Effect of auricular acupuncture on gastrointestinal motility and its relationship with vagal activity

Auricular Acupressure in Relieving PONV and Promoting Gastrointestinal Function Recovery in Females After Laparoscopic Sleeve Gastrectomy: A Prospective Randomized Controlled Trial

BACKGROUND

The role of current pharmacological treatment after laparoscopic sleeve gastrectomy (LSG) is limited. The incidence of postoperative nausea and vomiting (PONV) after LSG remains high. Auricular acupressure (AA) is believed to relieve PONV after laparoscopic surgeries, but its role in patients with obesity after LSG has yet to be confirmed.

METHODS

Ninety-five female patients who underwent LSG were randomized into two groups: AA combined with conventional anti-nausea medication (AA group, 47 patients) or conventional anti-nausea medication group (control group, 48 patients). Index of nausea and vomiting and retching (INVR) scores, postoperative anti-vomiting medication use, time of first anus exhausting, time of first fluid intake, and time of first to get out of bed were collected within 48 h after surgery.

RESULTS

Demographic data of patients in both groups were balanced and comparable. INVR score (F = 7.505, P = 0.007), vomiting score (F = 11.903, P = 0.001), and retching score (F = 12.098, P = 0.001) were significantly lower in the AA group than that in the control group within 48 h postoperatively. Use of metoclopramide was significantly less in the AA group than in the control group (4.7 [5.5]) vs. 8.8 [7.6], P = 0.004); time to first anus exhausting was significantly less in the AA group than in the control group (17.50 [6.00] vs. 20.42 [8.62], P = 0.020).

CONCLUSIONS

AA combined with conventional anti-vomiting agents can alleviate PONV in female patients after LSG, and AA can promote gastrointestinal exhaustion.

TRIAL REGISTRATION

The trial has been registered in the Chinese Clinical Trial Registry (ChiCTR) with the registration no. ChiCTR2100047381 on June 13, 2021.

Ameliorating effects of transcutaneous auricular vagus nerve stimulation on a mouse model of constipation-predominant irritable bowel syndrome

Limited treatment options have been shown to alter the natural course of constipation-predominant irritable bowel syndrome (IBS-C). Therefore, safer and more effective approaches are urgently needed. We investigated the effects of transcutaneous auricular vagus nerve stimulation (taVNS) in a mouse model of IBS-C. In the current study, C57BL/6 mice were randomly divided into normal control, IBS-C model control, sham-electrostimulation (sham-ES), taVNS, and drug treatment groups. The effects of taVNS on fecal pellet number, fecal water content, and gastrointestinal transit were evaluated in IBS-C model mice. We assessed the effect of taVNS on visceral hypersensitivity using the colorectal distention test. 16S rRNA sequencing was used to analyze the fecal microbiota of the experimental groups. First, we found that taVNS increased fecal pellet number, fecal water content, and gastrointestinal transit in IBS-C model mice compared with the sham-ES group. Second, taVNS significantly decreased the abdominal withdrawal reflex (AWR) score compared with the sham-ES group, thus relieving visceral hyperalgesia. Third, the gut microbiota outcomes showed that taVNS restored Lactobacillus abundance while increasing Bifidobacterium probiotic abundance at the genus level. Notably, taVNS increased the number of c-kit-positive interstitial cells of Cajal (ICC) in the myenteric plexus region in IBS-C mice compared with the sham-ES group. Therefore, our study indicated that taVNS effectively ameliorated IBS-C in the gut microbiota and ICC.

Neuromodulation and Functional Gastrointestinal Disease

INTRODUCTION

Functional gastrointestinal disorders (FGIDs) are common, and they severely impair an individual's quality of life. The mechanism of pathogenesis and the effective treatments for FGIDs remain elusive. Neuromodulation-a relatively new treatment-has exhibited a good therapeutic effect on FGIDs, although there are different methods for different symptoms of FGIDs.

MATERIALS AND METHODS

We used PubMed to review the history of neuromodulation for the treatment of FGIDs and to review several recently proposed neuromodulation approaches with improved effects on FGIDs.

CONCLUSION

Electroacupuncture, transcutaneous electroacupuncture, transcutaneous auricular vagal nerve stimulation, sacral nerve stimulation (SNS) (which relies on vagal nerve stimulation), and gastric electrical stimulation (which works through the modulation of slow waves generated by the interstitial cells of Cajal), in addition to the noninvasive neurostimulation alternative approach method of SNS-tibial nerve stimulation and transcutaneous electrical stimulation (which is still in its infancy), are some of the proposed neuromodulation approaches with improved effects on FGIDs. This review has discussed some critical issues related to the selection of stimulation parameters and the underlying mechanism and attempts to outline future research directions backed by the existing literature.

Auricular Vagal Nerve Stimulation Inhibited Central Nerve Growth Factor/Tropomyosin Receptor Kinase A/Phospholipase C-Gamma Signaling Pathway in Functional Dyspepsia Model Rats With Gastric Hypersensitivity

OBJECTIVE

Functional dyspepsia (FD), which has a complicated pathophysiologic process, is a common functional gastrointestinal disease. Gastric hypersensitivity is the key pathophysiological factor in patients with FD with chronic visceral pain. Auricular vagal nerve stimulation (AVNS) has the therapeutic effect of reducing gastric hypersensitivity by regulating the activity of the vagus nerve. However, the potential molecular mechanism is still unclear. Therefore, we investigated the effects of AVNS on the brain-gut axis through the central nerve growth factor (NGF)/ tropomyosin receptor kinase A (TrkA)/phospholipase C-gamma (PLC-γ) signaling pathway in FD model rats with gastric hypersensitivity.

