Opioid-like activity in the cerebrospinal fluid of pain patients treated by electroacupuncture

Thirteen patients with pain from various causes were treated by electroacupuncture for 30 min. Cerebrospinal fluid (CSF) was obtained before and after treatment. Opioid-like substances in the CSF were fractionated by high pressure liquid chromatography and assayed by competitive receptor binding using a mu-specific radioligand, [D-ala2, MePhe4, gly-ol5]-enkephalin (DAGO). Opioid activity, associated with a fraction, eluted at 18-20% acetonitrile, consistently showed an increase in level after acupuncture. Two other fractions eluted at larger concentrations of acetonitrile also increased significantly after acupuncture; however the increase was not consistently observed in every patient. Measurements of beta-endorphin and dynorphin by radioimmunoassay indicated that 80 and 60% of the patients, respectively, had a higher level of these peptides after acupuncture. The nature of the opioid activity, eluted at 18-20% acetonitrile is unknown; however a small amount of it could be found in various parts of the brain of rat.