Effect of Acupuncture applied to Hand Yang Meridian on the Rat Model of Ankle Sprain Pain

수양경(手陽經) 경혈(經穴) 자침(刺鍼)이 백서(白鼠)의 족과 염좌(捻挫) 통증(痛症)에 미치는 영향(影響)

Objectives : In the present study, the effect of electroacupuncture (EA) applied to hand yang meridian on the ankle sprain model was examined. Methods & Results : A common source of persistent pain in humans is the lateral ankle sprain. To model this condition, the rat's right ankle was bent repeatedly, overextending lateral ligaments, for 4 min under halothane anesthesia. The rat subsequently showed swelling of the ankle and a reduced stepping force of the affected limb for the next several days. The reduced stepping force of the limb was presumably due to a painful ankle. EA was applied to the several acupuncture point on the contralateral forelimb for 30 min under gaseous anesthesia. After the termination of EA, behavioral tests measuring stepping force were periodically conducted during the next 4 h. EA applied to SI-6 point produced a significant improvement of stepping force of the sprained foot lasting for at least 2 h. However, neigher LI-4 point nor TE-3 point produced any significant increase of weight bearing force. The improvement of stepping pressure was interpreted as an analgesic effect. The analgesic effect was specific to the acupuncture point since the analgesic effect on the ankle sprain pain model could not be mimicked by EA applied to a nearby point, LI-4 or TE-3. The analgesic effect of EA applied to SI-6 was more powerful when EA was applied by low-frequency and high-intensity stimulation. In addition, this effect need to be stimulated more than 15 min. Conclusions : These data suggest that EA produces a potent analgesic effect on the ankle sprain pain model in the rat. This analgesic effect is produced by applying EA to a Tae-Yang meridian at opposite side from the painful area in a stimulus point-specific way.