MATERIALS AND METHODS

We established the FD model rats with gastric hypersensitivity by means of colon administration of trinitrobenzenesulfonic acid on ten-day-old rat pups, whereas the control rats were given normal saline. AVNS, sham AVNS, K252a (an inhibitor of TrkA, intraperitoneally), and K252a + AVNS were performed on eight-week-old model rats for five consecutive days. The therapeutic effect of AVNS on gastric hypersensitivity was determined by the measurement of abdominal withdrawal reflex response to gastric distention. NGF in gastric fundus and NGF, TrkA, PLC-γ, and transient receptor potential vanilloid 1 (TRPV1) in the nucleus tractus solitaries (NTS) were detected separately by polymerase chain reaction, Western blot, and immunofluorescence tests.

RESULTS

It was found that a high level of NGF in gastric fundus and an upregulation of the NGF/TrkA/PLC-γ signaling pathway in NTS were manifested in model rats. Meanwhile, both AVNS treatment and the administration of K252a not only decreased NGF messenger ribonucleic acid (mRNA) and protein expressions in gastric fundus but also reduced the mRNA expressions of NGF, TrkA, PLC-γ, and TRPV1 and inhibited the protein levels and hyperactive phosphorylation of TrkA/PLC-γ in NTS. In addition, the expressions of NGF and TrkA proteins in NTS were decreased significantly after the immunofluorescence assay. The K252a + AVNS treatment exerted a more sensitive effect on regulating the molecular expressions of the signal pathway than did the K252a treatment.

CONCLUSION

AVNS can regulate the brain-gut axis effectively through the central NGF/TrkA/PLC-γ signaling pathway in the NTS, which suggests a potential molecular mechanism of AVNS in ameliorating visceral hypersensitivity in FD model rats.

Noninvasive Transcutaneous Auricular Vagal Nerve Stimulation Improves Gastric Slow Waves Impaired by Cold Stress in Healthy Subjects

BACKGROUND/AIMS

Stress is known to inhibit gastric motility. The aim of this study was to investigate the effects and autonomic mechanisms of transcutaneous auricular vagal nerve stimulation (taVNS) on cold stress (CS)-induced impairment in gastric motility that are relevant to the brain-gut interactions in healthy volunteers.

MATERIALS AND METHODS

Healthy volunteers (eight women; age 28.2 ± 1.8 years) were studied in four randomized sessions (control, CS, CS + taVNS, and CS + sham-electrical stimulation [sham-ES]). Each session was composed of 30 minutes in the fasting state and 30 minutes after a standard test meal. CS was induced during minutes 10 to 30 after the meal, whereas taVNS or sham-ES was performed during minutes 0 to 30 after the meal. The electrogastrogram and electrocardiogram were recorded for assessing gastric slow waves and autonomic functions, respectively.

RESULTS

First, CS decreased the percentage of normal gastric slow waves (59.7% ± 9.8% vs 85.4% ± 4.5%, p < 0.001 vs control); this impairment was dramatically improved by taVNS (75.5% ± 6.3% vs 58.4% ± 12.5%, p < 0.001 vs sham-ES). Second, CS increased the symptom score (22.0 ± 12.1 vs 39.3 ± 11.5, p = 0.001 vs control); taVNS, but not sham-ES, reduced the symptom score (26.0 ± 12.2 vs 38.3 ± 21.6, p = 0.026 vs sham-ES). Third, CS decreased vagal activity assessed from the spectral analysis of heart rate variability (0.21 ± 0.10 vs 0.26 ± 0.11, p < 0.05 vs control) and increased the sympathovagal ratio (4.89 ± 1.94 vs 3.74 ± 1.32, p = 0.048 vs control); taVNS normalized CS-induced suppression in vagal activity (0.27 ± 0.13 vs 0.22 ± 0.10, p = 0.049 vs sham-ES; p > 0.05 vs control) and CS-induced increase in the sympathovagal ratio (3.28 ± 1.61 vs 4.28 ± 2.10, p = 0.042 vs sham-ES; p > 0.05 vs control).

CONCLUSION

The noninvasive taVNS improves the CS-induced impairment in gastric pace-making activity, possibly by reversing the detrimental effect of CS on autonomic functions. taVNS may have a therapeutic potential for stress-induced gastric dysmotility.

The antinociceptive effect of manual acupuncture in the auricular branch of the vagus nerve in visceral and somatic acute pain models and its laterality dependence

AIMS

The vagus nerve provides an important route to the central nervous system, and its brain projections are involved in nociceptive control and pain perception. We investigated the effect of ABVN stimulation on the inhibition of nociceptive signaling and the role of the cholinergic system in its neurobiological effects in models of visceral-somatic pain in rats, as well as the potential difference in stimulus laterality.

MATERIALS AND METHODS

Male and female Wistar rats were pretreated with auricular acupuncture in the ABVN and submitted to the visceral-somatic nociception model by acetic acid or somatic nociception by formalin. Vagotomy and pharmacological tools were used to verify the participation of the cholinergic system in the experiments.

