When the human body was finally described in terms of cells, biochemicals, and specific structures (most of this accomplished less than 150 years ago), the Chinese method of acupuncture and its underlying concepts were evaluated in these new terms. As a first effort, researchers sought out physical pathways that might correspond to the meridians, and even a fluid substance that might correspond to qi. Neither of these were found. Nonetheless, the action of performing acupuncture was shown to have effects on the body that required some detailed explanation.
From the modern perspective, diseases and injuries are resolved by a complex set of responses; the responses are coordinated by several signaling systems. The signaling systems mainly involve peptides and other small biochemicals that are released at one site, travel to other sites, interact with cells, and stimulate various biologically programmed responses. Rather than blockages of circulation described in the old Chinese dogma, diseases are understood to be caused by microorganisms, metabolic failures, changes in DNA structure or signaling, or breakdown of the immune system. Some of these disorders are resolved by the cellular functions that are designed for healing, while others become chronic diseases because the pathological factors involved have either defeated the body’s normalizing mechanisms or because something else has weakened the body’s responses to the point that they are ineffective. For example, poor nutrition, unhealthy habits, and high stress can weaken the responses to disease.
Modern studies have revealed that acupuncture stimulates one or more of the signaling systems, which can, under certain circumstances, increase the rate of healing response. This may be sufficient to cure a disease, or it might only reduce its impact (alleviate some symptoms). These findings can explain most of the clinical effects of acupuncture therapy.
According to current understanding, the primary signaling system affected by acupuncture is the nervous system, which not only transmits signals along the nerves that comprise it, but also emits a variety of biochemicals that influence other cells of the body. The nervous system, with over 30 peptides involved in transmitting signals, is connected to the hormonal system via the adrenal gland, and it makes connections to every cell and system of the body.
In a review article, Acupuncture and the Nervous System (American Journal of Chinese Medicine 1992; 20(3–4): 331–337), Cai Wuying at the Department of Neurology, Loyola University of Chicago, describes some of the studies that implicate nervous system involvement. According to a report of the Shanghai Medical University, cranial nerves, spinal nerves, and their terminals were dispersed in the area surrounding the acupuncture points for about 5 millimeters. They also found that the nervous distribution of the Bladder Meridian points (which run along the spine) was in the same area of the spine as that of the corresponding viscera. In Japanese research, it was reported that when acupuncture points were needled, certain neurotransmitters appeared at the site. In laboratory-animal acupuncture studies, it was reported that two such transmitters, substance P and calcitonin gene-related peptide, were released from primary sensory neurons. Acupuncture analgesia appears to be mediated by release of enkephalin and beta-endorphins, with regulation of prostaglandin synthesis: all these have an effect on pain perception. One of the dominant areas of research into acupuncture mechanisms has been its effect on endorphins. Endorphins are one of several neuropeptides; these have been shown to alleviate pain, and have been described as the body’s own “opiates.” One reason for the focus on these biochemicals is that they were identified in 1977, just as acupuncture was becoming popular in the West, and they are involved in two areas that have been the focus of acupuncture therapy in the West: treatment of chronic pain and treatment of drug addiction.
According to traditional Chinese doctors, one of the key elements of a successful acupuncture treatment is having the person who is being treated experience what is called the “needling sensation.” This sensation may vary with the treatment, but it has been described as a numbness, tingling, warmth, or other experience that is not simple pain (pain is not an expected or desired response to acupuncture treatment, though it is recognized that needling certain points may involve a painful response). Sometimes the needling sensation is experienced as propagating from the point of needling to another part of the body. The acupuncturist, while handling the needle should experience a response called “getting qi.” In this case, the needle seems to get pulled by the body, and this may be understood in modern terms as the result of muscle responses secondary to the local nervous system interaction.
According to this interpretation, acupuncture is seen as a stimulus directed to certain responsive parts of the nervous system, producing the needling sensation and setting off a biochemical cascade which enhances healing. Some acupuncture points are very frequently used and their applications are quite varied: needling at these points may stimulate a “global” healing response that can affect many diseases. Other points have only limited applications; needling at those points may affect only one of the signaling systems. It is common for acupuncturists to combine the broad-spectrum points and the specific points for each treatment. Some acupuncturists come to rely on a few of these broad-spectrum points as treatments for virtually all common ailments.
This modern explanation of how acupuncture works does not explain why the acupuncture points are arrayed along the traditional meridian lines. At this time, no one has identified—from the modern viewpoint—a clear series of neural connections that would correspond to the meridians. However, acupuncturists have identified other sets of points, such as those in the outer ear, which seem to be mapped to the whole body. The description, in the case of the ear, is of a layout of the body in the form of a “homunculus” (a miniature humanoid form). Such patterns might be understood more easily than the meridian lines, because the brain, which is adjacent to the ear, also has a homunculus pattern of neurological stimulus that has been identified by modern research. Similarly, acupuncturists have identified zones of treatment (for example, on the scalp or on the hand) that correspond to large areas of the body, and this may also be more easily explained because there are connections from the spinal column to various parts of the body which might have secondary branches elsewhere. In fact, acupuncture by zones, homunculi, “ashi” points (places on the body that are tender and indicate a blockage of qi circulation), and “trigger” points (spots that are associated with muscle groups) is becoming a dominant theme, as the emphasis on treating meridians fades (for some practitioners). The new focus is on finding effective points for various disorders and for getting biochemical responses (rather than regulating qi, though there is no doubt some overlap between the two concepts).
During this modern period (since the 1970’s) an increasing number of ways to stimulate the healing response at various body points have been advocated, confirming that needling is not a unique method (the idea that the needle would produce a hole through which pathogenic forces could escape has long been fading). In the past, the main procedures for affecting acupuncture points were needling and application of heat (moxibustion). Now, there is increasing reliance on electrical stimulation (with or without needling), and laser stimulation. Since the basic idea of acupuncture therapy is gaining popularity throughout the world while the practice of needling is restricted to certain health professions and is not always convenient, other methods are also becoming widely used. Lay persons and practitioners with limited training are applying finger pressure (acupressure), tiny metal balls held to the to the skin by tape, magnets (with or without tiny needles attached), piezoelectric stimulus (a brief electric discharge), and low energy electrical pulsing (such as the TENS unit provides with electrical stimulus applied to the skin surface by taped electrodes). Some of these methods may have limited effectiveness, but it appears that if an appropriate body site is stimulated properly, then the healing response is generated.
For many nervous system functions, timing is very important, and this is the case for acupuncture. The duration of therapy usually needs to be kept within certain limits (too short and no effect, too long and the person may feel exhausted), and the stimulation of the point is often carried out with a repetitive activity (maintained for a minute or two by manual stimulation—usually slight thrusting, slight withdrawing, or twirling—or throughout treatment with electro-stimulation). It has been shown in laboratory experiments that certain frequencies of stimulus work better than others: this might be expected for nervous system responses, but is not expected for simple chemical release from other cells.