Ultrastructural synaptic features differ between α- and γ-motoneurons innervating the tibialis anterior muscle in the rat
Ultrastructural synaptic features differ between α- and γ-motoneurons innervating the tibialis anterior muscle in the rat
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DOI：
10.1002/cne.21110
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发表时间：
2006-11-10
影响因子：
2.5
通讯作者：
Havton, Leif A.
中科院分区：
文献类型：
--
作者：
Ichiyama, Ronaldo M.;Brown, Jonas;Havton, Leif A.
用辣根过氧化物酶（HRP）逆行标记成年大鼠胫骨前肌（TA），观察TA内脊髓运动神经元的突触学变化。总共，32 TA运动神经元在电子显微镜下进行了研究，并表现出双峰尺寸分布与细胞直径峰值在40 μ m和20 μ m，可能代表α和γ运动神经元，分别。α-和γ-运动神经元均由S-和F-型突触终扣并置，而只有α-运动神经元表现出由大的M-和C-型终扣输入。由突触输入覆盖的细胞体膜的比例在α运动神经元（72.2%）和γ运动神经元（63.5%）之间令人惊讶地难以区分。与运动神经元胞体并列的F-和S-型终扣的数量之间的比率（F/S比率）和由F-和S-型终扣提供的索马膜覆盖率之间的比率在α-运动神经元中均显著高于在γ-运动神经元中。当比较我们的数据与以前的研究结果在其他物种，我们得出结论，大鼠TA α-运动神经元是类似的猫和灵长类动物的α-运动神经元突触末端形态，频率和分布。然而，大鼠γ-运动神经元显示出显着更高的总突触覆盖率和频率比猫γ-运动神经元，虽然这两个物种表现出由相同的突触类型和抑制性和兴奋性输入之间的相似比例的并置。
We investigated the synaptology of retrogradely labeled spinal motoneurons after injection of horseradish peroxidase into the tibialis anterior (TA) muscle of adult rat. In total, 32 TA motoneurons were investigated in the electron microscope and demonstrated a bimodal size distribution with cell diameter peaks at 40 mu m and 20 mu m, likely representing alpha- and gamma-motoneurons, respectively. Both alpha- and gamma-motoneurons were apposed by S- and F-type synaptic boutons, whereas only alpha-motoneurons demonstrated inputs by the large M- and C-type boutons. The proportion of cell body membrane covered by synaptic inputs was surprisingly indistinguishable between alpha-motoneurons (72.2%) and gamma-motoneurons (63.5%). The ratio between the number of F- and S-type boutons in apposition with the motoneuron cell body (F/S ratio) and the ratio between the soma membrane coverage provided by F- and S-type boutons were both significantly higher in alpha- than in gamma-motoneurons. When comparing our data with previous findings in other species, we conclude that rat TA alpha-motoneurons are similar to cat and primate alpha-motoneurons with regard to synaptic terminal morphology, frequency, and distribution. However, rat gamma-motoneurons show a markedly higher total synaptic coverage and frequency than cat gamma-motoneurons, although both species exhibit appositions made by the same synaptic types and similar ratios between inhibitory and excitatory inputs.