KEY FINDINGS

Acupuncture on the left, but not the right, in the ABVN inhibited nociceptive signaling in the visceral-somatic nociception model in male and female rats. Acupuncture on the left ABVN reduced the response time in the formalin test. The cervical vagotomy of the left branch, but not the right, also inhibited nociceptive signaling in the visceral-somatic nociception model and reduced the effect of ABVN stimulation. Furthermore, cholinergic antagonists reduced the left ABVN stimulation effects in the same model.

SIGNIFICANCE

Our data show that only the stimulation in the left ABVN is capable of producing antinociceptive effect in acute pain models in rats, and that it is dependent on the activation of the vagus nerve caudal to the nodose ganglion, as well as the muscarinic and nicotinic cholinergic receptors.

Ameliorating effects and mechanisms of transcutaneous auricular vagal nerve stimulation on abdominal pain and constipation

BackgroundAbdominal pain and constipation are 2 main symptoms in patients with constipation-predominant irritable bowel syndrome (IBS-C). This study aimed to investigate the effects and possible mechanisms of transcutaneous auricular vagal nerve stimulation (taVNS) in patients with IBS-C.MethodsForty-two patients with IBS-C were randomized into a 4-week sham-taVNS or taVNS treatment. The primary outcomes were complete spontaneous bowel movements per week (CSBMs/week) and visual analog scale (VAS) for abdominal pain. High-resolution anorectal manometry (HRAM) was performed to evaluate anorectal motor and sensory function. Cytokines and brain gut peptides were analyzed in blood samples. ECG was recorded for the assessment of autonomic function.ResultsCompared with sham-taVNS, (a) taVNS increased CSBMs/week (P = 0.001) and decreased VAS pain score (P = 0.001); (b) improved quality of life (P = 0.020) and decreased IBS symptom score (P = 0.001); (c) improved rectoanal inhibitory reflex (P = 0.014) and improved rectal sensation (P < 0.04); (d) decreased a number of proinflammatory cytokines and serotonin in circulation; and (e) enhanced vagal activity (P = 0.040). The vagal activity was weakly correlated with the CSBMs/week (r = 0.391; P = 0.010) and the VAS pain score (r = -0.347; P = 0.025).ConclusionsNoninvasive taVNS improves both constipation and abdominal pain in patients with IBS-C. The improvement in IBS-C symptoms might be attributed to the integrative effects of taVNS on intestinal functions mediated via the autoimmune mechanisms.Trial registrationwww.chictr.org.cn, no. ChiCTR2000029644.FundingNational Natural Science Foundation of China (grant no. 81970538 for FL).

Transcutaneous auricular vagal nerve stimulation improves functional dyspepsia by enhancing vagal efferent activity

This study was designed to investigate whether transcutaneous auricular vagal nerve stimulation (taVNS) would be able to improve major pathophysiologies of functional dyspepsia (FD) in patients with FD. Thirty-six patients with FD (21 F) were studied in two sessions (taVNS and sham-ES). Physiological measurements, including gastric slow waves, gastric accommodation, and autonomic functions, were assessed by the electrogastrogram (EGG), a nutrient drink test and the spectral analysis of heart rate variability derived from the electrocardiogram (ECG), respectively. Thirty-six patients with FD (25 F) were randomized to receive 2-wk taVNS or sham-ES. The dyspeptic symptom scales, anxiety and depression scores, and the same physiological measurements were assessed at the beginning and the end of the 2-wk treatment. In comparison with sham-ES, acute taVNS improved gastric accommodation (P = 0.008), increased the percentage of normal gastric slow waves (%NSW, fasting: P = 0.010; fed: P = 0.007) and vagal activity (fasting: P = 0.056; fed: P = 0.026). In comparison with baseline, 2-wk taVNS but not sham-ES reduced symptoms of dyspepsia (P = 0.010), decreased the scores of anxiety (P = 0.002) and depression (P < 0.001), and improved gastric accommodation (P < 0.001) and the %NSW (fasting: P < 0.05; fed: P < 0.05) by enhancing vagal efferent activity (fasting: P = 0.015; fed: P = 0.048). Compared with the HC, the patients showed increased anxiety (P < 0.001) and depression (P < 0.001), and decreased gastric accommodation (P < 0.001) and %NSW (P < 0.001) as well as decreased vagal activity (fasting: P = 0.047). The noninvasive taVNS has a therapeutic potential for treating nonsevere FD by improving gastric accommodation and gastric pace-making activity via enhancing vagal activity.NEW & NOTEWORTHY Treatment of functional dyspepsia is difficult due to various pathophysiological factors. The proposed method of transcutaneous auricular vagal nerve stimulation improves symptoms of both dyspepsia and depression/anxiety, and gastric functions (accommodation and slow waves), possibly mediated via the enhancement of vagal efferent activity. This noninvasive and easy-to-implement neuromodulation method will be well received by patients and healthcare providers.

Auricular Vagal Nerve Stimulation Improves Constipation by Enhancing Colon Motility via the Central-Vagal Efferent Pathway in Opioid-Induced Constipated Rats

OBJECTIVES

Constipation and opioid-induced constipation (OIC) are common with limited treatment options. We investigated whether a noninvasive method of auricular vagal nerve stimulation (aVNS) could be used for treating OIC and explored its potential mechanisms and neural pathways in a rodent model of OIC.

