Recent acupuncture research has shown that Acupuncture in chronic pain patients failed to show superiority over sham acupuncture methods. This has caused many opponents of acupuncture to suggest that traditional acupuncture is not more effective than sham acupuncture.  Sham Acupuncture is when non-acupuncture points are needled, or the skin is pricked to mimic acupuncture.

Other scientific research has shown that the difference between traditional acupuncture and sham acupuncture lies in the short and long term effects on mu-Opioid receptors (m-ORs) in the body.

Mu-Opioid receptors are where pain relieving drugs like morphine and the body's own pain relieving chemicals like endorphins are received by the body. Besides pain relief, activation of mu-Opioid Receptors cause relaxation, reduced blood pressure, euphoria, decreased respiration and other other actions. 

Studies compared mu-Opioid receptor binding availability in chronic pain patients diagnosed with fibromyalgia.

During the trial, it was shown that Traditional Acupuncture therapy evoked short and long term pain relief and increases in mu-Opioid receptor binding potential in multiple pain and sensory processing regions of the body.

Sham Acupuncture showed pain relieving effects but no change in mu-Opioid receptor binding potential. 

Activation of mu-Opiod Receptors have a pain relieving affect on the area of activation of these receptors.

Natural opioids like endorphin relieve pain and are released by your body during Acupuncture. The long term effects of Traditional Acupuncture was associated with greater reductions in clinical pain due to the increased availability of mu-Opioid receptor binding potential.  In other words, more natural pain-relieving opioids are received by mu-Opioid receptors after Acupuncture. This increases the duration of the pain relieving effects of acupuncture.

The findings of this study suggest that mu-Opioid Receptor processes may play a role in clinically relevant pain relieving effects for acupuncture and sham acupuncture.

References

Harris, RE, Zubieta J, Scott DJ, Napadow V, Gracely RH, Clauw DJ. Traditional Chinese Acupuncture and placebo (sham) acupuncture are differentiated by their effects on mu-opioid receptors (MORs). Neuroimage 47, 1077-1085