Revealing the biological mechanism of acupuncture in alleviating excessive inflammatory responses and organ damage in sepsis: a systematic review.

Sepsis is a systemic inflammation caused by a maladjusted host response to infection. In severe cases, it can cause multiple organ dysfunction syndrome (MODS) and even endanger life. Acupuncture is widely accepted and applied in the treatment of sepsis, and breakthroughs have been made regarding its mechanism of action in recent years. In this review, we systematically discuss the current clinical applications of acupuncture in the treatment of sepsis and focus on the mechanisms of acupuncture in animal models of systemic inflammation. In clinical research, acupuncture can not only effectively inhibit excessive inflammatory reactions but also improve the immunosuppressive state of patients with sepsis, thus maintaining immune homeostasis. Mechanistically, a change in the acupoint microenvironment is the initial response link for acupuncture to take effect, whereas PROKR2 neurons, high-threshold thin nerve fibres, cannabinoid CB2 receptor (CB2R) activation, and Ca2+ influx are the key material bases. The cholinergic anti-inflammatory pathway of the vagus nervous system, the adrenal dopamine anti-inflammatory pathway, and the sympathetic nervous system are key to the transmission of acupuncture information and the inhibition of systemic inflammation. In MODS, acupuncture protects against septic organ damage by inhibiting excessive inflammatory reactions, resisting oxidative stress, protecting mitochondrial function, and reducing apoptosis and tissue or organ damage.

[Research progress and thinking of acupuncture in anti-inflammation by regulating autonomic nerve system].

The nervous system is the necessary condition for inducing the curative effect of acupuncture. Both the sympathetic and vagal nerve systems are widely distributed throughout the body and organically connect various systems and organs of the human body. In maintaining the coordination and unity of human physiological activities, it is in line with the holistic view and bidirectional regulation of acupuncture, and fits in with the meridian theory of "internally belonging to the Zang-fu organs and externally connecting with the limbs and joints". Acupuncture, one of the body surface stimulation therapies, can inhibit the inflammatory response via activating sympathetic/vagus nerve mediated anti-inflammatory pathways. The peripheral nerve innervating diffe-rent acupoints determines the different anti-inflammatory pathways of the autonomic nerve, and different acupuncture methods (stimulation form and stimulation amount) are important factors affecting the anti-inflammatory mechanism of the autonomic nerve. In the future, we should analyze the central integration mechanism between sympathetic nerve and vagus nerve regulated by acupuncture at the level of brain neural circuits, and clarify the "multi-target" advantage of acupuncture, so as to provide inspiration and reference for the study of neuroimmunological effects of acupuncture.

[Current situation and prospect of researches on regularities and mechanisms of acupuncture-moxibustion in alleviating chronic inflammatory response].

The inflammatory response plays an important role in the onset, development and prognosis of inflammatory diseases and a variety of chronic diseases. Long-term uncontrolled inflammatory response may lead to dysfunction or loss of organ tissue function. Clinical practice and evidence-based medicine suggest that acupuncture can effectively alleviate the inflammatory status of various inflammatory diseases and chronic diseases. Stimulation of acupoints related to internal organs and target organs can initiate neuromodulation by modulating the microenvironment of acupoints. After integration of acupuncture stimulus information in the central nervous system, neurotransmitters, hormones, etc. are released and ultimately act on immune cells through neuro-endocrine-immune pathways, such as the vagus-mediated cholinergic anti-inflammatory pathway, vagus nerve-adrenal medullary-dopamine pathway, somatic sympathetic nerve pathway, and hypothalamic-pituitary-adrenal axis, etc. Ultimately, the intracellular signaling pathways and polarization balance of monocytes/macrophages and T cell subsets are regulated and the immune homeo-stasis of target organs of the body realizes. Therefore, we proposed that the anti-inflammatory action of acupuncture may be one of the universal therapeutic strategies for multiple diseases, and a powerful interpretation of acupuncture in regulating the balance of yin and yang. The elucidation of its anti-inflammatory action rules and mechanism may better realize the clinical transformation of acupuncture and moxibustion precision treatment.

[Effect of electroacupuncture at "Zusanli" (ST36) and "Tianshu" (ST25) on intestinal function and autonomic nerve balance in rats with irritable bowel syndrome].

