Enhanced pre-synaptic glutamate release in deep-dorsal horn contributes to calcium channel alpha-2-delta-1 protein-mediated spinal sensitization and behavioral hypersensitivity

David Nguyen, Ping Deng, Elizabeth A. Matthews, Doo Sik Kim, Guoping Feng, Anthony H. Dickenson, Zao C. Xu, Z. David Luo

Research output: Contribution to journalArticle

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Abstract

Nerve injury-induced expression of the spinal calcium channel alpha-2-delta-1 subunit (Cavα2 δ1) has been shown to mediate behavioral hypersensitivity through a yet identified mechanism. We examined if this neuroplasticity modulates behavioral hypersensitivity by regulating spinal glutamatergic neurotransmission in injury-free transgenic mice overexpressing the Cavα2δ1 proteins in neuronal tissues. The transgenic mice exhibited hypersensitivity to mechanical stimulation (allodynia) similar to the spinal nerve ligation injury model. Intrathecally delivered antagonists for N-methyl-D-aspartate (NMDA) and α-amino-3-hydroxyl-5-methylisoxazole-4-propionic acid (AMPA)/ kainate receptors, but not for the metabotropic glutamate receptors, caused a dose-dependent allodynia reversal in the transgenic mice without changing the behavioral sensitivity in wild-type mice. This suggests that elevated spinal Cavα2 δ1 mediates allodynia through a pathway involving activation of selective glutamate receptors. To determine if this is mediated by enhanced spinal neuronal excitability or pre-synaptic glutamate release in deep-dorsal horn, we examined wide-dynamic-range (WDR) neuron excitability with extracellular recording and glutamate-mediated excitatory postsynaptic currents with whole-cell patch recording in deep-dorsal horn of the Cav α2δ1 transgenic mice. Our data indicated that overexpression of Cavα2 δ1 in neuronal tissues led to increased frequency, but not amplitude, of miniature excitatory post synaptic currents mediated mainly by AMPA/kainate receptors at physiological membrane potentials, and also by NMDA receptors upon depolarization, without changing the excitability of WDR neurons to high intensity stimulation. Together, these findings support a mechanism of Cavα2 δ1-mediated spinal sensitization in which elevated Cavα2δ1 causes increased pre-synaptic glutamate release that leads to reduced excitation thresholds of post-synaptic dorsal horn neurons to innocuous stimuli. This spinal sensitization mechanism may mediate at least partially the neuropathic pain states derived from increased pre-synaptic Cavα2δ1 expression.

Original languageEnglish
Article number6
JournalMolecular Pain
Volume5
DOIs
StatePublished - Feb 12 2009

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Calcium Channels
Transgenic Mice
Glutamic Acid
Hyperalgesia
Hypersensitivity
Kainic Acid Receptors
Hydroxyl Radical
Wounds and Injuries
Posterior Horn Cells
Neurons
Spinal Nerves
Metabotropic Glutamate Receptors
Neuronal Plasticity
Excitatory Postsynaptic Potentials
Glutamate Receptors
Neuralgia
Patch-Clamp Techniques
N-Methylaspartate
N-Methyl-D-Aspartate Receptors
Synaptic Transmission

ASJC Scopus subject areas

  • Anesthesiology and Pain Medicine
  • Molecular Medicine
  • Cellular and Molecular Neuroscience

Cite this

Enhanced pre-synaptic glutamate release in deep-dorsal horn contributes to calcium channel alpha-2-delta-1 protein-mediated spinal sensitization and behavioral hypersensitivity. / Nguyen, David; Deng, Ping; Matthews, Elizabeth A.; Kim, Doo Sik; Feng, Guoping; Dickenson, Anthony H.; Xu, Zao C.; Luo, Z. David.

In: Molecular Pain, Vol. 5, 6, 12.02.2009.

Research output: Contribution to journalArticle

Nguyen, David ; Deng, Ping ; Matthews, Elizabeth A. ; Kim, Doo Sik ; Feng, Guoping ; Dickenson, Anthony H. ; Xu, Zao C. ; Luo, Z. David. / Enhanced pre-synaptic glutamate release in deep-dorsal horn contributes to calcium channel alpha-2-delta-1 protein-mediated spinal sensitization and behavioral hypersensitivity. In: Molecular Pain. 2009 ; Vol. 5.
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