1 1 Symposium Chemosensory Receptors Satellite DEVELOPMENT ...

485 Poster Developmental, Neurogenesis, and ConsumerResearchETHANOL IN VIVO CAUSES DEGENERATION OFOLFACTORY SENSORY NEURONSUkhanova M. 1 , Kim H.H. 1 , Margolis J.W. 1 , Margolis F.L. 1 1 Anatomyand Neurobiology, University of Maryland at Baltimore, Baltimore, MDAlcoholism is a major medical problem resulting in damage to manyorgan systems. Neuronal degeneration in the CNS is reported fromhuman and animal studies particularly in limbic system areas. Deficitsin olfactory function in alcoholics are reported to be reversed onabstinence. We hypothesized that these deficits result from thedegeneration and death of mature olfactory sensory neurons (OSNs)after EtOH administration and that upon abstinence OSNs arereconstituted from mitotically active progenitors in OE. Nevertheless,the effect of ethanol on this neuronal population is uncharacterized.Therefore, we are studying the effect of EtOH on mouse olfactoryneuroepithelium. Administration of EtOH by i.p. injection results inreduced OMP expression in olfactory neuroepithelium (OE) andolfactory bulb (OB), and significant loss of mature neurons in the OE asmeasured by molecular and immunohistochemical techniques. Afterseveral weeks of abstinence the OMP levels and tissue morphologyreturn to control values. We also monitored gene expression in nonneuronalcells in OE and have shown the elevation of EtOH-inducibleP450 (CYP2E1) and carnosinase after EtOH administration. These datademonstrate that multiple cell types, in addition to OSNs, in OE areinfluenced by in vivo EtOH treatment. Supported by Grant NIH DC-00547, DC-003112 and NIH CINTPG T32 NS07375.486 Poster Developmental, Neurogenesis, and ConsumerResearchNG2-EXPRESSING CELLS: A 4TH CLASS OF MACROGLIA INTHE MOUSE OLFACTORY BULBTreloar H.B. 1 , Morton M. 1 , Whitman M. 1 , Greer C.A. 2 1 Neurosurgery,Yale University, New Haven, CT; 2 Neurobiology, Yale University, NewHaven, CTThe NG2 chondroitin sulfate proteoglycan (CSPG) is a large integralmembrane proteoglycan comprising a ~300 kDa core protein and atleast one chondroitin sulfate glycosaminoglycan (GAG) side chain. Inthe CNS, two distinct populations of NG2-positive cells have beendescribed: (1) a population of oligodendroglial precursors and (2) apopulation of mature neuroglial cells termed synantocytes that aredistinct from astrocytes, oligodendrocytes and microglia. We examinedNG2 expression in both developing and mature murine olfactory bulb(OB). NG2 was expressed by a population of stellate cells in theglomerular, external plexiform and granule cell layers of the OB. Thesestellate cells did not express the astrocytic marker GFAP or theoligodendrocyte marker RIP. Ultrastructurally, they displayed all themorphological charateriststic of synantocytes: an irregularly shapedpale nucleus; with a thin rim of heterochromatin beneath the nuclearenvelope; and few organelles in the cytoplasm. They also receivedsynapses, but did not express the neuronal markers NeuN, Dcx or MAP-2, thus appear to be glia rather than neurons. Moreover we demonstratethat these glia are proliferative. We describe for the first time that NG2+glia comprise a significant population of glia within the adult mouseOB, and are the predominant glial population within the EPL.487 Poster Developmental, Neurogenesis, and ConsumerResearchHETEROGENEOUS GENERATION OF PERIGLOMERULARCELLS IN THE ADULT MOUSEWhitman M.C. 1 , Greer C.A. 1 1 Depts of Neurobiology andNeurosurgery, Yale University, New Haven, CTThe olfactory system of adult mammals has a continual influx of newneurons. Stem cells in the subventricular zone (SVZ) lining the lateralventricles give rise to neuroblasts that migrate into the olfactory bulb(OB), via the Rostral Migratory Stream (RMS). In the OB, theydifferentiate into the two main populations of interneurons, granule cellsand periglomerular (PG) cells. The PG cells, because they represent asmall proportion of the new cells, have received relatively littleattention. PG cells can be divided into several subtypes, based onexpression of neurotransmitters and calcium-binding proteins. It is notknown if all the subtypes continue to be generated in adulthood, or ifthe adult-generated neurons comprise only one or a few subtypes of PGcell. We have examined this question in mouse by using BrdUincorporation as a marker of new cells. Animals are given BrdU,followed by a 30 day survival period to allow for migration anddifferentiation. Tissue is then double labeled for BrdU and calciumbinding proteins, such as calbindin, calretinin, and parvalbumin, ormarkers of neurotransmitter phenotype, such as tyrosine hydroxylase(TH) and glutamic acid decarboxylase (GAD). For each subtype of PGcell, we have found some labeled with BrdU, but when the proportionof total cells expressing each marker is compared to the proportion ofBrdU labeled cells expressing each marker, there are markeddifferences among the subtypes. Our data indicate that the generationand perhaps replacement of PG cells is not uniform and may reflectdifferent functional roles for PG cells or their integration intoglomerular circuits. Supported in part by NIH DC006972, DC00210,DC006291 to CAG and the Yale MSTP GM07205 to MCW.488 Poster Developmental, Neurogenesis, and ConsumerResearchTARSH GENE EXPRESSION IN THE DEVELOPING MITRALCELLCheng T. 1 , Gong Q. 1 1 Cell Biology and Human Anatomy, University ofCalifornia, Davis, Davis, CAMitral cell is the first relay in the olfactory system. Duringdevelopment, mitral cells first extend elaborated dendritic processes atembryonic stages and then undergo dendritic pruning at early postnatalstages to acquire the single primary dendrite morphology. Genomewidescreen was performed using oligonucleotide microarray tocompare the transcriptional differences between P6 and E16 mouseolfactory bulbs (OB). TARSH was identified as one of the upregulatedgenes in P6 OB. TARSH mRNA is first detected in E18 mouse brainand exclusively expressed in the mitral/tufted cells by in situhybridization. At early postnatal stages, TARSH is expressed in themitral/tufted cells in the main OB and also the anterior olfactorynucleus (AON). At P35, TARSH expression can not be detected in theOBs but the AON expression remains. Quantitative RT-PCR indicatesTARSH transcription level reaches the peak at P6 and is downregulatedafter P6. The changes of TARSH transcription level in the OBare correlated with the mitral cell pruning event. A previous study found5 alternative splicing forms of TARSH mRNA (Uekawa et al., 2005).We have identified 6 alternative splicing forms in the P6 OB and 4 ofthem are new alternative splicing variances in the SH3-binding motifregion. This suggests that TARSH may have different binding affinitieswith its interacting molecules. Full length cDNA of TARSH was clonedfrom the mouse OB. The over-expression and knockdown effects ofTARSH in mitral cell morphogenesis are currently under investigation.Supported by: NIH DC006015, NSF0324769.122