Sprouting capacity of lumbar motoneurons in normal and hemisected spinal cords of the rat
Sprouting capacity of lumbar motoneurons in normal and hemisected spinal cords of the rat
复制标题
正常和半切大鼠脊髓腰部运动神经元的出芽能力
DOI：
10.1113/jphysiol.2010.190389
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发表时间：
2010
期刊：
影响因子：
--
通讯作者：
N. Tyreman
中科院分区：
文献类型：
--
作者：
T. Gordon;N. Tyreman
神经发芽重新支配部分失神经肌肉是重要的几种疾病和损伤状态。为了检查活跃和不活跃的运动单位（MU）的发芽的有效性和发芽限制的基础，在正常条件下和脊髓在T12处半切时切断三个大鼠腰脊神经根之一。记录肌肉和MU等长收缩力，并在手术后23至380天对糖原耗尽的单个肌肉单位中的肌纤维进行计数。完整的MU发芽包围是有效的补偿高达80%的神经支配的损失。对于去除>70-80%的完整MU的损伤，肌肉收缩力和重量急剧下降。对于<70%的部分去神经，所有MU在正常活动的肌肉和T12半切减少活动的肌肉中以相同的因子增加收缩力。通过在生理学和组织化学定义的肌肉单位中计数糖原耗尽的肌纤维来直接测量MU大小，为MU大小的限制提供了直接证据，无论脊髓半切是否降低了肌肉的活动。肌肉单位的外边界内的肌纤维的空间分布的分析表明，在该领土内的发芽的限制时，大多数的肌肉单位纤维彼此相邻的纤维的逐步增加。我们的结论是，MU扩大的上限可以解释由轴突芽的肌肉单位，以前分布在马赛克图案的空间领土内的失神经支配的肌肉纤维的再支配。
Nerve sprouting to reinnervate partially denervated muscles is important in several disease and injury states. To examine the effectiveness of sprouting of active and inactive motor units (MUs) and the basis for a limit to sprouting, one of three rat lumbar spinal roots was cut under normal conditions and when the spinal cord was hemisected at T12. Muscle and MU isometric contractile forces were recorded and muscle fibres in glycogen‐depleted single muscle units enumerated 23 to 380 days after surgery. Enlargement of intact MUs by sprouting was effective in compensating for up to 80% loss of innervation. For injuries that removed >70–80% of the intact MUs, muscle contractile force and weight dropped sharply. For partial denervation of <70%, all MUs increased contractile force by the same factor in both normally active muscles and muscles whose activity was reduced by T12 hemisection. Direct measurements of MU size by counting glycogen‐depleted muscle fibres in physiologically and histochemically defined muscle units, provided direct evidence for a limit in MU size, whether or not the activity of the muscles was reduced by spinal cord hemisection. Analysis of spatial distribution of muscle fibres within the outer boundaries of the muscle unit demonstrated a progressive increase in fibres within the territory to the limit of sprouting when most of the muscle unit fibres were adjacent to each other. We conclude that the upper limit of MU enlargement may be explained by the reinnervation of denervated muscle fibres by axon sprouts within the spatial territory of the muscle unit, formerly distributed in a mosaic pattern.