I came across this authentic research explanation on the mechanism how acupuncture works. I am sharing this in this forum.

Acupuncture is a procedure in which fine needles are inserted into an individual at discrete points and then manipulated, with the intent of relieving pain. Since its development in China around 2,000 B.C., acupuncture has become worldwide in its practice1. Although Western medicine has treated acupuncture with considerable skepticism2, a broader worldwide population has granted it acceptance. For instance, the World Health Organization endorses acupuncture for at least two dozen conditions3 and the US National Institutes of Health issued a consensus statement proposing acupuncture as a therapeutic intervention for complementary medicine. Perhaps most tellingly, the U.S. Internal Revenue Service approved acupuncture as a deductible medical expense in 1973.

Although the analgesic effect of acupuncture is well documented, little is understood about its biological basis. Insertion of the acupuncture needles in itself is not sufficient to relieve pain4. An acupuncture session typically lasts for 30 min, during which the needles are intermittently rotated, electrically stimulated or, in some cases, heated. The pain threshold is reported to slowly increase and to outlast the treatment4. The primary mechanism implicated in the anti-nociceptive effect of acupuncture involves release of opioid peptides in the CNS in response to the long-lasting activation of ascending sensory tracks during the intermittent stimulation4–6. However, a centrally acting agent cannot explain why acupuncture is conventionally applied in close proximity to the locus of pain and why the analgesic effects of acupuncture are restricted to the ipsilateral side7,8.

RESULTS
Acupuncture triggers adenosine and ATP metabolites release

ATP is released in response to either mechanical and electrical stimulation or heat. Once released, ATP acts as a transmitter that binds to purinergic receptors, including P2X and P2Y receptors9,10. ATP cannot be transported back into the cell but is rapidly degraded to adenosine by several ectonucleotidases before re-uptake10. Thus, adenosine acts as an analgesic agent that suppresses pain through Gi-coupled A1-adenosine receptors11–13. To determine whether adenosine is involved in the anti-nociceptive effects of acupuncture, we first asked whether the extracellular concentration of adenosine increases during acupuncture.

We collected samples of interstitial fluid by a microdialysis probe implanted in the tibialis anterior muscle/subcutis of adult mice at a distance of 0.4–0.6 mm from the ‘Zusanli point’, which is located 3–4 mm
below and 1–2 mm lateral for the midline of the knee4. Adenine nucleotides and adenosine were quantified using high-performance liquid chromatography (HPLC) with ultraviolet absorbance before, during and after acupuncture (Fig. 1a)14,15. At baseline, the concentrations of ATP, ADP, AMP and adenosine were in the low nanomolar range (Fig. 1b), consistent with previous reports16,17. Acupuncture applied by gentle manual rotation of the acupuncture needle every 5 min for a total of 30 min sharply increased the extracellular concentrations of all purines detected (Fig. 1b).

Adenosine concentration increased ~24-fold (253.5 ± 81.1 nM from a baseline of 10.6 ± 6.7 nM) during the 30-min acupuncture session (Fig. 1c). The extracellular concentration of ATP returned to baseline after acupuncture, whereas adenosine, AMP and ADP remained significantly elevated (adenosine and AMP, P < 0.01; ADP, P < 0.05, paired t test compared to 0 min) at 60 min (Fig. 1c). Notably, previous studies have shown that deep brain stimulation is also associated with a severalfold increase in extracellular ATP and adenosine. Similar to electroacupuncture and transcutaneous electrical nerve stimulation, deep brain stimulation delivers electrical stimulation that triggers an increase in extracellular adenosine concentration18.


© 2010 Nature America, Inc. All rights reserved.
nature neuroscience


1Center for Translational Neuromedicine, University of Rochester Medical Center, Rochester, New York, USA. 2Department of Neurology, Boston University School of Medicine, Boston, Massachusetts, USA. 3National Institute of Diabetes and Digestive and Kidney Diseases, US National Institutes of Health, Bethesda, Maryland, USA. 4These authors contributed equally to this work. Correspondence should be addressed to M.N.

Received 16 March; accepted 27 April; published online 30 May 2010; doi:10.1038/nn.2562
Adenosine A1 receptors mediate local anti-nociceptive effects of acupuncture
Nanna Goldman1,4, Michael Chen1,4, Takumi Fujita1,4, Qiwu Xu1, Weiguo Peng1, Wei Liu1, Tina K Jensen1,
Yong Pei1, Fushun Wang1, Xiaoning Han1, Jiang-Fan Chen2, Jurgen Schnermann3, Takahiro Takano1,
Lane Bekar1, Kim Tieu1 & Maiken Nedergaard1