For those still harboring doubts about acupuncture, this discovery adds proof of local chemical release in the peripheral nervous system to the recent discovery of a central nervous system endorphin response.
Scientists have taken another important step toward understanding just how sticking needles into the body can ease pain.
In a paper published online May 30 in Nature Neuroscience (“Adenosine A1 receptors mediate local antinociceptive effects of acupuncture” ), researchers at the University of Rochester’s Center for Translational Neuromedicine have identified the molecule adenosine as a central player in parlaying some of the effects of acupuncture in the body.
Building on that knowledge, the scientists were able to triple the beneficial effects of acupuncture in mice by adding a medication approved by the FDA to treat leukemia in people.
The research focuses on adenosine, a natural compound known for its role in regulating sleep, for its effects on the heart, and for its anti-inflammatory properties. But adenosine also acts as a natural painkiller, becoming active in the skin after an injury to inhibit nerve signals and ease pain in a way similar to lidocaine. [According to the paper, mechanical or electrical tissue stimulation releases ATP (adenosine triphosphate) from the cells – and ATP, the stuff of cellular energy, quickly degrades to adenosine .]
In the current study, scientists found that the chemical is also very active in deeper tissues affected by acupuncture. The Rochester researchers looked at the effects of acupuncture on the peripheral nervous system – the nerves in our body that aren’t part of the brain and spinal cord.
Acupuncture’s Multiple Anti-Pain Effects
The research complements a rich, established body of work showing that in the central nervous system, acupuncture also creates signals that cause the brain to churn out natural pain-killing endorphins.(1)
The new findings add to the scientific heft underlying acupuncture, said neuroscientist Maiken Nedergaard, MD, DMSc , who led the research. Her team presents the work this week at a scientific meeting, Purines 2010, in Barcelona, Spain.
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“Acupuncture has been a mainstay of medical treatment in certain parts of the world for 4,000 years, but because it has not been understood completely, many people have remained skeptical,” said Nedergaard. “In this work, we provide information about one physical mechanism through which acupuncture reduces pain in the body.”
To do the experiment, the team performed acupuncture treatments on mice that had discomfort in one paw. The mice each received a 30-minute acupuncture treatment at a well known acupuncture point near the knee, with very fine needles rotated gently every five minutes, much as is done in standard acupuncture treatments with people.
The team made a number of observations regarding adenosine:
• In mice with normal functioning levels of adenosine, acupuncture reduced discomfort by two-thirds.
• In special “adenosine receptor knock-out mice” not equipped with the adenosine receptor, acupuncture had no effect.
• When adenosine was turned on in the tissues, discomfort was reduced even without acupuncture.
• During and immediately after an acupuncture treatment, the level of adenosine in the tissues near the needles was 24 times greater than before the treatment.
Adenosine Elimination Inhibitors May Boost Acupuncture’s Impact
Once they recognized adenosine’s role, the scientists explored the effects of a cancer drug called deoxycoformycin, which makes it harder for the tissue to remove adenosine. The compound boosted the effects of acupuncture treatment dramatically, nearly tripling the accumulation of adenosine in the muscles and more than tripling the length of time the treatment was effective.
“It’s clear that acupuncture may activate a number of different mechanisms,” said Josephine P. Briggs, MD, director of the National Center for Complementary and Alternative Medicine at the National Institutes of Health. “This carefully performed study identifies adenosine as a new player in the process. It’s an interesting contribution to our growing understanding of the complex intervention which is acupuncture.”
Funding for the work came from the New York State Spinal Cord Injury Program and the National Institutes of Health.
1. See article footnotes 4, 5, 6, and “Fibromyalgia imaging study demonstrates that Chinese acupuncture affects brain’s ability to regulate pain – describes how.” 
Source: Based on University of Rochester (NY) Medical Center, news release, May 30, 2010