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 Mo Chung

    Research output: Contribution to journalArticle

    39 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 1 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 Mo.

    In: Pain, Vol. 145, No. 3, 01.10.2009, p. 332-340.

    Research output: Contribution to journalArticle

    Kim, Hee Young ; Wang, Jigong ; Lee, Inhyung ; Kim, Hee Kee ; Chung, Kyungsoon ; Chung, Jin Mo. / 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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