Time course of substance P expression in dorsal root ganglia following complete spinal nerve transection

Wendy Weissner, Barbara J. Winterson, Alan Stuart-Tilley, Marshall Devor, Geoffrey M. Bove*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

52 Scopus citations

Abstract

Recent evidence suggests that substance P (SP) is up-regulated in primary sensory neurons following axotomy and that this change occurs in larger neurons that do not usually produce SP. If this is so, then the up-regulation may allow normally neighboring, uninjured, and nonnociceptive dorsal root ganglion (DRG) neurons to become effective in activating pain pathways. By using immunohistochemistry, we performed a unilateral L5 spinal nerve transection on male Wistar rats and measured SP expression in ipsilateral L4 and L5 DRGs and contralateral L5 DRGs at 1-14 days postoperatively (dpo) and in control and sham-operated rats. In normal and sham-operated DRGs, SP was detectable almost exclusively in small neurons (≤800 μm2). After surgery, the mean size of SP-positive neurons from the axotomized L5 ganglia was greater at 2, 4, 7, and 14 dpo. Among large neurons (>800 μm2) from the axotomized L5, the percentage of SP-positive neurons increased at 2, 4, 7, and 14 dpo, Among small neurons from the axotomized L5, the percentage of SP-positive neurons was increased at 1 and 3 dpo but was decreased at 7 and 14 dpo. Thus, SP expression is affected by axonal damage, and the time course of the expression is different between large and small DRG neurons. These data support a role for SP-producing, large DRG neurons in persistent sensory changes resulting from nerve injury.

Original languageEnglish
Pages (from-to)78-87
Number of pages10
JournalJournal of Comparative Neurology
Volume497
Issue number1
DOIs
StatePublished - 1 Jul 2006

Keywords

  • Immunohistochemistry
  • Neuropathy
  • Neuropeptides
  • Pain

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