Three sensory systems, olfaction, taste, and somatosensation, are dedicated to the de-tection of chemicals in the environment. Trigeminal somatosensory neurons enable usto detect a wide range of environmental stimuli, including pressure, temperature, andchemical irritants, within the oral and nasal mucosa. Natural plant-derived irritantshave served as powerful pharmacological tools for identifying receptors underlying so-matosensation. This is illustrated by the use of capsaicin, menthol, and wasabi to iden-tify the heat-sensitive ion channel TRPV1, the cold-sensitive ion channel TRPM8, andthe irritant receptor TRPA1, respectively. In addition to TRP channels, members of thetwo-pore potassium channel family have also been implicated in trigeminal chemosen-sation. KCNK18 was recently identified as a target for hydroxy-a-sanshool, the tinglingand numbing compound produced in Schezuan peppers and other members of the Xan-thoxylum genus. The role of these channels in trigeminal thermosensation and pain willbe discussed.
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