基于“菌-肠-脑”轴与相关神经递质的远志抗抑郁效应组分和作用机制研究

Alteration of intestinal microbiome could affect neurotransmitters in the brain associated with depression via "gut - brain" axis, which was closely associated with the pathogenesis and treatment of depression. The previous study demonstrated that Polygalae Radix has notable antidepressant effect and can mediate the levels of neurotransmitters in brain of depression models. But the poor absorption of saponins and oligosaccharide esters ,the main compositions of Polygalae Radix, indicated that they may take effect by other mechanisms. Therefore, it was worth in-depth study that whether Polygalae Radix and its active compounds control antidepressant through regulating the alteration of intestinal microbiome. The aims of the present study was to found the key functional microorganism Associated with the anti-depression effect of Polygalae Radix and to evaluated the adjustment function of Polygalae Radix, polygala saponins and oligosaccharide esters to microbiome in depression rats. The above results was combined with the changes in intestines and brain neurotransmitter system and the contrast of the results of vagotomy rats by parallel experiment to analysed the correlation of the key functional microorganism and neurotransmitter systems and the effective pathway of microbiome. And then the treatment mechanism of Polygalae Radix via the " microbiome - gut - brain" axis on depression was revealed. The efficacy contribution ratios of the two main components were analyzed and their gut bacteria metabolites were found to illuminate the effective components of polygala and its work forms. This study could provide new theoretical basis and idea for further studies regarding the antidepressant mechanism for Polygalae Radix and its related compounds.

肠道菌群与抑郁症的发生和治疗密切相关，它能通过“肠-脑”轴影响脑内与抑郁症相关的神经递质。前期研究表明远志具有良好的抗抑郁作用，能够调节抑郁模型大鼠脑内的神经递质水平，但远志主要组分皂苷和部分寡糖酯吸收差，提示其发挥抗抑郁作用存在入血以外的途径。初步研究和文献调研均提示远志能够作用于肠道菌群进而发挥抗抑郁功效。因此，本课题拟研究与远志抗抑郁作用相关的关键功能菌群，评价远志及远志总皂苷、总寡糖酯对关键功能菌群的调节作用。结合肠、脑内相关神经递质系统的变化及迷走神经切除大鼠的平行实验对比，分析远志抗抑郁功能菌群与神经递质系统的相关性及菌群作用的传导途径，揭示远志通过“菌-肠-脑”轴治疗抑郁症的作用机制。通过远志两类组分的药效贡献率评价及其肠道菌群代谢产物的分析，阐明远志通过调节肠道菌群治疗抑郁症的效应组分和肠道内发挥作用的形式。研究为远志及其复方抗抑郁作用机制的研究提供新的理论依据和研究思路。

肠道菌群与抑郁症的发生和治疗密切相关。常用中药远志具有良好的抗抑郁作用，然而，远志中主要成分吸收较差，提示其可能通过调节肠道微生态发挥抗抑郁作用。本项目采用16SrRNA高通量测序技术，分析远志及其组分干预后慢性不可预见性应激（CUMS）抑郁模型大鼠肠道菌群结构变化并探讨其通过“菌-脑-肠”轴治疗抑郁症的作用机制。结果表明远志寡糖酯是远志抗抑郁的主要组分。远志提取物及寡糖酯组分对模型大鼠肠道内的菌群失调具有调节作用，关键功能菌包括肠屏障功能保护菌、产内毒素菌和炎症相关菌群等。远志及寡糖酯组分能够增加肠屏障保护功能菌的丰度，下调产内毒素菌的丰度，进而改善短链脂肪酸代谢和肠黏膜损伤，降低肠黏膜通透性以及血清LPS及炎症因子IL-6的水平，从而减轻机体炎症水平而发挥抗抑郁作用。同时，通过Spearman相关性表明远志及寡糖酯组分对HPA轴功能亢进的改善作用可能与其对肠道菌群的调节作用有关；而肠道菌群可能通过犬尿氨酸代谢途径来影响脑内神经递质水平。项目还采用外翻肠囊法、体外菌群孵育法和UPLC-QTOF-MS 技术对远志及寡糖酯组分肠吸收及肠道菌群代谢产物进行研究，分析了远志寡糖酯成分的肠吸收特性并鉴定出20个远志寡糖酯类的代谢产物，初步阐明了远志寡糖酯组分肠道内发挥作用的形式。本研究为远志通过多途径多靶点发挥抗抑郁作用的机制提供新的理论依据，为进一步探讨远志提取物的抗抑郁作用机制提供了相关代谢通路的参考。