1 1 Symposium Chemosensory Receptors Satellite DEVELOPMENT ...

205 Poster Multimodal, Chemosensory Measurement,Psychophysical, Clinical Olfactory, and TrigeminalDETERMINATION OF ORAL TRIGEMINAL SENSITIVITY INHUMANSJust T. 1 , Steiner S. 1 , Pau H. 1 1 Otorhinolaryngology, University ofRostock, Rostock, Mecklenburg-West Pomerania, GermanyThe aim of this study was to establish a clinical test for determinationof oral trigeminal sensitivity. Capsaicin impregnated filter paper strips(5 concentrations: 0.0001–1%) were used for threshold tests of thedorsal anterior tongue. The strips were placed on the tongue for 10 s andthe subjects were asked for onset of any sensation, quality (9 trigeminaland 4 taste descriptors), and duration of sensation. Intensity ratings wereassessed after 10s stimulation. Thresholds were estimated in two ways:(1) the lowest concentration where subjects consistently indicated thatthey perceived a “burning,” “stinging,” or “hot” stimulus (THRESH1),and (2) the lowest concentration the pain intensity of which was rated 2and higher on a 10-item scale (THRESH2). The test was applied to 63nondesensitized healthy subjects (mean age 40 years; 34f, 29m). Thesedata were correlated to measures of gustatory sensitivity obtained with“taste strips” (filter papers impregnated with tastants). With regard towhole-mouth testing THRESH1 and THRESH2 exhibited a significantcorrelation (r63 =0.41, p < 0.001). Coefficients of correlations betweentest and retest were r25 = 0.67 (p < 0.001) for THRESH1 and r25 = 0.73(p 0.25). In conclusion, capsaicin threshold testappears to be a useful diagnostic tool for assessment of the intraoraltrigeminal sensitivity.206 Poster Multimodal, Chemosensory Measurement,Psychophysical, Clinical Olfactory, and TrigeminalCONCENTRATION-DETECTION FUNCTIONS FOR EYEIRRITATION FROM HOMOLOGOUS N-ALCOHOLSAPPROACHING A CUT-OFF POINTCometto-Muniz J.E. 1 , Cain W.S. 1 , Abraham M.H. 2 1 ChemosensoryPerception Laboratory, Surgery (Otolaryngology), University ofCalifornia, San Diego, La Jolla, CA; 2 Chemistry, University CollegeLondon, London, United KingdomThe study aims to measure and to model concentration-detectionfunctions for eye irritation. Based on previous studies, we selectedhomologous n-alcohols with carbon chain length reaching values whereocular detection begins to fail (cut-off effect). Failure of a vapor to eliciteye irritation could rest on a chemical-structural or a concentrationlimitation. The stimuli comprised 1-nonanol, 1-decanol, and 1-undecanol delivered to the eye for 6 sec at 2.5 L/min by a computercontrolledvapor delivery device. Delivered vapor concentrations (ppmby volume) were measured by gas chromatography. Twenty-twosubjects (16 females) were tested using a 3-alternative forced-choiceprocedure against humidified air blanks. As expected, detectionprobability (P), i.e., detectability, increased with vapor concentration.Close to vapor saturation, nonanol approached perfect detection,whereas decanol and undecanol barely reached halfway (P = 0.5)between chance (P = 0.0) and perfect (P = 1.0) detection. In fact,undecanol reached a ceiling in detectability (P = 0.5) even below vaporsaturation, and further increases in concentration failed to increasedetectability. The outcome provides additional support to the notion thatthe cut-off in eye irritation at the level of 1-undecanol rests on achemical-structural limitation rather than on a concentration limitation.Supported by grant R01 DC 005003 from the NIDCD, NIH and byPhilip Morris.207 Poster Multimodal, Chemosensory Measurement,Psychophysical, Clinical Olfactory, and TrigeminalTRPV1 RECEPTORS