[Abstract Title]. - Society for Neuroscience

The neurite's cell body resides in either the dorsal root or trigeminal ganglia, and the first
classical synapse for this receptor is thought to be in the spinal cord or medulla. For this reason,
the mechanism of rapid adaptation (RA) has been attributed solely to the mechanical properties
of the capsule of the PC. Past experiments in our laboratory have shown positive
immunoreactivity for glutamate receptors, glutamate transporters, synaptobrevin (VAMP2) and
SNAP-23 on the inner-core lamellae of the PC. Present results show positive labeling for
VAMP2 and GABA receptor 1A in the vicinity of the filopodial tips of the neurite. RT-PCR
results show gene expression for synaptobrevin in the lamellar cells. These results led us to
hypothesize that chemical inhibition, emanating from the lamellar cells, plays a role in the RA
response. Electrophysiological results show that isolated mesenteric PCs have an RA response to
ramp-and-hold stimuli when bathed in Krebs saline. This means that action potentials appear
during the dynamic (start and end of the on and off ramps) portion of the stimulus while little or
no spikes appear during the static (hold) portion. However, when GABA antagonists (0.3mM
gabazine or 4mM picrotoxin) are applied to the bathing solution many spikes appear in the static
portion of the stimulus and these static spikes disappear completely with the application of 0.5M
GABA. Hypothesizing that glutamate (either from the lamellae or from the neurite itself) is
responsible for the static spikes, 20mM kynurenate (a glutamate antagonist) was applied to PCs
that had some small static response. Once again, the static spikes disappeared while the dynamic
ones remained. Together these results lead us to suggest a "mechanochemical" rather than purely
mechanical model for rapid adaptation to sustained pressure in the PC. This glial-neuronal
interaction is a completely novel finding for the Pacinian corpuscle and for somatosensation.
Disclosures: L.J. Pawson, None; L.T. Prestia, None; G.K. Mahoney, None; B. Guclu,
None; P.J. Cox, None; A.K. Pack, None.
Poster
271. Mechanoreceptors
Time: Sunday, November 16, 2008, 1:00 pm - 5:00 pm
Program#/Poster#: 271.6/HH25
Topic: D.09.b. Receptors
Support: HHMI
GMO55831
GM067762
Title: Mechanical responses of cutaneous afferents in ASIC triple KO mice