Fig. 2.
The amount of time that wild-type mice (upper panel) and mice lacking the mu receptor (lower panel) spent in the CPP chambers before (D1) and after (D4) single conditioning with M6G (10 mg/kg). The data represent mean (±S.E.M.) of 6 mice per genotype. *significantly different compared to its respective chamber on day 1 (p<0.05)