2009 Abstracts - Association for Chemoreception Sciences

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#P230 Poster session V: Chemosensory memory/Central synaptic physiology/NeurogenesisProperties of rostral nucleus of the solitary tract (rNST)GABAergic interneuronsMin Wang 1 , Robert M. Bradley 1,21Department of Biologic and Material Sciences, School ofDentistry, University of Michigan Ann Arbor, MI, USA,2Department of Molecular and Integrative Physiology,MedicalSchool,University of Michigan Ann Arbor, MI, USAInhibition has been shown to play a significant role in rNSTsensory processing mediated by GABAergic interneurons.However, the properties of these inhibitory interneurons have notbeen systematically investigated. We have used transgenic mice inwhich enhanced green fluorescent protein (EGFP) expression islinked to glutamic acid decarboxylase expression (GAD + ) toidentify and characterize the rNST GABAergic interneurons. Incoronal brainstem sections GABAergic interneurons werelocalized to the ventral subdivision of rNST. The GAD-EGFPneurons also immunoreact with GABA and NeuN antibodies anddifferent subpopulations of these neurons also immunostain withsomastatin and parvalbumin. In whole cell brain slice recordingsGAD-EGFP neurons could be grouped based on their firing andmorphologic properties. In response to a depolarizing currentpulse 71% of the GAD-EGFP neurons responded with a shortinitial burst of action potentials, 13% responded with a stutterfiring pattern and 16% responded with a tonic firing pattern.The burst firing neurons had a small round soma area. Stutterfiring neurons had larger soma areas and round cell bodies andtonic firing neurons had large fusiform or multipolar somas.In conclusion, the rNST GAD-EGFP interneurons differ inpeptide expression and have heterogeneous physiological andmorphological properties. These differences may indicate thatthese inhibitory interneurons may have different roles in rNSTsensory processing of information derived from taste receptorsin the oral cavity.#P231 Poster session V: Chemosensory memory/Central synaptic physiology/NeurogenesisSox2 Regulation of Neurogenesis in the Adult OlfactoryEpitheliumAdam I Packard, James E SchwobTufts University School of Medicine Boston, MA, USASox2 is expressed in multiple cell types in the adult olfactoryepithelium (OE), including horizontal basal cells, globose basalcells and sustentacular cells. During lesion-induced regenerationof the OE, residual activated stem and progenitor cells expressSox2 robustly. The absence of Sox2 from neurons suggests that itmay function to suppress neuronal differentiation in both thenormal and regenerative settings. To test this we used areplication-incompetent retrovirus to drive expression of Sox2-IRES-eGFP in the regenerating mouse OE. The composition ofthe clones derived from the infected progenitors was characterizedusing cell type-specific antibodies. Sox2-infected clones have agreater number of cells on average compared with the controlvector (eGFP-only). Surprisingly, Sox2-infected clones didcontain numerous neurons as shown by co-expression of GFPwith Tuj1 and/or PGP9.5. Thus, Sox2 seems to be incapable ofblocking the differentiation of olfactory neurons on its own.However, immunoreactive Sox2 cannot be detected in aconsiderable percentage of GFP-labeled neurons, despiteenhanced levels of Sox2 expression by infected sustentacular andbasal cells. Moreover, those neurons in which Sox2 expression isdetectible by immunostaining were more lightly labeled thanother infected cells. This constellation of findings suggests thatSox2 is being degraded in neurons infected with the Sox2 vector.Of note, no clone-derived, Sox2-expressing neurons co-expressPax6, a known binding partner, indicating that Sox2 may need aco-factor to suppress neuronal differentiation in the OE. Insummary, selective over-expression of Sox2 is not able to suppressolfactory neuronal differentiation by itself, which may reflect aneed to partner with Pax6, as in other tissues, to accomplish anyinhibition.