神经生长因子对兔局灶性脑缺血再灌注神经功能修复的影响和MR影像学评价

The effect of nerve growth factor on neural functional recovery in focal cerebral ischemia reperfusion injury in rabbits and evaluation with MR imaging

目的:研究神经生长因子(NGF)对兔局灶性脑缺血再灌注损伤神经功能修复的影响,并利用MR成像技术进行评价。方法:采用兔大脑中动脉阻断(MCAO)局灶性脑缺血再灌注模型,分别在缺血2h再灌注损伤后0、1、3和6h应用微量进样器将NGF立体定向导入梗死灶周,于再灌注72h,应用MR影像学、TTC染色和流式细胞术评价兔梗死体积、水肿体积、表观弥散系数(ADC)及神经功能缺损和凋亡状态。结果:缺血再灌注0h、1h、3h和6h灶周给予NGF,梗死体积分别比对照组下降50.1%、48.4%、37.6%和13.7%。同时再灌注3h内应用NGF水肿体积、神经功能缺损评分、灶周凋亡率及caspase-3含量明显下降,梗死中心区及灶周ADC比率(ADCR)升高;再灌注6h后给药,则无明显作用。相关分析显示各组灶周ADCR与灶周凋亡率具有明显负相关。结论:NGF对兔局灶性脑缺血再灌注损伤有保护作用,抑制caspase-3活性的表达和细胞凋亡是其保护机制之一,MR影像学检查可作为定量评价基因疗效的可靠指标。

Objective： To investigate the influence of NGF on neural functional recovery in focal cerebral ischemia reperfusion injury in rabbits and evaluate with MR imaging. Methods： Focal cerebral ischemia was induced according to the middle cerebral artery occlusion （MCAO） method. After 2h of MCAO and at different time points 0, 1, 3 and 6h post reperfusion, the NGF was administered respectively. Infarct and edema volumes, apparent diffusion coefficient （ADC） were assessed by 2, 3, 5-tfiphenylterazolium chloride （TTC） staining and MRI 72h after reperfusion. We measured neural cell apoptosis and activation of caspase-3 in the perifocal regions of cerebral ischemic by flow cytometry （FCM） and neurological deficit score. Results： NGF reduced infarct volumes compared with normothermic controls by 50. 1 %, 48. 4%, 37.60% and 13.7% when administered NGF at Oh, 1h, 3h and 6h after reperfusion. Edema volumes, neurological deficit score, the percentage of apoptotic cell and activation of caspase-3 in the perifocal regions were significantly lower than that in control group when adeministered NGF 0, 1 and 3h after reperfusion （P〈0.01）. There was no difference when administered NGF at 6h after reperfusion. ADC ratios were correlated significantly and negatively with activation of caspase-3 in the perifocal regions （P〈0.01）. Conclusion： NGF has protective effects on focal cerebral ischemia/reperfusion. Inhibiting the expression of caspase-3 and neuronal apoptosis may be one of the possible mechanisms of the event. MRI could quantitativeiy evaluate the effect gene therapy in vivo.