The Distribution of TRPV1 and TRPV2 in the Rat Pharynx

Abstract

Immunohistochemistry for two nociceptive transducers, the transient receptor potential cation channel subfamily V members 1 (TRPV1) and 2 (TRPV2), was performed on the pharynx and its adjacent regions. TRPV1-immunoreactivity (IR) was detected in nerve fibers beneath and within the epithelium and/or taste bud-like structure. In the pharynx, these nerve fibers were abundant in the naso-oral part and at the border region of naso-oral and laryngeal parts. They were also numerous on the laryngeal side of the epiglottis and in the soft palate. TRPV2-IR was expressed by dendritic cells in the pharynx and epiglottis, as well as in the root of the tongue and soft palate. These cells were located in the epithelium and lamina propria. TRPV2-immunoreactive (IR) dendritic cells were numerous in the naso-oral part of the pharynx, epiglottis, and tongue. Abundance of TRPV2-IR dendritic processes usually obscured the presence of TRPV2-IR nerve fibers in these portions. However, some TRPV2-IR nerve fibers could be observed in the epithelium of the soft palate. Retrograde tracing method also revealed that sensory neurons which innervate the pharynx or soft palate were abundant in the jugular-petrosal ganglion complex and relatively rare in the nodose ganglion. In the jugular-petrosal ganglion complex, TRPV1- and TRPV2-IR were expressed by one-third of pharyngeal and soft palate neurons. TRPV2-IR was also detected in 11.5 % pharyngeal and 30.9 % soft palate neurons in the complex. Coexpression of TRPV1 and CGRP was frequent among pharyngeal and soft palate neurons. The present study suggests that TRPV1- and TRPV2-IR jugular-petrosal neurons may be associated with the regulation of the swallowing reflex.

Oropharyngeal and laryngeal sensory innervation in the pathophysiology of swallowing disorders and sensory stimulation treatments

“…S3). In experiments using animal tissue, TRPV1 has been located in nerves supplying rat pharynx, epiglottis, and soft palate …”

Breathing hot humid air induces airway irritation and cough in patients with allergic rhinitis

“…Among them, the potential involvement of TRPV1 merits further consideration. TRPV1 is abundantly expressed on the nerve terminals of the vagal and non-vagal C-fiber afferents innervating the entire respiratory tract, including the larynx, pharynx and upper airways (Hamamoto et al, 2008; Hamamoto et al, 2009; Lee and Yu, 2014; Sasaki et al, 2013; Yamamoto and Taniguchi, 2005). Using the whole-cell perforated patch clamping technique, our laboratory has recently demonstrated that an increase in temperature within the normal physiological range (35-41 °C) evoked inward currents (in voltage-clamp mode), and membrane depolarization and action potentials (in current-clamp mode) in isolated vagal pulmonary sensory neurons (Ni et al, 2006).…”

“…TRPV1 is also abundantly expressed in the sensory nerve fibers innervating the pharynx, larynx and upper airways (Hamamoto et al, 2008; Hamamoto et al, 2009; Sasaki et al, 2013; Yamamoto and Taniguchi, 2005). However, whether the sensitivity of these TRPV1-expressing sensory nerves is elevated resulting from the chronic inflammation of upper airways in AR patients is not yet known, and the reflex responses elicited by an increase in airway temperature in these patients have not been previously studied.…”

TRPs in Taste and Chemesthesis

“…This TRP channel is abundantly expressed in the mouse trigeminal ganglion (Vandewauw et al 2013), and TRPV2-immunopositive fibers are present in oral and nasal epithelium (Nakashimo et al 2010; Sasaki et al 2013). Dendritic and Langerhans cells within the epithelium also are reported to be TRPV2 immunopositive (Shimohira et al 2009; Sasaki et al 2013). Yet even given this pattern of expression in fibers and oronasal epithelium, a role for TRPV2 in chemesthesis is not readily apparent.…”