The Effect of Nitric Oxide Synthases Inhibitors on Inflammatory Bowel Disease in a Rat Model

Abstract

Background/Aims: Overexpression of nitric oxide (NO) has been implicated in the pathogenesis of experimental and clinical inflammatory bowel disease (IBD). NO is produced by two types of enzymes: constitutively expressed and inducible NO synthases (NOS). This study assessed N^w-nitro-L-arginine methyl ester (L-NAME) and aminoguanidine (AMG), the most studied inhibitors of nitric oxide synthases, with regard to their effectiveness as modulators of inflammation in trinitrobenzene sulfonic acid (TNBS)-induced colitis in the rat. Materials and Methods: Colitis was induced in Wistar rats. The colitis was treated everyday for 10 days with L-NAME and AMG. To assess the severity of the colitis, clinical (body weight), hematological (hematocrit and erythrocytes sedimentation rate-ESR) and morphological (gross and microscopic) criteria were used. Results: The administration of both nitric oxide synthases inhibitors L-NAME and AMG proved to be beneficial in all the examined parameters compared with the control group. A statistically significant difference between the L-NAME and the AMG groups was observed only in macroscopic and histological grading. Conclusion: NOS inhibitors may be promising agents in preventing the onset, or mediating the symptoms, of inflammatory bowel disease.