磁共振波谱评价脑缺血大鼠海马神经元损伤的实验研究

EXPERIMENTAL STUDY OF HIPPOCANPAL NEURONIC LESION IN ISCHEMIC RAT BY MAGNETIC RESONANCE SPECTROSCOPY

目的:应用磁共振波谱(MRS)观察大鼠大脑中动脉缺血(MCAO)再灌流后海马的迟发性神经元死亡,评价N-乙酰天门冬氨酸(NAA)能否准确反映神经元的损伤程度。方法:Wistar大鼠16只MCAO1h后再灌流及假手术对照组10只,6周后分别进行MRS和病理学的对比观察,根据海马的形态、及免疫组化结果对比分折磁共振波谱中NAA的对应性变化。结果:MCAO再灌流组大鼠缺血同侧海马的NAA、Cr及NAA/Cr的比值显著低于对侧和对照组,平均为2.05±0.33、2.42±0.41和0.86±0.10(对侧3.45±0.58、3.10±0.93、1.18±0.32;对照组3.42±0.43、3.57±0.47、0.98±0.14)。NAA下降的水平不能与病理显示海马CAl区神经元的脱失完全对应。结论:通过磁共振波谱的NAA显示MCAO再灌流后海马的迟发性神经元死亡。但神经元的丢失程度与NAA存在不完全对应性,这种变化可能与反应性星形胶质细胞增生密切相关。

Aim：To evaluate.N-acetylaspartate reflecting the neuronal lesion in middle cerebral atrety occlusion and reperfusion rat by magnetic resonance spectroscopy（MRS）.Methods：Sixteen adult Wistar rats with MCAO reperfusion and ten pseudooperaton rats were performed MRS in vivo at the sixth weeks ,then pathologic examination of HE staining and immunohistochemical staining were.We compared hippocampus modality ,cell density and immunohistochemical results with N-acetylaspartate,creatine changes and ration of NAA/Cr.Results：The values of NAA,Cr and NAA/Cr of ipsilateral hippocampus lesion in MCAO reperfusion rats（2.05±0.33、2.42±0.41and0.86±0.10）were visiblly decreased than contralateral hippocampsu（3.45±0.58、3.10±0.93、1.18±0.32）and control group（3.42±0.43、3.57±0.47、0.98±0.14）.But the level of decreased NAA is not corresponding to the degree of neuronal death in ipsilateral region of hippocampus in histochemistry.Conclusion：MRS has perfect explanation of cell metabolic changes in CA1 region.Decrease of NAA represented neuron delayed injury.But the edcreased level of NAA is not perfectly corresponded to the degree of neuron lost.This change has closed correlation with reactive astrocytes proliferation.