#P232 Poster session V: Chemosensory memory/Central synaptic physiology/NeurogenesisPACAP Enhances Cell Survival in Cultured Slices ofMouse Olfactory BulbMary T Lucero, Shami KanekarUniversity of Utah, Department of Physiology, NeuroscienceProgram Salt Lake City, UT, USAOur lab has previously demonstrated the importance of theneuropeptide PACAP in protection of neurons of the olfactoryepithelium against both axotomy-induced and cytokine-inducedapoptosis. Expression of PACAP and its receptor PAC1 iswidespread in the olfactory bulb (OB). In this study, we thereforeexamined whether PACAP enhances cell survival in the OB.We cut 300 micron thick live slices of the OB on a vibratome.Slices were immediately transferred into tissue culture media(DMEM/F12, 0.5% BSA) containing PACAP at 4 nM or 40 nM,or vehicle alone. Slices were cultured in a tissue culture incubatorat 37 o C for 21 hours, and then treated with 0.5% propidiumiodide to label dying cells. Slices were then fixed and all cellslabeled with sytox-green. Slices were imaged on a Zeiss LSM500confocal microscope, PI-labeled cells and total cells were counted,and the percent of dying /total cells calculated. After 21 hrs inculture, the percentage of dying cells in the 4 nM PACAP groupwas similar to control: 90 ± 4% that of control. The 40 nMPACAP group however showed significantly lower percentagesof dying cells than both control and 4 nM PACAP (One WayANOVA, p
#P233 Poster session V: Chemosensory memory/Central synaptic physiology/NeurogenesisCytoarchitecture of Neuroblasts and their Stem Cell NicheMaintaining Adult Neurogenesis in the Olfactory Midbrainof Spiny Lobsters, Panulirus argusManfred Schmidt, Charles D. DerbyNeuroscience Institute, Georgia State University Atlanta,GA, USAAdult neurogenesis persists in the olfactory midbrain of spinylobsters, Panulirus argus. Neuronal precursor cells are located in asmall proliferation zone (PZ) in each of the four soma clusters oflocal and projection neurons. One neuronal stem cell – a largeadult neuroblast (aNB) - is located close to each PZ and is itselfassociated with a unique clump of cells constituting a putativestem cell niche (Schmidt, J. Comp. Neurol. 503:64-84, 2007). Weanalyzed the cytoarchitecture of the aNB and the clump of cellswith immunocytochemistry and TEM. These analyses showedthat the clump is comprised of cells (clump cells) whose smallsomata form a dense mantle around a nucleus-free core and thatthe aNB has a unique hourglass-like shape. The peripheral part ofthe aNB contains a large nucleus and is connected via a thincytoplasmic bridge to a bulb-shaped ‘foot’ extending into core ofthe clump of cells. The clump cells are bipolar with a longoutward-facing process and a shorter process reaching into thecore of the clump. The outward-facing processes form a strandthat surrounds the peripheral part of the aNB and projects furtherto the PZ. The shorter processes are convoluted and completelycover the bulbous foot of the aNB. Processes of multipolar, somaassociatedglial cells envelope clump and strand in several layersand separate them from neighboring neuronal somata andarterioles. We conclude that the clump of cells has morphologicalfeatures of a protected stem cell niche, in which clump cellsconstitute the microenvironment of the aNB and insulate it fromthe surrounding tissue. Since the clump cells differ from glial cellsin immunocytochemical properties and in overt morphology, wehypothesize that they maintain embryonic characters, a commonfeature of stem cell niches in adult tissues.to be effective in wildtype and transgenic mice as well as rats.Given its versatility, robustness, and both time and costeffectiveness, this method offers a powerful new way to usegenetic manipulation to understand adult neurogenesis.#P235 Poster session V: Chemosensory memory/Central synaptic physiology/NeurogenesisDeafferentation affects cell genesis and neuron survivalin the olfactory bulb of adult zebrafishChristine A. Byrd-Jacobs, Ruth VillanuevaWestern Michigan University Kalamazoo, MI, USAThe potential effects of afferent innervation on adult neurogenesisin the olfactory bulb were examined with deafferentation.Olfactory organs of adult zebrafish were completely ablated bycautery to cause permanent denervation of the olfactory bulb.Animals were exposed to bromodeoxyuridine then examinedusing immunocytochemistry following short (4 hour) or long(3 week) survival periods. Short survival times allowed analysisof cell proliferation in the bulb and long survival times permittedinvestigation of survival of adult-formed cells. When examinedimmediately after deafferentation, no effect on cell proliferationwas observed. However, there was an effect on the number ofadult-formed cells present in the bulb three weeks later suggestingthat afferent removal influenced the fate of newly formed cells byimpacting subsequent divisions, maturation, or survival of thosecells. One week of deafferentation altered the pattern of cellgenesis, with a significant increase in the number of dividing cellslocated in the olfactory bulb. Survival also was impacted by oneweek of deafferentation since there was an elevation in thenumber of adult-formed cells in the glomerular layer of the bulb.Sham surgery and longer deafferentation times did not impacteither proliferation or survival of adult-formed cells. Thus,afferent innervation is necessary for normal cell proliferation andmaintenance of the olfactory bulb in adult zebrafish. Themechanisms by which olfactory axons exert an influence on theprocess of adult neurogenesis will be the subject of future studies.