Morphological features of rat gastric mucosa after acute and chronic treatment with amtolmetin guacyl: comparison with non-selective and COX-2 selective NSAIDs

Background/Aims: The compound amtolmetin guacyl (AMG) has been characterized in both animal and human studies as a novel non-selective non-steroidal anti-inflammatory drug (NSAID) endowed with lower ulcerogenicity in comparison with traditional NSAIDs due to a unique mechanism of action, namely the increase in endogenous production of gastric nitric oxide. Methods: Conscious rats were treated either acutely (4 h) or chronically (3 and 14 days) with intragastric AMG (50 and 150 mg/kg), the non-selective NSAID tolmetin (TOL, 30 and 100 mg/kg) or the COX-2-selective NSAID celecoxib (CXIB, 20 and 60 mg/kg). Macroscopically visible and histologic lesions were evaluated. The ultrastructure of mucosal microvasculature was assessed. Results: (1) TOL and CXIB caused quantitatively greater endothelial damage and inflammatory cell infiltration than that induced by AMG; (2) AMG and CXIB, unlike TOL, did not cause epithelial damage after acute or chronic treatment, and (3) gastric lesions induced by TOL underwent adaptation during chronic treatment. Conclusion: Endothelial cell damage in the gastric microvasculature is an early event following both non-selective and COX-2-selective inhibitors. The low gastric mucosal