孤束核参与刺激下丘脑室旁核的镇痛作用

本实验用电刺激鼠尾-嘶叫法测痛,观察电刺激下丘脑室旁核的镇痛效应,并采用核团损毁和核团内微量注射药物等方法分析其镇痛通路。实验结果如下:(1)电刺激下丘脑室旁核能产生明显的镇痛效应。同时,放射免疫测定发现脑干加压素含量升高。(2)损毁孤束核能取消刺激下丘脑室旁核的镇痛效应,但对基础痛阈无影响。(3)孤束核内微量注射加压素拮抗剂d(CH_2)_5 TYr(Me)-AVP]60ng/0.6μl 和加压素抗血清0.6μl 都可明显对抗刺激下丘脑室旁核的镇痛效应。(4)直接在孤束核内微量注射加压素60ng/0.6μl,能模拟刺激下丘脑室旁核的镇痛效应。实验结果表明:电刺激下丘脑室旁核能产生镇痛效应,其机理之一可能是兴奋了下丘脑室旁核中加压素能神经元胞体,后者通过下行投射纤维在孤束核中释放加压素,影响孤束核神经元的活动,从而产生镇痛。

INVOLVEMENT OF SOLITARY TRACT NUCLEUS IN ANAL GESIC EFFECT PRODUCED BY PARAVENTRICULAR NUCLEUS STIMULATION

This study was undertaken to evaluate the analgesic effect of paraventricu-lar nucleus(PVN)stimulation with tail stimulation-vocalization test.The mecha-nism of this analgesia was analysed with nuclear lesion and microinjection tech-nique.The main results were as follows:(1)Electrical stimulation of the PVN could significantly enhance the painthreshold and increase the content of AVP in brainstem measured by radioimmu-noassay.(2)Solitary tract nucleus(STN)lesion could eliminate the analgesic effectinduced by PVN stimulation.(3)Intranuclear microinjection of AVP-antagonist and AVP-antiserum intothe STN could block the analgesic effect of PVN stimulation.(4)Intranuclear microinjection of AVP into the STN could mimick theanalgesic effect similar to that of PVN stimulation.These results suggest that electrical stimulation of the PVN could produce ananalgesic effect.This effect might be mediated by the activation of VP-ergic neu-rons in PVN and upon releasing VP from the descending fibers,the activities of neu-rons in the STN are influenced.