Dong Minjian, Yi Qingqing, Shen Danjie, Yan Jiapin, Jiang Haowei, Xie Jiaojiao, Zhao Liangcai, Gao Hongchang
School of Pharmaceutical Sciences, Wenzhou Medical University, Wenzhou 325035, Zhejiang, China.
Oujiang Laboratory (Zhejiang Lab for Regenerative Medicine, Vision and Brain Health), Key Laboratory of Alzheimer's Disease of Zhejiang Province, Wenzhou Medical University, Wenzhou 325035, China.
Comput Struct Biotechnol J. 2022 Jul 25;20:3935-3945. doi: 10.1016/j.csbj.2022.07.034. eCollection 2022.
This study aimed to explore whether chronic l-lactate exposure could affect the peripheral tissues of mice and to determine the underlying pathogenesis. Herein, male C57BL/6 mice were divided into control and l-lactate groups. After l-lactate treatment for eight weeks (1 g/kg), metabolic changes in liver, kidney, muscle, and serum samples were determined by H nuclear magnetic resonance (H NMR)-based metabolomics. Additionally, organ function was evaluated by serum biochemical and histopathological examinations. Reactive oxygen species (ROS) levels were measured using dihydroethidium staining; levels of signals involved in lactate metabolism and ROS-related pathways were detected using western blotting or polymerase chain reaction. Apoptosis was detected by TUNEL-fluorescence staining. Metabolomic analysis revealed that l-lactate mice showed decreased levels of glutathione (GSH), taurine, ATP, and increased glucose content, compared to control mice. Furthermore, l-lactate mice presented significantly higher serum levels of alanine aminotransferase and aspartate aminotransferase and increased glycogen content in hepatic tissues, compared to control mice. l-lactate mice also had a greater number of apoptotic nuclei in the livers than controls. Moreover, l-lactate exposure reduced mRNA and protein levels of superoxide dismutase-2 and c-glutamylcysteine ligase, elevated levels of cytochrome P450 2E1 and NADPH oxidase-2, and increased the protein expressions of LDHB, Bax/Bcl-2, cleaved caspase-3, and sirtuin-1 in hepatic tissues. Together, these results indicate that chronic l-lactate exposure increases oxidative stress and apoptosis in hepatocytes via upregulation of Bax/Bcl-2 expression and the consequent mitochondrial cytochrome-C release and caspase-3 activation, which contributes to the pathogenesis of hepatic dysfunction.
本研究旨在探讨长期暴露于L-乳酸是否会影响小鼠的外周组织，并确定其潜在的发病机制。在此，将雄性C57BL/6小鼠分为对照组和L-乳酸组。在给予L-乳酸处理8周（1 g/kg）后，通过基于氢核磁共振（H NMR）的代谢组学方法测定肝脏、肾脏、肌肉和血清样本中的代谢变化。此外，通过血清生化和组织病理学检查评估器官功能。使用二氢乙锭染色法测量活性氧（ROS）水平；使用蛋白质免疫印迹法或聚合酶链反应检测参与乳酸代谢和ROS相关途径的信号水平。通过TUNEL荧光染色检测细胞凋亡。代谢组学分析显示，与对照小鼠相比，L-乳酸处理的小鼠谷胱甘肽（GSH）、牛磺酸、ATP水平降低，葡萄糖含量增加。此外，与对照小鼠相比，L-乳酸处理的小鼠血清丙氨酸氨基转移酶和天冬氨酸氨基转移酶水平显著升高，肝组织中糖原含量增加。L-乳酸处理的小鼠肝脏中的凋亡细胞核数量也比对照组更多。此外，暴露于L-乳酸会降低肝脏组织中超氧化物歧化酶-2和γ-谷氨酰半胱氨酸连接酶的mRNA和蛋白质水平，升高细胞色素P450 2E1和NADPH氧化酶-2的水平，并增加肝脏组织中LDHB、Bax/Bcl-2、裂解的半胱天冬酶-3和沉默信息调节因子1的蛋白质表达。总之，这些结果表明，长期暴露于L-乳酸会通过上调Bax/Bcl-2表达以及随后的线粒体细胞色素C释放和半胱天冬酶-3激活增加肝细胞中的氧化应激和细胞凋亡，这有助于肝功能障碍的发病机制。
