Expression of opioid receptors and c-fos in CB1 knockout mice exposed to neuropathic pain

Olga Pol, Patricia Murtra, Laura Caracuel, Olga Valverde, Margarita M. Puig, Rafael Maldonado*

*Corresponding author for this work

Research output: Contribution to journalArticleResearchpeer-review

31 Citations (Scopus)

Abstract

The development of neuropathic pain is associated with multiple changes in gene expression occurring in the dorsal root ganglia (DRG) and spinal cord. The goal of this study was to evaluate whether the disruption of CB1 cannabinoid receptor gene modulates the changes induced by neuropathic pain in the expression of μ- (MOR), δ- (DOR) and κ-opioid receptors (KOR) mRNA levels in the DRG and spinal cord. The induction of c-fos expression in the lumbar and sacral regions of the spinal cord was also evaluated in these animals. Opioid receptors mRNA levels were determined by using real-time PCR and Fos protein levels by immunohistochemistry. Nerve injury significantly reduced the expression of MOR in the DRG and the lumbar section of the spinal cord from CB1 cannabinoid knockout (KO) mice and wild-type littermates (WT). In contrast, mRNA levels of DOR and KOR were not significantly changed in any of the different sections analysed. Furthermore, sciatic nerve injury evoked a similar increase of c-fos expression in lumbar and sacral regions of the spinal cord of both KO and WT. In all instances, no significant differences were observed between WT and KO mice. These data revealed specific changes induced by neuropathic pain in MOR expression and c-fos levels in the DRG and/or spinal cord that were not modified by the genetic disruption of CB1 cannabinoid receptors.

Original languageAmerican English
Pages (from-to)123-132
Number of pages10
JournalNeuropharmacology
Volume50
Issue number1
DOIs
Publication statusPublished - Jan 2006

Keywords

  • c-fos
  • CB1 cannabinoid receptor
  • Dorsal root ganglia
  • Neuropathic pain
  • Opioid receptor
  • Spinal cord

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