微电泳导入纳洛酮对中缝大核刺激抑制脊髓背角神经元伤害性反应的影响

<正> 全身注射纳洛酮可阻断电针镇痛作用,说明内源性吗啡样物质参与针刺镇痛,进而我们又在脊髓背角伤害感受神经元胞体附近微电泳导入纳洛酮可以明显阻断电针对脊髓背角伤害性反应的抑制效应,进一步说明脊髓水平脑啡肽参与电针阻抑痛信息的传递。脊髓是外周各种传入冲动进入中枢的第一站,在此初步加工过程中,受着来自脊上水平的下行性调控。以往工作毁损中缝大核(NRM)可减弱针刺镇痛效应,电针穴位可激活中缝大核,电刺激模拟激活可产生与针刺穴位相似的明显镇痛效应,而此效应可被全身注射纳洛酮所阻断说明5-HT能下

THE EFFECT OF NALOXONE ON NRM STIMULATION PRODUCED INHIBITION ON NOCICEPTIVE RESPONSE IN SPINAL CORD

In present study the effect of iontophoretically applied naloxone on nucleus raphe magnus (NRM) stimulation produced inhibition on nocicep- tive response in spinal cord was observed for further investigating the mechanism of serotoninergic descending inhibitory pathway in blocking transmission of nociceptive informetion. Experiments were performed on 35 adult cats immobilized with galla- mine. The unit activity was extracellularly recorded and its response to saphenous stimulation was obsered. Both nociceptive and non-nociceptive response in spinal cord were in- hibited by stimulation of NRM (including nucleus reticular magnocellu- laris), however the former was far more inhibited than the later(P< 0.001). The NRM stimulation produced inhibition on nociceptive response was significantly(P<0.01)blocked by pre-treatment with iontophoretic nalo- xone, but it was slightly (P>0.05) blocked by iontophoretic methyser- gide. It was similar to the acupuncture effect which was also blocked by iontophoretic naloxone. These results suggest that endogenous opiate-like substance may play an important role in NRM stimulation producing inhibition on nociceptive response in spinal cord. It might be considered as an important mechanism in acupuncture analgesia. As the role of serotonin was uncertain, it re- mains to be studied.