以SPF级Balb/c雌性小鼠为实验动物,对其适应性饲养3 d后连续30 d灌喂不同剂量L-茶氨酸,然后腹腔注射产肠毒性大肠杆菌E44813诱导免疫应激,5 h后取样,分析研究了各组小鼠肝脏与脾脏系数,血清谷丙转氨酶（Alanine aminotranferease, ALT）与谷草转氨酶（Aspartate aminotransferase, AST）含量,肝组织匀浆丙二醛（Malondialdehyde, MDA）水平与谷胱甘肽过氧化物酶（Glutathione peroxidase, GSH-PX）、过氧化氢酶（Catalase, CAT）、超氧化物歧化酶（Superoxide Dismutase, SOD）活性,肝组织病理学变化,以及血清中γ-干扰素（γ-Interferon, IFN-γ）、白细胞介素-4（Interleukin-4, IL-4）的表达量,以探明L-茶氨酸对产肠毒性大肠杆菌免疫应激小鼠肝脏的保护作用。结果表明,不同剂量的茶氨酸干预处理均能明显降低由大肠杆菌E44813感染引起的肝脏、脾脏系数的升高,降低血清ALT、AST及肝组织匀浆MDA水平,提高肝组织匀浆SOD、CAT、GSH-PX活性,减少IFN-γ、IL-4表达量,改善肝脏组织病理损伤,其中以300 mg·kg-1剂量组效果最好,说明茶氨酸干预对产肠毒性大肠杆菌诱导的免疫应激小鼠肝损伤具有保护作用,而且可能是通过减少IFN-γ与IL-4的表达、降低炎症反应、提高抗氧化能力等途径达到保护肝脏的作用。
SPF grade Balb/c female mice were used for this experiment. After adaptive feeding for 3 d, the mice were pre-treated orally with different dosages of L-theanine once daily for 30 d. ETEC E44813 intraperitoneal injection was subsequently performed and samples were collected 5h later. The coefficient of liver and spleen, levels of serum alanine aminotranferease (ALT), aspartate aminotransferase (AST) as well as liver homogenate malondialdehyde (MDA), and activities of liver homogenate superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px), pathological changes of liver, expressions of serum γ-Interferon (IFN-γ) and Interleukin-4 (IL-4) were studied to explore the protective effects of L-theanine on liver of ETEC immune mouse model. Results show that pretreatment with L-theanine significantly reduced the increase of liver and spleen coefficient caused by ETEC infection|lowered the levels of serum ALT|AST and liver homogenate MDA|increased the activities of liver homogenate SOD|CAT|GSH-Px|decreased the expressions of serum IFN-γ|IL-4|and improved pathological injury of liver tissue. Therefore|it can be concluded that L-theanine is able to prevent ETEC-induced hepatic injury through depressing IFN-γ, IL-4 and inflammatory reaction and enhancing hepatocyte antioxidant abilities.
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