Neuronal NR2B-containing NMDA receptor mediates spinal astrocytic c-Jun N-terminal kinase activation in a rat model of neuropathic pain

Wei Wang, Xiao Peng Mei, Yan Yan Wei, Ming Ming Zhang, Ting Zhang, Wen Wang, Li Xian Xu, Sheng Xi Wu, Yun Qing Li

Research output: Contribution to journalArticlepeer-review

Abstract

Spinal N-methyl d-aspartate receptor (NMDAR) plays a pivotal role in nerve injury-induced central sensitization. Recent studies suggest that NMDAR also contributes to neuron-astrocyte signaling. c-Jun N-terminal kinase (JNK) is persistently and specifically activated (indicated by phosphorylation) in spinal cord astrocytes after nerve injury and thus it is considered as a dependable indicator of pain-related astrocytic activation. NMDAR-mediated JNK activation in spinal dorsal horn might be an important form of neuron-astrocyte signaling in neuropathic pain. In the present study, we observed that intrathecal injection of MK-801, a noncompetitive NMDA receptor antagonist, or Ro25-6981 and ifenprodil, which are selective antagonists of NR2B-containing NMDAR each significantly reduced nerve injury-induced JNK activation. Double immunostaining showed that NR2B was highly expressed in neurons, indicating the effect of NMDAR antagonists on JNK activation was indirect. We further observed that intrathecal injection of NMDA (twice a day for 3. days) significantly increased spinal JNK phosphorylation. Besides, NMDAR-related JNK activation could be blocked by a neuronal nitric oxide synthase (nNOS) selective inhibitor (7-nitroindazole sodium salt) but not by a nNOS sensitive guanylyl cyclase inhibitor (1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one). Finally, real-time RT-PCR and immunostaining showed that nerve injury-induced interleukin-1beta expression was dependent on astrocytic JNK activation. Treatments targeting NMDAR-nNOS pathway also influenced interleukin-1beta expression, which further confirmed our hypothesis. Taken together, our results suggest that neuronal NMDAR-nNOS pathway could activate astrocytic JNK pathway. Excitatory neuronal transmission initiates astrocytic activation-induced neuroinflammation in this way, which contributes to nerve injury-induced neuropathic pain.

Original languageEnglish (US)
Pages (from-to)1355-1366
Number of pages12
JournalBrain, Behavior, and Immunity
Volume25
Issue number7
DOIs
StatePublished - Oct 2011
Externally publishedYes

Keywords

  • Astrocyte
  • C-jun n-terminal kinase
  • NMDA receptor
  • Neuropathic pain
  • Spinal cord

ASJC Scopus subject areas

  • Immunology
  • Endocrine and Autonomic Systems
  • Behavioral Neuroscience

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