Response of raphe magnus neurons after acupuncture stimulation in rat.

Extracellular recording was made from single cells in the nucleus raphe magnus (NRM) of Wistar albino rats. The spontaneous firing rate of these cells increased, decreased or was not altered after acupuncture stimulation. Excitatory response of the cells was obtained more often than the other ones. There were no significant differences between the effects induced by stimulation of meridian and nonmeridian points. It is suggested that only the excited neuron may participate directly in the descending analgesic system through NRM cells activated by acupuncture stimulation. Presumably, meridian point is not a specific one for activation of NRM cells in rat.