Inflammatory activation of satellite glial cells in the dorsal root ganglia after nerve and skin injury
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| Year of publication | 2013 |
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| Description | The satellite glial cells (SGC) envelope the primary sensory neurons of the dorsal root ganglia (DRG) and react intensely to various types of nerve injury that induce neuropathic pain. Inflammatory activation of SGC after skin incision is still not well understood. Unilateral chronic constriction injury (CCI, n=64) of the sciatic nerve and skin incision in thigh (SIT, n=32) performed under aseptic conditions were used as experimental model of neuropathic (NPP) and surgical pain, respectively. Withdrawal threshold of mechanical and thermal hyperalgesia were tested bilaterally in hairless skin of fore and hind paws. Expression of TNFa, IL-6, their receptors and signaling proteins and mRNAs were investigated bilaterally by immunohistochemistry and in situ hybridization in both lumbar (L4-5) and cervical (C7-8) DRG 1, 3, 7 and 14 days from surgery. The SGC were identified by colocalization with GFAP or GS. Ipsilateral hind paws of all CCI-operated rats displayed mechanical and thermal hyperalgesia from 1 to 14 days, but temporal changes were measured in contralateral hind paws and forepaws of both sides. Hyperalgesia was measured in SIT-operated animals only during early periods of survival (1-3 days). Inflammatory activation of DRG neurons and their SGC detected by upregulation of cytokines and their receptors was found in DRG after nerve injury, while only SGC were activated after skin incision. These results suggest different mechanisms inducing inflammatory reactions in DRG and their regulation after traumatic nerve injury and skin incision. |
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