Stimulation of Rat Colonie Crypt Cell Proliferative Activity by Wheat Bran Consumption during the Stage of 1,2-Dimethylhydrazine Administration1

The effect on colonie epithelial cytokinetics of feeding a 20% wheat bran dietary supplement, either during and/or after the stage of carcinogen administration with 1,2-dimethylhydrazine, was examined in 48 male Sprague-Dawley rats fed defined diets for up to 31 weeks. Nutrient intake and body weight gain were equivalent in all groups of animals. All subgroups of rats fed bran, either during and/or after carcinogen administration, de veloped colonie crypt cell hyperplasia (p < 0.05), this being greater in the proximal than in the distal colon. Autoradiographic studies showed a significant increase in proximal colonie crypt cell-labeling index, proliferation zone size, and migration distance in those rats fed wheat bran during the period of carcinogen administration (p < 0.05). The increase in epithelial cell prolifer ation activity was most marked in the upper two-thirds of the crypt. These data show that there is a greater stimulation of crypt cell proliferation activity when wheat bran is consumed during the stage of carcinogen administration as compared to the stage following carcinogen exposure. This alteration in mucosal cytokinetics appears to be the mechanism by which wheat bran consumption enhances rat colon carcinogenesis during the period of dimethylhydrazine treatment.