Relationship between electroacupuncture analgesia and descending pain inhibitory mechanism of nucleus raphe magnus

摘要: Raphe-spinal (R-S) neurons were identified in the nucleus raphe magnus (NRM). The conduction velocity of their axons was calculated to be about 15-60 m/sec. great majority R-S did not respond clearly non-noxious stimuli, such as brushing hair or lightly pressing skin, but they noxious stimuli (pricking clamping), with increases decreases firing rates. receptive fields responding very wide covering almost all body. responses stimulation excitatory (increasing rates), inhibitory (decreasing) and unresponsive type, we unexpectedly found 3 reversibly excitatory-inhibitory type neurons, rate being higher than that neurons. reversible also related background effects electroacupuncture (EA) on mainly increase rates, inhibit nociceptive responses. After transection DLF, could still activated by EA, post-inhibitory EA obviously reduced. It is suggested can activate NRM, a supraspinal area mediating negative feedback circuit modulating pain, thus inducing analgesia via descending inhibition.