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AIM:To explore the roles of nitric oxide synthase (NOS),heine oxygenase (HO) and cyclooxygenase (COX) in gastriculceration and to investigate the relationships of theexpression and activities of these enzymes at different stagesof gastric ulceration.METHODS:Gastric ulcers (kissing ulcers) were induced byluminal application of acetic acid.Gastric tissue samples wereobtained from the ulcer base,ulcer margin,and non-ulcerated area around the ulcer margin at different timeintervals after ulcer induction.The mRNA expression andprotein levels of inducible and constitutive isoforms of NOS,HO and COX were analyzed with RT-PCR and Westernblotting methods.The activities of the total NOS,inducibleNOS (iNOS),HO,and COX were also determined.RESULTS:Differential expression of inducible iNOS,HO-1and COX-2 and enzyme activities of NOS,HO and COX werefound in the gastric ulcer base.High iNOS expression andactivity were observed on day 1 to day 3 in severely inflamedulcer tissues.Maximum expressions of HO-1 and COX-2 andenzyme activities of HO and COX lagged behind that of iNOS,and remained at high levels during the healing phase.CONCLUSION: The expression and activities of inducible NOS, HO-1 and COX-2 are found to be correlated to different stages of gastric ulceration. Inducible NOS may contribute to ulcer formation while HO-1 and COX-2 may promote ulcer healing.
AIM: To explore the roles of nitric oxide synthase (NOS), heine oxygenase (HO) and cyclooxygenase (COX) in gastric ulceration and to investigate the relationships of theexpression and activities of these enzymes at different stages of gastric ulceration. METHODS: Gastric ulcers (kissing ulcers) were induced byluminal application of acetic acid. Gastric tissue samples wereobtained from the ulcer base, ulcer margin, and non-ulcerated area around the ulcer margin at different timeintervals after ulcer induction. mRNA mRNA and protein levels of inducible and constitutive isoforms of NOS , HO and COX were analyzed with RT-PCR and Westernblotting methods. The activities of the total NOS, inducibleNOS (iNOS), HO, and COX were also determined.RESULTS: Differential expression of inducible iNOS, HO- 1 and COX-2 and enzyme activities of NOS, HO and COX were found in the gastric ulcer base. High iNOS expression and activity were observed on day 1 to day 3 in severely inflamedulcer tissues. Maximal expressions of HO-1 and COX-2 andenzyme activities of HO and COX lagged behind that of iNOS, and remained at high levels during the healing phase. CONCLUSION: The expression and activities of inducible NOS, HO-1 and COX-2 are found to be correlated to different stages of gastric ulceration. Inducible NOS may contribute to ulcer formation while HO-1 and COX-2 may promote ulcer healing.