Yue Yingying, Ke Youlan, Zheng Junping, Wang Zicheng, Liu Hongtao, Liu Songlin
College of Traditional Chinese Medicine, Hubei University of Chinese Medicine, Wuhan, China.
Hubei Shizhen Laboratory, Wuhan, China.
Front Pharmacol. 2024 Sep 16;15:1466336. doi: 10.3389/fphar.2024.1466336. eCollection 2024.
Depression is a common psychological disorder, accompanied by a disturbance of the gut microbiota and its metabolites. Recently, microbiota-derived tryptophan metabolism and AMPK/mTOR pathway were found to be strongly linked to the development of depression. Shugan Hewei Decoction (SHD) is a classical anti-depression traditional Chinese medicine formula. Although, we have shown that SHD exerted antidepressant effects via cecal microbiota and cecum NLRP3 inflammasome, the specific mechanism of SHD on metabolism driven by gut microbiota is unknown. In this study, we focus on the tryptophan metabolism and AMPK/mTOR pathway to elucidate the multifaceted mechanisms of SHD.
Male rats were established to the chronic unpredictable stress (CUS)/social isolation for 6 weeks, and SHD-L (7.34 g/kg/d), SHD-H (14.68 g/kg/d), Fructooligosaccharide (FOS) (3.15 g/kg/d) were given by intragastric administration once daily during the last 2 weeks. Behavioral experiments were carried out to evaluate the model. The colonic content was taken out for shotgun metagenomic sequencing combined with the untargeted metabolomics, the targeted tryptophan metabolomics. ELISA was used to detect the levels of zonula occludens 1 (ZO-1), Occludin in colon, as well as lipopolysaccharide (LPS), diamine oxidase (DAO), D-lactate (DLA) in serum. The expressions of mRNA and proteins of adenosine monophosphate-activated protein kinase (AMPK)/mammalian target of rapamycin (mTOR) pathway of autophagy were examined using RT-qPCR and Western blot in colon.
SHD modulated gut microbiota function and biological pathways, which were related to tryptophan metabolism. In addition, SHD could regulate microbiota-derived tryptophan production (such as reduction of 3-HK, 3-HAA etc., increment of ILA, IAA etc.), which metabolites belong to kynurenine (KYN) and indole derivatives. Further, SHD reduced intestinal permeability and enhanced the intestinal barrier function. Moreover, SHD could upregulate the levels of AMPK, microtubule associated protein light chain 3 (LC3), autophagy related protein 5 (ATG5) and Beclin1, downregulate the levels of mTOR, p62, promoted autophagy in colon. Spearman's analysis illustrated the close correlation between tryptophan metabolites and intestinal barrier, AMPK/mTOR pathway.
SHD may exert antidepressant-like effects by regulating microbiota-derived tryptophan metabolism, and triggering the AMPK/mTOR pathway of autophagy, enhancing the intestinal barrier function.
抑郁症是一种常见的心理障碍，伴有肠道微生物群及其代谢产物的紊乱。最近，发现微生物群衍生的色氨酸代谢和AMPK/mTOR途径与抑郁症的发生密切相关。疏肝和胃汤（SHD）是一种经典的抗抑郁中药方剂。虽然我们已经表明SHD通过盲肠微生物群和盲肠NLRP3炎性小体发挥抗抑郁作用，但SHD对肠道微生物群驱动的代谢的具体机制尚不清楚。在本研究中，我们聚焦于色氨酸代谢和AMPK/mTOR途径，以阐明SHD的多方面机制。
将雄性大鼠建立慢性不可预测应激（CUS）/社会隔离模型6周，在最后2周每天一次经胃内给予SHD-L（7.34 g/kg/d）、SHD-H（14.68 g/kg/d）、低聚果糖（FOS）（3.15 g/kg/d）。进行行为实验以评估模型。取出结肠内容物进行鸟枪法宏基因组测序，并结合非靶向代谢组学、靶向色氨酸代谢组学。采用ELISA法检测结肠中紧密连接蛋白1（ZO-1）、闭合蛋白的水平，以及血清中脂多糖（LPS）、二胺氧化酶（DAO）、D-乳酸（DLA）的水平。采用RT-qPCR和蛋白质免疫印迹法检测结肠中自噬的腺苷单磷酸激活蛋白激酶（AMPK）/雷帕霉素哺乳动物靶蛋白（mTOR）途径的mRNA和蛋白表达。
SHD调节了与色氨酸代谢相关的肠道微生物群功能和生物途径。此外，SHD可以调节微生物群衍生的色氨酸生成（如3-羟基犬尿氨酸、3-羟基邻氨基苯甲酸等减少，吲哚-3-乳酸、吲哚-3-乙酸等增加），这些代谢产物属于犬尿氨酸（KYN）和吲哚衍生物。此外，SHD降低了肠道通透性，增强了肠道屏障功能。此外，SHD可以上调AMPK、微管相关蛋白轻链3（LC3）、自噬相关蛋白5（ATG5）和Beclin1的水平，下调mTOR、p62的水平，促进结肠自噬。Spearman分析表明色氨酸代谢产物与肠道屏障、AMPK/mTOR途径之间密切相关。
SHD可能通过调节微生物群衍生的色氨酸代谢，触发自噬的AMPK/mTOR途径，增强肠道屏障功能，从而发挥抗抑郁样作用。
