Objective To investigate the protective effect of hypoxia-inducible factor-1α(HIF-1 α) on the neurovascular unit in rats with traumatic brain injury (TBI).Methods The fluid percussion model was applied to induce TBI in rats.A total of 600 rats were divided into sham operation group,TBI group,TBI + HIF-1 α silence group and TBI + control virus group according to the random number table,with 150 rats in each.Virus-mediated HIF-1 α silence gene and control virus were delivered 24 h before the fluid percussion injury.After 3,7 and 14 d,brain injury area and morphological changes in injured region were detected by HE staining,expressions of vascular endothelial cell markers (vWF) and HIF-1 α were detected by Western blot method,and expressions of vascular endothelial growth factor (VEGF),matrix metalloproteinase-9 (MMP-9),tumor necrosis factor-α (TNF-α),interleukin 6 (IL-6) and nuclear factor-κB (NF-κB) in peripheral blood and brain tissue were detected by ELISA method.Rat neural function was dynamically assessed using the modified neurological severity score (mNSS).Results (1) Brain injury area and edema area in TBI + HIF-1 α silence group were higher than those in TBI group at all time points (P ＜ 0.05).(2) Compared with sham operation group and TBI + control virus group,expression of HIF-1α in TBI group gradually increased and remained high at 7 and 14 d postinjury (P ＜ 0.05).Compared with TBI group,expression of vWF in TBI + HIF-1αsilence group decreased at all time points (P ＜ 0.05) and inhibited angiogenesis.(3) TBI + HIF-lα silence group versus TBI group showed remarkably decreased VEGF at all time points,increased expressions of TNF-α,IL-6 and NF-κB at all time point,and increased expression of MMP-9 at 7 and 14 d postinjury (all P ＜0.05).(4) TBI + HIF-1α silence group versus TBI group showed significant difference in mNSS at 7 and 14 d postinjury (all P ＜ 0.05).Conclusions After TBI,high expression of HIF-1αcan facilitate vascular formation and inhibit inflammatory reaction related factor expression,inducing the mitigation of brain edema and brain injury.Therefore,promoting HIF-1α expression may become a new means to improvement of neurovascular function after TBI.