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目的观察强力霉素对脑缺血再灌注MMP-9活性的影响,探讨其对神经元的保护作用。方法利用大脑中动脉线栓法(middle cerebral artery occlusion,MCAO)制备局灶性脑缺血再灌注模型,SD大鼠分为假手术组、生理盐水组、强力霉素组,每组18只。激光多普勒血流仪分别检测大鼠手术前、MCAO时、再灌注24 h大脑中动脉脑血流;再灌注24 h时应用TTC染色法观察大鼠脑梗死体积;明胶酶谱法检测缺血区脑组织MMP-9活性变化;透射电镜观察缺血区脑组织神经元超微结构。结果生理盐水组与强力霉素组大鼠在再灌注24 h时脑血流[分别为基础值的(57.98±4.20)%、(59.23±3.30)%]与MCAO时[分别为基础值的(22.94±3.16)%、(21.63±3.46)%]差异显著(P<0.01),但在同一时间点两组间无显著差异(P>0.05);强力霉素组大鼠脑梗死体积[(9.77±2.68)%]与生理盐水组[(33.44±4.50)%]相比显著减少(P<0.01);生理盐水组大鼠MMP-9活性(5.95±0.73)与假手术组(1.21±0.15)相比显著升高(P<0.01),应用强力霉素后MMP-9活性(2.47±0.42)与生理盐水组相比显著降低(P<0.01);生理盐水组大鼠神经元超微结构发生异常改变,强力霉素组大鼠神经元形态结构基本正常。结论强力霉素抑制MMP-9活性对大鼠局灶性缺血再灌注损伤脑组织具有保护作用。
Objective To observe the effect of doxycycline on the activity of MMP-9 after cerebral ischemia-reperfusion and to explore its protective effect on neurons. Methods The model of focal cerebral ischemia-reperfusion was established by middle cerebral artery occlusion (MCAO). The rats were divided into sham-operated group, saline group and doxycycline group, 18 rats in each group. Laser Doppler flowmetry was used to detect cerebral blood flow in middle cerebral artery of MCAO rats before reperfusion and 24 h after reperfusion. TTC staining was used to observe cerebral infarction volume 24 h after reperfusion. Gelatin zymography The changes of MMP-9 activity in blood were observed by transmission electron microscopy. The ultrastructure of neurons in the ischemic area was observed by transmission electron microscopy. Results Compared with MCAO group, the values of cerebral blood flow [(57.98 ± 4.20)% and (59.23 ± 3.30)% respectively) in the saline group and the doxycycline group at 24 h after reperfusion (P <0.01), but there was no significant difference between the two groups at the same time point (P> 0.05); The volume of cerebral infarction in the doxycycline group [(9.79 ± 3.16)%, (21.63 ± 3.46)%] ± 2.68)%] was significantly lower than that in the saline group [(33.44 ± 4.50)%] (P <0.01). The MMP-9 activity in the saline group was significantly lower than that in the sham operation group (1.21 ± 0.15) (P <0.01). The activity of MMP-9 after applied with doxycycline (2.47 ± 0.42) was significantly lower than that of saline group (P <0.01). The ultrastructure of neurons in NS group Abnormal changes in the doxycycline group of neurons morphology was normal. Conclusion Doxycycline inhibits the activity of MMP-9 in rats with focal cerebral ischemia-reperfusion injury.