Acupuncture mechanisms for clinical long-term effects, a hypothesis
Introduction
This article is based upon a hypothesis in the author's dissertation, where more discussion and more references can be found regarding the subject [1]. In the thesis, some of the original articles [2], [3] make it probable that acupuncture for some chronic pain patients, mostly those with nociceptive pain, can lead to a long-term pain relieving effect. In order to explain these long-term effects, the author analysed the experimental work performed to explain acupuncture analgesia. It became obvious that the animal research (and experimental human research) was almost not at all relevant for what we try to perform in the clinical setting. Thus, it became obvious to look at probable mechanisms in another way and not only in the usual neurophysiological manner. Therefore, a new hypothesis of mechanisms behind therapeutic acupuncture was put forward in the thesis. This text is a summary of the experimental work published from different research groups since about 35 years ago. From conclusions drawn after reviewing this literature, the hypothesis was formulated.
Section snippets
Acupuncture analgesia (AA)
In China, experiments began in 1958 [4] using electroacupuncture (EA) for pain relief during surgery. A success rate of 90% was claimed among those selected for the method. However, less than 10% of the patients showed a satisfactory response in acupuncture trials, and were the only ones given acupuncture for surgical pain relief. Of these 10%, only a third had acceptable analgesia according to western standards [5], [6]. It should also be realised that, in order to get this small “success”
Stress-induced analgesia or specific acupuncture induced analgesia?
Most research groups have used conscious animals where no special attention has been taken to rule out stress-induced analgesia (SIA). We now know that stress induces an increase in brain endorphins (e.g. Ref. [19]). We also know that repeated daily applications of, e.g. foot shocks, gradually lead to adaptation. Thus, SIA develops tolerance and not an increased effect after repeated applications. It has also been shown that the different endorphin receptors (μ, κ, δ) can be involved in
Peripheral effects
The insertion of a needle in the tissues induces important changes close to the needle in all the different tissues penetrated.
Vasodilatation in the skin due to axon reflexes (flare reaction) has been recognised for a very long time and the mechanisms have been clarified in detail [46], [47].
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Stimulation of Aδ or C fibres releases vasoactive and pro-inflammatory neuropeptides (e.g. CGRP, SP, opioids, galanin, somatostatin and VIP) [48], [49].
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EA (and TENS) produces peripheral vasodilatation, in
A hypothesis on the mechanisms of acupuncture
Based on the mechanisms mentioned, the following hypothesis may be proposed.
Clinical observations that can be understood with this hypothesis
The hypothesis presented might be a ground for new kinds of mechanism studies, which are quite obvious.
The main purpose of the hypothesis is that it can explain much more of what we see in the clinic than the usual neurophysiological model.
With this hypothesis, we can understand:
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Why we shall use local points. The neurophysiological model only tells us that we should use some segmental points and some extrasegmental points. The points we use does not matter at all. This is not in accordance with
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2017, JAMS Journal of Acupuncture and Meridian StudiesCitation Excerpt :Other concept based on the central biasing mechanism is as follows: acupuncture may alter the metabolism of substrates involved in both the ascending facilitatory pathways (N-methyl-D-aspartate receptors, substance P, and interleukin-1) and the descending inhibitory pain pathways (endogenous opioids, serotonin, and norepinephrine) [13]. Therefore, simultaneous stimulation of the smaller fibers, during acupuncture needling results in activation and release of opioids, including β-endorphins, encephalins, and dynorphins which are endogenous peptides that bind to μ-, δ-, and κ-receptors from the brain stem into the blood to create analgesia [14,15,25–27]. These endogenous peptides block the incoming pain information through the release of neurotransmitters such as serotonin, norepinephrin, GABA which reduces pain subsequently [14,15].
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Neural mechanism underlying acupuncture analgesia
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