预吸氧对大鼠缺氧复氧性脑损伤影响的研究

The effect of the preoxygenation on rat cerebral hypoxia/reoxygenation injury

目的探讨预吸氧对大鼠缺氧复氧性脑损伤的影响及其机制。方法49只雄性Wistar大鼠随机分为7组,应用Western印迹、免疫组化和黄嘌呤氧化酶法检测在50%和100%预吸氧30min后缺氧(5%O2,30min)复氧(100%O2,1或6h)后大鼠脑皮质内NF-κB、iNOS和Mn-SOD的表达情况,同时用病理组织学方法观察脑组织损伤程度。结果与对照组相比,NF-κB的表达在100%预吸氧缺氧复氧1h组的表达显著增加(P<0.05),而50%预吸氧缺氧复氧1h组表达显著降低(P<0.01),50%预吸氧缺氧复氧6h组最低(P<0.01);与缺氧复氧1h组相比,NF-κB的表达在50%预吸氧缺氧复氧1h组显著降低(P<0.01);与缺氧复氧6h组相比,NF-κB的表达在50%预吸氧缺氧复氧6h组显著降低(P<0.01)。100%预吸氧缺氧复氧1h(P<0.05)和6h(P<0.01)两组的iNOS阳性细胞数显著高于对照组。与对照组相比,各组Mn-SOD的活力均显著增加(P<0.05或P<0.01)。与缺氧复氧1h组相比,50%预吸氧缺氧复氧1h组Mn-SOD的活力显著增加(P<0.05)。病理表现为:50%预吸氧缺氧复氧组的损伤与缺氧复氧组无明显差别,而100%预吸氧缺氧复氧组病理改变加重。结论50%预吸氧可能改善缺氧复氧性脑损伤程度,而100%浓度预吸氧可加重缺氧复氧性脑损伤程度。

Objective To study the effect of the preoxygenation on rat cerebral hypoxia/reoxygenation injury. Methods Forty-nine healthy male Wistar rats weighting 230 - 280 g were randomly divided into 7groups. All rats were exposed to preoxygenation （50% or 100% O2 ） for 30 min , then to hypoxia （5% O2 ） for 30 min, to reoxygenation （ 100% 02 ） for 1 hor 6 h at last. The protein expression level of nuclear factorκB（ NF- κB）, induced nitric oxide synthase （iNOS） and Manganese superoxide dismutase （Mn-SOD）in the brain of rats were examined by Western blot , immunohistochemistry and xanthine oxidase analysis. Rat brain tissues were examined by light microscope to determine the degree of neuronal damage. Results The expression of NF-κB significantly increased in 100% preoxygenation-hypoxia-reoxygenation（PHR） 1 h group than normal group（ P 〈 0. 05 ）, but the expression of NF-κB significantly decreased in 50% PHR group than normal group （P 〈 0. O1 ）. Compared with hypoxia-reoxygenation （HR） 1 and 6 h group, the expression of NF-κB significantly decreased in 50% PHR 1 and 6 h group（P 〈0. O1 ）. The percentage of iNOS positive ceils all significantly increased after reoxygenation for 1 and 6 h in 100% PHR group（ P 〈 0. 05 ,P 〈 O. O1 ）. The activity of Mn-SOD all increased. Compared with HR 1 h group, the activity of Mn-SOD increased significantly in 50% PHR 1 h group（P 〈0. 05）. Pathologic findings： the degree of injury in HR group was more serious than hypoxia （5% 02 ） group. The degree of injury was the most serious in HR 6 h group. There were no significant differences in rats＇cerebral injury between 50% PHR group and HR group. The degree of injury in 100% PHR group was more serious than in HR group. Conclusions 50% preoxygenation can improve reversible injury, but 100% preoxygenation can aggravate hypoxia-reoxygenation injury.