1 1 Symposium Chemosensory Receptors Satellite DEVELOPMENT ...

417 Poster Central Taste and Chemosensory BehaviorRELATIONSHIPS BETWEEN INSULIN RELEASE AND TASTETonosaki K. 1 1 Meikai University, Sakatoshi, JapanIt is known that the food related sensory stimuli induces cephalicphase hormonal release. Thus, tasting sweet food elicits insulin releaseprior to increasing plasma glucose levels, it is called cephalic phaseinsulin release (CPIR). The characteristic of the CPIR is that the plasmainsulin secrets within 2 minutes after oral sensory stimulation, peak at 4minutes and return to baseline in the 8-10 minutes poststimulus timeperiod. The functional role of CPIR is not known clearly. In thisexperiment, we examined any tastes which was placed on the tongueinduced CPIR or not . We used female Wistar rats and five basic tastestimuli: sucrose (sweet), sodium chloride (salty), HCl (sour), quinine(bitter) or monosodium glutamate (umami). Rats reliably exhibit CPIRto sucrose. Sodium chloride, HCl, quinine or monosodium glutamatedoes not elicit CPIR. Sucrose has two typical characters such as `sweet`and `nutritive´. Then, we tested whether `sweet `or `nutritive´ elicitsCPIR. As the results, the non-nutritive sweetener saccharine does elicitCPIR. However, the non-sweetener nutrition starch does not elicitCPIR. In addition, we studied whether the CPIR related with the tastereceptor cell activity. We carried out the experiment that bilaterality cutoff the chorda tympani nerve which is one of the gustatory nerve. Thenthe CPIR could not be recognized for the sweet stimulation. From theseresults, it was proven that CPIR was elicited by the conducted tastenerve sweetness information. It is considered that these results mustinform the important comprehensible information for CPIR.418 Poster Central Taste and Chemosensory BehaviorTASTE FUNCTIONS AFTER GASTRIC BYPASS SURGERY INDIETARY AND GENETIC OBESE RATSHajnal A. 1 , Ahmed T.A. 2 , Khokhar S. 1 , Acharya N. 1 , Cooney R.N. 21 Neural and Behavioral Sciences, PennState Univ., College ofMedicine, Hershey, PA; 2 Surgery, PennState Univ. College of Medicine,Hershey, PAWeight loss after gastric bypass surgery (GBP) is caused byrestriction of food intake and malabsorption, but many patients alsonote decreased appetite for palatable meals. To investigate involvementof central taste mechanisms, we performed GBP in diet-induced obese(DIO) and CCK-1 receptor deficient Otsuka Long-Evans TokushimaFatty (OLETF) male rats. After GBP, both DIO and OLETF lost bodyweight similar to that seen in humans (25-30% weight loss) andexhibited improved glucose tolerance compared to both theirpreoperative baseline and pair-fed sham-operated controls. In addition,GBP rats of both strains showed a significantly reduced 24 hr 2-bottlepreference for sucrose (1.0 M) compared to sham-operated controls(preference ratio, DIO: 0.48 ± 0.04 vs. 0.90 ± 0.04, p < 0.001, n = 3/4;OLETF: 0.69 ± 0.02 vs. 0.89 ± 0.06; p < 0.05, n = 6/4). Lick rate (10-s)analysis revealed decreased responsiveness by DIO-GBP to sucroseconcentrations above 0.1M and by OLETF-GBP to sucrose 0.3Mthrough 1.5M and to fructose above 0.4 M (p < 0.05). No differencewas noted in either strain for the non-caloric sweetener saccharin,alanine, aversive taste solutions or trigeminal stimulation withcapsaicin. These findings suggest that (1) GBP may result in alteredtaste function with a reduced preference for palatable sugars in animalmodels of obesity, irrespective to the etiology of obesity, and (2) CCK-1 receptors do not contribute to the beneficial effects of GBP, such asweight reduction and improvement in insulin sensitivity. Supported byNIH grants DK065709, GM55639, and PSU-DFG.419 Poster Central Taste and Chemosensory BehaviorTEMPERATURE MODULATES BEHAVIORAL RESPONSESTO SUCROSE TASTE IN THE RATBreza J.M. 1 , Curtis K.S. 1 , Contreras R.J. 1 1 Program in Neuroscience,Florida State University, Tallahassee, FLWe recently showed that temperature modulates the responsivenessof gustatory neurons in the rat geniculate ganglion that respondprimarily to sucrose (sucrose-specialists). Specifically, responses to 0.5M sucrose at 10°C were less than those at 25°C or 40°C, which werenot different from each other. The goal of this study was to investigatewhether temperature modulates behavioral responses to sweet taste inrats. We employed very brief (10-s) trials in a Davis MS80 Riglickometer, modified with individual Peltier heat exchange deviceslocated near the tip of each drinking tube, that allows solutions to bemaintained at constant temperatures. We recorded the number oflicks/10 s to 0.2 M sucrose and to 0.05 M sucrose at 10, 25, and 40°C.Lick rates to 0.2 M sucrose were greater than those to 0.05 M sucrose atall temperatures. For a given concentration of sucrose, licking waslowest at 10°C, most robust at 25°C, and intermediate at 40°C. Lickingto 0.2 M sucrose at 10°C was 33% less at than that at 25°C, whereaslicking to 0.05 M sucrose at 10°C was 58% less than that at 25°C. Thefinding that lick rates to sucrose at 10°C decreased is consistent withour previous observation of reduced responses from sucrose-specialistneurons in the geniculate ganglion to sucrose at 10°C, and suggests thatcold temperature modulates sweet taste perception and thereby affectsbehavioral responses to sweet taste. Supported by NIH Grant DC04875420 Poster Central Taste and Chemosensory BehaviorEVALUATING THE LIMITS OF CANINE OLFACTIONSeward M.K. 1 , Latchney S.E. 1 , Hornung D.E. 1 1 St. LawrenceUniversity, Canton, NYTo assess the limits of a canine´s ability to identify a specific humanscent, a golden-retriever was trained to pick a T-shirt impregnated witha target human´s scent from T-shirts worn by the target´s relatives andnon-related persons. After sampling three test boxes (one of whichcontained the target), the dog was trained to exhibit a sit/stay responsewhen the target was identified. Correct responses were rewarded 90%of the time. The first series of experiments introduced olfactory “noise”to the testing environment by placing beakers containing increasingconcentrations of pure olfactory and olfactory/trigeminal odors betweenthe T-shirts and the sampling ports of the test boxes. The dog was ableto correctly identify the target even when the air concentrations of theseadded distracter odors were at their highest vapor concentrations. Asecond series of experiments reduced the concentration of the targetscent by covering the three beakers containing the T-shirts with platesthat decreased the exposed surface area, thus reducing the number ofmolecules present for detection. The dog was able to detect the targetscent when the surface area of the beaker was reduced by 93%.Combined, these two series of experiments illustrate the specificity andsensitivity with which a canine is able to detect a target human scentand discriminate between this scent and that of competingenvironmental odors. The first series of experiments provides somehints as to the chemical nature of this particular type of detection taskand the second series of experiments allows for an estimation of theminimum number of molecules necessary for detection.105