Science forms the strong basis of our modern medicine. Traditional acupuncture theories, however, are not based on anatomical, physiological, or biochemical evidence. This made it extremely difficult for mechanistic understanding of acupuncture (#8). In the last 40 years, many scientists, both from the Western and Eastern hemispheres, have proposed multiple physiologic models to explain the effects of acupuncture. Endorphins, cytokines, hormones such as cortisol and oxytocin, biomechanical effects, the immune system, electromagnetic effects, autonomic and somatic nervous systems have been implicated in these models. Unfortunately the data have been inadequate or too inconsistent to draw significant conclusions (#4).
To date, pain relief is the most thoroughly studied application of acupuncture. Endorphin release at the spinal and supra-spinal levels is thought to be the neurotransmitter effects of acupuncture stimulation (#4).
“In 1987, Pomeranz proposed that acupuncture stimulation activates A-gamma and C afferent fibers in muscle, causing signals to be transmitted to the spinal cord, which then results in a local release of dynorphin and enkephalins. These afferent pathways propagate to the midbrain, triggering a sequence of excitatory and inhibitory mediators in the spinal cord. The resultant release of neurotransmitters, such as serotonin, dopamine, and norepinephrine onto the spinal cord leads to pre and postsynaptic inhibition and suppression of the pain transmission. When these signals reach the hypothalamus and pituitary, they trigger the release of adenocorticotropic hormones (ACTH) and endorphins. Pomeranz’s theory was confirmed by a large series of experiments by his research laboratory and other investigators. This conceptual framework for acupuncture-induced analgesia has also been investigated in a series of neurophysiologic and imaging studies over the last three decades,”(#8).
In support of Pomeranz’s theory, opioid antagonists (eg. Naloxone) were found to block the analgesic effects of acupuncture. In contrast, however, the Endorphin effects appear to be short-term, only lasting 10 to 20 minutes up to several days, while many acupuncture clinical trials have documented longer effects. In addition, endorphin release can be induced by strongly stimulating any muscle afferents or free nerve ending. Thus, the specificity and rationale of acupuncture point locations for different conditions remain unexplained (#4).
According to a recent review article on the scientific basis of acupuncture analgesia (#8), the conclusions based on current neurophysiologic studies are as follows:
- Afferent nociceptive pathways are essential for acupuncture analgesia.
- Acupuncture analgesia is mediated by way of various endogenous neurotransmitters, systemic release of enkephalin and dynorphin, and probably by decreasing the local inflammatory response via N-methyl-D-aspartate receptors.
- The acupuncture-induced pain threshold is gradual, with a peak effect at 20 to 40 minutes, followed by an exponential decay with a half-life of approximately 16 minutes.
- A prolonged period of acupuncture stimulation results in tolerance that is mediated via release of cholecystokinin octapeptide.
- Immunochemistry studies indicate that both pain and acupuncture activate the hypothalamic-pituitary-adrenocortical axis.
Powerful imaging technologies such as PET scan (positron emission tomography), functional MRI (magnetic resonance imaging) and SPECT (single-proton emission computer tomography have recently allowed non-invasive visualization of anatomical and functional effects of acupuncture stimulation in the human brain.
Based on current central nervous system (CNS) imaging studies (#8), the following conclusions were made by investigators:
- The hypothalamus and the limbic system play a central role in acupuncture analgesia.
- The significant overlap between acupuncture and CNS pain pathways suggests that acupuncture stimulation may affect pain signals processed in the CNS.
- Traditional needling (with “de qi” sensation) and superficial needling activate two different central pathways and yet both provide clinical analgesia.
The majority of current neuroimaging studies in acupuncture are merely explorations of acupuncture signal networks. The clinical relevance of the data obtained from these studies remains unclear (#8).
Worth mentioning, especially for the Quantum physics enthusiasts among us, is that a group of German scientists and physicists have recently demonstrated “evidence of the existence of the acupuncture meridian structure in the human body” via the use of biophotonics in the infrared spectral range (#9).
The scientists stated that: “After moxibustion (or similar light stimulation) of the body in the 3-5 micrometer range, “light channels” appear on the body, which appear to be identical to what are known as meridians in all textbook of Traditional Chinese Medicine. These findings appear not only to confirm the existence of acupuncture meridians, but they also open a new window on understanding the energy transfer dynamics of the human body. Furthermore, it is likely that living matter is not in the ground state, but permanently electronically excited,”(#9).