Erythropoietin rescues primary rat cortical neurons from pyroptosis and apoptosis via Erk1/2-Nrf2/Bach1 signal pathway

The most commonly used inhalation anesthetics, sevoflurane, is reported to be a risk for development of learning disability. Erythropoietin (EPO) administration might be involved an effective therapy for sevoflurane neurotoxicity. EPO-EPO receptor-extracellular signal-related kinases 1/2 (Erk1/2) signal pathway plays a pivotal role in the neuroprotective effect. Nuclear factor erythroid 2-related factor (Nrf2)/BTB and CNC homology 1 (Bach1) ratio altering by Erk1/2 could ameliorate oxidative stress occurred in human macrophages. Primary cortical neuron cultures exposed to sevoflurane were assessed for cleaved caspase-1, cleaved caspase-3, Nrf2, Bach1, total Erk1/2, and phosphorylated Erk1/2 with the following: 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT); propidium iodide uptake (PI); lactate dehydrogenase (LDH); malondialdehyde (MDA); superoxide dismutase (SOD); Real-time PCR; and Western blot. We found that sevoflurane exposure increased cell pyroptosis, apoptosis, injury, and MDA (n = 9, P < 0.05), but decreased cell viability (n = 9, P < 0.05) and down-regulated SOD (n = 9, P < 0.05), while EPO partially rescued the neurotoxicity induced by sevoflurane (n = 9, P < 0.05), as well as increase the expression of Nrf2 mRNA and Nrf2/Bach1 ratio (n = 9, P < 0.05). Inhibition of Erk1/2 phosphorylation via PD98059 reversed the protective effect of EPO (n = 9, P < 0.05). Thus, protection of EPO markedly attenuated pyroptosis and apoptosis of neurons exposed to sevoflurane via Erk1/2-Nrf2/Bach1 signal pathway.