低氧预适应对自体肝移植大鼠Bcl-2蛋白表达的影响及其意义

Impact and significance of hypoxia preconditioning on the expression of Bcl-2 protein in orthotopic liver autotransplantation in rats

目的探讨低氧预适应(HP)对大鼠自体肝移植后Bcl-2蛋白表达的影响及其意义。方法采用改良的自体肝移植模型研究缺血再灌注损伤(IRI),将SD大鼠随机分为正常对照(NC)、自体移植(AT)和AT+低氧预适应(HP)3组,每组24只。HP组术前用8%氮氧混合气体处理90 min,分别于术后1,6,24 h处死大鼠取肝脏标本,抽血检测肝功能,免疫组化方法测定大鼠肝组织Bcl-2蛋白的表达,并在光镜和透射电镜下观察各组肝细胞形态学改变、线粒体损伤程度等。结果HP组血清ALT和AST水平显著低于AT组,差异有统计学意义(P<0.05);HP组各时段的肝功能明显优于AT组;HP组各时段Bcl-2蛋白明显高于AT组,差异有统计学意义(P<0.05)。光镜下AT组的肝组织肿胀明显,而HP组无明显改变。透射电镜下AT组肝细胞出现典型的凋亡征象,而HP组肝细胞无明显凋亡形态;定量分析线粒体的面积、周长及直径均与AT组差异有统计学意义(P<0.05),HP组线粒体损伤程度较AT组为轻。结论HP对移植所导致的肝细胞凋亡有明显的抑制作用;它可能系通过上调Bcl-2蛋白的表达、减轻线粒体损伤途径而发挥其保护作用。

Objective To explore the impact and significance of hypoxia preconditioning on the expression of Bcl-2 protein after orthotopic liver autotransplantation in rats. Methods A modified orthopotic liver autotransplantation model was used to study the ischemia reperfusion injury in liver transplantation. Sprague-Dawley rats were randomly divided into the following three groups ： normal control （ NC ） group, autotransplantation （AT） group, and hypoxia preconditioning （HP） group, there were twenty four rats in each group. HP Group was given an 8% oxygen -mixed gas for 90 minutes before the operation. At 1, 6, and 24 hours after the operation, the rats were killed and the following tests were conducted： （1）Liver tissue was sampled to observe the expression of Bcl-2 protein ; （ 2 ） blood was drawn to conduet a chemical examination; （3） morphology was observed by light microscopy and transmission electron microscopy; （4） chondrosomes were quantitatively analysed by a MiVnt image analysis system. Results The serum levels of ALT and AST in HP group were significantly lower than that of AT group （ P 〈 0.05 ） at 1 , 6 and 24 hours after the orthopotic liver autotransplantation. The expression of Bcl-2 protein was increased significantly （ P 〈 0.05 ） in HP group at each measurement point. The hepatic tissues in HP group were less swollen than AT group under light microscopy. Hepatic cells in AT group showed typical apoptosis signs under transmission electron microscopy （ TEM ） , but no apoptosis was found in HP group. The appearance of hepatocytes in HP group was much better than AT group, and the areas, perimeters and diameters of chondrosomes in group HP under TEM were much smaller than that in AT group （ P 〈 0.05 ）. Conclusions HP has marked inhibition to apoptosis by up-regulating the expression of Bcl-2 protein and protection to chondrosomes after an orthopotic liver autotransplantation.