MATERIALS AND METHODS

Sprague-Dawley were chronically implanted with one pair of auricular electrodes for aVNS. Sixteen rats were treated with loperamide for a week while another 16 rats received bilateral vagotomy, then randomly treated with aVNS or sham-aVNS for a week. In addition, eight normal rats were implanted with a polyethylene catheter in the proximal colon for assessing whole colon transit.

RESULTS

1) The number of fecal pellets and water content in feces increased after aVNS, compared with sham-aVNS. 2) aVNS accelerated colon transit and whole gut transit, compared with sham-aVNS. 3) In colon tissues, aVNS increased the protein expression of choline acetyltransferase, glial cell line-derived neurotrophic factor and the c-kit expression in myenteric interstitial cells of Cajal but decreased the protein expression of neural nitric oxide synthase (p < 0.05 for all, vs. sham-VNS). 4) The prokinetic effects of aVNS were abolished by both subdiaphragmatic vagotomy and atropine. 5) aVNS increased the c-fos expression in both nucleus tractus solitarius and dorsal motor nucleus of vagus, and increased vagal efferent activity (p < 0.05, vs. sham-VNS).

CONCLUSIONS

aVNS improves OIC by enhancing colon motility and restoring enteric neural functions mediated via the central and vagal efferent pathway.

Auricular therapy improves gastrointestinal function in patients with gynecological laparoscopic surgery: A protocol for systematic review and meta analysis

BACKGROUND

Gynecological laparoscopic surgery is the main method to treat gynecological diseases, but postoperative gastrointestinal reactions are more common in patients. Auricular therapy, as a characteristic therapy of Traditional Chinese Medicine, can improve gastrointestinal symptoms such as nausea and vomiting by stimulating the conduction of acupoints through the nervous system on internal organs, but there are studies questioning the efficacy of auricular therapy. Therefore, the purpose of this study is to prove the efficacy and safety of auricular therapy in promoting gastrointestinal function recovery after gynecological laparoscopic surgery, and to provide reference value for future clinical practice.

METHODS

To search English databases (PubMed, Excerpta Medical Database [Embase], Web of Science, the Cochrane Library) and Chinese databases (Chinese National Knowledge Internet [CNKI], WanFang, Viper, Chinese Biomedical Literature Database) by computer, and conduct a randomized controlled trial on the effect of aural point therapy on gastrointestinal function recovery of patients after gynecological laparoscopic surgery from the establishment of the database to October 2020. Two researchers independently evaluate the quality of the included studies and extract the data, and meta-analysis of the included literature is carried out using RevMan5.3 software.

RESULTS

In this study, the efficacy and safety of auricular therapy in the recovery of gastrointestinal function after gynecological laparoscopic surgery are evaluated from the aspects of first anal exhaust time, bowel sound recovery time, and incidence of gastrointestinal complications.

CONCLUSION

This study will provide reliable evidence-based evidence for auricular therapy in the treatment of gastrointestinal function after gynecologic laparoscopic surgery.

ETHICS AND DISSEMINATION

Private information from individuals will not be published. This systematic review also does not involve endangering participant rights. Ethical approval was not required. The results may be published in a peer-reviewed journal or disseminated at relevant conferences.

OSF REGISTRATION NUMBER

DOI 10.17605 / OSF.IO / ZSPGA.

The effects of low-and high-frequency non-invasive transcutaneous auricular vagal nerve stimulation (taVNS) on gastric slow waves evaluated using in vivo high-resolution mapping in porcine

BACKGROUNDS

Gastric motility is regulated by an electrophysiological activity called slow-wave and neuronal innervations by the vagus nerve. Transcutaneous auricular vagal nerve stimulation (taVNS) has been demonstrated to have therapeutic potential for a wide range of medical conditions, including the management of gastric dysfunctions. The main objective of this study was to gain a better understanding of how non-invasive neuromodulation influences gastric slow wave under in vivo conditions.

METHODS

TaVNS protocols were applied in conjunction with 192-channel gastric bioelectrical mapping in porcine subjects under general anesthesia. The spatiotemporal profiles of gastric slow wave were assessed under two different taVNS protocols at 10 and 80 Hz.

KEY RESULTS

The taVNS protocols effectively altered the interval and amplitude of gastric slow waves, but not the velocity or the percentage of spatial dysrhythmias. In the subjects that responded to the protocols, the 10 Hz protocol was shown to normalize slow-wave propagation pattern in 90% of the subjects, whereas the 80 Hz protocol was shown to inhibit slow waves in 60% of the subjects.

CONCLUSIONS AND INFERENCES

Chronic responses of gastric motility and slow waves in response to taVNS should be investigated using non-invasive means in conscious subjects in future.

Neuromechanism of acupuncture regulating gastrointestinal motility

Acupuncture has been used in China for thousands of years and has become more widely accepted by doctors and patients around the world. A large number of clinical studies and animal experiments have confirmed that acupuncture has a benign adjustment effect on gastrointestinal (GI) movement; however, the mechanism of this effect is unclear, especially in terms of neural mechanisms, and there are still many areas that require further exploration. This article reviews the recent data on the neural mechanism of acupuncture on GI movements. We summarize the neural mechanism of acupuncture on GI movement from four aspects: acupuncture signal transmission, the sympathetic and parasympathetic nervous system, the enteric nervous system, and the central nervous system.

