RESUMO
Objective To investigate the effect of hyperbaric oxygen preconditioning (HBO) on activation of extracellular signal-regulated kinase (ERK) and death-associated protein kinase 1 (DAPK1)in ischemia-like treated neurons.Methods (1) Cultured mouse primary neurons were allocated into control,ischemia-like condition treated and HBO preconditioning groups.Neurons in ischemia-like condition treated group were treated with 95％ NO2+5％ CO2 for 30 min,and cells in the HBO preconditioning group were pretreated with 98％ O2+2％ CO2 for 2 h,followed by ischemia-like condition treatment.At the end ofthe treatment,the growth of neurons was measured by MTT assay and expression of phosphorylated extracellular signal-regulated kinase (p-ERK) was detected by Western blotting.Neurons were transfected with ERK over-expression vector and pretreated with HBO and ischemia-like condition,and then,the expressions of activated caspase-3 (cleavage caspase-3) and DAPK1 in neurons were analyzed by Western blotting.The interactions of ERK with DAPK1 were also detected by irnmunoprecipitation.(2) Forty-five BALB/c mice were randomized into control,ischemia treated and HBO preconditioning groups.After finishing the treatments,the interactions of ERK with DAPK1 in hippocampal neurons were detected by immunoprecipitation.Results As compared with control group,cells in ischemia-like condition group showed a reduction of cell survivals,while cells in HBO preconditioning group exhibited an inhibition effect on ischemia-like condition-induced cell survival reduction.The expressions of p-ERK were increased by ischemia-like condition,while decreased by HBO preconditioning,with significant difference (P＜0.05).Moreover,over-expression of ERK promoted level of cleavage caspase-3 in neurons; however,DAPK1 expressions were not affected by ischemia-like condition or HBO preconditioning.The interactions of ERK with DAPK1 were attenuated by HBO preconditioning as compared with those by ischemia-like condition treatment.Conclusion HBO preconditioning inhibits ERK activation and disturbs the interaction between ERK and DAPK1,which blocks cell apoptosis and thus induces ischemic tolerance.