叶酸对局灶性脑缺血大鼠神经细胞凋亡的影响

目的观察叶酸(folic acid,FA)对局灶性脑缺血大鼠神经细胞凋亡的影响并探讨其作用机制。方法将32只成年雄性SD(Sprague-Dawley)大鼠随机分为假手术(SO)、大脑中动脉栓塞模型(MCAO)、缺血+叶酸低剂量(MCAO+FA-L)和缺血+叶酸高剂量(MCAO+FA-H)4组。除假手术组外,其他三组采用线栓法制作大鼠大脑中动脉栓塞(middle cerebral artery occlusion,MCAO)模型,各组于造模后D7处死。叶酸补充前、补充28d后(造模前)和造模后D7分别检测血清中丙二醛(MDA)含量、超氧化物歧化酶(SOD)和谷胱甘肽过氧化物酶(GSH-Px)活性;采用TUNEL法检测脑组织细胞凋亡率;Western blotting方法检测磷酸化细胞外信号调节激酶(extracellular signaling-related kinase,ERK1/2)蛋白表达水平。结果与缺血模型组比,低、高剂量叶酸均可明显减少脑组织中凋亡细胞率(P<0.01),降低血清中MDA含量(P<0.01),提高SOD、GSH-Px活性水平(P<0.01),并增加磷酸化ERK1/2蛋白的表达。结论叶酸能降低神经细胞凋亡率,其作用机制可能与增强自由基清除酶活性,抑制脂质过氧化反应,或上调磷酸化ERK1/2蛋白有关。

EFFECTS OF FOLIO ACID ON APOPTOSIS OF NEURAL CELLS IN RATS WITH FOCAL CEREBRAL ISCHEMIA INJURY

Objective To investigate the effects of folic acid on apoptosis of neural cells after focal cerebral ischemia injury in rats and the mechanisms.Method Thirty two adult male Sprague-Dawley(SD) rats were randomly divided into sham operation group(SO),middle cerebral artery occlusion group(MCAO),MCAO+ low dose folic acid group(MCAO+FA-L) and MCAO+ high dose folic acid group(MCAO+FA-H).The model of middle cerebral artery occlusion(MCAO) was set up by using intraluminal filament method.The rats were sacrificed at D7 day after cerebral ischemia.The apoptotic rate of neural cells was examined by TUNEL test,and the expression of pERK1/2 protein was detected by Western blotting method,The MDA content and serum SOD and GSH-Px activities in rats were measured before and 28d after folic acid treatment and 7th day after ischemia.Results Compared with ischemia group,the apoptotic rate of neural cells and MDA content in both folic acid supplemented groups were decreased significantly(P<0.01),and the activities of SOD and GSH-Px in serum and pERK1/2 protein expression in both folic acid treated group were increased significantly(P<0.01).Conclusion Folic acid can decrease apoptosis of neural cells of rats with cerebral ischemia,Through possible mechanisms of enhancing antioxidative enzymatic activities,inhibition of lipid hyperoxidation,and up-regulation of pERK1/2 protein expression,it has protective effect on the injury of ischemia.