Characteristics of effect of H_2O_2 preconditioning on NF-κB activation and its role in the cytoprotection in PC12 cells

Aim To explore the effect of H2O2 precon-ditioning on nuclear factor-kappa B(NF-κB)activa-tion and the role NF-κB in cytoprotection induced by H2O2 preconditioning in PC12 cells.Methods The experimental model of H2O2 preconditioning against apoptosis induced by H2O2 at a high concentration was established,and experimental groups were divided as follows:(1)control;(2)precondition;(3)H2O2;(4)precondition+H2O2;(5)TPCK+ precondition+H2O2;(6)TPCK.The percentage of apoptotic cells was measured by flow cytometry(FCM)with propidium iodide stain.The viability of PC12 cells was assessed by MTT assay.The level of NF-κB expression was detected by Western blot.The NF-κB DNA binding activity was detected by electrophoretic mobility shift assay(EMSA).Results H2O2 preconditioning significantly up-regulated NF-κB p65 expression and promoted its DNA binding activity.Furthermore,H2O2 preconditioning obviously enhanced the expression of NF-κB p65 induced by H2O2 at a high dose(P0.01,compared with H2O2 group).H2O2 preconditioning markedly protected PC12 cells against injury induced by H2O2 at a high dose,increasing the viability of cells and decreasing the percentage of apoptotic cells(P0.01,compared with H2O2 group).N-tosyl-L-phenylalanine chloromethyl ketone(TPCK),an inhibitor of NF-κB antagonized H2O2 preconditioning-induced NF-κB activation and the adaptive cytoprotection(P0.01,compared with PC+H2O2 group).Conclusion NF-κB was activated by H2O2 preconditioning,which was one of the underlying mechanisms underlying adaptive cytoprotection induced by H2O2 preconditioning.