Impact of social isolation and resident intruder stress on aggressive behavior in the male rat

Stress studies frequently utilize physical stressors to establish animal models of stress. In the majority of cases, these models are not consistent with human circumstances. The present study simulated a social isolation plus resident intruder stress model in the rat. The rats were subjected to daily social isolation and resident intruder stress for 2 weeks. Behaviors were then tested. Rats subjected to social stress exhibited different aggressive behavior styles; some rats had greater scores on composite aggression behaviors, as well as locomotor and exploratory activity, but lower scores on latency than others. The high-aggressive group exhibited predominantly anger-out, while the low-aggressive group exhibited anger-in. Results suggest that social isolation plus resident intruder may serve as an appropriate model for anger-in and anger-out emotion modeling in the rat.