Intestinal radioprotection by vitamin E (alpha-tocopherol).

The major objective of this study was to test vitamin E as a potential radioprotectant for the small bowel of the rat. Vitamin E has previously been shown to provide radioprotection in animal models: increased survival after whole-body irradiation, diminished absorptive malfunction, and modest diminution in postirradiation hemolysis. The lumenal route for intestinal radioprotection has not been tested. Rat mid-small bowel was surgically exteriorized and segmented by ties into compartments, each of which was filled with a test solution 30 minutes before 1100 cGy of x-irradiation was administered. After the rats were killed 5 days later, the various segments were evaluated for surviving crypts, mucosal height, and goblet cell preservation. Lumenal agents included alpha-tocopherol phosphate and alpha-tocopherol acetate. In a separate study, dietary supplements of alpha-tocopherol were given for 10 days before irradiation, and the same irradiation sequence was carried out. Small bowel crypt cell numbers, mucosal height, and goblet cell numbers were significantly protected from radiation effects by dietary alpha tocopherol pretreatment and by lumenal application of the vitamin. These studies indicate that vitamin E can serve as a partial protectant against acute irradiation enteritis, whether given as chronic oral systemic pretreatment or as a brief topical application.