Role of ERK signaling pathway in inhibition of OGD/R-induced apoptosis in rat cortical neurons by sevoflurane: the relationship with mPTP

Abstract

Objective To evaluate the role of extracellular signal-regulated kinase(ERK)signaling pathway in inhibition of oxygen-glucose deprivation and restoration(OGD/R)-induced apoptosis in rat cortical neurons by sevoflurane and the relationship with mitochondrial permeability transition pore(mPTP). Methods The rat cortical neurons were cultured in vitro and seeded in 6-well or 12-well culture plates.The neurons were randomly divided into 4 groups(n=18 each)using a random number table: control group(group C); OGD/R group(group O); sevoflurane group(group OS); sevoflurane+ ERK1/2 inhibitor PD98059 group(group OSP). The neurons were subjected to O2-glucose deprivation for 90 min followed by restoration of O2-glucose supply for 24 h in group O. The neurons were incubated with 2% sevoflurane for 2 h after OGD/R in group OS.OGD/R was performed at 1 h after ERK1/2 inhibitor PD98059 30 μmol/L was added, and the neurons were incubated with 2% sevoflurane for 2 h after OGD/R in group OSP.At 24 h of restoration of O2-glucose supply, the expression of phosphorylated ERK1/2(p-ERK1/2)in neurons was measured by Western blot, the neuronal apoptosis was detected using Annexin V-FITC/PI double staining combined with flow cytometry, and the opening of mPTP was determined through measuring the optical density at 540 nm.The apoptosis rate was calculated. Results Compared with group C, the expression of p-ERK1/2 in neurons was significantly up-regulated, and the apoptosis rate and mPTP opening were significantly increased in group O(P<0.05). Compared with group O, the expression of p-ERK1/2 in neurons was significantly up-regulated, and the apoptosis rate and mPTP opening were significantly decreased in group OS(P<0.05). Compared with group OS, the expression of p-ERK1/2 in neurons was significantly down-regulated, and the apoptosis rate and mPTP opening were significantly increased in group OSP(P<0.05). Conclusion The mechanism by which sevoflurane inhibits OGD/R-induced apoptosis in rat cortical neurons is related to inhibition of mPTP opening after activation of ERK signaling pathway. Key words: Extracellular signal-regulated MAP kinases; Mitochondrial membrane transport proteins; Anesthetics, inhalation; Neurons; Apoptosis