基于扩散张量成像初探苍艾挥发油对大鼠脑缺血再灌注损伤的神经保护作用

李若阳; 朱静; 李彦橙; 王磊; 陈柏君; 熊磊; 郜发宝

doi:10.12182/20200960103

基于扩散张量成像初探苍艾挥发油对大鼠脑缺血再灌注损伤的神经保护作用

Basic Research on Neuroprotective Effect of Volatile Oil of Cang Ai after Cerebral Ischemia-Reperfusion Injury Based on Diffusion Tensor Imaging

摘要

摘要:
目的利用MRI扩散张量成像技术研究经鼻吸入苍艾挥发油对大鼠脑缺血再灌注损伤模型的神经保护作用。
方法 24只健康成年雄性 SD 大鼠，按照随机分配原则，分为假手术组、中动脉阻闭再灌注（middle cerebral artery occlusion, MCAO）组和苍艾挥发油（volatile oil of Cang Ai, VOCA）组。采用Zea Longa评分于造模后即刻和造模后第7天对各组大鼠神经功能损伤程度进行评估。用 7.0T磁共振对3组大鼠在造模成功后3 h、3 d、7 d行冠状位扩散张量成像（diffusion tensor imaging, DTI）扫描，对最大梗死层面的纹状体区和运动平层区DTI的表观扩散系数（apparent diffusion coefficient, ADC）和各向异性分数（fractional anisotropy, FA）进行测量，然后计算相对表观扩散系数(rADC)和相对各向异性分数（rFA）。造模7 d后采用 TTC 染色法对各组大鼠脑梗死体积进行评估，并对rFA、rADC与神经功能缺损评分进行相关性分析。
结果假手术组苏醒后无神经功能缺损，MCAO组与VOCA组均有不同程度神经功能缺损，造模后7 d时VOCA组神经功能缺损评分小于MCAO组（P<0.05）。DTI扫描结果显示，造模后3 h以及3 d，VOCA组大鼠纹状体rADC值均高于MCAO组（P<0.05），7 d时3组无明显差异（P>0.05）。VOCA组运动皮层区rADC值在造模后3 h高于MCAO组（P<0.01），3 d、7 d时差异无统计学意义。VOCA组纹状体rFA值在造模后3 d和7 d均高于MCAO组（P<0.05）。MCAO组与VOCA组大鼠运动皮层区rFA值在3个时间点的组间差异均无统计学意义。TTC染色结果显示假手术组无梗死区，VOCA组脑梗死体积小于MCAO组（P<0.05）。相关性分析显示MCAO组和VOCA组大鼠纹状体rFA值（r=−0.847）、运动皮层rADC值（r=−0.647）、运动皮层rFA值（r=−0.660）与神经功能缺损评分均呈明显相关性（P<0.05）。
结论 VOCA在脑缺血再灌注后能有效通过降低缺血区细胞的毒性水肿及加快神经纤维束恢复来保护MCAO大鼠的神经功能。rFA、rADC值可作为评价脑缺血再灌注后神经功能恢复的有效指标。

Abstract:
Objective To study the neuroprotective effect of inhalation of volatile oil of Cang Ai (VOCA) on cerebral ischemia-reperfusion injury model by MRI diffusion tensor imaging.
Methods Twenty-four healthy adult male SD rats were randomly divided into sham operation group, model (middle cerebral artery occlusion (MCAO) ) group and VOCA group. Evaluated the degree of neurological impairment of rats in each group immediately after successful establishment of model or 7 d later according to Zea Longa scoring. Coronal diffusion tensor imaging (DTI) scan was performed at 3 h, 3 d, and 7 d after the model successfully established by using 7.0 T magnetic resonance imaging. Measured the apparent diffusion coefficient (ADC) and anisotropy score (FA) of the DTI in the striatal region and the motion flat zone of the maximum infarct level and then calculate the relative apparent diffusion coefficient (rADC) and relative anisotropy score (rFA). TTC staining was used to evaluate the cerebral infarction volume of rats in each group at 7 d post model establishment, and the correlation analysis of rFA, rADC and neural score was performed.
Results No neurological defect was detected in mice in the sham operation group. The MCAO group and the VOCA group showed neurological defect to different degrees. The neurological function score of the VOCA group was obviously lower than that of MCAO group at 7^th day (P<0.05). The DTI scan results showed that the rADC value of striatum of rats in VOCA group was higher than that in MCAO group at 3 h and 3 d after modeling (P<0.05), while there was no significant difference between the three groups at 7^th day. The rADC value of the motor cortex in the VOCA group was higher than that in the MCAO group at 3 h after modeling (P<0.01), and there was no significant difference at 3^rdday and 7^thday. The rFA value of striatum in VOCA group was higher than that in MCAO group at 3^rd day and 7^th day after modeling (P<0.05). There were no significant differences in rFA value between the MCAO and the VOCA group at three time points. TTC staining results showed that there was no infarcted area in the sham operation group, and the infarct volume in the VOCA group was smaller than that of the MCAO group (P<0.05). Correlation analysis showed that the striatum rFA value was highly correlated with neurological scores (r=－0.847, P<0.01).
Conclusion For the first time, we found that VOCA can effectively protect the neurological function of MCAO rats by reducing the toxic edema of cells in the ischemic area and accelerating the recovery of nerve fiber bundles after cerebral ischemia and reperfusion. rFA and rADC values can be used as effective indicators to evaluate the recovery of nerve function after cerebral ischemia and reperfusion.

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