Fig. 5.
Enhanced CPP to cocaine in mGluR2–/– KO mice. Shown are results of before and after conditioning with indicated doses of i.p. cocaine injection for 3 days, and the time difference was calculated by subtracting time mice spent in the saline-paired side from the time they spent in the cocaine-paired side (for each group, n > 8). mGluR2–/– KO mice spend significantly more time as compared with WT mice in the cocaine-paired side after conditioning with 10 and 20 mg/kg cocaine [genotype effect, F(1, 44) = 9.465, P = 0.0036] (*, P = 0.014; **, P = 0.006).