Red nucleus projections to distinct motor neuron pools in the rat spinal cord
Red nucleus projections to distinct motor neuron pools in the rat spinal cord
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DOI：
10.1002/cne.10259
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发表时间：
2002-05-08
影响因子：
2.5
通讯作者：
Raineteau, O
中科院分区：
文献类型：
--
作者：
Küchler, M;Fouad, K;Raineteau, O
尽管红核脊髓束是大鼠脊髓下行通路中研究最多的一条，但其终止方式和突触后靶点仍存在一些尚未解决的问题。除了运动功能外，神经节还参与控制肢体运动，如伸手和抓握。虽然一个强大的神经投射到中间Rexed的板层V和VI的中间神经元已被描述通过整个大鼠脊髓的长度，直接红核运动神经元连接的存在尚未得到证明。在本研究中，顺行追踪大鼠脊髓与生物素葡聚糖胺（BDA）与注射霍乱毒素P-亚单位（CTbeta）到选定的组前肢肌肉详细分析红核的预测前肢区的颈脊髓。双染色程序表明，直接投射从延髓特定群体的运动神经元。前肢肌肉的三个种群被区分，即，爪，“远端”肌肉;前臂，“中间”肌肉;和上臂，“近端”肌肉。相应的运动神经元池的躯体分布存在于脊髓节段C4-Th 1。红核脊髓轴突被认为是在密切并列的远端和中间的肌肉运动神经元，但始终缺席的最腹侧位于运动柱投射到近端肌肉。微刺激红核导致的肌电图反应与较短的潜伏期在前肢远端肌肉比近端肌肉。这些实验支持一个特定的，优先的作用，在远端前肢肌肉控制的腹侧肌。(C)2002 Wiley-Liss，Inc.
Despite being one of the more extensively investigated descending pathways of the rat spinal cord, the termination pattern and postsynaptic targets of the rubrospinal tract (RST) still present some unresolved issues. In addition to locomotor functions, the RST is implicated in the control of limb movements such as reaching and grasping. Although a strong RST projection onto interneurons of intermediate Rexed's laminae V and VI have been described through the entire length of the rat spinal cord, the existence of direct rubro-motoneuronal connections have not been demonstrated. In the present study, anterograde tracing of the rat RST with biotinylated dextran amine (BDA) was combined with injections of cholera toxin P-subunit (CTbeta) into selected groups of forelimb muscles to analyze in detail the rubral projections to the forelimb areas of the cervical spinal cord. The double-staining procedure suggested a direct projection from the RST to specific populations of motoneurons. Three populations of forelimb muscles were distinguished, i.e., paw, "distal" muscles; forearm, "intermediate" muscles; and upper arm, "proximal" muscles. A somatotopic distribution of the corresponding motor neuron pools was present in the spinal cord segments C4-Th1. Rubrospinal axons were seen in close apposition to the distal and intermediate muscle motoneurons, but were consistently absent in the most ventrally situated motor column projecting to proximal muscles. Microstimulation of the red nucleus resulted in electromyographic responses with shorter latency in the distal forelimb muscles than in proximal muscles. These experiments support a specific, preferential role of the RST in distal forelimb muscle control. (C) 2002 Wiley-Liss, Inc.