BACKGROUND: The stimulation and selection of an effective acupoint is important for producing effective analgesia in electraoacupuncture. This study examined the effect of electroacupuncture to different acupoints and investigated the effective acupoint for ankle-sprained pain in rats.

METHODS: A Sprain was produced by manually overextending the lateral ligament of the right ankle in rats. Electrical stimulation was delivered individually to five acupoints: bilateral Yangno (SI6s), contralateral Zusanli (ST36), Hapko (LI4) and Sanyinjiao (SP6). The level of pain evoked by ankle sprain was measured by the stepping force of the sprained paw during walking at pre-sprain and 24 hrs after the sprain. The effect of electroacupuncture was evaluated by the % full recovery of the stepping force at 1, 2, 4 hr after terminating electroacupuncture.

RESULTS: Electrical stimulation to SI6 and ST36 among the five acupoints produced a significant increase in the % full recovery of the stepping force of the ankle-sprained paw during walking.

CONCLUSIONS: The effective acupoints for electroacupuncture on ankle-sprained pain in rats is SI6 and ST36. These points are relatively specific to ankle-sprain. It is important to select the appropriate acupoint for effective electroacupuncture-induced analgesia.