Distribution of vanilloid receptors in the rat laryngeal innervation.
OBJECTIVE
Capsaicin is known to selectively activate nociceptic sensory neurons through vanilloid receptors. In this study we investigated the distribution of vanilloid receptor subtype 1 (VR1) and vanilloid receptor-like protein 1 (VRL-1) in the rat larynx.


METHODS
The distributions of VR1 and VRL-1 were determined immunohistochemically. The colocalization of vanilloid receptors with common choline acetyltransferase (cChAT), vasoactive intestinal polypeptide (VIP), substance P (SP) and neuronal nitric oxide synthase (nNOS) was also studied using an immunohistochemical double-labeling technique.


RESULTS
VRL-1-positive fibers were detected in the laryngeal epithelium and lamina propria. VR1-positive nerve fibers were seen in the lamina propria but not in the mucosal epithelium. VR1- and VRL-1-positive cells were distributed in the intralaryngeal ganglia and colocalization of capsaicin receptors with VIP, nNOS and cChAT was seen.


CONCLUSIONS
These findings suggest that these capsaicin receptors participate in the parasympathetic innervation as well as in nociception of the rat larynx.
Koike
Shinobu
S
Department of Otolaryngology, Kyoto Prefectural University of Medicine, Kyoto, Japan.
Uno
Toshiyuki
T
Bamba
Hitoshi
H
Shibata
Toshiaki
T
Okano
Hiroyuki
H
Hisa
Yasuo
Y
D000818:Animals; D002211:Capsaicin / Q000378:metabolism; D007150:Immunohistochemistry; D007473:Ion Channels; D007820:Laryngeal Mucosa / Q000294:innervation; D007823:Laryngeal Nerves / Q000378:metabolism*; D009412:Nerve Fibers / Q000378:metabolism; D009619:Nociceptors / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D011955:Receptors, Drug / Q000378:metabolism*; D050916:TRPV Cation Channels
D007473:Ion Channels; D011955:Receptors, Drug; D050916:TRPV Cation Channels; C494484:TRPV1 receptor; C476722:Trpv2 protein, rat; D002211:Capsaicin