甘氨酸对内毒素性肝损害保护作用的实验研究

目的探讨甘氨酸(Gly)对内毒素(LPS)性肝损害的保护机制。方法BABL／c小鼠随机分为两组,LPS组经腹腔注射10 mg／kg的LPS,Gly组在注射相同剂量LPS前3 d开始喂饲含5％Gly的饲料。光镜观察组织病理学改变、免疫组织化学法检测Toll样受体4(TLR4)表达水平；酶联免疫吸附法检测血浆肿瘤坏死因子(TNF)α、白细胞介素10(IL-10)浓度及逆转录聚合酶链反应检测肝组织中TNFα、IL-10及TLR4的mRNA表达水平。结果Gly能明显提高小鼠存活率,肝脏病理损害程度减轻；Gly组TNFα水平显著低于LPS组,差异有统计学意义(1852.80±126.64)pg／ml对(708.83±51.29)pg／ml,P＜0.05]；Gly组IL-10增加且高峰前移,与LPS组比较差异有统计学意义(418.64±38.86)pg／ml对(344.09±31.70)pg／ml,P＜0.05]；Gly组肝组织中TNFα及TLR4表达也明显减弱,IL-10表达明显增强,与LPS组比较差异均有统计学意义分别为TNFα：A值1.59±0.14对0.91±0.11；TLR4：A值0.97±0.12对0.53±0.11；IL-10：A值0.62±0.08对1.06±0.15；P值均＜0.05]。结论Gly能明显减轻LPS所致的肝损害,其机制可能与其下调肝脏各种细胞的TLR4表达,同时上调IL-10的水平有关。

The protection mechanisms of glycine against liver injury induced by lipopolysaccharides

OBJECTIVE: To explore the protective mechanisms of glycine (Gly) on lipopolysaccharides (LPS) induced liver injury. METHODS: BABL/c mice were randomly divided into a LPS group, in which the animals were intraperitoneally injected with 10 mg/kg LPS, and a Gly group, in which the mice were pretreated with a 5% Gly-containing diet for 3 days before receiving the same dose of LPS. The livers of the mice were examined for histopathological changes. The TNF alpha and interleukin-10 (IL-10) levels in the blood plasma were measured using ELISA analysis. The mRNA expression of TNF alpha, IL-10 and Toll-like receptor 4 (TLR4) in hepatic tissues were detected using RT-PCR analysis. Protein expression of TLR4 in livers was detected using immunohistochemistry. RESULTS: The Gly group mice had an improved survival rate and attenuated LPS-induced pathological changes in the liver tissues in comparison with those of the LPS group animals. The TNF alpha levels (1,852.80+/-126.64) pg/ml vs (708.83+/-51.29) pg/ml, P<0.05] in plasma, as well as the expression of TNF alpha (A 1.59+/-0.14 vs. 0.91+/-0.11, P<0.05) and TLR4 (A 0.97+/-0.12 vs. 0.53+/-0.11, P<0.05) mRNA in liver tissues were decreased. However, the levels of plasma interleukin-10 (344.09+/-31.70) pg/ml vs (418.64+/-38.86) pg/ml, P<0.05] were significantly increased and the peaking time left, shifted. CONCLUSIONS: Gly pretreatment could attenuate LPS -induced liver injury in mice, which may be associated with its role in down-regulating TLR4 expression and up-regulating IL-10 production.