Expression and activity patterns of iNOS and eNOS in acetic acid induced gastric ulcers in rats

Abstract

AIM - To study the expression and activity patterns of constitutive and inducible forms of nitric oxide synthase (eNOS and iNOS) in gastric ulcer and their roles in gastric ulcer healing. METHODS - Rat models of gastric ulcer were induced by intraluminal application of acetic acid solution. Stomach samples from the base, margin and normal tissues around the gastric ulcers were collected at different times after ulcer induction. Expressions of eNOS and iNOS mRNA and their protein levels were detected by RT-PCR and Western Blot methods. NOS activities were measured as the ability of tissue homogenates to convert L-[3H]-arginine to L-[3H] citrulline. RESULTS - A high level of expression and enzyme activity of iNOS were detected in the ulcer base in day 1 to day 3 after ulcer induction when the tissue inflammation was most severe. The protein level and activity of iNOS in normal gastric tissue or the ulcerated tissue in the healing phase were undetectable or at a low level. The expression and activity of eNOS was relatively stable during the whole experimental period. CONCLUSION - There are restricted induction and regulation of iNOS expression and activity in the healing process of gastric ulcer. Nitric oxide mainly derived from the activity of iNOS, plays an important role in the pathological process of inflammation and gastric ulcer healing.