大鼠急性脑梗死后交叉性小脑神经机能联系不能DTI的评价

发布时间：2018-06-07 07:06

本文选题：脑梗死 + 磁共振扩散张量成像　；参考：《郑州大学》2013年硕士论文

【摘要】：背景和目的脑梗死是缺血性脑血管病(ischemic cerebro vascular disease, ICVD)的严重表现形式,是临床中枢神经系统最常见的疾病之一。随着社会老龄人口的增加,其发病率呈逐渐上升趋势,约占全部脑血管疾病的80%左右[2]。其高死亡率、高致残率及易复发性严重影响着人类的健康和生活质量,给社会及家庭带来巨大的精神和经济负担。近年来的研究发现,幕上局灶性的脑损伤也可引起远隔区域(丘脑、小脑等)的功能改变,磁共振成像(：magnetic resonance imaging, MRI)上可以表现为表观扩散系数和部分各向异性指数的改变。多数学者认为其发生机制可能与神经机能联系不能学说有关。脑梗死后交叉性小脑神经机能联系不能(crossed cerebellar diaschisis, CCD)是指幕上脑梗死导致对侧小脑半球血流量的降低,进而引起对侧小脑半球神经元活性下降及新陈代谢障碍的现象。大多学者认为此现象与皮质-桥脑-小脑(cortical-pons-cerebellum, CPC)通路的损伤有关。另外也有学者认为此现象与患者小脑血流动力学改变和迟发性小脑神经元死亡有关。磁共振弥散张量成像(diffusion tensor imaging, DTI)是在磁共振扩散加权成像(diffusion weighted imaging, DWI)的基础上基于平面回波成像(echo planar imaging, EPI)技术发展起来的一种新的、无创、可视化观察体内水分子微观扩散运动的磁共振成像的新技术,其通过测量水分子扩散的程度和方向来反映脑梗死后表观扩散系数及部分各向异性指数的改变,可以为脑梗死的早期诊断和治疗提供重要的参考价值。本研究采用改良的Longa线栓法,建立重复性高、稳定性强的大脑中动脉阻塞(middle cerebral artery occlusion, MCAO)模型。采用磁共振扩散张量成像技术,对大鼠脑MCAO后不同的时间点(1h、3h、6h、9h、12h、24h和72h)不同部位脑组织的表观扩散系数及部分各向异性分数情况进行检测,并与免疫组织化学检测与磁共振检查相应时间点、相应部位脑组织RGMa蛋白的表达对照。以此探讨：1、DTI参数值在MCAO后远隔区域不同时间点的扩散变化,从而为应用DTI技术来评价脑梗死后神经机能联系不能提供理论依据和实验基础。2、大鼠脑梗死后小脑改变的病理变化及其与磁共振信号改变的相关性。3、脑梗死后神经机能联系不能的相关机制。材料与方法 1、选取健康SD大鼠70只,体重为260g-300g,平均(286.2+8.9)g；将70只大鼠随机分为两组：实验组56只,参照Longa法建立左侧大鼠MCAO模型；对照组14只,仅暴露左侧的大脑中动脉,不插入线栓。 2、采用美国GE公司HDxt3.0T高场磁共振扫描机和大鼠专用线圈,对照组和实验组大鼠分别采集横轴位T1加权成像(T1-weighted imaging, T1WI)和T2加权成像(T2-weighted imaging, T2WI)、矢状位T2WI、DWI及DTI。依据磁共振横轴位T2WI扫描层面,在每个时间点分别选取2只大鼠,然后将鼠脑组织切成3mm厚的切片,运用免疫组化检测大鼠脑缺血梗死核心及远隔部位小脑RGMa蛋白的表达情况。 3、观察并记录左侧大脑半球梗死核心(基底节区)及双侧小脑半球脑组织在DWI图像上随时间的变化情况,并记录不同时间点脑扩散参数包括表观扩散系数(apparent diffusion coefficient, ADC)和部分各向异性指数(fractional anisotropic, FA)。比较1h、3h、6h、9h、12h、24h和72h实验组左侧基底节区和双侧小脑半球与正常对照组ADC值和FA值是否存在差异,及其随时间点的变化曲线。比较不同时间点实验组对侧小脑半球FA值与RGMa蛋白表达的相关性。 4、采用SPSS17.0统计软件进行统计学分析,计量资料采用X±SD表示。正常对照组与MCAO组计量资料比较采用两随机样本t检验,影像学与病理学指标的相关性采用Spearnman相关分析。以P0.05表示差异具有统计学意义。结果 1、大鼠MCAO后1h基底节ADC值、FA值开始降低,12h降至最低,后有所回升,但仍低于对照组。大鼠MCAO后各个时间点左侧基底节区及双侧小脑半球与正常对照组相比,ADC值和FA值降低,均具有统计学差异(P0.05)。双侧小脑ADC值及FA值的变化趋势与梗死核心区一致。梗死对侧小脑半球ADC值及FA值较梗死同侧小脑半球下降程度较大。 2、脑缺血后不同时相RGMa蛋白在左侧基底节区的表达均有所增加,可见棕黄色的RGMaP日性着色。局灶性脑缺血后1h RGMa P日性细胞在病灶区不断聚集,24h达高峰,RGMa阳性表达数目增多最为明显,在随后的72h内稍有下降,但与正常对照组相比仍持续高表达。双侧小脑半球RGMa蛋白表达与梗死核心区变化相似。梗死对侧小脑RGMa蛋白表达平均灰度值较梗死同侧小脑半球高。在对照组大鼠脉络丛、血管周围、小脑浦肯野细胞及脑干神经元中均可见RGMa蛋白阳性表达。 3、远隔部位RGMa蛋白表达上调与FA值下降呈负相关(P0.05,r=-0.341)。结论 1、幕上脑梗死后远隔区域可以发生神经机能联系不能现象。 2、远隔部位扩散参数随幕上梗死核心变化而变化,间接说明神经机能联系不能现象可能与神经传导通路有关。 3、脑缺血后,轴突导向分子RGMa蛋白的表达上调,说明RGMa参与轴突再生与修复过程。 4、双侧小脑半球RGMa蛋白和磁共振扩散参数的变化证实交叉性小脑神经机能联系不能存在。
