Data Sheet 1_Transcutaneous auricular vagus nerve stimulation regulates gut microbiota mediated peripheral inflammation and metabolic disorders to suppress depressive-like behaviors in CUMS rats.zip

BackgroundDepression is a common mental disorder, and the changes of intestinal microflora and peripheral plasma metabolites can affect the gut-brain axis through vagus nerve, leading to the occurrence, and progress of the disease. Transcutaneous auricular vagus nerve stimulation (taVNS) has been previously shown to be clinically safe and effective in treating depression. However, there is no evidence whether its antidepressant effect is related to the regulation of intestinal flora and metabolites.
ObjectiveThis study investigated the gut microbiota and plasma metabolism mechanisms of taVNS in the treatment of depression.
MethodsIn this study, we established a chronic unpredictable mild stress (CUMS) model in SD rats for 5 weeks. During the last 3 weeks of CUMS treatment, the rats received continuous taVNS intervention for 3 weeks. Depressive-like behavior in SD rats was evaluated through behavioral assessments. The gut microbiota and plasma were analyzed using 16S rRNA gene sequencing and liquid chromatography-mass spectrometry (LC-MS) techniques.
ResultsBehavioral tests showed that taVNS significantly reversed the depressive-like behavior induced by CUMS in rats. 16S rRNA sequencing results showed that taVNS could improve the intestinal flora structure of CUMS rats. Microbial community characterization index showed that taVNS could reverse the gut microbiota dysbiosis in CUMS rats. ROC analysis revealed that Lachnospiraceae_NK4A136_group. Parabacteroides and Corynebacterium_1 are potential biomarkers for diagnosing gut microbiota dysbiosis in CUMS rats and could also serve as potential therapeutic targets for taVNS. Plasma metabolomics results showed that the differential metabolites between the CUMS group and the control group were primarily enriched in pathways such as bile acid metabolism, arachidonic acid metabolism and ether lipid metabolism. The differential metabolites between the taVNS group and the CUMS group were primarily enriched in pathways related to vitamin digestion and absorption, glycerophospholipid metabolism and amino acid metabolism. Correlation analysis between the gut microbiota and plasma metabolites suggested that pathogenic microbial genera such as Lachnospiraceae, Lactobacillus, and Tyzzerella were positively correlated with plasma metabolites during inflammation, bile acid, and lipid metabolism dysregulation, while beneficial microbiota showed the opposite trend.
ConclusionThis study demonstrated that taVNS can regulate the gut microbiota, including Lachnospiraceae, Lactobacillus, Tyzzerella, and Bacteroides genera, which mediate peripheral inflammation, bile acid, and lipid metabolism dysregulation, thereby reversing the depressive-like behavior induced by CUMS in rats and exerting an antidepressant effect.

背景
抑郁症（Depression）是一类常见精神障碍，肠道菌群与外周血浆代谢物的变化可通过迷走神经影响肠-脑轴，进而参与疾病的发生与进展。经皮耳迷走神经刺激（transcutaneous auricular vagus nerve stimulation, taVNS）此前已被证实用于抑郁症治疗时具备临床安全性与有效性，但目前尚无证据表明其抗抑郁效应是否与调控肠道菌群及代谢物相关。

研究目的
本研究旨在探讨taVNS治疗抑郁症的肠道菌群与血浆代谢组学机制。

研究方法
本研究对SD大鼠构建为期5周的慢性不可预见性温和应激（chronic unpredictable mild stress, CUMS）模型。在CUMS造模的最后3周，对大鼠实施连续3周的taVNS干预。通过行为学评估检测SD大鼠的抑郁样行为；采用16S rRNA基因测序与液相色谱-质谱联用法（liquid chromatography-mass spectrometry, LC-MS）对肠道菌群及血浆样本进行分析。

研究结果
行为学测试结果显示，taVNS可显著逆转CUMS诱导的大鼠抑郁样行为。16S rRNA测序结果表明，taVNS能够改善CUMS大鼠的肠道菌群结构。微生物群落特征指数显示，taVNS可逆转CUMS大鼠的肠道菌群失调状态。ROC分析揭示，Lachnospiraceae_NK4A136_group、Parabacteroides及Corynebacterium_1可作为诊断CUMS大鼠肠道菌群失调的潜在生物标志物，同时也可作为taVNS的潜在治疗靶点。血浆代谢组学结果显示，CUMS组与对照组间的差异代谢物主要富集于胆汁酸代谢、花生四烯酸代谢及醚脂代谢等通路。taVNS组与CUMS组间的差异代谢物主要富集于维生素消化吸收、甘油磷脂代谢及氨基酸代谢相关通路。肠道菌群与血浆代谢物的关联分析表明，Lachnospiraceae、Lactobacillus及Tyzzerella等致病微生物属与炎症、胆汁酸及脂质代谢失调相关的血浆代谢物呈正相关，而有益菌群则呈现相反的调控趋势。

研究结论
本研究证实，taVNS可调控包括Lachnospiraceae、Lactobacillus、Tyzzerella及Bacteroides在内的肠道菌群，通过介导外周炎症、胆汁酸及脂质代谢失调的改善，逆转CUMS诱导的大鼠抑郁样行为，进而发挥抗抑郁效应。