The effects of emotional stress are not identical to those of physical stress in mouse model of social defeat stress.

In this study, we investigated the effects of emotional stress and physical stress using the social defeat stress (SDS) model in mice. Male C57BL/6 J mice were attacked by male non-retired ICR mice for 10 min daily for 10 days (physical stress; PS), while the other cohort of mice witnessed the defeat (emotional stress; ES). As a result, both PS and ES mice exhibited decreased social behavior in the social interaction test (SIT) and increased immobility in the forced swim test (FST). Interestingly, only ES mice exhibited decreased sucrose preference, and only PS mice exhibited decreased time spent in the open arms in the elevated plus-maze test. ES mice did not exhibit increased levels of corticosterone and epinephrine after a single stress exposure, but showed a decrease in plasma CXCL16 levels 1 month after stress exposure. Finally, a RhoA/Rho kinase inhibitor, fasudil, which has been reported to attenuate the effects of chronic stress, suppressed the increased immobility in the FST in PS mice, but not in ES mice. These results demonstrate that, although ES and PS mice shared many characteristics, the effects of emotional stress are not identical to those of physical stress in mice.