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电离辐射对肠道胆汁酸代谢的影响:甘氨熊脱氧胆酸辐射防护作用机制的探索

Effects of Ionizing Radiation on Intestinal Bile Acid Metabolism: Mechanism of the Radioprotective Effect of Glycoursodeoxycholic Acid

  • 摘要:
    目的 放射性肠道损伤是肿瘤放射治疗过程中常见并发症,本研究旨在观察电离辐射对肠道胆汁酸短期变化的影响,并探索胆汁酸对肠道细胞辐射防护作用。
    方法 采用腹部每日照射2 Gy,连续照射4 d射线构建大鼠小肠损伤模型,并运用代谢组学技术对胆汁酸进行定量分析。将小肠上皮细胞IEC-6分为二甲基亚砜(dimethyl sulfoxide, DMSO)对照组(DMSO+0 Gy)、甘氨熊脱氧胆酸(glycoursodeoxycholic acid, GUDCA)实验组(GUDCA+0 Gy)、DMSO辐照组(DMSO+10 Gy)、GUDCA辐照组(GUDCA+10 Gy)。用CCK-8法检测细胞的存活率和细胞毒性;采用流式细胞术检测细胞的凋亡率;通过平板克隆形成实验检测细胞克隆形成率以及放射敏感性;利用Western blot检测与细胞死亡相关的蛋白表达水平。
    结果 大鼠小肠组织辐照后均出现典型放射性肠损伤表现,多种胆汁酸在辐照前后发生波动,其中GUDCA在辐照后3 d显著升高,而在辐照后7 d恢复至辐照前水平;与对照组相比较,20 μmol/L GUDCA作用24 h,辐照后细胞存活率高于DMSO组(P<0.05);PARP、caspase-3、RIP、GSDMD蛋白表达量明显低于对照组(P<0.05);20 μmol/L GUDCA作用24 h、48 h,辐照后细胞凋亡率低于DMSO组(P<0.05);与DMSO对照组相比,GUDCA实验组在0、2、4和6 Gy剂量辐照下克隆形成能力均强于DMSO组(P<0.05),GUDCA组平均致死量D0为6.374,DMSO组平均致死量D0为4.572,与DMSO对照组相比,GUDCA药物组的D0值增大,SER为0.717。
    结论 辐照大鼠腹部后,大鼠肠道胆汁酸代谢会产生显著变化,GUDCA可在一定程度上对肠道细胞产生辐射防护作用。

     

    Abstract:
    Objective Radioactive intestinal injury is a common complication during radiotherapy of tumors. The aim of this study is to observe the effect of ionizing radiation on short-term changes in intestinal bile acids and to investigate the radioprotective effect of bile acids on intestinal cells.
    Methods A rat model of small intestinal injury was constructed by exposing the abdomen of the rats to daily irradiation at 2 Gy for 4 d in succession. The bile acids were quantified using metabolomics analysis. IEC-6 cells, a small intestinal epithelial cell line, were divided into a dimethyl sulfoxide (DMSO) control group receiving DMSO and 0 Gy irradiation, a glycoursodeoxycholic acid (GUDCA) experimental group receiving GUDCA and 0 Gy irradiation, a DMSO irradiation group receiving DMSO and 10 Gy irradiation, and a GUDCA irradiation group receiving GUDCA and 10 Gy irradiation. Cell viability and cytotoxicity was assessed by CCK-8 assay test. The apoptosis rate of cells was determined by flow cytometry. The colony formation rate and the radiosensitivity of the cells were determined by colony formation assay on solid media. The expression levels of proteins associated with cell death were determined using Western blot.
    Results After exposure to irradiation, the small intestine tissues of the rats showed typical radioactive intestinal injury. In addition, various bile acids showed fluctuation before and after irradiation. Among the bile acids, GUDCA increased significantly at 3 d after irradiation, but returned to the pre-irradiation level at 7 d after irradiation. Compared with the control group, after GUDCA treatment at 20 μmol/L for 24 h, the cell viability rate after irradiation was significantly higher than that of the DMSO group (P<0.05); the expression levels of the proteins, including PARP, caspase-3, RIP, and GSDMD, were significantly lower than those in the control group (P<0.05). After GUDCA treatment at 20 μmol/L for 24 h and 48 h, the cell apoptosis rate of the cells after irradiation was lower than that of the DMSO group (P<0.05). Compared with the DMSO control group, the colony formation ability of the GUDCA experimental group was stronger than that of the DMSO group after irradiation at 0, 2, 4, and 6 Gy (P<0.05). D0, or the mean lethal dose, of the GUDCA group was 6.374, while that of the DMSO group was 4.572. Compared with the DMSO control group, the D0 value of the GUDCA treatment group increased, and the sensitization enhancement ratio (SER) was 0.717.
    Conclusion After exposing the abdomen of rats to irradiation, the intestinal bile acid metabolism of the rats will change significantly, and GUDCA can produce radioprotective effects on intestinal cells to a certain extent.

     

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