The effect of clonidine pretreatment on epidural resiniferatoxin in a neuropathic pain rat model

Mi Geum Lee, Dong Kyu Lee, Billy K. Huh, Sang Sik Choi, Hee Zoo Kim, Byung Gun Lim, Hong Soon Kim, Yun Suk Choi, Won Seok Hur, Mi Kyoung Lee

    Research output: Contribution to journalArticlepeer-review

    4 Citations (Scopus)

    Abstract

    Resiniferatoxin (RTX) is an ultrapotent synthetic TRPV1 (transient receptor potential vanilloid subtype 1) agonist with significant initial transient hyperalgesia followed by a prolonged analgesic effect in response to thermal stimulus. Using a rat model of neuropathic pain, we evaluated the effect of pretreatment with clonidine-which has been shown to relieve intradermal capsaicin-induced hyperalgesia-on the initial hyperalgesic response and the thermal analgesic property of RTX. Thirty-six male rats were divided into 6 treatment groups (n=6 each):RTX 500ng, RTX 1μg, clonidine 20μg (Cl), Cl+RTX 500ng, Cl+RTX 1μg, or normal saline 20μL (control). We evaluated the short-term (180min) and long-term (20 days) analgesic effects of RTX after thermal stimulation and mechanical stimulation. RTX had significant initial transient hyperalgesia followed by a prolonged analgesic effect in response to the thermal stimulus, but the RTX 500ng and RTX 1μg groups showed no initial short-term thermal hyperalgesic responses when pretreated with clonidine. The Cl+RTX 1μg rats' behavior scores indicated that they were more calm and comfortable compared to the RTX 1μg rats. Even though we cannot precisely confirm that pretreatment with clonidine potentiates or adds to the analgesic effect of RTX, clonidine pretreatment with epidural RTX eliminated the initial RTX-associated hyperalgesic response and systemic toxicity in this neuropathic pain rat model.

    Original languageEnglish
    Pages (from-to)95-103
    Number of pages9
    JournalActa Medica Okayama
    Volume69
    Issue number2
    Publication statusPublished - 2015

    Keywords

    • Clonidine
    • Epidural administration
    • Resiniferatoxin
    • Spinal nerve ligation rat model
    • Thermal hyperalgesia

    ASJC Scopus subject areas

    • Biochemistry, Genetics and Molecular Biology(all)

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