• Eran Gabay, Gilly Wolf, Yehuda Shavit, Raz Yirmiya, and Michael Tal.
• Department of Anatomy and Cell Biology, Faculty of Dentistry and Medicine, Hebrew University, Jerusalem, Israel.
• Eur J Pain. 2011 Mar 1; 15 (3): 242-8.

AbstractNeuropathic pain is a chronic pain state resulting from peripheral nerve injury, characterized by hyperalgesia and allodynia. We have reported that mice with genetic impairment of IL-1 signaling display attenuated neuropathic pain behavior and ectopic neuronal activity. In order to substantiate the role of IL-1 in neuropathic pain, WT mice were implanted subcutaneously with osmotic micropumps containing either IL-1ra or vehicle. Two days following the implantation, two models of neuropathic pain were used; partial nerve injury (spinal nerve transection, SNT), or complete nerve cut (spinal neuroma model). Mechanosensitivity was assessed seven consecutive days following SNT, and on day 7 recordings of spontaneous ectopic activity were performed. In the spinal nerve neuroma model, autotomy scores were recorded up to 35 days. Vehicle-treated mice developed significant allodynia and autotomy, and clear ectopic activity (4.1±1.1% of the axons); whereas IL-1ra-treated mice did not display allodynic response, displayed delayed onset of autotomy and markedly reduced severity of autotomy scores, and displayed reduced spontaneous activity (0.8±0.4% of the axons). To test whether IL-1 is involved in maintenance of mechanical allodynia, a separate group of WT mice was treated with a single injection of either saline or IL-1ra four days following SNT, after the allodynic response was already manifested. Whereas saline-treated mice displayed robust allodynia, acute IL-1ra treatment induced long-lasting attenuation of the allodynic response. The results support our hypothesis that IL-1 signaling plays an important role in neuropathic pain and in the ectopic neuronal activity that underling its development.Copyright © 2010 European Federation of International Association for the Study of Pain Chapters. All rights reserved.

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