Mechanisms of acupuncture-electroacupuncture on persistent pain (review)

Preclinical (animal-model) review of the physiological mechanisms by which electroacupuncture reduces persistent pain (inflammatory, neuropathic, cancer, and visceral pain models). Needling appears to release endogenous opioids (endorphins, enkephalins, dynorphin) acting at central opioid receptors, to generate adenosine acting at A1 receptors locally at the needle site, and to engage descending inhibitory pathways involving serotonergic, noradrenergic and other systems. These are real, measurable effects that establish a plausible biological mechanism for a needle’s analgesic action. They do not, on their own, validate the traditional meridian framework or settle how much of the clinical effect exceeds a credible sham.