Distribution of vanilloid receptors in the rat laryngeal innervation

Abstract

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.

Material and 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.

Conclusion These findings suggest that these capsaicin receptors participate in the parasympathetic innervation as well as in nociception of the rat larynx.

Keywords:

• common choline acetyltransferase
• intralaryngeal ganglion
• neuronal nitric oxide synthase
• nociceptor
• substance P
• vanilloid receptor like-protein 1
• vanilloid receptor subtype 1
• vasoactive intestinal polypeptide

Koike S, Uno T, Bamba H, Shibata T, Okano H, Hisa Y. Distribution of vanilloid receptors in the rat laryngeal innervation. Acta Otolaryngol 2004; 124: 515–519.

Koike S, Uno T, Bamba H, Shibata T, Okano H, Hisa Y. Distribution of vanilloid receptors in the rat laryngeal innervation. Acta Otolaryngol 2004; 124: 515–519.