甲基泼尼松龙在大鼠局灶性脑缺血再灌注损伤中的保护作用

Protective effect of methylprednisolone on brain ischemia-reperfusion injury in rats

目的探讨甲基泼尼松龙(methylprednisolone,MP)对大鼠局灶性脑缺血再灌注损伤中脑神经元细胞凋亡的影响,并探讨其可能的机制。方法SD雄性大鼠84只,随机分为假手术组(Sham组)、缺血再灌注组(I/R组)、MP组,制造大脑中动脉阻塞模型,缺血2h后再灌注3、6、12、24h。MP组于再灌注时腹腔注射MP30mg/kg。光镜和电镜下观察脑组织神经细胞形态学变化,免疫组化法检测半胱氨酸天冬氨酸蛋白酶-3(caspase-3),血红素氧合酶-1(HO-1)的蛋白表达,流式细胞仪Annexin-V-PI双染法测定神经细胞凋亡率。结果I/R组与Sham组相比,脑组织细胞凋亡率显著增加(P<0.01),caspase-3,HO-1蛋白表达明显上升(P<0.05或P<0.01);MP组与I/R组相比,神经细胞凋亡率显著减少(P<0.01),caspase-3的表达明显降低(P<0.01),HO-1表达显著增加(P<0.01)。细胞病理形态改变在24h最严重,经MP处理后损伤明显减轻。结论MP可能通过诱导缺血再灌注损伤后脑组织细胞中HO-1的高表达,从而抑制细胞凋亡来减轻脑缺血再灌注损伤。

Objective To investigate the effects of methylprednisolone（MP）on neuronal apoptosis during focal cerebral ischemiareperfusion injury in rats and to study the possible role of MP in pneumocyte apoptosis. Methods Eightyfour male SpragueDawley rats were randomly divided into three groups： sham operation group（Sham group）, ischemiareperfusion group（I/R group）,and MP group. The model of focal cerebral ischemiareperfusion injury was induced by suture method （ischemia for 2 h,and reperfusion for 3,6,12,24 h respectively）. MP was intraperitoneally injected with a dose of 30 ml/kg before reperfusion in MP group. The apoptosis rate in nerve cell was detected by the way of AnnexinVPI in flow cytometer. The expression of caspase3 and heme oxygenose1（HO1） were measured by immunohistochemical stain, and the mean optical density （OD） values of positive fields were examined quantitatively by image analysis system. The pathological and ultrastructure changes of cerebral tissue were also observed. Results The rate of apoptosis and the expression of caspase3 and the expressin of HO1 in I/R group and MP group were significantly higher than those in sham group （P〈0.05 or P〈0.01）,while the rate of apoptosis and the expression of caspase were higher and the expression of HO1 was lower in I/R group than those in MP group（P〈0.01）.The pathological and ultrastructure change of cerebral tissue was better in MP group than that in I/R group. Conclusions MP has a protective effect on cerebral ischemiareperfusion injury by reducing the neuronal apoptosis, and the mechanism may be related to the higher expression of HO1,which reduces oxidative damage, and inhibits the neuronal apoptosis.