Promotion effects of hot water on N-nitrosomethylbenzylamine-induced esophageal tumorigenesis in F344 rats

This study is to determine the effects of hot water on N-nitrosomethylbenzylamine (NMBA)-induced rat esophageal tumorigenesis model. F344 rats received one treatment of hot water 1 ml/kg and NMBA 1 mg/kg, or a combination treatment of NMBA I mg/kg pus hot water 1 ml/ kg, or/and EGCG (epigal locatechin-3-gallate) 10 mg/kg. The experiment was concluded at the 20th week. Our results showed that the number of tumors and incidence of carcinomas were significantly increased by hot water (65degreesC) (p<0.05, p<0.03, respectively), as compared with the group which received NMBA injections only. EGCG treatment did not significantly reduce the number or the size of tumours as the temperature of added hot water increased. In addition, PGE(2) production was induced by NMBA, and further significantly increased by added hot water (p<0.05). On the other hand, EGCG slightly decreased the elevated PGE(2) production, however, this effect of EGCG was offset by hot water. Our study further confirmed that the drinking of hot beverages increased the risk of esophageal carcinogenesis, and the drinking hot tea will abolish the inhibitory effects of EGCG on this disease.