Electroacupuncture reduces the evoked responses of the spinal dorsal horn neurons in ankle-sprained rats

Jae Hyo Kim, Hee Young Kim, Kyungsoon Chung, Jin Mo Chung

Research output: Contribution to journalArticle

13 Scopus citations

Abstract

Acupuncture is shown to be effective in producing analgesia in ankle sprain pain in humans and animals. To examine the underlying mechanisms of the acupuncture-induced analgesia, the effects of electroacupuncture (EA) on weight-bearing forces (WBR) of the affected foot and dorsal horn neuron activities were examined in a rat model of ankle sprain. Ankle sprain was induced manually by overextending ligaments of the left ankle in the rat. Dorsal horn neuron responses to ankle movements or compression were recorded from the lumbar spinal cord using an in vivo extracellular single unit recording setup 1 day after ankle sprain. EA was applied to the SI-6 acupoint on the right forelimb (contralateral to the sprained ankle) by trains of electrical pulses (10 Hz, 1-ms pulse width, 2-mA intensity) for 30 min. After EA, WBR of the sprained foot significantly recovered and dorsal horn neuron activities were significantly suppressed in ankle-sprained rats. However, EA produced no effect in normal rats. The inhibitory effect of EA on hyperactivities of dorsal horn neurons of ankle-sprained rats was blocked by the α-adrenoceptor antagonist phentolamine (5 mg/kg ip) but not by the opioid receptor antagonist naltrexone (10 mg/kg ip). These data suggest that EA-induced analgesia in ankle sprain pain is mediated mainly by suppressing dorsal horn neuron activities through α-adrenergic descending inhibitory systems at the spinal level.

Original languageEnglish (US)
Pages (from-to)2050-2057
Number of pages8
JournalJournal of neurophysiology
Volume105
Issue number5
DOIs
StatePublished - May 2011

Keywords

  • Acute ankle sprain
  • α-adrenergic descending inhibition

ASJC Scopus subject areas

  • Neuroscience(all)
  • Physiology

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