Electrical therapies for gastrointestinal motility disorders

The gut-brain and gut-macrophage contribution to gastrointestinal dysfunction with systemic inflammation

The gastrointestinal tract is one of the main organs affected during systemic inflammation and disrupted gastrointestinal motility is a major clinical manifestation. Many studies have investigated the involvement of neuroimmune interactions in regulating colonic motility during localized colonic inflammation, i.e., colitis. However, little is known about how the enteric nervous system and intestinal macrophages contribute to dysregulated motility during systemic inflammation. Given that systemic inflammation commonly results from the innate immune response against bacterial infection, we mimicked bacterial infection by administering lipopolysaccharide (LPS) to rats and assessed colonic motility using ex vivo video imaging techniques. We utilized the Cx3cr1-Dtr rat model of transient depletion of macrophages to investigate the role of intestinal macrophages in regulating colonic motility during LPS infection. To investigate the role of inhibitory enteric neurotransmission on colonic motility following LPS, we applied the nitric oxide synthase inhibitor, Nω-nitro-L-arginine (NOLA). Our results confirmed an increase in colonic contraction frequency during LPS-induced systemic inflammation. However, neither the depletion of intestinal macrophages, nor the suppression of inhibitory enteric nervous system activity impacted colonic motility disruption during inflammation. This implies that the interplay between the enteric nervous system and intestinal macrophages is nuanced, and complex, and further investigation is needed to clarify their joint roles in colonic motility.

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.

MiR-26b-3p Promotes Intestinal Motility Disorder by Targeting FZD10 to Inhibit GSK3β/β-Catenin Signaling and Induce Enteric Glial Cell Apoptosis

Enteric glial cells (EGCs) are the major component of the enteric nervous system and affect the pathophysiological process of intestinal motility dysfunction. MicroRNAs (miRNAs) play an important role in regulating gastrointestinal homeostasis. However, the mechanism of miRNA-mediated regulation of EGCs in intestinal dysmotility remains unclear. In this study, we investigated the effect of EGC apoptosis on intestinal dysmotility, and the effect of miR-26b-3p on EGC proliferation and apoptosis in vivo and in vitro. A loperamide hydrochloride (Lop)-induced constipated mouse model and an in vitro culture system of rat EGCs were established. The transcriptome was used to predict the differentially expressed gene miR-26b-3p and the target gene Frizzled 10 (FZD10), and their targeting binding relationship was verified by luciferase. EGCs were transfected with miR-26b-3p mimic or antagomir, and the FZD10 expression was down-regulated by siRNA. Immunofluorescence and flow cytometry were used to detect EGC apoptosis. MiR-26b-3p and FZD10 expressions were examined using quantitative real-time PCR (qRT-PCR). The CCK-8 assay was used to detect EGC proliferation. The protein levels were detected by Western blotting and enzyme-linked immunosorbent assay (ELISA). The results showed that miR-26b-3p was up-regulated in the Lop group, whereas FZD10 was down-regulated, and EGC apoptosis was increased in the colon of intestinal dysmotility mice. FZD10 down-regulation and miR-26b-3p mimic significantly increased glycogen synthase kinase-3β phosphorylation (p-GSK3β) levels, decreased β-catenin expression, and promoted EGC apoptosis. MiR-26b-3p antagomir alleviated intestinal dysmotility, promoted EGC increased activity of EGCs, and reduced EGC apoptosis in vivo. In conclusion, this study indicated that miR-26b-3p promotes intestinal motility disorders by targeting FZD10 to block GSK3β/β-catenin signaling and induces apoptosis in EGCs. Our results provide a new research target for the treatment and intervention of intestinal dysmotility.

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.

Bioadhesive Technology Platforms

Bioadhesives have emerged as transformative and versatile tools in healthcare, offering the ability to attach tissues with ease and minimal damage. These materials present numerous opportunities for tissue repair and biomedical device integration, creating a broad landscape of applications that have captivated clinical and scientific interest alike. However, fully unlocking their potential requires multifaceted design strategies involving optimal adhesion, suitable biological interactions, and efficient signal communication. In this Review, we delve into these pivotal aspects of bioadhesive design, highlight the latest advances in their biomedical applications, and identify potential opportunities that lie ahead for bioadhesives as multifunctional technology platforms.

