中缝大核内催产素在电针镇痛中的作用

目的 :探讨中缝大核 (NRM )内催产素 (OT)在电针镇痛中的作用 ,及其和内源性 5 HT在电针镇痛中的关系。方法 :以钾离子透入法引起大鼠甩尾反应的电流强度为痛行为反应指标 ,测定动物痛阈 ,观察NRM内注射催产素和噻庚啶对电针镇痛的影响。结果 :向大鼠NRM内微量注入催产素后 ,能明显增加电针镇痛的效应 ;而向NRM内注入噻庚啶后 ,可阻断催产素增加电针镇痛的效应。结论 :NRM内的催产素在电针镇痛的复杂过程中发挥着一定作用 ,且其效应可能是通过内源性 5 HT系统中介的。

Effect of Oxytocin in the Nucleus Raphe Magnus on Electroacupuncture Analgesia in Rats

Objective:To study the effect of oxytocin(OT)in nucleus raphe magnus (NRM) on electroacupuncture (EA) analgesia and its correlation with the endogenous 5-HT. Methods: In the first part of the study, 24 Wistar rats were randomly divided into normal saline group (n=8), OT group (n=6), normal saline (NS)+EA group (n=6) and OT+EA group (n=6) for observing the effect of injection of OT (4 ng) into NRM on EA analgesia. In the second part of the study, 18 Wistar rats were randomized into NS+EA, Cyproheptadin (C, an antagonist of 5-HT receptors) +NS+EA and C+OT+EA groups for analyzing the effect of injection of C (10 μg) into NRM on EA analgesia. The potassium iontophoresis induced tail-flick was used to measure the pain threshold. Results: Following administration of OT into NRM, EA and OT+EA,and during EA and after cease of EA, the percentages of the increased pain threshold were considerably higher than those of NS group. There were significant differences between OT and NS groups and between NS+EA and OT+EA groups (P< 0.01), showing that microinjection of OT in NRM can induce an enhancement of EA analgesia. Following administration of C in NRM, the percentages of the increased pain threshold of C+NS+EA and C+OT+EA groups were strikingly lower than those of NS+EA group, displaying that after administration of antagonist of 5-HT receptors, the effect of EA analgesia is weakened pronouncedly.Conclusion: OT in NRM is involved in EA analgesia, that is probably accomplished partially by endogenous 5-HT.