2009 Abstracts - Association for Chemoreception Sciences

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#P70 Poster session II: Chemosensory response to,and control of, feeding/NeuroethologySweet Stimuli Elicit Differential Responses in the ChordaTympani Nerve of Obesity-resistant Rats Compared toObesity-prone RatsKimberly R. Smith, David W. PittmanDepartment of Psychology, Wofford College Spartanburg,SC, USAintensity), but had a more complex effect on Na 2 CO 3 (suggestiveof a change in perceived quality and a reduction in perceivedintensity). Taken together with our previous work investigatingbehavioral responses to KCl and sodium gluconate, and combinedsalt appetite and taste aversion work, we conclude that sodiumappetite is driven neither by shifts in quality nor intensity, butrather in a modification of the hedonic valence of a stable perceptof salty taste.P O S T E R SPrevious research has shown that obesity-resistant, S5B/Pl ratsdifferentially prefer carbohydrate diets compared to high-fat dietpreference of the obesity-prone, OM rats. Furthermore, followinga conditioned taste aversion, OM rats appear to be more sensitivein detecting fatty acids. In vitro recordings from taste receptorcells suggest further strain differences such that fatty acids appearto produce more depolarization in the S5B/Pl rats than OM rats;however, in vivo gustatory signaling has not been examined ineither strain. This study characterized afferent gustatoryresponses of the whole chorda tympani nerve in these two strainsof rat using an array of salt (NaCl, KCl), bitter (quinine-HCl),sour (citric acid), umami (MSG), and sweet (glucose, saccharin,glucose+saccharin mixture) taste stimuli at 3 concentrations eachwith and without the presence of a fatty acid in 20-s trials.The addition of 200 µM linoleate tended to produce subtleenhancements of the neural responses to select concentrations ofthe tastants with the most consistent effects on the sweet tastestimuli. The strains showed similar neural responsiveness withineach taste category with the exception of the sweet taste stimuli.The S5B/Pl strain demonstrated greater differences in neuralresponses to glucose, saccharin, and a glucose+saccharin mixturecompared to the OM strain which showed similar responsivenessacross the three sweet stimuli. This difference in the neuralresponsiveness to sweet tastants may underlie the dietarypreference for carbohydrates observed in the S5B/Pl strain.#P71 Poster session II: Chemosensory response to,and control of, feeding/NeuroethologyThe Perceptual Consequences Of Salt Appetite In RatsSteven J. St. John, Anya C. Marshall, Erin KrauskopfDepartment of Psychology, Rollins College Winter Park, FL, USAIn rats and other mammals, a physiological sodium deficit leadsto a robust appetite for sodium that is guided by the gustatorysystem. In 1993, Breslin et al. (Am. J. Physiol., 264, R312-8)demonstrated that the inverted-U intake-concentration functionfor NaCl was preserved (but elevated) in salt-deprived rats.They concluded, in contrast to some theories of salt appetite, thatthe perceived taste intensity of NaCl is unchanged during sodiumdeprivation, since a reduction in intensity should produce arightward shift and increases in intensity a leftward shift of theresponse-concentration function. We tested the logic of thisconclusion by examining the responses of salt deprived rats toNa 2 CO 3 , a salt that G.R. Morrison reported was ten times asintense as NaCl to rats (Physiol. Behav., 8, 25-28). Furosemideinjectedrats were tested the following day for their lickingresponses to water and 7 concentrations of Na 2 CO 3 in eitherlow (0.0028 – 0.089 M) or high (0.028 – 0.89 M) concentrationranges. Consistent with Breslin et al. and Morrison, behaviortowards Na 2 CO 3 was an inverted-U shaped lickingconcentrationfunction leftward shifted from NaCl precisely oneorder of magnitude. Amiloride dose-dependently reduced theresponses to NaCl (suggesting a change in perceived quality, not#P72 Poster session II: Chemosensory response to,and control of, feeding/NeuroethologyRat as a model for the study of multimodal integrationof flavorShree H. Gautam, Justus V. VerhagenThe John B. Pierce Laboratory New Haven, CT, USANeuroimaging studies in humans have revealed that formation ofa flavor percept involves taste-odor integration. It has also beenestablished that retronasal olfaction and flavor experience playkey roles in this process. Little is known about the detailed neuralcircuitry and mechanisms underlying retronasal stimulus coding,experience and sensory integration of flavor. Since the use ofhumans precludes necessary invasive experimental procedures andcontrol of flavor experiences, we are establishing the use of rats toexplore the neuro-behavioral mechanisms of flavor perception.By optical calcium imaging of olfactory bulb responses to orallypresented odorants in awake behaving rats we ask whether andhow rats smell retronasally, and how this compares to orthonasalolfaction. We found evidence for bulbar responses to oralodorants. Both fast sniffing and fast licking attenuate ortho- andretronasal OB responses, but presumably by different means.Olfactory receptor