Fig. 4. Antihyperalgesic action of 25 mg/kg palmitoylethanolamide (PEA) and the effects of antagonists. Control and 25 mg/kg PEA alone data are taken from figure 2for comparison. (A ) Mean (± SEM) differences in withdrawal latencies against time. Coadministration of 1 mg/kg selective CB¹receptor antagonist SR141716A (SR1) with 25 mg/kg PEA results in difference (from baseline) of withdrawal latencies significantly different from those of vehicle controls. Therefore, SR1 does not affect the antihyperalgesic action of 25 mg/kg PEA. (B ) Mean (± SEM) differences in withdrawal latencies against time. The action of PEA is prevented by coadministration of 1 mg/kg selective CB²receptor antagonist SR144528 (SR2), because this causes differences in withdrawal latencies not significantly different from those of vehicle controls. (*P < 0.05, two-way ANOVA, post hoc  Dunnett, n = 5 in all groups).