Cytotoxicity of NaCl, a stomach tumor promoter, and prevention by rice extract in stomach mucosa of F344 rats.

Cytotoxicity of NaCl and its prevention by rice extract were studied in the pyloric mucosa of male F344 rat stomach after oral administration of rice extract and 2.6 M NaCl. Effect were observed histologically by hematoxylin and eosin staining and the bromodeoxyuridine method. Replicative DNA synthesis (RDS) was assayed by liquid scintillation counter with [3H]thymidine. NaCl (2.6 M) induced destruction of the surface mucous cells within 1 min. RDS and S-phase cells increased significantly (p < 0.01) and to a maximum at 17 h, and returned to control levels 48 h after exposure. Administration of aqueous rice extract 3 h before NaCl exposure reduced the morphological damage to the mucosa and prevented the increase in RDS dose dependently by up to 65% (p < 0.01). These results showed that NaCl induced rapid mucosal damage and cell proliferation in rat stomach mucosa and that rice extract prevented the damage and reduced the increase in RDS.