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编号:10264821
实验性癫痫大鼠海马损害与磁共振波谱对照研究
http://www.100md.com 《实用放射学杂志》 2000年第6期
     作者:叶静 张文波 祁吉 韩悦 廉宗澄 孙平川 黎明

    单位:叶静(华西医科大学附属第一医院精神科,四川 成都 610041);张文波 祁吉(天津医科大学第一中心医院放射科);韩悦 廉宗澄(天津医科大学第二医院MRI室);孙平川 黎明(南开大学吸附高分子研究所)

    关键词:氢质子磁共振波谱;癫痫;海马硬化;大鼠

    实用放射学杂志000601 [摘要] 目的:观察癫痫持续不同时间氢质子磁共振波谱(1H MRS)检测的致痫灶NAA和Cho异常与海马结构损害的相关性。方法:21只Wistar大鼠,实验组15只,10%Pilocarpine 350 mg/kg腹腔注射,诱发反复全面强直阵挛发作,光镜观察发作持续5 min至60 h大鼠海马区神经元和胶质细胞变化,并计数海马CA1和CA3段残存正常神经元数量;离体1H MRS测定代谢产物NAA和Cho含量变化。结果:癫痫持续(SE)5~30 min,光镜观察到神经元变性,1HMRS检测出NAA值降低;SE 30 min~3 h部分神经元坏死、少许丢失,轻度胶质增生,NAA明显降低;SE 3~6 h后,大部分神经元坏死、丢失,胶质增生明显,形成典型的海马硬化;除NAA值降低外,1HMRS还检测出Cho值升高。结论:1HMRS检出的NAA可反映癫痫脑损害程度,并且癫痫发作持续时间与NAA值和残存正常神经元数量呈显著的负相关。Cho值升高在海马硬化形成后检出,可能反映胶质增生。
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    [中图分类号]R742.1 [文献标识码] A

    [文章编号]1002-1671(2000)06-0323-04

    The Comparative Study of MRS and Hipocampal Damage in Epilepsy Model of Rat

    YE Jing,ZHANG Wen-bo,QI Ji,HAN Yue,LIAN Zong-cheng,SUN Ping-chuan,LI Ming

    (Department of Psychiatry,the First Hospitol,West China University of

    Medical Sciences,Chengdu 610041,Shichuan Province)
, 百拇医药
    [ABSTRACT] Objective:To study the relationship between hippocamal damage and abnormalities of NAA,Cho with 1HMRS.Methods:21 Wistar rats were injected with 10% pilocarpine intraperitoneal to induce generalized tonic-clonic seizure(GTCS).Six rats were used as control.According to status epilepticus(SE),the epileptic rats were divided into 4 groups.The brain samples were got 30 μm axial slices,stain with HE,observe the changes of histology in hippocampal regions with different seizure time,and the amount of remaining neurons in CA1 and CA3 of hippocampus were counted.The concentrations of NAA(N-acetyla-spatate)and Cho(cholin)were determined in vitro with 1HMRS.Results:After 5 min~30 min of SE,the neuronal degeneration were found,and concentration of NAA decreased.SE 30 min~3 hours,the amount necrotic neurons increased.There were small amount of neuronal loss and gliosis;The concentration of NAA increased significantly.After 3~6 hours of SE,most of neurons were disappeared and gliosis,then the typical hippocampal sclerosis was formed.Besides of the NAA decreased,the increased concentration of Cho was determined.Conclusion:The lasting time of seizure is negative correlation to the concentration of NAA and the amount of remained normal neurons,it is sensitive marker in indicating the brain damage.The increased concentration of Cho may imply gliosis.
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    [Key Words]:1H MRS; epilepsy; hippocampal sclerosis; rat

    1HMRS可无创性检出活体组织某些代谢产物含量变化。目前认为利用MRS可提高癫痫病人术前致痫灶检出率,但在活体得到致痫灶标本的困难给进一步研究MRS检测指标意义带来障碍。我们用10% Pilocarpine腹腔注射,诱发大鼠反复全面强直痉挛大发作(generalization tonic-clonic seizure GTCS),动态观察癫痫发作持续不同时间1HMRS所测的代谢产物N-乙酰天门冬氨酸(N-acetylaspartate,NAA)和胆碱(choline,Cho)含量与海马结构损害的相关性。

    1 材料与方法

    1.1 癫痫动物模型制作:Wistar大鼠21只,6只为对照组,15只为实验组。10%Pilocarpine 350 mg/kg腹腔注射,诱发大鼠反复全面强直痉挛发作,并制成癫痫持续状态(statue epilepsy SE),东莨菪碱1 mg/kg和安定4 mg/kg腹腔注射,将抽搐控制在不同时间,据此分4组(见附表)。
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    1.2 病理学观察:低温状态下取脑,沿大脑正中裂将前脑分离成左右两侧,其中一侧取海马组织,立即冷冻待处理;另一侧脑福尔马林固定,石蜡包埋,沿海马-杏仁核复合体层面制成30 μm层厚切片,HE染色,光镜观察海马组织学改变,并随机取海马CA1段5个和CA3段1个不连续高倍镜下(400倍)视野,计数存活正常神经元数量。

    附表 癫痫持续不同时间病理、1HMR检测结果 SE时间

    例数(只)

