title: The effects of an intraperitoneal single low dose of ketamine in attenuating the postoperative skin/muscle incision and retraction-induced pain related to the inhibition of N-methyl-D-aspartate receptors in the spinal cord.
abstract: BACKGROUND
  Chronic postoperative pain (CPOP) is a common clinical problem which might be related to central sensitization. It has been widely accepted that NMDA (N-methyl-D-aspartate) receptors are among the triggers of central sensitization. Ketamine is a non-competitive NMDA receptor antagonist that is widely used in alleviating postoperative pain, but its effect on CPOP has been rarely reported. In the present study, the skin/muscle incision and retraction (SMIR) model was used to investigate the role of NMDARs in chronic postoperative pain and the effect of an intraperitoneal single low dose ketamine (10mg/kg) of attenuating SMIR-induced CPOP.
  
  
  METHODS
  We assessed pain behaviours after a SMIR operation by paw withdrawal threshold (PWMT) and paw withdrawal latency (PWMTL). Western blotting were performed to examine the role of NMDARs in SMIR-induced CPOP and the effect of ketamine on the expression and phosphorylation of NMDARs.
  
  
  RESULTS
  The SMIR operation induced long-lasting mechanical hyperalgesia, and the up-regulation of phosphorylated NMDARs and total NMDARs at the spinal level. A single intraperitoneal administration of low dose ketamine (10mg/kg) during surgery alleviated pain behaviors and inhibited the up-regulation of phosphorylated NMDARs and total NMDARs.
  
  
  CONCLUSIONS
  Our datas suggested that NMDARs play important roles in SMIR-induced CPOP. A single intraperitoneal low dose of ketamine could attenuate SMIR-induced CPOP, which might be associated with the inhibition of NMDARs. Our finding might provide a new, simple method of addressing CPOP.
authors.affiliation: Department of Anesthesiology, Affiliated Drum Tower Hospital of Medical Department of Nanjing University, Nanjing, Jiangsu, China. Electronic address: feather0417@sina.com.
authors.forename: Yu
authors.initials: Y
authors.lastname: Shen
authors.affiliation: Department of Anesthesiology, Affiliated Drum Tower Hospital of Medical Department of Nanjing University, Nanjing, Jiangsu, China. Electronic address: 275585794@qq.com.
authors.forename: Li
authors.initials: L
authors.lastname: Xu
authors.affiliation: Department of Anesthesiology, Affiliated Drum Tower Hospital of Medical Department of Nanjing University, Nanjing, Jiangsu, China. Electronic address: liuming0225@126.com.
authors.forename: Ming
authors.initials: M
authors.lastname: Liu
authors.affiliation: Department of Anesthesiology, Affiliated Drum Tower Hospital of Medical Department of Nanjing University, Nanjing, Jiangsu, China. Electronic address: mikunichan@sina.com.
authors.forename: Yishan
authors.initials: Y
authors.lastname: Lei
authors.affiliation: Department of Anesthesiology, Affiliated Drum Tower Hospital of Medical Department of Nanjing University, Nanjing, Jiangsu, China. Electronic address: 13813996903@126.com.
authors.forename: Xiaoping
authors.initials: X
authors.lastname: Gu
authors.affiliation: Department of Anesthesiology, Affiliated Drum Tower Hospital of Medical Department of Nanjing University, Nanjing, Jiangsu, China. Electronic address: mazhengliang1964@nju.edu.cn.
authors.forename: Zhengliang
authors.initials: Z
authors.lastname: Ma
mesh_terms: D000700:Analgesics / Q000008:administration & dosage*; D000818:Animals; D007274:Injections, Intraperitoneal; D007649:Ketamine / Q000008:administration & dosage*; D008297:Male; D018482:Muscle, Skeletal / Q000601:surgery; D010149:Postoperative Pain / Q000188:drug therapy*; D017207:Rats, Sprague-Dawley; D016194:Receptors, N-Methyl-D-Aspartate / Q000037:antagonists & inhibitors* / Q000378:metabolism; D013116:Spinal Cord / Q000187:drug effects* / Q000378:metabolism
chemical_list: D000700:Analgesics; D016194:Receptors, N-Methyl-D-Aspartate; D007649:Ketamine
keywords: Central sensitization; Chronic postoperative pain; N-methyl-d-aspartate; Skin/muscle incision and retraction