Moving beyond belief: A narrative review of potential biomarkers for transcutaneous vagus nerve stimulation

Transcutaneous vagus nerve stimulation (tVNS) is a non-invasive neurostimulation technique that is currently being tested as a potential treatment for a myriad of neurological and psychiatric disorders. However, the working mechanisms underlying tVNS are poorly understood and it remains unclear whether stimulation activates the vagus nerve for every participant. Finding a biological marker of tVNS is imperative, as it can help guide research on clinical applications and can inform researchers on optimal stimulation sites and parameters to further optimize treatment efficacy. In this narrative review, we discuss five potential biomarkers for tVNS and review currently available evidence for these markers for both invasive and tVNS. While some of these biomarkers hold promise from a theoretical perspective, none of the potential biomarkers provide clear and definitive indications that tVNS increases the vagal activity or augments activity in the locus coeruleus-noradrenaline network. We conclude the review by providing several recommendations for how to tackle the challenges and opportunities when researching potential biomarkers for the effects of tVNS.

Auricular acupuncture induces FNDC5/irisin and attenuates obese inflammation in mice

OBJECTIVE

To investigate whether auricular acupuncture (AA) attenuates bodyweight and obese inflammation through the release of irisin from muscle tissue in mice.

METHODS

Sixty 4-week-old mice were fed a high fat diet (HFD) for 4 weeks. These animals were divided into six groups that remained untreated (HFD) or underwent electrical AA (HFD+EAA), sham EAA (HFD+SEAA), adrenalectomy (HFD+AD), adrenalectomy and EAA (HFD+AD+EAA), or adrenalectomy and injection of recombinant lentivirus expressing fibronectin type III domain-containing protein 5 (rFNDC) (HFD+AD+rFNDC) in the ninth week. The EAA and SEAA were performed at two traditional auricular acupuncture points daily for 4 weeks. An additional 10 mice fed a control diet were included as a normal control (NC) group. At the end of the study, norepinephrine (NE) in the serum, tumour necrosis factor α (TNFα) and interleukin 1β (IL-1β) in the serum and white adipose tissue, irisin in the serum and muscle, uncoupling protein-1 (UCP-1) in the brown adipose tissue (BAT), and FNDC5 in the muscle, were analysed.

RESULTS

The AD+EAA group exhibited better control of bodyweight and inflammation compared with the AD+SEAA and untreated HFD model groups (P<0.05), especially regarding the increased expression of NE, FNDC5, irisin and UCP-1 (P<0.05). After adrenalectomy, mice receiving EAA had less NE, FNDC5, irisin and UCP-1 as well as greater expression of inflammatory cytokines and bodyweight. However, lentiviral overexpression of rFNDC successfully reversed this situation in the AD mice and mimicked the effects of EAA on bodyweight, inflammation and expression of FNDC5, irisin and UCP-1, although it did not impact NE.

CONCLUSIONS

EAA promoted NE release from the adrenal gland leading to further expression of FNDC5, irisin and UCP-1, which contributed to weight management and inflammatory inhibition.

Extracellular and Intracellular Fluid Shifts on the Onset of Transcutaneous Auricular Vagus Nerve Stimulation

In this paper, we propose multifrequency body impedance measurement technique for monitoring the onset of vagus nerve stimulation. In response to transcutaneous electrical vagus stimulation, changes occur in body fluids i.e. fluid shifts in extracellular and intracellular media that can be assessed by Cole parameters R_e and R_i before and after stimulus, by measuring single side impedance spectroscopy (from 3 kHz to 1 MHz) between wrist and ankle. Following a resting period of 5 minutes in supine position, auricular vagus nerve was stimulated for 3 minutes and BIS performed every 10 seconds, on 23-27 years old, 5 healthy subjects. During the stimulation phase, either an increase or a decrease was observed in extracellular and intracellular fluids. In 3 of the subjects, an ECF decrease of 0.02% per kg was compensated by 0.02 to 0.06% per kg increase in ICF; with a correlation coefficient of -0,70 to -0,79; suggesting fluid shifts between ECF and ICF. With the other 2 subjects, both ECF and ICF decreased by about 0.02% per kg. The study was performed with a limited number of participants; to reach statistically meaningful results measurements will be performed over a larger sample size.

Can the vagus nerve serve as biomarker for vata dosha activity?

This 'discussion paper' raises 'provocative questions' to identify physiological systems underlying vata dosha and candidate biomarkers for vata activity. We explained the strong correlations between survival and homeostatic functions of the parasympathetic vagus nerve, and functions governed by the five major sub-types of vata dosha (Praana, Udana, Vyaana, Samaana, and Apana). Four reasons were provided to hypothesize that vagal activity is a reliable candidate biomarker of important vata dosha functions. First, normal vata dosha and the vagus maintain neural, respiratory, and digestive homeostasis, and dysfunctions in both entities cause very similar diseases. Second, vata dosha regulates higher neural functions such as mental health and behaviour, and the 'polyvagal theory' proposes similar functions for the vagus. Third, the similar roles of vata dosha and vagus in maintaining gut homeostasis, suggest that vagal activity in the 'gut-brain' link is a candidate biomarker of pakwashaya (lower gut), a primary regulatory site for vata dosha. Fourth, the vagus is the only vital nerve whose activity can be reliably measured and manipulated. Indeed, vagal nerve stimulation is a USA-FDA approved therapy for certain ailments attributed to impaired vata dosha. No other nerve or dosha, has such multi-functional and life-sustaining properties. These arguments position vagal activity as a suitable candidate biomarker for certain functions of vata dosha.

