Kiernan J A, Hudson A J
Department of Anatomy, University of Western Ontario, London, Canada.
Brain. 1991 Apr;114 ( Pt 2):843-53. doi: 10.1093/brain/114.2.843.
It has been suggested that the degeneration of lower motor neurons in amyotrophic lateral sclerosis (ALS) is a transneuronal event, secondary to the loss of corticospinal and corticobulbar neurons. In an attempt to test this hypothesis, the cross-sectional areas of pyramidal cells in layer 5 of the foot and tongue areas of the precentral gyri were measured in 12 cases of the classical sporadic form of ALS, and in 10 control subjects. The areas of motor neurons in the hypoglossal nuclei and in the ventral horns of segment L4 of the spinal cord were also measured. The number of neurons per 20 microns section of ventral horn or hypoglossal nucleus provided a more reliable index of severity of lower motor neuron loss at the time of death than did a semiquantitative score derived from clinical observations. Cortical neurons and lower motor neurons were significantly smaller in the cases of ALS than in the controls. In the cortex this change included, but was not confined to, the largest neurons. These observations indicate that shrinkage precedes neuronal death. There was no correlation, positive or negative, between the numbers of surviving lower motor neurons and the mean sizes of pyramidal cells in layer 5 of the corresponding areas of the precentral gyri. The absence of such a correlation indicates that functionally related cortical and lower motor neurons probably degenerate independently, and not from a transsynaptic effect. Neuronal shrinkage has been observed in other diseases in which interconnected systems of neurons degenerate. The possible association of shrinkage with cytoskeletal degradation is discussed.
有人提出，肌萎缩侧索硬化症（ALS）中运动神经元的退化是一种跨神经元事件，继发于皮质脊髓和皮质延髓神经元的丧失。为了验证这一假设，在12例经典散发性ALS病例和10名对照受试者中，测量了中央前回足部和舌部区域第5层锥体细胞的横截面积。还测量了舌下神经核和脊髓L4节段腹角运动神经元的面积。与临床观察得出的半定量评分相比，腹角或舌下神经核每20微米切片中的神经元数量为死亡时运动神经元丧失的严重程度提供了更可靠的指标。ALS病例中的皮质神经元和运动神经元明显小于对照组。在皮质中，这种变化包括但不限于最大的神经元。这些观察结果表明，萎缩先于神经元死亡。存活的运动神经元数量与中央前回相应区域第5层锥体细胞的平均大小之间没有正相关或负相关。这种相关性的缺乏表明，功能相关的皮质和运动神经元可能独立退化，而不是通过突触后效应。在其他神经元相互连接系统退化的疾病中也观察到了神经元萎缩。讨论了萎缩与细胞骨架降解的可能关联。
