Expression and activity of cyclooxygenases-1 and -2 in acetic acid induced gastric ulcer in rats

Abstract

OBJECTIVE: To investigate the dynamic changes of the expression and activity of the two forms of cyclooxygenase (COX-1 and COX-2) in animal model of gastric ulcer and their role in the pathological process of gastric ulcer. METHODS: Acetic acid was perfused into the gastric cavitties of 130 rats to produce animal model of /gastric ulcer. Specimens of the base part and margin of gastric ulcer and normal gastric tissue around were collected 1 hour to 15 days after the induction. RT-PCR and Western blotting were used to detect the expression of COX-1 mRNA and COX-2 mRNA and their protein levels. The total COX activity was determined by determining the ability of tissue homogenate to metabolize arachidonic acid to produce PGE2. RESULTS: After the ulcer induction, the expression of COX-2 mRNA and its protein were highly induced at the ulcer base in inflammation stage (6 hours to 3 days) and kept at a high level during the healing stage (3 days to 15 days), while the expression of COX-1 remained relatively stable. The homogenates from tissues of basal and marginal parts of ulcer showed very high level of COX activity during the ulcer healing stage. The COX activity of normal tissue around ulcer showed little change before and after ulcer induction. CONCLUSION: COX, especially COX-2, which maintains a high level of expression and activity during the ulcer healing stage, may play an important role in ulcer healing and tissue remodeling.