The gut-brain axis plays a major role in multiple metabolic regulation processes, but studies regarding its responses to environmental stress in fish are still limited. In this study, we performed transcriptome sequencing analysis and enzyme-linked immunosorbent assay (ELISA) in yellowfin seabream (Acanthopagrus latus) exposed to environments with different water salinity (freshwater: 0 ppt; low-saline water: 3 ppt; brackish water: 6 ppt). According to transcriptome analysis, 707 and 1477 genes were identified as differentially expressed genes (DEGs) between freshwater and brackish water treatments in the brain and gut, respectively. Brain DEGs were significantly enriched into a set of Gene Ontology terms and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways associated with signal transduction, most of which were downregulated. Gut DEGs were enriched into a neurotransmission-relevant KEGG pathway tryptophan metabolism, and the downregulated DEGs were enriched into the KEGG pathway focal adhesion. ELISA demonstrated significant physiological responses of the brain and gut across treatments, as determined by the concentrations of tight junction protein ZO-2, interleukin 1β, and serotonin. Under hypoosmotic stress, the functions of the gut-brain axis are altered via impairment of intestinal barrier integrity, by disturbance of gut-brain neurotransmission, and through tissue-damaging inflammatory reactions. Our work identified candidate genes which showed significantly differential expression in the gut-brain axis when yellowfin seabream encountered hypoosmotic stress, which could shed lights on the understanding of the potential osmotic regulation mechanisms of the gut-brain axis in teleost.

肠脑轴在多种代谢调节过程中发挥着重要作用，但关于其对鱼类环境应激反应的研究仍然有限。在这项研究中，我们对黄鳍鲷 ( Acanthopagrus latus ) 进行了转录组测序分析和酶联免疫吸附试验 (ELISA)) 暴露于不同水盐度的环境（淡水：0 ppt；低盐水：3 ppt；微咸水：6 ppt）。根据转录组分析，707 和 1477 个基因分别被鉴定为大脑和肠道中淡水和微咸水处理之间的差异表达基因 (DEG)。脑 DEG 显着富集到一组与信号转导相关的基因本体术语和京都基因和基因组百科全书 (KEGG) 通路，其中大部分被下调。肠道 DEGs 富集到与神经传递相关的 KEGG 通路色氨酸代谢中，下调的 DEGs 富集到 KEGG 通路粘着斑中。ELISA 显示了大脑和肠道在治疗过程中的显着生理反应，由紧密连接蛋白 ZO-2、白细胞介素 1β 和血清素的浓度决定。在低渗压力下，肠-脑轴的功能通过肠道屏障完整性受损、肠-脑神经传递障碍和组织损伤性炎症反应而改变。我们的工作确定了当黄鳍鲷遇到低渗胁迫时在肠-脑轴中表现出显着差异表达的候选基因，这可以阐明对硬骨鱼肠-脑轴潜在渗透调节机制的理解。并通过破坏组织的炎症反应。我们的工作确定了当黄鳍鲷遇到低渗胁迫时在肠-脑轴中表现出显着差异表达的候选基因，这可以阐明对硬骨鱼肠-脑轴潜在渗透调节机制的理解。并通过破坏组织的炎症反应。我们的工作确定了当黄鳍鲷遇到低渗胁迫时在肠-脑轴中表现出显着差异表达的候选基因，这可以阐明对硬骨鱼肠-脑轴潜在渗透调节机制的理解。