Figure 1:

Effects of MNTX on acute morphine-induced antinociception in a warm-water tail-withdrawal assay. Mice were administered a MNTX dose (0.5, 1, 2.5, 5, 10, 25 mg/kg, s.c.) or vehicle (VEH) followed 20 min later by injection of 10 mg/kg morphine (s.c.), then tested 30 min after morphine administration. Data represent the mean ± SEM percent maximum possible effect (%MPE) of 5-6 mice per treatment condition. Significant differences in %MPE relative to vehicle-pretreated mice are denoted by filled symbols (p<0.05).