Autonomic modulation by low-intensity focused ultrasound stimulation of the vagus nerve

Author: Ning Ji1,2, Yuanheng Li2, Jingjing Wei2,3, Fei Chen4, Lisheng Xu1, Guanglin Li2, Wan-Hua Lin2
1 College of Medicine and Biological Information Engineering, Northeastern University, Shenyang 110819, People's Republic of China.
2 CAS Key Lab of Human-Machine Intelligence-Synergy Systems and Research Center for Neural Engineering, Shenzhen Institutes of Advanced Technology (SIAT), Chinese Academy of Sciences (CAS), Shenzhen 518055, People's Republic of China.
3 Department of Human Anatomy, Zhuhai Campus of Zunyi Medical University, Zhuhai 519041, People's Republic of China.
4 Department of Electrical and Electronic Engineering, Southern University of Science and Technology, Shenzhen 518055, People's Republic of China.
Conference/Journal: J Neural Eng
Date published: 2022 Dec 16
Other: Volume ID: 19 , Issue ID: 6 , Special Notes: doi: 10.1088/1741-2552/aca8cd. , Word Count: 259

Objective.Our previous study has shown that low-intensity focused ultrasound stimulation (FUS) of the vagus nerve could modulate blood pressure (BP), but its underlying mechanisms remain unclear. We hypothesized that low-intensity FUS of the vagus nerve would regulate autonomic function and thus BP.Approach.17 anesthetized spontaneously hypertensive rats were treated with low-intensity FUS of the left vagus nerve for 15 min each trial. Continuous BP, heart rate, respiration rate (RR), and core body temperature were simultaneously recorded to evaluate the effects on BP and other physiological parameters. Heart rate variability (HRV), systolic BP variability, and baroreflex sensitivity were computed to evaluate the autonomic modulation function. A Control-sham group without stimulation and another Control-FUS group with non-target stimulation were also examined to exclude the influence of potential confounding factors on autonomic modulation.Main results.A prolonged significant decrease in BP, pulse pressure, RR, the normalized low-frequency power of HRV, and the low-to-high frequency power ratio of HRV were found after the low-intensity FUS of the left vagus nerve in comparison with the baseline and those of the control groups, demonstrating that activities of the sympathetic nervous system were inhibited. The prolonged significant increase of the normalized high-frequency power of HRV suggested the activation of parasympathetic activity.Significance.Low-intensity FUS of the left vagus nerve effectively improved the autonomic function by activating parasympathetic efferent and inhibiting sympathetic efferent, which contributes to BP reduction. The findings shed light on the hypotensive mechanism underlying FUS.

Keywords: autonomic modulation; blood pressure modulation; heart rate variability; hypertension; low-intensity focused ultrasound stimulation.

PMID: 36541473 DOI: 10.1088/1741-2552/aca8cd