REDUCTION IN NACL-ENHANCED GASTRIC CARCINOGENESIS IN RATS FED A HIGH-PROTEIN DIET

The effect of a purified, high protein diet on enhanced gastric carcin ogenesis induced by oral administration of NaCl was investigated in Wi star rats. Rats were fed on a purified diet with an equalized caloric content, containing 8% NaCl and 25% casein (normal protein diet), or 5 0% casein (high protein diet) after oral treatment with N-methyl-N'-ni tro-N-nitrosoguanidine for 25 weeks. In week 52, oral administration o f NaCl had significantly increased the incidence and size of gastric c ancer in rats fed a normal protein diet. However, NaCl had no signific ant effect on gastric carcinogenesis in rats fed a high protein diet. Oral administration of NaCl also caused a significant increase in tiss ue norepinephrine concentrations in the antral portion of the gastric wall, and increased the labeling indices of the antral epithelial cell s of rats fed on a normal protein diet. However, in rats fed a high pr otein diet, administration of NaCl had no significant influence on the se two parameters. These findings indicate that a high protein diet at tenuates enhanced gastric carcinogenesis induced by the administration of NaCl, and that this effect may be related to its ability to decrea se norepinephrine concentrations in the gastric wall, which subsequent ly decreases the proliferation of antral epithelial cells. (C) 1997 El sevier Science Ireland Ltd.