Antinociception of heterotopic electro-acupuncture mediated by the dorsolateral funiculus.
We investigated the inhibitory pathways that mediate the antinociceptive effects of heterotopic electro-acupuncture (EA) on formalin injection-induced pain in rats. EA (2 ms, 10 Hz, 3 mA) was delivered to heterotopic acupoints HT(7) and PC(7) for 30 min; this was followed immediately by subcutaneous injection of formalin into the left hind paw of rats. Naltrexone (10 mg/kg, i.p.), an opioid receptor antagonist, was administered to evaluate the involvement of endogenous opioids. The dorsolateral funiculus (DLF), which is a descending pathway that inhibits pain, was transected at the ipsilateral T10-11 level of the thoracic spinal cord. EA inhibited behavioral responses to formalin injection-induced pain and prevented the pain-induced increase in cFos expression in the lumbar spinal cord. Pretreatment with naltrexone did not inhibit the antinociceptive effects of EA on formalin injection-induced pain. Transection of the DLF ipsilateral to the acupuncture site eliminated the antinociceptive effects of EA. These results suggest that the antinociceptive effects of heterotopic EA are mediated by the DLF and not by endogenous opioids.
Lee
Seung Jae
SJ
The Institute of New Life Health Center, Boston, USA.
Lyu
Yeoung Su
YS
Kang
Hyung Won
HW
Sohn
In Churl
IC
Koo
Sungtae
S
Kim
Min Sun
MS
Park
Byung Rim
BR
Song
Jeong Hoon
JH
Kim
Jae Hyo
JH
D015669:Acupuncture Points; D000818:Animals; D001522:Behavior, Animal; D015671:Electroacupuncture; D005557:Formaldehyde / Q000494:pharmacology; D007279:Injections, Subcutaneous; D008297:Male; D009271:Naltrexone / Q000494:pharmacology; D009292:Narcotic Antagonists / Q000494:pharmacology; D009474:Neurons / Q000378:metabolism; D010146:Pain / Q000139:chemically induced / Q000517:prevention & control*; D016760:Proto-Oncogene Proteins c-fos / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D013116:Spinal Cord / Q000502:physiology* / Q000601:surgery
D009292:Narcotic Antagonists; D016760:Proto-Oncogene Proteins c-fos; D005557:Formaldehyde; D009271:Naltrexone