OBJECTIVE: To study whether electroacupuncture (EA) of "Zusanli" (ST36) combined with "Tianshu" (ST25) has a synergistic effect in regulating the colonic function and autonomic nerve balance in rats with irritable bowel syndrome (IBS). METHODS: Male Wistar rats were randomly divided into control, model, EA-ST36, and EA-ST36+ST25 groups, with 14 rats in each group. The IBS model was established by using water avoidance stress method. The visceral hypersensitivity was measured using the abdominal wall retraction reflex (AWR). The rectus abdominis electromyogram (EMG), intestinal electrical activity, and electrocardiogram (ECG) were recorded using a PowerLab data acquisition and analysis system. The contents of serum cAMP and cGMP were determined by ELISA, the expression levels of colonic tyrosine hydroxylase (TH) and choline acetyl-transferase (ChAT) proteins were determined by immunofluorescence staining and Western blot, respectively. RESULTS: Compared with the control group, the model group had an evident increase in the levels of AWR, LF, LF/HF, ChAT protein expression, cAMP and cGMP contents and cAMP/cGMP ratio (P<0.001, P<0.05), and a marked decrease in the levels of HF, frequency of slow waves of intestinal EMG, visceral pain threshold (PT), immunoactivity and expression of TH protein (P<0.05, P<0.001). In contrast to the model group, the levels of AWR, LF, LF/HF, ChAT protein expression and immunoactivity, cAMP and cGMP contents and ratio of cAMP/cGMP were significantly reduced (P<0.001, P<0.05, P<0.01), whereas the levels of frequency of slow waves of intestinal EMG, PT, and the immunoactivity and expression of TH were considerably increased (P<0.001, P<0.05) in both EA-ST36 and EA-ST36+ST25 groups. CONCLUSION: EA of both ST36 and ST36+ST25 can relieve visceral pain, and reduce sympathetic activity to improve autonomic nerve balance, but without apparent synergistic effect between EA-ST36 and EA-ST25 in rats with IBS.

The Dosage Effect of Laser Acupuncture at PC6 (Neiguan) on Heart Rate Variability: A Pilot Study.

Laser acupuncture (LA) has been more applicated in the clinical practice with good responses, but the dosage and parameter settings are still inconsistent with the arguments. This study is focused on the effect of LA on heart rate variability (HRV) with different energy density (ED). Based on the Arndt-Schulz law, we hypothesized that the effective range should fall within 0.01 to 10 J/cm2 of ED, and settings above 10 J/cm2 would perform opposite or inhibitory results. We recruited healthy adults in both sexes as subjects and choose bilateral PC6 (Neiguan) as the intervention points to observe the HRV indexes changes by an external wrist autonomic nerve system (ANS) watch on the left forearm. The data from the ANS watch, including heart rate, blood pressure, and ANS activity indexes, such as low frequency (LF), high frequency (HF), LF%, HF%, LF/HF ratio, and so on, were analyzed by the one-way ANOVA method to test the possible effect. In this study, every subject received all three different EDs of LA in a randomized order. After analyzing the data of 20 subjects, the index of HF% was upward and LF/HF ratio was downward when the ED was 7.96 J/cm2. Otherwise, the strongest ED 23.87 J/cm2 performed the opposite reaction. Appropriately, LA intervention could affect the ANS activities, with the tendency to increase the ratio of parasympathetic and decrease the ratio of sympathetic nerve system activities with statistically significant results, and different ED interventions are consistent with Arndt-Schulz law with opposite performance below and above 10 J/cm2.

[Research progress of acupuncture for peripheral inflammatory response].

Acupuncture can regulate peripheral inflammatory response mainly through somatosensory-vagal/sympathetic nerve-splenic/adrenal/local reflex pathway. Besides, acupuncture may also play an anti-inflammatory role through gut microbiota and neuro-endocrine pathway. The effects of acupuncture have acupoint specificity and time window effect, and are influenced by voltage, current and frequency of electroacupuncture. Future research should focus on the connection and interaction of multiple targets, pathways and mechanisms in the brain, and clarify the multi-target advantages of acupuncture anti-inflammatory.

[Research progress on mechanisms of bidirectional regulation of acupuncture].

Bidirectional regulation is one of the key function of acupuncture. The stimulator, mediator and receptor are the basis while the specificity of acupoints and the multi-target regulation of receptors receiving stimulation signals are the essential link of the bidirectional regulation of acupuncture. The possible mechanisms of bidirectional regulation of acupuncture are discussed in 4 aspects, i.e. homeostasis mechanism, stress reaction, central adaptive regulation and autonomic nerve regulation. Knowing the limitations of bidirectional regulation and exploring suitable researchmethods are proposed to be the key points in future researches.

