Title: Bilateral changes of SDF-1 and its receptor CXCR4 in the dorsalroot ganglia of chronic constriction injury and spinal nerveligation models of neuropathic pain
Abstract: There is compelling evidence indicating that hyperalgesia,
allodynia and ongoing pain associated with peripheral nerve
injury are due to changes in the DRG. Chronic constriction
injury (CCI) and spinal nerve ligation (SNL) are most
frequently used experimental models of neuropathic pain based
on nerve injury. Chemokines are small chemotactic cytokines
which produce their effects by activating a family of G-protein
coupled receptors. Some recent studies have shown that
regulation of chemokines is one of the mechanisms underlying
the development and maintenance of neuropathic pain. The
biological activity of stromal cell-derived factor (SDF1) is
signaled through the chemokine receptor CXCR4 which is unique
among chemokine receptors, having only one known ligand. The
role of SDF1/CXCR4 in the peripheral nervous system is implied
by their early expression in neural crest cells/derivatives as
well as in the dorsal root ganglia (DRG). The goal of our
experiments was to compare an immunohistochemical staining for
SDF-1 and CXCR4 proteins in the L4-L5 DRG of naive rats and
those operated for unilateral L4-L5 SNL and CCI of sciatic
nerve. The naive DRG displayed a sharp immunofluorescence for
SDF1 (SDF1-IF) at the surface of neuron/satellite glial cell
units. A significant decrease of SDF1-IF was induced
bilaterally in the L4-L5 DRG 3 days after both CCI and SNL. A
diffuse immunofluorescence for SDF1 was found in SGC after both
types of nerve injuries for 1 and 2 weeks with a higher
intensity following CCI. CXCR4-IF was present in the small- and
medium sized neurons and the satellite glial cells (SGC)
enveloping the large-sized neurons of naive DRG. CXCR4-IF was
unchanged in the small- and medium sized neurons in the DRG
from operated rats for all periods of survival. A significant
reduced CXCR4-IF was observed in the SGC of contralateral DRG
after both types of nerve injuries, but was elevated at the
surface of large-sized neurons of ipsilateral DRG when CCI was
applied. Latter pattern of staining was not significantly
developed following SNL. Our results suggest different
regulation of SDF1/CXCR4 expression in the DRG during various
periods of survival and by the type of nerve injury used in
neuropathic pain models.
Publication Year: 2007
Publication Date: 2007-01-01
Language: en
Type: article
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