Department of Anesthesiology, University of Virginia, Charlottesville, VA 22908, USA.
Neuroscience. 2011 Dec 29;199:44-50. doi: 10.1016/j.neuroscience.2011.10.022. Epub 2011 Oct 20.
We have shown that isoflurane application at the onset of reperfusion (postconditioning) reduces brain ischemic injury in rats. This study was designed to determine whether this protection involved activation of prosurvival protein kinases and maintenance of normal mitochondrial membrane permeability. Two-month-old male rats were subjected to a 90-min middle cerebral arterial occlusion. They then were exposed or were not exposed to 2% isoflurane for 1 h. Ischemic penumbral cerebral cortex was harvested immediately and separated into the mitochondrial and cytosolic fractions. We showed that the mitochondrial nicotinamide adenine dinucleotide content in the ischemic penumbral cortex was significantly reduced, suggesting an increased mitochondrial membrane permeability. This increase was partly attenuated by isoflurane postconditioning. The mitochondrial adenosine diphosphate content in the penumbral cortex was reduced no matter whether the animals were postconditioned with isoflurane. The mitochondrial adenosine triphosphate concentration was not different among various experimental conditions. The phospho-Akt in the cytosolic and mitochondrial fractions of the ischemic penumbral cortex was higher than that in the control cortex. This increase trended to be higher in animals with isoflurane postconditioning. A similar change pattern was observed in the mitochondrial phospho-glycogen synthase kinase 3β, an Akt substrate that can regulate the mitochondrial membrane permeability. Isoflurane postconditioning reduced oxygen-glucose deprivation-induced injury of rat cortical neuronal cultures and increased phospho-Akt in these cells. The isoflurane postconditioning-induced protection in the neuronal cultures was decreased by the Akt inhibitor LY294002. These results suggest that isoflurane postconditioning effects may be mediated by Akt and involve reduced mitochondrial membrane permeability.
我们已经证明，在再灌注（后处理）开始时应用异氟醚可减少大鼠的脑缺血损伤。本研究旨在确定这种保护是否涉及激活存活蛋白激酶和维持正常的线粒体膜通透性。将 2 月龄雄性大鼠进行 90 分钟大脑中动脉闭塞。然后，他们暴露或不暴露于 2%异氟醚 1 小时。立即收获缺血半影脑皮质，并将其分离为线粒体和胞浆部分。我们表明，缺血半影皮质中的线粒体烟酰胺腺嘌呤二核苷酸含量显着降低，提示线粒体膜通透性增加。这种增加部分被异氟醚后处理减弱。无论动物是否用异氟醚后处理，半影皮质中的线粒体腺苷二磷酸含量都减少。各种实验条件之间的线粒体三磷酸腺苷浓度没有差异。缺血半影皮质的胞浆和线粒体部分中的磷酸化 Akt 高于对照皮质。这种增加在异氟醚后处理的动物中趋势更高。在 Akt 底物，可调节线粒体膜通透性的线粒体磷酸化糖原合成激酶 3β中观察到类似的变化模式。异氟醚后处理可减少氧葡萄糖剥夺诱导的大鼠皮质神经元培养物损伤，并增加这些细胞中的磷酸化 Akt。Akt 抑制剂 LY294002 降低了神经元培养物中异氟醚后处理诱导的保护作用。这些结果表明，异氟醚后处理的作用可能通过 Akt 介导，并涉及减少线粒体膜通透性。