Traumatic stress and the autonomic brain-gut connection in development: Polyvagal Theory as an integrative framework for psychosocial and gastrointestinal pathology

A range of psychiatric disorders such as anxiety, depression, and post-traumatic stress disorder frequently co-occur with functional gastrointestinal (GI) disorders. Risk of these pathologies is particularly high in those with a history of trauma, abuse, and chronic stress. These scientific findings and rising awareness within the healthcare profession give rise to a need for an integrative framework to understand the developmental mechanisms that give rise to these observations. In this paper, we introduce a plausible explanatory framework, based on the Polyvagal Theory (Porges, Psychophysiology, 32, 301-318, 1995; Porges, International Journal of Psychophysiology, 42, 123-146, 2001; Porges, Biological Psychology, 74, 116-143, 2007), which describes how evolution impacted the structure and function of the autonomic nervous system (ANS). The Polyvagal Theory provides organizing principles for understanding the development of adaptive diversity in homeostatic, threat-response, and psychosocial functions that contribute to pathology. Using these principles, we outline possible mechanisms that promote and maintain socioemotional and GI dysfunction and review their implications for therapeutic targets.

Nerve Stimulation: Immunomodulation and Control of Inflammation

Neuronal stimulation is an emerging field in modern medicine to control organ function and re-establish physiological homeostasis during illness. Transdermal nerve stimulation with electroacupuncture is currently endorsed by the World Health Organization (WHO) and the National Institutes of Health (NIH), and is used by millions of people to control pain and inflammation. Recent advances in electroacupuncture may permit activation of specific neuronal networks to prevent organ damage in inflammatory and infectious disorders. Experimental studies of nerve stimulation are also providing new information on the functional organization of the nervous system to control inflammation and its clinical implications in infectious and inflammatory disorders. These studies may allow the design of novel non-invasive techniques for nerve stimulation to help to control immune and organ functions.

Effects and mechanisms of auricular electroacupuncture on gastric hypersensitivity in a rodent model of functional dyspepsia

Background

Functional dyspepsia (FD) is a common functional gastrointestinal disease, and abdominal pain is one of the main symptoms. The aim of this study was to explore the effects and mechanisms of auricular electro-acupuncture (AEA) on gastric hypersensitivity in a rodent model of FD.

Methods

Ten-day-old pups were gavaged with 0.2 ml of 0.1% iodoacetamide daily for 6 days. AEA at the “stomach” point with different parameters or sham-EA was performed on 8-week-old animals. Gastric sensitivity to gastric distention was measured under different conditions. Autonomic functions were assessed from the spectral analysis of heart rate variability (HRV) derived from the electrocardiogram. Naloxone was injected intraperitoneally before AEA to explore the opioid mechanism. Gastric emptying was measured at the end of the study.

Results

1) Gastric sensitivity to gastric distention was higher in the FD rats. AEA with parameters of 0.1s on, 0.4s off, 100Hz, 0.3ms and 0.4–0.5mA, but not other parameters or sham-EA, decreased gastric hypersensitivity in the FD rats. Naloxone did not block the effect of AEA. 2) Lower vagal activity and higher sympathovagal ratio were noted in the FD rats, compared with the controls. AEA increased vagal activity and improved sympathovagal imbalance.

Conclusions

AEA ameliorates gastric hypersensitivity in FD rats and this effect may be attributed to the improvement of sympathovagal balance.

The Effects of Auricular Electro-Acupuncture on Ameliorating the Dysfunction of Interstitial Cells of Cajal Networks and nNOSmRNA Expression in Antrum of STZ-Induced Diabetic Rats

BACKGROUD

Interstitial cells of Cajal (ICCs) and nNOS play a crucial role in diabetic gastrointestinal dysmotility(DGD). Our previous study found that electro-acupuncture(EA) on ear point 'stomach' could repair the gastric dysrhythmias in rats induced by rectal distention(RD) after meal. However, little were known about the possible effect of auricular electro-acupuncture (AEA) on diabetic rats. Thus, we designed this study to investigate the effect of AEA on streptozotocin(STZ)-induced diabetic rats.

METHOD

Forty male Sprague_Dawley (SD) rats were injected with STZ, at the end of 8th week after injection, animals were randomly divided into four groups and received 2 weeks-treatment(10 times) respectively: control group(CON,n = 10, no stimulation), sham auricular electro-acupuncture group(SEA,n = 10, low frequency EA on earlobes), auricular eletro-acupuncture group(AEA,n = 10, low frequency EA on ear point 'stomach'), and ST-36 group(ST-36,n = 10, low frequency EA on ST-36). Gastrointestinal (GI) motility was measured by GI transit rate. ICCs(c-kit+ expression) in antrum were analyzed by Immunohistochemistry and western blotting. NO level in blood serum were detected by Griess Reagent, and nNOSmRNA expression in antrum were determined by Real-time PCR.

