microbial populations. Mic