国内外的工作表明中脑导水管周围灰质(Pariagueauctal grag

简称PAG)是与镇痛作用密切相关的神经结构

也是微量注射吗啡和电刺激可产生最有效镇痛作用的脑区。此部位阿片受体较为密集。朱丽霞等人认为PAG是针刺传入信号和伤害性刺The effects of stimulating periaqueductal gray (PAG) on the nociceptive neuron discharges of ponucleus evoked dy stimulating the splanchnic nerve in cats were studied. The two kinds of inhibitory action were observed. One was called early phase or prompt inhibition phase which occured within 30 ms to 150 ms after stimulation of PAG. The other was called slow-pase or sustained inhibition which occured from a few minutes to more than ten minutes after the stimulation of PAG. The results showed that PAG played an important role in the analgesia of visceral rain. Both kinds of inhibition may be blocked by naloxone

this suggests that endogencus opiate like substances involved in these inhibitory processes caused by stimulating role in the inhibitory effect of PAG.