Electroacupuncture-induced analgesia in a rat model of ankle sprain pain is mediated by spinal alpha-adrenoceptors
Language: 
English
Abstract: 

In a previous study, we showed that electroacupuncture (EA) applied to the SI-6 point on the contralateral forelimb produces long-lasting and powerful analgesia in pain caused by ankle sprain in a rat model. To investigate the underlying mechanism of EA analgesia, the present study tested the effects of various antagonists on known endogenous analgesic systems in this model. Ankle sprain was induced in anesthetized rats by overextending their right ankle with repeated forceful plantar flexion and inversion of the foot. When rats developed pain behaviors (a reduction in weight-bearing of the affected hind limb), EA was applied to the SI-6 point on the contralateral forelimb for 30 min under halothane anesthesia. EA significantly improved the weight-bearing capacity of the affected hind limb for 2h, suggesting an analgesic effect. The alpha-adrenoceptor antagonist phentolamine (2mg/kg, i.p. or 30 microg, i.t.) completely blocked the EA-induced analgesia, whereas naloxone (1mg/kg, i.p.) failed to block the effect. These results suggest that EA-induced analgesia is mediated by alpha-adrenoceptor mechanisms. Further experiments showed that intrathecal administration of yohimbine, an alpha(2)-adrenergic antagonist, reduced the EA-induced analgesia in a dose-dependent manner, whereas terazosin, an alpha(1)-adrenergic antagonist, did not produce any effect. These data suggest that the analgesic effect of EA in ankle sprain pain is, at least in part, mediated by spinal alpha(2)-adrenoceptor mechanisms.

Author(s): 
Koo, Sung Tae
Lim, Kyu Sang
Chung, Kyungsoon
Ju, Hyunsu
Chung, Jin Mo
Item Type: 
Journal Article
Publication Title: 
Pain
Journal Abbreviation: 
Pain
Publication Date: 
Mar 2008
Publication Year: 
2008
Pages: 
11-19
Volume: 
135
Issue: 
1-2
ISSN: 
1872-6623
DOI: 
10.1016/j.pain.2007.04.034
Library Catalog: 
NCBI Published Medical (?)
Extra: 
PMID: 17537577 PMCID: PMC2268107

Turabian/Chicago Citation

Sung Tae Koo, Kyu Sang Lim, Kyungsoon Chung, Hyunsu Ju and Jin Mo Chung. Mar 2008. "Electroacupuncture-induced analgesia in a rat model of ankle sprain pain is mediated by spinal alpha-adrenoceptors." Pain 135: 1-2: 11-19. 10.1016/j.pain.2007.04.034.

Wikipedia Citation

<ref> {{Cite journal | doi = 10.1016/j.pain.2007.04.034 | issn = 1872-6623 | volume = 135 | pages = 11-19 | last = Koo | first = Sung Tae | coauthors = Lim, Kyu Sang, Chung, Kyungsoon, Ju, Hyunsu, Chung, Jin Mo | title = Electroacupuncture-induced analgesia in a rat model of ankle sprain pain is mediated by spinal alpha-adrenoceptors | journal = Pain | date = Mar 2008 | pmid = | pmc = }} </ref>