全谷物糙米主效酚类成分群基于肠道FXR调节脂质代谢作用机制

Modern food nutrition study suggests that an appropriate increase in dietary whole grain rice improves lipid metabolism in human. Our previous studies have demonstrated that the polyphenol extract from brown rice (PEBR) can regulate lipid metabolism in vitro. However, the bioactive equivalence combinatorial components of polyphenols (BECCP) in brown rice remain unclear and the mechanism on regulating lipid metabolism is also unknown. In the present study, we will first investigate effects of PEBR on lipid metabolism in mice induced by high-fat/high-cholesterol diet. In order to elucidate the mechanism of PEBR on lipid metabolism, we are going to focus on influences of PEBR on the express of intestinal Farnesoid X Receptor (FXR) as well as its down-regulated target genes and proteins. Moreover, we compare the effects of different polyphenols combinatorial components from brown rice on lipid metabolism in NBD-cholesterol loaded Caco-2 cell by measuring uptake rate and outflow rate of NBD-cholesterol, which will enable us to find out the BECCP based on the theory of “equivalence combinatorial components” in Chinese Herbology. The expression of FXR and its targets will also be determined in NBD-cholesterol loaded Caco-2 cell. Based on the above-mentioned research, the mechanism of BECCPR on regulating lipid metabolism from the aspect of intestinal FXR will be systematically revealed at levels of animal, cell and molecular. This project will provide new knowledge for the lipid metabolism of whole grain and provide theoretical guide for the fine processing of whole grain.

现代食品营养学研究表明在膳食结构中适当增加全谷物的摄入量能有效改善机体的脂质代谢。针对前期研究发现全谷物糙米酚类提取物有体外调节脂质代谢作用而其具体成分及作用机制不明确等问题，本项目通过脂质代谢紊乱C57BL/6J小鼠模型，分析全谷物糙米酚类提取物对小鼠血脂水平及脂肪聚集的影响，探讨其对回肠法呢醇X受体FXR及其下游靶点回肠和肝脏中关键基因和蛋白表达水平的影响，明确其对肠道FXR的调节作用；通过荧光标记胆固醇负荷Caco-2细胞模型，比较剔除糙米酚类提取物中某一酚类单体前后的不同酚类成分群对细胞胆固醇摄入和外流的影响，借鉴中药“等效成分群”的研究思路，筛选确定糙米主效酚类成分群；分析主效酚类成分群对肠道FXR及其靶点FGF15等的基因和蛋白表达水平的影响，探明糙米主效酚类成分群基于肠道FXR调节改善脂质代谢的分子机制。研究结果将丰富全谷物调节脂质代谢的理论基础，为其精深加工提供理论依据。

现代食品营养学研究表明在膳食结构中适当增加全谷物的摄入量能有效改善机体的脂质代谢。针对前期研究发现全谷物糙米酚类提取物有体外调节脂质代谢作用，但其具体成分及作用机制不明确等问题，本项目采用高脂高胆固醇膳食小鼠模型，研究了全谷物糙米酚类物质提取物（BRPE）对脂质代谢的改善作用及基于肠道FXR的作用机制。发现摄入BRPE能够显著降低高脂高胆固醇膳食小鼠血清和肝脏总胆固醇（TC）、甘油三酯（TG）含量、减轻肝脏、附睾脂质聚集等，表明BRPE对高脂高胆固醇膳食诱导的脂质代谢紊乱具有良好的调节作用。采用分子生物学方法分析摄入BRPE对小鼠肠道FXR及其下游靶基因表达的影响，发现摄入BRPE能够显著提高回肠成纤维细胞生长因子15（FGFl5）、回肠胆汁酸结合蛋白（IBABP）、有机溶质转运体α（OSTα）、小异源二聚体配体1（SHP1）、肝受体同源物（LRH-1）的基因表达水平和肝脏成纤维细胞生长因子受体4（FGFR4）基因表达水平，表明BRPE能有效激活肠FXR信号通路，从而发挥脂质代谢调节作用。.通过荧光标记胆固醇负荷Caco-2细胞模型，比较剔除糙米酚类提取物中某一酚类单体前后的不同酚类成分群对细胞胆固醇摄入和外流的影响，发现分类成分群（原儿茶酸+儿茶素+表儿茶素+阿魏酸）是糙米酚类提取物的主效酚类成分群，其调节摄入率和外流率上与糙米酚类提取物具有等效性。利用分子生物学方法分析主效酚类成分群对肠道FXR及下游靶基因的影响，发现主效酚类成分群能够显著提高FGFl5、IBABP、OSTα、SHP1、LRH-1基因表达水平，表明主效酚类成分群能通过激活肠FXR信号通路来改善脂质代谢。 研究结果将丰富全谷物调节脂质代谢的理论基础，为其精深加工提供理论依据，为提高全谷物糙米的附加值具有重大意义。.本项目发表论文 9 篇，其中 SCI 收录 6 篇，获得科技奖励 1 项，培养研究生1名。