Enhancement of NMDA receptor phosphorylation of the spinal dorsal horn and nucleus gracilis neurons in neuropathic rats

Xiu Gao, Kee Kim Hee, Mo Chung Jin, Kyungsoon Chung

Research output: Contribution to journalArticle

111 Scopus citations

Abstract

NR1 is an essential component of functional NMDA receptors and can be activated by phosphorylation. It is suggested that phosphorylation of NR1 (pNR1) contributes to central sensitization after intradermal capsaicin injection. The present study investigates whether increases of spinal pNR1 are correlated to central sensitization and thus pain behaviors in neuropathic pain. Neuropathic rats were produced by L5 spinal nerve ligation, mechanical thresholds of the paw were measured, and then the L4/5 spinal cords and the nucleus gracilis (NG) were removed and immunostained for pNR1. The results showed that the number of pNR1-immunoreactive neurons was significantly increased in the ipsilateral cord, at 3, 7, and 28 days after nerve ligation and these increases coincide with mechanical allodynia. The increase of pNR1-immunoreactive neurons in the NG was observed only at 28 days after the nerve ligation. Western blot analyses confirmed the significant increase of pNR1 protein in spinal dorsal horn after nerve ligation. A protein kinase A inhibitor, H89, moderately reversed mechanical allodynia in 7 day neuropathic rats. Many pNR1-immunoreactive neurons were identified as projection neurons by retrograde tracer. The data suggest that PKA mediated NMDA receptor phosphorylation plays an important role in spinal nerve ligation induced neuropathic pain.

Original languageEnglish (US)
Pages (from-to)62-72
Number of pages11
JournalPain
Volume116
Issue number1-2
DOIs
StatePublished - Jul 1 2005

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Keywords

  • Allodynia
  • Central sensitization
  • Glutamate receptor
  • Neuropathic pain
  • Projection neurons
  • Protein kinase

ASJC Scopus subject areas

  • Neurology
  • Clinical Neurology
  • Anesthesiology and Pain Medicine

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