Effect of ischemic postconditioning on expression of heat shock proteins after kidney ischemia/reperfusion injury in rats

Obiective To investigate the effect of ischemic postconditioning on expression of heat shock protein (HSP)70,HSP27 and heme oxygenase-1 (HO-1) and the role of which in reduction renal ischemia/reperfusion injury (I/RI) in rats.Methods One hundred forty healthy male SD rats weighing 250 g-280 g were randomly divided into 4 groups (n=35):group Ⅰ sham operation group (group S) ; group ]Ⅱ I/R; group Ⅲ IPo; group Ⅳ quercetin+IPo group (group Q +IPo).The rats were anesthetized with intraperitoneal (IP) chloral hydrate 300 mg/kg.Bilateral kidneys were exposed and their pedicels were clamped for 45 min followed by reperfusion in group Ⅱ -Ⅳ.In group Ⅲ and Ⅳ 3 cycles of 10 s reperfusion followed by 10 s ischemia were applied immediately after 45 min kidney ischemia.In group Ⅳ quercetin (a inhibitor of HSP) 100 mg/kg was given IP at 30 min before ischemia.Five rats were sacrificed at 0, 1,3,6, 12,24,and 48 h (T0-6) of reperfusion and the kidneys were immediately removed for determination the expression of HSP70 mRNA,HSP27 mRNA,HO-1 mRNA,HSP70,HSP27 and HO-1.At T3 before the rats were sacrificed blood samples were obtained for determination of serum creatinine (Cr),urea nitrogen (BUN) and tumor necrosis factor α (TNF-α) concentrations and kidneys were removed for determination of the expression of nuclear factor-kappa B (NF-κB),the methylene dioxyamphetamine (MDA) content and superoxide dismutase (SOD) activity,and observation of histopathology with light microscope. Results The expression of HSP70 mRNA,HSP27 mRNA,HO-1 mRNA,HSP70,HSP27 and HO-1 was traced in group S,and in the other three groups the expression of HSP70 mRNA,HO-1 mRNA and HSP70,HO-1 increased at T1 and reached peakpoint at T3,then began to decrease.Compared with group S,the expression of HSP70 mRNA,HSP27 mRNA,HO-1 mRNA,HSP70,HSP27 and HO-1 was up-regulated at T0-6 in other 3 groups (P＜0.05),.Compared with group I/R,the expression of HSP70 mRNA,HSP27 mRNA,HO-1mRNA,HSP70,HSP27 and HO-1 was up-regulated at T2-5 in group IPo (P＜0.05),Compared with group IPo,the expression of HSP70m RNA,HSP27m RNA,HO-1m RNA,HSP70,HSP27 and HO-1 was down-regulated at T2-5 in group Q+IPo (P＜0.05).There were no significant difference between group I/R and group Q+IPo (P＞0.05).Serum Cr,BUN and TNF-αconcentrations at T3 in group I/R (102±5) μmol/L,(25.7±3.9) mmol/L,(2.29±0.18) μg/L,in group IPo (64±5) μmol/L,(11.3±3.0) mmo]/L,(1.76±0.13) μg/L,and in grou Q+IPo (101±6) μ mol/L,(26.5±4.5) mmol/L,(2.31±0.17) μg/L were significantly increased than those in group S (46±6) μmol/L, (5.1±1.9) mmol/L and (1.13±0.14) μg/L (P＜0.05),and the serum Cr,BUN and TNF-αconcentrations in group IPo were decreased than those in group I/R,and those in group Q+IPo were increased than those in group IPo (P＜0.05).There were no significant difference between group I/R and group Q+IPo (P＞0.05).The MDA content (2.20±0.23) nmol/mgprot in group I/R,(1.35±0.13) nmol/mgprot in group IPo and (2.25±0.16) nmol/mgprot in group Q+IPo was increased than that in group S (P＜0.05),the activity of SOD (104±6) U/mgprot in group I/R,(124±4) U/mgprot in group IPo and (106±5) U/mgprot in group Q+IPo was decreased than that in group S (P＜0.05); the MDA content was decreased and SOD activity was increased in group IPo compared with group I/R,and the MDA content was increased and SOD activity was decreased in group Q+IPo compared with group IPo (P＜0.05).The expression of NF-KB in group was up-regulated at T3 in group I/R,IPo and Q+IPo compared with group S,that in group IPo was down-regulated compared with group I/R,and that in Q+IPo was up-regulated compared with group IPo (P＜0.05).There were no significant difference between group I/R and group Q+IPo (P＞0.05).Microscope examination showed that the renal injury was attenuated in group IPo compared with group I/R while there was no significant difference between group I/R and group Q+IPo. Conclusions IPo increased the expression of HSP70,HSP27,and HO-1 and the expression of HSP is involved in the reduction of renal I/R injury by IPo in rats. Key words: Ischemic postconditioning;  Ischemic/reperfusion injury;  Renal;  Heat shock protein