Abstracts - Association for Chemoreception Sciences

These results indicate that IL-1b rapidly augments ENaC
function, in contrast to the cytokine’s delayed inhibition
of sodium transport in other epithelial cells. Together, this
indicates a novel, direct influence of IL-1b on ENaC in taste
buds, mediated by mechanisms which diverge from those acting
in other sodium-transporting epithelia. Acknowledgements:
NIDCD 005811-10
#P157 POSTER SESSION III:
TRIGEMINAL; HUMAN OLFACTORY
PSYCHOPHYSICS; TASTE PERIPHERY
Ryanodine receptors selectively interact with L type calcium
channels in mouse taste cells
Amanda B Maliphol 1 , Michelle R Rebello 1,2 , Kathryn F Medler 1
1
University at Buffalo Buffalo, NY, USA, 2 John B Pierce Lab New
Haven, CT, USA
#P156 POSTER SESSION III:
TRIGEMINAL; HUMAN OLFACTORY
PSYCHOPHYSICS; TASTE PERIPHERY
Ligand Specificity of Orphan G Protein-coupled
Receptor GPR84
Yan Liu, Timothy A. Gilbertson
Department of Biology, Utah State University Logan, UT, USA
Previous studies concluded that medium chain fatty acids
with carbon chain lengths of 9-14 were ligands for GPR84
(Venkataraman and Kuo Immunol Lett 101:144, 2005; Wang et
al. J Biol Chem 281:34457, 2006), however, there has never been
a careful and systematic analysis of the ligand specificity of this
receptor which we have shown previously to be expressed in
mammalian taste cells. As a means to compare the specificity
and concentration-response functions for fatty acids in the taste
system with GPR84, fura-2 based ratiometric calcium imaging
was used to characterize GPR84 in a cell line that has been
designed to express this receptor in an inducible fashion under
control by the tetracycline (TET) promoter. The specific cell line
has an inducible GPR84 + Gqi9 (a chimeric G protein; (Wang
et al., 2006)), which has been cloned, validated by PCR/qPCR
and verified for function in FLIPR-based calcium assays. Noninduced
cells were used as controls. Using fura-2 based calcium
imaging, we found that caproic (C 6:0
), caprylic acid (C 8:0
), capric
acid (C 10:0
), undecanoic acid (C 11:0
), lauric acid (C 12:0
), oleic acid
(C 18:1
), and arachidic acid (C 20:0
) can all elicited a robust and
reversible increase in intracellular calcium in the cells induced
to express GPR84, while they cannot induce any calcium signal
in the non-induced cells. Our results suggest GPR84 functions
as a receptor for unsaturated fatty acids from C 6:0
–C 12:0
and
other fatty acids (oleic acid, arachidic acid) previously not
thought to activate this receptor. Currently, we are investigating
the concentration-response functions for ligands of GPR84 in
the inducible cell line. The specific signaling pathway for fatty
acid transduction through GPR84 receptors and its role in the
peripheral gustatory system remain to be elucidated.
We reported that ryanodine receptors, specifically ryanodine
receptor type 1, are expressed in two different types of
mammalian peripheral taste receptor cells: Type II and Type
III cells. In Type II cells that lack voltage-gated calcium
channels (VGCCs) and chemical synapses, the ryanodine
receptors contributed to the taste-evoked calcium signals that are
initiated by opening inositol trisphosphate receptors located on
internal calcium stores. In Type III cells that do have VGCCs
and chemical synapses, ryanodine rreceptors were no longer
able to contribute to taste-evoked calcium release signals but
contributed to the depolarization-dependent calcium influx.
The goal of this study was to better understand the role of the
ryanodine rreceptors in Type III cells. Specifically, we wished
to establish if there was selectivity in the type of VGCC that
was associated with the ryanodine receptor or if the ryanodine
receptor opened irrespective of the calcium channels involved.
We also wished to determine if the ryanodine receptors and
VGCCs required a physical linkage to interact or were simply
functionally associated with each other. Using calcium imaging
and pharmacological inhibitors on a transgenic mouse line
that expresses green fluorescent protein (GFP) in GAD67
expressing Type III taste cells, we found that ryanodine receptors
are selectively associated with L type VGCCs but not through
a physical linkage. Taste cells are able to undergo calcium
induced calcium release through ryanodine receptors to increase
the initial calcium influx signal and provide a larger calcium
response than would otherwise occur when L type channels are
activated. Acknowledgements: This work was supported by NSF
Grant 0917893 to KFM.
#P158 POSTER SESSION III:
TRIGEMINAL; HUMAN OLFACTORY
PSYCHOPHYSICS; TASTE PERIPHERY
Functional Profile of the Adult Glossopharyngeal Nerve
Following Neonatal Chorda Tympani Transection in Rats
Louis J. Martin, Suzanne I. Sollars
University of Nebraska at Omaha/Psychology Department Omaha,
NE, USA
Rats receiving bilateral neonatal chorda tympani transection
(neoCTX) show an increased preference for ammonium
chloride (NH 4
Cl) as adults – a substance which normal adult
rats never prefer. It is currently unclear what changes to the
taste system underlie this altered preference. To determine if
injury-induced differences in the response properties of the
remaining taste nerves can account for this behavior, whole-nerve
electrophysiology was performed on the glossopharyngeal nerve
POSTER PRESENTATIONS
Abstracts are printed as submitted by the author(s).
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