Figure 3.

Effect of age and nicotine pretreatment on quinpirole-induced behavioral responses. Quinpirole (0.4 and 1.6 mg/kg, intraperitoneal) significantly increased locomotor activity (a) and stereotypy (b) in adolescent rats (^**p<0.0001). Quinpirole (0.1 mg/kg, intraperitoneal) had no effect on locomotion or stereotypy compared with vehicle controls. Nicotine-pretreated adolescents showed increased locomotion following quinpirole (0.4 mg/kg) injection (a) compared with saline-pretreated controls (⁺⁺p<0.0001 vs saline pretreated). n=6–13 per group