血清脂联素和肝细胞凋亡在大鼠非酒精性脂肪性肝病形成过程中的变化

Dynamic changes of serum adiponectin and hepatocellular apoptosis in the rats with non-alcoholic fatty liver disease

目的探讨大鼠非酒精性脂肪性肝病（NAFLD）形成过程中，血清脂联素、肝脏磷酸化caspase3蛋白表达和肝细胞凋亡的变化。方法将24只sD雄性大鼠随机分为4组：正常组6只、模型组（M4组）6只、模型组（M8组）6只和模型组（M12组）6只。予正常组大鼠普通饲料喂养，模型组大鼠高脂饲料喂养。分别于第4周末处死M4组大鼠，第8周末处死M8组大鼠，第12周末处死正常组和M12组大鼠。采用苏木素-伊红（HE）染色观察各组大鼠肝组织病理学改变；酶联免疫吸附试验（ELISA）检测各组大鼠血清脂联素水平；Western blot法检测各组大鼠肝脏磷酸化caspase3蛋白表达；原位末端标记（TUNEL）法检测各组大鼠肝细胞凋亡情况，并对结果进行比较分析。结果肝脏HE染色结果显示，第12周末时模型组大鼠可见肝细胞肿胀明显，细胞质内可见大量的脂肪空泡，少量肝细胞发生坏死。与正常组比较，模型组（M4组）、模型组（M8组）、模型组（M12组）血清脂联素水平呈逐渐下降趋势，两两比较差异均有统计学意义（P〈0．05）。模型组（M8组）和模型组（M12组）大鼠肝脏磷酸化caspase3蛋白表达及肝细胞凋亡逐渐增强，与正常组比较差异有统计学意义（P〈0．05），且模型组（M8组）和模型组（M12组）比较差异也有统计学意义（P〈0．05）。结论在NAFLD发生的中后期，caspase3蛋白磷酸化水平逐渐增强，肝细胞凋亡数目逐渐增多，其机制可能与血清脂联素水平的逐渐下降有关。

Objective To study the dynamic changes of serum adiponectin, phosphorylation caspase 3 protein expression and hepatocellular apoptosis in the course of non-alcoholic fatty liver disease （NAFLD） rats. Methods Twenty four SD male rats were randomly divided into 4 groups ： normal group （ n = 6 ）, model group M4 （ n = 6 ）, model group M8 （ n = 6 ） and model group M12 （ n = 6 ）. Normal group was given ordinary feed and NAFLD model groups were given high-fat feed. Rats in model group M4 were sacrificed at the end of week 4, rats in model group M8 were killed at the end of week 8, and rats in normal group and model group M12 were sacrificed at the end of week 12. Hematoxylin-eosin （ HE ） staining was used for tissue histopathological examinations. Serum adiponectin was detected by enzyme linked immunosorbent（ ELISA）. Protein expression of phosphorylation caspase 3 was examined by Western blotting. Hepatocellular apoptosis were determined by TdT-mediated dUTP nick end labeling （TUNEL）. Results HE staining showed that the rat liver cell swelling was obvious at the end of week 12, a large number of fat vacuoles were found in the cytoplasm, and a small amount of liver cells were necrotic. Compared with the normal group, the serum adiponectin in model group rats gradually weakened in model group M4 ,model group M8 and model group M12 and there were significant differences between each two groups（ P 〈 0.05 ）. Protein expression of phosphorylation caspase 3 and hepatocellular apoptosis in model group M8 and model group M12 gradually strengthened in comparison with that in normal group （ P 〈 0. 05 ） and there were significant differences between each two groups （ P 〈 0. 05 ）. Conclusion In the middle and late periods of NAFLD, the protein expression of phosphorylation caspase 3 gradually strengthen and the number of hepatoeellular apoptosis is gradually increasing. The mechanism may be related to the gradual decline of serum adiponectin levels.