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4 June 2010

Relief as scientists suggest how acupuncture may work

Scientists from the USA have given mice acupuncture to try and pinpoint exactly how it produces its pain-relieving effects.

Acupuncture is a procedure in which fine needles are put into the skin at specific points on the body to relieve pain. The needles are placed along special channels (meridians) on the body. They can be twisted, stimulated with electricity or sometimes heated to enhance the effect. Traditional practitioners believe that acupuncture works by improving the flow of an energy known as 'qi' in the body. If the flow of qi is restored, then the body can start to heal itself. In this study, the researchers did a number of experiments to challenge the view that the benefits of acupuncture are merely the result of a placebo (dummy) effect.

The researchers first wanted to find out if adenosine (a chemical released naturally by cells when they are damaged) is produced by the body during acupuncture. They did this by putting a needle into the anaesthetised mouse's knee and then turning it every five minutes for a total of 30 minutes. The test showed that adenosine levels increased 24-fold in the tissues surrounding the needle, and remained raised for up to an hour.

In a second experiment, the researchers looked at whether adenosine can relieve pain caused by an injury. They compared two groups of mice: one normal group and one group that didn't react to adenosine. Each mouse was given a sore paw by injecting it with a special chemical, before the acupuncture needle was put into the knee above the injured foot. The researchers measured how quickly each mouse pulled its sore paw away from a small, bristly brush. The more pain the mouse was in, the faster it pulled away. Overall, the results showed that acupuncture reduced pain substantially in the normal group of mice, but had no effect on the mice that couldn't react to adenosine. This means that adenosine may be responsible for producing the pain relieving effects of acupuncture, when there is an injury to the area.

The researchers also tried to explain why acupuncture only seems to work if the needles are inserted at specific points on the body. They suggest that the meridians targeted by acupuncturists lie along major nerve tracks, which is where lots of adenosine receptors are located.

Researching acupuncture in mice is certainly innovative, but there are several aspects of this study that aren't very clear, and questions that remain unanswered. For example, the researchers don't actually tell us whether they anaesthetised the mice during their experiments or not. If they did, which is very likely, how can we be sure the pain-relieving effects observed aren't related to the anaesthetic? Also, the researchers don't say if the acupuncture points they used are the same in mice as they are in humans. If they aren't, then we should be very sceptical of these results.

Commenting on the research, Dr Virginia Warren, Assistant Medical Director for Bupa, said: "Although this study showed that the mice responded to having a needle put into their knee and having it twisted, more research is needed to understand exactly how acupuncture works in humans. We should remain open-minded about acupuncture treatments and wait to see if they become more accepted in evidence based medicine."

Related information

• Acupuncture health factsheet
• Acupuncture may help to alleviate depression in pregnancy - health news
• Migraine health factsheet
• Osteoarthritis health factsheet
• Rheumatoid arthritis health factsheet
• Tension-type and medication overuse headaches health factsheet

Read the study

Goldman N, Chen M, Fujita T, et al. Adenosine A1 receptors mediate local anti-nociceptive effects of acupuncture. Nature Neuroscience 2010 doi: 10.1038/nn.2562

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