Noninvasive electrical neuromodulation for gastrointestinal motility disorders

INTRODUCTION

Gastrointestinal motility disorders are highly prevalent without satisfactory treatment. noninvasive electrical neuromodulation is an emerging therapy for treating various gastrointestinal motility disorders.

AREAS COVERED

In this review, several emerging noninvasive neuromodulation methods are introduced, including transcutaneous auricular vagal nerve stimulation, percutaneous auricular vagal nerve stimulation, transcutaneous cervical vagal nerve stimulation, transcutaneous electrical acustimulation, transabdominal interference stimulation, tibial nerve stimulation, and translumbosacral neuromodulation therapy. Their clinical applications in the most common gastrointestinal motility are discussed, including gastroesophageal reflux disease, functional dyspepsia, gastroparesis, functional constipation, irritable bowel syndrome, and fecal incontinence. PubMed database was searched from 1995 to June 2023 for relevant articles in English.

EXPERT OPINION

Noninvasive neuromodulation is effective and safe in improving both gastrointestinal symptoms and dysmotility; it can be used when pharmacotherapy is ineffective. Future directions include refining the methodology, improving device development and understanding mechanisms of action.

Transcutaneous electrical stimulation for gastrointestinal motility disorders

BACKGROUND/PURPOSE

Gastrointestinal (GI) dysmotility is categorized by muscle or nerve dysfunctions in any portion of the GI tract, which leads to abnormalities in GI motor and sensory function. Symptoms may vary depending on the organ affected and can be debilitating. Treatment usually involves diet and lifestyle changes. Pharmacotherapy is limited in effectiveness with various side effects. Transcutaneous electrical stimulation (TES), a noninvasive, needleless technique that provides electrical stimulation using cutaneous non-needle electrodes, has become increasingly popular. It has been shown to be beneficial in treating GI motility disorders.

METHODS

This review paper navigates through the different TES techniques, including transcutaneous peripheral nerve (vagal/sacral/tibial nerves) electrical stimulation, transcutaneous electrical acustimulation (stimulation via acupuncture point), transcutaneous interferential current therapy, and transcutaneous electrical nerve stimulation.

KEY RESULTS

As we delve deeper, we explore the promising effects of TES on dysphagia, gastroesophageal reflux disease, functional dyspepsia, gastroparesis, postoperative ileus, constipation, and irritable bowel syndrome. The literature at hand speaks volumes about the therapeutic prowess of this noninvasive technique.

CONCLUSION & INFERENCES

The time is ripe to evaluate further the full therapeutic potential of TES, a noninvasive, nonpharmaceutical, nonsurgical, and home-based self-administrative technique in managing GI motility disorders.

Current complementary and alternative therapy forgastroesophageal reflux disease

Gastroesophageal reflux disease (GERD) is a widely prevalent gastrointestinal disorder, affecting ∼13.3% of the global population. There are shortages and limitations of current GERD treatment modalities, and complementary and alternative therapy (CAT) is a promising option to fill in the gap. Dietary and lifestyle modifications might play an important and complementary role in alleviating GERD symptoms. Traditional Chinese medicine and brain-gut behavior therapy, particularly transcutaneous electrical acustimulation and diaphragmatic breathing therapy were shown to be useful adjuncts or alternatives in treating GERD. CAT may help to relieve GERD symptoms, minimize medication dosage, and slow the demand for surgery. The aim of this review was to summarize the existing evidence of some common CATs in treating symptomatic GERD, including dietary modification, lifestyle change, traditional Chinese medicine, and brain-gut behavior therapy.

Pyridostigmine in chronic intestinal pseudo-obstruction - a systematic review

BACKGROUND

Chronic intestinal pseudo-obstruction (CIPO) may be a primary or secondary phenomenon and is often multifactorial. Treatment is largely directed at improving colonic motility. The use of cholinesterase inhibitors such as pyridostigmine has been hypothesized to increase acetylcholine in the bowel, improving symptoms and transit times.

METHODS

A systematic review of the use of pyridostigmine in CIPO was conducted using scientific and commercial search engines identifying scientific studies enrolling adult human subjects, published from 2000 to 2022 in the English language.

RESULTS

Four studies were identified including two randomized controlled trials (RCT) and two observational studies. The studies had heterogenous inclusion criteria, dosing regimens and reported outcomes. Two studies were identified as being at high risk of bias. All studies reported improved patient outcomes with use of pyridostigmine, and low rates (4.3%) of mild cholinergic side effects. No major side effects were reported.

