LAUSR

Overexcitation of sympathetic activity strongly related to increased blood pressure (BP) is decreased by electroacupuncture (EA). Reflex elevated BP response and elevated neuronal activity in the rostral ventrolateral medulla (rVLM), a central region for sympathetic outflow are reduced by stimulation of somatosensory nerves during a 30 min EA. However, it is unclear if the medullary nucleus ambiguus (NA) related to parasympathetic activity also is influenced by EA during elevated BP. In hypertensive subjects, EA therapy over deep peroneal and tibial nerves (ST36-37+SP6-7) decreases high BP. We hypothesize that a course of EA treatments decreases high BP by reducing rVLM and simultaneously increasing NA neuronal activity in hypertensive rats. Dahl salt-sensitive rats were fed either a standard rat diet or 4% salt rat diet developing hypertension. Normotensive control rats were acclimated to handling and restraining while Sham-EA (absence of electrical input to acupuncture needles) and EA treated hypertensive rats were acclimatized also to needling. Sham-EA or EA was given twice a week for 30 minutes in awake hypertensive rats for 5 weeks. BPs were measured with tail-cuff CODA system. At end of 10 weeks, tyrosine hydroxylase (TH) and choline acetyltransferase (ChAT) neuronal (NeuN) expressions were evaluated by immunohistochemistry as well as neuronal activity were determined by extracellular recordings in the rVLM and NA in Sham-EA, EA treated rats, and control rats. BP of control rats was at 130.3±1.7 mmHg (n=6) at end of experiment. BP significantly decreased by 25.9% in EA treated (138.04±1.8 mmHg, n=6) compared to Sham-EA (186.3±2.3 mmHg, n=7) hypertensive rats. Cardiovascular pre-sympathetic neuronal activity in rVLM significantly was decreased by 43% (1.33±0.10 to 0.75±0.13 sp/s, n=10) while the pre-parasympathetic activity in NA was increased by 96% (0.70±0.08 to 1.37±0.13 sp/s, n=12) in EA compared to Sham-EA treated hypertensive rats. Control rats rVLM activity was 0.23± 0.07 sp/s (n=4) and NA activity was 2.71±0.56 sp/s (n=5). Also, numbers of rVLM neurons expressing TH and NeuN were decreased (from 96 to 73) and NA neurons expressing ChAT and NeuN were increased (from 35 to 107) in Sham-EA compared to EA treated hypertensive rats. In normal control rats, rVLM showed 69 TH neurons and NA demonstrated 134 ChAT neurons. In conclusion, the BP lowering EA effect likely involved central autonomic rebalance by activating both sympathoinhibition and parasympathoexcitation. National Institute of Health National Center for Complementary & Integrative Health Grant AT011306 This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.