缺氧诱导因子-1α在蛛网膜下腔出血早期脑水肿形成中的作用

Role of Hypoxia Inducible Factor- 1α in Early Brain Edema Formation after Subarachnoid Hemorrhage in Rats

目的探究缺氧诱导因子-1α(hypoxia inducible factor-1α,HIF-1α)在蛛网膜下腔出血(subarachnoid hemorrhage,SAH)早期脑水肿形成中的作用及相关机制。方法采用改良血管内穿刺法制作SAH模型。雄性SD(Sprague-Dawley)大鼠随机分成以下3组:SAH+3-(5'-羟甲基-2'-呋喃基)-1-甲苯(YC-1)组;SAH+二甲亚砜(DMSO)组;假手术组(sham组)。手术后24h采集脑组织标本。分别用Western blot技术和免疫荧光染色技术检测HIF-1α和血管内皮生长因子(vascular endothelial growth factor,VEGF)的表达水平;应用伊文思蓝法(Evans blue,EB)和干湿重法分别检测血脑屏障通透性和脑组织含水量;同时记录大鼠术后24h神经功能评分及死亡率。结果与sham组相比,SAH+DMSO组中HIF-1α和VEGF的表达显著增多,血脑屏障破坏和脑水肿明显加重(P<0.05);相对于SAH+DMSO组,SAH+YC-1组中HIF-1α和VEGF的表达显著性减少,血脑屏障破坏和脑水肿明显减轻,同时改善神经功能及降低大鼠死亡率(P<0.05)。结论 HIF-1α可能通过诱导、调控VEGF的表达加重血脑屏障破坏,从而促进SAH早期脑水肿的形成。YC-1通过抑制SAH后HIF-1α、VEGF表达水平,进而减轻SAH后血脑屏障破坏和早期脑水肿,同时改善大鼠神经功能及降低大鼠死亡率。

Objective To investigate the role of hypoxia inducible factor-1α （HIF-1 α） in early brain edema formation and its possible mechanism after experimental subarachnoid hemorrhage （SAH） in rat.Methods The monofilament puncture model was used to induce SAH in this study.Adult male Sprague-Dawley （SD） rats were randomly assigned into SAH ＋ YC-1 group,SAH ＋ DMSO group and sham group.Rats in the SAH ＋ YC-1 group were treated with 2 mg/kg 3-（5＇-hydroxymethyl-2＇-furyl）-1-benzylindazole （YC-1） at 24 h and 30 min before the induction of SAH,and rats of the SAH ＋ DMSO group received equivolume DMSO vehicle.Brain samples were extracted at 24 h after surgery.Protein expression levels of HIF-1 α and vascular endothelial growth factor （VEGF） were analysed using western blot and immunofluorescence staining.The permeability of blood-brain barrier （BBB） and brain water content were assessed by Evans Blue （EB） and dry-wet method,respectively.Additionally,the mortality and neurological scores were recorded at 24 h after operation.Results Compared with the sham-operated group,increased expressions of HIF-1α and VEGF,and remarkable brain edema and BBB extravasations were observed after SAH （P ＜ 0.05）.Compared to the SAH ＋ DMSO group,inhibition of HIF-1 α with YC-1 suppressed the expression of VEGF,diminished BBB damage and brain edema,improved neurologic function and reduced mortality （P ＜ 0.05）.Conclusion These data indicated that HIF-1-induced VEGF increases BBB permeability and accelerate the formation of brain edema after SAH.YC-1 improved brain edema and neurologic function and reduced mortality after SAH,probably by inhibition of HIF-1α and VEGF,which led to the preservation of the BBB function.