甘氨酸对内毒素性肝损害保护作用的实验研究

The protection mechanisms of glycine against liver injury induced by lipopolysaccharides

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。

Objective To explore the protective mechanisms ofglycine （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 α and interleukin- 10 （IL- 10） levels in the blood plasma were measured using ELISA analysis. The mRNA expression of TNF α, 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 tale and attenuated LPS-induced pathological changes in the liver tissues in comparison with those of the LPS group animals. The TNF α 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 α （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 downregulating TLR4 expression and up-regulating IL-10 production.