Morphological and pathologic changes of experimental chronic atrophic gastritis (CAG) and the regulating mechanism of protein expression in rats

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Abstract

Objective: To study the pathologic change and molecular regulation in cell proliferation and apoptosis of gastric mucosa in rats with chronic atrophic gastritis (CAG), and evaluate the possible mechanisms. Methods: Rats were administered with 60% alcohol or 2% salicylate sodium, 20 mmol/L deoxycholate sodium and 0.1% ammonia water to establish chronic atrophic gastritis (CAG) models. The gastric specimens were prepared for microscopic view with hematoxylin and eosin (H-E) and alcian blue (A-B) stain. The number of infiltrated inflammatory cells, the thickness of the mucosa gland layer (μm) and the number of gastric glands were calculated. The damage of barrier in mucosa with erosion or ulceration, and the thickness of mucin were examined by scanned electron microscope (SEM). The levels of PGE2, EGF (epiderminal growth factor) and gastrin in the serum were measured with radioimmunoassay or ELISA method. The immunohistochemistry method was used to observe the number of G cells, the expression of protein of EGFR (EGF receptor), C-erbB-2, p53, p16 and bel-2 in gastric tissue. Results: Under SEM observation, the gastric mucosa was diffused erosion or ulceration and the thickness of mucin was decreased. Compared with normal rats, the grade of inflammatory cell infiltration in CAG rats was elevated, whereas the thickness and number of gastric gland were significantly lower (P<0.05). Compared with normal level of (0.61±0.28) μg/L, EGF in CAG (2.24±0.83) μg/L was significantly higher (P<0.05). The levels of PGE2 and gastrin in serum were significantly lower in CAG rats than that in normal rats (P<0.05). Immunohistochemistry detection showed that the number of G cell in antrum was lower in CAG group (P<0.05). Immuno-stain showed EGFR protein expression in the basal and bilateral membrane, and the cytoplasma in atrophic gastric gland, while negative expression was observed in normal gastric epithelial cells. Positive staining of p53 and p16 protein was localized in the nucleus of epithelial cells. The former was higher positively expressed in atrophic gland, while the later was higher positively stained in normal gastric tissue. bel-2 protein was positively stained in the cytoplasma in atrophic gastric gland, while very weakly stained in normal gastric tissue. Conclusion: The pathological findings in gastric gland accorded with the Houston diagnostic criteria of antrum-predominant CAG. CAG in rats was related with the damage of barrier in gastric mucosa and the misbalance of cell proliferation and apoptosis. There was high protein expression of oncogene, while inhibitor of suppressor gene in CAG rats indicated high trend of carcinogenesis.

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