Jiangsu Province Key Laboratory for Molecular and Medicine Biotechnology, College of Life Science, Nanjing Normal University, Nanjing 210046, People's Republic of China.
Food Chem Toxicol. 2012 Feb;50(2):363-72. doi: 10.1016/j.fct.2011.10.036. Epub 2011 Oct 14.
l-Theanine is a unique amino acid in green tea. We here evaluated the protective effects of l-theanine on ethanol-induced liver injury in vitro and in vivo. Our results revealed that l-theanine significantly protected hepatocytes against ethanol-induced cell cytotoxicity which displayed by decrease of viability and increase of LDH and AST. Furthermore, the experiments of DAPI staining, pro-caspase3 level and PARP cleavage determination indicated that l-theanine inhibited ethanol-induced L02 cell apoptosis. Mechanically, l-theanine inhibited loss of mitochondrial membrane potential and prevented cytochrome c release from mitochondria in ethanol-treated L02 cells. l-Theanine also prevented ethanol-triggered ROS and MDA generation in L02 cells. l-Theanine restored the antioxidant capability of hepatocytes including GSH content and SOD activity which were reduced by ethanol. In vivo experiments showed that l-theanine significantly inhibited ethanol-stimulated the increase of ALT, AST, TG and MDA in mice. Histopathological examination demonstrated that l-theanine pretreated to mice apparently diminished ethanol-induced fat droplets. In accordance with the in vitro study, l-theanine significantly inhibited ethanol-induced reduction of mouse antioxidant capability which included the activities of SOD, CAT and GR, and level of GSH. These results indicated that l-theanine prevented ethanol-induced liver injury through enhancing hepatocyte antioxidant abilities.
L-茶氨酸是绿茶中一种独特的氨基酸。我们在这里评估了 L-茶氨酸对体外和体内乙醇诱导的肝损伤的保护作用。我们的结果表明，L-茶氨酸显著保护肝细胞免受乙醇诱导的细胞毒性，表现为活力下降和 LDH 和 AST 增加。此外，DAPI 染色、原半胱天冬酶 3 水平和 PARP 切割测定实验表明，L-茶氨酸抑制了乙醇诱导的 L02 细胞凋亡。在机制上，L-茶氨酸抑制了乙醇处理的 L02 细胞中线粒体膜电位的丧失，并防止细胞色素 c 从线粒体释放。L-茶氨酸还防止了乙醇诱导的 L02 细胞中 ROS 和 MDA 的产生。L-茶氨酸恢复了乙醇降低的肝细胞抗氧化能力，包括 GSH 含量和 SOD 活性。体内实验表明，L-茶氨酸显著抑制了乙醇刺激的小鼠 ALT、AST、TG 和 MDA 的增加。组织病理学检查表明，L-茶氨酸预处理小鼠明显减轻了乙醇诱导的脂肪滴。与体外研究一致，L-茶氨酸显著抑制了乙醇诱导的小鼠抗氧化能力下降，包括 SOD、CAT 和 GR 的活性以及 GSH 水平。这些结果表明，L-茶氨酸通过增强肝细胞抗氧化能力来预防乙醇诱导的肝损伤。
