Acupuncture is originated from China 2500 thousand years ago and the theory is based on the meridians and energy (Qi) flow through the body. Recent research on acupuncture provided evidence of the mechanisms of acupuncture in scientific bases. In 1950s Chinese government began to invest in research on acupuncture. The interest in acupuncture is increased not only for medical professionals all over the world, but also for researchers. They would like to know how the needles work. Since 70’s, acupuncture becomes more and more popular in US and European countries. In 1971, a report in the New York Times inspired American doctors to China to study analgesia effect of acupuncture. In 1990s there was a remarkable increase in acupuncture research. The publications of acupuncture research continue to increase. Acupuncture has received an enormous boost in the last few years. In 50 years the achievements of acupuncture research is extraordinary. The National Institute of Health consensus conference in 1997 recognised acupuncture (and by extension Traditional Chinese Medicine) as a legitimate branch of scientific medicine. Acupuncture seems very likely to be accepted and incorporated into Western medicine. Acupuncture becomes popular than ever.
Acupuncture increases blood circulation
Acupuncture increases local blood flow.
Regulating blood flow both centrally and peripherally are important in contributing mechanism of acupuncture. Here are some examples of the research in this aspect.
Recently a study investigated the changes of local blood flow in response to acupuncture stimulation. In this study eight random controlled trials involved 205 participants were included. In most of the selected studies, acupuncture was performed at points located distal to the elbows and knees such as LI4, ST36, and PC6, whereas one study simultaneously used several acupoints on the extremities. In one study the GB21 acupoint on the posterior region of the shoulder was stimulated with an acupuncture needle. All eight studies selected for the present review observed acupuncture-induced changes in blood flow in the skin, whereas three studies observed changes in blood flow in the muscle. Four reported significant increases in blood flow following acupuncture compared with control, whereas one other study observed reductions in microcirculation immediately after acupuncture needling. The studies that assessed patients with either fibromyalgia or trapezius myalgia found significant increases in blood flow in the skin and muscle. Additionally, the degree and duration of increases in microcirculation varied depending on the condition of the subjects and the manipulation technique.
Another study about effect of acupuncture in peripheral tissue perfusion has been done on two healthy subjects. Acupuncture was performed on two acupoints (LI4 and SI3) which are in the hands three treatments within 1 week. Local blood perfusion on the hands was measured before and after acupuncture treatments. The result has shown that the blood perfusion rates of the hands were noticeably increased immediately after acupuncture at the first treatment in both cases. At the third treatment the increased blood perfusion was seen in one case, not the other one.
Hsiu H et al studied the microcirculatory blood flow response following acupuncture stimulation using beat to beat laser Doppler flowmetry (LDF) which could provides important information on the circulatory regulatory activities. Changes in the arterial pulse transmission or the opening condition of arteriolar opening might change the fluctuation pattern of the microcirculatory blood supply. They measured LDF signals to study the microcirculatory blood flow response at the needled site particularly at Hegu LI4 acupuncture point) after acupuncture stimulation. They selected 29 male healthy volunteers to measure microcirculatory blood flow after acupuncture stimulation. The measurements were at three times: before acupuncture stimulation, immediately after acupuncture stimulation and about 1 hour after acupuncture stimulation. They found that acupuncture not only improves local blood supply and but also regulates microciculatory blood flow by altering microcirculatory blood supply parameters. Their findings could help to identify the mechanism underlying the effects of acupuncture stimulation.
Acupuncture increases blood perfusion around the acupoints.
Researchers are using modern techniques to study the mechanisms of acupuncture to explain the phenomenon from modern science aspect. Li XM et al studied influence of different acupuncture manipulations at Zusanli (ST36) on skin microcirculation blood perfusion in healthy subjects. They measured local blood perfusion at ST 36 acupuncture points after acupuncture stimulation at 1min, 5 min, 10, 15min, 20 min, 25 min and 30 min. They also compared blood perfusion levels of microcirculation around the acupoints among the different manipulation techniques. They found that microcirculation around the selected acupoint was significantly increased from 1-10 min following simple needle insertion, from 5 -30 min after uniform reinforcing-reducing manipulation, from 1-30 min after reinforcing manipulation, and from 1-25 min following reducing manipulation respectively. The reinforcing manipulation was superior to other techniques. From this study we can see acupuncture increases local blood perfusion in normal subjects. The reinforcing manipulation had better effect.
