停通气缺氧预处理对大鼠脑出血后血肿周围区超微结构和IL-6含量的影响

Effects of asphyxial hypoxic preconditioning on ultrastructural characters and interlukin-6 in perihemotoma area after intracranial hemorrhage in rats

目的观察停通气缺氧预处理对脑出血(ICH)后大鼠血肿周围区超微结构以及脑组织中白细胞介素-6(IL-6)含量的影响。方法120只雄性SD大鼠,随机分为脑出血组(I组,60只)和缺氧预处理组(P组,60只)。每组麻醉后行气管插管机械控制通气。P组进行停通气1min、复通气5min的缺氧预处理,反复4次。所有大鼠机械通气1h后,拔出气管导管,然后采用立体定向技术,将50μl自体不凝血注入尾状核中。在脑出血后6、24、48和72h电镜下观察血肿周边区超微结构的变化,并进行评分,同时采用放射免疫分析法测定IL-6含量。结果电镜观察可见:I组血肿周围组织注血后6h星形胶质细胞胞体和周边足突肿胀,24h星形胶质细胞肿胀加重,神经元固缩,72h部分神经元出现坏死崩解;P组神经元和星形胶质细胞的损害轻于I组,电镜评分在48h明显优于I组(P<0.01)。脑组织匀浆中IL-6的含量随脑出血时间的延长而逐渐增加,在ICH后48h达高峰,72h有所下降。两组比较,ICH后6h时,I组IL-6含量显著低于P组,P<0.01。结论停通气缺氧预处理可增加脑出血后大鼠脑组织中IL-6的含量,减轻血肿周围组织超微结构的损害,具有一定的脑保护作用。

Objective To observe the effects of asphyxial hypoxic preconditioning on uhrastructural characters and the concentration of interlukin-6 in perihemotoma area after intracranial hemorrhage （ICH） in rats. Methods 120 male SD rats were randomly divided into two groups： ICH group（Group Ⅰ, n=60） and preconditioning group （Group P, n= 60）. The rats were anesthetized 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, the endotracheal was extubated. ICH model was made by stereotactic injection of 50 μl anti-coagulated blood into the caudate nucleus in group P and I. Ultrastructural characters were observed and evaluated under electric microscope and the concentration of interlukin-6 in brain tissues were measured with radioimmu noassay at 6 h, 24 h, 48 h and 72 h after intracerebral hemorrhage. Results From the electric microscope investigation, astrocytes started to swell at 6h after ICH in group I. 24 h after ICH, neurous degenerated and the capillaries were pressed by the swollen foot-plate. At 72h, part of neurous became degenerated and necrotic, blood-brain barrier was destroyed. The changes in group P were much milder than that in group Ⅰ, especially neurous at 48 h were much better in group P than in group Ⅰ. The concentration of IL-6 in brain raised markedly in group Ⅰ and P at 6 h after ICH （P〈0.01）, peaked at 48 h （P〈0.05） and decreased at 72 h. Conclusions Asphyxial hypoxic preconditioning increases the concentration of IL-6, alleviates uhrastructural damages, and demonstrates certain cerebral protective effect after ICH in rats.