The role of macrophage polarization and associated mechanisms in regulating the anti-inflammatory action of acupuncture: a literature review and perspectives.

Acupuncture is used in the treatment of a variety of inflammatory conditions and diseases. However, the mechanisms of its anti-inflammatory action are complex and have not been systematically investigated. Macrophages are key components of the innate immune system, thus, balancing the M1/M2 macrophage ratio and modulating cytokine levels in the inflammatory environment may be desirable therapeutic goals. Evidence has shown that acupuncture has anti-inflammatory actions that affect multiple body systems, including the immune, locomotory, endocrine, nervous, digestive, and respiratory systems, by downregulating pro-inflammatory M1 and upregulating anti-inflammatory M2 macrophages, as well as by modulating associated cytokine secretion. Macrophage polarization is controlled by the interlocking pathways of extrinsic factors, the local tissue microenvironment, and the neural-endocrine-immune systems. It has been suggested that polarization of T lymphocytes and cytokine secretions resulting in modulation of the autonomic nervous system and the hypothalamic-pituitary-adrenal axis, may be upstream mechanisms of acupuncture-induced macrophage polarization. We further propose that macrophage polarization could be the principal pathway involved in acupuncture immune regulation and provide the scientific basis for the clinical application of acupuncture in inflammatory conditions.

[Effect characteristics and mechanism of acupuncture in autonomic nerve regulation].

OBJECTIVE: To investigate the effect characteristics and mechanism of acupuncture in autonomic nerve regulation through a comprehensive literature analysis. METHODS: CNKI and PubMed databases were searched for the studies on acupuncture in autonomic nerve regulation in the past 30 years, and Excel was used to perform a descriptive analysis of research subjects, intervention methods, intervention sites (acupoint selection), intervention parameters, and effect mechanism of acupuncture. RESULTS: A total of 202 studies were included, among which there were 51 clinical studies, mostly on the nervous system and the circulatory system; Neiguan (PC6), Zusanli (ST36), Fengchi (GB20), and Hegu (LI4) were the most frequently used acupoints, manual acupuncture was the most common intervention method, most of the acupoints selected were in the extremities, head, face, and neck, and heart rate variability was the main parameter for evaluation. Among the 151 animal experimental studies, there were many studies on the digestive system and the circulatory system; "Zusanli" (ST36), "Neiguan" (PC6), and "Shenmen" (HT7) were the most frequently used acupoints, electroacupuncture was the most common intervention method, most of the acupoints selected were in the extremities, and the main effect mechanism was to regulate the central vagus nerve activity and the cholinergic anti-inflammatory pathway (CAP). CONCLUSION: Acupuncture has a good effect on autonomic nerve regulation. The acupoints in extremities, head, and face are mainly used in studies. The main action pathways are central vagus nerve activity and CAP, as demonstrated in the animal experiments. Acupuncture has specific effect characteristics, which are closely associated with the acupoints, methods, and parameters of stimulation.

Effects of temporary sacral nerve stimulation on gastrointestinal motility and function in patients with chronic refractory slow-transit constipation.

BACKGROUND: The efficacy of sacral nerve stimulation (SNS) on patients with chronic refractory slow-transit constipation is controversial and its mechanism of action on gastrointestinal motility and transit is not fully understood. The aim of this study was to document the effects of temporary SNS on the gastrointestinal and biliary tract motility and on gastrointestinal transit in patients with refractory slow-transit constipation. METHODS: This was a prospective interventional study. Patients with slow-transit chronic constipation, unresponsive to any conservative treatment, were enrolled between January 2013 and December 2018. Patients' quality of life [patient assessment of constipation quality of life (PAC-QOL) questionnaire], constipation scores (Cleveland Clinic Constipation Score) colonic transit time (CTT), orocecal transit time (OCTT), gastric and gallbladder kinetics, together with the assessment of the autonomic nerve function were evaluated before and during temporary SNS. RESULTS: 14 patients (12 females, median age 38 years, range 24-42 years) had temporary SNS. The Cleveland Clinic Constipation Score did not change compared to baseline (23 ± 3 vs 21.4; p = 070). The PAC-QOL did not improve significantly during the stimulation period. Gallbladder/stomach motility (half-emptying time) did not change significantly before and after SNS. OCTT was delayed at baseline, as compared to standard internal normal values, and did not change during SNS. CTT did not improve significantly, although in two patients it decreased substantially from 97 to 53 h, and from 100 to 65 h. CONCLUSIONS: Temporary SNS did not have any effect on upper/lower gastrointestinal motility and transit in patients with severe constipation.