RESULTS

GI transit rate and ICCs(c-kit+ expression) in antrum of AEA group have the tendency to increase compared with CON group, but had no statistics difference (P>0.05). nNOSmRNA expression in antrum of AEA group was dramatically increased compared with CON group (P = 0.037).

CONCLUSIONS

Low frequency EA on ear 'stomach' point could significantly up-regulate nNOS mRNA expression and ameliorate the ICCs networks partly in gastric antrum of STZ -induced diabetic rats, which may has benefits on regulating the GI motility.

Electroacupuncture ameliorates abnormal defaecation and regulates corticotrophin-releasing factor in a rat model of stress

Objective

To examine the effect of electroacupuncture (EA) treatment on abnormal defaecation in a rat model of chronic heterotypic stress (CHS) and investigate the underlying mechanisms.

Methods

20 male Sprague-Dawley rats were randomly divided into three groups: normal (n=6), CHS (n=7), and CHS+EA (n=7). Rats in the CHS group and CHS+EA groups received four different types of stressors for 7 days. For rats in the CHS+EA group, EA was applied at ST36 in the bilateral hind legs for 30 min before each stress-loading session. Rats in the normal group did not receive stressors or EA treatment. The faecal pellets of each rat were collected and weighed at a fixed time every day. Protein expression of corticotrophin-releasing factor (CRF) in the hypothalamus and colorectal tissues was measured by Western blotting at the end of the experiment on the 7th day.

Results

After 7 consecutive days of CHS, the number of faecal pellets, faecal wet weight, and faecal water content were significantly increased in the CHS group compared with the normal group (p=0.035, p=0.008 and p=0.008, respectively). All three parameters were significantly decreased in CHS+EA versus CHS groups (p=0.030, p=0.011 and p=0.006, respectively). Stress significantly increased CRF expression in both the hypothalamus and colorectal tissues. The excessive CRF responses seen following CHS were significantly suppressed by EA treatment.

Conclusions

EA treatment can ameliorate stress loading induced abnormal defaecation in rats and decrease protein expression of CRF centrally (hypothalamus) and peripherally (colorectal tissues), suggesting a potentially therapeutic role for EA in stress-related responses.

Modulation of vagal tone enhances gastroduodenal motility and reduces somatic pain sensitivity

BACKGROUND

The parasympathetic nervous system, whose main neural substrate is the vagus nerve, exerts a fundamental antinociceptive role and influences gastrointestinal sensori-motor function. Our research question was to whether combined electrical and physiological modulation of vagal tone, using transcutaneous electrical vagal nerve stimulation (t-VNS) and deep slow breathing (DSB) respectively, could increase musculoskeletal pain thresholds and enhance gastroduodenal motility in healthy subjects.

METHODS

Eighteen healthy subjects were randomized to a subject-blinded, sham-controlled, cross-over study with an active protocol including stimulation of auricular branch of the vagus nerve, and breathing at full inspiratory capacity and forced full expiration. Recording of cardiac derived parameters including cardiac vagal tone, moderate pain thresholds to muscle, and bone pressure algometry, conditioned pain modulation using a cold pressor test and a liquid meal ultrasonographic gastroduodenal motility test were performed.

KEY RESULTS

Cardiac vagal tone increased during active treatment with t-VNS and DSB compared to sham (p = 0.009). In comparison to sham, thresholds to bone pain increased (p = 0.001), frequency of antral contractions increased (p = 0.004) and gastroduodenal motility index increased (p = 0.016) with active treatment. However, no effect on muscle pain thresholds and conditioned pain modulation was seen.

CONCLUSIONS & INFERENCES

This experimental study suggests that this noninvasive approach with combined electrical and physiological modulation of vagal tone enhances gastroduodenal motility and reduces somatic pain sensitivity. These findings warrant further investigation in patients with disorders characterized with chronic pain and gastrointestinal dysmotility such as functional dyspepsia and irritable bowel syndrome.

Exploring Self-Reported Benefits of Auricular Acupuncture Among Veterans With Posttraumatic Stress Disorder

PURPOSE

Auricular acupuncture treatments are becoming increasingly available within military treatment facilities, resulting in an expansion of nonpharmacologic treatment options available to veterans with posttraumatic stress disorder (PTSD). This study aimed to explore the self-reported benefits of auricular acupuncture treatments for veterans living with PTSD.

DESIGN

A qualitative research methodology, thematic content analysis, was used to analyze data.

METHOD

Seventeen active duty veterans with PTSD provided written comments to describe their experiences and perceptions after receiving a standardized auricular acupuncture regimen for a 3-week period as part of a pilot feasibility study.

FINDINGS

A variety of symptoms experienced by veterans with PTSD were improved after receiving auricular acupuncture treatments. Additionally, veterans with PTSD were extremely receptive to auricular acupuncture treatments. Four themes emerged from the data: (1) improved sleep quality, (2) increased relaxation, (3) decreased pain, and (4) veterans liked/loved the auricular acupuncture treatments.

CONCLUSIONS

Veterans with PTSD reported numerous benefits following auricular acupuncture treatments. These treatments may facilitate healing and recovery for veterans with combat-related PTSD, although further investigations are warranted into the mechanisms of action for auricular acupuncture in this population.

