木犀草素对缺氧缺血性脑损伤新生大鼠的神经保护作用

Neuroprotective effect of luteolin on neonatal rats with hypoxic-ischemic brain damage

目的:探究木犀草素(Lut)对缺氧缺血性脑损伤(HIBD)新生大鼠是否具有神经保护作用及其作用机制。方法:将7日龄新生大鼠分为假手术组、模型组(HIBD组)和Lut治疗组(HIBD+Lut组)。用Rice-Vannucci法建立新生大鼠HIBD模型。HIBD+Lut组在造模后即刻通过腹腔注射给予50 mg/kg Lut,连续3 d,模型组和假手术组同时腹腔注射等体积生理盐水。3 d后,用氯化三苯基四氮唑(TTC)染色评估脑梗死范围;用干/湿重脑含水量法评估缺血脑半球的脑水肿情况;用苏木精-伊红(HE)染色以及原位末端转移酶标记(TUNEL)和神经元核抗原(NeuN)荧光双标共定位法观察缺血脑半球海马和皮质中神经元损伤情况;用商用试剂盒检测缺血脑半球中超氧化物歧化酶(SOD)、谷胱甘肽过氧化物酶(GSH-Px)和过氧化氢酶(CAT)活性及丙二醛(MDA)水平;用Western blot法检测缺血脑半球的海马和皮质中核因子E2相关因子2(NRF-2)和血红素加氧酶1(HO-1)的蛋白表达水平。取35日龄大鼠,用水迷宫实验评估大鼠的认知功能情况。结果:与假手术组比较,HIBD组大鼠脑梗死、脑水肿、海马和皮质中神经元损伤均显著增加(P<0.05或P<0.01);而Lut治疗显著改善了HIBD大鼠的上述情况(P<0.05或P<0.01)。同时,Lut逆转了HIBD导致的缺血脑半球中SOD、CAT和GSH-Px活性降低和MDA水平升高(P<0.05或P<0.01)。Western blot结果显示,与假手术组比较,HIBD组缺血半球脑海马和皮质中NRF-2和HO-1的蛋白表达水平均增加(P<0.05或P<0.01);Lut治疗进一步增加了HIBD大鼠缺血半球海马和皮质中NRF-2和HO-1的蛋白表达水平(P<0.01)。结论:Lut可能通过抗氧化作用减轻HIBD新生大鼠脑梗死、脑水肿及皮质和海马CA1区神经元损伤,改善后期的认知功能。

AIM:To investigate the effects of luteolin(Lut)on hypoxic-ischemic brain damage(HIBD)in neonatal rats and its mechanism.METHODS:Seven-day-old neonatal rats were divided into sham group,model group(HIBD group)and Lut treatment group(HIBD+Lut group).The HIBD model of neonatal rats was established by Rice-Vannucci method.The rats in HIBD+Lut group were given 50 mg/kg Lut by intraperitoneal injection immediately after modeling for 3 consecutive days,while the rats in model group and sham group were intraperitoneally injected with the same volume of normal saline.Three days later,the size of cerebral infarction was evaluated by 2,3,5-triphenyltetrazo⁃lium chloride(TTC)staining.The cerebral edema of ischemic hemisphere was assessed by dry/wet weight brain water con⁃tent method.The injury of neurons in the hippocampus and cortex of ischemic cerebral hemisphere was observed by HE staining and TUNEL-NeuN fluorescence co-location.The activity of superoxide dismutase(SOD),glutathione peroxidase(GSH-Px)and catalase(CAT),and the content of malondialdehyde(MDA)in ischemic cerebral hemisphere were mea⁃sured with commercial kits.The expression levels of nuclear factor E2-related factor-2(NRF-2)and heme oxygenase-1(HO-1)proteins in the hippocampus and cortex of ischemic cerebral hemisphere were detected by Western blot.The cog⁃nitive function of 35-day-old rats was evaluated by water maze test.RESULTS:Compared with sham group,cerebral in⁃farction,cerebral edema,and neuronal injury in the hippocampus and cortex were all significantly increased in HIBD group(P<0.05 or P<0.01).However,the above situation of HIBD rats was significantly improved after Lut treatment(P<0.05 or P<0.01).Meanwhile,Lut reversed the decrease in SOD,CAT and GSH-Px activity and the increase in MDA con⁃tent in ischemic cerebral hemisphere induced by HIBD(P<0.05 or P<0.01).Western blot results showed that compared with sham group,the expression levels of NRF-2 and HO-1 proteins in the hippocampus and cortex of ischemic hemi⁃sphere in HIBD group were increased(P<0.05 or P<0.01),while Lut treatment further increased NRF-2 and HO-1 pro⁃tein expression levels in the hippocampus and cortex of ischemic hemispheres of HIBD rats(P<0.01).CONCLUSION:Treatment with Lut alleviates cerebral infarction,cerebral edema,neuronal damage in the cortex and hippocampal CA1 re⁃gion and later cognitive dysfunction in neonatal HIBD rats through antioxidant effect.