黄芪对自然衰老小鼠肠道功能及菌群稳态的作用研究

The effect of Astragalus membranaceus(Fisch.) Bge. on intestinal function and gut microbiota homeostasis in aging mice

伴随着衰老的进程,机体内多个组织、器官功能发生退行性改变。肠道功能失调及菌群稳态失衡是老年人常见表现。本研究旨在探讨黄芪对自然衰老小鼠肠道功能及菌群稳态的影响,为进一步的抗衰老机制研究提供依据。采用自然衰老小鼠模型,动物实验遵循南京中医药大学动物伦理委员会规定。首先采用“虚弱指数”综合评分对小鼠衰老表型进行整体评价。检测小鼠肠道葡萄糖吸收能力、肠道运输时间、肠道脂肪酶以及淀粉酶的活性,评估肠道吸收和运输功能,酶联免疫吸附法(ELISA)检测结肠炎症因子水平,苏木精-伊红(H&E)染色评价肠道绒毛长度,阿立新蓝(AB)染色评价肠道黏膜厚度及杯状细胞数量,利用qRT-PCR方法检测肠道干细胞增殖与分化相关基因的转录水平, 16S rDNA测序分析肠道菌群组成。结果显示,在衰老整体表型方面,黄芪具有降低衰老小鼠“虚弱指数”的趋势,但并没有显著性差异。在衰老表型的某些指标上,黄芪对衰老小鼠毛发以及体能的改善作用最为显著。在肠道功能方面,黄芪可增加衰老小鼠肠道葡萄糖吸收能力,缩短肠道运输时间,促进脂肪酶分泌。黄芪可降低衰老小鼠肠道组织中炎症因子如肿瘤坏死因子α (TNF-α)、白介素6 (IL-6)水平;增加小肠绒毛长度、结肠黏膜厚度以及杯状细胞数量,促进肠干细胞的增殖与分化,改善肠道屏障功能。此外,黄芪能增加小鼠肠道菌群多样性,恢复肠道菌群稳态,恢复毛螺菌科等多种细菌的丰度。上述研究结果提示,黄芪可改善自然衰老小鼠的某些表型,对小鼠肠道功能及菌群稳态的改善作用尤其显著。

Aging can cause degenerative changes in the function of multiple tissues and organs in the body.Gastrointestinal diseases and intestinal dysfunction are very common in the elderly people.The purpose of this study is to explore the effect of the total extract of Astragalus membranaceus(Fisch.) Bge.on intestinal function and gut microbiota homeostasis in natural aging mice,which will provide clues for further mechanism study.The natural aging mice model is established and animal experiments follow the regulations of the Animal Ethics Committee of Nanjing University of Traditional Chinese Medicine.The overall health of the mice was evaluated by the "frailty index" scoring method.The intestinal absorption and transport function were measured by detecting intestinal glucose absorption capacity,transport time,lipase and amylase activities of aging mice.Intestinal inflammation was assessed by detecting inflammatory cytokines by enzyme-linked immunosorbent assay(ELISA).The pathological changes in the intestines of aging mice were tested by hematoxylin-eosin(H&E) staining and alizarin blue(AB) staining.The qRT-PCR method was used to explore the gene transcription level related with the proliferation and differentiation of intestinal stem cells.Microbiota analysis based on 16S rDNA were used to evaluate the composition of gut microbiota.The results showed that Astragalus had a tendency to reduce the "frailty index" of aging mice,but did not show a significant difference.In some indicators of aging phenotype,Astragalus has the most significant effect on hair loss and physical fitness.In terms of intestinal function,Astragalus could increase intestinal glucose absorption capacity,shorten intestinal transportation time and promote lipase secretion in aging mice.The levels of inflammatory cytokines such as tumor necrosis factor-α(TNF-α) in the aging intestinal tissue were reduced after Astragalus administration.Astragalus also ameliorated the pathological degeneration of the intestinal tissue of aging mice by increasing the length of small intestinal villi,the thickness of colonic mucosa and goblet cell number.In addition,Astragalus elevated the expression of genes associated with the proliferation and differentiation in jejunum and modulated gut microbiota,especially restoring the abundance of Lachnospiraceae.Taken together,the above research results demonstrate the total extract of Astragalus as a key factor improving the intestinal function and gut microbiota homeostasis of aging mice.