Effect of i.pl. pre-treatment with NMP-4 (0.03 μg/i.pl.) on the antinociceptive effect of NMP-7 (1 μg/i.pl.) on first phase of formalin-induced pain in mice (A). Each bar represents the mean response from 5-7 animals and the error bars indicate the S.E.M. Vehicle values are from animals injected with PBS solution with 5% of DMSO. The asterisks denote the significance level: *P < 0.05 (two-way ANOVA followed by the Newman-Keuls' test). B, C. Effect of systemically delivered NMP-7 (1 mg/kg, i.p.) on both phases of formalin induced pain. Each bar represents the mean response from 5-6 animals and the error bars indicate the S.E.M. Control values (indicated by "C") are from animals injected with 5% of DMSO and the asterisks denote the significance relative to the control group. *P < 0.05, **P < 0.01, ***P < 0.001. (one-way ANOVA followed by Dunnett' test).