Givaudan-Roure Lecture - Association for Chemoreception Sciences

384 Poster [ ] Cell Biology of the Olfactory Epithelium
LOCALIZATION OF RETINOIC ACID RECEPTORS IN
MOUSE AND HUMAN NASAL EPITHELIUM
Yee K.K. 1, Hahn C. 2, Rawson N.E. 1 1Monell Chemical Senses Center,
Philadelphia, PA; 2Dept. Psychiatry, University of Pennsylvania,
Philadelphia, PA
All-trans retinoic acid (ATRA), a metabolite of vitamin A, binds to
retinoic acid receptors (RARs) to mediate gene-transcription in target
cells. We previously found that an ATRA supplement enhanced
olfactory recovery rate in adult mice after olfactory bulb (OB)
deafferentation. In this study, we examined the localization of
RAR&alpha, RAR&beta, and RAR&gamma after injury and ATRA
treatment using immunocytochemistry. Mice received a left olfactory
nerve transection (LNX) with the right side serving as control. One day
after LNX, the mice were given either ATRA mixed with sesame oil or
just sesame oil. In the control OB, RAR&alpha immunoreactivity (ir)
was observed in periglomerular and granule cells, while we did not
detect immunostaining for RAR&beta or RAR&gamma. In the oiltreated
right olfactory epithelium (OE), RAR&alpha -ir was found in
NST- and SUS4-negative microvillar-like cells located in the
supporting cell layer, in cells in the lamina propria, and in some
respiratory cells. RAR&beta -ir was localized only in the respiratory
cells while no RAR&gamma -ir was observed in the OE. Surprisingly,
the density of RAR&alpha -ir microvillar-like cells was higher in the
transected OE and highest in transected OE with ATRA treatment,
suggesting these cells are non-neural. We also examined RARs-ir in
human nasal tissue and found a similar cellular localization. These
findings suggest that microvillar cells, a population about which
comparatively little is known, are targets for ATRA modulation of gene
expression in the OE and may play a role in OE recovery following
injury. Supported by NIH DC04645 and DC00214.
385 Poster [ ] Cell Biology of the Olfactory Epithelium
IMMUNOLOCALIZATION OF BEX PROTEINS IN THE
MOUSE BRAIN: COLOCALIZATION WITH OMP
Koo J. 1, Manda S. 1, Margolis F.L. 1 1Medicine, University of Maryland
at Baltimore, Baltimore, MD
Bex proteins are a family of “Brain expressed X-linked genes” that
are closely linked on the X-chromosome. Bex1 and 2 have been
characterized as interacting partners of OMP. Here we report the
development and characterization of an antibody to mouse Bex1 protein
that also cross-reacts with Bex2 (but not Bex3) and its use to determine
the first comprehensive distribution of Bex proteins in the murine brain.
Immuno-blots and immunocytochemical analyses of cells transfected
with either Bex1 or Bex2 have shown that the antiserum reacts with
both Bex1 and Bex2. Antibodies preabsorbed with recombinant Bex2
still recognize Bex1 while blocking with Bex1 totally eliminates all
immunoreactivity to Bex1 and Bex2. Bex protein immunoreactivity (ir)
was primarily localized to neuronal cells within select regions of the
brain, including the olfactory bulb, epithelium, peri/paraventricular
nuclei, suprachiasmatic nucleus, arcuate nucleus, median eminence,
lateral hypothalamic area, thalamus, hippocampus, and cerebellum. Bex
protein-ir was broadly present throughout the rostral-caudal aspects of
the hypothalamic region. Further studies, using double-label
immunocytochemistry, indicate that Bex-ir is colocalized with OMP in
mature ORNs and in the OMP-positive subpopulation of hypothalamic
neurons. This is the first anatomical demonstration of the
comprehensive mapping of Bex proteins in the mouse brain and their
colocalization with OMP in ORNs and hypothalamic neurons.
