Inhibition of endoplasmic reticulum stress by ethyl pyruvate attenuates simulated ischemia reperfusion injury of neonatal rat cardiomyocyte

Abstract

Objective To explore the effect of ethyl pyruvate(EP)on the simulated ischemia reperfusion(SIR)injury of neonatal rat cardiomyocyteand the role of endoplasmic reticulum stress(ERS)in this procedure. Methods The cultured neonatal rat cardiomyocytes, pretreated with EP(5 or 10 mmol/L)for 2 h, were subjected to SIR injury(hypoxia for 2 h, reoxygenation for 4 h). Methyl thiazolyl tetrazolium (MTT)method was used to detect the cell viability,special kits were used to detected the levels of malondialdehyde(MDA)and superoxide dismutase(SOD)in culture medium.Western blotting was used to detect the expression of ERS related molecules glucose regulated protein 78(GRP78) and CCAAT/enhancerbinding protein homologous protein(CHOP).Further, EP treatment was added with the ERS activator thapsigargin(THA), the effect of THA on the protection of EP against SIR was observed. Results Both 5 and 10 mmol/LEP treatment dramatically increased the cell viability(0.424±0.016 and 0.517± 0.020), downregulated the increased MDA level[(16.17±1.75)and(11.45±1.20)μmol/L]and decreased SOD level[(58.61±4.70)and(72.60±4.35) U/L]in the culture medium(vs.the SIR group, P<0.05).Compared with the control group, the level of GRP78 and CHOP increased significantly in the SIR group(P< 0.05), while EP treatment significantly decreased the level of GRP78 and CHOP(vs.the SIR group, P<0.05).Further, the ERSactivator THA reversed the protection of EP, decreased the cell viability(vs.the EP+ SIR group, P< 0.05), upreguleted the expression of GRP78 and CHOP(vs.the EP+ SIR group, P<0.05). Conclusion EP treatment can protect against SIR injury of neonatal rat cardiomyocyte, this effect is associated with inhibition of ERS. Key words: Ethyl pyruvate; Cardiomyocyte; Simulated ischemia reperfusion; Endoplasmic reticulum stress