Central projection of calcitonin gene-related peptide (CGRP)- and substance P (SP)-immunoreactive trigeminal primary neurons in the rat

Tomosada Sugimoto, Yoshiaki Fujiyoshi, Chun Xiao, Yi Fen He, Hiroyuki Ichikawa

Research output: Contribution to journalArticlepeer-review

116 Citations (Scopus)


Substance P (SP) is implicated in transmission of primary afferent nociceptive signals. In primary neurons, SP is colocalized with calcitonin gene-related peptide (CGRP), which is another neuropeptide marker for small to medium primary neurons. CGRP coreleased with SP augments the postsynaptic effect of SP and thereby modulates the nociceptive transmission. This study demonstrates the distribution of CGRP-like immunoreactivity (-ir) and SP-ir in the lower brainstem of normal rats and after trigeminal rhizotomy or tractotomy at the level of subnucleus interpolaris (Vi). By comparing the results obtained from normal and deafferented rats, we analyzed the central projection of trigeminal primary nociceptors. The CGRP-immunoreactive (-ir) trigeminal primaries projected to the entire rostrocaudal extent of the spinal trigeminal nucleus, the principal nucleus (PrV), the paratrigeminal nucleus (paraV), and the lateral subnucleus of solitary tract nucleus (STN) on the ipsilateral side. The trigeminal primaries projecting to the spinal trigeminal nucleus, paraV and STN also contained SP-ir. The ipsilateral trigeminal primaries were the exclusive source of CGRP-ir terminals in the PrV, the Vi and the dorsomedial nucleus within the subnucleus oralis (Vo). The medullary dorsal horn (MDH) and the lateral edge of Vo received convergent CGRP-ir projection from the ipsilateral trigeminal primaries and other neurons. The glossopharyngeal and vagal primaries are candidates for the source of CGRP-ir projection to the Vo and the MDH, while the dorsal root axons supply the MDH with CGRP-ir terminals. In addition, contralateral primary neurons crossing the midline appear to contain CGRP and to terminate in the MDH.

Original languageEnglish
Pages (from-to)425-442
Number of pages18
JournalJournal of Comparative Neurology
Issue number3
Publication statusPublished - Feb 17 1997


  • nociception
  • orofacial pain
  • rhizotomy
  • tractotomy
  • trigeminal nuclei

ASJC Scopus subject areas

  • Neuroscience(all)


Dive into the research topics of 'Central projection of calcitonin gene-related peptide (CGRP)- and substance P (SP)-immunoreactive trigeminal primary neurons in the rat'. Together they form a unique fingerprint.

Cite this