1 1 Symposium Chemosensory Receptors Satellite DEVELOPMENT ...

461 Poster Developmental, Neurogenesis, and ConsumerResearchFRESH POSTMORTEM HUMAN OLFACTORY BULBCULTURES TO STUDY NEUROGENESISMurrow B. 1 , Restrepo D. 2 1 Otolaryngology, University of ColoradoHealth Sciences Center, Denver, CO; 2 Cell and Developmental Biology,University of Colorado Health Sciences Center, Aurora, COWhile neurogenesis in the olfactory bulb of lower animals is wellaccepted, this process in humans is much more controversial. In orderto address this question in humans, olfactory bulbs from freshpostmortem cadavers were placed in primary tissue culture. Thedissociated cells produced differentiated cells of diverse morphologythat over time formed cellular networks. Fluorescent labeling suggestedsome of these cells to be of neuronal phenotype. Whole-cell voltageclamp revealed inward currents that appear to be sodium currents basedupon their kinetics and voltage dependency, as well as an array ofoutward currents. In isolated cases, an action potential-like event couldbe stimulated. To address the issue of neurogenesis, BrdU was added tothe cultures to label post-mitotic cells. Preliminary results revealed afew BrdU positive cells, suggesting that the human olfactory bulbintrinsically may possess a neurogenic process. Ongoing experimentsare altering the culture conditions to increase the number of post-mitoticcells and addressing the phenotypic makeup of the cells in culture.462 Poster Developmental, Neurogenesis, and ConsumerResearchGROWTH FACTORS AND RECEPTORS IN THE OLFACTORYEPITHELIUMBergman D.A. 1 , Sammeta N. 1 , McClintock T.S. 1 1 Basic Science:Physiology, University of Kentucky, Lexington, KYThe olfactory epithelium (OE) is a dynamic cellular environmentwhere cell death, proliferation, and neural differentiation arecontinuous. These dynamics are coordinated by signaling events, someof which are known (e.g., Wu et al. 2003, Neuron 37:197). Ourmicroarray data predicts expression of 47 growth factors and 30 growthfactor receptors in the OE. The data also predict whether they areexpressed in olfactory sensory neurons (OSNs) or in other cells in theOE. We have used in situ hybridization to test these predictions. OSNsexpress growth factor receptors Acvr1, Arvcf, Bmpr1a, Fzd3, Igf2r,Pdgfrb, Pdgfr1, and Tgfbr1, and growth factors Ecgf, Fgf9, Fgf12, andPdgfa. Basal cells expressed growth factor receptors Fzd3 and Tgfbr1,and growth factors Hdgf and Pdgfa. These data agree with evidence oflocal signaling in the OE by PDGF and TGF-b family signals. They alsopredict roles for Wnt, Ecgf, and Hdgf signaling in the OE, or in the caseof signals expressed by OSNs, the possibility of signaling to cellsoutside the OE such as olfactory ensheathing cells or cells in theolfactory bulb. Supported by R01 DC002736.463 Poster Developmental, Neurogenesis, and ConsumerResearchPURINERGIC RECEPTOR ACTIVATION EVOKESNEUROTROPHIC FACTOR NPY RELEASE FROM MOUSEOLFACTORY EPITHELIAL (OE) SLICESKanekar S. 1 , Hegg C. 1 1 Physiology, University of Utah, Salt Lake City,UTThe signals for injury-evoked neuroregeneration are unknown;however previous studies implied that injured cells secrete neurotrophicfactors which trigger neurogenesis. Extracellular purine nucleotidesexert multiple neurotrophic actions in the CNS mediated via activationof purinergic (P2) receptors. 1 Our previous work demonstrated that ATPacts as a neuromodulator and a stress signal in the OE. To determinewhether ATP and P2 receptor activation evokes neurotrophic factorsecretion in the OE, we monitored release of NPY, a neuroproliferativefactor known to be present and functional in the OE. 2 Neonatal mouseOE slices were cultured on nitrocellulose paper to visualize NPYrelease. Immunoassaying the nitrocellulose resulted in NPYimmunoreactivity in the region corresponding to the OE of the nasalseptum. We found that exogenous ATP (10-500 µM) significantlyincreased the percentage of OE slices that released NPY from 22% to46% (p < 0.05). P2 receptor antagonists PPADS (25 µM) and suramin(100 µM) reduced the number of OE slices exhibiting NPY releaseevoked by ATP by 53%, suggesting that activation of P2 receptorsmediates NPY release. Moreover, P2 receptor antagonists reduced thenumber of OE slices that released NPY under control conditions by40%, suggesting tonic release of endogenous ATP evokes NPY release.This study directly verifies that neurotrophic factor ATP evokesneurotrophic factor NPY release in the OE and providespharmacological targets to promote regeneration of damaged OE.Research supported by NIH NIDCD DC006897. (1) Neary et al. 1996.TINS 19:13-18. (2) Hansel et al. 2001. Nature 410:940-944.464 Poster Developmental, Neurogenesis, and ConsumerResearchSDF-1/CXCR4 SIGNALING REGULATES CELL MIGRATIONIN THE EMBRYONIC OLFACTORY SYSTEMSchwarting G. 1 , Henion T.R. 1 , Tobet S. 2 1 University of MassachusettsMedical School (Worcester), Waltham, MA; 2 Biomedical Sciences,Colorado State University, Fort Collins, COTwo cell types that are derived from the olfactory placodes undergoimportant migratory phases during early stages of embryonicdevelopment in mice: 1. The Migratory Mass (MM) is a heterogeneousmixture of cells that is mainly composed of glial precursors that willpopulate the nerve layer of the olfactory bulbs. At embryonic day 10(E10) in mice, the MM is visible as a single row of cells migratingthrough the nasal mesenchyme between the olfactory placodes and therostral telencephalon. 2. Gonadotropin releasing hormone (GnRH)containing neurons migrate from the vomeronasal organ (VNO) in thenasal compartment to the basal forebrain in mice beginning at E11.These neurons use vomeronasal axons as guides to migrate through thenasal mesenchyme. In situ hybridization studies reveal that the cytokinestromal derived factor 1 (SDF-1) is expressed in the nasal mesenchymeat E10 and continues throughout embryonic development. SDF-1 isexpressed in an increasing rostral to caudal gradient, which is mostintense at the border of the nasal mesenchyme and the developingtelencephalon. CXCR4, the receptor for SDF-1, is expressed by neuronsin the olfactory epithelium and VNO, and by cells dispersed alongmigratory pathways in the nasal mesenchyme. These dispersed cellscomprise two identifiable cell populations; migrating mass cells fromE10 to E12, and migrating GnRH neurons from E11 to at least E18.Based on these studies, we suggest that CXCR4+ MM cells and GnRHneurons are attracted toward the telencephalon by SDF-1 from theirorigins in the olfactory placodes. (Supported by NIH grant DC00953).116