By Dr. Winson Chen
Acupuncture is a significant constituent of Traditional Chinese Medicine (TCM), widely employed for thousands of years. Despite the lack of definitive consensus on its mechanism of action, significant evidence suggests it involves intricate physiological responses in the musculature, peripheral, and central nervous systems. This paper aims to review the underlying mechanisms of acupuncture from both the traditional TCM perspective and the latest scientific explanations.
Acupuncture, an ancient TCM practice, has been used as a therapeutic modality for millennia. Its utility ranges from pain alleviation to managing chronic conditions. This ancient technique involves the insertion of fine needles into specific body points, known as acupuncture points or ‘acupoints.’ Despite its widespread use, the mechanism of action remains a topic of ongoing research and debate in modern medicine
Traditional Chinese Medicine Perspective
The traditional explanation for acupuncture’s effectiveness lies in the concept of Qi (pronounced “chi”), a vital life force or energy flowing through the body along meridians or pathways. Health is perceived as the harmonious balance and free flow of Qi. Disease, on the other hand, is believed to result from the disruption or imbalance of Qi. Acupuncture, by stimulating specific acupoints, aims to restore the balance and flow of Qi, thereby restoring health.
Modern Scientific Explanations
Modern scientific studies indicate that acupuncture’s mechanisms might involve complex neurophysiological processes affecting various body systems. These can be examined under three broad categories: musculature, peripheral nervous system, and central nervous system.
When an acupuncture needle is inserted into the skin and underlying muscle tissue, it causes a minor injury or “micro-trauma” at the site of insertion. This minor trauma stimulates the body’s natural healing response, causing inflammation and release of various chemicals. Among these chemicals are histamines, prostaglandins, and cytokines, which are part of the body’s immune response.
Histamines and prostaglandins cause vasodilation or widening of blood vessels at the site of injury, increasing blood flow to the area. This increased blood flow brings more nutrients and oxygen, which are necessary for healing. Cytokines are small proteins that play a critical role in cell signaling during the immune response. They help to promote the proliferation of cells necessary for healing, such as fibroblasts, which are responsible for wound healing by producing collagen.
2. Peripheral Nervous System
The peripheral nervous system (PNS) serves as a communication relay between the body and the central nervous system (CNS). When an acupuncture needle is inserted and manipulated, it stimulates specific nerve fibers in the PNS. These stimulated nerve fibers then send signals up to the spinal cord and brain.
One significant effect of this stimulation is the release of endogenous opioids, including endorphin, enkephalin, and dynorphin. These are the body’s natural painkillers, working by binding to opioid receptors on nerve cells and blocking the transmission of pain signals. This local release of endogenous opioids at the site of needle insertion is one reason why acupuncture can have an analgesic or pain-relieving effect.
3. Central Nervous System
Acupuncture’s effects on the central nervous system, which consists of the brain and spinal cord, are complex and multifaceted. As mentioned, the stimulation of peripheral nerve fibers by the acupuncture needle sends signals up to the brain. These signals can alter the activity in various brain regions involved in pain perception and processing, including the anterior cingulate cortex, prefrontal cortex, and insula. This can lead to a reduction in the perception of pain.
In addition to influencing pain-related neural areas, acupuncture has also been found to modulate the activity of the limbic system, the brain’s emotional center. This could explain why acupuncture can be beneficial in managing stress and anxiety disorders.
Moreover, acupuncture stimulates the release of various neurotransmitters in the brain. These include serotonin and norepinephrine, which can help modulate mood and are involved in the body’s natural pain inhibitory pathways. Acupuncture also triggers the release of adenosine, a neuromodulator with potent analgesic effects, in the vicinity of the needle placement.
Although acupuncture’s mechanism of action remains partially elusive, modern science has illuminated its multifaceted physiological impact, spanning from local tissue to the brain. These insights allow for an increasingly nuanced understanding of its therapeutic potential beyond the traditional Qi-based explanation. Despite the differences between traditional and modern perspectives, both share a common emphasis on balance and homeostasis. Further research is warranted to fully elucidate acupuncture’s complex mechanisms, which could potentially pave the way for novel therapeutic interventions.