吸氧预处理对大鼠局灶性脑缺血损伤的保护作用

目的　研究吸入不同时间 10 0 % O2 能否诱导脑缺血耐受而对脑缺血再灌注损伤产生保护作用 .方法　 6 3只 SD大鼠随机分为 7组 (每组 n=9) :即 A组 (对照组 )于缺血前 2 4h吸空气 2 4 h;B,C和 D组分别于缺血前 2 4 h连续吸 10 0 %O2 2 4 ,12和 6 h;E,F和 G组分别连续吸 10 0 % O2 2 4 ,12和 6 h. A,B,C和 D组于吸氧结束后 2 4 h造成脑缺血 ;E组于吸氧后即刻造成脑缺血模型 ;F组间隔 12 h;G组间隔 18h后造成脑缺血 .局灶性脑缺血模型采用 3- 0尼龙线线栓法栓塞大脑中动脉 ,2 h后拔出尼龙线使血液再灌注 .脑缺血 2 h和再灌注后 2 4 h行脑功能障碍评分 ,并处死动物取大脑行TTC染色测量脑梗死容积 .结果　 B组的脑功能障碍评分与A组相比显著降低 (P<0 .0 5 ) ,C,D,E,F和 G组与 A组相比无显著性差异 ;脑梗死容积 B组 (10 4 .8± 6 2 .1) mm3显著小于 A组 (199.0± 6 9.6 ) mm3(P<0 .0 1) .吸 10 0 % O2 12 h及6 h组及吸 10 0 % O2 2 4 h后即刻造成脑缺血组与对照组相比其脑梗死容积无明显差异 .结论　本实验首次证实连续吸10 0 % O2 2 4 h且间隔一定时间后能模拟缺血预处理对大鼠短暂性脑缺血产生保护作用 .

Neuroprotection of preconditioning with oxygen inhalation against ischemic injury in transient middle cerebral artery occlusion rats

AIM To determine if 100% oxygen inhalation induces ischemic tolerance in focal cerebral ischemia in rats. METHODS Sixty three male SD rats were randomly allocated to 7 groups ( n =9 in each group): Group A (control group), the animals inhaling room air for 24 h; Groups B, C and D, the animals inhaling 100% oxygen for 24 h, 12 h and 6 h respectively; Group E, the animals inhaling 100% oxygen for 24 h; Group F, the animals inhaling 100% oxygen for 12 h; Group G inhaling 100% oxygen for 6 h. All the rats of Groups A, B, C and D, 24 h after inhaling oxygen or room air were subjected to middle cerebral artery occlusion (MCAO). All the rats of Group E, after inhaling oxygen at once were subjected to MCAO. All the rats of Group F, 12 h after inhaling oxygen were subjected to MCAO; Group G 18 h after inhaling oxygen all rats subjected to MCAO. The MCAO (120 min) was induced by introducing a 3 0 nylon monofilament suture through internal carotid artery based on the Koizumi technique. The neurologic outcome was evaluated 24 h after the reperfusion. The infarct volume was then assessed by TTC staining. RESULTS In Group B, the neurologic outcome was better than the control group ( P < 0.05 ). There were no significant differences in neurologic outcome between Groups C, D, E, F, G and A. The infarct volume of Group B was significantly less than that of the control group ( P <0.01). There were no significant differences in infarct volume between other groups. CONCLUSION The present study was the first to demonstrate that preconditioning with 100% oxygen inhalation for 24 h could mimic ischemic preconditioning to induce ischemic tolerance in transient MCAO rats.