Prior stress experience modulates social preference for stressed conspecifics in male rats.

Adult male rats tend to avoid adult conspecifics in distress. In this study, we asked whether prior stress experience would modulate social preference for a stressed conspecific using a social affective preference (SAP) test. Male Long-Evans adult rats were assigned to the shocked and non-shocked groups. In the shocked group, rats were acutely subjected to foot shocks (1.0 mA, 5 s duration × 2) 24 h before the SAP test. During the SAP test, the experimental rats were placed in an arena where two adult conspecific stimuli, one of which received the foot shocks immediately before the SAP test, were presented at both ends and allowed to explore freely for 5 min. We measured sniffing behavior toward each conspecific as an index of social preference. Non-shocked adult rats avoided, while shocked rats approached, the stressed conspecifics more than the non-stressed ones. These results suggest that prior stress promotes social preference for a stressed conspecific in adult male rats.