Analgesic effect of vitamin E is mediated by reducing central sensitization in neuropathic pain.
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.
Kim
Hee Kee
HK
Department of Neuroscience and Cell Biology, University of Texas Medical Branch, Galveston, TX 77555-1069, USA.
Kim
Jae Hyo
JH
Gao
Xiu
X
Zhou
Jun-Li
JL
Lee
Inhyung
I
Chung
Kyungsoon
K
Chung
Jin Mo
JM
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
D000700:Analgesics; D014810:Vitamin E