1 1 Symposium Chemosensory Receptors Satellite DEVELOPMENT ...

209 Poster Multimodal, Chemosensory Measurement,Psychophysical, Clinical Olfactory, and TrigeminalTRPM5-EXPRESSING SOLITARY CHEMORECEPTOR CELLSIN THE MOUSE NASAL CAVITY RESPOND TO ODORS ATHIGH CONCENTRATIONSOgura T. 1 , Lin W. 1 , Margolskee R.F. 2 , Finger T.E. 1 , Restrepo D. 11 Rocky Mountain Taste & Smell Ctr, Univ of Colorado at Denver &Hlth Sci Ctr, Aurora, CO; 2 Neuroscience, Mount Sinai School ofMedicine, New York, NYThe trigeminal system in the respiratory epithelium of the nasalcavity detects airborne irritants. Previously, we reported that thetransient receptor potential channel TRPM5 is expressed in a largepopulation of solitary chemoreceptor cells (SCCs) in the mouse nasalcavity (Lin et al., Neurosci. meeting abstract. 2005); a subset of whichalso express α-gustducin (Finger et al., PNAS 2003), indicating thatdiverse populations of SCCs could be trigeminal sensors. In this study,we further characterized SCCs using immunohistochemistry and Ca 2+ -imaging. Many TRPM5-expressing cells also reacted with antibodiesagainst elements of the phospolipase C (PLC) pathway including PLCβ2 and G γ13. We also found that synaptobrevin-2, a key component insynaptic vesicle release, was present in these cells. In Ca 2+ -imagingstudies, we observed that some isolated GFP-marked TRPM5-expressing SCCs responded to high concentrations of various odorants,and the PLC inhibitor U73122 suppressed the odor-evoked Ca 2+responses, suggesting the TRM5-expressing SCCs respond to theseodors via the PLC transduction pathway. These results show thatdiverse populations of SCCs are present in the respiratory epithelium ofthe mouse nasal cavity, and that these cells are able to detect odorants athigh concentrations that act presumably as trigeminal irritants.Supported by NIH grants DC05140 (TO), DC006828 (WL), DC00566,DC04657, DC006070 (TF & DR), DC03155 (RFM).210 Poster Multimodal, Chemosensory Measurement,Psychophysical, Clinical Olfactory, and TrigeminalOLEOCANTHAL, AN ANTI-INFLAMMATORY AND ANTI-OXIDANT COMPOUND OF OLIVE OILS, ELICITS ACTIVITYIN ISOLATED TRIGEMINAL NEURONSPeyrot Des Gachons C. 1 , Bryant B. 1 , Breslin P. 1 , Beauchamp G. 11 Monell Chemical Senses Center, Philadelphia, PAPremium extra virgin olive oils are characterized by a distinctivepungency that is unusual because it is sensed primarily in the pharynxor throat and much less in the mouth. The compound responsible forthis irritation is (-)-deacetoxy-dialdehydic ligstroside aglycone, whichwe termed oleocanthal (oleo = oil; canth = sting; al = aldehyde).Thisrestricted throat irritation is remarkably similar to that elicited by thenon-steroidal, anti-inflammatory drug ibuprofen. Cyclooxygenase andlipoxygenase assays conducted with synthetic (-)-oleocanthaldemonstrated that it is a natural NSAID. This compound may thus playa significant role in the well-known health benefits associated with adiet high in extra virgin olive oil. In order to investigate the physiologyunderlying the unusual pharyngeal sensation of oleocanthal, wemeasured intracellular calcium in rat trigeminal and nodose ganglionneurons. We found that oleocanthal induces increases in intracellularcalcium in a calcium- and sodium-dependent manner in selected cells.Because the compound activates neither all of the capsaicin- nor all ofthe cool-sensitive neurons, it is unlikely that either TRPV1 or TRPM8mediate the trigeminal or nodose response to oleocanthal. Future studieswill further define the pharmacology of oleoacanthal receptors.Supported in part by NIH grants DC02995 and P50DC0670 (PASB).211 Poster Multimodal, Chemosensory Measurement,Psychophysical, Clinical