Gastric mucosal levels of prostaglandins and leukotrienes in patients with gastric ulcer after treatment with rabeprazole in comparison to treatment with ranitidine

AIM : Prostaglandins (PGs) and leukotrienes (LTs) are major factors involved in the defense of the gastric mucosa against ulcer formation. However, little is still known about the gastromucosa-protecting action of proton pump inhibitors (PPIs) and histamine H2 receptor antagonists (H2 blockers) in patients with gastric ulcer. We therefore examined the effectiveness of a PPI in protecting the gastric mucosa.
METHODS : We compared the PGE2 and LTB4 levels and the expression levels of cyclooxygenase (COX)-1 and COX-2 mRNA in the gastric mucosa in gastric ulcer patients between the group treated for 8 weeks with a PPI, rabeprazole (PPI group ; n=5), and the group treated for 8 weeks with an H2 blocker, ranitidine (H2 blocker group ; n=6), as well as in nonulcer subjects (control group ; n=5).
RESULTS : The mucosal levels of PGE2 and COX-2 mRNA expression were significantly lower in the ulcer patients than those in the nonulcer patients, whereas the LTB4 level was significantly higher in the ulcer patients than that in the nonulcer patients, and it was also significantly lower in the ulcerated mucosa than that in the nonulcerated mucosa. The PPI group had a significantly increased PGE2 and decreased LTB4 levels in comparison to the H2 blocker group during the ulcer-healing stage. The COX-1 mRNA expression showed no difference among the PPI and H2 blocker groups or between before and after the treatment. However, the COX-2 mRNA expression increased in the PPI group more than that in the H2 blocker group during the ulcer-healing stage.
CONCLUSION : These findings demonstrated the significant gastric-mucosa-protecting effect of PPI by increasing the PGE2 production and reducing the LTB4 production.