Integrated analysis of metabolome and microbiome in a mouse model of sodium valproate-induced autism

Background: Sodium valproate (SV) can induce autism in animals. The aim of this study is to investigate the potential correlations between gut microbiota compositions and metabolomic disorders in SV-induced autism in mice.Methods: A autism mouse model induced by SV was established. Open field test, elevated plus-maze test and water maze test were performed to assess the anxiety like-behaviors and the learning and memory performance of mice. Hematoxylin & eosin staining showed the histological changes of hippocampus. Gas chromatography-mass spectrometry and 16S ribosomal RNA gene sequencing were integrated to evaluate the influences of SV on metabolic profiles and gut microbiota in autism mice. Based on Spearman correlation coefficient, the correlations between metabolites and gut microbiota were calculated.Results: Open field test, elevated plus-maze test and water maze test all indicated that SV treatment aggravated anxiety like-behaviors, and impeded spatial learning and memory capabilities. SV disrupted metabolic and biosynthesis pathways in hippocampus, cortex, intestine and serum samples, mainly including glycine, serine and threonine metabolism, glycerophospholipid metabolism and aminoacyl-tRNA biosynthesis and so on. SV could decrease the abundances of Dubosiella, Faecalibaculum, norank_f__norank_o__Clostridia_UCG-014, Bifidobacterium, Alloprevotella, Prevotellaceae_NK3B31_group, norank_f__Oscillospiraceae, Muribaculum, Erysipelatoclostridium, norank_f__Eubacterium_coprostanoligenes_group, Parabacteroides, norank_f__norank_o__Gastranaerophilales,norank_f__Desulfovibrionaceae, norank_f__Mitochondria, Rikenellaceae_RC9_gut_group and Eubacterium_nodatum_group, while increase the abundances of Candidatus_Saccharimonas, Lachnoclostridium, norank_f__Ruminococcaceae, Streptococcus,norank_f__Erysipelotrichaceae,norank_f__norank_o__Clostridia_vadinBB60_group,unclassified_f__Ruminococcaceae, Candidatus_Arthromitus and Novosphingobium in intestine. The results of correlation analysis showed that in hippocampus and cortex, Bifidobacterium and Parabacteroides were positively correlated with serine and glycine, while Streptococcus was negatively correlated with them.Conclusion: These findings evidenced that SV can induce neurotoxicity to promote autism progression by altering the gut microbiota abundances and brain metabolite profiles. This may provide new direction for the management of SV-induced autism.

背景：丙戊酸钠（Sodium valproate，SV）可在动物体内诱发自闭症。本研究旨在探究丙戊酸钠诱导的小鼠自闭症模型中，肠道菌群组成与代谢组紊乱之间的潜在关联。
方法：本研究构建了SV诱导的自闭症小鼠模型。采用旷场实验、高架十字迷宫实验与水迷宫实验，评估小鼠的焦虑样行为与学习记忆能力。通过苏木精-伊红染色观察海马体的组织学变化。整合气相色谱-质谱联用法与16S核糖体RNA基因测序技术，评估SV对自闭症小鼠代谢谱及肠道菌群的影响。基于斯皮尔曼相关系数，计算代谢物与肠道菌群之间的相关性。
结果：旷场、高架十字迷宫及水迷宫实验结果均显示，SV处理会加重小鼠的焦虑样行为，并损害其空间学习与记忆能力。SV可破坏小鼠海马体、皮层、肠道及血清样本中的代谢与生物合成通路，主要涵盖甘氨酸、丝氨酸与苏氨酸代谢、甘油磷脂代谢以及氨酰-tRNA生物合成等通路。SV可降低肠道内Dubosiella、Faecalibaculum、norank_f__norank_o__Clostridia_UCG-014、双歧杆菌属（Bifidobacterium）、Alloprevotella、Prevotellaceae_NK3B31_group、norank_f__Oscillospiraceae、Muribaculum、Erysipelatoclostridium、norank_f__Eubacterium_coprostanoligenes_group、副杆菌属（Parabacteroides）、norank_f__norank_o__Gastranaerophilales、norank_f__Desulfovibrionaceae、norank_f__Mitochondria、Rikenellaceae_RC9_gut_group以及Eubacterium_nodatum_group的丰度，同时上调Candidatus_Saccharimonas、Lachnoclostridium、norank_f__Ruminococcaceae、链球菌属（Streptococcus）、norank_f__Erysipelotrichaceae、norank_f__norank_o__Clostridia_vadinBB60_group、unclassified_f__Ruminococcaceae、Candidatus_Arthromitus以及Novosphingobium的丰度。相关性分析结果显示，在海马体与皮层中，双歧杆菌属与副杆菌属的丰度与丝氨酸、甘氨酸含量呈正相关，而链球菌属则与二者呈负相关。
结论：本研究结果证实，SV可通过改变肠道菌群丰度与脑部代谢谱，诱发神经毒性并促进自闭症进展。该发现可为SV诱导的自闭症的临床管理提供新的研究方向。