CONCLUSION

The use of pyridostigmine in management of CIPO is biologically plausible due to its ability to increase colonic motility, and early studies on its role are uniformly suggestive of benefit with low side-effect profile. Four clinical studies have been conducted to date, with small sample sizes, heterogeneity and high risk of bias. Further high-quality studies are required to enable assessment of pyridostigmine's utility as an effective management strategy in CIPO.

Review of recent advances on health benefits, microbial transformations, and authenticity identification of Citri reticulatae Pericarpium bioactive compounds

The extensive health-promoting effects of Citri Reticulatae Pericarpium (CRP) have attracted researchers' interest. The difference in storage time, varieties and origin of CRP are closely related to the content of bioactive compounds they contain. The consitituent transformation mediated by environmental microorganisms (bacteria and fungi) and the production of new bioactive components during the storage process may be the main reason for 'the older, the better' of CRP. In addition, the gap in price between different varieties can be as large as 8 times, while the difference due to age can even reach 20 times, making the 'marketing young-CRP as old-CRP and counterfeiting origin' flood the entire market, seriously harming consumers' interests. However, so far, the research on CRP is relatively decentralized. In particular, a summary of the microbial transformation and authenticity identification of CRP has not been reported. Therefore, this review systematically summarized the recent advances on the main bioactive compounds, the major biological activities, the microbial transformation process, the structure, and content changes of the active substances during the transformation process, and authenticity identification of CRP. Furthermore, challenges and perspectives concerning the future research on CRP were proposed.

Effects of Banxia Xiexin Decoction on apoptosis of interstitial cells of cajal by regulation of MiR-451-5p: An in vivo and in vitro study

ETHNOPHARMACOLOGICAL RELEVANCE

Banxia Xiexin Decoction (BXD) is a traditional Chinese medical formula applied to gastrointestinal (GI) motility disorders. Previous studies showed that miR-451-5p was down-regulated in rats with GI motility disorders induced by gastric electrical dysrhythmia. Interstitial cells of cajal (ICCs) are pacemakers for GI motility, while loss of ICCs is responsible for GI motility disturbance. Thus, the underlying interaction mechanisms for BXD regulating ICCs apoptosis via miR-451-5p remain to be explored.

AIM OF THE STUDY

In this work, the main objectives were to examine the efficacy of BXD on ICCs via miR-451-5p both in GI motility disorders rats model and in vitro, as well as the potential contributions of SCF/c-kit signaling.

MATERIALS AND METHODS

Rats with gastric electrical dysrhythmia were established in male SD rats by using a single-day diet and a double fasting method (drinking diluted hydrochloric acid water during the period) for 4 weeks. The gastric slow wave (GSW) recording, RT-qPCR, and western blot were performed to examine the effects of BXD on ICCs apoptosis in rats with GED and miR-451-5p expression. In vitro assays included CCK-8, flow cytometry analysis, RT-qPCR, and western blot were applied to investigate the potential molecular mechanism of BXD on ICCs apoptosis via miR-451-5p.

RESULTS

BXD promoted gastric motility, reduced ICCs apoptosis, and elevated miR-451-5p in GED rats. In addition, miR-451-5p was significantly up-regulated in ICCs after BXD treatment compared with that in ICCs with miR-451-5p inhibitor transfection. Meanwhile, high miR-451-5p expression with either BXD treatment or miRNA mimics enhanced ICCs proliferation and inhibit apoptosis. Moreover, overexpression of miR-451-5p can reverse G0/G1 arrest in ICCs by BXD treatment. Further, SCF and c-kit protein levels were detected to demonstrate that modulation of miR-451-5p by BXD treatment was involved in this signaling.

CONCLUSIONS

Through this study, we demonstrated that BXD could promote ICCs proliferation and inhibit apoptosis via miR-451-5p and may involve the modulations of SCF/c-kit signaling, thus suggesting a new therapy basis for GI motility dysfunction from the perspective of modulation of ICCs apoptosis by targeting miR-451-5p.

Electroceuticals for Neurogastroenterology and Motility Disorders

PURPOSE OF REVIEW

To provide an updated overview on use of electrostimulation in gastrointestinal motility disorders and obesity, with a focus on gastric electrical stimulation, vagal nerve stimulation and sacral nerve stimulation.

