title: The thalidomide analgesic effect is associated with differential TNF-α receptor expression in the dorsal horn of the spinal cord as studied in a rat model of neuropathic pain.
abstract: The proinflammatory cytokine tumor necrosis factor-α (TNF-α) is well recognized as a key player in nociceptive signaling. Yet, therapeutic capitalization of this knowledge requires a better understanding of how TNF receptors (TNFR) contribute to pain. To address this question, we studied TNFR expression in the chronic sciatic nerve constriction (CCI) model of neuropathic pain. CCI and sham operated rats received two subcutaneous injections (one immediately after surgery, the other on postoperative day 5) containing either saline, GABA-reuptake inhibitor (NO-711), insulin-like growth factor-1 (IGF-1), ZVAD or thalidomide. Mechanical (using von Frey filaments) and thermal hypersensitivity (Hargreaves test) were assessed preoperatively and weekly during the first four postoperative weeks. Spinal cord dorsal horn samples were collected from animals that were sacrificed at 2 weeks and 4 weeks after surgery, and analyzed for TNFR1 and TNFR2 mRNA levels by qPCR and protein levels by Western blot. Compared to saline, all applied drug treatments resulted in a faster recovery from mechanical and thermal hypersensitivity, yet in a potency order of thalidomide>ZVAD=IGF-1>NO-711. CCI resulted in increased TNFR1 and TNFR2 mRNA and protein levels in the ipsilateral dorsal horn. Thalidomide was the only treatment that attenuated these increases. Finally, animals that showed a poor behavioral recovery were characterized by a significantly higher TNFR1/TNFR2 mRNA ratio. These data show that differential expression of TNFR in the dorsal horn is associated with recovery from pain in this model and suggest that the analgesic effects of thalidomide may act via this mechanism.
authors.affiliation: Department of Neuroscience, Faculty of Health, Medicine and Life Sciences, Maastricht University, Maastricht, The Netherlands. p.andrade@maastrichtuniversity.nl
authors.forename: Pablo
authors.initials: P
authors.lastname: Andrade
authors.forename: Veerle
authors.initials: V
authors.lastname: Visser-Vandewalle
authors.forename: John S
authors.initials: JS
authors.lastname: Del Rosario
authors.forename: Marc A
authors.initials: MA
authors.lastname: Daemen
authors.forename: Wim A
authors.initials: WA
authors.lastname: Buurman
authors.forename: Harry W
authors.initials: HW
authors.lastname: Steinbusch
authors.forename: Govert
authors.initials: G
authors.lastname: Hoogland
mesh_terms: D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects; D004195:Disease Models, Animal; D006930:Hyperalgesia / Q000188:drug therapy / Q000378:metabolism; D008297:Male; D009437:Neuralgia / Q000188:drug therapy / Q000378:metabolism*; D010147:Pain Measurement / Q000187:drug effects*; D020671:Posterior Horn Cells / Q000187:drug effects / Q000378:metabolism*; D051381:Rats; D047888:Receptors, Tumor Necrosis Factor, Type I / Q000235:genetics / Q000378:metabolism*; D047889:Receptors, Tumor Necrosis Factor, Type II / Q000235:genetics / Q000378:metabolism; D020426:Sciatic Neuropathy / Q000188:drug therapy / Q000378:metabolism; D013116:Spinal Cord / Q000187:drug effects / Q000378:metabolism*; D013792:Thalidomide / Q000494:pharmacology / Q000627:therapeutic use*
chemical_list: D047888:Receptors, Tumor Necrosis Factor, Type I; D047889:Receptors, Tumor Necrosis Factor, Type II; C506237:Tnfrsf1a protein, rat; D013792:Thalidomide