Peripheral and Central Mechanisms Underlying Acupuncture-induced Antinociceptive Effects

Kazuo Toda
Department of Physiology, Faculty of Dentistry, Tokyo Medical and Dental University, Bunkyo-ku, 113-8549, Japan

Acupuncture stimulation evokes powerful analgesic effects in various species of animals and in man. Recently, a number of experiments were done to reveal the scientific secret of acupuncture. As one of the specific action of the acupuncture analgesia, it has been re-ported that maximum effects are produced some time after the onset of the stimulation and the effects still remain after the cessation of its stimulation. Above-mentioned specific action, Which is usually sustained for some minutes or even some days, may not be explained by simple inhibitory neural mechanisms. Therefore, it has been proposed that the acupuncture effects are elicited by the activation of the endogenous humoral systems.

Especially, opioid systems are reported to play a leading role for producing analgesic effects. However, detailed mechanisms of analgesic effects induced by acupuncture are still unclear. The present speech shows the summary of the recent studies about peripheral and central mechanisms of acupuncture-induced antinociceptive effects obtained by basic electrophysiological experiments. The main topics are as follows:

1. characteristics of meridian points

2. afferent nerve information evoked by acupuncture stimulation

3. inhibitory mechanisms in the CNS

4. endogenous antinociceptive substances concerned with acupuncture analgesia

5. descending mechanisms of antinociceptive control.