RECENT FINDINGS

Recent studies on gastric electrical stimulation for chronic vomiting showed a decrease in frequency of vomiting, but without significant improvement in quality of life. Percutaneous vagal nerve stimulation shows some promise for both symptoms of gastroparesis and IBS. Sacral nerve stimulation does not appear effective for constipation. Studies of electroceuticals for treatment of obesity have quite varied results with less clinical penetrance of the technology. Results of studies on the efficacy of electroceuticals have been variable depending on pathology but this area remains promising. Improved mechanistic understanding, technology and more controlled trials will be helpful to establish a clearer role for electrostimulation in treatment of various GI disorders.

Sustained ameliorating effects and autonomic mechanisms of transcutaneous electrical acustimulation at ST36 in patients with chronic constipation

BACKGROUND AND AIMS

The treatment of chronic constipation is still a great challenge in clinical practice. This study aimed to determine the efficacy and sustained effects of transcutaneous electrical acustimulation (TEA) at acupoint ST36 on the treatment of chronic constipation and explore possible underlying mechanisms.

METHODS

Forty-four patients with chronic constipation were recruited and randomly assigned to a TEA group or sham-TEA group. A bowel diary was recorded by the patients. The Patient Assessment of Constipation Symptom (PAC-SYM) and the Patient Assessment of Constipation Quality of Life (PAC-QoL) questionnaires were administered during each visit. Anal and rectal functions were evaluated with anorectal manometry. Autonomic functions were assessed by the special analysis of heart rate variability derived from the ECG recording.

RESULTS

Compared with sham-TEA, 2-week TEA treatment significantly increased the number of spontaneous bowel movements (SBMs) (5.64 ± 0.54 vs. 2.82 ± 0.36, P < 0.001) and lowered the total scores of PAC-SYM (0.90 ± 0.14 vs. 1.35 ± 0.13, P < 0.001) and PAC-QoL (0.89 ± 0.13 vs. 1.32 ± 0.14, P < 0.05). TEA improved symptoms, as reflected by a reduction in the straining (P < 0.001), the incomplete defecation (P < 0.05), the frequency of emergency drug use (P < 0.05), the days of abdominal distension (P < 0.01) and an increase in intestinal satisfaction (P < 0.01). Interestingly, the effects of TEA on the improvement of weekly SBMs sustained four weeks after the cessation of treatment (P < 0.001). Anorectal manometry indicated that 2-week treatment of TEA lowered the threshold of first sensation (P < 0.05), desire of defecation (P < 0.01) and maximum tolerable volume (P < 0.001) compared with sham-TEA group. TEA also significantly enhanced vagal activity, reflected by high-frequency band of heart rate variability, compared with sham-TEA (57.86 ± 1.83 vs. 48.51 ± 2.04, P < 0.01).

CONCLUSION

TEA ameliorates constipation with sustained effects, which may be mediated via improvement of rectal sensitivity and enhancement of vagal activity.

CLINICAL TRIAL REGISTRATION

[https://clinicaltrials.gov/], identifier [ChiCTR210004267].

Modulation of the autonomic nervous system by one session of spinal low-level laser therapy in patients with chronic colonic motility dysfunction

Patients with a defecation disorder may not evoke a normal defecation reflex, or the reflex may be excessive, as a dysfunction of the spinal autonomic nervous system. Treatment with various forms of lumbar and sacral neuromodulation have shown symptom improvement, but potential changes in autonomic functioning are rarely studied. Here we evaluate the effects on autonomic function of a single session of low-level laser therapy (LLLT) on the lumbar and sacral spine in 41 patients with chronic gastrointestinal motor dysfunction. The LLLT protocol used red LED light at a wavelength of 660 nm for 10 min and infrared LED light at a wavelength of 840 nm for 10 min, followed by infrared laser light at a wavelength of 825 nm for 10 min. Effects on the autonomic nervous system were assessed by measuring heart rate variability (HRV) changes. Respiratory Sinus Arrhythmia (RSA) and Root Mean Square of Successive Differences (RMSSD) were used to quantify parasympathetic reactivity; the Baevsky’s Stress Index (SI) reflected sympathetic activity while the ratios SI/RSA and SI/RMSSD were used to show shifts in autonomic dominance. The results indicate that lumbar and sacral neuromodulation using light arrays reduced, whereas stimulation by the laser probes significantly increased parasympathetic activity. The light arrays increased whereas the laser probes significantly decreased sympathetic activity (SI). The entire protocol shifted the autonomic balance toward parasympathetic activity. The comparison of actual vs. sham neuromodulation proved that the change in HRV parameters was due to actual light stimulation and not due to the arrays and probe touching the skin. In conclusion, a single session of LLLT markedly affects autonomic nervous system activity reflected in changes in HRV which is only possible by generating activity in the spinal autonomic nerves. These results warrant a study into the effects of LLLT on restoring autonomic dysfunction in chronic refractory colonic motility disorders.

