慢性热应激诱导大口黑鲈肝脏线粒体功能障碍及糖脂异常沉积

Chronic heat stress induces hepatic glycolipid abnormal deposition and mitochondrial dysfunction in Micropterus salmoides

  • 摘要:
    目的 为探究慢性热应激(CHS)对鱼类糖脂代谢及线粒体稳态的影响。
    方法 将240尾均重(12.04±0.15) g的大口黑鲈幼鱼随机分为2组(每组4个重复),在(27.0±0.5) ℃(Control组)及(33.0±0.5) ℃ (Heat组) 恒温养殖桶中用商品料养殖8周后取样,并利用转录组测序、qPCR、TEM、油红O和PAS染色等方法加以分析。
    结果 Heat组大口黑鲈肝脏糖代谢基因(IRAIRBIRS1、PEPCKGSK3βAKT1及PBP1)表达显著下调,脂代谢相关基因中FASLPLHSL表达显著下调,而CPT-1、FFARACC及ATGL表达显著上调。线粒体稳态相关基因中SIRT1及AMPKα表达显著上调,PGC-1αERRαTFAM7、OAP1、DRP1、P62、LC3及MFN1则显著下调。Heat组大口黑鲈肝脏IκBβP65、IκκβIL-8表达量显著下调。此外,Heat组大口黑鲈肝脏糖原及脂质异常蓄积,线粒体结构损伤且密度显著下降。肝脏转录组测序发现,差异基因主要富集于C型凝集素受体信号通路、细胞因子-细胞因子受体相互作用、肌动蛋白细胞骨架调控、碳代谢及糖酵解/糖异生信号通路。
    结论 CHS破坏线粒体动力学稳态,诱发线粒体功能障碍及能量代谢失衡。CHS扰乱大口黑鲈糖脂代谢,诱导肝脏糖原及脂肪沉积。CHS对能量代谢稳态的抑制效应破坏了大口黑鲈肝脏免疫功能。本研究结果既可为解析鱼类肝脏慢性热应激损伤提供数据支撑,也可为开发改善鱼类肝脏慢性热应激损伤的饮食策略提供思路。

     

    Abstract: With worsening global greenhouse effect, aquaculture faces growing high-temperature threats. Mass mortality events of farmed fish induced by chronic heat stress (CHS) have become common. Therefore, more attention should be paid to CHS. To investigate the effects of CHS on carbohydrate and lipid metabolism, as well as mitochondrial homeostasis in fish, a total of 240 juvenile Micropterus salmoides with an average body weight of (12.04±0.15) g were randomly divided into two groups, each consisting of four replicates. The fish were cultured in thermostatically controlled aquaculture tanks at (27.0±0.5) ℃ (Control group) and (33.0±0.5) ℃ (Heat group) for 8 weeks, using commercial feed. The results demonstrated that in the Heat group, the hepatic expression levels of glucose metabolism-related genes, including IRA, IRB, IRS1, PEPCK, GSK3β, AKT1, and PBP1, were significantly downregulated. Among lipid metabolism-related genes, FAS, LPL, and HSL were significant downregulated, whereas CPT-1, FFAR, ACC, and ATGL were marked upregulated. Among genes related to mitochondrial homeostasis, SIRT1 and AMPKα were significantly upregulated, while PGC-1α, ERRα, TFAM7, OAP1, DRP1, P62, LC3, and MFN1 also showed marked downregulation. In addition, the expression levels of IκBβ, P65, Iκκβ, and IL-8 were all significantly downregulated in the Heat group. Furthermore, the Heat group exhibited abnormal glycogen accumulation and lipid deposition in the liver, accompanied by mitochondrial structural damage and a significant decrease in mitochondrial density. Liver transcriptome sequencing revealed that differentially expressed genes were primarily enriched in the C-type lectin receptor signaling pathway, cytokine-cytokine receptor interaction, actin cytoskeleton regulation, carbon metabolism, and glycolysis/gluconeogenesis signaling pathway. In summary, CHS disrupts mitochondrial dynamics homeostasis, induces mitochondrial dysfunction and energy metabolic imbalance in M. salmoides. Additionally, CHS disrupts hepatic carbohydrate and lipid metabolism, leading to abnormal accumulation of glycogen and lipids in the liver. The suppression of energy metabolic homeostasis by CHS further impairs hepatic immune function in this species. The findings of this study not only provide data supporting the elucidation of CHS-induced hepatic metabolic disorders in fish but also offer insights for developing dietary strategies to mitigate such damage in fish livers.

     

/

返回文章
返回