Electroacupuncture suppresses capsaicin-induced secondary hyperalgesia through an endogenous spinal opioid mechanism

Hee Young Kim, Jigong Wang, Inhyung Lee, Hee Kee Kim, Kyungsoon Chung, Jin Chung

Research output: Contribution to journalArticle

36 Citations (Scopus)

Abstract

Central sensitization, caused either by tissue inflammation or peripheral nerve injury, plays an important role in persistent pain. An animal model of capsaicin-induced pain has well-defined peripheral and central sensitization components, thus is useful for studying the analgesic effect on two separate components. The focus of this study is to examine the analgesic effects of electroacupuncture (EA) on capsaicin-induced secondary hyperalgesia, which represents central sensitization. Capsaicin (0.1%, 20 μl) was injected into the plantar side of the left hind paw, and foot withdrawal thresholds in response to von Frey stimuli (mechanical sensitivity) were determined for both primary and secondary hyperalgesia in rats. EA (2 Hz, 3 mA) was applied to various pairs of acupoints, GB30-GB34, BL40-BL60, GV2-GV6, LI3-LI6 and SI3-TE8, for 30 min under isoflurane anesthesia and then the effect of EA on mechanical sensitivity of paw was determined. EA applied to the ipsilateral SI3-TE8, but to none of the other acupoints, significantly reduced capsaicin-induced secondary hyperalgesia but not primary hyperalgesia. EA analgesic effect was inhibited by a systemic non-specific opioid receptor (OR) antagonist or an intrathecal μ- or δ-OR antagonist. EA analgesic effect was not affected by an intrathecal κ-OR antagonist or systemic adrenergic receptor antagonist. This study demonstrates that EA produces a stimulation point-specific analgesic effect on capsaicin-induced secondary hyperalgesia (central sensitization), mediated by activating endogenous spinal μ- and δ-opioid receptors.

Original languageEnglish (US)
Pages (from-to)332-340
Number of pages9
JournalPain
Volume145
Issue number3
DOIs
StatePublished - Oct 2009

Fingerprint

Electroacupuncture
Capsaicin
Hyperalgesia
Opioid Analgesics
Central Nervous System Sensitization
Analgesics
Narcotic Antagonists
Acupuncture Points
Pain
Peripheral Nerve Injuries
Adrenergic Antagonists
Isoflurane
Opioid Receptors
Foot
Anesthesia
Animal Models
Inflammation

Keywords

  • Capsaicin
  • Electroacupuncture
  • Hyperalgesia
  • Opioid

ASJC Scopus subject areas

  • Clinical Neurology
  • Anesthesiology and Pain Medicine
  • Neurology
  • Pharmacology

Cite this

Electroacupuncture suppresses capsaicin-induced secondary hyperalgesia through an endogenous spinal opioid mechanism. / Kim, Hee Young; Wang, Jigong; Lee, Inhyung; Kim, Hee Kee; Chung, Kyungsoon; Chung, Jin.

In: Pain, Vol. 145, No. 3, 10.2009, p. 332-340.

Research output: Contribution to journalArticle

Kim, Hee Young ; Wang, Jigong ; Lee, Inhyung ; Kim, Hee Kee ; Chung, Kyungsoon ; Chung, Jin. / Electroacupuncture suppresses capsaicin-induced secondary hyperalgesia through an endogenous spinal opioid mechanism. In: Pain. 2009 ; Vol. 145, No. 3. pp. 332-340.
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