Gastric Electrical Stimulation: Role and Clinical Impact on Chronic Nausea and Vomiting

Gastric electrical stimulation (GES) is currently used as an alternative treatment for medically refractory gastroparesis. GES has been initially developed to accelerate gastric motility, in order to relieve the symptoms of the patients. Subsequent studies, unfortunately, failed to demonstrate the acceleration of gastric emptying using high-frequency stimulation - low energy stimulation although the technique has shown a clinical impact with a reduction of nausea and vomiting for patients with gastroparesis. The present review details the clinical efficacy of GES in gastroparesis as well as its putative mechanisms of action.

Low-frequency electrical stimulation promotes the recovery of gastrointestinal motility following gynecological laparoscopy (Review)

The rapid recovery of gastrointestinal transit is critical for clinical recovery following laparoscopic procedures, including gynecological laparoscopies (GLs). Rehabilitation interventions post-surgery may provide significant prevention against early post-operative gastrointestinal motility disorders and maid aid in the acceleration of post-operative recovery in patients undergoing GLs. Among others, low-frequency electrical stimulation (LFES) has been demonstrated to pronouncedly mitigate the symptoms caused by gastrointestinal motility disorders; thus, this has attracted increasing attention over the past decade. The present study aimed to present an overview of the efficacy and application of LFES in gastrointestinal motility recovery following GL procedures.

A Low Cost, Novel Treatment of Severe Diabetic Gastroparesis Based on Burkitt's Dietary Fiber Hypothesis

We report a seven-year follow-up of a 43-year-old Hispanic female with severe diabetic gastroparesis (GP) and a 42.5 kg weight loss (45% of body mass), who required feeding jejunostomy tube placement. The patient had an excellent response to a treatment regime directed at increasing stool bulk, enhancing gut transit, and mobilizing intestinal gas by using dietary fiber supplements and osmotic laxatives with as needed tap water enemas. Hospital cost savings for this patient exceeded $125,000 annually. This case study suggests that constipation may substantially contribute to GP.

Integrative Effects and Vagal Mechanisms of Transcutaneous Electrical Acustimulation on Gastroesophageal Motility in Patients With Gastroesophageal Reflux Disease

INTRODUCTION

Impaired esophageal and gastric motilities are known to contribute to symptoms of gastroesophageal reflux disease (GERD). However, there is a lack of GERD therapy, targeting both gastric and esophageal functions. This study was designed to investigate the effects of transcutaneous electrical acustimulation (TEA) on symptoms of GERD and gastroesophageal functions and possible mechanisms in patients with GERD.

METHODS

Thirty patients with GERD with ineffective esophageal motility were equally divided and randomized into a 4-week sham-TEA or 4-week TEA treatment. The GERD questionnaire (GerdQ), GERD health-related quality-of-life questionnaire, high-resolution esophageal manometry, a nutrient drink test, the electrogastrogram, and ECG were performed to assess the severity of reflux symptoms, low esophageal sphincter (LES) pressure, distal contractile integral (DCI), gastric accommodation, gastric slow waves (GSW), and autonomic functions, respectively.

RESULTS

Compared with sham-TEA, the 4-week TEA treatment significantly decreased the GerdQ score (P = 0.011) and GERD health-related quality of life (P = 0.028) and improved nutrient drink-induced fullness (P < 0.001) and belching (P < 0.001) in patients with GERD. Although only acute TEA significantly enhanced LES pressure (P < 0.05), both acute and chronic TEA remarkedly increased DCI (P < 0.05) and reduced the incidence of ineffective esophageal contractions during wet swallows (P = 0.02). In addition, chronic TEA significantly increased gastric accommodation and the percentage of postprandial normal GSW compared with sham-TEA and baseline. Concurrently, TEA-enhanced vagal activity (P = 0.02) and the vagal activity positively correlated with LES pressure (r = 0.528; P = 0.003) and DCI (r = 0.522; P = 0.003).

