大脑皮层下轴突纤维横断模型的建立

目的　建立一种机械性大脑皮层下轴突纤维横断动物模型。方法　对 1 0例正常 2 1 0～2 4 0 g雄性SD大鼠的大脑皮层厚度和第V层神经元深度进行测定。根据测定结果决定三组不同的横切深度 (每组用SD大鼠 8只 )。在立体定位下进行脑皮层下轴突纤维横断 ,观察动物术后肢体功能恢复情况。 1 7d后取脑进行切片和染色 ,对横切深度进行测量 ,并对神经元和神经纤维状况进行观察。结果　正常 2 1 0～ 2 4 0g雄性SD大鼠大脑皮层厚度为 ( 1 85± 0 1 2 )mm ;第V层神经元深度为 ( 1 1 7± 0 0 5 )mm。对同一预定深度所获的实际深度之间最大相差 1 60 μm。三个损伤组实际深度与预定深度差值的绝对值 |d|分别为 ( 5 0 1 7± 2 6 2 0 ) μm、( 4 6 68± 32 84)μm和 ( 4 8 70± 2 9 76) μm ,最大 |d|值为 90 μm。在损伤深度分别为 2 0 0 μm、40 0 μm和 60 0 μm时 ,神经元存活率分别为 ( 4 2 5 5± 5 1 0 ) %、( 68 96± 5 2 1 ) %和 ( 74 5 2± 5 37) %。结论　该模型模拟了多种脑白质病变导致轴突损伤的共同特征 ,重复性好 ,是进行脑轴突损伤后神经修复与再生研究较理想的模型。

The establishment of an in vivo model of infracortical axotomy

Objective To develop an in vivo model of infracortical axotomy. Methods The thickness of cerebral cortex and the depth of layer V cortical neurons were measured in 210～240?g male SD rats.Then,infracortical axotomy was proceeded stereotaxically in 3 groups with different lesion depths(namely:group A,B and C,which is 200?μm,400?μm and 600?μm beneath the layer V neurons respectively)according to the normal parameters determined.Seventeen days after operation,histological examinations were proceeded to measure the actual lesion depths and to count the survived neurons in layer V and the density of neuro fibers beneath.Meanwhile,functional recovery was evaluated in all animals using Houweling Gridwalk Test.Results The thickness of cortex and the depth of layer V neurons were(1 85±0 12)?mm and (1 17±0 05)?mm respectively.For the same intended lesion depth,the utmost difference between the actual lesion depths acquired was 160?μm.The absolute value |d| between the acquired and the intended depths in groups A,B and C were(50 17±26 20)μm,(46 86±32 84)μm and(48 70±29 76)?μm, respectively.Among all |d| values,the utmost was 90?μm.The survival rates of layer V neurons in group A,B and C were(42 55±5 10)%,(68 95±5 2)%and(74 52±5 37)%,respectively.Animals in group C got the best functional recovery.Conclusion This model imitated the common pathological characteristics of numerous intracerebral diseases and can be reliably replicated,therefore,it is considered a suitable model for the research of CNS protection and regeneration following intracerebral axonal injury.