Expression of vesicular glutamate transporters, VgluT1 and VGluT2, in axon terminals of nociceptive primary afferent fibers in the superficial layers of the medullary and spinal dorsal horns of the rat
Expression of vesicular glutamate transporters, VgluT1 and VGluT2, in axon terminals of nociceptive primary afferent fibers in the superficial layers of the medullary and spinal dorsal horns of the rat
复制标题
DOI：
10.1002/cne.10556
复制
发表时间：
2003-03-10
影响因子：
2.5
通讯作者：
Mizuno, N
中科院分区：
文献类型：
--
作者：
Li, JL;Fujiyama, F;Mizuno, N
我们研究了囊泡谷氨酸转运体（VGluTs），VGluT 1和VGluT 2，是否可能表达在突触终末的伤害性初级传入纤维内板层I和II的髓和脊髓背角的大鼠。VGluT 1免疫反应（IR）是强烈的，在第二层的内部，但在第一层和第二层的外部弱。VGluT 2-IR在I层和II层的外部最强。VGluTs和突触素的双重免疫荧光组织化学证实了VGluTs在突触终末的表达。VGluTs的表达在初级传入纤维的轴突终末终止于板层I和II后，也证实了单侧背根切断。双重免疫荧光组织化学显示VGluTs表达在I层和II层外部的含P物质（SP）的轴突终末。电子显微镜证实了VGluTs和SP在轴突终末内的I和II层的共表达; VGluTs与圆形突触囊泡在不对称的突触。进一步观察到，isolectin IB 4，无髓鞘轴突的标记物，经常与VGluT 2-免疫阳性结构结合，但很少与VGluT 1-免疫阳性结构在板层II。因此，结果表明，在脊髓和脊髓背角的I和II层中，VGluT 1和VGluT 2都在初级传入纤维的轴突终末表达，包括含SP的伤害性纤维，并且终止于II层的无髓鞘初级传入纤维中的VGluT主要是VGluT 2。
We examined immunohistochemically whether the vesicular glutamate transporters (VGluTs), VGluT1 and VGluT2, might be expressed in synaptic terminals of nociceptive primary afferent fibers within laminae I and II of the medullary and spinal dorsal horns of the rat. VGluT1 immunoreactivity (IR) was intense in the inner part of lamina II but weak in lamina I and the outer part of lamina II. VGluT2-IR was most intense in lamina I and the outer part of lamina II. Expression of VGluTs in synaptic terminals was confirmed by dual immunofluorescence histochemistry for VGluTs and synaptophysin. Expression of VGluTs in axon terminals of primary afferent fibers terminating in laminae I and II was also confirmed immunohistochemically after unilateral dorsal rhizotomy. The dual immunofluorescence histochemistry indicated expression of VGluTs in substance P (SP)-containing axon terminals in lamina I and the outer part of lamina II. Electron microscopy confirmed the coexpression of VGluTs and SP in axon terminals within laminae I and II; VGluTs was associated with round synaptic vesicles at the asymmetric synapses. It was further observed that isolectin IB4, a marker for unmyelinated axons, often bound with VGluT2-immunopositive structures but rarely with VGluT1-immunopositive structures in lamina II. Thus, the results indicated in laminae I and II of the medullary and spinal dorsal horns that both VGluT1 and VGluT2 were expressed in axon terminals of primary afferent fibers, including SP-containing nociceptive fibers and that VGluT in unmyelinated primary afferent fibers terminating in lamina II was primarily VGluT2.