异丙酚对大鼠局灶性脑缺血再灌注后Ca2＋诱发神经元线粒体损伤的影响

The effects of propofol on Ca2＋ -induced mitochondrial dysfunction after focal cerebral ischemia-reperfusion injury in rats

目的评价异丙酚对大鼠局灶性脑缺血再灌注后Ca2＋诱发神经元线粒体损伤的影响。方法健康雄性Wistar大鼠84只，体重250～300g，随机分为4组（n=21），假手术组（S组）仅暴露颈内动脉但不结扎颈总动脉；缺血再灌注组（IR组）、CaCl3组和异丙酚组（P组）采用结扎颈总动脉的方法建立大鼠局灶性脑缺血再灌注模型，缺血2h，再灌注24h。缺血2h时进行神经功能缺陷评分。再灌注24h时处死大鼠，分离额叶皮质，提取神经元线粒体。CaCl2组加入CaCl2200umol／L于37℃下孵育5min；P组加入异丙酚200umol／L于37℃下孵育2min后，再加入CaCl2 200umol／L孵育5min。透射电镜下观察线粒体超微结构。采用紫外分光光度法检测线粒体通透性转换孔（MPTP）的活性。结果S组神经功能缺陷评分为0分，IR组、CaCl2组和P组神经功能缺陷评分为2—3分。CaCl2组线粒体明显肿胀，基质电子密度低，嵴大部分断裂，线粒体膜崩解；P组较CaCl2组病理学损伤减轻。与S组比较，IR组和CaCl2组MPTP活性升高，P组MPTP活性降低（P〈0．05）；与IR组比较，CaCl2组MPTP活性升高，P组MPTP活性降低（P〈0．05）；与CaCl2组比较，P组MPTP活性降低（P〈0．05）。结论异丙酚可减轻大鼠局灶性脑缺血再灌注后Ca2＋诱发的神经元损伤，与其抑制MPTP的开放有关。

Objective To investigate the effects of propofol on Ca2＋ -induced mitochondrial dysfunction after focal cerebral ischemia-reperfusion（IR） injury in rats. Methods Eighty-four male Wistar rats weighing 250- 300 g were randomly divided into 4 groups （ n = 21 each） ： group I sham operation （group S） ; group II IR; group m CaCl2 and group IV propofol （group P） . In group II -IV focal cerebral IR was induced by 2 h middle cerebral artery occlusion （MCAO） followed by 24 h reperfusion. Neurological function was assessed at 2 h of ischemia and scored （0 = no deficit, 5 = death）. The animals were decapitated at the end of 24 h reperfusion. Left parietal and frontal cortex were immediately isolated and mitochondria were extracted. In group III and IV mitochondria were incubated with 200 umol/L CaC12 for 5 min at 37 ℃ , and were pretreated with propofol 200umol/L in group IV for 2 min before CaCl2 . Morphological changes of mitochondria were examined by electron microscopy. Mitoehondrial permeability transition pore （MPTP） activity was detected by ultraviolet visible absorption spectroscopy. Results Mitochondrial ultrastructure was normal in group I . Significant mitochondrial swelling, disrupted cristae and membrane rupture were observed in group III . Propofol significantly attenuated the Ca2＋ -induced changes. The MPTP activity was significantly increased in group II and III as compared with group I but were significantly decreased in group IV （propofol group）. The decrease in MPTP activity was attenuated in group IV as compared with group III . Conclusion Propofol can improve mitochondrial dysfunction induced by Ca2＋ after focal cerebral IR by inhibiting MPTP opening in rats.