EFFECT OF CO-ADMINISTRATION OF N-METHYL-N'-NITRO-N-NITROSOGUANIDINE AND SODIUM CHLORIDE AS AN INITIATION PROCEDURE FOR A PROMOTING EFFECT OF ETHOXYQUIN ON STOMACH TUMORIGENESIS IN F344 MALE RATS

抄録

The promoting potential of ethoxyquin, an antioxidant, was investigated on two-stage glandular stomach carcinogenesis in rats. After simultaneous administration of N-methyl-N'-nitro-Nnitrosoguanidine (MNNG, 100ml/L in the drinking water) and sodium chloride (NaCl, 10% in basal diet) to group I or these agents singly to groups 2 and 3, respectively, for the first 8 weeks, the animals received a 1% ethoxyquin supplement in the basal diet for the following 32 weeks. Group 4 rats received the MNNG and NaCl combination and were then maintained as controls. The resultant incidences of carcinomas arising in the pyloric mucosa of rats in groups 1 to 4 were 8/17 (47%), 1/16 (6%), 0/16 (0%), and 2/10 (20%), respectively, with the group 1 incidence being significantly higher than that of group 2 or 3. These results clearly showed that promotion by ethoxyquin was observed only after simultaneous treatment with MNNG and NaCl, but not after MNNG treatment without NaCl.