Figure 5.

Mean (+SEM) physiological responses to stress at baseline (plain bars) and following 15 minutes of immobilization stress (hashed bars), as measured by serum corticosterone levels (ng/dL) during the week following the CPP reinstatement test. Both groups of rats exhibited an increase in serum corticosterone in response to stress (*p<0.001 for both). Following CPP, while there were no differences in baseline corticosterone levels between sedentary and exercise rats, exercise rats exhibited significantly greater stress-induced serum concentration of corticosterone compared to sedentary controls (^p<0.01). *Significant difference from baseline, #significant difference between treatment groups within the same session.