ABSTRACT
A total of 100 neurons were recorded from the nucleus raphe magnus (NRM), of which 59 were identified as noxious-exaitation neurons; 30 as noxioes-inhibition neurons; 5 as non-noxious neurons; and 6 as non-responsive neurons Seventy neurons were further tested with electro-acupuncture (EA). 69.77% of the noxious-excitation neurons were excited and 68.42% of the noxious -inhibition neurons inhibited by EA. Stimulation of the periaqueductal gray (PAG) could activate the majority of the EA-response neurons. Systemic morphine could also affect the EA-response neurons through the following three patterns: excitation, inhibition and no-effect. No signilicant correlation between the response patterns of EA and morphine was found. The results indicate that the effect of NRM in EA and morphine analgesia is only partially overlapped.