NOS3 and ulcerative colitis: While the disruption of the intestinal barrier and body inflammation may be important triggers of ulcerative colitis, it was found that the expression of endothelial nitric oxide synthase (eNOS), neuronal nitric oxide synthase (nNOS), IκB-α, ZO-1 and Occludin was significantly reduced in the DSS group, while the expression of iNOS, COX-2, and NF-κB was significantly increased when compared with that of the normal group (p < 0.05) (Figure 5).