DISTRIBUTION OF EXTRACELLULAR-MATRIX PROTEINS IN INDOMETHACIN-INDUCED LESIONS IN THE RAT STOMACH

Introduction: We investigated the distribution of extracellular matrix (ECM) proteins in indomethacin-induced lesions of the rat stomach. Method: Twenty rats received indomethacin orally at a dose of 8 mg/kg/body weight. The animals were killed at 3, 6, 12, 24, and 48 h after administration of the drug. The stomachs were removed and frozen in liquid nitrogen. Cryostat serial sections of the lesions were immunostained with antibodies to collagen III, IV, and VI, laminin, and fibronectin. Results: Fibronectin was the dominant extracellular protein of the provisional ECM in deep gastric lesions and gastric ulcers. Collagen III was strongly positive in stromal cells under the necrotic material in gastric erosions. Basal membrane proteins (collagen IV and laminin) were found to originate from the muscularis mucosae at the ulcer edge. Conclusion: There is a typical distribution of ECM proteins in erosions and ulcers of the rat stomach. Fibronectin was most prominent in the provisional matrix of gastric erosions and ulcers.