Peptide immunoreactivity of unmyelinated primary afferent axons in rat lumbar dorsal roots

D. L. McNeill, K. N. Westlund, R. E. Coggeshall

Research output: Contribution to journalArticle

46 Scopus citations


The present study demonstrates calcitonin gene-related peptide (CGRP), somatostatin (SOM), bombesin (BOM), and substance P (SP) at the electron microscopic level in lumbar dorsal root axons of normal rats. The highest percentages of labeled axons were for CGRP (14%) and then, in descending order, for SP (8.6%), SOM (6.8%), and BOM (3.1%). The labeled axons were exclusively unmyelinated for SP, SOM, and BOM, and predominantly unmyelinated for CGRP. These data are consistent with the data for labeled sensory cell bodies for these same compounds. We emphasize that these peptides were immunocytochemically visualized in the dorsal roots without experimental manipulation, such as colchicine or dorsal root ligation. Quantitative sampling of this type can be used to assay changes in response to physiological stimuli in numbers of sensory axons that contain identifiable concentrations of these peptides.

Original languageEnglish (US)
Pages (from-to)1047-1052
Number of pages6
JournalJournal of Histochemistry and Cytochemistry
Issue number7
StatePublished - Jan 1 1989


ASJC Scopus subject areas

  • Anatomy
  • Histology

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