膳食胆酸对辐射后的大鼠大肠上皮细胞凋亡与增殖的影响(英文)

Effect of Dietary Cholic Acid on Apoptosis and Proliferation of Large Intestinal Epithelial Cells in Irradiation-Exposed Rats

研究膳食胆酸对大肠上皮细胞在单剂量辐射之后急性反应的影响。各组实验大鼠在喂食空白膳食或者0.2%胆酸膳食10d之后接受全身γ射线照射,然后分别在辐射后1、3、6、12、24h被处死。盲肠和远端结肠样品被采集进行组织化学研究。结果显示:空白和胆酸膳食组的大鼠,其盲肠和远端结肠上皮细胞的凋亡均在辐射后被激发,并在辐射后3h后达到最高峰。然而,膳食胆酸在辐射6h后开始显著抑制远端结肠上皮细胞的凋亡。比较空白膳食各组,在大鼠接受辐射1h后盲肠和远端结肠两个部位的BrdU标记的细胞数量都开始减少,而胆酸的摄入却使上皮细胞的增殖瞬时增加。比较两个实验部位,膳食胆酸的摄入对远端结肠部位上皮细胞增殖和凋亡的影响比对盲肠部位上皮细胞的影响更大。综上所述,膳食胆酸的摄入改变了结肠细胞更新规律,并且对辐射后DNA受损伤的大肠上皮细胞的凋亡有抑制作用。

The effect of dietary cholic acid （CA） on the acute response of the rat large intestinal epithelial cells following a single-dose 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 post-irradiation 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.