PTGS2 and colitis: Western blotting analysis of intestinal extracts showed that colitis rats (TNBS) had significantly increased COX-2 and iNOS protein expression compared to controls (P <0.01), and there was a significant decrease in the relative density of COX-2 and iNOS protein in colitis rats treated with HBO (TNBS/HBO) (P < 0.01) (Figure 4A and C).