Abstracts - Association for Chemoreception Sciences

early postnatal period. This shift is concurrent with terminal
field plasticity, i.e., developmental remodeling and fine-tuning
of circuits. Furthermore, the GFAP-positive astrocyte-like
cells are differentially distributed throughout the rNST. This
work highlights potential neuron-glia interactions that are
important for the development of the gustatory brainstem.
The results provide basic information for building mechanistic
studies regarding glial function in taste circuit formation.
Acknowledgements: NIH NIDCD Grant DC009982
#P218 POSTER SESSION V:
HUMAN TASTE PSYCHOPHYSICS;
OLFACTION RECEPTORS; TASTE DEVELOPMENT
The p75 receptor regulates gustatory innervation patterns
during development
Da Fei, Robin Krimm
University of Louisville/Anatomical Sciences and Neurobiology
Louisville, KY, USA
#P217 POSTER SESSION V:
HUMAN TASTE PSYCHOPHYSICS;
OLFACTION RECEPTORS; TASTE DEVELOPMENT
Functions of the GDNF family of neurotrophic factors in the
development of the peripheral gustatory system
Christopher R. Donnelly, Brian A. Pierchala
University of Michigan School of Dentistry/Biologic and Materials
Sciences Ann Arbor, MI, USA
During development of the peripheral nervous system (PNS),
target-derived neurotrophic factors, such as the neurotrophins
and the glial cell-line derived neurotrophic factor (GDNF) family
ligands (GFLs), are critical for the establishment of proper
connections between neurons and their targets. The four GFLs,
GDNF, neurturin (NRTN), artemin (ARTN) and persephin
(PSPN), are potent growth, guidance and survival factors
for both PNS and CNS neurons. The GFLs bind with high
affinity to GPI-anchored coreceptors called the GFRalphas, of
which there are four (GFRalpha1-4). In the PNS, these GFL-
GFRalpha complexes then associate with and activate their
common receptor tyrosine kinase, Ret. Several of the GFLs and
their receptors are expressed by components of the peripheral
gustatory system. GDNF and NRTN are expressed throughout
the lingual epithelium, and GDNF, GFRalpha1, GFRalpha2
and Ret are all expressed in taste buds of circumvallate papillae.
In addition, neurons of the petrosal and geniculate ganglia
express Ret and cognate GFRalphas. It is not known, however,
whether GFLs function in the development and maintenance
of peripheral gustatory circuits. Using conditional transgenic
deletion of Ret, we are in the process of determining whether the
GFL/Ret signaling pathway is necessary for the development
of fungiform papillae, taste buds within circumvallate and
fungiform papillae, and their respective innervation by petrosal
and geniculate neurons. These studies will establish whether
other neurotrophic factors besides BDNF and NT-4 have
developmental functions in the embryonic morphogenic events
in the lingual epithelium necessary for papillae and taste bud
development, as well as growth and survival functions for
the sensory neurons that innervate these lingual structures.
Acknowledgements: BAP: NINDS R01 NS058510 CRD:
NIDCR TEAM Tissue Engineering and Regeneration Training
Grant T32 DE007057
As a pan receptor of neurotrophins, p75 can function as either
a pro-survival or pro-death factor during development. P75 is
expressed in both taste buds and taste (geniculate) neurons;
however, the role of p75 receptor during taste development is
unclear. Here we examined the role of p75 in neuron survival,
taste bud formation and peripheral innervation patterns during
development. We found that p75 -/- mice began to lose about
22% (p=0.05) of geniculate neurons compared to the wild type
mice at E14.5, and the loss continued to around 36% (p