Effect Of Recombinant Human Erythropoietin On TLR4/NF-κB Signal Transduction Pathway Of Renal Ischemia Reperfusion Injury In Rats

Objective：To observe the effect of recombinant human erythropoietin(rhEPO) injected in the same dose but different time points on toll-like receptor4/nucleus factor-kappa B (TLR4/NF-κB) signal transduction pathway of renalischemia reperfusion injury in rats. To discuss the effect of toll-like receptor4/nucleus factor-kappa B (TLR4/NF-κB) on renal ischemia reperfusion injury inrats，and how it works. And to discuss the renal protective effects of rhEPO andthe differences between different time points.Methods：70male SD rats were randomly divided into sham operationgroup (Sham group, n=10)、ischemia reperfusion group (IR group, n=10)、thegroup receiving rhEPO in the different time points（n=50）. The group receivingrhEPO in the different time points conclude: the group receiving rhEPO6hbefore ischemia (P6group，n=10)、the group receiving rhEPO2h beforeischemia (P2group，n=10)、the group receiving rhEPO0h before ischemia (P0group，n=10)、the group receiving rhEPO2h after ischemia (A2group，n=10)、the group receiving rhEPO6h after ischemia (A6group，n=10).Sham group, in which rats were right nephrectomy without left renal ischemia/reperfusion andadministered the same dose of saline; I/R group, in which rats were rightnephrectomy and clamping on the left renal pedicle for45min and reperfusionfor24h; P6group, in which rats were were also right nephrectomy andadministered rhEPO2000u/kg6h prior to I/R; P2group, in which rats were werealso right nephrectomy and administered rhEPO2000u/kg2h prior to I/R; P0group, in which rats were were also right nephrectomy and administered rhEPO2000u/kg at the same time of clamping on the left renal pedicle and reperfusionfor24h; A2group, in which rats were were also right nephrectomy andclamping on the left renal pedicle for45min and administered rhEPO2000u/kg2h after clamping on the left renal pedicle, and reperfusion for24h; A6group,in which rats were were also right nephrectomy and clamping on the left renalpedicle for45min and administered rhEPO2000u/kg6h after clamping on theleft renal pedicle, and reperfusion for24h. After24h of reperfusion the renalpathological changes were observed by light electron microscope. BUN and Crwere determined and compared. Reverse transcriptional-polymerase chainreaction (RT-PCR) was performed to evaluate the mRNA levels of TLR4andNF-κB. The expression and distribution of TLR4and NF-κB p50in renaltubular epithelial cell(TEC) in renal ischemia reperfusion were determined byimmunohistochemistry.Results： The renal pathological changes of rats in IR group weresignificantly, the expression of BUN,Cr,TLR4mRNA, NF-κB mRNA，TLR4protein(expressed in cytoplasm)，NF-κB p50protein（expressed in cytoplasmand nucleus）were increased remarkably in IR group, as compared with Shamgroup (P＜0.05). The renal pathological changes of rats in the group receiving rhEPO in the different time points were insignificantly. BUN and Cr were lowerthan those of IR group, the expression of TLR4mRNA and NF-κB mRNA weredecreased, so were the expression of TLR4protein(expressed in cytoplasm)，NF-κB p50protein（expressed in cytoplasm and nucleus）(P＜0.05). In the groupreceiving rhEPO in the different time points, the renal pathological changes ofrats in P6and P2were less significantly than P0、A2、A6, the expression ofBUN,Cr,TLR4mRNA, NF-κB mRNA，TLR4protein(expressed in cytoplasm)，NF-κB p50protein（expressed in cytoplasm and nucleus）were lower (P＜0.05).The difference between P6and P2was not significant (P＞0.05)，so were thedifferences between P0,A2,A6(P＞0.05).Conclusion： The expression of the TLR4/NF-κB signal transductionpathway can be decreased by rhEPO, the renal protective effect of receivingrhEPO before ischemia is more significant than receiving rhEPO after ischemia.