[Effects of intrathecal ouabain and tizanidine injection for treatment of neuropathic pain in rats].
OBJECTIVE
To investigate the effects of intrathecal ouabain and tizanidine injection for treatment of neuropathic pain in rats.


METHODS
Male SD rats weighing 250-300 g were randomly divided into 5 groups (n = 6), namely the control group, ouabain group, tizanidine group, combined ouabain and tizanidine injection group, and the antagonist group. Intrathecal catheter was implanted 7 days before spinal nerve ligation to establish the neuropathic pain model. Mechanical withdrawal threshold (MWT) before and after intrathecal administration of the agents was recorded in the rats. Isobolographic analysis was performed to evaluate the interactions between the agents.


RESULTS
Intrathecal injection of ouabain (0.25-5 microg) or tizanidine (0.5-5 microg) alone produced dose-dependent analgesic effect against the neuropathic pain (P < 0.05). Isobolographic analysis revealed a synergistic interaction between ouabain and tizanidine. Intrathecal pretreatment with atropine (5 microg) or yohimbine (20 microg) antagonized the effects of ouabain and tizanidine administered alone or in combination (P < 0.05).


CONCLUSIONS
Intathecal injection of ouabain or tizanidine produces dose-dependent analgesic effects against neuropathic pain, and their synergistic effect after combined injection probably involves the cholinergic transmission and alpha2 receptor.
Ou-Yang
Han-dong
HD
State Key Laboratory of Oncology in Southern China/Cancer Center, Sun Yat-sen University, Guangzhou 510060, China.
Zeng
Wei-an
WA
Li
Qiang
Q
He
Wei-xiong
WX
Wang
Pei-zong
PZ
Lin
Li-ling
LL
Zhang
Zhi-quan
ZQ
Liu
Xian-guo
XG
D000700:Analgesics / Q000008:administration & dosage; D000818:Animals; D003000:Clonidine / Q000008:administration & dosage / Q000031:analogs & derivatives*; D007278:Injections, Spinal; D010042:Ouabain / Q000008:administration & dosage*; D010146:Pain / Q000188:drug therapy*; D011897:Random Allocation; D051381:Rats; D017207:Rats, Sprague-Dawley; D013127:Spinal Nerves / Q000293:injuries
D000700:Analgesics; D010042:Ouabain; C023754:tizanidine; D003000:Clonidine