Ameliorating effects of auricular electroacupuncture on rectal distention-induced gastric dysrhythmias in rats

Gastric slow waves (GSW) are known to regulate gastric motility and are impaired with rectal distention (RD). Electroacupuncture (EA) at body acupoints, such as ST 36, has been shown to improve gastric dysrhythmias; however, little is known about the possible effects of auricular electroacupuncture (AEA) on GSW. To study effects and possible mechanisms of AEA on RD-induced gastric dysrhythmias in rats, ten male Sprague-Dawley (SD) rats implanted with gastric serosal electrodes were studied in two different experiments in fed state. Four sessions were performed in experiment 1 as follows: control (RD, no stimulation), RD+AEA, RD+EA at body points and RD+sham AEA. Two sessions were included in experiment 2 to study mechanisms of AEA: RD + atropine and RD + atropine + AEA. It was found that 1) RD significantly decreased the percentage of normal GSW from 89.8 ± 3.5% to 76.0 ± 3.3% (P<0.05); 2) AEA increased the percentage of normal GSW during RD to 94.0 ± 2.1% (P<0.05 vs. RD) via a reduction in the percentages of tachygastria and arrhythmia (P<0.05 vs. RD); 3) atropine blocked the ameliorating effect of AEA on RD-induced gastric dysrhythmias. Our results demonstrated that RD induces gastric dysrhythmias in fed state in rats. AEA improves RD-induced gastric dysrhythmias via the vagal pathway. AEA may have a therapeutic potential in treating gastric dysrhythmias.

Effects and mechanisms of auricular electroacupuncture on visceral pain induced by colorectal distension in conscious rats

OBJECTIVE

To investigate the effects and mechanisms of action of auricular electroacupuncture (AEA) on visceral pain induced by colorectal distension (CRD).

METHODS

Twenty-nine female Sprague-Dawley rats were randomly divided into four groups: control; untreated CRD; CRD+AEA; and CRD+sham electroacupuncture (SEA). An electromyogram (EMG) was recorded for 120 min in the conscious state. After a 30 min baseline recording, CRD was performed in untreated CRD, AEA and SEA groups and lasted for 90 min. AEA and SEA were started at 30 min and lasted for 30 min. The EMG was recorded and analysed to evaluate the severity of visceral pain, indicated by the magnitude of the vasomotor response (VMR). mRNA expression of the 5-hydroxytryptamine 1a (5-HT1a) receptor was measured separately in the colon and raphe nuclei using real-time fluorescent quantitative PCR.

RESULTS

No differences were seen in the baseline EMG among the four groups (p>0.05). During pre-stimulation, VMR magnitude in the CRD, AEA and SEA groups increased compared with that in the control group (p<0.05). During stimulation, the VMR magnitude was significantly decreased in AEA but not SEA groups relative to the (untreated) CRD group. Similarly, mRNA expression of the 5-HT1a receptor in both the colon and raphe nuclei was lower in AEA but not SEA groups compared with the CRD group (p<0.05).

CONCLUSIONS

AEA can ameliorate CRD-induced visceral pain in rats, and increase mRNA expression of the 5-HT1a receptor peripherally (in the colon) and centrally (in the raphe nuclei), suggesting a serotonergic mechanism of action.

Manual acupuncture and laser acupuncture for autonomic regulations in rats: observation on heart rate variability and gastric motility

This study focused on the effects of laser acupuncture (LA) and manual acupuncture (MA) at different acupoints on gastric motility and heart rate variability (HRV) simultaneously to elucidate the site specific effects of acupoints and the correlation between changes of gastric motility and low frequency/high frequency (LF/HF) ratio. Gastric motility and HRV were recorded before and during MA or LA. Stimulating PC-6 or ST-36 significantly enhanced gastric motility, while BL-21 caused no changes. In contrast, MA or LA at CV-12 significantly suppressed gastric motility. Stimulating PC-6 or ST-36 significantly increased heart rate (HR), while CV-12 or BL-21 induced no significant changes of HR. Stimulating PC-6 significantly increased LF/HF, while ST-36, CV-12, or BL-21 induced no significant effects. These results indicated that there was acupoint specificity in the effects of acupuncture on gastric motility and HRV. The stimulatory effect of MA and LA at PC-6 and ST-36 on HR was associated with sympathetic activity. The stimulatory effect of MA or LA at PC-6 or ST-36 on gastric motility was associated with vagal activity. Laser needle can be used as an alternative stimulation therapy.

Acupuncture in practice: investigating acupuncturists' approach to treating infantile colic

Infantile colic is common, but no safe and effective conventional treatment exists. The use of acupuncture has increased despite weak evidence. This practitioner survey explores and discusses how infantile colic is regarded and treated in Traditional Chinese Medicine (TCM). The study is based on personal communication with 24 acupuncturists from nine countries. These acupuncturists specialize in pediatric acupuncture and represent different styles of acupuncture. Their experiences are discussed and related to relevant books and articles. Informants claimed good results when treating infants with colic. The TCM patterns commonly described by informants matched the textbooks to a great extent. The most common syndromes were "stagnation of food" and "Spleen Qi Xu." Regarding treatment, some informants followed the teachers' and the textbook authors' advice on differentiated treatment according to syndrome. The points used most often were LI4, ST36, and Sifeng. Other informants treated all infants alike in one single point, LI4. The results demonstrate the diversity of TCM. The use of acupuncture for infantile colic presents an interesting option, but further research is needed in order to optimize the effects and protect infants from unnecessary or less effective treatment.