[Exogenous EPO protects HT22 cells from intermittent hypoxia-induced injury by activating JAK2-STAT5 signaling pathway].

Abstract

The aim of this study was to investigate the effects of exogenous erythropoietin (EPO) on intermittent hypoxia (IH)-induced neuronal injury and the underlying mechanism. Mouse hippocampal neuron HT22 cells were exposed to IH for different durations (1% O₂ for 7 min/21% O₂ for 3 min, one cycle for 10 min). Cell viability was detected by CCK-8. EPO content in the supernatant of cell culture medium was detected by ELISA kit, and the protein expression was detected by Western blot. EPO receptor (EPOR) protein expression was detected by immunofluorescence staining and Western blot. Cellular apoptosis and mitochondrial membrane potential were detected by the corresponding kits. Reactive oxygen species (ROS) level was detected by DCFH probe, and expression levels of JAK2-STAT5 signaling pathway-related proteins were detected by Western blot. The results showed that IH exposure significantly decreased HT22 cell activity. EPO and EPOR protein expressions were significantly up-regulated at 12 h of IH exposure, but down-regulated at 24 and 48 h. In IH-treated HT22 cells, exogenous EPO significantly increased cell activity and mitochondrial membrane potential, decreased ROS levels and cell apoptosis, up-regulated Nrf-2 and heme oxygenase 1 (HO-1) protein expression levels, decreased Cleaved-Caspase-3/Caspase-3 and Bax/Bcl-2 ratios, and promoted the phosphorylation of JAK2-STAT5 pathway-related proteins. Whereas JAK2 and STAT5 blockers both reversed these neuronal protective effects of EPO. These results suggest exogenous EPO inhibits IH-induced oxidative stress and apoptosis by activating the JAK2-STAT5 signaling pathway, thus exerting a neuronal protective effect.