neurons may be over-stimulated during rapidsniffing, and under-stimulated during licking and swallowing.Behaviorally, by employing conditioned odor and taste aversions,we asked whether the perceived smell of “sweet” odorants issimilar to “sweet” tastants to flavor-naive rats. Retronasalodorants (benzaldehyde and tasteless amyl acetate, CS) did notgeneralize to the prototypical tastants in naive rats. Sucrose (CS)also did not generalize to the odorants. However, the priorexperience of either odor-taste pair did result in specificgeneralization of the odorant to sucrose, suggesting a primary roleof paired odor-taste experience in the formation of flavor objects.Both lines of enquiry provide direct evidence for retronasalolfaction in rats. Thus, the rat emerges as a useful model forextensive flavor research in mammals.#P73 Poster session II: Chemosensory response to,and control of, feeding/NeuroethologyMouse Strain Differences in Conditioned Taste AversionFormation, Generalization and Extinction using aSelf-administration ParadigmApril R. Glatt, Kenichi Tokita, John D. Boughter, Jr.University of Tennessee Health Science Center Memphis,TN, USATraditional approaches to conditioned taste aversion (CTA)learning have employed pairing of a novel taste with i.p. injectionsof LiCl. However, a self-administration model involvingcontinuous licking of a LiCl solution is more comparable tonaturally developed food aversions, and allows for temporalAbstracts | 49
analysis of CTA processing (Baird et al., 2005). In this study, weanalyzed acquisition, expression and extinction of CTA inC57Bl/6J (B6) and DBA2/J (D2) mice by examining lickingbehavior to LiCl and NaCl solutions. In preliminary studies withwater-restricted mice, we obtained baseline values for waterlicking and established that B6 and D2 mice respond equivalentlyto concentration series of NaCl and LiCl in brief access tests.Methods: Water-restricted mice were trained to lick water in theMS160 lickometer. On conditioning day, mice received a 20-mintrial with either 0.12M NaCl or LiCl. For 6 days followingacquisition, mice received a 20-min trial of 0.12M NaCl. Results:On conditioning day, mice from both strains responded similarlyto NaCl and LiCl in the first minute, suggesting these stimuli arecomparable in taste. All mice receiving LiCl rapidly formed anaversion beginning in the second minute; D2 mice displayedcomplete aversion by minute 3, while B6 showed this by minute6. On the following day, both strains avoided NaCl relative tocontrols; B6 displayed comparable licks to controls by the 4 thminute, while D2s did not show this until the 8 th minute.However, D2 mice showed lick counts close to zero throughoutthe entire trial. Conclusion: B6 and D2 mice can rapidly develop aCTA to LiCl via self-administration in a lickometer. The CTAgeneralizes to NaCl the next day, but extinguishes, with B6 miceshowing a faster rate of extinction than D2 mice.#P74 Poster session II: Chemosensory response to,and control of, feeding/NeuroethologyBeyond Tas1r3: Identification of other loci affectingconsumption of sweet-tasting compoundsNatalia P. Bosak, Maria L. Theodorides, Cailu Lin, ZakiyyahSmith, Gary K. Beauchamp, Alexander A. BachmanovMonell Chemical Senses Center Philadelphia, PA, USAInbred mouse strains differ in their responses to sweet tastestimuli. Although allelic variation of the Tas1r3 locus is partiallyresponsible for these differences, our genetic analyses usingC57BL/6ByJ (B6) and 129P3/J (129) strains suggests that otherloci are also involved and that some of them are sweetenerspecific.We have further studied such loci using an F2 intercrossbetween B6 inbred and 129.B6-Tas1r3 congenic mice andsubsequent selective breeding. F2 mice varied in consumption ofthe 30 mM glycine and 20 mM saccharin and there was nocorrelation between these two traits. From the F2 generation, westarted selective breeding of two pairs of lines: with high and lowsaccharin intakes, and with high and low glycine preferences. Thephenotype-based selection resulted in divergence between thesepairs of lines, which confirms presence of loci polymorphicbetween the B6 and 129 strains. To refine positions of these loci,we have genotyped mice from the 10th and 8th generations ofselective breeding with markers on chromosomes, which werepreviously linked to glycine preference and saccharin intake,respectively. For all chromosomes, there was a significantdivergence of frequencies of alleles in these regions. For glycineselection, mice from the High line accumulated B6 alleles in Chr2,7 and 12, and 129 alleles in Chr14. For saccharin selection, micefrom the High line accumulated B6 alleles in Chr1, 3 and 13, and129 alleles in Chr2 and 7. Mice from the Low lines accumulatedalleles from the opposite strain at these locations. This observationsuggests a complex genetic architecture of behavioral tasteresponses to sweeteners. There are two distinct sets of genesregulating glycine and saccharin consumption and each parentalstrain contributes loci increasing or decreasing a trait value.