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Distribution of TRPV1‐ and TRPV2‐immunoreactive afferent nerve endings in rat trachea
Author(s) -
Yamamoto Yoshio,
Sato Yoshikazu,
Taniguchi Kazuyuki
Publication year - 2007
Publication title -
journal of anatomy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.932
H-Index - 118
eISSN - 1469-7580
pISSN - 0021-8782
DOI - 10.1111/j.1469-7580.2007.00821.x
Subject(s) - trpv1 , nodose ganglion , calcitonin gene related peptide , anatomy , free nerve ending , nociception , neuropeptide , dorsal root ganglion , retrograde tracing , nucleus ambiguus , chemistry , plexus , immunohistochemistry , pathology , medicine , central nervous system , medulla oblongata , endocrinology , vagus nerve , receptor , dorsum , stimulation , transient receptor potential channel
Nociception in the trachea is important for respiratory modulation. We investigated the distribution, neurochemical characteristics, and origin of nerve endings with immunoreactivity for candidate sensor channels, TRPV1 and TRPV2, in rat trachea. In the epithelial layer, the intraepithelial nerve endings and dense subepithelial network of nerve fibers were immunoreactive for TRPV1. In contrast, TRPV2 immunoreactivity was observed mainly in nerve fibers of the tracheal submucosal layer and in several intrinsic ganglion cells in the peritracheal plexus. Double immunostaining revealed that some TRPV1‐immunoreactive nerve fibers were also immunoreactive for substance P or calcitonin gene‐related peptide, but neither neuropeptide colocalized with TRPV2. Injection of the retrograde tracer, fast blue, into the tracheal wall near the thoracic inlet demonstrated labeled neurons in the jugular, nodose, and dorsal root ganglia at segmental levels of C2–C8. In the jugular and nodose ganglia, 59.3% (70/118) and 10.7% (17/159), respectively, of fast blue‐labeled neurons were immunoreactive for TRPV1, compared to 8.8% (8/91) and 2.6% (5/191) for TRPV2‐immunoreactive. Our results indicate that TRPV1‐immunoreactive nerve endings are important for tracheal nociception, and the different expression patterns of TRPV1 and TRPV2 with neuropeptides may reflect different subpopulations of sensory neurons.