目的 比较慢性不可预知温和应激（CUMS）与慢性束缚应激（CRS）抑郁大鼠的肠道真菌、细菌及其代谢产物的差异，从“肠道菌群-代谢轴”角度探索不同应激刺激塑造抑郁大鼠肠道微环境是否具有特异性。方法 制备CUMS和CRS大鼠模型，采用强迫游泳实验和悬尾实验验证模型成功；采用16S rRNA基因测序技术测定2种抑郁模型大鼠肠道真菌、细菌的多样性及组成。应用UPLC-Q-TOF/MS技术的非靶向代谢组学方法，检测大鼠肠道内容物的代谢轮廓及代谢产物。通过数据关联分析，筛选与抑郁发生发展相关的肠道真菌、细菌及代谢产物，并比较2种模型的差异。结果 与相应对照组相比，CUMS大鼠和CRS大鼠强迫游泳和悬尾不动时间均显著延长（P<0.05、0.01、0.001），证实CUMS和CRS抑郁模型已成功制备。2种模型肠道真菌具有一定的相似性，其中门水平真菌Fungi_phy_Incertae_sedis和unclassified_k_Fungi以及属水平真菌Fungi_gen_Incertae_sedis和unclassified_k_Fungi在2种模型中的丰度均显著降低。2种模型大鼠肠道细菌组成及丰度变化差异较大，如Patescibacterota的丰度在CUMS大鼠中增加，而在CRS大鼠中降低；norank_f_[Eubacterium]_coprostanoligenes_group的丰度在CUMS大鼠中减少而在CRS大鼠中增加；Candidatus_Saccharimonas等5个属的细菌仅在CUMS大鼠中观察到显著变化；Thermodesulfobacteriota和Actinomycetota等2个门和norank_f_Muribaculaceae等9个属细菌仅在CRS大鼠中显著改变。2种模型大鼠肠道菌群代谢产物及富集通路差异较大，CUMS大鼠主要与初级胆汁酸生物合成、不饱和脂肪酸生物合成和色氨酸代谢紊乱密切相关，而CRS大鼠主要与类固醇激素生物合成和嘌呤代谢紊乱密切相关。结论 CUMS与CRS通过不同的菌群-代谢轴诱发抑郁样表现，提示应激源性质可特异性塑造肠道微环境与代谢紊乱模式，为抑郁的异质性机制研究与精准干预提供新思路。

Objective To compare the differences in gut mycobiota, microbiota, and metabolites between depression rat models induced by Chronic Unpredictable Mild Stress(CUMS) and Chronic Restraint Stress(CRS). From the perspective of the "gut microbiota-metabolite axis", this study aims to explore whether different stress stimuli specifically shape the gut microenvironment in depressed rats. Methods The CUMS and CRS rat models were prepared, and the success of the models was verified through the forced swimming test and the tail suspension test. 16S rRNA gene sequencing technique was used to determine the diversity and composition of gut mycobiota and microbiota in rats based on the two models. The metabolic profile and metabolites of gut contents in rats were detected by using the untargeted metabolomics method of UPLC-Q-TOF/MS. Through data association analysis, gut mycobiota, microbiota, and metabolites related to the occurrence and development of depression were screened, and the differences between the two models were compared. Results Compared with the corresponding control groups, the forced swimming and tail suspension immobility times of the CUMS rats and the CRS rats were significantly prolonged(P < 0.05, 0.01, 0.001), confirming that the depression models of CUMS and CRS have been successfully established. The sequencing results showed that the gut mycobiota in the two models had certain similarities, and the abundance of Fungi_phy_Incertae_sedis and unclassified_k_Fungi in the phylum level and Fungi_gen_Incertae_sedis and unclassified_k_Fungi in the genus level in the two models decreased significantly. There were significant differences in gut microbiota composition and change trend between the two models. Such as, the abundance of Patescibacterota increased in CUMS rats and decreased in CRS rats; the abundance of norank_f_[Eubacterium] _coprostanoligenes_group decreased in CUMS rats and increased in CRS rats; the bacterium of Candidatus_Saccharimonas and other four genus level bacteria showed significant changes only in CUMS rats; two phylum level bacteria including Thermodesulfobacteriota and Actinomycetota and nine genus level bacteria including norank_f_Muribaculaceae changed significantly in CRS rats. The results of metabolomics study showed that the metabolites and enrichment pathways of gut microbiota in the two models were significantly different. CUMS rats were mainly related to the disturbance of primary bile acid biosynthesis, unsaturated fatty acid biosynthesis and tryptophan metabolism, while CRS rats were mainly related to the disturbance of steroid hormone biosynthesis and purine metabolism. Conclusion Our findings demonstrate that CUMS and CRS induce depression-like phenotypes via distinct gut microbiota-metabolite axis, highlighting stressor-specific modulation of the gut microenvironment and metabolism. This work advances our understanding of the heterogeneous pathophysiology of depression and lays the groundwork for targeted interventions.

R965

国家自然科学基金资助项目(82274076)