Effects of Vitamin E Deficiency on 1,2-Dimethylhydrazine-Induced Intestinal Carcinogenesis in Rats

The effects of vitamin E deficiency on intestinal carcinogenesis and intestinal epithelial cell kinetics were investigated in male Wistar strain rats treated with 1,2-dimethylhydrazine (DMH) dihydrochloride. In the time course study of intestinal tumors induced by DMH (20 mg/kg, 20 weekly s.c. injections), at the early stage when no intestinal tumor was observed in control rats, tumor-bearing rats were detected in the vitamin E deficient group. Moreover, in rats treated with DMH (20 mg/kg, 3 weekly s.c. injections) after vitamin E deficient status, the incidence of rats with intestinal tumors was significantly higher in the vitamin E deficient group (58.3 %) than in the sufficient group (8.3 %) at 15 weeks after DMH treatment (p<0.05). However, after 45 weeks the incidence of tumors was the same in the both groups. In the cell kinetics study at 15 weeks after DMH treatment, DNA synthsis in the intestinal mucosa increased significantly in the vitamin E deficient group compared to that of the sufficient group. Nevertheless, the life span of intestinal epithelium was shorter in vitamin E deficient rats than in sufficient rats.
These results suggest that vitamin E deficiency promotes the initiation in colon carcinogenesis induced by DMH but inhibits the growth of the tumor.