Monosynaptic connections between primary afferents and giant neurons in the turtle spinal dorsal horn
Monosynaptic connections between primary afferents and giant neurons in the turtle spinal dorsal horn
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初级传入神经与龟脊髓背角巨神经元之间的单突触连接
DOI：
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发表时间：
1996
影响因子：
2
通讯作者：
O. Trujillo
中科院分区：
文献类型：
--
作者：
A. Fernández;M. Radmilovich;R. E. Russo;J. Hounsgaard;O. Trujillo
本文报道了背根传入神经与龟脊髓背角深处的一种独特的细胞类型--巨神经元之间的单突触联系。光镜研究结合尼氏染色和transganglionic HRP标记的初级传入揭示了轴体和axodendritic标记的终扣和巨大的神经元之间的接触的发生。这些接触的突触性质已被证实，通过使用电子显微镜程序，涉及部分的三维重建确定的巨大神经元。脊髓切片的细胞内记录提供了背根传入神经与巨神经元之间存在单突触联系的功能证据。记录的神经元通过生物胞素注射和亲和素结合物进行形态学鉴定。电刺激同侧背根诱发的突触反应具有短的、固定的潜伏期（1.6-5.6 ms），其在高频（10 Hz）下保持不变。还观察到兴奋性多突触电位。通过药理学方法，将短潜伏期反应分为两部分：一部分对河豚毒素不敏感，另一部分被药物消除。推测小直径的C纤维维持了毒素抵抗成分。突触反应主要由谷氨酸-AMPA受体亚型介导，然而，也存在一个小组件由NMDA受体介导。
This paper reports the occurrence of monosynaptic connections between dorsal root afferents and a distinct cell type — the giant neuron — deep in the dorsal horn of the turtle spinal cord. Light microscope studies combining Nissl stain and transganglionic HRP-labeling of the primary afferents have revealed the occurrence of axosomatic and axodendritic contacts between labeled boutons and giant neurons. The synaptic nature of these contacts has been confirmed by use of electron microscope procedures involving the partial three-dimensional reconstruction of identified giant neurons. Intracellular recording in spinal cord slices provided functional evidence indicating the monosynaptic connections between dorsal root afferents and giant neurons. The recorded neurons were morphologically identified by means of biocytin injection and with avidin conjugates. Electrical stimulation of the ipsilateral dorsal roots evoked synaptic responses with short, fixed latencies (1.6–5.6 ms), which remained unchanged at high frequencies (10 Hz). Excitatory polysynaptic potentials were also observed. By means of pharmacological procedures the short-latency response was dissected in two components: one insensitive to tetrodotoxin, the other abolished by the drug. The toxin-resistant component was presumed to be sustained by small-diameter C fibers. The synaptic response was mainly mediated by the glutamate-AMPA receptor subtype; however, a small component mediated by NMDA receptor was also present.