JNK-induced MCP-1 production in spinal cord astrocytes contributes to central sensitization and neuropathic pain.

Published

Journal Article

Our previous study showed that activation of c-jun-N-terminal kinase (JNK) in spinal astrocytes plays an important role in neuropathic pain sensitization. We further investigated how JNK regulates neuropathic pain. In cultured astrocytes, tumor necrosis factor alpha (TNF-alpha) transiently activated JNK via TNF receptor-1. Cytokine array indicated that the chemokine CCL2/MCP-1 (monocyte chemoattractant protein-1) was strongly induced by the TNF-alpha/JNK pathway. MCP-1 upregulation by TNF-alpha was dose dependently inhibited by the JNK inhibitors SP600125 (anthra[1,9-cd]pyrazol-6(2H)-one) and D-JNKI-1. Spinal injection of TNF-alpha produced JNK-dependent pain hypersensitivity and MCP-1 upregulation in the spinal cord. Furthermore, spinal nerve ligation (SNL) induced persistent neuropathic pain and MCP-1 upregulation in the spinal cord, and both were suppressed by D-JNKI-1. Remarkably, MCP-1 was primarily induced in spinal cord astrocytes after SNL. Spinal administration of MCP-1 neutralizing antibody attenuated neuropathic pain. Conversely, spinal application of MCP-1 induced heat hyperalgesia and phosphorylation of extracellular signal-regulated kinase in superficial spinal cord dorsal horn neurons, indicative of central sensitization (hyperactivity of dorsal horn neurons). Patch-clamp recordings in lamina II neurons of isolated spinal cord slices showed that MCP-1 not only enhanced spontaneous EPSCs but also potentiated NMDA- and AMPA-induced currents. Finally, the MCP-1 receptor CCR2 was expressed in neurons and some non-neuronal cells in the spinal cord. Together, we have revealed a previously unknown mechanism of MCP-1 induction and action. MCP-1 induction in astrocytes after JNK activation contributes to central sensitization and neuropathic pain facilitation by enhancing excitatory synaptic transmission. Inhibition of the JNK/MCP-1 pathway may provide a new therapy for neuropathic pain management.

Full Text

Duke Authors

Cited Authors

  • Gao, Y-J; Zhang, L; Samad, OA; Suter, MR; Yasuhiko, K; Xu, Z-Z; Park, J-Y; Lind, A-L; Ma, Q; Ji, R-R

Published Date

  • April 1, 2009

Published In

Volume / Issue

  • 29 / 13

Start / End Page

  • 4096 - 4108

PubMed ID

  • 19339605

Pubmed Central ID

  • 19339605

Electronic International Standard Serial Number (EISSN)

  • 1529-2401

Digital Object Identifier (DOI)

  • 10.1523/JNEUROSCI.3623-08.2009

Language

  • eng

Conference Location

  • United States