大豆异黄酮对大鼠局灶性脑缺血再灌注损伤的保护作用及其机制研究

The protective effects and mechanism of soybean isoflavone on focal cerebral ischemia-reperfusion injury in rats

目的:研究大豆异黄酮(Soybean Isoflavone,SI)对大鼠局灶性脑缺血再灌注损伤的保护作用,并探讨其作用机制。方法:采用线栓法制备局灶性脑缺血再灌注大鼠模型,选取120只随机分为6组:局灶性脑缺血再灌注模型组、大豆异黄酮(20、40、80和160 mg/kg)腹腔注射预处理组和舒血宁注射液(4mg/kg)阳性对照组,并设假手术组。再灌注6h后,采用盲法进行神经功能评分,测定脑梗死体积(IV%)及脑组织含水量;通过HE染色法观察脑组织病理形态学改变,通过TUNEL染色观察神经细胞凋亡状况并计算凋亡指数(Apoptosis Index,AI);通过生化分析仪测定血清中肌酸激酶(CK)、乳酸脱氢酶(LDH)含量;检测脑组织中超氧化物歧化酶(SOD)、谷胱甘肽过氧化物酶(GSH-Px)、过氧化氢酶(CAT)活性和丙二醛(MDA)含量。结果:与假手术组相比,局灶性脑缺血再灌注模型组大鼠出现明显的行为障碍,脑梗死体积(IV%)和脑组织含水量显著升高,脑组织出现明显的病理性改变,神经细胞凋亡状况加重,凋亡指数显著升高;血清中CK,LDH含量显著升高,脑组织中SOD、GSH-Px、CAT活性显著降低且MDA含量显著升高,差异均具有统计学意义。与局灶性脑缺血再灌注模型组相比,大豆异黄酮(40、80和160 mg/kg)组大鼠行为障碍明显好转,大豆异黄酮(80和160 mg/kg)组脑梗死体积和含水量均显著降低;大豆异黄酮预处理组大鼠脑组织病变和神经细胞凋亡均明显减轻,以160 mg/kg组效果最为显著,大豆异黄酮(80和160 mg/kg)组凋亡指数显著降低;大豆异黄酮(40、80和160 mg/kg)组大鼠血清中CK,LDH含量和脑组织中MDA含量均显著降低;大豆异黄酮(80和160 mg/kg)组脑组织中SOD、CAT活性显著降低,且160mg/kg组GSH-Px活性显著降低。结论:大豆异黄酮能够有效改善局灶性脑缺血大鼠神经功能障碍、降低脑梗死体积和脑组织含水量、改善脑组织病变和神经细胞凋亡状况,提示大豆异黄酮对大鼠局灶性脑缺血再灌注损伤具有剂量依赖性的保护作用,其作用机制可能与大豆异黄酮能够有效改善抗氧化酶活性、提高机体清除自由基能力、抑制氧化应激损伤有关。

Objective： To investigate the protective effects and mechanism of soybean isoflavone（ SI） focal cerebral ischemia-reperfusion injury in rats. Methods： 120 focal cerebral ischemic reperfusion rat models established with Zea-Longa occluding suture were randomly divided into six groups： focal cerebral ischemic- reperfusion control group,SI（ 20,40,80,120 mg / kg） pre-treated groups,Shuxuening（ 4mg / kg） pretreated group,and selected another 20 same-aged rats as sham operation group. 6h after reperfusion,the neurological deficits,ratio of infarct volume,water content of the brain were evaluated; the histopathological changes and neurocyte apoptosis were observed,and the AI were determined. The content of CK,LDH in serum were determined; the activity of SOD,GSH-Px,CAT and the content of MDA in brain tissue were determined. Results： Compared with sham operation group,the neurological scores of focal cerebral ischemia-reperfusion control group was significantly decreased（ P〈0. 01）,the ratio of infarct volume and water content of the brain were significantly increased（ P〈0. 01）,the histopathological changes of brain tissue and the neurocyte apoptosis was appeared,and the AI was significantly increased（ P〈0. 01）;the content of CK,LDH in serum were significantly increased（ P〈0. 01）; and the activity of SOD,GSH-Px,CAT in brain tissue were significantly decreased（ P〈0. 01）,and the content of MDA was significantly increased（ P〈0. 01）. Compared with focal cerebral ischemiareperfusion control group,the neurological scores of SI（ 40,80 and 120 mg / kg） pre-treated groups were significantly decreased（ P〈0. 05,P〈0. 01）,and the ratio of infarct volume and brain water content of SI（ 80,120 mg / kg） pre-treated groups were significantly decreased（ P〈0. 05,P〈0. 01）,the histopathological changes and neurocyte apoptosis of SI pre-treated groups were significantly improved,and the AI of SI（ 80,120 mg / kg） pre-treated groups were significantly decreased（ P〈0. 05,P〈0. 01）. The content of CK,LDH in serum and MDA in brain tissue in SI（ 40,80 and 120 mg / kg） pre-treated groups were significantly decreased（ P〈0. 05,P〈0. 01）; the activity of SOD,CAT in brain tissue of SI（ 80,120 mg / kg） pre-treated groups were significantly increased（ P〈0. 05,P〈0. 01）,and the activity of GSH-Px in SI 120 mg / kg pre-treated group was significantly increased（ P〈0. 05）. Conclusion： SI could effectively lower the neurological scores,decrease the ratio of infarct volume and water content of the brain tissue,improve the histopathological changes and neurocyte apoptosis,suggesting that SI had dose-dependent protective effects on focal cerebral ischemic-reperfusion injury in rats,which was perhaps related with its pharmacological effects of enhanceing the activity of antioxidant enzymes and depressing the oxidative stress injury.