热暴露不同时期大鼠肝与心肌细胞热休克蛋白70的表达

The expression of heat shock protein 70(HSP70) in the cells of rat liver and cardiac muscle in different heat exposure stages

目的 研究热暴露不同阶段对大鼠肝与心肌细胞热休克蛋白 70 (HSP70 )表达的影响 ,为探讨HSP70在细胞水平的表达机制 ,以及HSP70对热暴露机体的意义提供实验依据。方法 采用人工热气候室 [(34± 1)℃、湿度 6 0 % ],建立热暴露动物模型。SD大鼠 80只分为对照组和热暴露组 ,每组又分为 2、7、14、2 8d 4个时段。取肝与心肌组织做免疫组化SP法染色 ,应用图像分析系统分析组织HSP70含量的变化。结果 在热暴露的 4个时段 ,热暴露组肝 (灰度值分别为 137.0± 5 .1、137.0± 5 .2、137.8± 7.1、139.2± 5 .2 )与心肌 (灰度值分别为 15 6 .1± 4 .4、15 5 .1± 6 .2、15 5 .4± 4 .5、15 6 .2±5 .1)细胞的HSP70表达均明显强于对照组 ,差异有显著性 (P <0 .0 1或P <0 .0 5 ) ;适应时段对HSP70的表达强度无明显影响。热暴露 2d时HSP70在核内表达强于胞浆 ,肝枯否氏细胞HSP70阳性表达率明显高于对照组 ,差异有显著性 (P <0 .0 5 ) ;热暴露 2d与 2 8d时血清中肝与心肌细胞胞内酶浓度明显增高。结论 受热早期机体的重要器官会产生损伤性改变 ;HSP70高表达可作为组织细胞受损伤的标志 ;延长受热时间 ,机体产生热暴露 ,HSP70的高表达在此期热暴露的产生中起到重要作用 ;过长时间受热 ,机体将失去对热的适应 。

Objective To show the changes of heat shock protein 70(HSP70) expression at cellular level in different heat exposure stages and the significance of HSP70 expression in heat exposure organism. Method The heat exposure model was established in rats with artificial hot climatic chamber[(34±1)℃,RH 60%].SD rats were randomly divided into control groups(C) and heat exposure groups(A),and into subgroups including 2,7,14,28 d stages from each one of the groups.The immuno histochemistry was used to detect HSP70 expression in rat liver and cardiac muscle,and photography analytic software was used to analyze HSP70 expression in liver and cardiac cells. Results The expression intensity of HSP70 in heat exposure groups(gray values of liver were 137.0±5.1,137.0±5.2,137.8±7.1,139.2±5.2 respectively;of cardiac muscle 156.1±4.4,155.1±6.2,155.4±4.5,156.2±5.1 respectively) was stronger than that in control groups( P <0.01 or P <0.05) during all stages of the heat exposure;There was no significant difference in expression intensity of HSP70 among various stages of heat exposure;after 2 d of heat exposure,HSP70 expression in cell nuclei of the liver and cardiac muscle cells was stronger than that in cytoplasm in heat exposure group;HSP70 expression in Kupffer's cells of liver was also stronger than that of control( P <0.05),but not on 7,14 and 28 d;the activities of alanine aminotransferase(ALT),aspartate aminotransferase(AST),creatine kinase(CK) and hydroxybutyrate dehydrogenase(HBD) showed an increase on 2 d and 28 d of heat exposure. Conclusion The vital organs would be damaged on 2 d of heat exposure.High expression of HSP70 at this stage may be a marker of cell damage;Increased HSP70 expression on 7～14 d of heat exposure may play an important role in adaptation to heat,while long term(28 d) heat exposure,the protection of HSP70 from tissue damage may not be enough.