Abstracts - Association for Chemoreception Sciences

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P O S T E R S behavioral differences are associated with variation in peripheral taste responsiveness. Mice were anesthetized, the CT was accessed by exposing the nerve’s passage through the inner ear, and NaCl and other solutions were flowed over the anterior tongue in order to measure the integrated whole-nerve response. NaCl was applied before, during, and after application of 100 micromolar amiloride. Responses to low concentrations of NaCl were significantly larger in A/J than B6 mice, despite the relatively high behavioral threshold for NaCl in the former strain. This difference in NaCl response magnitude arose due to a larger amiloride-insensitive NaCl response in A/J mice, whereas the amiloride-sensitive component of the NaCl response was similar in the two strains. These data support a role for peripheral taste mechanisms in causing the strain differences in behavioral taste thresholds for NaCl. However, the results suggest that detection of NaCl by mice depends on the ratio of amiloride-sensitive and – insensitive responses in the CT, rather than on the absolute level of the whole-nerve response to NaCl or on the size of the amiloride-sensitive component alone. Ishiwatari Y, Bachmanov AA. NaCl taste thresholds in 13 inbred mouse strains. 29th AChemS annual meeting, Sarasota, Florida. April 25-29, 2007. Chem. Senses 32: A26, 2007. #P151 POSTER SESSION III: OLFACTORY PERCEPTION, HUMAN PSYCHOPHYSICS & ANIMAL BEHAVIOR; PERIPHERAL TASTE DEVELOPMENT & SIGNALING Differential regulation of chorda tympani (CT) taste nerve responses to sweet, salty, bitter and umami taste stimuli by phosphatidylinositol 4, 5-bisphosphate (PIP2) Vijay Lyall, Tam-Hao T Phan, Shobha Mummalaneni, Melone Pamela, John A. DeSimone Department of Physiology & Biophysics, Virginia Commonwealth University Richmond, VA, USA To investigate the regulation of taste responses by changes in membrane PIP2 levels in taste receptor cells, we monitored rat CT responses to sweet, bitter, umami and salty stimuli before and after topical lingual application of a short chain synthetic PIP2 (diC8-PIP2; 250 mM) dissolved in dimethyl sulfoxide. Tonic CT responses to 500 mM sucrose, 5 mM SC45647, 250 mM glycine and 10 mM quinine were enhanced after lingual application of diC8-PIP2 relative to control. DiC8-PIP2 treatment inhibited the CT response to 100 mM NaCl relative to control. The decrease in the NaCl CT response was due to a decrease in the putative benzamil (Bz)-insensitive TRPV1t-dependent NaCl component of the CT response. DiC8-PIP2 had no effect on the Bz-sensitive ENaC component of the NaCl CT response. DiC8-PIP2 also did not alter the CT response to 100 mM monosodium glutamate (MSG)+5 mM Bz+1 mM SB-366791 (SB) relative to control. However, diC8-PIP2 inhibited the increase in the CT response to MSG+Bz+SB+1 mM inosine 5’-phosphate (IMP) relative to MSG+Bz+SB observed under control conditions. Bz and SB were added to the stimulus solution to eliminate the contribution of Na + to MSG CT response. We conclude that PIP2 is a common intracellular effector involved in the transduction of sweet, bitter, umami and TRPV1t-dependent salt tastes. While PIP2 enhances CT nerve responses to sweet and bitter stimuli, it inhibits the synergistic effect of IMP on MSG CT responses and the putative Bz-insensitive TRPV1t-dependent component of the NaCl CT response. An increase in PIP2 inhibits salt taste by directly interacting with TRPV1t and enhances sweet and bitter CT responses by modulating PLCb2 activity. Alternately, PIP2 may compete with the IMP binding site on the umami receptor and inhibit CT responses to MSG+IMP. Acknowledgements: Supported by grants DC-000122 (VL) and DC-005981 (VL) from NIH/NIDCD. #P152 POSTER SESSION III: OLFACTORY PERCEPTION, HUMAN PSYCHOPHYSICS & ANIMAL BEHAVIOR; PERIPHERAL TASTE DEVELOPMENT & SIGNALING PKD2L1 is required for normal chorda tympani nerve responses to acids Nao Horio 1 , Ryusuke Yoshida 1 , Yoshiro Ishimaru 2 , Hiroaki Matsunami 3 , Yuzo Ninomiya 