米糠不溶性膳食纤维对慢性镉暴露小鼠的保护作用

该研究探讨了米糠不溶性膳食纤维（rice bran insoluble dietary fiber，RBIDF）对慢性镉暴露小鼠的保护作用。对大肠埃希菌进行体外培养，观察镉对细菌生长的影响以及RBIDF对镉的吸附作用；将小鼠分为阴性对照组、阳性对照组及RBIDF处理组，喂养8周后检测其组织、血液和粪便中镉的含量以及粪便中短链脂肪酸（short chain fatty acids，SCFAs）的含量，并提取粪便中肠道菌群DNA进行高通量测序和荧光定量PCR检测。结果显示，RBIDF可以吸附镉，保护大肠埃希菌的生长；与阳性对照组相比，RBIDF处理组小鼠血液中镉含量下降了66.67%、肝脏中下降了57.67%、小肠中下降了27.15%、粪便中增加了60.64%，粪便中三种SCFAs含量分别增加到1.30倍、2.25倍、2.75倍，并且肠道细菌总量增加到1.40倍。此外，在门水平上，RBIDF处理组肠道菌群结构与阴性对照组相似，以拟杆菌门（68.75%）、厚壁菌门（23.67%）和变形菌门（6.82%）为主，而阳性对照组以拟杆菌门（55.71%）、厚壁菌门（33.25%）、疣微菌门（5.62%）为主。这些结果表明，RBIDF可以吸附镉，降低小鼠组织血液中的镉浓度，促进小鼠肠道菌群恢复，对慢性镉暴露小鼠具有保护作用。

Protective Effect of Rice Bran Insoluble Dietary Fiber on Chronic Cadmium-exposed Mice

Escherichia coli were cultured in vitro to observe the effect of cadmium on bacterial growth as well as the adsorption of cadmium by rice bran insoluble dietary fiber (RBIDF) to investigate the protective effects of RBIDF on mice under chronic cadmium exposure. Mice were divided into the negative and positive control groups and RBIDF treatment group. After 8 weeks of feeding, cadmium levels in tissues, blood, and feces as well as fecal short chain fatty acids (SCFAs) were tested. DNA was extracted from intestinal flora in feces for high-throughput sequencing and fluorescence quantitative PCR detection. The results of the experiments showed that RBIDF can adsorb cadmium and protect the growth of E. coli. Cadmium content in blood, liver, small intestine, and feces of mice treated with RBIDF decreased by 66.67%, 57.67%, 27.15%, and 60.64%, respectively, when compared with that in the positive control group. The levels of the three types of SCFAs in feces increased by 1.30 times, 2.25 times, and 2.75 times, respectively. The total amount of intestinal bacteria in the RBIDF treatment group increased by 1.40 times. In addition, at the phylum level, the distribution of intestinal flora of the RBIDF treatment group was similar to that of the negative control group and was dominated by Bacteroidetes (68.75%), Firmicutes (23.67%), and Proteobacteria (6.82%). The positive control group was dominated by Bacteroidetes (55.71%), Firmicutes (33.25%), and Verrucomicrobia (5.62%). The results of this study suggest that RBIDF is able to adsorb cadmium to reduce cadmium concentration in the tissues and blood of mice, promote the recovery of intestinal flora in mice, and has a protective effect on chronic cadmium-exposed mice.