[Abstract]:Background and purpose
Cerebral infarction is a serious manifestation of ischemic cerebrovascular disease (ischemic cerebro vascular disease, ICVD). It is one of the most common diseases of the clinical central nervous system. With the increase of the aging population of the society, the incidence of the cerebral infarction is increasing gradually, accounting for about 80% [2]. of all cerebrovascular diseases, high mortality, high disability rate and easy recurrence. Sex has a serious impact on human health and quality of life and brings great spiritual and economic burden to the society and family. In recent years, it has been found that the supratentorial brain damage can also cause functional changes in the distant regions (:magnetic resonance imaging, MRI), and can be shown as apparent diffusion system. Changes in the number and partial anisotropy index. Most scholars believe that the mechanism of its occurrence may be related to the inability of the neurologic connection. The cross cerebellar neurologic connection after cerebral infarction (crossed cerebellar diaschisis, CCD) refers to the reduction of the half of the cerebellum by the supratentorial cerebral infarction, which leads to the half of the cerebellum. Most scholars believe that this phenomenon is related to the damage to the cortical-pons-cerebellum (CPC) pathway. In addition, some scholars believe that this phenomenon is related to the changes in the hemodynamics of the cerebellum and the delayed cerebellar deity of the cerebellum.
Magnetic resonance diffusion tensor imaging (diffusion tensor imaging, DTI) is a new, noninvasive, visually observed magnetic resonance imaging of the microdiffusion motion of water molecules in the body based on the magnetic resonance diffusion weighted imaging (diffusion weighted imaging, DWI) based on the plane echo imaging (echo planar imaging, EPI) technology. Technology, by measuring the degree and direction of water molecular diffusion, reflects the apparent diffusion coefficient and the change of partial anisotropy after cerebral infarction, which can provide important reference value for the early diagnosis and treatment of cerebral infarction.
