title: Antinociceptive effects of intraperitoneal and intrathecal vitamin e in the rat formalin test.
abstract: BACKGROUND
  Vitamin E is widely known to be one of the reactive oxygen species (ROS) scavengers and a drug that can easily be obtained, and it has been shown to attenuate the pain responses induced by various causes in animal pain models. Thus, this experiment was conducted to assess the antinociceptive effects of vitamin E by comparing intraperitoneal and intrathecal injections in rats subjected to the formalin test.
  
  
  METHODS
  AFTER THE INTRAPERITONEAL AND INTRATHECAL INJECTIONS OF VITAMIN E WERE CARRIED OUT, RESPECTIVELY (IP: 500 mg/kg, 1 g/kg, and 2 g/kg, IT: 3 mg/kg, 10 mg/kg, and 30 mg/kg), the formalin test was perfumed. As soon as 5% formalin was injected into left hind paw, the number of flinches induced by pain was measured at 5-minute intervals for 1 hour.
  
  
  RESULTS
  Formalin injected into the left hind paw induced biphasic nociceptive behavior in all animals. Intraperitoneal injection of vitamin E diminished the nociceptive behavior in a dose-dependent manner during the early and late phase. Intrathecal vitamin E diminished nociceptive behavior dose dependently during the late phase but showed no significant difference in the early phase.
  
  
  CONCLUSIONS
  Vitamin E attenuated acute nociception when it was injected systemically, while both systemic and intrathecal injection produced analgesia in a rat model of formalin-induced hyperalgesia.
authors.affiliation: Department of Anesthesiology and Pain Medicine, Chungnam National University Hospital, Daejeon, Korea.
authors.forename: Myoung Joong
authors.initials: MJ
authors.lastname: Kim
authors.forename: Boo Hwi
authors.initials: BH
authors.lastname: Hong
authors.forename: En Ji
authors.initials: EJ
authors.lastname: Zhang
authors.forename: Young Kwon
authors.initials: YK
authors.lastname: Ko
authors.forename: Won Hyung
authors.initials: WH
authors.lastname: Lee
keywords: formalin test; intraperitoneal; intrathecal; vitamin E