Supported by NIH grants DC003112 and DC00054.
102
386 Poster [ ] Cell Biology of the Olfactory Epithelium
REDUCED OLFACTORY EPITHELIUM MITOTIC RATE IN
STREPTOZOTOCIN-INDUCED DIABETIC RATS
Dennis J.C. 1, Swyers S. 2, Wright J.C. 3, Coleman E.S. 4, Judd R.L. 2, Hoe
L. 2, Morrison E.E. 4 1Anatomy, Physiology and Pharmacology, Auburn
University, Auburn, AL; 2Anatomy, Physiology, Pharacology, Auburn
University, Auburn, AL; 3Pathobiology, Auburn University, Auburn,
AL; 4Anatomy, Physiology, Pharmacology, Auburn University, Auburn,
AL
Individuals who suffer from diabetes frequently develop anosmia for
unknown reasons. The site(s) of disfunction in the olfactory pathways is
(are) not known. We used immunohistochemistry to compare the
numbers of mitotically active cells in the main olfactory epithelium
(OE) of normal (n=4) male Wistar rats and in males (n=4) that suffered
from streptozotocin (STZ)-induced diabetes. Insulin-dependent (type 1)
diabetes was induced by intravenous injection of 50 mg/kg bw STZ.
After 8 weeks, each animal was injected with bromodeoxyuridine
(BrdU) (50ìg/gm bw). An hour later, the animals were deeply
anesthetized with pentobarbital and perfused with buffered 4%
paraformaldehyde. After paraffin embedding, 7 ìm transverse sections
were mounted on slides and hydrated. BrdU(+) cells were counted in 8
nonserial sections from 3 regions dorsal to ventral per animal. The
length of epithelium containing those cells was measured using Spot
Advanced software. Counts were rendered as BrdU(+) cells/mm
epithelium. Analysis by Student´s t Test using SAS 8.2 software
indicated a significant difference in mitotic rates (p0.05).
These data indicate that, after 8 weeks of STZ-induced type 1 diabetes
in Wistar rats, mitotic rate in the main OE is lower in diabetics
compared to normal controls.
387 Poster [ ] Cell Biology of the Olfactory Epithelium
QUALITATIVE AND QUANTITATIVE STUDY OF
CYTOCHROME OXIDASE STAINING PATTERN IN
OLFACTORY EPITHELIUM OF NEONATAL RAT
Pataramekin P.P. 1, Meisami E. 1 1Molecular and Integrative Physiology,
University of Illinois at Urbana-Champaign, Urbana, IL
Newborn rats are capable of olfaction and their olfactory epithelium
(OE) contains functionally mature olfactory receptor neurons (ORNs),
although total ORN number is less than 10% of adult. Cytochrome
oxidase (CO) staining density is positively correlated to levels of
metabolic/neuronal activity. We stained newborn rat OE to characterize
its staining pattern qualitatively and quantitatively. Staining
densitometry was carried out using MCID software to gauge the
luminescence of the sample over a range of 0.0 – 1.0 (higher numbers
indicated lesser CO staining). A differential banding pattern of CO
staining was observed corresponding to specific OE layers and ORN
cellular sites, indicating the parts of the ORNs that were most actively
involved in neuronal activity and transduction. Zones corresponding to
ORN dendrite and knob exhibited high CO activity (0.34). Staining was
heterogeneous within and along the length of dendrites, darker in the
apical part, implying higher neuronal activity in this region than the
deeper part of the dendrite, closer to the soma. A light staining band
(0.40), between the two dark bands, corresponded to the overlapping
presence of supporting cell cytoplasm and nuclei. Areas of OE close to
the basal lamina also stained lightly (>0.44), implying lack of
mitochondria and neuronal functional activity in the basal and immature
neurons. The findings confirm that some ORNs are metabolically
mature and functional in neonatal rats, capable of neuronal function.
Support: University of Illinois Research Funds