Yamamoto Yoshio, Nakamuta Nobuaki
Laboratory of Veterinary Anatomy and Cell Biology, Faculty of Agriculture, Iwate University, Morioka, Iwate, Japan.
J Comp Neurol. 2018 Feb 15;526(3):550-566. doi: 10.1002/cne.24351. Epub 2017 Nov 26.
Nerve endings with immunoreactivity for the P2X3 purinoreceptor (P2X3) in the rat tracheal mucosa were examined by immunohistochemistry of whole-mount preparations with confocal scanning laser microscopy. P2X3 immunoreactivity was observed in ramified endings distributed in the whole length of the trachea. The myelinated parent axons of P2X3-immunoreactive nerve endings ramified into several branches that extended two-dimensionally in every direction at the interface between the epithelial layer and lamina propria. The axonal branches of P2X3-immunoreactive endings branched off many twigs located just beneath the epithelium, and continued to intraepithelial axon terminals. The axon terminals of P2X3-immunoreactive endings were beaded, rounded, or club-like in shape and terminated between tracheal epithelial cells. Flat axon terminals sometimes partly ensheathed neuroendocrine cells with immunoreactivity for SNAP25 or CGRP. Some axons and axon terminals with P2X3 immunoreactivity were immunoreactive for P2X2, while some terminals were immunoreactive for vGLUT2. Furthermore, a retrograde tracing method using fast blue (FB) revealed that 88.4% of FB-labeled cells with P2X3 immunoreactivity originated from the nodose ganglion. In conclusion, P2X3-immunoreactive nerve endings in the rat tracheal mucosa have unique morphological characteristics, and these endings may be rapidly adapting receptors and/or irritant receptors that are activated by mucosal irritant stimuli.
采用整装制剂免疫组织化学结合共聚焦扫描激光显微镜技术，对大鼠气管黏膜中对P2X3嘌呤受体（P2X3）具有免疫反应性的神经末梢进行了研究。在气管全长分布的分支状末梢中观察到P2X3免疫反应性。P2X3免疫反应性神经末梢的有髓母轴突分支成几个分支，这些分支在上皮层和固有层之间的界面处以二维方式向各个方向延伸。P2X3免疫反应性末梢的轴突分支从位于上皮下方的许多细枝上分支出来，并延伸至上皮内轴突终末。P2X3免疫反应性末梢的轴突终末呈串珠状、圆形或棒状，终止于气管上皮细胞之间。扁平的轴突终末有时部分包裹着对SNAP25或降钙素基因相关肽（CGRP）具有免疫反应性的神经内分泌细胞。一些具有P2X3免疫反应性的轴突和轴突终末对P2X2具有免疫反应性，而一些终末对囊泡谷氨酸转运体2（vGLUT2）具有免疫反应性。此外，使用快蓝（FB）的逆行追踪方法显示，88.4%具有P2X3免疫反应性的FB标记细胞起源于结状神经节。总之，大鼠气管黏膜中P2X3免疫反应性神经末梢具有独特的形态学特征，这些末梢可能是快速适应性受体和/或由黏膜刺激物激活的刺激感受器。