Research progress on mechanisms of bidirectional regulation of acupuncture / 中国针灸

Bidirectional regulation is one of the key function of acupuncture. The stimulator, mediator and receptor are the basis while the specificity of acupoints and the multi-target regulation of receptors receiving stimulation signals are the essential link of the bidirectional regulation of acupuncture. The possible mechanisms of bidirectional regulation of acupuncture are discussed in 4 aspects, i.e. homeostasis mechanism, stress reaction, central adaptive regulation and autonomic nerve regulation. Knowing the limitations of bidirectional regulation and exploring suitable researchmethods are proposed to be the key points in future researches.

Topical intranasal lidocaine is not a sphenopalatine ganglion block.

There is renewed interest in the central role of the sphenopalatine ganglion (SPG) in cerebrovascular autonomic physiology and the pathophysiology of different primary and secondary headache disorders. There are diverse neural structures (parasympathetic, sympathetic and trigeminal sensory) that convene into the SPG which is located within the pterygopalatine fossa (PPF). This makes the PPF an attractive target to neuromodulatory interventions of these different neural structures. Some experts advocate for the nasal application of local anesthetics as an effective route for SPG block with the belief that the local anesthetic can freely access the PPF. It is time to challenge this historical concept from the early 1900s. In this daring discourse, I will review anatomical studies, CT and MRI reports to debunk this old myth. Will provide anatomical evidence to explain that all these assumptions are untrue and the local anesthetic has to magically 'travel' a distance of 4-12 mm of adipose and connective tissue to reach the SPG in sufficient concentration and volume to effectively induce SPG blockade. Future research should focus on assessing a clinical biomarker to confirm SPG blockade. It could be regional cerebral blood flow or lacrimal gland secretion.

Ubiquinol-10 Intake Is Effective in Relieving Mild Fatigue in Healthy Individuals.

Our double-blind, placebo-controlled study evaluated effects of ubiquinol, the reduced form of coenzyme Q10, on mild fatigue in healthy individuals experiencing fatigue in daily life that had continued for more than 1 and less than 6 months. The participants received 100-mg/day (Ubq100; age 44.0 ± 9.8 years; 14 females and 6 males) or 150-mg/day ubiquinol (Ubq150; age 40.4 ± 11.8 years; 14 females and 8 males) or placebo (Plc; age 41.3 ± 13.4 years; 13 females and 7 males) daily for 12 weeks. Measurements of subjective and objective fatigue were conducted by using questionnaires-based fatigue scales/visual analogue scales and autonomic nerve function/biological oxidation index, respectively, prior to the first dosing and every 4 weeks thereafter. Serum ubiquinol level increased three- to four-fold after 4 weeks and remained significantly higher than that after Plc administration throughout the intake period. Although a higher blood level of ubiquinol was observed with Ubq150 than with Ubq100, the difference was not statistically significant. In both Ubq100 and Ubq150 groups, subjective levels of fatigue sensation and sleepiness after cognitive tasks, which consisted of the modified Advanced Trail Making Test, the modified Stroop Color-Word Test, and the Digit Symbol Substitution Test, improved significantly compared with those in the placebo group, suggesting an anti-fatigue effect. The Ubq150 group demonstrated significant improvement compared with the Plc group regarding subjective level of relaxation after task, sleepiness before and after task, motivation for task, and serum level of oxidative stress. Correlation analysis between blood level of ubiquinol and each evaluated effect suggested a positive relationship with relaxation after task, motivation for cognitive task, and parasympathetic activity. The results of the study suggest that ubiquinol intake relieves mild fatigue in healthy individuals.

Bepridil Inhibits Premature Ventricular Complexes Induced by Cardio-Sympathetic Nerve Stimulation in a Canine Experimental Model.

