Systemic effect of CB1 receptor agonists on 5-HT efflux in the DRN and NAcc. Data are expressed as percent of average baseline values (% mean ± s.e.m.). Mean baseline level of extracellular 5-HT was  pg/sample in the DRN () and  pg/sample in the NAcc (). The arrow indicates the time of the injection. (a) Systemic injection of WIN 55,212-2 (2.5 and 5 mg/kg, i.p.) had no effect on extracellular 5-HT in the DRN. (b) Systemic injection of WIN 55,212-2 (2.5 and 5 mg/kg, i.p.) produced dose- and time-dependent effects on extracellular 5-HT in the NAcc. (c) Systemic injection of CP55940 (0.25 and 0.5 mg/kg, i.p.) produced dose- and time-dependent effects on extracellular 5-HT in the NAcc. * and *** versus vehicle examined by the repeated measures ANOVA followed by the post hoc Scheffe test.