高原高海拔环境暴露对大鼠肝脏功能的影响及其机制

Effects and mechanism of exposure to high altitude environment on liver function in rats

目的 初步观察高原高海拔环境暴露对大鼠肝脏功能的影响及其可能机制。方法 健康雄性SD大鼠48只,随机分为平原组、高原1个月组、高原2个月组与高原4个月组,每组12只。平原组于海拔约500 m处喂养1个月,各高原暴露组于高原环境模拟舱(5000 m)中分别喂养1、2和4个月,造模结束时采集血清和肝组织。采用全自动生化仪测定血清谷丙转氨酶(ALT)、谷草转氨酶(AST)、总胆红素(TBIL)水平,HE染色观察肝组织病理学变化,ELISA法检测肝组织中还原型谷胱甘肽(GSH)、超氧化物歧化酶(SOD)水平,透射电镜观察肝细胞超微结构改变,Western blotting检测自噬相关蛋白Beclin-1、LC3-Ⅱ的相对表达量。结果 与平原组比较,高原2个月组血清ALT、AST、TBIL水平明显升高(P<0.05);与高原2个月组比较,高原4个月组血清ALT、AST、TBIL水平明显降低(P<0.05)。HE染色显示,各组肝组织小叶结构清晰,无明显炎性浸润,也无明显的细胞水肿或坏死。透射电镜观察显示,高原1个月组和高原2个月组肝细胞中自噬小体数目明显多于平原组,高原4个月组肝细胞中自噬小体数目较高原2个月组明显减少。Western blotting和ELISA检测结果显示,高原1个月组和高原2个月组肝组织中Beclin-1、LC3-Ⅱ蛋白相对表达量明显高于平原组(P<0.05),GSH和SOD水平明显低于平原组(P<0.05);高原4个月组肝组织中Beclin-1、LC3-Ⅱ蛋白相对表达量明显低于高原2个月组(P<0.05),GSH和SOD水平明显高于高原2个月组(P<0.05),且与平原组差异无统计学意义(P>0.05)。结论 在适应低压低氧环境的过程中,大鼠肝功能指标出现异常改变,其机制可能与肝脏氧化应激水平改变及肝细胞自噬有关。

Objective To observe the effects and possible mechanism of exposure to high altitude environment on liver function in rats.Methods Forty-eight healthy male SD rats were randomly divided into plain group,plateau 1-month group,plateau 2-month group and plateau 4-month group (12 each).Rats in plain group were fed at an altitude of about 500 m for1 month,and in the plateau groups were fed in a simulated chamber of high altitude (5000 m) for 1 month,2 months and 4 months,respectively.Serum and liver tissue were collected at the end of the model.The contents of serum alanine aminotransferase (ALT),aspartate aminotransferase (AST) and total bilirubin (TBIL) were measured with automatic biochemical analyzer.The pathological morphology of liver tissue was observed by HE staining.The levels of reduced glutathione (GSH) and superoxide dismutase (SOD) in liver tissue were measured by ELISA.The ultra structural changes of hepatocytes were observed by transmission electron microscope.The relative expressions of autophagy associated proteins LC3-Ⅱ and Beclin-1 were determined by Western blotting.Results Compared with the plain group,the serum levels of ALT,AST and TBIL significantly increased in the plateau 2-month group (P<0.05);compared with the plateau 2-month group,the serum levels of ALT,AST and TBIL significantly decreased in the plateau 4-month group (P<0.05).HE staining showed that the lobule structure of liver tissue in each group was clear without obvious inflammatory infiltration,cell edema or necrosis.The results of transmission electron microscope showed that the number of autophagy corpuscles in hepatocytes of rats was significantly higher in plateau 1-month group and plateau 2-month group than in plain group,and was significantly lower in plateau 4-month group than in plateau 2-month group.Western blotting and ELISA results showed that the relative expression levels of LC3-Ⅱ and Beclin-1 protein increased significantly,while the GSH and SOD levels decreased significantly in plateau 1-month group and plateau 2-month group than in the plain group (P<0.05);the relative expression levels of LC3-Ⅱ and Beclin-1 protein significantly decreased,and the levels of GSH and SOD significantly increased in plateau 4-month group than in plateau 2-month group (P<0.05),but no significant differences compared with those in plain group (P>0.05).Conclusion In the process of adapting to hypobaric and hypoxic environment,abnormal changes of liver function indexes of rats occurred,the mechanism may be related to the changes of oxidative stress level and autophagy of hepatocytes.