Fig. 5.

The amount of time that wild-type (upper panel) and knockout (lower panel) mice spent in the CPP chambers prior to (D1) and after (D10) repeated conditioning with morphine (10 mg/kg) and following a saline (D14) or morphine (5 mg/kg, D15) challenge. The data represent the mean (±S.E.M.) of 6–7 mice per genotype. *significantly different compared to the amount of time that the mice spent in this chamber on day 1 (p<0.05), ***significantly different compared to the amount of time that mice spent in this chamber on day 1 (p<0.001)