Happy World Moxa Day! – with a neurological explanation for why St36 is so effective with moxa
We came across this paper recently, and found it intriguing, and figure it’s worth discussing on this World Moxa Day (May 9th) because of what it implies. A neuroanatomical basis for electroacupuncture to drive the vagal–adrenal axis | Nature
Okay, it’s a bit technical. What’s more it’s about the effect of electro-acupuncture stimulation (ES) on a specific point, and EA most certainly isn’t small cone moxa (or indirect moxa if that’s your bag). In other words, we should be cautious about exactly how we draw any conclusions and not go over the top about it. Nevertheless, what it exposes about the neuro-anatomical connections of the St36 point is fascinating, but may also help explain why St36 has been so favoured as a key point for moxa over the centuries and (more recently) why it has been the ‘go to’ point for moxa researchers in East Asia in respect of moxa’s undeniable effects on the immune system.
So let’s dig in and get a little more technical.
What does the paper propose?
First of all it acknowledges that “somatosensory autonomic reflexes … modulate body physiology at distant sites (for example, suppressing severe systemic inflammation.” So far so good? Stimulating a distal point can promote a systemic effect, right?
It then joins up a few more dots to paint an even more interesting picture: “For example” the authors write, “ES at the hindlimb ST36 acupoint … can drive the vagal–adrenal anti-inflammatory axis in mice.”
Ahah! Maybe now you see why we found this interesting!
The research was led by Professor Qiufu Ma who is a neurobiologist at Harvard. He studies pain but has been particularly curious about the biological underpinnings of acupuncture. Previously his team has shown how activating these ‘somatosensory autonomic reflexes’ can play a vital role in reducing systemic inflammation (once again done by electroacupuncture stimulation).
This study, however, homes in on a specific subset of sensory neurons (PROKR2 Cre -marked sensory neurons) which innervate the deep leg fascia and identifies that they are crucial for driving the vagal–adrenal axis. In this case, they were stimulated at the St36 point.
PROKR2? No, we’d never heard of them either – all we can say is that prokineticin receptor 2 (PROKR2) neurons are predominantly expressed in the mammalian central nervous system and this paper suggests that they can be stimulated at St36.
And the ‘vagal-adrenal axis’? Well, many of us already know quite a bity about that one because it has been eliciting so much recent interest, not least in its capacity to modulate both the autonomic system (ANS) and immune system and connects both brain and gut. It’s a huge subject, but we think we can reasonably state here that it helps regulate the body’s response to stress, promotes immune function, and manages energy expenditure, mood, emotions and libido.
So why Bring this up on World Moxa Day?
Well, simply because on this day of all days we want to encourage the daily self-application of small cone direct moxa to St36. Back in 1933 our inspiration, Dr Shimetaro Hara, encouraged this practice (himself living to the age of 108, and still practising medicine after passing a hundred) – ‘it is so simple’, he wrote, “that it feels like a lie”. Sometimes it feels the same to us!
We suspect that Dr Hara would have found this recent paper very interesting indeed! It certainly encourages us to keep moxa-ing daily (stimulating our prokineticin receptors!). Maybe it will do the same for you!
Happy World Moxa Day, folks!.
A couple of necessary cautions about the above:
Of course, we should note that the research quoted above was done on laboratory mice (which makes us reluctant to quote it at all). We hope you’ll forgive us for doing so. But can it be reasonably extrapolated to humans anyway? We think it probably can be, though obviously more research is needed to be sure. These PROKR2 neurons are common to mammals, including humans.
And we should also repeat that this research used EA, so we can’t just assume that small cone direct moxa provokes a similar response. But since we have been convinced for some time that moxa’s immunomodulatory effects work via more than one mechanism (including ANS modulation, but also via transient receptor potential cation channels (TRPV’s) which are also a part of the mammalian somatosensory system we believe that a similar mechanism to what is discussed above is highly plausible.
And as it’s highly unlikely that anyone is going to do any similar research using moxa, so this is as good as we’re likely to get…