Excitatory and inhibitory intermediate zone interneurons in pathways from feline group I and II afferents: differences in axonal projections and input
Excitatory and inhibitory intermediate zone interneurons in pathways from feline group I and II afferents: differences in axonal projections and input
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DOI：
10.1113/jphysiol.2008.159129
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发表时间：
2009-01-15
影响因子：
5.5
通讯作者：
Maxwell, D. J.
中科院分区：
文献类型：
--
作者：
Bannatyne, B. A.;Liu, T. T.;Maxwell, D. J.
本研究的目的是比较猫I组和II组肌肉传入通路中兴奋性和抑制性脊髓中间带中间神经元的特性。细胞内标记中间神经元，利用免疫细胞化学确定其递质表型。共检索到14个谷氨酸能、22个甘氨酸能和2个gaba能/甘氨酸能中间神经元。所有中间神经元均位于L3-L7节段的V-VII层。兴奋性和抑制性中间神经元的位置、胞体大小和树突状树的范围没有一致的差异。然而，它们在轴突投射方面存在主要差异；兴奋性中间神经元在同侧、双侧或对侧投射，而抑制性中间神经元只在同侧投射。在运动核以及灰质的其他区域（包括中间区域、第七和第八层）内发现了甘氨酸和谷氨酸能细胞的末端突起。含有GABA/甘氨酸的细胞有更有限的投射，主要在中间区，在那里它们与谷氨酸能轴突终末和未识别的细胞形成偶联，因此可能参与突触前和突触后抑制。大多数兴奋性和抑制性中间神经元被I组和II组传入神经（单突触）和网状脊髓神经元（单突触或双突触）共同兴奋，并整合来自多个肌肉的信息。形态学和电生理数据表明，单个兴奋性和抑制性中间带中间神经元可能以高度分化的方式运作，从而促进各种运动协同作用。
The aim of the present study was to compare properties of excitatory and inhibitory spinal intermediate zone interneurons in pathways from group I and II muscle afferents in the cat. Interneurons were labelled intracellularly and their transmitter phenotypes were defined by using immunocytochemistry. In total 14 glutamatergic, 22 glycinergic and 2 GABAergic/glycinergic interneurons were retrieved. All interneurons were located in laminae V-VII of the L3-L7 segments. No consistent differences were found in the location, the soma sizes or the extent of the dendritic trees of excitatory and inhibitory interneurons. However, major differences were found in their axonal projections; excitatory interneurons projected either ipsilaterally, bilaterally or contralaterally, while inhibitory interneurons projected exclusively ipsilaterally. Terminal projections of glycinergic and glutamatergic cells were found within motor nuclei as well as other regions of the grey matter which include the intermediate region, laminae VII and VIII. Cells containing GABA/glycine had more restricted projections, principally within the intermediate zone where they formed appositions with glutamatergic axon terminals and unidentified cells and therefore are likely to be involved in presynaptic as well as postsynaptic inhibition. The majority of excitatory and inhibitory interneurons were found to be coexcited by group I and II afferents (monosynaptically) and by reticulospinal neurons (mono- or disynaptically) and to integrate information from several muscles. Taken together the morphological and electrophysiological data show that individual excitatory and inhibitory intermediate zone interneurons may operate in a highly differentiated way and thereby contribute to a variety of motor synergies.