title: Ketamine and N-acetylaspartylglutamate peptidase inhibitor exert analgesia in bone cancer pain.
abstract: OBJECTIVE
  Not all bone cancer pain can be effectively treated with current therapies. In the present study, the effects of ip administration of alpha-2 agonists (dexmedetomidine and clonidine), N-methyl-D-aspartate (NMDA) antagonists (MK-801 and ketamine), an N-acetylaspartylglutamate peptidase inhibitor (ZJ-43), and morphine were examined in a mouse bone cancer pain model.
  
  
  METHODS
  A bone cancer pain model was produced by injection of murine sarcoma cells into the medullary cavity of the distal femur. To estimate the level of bone cancer pain, the number of pain-related behaviours induced by repeated applications of a von Frey monofilament (0.166 g) to the site of tumour cells implantation was counted. Drugs were administered two weeks after the implantation.
  
  
  RESULTS
  Morphine produced a significant analgesic effect (P < 0.001). The alpha-2 agonists produced analgesic effects (P < 0.001) with an efficacy similar to that of morphine, but only at doses that produced severe sedation. MK-801 had only limited analgesic effects, while ketamine produced an analgesic effect (P < 0.001) with the same efficacy as morphine. ZJ-43 (100 mg.kg(-1)) had a significant analgesic effect (P < 0.05) and the effect of ZJ-43 was antagonized by the selective group II metabotropic glutamate receptor (mGluR) antagonist.
  
  
  CONCLUSIONS
  These data suggest that alpha-2 agonists produce an analgesic effect only at a sedative dose and that ketamine, but not MK-801, is associated with an analgesic response without overt side effects. The effect of ZJ-43 is mediated by activating group II mGluRs.
authors.affiliation: Department of Anesthesiology, Graduate School of Medicine, Chiba University, 1-8-1 Inohana, Chiba-shi, Chiba, Japan.
authors.forename: Osamu
authors.initials: O
authors.lastname: Saito
authors.forename: Tomohiko
authors.initials: T
authors.lastname: Aoe
authors.forename: Alan
authors.initials: A
authors.lastname: Kozikowski
authors.forename: Jayaprakash
authors.initials: J
authors.lastname: Sarva
authors.forename: Joseph H
authors.initials: JH
authors.lastname: Neale
authors.forename: Tatsuo
authors.initials: T
authors.lastname: Yamamoto
mesh_terms: D000316:Adrenergic alpha-Agonists / Q000627:therapeutic use; D000698:Analgesia; D000818:Animals; D001859:Bone Neoplasms / Q000503:physiopathology*; D020927:Dexmedetomidine / Q000627:therapeutic use; D016291:Dizocilpine Maleate / Q000627:therapeutic use; D004305:Dose-Response Relationship, Drug; D007649:Ketamine / Q000627:therapeutic use*; D008297:Male; D051379:Mice; D008809:Mice, Inbred C3H; D009020:Morphine / Q000627:therapeutic use; D010148:Intractable Pain / Q000188:drug therapy*; D011480:Protease Inhibitors / Q000627:therapeutic use*; D014508:Urea / Q000031:analogs & derivatives* / Q000627:therapeutic use
chemical_list: D000316:Adrenergic alpha-Agonists; D011480:Protease Inhibitors; C486211:ZJ43; D020927:Dexmedetomidine; D007649:Ketamine; D016291:Dizocilpine Maleate; D009020:Morphine; D014508:Urea