SPATIAL-DISTRIBUTION OF RECURRENT INHIBITORY SYNAPSES ON SPINAL MOTONEURONS IN THE CAT
SPATIAL-DISTRIBUTION OF RECURRENT INHIBITORY SYNAPSES ON SPINAL MOTONEURONS IN THE CAT
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DOI：
10.1152/jn.1991.65.5.1134
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发表时间：
1991-05-01
影响因子：
2.5
通讯作者：
FYFFE, REW
中科院分区：
文献类型：
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作者：
FYFFE, REW
1.采用Renshaw细胞和α运动神经元细胞内染色的方法，观察猫脊髓运动神经元上反复抑制性突触的空间分布。在每个实验中，一个Renshaw细胞和一个或多个可能的靶运动神经元经生理学鉴定后，用辣根过氧化物酶标记.对标记的神经元进行重建，并在光镜水平上进行测量。如光学显微镜所定义，观察到9个Renshaw细胞和10个突触后运动神经元之间的假定突触接触。平均而言，每个Renshaw细胞在每个运动神经元上进行三次突触接触（范围1-9）。电子显微镜证实了几个假定的接触提供了证据，并确定由光镜标准之间的Renshaw细胞终扣和标记的运动神经元的真正接触。在这些实验中观察到的所有识别的突触位于运动神经元树突，从索马65和706 μ m之间。使用简化的电缆模型表明，突触在电紧张性上靠近索马，平均位置距离索马约0.25个长度常数（范围0.04-0.82 λ）。这些观察结果提供了直接证据来支持运动神经元上的Renshaw细胞突触位于树突上而不是细胞体上的假设（而来自Ia抑制性中间神经元的相互抑制性突触主要位于索马上）。讨论了所观察到的Renshaw抑制性突触分布的功能意义。一种可能性是，复发性抑制途径选择性地抑制特定的树突输入。
1. Intracellular staining of Renshaw cells and alpha motoneurons was used to determine the spatial distribution of recurrent inhibitory synapses on spinal motoneurons in the cat. In each experiment, a Renshaw cell and one or more possible target motoneurons were labeled with horseradish peroxidase after physiological identification.2. Pairs of labeled neurons were reconstructed and measured at the light microscopic level. As defined by light microscopy, presumed synaptic contacts between nine Renshaw cells and 10 post-synaptic motoneurons were observed. On average, each Renshaw cell made three synaptic contacts (range 1-9) on each motoneuron.3. Electron microscopic confirmation of several presumed contacts provided evidence that the appositions identified by light microscopic criteria are genuine contacts between Renshaw cell boutons and the labeled motoneuron.4. All of the identified synapses observed in these experiments were located on motoneuron dendrites, between 65 and 706 mu-m from the soma. Use of a simplified cable model indicated that the synapses are electrotonically close to the soma, the average location being approximately 0.25 length constants from the soma (range 0.04-0.82-lambda).5. These observations provide direct evidence to support the hypothesis that Renshaw cell synapses on motoneurons are located on the dendrites and not on the cell body (whereas reciprocal inhibitory synapses, from Ia inhibitory interneurons, are predominantly located on the soma). the functional significance of the observed distribution of Renshaw inhibitory synapses is discussed. One possibility is that the recurrent inhibitory pathway selectively inhibits particular dendritic inputs.