Abstract
Based on investigations in humans, intestinal metaplasia have been considered as precancerous lesions or a predisposing condition for differentiated gastric carcinoma development. An inverse relationship between quantity of intestinal metaplasia and gastric tumor development and its presence does not exert a positive influence on induction of gastric neoplasia by N-methyl-N'-nitro N-nitrosoguanidine (MNNG) or N-methylnitorsoure (MNU) in rats. Male-5week-old CD, Wistar and F344 rats were X-irradiated with a total of 20 Gy in two equal fractions with a 3day interval. Beginning 16 weeks after the first dose, DMH was injected at a dose of 20mg/kg body weight weekly for 10 times in CD and Wistar rats. Azoxymethane (AOM) was injected at a dose of 15mg/kg body weight weekly for 3 weeks and 2 amino 1 methyl 6 phenylimidazol [4,5-b]pyridine (PhIP) was given every 2 days, 3 times per week, for a total 10 doses of 75 mg/kg body weight by intragastric intubation in F344 rats. Twelve months after the initial carcinogen treatment, tumors in pylorus of the glandular stomach were observed in the X-rays pulas DMH, AOM or PhIP group in X-ray irradiated rats. No such lesions were found in the DMH, AOM, PhIP or X-ray alone or nontreated groups. Large intestinal tumors appeared in the glandular stomach by X-ray plus colon carcinogen.
