氧化苦参碱对大鼠局灶性脑缺血损伤的保护作用及其抑制凋亡的作用机制

摘要

目的 探讨氧化苦参碱(oxymatrine,OMT)对大鼠局灶性脑缺血损伤的保护作用及其抑制凋亡的作用机制.方法 采用大鼠永久性大脑中动脉阻塞(permanent middle cerebral artery occlusion,pMCAO)方法,建立脑缺血模型,大鼠pMCAO术后通过腹腔给予OMT(30、60、120 mg·kg-1),以脑梗死体积、脑含水量和行为学症状等指标评价OMT对脑缺血的神经保护作用.通过HE染色方法观察OMT对缺血皮层神经细胞的形态变化以及数目的 影响;应用Western blot法检测OMT对缺血皮层Caspase-3、Bcl-2、Bax蛋白水平的表达.结果 在大鼠局灶性脑缺血体内模型中,OMT(30、60、120 mg·kg-1)可明显减小脑梗死体积、脑含水量和改善行为学体征(P<0.01).HE染色结果提示:OMT可明显增加神经细胞的存活率改善神经细胞的形态.Western blot 结果显示:与假手术组相比,大鼠pMCAO后3、6、12、24 h,缺血皮层Caspase-3、Bax蛋白的表达水平在3 h开始上升,24 h达到峰值;而Bcl-2的表达水平在3h开始下降,24 h降到最低.给予OMT后可下调pMCAO大鼠缺血皮层中Caspase-3、Bax蛋白,上调Bcl-2蛋白.结论 氧化苦参碱对脑缺血损伤有直接的神经保护作用,其机制可能通过上调Bcl-2及下调Bax 、Caspase-3蛋白水平抑制凋亡发生.%Aim To investigate the protection of oxymatrine on focal crerebral ischemic injury in rats and its mechanism of inhibition of opoptosis. Methods The method of permanent middle cerebral artery occlusion in rats ( permanent middle cerebral artery occlusion , pMCAO ) was adopted to establish cerebral ischemia model, Through the abdominal cavity pMCAO postoperative rats were given OMT ( 30,60,120 mg · kg-1 ). Evaluation index like cerebral infarction volume, water content and behavioral symptoms of brain were taken account in terms of OMT in cerebral ischemia neural protection. Through HE dyeing method the influence of OMT on form change and number of ischemic cortex of nerve cells was observed. Western blot was applied to detect OMT of ischemic cerebral cortex Caspase-3, Bcl-2, Bax protein level of expression. Results In rat focal cerebral ischemia body model, OMT ( 30, 60, 120 mg · kg-1 ) could significantly reduce the cerebellum infarction volume, water contentrnand improve brain behavior signs ( P < 0. 01 ). HE dyeing results indicated: OMT could significantly increase the survival rate of nerve cells and improve the form of nerve cells. Western blot results showed: compared with false surgery group, PMCAO rats after 3, 6, 12, 24 h, ischemic cortex Caspase-3, Bax protein expression level in 3 h began to rise and peaked at 24 h; Bcl-2 in the expression level 3h began to drop, 24 h to a minimum. After given the OMT, the levels of Caspase-3, Bax protein in PMCAO rat cortex ischemia could down-regulated and the levels of Bcl-2 protein up-regulated. Conclusions The current finding provide the first evidence that OMT has a direct neuropro-tective activity in cerebral ischemic neuronal injury, which is probably related to the inhibition of opoptosis by up-regulation of the levels of Bcl-2 and down-regulation of the levels of Bax and Caspase-3 singnal way.