Abstract:

The effect of dietary cholic acid (CA) on the acute response of the rat large intestinal epithelial cells following a singledose irradiation was investigated. Rats were exposed to whole-body gamma-irradiation after being fed a control or 0.2% CA diet for 10 days. The rats were then sacrificed at 1, 3, 6, 12 h and 24 h post-irradiation. Segments of cecum and distal colon were collected for histochemical analysis. Apoptosis in the epithelial cells of cecum and distal colon was stimulated and peaked at 3 h postirradiation in both dietary groups, however, in CA group, apoptosis was markedly inhibited at 6 h post-irradiation in the distal colon. In epithelial cells of rats fed the control diet, the number of bromodeoxyuridine (BrdU)-incorporated cells began to decrease at 1 h post-irradiation in both distal colon and cecum. Interestingly, the proliferation of the cells was transiently stimulated by CA intake before decreasing. It should be noted that the effect of dietary CA on proliferation and apoptosis in the colonic epithelial cells was more significant than that in the cecal epithelial cells. In conclusion, these results demonstrate that dietary CA alters the regeneration regularity of colonic cells and serves as an inhibitor of apoptosis in the intestinal epithelial cells following DNA damage induced by gamma-irradiation.

Key words: cholic acid (CA), gamma-irradiation, intestinal epithelial cells, proliferation, apoptosis