An interpretation of dental innervation based upon the pattern of calcitonin gene-related peptide (CGRP)-immunoreactive thin sensory axons.
An interpretation of dental innervation based upon the pattern of calcitonin gene-related peptide (CGRP)-immunoreactive thin sensory axons.
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DOI：
10.3109/07367228709144624
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发表时间：
1987
期刊：
影响因子：
--
通讯作者：
J. Silverman;Lawrence Kruger
中科院分区：
文献类型：
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作者：
J. Silverman;Lawrence Kruger
降钙素基因相关肽(CGRP)是近年来发现的一种神经活性物质，广泛分布于脊髓浅层和延髓背角的中小直径感觉神经节神经元中。这种在外周神经系统内的有限分布表明，该肽在伤害性信息处理中具有突出的作用。哺乳动物的牙髓接受来自这个三叉神经节细胞亚群的细小(可能是伤害性的)纤维的相对均匀的传入输入，因此为研究外周伤害性机制提供了一个理想的靶区。大量的CGRP免疫反应神经元(CGRP-LI)进一步为研究其细纤维传入神经提供了有价值的工具。CGRP-LI已经定位于完整的、脱钙的大鼠、猫、猴子和人类牙齿以及相关的牙齿结构的标本中。在所有物种中，磨牙牙髓和牙本质都有非常强大的CGRP-LI神经支配，纤维既有成束的，也有单独的，与血管和牙髓基质的关系不同。我们的方法能够通过Raschkow神经丛和成牙本质细胞层追踪大量轴突进入牙本质小管。平行于轴突顺行运输的研究发现，与神经根牙本质相比，冠状轴突中的纤维所占比例更大。在大鼠中，这种纤维模式既与缺乏CGRP-LI的切牙本质形成对比，也与牙龈和牙周组织中丰富的标记轴突形成对比。手术切断大鼠下颌骨的传入导致CGRP-LI的广泛缺失，而颈上神经节切除无效，证实了CGRP-LI纤维的感觉性质。新生儿辣椒素治疗显著减弱了免疫染色，为CGRP-LI在化疗敏感性的无髓传入神经元中的定位提供了证据。CGRP-LI轴突的巨大密度被认为与牙齿可能受到的感觉刺激的有限范围和程度相反，并与牙齿结构中各种正在进行的营养、调节和修复过程有关。因此，我们认为这些纤维可能是牙髓中重要的传出纤维，与伤害性感觉没有直接关系。
Calcitonin gene-related peptide (CGRP) is a recently characterized neuroactive substance that is expressed in a large proportion of small- to medium-diameter sensory ganglion neurons whose central terminals lie in the superficial spinal and medullary dorsal horn. This restricted distribution within the peripheral nervous system suggests a prominent role for the peptide in nociceptive processing. The mammalian tooth pulp, which receives a relatively homogeneous afferent input from thin (putative nociceptive) fibers originating from this subpopulation of trigeminal ganglion cells, thus affords an ideal target zone in which to examine peripheral nociceptive mechanisms. The large percentage of these neurons displaying CGRP-like immunoreactivity (CGRP-LI) furthermore provides a valuable tool to study its thin-fiber afferent innervation. CGRP-LI has been localized within intact, decalcified specimens of rat, cat, monkey, and human teeth and associated dental structures. A remarkably robust CGRP-LI innervation of molar pulp and dentin was revealed in all species, with fibers coursing both in fascicles and individually, in variable relation to blood vessels and pulpal stroma. Our methods enabled tracing of a large number of axons through Raschkow's plexus and odontoblast layer into dentinal tubules. Paralleling anterograde axonal transport studies, a greater share of fibers was found in coronal vis-à-vis radicular dentin. In the rat, this fiber pattern stood in contrast both to incisor dentin, which appeared devoid of CGRP-LI, and to the abundant labeled axons in gingiva and periodontal tissues. Surgical deafferentation of rat mandible resulted in widespread depletion of CGRP-LI, while superior cervical ganglionectomy was without effect, confirming the sensory nature of the CGRP-LI fibers. Neonatal capsaicin treatment greatly attenuated the immunostaining, providing evidence for CGRP-LI localization in chemosensitive unmyelinated afferents. The great density of CGRP-LI axons demonstrated is considered in contrast to the restricted range and extent of sensory stimuli to which teeth are presumably subjected, and in relation to the diverse ongoing trophic, regulatory, and reparative processes in tooth structures. It is therefore suggested that these fibers may be subserving prominent efferent roles in dental pulp not directly related to nociception.