title: Analgesic effect of vitamin E is mediated by reducing central sensitization in neuropathic pain.
abstract: Recent studies suggest that reactive oxygen species (ROS) are critically involved in neuropathic pain. Although vitamin E is a well-known antioxidant, its efficacy on chronic pain is not known. This study investigated the efficacy and mechanisms of vitamin E analgesia in a rat model of neuropathic pain produced by spinal nerve ligation. The effects of vitamin E were investigated using behavioral testing, electrophysiological recording of dorsal horn neurons, and determinations of phosphorylated NMDA receptor subunit 1 (pNR1) levels in the spinal dorsal horn. Results showed that a systemic single injection of a high dose or repetitive daily injections of low doses of vitamin E significantly reduced neuropathic pain behaviors. Vitamin E was also effective in producing analgesia by intrathecal injection, suggesting the importance of spinal mechanisms. In spinal dorsal horn neurons, vitamin E reduced evoked responses to mechanical stimuli as well as the sizes of their receptive fields. In addition, levels of pNR1 in neuropathic rats were also reduced by vitamin E injection. These data suggest that vitamin E produces analgesia in neuropathic rats that is, at least in part, mediated by reducing central sensitization which, in turn, is induced by peripheral nerve injury.
authors.affiliation: Department of Neuroscience and Cell Biology, University of Texas Medical Branch, Galveston, TX 77555-1069, USA.
authors.forename: Hee Kee
authors.initials: HK
authors.lastname: Kim
authors.forename: Jae Hyo
authors.initials: JH
authors.lastname: Kim
authors.forename: Xiu
authors.initials: X
authors.lastname: Gao
authors.forename: Jun-Li
authors.initials: JL
authors.lastname: Zhou
authors.forename: Inhyung
authors.initials: I
authors.lastname: Lee
authors.forename: Kyungsoon
authors.initials: K
authors.lastname: Chung
authors.forename: Jin Mo
authors.initials: JM
authors.lastname: Chung
mesh_terms: D000700:Analgesics / Q000008:administration & dosage; D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects*; D005073:Evoked Potentials, Somatosensory / Q000187:drug effects*; D008297:Male; D009437:Neuralgia / Q000175:diagnosis / Q000188:drug therapy* / Q000503:physiopathology*; D017288:Pain Threshold / Q000187:drug effects*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013116:Spinal Cord / Q000187:drug effects* / Q000503:physiopathology*; D016896:Treatment Outcome; D014810:Vitamin E / Q000008:administration & dosage
chemical_list: D000700:Analgesics; D014810:Vitamin E