Enhanced acquisition of cocaine self-administration in adult rats with neonatal isolation stress experience.

That stress enhances the behavioral effects of cocaine is well-documented in adult rats, but whether early life stress endures into adulthood to affect responsivity to cocaine is less clear. We now report that neonatal isolation stress (1 h per day isolation on postnatal days 2-9) enhances acquisition of cocaine self-administration in adult rats. This effect was specific to cocaine and not due to learning or performance differences. Neither acquisition of operant responding for food nor locomotor activity differed between groups. These results have important implications for the role of early childhood stress in vulnerability to cocaine addiction.