Enriched environment during adulthood temporarily ameliorates aggression induced by post-weaning social isolation in...

Childhood maltreatment increases the risk of psychiatric disorders with impulsive aggression. Post-weaning social isolation (PWSI) also increases impulsive aggression in adult rats, suggesting value as a model for elucidating the underlying neurodevelopmental mechanisms and for screening potential therapies. An enriched environment (EE) has been shown to increase social interaction, serotonergic transmission, and brain-derived neurotrophic factor level, and to reactivate developmental plasticity after the critical period. In this study, we show that the PWSI until adulthood increases shock-induced impulsive aggression in male Sprague-Dawley rats, and that housing in a long-term EE for 53 days (but not a short-term EE for 11 days) attenuates this increased aggression. However, this increased aggression re-emerged soon after return to standard housing. These results suggest that long-term EE is effective but not curative for PWSI-induced impulsive aggression.