Motivation: Spices in food and beverages and compounds in tobacco smoke are supposed to interact with sensory irritant receptors of the transient receptor potential (TRP) cation channel family. TRPV1, TRPA1 and TRPM8 not only elicit action potential signaling through trigeminal nerves, eventually evoking pungent or cooling sensations, but by their calcium conductance they also stimulate the release of calcitonin gene-related peptide (CGRP). Methods: The immunocytochemical buccal mucosa preparations were evaluated using a confocal laser scanning microscope. CGRP release was measured ex vivo using EIA kits (Bertin Pharma, Montigny-le-Bretonneux, France) as an index of neuronal activation to elucidate the chemo- and thermosensory transduction in the isolated superfused mouse buccal mucosa of wildtypes and pertinent knockouts (1). Results: The lipophilic capsaicin, mustard oil and menthol effectively get access to the nerve endings below the multi-layered squamous epithelium, while cigarette smoke and its gaseous phase were weakly effective releasing CGRP. The hydrophilic nicotine 20mM pH7.4 was ineffective unless applied unprotonated in alkaline (pH9) solution (29±2.4 pg/mL, P=0.0001, n=12; ANOVA, LSD test). TRPA1-/-, TRPV1-/- and double knockouts TRPA1/TRPV1=/= showed a reduction of this nicotine response to a similar degree in any of the three mutant strains (F3,34=15.218, P<0.001). In WT a bimodal concentration-response relationship was found for AITC with a threshold between 30-100µM, increasing response up to 300µM and much greater CGRP release at 1-10mM (F4,19=84.756, P<0.001). Also AITC 1mM activated both irritant receptors, all knockout strains showed response deficits, largest the double knockouts (F3,19=58.09; P<0.001), but only TRPA1-/- did not respond to 100µM . AITC in combination (1mM) with heat (45°C) showed supraadditive, heat-sensitizing, effects even in double knockouts, suggesting action on an unknown heat-activated channel and mustard oil receptor. Menthol caused little CGRP release by itself, but in subliminal concentration (2mM) it enabled a robust cold response that was absent in TRPM8-/- (P<0.0003, n=4,6) and strongly reduced by TRPM8 inhibitors (P=0.03, n=4,6) but retained in TRPA1-/- . Conclusions: Our results from the oral mucosa show that lipophilic irritants (capsaicin, mustard oil and menthol) contained in foodstuff and drinks easily gain access to trigeminal sensory nerves to activate TRPV1, TRPA1 and TRPM8, respectively, which sensitize to heat or cold, and mediate the release of vasodilatory CGRP. The hydrophilic nicotine requires a strongly alkaline condition to access and weakly activate TRPA1 and TRPV1, while full cigarette smoke (with nicotine) and its filtered gas phase (without nicotine) exert moderate and about equal effects likely through TRPA1.