促红细胞生成素对脂多糖所致大鼠肝脏损伤的保护作用

目的:利用内毒素（LPS）建立大鼠肝脏损伤模型，探讨促红细胞生成素（EPO）对肝脏损伤的保护作用及可能机制，为防治LPS引起的肝脏损伤提供依据。方法：将40只成年Wistar大鼠随机分成空白对照组、EPO对照组、LPS组和LPS+EPO组，每组10只。LPS组、LPS+EPO组大鼠尾静脉注射LPS（10 mg/kg）建立肝损伤模型，对照组大鼠给予同等量生理盐水， 30 min后，LPS+EPO组和EPO对照组给予rhEPO(5 000 U/kg)　经尾静脉注射，其余2组大鼠给予生理盐水。在LPS注射后6和24 h每组分别处死5只大鼠，生化分析仪测定大鼠血清谷草转氨酶（AST）和谷丙转氨酶（ALT）水平，放射免疫法测定大鼠血清肿瘤坏死因子-α(TNF-α）水平。在第24小时处死其余大鼠，制备肝组织切片，HE染色后光镜下观察大鼠肝脏组织病理结构改变，透射电子显微镜观察大鼠肝脏超微结构改变。应用免疫印记方法检测大鼠丙氨酸转氨酶（AKT）、磷酸化丙氨酸转氨酶（P-AKT）和核因子-κB （NF-κB）表达水平。结果：与对照组比较，LPS、LPS+EPO组大鼠血清ALT、AST和TNF-α水平升高（P<0.05）；LPS组升高显著多于LPS+EPO组（P<0.05）。与对照组比较，LPS组AKT和NF -κB表达增强；与LPS组比较，LPS+EPO组P-AKT及NF -κB表达下降。光镜下可见LPS组肝脏组织炎症细胞浸润，肝细胞肿胀坏死；LPS+EPO组亦可见炎症细胞浸润、肝细胞肿胀，但较LPS组轻微。电镜下LPS组肝细胞线粒体肿胀、微绒毛消失、肝细胞空泡化；LPS+EPO组细胞损伤表现相似，但较LPS组轻微。结论：EPO可通过减轻炎症反应、减轻组织退变有效地保护LPS所致的肝损伤，其机制可能与磷脂酰肌醇3-激酶（PI3K）/ AKT/ NF -κB信号通路有关。

Protective effect of erythropoietin on lipopolysaccharide -induced liver injury in rats

Objective To establish liver injury rat models with lipopolysaccharide(LPS) and investigate the protective effect of erythropoietin(EPO) on liver injury and its possible mechanism,and to provid evidence for the treatment of liver injury induced by LPS.Methods 40 adult Wistar rats were randomly divided into blank control group(n=10),EPO control group(n=10),LPS group(n=10) and LPS + EPO group(n=10).The liver injury rat models were established by injecting 10 mg·kg-1 LPS into the tail vein of rats in LPS and LPS+EPO groups,while the rats in control group received the same amount of saline.30 min later,the rats in LPS + EPO group and EPO control group were given rhEPO(5 000 U·kg-1) via the tail vein injection,while the rats in the other two groups were given saline.5 rats were killed in each group after 6 and 24 h,and the levels of serum enzymes including aspartate aminotransferase(AST) and alanine transarninase(ALT) were evaluated by biochemical analysis and the tumor necrosis factor-α(TNF-α) was determined by immunoradiometric assay.The other rats were killed at 24 h,the liver tissue sections were underwent histological examination by hematoxylin and eosin(HE) staining under light microscope.The ultrastructure changes of liver tissues were assessed by transmission electron microscope(TEM).The expressions of AKT,P-AKT and NF-κB were determined by Western blotting.Results Compared with control group,the levels of ALT,AST,and TNF-α in LPS and LPS + EPO groups were elevated(P<0.05);the levels in LPS group were increased significantly compared with LPS+EPO group(P<0.05).Compared with control group,the expressions of AKT,NF-κB in LPS group were enhanced;compared with LPS group,the expressions of P-AKT and NF-κB in LPS+EPO group were decreased.The light microscope results showed the inflammatory cells presented infiltration and swelling or necrosis of liver cells in the liver tissue in LPS group,and the inflammatory cell infiltration and hepatocyte swelling were also visible in LPS+EPO group,but much slightly.The electron microscope results showed that the hepatocyte mitochondrial presented swelling,disappearance of microvilli,vacuolization of liver cells in LPS group,and the similar injury was visible in LPS+EPOgroup,but much slightly.Conclusion EPO can protect the LPS-induced liver injury by reducing inflammatory and tissue degeneration which may be related with phosphatidylinositol 3-kinase(PI3K)/AKT/NF-κB signal pathway.