title: Opioid-induced hyperalgesia in a mice model of orthopaedic pain: preventive effect of ketamine.
abstract: BACKGROUND
  The aim of this study was to assess the preventative effect of ketamine on the exaggerated postoperative pain observed in sufentanil-treated mice and its ability to improve the analgesic effectiveness of morphine during the postoperative period in an orthopaedic model of pain.
  
  
  METHODS
  In this study, we assessed the effects of ketamine on sufentanil enhancement of pain behaviour induced by fracture and the effects of ketamine on postoperative morphine-induced analgesia. Three tests were used to assess pain behaviour: von Frey filament application, hot-plate test, and a subjective pain scale.
  
  
  RESULTS
  When administered 1 day after surgery in mice treated with sufentanil on D0 (before surgery), morphine induced an analgesic effect as observed by the nociceptive threshold increase in saline- and ketamine-treated mice. Morphine was more effective in ketamine-treated (1 and 50 mg kg(-1)) mice.
  
  
  CONCLUSIONS
  Our results suggest that pre-emptive use of ketamine is useful in orthopaedic surgery in this mice model to diminish short- and long-term hyperalgesia, but also to improve morphine effectiveness leading to a better mobilization and more rapid rehabilitation.
authors.affiliation: Department of Anesthesiology and Intensive Care, Toulouse University Hospital Rangueil, Toulouse, France. minville.v@chu-toulouse.fr
authors.forename: V
authors.initials: V
authors.lastname: Minville
authors.forename: O
authors.initials: O
authors.lastname: Fourcade
authors.forename: J-P
authors.initials: JP
authors.lastname: Girolami
authors.forename: I
authors.initials: I
authors.lastname: Tack
mesh_terms: D000700:Analgesics / Q000627:therapeutic use; D000701:Analgesics, Opioid / Q000009:adverse effects*; D000818:Animals; D004195:Disease Models, Animal; D004353:Drug Evaluation, Preclinical / Q000379:methods; D004359:Drug Therapy, Combination; D006930:Hyperalgesia / Q000139:chemically induced / Q000517:prevention & control*; D007649:Ketamine / Q000627:therapeutic use*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D009020:Morphine / Q000627:therapeutic use; D019637:Orthopedic Procedures; D010147:Pain Measurement / Q000379:methods; D010149:Postoperative Pain / Q000139:chemically induced / Q000517:prevention & control*; D011229:Preanesthetic Medication; D017409:Sufentanil / Q000009:adverse effects
chemical_list: D000700:Analgesics; D000701:Analgesics, Opioid; D007649:Ketamine; D009020:Morphine; D017409:Sufentanil