Analgesic effect of acupuncture applied to $SI_6$ in a rat model of neuropathic pain

흰쥐의 신경병증성(神經病症性) 통증(痛症) 모델에서 양로(養老) 자침(刺鍼)의 진통효과(鎭痛效果)

Objectives : The usage of acupuncture has gained popularity for certain chronic pain conditions. However, the efficacy of acupuncture in various diseases has not been fully established and the underlying mechanism is not clearly understood. In the present study, the effect of electroacupuncture (EA) applied to yangno$(SI_6)$ on the neuropathic pain was examined. Methods : A common source of persistent pain in human is a neuropathic pain. Neuropathic pain was induced by tight ligation of L5 spinal nerve. When rats developed pain behaviors, EA was applied for 30 min. under enflurane anesthesia with repeated train stimuli at the intensity of 10X of muscle twitch threshold. The foot withdraw latency of the hind limb was measured for an indicator of pain level after each manipulation. Results : EA increased the mechanical threshold of the foot in the rat model of neuropathic pain significantly for the duration of 1 hr. suggesting a partial alleviation of pain. EA applied to SI6 point produced a significant improvement of mechanical sensitivity of the foot lasting for at least 1 h. However, $ST_{36}$ point did not produce any significant increase of mechanical sensitivity. The improvement of mechanical threshold was interpreted as an analgesic effect. The analgesic effort was specific to the acupuncture point since the analgesic effect on the neuropathic pain model could not be mimicked by EA applied to a point, $ST_{36}$. In addition, this analgesic effect of EA is mediated by a adrenergic mechanism of descending control of spinal cord from the brain. Conclusions : The data suggest that EA produces a potent analgesic effect on the neuropathic pain model in the rat; and 2) that EA-induced analgesia is mediated by a adrenergic mechanism of descending control in a point specific manner.