Traditional Chinese Acupuncture affects mu Opioid Receptors differently to Sham Acupuncture

A team of researchers at the University of Michigan, including FibroAction Professional Advisory Board member, Daniel Clauw MD, have used Positron emission tomography to determine that traditional chinese acupuncture activates certain pain relieving systems in the body better than sham acupuncture.

Controversy remains regarding the mechanisms of acupuncture analgesia or pain relief. A prevailing theory, largely unproven in humans, is that it involves the activation of endogenous opioid antinociceptive systems and mu-opioid receptors - i.e. the body's natural pain-killing mechanisms. This is also a neurotransmitter system that mediates the effects of placebo-induced analgesia. This overlap in potential mechanisms may explain the lack of differentiation between traditional acupuncture and either non-traditional or sham acupuncture in multiple controlled clinical trials. In other words, the systems that acupuncture activates to relieve pain are the same systems activated by the placebo effect of pain relief, which would explain why it is so hard to prove that traditional chinese acupuncture works better than the placebo of sham acupuncture.

The researchers compared both short-and long-term effects of traditional Chinese acupuncture versus sham acupuncture treatment on the binding availability of mu-opioid receptors in chronic pain patients diagnosed with fibromyalgia syndrome.

Patients were randomized to receive either traditional Chinese acupuncture or sham acupuncture treatment over the course of four weeks.

Positron emission tomography (PET) with (11)C-carfentanil was performed once during the first treatment session and then repeated a month later following the eighth treatment.

The researchers found that acupuncture therapy evoked short-term increases in mu-opioid receptor binding potential, in multiple pain and sensory processing regions including the cingulate (dorsal and subgenual), insula, caudate, thalamus, and amygdala. Acupuncture therapy also evoked long-term increases in mu-opioid receptor binding potential in some of the same structures including the cingulate (dorsal and perigenual), caudate, and amygdala.

These short-and long-term effects were absent in the sham group where small reductions were observed, an effect more consistent with previous placebo PET studies.

Long-term increases in mu-Opioid receptor binding potential following traditional Chinese acupuncture were also associated with greater reductions in clinical pain.

In conclusion:

"These findings suggest that divergent [mu-Opioid receptor] processes may mediate clinically relevant analgesic effects for acupuncture and sham acupuncture."

References:

1. Harris RE, Zubieta JK, 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. 2009 Jun 4. [Epub ahead of print]