Oral Epithelial Cells are Activated via TRP Channels

Transient receptor potential (TRP) ion channels are critical contributors to the perception of various environmental stimuli. Although the oral cavity is the access point for various food types, the expression of TRP channels in oral mucosa remains unknown. We hypothesized that the oral epithelium itself may participate in sensing thermal, mechanical, and chemical conditions. The expression profiles of TRP channels exhibited regional differences among the buccal, palatal, and tongue epithelia. Changes in elevated intracellular Ca²⁺ concentration ([Ca²⁺]_i) in oral epithelial cells were found after stimulation of the TRP channels with capsaicin, camphor, 4α-phorbol-12,13 didecanoate (4α-PDD), 2-aminoethoxydiphenyl borate (2-APB), and menthol. These increases in Ca²⁺ appeared dependent on the TRP channels, because [Ca²⁺]_i suppression was observed after the addition of the TRPV channel antagonist ruthenium red. These results demonstrate that the oral epithelia express various TRP channels and may have functional roles in sensory activities, together with neurons.