1 1 Section of Oral Neuroscience, Graduate School of Dental Science, Kyushu University Fukuoka, Japan, 2 Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo Tokyo, Japan, 3 Department of Molecular Genetics and Microbiology, Duke University Medical Center Durham, NC, USA Recent studies have suggested that the polycystic kidney diseaseslike ion channel PKD2L1 and its associated partner PKD1L3 are potential candidate for sour taste receptors. PKD2L1 and PKD1L3 are shown to be coexpressed in a subset of taste cells in the posterior tongue innervated by the glossopharyngeal (GL) nerve, while only PKD2L1 is expressed in the anterior tongue innervated by the chorda tympani (CT) nerve. In a heterologous system, PKD1L3-PKD2L1 channel complex responds to acids with an off-response property. In vivo, genetic elimination of cells expressing PKD2L1 substantially reduces CT nerve responses to sour taste stimuli. However, in vivo function of PKD1L3 and PKD2L1 remains unclear. In this study, we measured CT and GL nerve responses to various taste stimuli in PKD1L3 knock-out (1L3KO), PKD2L1 knock-out (2L1KO), PKD1L3 and PKD2L1 double knock-out (DKO) mice in comparison with wild type (WT) mice. We found that 2L1KO and DKO mice showed significantly decreased responses of the CT nerve to acids (HCl, citric and acetic acid) without affecting responses to salty, bitter, sweet and umami compounds, while no such difference in acid responses was observed between 1L3KO and WT mice. In the GL nerve, magnitudes of responses to acids in the 3 KO strains were not significantly different from those of WT mice. In single CT fiber response measurements, we found that spike frequencies of acid-responsive fibers to acids were significantly lower in 2L1KO mice than WT mice. These results suggest that PKD2L1 is essential for normal sour taste transduction, at least in the anterior region of the tongue innervated by the CT nerve. #P153 POSTER SESSION III: OLFACTORY PERCEPTION, HUMAN PSYCHOPHYSICS & ANIMAL BEHAVIOR; PERIPHERAL TASTE DEVELOPMENT & SIGNALING Comparative analysis of ENaC and TRPV1-mediated NaCl responses of the rat chorda tympani nerve Joanne M Garcia, Robert J Contreras Department of Psychology and Program in Neuroscience, Florida State University Tallahassee, FL, USA NaCl taste transduction consists of two putative components: the first a highly selective cation epithelial channel for Na + (ENaC) that can be blocked pharmacologically by amiloride or benzamil; 78 | AChemS Abstracts 2010 Abstracts are printed as submitted by the author(s)
the second a non-specific cation channel of the TRP family (TRPV1t) that is broadly responsive to Na + as well as K + , NH4 + , and Ca 2+ salt solutions. We examined the ENaC-mediated portion by comparing the relative effectiveness of amiloride and the more selective amiloride analog, benzamil in suppressing NaCl responses of the chorda tympani nerve (CT) in male Sprague- Dawley rats. In addition, we assessed the nonselective pathway by recording responses to 100mM NaCl mixed with 1mM SB-366791, a TRPV1 antagonist. We recorded whole nerve activity from the CT in response to lingual application of NaCl (100, 300, 600mM) and all NaCl concentrations mixed with either 100mM amiloride or 4mM benzamil in artificial saliva (15mM NaCl, 22mM KCl, 3mM CaCl 2 , 0.6mM MgCl 2 ). All taste stimuli were delivered for 10 s at a constant flow rate of 50 ml/s and temperature of 35°C and were preceded and followed by 60-s rinses with artificial saliva. Preliminary data (n = 3) indicate that amiloride was more effective than benzamil in suppressing CT responses to NaCl. Amiloride suppressed CT responses by 54% across all NaCl concentrations, while benzamil suppression decreased with increasing NaCl concentration (44% at 100mM NaCl and 26% at 600mM NaCl). Benzamil suppression may be less than that for amiloride because the effective concentrations were not matched or because amiloride affects more than ENaC. Furthermore, SB-366791 suppressed 100mM NaCl responses by only 10%, suggesting that the nonselective cation pathway of NaCl taste transduction may