DISCUSSION

The TEA treatment performed in this study improves reflux-related symptoms, increases DCI, reduces the incidence of ineffective esophageal contractions during wet swallows, and improves gastric accommodation and slow waves. The improvement in GERD symptoms might be attributed to the integrative effects of TEA on these gastroesophageal functions mediated via the vagal mechanism.

Tackling the gap in platelet inhibition with oral antiplatelet agents in high-risk patients undergoing percutaneous coronary intervention

Introduction: Oral P2Y₁₂ inhibitors represent the mainstay therapy for the prevention of thrombotic complications in patients presenting with an acute coronary syndrome and/or undergoing percutaneous coronary intervention (PCI). However, the onset of antiplatelet action of the oral P2Y₁₂ inhibitors is affected by their need to be absorbed in the gastrointestinal (GI) tract before becoming systemically available.Areas covered: Following oral intake of P2Y₁₂ inhibitors, the timeframe required for GI absorption leads to a window of inadequate antiplatelet protection during which patients are at increased thrombotic risk. The onset of action of the oral P2Y₁₂ inhibitors is even further delayed in high-risk patients, underscoring the need to define strategies to bridge the gap in platelet inhibitory effects following their intake.Expert opinion: Multiple mechanisms may impair GI absorption leading to a delay in the onset of action of oral P2Y₁₂ inhibitors. Several strategies have been tested to overcome the gap in platelet inhibition in high-risk patients undergoing PCI. These include administration of crushed or chewed tablets to improve the dissolution rate and use of opioid receptor antagonists or metoclopramide to counteract impairment of gastric motility induced by opioids. However, intravenous antiplatelet therapies represent the most effective strategy to bridge such gap in platelet inhibition.

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.

Artificial Neural Network-Based Automatic Detection of Food Intake for Neuromodulation in Treating Obesity and Diabetes

PURPOSE

Neuromodulation, such as vagal nerve stimulation and intestinal electrical stimulation, has been introduced for the treatment of obesity and diabetes. Ideally, neuromodulation should be applied automatically after food intake. The purpose of this study was to develop a method of automatic food intake detection through dynamic analysis of heart rate variability (HRV).

MATERIALS AND METHODS

Two experiments were conducted: (1) a small sample series with a standard test meal and (2) a large sample series with varying meal size. Electrocardiograms (ECGs) were collected in the fasting and postprandial states. Each ECG was processed to compute the HRV. For each HRV segment, time- and frequency-domain features were derived and used as inputs to train and test an artificial neural network (ANN). The ANN was trained and tested with different cross-validation methods.

RESULTS

The highest classification accuracy reached with leave-one-subject-out-leave-one-sample-out cross-validation was 0.93 in experiment 1 and 0.88 in experiment 2. Retraining the ANN on recordings of a subject drastically increased the achieved accuracy for that subject to values of 0.995 and 0.95 in experiments 1 and 2, respectively.

CONCLUSIONS

Automatic food intake detection by ANNs, using features from the HRV, is feasible and may have a great potential for neuromodulation-based treatments of meal-related disorders.

Comparison of the effects of colonic electrical stimulation and prucalopride on gastrointestinal transit and defecation in a canine model of constipation

OBJECTIVE

The aim of this study was to compare the effects of colonic electrical stimulation (CES) and prucalopride on gastrointestinal transit and defecation and to verify the safety of CES in a canine model of constipation.

METHODS

Eight beagles received CES implantation and induction drugs for slow transit constipation (STC). In the STC model, the gastrointestinal transit time (GITT), colonic transit time (CTT), stool frequency and stool consistency were assessed to compare the effects of CES and prucalopride on gastrointestinal transit and defecation. The histocompatibility of the implantable device was evaluated.

RESULTS

The individualized parameters for CES varied greatly among the animals, and the GITTs were not significantly shortened by CES or prucalopride; however, both the CES and prucalopride treatment significantly accelerated CTT and improved stool consistency compared with sham stimulation. CES treatment also resulted in significantly higher stool frequency than prucalopride treatment, which did not significantly change the stool frequency. No severe inflammation response was detected in the gross and microscopic appearance around the implants.