AND NASAL TRIGEMINALCHEMESTHESISSilver W.L. 1 , Clapp T.R. 2 , Stone L.M. 2 , Kinnamon S.C. 2 1 Biology,Wake Forest University, Winston-Salem, NC; 2 Biomedical Sciences,Colorado State University, Fort Collins, COThe trigeminal nerve responds to a variety of irritants in theenvironment and serves a protective role. Trigeminal nerve fibersexpress several receptors including TrpV1 (vanilloid receptor 1), ASICs(acid sensing ion channels), and P2X (purinergic receptors). TrpV1 isactivated by capsaicin (CA) and acids, although its role in thetransduction of other irritants has not been determined. The irritants:amyl acetate, AA; cyclohexanone, CY; acetic acid, AC; toluene, TO;benzaldehyde, BE; (–)-nicotine, NI; (R)-(+)-limonene, LI; (R)-(–)-carvone, RCR; (S)-(+)-carvone, SCR, and CA) all stimulate thetrigeminal nerve when delivered in solution to the nasal cavity of rats,but their mechanism of action is unclear. We have used standardcalcium imaging techniques to examine responses of TrpV1 receptors tothese chemical irritants. For these experiments, TrpV1 and GFPconstructs were co-transfected into HEK293t cells. Three irritants (AC,SCR and RCR) stimulated non-transfected controls and were not testedfurther. Two irritants (CA and CY) stimulated only transfected cells,and the response could be eliminated with capsazepine, a TrpV1blocker. The five remaining irritants (NI, BE, AA, LI, and TO) werenonstimulatory in both non-transfected and transfected cells, suggestingthey utilize a different receptor mechanism. These results suggest thatTrpV1 serves as a receptor for both CY and CA in trigeminal nerveendings. Supported by RO1DC006070-03.208 Poster Multimodal, Chemosensory Measurement,Psychophysical, Clinical Olfactory, and TrigeminalFOOD FLAVORS AND THE SWEETENER SACCHARINACTIVATE THE TRANSIENT RECEPTOR POTENTIALVANILLOID SUBTYPE 1 (TRPV1) CHANNEL.Riera C. 1 , Damak S. 1 , Le Coutre J. 1 1 Nestle Research Center, Verschez-les-Blancs,Lausanne, SwitzerlandChemosensory perception of food relies on olfaction, taste andtrigeminal sensation and several volatile organic compounds naturallypresent in food stimulate these senses. Many artificial sweetenersactivate two taste modalities (sweet and bitter at higher concentrations),but it is not known whether these molecules can also inducechemesthesis. The sensation of irritation is initiated by pungentmolecules activating Trp channels expressed in sensory nerve endingsof the trigeminal nerve. Capsaicin, the pungent molecule in hot chillipeppers, and other irritant molecules are known to activate the heatgated vanilloid receptor TRPV1. We investigated whether severalaromas and artificial sweeteners activate TRPV1, using Fura-2-basedCalcium imaging of a HEK293 cell line heterologously expressingTRPV1. Aromas at 1mM (Thujone, Geraniol, Linalool, Coumarine,Citral, p-Anisalehyde, Menthone) elevate intracellular [Ca 2+ ] i and thisresponse is decreased in the presence of the TRPV1 inhibitorcapsazepine. At one millimolar concentration Limonene, β-Pinene,Safrole, (+) and (-) Carvones, Cyclohexanol, and Thymol do notactivate the TRPV1 channel. Saccharin, a common artificial sweetener,strongly activates TRPV1 at 1 mM and at 10 mM. This response ispartially inhibited by capsazepine. Aspartame at 1 mM does not activatethe channel. All agonists listed here are lacking the vanilloid groupcharacteristic of Capsaicin but their hydrophobicity suggests they mightbind TRPV1 by diffusion through the cell membrane as does capsaicin.Taken together the data show that several food flavors and saccharincan stimulate the trigeminal system by activating the vanilloid receptor.52