Light and electron microscopic localization of calcitonin gene‐related peptide immunoreactivity in lamina II of the feline trigeminal pars caudalis/medullary dorsal horn: A qualitative study

Michael A. Henry, Nancy A. Nousek‐Goebl, Lesnick E. Westrum

Research output: Contribution to journalArticle

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Abstract

Calcitonin gene‐related peptide (CGRP) is a neuropeptide that is associated with a subset of primary afferent fibers and appears to have a role in nociception. The purpose of the present study was to perform a qualitative light, and especially electron microscopic (LM and EM), examination of CGRP‐immunoreactivity (IR) within lamina II (substantia gelatinosa) of the feline pars caudalis/medullary dorsal horn (PC/MDH) of the spinal trigeminal nucleus. The LM investigation revealed massive CGRP‐IR within lamina II outer, with fewer fibers that traversed lamina II inner. The EM preparations showed CGRP‐IR in small, thinly myelinated and unmyelinated axons, preterminal axons, and in axon terminals that formed asymmetric synaptic contacts onto small dendritic profiles. The terminals with CGRP‐IR were often the central element within glomeruli, where the terminal usually formed 2 or more asymmetric synaptic specializations onto 1 or more dendrites. Many of these postsynaptic dendrites contained synaptic vesicles. Other profiles were seen forming presynaptic contacts onto the terminal with CGRP‐IR, and these profiles most likely represent presynaptic dendrites and/or other axon terminals of intrinsic origin. The synaptic association of terminals showing CGRP‐IR with vesicle‐containing dendrites, presynaptic dendrites, and/or other axon terminals suggests that terminals with CGRP‐IR are especially susceptible to modulation. © 1993 Wiley‐Liss, Inc.

Original languageEnglish (US)
Pages (from-to)99-107
Number of pages9
JournalSynapse
Volume13
Issue number2
DOIs
StatePublished - Feb 1993

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Keywords

  • Immunocytochemistry
  • Neuropeptides
  • Primary afferents
  • Substantia gelatinosa
  • Synaptic glomeruli
  • Ultrastructure

ASJC Scopus subject areas

  • Cellular and Molecular Neuroscience

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