Lack of tumor promoting effects of carrageenan on 1,2-dimethylhydrazine-induced colorectal carcinogenesis in male f344 rats

Abstract

The modifying effects of carrageenan administration on colonic carcinogenesis were investigated in male F344/DuCrj rats subcutaneously injected with 1,2-dimethylhydrazine dihydrochloride (DMH) 4 times at weekly intervals. Starting one week after the final injection of DMH, the rats were given carrageenan at dietary levels of 0, 1.25, 2.50. or 5.0% until week 36. Animals given cholic acid at a dietary level of 0.2%, served as a reference group. All rats were killed at the end of week 36, and the colons were carefully examined for preneoplastic and neoplastic lesions. No treatment related changes in clinical signs and body weights were found. Detailed histopathological examination did not demonstrate any enhancement by carrageenan of carcinogenesis with regard to the incidence of lesions in the colon. The results thus demonstrate that carrageenan does not possess any promoting activity at the highest dietary level of 5.0% for colorectal carcinogenesis under the present experimental conditions.