电针引起脊髓P物质释放的频率依赖性

我室以往的研究表明，不同频率的电针可引起脊髓释放不同种类的阿片肽。本工作观察Ｐ物质（ＳＰ）释放的频率依赖性，电针频率选择２，４，８，１５，３０和１００Ｈｚ，分别收集电针期间及电针前后各３０ｍｉｎ的脊髓灌流液，通过放射免疫方法测定大鼠电针有效组和电针无效组Ｐ物质免疫活性（ＳＰ－ｉｒ）．结果如下：（１）电针有效组：２Ｈｚ引起ＳＰ－ｉｒ降低，与电针前相比，Ｐ＜０．０１；４Ｈｚ电针前后ＳＰ－ｉｒ比较，无统计学意义；８，１５，３０，１００Ｈｚ时ＳＰ－ｉｒ均增加（Ｐ＜０．０１），其中１５Ｈｚ时ＳＰ增加最多（Ｐ＜０．００１），表明刺激引起ＳＰ释放有频率依赖性。（２）电针无效组：不论应用何种频率，电针前后脊髓灌流液中ＳＰ－ｉｒ变化不大（均Ｐ＞０．０５）。提示，电针时脊髓液中ＳＰ含量变化与镇痛效果有密切关系。

FREQUENCY DEPENDENCE OF SUBSTANCE P RELEASE BY ELECTROACUPUNCTURE IN RAT SPINAL CORD

Previous studies in our laboratory have shown that electroacupuncture (EA) usingdifferent frequencies produced differential opioid peptides release in the spinal cord ofrats and human beings. In the present study we observed the frequency dependence ofsubstance P (SP) release from rat spinal cord, with the frequencies of EA set at 2, 4,8, 15, 30 and 100 Hz. The spinal perfusate was collected in 3 periods of 30 min before, during and after EA, and the immunoreactive SP (SP-ir) was measured by radioimmunoassay (RIA). The effectiveness of EA-induced analgesia was assessed bytail flick latency (TFL). Rats showing an increase of TFL over 40% was considered asEA responder. The results showed that in the responders, SP-ir in spinal perfusateshowed a moderate decrease during 2 Hz EA, (P<0. 01 compared with baselinelevel), no change in the 4 Hz EA group, and a marked increase during 8, 15, 30 and100 Hz EA (P<0. 01 ), with maximal increase occurring at 15 Hz (P<0. 001 ). Theabove results sugged that EA may induce upward or downward modulation in SP-ir release depending on the frequency of EA. However in the non-responder rats no changein spinal fluid SP-ir content was observed. This suggests that changes in SP-ir releasehave same causal relation with the analgesia induced by EA stimulation.