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Medical Research

Brain Physiology Behind Electroacupuncture’s Modulating Effect on Blood Pressure

Kristen Sparrow • May 25, 2016

Nice.  This article appears in Nature, quite a coup. There is a lot about this paper that surprises me.  Perhaps I’m just not familiar enough with this type of experimental set up, and haven’t been aware of these studies.   What they found was that naloxone interfered with the suppression of blood pressure by electroacupuncture in anesthetized cats.  So even though the cats were under general anesthesia, electroacupuncture still produced an endogenous opiate response which triggered top down modulation of cardiovascular excitability.  Somehow, I would have thought that general anesthetic would obliterate this sort of reflex, and I would have been wrong!
Full free text here.    In the article they give a nice summary of all of their work on the brain mechanisms involved in the hypotensive effects of acupuncture.
This group used P5-P6 electroacupuncture in their studies on hypertension control in human subjects, and I just don’t have the heart to use this combination in the clinic.  It hurts!
Sci Rep. 2016 May 16;6:25910. doi: 10.1038/srep25910.

Paraventricular Nucleus Modulates Excitatory Cardiovascular Reflexes during Electroacupuncture.

Tjen-A-Looi SC1, Guo ZL1, Fu LW1, Longhurst JC1.

Author information

Abstract

The paraventricular nucleus (PVN) regulates sympathetic outflow and blood pressure. Somatic afferent stimulation activates neurons in the hypothalamic PVN. Parvocellular PVN neurons project to sympathoexcitatory cardiovascular regions of the rostral ventrolateral medulla (rVLM). Electroacupuncture (EA) stimulates the median nerve (P5-P6) to modulate sympathoexcitatory responses. We hypothesized that the PVN and its projections to the rVLM participate in the EA-modulation of sympathoexcitatory cardiovascular responses. Cats were anesthetized and ventilated. Heart rate and mean blood pressure were monitored. Application of bradykinin every 10-min on the gallbladder induced consistent pressor reflex responses. Thirty-min of bilateral EA stimulation at acupoints P5-P6 reduced the pressor responses for at least 60-min. Inhibition of the PVN with naloxone reversed the EA-inhibition. Responses of cardiovascular barosensitive rVLM neurons evoked by splanchnic nerve stimulation were reduced by EA and then restored with opioid receptor blockade in the PVN. EA at P5-P6 decreased splanchnic evoked activity of cardiovascular barosensitive PVN neurons that also project directly to the rVLM. PVN neurons labeled with retrograde tracer from rVLM were co-labeled with μ-opioid receptors and juxtaposed to endorphinergic fibers. Thus, the PVN and its projection to rVLM are important in processing acupuncture modulation of elevated blood pressure responses through a PVN opioid mechanism.