蛛网膜下腔出血大鼠早期大脑皮层低氧诱导因子-1α表达与细胞凋亡相关性研究

The relationship between hypoxia-inducible factor-1αexpression and apoptosis in early brain injury after subarachnoid hemorrhage

目的:研究大鼠蛛网膜下腔出血(SAH)后大脑皮层低氧诱导因子-1α(HIF-1α)的表达情况及其与细胞凋亡可能存在的关系,初步探讨HIF-1α表达在SAH后早期脑损伤中的作用。方法:采用改良血管内穿刺法建立SAH模型。35只成年雄性SD大鼠随机分入假手术组和SAH 6、12、24、72 h组。采用免疫荧光染色技术检测HIF-1α的表达水平,末端脱氧核苷酸介导的X-dUTP缺口末端标记法(TUNEL)检测细胞凋亡,同时应用免疫荧光双标染色技术检测表达HIF-1α的细胞类型。结果:免疫荧光染色结果显示HIF-1α的表达在假手术组几乎未见(0.29%±0.30%),SAH后6 h增加(4.65%±1.01%),24 h达高峰(18.55%±4.23%),差异均有统计学意义(均P<0.05)。TUNEL法检测到大鼠大脑凋亡细胞数在SAH后增多,6 h时可见少数凋亡细胞(7.09%±2.34%),在24 h到达高峰(25.54%±7.36%),差异有统计学意义(P<0.05)。相关分析显示各组HIF-1α阳性率与TUNEL阳性率呈正相关(r=0.738,P<0.05)。免疫荧光双标染色显示HIF-1α蛋白主要表达于神经元,部分HIF-1α染色阳性的细胞核与TUNEL染色重合。结论:大鼠SAH后早期脑损伤过程中HIF-1α表达与细胞凋亡呈正相关,提示HIF-1α可能参与SAH后早期脑损伤病理生理过程。

Objective： To investigate the association of hypoxia-inducible factor-1α （HIF-1α） expression and apoptosis in the cerebral cortex following subarachnoid hemorrhage （SAH）. Methods： Subarachnoid hemorrhage was induced by modified monofilament puncture method in rats. Thirty-five adult male Sprague-Dawley rats were randomly assigned to five groups ： sham-operated group, SAH 6 h, SAH 12 h, SAH 24 h and SAH 72 h groups. HIF-1 α expression was assessed by immunofluorescence staining. TdT-mediated dUTP-biotin nick end-labeling （TUNEL） technique was adopted to detect apoptotic cells. Double immunolabeling was used to identify cell types with positive HIF-1α expression. Results： The expression of HIF-1α was increased at 6 h （4. 65% ±1.01%）,peaked at 24 h （18.55% ±4.23%）,and decreased at 72 h （6. 31%± 1.15% ） after SAH （P 〈0. 05）. TUNEL-positive cells were up-regulated in the brain at 6 h （7.09% ±2. 34% ） ,peaked at 24 h （25.54% ±7.36% ） ,and down- regulated at 72 h （ 14. 11%± 3.03% ） after SAH （ P 〈 0. 05 ）. A significant positive correlation was noted between HIF-1α positive rates and TUNEL positive rates following SAH （r = 0. 738, P 〈 0. 05 ）. Double immunolabeling indicated that HIF-1α was expressed predominantly in neurons and some nuclei with positive HIF-1α were co- stained with TUNEL. Conclusion： The data indicate that HIF-1α might participate in the pathological progression of early brain injury after SAH.