100Hz电针和脊髓鞘内注射强啡肽A引起大鼠镇痛作用的性别差异

目的：比较１００Ｈｚ电针对雌性与雄性大鼠的镇痛作用，以及脊髓蛛网膜下腔（ｉ．ｔ．）注射阿片κ受体激动剂强啡肽Ａ１１７（ＤｙｎＡ）对雌、雄大鼠镇痛的差异性。方法：用辐射热甩尾法测痛。为避免强啡肽的致瘫作用，本实验采用小剂量（５μｇ或２．３ｎｍｏｌ，１０μｌ）ｉ．ｔ．注射，并以斜板试验观察大鼠运动功能的变化。结果：雌性大鼠１００Ｈｚ电针的镇痛作用强于雄性大鼠，这种差异以电针２０ｍｉｎ时最为显著。ｉ．ｔ．注射ＤｙｎＡ２．３ｎｍｏｌ后１０ｍｉｎ雌鼠有镇痛作用，而雄鼠在给药后６０ｍｉｎ内均未表现镇痛作用。结论：１００Ｈｚ电针对雌性大鼠的镇痛作用强于雄性，这种性别差异可能与脊髓水平强啡肽镇痛的性别差异有关。

SEX DIFFERENCES OF ANALGESIA INDUCED BY 100Hz ELECTROACUPUNCTURE AND INTRATHECAL INJECTION OF DYNORPHIN A IN RATS

Aim: To assess whether there is a sex difference in 100 Hz electroacupuncture induced analgesia (EAA) and the analgesic effect elicited by intrathecal (i.t.) injection of the kappa agonist dynorphin A (117) in rats. Method: The tailflick latency (TFL) induced by radiant heat was used to measure the pain threshold. Dyn A was injected at a small dose of 2.3nmol(5 g)in 10 l to avoid possible paralytic effect, and the motor function was monitored by the angle change of inclined plane test. Results: Female rats presented greater analgesic effects than male rats after 100Hz EA for 20min. It was in female rats but not the male ones that i.t. injection of 5g Dyn A produced significant analgesic effects without motor dysfunction. Conclusion: Female rats show much stronger analgesic effect in response to 100 Hz EA and to i.t. injection of dynorphin A (117)as compared to male rats. A possible relation between sex difference toward 100Hz EA analgesia and spinal dynorphin A induced analgesia is suggested.