Induction of Tumor Necrosis Factor-α and Apoptosis in Gastric Mucosal Injury by Indomethacin: Effect of Omeprazole and Ebrotidine

Abstract

Background: The gastric injury associated with nonsteroidal anti-inflammatory drug (NSAID) therapy has been linked to the detrimental effects of the agents on the processes of prostaglandin generation, leukocyte adherence, superoxides production, and mucosal cell proliferation. In the present study we investigated the expression of tumor necrosis factor-α (TNF-α) and epithelial cell apoptosis during indomethacin-induced gastric mucosal injury and evaluated the effect of two antiulcer agents on this process. Methods: The experiments were carried out with groups of rats subjected to intragastric pretreatment with 40 mg/kg omeprazole, 100 mg/kg ebrotidine, or vehicle, followed 30 min later by an intragastric dose of indomethacin at 60 mg/kg. After 2 h the animals were killed, and the gastric mucosal tissue used for macroscopic damage assessment, quantitation of TNF-α expression, and the assay of epithelial cell apoptosis. Results: In the absence of antiulcer drugs, indomethacin caused extensive multiple hemorrhagic lesions accompanied by a 47% increase in mucosal expression of TNF-α and a dramatic (300-fold) enhancement in gastric epithelial cell apoptosis. Pretreatment with a proton pump inhibitor, omeprazole, produced only marginal (6–8%) reduction in the extent of mucosal damage caused by indomethacin, whereas the mucosal expression of TNF-α decreased by 15% and the apoptotic DNA fragmentation by 10–13%. In contrast, the H₂-receptor antagonist ebrotidine, also known for its gastroprotective effects, not only successfully prevented (98.3%) the enhancement in mucosal TNF-α expression caused by indomethacin but also caused a 54% reduction in the epithelial cell apoptosis. These effects of ebrotidine were, furthermore, reflected in a 90.2% prevention in the gastric mucosal damage. Conclusions: Our findings provide new insights into the mechanism of gastric injury caused by NSAIDs and show that ebrotidine protection against indomethacin-induced mucosal damage occurs through the inhibition of epithelial celt apoptosis triggered by the enhancement in the mucosal TNF-α expression. Our data also show that omeprazole does not possess antiapoptotic properties.

Key Words:

• Antiulcer drugs
• apoptosis
• indomethacin
• mucosal injury
• tumor necrosis factor-a