【摘要】 目的探讨甲钴胺对缺血-再灌注大鼠脑组织半胱氨酸天冬氨酸酶3（Caspase-3）mRNA表达的影响。方法将大鼠按随机原则分为假手术组、模型对照组、尼莫地平组、甲钴胺小剂量组、甲钴胺大剂量组,每组30只。假手术组与模型对照组分别灌胃给予0.9%氯化钠溶液20 m L·kg^-1·d^-1;尼莫地平组灌胃尼莫地平1 mg·kg^-1·d^-1;甲钴胺小、大剂量组分别灌胃甲钴胺50,100μg·kg^-1·d^-1,给药1周。采用线栓法栓塞大脑中动脉3 h制作大鼠脑缺血-再灌注模型;观察再灌注24 h后神经功能缺损评分,于6,12,24 h用TUNEL法检测顶叶皮质细胞凋亡、反转录聚合酶链反应（RT-PCR）检测Caspase-3 mRNA的表达。结果模型对照组神经功能缺损评分为（2.70±0.52）分,尼莫地平组、甲钴胺小剂量组、甲钴胺大剂量组分别为（1.30±0.51）,（2.20±0.75）,（1.30±0.81）分,与模型对照组比较,均差异有统计学意义（P<0.05或P<0.01）;与尼莫地平组比较,甲钴胺大剂量组差异无统计学意义（P>0.05）,与甲钴胺小剂量组比较,甲钴胺大剂量组差异有统计学意义（P<0.05）。尼莫地平组、甲钴胺小、大剂量组各时间点神经细胞凋亡较模型对照组明显减少;甲钴胺大剂量组24 h时较尼莫地平组差异有统计学意义（P<0.01）;6²4 h较甲钴胺小剂量组差异有统计学意义（P<0.01或P<0.05）。假手术组Caspase-3 mRNA少量表达,与假手术组比较,模型对照组6²4 h Caspase-3 mRNA表达差异有统计学意义（P<0.01）;与模型对照组比较,尼莫地平组、甲钴胺大、小剂量组6²4 h Caspase-3 mRNA表达差异有统计学意义（P<0.05或P<0.01）;与尼莫地平组比较,甲钴胺大、小剂量组各时间点Caspase-3 mRNA差异无统计学意义（P>0.05）,与甲钴胺小剂量组比较,甲钴胺大剂量组于24 h差异有统计学意义（P<0.05）。结论甲钴胺对脑缺血-再灌注损伤保护机制与抑制Caspase-3 mRNA表达有关,且以大剂量效果较好。更多还原

【Abstract】 Objective To investigate the effects of methycobal on the expression of Caspase-3 in brain tissue after cerebral ischemia reperfusion in rats. Methods Rats were randomly divided into sham-operation group,model control group,nimodipine group and low-dose methycobal group,high-dose methycobal group（ n = 30 in each group）.Rats in the sham-operation group and model control group were administered intragastrically with 0.9% sodium chloride solution,rats in the nimodipine group were treated with 1 mg · kg^-1·d^-1of nimodipine,rats in the low- and high-dose of methycobal groups were given 50 and100 μg·kg^-1·d^-1of methycobal,respectively. The rat model of cerebral ischemia reperfusion was established by middle cerebral artery occlusion with suture method for 3 h.Neurological deficit scores were evaluated 24 h after reperfusion.The apoptosis of perifocal cortex cells was detected by TUNEL method and the expression of Caspase-3 was analyzed by RT-PCR 6,12 and 24 h after reperfusion. Results Neurological deficit scores in model control group,nimodipine group,low-dose methycobal group and high-dose methycobal group were 2.70 ± 0. 52,1. 30 ± 0. 51,2. 20 ± 0. 75 and 1. 30 ± 0. 81,respectively. Compared with model control group,neurological deficit scores were significantly different in the nimodipine group,low-dose methycobal group and high-dose methycobal group（ P<0.05 or P<0.01）. There were no significant differences between the high-dose methycobal group and nimodipine group（ P > 0. 05）. There was a significant difference between the high-dose methycobal group and low-dose methycobal group（ P < 0. 05）. The results of apoptosis by TUNEL were as follows: compared with model control group,the apoptosis decreased obvsiouly in the nimodipine group,low-dose methycobal group,and high-dose methycobal group at each time point.There was significant difference between the high-dose methycobal group and nimodipine group at the end of the 24thhours（ P<0.01）.Compared with low-dose methycobal group,there were significant differences in the high-dose methycobal group at the end of 6th,12 thand 24thhours（ P<0.01 or P< 0.05）. The results of RT-PCR were as follows: there was expression of caspase-3mRNA in the perifocal cortex of all groups,with weak expression in the sham-operation group.Compared with the sham-operation group,the expression of caspase-3 mRNA was increased significantly in the model control group（ P < 0. 01）. The expression of caspase-3 mRNA was reduced significantly in the nimodipine group,the low-dose methycobal group and high-dose methycobal group as compared with model control group at each time point（ P<0.05 or P<0.01）,but it was not significantly different in the low-dose methycobal group and high-dose methycobal group as compared with that of the nimodipine group（ P>0.05）.There were significant differences between the high-dose methycobal group and low-dose methycobal group at the end of 24 h（ P< 0.05）.Conclusion Methycobal can protect the brain cells from injury after cerebral ischemia reperfusion by adjusting the expression of Caspase-3m RNA,and the high-dose methycobal is more effective.更多还原