The expression of heat shock protein 70 (HSP70) in the cells of rat liver and cardiac muscle in different heat exposure stages / 中华劳动卫生职业病杂志

ABSTRACT

<p><b>OBJECTIVE</b>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.</p><p><b>METHOD</b>The heat exposure model was established in rats with artificial hot climatic chamber[34 +/- 1) degree C, 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.</p><p><b>RESULTS</b>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.</p><p><b>CONCLUSION</b>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.</p>