[Inhibition in the spinal cord: a neuronal mechanism of hypalgesia produced by acupuncture (author's transl)].

Central nervous system mechanisms of nociception and pain were studied electrophysiologically in the spinal cord of cats. A great proportion of dorsal horn neurons respond to noxious skin stimuli, for instance to heating to 50 degrees C; such stimuli predominantly activate afferent C fibres. These spinal neurons participate in the transmission of nociceptive information to the brain. The heat-evoked discharges of dorsal horn neurons are effectively inhibited by repetitive electrical stimulation of large;, low-threshold cutaneous A fibres. The inhibition reaches its maximum effect after several minutes of nerve stimulation, and declines at a slow rate after the end of stimulation. This long-term suppression is considered to be a neuronal mechanism underlying hypalgesia produced in man e.g. by acupuncture and by transcutaneous nerve stimulation.