Table 1_Behavioral alterations in antibiotic-treated mice associated with gut microbiota dysbiosis: insights from 16S rRNA and metabolomics.xlsx

The gut and brain interact through various metabolic and signaling pathways, each of which influences mental health. Gut dysbiosis caused by antibiotics is a well-known phenomenon that has serious implications for gut microbiota-brain interactions. Although antibiotics disrupt the gut microbiota’s fundamental structure, the mechanisms that modulate the response and their impact on brain function are still unclear. It is imperative to comprehend and investigate crucial regulators and factors that play important roles. We aimed to study the effect of long-term antibiotic-induced disruption of gut microbiota, host metabolomes, and brain function and, particularly, to determine the basic interactions between them by treating the C57BL/6 mice with two different, most commonly used antibiotics, ciprofloxacin and amoxicillin. Anxiety-like behavior was confirmed by the elevated plus-maze test and open field test. Gut microbes and their metabolite profiles in fecal, serum, and brain samples were determined by 16S rRNA sequencing and untargeted metabolomics. In our study, long-term antibiotic treatment exerted anxiety-like effects. The fecal microbiota and metabolite status revealed that the top five genera found were Lactobacillus, Bacteroides, Akkermansia, Ruminococcus_gnavus_group, and unclassified norank_f_Muribaculaceae. The concentration of serotonin, L-Tyrosine, 5-Hydroxy-L-tryptophan, L-Glutamic acid, L-Glutamate, 5-Hydroxyindole acetic acid, and dopaminergic synapsis was comparatively low, while adenosine was high in antibiotic-treated mice. The KEGG enrichment analysis of serum and brain samples showed that amino acid metabolism pathways, such as tryptophan metabolism, threonine metabolism, serotonergic synapsis, methionine metabolism, and neuroactive ligand-receptor interaction, were significantly decreased in antibiotic-treated mice. Our study demonstrates that long-term antibiotic use induces gut dysbiosis and alters metabolic responses, leading to the dysregulation of brain signaling molecules and anxiety-like behavior. These findings highlight the complex interactions between gut microbiota and metabolic functions, providing new insights into the influence of microbial communities on gut-brain communication.

肠道与大脑通过多种代谢通路与信号通路实现交互，每一条通路均可对精神健康产生影响。抗生素诱发的肠道菌群失调（gut dysbiosis）是一种已被广泛认知的现象，其对肠道菌群与大脑的交互作用具有重要的临床意义。尽管抗生素可破坏肠道菌群的基础结构，但调控菌群应答的具体机制及其对大脑功能的影响仍未明确。因此，亟需阐明并探究其中发挥关键作用的调控因子与相关因素。本研究旨在探究长期抗生素诱导的肠道菌群失调、宿主代谢组及大脑功能的变化，尤为关键的是，通过为C57BL/6小鼠施加两种临床最常用的抗生素——环丙沙星（ciprofloxacin）与阿莫西林（amoxicillin）——，明确三者之间的基本交互机制。本研究通过高架十字迷宫实验与旷场实验，成功验证了抗生素处理后小鼠出现焦虑样行为。采用16S rRNA测序（16S rRNA sequencing）与非靶向代谢组学（untargeted metabolomics）技术，对粪便、血清及脑组织样本中的肠道菌群及其代谢物谱进行了检测分析。结果显示，长期抗生素处理可诱导小鼠产生焦虑样行为。粪便菌群与代谢物谱分析结果显示，丰度排名前五的菌属依次为乳杆菌属（Lactobacillus）、拟杆菌属（Bacteroides）、嗜黏蛋白阿克曼菌属（Akkermansia）、瘤胃球菌_gnavus群（Ruminococcus_gnavus_group）以及未分类norank_f_Muribaculaceae（unclassified norank_f_Muribaculaceae）。与对照组小鼠相比，抗生素处理组小鼠体内5-羟色胺（serotonin）、L-酪氨酸（L-Tyrosine）、5-羟基-L-色氨酸（5-Hydroxy-L-tryptophan）、L-谷氨酸（L-Glutamic acid）、L-谷氨酸盐（L-Glutamate）、5-羟基吲哚乙酸（5-Hydroxyindole acetic acid）及多巴胺能突触相关物质的浓度相对较低，而腺苷（adenosine）的浓度则显著升高。对血清及脑组织样本进行KEGG富集分析（KEGG enrichment analysis）后发现，抗生素处理组小鼠体内的氨基酸代谢通路（如色氨酸代谢、苏氨酸代谢、5-羟色胺能突触、蛋氨酸代谢）以及神经活性配体-受体相互作用通路均显著下调。本研究证实，长期使用抗生素可诱发肠道菌群失调并改变宿主代谢应答，进而导致大脑信号分子调控紊乱及焦虑样行为的产生。本研究结果揭示了肠道菌群与代谢功能之间复杂的交互关系，为探究微生物群落对肠道-大脑通讯的影响提供了全新的研究视角。