By Shen-Bin Liu

Acupuncture has been practiced for thousands of years in China and now all over the world. Here we used the modulation of severe systemic inflammation as an experimental model system, and explored the underlying neuroanatomical basis.

We first found that sympathetic neurons expressing the neuropeptide Y (NPY) have dense innervation in immune organs (such as the spleen). We then used genetic tools to ablate, silence or activate these sympathetic cells in mice, followed by testing the impact on acupuncture effects. By inserting a pair of electrodes to deliver electric currents to different body regions, we uncovered several rules on how electroacupuncture (EA) drives distinct autonomic nervous pathways and modulates systemic inflammation:

First, there is an somatotopic organization. EA can drive the vagal-adrenal axis from the hindlimb region, but not from the abdominal region, arguing the presence of regional specificity in driving a particular autonomic nervous pathway.

Second, there is an intensity dependence. While low-intensity EA at the hindlimb region is sufficient to drive the vagal-adrenal axis, high-intensity EA, at both hindlimb and abdominal regions, is required to drive splenic sympathetic pathways.

Third, there is a disease-state dependence. Splenic sympathetic pathways, activated by high-intensity ES, can reduce inflammation, if EA is performed before the onset of systemic inflammation. However, if EA is performed after inflammation has reached the peak, it could make worse inflammation and becomes detrimental for animals. This is due to dynamic changes of adrenergic receptors in immune cells that have opposing impact on inflammation. In contrast, the vagal-adrenal axis, evoked by low-intensity EA at the hindlimb region, can both prevent and treat severe systemic inflammation, in a disease state-independent manner.

Our studies bring new scientific credentials for the ancient acupuncture practices, and may help to treat fatal systemic inflammation for patients with severe bacterial or viral infections (such as COVID-19 patients), or for some cancer patients receiving immune therapy.

Shen-Bin Liu is a postdoc in the lab of Qiufu Ma at the Dana-Farber Cancer Institute and the Harvard Medical School Department of Neurobiology.

Learn more in the original research article:
Liu S, Wang ZF, Su YS, et al.
Somatotopic Organization and Intensity Dependence in Driving Distinct NPY-Expressing Sympathetic Pathways by Electroacupuncture [published online ahead of print, 2020 Aug 8]. Neuron. 2020;S0896-6273(20)30532-8. doi:10.1016/j.neuron.2020.07.015