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A minimal stress model for the assessment of electroacupuncture analgesia in rats under halothane
Author(s) -
Wen YeongRay,
Yeh GengChang,
Shyu BaiChuang,
Ling QingDong,
Wang KuoChing,
Chen TaLiang,
Sun WeiZen
Publication year - 2007
Publication title -
european journal of pain
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.305
H-Index - 109
eISSN - 1532-2149
pISSN - 1090-3801
DOI - 10.1016/j.ejpain.2006.11.003
Subject(s) - halothane , electroacupuncture , medicine , anesthesia , (+) naloxone , hyperalgesia , stimulation , morphine , analgesic , threshold of pain , anesthetic , nociception , acupuncture , opioid , alternative medicine , receptor , pathology
The use of anesthetics in acupuncture analgesia is controversial. We evaluate a steady‐state light anesthesia model to test whether minimal stress manipulation and reliable measurement of analgesia could be simultaneously achieved during electroacupuncture (EA) in animals. A series of experiments were performed. Firstly, EA compliance and tail‐flick latencies (TFL) were compared in rats under 0.1%, 0.3%, 0.5%, 0.7%, or 1.1% halothane for 120min. Under 0.5% halothane, TFL were then measured in groups receiving EA at intensity of 3, 10 or 20 volt (V), 1 or 2mg/kg morphine, 20V EA plus naloxone, or control. Subsequently, the effect of EA on formalin‐induced hyperalgesia was tested and c‐ fos expression in the spinal dorsal horn was analyzed. Rats exhibited profound irritable behaviors and highly variable TFL under 0.1% or 0.3% halothane, as well as a time‐dependent increase of TFL under 0.7% or 1.1% halothane. TFL remained constant at 0.5% halothane, and needle insertion and electrical stimulation were well tolerated. Under 0.5% halothane, EA increased TFL and suppressed formalin‐induced hyperalgesia in an intensity‐dependent and naloxone‐reversible manner. EA of 20V prolonged TFL by 74%, suppressed formalin‐induced hyperalgesia by 32.6% and decreased c‐ fos expression by 29.7% at the superficial and deep dorsal horn with statistically significant difference. In conclusion, 0.5% halothane provides a steady‐state anesthetic level which enables the humane application of EA stimulus with the least interference on analgesic assessment. This condition serves as a minimal stress EA model in animals devoid of stress‐induced analgesia while maintaining physiological and biochemical response in the experiment.