核因子κB和转化生长因子β1在银杏叶提取物抗肝纤维化中的作用

目的观察银杏叶提取物（EGB）对大鼠肝纤维化的防治效果，探讨EGB抗肝纤维化的机制。方法采用四氯化碳诱导大鼠肝纤维化。EGB各组四氯化碳处理同模型组，另分别给予0．25、0．5、1．0g／kg EGB灌胃。8周末检测其肝功能以及血清透明质酸和层黏连蛋白。取肝组织进行氧化应激测定，免疫组织化学法检测核因子KB（NF-kB）P65和α-平滑且儿肌动蛋白的表达，逆转录聚合酶链反应法检测转化生长因子β1（TGF-β1）和Ⅰ型胶原mRNA的表达，凝胶电泳迁移率分析检测NF-kB的活性，并进行病理组织学检查。结果EGB组肝纤维化分级评分、肝功能以及血清透明质酸和层黏连蛋白较模型组明显改善；EGB能抑制氧化应激、肝星状细胞的活化、NF-kB P65的表达以及NF-kB活性。此外，EGB还可减低TGFβ1和1型胶原mRNA的表达。结论EGB可能通过抑制氧化应激和TGFβ1的表达，减弱NF-kB诱导的肝星状细胞活化，从而阻止四氯化碳诱导的大鼠肝纤维化的发生发展。

Effects of nuclear factor κB and transforming growth factor β 1 in the anti-liver fibrosis process using Ginkgo biloba extract

OBJECTIVE: To evaluate the effects of Ginkgo biloba extract (EGB) on CCl(4)-induced liver fibrosis and to investigate the underlying mechanisms. METHODS: Rats were divided into the following groups: normal control group, CCl(4) model group, low dose EGB group, moderate dose EGB group and high dose EGB group. The rat liver fibrosis model was induced by intraperitoneal injection of CCl(4) twice a week for 8 weeks. The model rats of the three EGB treated groups were given 0.25 g/kg, 0.5 g/kg, 1.0 g/kg of EGB by stomach tubes every day. At the end of the eighth week, the blood and liver specimens were obtained. The expressions of nuclear factor kappaB (NF-kappaB) P65, and alpha-smooth muscle actin (alpha-SMA) were detected by immunohistochemistry. Radioimmunoassay was exploited to evaluate serum hyaluronic acid (HA) and laminin (LN) levels. Electrophoretic mobility shift assay (EMSA) was used to confirm the nuclear translocation activity of NF-kappaB in liver tissues. The mRNA expression of transforming growth factor-beta1 (TGFbeta1) and collagen I was determined by RT-PCR. Malondialdehyde (MDA), superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) in liver tissues and alanine aminotransferase (ALT) and aspartate aminotransferase (AST) in the sera were also examined. RESULTS: CCl(4) administration induced liver fibrosis, which was inhibited by EGB in a dose-dependent manner. The histopathologic scores of liver fibrosis, the levels of serum ALT, AST, HA and LN were significantly lower in the rats treated with EGB compared with those not treated (P <0.01 or P <0.05). SOD and GSH-Px activities were notably elevated and MDA content was significantly lower in the rats treated with EGB (P <0.01 or P <0.05), indicating reduced oxidative stress. Immunohistochemical staining demonstrated inhibition of hepatic stellate cell (HSC) activation (in terms of alpha-SMA expression) and NF-kappaB P65 expression in the livers of the EGB-treated rats. As determined by EMSA and RT-PCR, activation of NF-kappaB, the mRNA expression of TGFbeta1 and collagen I were significantly higher in model group rats, but obviously lower in EGB treated rats. CONCLUSION: EGB is able to ameliorate liver injury and prevent rats from CCl(4)-induced liver fibrosis by suppressing oxidative stress. This process may be related to inhibiting the expression of TGFbeta1 and the induction of NF-kappaB on HSC activation.