Adolescent male rats are less sensitive than adults to the anxiogenic and serotonin-releasing effects of fenfluramine

► Fenfluramine was more anxiogenic to adult male rats than adolescents. ► Adolescents had lower fenfluramine-stimulated cortical serotonin release. ► Lower tissue serotonin stores may limit the effects of fenfluramine in adolescents. ► Serotonin-releasing drugs of abuse could also be less anxiogenic to adolescents.