Antinociceptive effects of heterotopic electroacupuncture in formalin-induced pain.
This study examined the antinociceptive effect of electroacupuncture (EA) to heterotopic acupoints on formalin-induced pain in rats. EA (2 ms, 10 Hz, and 3 mA) was delivered to heterotopic acupoints HE(7) and PE(7), or non-acupoints at the right fore limb, for 30 min and was immediately followed by subcutaneous formalin injection into the left hind paw, respectively. The quantified pain score, electromyogram (EMG) response of the C-fiber reflex, and cFos immunoreactivity were assessed, respectively. EA to heterotopic acupoints significantly reduced both early- and late-phase pain-like behaviors and significantly decreased the EMG responses of the C-fiber reflex after formalin injection. By contrast, EA to non-acupoints had no significant effects on pain-like behavior or the EMG response. In addition, EA to heterotopic acupoints decreased cFos immunoreactivity in the lumbar spinal dorsal horn. Therefore, EA induced pre-emptive antinociception via the extra-segmental inhibition of the formalin-induced pain, suggesting that EA to heterotopic acupoints is a useful treatment for inflammatory pain.
Kim
Jae Hyo
JH
Department of Meridian and Acupoints, Wonkwang University College of Oriental Medicine, Iksan 570-749, Korea. medicdog@wonkwang.ac.kr
Gwak
Young Seob
YS
Lee
Inhyung
I
Sohn
In Churl
IC
Kim
Min Sun
MS
Choi
Dong Ok
DO
Baek
Dae Bong
DB
Park
Byung Rim
BR
D015667:Acupuncture Analgesia / Q000379:methods*; D000704:Analysis of Variance; D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects; D004558:Electric Stimulation; D015671:Electroacupuncture / Q000379:methods*; D004576:Electromyography; D005557:Formaldehyde; D007150:Immunohistochemistry; D008297:Male; D010146:Pain / Q000139:chemically induced / Q000503:physiopathology; D059408:Pain Management; D010147:Pain Measurement / Q000379:methods; D020671:Posterior Horn Cells / Q000737:chemistry; D016760:Proto-Oncogene Proteins c-fos / Q000032:analysis; D011897:Random Allocation; D051381:Rats; D017207:Rats, Sprague-Dawley
D016760:Proto-Oncogene Proteins c-fos; D005557:Formaldehyde