CONCLUSION

CES and prucalopride treatment may yield similar short-term effects for improving gastrointestinal transit and stool consistency, and CES outperformed prucalopride treatment in terms of defecation inducement in the short term. There were ideal levels of endurance and histocompatibility for the animals that underwent CES.

LC-MS-based plasma metabolomics study of the intervention effect of different polar parts of hawthorn on gastrointestinal motility disorder rats

Dyspepsia, one of the most prevalent diseases of the digestive tract that impacts the quality of patient life, is mainly caused by gastrointestinal motility disorder. Hawthorn is a commonly used traditional Chinese medicine for treating dyspepsia, and has been proven to improve gastrointestinal motility. Herein, a rat model of gastrointestinal motility disorder was established by subcutaneous injection with atropine. The modeled rats were treated with four polar parts (T1-4 in descending polarity, corresponding to water, n-butanol, ethyl acetate and petroleum ether extracts, respectively) of hawthorn. Through metabolomics analysis, a total of 20 significantly metabolites were identified with significant changes in their abundance levels and these metabolites were related to many metabolic pathways such as amino acid metabolism and primary bile acid biosynthesis. The results showed that T3 had the best therapeutic effect of promoting gastrointestinal motility. Other parts showed no obvious therapeutic effect, demonstrating that the effective components of hawthorn may be compounds of medium polarity. T3 might achieve good therapeutic effects owing to the gastrointestinal motility promotion activity, and by rectifying the disturbed metabolic pathways in the gastrointestinal motility disorder model.

Intestinal Electrical Stimulation Enhances Release of Postprandial Incretin Hormones Via Cholinergic Mechanisms

INTRODUCTION

Intestinal electrical stimulation (IES) has been reported to reduce body weight and improve glucose tolerance in obese and diabetic rats. Our study aimed to investigate possible IES mechanisms involving incretin hormones using intraduodenal glucose infusion in rats. We hypothesized that the enhanced release of postprandial glucagon-like peptide-1 (GLP-1) at early phase by IES was mediated through neuro/paracrine mechanisms involving the vagal nerve and glucose-dependent insulinotropic peptide (GIP).

METHODS

Fifteen normal male Sprague-Dawley rats chronically implanted with duodenal electrodes for IES, and an intra-duodenum catheter for the infusion of glucose were studied in a series of sessions with IES of different parameters with and without atropine and M3 receptor antagonist. Blood samples were collected via the tail vein for the measurement of blood glucose, and plasma GLP-1, and GIP.

RESULTS

(1) Compared to sham-IES, IES of 0.3 ms reduced blood glucose by 16.5-28.4% between 30 and 120 min (all time points p < 0.05), and IES of 3-ms reduced blood glucose at 60 (12.6%) and 90 min (11.8%). IES of 0.3 ms showed a greater hypoglycemic effect than 3 ms (p = 0.024) at 30 min. (2) IES elevated plasma GLP-1 with 0.3 ms (p = 0.001) and with 3 ms p = 0.03). (3) IES substantially elevated plasma GIP with 0.3 ms (p = 0.002) and with 3 ms (p < 0.001). (4) Pretreatment of atropine and the M3 receptor antagonist 4-DAMP blocked the effects of IES on GLP-1, GIP, and blood glucose.

CONCLUSIONS

IES reduces postprandial blood glucose by enhancing the release of GLP-1 and GIP mediated via the cholinergic mechanism.

Progress in research of gastrointestinal motility regulation

Gastrointestinal motility is an important part of the physiological function of the digestive tract, and its dysfunction is one of the key factors that cause different gastrointestinal motility disorders. These diseases seriously affect patients' normal life. With the development of scientific research and technology, well-designed research studies have been conducted on the regulatory mechanisms of gastrointestinal motility, which mainly include the regulation of gastrointestinal hormones, intestinal microflora, neurotransmitters, brain-gut peptides, interstitial cells of Cajal, and gastrointestinal electrical activities. In addition, current studies have proved that bitter taste receptors have certain regulatory effects on gastrointestinal motility. This paper primarily discusses the relevant pathways controlling gastrointestinal motility.