involve mechanisms other than TRPV1. Acknowledgements: NIH grants R01 DC04785, T32 DC00044 #P154 POSTER SESSION III: OLFACTORY PERCEPTION, HUMAN PSYCHOPHYSICS & ANIMAL BEHAVIOR; PERIPHERAL TASTE DEVELOPMENT & SIGNALING Anion Size Attenuates Summated Epithelial Potentials of Tongue and Single-cell Responses of Geniculate Ganglion Neurons to TRPV1-mediated Salt Stimulation in Rats Joseph M Breza, Joanne M Garcia, Robert J Contreras Florida State University Tallahassee, FL, USA In anesthetized male rats, we recorded stimulus-evoked summated lingual epithelial potentials (Electrogustogram; EGG) from the anterior two thirds of the tongue simultaneously with single-cell responses in the geniculate ganglion (n = 17). Artificial saliva (15mM NaCl, 22mM KCl, 3mM CaCl 2 , 0.6mM MgCl 2 ) at 35°C served as the rinse solution and solvent for all taste stimuli. Each stimulus was applied 3-9 times. The average responses to 0.5 M sucrose, 0.1 M NaCl, 10 mM citric acid, and 20 mM quinine hydrochloride, as well as 0.1 M KCl separated neurons into 2 Sucrose-specialists, 7 NaCl-specialists, and 8 Acid-generalists. EGG and single-cell responses were also measured to ascending concentrations of NaCl and NaGluconate (0.03, 0.1, 0.3, and 0.5 M). We used 1 µM Benzamil (Bz) and 1 µM SB366791 (SB) to distinguish 0.1 M NaCl evoked neural responses mediated via ENaC and TRPV1 channels, respectively. EGG amplitude and neural spike frequency increased, while neural response latency decreased with increasing NaCl and NaGluconate concentration. EGG amplitude to NaCl stimulation was 3X greater than that to NaGluconate at each concentration. Sucrose-specialist neurons were virtually unresponsive to Na + salts, even at the highest salt concentration. For NaCl-specialist neurons, response latency and frequency was similar to stimulation with both Na + salts. In contrast, response frequency was less and response latency longer to NaGluconate than to NaCl in Acid-generalist neurons. In NaCl-specialists, Bz decreased NaCl responses by 39%; in Acid-generalists, SB decreased NaCl responses by 20%. This latter effect is in concert with integrated chorda tympani nerve recordings from our lab. Together, these data support the notion of independent processing pathways for Na + in fungiform papillae. Acknowledgements: Supported by NIH grants RO1 DC004785, F31 DC009920 #P155 POSTER SESSION IV: CHEMOSENSORY TRANSDUCTION AND SIGNALING Estrogen Modulates Excitability and Olfactory Responses in Mouse Vomeronasal Neurons Suraj Cherian, Ian McDaniels, Chun Yang, Rona J. Delay Department of Biology, University of Vermont Burlington, VT, USA Aggression and parental care are behaviors that are often mediated by chemical cues. Many of these chemical responses occur in the vomeronasal organ (VNO). Vomeronasal sensory neurons (VSNs) are the chemical sensors of the VNO and express specific odor receptors that are G-protein coupled and linked to a PLC pathway. While hormonal modulation of neurons in the CNS by steroids has been well established in mammals little is known about such modulation in VSNs especially rapid (non-genomic) effects of estrogen. To determine if estrogen plays a role in the VNO in mice, RT-PCR was used to determine that the mRNA for two estrogen receptors GPR30, a G -protein coupled estrogen receptor and the classical a-estrogen receptor were present in the VNO but not the b isoform estrogen receptor. Immunocytochemistry revealed that it was the VSNs that labeled for GPR30. Recording from isolated VSNs, using perforated patch clamp, showed that physiological concentrations (1nM) of 17b-estradiol can hyperpolarize the membrane by 3-5mV (n=5 out of 6 cells) and decrease the spontaneous firing of action potentials (n=3 out of 6 cells). VSNs respond to urine, a natural stimulus that is a complex mixture of pheromones, metabolites and salts. Estrogen was found to inhibit urine-induced current responses by 50% or more (n=16 out of 17 cells). Also in 3 out of 5 cells urine-induced action potentials decreased in the presence of estrogen. By studying such effects and dissecting the pathways