人们在临床实践中体验到

在同一穴位上运用不同的针刺手法可产生不同的治疗效果。这一现象愈来愈引起针灸原理研究工作者的兴趣。近二十年来针刺镇痛原理的研究日益深入

业已证明

电针刺激可使中枢神经系统释放阿片肽产生镇痛作用。但阿片颉颃剂纳洛酮阻断大鼠电针镇痛的程度和所需的剂量与电针频率密切相Male rabbits of 2 0-2.6kg were used. nociception was assessed by measuringthe latency of the escape response (ERL) elicited by strong radiant heat focused on the skin of the nostrils or on the tail. Electroacupunctre (EA) stimulationwas applied via acupuncture needles inserted into the acupoint Zusanli andQuenlun

located near the knee joint and ankle joint respectively

A 50% increasein ERL at the end of 10 min EA stimulation was considered as positive responsein EA analgesia. The effectivenese of EA analgesia was determined usingEA of different frequencies

ranging from 2

2—15

15

30

up to 60 and 100Hz with the intensify of EA being fixed at 2 volts (2.24±0.11mA). Thepercentage of responders was highest in 2-15 Hz EA (70%)

followed by 15Hz≥2 Hz>30Hz

whereas 60 and 100 Hz EA were practically ineffective(responders only 12--13%). The rate of responders as determined by nociceptivetest applie on the head showed no significant difference with those applied onthe tall

indicating that the analgesic effect is generalized rather than segmental.The vulnerability of EA analgesia to naloxone blockade depends on the frequencyof EA being used. The analgesic effect of 2 Hz & 2-15 Hz EA could be blockedby a small dosc (1mg/kg) of naloxone

that of 15 Hz EA by a higher dose(5mg/kg)

whereas the effect of 30 Hz HA could not be blocked even by 10mg/kg of naloxone. The results suggest that low frequency (2 Hz

2-15 Hz) EAanalgesia is mediated predominantly

and 15 Hz EA analgesia partly

by opioidmechanisms

whereas higher frequency (30 Hz or more) EA analgesia seems tobe mediated by non-opioid mechanisms.