停通气缺氧预处理对脑出血模型大鼠缺氧诱导因子-1α的影响

Effects of Asphyxial Hypoxic Preconditioning on HIF-1α after Intracranial Hemorrhage in Rats

目的观察停通气缺氧预处理（HPC）对脑出血（ICH）模型大鼠神经行为学评分、血肿周围组织中缺氧诱导因子-1α（HIF-1α）的表达和一氧化氮（NO）含量、一氧化氮合酶（NOS）活性的影响。方法180只雄性SD大鼠，体质量260～290g，用数字表法随机分为假手术组（S组，60只）、脑出血组（I组，60只）和缺氧预处理组（P组，60只）。所有大鼠麻醉后行气管插管并给予维库溴胺机械控制通气。P组进行停通气1min、复通气5min的缺氧预处理（反复4次），其他2组未做处理，仅进行机械通气。所有大鼠机械通气1h后，拔出气管导管。采用立体定向技术，将50μL自体不凝血注入P组和Ⅰ组动物的尾状核中，S组注入同样剂量的生理盐水。在ICH后6h、24h、48h和72h各时间点，从存活鼠中随机抽取10只大鼠记录神经行为学（NDS）评分和Rosenberg评分，其中5只连续切片进行HIF-1α免疫组化染色；另5只大鼠活杀后取脑，用分光光度法测定血肿周围组织中NO质量摩尔浓度和NOS酶活性。结果P组神经行为学评分在ICH后6h、24h和48h均优于Ⅰ组（P〈0．05）。Rosenberg评分P组在6h为3．9±1．5，优于I组的5．4±1．5（P〈0．01）。P组和Ⅰ组的HIF-1α阳性细胞明显增多，与S组相比差异有统计学意义（P〈0．01）。P组在24hHIF-1α阳性细胞数为（6．0±0．8）个，明显低于Ⅰ组[（11．4±1．8）个，P〈0．01]。NO质量摩尔浓度和NOS酶活力在ICH后也显著增加，其中P组NO质量摩尔浓度在24h的变化明显轻于Ⅰ组（P〈0．01）。结论停通气缺氧预处理能够改善脑出血模型大鼠的神经功能预后，具有一定的脑保护作用。其机制可能与降低HIF-1α的表达，抑制脑组织中NO质量摩尔浓度和NOS酶活性增加有关。

Objective To investigate observe the effects of asphyxial hypoxic preconditioning on neurological symptoms, expression of Hypoxia-inducible factor-1α（HIF-1α）, content of nitric oxide （NO） and nitric oxide synthase （NOS） in brain tissue after intracranial hemorrhage（ICH） in rats. Methods 180 male SD rats were randomly allocated into three groups： sham group （group S, n=60） ,ICH group（group Ⅰ, n：60） and preconditioning group（group P, n=60）. The rats were anesthetized, paralyzed with vecuronium 2 mg/kg and mechanically ventilated. The rats in P group were pretreated with four times of preconditioning, by being stopped ventilation for 1 min and reventilated for 5 min per circle. One hour later, endotracheal was extubated. ICH model was made by stereotactic injection of 50/μL antilogous blood into the caudate nucleus in group P and I, and 50 /μL saline in group S. Neural deficit scores （NDS） and Rosenberg scores were evaluated and the expression of HIF-1α in cerebral tissues were detected by using immunohistochemistry techniques and the content of NO and NOS were assayed by spectrometry at 6 h, 24 h, 48 h and 72 h after intracerebral hemorrhage. Results In group P, NDS scores were much better at 6 h, 24 h and 48 h than that in group Ⅰ （P〈0.05）. Rosenberg score was significantly decreased in group P at 6 h （3.9± 1.5） as compared with group Ⅰ （5.4±1.5, P〈0.01）. HIF-1α expression raised obviously at 24 h and increased to the 72 h after ICH. The number of HIF-1α positive cells was much higher in group Ⅰ than that in group P at 24 h and 48 h after ICH（P〈0.01）. Compared with the S group, NO and NOS content in group P and Ⅰ raised obviously after 6 h ICH. But in group P the changes of NO and NOS content were much less at 24 h than that in group I （ P〈 0.01 ） . Conclusion Asphyxial hypoxic preconditioning improves NDS and Rosenberg scores and demonstrates cerebral protective effect after ICH in rats which maybe related to the decreasing of the HIF-1α expression and the depressing of the NO and NOS increase in brain tissue.