behind it, a better understanding of how behavior is modulated by the every-changing concentration of hormones that occurs in response to internal and external cues may be possible. Acknowledgements: NIH-DC006939 & NIH-P20RR16435 #P156 POSTER SESSION IV: CHEMOSENSORY TRANSDUCTION AND SIGNALING Variation in vomeronasal receptor expression in a terrestrial salamander Sarah K. Woodley 1 , Karen M. Kiemnec-Tyburczy 2 , Lynne D. Houck 3 1 Duquesne University Pittsburgh, PA, USA, 2 Cornell University Ithaca, NY, USA, 3 Oregon State University Corvallis, OR, USA Individuals vary in their physiological and behavioral responses to sensory information. It is unknown whether individual differences at the level of the peripheral sensory organ contribute to individual variation at the organismal level. We studied pheromone detection by the vomeronasal system in a terrestrial salamander (Plethodon shermani). In this species, the volume of the vomeronasal organ (VNO) varied both within and between males and females. Using degenerate primers, V2R fragments have P O S T E R S Abstracts are printed as submitted by the author(s) Abstracts | 79
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AChemS Association for Chemorecepti
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AChemS Association for Chemorecepti
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We are pleased to announce that sev
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#1 GIVAUDAN LECTURE Normal and Canc
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and against delta ENaC is being pur
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#13 SYMPOSIUM - GENETICS OF HUMAN O
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#19 SYMPOSIUM - CILIA, SENSORY DYSF
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#26 PLATFORM PRESENTATIONS - POLAK
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esponse selectivity for both OSNs a
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elicit glucagon-like peptide-1 (GLP
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contrast, changing the concentratio
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of OBPs, we have systematically sup
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whereas mouse and joystick reaction
Page 29 and 30: POSTER PRESENTATIONS #P1 POSTER SES
Page 31 and 32: PROP strips and PROP solutions. PAV
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Page 53 and 54: hours later, the levels of prolifer
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Page 63 and 64: gene, HMBS was used. All primers we
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Page 73 and 74: decreasing of endogenous volatiles
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wing. Philip Callahan exposed insec
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seem to indicate that total nasal v
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possibly suggesting non-apoptotic m
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#P325 POSTER SESSION VII: OLFACTORY
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of 7/10, and causing eyes to water
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showed that N1/P2 latencies were lo
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differentiated patients with AD (M=
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pleasantness 3)of mixtures (A,B), A
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Index Aarts, H - P328 Abe, K - P88,
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Haase, L - P3, P4, P29, P355 Haddad
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Murata, Y - P272 Murphy, C - P3, P4
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Veldhuizen, M - P7, P24, P25, P242,
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Registration 7:30 am to 1:00 pm, 6:
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See you next year! AChemS 33rd Annu
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Abstracts - Association for Chemoreception Sciences

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