Mechanisms of rapid receptive field reorganization in rat spinal cord

Rapid receptive field (RF) reorganization of somatosensory neurons in the rat dorsal horn was examined using extracellular single unit recording. Subcutaneous injection of lidocaine into RFs of dorsal horn neurons results in expansion of their RFs within minutes. The expanded RFs appear adjacent to or/and proximal to original RFs. Out of 63 neurons tested, 36 (58%) show RF reorganization. The data suggest that dorsal horn of spinal cord is one of the initial sites for RF reorganization. The neural mechanisms of this effect are not well understood. We propose that changes in biophysical properties (membrane conductance, length constant) of the neurons resulting from lidocaine injection contribute to RF reorganization. Iontophoretic application of glutamate onto dorsal horn neurons that show lidocaine induced RF's expansion were used to test the model. Application of glutamate produced reduction of reorganized RFs in 9 of 20 (45%) tested cells. Application of NBQX produced no effect on either original or expanded RFs indicate that RF shrinkage effects of glutamate involve NMDA receptors. The results are consistent with the prediction of the proposed model. Subcutaneous injection of capsaicin into tactile RFs of low threshold mechanoreceptive dorsal horn neurons produced no effect on the RF sizes that are consistent with other studies. Following the injection, the original RFs were completely silenced (46%) or remained responsive (54%).

Grantor dc:publisher

University of North Texas

Year dc:date

2002

Author dc:creator

• Vu, Hung

Contributors dc:contributor

• Schwark, Harris
• Fuchs, Jannon L.
• Donahue, Manus J.
• Droge, Michael

• Sensory neurons.
• Rats -- Nervous system.
• Spinal cord.
• rapid receptive field
• dorsal horn neurons
• spinal cord dorsal horn
• NBQX
• capsaicin

Statement dc:rights

• Public
• Copyright
• Vu, Hung
• Copyright is held by the author, unless otherwise noted. All rights reserved.

Language dc:language

English

Identifier

oclc: 50949609
https://digital.library.unt.edu/ark:/67531/metadc3197/
ark: ark:/67531/metadc3197

OAI identifier oai:identifier

info:ark/67531/metadc3197