Histological and ultrastructural changes induced by selenium in early experimental gastric carcinogenesis

AIM： To investigate the effect and significance of selenium in early experimental gastric carcinogenesis. METHODS： Weaning male Wistar rats were divided randomly into normal control group, experiment control group, low selenium （2 mg/L） group and high selenium （4 mg/L） group. Wistar rat gastric carcinogenesis was induced by N-methyl-N-nitro-N-nitroso guanidine （MNNG） （20 mg/kg） gavage dally for 10 d. Na2SeO3 was given by piped drinking 1 wk prior to MNNG gavage. The rats were killed at the 43^rd wk. The surface characteristics of gastric mucosa were observed with naked eyes. Histopathologic changes of rat gastric mucosa were observed by HE staining and AB-PAS methods. The changes of cellular ultrastructure were observed under transmission electron microscope. Statistical analysis was carried out by SPSS. RESULTS： The incidence rate of gastric mucosa erosion, hemorrhage and intestinal metaplasia was 0, 45.5%, 66.7%, and 92.9%, respectively （92.9% vs 45.5%, P〈0.05） in the normal control group, experiment control group, low selenium group, and high selenium group. Leiomyoma formed in the process of inducement of rat gastric carcinoma. Dietary Na2SeO3 （2 and 4 mg/L） slightly increased the incidence rate of leiomyoma （0.23%, 46.6%, and 46.6%）. gastric mucosa did not change in the course of rat gastric carcinogenesis. Dietary Na2SeO3 by pipe drinking could expand the intracellular secretory canaliculus of parietal cells and increase the number of endocrine cells and lysosomes. CONCLUSION： Dietary Na2SeO3 by pipe drinking aggravates gastric erosion, hemorrhage and promotes intestinal metaplasia of gastric mucosa. The mechanism may be related with the function of parietal cells.