Endorphin release: a possible mechanism of acupuncture analgesia.

The action of acupuncture stimulation on analgesia has been investigated. The brain and serum extracts of acupunctured rabbits injected into rabbits produced a marked analgesic effect on the recipient, as shown by a great increase of their pain threshold. This effect is counteracted by a specific opiate anatagonist, naloxone. The data suggest that the release of the endogenous substances with morphine-like biological properties, endorphins, is increased by acupuncture stimulation, thus inhibiting pain perception.