title: Gene expression in skin, muscle, and dorsal root ganglion after plantar incision in the rat.
abstract: BACKGROUND
  Treating postoperative pain remains a significant challenge for perioperative medicine. Recent studies have shown that nerve growth factor is up-regulated and contributes to incisional pain. To date, few studies have examined expression of other neurotrophin-related mediators that may contribute to the development and/or maintenance of incisional pain.
  
  
  METHODS
  Male Sprague-Dawley rats underwent a plantar incision, and pain behaviors were examined (n = 6). In a separate group of rats, expression of neurotrophic factors were studied. At various times after incision (n = 4) or sham surgery (n = 4), the skin, muscle, and dorsal root ganglia were harvested and total RNA isolated. Real-time reverse transcription polymerase chain reaction was performed and the fold change in gene expression was analyzed using significance analysis of microarrays.
  
  
  RESULTS
  Several genes were changed (P < 0.05) as early as 1 h after incision. Expression of artemin and nerve growth factor were increased in both incised skin and muscle. Brain-derived neurotrophic factor, neurotrophin-3, and neurotrophin-5 were all down-regulated in the skin but up-regulated in the muscle 48 h after incision. Few genes changed in the dorsal root ganglion. Most changes in expression occurred in the first 48 h after incision, a timeframe when pain behavior was the greatest.
  
  
  CONCLUSIONS
  Surgical incision is associated with pain-related gene expression changes in skin, muscle, and, to a lesser extent, dorsal root ganglion. The gene expression profile provides clues as to mediators that are involved in peripheral sensitization and pain transmission after surgical incision and also suggest mechanisms for resolution of postoperative pain when more persistent pain syndromes like neuropathic pain continue.
authors.affiliation: Department of Anesthesia, University of Iowa, Iowa City, Iowa 52242, USA. christina-spofford@uiowa.edu
authors.forename: Christina M
authors.initials: CM
authors.lastname: Spofford
authors.forename: Timothy J
authors.initials: TJ
authors.lastname: Brennan
mesh_terms: D000818:Animals; D019208:Brain-Derived Neurotrophic Factor / Q000235:genetics; D005727:Ganglia, Spinal / Q000378:metabolism*; D005786:Gene Expression Regulation; D051100:Glial Cell Line-Derived Neurotrophic Factor / Q000235:genetics; D008297:Male; D009132:Muscles / Q000378:metabolism*; D020932:Nerve Growth Factor / Q000235:genetics; D020933:Neurotrophin 3 / Q000502:physiology; D010149:Postoperative Pain / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012867:Skin / Q000378:metabolism*
chemical_list: D019208:Brain-Derived Neurotrophic Factor; D051100:Glial Cell Line-Derived Neurotrophic Factor; D020933:Neurotrophin 3; D020932:Nerve Growth Factor