Networks of inhibitory and excitatory commissural interneurons mediating crossed reticulospinal actions
Networks of inhibitory and excitatory commissural interneurons mediating crossed reticulospinal actions
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DOI：
10.1046/j.1460-9568.2003.02973.x
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发表时间：
2003-10-01
影响因子：
3.4
通讯作者：
Maxwell, DJ
中科院分区：
文献类型：
--
作者：
Bannatyne, BA;Edgley, SA;Maxwell, DJ
在成年猫上研究了连合中间神经元介导网状脊髓神经元交叉活动的轴突投射和神经递质。十八interneurons，位于或接近层VIII中腰中段，单突触兴奋的网状脊髓束纤维和投射到对侧运动核标记细胞内注射四甲基罗丹明-葡聚糖和神经生物素。9个最完全标记的中间神经元进行了分析，结合共聚焦和光学显微镜。所有的轴突均未发出同侧轴突侧支。7个细胞的轴突侧支在同一节段的腹角对侧灰质中分叉。通过使用针对囊泡谷氨酸转运蛋白1和2、谷氨酸脱羧酶和甘氨酸转运蛋白2的抗体来鉴定传递蛋白。两个细胞的轴突是免疫反应的甘氨酸转运蛋白2，因此是甘氨酸。三个细胞的囊泡谷氨酸转运蛋白2的免疫反应，因此是amatergic。没有轴突显示谷氨酸脱羧酶的免疫反应性。两个细胞的电子显微镜显示与运动神经元和其他神经元的直接突触连接。一个神经元的轴突selling形成突触的运动核，而其他的形成突触与其他结构，包括在第七层的细胞体的配置文件。结果表明，这个人口连合中间神经元包括兴奋性和抑制性细胞，可能会直接兴奋或抑制对侧运动神经元。它们也可能通过位于对侧灰质运动核外的中间神经元间接影响运动神经元的活动，但不太可能对同侧灰质中的中间神经元产生直接作用。
Axonal projections and neurotransmitters used by commissural interneurons mediating crossed actions of reticulospinal neurons were investigated in adult cats. Eighteen interneurons, located in or close to lamina VIII in midlumbar segments, that were monosynaptically excited by reticulospinal tract fibres and projected to contralateral motor nuclei were labelled by intracellular injection of tetramethylrhodamine-dextran and Neurobiotin. The nine most completely labelled interneurons were analysed with combined confocal and light microscopy. None of the stem axons gave off ipsilateral axon collaterals. Seven cells had axon collaterals that arborized in the contralateral grey matter in the ventral horn of the same segments. Transmitters were identified by using antibodies raised against vesicular glutamate transporters 1 and 2, glutamic acid decarboxylase and the glycine transporter 2. The axons of two cells were immunoreactive for the glycine transporter 2 and hence were glycinergic. Three cells were immunoreactive for the vesicular glutamate transporter 2 and hence were glutamatergic. None of the axons displayed immunoreactivity for glutamic acid decarboxylase. Electron microscopy of two cells revealed direct synaptic connections with motoneurons and other neurons. Axonal swellings of one neuron formed synapses with profiles in motor nuclei whereas those of the other formed synapses with other structures, including cell bodies in lamina VII. The results show that this population of commissural interneurons includes both excitatory and inhibitory cells that may excite or inhibit contralateral motoneurons directly. They may also influence the activity of motoneurons indirectly by acting through interneurons located outside motor nuclei in the contralateral grey matter but are unlikely to have direct actions on interneurons in the ipsilateral grey matter.