The effect of nitric oxide synthases inhibitors on inflammatory bowel disease in a rat model

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.

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.

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.

NOS inhibitors may be promising agents in preventing the onset, or mediating the symptoms, of inflammatory bowel disease.