大豆异黄酮对脑缺血/再灌注诱导的线粒体损伤和脑细胞凋亡的影响

Effects of soybean isflavones on mitochondrial damage and neuronal apoptosis induced by cerebral ischemia/reperfusion

目的:研究大豆异黄酮(SI)对全脑缺血/再灌注大鼠脑组织线粒体超微结构、细胞凋亡和细胞色素C(Cyt-C)、caspase-3及caspase-9表达的影响,探讨大豆异黄酮对脑缺血/再灌注损伤的作用及机制。方法:60只健康成年SD大鼠随机分为假手术组(sham)、缺血再灌注组(I/R)和大豆异黄酮预处理组(SI)。SI组给予SI120 mg·kg-1·d-1连续灌胃21 d,其余2组用等体积生理盐水灌胃,每天1次,第22天I/R组和SI组行手术阻断三血管制备全脑缺血/再灌注模型。缺血1 h,再灌1 h后处死,取大脑皮层,光镜观察脑细胞形态学变化,透射电镜观察线粒体超微结构变化,流式细胞术检测细胞凋亡率,半定量RT-PCR法和免疫组织化学法测定脑组织中Cyt-C、caspase-9及caspase-3的表达。结果:I/R组线粒体膜崩解、嵴消失,脑细胞大量凋亡。与I/R组相比,大豆异黄酮预处理能明显改善线粒体超微结构的损伤,减少脑细胞凋亡率(P<0.01)。I/R组Cyt-C、caspase-9和caspase-3mRNA的表达和蛋白的含量高于sham组(P<0.01),与I/R组相比,SI组Cyt-C、caspase-9及caspase-3 mRNA和蛋白的表达显著降低(P<0.01)。结论:大豆异黄酮可能通过稳定线粒体结构,减少线粒体释放Cyt-C,降低caspase-9和caspase-3的表达,抑制细胞凋亡,从而减轻脑缺血/再灌注损伤。

AIM： To study the effects of soybean isoflavones on mitochondrial uhrastructure, neuronal apopto- sis and expression of cytochrome C, caspase-9 and caspase-3 in the rats with cerebral ischemia/reperfusion. METHODS： Adult healthy SD rats （n = 60） were randomly divided into 3 groups： sham group, ischemia/reperfusion injury （I/R） group and soybean isoflavone （SI） pretreatment group. Soybean isoflavones （120 mg kg 1 d l） were fed by gastric lay- age for 21 d. The global ischemia/reperfusion model of the rats was established by blocking 3 vessels, and then reperfused for 1 h after 1 h of ischemia. The morphological change of the cerebral cortex cells was observed under light microscope. The mitochondrial uhrastructure of the cerebral cortex ceils was determined by transmission electron microscope. The apop- totic rate of the cerebral cortex cells was detected by flow cytometry. The expression of cytochrome C, caspase-9 and caspase-3 in the cerebral cortex cells was determined by semi-quantitative RT-PCR and immunohistochemical techniques. RESULTS： Disintegration of mitochondria membrane and disappearance of the mitochondrial cristae were seen in I/R group. Compared with I/R group, the change of uhrastructure of mitochondria was significantly improved by soybean isofla- vone pretreatment, and the neuronal apoptotic rate was also significantly decreased （P 〈 0. 01 ）. The mRNA expression and protein content of cytochrome C, caspase-9 and caspase-3 in I/R group were obviously higher than those in sham group （P 〈 0. 01 ）. Compared with I/R group, the mRNA expression and protein content of cytochrome C, caspase-9 and caspase-3 in SI group were significantly decreased （ P 〈 0.01 ）. CONCLUSION ： Soybean isoflavones attenuate cerebral ischemia/reperfusion injury by stabilizing the structure of mitochondria, preventing cytochrome C release to the cytoplasm, inhibiting the activation of caspase-9 and caspase-3 and decreasing cell apoptosis.