Sympathetic nerve activity has arrhythmogenic potential for ventricular arrhythmias associated with structural heart diseases. However, a sufficient amount of beta-blockers occasionally cannot be prescribed in some patients.An experimental study was performed to clarify the therapeutic effects of bepridil, a multiple ionic current inhibitor that does not affect beta-adrenergic receptors, for premature beats occurring during enhanced sympathetic nerve activity. Cardio-sympathetic nerve activity was augmented via stellate-ganglion (SG) stimulation in a canine model (n = 8), and the arrhythmogenic potential and anti-arrhythmic effects of bepridil (2 and 4 mg/kg intravenously) were assessed. For safe use, vagal-stimulation-induced slow HR and programmed electrical stimulation were applied to evaluate possible pro-arrhythmic effects of the drug. Heart rate variability (HRV) indexes were used to estimate cardio-autonomic nerve activity.Either side of the SG-stimulation increased BP and HR. Premature beats were induced in 10/16 SG-stimulations and it was more frequent in left (8/8) rather than right stimulation (2/8). Following 2 mg/kg drug administration, premature beats were still inducible in 8/16 stimulations (7/8 in left and 1/8 in right), but burden of the premature beats decreased from 87.1 ± 46.8 to 62.1 ± 42.6 beats. After 4 mg/kg administration, premature beats were inducible in one SG-stimulation. Proarrhythmic effects were not observed in all experiments. Steady-state HRV indexes and percent increases in SG-stimulation-induced BP-elevation and HR-acceleration were similar among the 3 periods (before, 2 and 4 mg/kg of the drug).Bepridil may be an option for ventricular arrhythmias developed during enhanced cardio-sympathetic nerve activity with minimal effect on autonomic nerve responses.

Increase in diastolic blood pressure induced by fragrance inhalation of grapefruit essential oil is positively correlated with muscle sympathetic nerve activity.

Fragrance inhalation of essential oils is widely used in aromatherapy, and it is known to affect blood pressure (BP) and heart rate (HR) via autonomic control of circulation. In this study, we aimed to test the hypothesis that the changes in hemodynamics with fragrance inhalation were observed along with changes in muscle sympathetic nerve activity (MSNA). In study 1, thirteen healthy men were exposed to fragrance stimulation of grapefruit essential oil for 10 min, and BP, HR, and MSNA were continuously measured. In study 2, another nine healthy men were exposed to the same fragrance stimulation; responses in BP and HR were continuously measured, and plasma noradrenaline and cortisol concentrations were determined. We found that diastolic BP increased significantly during fragrance inhalation, while the other variables remained unchanged in both studies. Although MSNA burst frequency, burst incidence, and total activity remained unchanged during fragrance inhalation, we found a significant linear correlation between changes in diastolic BP in the last 5 min of fragrance inhalation and changes in MSNA burst frequency. The plasma cortisol concentration decreased significantly at 10 min of fragrance inhalation, though the noradrenaline concentration remained unchanged. These results suggest, for the first time, that changes in BP with fragrance inhalation of essential oil are associated with changes in MSNA even with decreased stress hormone.

Didgeridoo Health Promotion Method Improves Mood, Mental Stress, and Stability of Autonomic Nervous System.

A potential method of health promotion using the traditional wooden brass instrument the didgeridoo was examined, especially in terms of mood, stress, and autonomic nerve stabilization. Twenty Japanese healthy subjects undertook 10 lessons of the Didgeridoo Health Promotion Method (DHPM) and a moods questionnaire, blood pressure, salivary amylase (sAmy) as a stress marker, pulse rate and autonomic balance expressed by Ln[low frequency (LF)/High frequency (HF) were examined twice before the entire lessons and once before and after each lesson. The subjects had improved total mood disturbance (TMD: overall mood disorder degree) as measured by the Japanese version of the Profile of Mood States 2nd Edition (POMS2) as a result of taking the lessons. The pulse of the subjects decreased after the lessons, which correlated with a reduction in sAmy. Additionally, it was found that sAmy decreased after the lessons with increasing age of the subject, subjects with higher TMD before the lessons, or subjects with higher sAmy values before the lessons. With autonomic balance measured by Ln[LF/HF], subjects who had parasympathetic dominance as a result of the lesson were significantly more frequent. Additionally, it has been shown that Ln[LF/HF] decreased over 10 weeks, and it is also clear that the effect is sustained. Health promotion is an important concern for societies as a whole. In this study, it became clear that the DHPM affected mood, stress, and autonomic stability. Future studies should focus on monitoring the effects of continuing the lessons for a longer period of time. Additionally, physical effects such as strength of respiratory muscles should be examined. DHPM may be employed in the work place to promote the mental health of workers as well as in regional neighborhood associations/communities.

Elevation of Lower Esophageal Sphincter Pressure With Acute Transcutaneous Electrical Acustimulation Synchronized With Inspiration.