In this study, a modified Longa thread thrombus method was used to establish a high repeatability and stable middle cerebral artery occlusion (MCAO) model. The apparent diffusion coefficient and part of the brain tissue in different parts of the rat brain (1H, 3h, 6h, 9h, 12h, artery) were measured by magnetic resonance diffusion tensor imaging (MR diffusion tensor imaging). Detection of the heterosexual fraction, and compared with the expression of RGMa protein in the corresponding parts of the brain tissue with the corresponding time points of immunohistochemistry and magnetic resonance examination and the expression of RGMa protein in the corresponding parts of the brain. This is to discuss the diffusion of the parameters of the 1, DTI parameters at different time points in the distant region, so that the application of DTI to evaluate the neurologic connection after cerebral infarction can not be mentioned. For the theoretical basis and experimental basis.2, the pathological changes of the cerebellar changes after cerebral infarction and the correlation with the change of MRI signal.3, and the related mechanism of the neurologic function after cerebral infarction.
Materials and methods
1, 70 healthy SD rats were selected, with a weight of 260g-300g and an average of (286.2+8.9) g, and 70 rats were randomly divided into two groups: the experimental group was 56, and the Longa method was used to establish the left rat MCAO model. The control group was only exposed to the left middle cerebral artery and did not insert the thread thrombus.
2, the GE HDxt3.0T high field MRI scanner and the rat special coil were used, the control group and the experimental group were used to collect the transverse axis T1 weighted imaging (T1-weighted imaging, T1WI) and T2 weighted imaging (T2-weighted imaging, T2WI), and the sagittal position T2WI. 2 rats were selected and the rat brain tissue was cut into 3mm thick slices. The expression of RGMa protein in the nucleus of cerebral ischemia and the cerebellum in the distant part of the rat was detected by immunohistochemistry.
3, observe and record the changes in the DWI images of the left cerebral hemisphere infarct core (basal ganglia) and bilateral cerebellar hemisphere, and record the parameters of brain diffusion at different time points including the apparent diffusion coefficient (apparent diffusion coefficient, ADC) and the partial anisotropy index (fractional anisotropic, FA). Compare 1H, 3h, The ADC values and FA values of the left basal ganglia and bilateral cerebellar hemispheres in the experimental group of 6h, 9h, 12h, 24h and 72h were different, and their FA values were different, and their curves of change with time. The correlation between the FA value of the lateral cerebellar hemisphere and the expression of RGMa protein in the experimental group at different time points was compared.
4, statistical analysis was carried out with SPSS17.0 statistical software, and the measurement data were expressed in X + SD. The normal control group and the MCAO group were compared with the two random sample t test, and the correlation between the imaging and pathological indexes was analyzed by Spearnman correlation analysis. P0.05 indicated that the difference had the significance of unified planning.
Result
1, the ADC value of 1H basal ganglia after MCAO in rats was reduced, 12h decreased to the lowest, and then recovered, but it was still lower than that of the control group. The left basal ganglia and bilateral cerebellar hemisphere at each time point after MCAO were lower than the normal control group, the ADC value and FA value decreased, all of which were statistically different (P0.05). The trend of the bilateral cerebellar ADC value and FA value and the infarction were the stem. The ADC values and FA values in the contralateral cerebellar hemisphere were larger than those in the ipsilateral cerebellar hemisphere.
2, after cerebral ischemia, the expression of RGMa protein in the left basal ganglia increased, and brown yellow RGMaP diurnal coloring. After focal cerebral ischemia, 1H RGMa P daily cells gathered in the focus area, 24h reached the peak, the number of RGMa positive expression increased most obviously, slightly decreased in the following 72h, but compared with the normal control group. The expression of RGMa protein in bilateral cerebellar hemisphere was similar to that of the infarct core region. The mean gray value of RGMa protein expression in the cerebellar cerebellum was higher than that of the ipsilateral cerebellar hemisphere. The positive expression of RGMa protein was found in the choroid plexus, the perivascular, the cerebellar Purkinje cells and the brainstem neurons in the control group.
3, the up regulation of RGMa protein was negatively correlated with the decrease of FA value (P0.05, r=-0.341).
conclusion
1, after supratentorial cerebral infarction, there can be neurotic dysfunction in remote areas.
2, the distant site diffusion parameters change with the core changes of supratentorial infarction, which indirectly indicates that neurologic inability may be related to the nerve conduction pathway.
3, after cerebral ischemia, the expression of RGMa protein was up-regulated, indicating that RGMa participates in axonal regeneration and repair.
4, the changes of RGMa protein and MRI diffusion parameters in bilateral cerebellum proved that cross cerebellar nervous function connection could not exist.
【学位授予单位】：郑州大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：R743.33;R445.2

【参考文献】