Acupuncture dilates blood vessels
Research has shown that there were more of nerve fibers/trunks, blood vessels, hair follicles, and sweat glands as well as density of the gap junction in the acupuncture points. Recent research has shown that nitric oxide (NO) level is elevated in the acupoints and is associated with an enhanced expression of NO synthase endowed with transient receptor potential vanilloid type-1. This suggests that acupuncture induces NO-mediated vasodilatation, which increases local blood flow and allows for a flush of algesic or sensitizing substances, leading to pain relief.
Color Doppler imaging (CDI) can be used to noninvasively create images of human blood vessels and quantitatively evaluate blood flow in real-time. The purpose of this study was to assess the effects of acupuncture on the blood flow of the peripheral, mesenteric, and retrobulbar arteries by CDI. Statistical significance was defined as P values less than 0.05. Blood flow in the radial and brachial arteries was significantly lower during needle stimulation on LR3 than before in healthy volunteers, but was significantly higher after needle stimulation than before. LR3 stimulation also resulted in a significant decrease in the vascular resistance of the short posterior ciliary artery and no significant change of blood flow through the superior mesenteric artery (SMA) during acupuncture. In contrast, ST36 stimulation resulted in a significant increase in blood flow through the SMA and no significant change in the vascular resistance of the retrobulbar arteries. Additionally, acupuncture at previously determined acupoints in patients with open-angle glaucoma led to a significant reduction in the vascular resistance of the central retinal artery and short posterior ciliary artery. Our results suggest that acupuncture can affect blood flow of the peripheral, mesenteric, and retrobulbar arteries, and CDI can be useful to evaluate hemodynamic changes by acupuncture.
Hsiu H et al Microvasc Res (2013) Jun 24
Kim S et al Evid Based Complement Alternat Med (2016) 9874207. doi: 10.1155/2016/9874207. Epub 2016 Jun 14.
Li XM et al Zhen Ci Yan Jiu (2013) 38:297-300
Shin Takayama, et al Evid Based Complement Alternat Med. 2012; 2012: 513638.
Acupuncture reduces inflammation
The signs of inflammation include increasing temperature, oedema, redness, pain and loss of function. In molecular side, neuropeptides, cytokines and vasoactive mediators are suggested to be a part of the inflammation. After inflammation has been initiated, vasoactive mediators could regulate blood flow and blood distribution to affected organs and tissue. Acupuncture stimulates local blood flow and activates the defence systems and clear up all bioactive mediators, as result it reduces local inflammation.
F. Zijlstra1 Et al Mediators of Inflammation, 12(2), 59/69 (April 2003)
Acupuncture makes the brain release endorphins
Endorphins are neurotransmitters produced in the brain known as endogenous opioids and they can be found in the pituitary gland, in other parts of the brain, or distributed throughout the nervous system. They transmit electrical signals within the nervous system by interacting with opiate receptors in the brain. The action is similar to morphine and codeine, but without addiction or dependence. At least 20 types of endorphins have been found in humans. In response to pain and stress, they decrease feelings of pain and also lead to feelings of euphoria, modulate appetite, release sex hormones, and enhance the immune response. As a result, it makes people feel less pain and less stressed.
Many studies in animals and humans have demonstrated that acupuncture can cause multiple biological responses. These responses can occur locally, i.e., at or close to the site of application, or at a distance, mediated mainly by sensory neurons to many structures within the central nervous system. This can lead to activation of pathways affecting various physiological systems in the brain as well as in the periphery. Endogenous opioids (endorphins) in acupuncture analgesia is well established. The opioid peptides are released during acupuncture and that the analgesic effects of acupuncture are at least partially explained by their actions. That opioid antagonists such as naloxone reverse the analgesic effects of acupuncture further strengthens this hypothesis. Stimulation by acupuncture may also activate the hypothalamus and the pituitary gland, resulting in a broad spectrum of systemic effects. Alteration in the secretion of neurotransmitters and neurohormones and changes in the regulation of blood flow, both centrally and peripherally, have been documented.
Acupuncture alters brain activities
Acupuncture has been accepted globally. Acupuncture stimulates the brain releasing endorphins which is essential in acupuncture analgesic effect.
