急性肝损伤大鼠肝脏Fas和FasL的表达及其意义

目的 研究急性肝损伤大鼠肝脏Fas和FasL的表达情况，探讨细胞凋亡在中毒性肝损伤发病中的地位及其意义。方法 健康雄性Wistar大鼠35只，随机分为正常对照组和实验组，实验组再分为3、9、16、24、36和48h6个亚组，每组5只。制备四氯化碳中毒性肝损伤动物模型，采用苏木素-伊红（HE）染色，光镜下观察肝组织损伤情况，采用免疫组化方法测定不同时间点肝组织Fas和FasL的表达，采用末端脱氧核苷酸转移酶介导的dUTP缺口末端标记法（TUNEL）观察肝细胞凋亡情况。同时测定各时间点血清丙氨酸转氨酶（ALT）、天冬氨酸转氨酶（AST）和肝组织超氧化物歧化酶（SOD）活性、肝组织丙二醛（MDA）含量变化。结果 Fas和FasL在正常大鼠肝细胞中未见表达，实验组3h后即开始有明显表达，并随时间延长表达相应增强；病理学和TUNEL检测结果均显示肝脏有严重损伤，大量肝细胞发生凋亡。大鼠染毒后血清ALT、AST活性和肝组织MDA含量明显升高，肝组织SOD活性显著降低，与正常对照组比较差异均十分显著（P〈O．05或P〈O．01）。结论 大鼠急性肝损伤时Fas和FasL表达显著增加，和肝细胞凋亡变化相一致，提示Fas／Fasl。系统及介导的细胞凋亡反应在中毒性肝损伤的发病机制中可能占有重要地位。

Expression of Fas antigen and Fas ligand in acute liver injury induced by carbon tetrachloride in rat

Objective To investigate the dynamics of expression of Fas antigen and Fas ligand (FasL) in a rat model of carbon tetrachloride-induced acute liver injury , and explore the role of apoptosis in liver injury . Methods Thirty-five healthy male Wistar rats were randomly divided into normal control group and experiment group, and the latter group was divided into six subgroups: 3, 9, 16, 24, 36 and 48 hours groups with 5 rats in each group. The liver injury was induced by carbon tetrachloride. Sections of liver tissue were stained with hematoxylin and eosin and observed under optical microscope. Fas antigen and FasL in rat liver were determined at different time points with immunohistochemical method. Hepatocytes apoptosis were observed with terminal deoxynucleotidyl-transferase mediated dUTP-biotin nick end labeling (TUNEL) method. Superoxide dismutase (SOD) activity and malondialdehyde (MDA) concentration in the liver tissues were analyzed at the same time point. Serum aspartate aminotransferase (ALT) and alanine aminotransferase (AST) levels were also determined. Results Fas antigen and FasL were expressed in the liver tissues of control rats. Following carbon tetrachloride challenge, severe liver injury took place in rats as revealed under microscope and a large amount of hepatocytes apoptosis was found. Hepatic Fas and FasL expression were both increased markedly from 3 to 48 hours after carbon tetrachloride challenge in experiment group. Liver MDA concentration and serum ALT and AST were elevated significantly, while SOD activity decreased remarkably in the experiment group compared with control group (P<0.05 or P<0.01). Conclusion Expression of Fas/FasL is remarkably induced in acute liver injury and accords with the changes of hepatocytes apoposis, which suggests that apoptosis mediated by Fas/FasL may play an important role in the pathogenesis of acute liver injury.