#P75 Poster session II: Chemosensory response to,and control of, feeding/NeuroethologyThe Benzamil (Bz)-insensitive NaCl Chorda Tympani (CT)Taste Nerve Responses Demonstrate Increased Sensitivity toTRPV1t Modulators in Alcohol-preferring (P) RatsVijay Lyall, Tam-Hao T. Phan, Shobha Mummalaneni, PamelaMelone, Jamison Coleman, John A. DeSimoneDepartment of Physiology and Biophysics, VirginiaCommonwealth University Richmond, VA, USAEthanol (ETH), nicotine (NIC) and resiniferatoxin (RTX),modulators of TRPV1t, induce biphasic effects on rat BzinsensitiveNaCl CT responses. At low concentrations theyenhance and at high concentrations inhibit the NaCl CT response.To investigate if chronic ethanol ingestion and genetic preferencefor ethanol are related to alterations in the Bz-insensitive NaClCT responses, we investigated the effect of ETH, NIC and RTXon the Bz-insensitive NaCl CT responses in alcohol-preferring(P) and alcohol nonpreferring (NP) rats. In naïve P rats ETH,NIC and RTX concentration versus the magnitude of the BzinsensitiveNaCl CT response curves were significantly higherand were shifted to the left on the agonist concentration axisrelative to NP rats. This suggests that alcohol preference increasesthe sensitivity of TRPV1t to stimulation by various agonists.P and NP rats were adapted to chronic oral ethanol ingestionusing the sucrose fading paradigm. When adapted to 5% ethanol,P rats consumed significantly more ethanol than NP rats givenfree access to ethanol alone or when given a choice betweenethanol and water. NP rats given oral 5% ethanol for 2 weeks theRTX concentration versus the Bz-insensitive NaCl CT doseresponse curve was higher and shifted to the left on theconcentration axis and was not different from the responseprofiles observed in naïve P rats or P rats given 5% ethanol.These results suggest that upon chronic ethanol consumption NPrats develop the phenotype of P rats related to TRPV1t activity.We conclude that TRPV1t activity is modulated by both ethanolconsumption and genetic preference for alcohol.#P76 Poster session II: Chemosensory response to,and control of, feeding/NeuroethologyCentral neural sensitivity to ethanol and other taste stimuliin selectively bred ethanol-preferring and ethanol-nonpreferringratsChristian H Lemon 1 , Susan M Brasser 21St. Louis University School of Medicine Saint Louis, MO, USA,2San Diego State University San Diego, CA, USAA strong positive relationship has been found in mammals forpreference and intake of ethanol and sweet-tasting substances.Ethanol is an ingested drug and its first direct interaction with thebody is orosensory. Data from randomly bred rats indicate thatorally-applied ethanol stimulates neural substrates for sweet taste,which are known to activate forebrain systems associated withreward. Yet it is unknown how ethanol’s appetitive sweet tasteproperties play into the array of variables that influence alcoholingestive reinforcement. Here, we made in vivoelectrophysiological recordings from central gustatory neurons inselectively bred ethanol-preferring (P) and ethanol-non-preferring(NP) rats (Lumeng et al. 1977) to determine if a relationship existsbetween genetically-mediated alcohol preference and the neuralprocessing of ethanol taste. Rats were anesthetized and taste50 | AChemS Abstracts 2009
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#P230 Poster session V: Chemosensor
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data here from mouse studies using
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in taste bud induction and developm
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trends in expression of GAP-43, OMP
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elationship between concentration a
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four (4 AFC) that they believe is m
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pleasantness (r=.275 p=.006), where
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utyl, hexyl, and octyl benzene). We
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taller compared to wild-type mice.
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animals over the age of P24 were gi
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classify subjects as PROP non-taste
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al 2008. Increases in glucose sensi
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#P315 Poster session VII: Chemosens
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differences in taste receptors is n
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IndexAbaffy, T - 48Abakah, R - P299
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Illig, K - 19, P109Imoto, T - P136I
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Rucker, J - P305Rudenga, K - P315Ru
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AChemS Abstracts 2009 | 135
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Registration7:30 am to 1:00 pm, 6:3
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Notes______________________________
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See you next yearat ournew venue!Tr
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2009 Abstracts - Association for Chemoreception Sciences

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