Acupuncture-like stimulation induces a heterosegmental release of Met-enkephalin-like material in the rat spinal cord

In order to investigate the effects induced by acupuncture on the activity of enkephalinergic neurons in the spinal cord, either the lumbar or the cervico-trigeminal area was perfused with artificial cerebrospinal fluid (CSF) (0.1 ml/min) in halothane-anaesthetized rats, and Met-enkephalin-like material (MELM) was measured in 0.5 ml fractions of the perfusates. The effects of manual acupuncture performed by a traditional Chinese acupuncturist at the 'Zusanli' point on the right hind limb were compared to the effects induced by acupuncture applied at a non-acupoint next to 'Zusanli.' The manipulation of needles either at the 'Zusanli' point or at the non-acupoint had no effect on the release of MELM from the lumbar area but significantly increased the release from the cervico-trigeminal zone. It is concluded that manual acupuncture triggers a heterosegmental activation of enkephalinergic neurones within the spinal cord and that this effect is non-specific in terms of the location of the stimulated point.