The origins of acupuncture are lost in antiquity and, today, the effectiveness of such treatment remains controversial. Despite the sometimes extravagant claims of proponents, there is little scientific basis to explain how acupuncture works and many researchers believe that the effects are attributable to a placebo effect. In a study published in Nature Neuroscience, researchers led by a team at the University of Rochester Medical Center have now suggested a physiological mechanism that may explain the analgesic effects of acupuncture.
The team found that adenosine was released during acupuncture in mice and that the analgesic effect of acupuncture could be replicated by direct injection of an adenosine A1 receptor agonist, 2-chloro-N(6)-cyclopentyladenosine (CCPA). Adenosine, which is released in response to injury or inflammation, has known pain-relieving properties and acupuncture was found to be ineffective in A1 receptor knock-out mice. 2′-Deoxycoformycin (dCF), a potent inhibitor of adenosine deaminase, was found to boost the effects of acupuncture, increasing the accumulation of adenosine in tissue as well as the duration of analgesia.
It will be interesting to see whether similar effects are observed in human subjects and also whether adenosine is also released during ‘sham’ acupuncture treatment in which needles are pressed against the skin without puncturing it – lack of differentiation from sham treatment is one of the main reasons that detractors cite for the placebo effect of acupuncture.