1 1 Symposium Chemosensory Receptors Satellite DEVELOPMENT ...

117 Poster Chemosensory Coding and ClinicalEARLY POSTNATAL ALCOHOL EXPOSURE REDUCED THESIZE OF THE NUCLEUS OF THE SOLITARY TRACT (NST) INNEONATAL RAT PUPSLi C.X. 1 , Maier S.E. 2 , Brasser S.M. 1 , Waters R.S. 1 1 Anatomy andNeurobiology, University of Tennessee Health Science Center,Memphis, TN; 2 NIAAA, NIH, Rockville, MDIntroduction: A strong association exists between alcohol ingestionand sucrose responsive neurons in rat NST (Lemon et al. 2004). Here,we examined the effect of postnatal alcohol exposure on the size ofNST in rat pups examined on postnatal day 10 (P10). Methods: Pupsobtained from untreated and normally conceived Sprague-Dawley damswere randomly assigned to alcohol (EtOH), pair-fed (PF), and untreated(UC) groups. EtOH pups received 6 g/kg dosage of alcohol while PFpups received isocaloric maltose-dextrin solution from P4–P9. EtOHand PF pups were treated daily (binge model) through a gastrostomytube implanted for artificial rearing. On P10, pups were sacrificed,brains removed and weighed, brainstem blocked, cut along a sagittalplane, and sections stained with cytochrome oxidase. The NST wasdigitized, reconstructed in Photoshop 7.0, and NST size measured usingImageJ. Body weight was also examined over postnatal days. Results:The total area of NST in EtOH pups (mean area = 0.32 mm 2 ) wassignificantly smaller (p < 0.5) compared to PF (mean area = 0.39 mm 2 )controls. Normalization of the data (EtOH vs PF) revealed a 16%reduction of total NST in EtOH pups. Similarly, normalized body andbrain weights of EtOH pups were 12% and 25% lower compared to PFpups, respectively. Conclusion: The present results suggest that earlyalcohol exposure results in detrimental effects on developing NST.(Supported by NIAAA, R01 AA013437 to R.S.W., and AA10090 to J.West)118 Poster Chemosensory Coding and ClinicalLACTISOLE GREATLY DECREASES DIFFERENTIALTHRESHOLDS FOR SUCROSE: A CASE FOR INCREASEDCOOPERATIVITYGalindo-Cuspinera V. 1 , Tharp A.A. 1 , Winnig M. 2 , Bufe B. 2 , MeyerhofW. 2 , Breslin P.A. 1 1 Monell Chemical Senses Center, Philadelphia, PA;2 German Institute of Human Nutrition Potsdam-Rehbruecke, Nuthetal,GermanyWe have previously demonstrated that adaptation to a taste stimulusresults in increased sensitivity, despite decreasing the overall perceivedintensity. Here, we demonstrate that the addition of a taste inhibitor canalso lead to increased differential sensitivity. Lactisole, a broad-actingsweetness inhibitor, suppresses the sweet taste of sugars, proteinsweeteners, and artificial sweeteners. Lactisole's inhibitory effect isspecific to primates and does not affect responses to sweet compoundsin rodents. Here we show by using two different psychophysicalmethods, Weber fractions and psychometric functions, that lactisoleadded in small amounts greatly increases differential sensitivity tosucrose, reducing Weber fractions to as low as 0.25%. Some subjectswere able to distinguish 400 from 401 mM sucrose. We observed thatlactisole acts as an inverse agonist by studying, in vitro, its interactionwithin the intrinsically active hTAS1R2-hTAS1R3 sweetener receptorheteromer. The presence of an inverse agonist, lactisole, could enablean increased cooperativity of sucrose molecules when binding to thehTAS1R2-hTAS1R3 receptor, which would explain the greatlyincreased differential sensitivity to sucrose observed in the presence oflactisole. Suported by PASB NIH DC02995 and NIHP50DC0670119 Poster Chemosensory Coding and ClinicalEFFECTS OF PREGNANCY ON OLFACTIONCameron E.L. 1 1 Carthage College, Kenosha, WIReports of changes in olfactory sensitivity during pregnancy havebeen inconsistent, but hedonic ratings do appear to change. Odoridentification is unaffected by pregnancy, but the range of odors testedhas been limited. The current study tested 30-18- to 45-year-old nonsmokingwomen (15 pregnant, equally divided across trimester, and 15age-matched controls) on the 40-item UPSIT. Intensity ratings andnumber of scratches and sniffs were collected as indicators ofsensitivity, and participants rated the pleasantness of each odor.Participants also rated their own sense of smell. Mean UPSIT scoreswere 35.4 (pregnant) and 35.5 (controls), indicating no difference inodor identification for a large range of odors. Pregnant women ratedtheir sense of smell significantly higher than controls (Wilcoxon test),and trends suggest that they used fewer scratches and sniffs per odor,potentially confirming their self-reports. Between groups, meanintensity and pleasantness ratings approached significance; 87% ofodors were rated as slightly more intense and 67% as less pleasant bypregnant women. Consistent with previous reports, over 90% ofpregnant women reported that specific odors smell less pleasant (e.g.,meat and smoke) and about 75% reported that some odors smell morepleasant (e.g., fruit). In conclusion, pregnant women report that theirodor sensitivity is enhanced during pregnancy and appear to need toscratch and sniff less often in order to identify odors on the UPSIT.Moreover, pregnant women show enhanced intensity and hedonicratings. Odor identification, however, is unchanged. These data are partof an on-going study that will examine trimesters and postpartumphases separately.120 Poster Chemosensory Coding and ClinicalNICOTINE SUPPRESSION OF TASTE AND GUSTATORYRESPONSES OF NTS NEURONSSimons C.T. 1 , Boucher Y. 2 , Albin K. 3 , Iodi Carstens M. 3 , Carstens E. 31 Givaudan Flavors Global R&D, University of California, Davis,Cincinnati, OH; 2 Université Paris 7, Paris, France; 3 Neurobiology,Physiology and Behavior, University of California, Davis, Davis, CASmokers weigh less than nonsmokers and gain weightdisproportionately upon quitting. We investigated the hypothesis thatthe anorectic effect of nicotine in tobacco is mediated partly by areduction in the intensity of and preference for certain tastes viadepression of central gustatory transmission. In psychophysicalexperiments using a sensitive two-alternative forced choice methodcoupled with magnitude ratings of taste on each side of the tongue,nicotine reduced the perceived intensity of sweet and bitter tastequalities and reduced hedonic ratings of a naturally sweetened custard.The effect was transient and no longer present 5 min later after nicotineirritation had waned. In single-unit recordings from anesthetized rats,nicotine directly excited gustatory neurons in the nucleus of the solitarytract (NTS) and significantly attenuated their responses to the preferredtastant (sucrose, NaCl, citric acid or MSG) in a dose-dependent manner.Nicotinic excitation of NTS units, and depression of tastant-evokedresponses, were significantly attenuated by the nicotinic antagonistmecamylamine. Nicotine excited NTS units in rats in which trigeminalafferent input was blocked by ganglionectomy, but no longer depressedtastant-evoked responses, indicating that nicotine excites NTS unitsdirectly via taste nerves and inhibits their tastant-evoked responses by acentral trigeminally-mediated mechanism. The results are consistentwith the hypothesis that nicotine reduces food intake in part by aphysiologically mediated reduction in taste intensity and palatability.30