神经生长因子对兔局灶性脑缺血再灌注损伤的治疗时间窗及MR影像学评价

目的研究神经生长因子(NGF)对脑缺血再灌注损伤保护作用的有效时间窗,同时利用MR成像技术对其进行评价。方法采用兔大脑中动脉阻断(MCAO)局灶性脑缺血2 h再灌注72 h模型,分别于缺血再灌注0、1、36、h应用微量进样器将NGF立体定向导入梗死灶周,并于再灌注不同时间点应用MR影像学、TTC染色和流式细胞术评价家兔梗死体积、神经功能缺损和凋亡状态。结果缺血再灌注0、13、h组梗死灶周注射NGF后,经MRI检查所测梗死体积分别为(229.9±17.1)(、260.7±24.2)、(314.6±25.3)mm3,与对照组(468.6±29.7)mm3]比较差异有统计学意义(均P<0.01);缺血再灌注6 h组梗死体积为(441.1±14.8)mm3,与对照组比较差异无统计学意义(P>0.05)。采用TTC染色所测梗死体积与MRI检查结果一致。脑缺血再灌注3 h内注射NGF,其神经功能缺损评分明显降低,凋亡率明显下降;再灌注6 h后注射NGF则无明显作用。结论NGF对兔局灶性脑缺血再灌注损伤的有效时间窗为再灌注损伤3 h内,MR影像学检查可作为定量评价基因疗效的可靠指标。

Study on Therapeutic Time Window of Opportunity for NGF following Focal Cerebral Ischemia/Reperfusion Injury in Rabbit by MRI

Objective To study the therapeutic time window of opportunity for NGF following focal cerebral ischemia /reperfusion injury in rabbits and the effectiveness was evaluated by advanced MR image technology.Methods Focal cerebral ischemia 2 h /reperfusion 72 h model in rabbits was induced by transient occlusion of middle cerebral artery(MCA) for 2 h and reperfusion for 72 h.The NGF was administered at 0 h,1 h,3 h and 6 h after reperfusion respectively.Infarct volumes were assessed by 2,3,5-triphenylterazolium chloride(TTC) staining and MRI scanning at different time after reperfusion.We measured neural cell apoptosis in the cerebral ischemic penumbra by flow cytometry(FCM) and neurological deficit scores were also recorded.Results When administered NGF at 0 h,1 h,3 h after reperfusion,infarct volumes,neurological deficit scores and the percentage of apoptotic cell were significantly lower than that in control group(P<0.01).There was no difference when administered NGF at 6 h after reperfusion.Conclusions The therapeutic time window of opportunity for NGF following focal cerebral ischemia/reperfusion injury in rabbit was not more than 3 h after reperfusion.MRI could be qualitatively evaluated the effect of gene therapy in vivo.