title: Experimental Disc Herniation in the Rat Causes Downregulation of Serotonin Receptor 2c in a TNF-dependent Manner.
abstract: BACKGROUND
  During recent decades, the knowledge of the pathophysiology of disc herniation and sciatica has drastically improved. What previously was considered a strict biomechanical process is now considered a more complex interaction between leaked nucleus pulposus and the tissue in the spinal canal. An inflammatory reaction, with tumor necrosis factor (TNF) playing an essential role, has been demonstrated. However, the exact mechanisms of the pathophysiology of disc herniation remain unknown.
  
  
  OBJECTIVE
  In this study we use an animal model to investigate (1) if and/or how experimental disc herniation affects gene expression in the early phase (24 hours postsurgery) in the dorsal root ganglion; and (2) if TNF inhibition can reduce any observed changes.
  
  
  METHODS
  A rat model of disc herniation was used. Twenty rats were evenly divided into four groups: naïve, sham, disc herniation, and disc herniation with TNF inhibition. The dorsal root ganglion of the affected nerve root was harvested 24 hours after surgery and analyzed with a TaqMan Low Density Array(®) quantitative polymerase chain reaction assay. Gene expression levels in sham were compared with disc herniation to assess question 1 and disc herniation to disc herniation with TNF inhibition to assess question 2.
  
  
  RESULTS
  Experimental disc herniation caused a decrease in the expression of the serotonin receptor 2c gene (p = 0.022). TNF inhibition was found to reduce the observed decrease in expression of serotonin receptor 2c (p = 0.037).
  
  
  CONCLUSIONS
  Our results suggest that a decrease in the expression of the serotonin receptor 2c gene may contribute to the pathophysiology of disc herniation. Further research on its involvement is warranted.
  
  
  CONCLUSIONS
  This pilot study gives a brief insight into cellular changes that may contribute to the pathophysiology of disc herniation. This knowledge may contribute to the development of more and better treatment options for patients with disc herniation and sciatica.
authors.affiliation: Musculoskeletal Research, Department of Medical Chemistry and Cell Biology, Institute of Biomedicine, Sahlgrenska Academy, University of Gothenburg, 405 30, Gothenburg, Sweden.
authors.forename: Daniel
authors.initials: D
authors.lastname: Jonsson
authors.forename: Oscar
authors.initials: O
authors.lastname: Finskas
authors.forename: Yuki
authors.initials: Y
authors.lastname: Fujioka
authors.forename: Anders
authors.initials: A
authors.lastname: Ståhlberg
authors.forename: Kjell
authors.initials: K
authors.lastname: Olmarker
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000494:pharmacology; D004195:Disease Models, Animal; D015536:Down-Regulation; D005260:Female; D005727:Ganglia, Spinal / Q000187:drug effects / Q000276:immunology / Q000378:metabolism* / Q000503:physiopathology; D020869:Gene Expression Profiling / Q000379:methods; D018836:Inflammation Mediators / Q000037:antagonists & inhibitors / Q000378:metabolism*; D000069285:Infliximab; D007403:Intervertebral Disc / Q000187:drug effects / Q000276:immunology / Q000378:metabolism* / Q000503:physiopathology; D007405:Intervertebral Disc Displacement / Q000235:genetics / Q000276:immunology / Q000378:metabolism* / Q000503:physiopathology; D010865:Pilot Projects; D016133:Polymerase Chain Reaction; D051381:Rats; D017207:Rats, Sprague-Dawley; D044405:Receptor, Serotonin, 5-HT2C / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D013997:Time Factors; D014409:Tumor Necrosis Factor-alpha / Q000037:antagonists & inhibitors / Q000378:metabolism*
chemical_list: D000911:Antibodies, Monoclonal; D018836:Inflammation Mediators; D044405:Receptor, Serotonin, 5-HT2C; D014409:Tumor Necrosis Factor-alpha; D000069285:Infliximab