Acupuncture altered brain activity and releases low back pain
Functional magnetic resonance imaging (fMRI) is a new technology that is used to study brain. Pain stimulus could induce extensive activations in the limbic system [anterior cingulated cortex (ACC), periaqueductal gray (PAG), prefrontal cortex] and somatosensory system (thalamus, primary somatosensory cortex (S1), secondary somatosensory cortex (S2), posterior parietal cortices, insula, supplementary motor area, striatum, and cerebellum) areas as well as the pain matrix (S1, S2, insular, frontal lobe and parietal lobe). The pain matrix showed a strong relationship with pain, which plays an important role in the conduction and communication of pain. This can be seen changes on fMRI. Low back pain (LBP) is one of the most common clinical syndromes and affects 80–85% of people at some point in their life. Most LBP is nonspecific which does not have a definitive cause.
In a recent study, an experimental acute LBP model and fMRI was used to study the neural mechanisms of acupuncture analgesia. All LBP subjects first underwent two resting state fMRI scans at baseline and during a painful episode and then underwent two additional fMRI scans, once during acupuncture stimulation (ACUP) and once during sham stimulation, at the BL40 acupoint. They found that acupuncture induced more deactivations and fewer activations in the brain. Acupuncture can alter brain activity and this contributes to mechanism of analgesia of acupuncture to LBP.
Acupuncture altered brain network function
There was a study about acupuncture stimulating brain functional network. This study was based on sample entropy of electroencephalograph (EEG) under magnetic stimulation at PC6 acupoint which is on your forearm and near your wrist. Magnetic stimulation at acupuncture point is a new method for studying the theory of acupuncture. It helps to investigate brain network and understand how brain works. This study was trying to provide evidence for the mechanism of acupuncture which is a part of traditional Chinese medicine. The magnetic stimulation of PC6 acupoint was performed and EEG signals were recorded. By analysing the results they found the brain network topology was changed after acupuncture at PC6 acupoint, the connection of the network is increased, the efficiency of information transmission is improved and the small-world proper is strengthened through stimulation the PC6 acupoint.
Acupuncture at different acupoints may alter brain activities in different area.
Recent acupuncture research study the effect of acupuncture on brain activity using functional magnetic resonance imaging (MRI). Wang W et al used electro-acupuncture to stimulate the cerebral activated areas. They compared the altered activation areas of the acupuncture point LI4 on the right hand with some non acupuncture points on the face. There were 6 people in the LI4 group and 5 in the facial nonacupoint group. MRI ws performed before and after acupuncture. They found that activation or deactivation was found the multiple cerebral areas in both groups. In the LI4 group, activation was found in the areas including medline nuclear group thalamus, left supra marginal gyrus, left supra temporal gyrus, right precuneous lobe, bilateral temporal pole, left precentral gyrus and left cerebellum; deactivation areas include bilateral hippocampus, parahippocampal gyrus, amygdale body area, rostral side/audal side of ingulate gyrus, prefrontal lobe and occipital lobe as well as left infratemporal gyrus. In the control group, the activation and deactivation areas were different from LI4. They concluded that the deactivation area by LI4 was a similar area distribution of pain area in the brain and closely related to the anatomic structure of limbic system which is possibly related to pain relief. Activation of left anterior gyrus by LI4 represents the movement of facial muscles and activation of cerebellum is possibly related to effect of LI4 in treating facial palsy and facial muscle spasm.
Fang JL et al compared the effects of electroacupuncture at acupoints ST36 and CV4 using MRI in 21 healthy volunteers. The similar deactivation effects in the anterior cingulated and medial prefrontal cortices were induced by acupuncture at ST36 or CV4 acupoint. The functional brain network was significantly changed after acupuncture. The instant postacupuncture effects were mainly found in the ventral medial prefrontal cortex and ventral anterior cingulated cortex in the limbic-paralimbic-neocortical network and the effects were stronger at ST36 than that CV4.
Facial acupuncture increases brain blood flow
A new research studies the effect of facial acupuncture on brain blood flow. In this study brain blood flow and heart rate were measured before and after acupuncture treatment. The result has shown that brain blood flow was significantly greater in the brain more specifically in the prefrontal cortex in the acupuncture group. Heart rate was reduced.