Fig. 7. Effects of SR141716A and SR144528 antagonists on anandamide (AEA) and palmitoylethanolamide (PEA) effects on nerve growth factor (NGF)–induced increase in absorbance at 620 nm (and thus myeloperoxidase activity). Myeloperoxidase activity is taken as the measure of neutrophil accumulation. (A ) AEA alone at a dose of 25 mg/kg does not have a significant effect on absorbance at 620 nm and is not significantly altered by the addition of either 1 mg/kg SR141716A (SR1) or SR144528 (SR2). (B ) The 25-mg/kg PEA-mediated reduction in absorbance at 620 nm (and thus myeloperoxidase activity) is unaffected by 1 mg/kg SR1 but is reversed by 1 mg/kg SR2. PEA therefore exerts an antineutrophil accumulation action via  an SR144528-sensitive mechanism. (*P < 0.05, one-way ANOVA, post hoc  Dunnett, n = 5 in all groups).