电针足三里穴对脊髓背角内P物质致痛效应的影响

<正> 有关针刺镇痛原理的许多研究工作均已说明针刺穴位可激活机体的抗癌系统,释放有关递质参与痛觉的调制。那么,在针刺镇痛过程中,痛觉通路上的致癌物质受到何种影响?有何变化?对此了解较少。 P物质是初级传入神经末梢在脊髓背角释放的一种神经递质,有工作表明它主要分布于细的初级传入神经内,特别是C类纤维的末梢,因而它与伤害性感受可能有着密切的关系。为进一步研究针刺镇痛的脊髓机理,我们观察了电针足三里穴对脊髓背角内微电泳导入P物质产生的致痛效应的影响。

THE EFFECT OF ACUPUNCTURE "ZUSANLI" ON THE SP--EVORED NOCICEPTIVE RESPONSES OF DORSAL HORN NEURONS IN THE RAT

The effects of substance p (sp) microiontophoretically applied on spi- nal dorsal horn neurones were observed in 32 rats. Sp caused an increas in excitability for majority of the units affected by sp and a decreas only for a few units. The examination in receptive character of 25 units showed that 20 of 25 units can be excited by noxious mechanical stimulus or/and noxious heat or/and bradykinin applied and 18 of 20 units can also be excited by micro- iontophoretic sp. But the rest which were non-nociceptive units failed to respond to sp or were slightly inhibited by sp. The results support the po- int of view that sp acts as a neurotransmitter or modulater in spinal pain pathways. The excitatory effect of 15 of 17 units caused by sp was inhibited by electro-acupuncture stimulation at Zusanli points. 4 of 5 units tested for the effect of naloxone on the electro-acupuncture action showed that the i- nhibitory action of acupuncture stimulation on excitatory effect of sp fai- led to be blocked by microiontophoretic naloxone. It is suggested that the mechanism of acupuncture analgseia in spinal cord includs postsynaptic nhi- bition and endogenous opiate-like substance may not play an important role in the inhibitory mechanism.