Edaravone inhibits the expression of vascular endothelial growth factor in human astrocytes exposed to hypoxia

Edaravone (3-methyl-1-phenyl-2-pyrazolin-5-one), a free radical scavenger, reduces brain edema in patients with acute ischemic stroke. We have addressed the effect of edaravone on the expression of vascular endothelial growth factor (VEGF), a potential mediator of brain edema, in astrocytes exposed to hypoxia. Normal human astrocytes in culture were treated with edaravone, and the levels of VEGF mRNA and protein were analyzed by reverse transcription-polymerase chain reaction (RT-PCR), real-time quantitative PCR and enzyme-linked immunosorbent assay (ELISA). The expression of hypoxia-inducible factor-1α (HIF-1α), a transcriptional activator of VEGF, was examined by RT-PCR, real-time PCR and western blotting; and the binding of HIF-1α to the promoter region of VEGF gene by chromatin immunoprecipitation (ChIP) assay. Edaravone moderately suppressed the expression of VEGF mRNA and protein in astrocytes under hypoxia in time- and concentration-dependent manners. It also suppressed the accumulation of HIF-1α in the nuclei under hypoxia. ChIP assay confirmed that edaravone reduced HIF-1α binding to VEGF promoter. We conclude that edaravone inhibits VEGF expression in astrocytes exposed to hypoxia, at least partly, through the down-regulation of HIF-1α. These findings offer a partial explanation for the protective effect of edaravone on the development of brain edema in patients with acute ischemic stroke.