基于代谢组学的知母皂苷抗抑郁作用与肠道菌群关系研究

In recent years, the relationship between gut microbiota and depression has attracted more attention of clinicians and researchers. In our previous study, the extracts and constituents of rhizoma anemarrhenae were found to have obvious anti-depression effects. And timosaponin BII (TBII), whose content account for more than 70% of the total saponin of Anemarrhena asphodeloides rhizome, displayed stronger anti-depression efficacy after oral administration in multiple acute and chronic depression model animals, with low levels in portal vein and systemic plasma. It has been found that TBII was mostly transformed to the metabolite, timosaponin AIII, in the intestinal tract, who showed weak anti-depression effect. These results indicated that the anti- depression effect of TBII may be generated by stimulating the intestinal flora and secretions. The primary metabonomics experements manifested that the endogenic metabolites showed obvious tendency of returning to normal levels after oral administration of timosaponin in chronic depression animals. In the further study, we will systematically elucidate the mechanism of anti-depression effect of timosaponin by solving the following question how timosaponin affects the tryptophan metabolic pathway and NMDA receptors by regulating the intestinal flora.

近年来，肠道菌群与抑郁症的关系逐渐被临床医生和研究人员关注。.本团队在前期明确了知母提取物及皂苷成分具有显著抗抑郁作用的基础上，进一步发现含量占知母总皂苷70%以上的单体皂苷TBII在多种急性和慢性抑郁模型动物上口服给药的药效最强，但发现口服后血中（门静脉和外周血）暴露量极小。研究发现TBII在肠道中绝大部分转化为抗抑郁作用较弱的降解产物TAIII，提示知母皂苷的抗抑郁作用途径之一可能是通过影响肠道菌群及所分泌的炎症因子。初步代谢组学预试表明，慢性抑郁模型动物给药知母皂苷后，给药组的内源性代谢物具有明显回归正常水平趋势。.本项目将进一步研究知母皂苷如何通过影响肠道菌群进而影响色氨酸等代谢通路及NMDA受体，系统阐明知母皂苷的抗抑郁作用机制。

本研究采用多种动物模型评价知母皂苷YY-23F的抗抑郁药效，小鼠强迫游泳模型（FST），给药一周后，显示YY-23F各剂量（10，20，40 mg/kg）和阳性药FLX（20 mg/kg）均能够显著降低小鼠不动时间且YY-23F中高剂量效果优于阳性药氟西汀。慢性不可预知性温和刺激（CUMS）模型，给药四周后，显示YY-23F给药3周后，糖水饮用量显著升高，阳性药FLX给药4周后，糖水饮用量显著升高，YY-23F和阳性药FLX均具有抗抑郁作用，且YY-23F比阳性药起效快1周；悬尾测试中YY-23F和阳性药给药2周后，不动时间均显著降低，表明YY-23F和阳性药FLX均具有抗抑郁作用。菌群测序分析结果显示，YY-23F给药组有向正常组回归的趋势；根据LDA值，共筛选并鉴定出8个差异性菌种（种属水平），分别为g_Family_XIII_UCG-001，g_norank_f_norank_o_Rhodospirillales，g_NK4A214_group，s_uncultured_bacterium_g_XIII_UCG-001，s_Clostridium_sp._Culture-54，s_unclassified_g_NK4A214_group，s_unclassified_g_XIII_AD3011_group和s_gut_metagenome_g_norank。代谢组学研究结果显示， YY-23F给药组有向正常组回归的趋势；根据VIP值，共筛选并鉴定出36个差异性代谢物，如Butyric acid，3-Hydroxybutyric acid和4-Hydroxybutyric acid等，相关代谢通路如鞘脂类代谢，甘油磷脂代谢和三羧酸循环等。根据文献报道，推测相关机制为YY-23F可能通过调节肠道内梭菌比例，使得体内丁酸含量升高，而丁酸是一种脱乙酰化酶抑制剂，可通过产生5α还原型神经类固醇来促进体内C6胶质细胞分化，促进了BDNF基因表达，而BDNF可以进一步与酪氨酸激酶受体B结合，激活细胞内磷脂酰肌醇-3-羟激酶、丝裂原活化蛋白激酶、磷脂酶C等信号通路，从而调节突触可塑性、促进神经元的修复及再生，进而起到抗抑郁作用。本研究为抗抑郁新药研发提供新思路。