Trigeminal collaterals in the nasal epithelium and olfactory bulb: A potential route for direct modulation of olfactory information by trigeminal stimuli

Thomas E. Finger, Bärbel Böttger, Michele L. Schaefer, Wayne L. Silver

Research output: Contribution to journalArticlepeer-review

Abstract

The nasal epithelium is richly invested with peptidergic (substance P and calcitonin gene-related peptide [CGRP]) trigeminal polymodal nociceptors, which respond to numerous odorants as well as irritants. Peptidergic trigeminal sensory fibers also enter the glomerular layer of the olfactory bulb. To test whether the trigeminal fibers in the olfactory bulb are collaterals of the epithelial trigeminal fibers, we utilized dual retrograde labeling techniques in rats to identify the trigeminal ganglion cells innervating each of these territories. Nuclear Yellow was injected into the dorsal nasal epithelium, and True Blue was injected into the olfactory bulb of the same side. Following a survival period of 3-7 days, the trigeminal ganglion contained double-labeled, small (11.8 x 8.0 μm), ellipsoid ganglion cells within the ethmoid nerve region of the ganglion. Tracer injections into the spinal trigeminal complex established that these branched trigeminal ganglion cells also extended an axon into the brainstem. These results indicate that some trigeminal ganglion cells with sensory endings in the nasal epithelium also have branches reaching directly into both the olfactory bulb and the spinal trigeminal complex. These trigeminal ganglion cells are unique among primary sensory neurons in having two branches entering the central nervous system at widely distant points. Furthermore, the collateral innervation of the epithelium and bulb may provide an avenue whereby nasal irritants could affect processing of coincident olfactory stimuli.

Original languageEnglish (US)
Pages (from-to)221-226
Number of pages6
JournalJournal of Comparative Neurology
Volume444
Issue number3
DOIs
StatePublished - Mar 12 2002
Externally publishedYes

Keywords

  • Brainstem
  • Innervation
  • Multimodal
  • Peptidergic
  • Sensory

ASJC Scopus subject areas

  • Neuroscience(all)

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