Olfactory, and TrigeminalTOPOGRAPHICAL DIFFERENCES IN THE TRIGEMINALSENSITIVITY OF THE HUMAN NASAL MUCOSAScheibe M. 1 , Zahnert T. 1 , Hummel T. 1 1 Otorhinolaryngology,University of Dresden Medical School, Dresden, Saxony, GermanyBackground: Previous work suggests differences in the distribution ofhuman intranasal trigeminal receptors. The aim of this study was toinvestigate these topographical differences using anelectrophysiologcial measure of trigeminal induced activation, theNegative Mucosa Potential (NMP). Material and Methods: A total of29 young, healthy volunteers participated (16 men, 13 women; age 19-42 years). CO2 (60% v/v; stimulus duration 500 ms; interstimulusinterval 30 s) was used for trigeminal stimulation. For stimuluspresentation we used a computer controlled olfactometer (OM6b,Burghart Instruments, Wedel). Recording of the NMP was performedwith a tubular electrodes (AgAgCl, outside diameter 0.8 mm, 1%Ringer-agar). Recording sites were the anterior septum, the lowerturbinate, and the rima olfactoria. Results: Maximum amplitudes of theNMP were found at the anterior septum, lowest amplitudes wererecorded at the rima olfactoria. Conclusions: The present data suggestthat there are topographical differences in the arrangement of trigeminalneurons with the highest sensitivity in the anterior part of the nasalcavity. This finding is compatible with the idea that the trigeminalsystem acts as a sentinel of the human airways.212 Poster Multimodal, Chemosensory Measurement,Psychophysical, Clinical Olfactory, and TrigeminalPET-BASED INVESTIGATION OF CEREBRAL ACTIVATIONFOLLOWING INTRANASAL TRIGEMINAL STIMULATIONHummel T. 1 , Beuthien-Baumann B. 2 , Heinke M. 1 , Oehme L. 2 , Van DenHoff J. 3 , Gerber J.C. 4 1 Otorhinolaryngology, Univ of Dresden MedicalSchool, Dresden, Saxony, Germany; 2 Nuclear Medicine, Univ ofDresden Medical School, Dresden, Saxony, Germany; 3 Institute forBioanorganic and Radiopharmaceutical Chemistry /PET Center,Research Center Rossendorf, Dresden, Saxony, Germany;4 Neuroradiology, Univ of Dresden Medical School, Dresden, Saxony,GermanyThe present study aimed to investigate cerebral activation followingintranasal trigeminal chemosensory stimulation using O15-H2O-PET.A total of 15 healthy male volunteers participated (age range 30-58years). Using a PET scanner (ECAT EXACT HR+; Siemens, Erlangen,Germany) subjects underwent 4 sessions of 5 min each with an intervalof at least 15 min. During 2 of the sessions subjects received left-sidedCO2-stimuli (duration 1 s, interstimulus interval 3 s) embedded in aconstant stream of air (36°C, 80% rH). Stimulation started 20 s beforeintravenous injection of 1.7 GBq O15-H2O for the entire duration ofthe sampling period of 2 min. During the other two sessions subjectsreceived odorless air only. SPM99 was used for analysis of the data. In12 subjects measurements were analysed for all 4 sessions, in 3 subjectsonly one stimulation session and one resting session could be analysed.There was a pronounced activation of the trigeminal projection area atthe base of the postcentral gyrus which was more intense for the righthemisphere, contralateral to the side of stimulation. In addition,activation was also found in the orbitofrontal and the pririform cortex,respectively, which are typically found to be active followingpresentation of odors. In conclusion, the present data suggest thatintranasal trigeminal stimulation not only activates somatosensoryprojection areas, but that it also leads to activation in cerebral areasassociated with the processing of olfactory information. This may beinterpreted in terms of the intimate relation between intranasaltrigeminal and olfactory sensations.53