[Abstract Title]. - Society for Neuroscience

we examined whether the functional change of AMPA-type glutamate receptors is involved in
the plastic changes of the spinal nociceptive synaptic transmission in vivo following
inflammation. In inflamed rats 24 h after intraplantar injection of complete Freund‟s adjuvant,
whole-cell recordings were obtained from substantia gelatinosa (SG, lamina II of the spinal cord)
neurons with resting membrane potentials of about -60 mV. In the presence of bicuculline,
strychnine and D-APV, all neurons of inflamed rats tested exhibited spontaneous EPSCs at a
holding potential of -70 mV. Large amplitudes of EPSCs were frequently observed in SG
neurons that had receptive fields located on the inflamed skin on the hind paw or lower leg
compared with the amplitudes of SG neurons that had receptive fields located on the uninflamed
skin on the upper leg or thigh. The spontaneous events were completely inhibited by CNQX and
GYKI52466. Pinch stimulation applied to the skin elicited a barrage of EPSCs with large
amplitudes. Whereas the I-V relationship of the pinch-evoked current charges in the SG neurons
that had receptive fields located on the uninflamed skin was linear, that in the SG neurons having
receptive fields located on the inflamed skin was inwardly rectified. The average rectification
index (RI) of pinch-evoked EPSCs in the SG neurons received from inflamed skin was lower
than that from the uninflamed skin. Application of PhTx, a Ca 2+ -permeable AMPA receptore
(CP-AMPAR) antagonist, markedly inhibited the pinch-evoked responses in SG neurons that had
receptive fields located on the inflamed skin, though EPSCs with large amplitudes were still
elicited at lower frequencies than those in the control in the absence of PhTX, thus suggesting
that the excitatory synaptic inputs in single SG neurons were mostly mediated by CP-AMPAR.
The amplitude of current charges of the pinch-evoked EPSCs was significantly decreased in the
presence of PhTx. Even at the same spinal level in the same rats, however, SG neurons with
receptive fields located on the uninflamed skin were insensitive to PhTX. These results suggest
that CP-AMPARs in the superficial spinal dorsal horn received from inflamed skin have an
important role in the induction of central sensitization following inflammation.
Disclosures: H. Furue , None; M. Yoshimura, None.
Poster
268. Neuropathic Pain Mechanisms: Ion Channels
Time: Sunday, November 16, 2008, 1:00 pm - 5:00 pm
Program#/Poster#: 268.3/FF34
Topic: D.08.l. Neuropathic pain: Mechanisms
Title: Behavioral and electrophysiological analyses of spinal nociceptive transmiss ion in a
murine model of cancer-induced bone pain
Authors: *Y. YANAGISAWA 1,2 , H. FURUE 2 , T. KAWAMATA 3 , D. UTA 2 , A. NAMIKI 3 , Y.
IWAMOTO 1 , M. YOSHIMURA 2 ;