    5~30 min

    3

    30 min~3 h

    3

    3~6 h
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    3

    6~60 h

    6

    对照组

    6

    病

    理

    变性 +

    坏死 ±

    水肿 -

    +

    +

    ±

    +
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    ++

    ++

    +

    ++

    ++

    -

    -

    -

    细胞

    计数

    CA1 55.8±3.2

    CA2 47.1±5.4

    35.7±4.4*
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    30.3±8.2*

    9.6±1.6**

    11.0±2.6**

    5.4±3.2**

    9.4±5.3**

    71.6±7.2

    60.6±9.0

    1 H

    MRS

    NAA 0.8±0.06*
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    Cho 0.78±0.17

    0.81±0.11*

    0.84±0.29

    0.72±0.04**

    1.13±0.03*

    0.71±0.04**

    1.76±0.18*

    1.24±0.06

    0.76±0.28

    注:(1)细胞计数单位:个神经细胞 (2)NAA、Cho值为峰下面积与Cr峰下面积比值
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    (3)-无;±轻;+中;++重 (4)*P≤0.05,**P≤0.01

    图1 正常大鼠海马区1HMRS波谱,相应化学位移对应的化合物为:2.0ppm-NAA,3.0 ppm-Cr,3.2 ppm-Cho 积分法计算曲线下面积与Cr比值为:NNA/Cr 1.33 Cho/Cr 0.78

    1.3 离体1HMRS检测组织提纯:取冷冻脑标本,严格按Peeling方法[1]进行处理。提纯后的样品溶于0.5 ml氘代水中,用氘代盐酸和氘代氢氧化钠,校准PH=7.25±1;将处理好的样品放入5 mm MR管中,准备MRS检测。

    1HMRS检测:用美国Varian公司生产的UNITY Plus-400型(9.4 Tesla)NMR波谱仪。主要观察代谢产物NAA和Cho的波谱,用积分法测量峰的曲线下面积,其化合物的化学位移如(图1)。1HMRS的绝对定量是困难的,而Cr的值是稳定的[2,3],故每个化合物测得值与Cr值的比,可得到某一化合物的相对值[4,5],我们也用此方法来确定化合物相对含量。
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    1.4 统计学分析:用SPSS统计学软件,进行(1)方差分析,P<0.05为显著差异;(2)等级相关检验:SE持续时间与化合物相对含量及海马神经元丢失的相关性。

    2 结果

    表中显示,在SE 5~30 min内,海马区的病理学改变以变性为主,CA1和CA3区少许神经元丢失,但与对照组比较无显著性差异,此时已有NAA值减低;SE30 min~3 h神经元进一步损害,神经元丢失明显,轻度胶质细胞增生,NAA值减低,但无Cho值变化;SE 3~6 h后(包括6~60 h),光镜下观察到CA1和CA3区仅残存少量正常神经元,为变性、坏死神经细胞或由胶质细胞充填(图2),MRS检测发现显著NAA降低和Cho升高;经等级相关统计学检验,发作持续时间与海马CA1和CA3区残存神经元和NAA值呈显著负相关,(CA1区γs=-0.81,CA3区γs=-0.76),即发作持续时间越长,CA1和CA3区神经元丢失数量越多,NAA值越低,但与Cho值无显著相关性。
, 百拇医药
    图2 癫痫持续24 h,大鼠海马CA1区,大部分神经元坏死、脱失、胶质细胞增生,神经元胞浆及间质区水肿(HE×400)

    3 讨论

    以往的研究证明,在细胞质大分子的化学位移上,大鼠和人脑相似[6~9]。我们利用实验性癫痫大鼠的海马标本,进行1HMRS检测,来探讨脑代谢产物NAA和Cho的变化与致痫灶病理学改变的相关性。

    3.1 NAA:NAA完全位于神经元胞体和突触中[10,11],由线粒体产生[12,13],NAA含量减少反映神经元丢失或机能受损[10,14,15]

    本研究结果显示,癫痫发作早期(5~30 min)即有NAA信号减低,此期病理学改变以变性为主,表明NAA在反映神经元损伤上是敏感的。抽搐持续时间与残存神经元和NAA值呈负相关,反映出NAA作为定量指标对痫性脑损伤程度的反映能力,与其他学者研究结果一致,即NAA值减低量与神经元丢失相关[16,17],暗示临床可根据1HMRS检测的NAA值来判断癫痫所致脑损伤程度。
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    3.2 胆碱:Cho是磷脂酰胆碱卵磷脂和甘油磷酸胆碱的前驱物质,参与细胞膜构成[5]。细胞学研究提示,Cho存在于神经元和胶质细胞,其浓度胶质高于神经元,因而认为Cho主要反映神经胶质的变化。在癫痫病人检出Cho峰值升高被认为与海马萎缩和胶质增生有关。本实验显示SE 3 h后,Cho升高,病理结果提示神经元丢失严重,伴有严重的胶质增生。因此我们的实验也可以说明Cho峰值升高与海马硬化有关,与Cross[18],Connelly[19],等的研究结果一致。并且我们的结果还提示,通过1HMRS检出的Cho值在反映胶质增生的敏感性上低于NAA反映神经元损伤。因为本实验观察到,SE 30 min~3 h,有轻度胶质细胞增生,但1HMRS未检出Cho改变。病理学研究认为[20],一旦神经元损伤成为不可逆,随即有胶质细胞反应,并可持续数天至数月。Cho与神经病理的确切关系还须与基础研究相结合。

    基金项目:本课题由国家自然科学基金资助-批准号39700037
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    作者简介:叶静(1962- ),女,山东省宁津县人,天津医科大学影像医学博士,现华西医科大学附属第一医院精神科博士后,主治医师。

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, 百拇医药
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    收稿日期:1999-08-09, 百拇医药