激光多普勒血流仪动态观察镁对脑缺血再灌注损伤保护作用

Protective effect of magnesium on brain with acute ischemia and reperfusion injury

目的:用激光多普勒血流仪动态观察硫酸镁对局灶性大脑中动脉阻塞(MCAO)大鼠模型缺血/再灌注损伤的保护作用。方法:体重280-300 g的雄性SD大鼠24只,传统线栓法制作单侧MCAO模型后根据硫酸镁处理时间不同分为4组,每组6只,分别为:缺血20 min、30 min、40 min硫酸镁处理组(25%硫酸镁160 mg/kg腹腔注射)和对照组(等体积生理盐水腹腔注射),激光多普勒血流仪实时动态监测各组不同时段的脑血流变化。4组动物模型均于缺血2 h+再灌注24 h后进行神经功能缺损评分,断头取脑,TTC染色观测脑片梗死灶体积。结果:再灌注后硫酸镁处理的各组脑血流均缓慢恢复至基线而后保持稳定,对照组脑血流随心跳波动明显,平均血流变化幅度有明显差异。平均脑梗死体积为:硫酸镁组26.5%、36.5%和24.5%,对照组为54.0%。神经功能缺损评分:硫酸镁组5.670±1.003、8.670±1.211和7.170±1.472,对照组11.170±0.983。结论:缺血早期给予硫酸镁对脑缺血和再灌注损伤具有一定的保护作用,其机制可能是通过改善脑血管的自动调节功能来实现的。

AIM： To dynamically observe the protective effect of magnesium on the brain with ischemia and reperfusion injury in the middle cerebral artery occlusion（MCAO） rat model using the device of laser Doppler flowmetry（LDF）.METHODS： Twenty-four Sprague-Dawley male rats（280-300 g） were used to establish MCAO model with the conventional line-embolism method.The rats were divided into 4 groups according to the initial time of peritoneal injection of magnesium sulfate（MgSO4）.The rats in MgSO4 groups were treated with 25% MgSO4 at 160 mg/kg at time points of 20 min,30 min and 40 min after ischemia.The rats in control group were treated with the same volume of normal saline.The real-time fluctuation of the local cerebral blood flow（CBF） was dynamically monitored by LDF.The degree of nervous functional defect was evaluated by calculating the neurological impairment score of the rats after suffered from 2 h ischemia and followed with 24 h reperfusion.All the rats were killed with an end breaking method,and the volumes of brain infarction were evaluated by TTC staining at the brain slices obtained by autopsy.RESULTS： The fluctuating features in 3 MgSO4 treatment groups were as follows： when reperfusion began,the local CBF appeared and increased smoothly,then approached to its baseline step by step,and kept at the stable level in the whole reperfusion period.The CBF in control group fluctuated sharply in the whole reperfusion period associated with the heart beating,which was significantly different from those in MgSO4 treatment groups.The average volume of brain infarction in MgSO4 treatment groups was 26.5%,36.5% and 24.5%,respectively,and was 54.0% in control group.The local nervous defect scores in MgSO4 treatment groups were 5.670±1.003,8.670±1.211 and 7.170±1.472,respectively,and was 11.170±0.983 in control group.CONCLUSION： Vasomotor functional improvement might be one of the protective mechanisms of magnesium on the brain with cerebral ischemia and reperfusion injury in acute ischemic stroke.