BACKGROUND: Gastroesophageal reflux disease (GERD) is a common esophageal disorder. Transcutaneous electrical acustimulation (TEA), as a needleless method of electroacupuncture (EA) has been reported to improve hypotensive lower esophageal sphincters pressure (LESP) in GERD. Synchronized TEA (STEA) with inspiration has been revealed to be more effective than TEA in enhancing vagal tone. AIM: To explore the effect of STEA on LESP in GERD and possible mechanisms involving autonomic functions. METHODS: Sixty patients were randomly allocated into a STEA group (45 patients) and sham-TEA group (15 patients). The ECG was recorded for the assessment of the autonomic function, followed with an esophageal high-resolution manometry (HRM) test. When the test was completed, the STEA or sham-TEA treatment was performed for 30 minutes. Then the HRM test was repeated. RESULTS: STEA increased LESP from 21.9 to 31.9 mmHg in GERD patients (p < 0.001). A negative correlation between the percentage of STEA-induced increase in LESP and basal LESP was observed (R = -0.471, p = 0.001). STEA reduced the number of ineffective esophageal contractions (p < 0.05). STEA rather than sham-TEA increased vagal activity (0.27 ± 0.14 vs. 0.36 ± 0.18, p < 0.001) and decreased sympathetic activity (0.73 ± 0.14 vs. 0.64 ± 0.18, p < 0.001). CONCLUSIONS: Acute STEA augments LESP in GERD and the percentage of the increase in LESP was negatively correlated with basal LESP. The effect of STEA on LESP might be mediated via autonomic function. CONFLICT OF INTEREST: The authors reported no conflict of interest.

The cardiac autonomic nervous system: A target for modulation of atrial fibrillation.

The cardiac autonomic nerve system (CANS) is a potentially potent modulator of the initiation and perpetuation of atrial fibrillation (AF). In this review, we focus on the relationship between the autonomic nervous system (ANS) and the pathophysiology of AF and the potential benefit and limitations of neuromodulation in the management of this arrhythmia from eight aspects. We conclude that Activation and Remodeling of CANS involved in the initiation and maintenance of AF. The network control mechanism, innervation regions, and sympathetic/parasympathetic balance play an important role in AF substrate. And the formation of Complex Fractional Atrial Electrograms also related to CANS activity. In addition, modulating CANS function by potential therapeutic applications include ganglionated plexus ablation, renal sympathetic denervation, and low-level vagal nerve stimulation, may enable AF to be controlled. Although the role of the ANS has long been recognized, a better understanding of the complex interrelationships of the various components of the CANS will lead to improvement of treatments for this common arrhythmia.

Vagus nerve stimulation reduces ventricular arrhythmias and increases ventricular electrical stability.

BACKGROUND: Transcutaneous stimulation of the auricular branch of the vagus nerve (AB-VNS) is a potentially noninvasive, inexpensive, and safe approach for vagus nerve stimulation that suppresses the induction and duration of atrial fibrillation and reduces sympathetic nerve outflow in healthy humans. Researchers have not determined whether AB-VNS affects ventricular arrhythmias. OBJECTIVE: To evaluate the antiarrhythmic effects of noninvasive AB-VNS on ventricular arrhythmias induced by myocardial infarction (MI). METHODS AND RESULTS: Twelve beagle dogs were randomly divided into the following two groups: a AB-VNS group (coronary artery occlusion and noninvasive AB-VNS) and a control group (coronary artery occlusion but without AB-VNS). We examined spontaneous ventricular arrhythmias, ventricular electrophysiological properties, and cardiac function in conscious dogs. Morphology, fibrosis, and ultrastructures were also assessed. AB-VNS significantly reduced the occurrence of spontaneous ventricular arrhythmias, including isolated premature ventricular complexes, ventricular couplets, ventricular bigeminy, ventricular trigeminy, and ventricular tachycardia. AB-VNS effectively increased ventricular electrical stability, including significantly prolonged ventricular effective refractory periods, decreased the dispersion of effective refractory period, enhanced the ventricular fibrillation threshold, and decreased the maximum slope of the monophasic action potential duration restitution curve. AB-VNS treatments alleviate ventricular interstitial fibrosis after MI. However, cardiac function was not improved, and MI-induced ultrastructural changes in the myocardium were not reversed by 4 weeks of AB-VNS. In addition, AB-VNS for 4 weeks resulted in mild mitochondrial swelling within the neuronal axons of the auricular vagus fiber. CONCLUSIONS: Noninvasive AB-VNS reduces the occurrence of spontaneous ventricular arrhythmias in conscious dogs with MI. AB-VNS increases ventricular electrical stability and alleviates ventricular interstitial fibrosis induced by MI.