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dopamine-beta-hydroxylase (DBH) and the norepinephrine
transporter (NET) using techniques of immunocytochemistry.
Dopamine-beta-hydroxylase:
Our data indicate that DBH-like
immunoreactivity (LIR) colocalizes with the Type II cell markers
α-gustducin and PLCβ2. Quantitative analysis indicates that
approximately 41 % of PLCβ2-LIR expressing cells also express
DBH-LIR. However, DBH-LIR does not appear to be present in
Type III cells, as DBH-LIR did not colocalize with the Type III cell
marker, NCAM. We are currently investigating the possibility of
colocalization between DBH-LIR and NTPDase-2-LIR, a standard
Type I cell marker.
Norepinephrine Transporter:
Our data show
that NET-LIR is present in both Type II and Type III taste cells.
NET-LIR colocalizes with a subset of IP
3
R3-LIR cells as well as
with two Type III cell markers: serotonin (5HT) and syntaxin-1.
We are currently conducting quantitative studies for these
colocalizations. Based on our preliminary results, we suggest that
DBH-LIR is present in Type II taste cells and that NET-LIR is
present in both Type II and Type III taste cells. Acknowledgements:
This work is supported by NIH grants DC00285 and P30 DC04657
#P20
POSTER SESSION I:
MULTIMODAL RECEPTION;
CHEMOSENSATION & DISEASE;
TASTE PERIPHERY; OLFACTION PERIPHERY
Serotonin’s modulatory effects in the rat taste bud facilitate
the gustatory afferent neural response
Luc F. Jaber, Tamara Kolli, Fang-L. Zhao, Scott Herness
Division of Oral Biology, College of Dentistry, The Ohio State
University Columbus, OH, USA
Serotonin (5-HT), once thought to be the primary neurotransmitter
of the taste bud, is now believed to have a modulatory role in the
generation of the afferent gustatory signal. The nature of this
modulation is not well understood. We have previously
demonstrated that the rat taste bud expresses only the 5-HT
1A
and 5-HT
3
receptor subtypes, and that the 5-HT
1A
-expressing taste
receptor cell (TRC) is paracrine to the 5-HT TRC. The receptor
5-HT
3
is presumed to be expressed in postsynaptic neural elements.
We seek to further understand the nature of 5-HT’s modulatory
role in the rat taste bud and its influence on the afferent signal
by: (1) phenotyping the 5-HT
1A
-expressing cell using
immunocytochemistry and/or
in situ
hybridization double labeling
and RT-PCR, and (2) exploring 5-HT’s role at the neural level
through chorda tympani (CT) recordings in combination with
systemic administration of 5-HT
1A
or 5-HT
3
receptor antagonists
WAY100635 (at 0.01, 0.025, 0.1 or 0.2 mg/kg) and NAD-299 (0.35
mg/kg), and 5-HT
3
receptor antagonist ondansetron (1mg/kg). Our
data show extensive, but not complete co-expression of 5-HT
1A
and
Type II cell markers gustducin, GAD, NPY, and NPY1 receptor,
and almost no co-expression with NCAM, a type III cell marker.
In CT recordings, WAY-100635 at 0.1 mg/kg caused a reversible
reduction in CT response to NaCl (34% reduction), sucrose (59%),
quinine (57%), and HCl (51%). Recovery to near pre-drug values
averaged 45 minutes after drug injection. NAD-299 caused an
irreversible reduction in CT response to NaCl (17% reduction),
sucrose (30%), quinine (30%) and HCl (29%). Administering either
ondansetron or a saline vehicle had no significant effect on CT
responses. We postulate that 5-HT is part of a negative feedback
mechanism for the regulation of ATP release from Type II cells.
Acknowledgements: NIH NIDCD R01 DC00401
#P21
POSTER SESSION I:
MULTIMODAL RECEPTION;
CHEMOSENSATION & DISEASE;
TASTE PERIPHERY; OLFACTION PERIPHERY
Expression of NPY Family Genes in Lingual Cells:
Novel Anatomical Domain and Physiological Functions
Michael S. La Sala
1
, Maria D. Hurtado
1
, Andres Acosta
1
,
Paola P. Riveros
3
, Bruce Baum
3
, Alicia Brown
2
,
Cedrick D. Dotson
2
, Herbert Herzog
4
, Sergei Zolotukhin
1
1
University of Florida Dept. of Pediatrics Gainesville, FL, USA,
2
University of Florida bDepts. of Neuroscience and Psychiatry
Gainesville, FL, USA,
3
Molecular Physiology and Therapeutics
Branch, National Institute of Dental and Craniofacial Research
(NIDCR), National Institutes of Health Bethesda, MD, USA,
4
Garvan Institute of Medical Research Sydney, Australia
The hormones Neuropeptide Y (NPY), Peptide YY (PYY),
Pancreatic Polypeptide (PP) and their cognate receptors YR1,
YR2, YR4, and YR5 are memebers of the NPY gene family and are
widely expressed in the brain as well as on the periphery mediating
multiple metabolic functions. Recently, we have shown the
presence of PYY in the saliva, and the expression of its preferred
receptor, Y2R, in the lingual epithelia. We now extend our finding
to all main NPY family members and characterize their expression
in the lingual basal cell epithelia and in taste receptor cells (TRCs)
in mice. Using IHC and RT PCR protocols, we now show the
expression of the genes coding for NPY, PYY, and PP in the tongue
epithelia and TRCs. In the stratified keratinized lingual epithelial
cells in the dorsum of the tongue, Y receptors are expressed in a
cascade fashion following epithelial cell differentiation. The
cascade manifested in switching from Y1R/Y2R+ progenitor cells
in the basal layer, to Y1R+ cells in the prickle cell layer, to
Y1R/Y5R+ cells in the granular layer, to Y5R+ cells in the
keratinocytes. In addition, Y4R is shown to be expressed in
somatosensory neurons innervating basal layer. In taste buds of the
CV, Y4R was shown to be expressed in nerve fibers innervating
TRCs. Moreover, significant population of TRCs was positive for
Y1R, Y2R, Y4R, or Y5R showing preferential accumulation of
YRs within the microvilli of the apical part of the cells. TRCs
expressing Y receptors also expressed Neural Cell Adhesion
Molecule suggesting their possible role in the gustatory signal
transduction. Taken together these experiments characterize, for
the first time, the expression of all NPY family members in the
lingual mucosa suggesting multiple and diverse functions in the
proliferation/differentiation and in taste perception.
Acknowledgements: University of Florida
#P22
POSTER SESSION I:
MULTIMODAL RECEPTION;
CHEMOSENSATION & DISEASE;
TASTE PERIPHERY; OLFACTION PERIPHERY
Analysis of Taste Information-coding Mechanisms in
Gustatory Neurons
Naohiro Maeda
1
, Azusa Kurokawa
1
, Kurumi Yamamoto
1
,
Chigusa Nagai
1
, Yoshiro Ishimaru
1
, Makoto Ohmoto
1,2
,
Takumi Misaka
1
, Ichiro Matsumoto
1,2
, Keiko Abe
1
1
Department of Applied Biological Chemistry, Graduate School
of Agricultural and Life Sciences, The University of Tokyo Tokyo,
Japan,
2
Monell Chemical Senses Center Philadelphia, PA, USA
Five basic taste modalities are inputted with separate populations
of taste receptor cells, although taste discrimination mechanism
in peripheral nervous system remains unclear. In our previous
Abstracts | 35
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