How does acupuncture work?

This is perhaps the most simple and natural question about acupuncture but it’s actually more complex than it might seem and the answer depends upon the perspective from which one is asking – there is acupuncture as conceived by the Chinese 2000 years ago, and there is acupuncture as conceived now by conventional medicine in the 21^stcentury. In many ways the two can be seen to overlap and to communicate about the same thing, just in different language. This is the first of two articles exploring how acupuncture works, and here we will focus on the modern day conventional view.

What modern science has to say about acupuncture

Although it is still partial, there is now a good basic understanding of how acupuncture works – particularly in relation to its potential to reduce pain. The wider capabilities of acupuncture are not so well understood, and it is likely that there are additional mechanisms not yet discovered. The mechanisms that are understood can be categorised in the following way:

1)      Local effects in the tissues surrounding the needle

2)      Segmental effects affecting portions of the body supplied by common nerve pathways

3)      Extra segmental effects occurring in the brain in the form of neuropeptide release

4)      Central regulatory effects occurring throughout the whole human system.

 

Local effects in the tissues surrounding the needle

As soon as a needle is inserted into the body it begins to stimulate the nervous system. A nerve in response to being stimulated by a needle soon begins to release a chemical called calcitonin gene related peptide (CGRP). CGRP is a vasodilator which means it dilates blood vessels thereby increasing blood flow to the immediate area. This stimulates tissue repair and aids recovery.

Segmental effects affecting portions of the body supplied by common nerve pathways

At the same time as CGRP is being released, the stimulated nerve, in what’s known as an axon reflex, continues to propagate the stimulation up into a portion of the spinal cord called the dorsal horn. Here local cells release enkephalin which is a chemical that blocks further stimulation from the nerve. As nerves supply wide portions of the body a needle inserted in one area will hamper further stimulation from a wider area around it. This is termed segmental analgesia and an additional effect of it is to soften muscle tone in the area thereby dissipating tension. One could understand the action of enkephalin in the dorsal horn as the equivalent of a red light at a traffic light that halts the progress of further traffic i.e. it stops the progress of pain messages. As nerves supply and run off organs as well as muscles, acupuncture can help block pain messages coming from both.

Extra segmental effects occurring in the brain in the form of neuropeptide release

It is acupuncture’s effects in the brain that correspond to its capacities to effect change in a wide range of conditions.

Continuing up from the spinal cord the stimulated nerve propagates up and into the brain and across several portions of it. This in turn stimulates the production of:

ACTH (Adrenocorticotropic hormone) – a hormone which increases the production of corticosteroid thereby reducing inflammation

Endorphin – which further increases analgesia and promotes a sense of well being

Serotonin – which increases the further production of enkephalin, thereby reinforcing analgesia and feelings of wellness.

Noradrenaline – which further inhibits pain messages from the dorsal horn in the spinal cord

It is also hypothesised that oxytocin may be an important component in the sedating and calming effects that acupuncture induces, and also that the hypothalamo-pituitary ovarian axis is brought into balance by secretion of endorphin and ACTH. This mechanism may explain how acupuncture is able to regulate menstrual flow and duration and also to reduce the pain associated with the period.

Central regulatory effects occurring throughout the whole human system.

Once the axon reflex affects the brain it exerts an influence over the limbic system. The limbic system is the portion of the brain responsible for the affective component of illness as opposed to the sensory aspect of it, and when affected by acupuncture it typically reduces the sense of distress that pain and ill health can cause. An example would be experiencing a headache but with a reduced sense of distress that the pain might usually cause. It is this mechanism that could account for the sense that many patients get from acupuncture, which is the feeling of being happier, more relaxed, and more able to cope with life.

So to conclude our brief tour of the conventional perspective we can see that acupuncture produces inhibition of pain from peripheral nerve stimulation blocking pain messages from below, and induces the production of pain killing chemicals from above in the brain. This produces typical experiences of calmness and well being. In terms of the wider effects of acupuncture, this is thought to occur through various structures in the brain whose stimulation results in the production and secretion of a variety of different chemicals which exert widespread influence throughout the whole human system.