18β-甘草次酸对局灶性脑缺血再灌注损伤的保护作用

Neuroprotective effects of 18β-glycyrrhetinic acid against focal cerebral ischemia reperfusion injury in rats

目的:探讨中药甘草提取物18β-甘草次酸(18β-GA)对脑缺血再灌注损伤的保护作用及其机制。方法:线栓法制备大鼠局灶性脑缺血/再灌注损伤模型,随机分为假手术组、中脑动脉闭塞(MCAO)模型组、依达拉奉(50 mg·kg^(-1))阳性药对照组、18β-GA 50 mg·kg^(-1)、18β-GA 100 mg·kg^(-1)和18β-GA 150 mg·kg^(-1)组,于缺血1 h、再灌注后5 h分别腹腔给药。采用Zea Longa法进行神经功能评分,TTC染色比较各组动物脑梗死体积差异,分别用HE染色和TUNEL染色观测组织病理损伤以及神经元细胞凋亡,Western blot技术检测大鼠海马组织凋亡关键分子Caspase-3蛋白表达,ELISA检测大鼠海马炎性因子IL-1,IL-6和TNF-α表达水平,分光光度法检测大鼠海马MDA和SOD活性。结果:与MCAO大鼠相比,18β-GA 100 mg·kg^(-1)和18β-GA 150 mg·kg^(-1)组均可显著减少脑缺血再灌注大鼠脑梗死体积,降低神经功能缺损评分,可显著改善MCAO大鼠海马神经元细胞核固缩、排列紊乱、细胞死亡等病理损伤,抑制海马神经元Caspase-3的表达及抑制细胞凋亡,降低MCAO大鼠海马炎性因子IL-1,IL-6和TNF-α表达水平,降低MDA水平以及提升SOD活性,与阳性药依达拉奉效果相当。结论:18β-GA可能通过抑制炎症反应及氧化应激,从而减轻脑组织细胞凋亡及脑损伤,实现对大鼠局灶性脑缺血再灌注损伤的神经保护作用。

Objective： We investigated the neuroprotective effect of 18β-glycyrrhetinic acid （18β-GA） against ischemia-reperfusion （I/R） injury in cerebral neurons in Sprague-Dawley rats. Methods： 18β-GA （50, 100 or 150 mg·kg^-1, i.p. ） was administered 1 h after the start of ischemia and 5 h after reperfusion. Neurological deficit scores and infarct volumes were evaluated 24 h later. Neuronal apoptosis was assessed by performing terminal deoxynucleotidyl transferase-mediated dUTP-nick end labeling （TUNEL） staining, and pathological brain damage was estimated by performing hematoxylin and eosin staining. In addition, Caspase-3 protein expression was detected with Western blot. Results： 18β-GA significantly reduced the brain infarct area, resolved neurological deficit, reduced the pathological damage, and ameliorated neuronal apoptosis in hippocampal CA1. It also significantly reduced the levels of Caspase-3 protein expression. Conclusion： These results indicated that 18β-GA is neuroprotective and may be useful in reducing the damage caused by stroke.