1 1 Symposium Chemosensory Receptors Satellite DEVELOPMENT ...

265 Poster Central Olfaction and Chemical EcologySEXUALLY DIFFERENTIATED EXPRESSION OF BDNF ANDTRKB ASSOCIATED WITH THE P2 GLOMERULI OF MOUSEMAIN OLFACTORY BULBOliva A.M. 1 , Vivekanandan V. 1 , Jones K. 2 , Restrepo D. 1 1 NeuroscienceProgram, University of Colorado Health Sciences Center, Aurora, CO;2 University of Colorado at Boulder, Boulder, CODifferential behavioral responses of female and male rodents tovarious chemosensory signals have been described abundantly in theliterature, yet the neural basis mediating those responses is largelyunknown. We are testing the hypothesis that sexually dimorphicglomeruli may contribute to sex-differentiated behaviors. The aim ofthis study was to determine whether expression of BDNF and itsreceptor, TrkB, have sexually differentiated expression associated withP2 glomeruli previously described as sexually dimorphic. Toaccomplish this, we bred P2-IRES-tauGFP mice to BDNF-LacZ mice.The former strain expresses GFP in all olfactory sensory neurons thatexpress the P2 odorant receptor while in the latter strain LacZ replacesone BDNF allele. We show a correlation between the sex differences inthe volume of P2 glomeruli and the number of β-galactosidase (β-gal)-immunoreactive (IR) periglomerular (PG) cells surrounding the P2glomeruli. Specifically, the number of β-gal-IR PG cells surroundingthe lateral P2 glomeruli was higher in females compared to males.Consistent with this finding, we show that the intensity of TrkB stainingwithin the lateral P2 glomeruli is higher in females compared to males.These results show that BDNF and TrkB expression associated with theP2 glomeruli is sexually differentiated and suggests that BDNF/TrkBmay mediate the sex differences in the volume of the lateral P2glomeruli. Supported by grants from the NIDCD (DC00566 andDC004657) to D.R.266 Poster Central Olfaction and Chemical EcologyTHE SENSE OF SMELL: MULTIPLE OLFACTORYSUBSYSTEMSBreer H. 1 , Fleischer J. 1 , Schwarzenbacher K. 1 , Strotmann J. 1 1 Instituteof Physiology, University of Hohenheim, Stuttgart, GermanyThe mammalian olfactory system is not uniformly organized butconsists of several subsystems each of which probably serves distinctfunctions. Not only are the two major nasal chemosensory systems, thevomeronasal organ and the main olfactory epithelium structurally andfunctionally separate entities, but the latter is furthersubcompartimentalized into overlapping expression zones andprojection-related subzones. Moreover, the populations of OR37neurons not only express a unique type of olfactory receptors, but alsoare segregated in a cluster-like manner and generally project to only oneglomerulus. The septal organ (SO) is an additional island of sensoryepithelium on the nasal septum. SO neurons express a limited repertoireof odorant receptors, including a few which are found in a very highproportion of neurons. One set of SO axons enters glomeruli which aremainly targeted by axons of neurons located in the main olfactoryepithelium. Another fraction targets SO-specific glomeruli. Due to itsexposed position in the airstream and close to the nasopalatine ductwhich connects the mouth to the nasal cavity it is considered a “mininose”with dual function. A specific chemosensory function of the mostrecently discovered subsystem, the so-called Grueneberg ganglion, isbased on the expression of olfactory marker protein and the axonalprojections to defined glomeruli within the olfactory bulb. Thiscomplexity of distinct olfactory subsystems may be one of the featuresdetermining the enormous chemosensory capacity of the sense of smell.This work was supported by the Deutsche Forschungsgemeinschaft267 Poster Central Olfaction and Chemical EcologySPATIALLY DISTINCT SENSORY INPUT TO MEDIALOLFACTORY BULB GLOMERULI AND OUTPUTPROJECTIONS INTO THE HABENULA AND VENTRALTHALAMUS IN THE SEA LAMPREY PETROMYZON MARINUSRen X. 1 , Chang S. 1 , Auclair F. 2 , Dubuc R. 2 , Zielinski B. 1 1 BiologicalSciences, University of Windsor, Windsor, Ontario, Canada;2 Département de Kinanthropologie, Université du Quebec à Montréal,Montréal, Quebec, CanadaIn this study of the olfactory system of the sea lamprey, weinvestigated the spatial origin of olfactory sensory neurons extendinginto medial olfactory bulb glomeruli, and the projection pathways ofsecond order olfactory bulb neurons. Our previous studies have shownthat the medial glomerular territories are biochemically distinct fromothers in the olfactory bulb. Here, we use double labeling with DiI andDiA to show unique peripheral input to medial glomeruli. Peripheralcells in the accessory olfactory organ, a long ignored tiny structure thatis ventro-caudal to the peripheral olfactory organ, as well as olfactorysensory neurons (OSNs) in the olfactory epithelium extended fibers intomedial glomeruli. Dye injection into lateral glomeruli filled OSNs in theolfactory epithelium, but failed to label cells in the accessory olfactoryorgan. Neuronal fibers labeled by microinjection of biotinlyated dextraninto medial glomerular territories extended through the habenula,ventral thalamus and hypothalamus. Fibers decussating through thedorsal commissure to the contralateral olfactory bulb were alsoobserved. These data suggest the presence of a spatially distinctolfactory sub-system in this ancestral vertebrate.268 Poster Central Olfaction and Chemical EcologyFUNCTIONAL AND SPATIAL IDENTITY OF MOUSEOLFACTORY GLOMERULI INNERVATED BY DEFINEDPOPULATION OF OLFACTORY RECEPTOR NEURONSOka Y. 1 , Katada S. 1 , Omura M. 1 , Suwa M. 2 , Yoshihara Y. 3 , Touhara K. 11 Integrated Biosciences, University of Tokyo, Kashiwa, Chiba, Japan;2 CBRC, National Institute of Advanced Industrial Science andTechnology, Tokyo, Japan; 3 RIKEN Brain Scinece Institute, Saitama,JapanDespite recent progresses in deorphanizing olfactory receptors (ORs),gene-targeting or transgenic approach has been required to characterizeodorant-responsiveness of a glomerulus innervated by definedpopulation of olfactory neurons in the olfactory bulb (OB). In thisstudy, we generated transgenic mice to visualize olfactory neuronsexpressing a eugenol receptor, mOR-EG (MOR174-9). Using thesemice, we established an in vivo OR identification technique based onglomerulus activity. Several ORs sharing high sequence homology wereidentified from eugenol-responsive glomeruli. Further, singleglomerulus RT-PCR and reconstitution of identified ORs in HEK293cells recapitulated our results. Spatial characterization of OR-definedglomeruli in the OB across animals revealed that positional relationshipof these glomeruli considerably varied between individuals. We alsocompared odorant-response properties of OR-defined glomeruli withthose obtained in HEK293 cells, demonstrating that odorantresponsiveness of each glomerulus was not exactly reflected by ORpharmacology observed in heterologous expression system. Ourfindings point out caveat that odor identity in the OB should bediscussed at the OR level, rather than at the level of activity pattern.Supported by PROBRAIN Japan.67