基于“肠道菌群-短链脂肪酸-DNA甲基化”途径研究逍遥散治疗抑郁症的作用机制

The pathogenesis of depression is complex. Previous studies suggest that the metabolites of intestinal flora closely related to depression are short-chain fatty acids. Intestinal flora-short-chain fatty acids can induce DNA methylation. DNA methylation is closely related to depression. Xiaoyaosan can improve depression symptoms by regulating intestinal flora. Therefore, this project proposes the following hypothesis: Xiaoyaosan may play a role in the prevention and treatment of depression by regulating intestinal flora - short chain fatty acid - DNA methylation. In this study, chronic restraint stress depression rat model was used to detect intestinal flora in rat feces by macrogenomics, macroproteomics, metabonomics, quantitative PCR, short-chain fatty acids in feces and colon by HPLC, DNA methylation profiles and target genes regulated by whole genome sulfite sequencing (WGBS), and functional tests of candidate target genes by quantitative PCR. Through the above methods, the mechanism of intestinal flora-short-chain fatty acid-DNA methylation in depression and the regulation mechanism of Xiaoyaosan were revealed. This study provides a new idea and method for the study of the anti-depression mechanism of Xiaoyaosan.

抑郁症发病机制复杂，前期研究提示与抑郁症密切相关的肠道菌群的代谢产物为短链脂肪酸，肠道菌群-短链脂肪酸可以诱导DNA甲基化发生变化，DNA甲基化与抑郁症密切相关；而逍遥散可以通过调节肠道菌群改善抑郁症状。因此，本项目提出如下假说：逍遥散防治抑郁症可能是通过调节肠道菌群-短链脂肪酸-DNA甲基化而发挥作用。本研究采用慢性束缚应激抑郁大鼠模型，通过宏基因组学、宏蛋白质组学、代谢组学、定量PCR法检测大鼠粪便中肠道菌群、HPLC法检测粪便及结肠中的短链脂肪酸、全基因组亚硫酸测序法（WGBS）法检测结肠DNA甲基化谱及其调控的靶基因、定量PCR法对候选靶基因进行功能验证，通过以上方法揭示肠道菌群-短链脂肪酸-DNA甲基化在抑郁症的作用机制及逍遥散的调节机制，本研究为逍遥散抗抑郁机制研究提供了新的思路和方法。

抑郁症是一种以明显而持久的心情低落为主的精神障碍性疾病，具有高病发率、高复发率、高致残率的特点，严重危害人类身心健康，给社会和家庭带来沉重负担。WHO 预测到 2030 年抑郁症将成为全球疾病负担的主要原因。抑郁症病的西医治疗存在明显副作用，因此开展中医药抗抑郁研究迫在眉睫。本研究采用慢性束缚应激抑郁大鼠模型，通过宏基因组学，非靶向代谢组学，靶向代谢组学和全基因组亚硫酸测序法初步阐释了肠道菌群-短链脂肪酸-DNA甲基化在抑郁症中的作用机制及逍遥散的调节机制。本研究发现逍遥散明显改善抑郁行为。逍遥散主要调控菌群为Bacteroidaceae,Bacteroidales,Bacteroidia,Bacteroidetes,Proteobacteria,Sutterellaceae等，Bacteroidaceae,Bacteroidales,Bacteroidia,Bacteroidetes主要产短链脂肪酸中的乙酸，丙酸，丁酸。Proteobacteria主要产丙酸。逍遥散组与模型组间上调的代谢物Phytosphingosine,Ursocholic acid,Acetoxyvalerenic acid,N-alpha-acetyl-l-ornithine,Cholesterol, 1-(4-hydroxyphenyl)ethenone等。主要下调的代谢物有Fenpropidin,Pyridoxamine, Palmitoleoyl3-carbacyclic phosphatidic acid等.逍遥散组与模型组之间代谢趋势下调的为Vitamin B6 metabolism，代谢趋势上调的为Cholesterol metabolism,Bile secretion,beta-Alanine metabolism,Basal cell carcinoma.逍遥散可以增加SCFAs总量，Acetic，Valeric，Isovaleon.结合DNA甲基化结果得出：逍遥散可以通过重塑肠道菌群，增加SCFAs，调节Butanoate metabolism，改善抑郁行为。本研究为逍遥散抗抑郁机制研究提供了新的思路及方法，为临床应用逍遥散抗抑郁提供了坚实的基础。