2009 Abstracts - Association for Chemoreception Sciences

Across all odorants and the 2 presentation conditions, as well asacross the odorants for just retronasal and for just the oral-cavityonly(OCO) presentations, there were significant differences in %correct ID, p 65%) but not OCO (≤ 33%), with OCO geraniol ID at 0%.For 4 of the 6 odorants, retronasal median % correct ID werelarger than corresponding OCO median % correct ID. Within thestudied set of odorants, ID of dl-menthol was difficult.CONCLUSIONS: TRPM8 agonists do not share a commonodorant ID and are responded to differently both betweenretronasal versus OCO presentations and for OCO per se.The OCO differences suggest that TRM8 classification is notsufficient to predict trigeminal responses to odorants. Supportfrom the Food Science Summer Scholars Program, the BiologicalSciences Honors Program, and a Susan Lynn Sage Professorship#P254 Poster session VI: Chemosensory developmentand Psychophysics IEph/Ephrin Expression in the Developing and AdultTaste SystemGennadiy Katsevman, Michael Oleksiak, Natalia Hoshino, MWilliam RochlinLoyola University Chicago Chicago, IL, USAWe are profiling the expression of Eph receptors and their Ephrinligands in the taste system of embryonic to adult mouse and rat.Both classes of protein can initiate signaling cascades that underliecontact dependent repulsion or adhesion, thereby influencingaxon pathfinding, target selection, and epithelial cell arrangement.“Forward” signaling refers to signaling within the Eph-bearingcell; “reverse” signaling is for Ephrin-bearing cells. In E11.5 and14.5 mouse, EphrinB1 is detected in mandibular and chordatympani axons that are bordered by EphB2-positive and EphB3-positive cells, respectively. Thus, reverse signaling could constrictthese axons to their paths. In the tongues of embryonic mouse/ratand postnatal rat, however, anti-EphB1,2,3 labels geniculate andtrigeminal axons; and Ephrins B1 and B2 are most concentrated inthe non-gustatory epithelium avoided by these axons (mouseonly). These data are consistent with a role for forward signalingin restricting the exploration of sensory axons in the target.EphA4, EphA7, and EphrinA2 are also present in embryonicmouse geniculate and trigeminal nerves. We have not detectedEph receptors or ephrins in adult mouse/rat sensory nerves, butboth classes are detected in other adult tissues: In mouse,EphrinB1 and B2 staining of non-gustatory epithelium persists,and EphrinB1 is also detected at low levels within taste buds.In rat fungiform papillae, anti-EphA4 labels taste buds and anti-EphA7 appears to label microvasculature. These results areconsistent with a role for Eph/ephrin signaling in axon guidanceand targeting during development and plasticity, and perhapsduring recovery following injury. In vitro functional assays areunderway to determine if Eph/ephrin signaling supports orinhibits sensory axons throughout development.#P255 Poster session VI: Chemosensory developmentand Psychophysics IInvestigation of detection and pain thresholds at different sitesat the human nasal mucosa in response to electrical stimuliMandy Scheibe, Annika SchmidtSmell & Taste Clinic, Department of Otorhinolaryngology,University of Dresden Medical School Dresden, GermanyBackground: Previous investigations in humans suggestdifferences in the distribution of intranasal trigeminalchemosensitivity. The aim of the present study was to investigatethese topographical differences in the human nasal mucosa usingunspecific electrical stimuli. Material and Methods: A total of 27young, healthy volunteers participated (11 men, 16 women; age22-30 years). Detection and pain threshold of trigeminal stimuliwere investigated at 5 different sites at the nasal mucosa: anteriorseptum, posterior septum, lower turbinate, middle turbinate andanterior lateral nasal wall. Electrical stimuli were applied with aspherical electrode. Results: At the anterior parts of the nosesignificantly higher trigeminal sensitivity was found than at theposterior part. There was a similar distribution pattern of thesensitivity for detection and pain thresholds. Conclusions: Thepresent data suggest that there are topographical differences in thedistribution of trigeminal receptors at the human nasal cavity.Thereby it seems that the highest sensitivity is located in theanterior part. This finding is compatible with the idea that thetrigeminal system acts as a sentinel of the human airways withregard to toxic agents.#P256 Poster session VI: Chemosensory developmentand Psychophysics ITime-Intensity ratings of nasal irritation from pulsedhomologous alcoholsPaul M Wise, Kai Zhao, Charles J WysockiMonell Chemical Senses Center Philadelphia, PA, USARelatively few studies have focused on how nasal irritationchanges over time. To simulate the rhythm of natural respiration,subjects received 3-sec pulses of VOC (volatile organiccompound) interspersed with 3-sec pulses of clean air. Each trial,subjects received nine VOC pulses over 51 sec. Subjects ratednasal irritation from each pulse using magnitude estimation.Within a trial, compound and concentration were fixed.Compound (n-ethanol, n-butanol, and n-hexanol) andconcentration (four levels for each compound) varied across trials.Findings: 1) For all stimuli, rated irritation decreased over time(adaptation). Plots of log rated intensity versus elapsed time wereapproximately linear (intensity decreased by a fixed ratio per unittime). Interestingly, the slopes of intensity versus time functionsdiffered very little: Regardless of concentration and compound,rated irritation decreased by about 30 or 40% over the ninepulses. 2) For a given compound, the slopes of intensity versusconcentration (psychophysical) functions remained constantacross pulses. Overall intensity decreased over time, but the106 | AChemS Abstracts 2009