#P234 Poster session V: Chemosensory memory/Central synaptic physiology/NeurogenesisEctopic gene expression by postnatal electroporationduring olfactory interneurons neurogenesisDongjing Zou 1 , Alex Chesler 1 , Claire Le Pichon 1 , Jesse Brann 1 ,Ricardo Araneda 2 , Stuart Firestein 11Department of Biological Sciences, Columbia University NewYork, NY, USA, 2 Department of Biology, University of MarylandCollege Park, MD, USANeurogenesis persists in the olfactory system throughout life.The mechanisms of how new neurons are generated, how theyintegrate into circuits, and their role in coding remain mysteries.Here we report a technique that will greatly facilitate research intothese questions. We found that electroporation can be used torobustly and selectively label progenitors in the SubventicularZone. The approach was performed postnatally, without surgery,and with near 100% success rates. Labeling was found in allclasses of interneurons in the olfactory bulb, persisted toadulthood and had no adverse effects. The broad utility ofelectroporation was demonstrated by encoding a calcium sensorand markers of intracellular organelles. The approach was found#P236 Poster session V: Chemosensory memory/Central synaptic physiology/NeurogenesisCell specific deletion of BDNF leads to impairments inmurine adult olfactory neurogenesisKevin G Bath, Christine Neeb, Deqiang Jing, Francis S LeeWeill Medical College of Cornell New York, NY, USANeurotrophins are a class of molecules known to influence thedevelopment and survival of cells of the nervous system. BDNFsignaling through TrkB receptors is important for postnatalmodifications of the nervous system such as synaptic remodeling,dendritic outgrowth, and cell survival. In adult animals, theapplication or overexpression of exogenous BDNF has beenshown to impact neurogenesis. We have recently shown, throughthe use of several genetically engineered lines of mice and novelreagents that endogenously produced BDNF plays a significantrole in regulating adult olfactory bulb (OB) neurogenesis.Furthermore, we have shown that adult OB neurogenesis reliesheavily upon the regulated release of BDNF and signalingthrough TrkB and not p75 receptors. However, the source of theendogenously released BDNF has remained elusive. We present100 | AChemS Abstracts 2009
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AChemSAssociation for Chemoreceptio
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#4 GustationGPR40 knockout mice hav
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small population of cells respondin
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higher order areas. The beta oscill
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conclusions limited, however, by th
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expressed in the taste cells may al
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glomerulus varies across individual
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TH/GFP expression levels in depolar
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not activation and sensitivity. Fur
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POSTER PRESENTATIONS#P1 Poster sess
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and gender (all male). Our results
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activation in psychiatric disorders
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the e4 allele. The ApoE e4 allele i
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including the olfactory epithelium,
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and posterior (MeP), which are diff
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75 and 39 of 80 PbN cells were acti
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on the left side and from 60.9 ± 1
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#P52 Poster session II: Chemosensor
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Page 130 and 131: IndexAbaffy, T - 48Abakah, R - P299
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Page 134 and 135: Rucker, J - P305Rudenga, K - P315Ru
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Page 138 and 139: Registration7:30 am to 1:00 pm, 6:3
Page 140 and 141: Notes______________________________
Page 142 and 143: See you next yearat ournew venue!Tr
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2009 Abstracts - Association for Chemoreception Sciences

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