Effects of extracts of Cheezheng pain relieving plaster on nitric oxide and iNOS expression in macrophages induced by lipopolysaccharides

This study is to explore the effects of extracts of Cheezheng pain relieving plaster (ECPRP) on  nitric oxide (NO) production and expression of inducible nitric oxide synthase (iNOS) in macrophages induced by LPS and the mechanism involved.  Nitric oxide level was measured with Griess reagent assay.  Inducible nitric oxide synthase (iNOS) protein and NF-κBp65 fragment were detected with Western blotting.  ECPRP (62.5 and 125 mg·L⁻¹) significantly inhibited the increase of nitric oxide level.  Furthermore, ECPRP (62.5 and 125 mg·L⁻¹) notably reduced the expression of iNOS mRNA and protein.  ECPRP (62.5 and 125 mg·L⁻¹)    elevated the content of I-κB protein in cytoplasm, while decreased the content of NF-κBp65 protein in nucleus.  These results suggest that ECPRP reduce nitric oxide level via down-regulation of NF-κB-iNOS-nitric oxide pathway, resulting in prevention of inflammation.