TY - JOUR
T1 - Analgesic effect of vitamin E is mediated by reducing central sensitization in neuropathic pain
AU - Kim, Hee Kee
AU - Kim, Jae Hyo
AU - Gao, Xiu
AU - Zhou, Jun Li
AU - Lee, Inhyung
AU - Chung, Kyungsoon
AU - Chung, Jin Mo
N1 - Funding Information:
This work was supported by NIH Grants NS 31680, NS 11255, and AT 01474, and a Research Development Grant from the Sealy Memorial Endowment Fund (2547-03). The authors sincerely thank Denise Broker for her excellent service in English editing.
PY - 2006/5
Y1 - 2006/5
N2 - 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.
AB - 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.
KW - Analgesia
KW - Antioxidant
KW - Free radical scavenger
KW - Mechanical allodynia
KW - ROS
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U2 - 10.1016/j.pain.2006.01.013
DO - 10.1016/j.pain.2006.01.013
M3 - Article
C2 - 16524661
AN - SCOPUS:33646042205
SN - 0304-3959
VL - 122
SP - 53
EP - 62
JO - Pain
JF - Pain
IS - 1-2
ER -