Altered immune response is involved in the occurence of diabetes, arthritis, allergies and perhaps even autism. So in medicine, immunity is a key area of research. The current issue of Scientific American has a synopsis written by Kevin Tracey, one of the founders of Set Point Medical. We’ve talked about their bioelectric company on the blog before. What he has found is that the vagus nerve is involved with decreasing the inflammatory response, or rather regulates the inflammatory response by feeding back on the spleen which in the end decreases Tumor Necrosis Factor, a marker of inflammation.
This research relates intimately to my studies looking at the effect of acupuncture on the vagal activity of the heart (this is what HRV measures). So where Set Point medical is implanting electrical stimulation devices to stimulate vagal activity, I am trying to augment vagal activity through acupuncture. So most likely acupuncture decreases pain in inflammatory conditions partly by increasing vagal activity. The way he describes the reflex arm might work like this:
Il1 or interleukin 1-which is produced with fever, for example, stimulates the vagus nerve which leads to the base of the brain. The motor or efferent branch of the vagus then fires and stimulates the celiac ganglion which stimulates the spleen. Here, Norepinephrine is released which acts on Tcells to produce acetylcholine. Acetylcholine then acts on the macrophages which down regulate the Tumor necrosis factor.
An additional factor that I didn’t know was that Tracey tried the experiment in rats with an inactive pituitary, and it still worked. That implies that steroids (corticosteroids) are NOT involved in this anti-inflammatory effect.
I still maintain that studying HRV may give us some idea of how much vagal activity we are achieving with acupuncture. It’s completely unclear how long that effect is lasting though. Even though I’ve seen an improvement with HRV over months to years in many patients, it doesn’t always happen. But given the implicit importance of vagal activity in the inflammatory and immune response, I’m very gratified that I’ve been looking at it for so long. Even though I haven’t had any breakthroughs yet!!