Objective: To observe and compare the ameliorate effects of electroacupuncture (EA) and transcutaneous electrical acupoint stimulation (TEAS) with different intensities on inflammatory muscle pain, so as to confirm the role of different afferent nerve fibers in different layers (skin or muscle) in pain relief of acupuncture.
Methods: The intensities of the thresholds of A (Ta) and C (Tc) were selected for TEAS and EA. TEAS and EA were applied on the layer of skin and muscle of "Liangqiu" (ST34), respectively. Forty-eight rats were randomly divided into control, model, TEAS-Ta, TEAS-Tc, EA-Ta and EA-Tc groups (n=8 in each group). The inflammatory muscle pain model was established by complete Freund's adjuvant (CFA) injection into the right biceps femoris muscle. EA or TEAS was applied once a day for 3 days. The weight difference between the hind limbs and the abnormal electromyography (EMG) activities were observed as an index for pain of the rats.
Results: After modeling, the weight difference between the hind limbs was increased markedly in the model group relevant to the control group (P<0.01). Compared with the model group, the weight difference between the hind limbs in the TEAS-Tc, EA-Ta, and EA-Tc groups was significantly decreased (P<0.05, P<0.01). Compared with that before intervention, the area under the curve and discharge frequency of abnormal EMG of rats in the TEAS-Tc and EA-Ta groups were significantly reduced after intervention (P<0.01, P<0.05), while those in the EA-Tc group were significantly increased (P<0.05). After the intervention, compared with the TEAS-Ta group, the inhibition rate of the area under the curve and the discharge frequency of the abnormal EMG in the TEAS-Tc group increased significantly (P＜0.05); and those were also increased in the EA-Ta group when compared with the EA-Tc group (P<0.01).
Conclusion: TEAS with Tc or EA with Ta in the muscle layer can alleviate the pain and inhibit the abnormal EMG in inflammatory muscle pain rats. It is indicated that local pain relief by acupuncture was related to the afferent nerve fiber in different layer with different intensities.
目的：观察比较不同强度的电针(EA)和经皮穴位电刺激(TEAS)对肌肉炎性痛模型大鼠的镇痛作用，探讨刺激穴位不同层次结构激活不同传入神经纤维在针刺镇痛中的作用。方法：将刺激强度分为激活A纤维阈值(Ta)或者激活C纤维阈值(Tc)，刺激层次采用TEAS或电针“梁丘”(达肌肉层)。将SD大鼠随机分为正常组、模型组、Ta强度经皮穴位电刺激(TEAS-Ta)组、Tc强度经皮穴位电刺激(TEAS-Tc)组、Ta强度电针(EA-Ta)组、Tc强度电针(EA-Tc)组，每组8只。以SD大鼠右侧股二头肌注射完全弗氏佐剂建立肌肉炎性痛模型。4个干预组以相应刺激强度于“梁丘”给予TEAS或电针干预，每日干预1次，共干预3 d。以大鼠双足承重差值和异常肌电发放作为疼痛检测指标，观察不同强度和层次干预局部穴位“梁丘”的镇痛作用。结果：与正常组比较，模型组大鼠双足承重差值明显升高(P<0.01)；与模型组比较，TEAS-Tc组、EA-Ta组、EA-Tc组双足承重差值显著降低(P<0.05，P<0.01)。与本组干预前比较，TEAS-Tc组、EA-Ta组干预后大鼠异常肌电的曲线下面积、放电频率显著降低(P<0.01，P<0.05)，EA-Tc组显著升高(P<0.05)。干预后与TEAS-Ta组比较，TEAS-Tc组异常肌电的曲线下面积抑制率、放电频率抑制率显著升高(P<0.05)；与EA-Tc组比较，EA-Ta组异常肌电的曲线下面积抑制率、放电频率抑制率显著升高(P<0.01)。结论：Tc强度的TEAS和Ta强度的肌肉层电针梁丘穴均可以减轻CFA炎性痛模型大鼠疼痛行为和异常肌电发放，说明局部镇痛的效果和穴位局部的层次和神经传入密切相关。.
Keywords: Electroacupuncture; Electromyography; Inflammatory muscle pain; Transcutaneous electrical acupoint stimulation.