Sevoflurane induces HO-1 Gene Expression via p38/Nrf2 Kinase Signal Pathways and Inhibits Neuron Apoptosis

Objective To investigate signal pathway associated with neuron hemeoxygenase-1(HO-1) expression in sevoflurane-induced, and explore neuroprotection mechanisms of sevoflurane. Methods Newborn (24～48h) Wistar rats were decapitated and hippocampus tissue was dissected. Then digestion with 0.125% trypsin, centrifuged at 800 rpm/min for 5 min at 4℃, and suspended in a medium containing DMEM supplemented to 25mmol/L glucose, 10% fetal bovine serum, 10% horse serum, and 2 mmol/L glutamine. Cells were plated at 1×105/mL on poly-Dlysine-treated 6-well (2mL/well), 96-well (100μL/well) plates and were treated with 10 μmol/L cytosine arabinoside on day 4 to minimize glial growth. One-half of the medium was replaced twice a week with medium consisting of DMEM (4.5g/L glucose)/F12(1∶1), 5% fetal bovine serum and 5% horse serum. Cells were used after growing for 7 days. Cells were randomly divided into 5 groups: control group(C group),oxygen glucose deprivation(OGD) group (D group), 2% sevoflurane + OGD group (S1 group), 4% sevo? urane + OGD group (S2 group)and 4% sevo? urane + SB203580 + OGD group (SB group). Control cells were cultured normally. D group cultures were washed three times in a glucose-free balanced salt solution (BSS) .They were then placed in deoxygenated glucose-free medium and sealed under 95% N2-5% CO2 in an anaerobic chamber equilibrated to 37℃ and 100% humidity for 60 min. OGD was terminated by replacement of stored medium and by returning the cultures to a standard incubator maintained at 37℃ in 95% Air-5% CO2. Group S1 and S2 cells preconditioned with 2% or 4% sevoflurane firstly and cells was carried out OGD, then cultured normally 24 hours. Group SB cells culture medium was added 10μmol/L SB203580 and preconditioned with 4% sevoflurane, and cells was carried out OGD, then cultured normally 24 hours. The expression of HO-1 mRNA, p38, Nrf2, AP-1 and HO-1 protein were detected. Neuron viability and apoptosis were measured. Results 2% Sevoflurane enhanced neuron expression of p38 and Nrf2(vs group D, P0.01), and increased neuron expression of HO-1 mRNA and HO-1 (vs group D, P0.01),but AP-1 expression had no signifi cant difference (vs group D, P0.05), meanwhile increased neuron viability and decreased neuron apoptosis (vs group D, P0.01).4% Sevoflurane enhanced neuron expression of p38 and Nrf2 (vs group S1, P0.05), and increased neuron expression of HO-1 mRNA and HO-1 (vs group S1, P0.05),but AP-1 expression had no significant difference (vs group S1, P0.05), meanwhile increased neuron viability and decreased neuron apoptosis (vs group S1, P0.01). SB203580 inhibited neuron expression of p38 and Nrf2 (vs group S2, P0.01), and inhibited neuron expression of HO-1 mRNA and HO-1 (vs group S2, P0.01), but AP-1 expression had no signifi cant difference (vs group S2, P0.05), meanwhile decreased neuron viability and increased neuron apoptosis (vs group S2, P0.01). Conclusion Sevoflurane induces neuron HO-1 mRNA expression via p38/ Nrf2 kinase signal pathways and protects neuron against oxygen glucose deprivation injury.