Bioelectrical Signals for the Diagnosis and Therapy of Functional Gastrointestinal Disorders

Coordinated contractions and motility patterns unique to each gastrointestinal organ facilitate the digestive process. These motor activities are coordinated by bioelectrical events, sensory and motor nerves, and hormones. The motility problems in the gastrointestinal tract known as functional gastrointestinal disorders (FGIDs) are generally caused by impaired neuromuscular activity and are highly prevalent. Their diagnosis is challenging as symptoms are often vague and difficult to localize. Therefore, the underlying pathophysiological factors remain unknown. However, there is an increasing level of research and clinical evidence suggesting a link between FGIDs and altered bioelectrical activity. In addition, electroceuticals (bioelectrical therapies to treat diseases) have recently gained significant interest. This paper gives an overview of bioelectrical signatures of gastrointestinal organs with normal and/or impaired motility patterns and bioelectrical therapies that have been developed for treating FGIDs. The existing research evidence suggests that bioelectrical activities could potentially help to identify the diverse etiologies of FGIDs and overcome the drawbacks of the current clinically adapted methods. Moreover, electroceuticals could potentially be effective in the treatment of FGIDs and replace the limited existing conventional therapies which often attempt to treat the symptoms rather than the underlying condition.

The effect of colonic tissue electrical stimulation and celiac branch of the abdominal vagus nerve neuromodulation on colonic motility in anesthetized pigs

BACKGROUND

Knowledge on optimal electrical stimulation (ES) modalities and region-specific functional effects of colonic neuromodulation is lacking. We aimed to map the regional colonic motility in response to ES of (a) the colonic tissue and (b) celiac branch of the abdominal vagus nerve (CBVN) in an anesthetized porcine model.

METHODS

In male Yucatan pigs, direct ES (10 Hz, 2 ms, 15 mA) of proximal (pC), transverse (tC), or distal (dC) colon was done using planar flexible multi-electrode array panels and CBVN ES (2 Hz, 0.3-4 ms, 5 mA) using pulse train (PT), continuous (10 min), or square-wave (SW) modalities, with or without afferent nerve block (200 Hz, 0.1 ms, 2 mA). The regional luminal manometric changes were quantified as area under the curve of contractions (AUC) and luminal pressure maps generated. Contractions frequency power spectral analysis was performed. Contraction propagation was assessed using video animation of motility changes.

KEY RESULTS

Direct colon ES caused visible local circular (pC, tC) or longitudinal (dC) muscle contractions and increased luminal pressure AUC in pC, tC, and dC (143.0 ± 40.7%, 135.8 ± 59.7%, and 142.0 ± 62%, respectively). The colon displayed prominent phasic pressure frequencies ranging from 1 to 12 cpm. Direct pC and tC ES increased the dominant contraction frequency band (1-6 cpm) power locally. Pulse train CBVN ES (2 Hz, 4 ms, 5 mA) triggered pancolonic contractions, reduced by concurrent afferent block. Colon contractions propagated both orally and aborally in short distances.

CONCLUSION AND INFERENCES

In anesthetized pigs, the dominant contraction frequency band is 1-6 cpm. Direct colonic ES causes primarily local contractions. The CBVN ES-induced pancolonic contractions involve central neural network.

Robotic Setup Promises Consistent Effects of Multilocular Gastrointestinal Electrical Stimulation: First Results of a Porcine Study

BACKGROUND

Electrical stimulation (ES) of several gastrointestinal (GI) segments is a promising therapeutic option for multilocular GI dysmotility, but conventional surgical access by laparotomy involves a high degree of tissue trauma. We evaluated a minimally invasive surgical approach using a robotic surgical system to perform electromyographic (EMG) recordings and ES of several porcine GI segments, comparing these data to an open surgical approach by laparotomy.

MATERIALS AND METHODS

In 5 acute porcine experiments, we placed multiple electrodes on the stomach, duodenum, jejunum, ileum, and colon. Three experiments were performed with a median laparotomy and 2 others using a robotic platform. Multichannel EMGs were recorded, and ES was sequentially delivered with 4 ES parameters to the 5 target segments. We calculated pre- and poststimulatory spikes per minute (Spm) and performed a statistical Poisson analysis.

RESULTS

Electrode placement was achieved in all cases without complications. Increased technical and implantation time were required to achieve the robotic electrode placement, but invasiveness was markedly reduced in comparison to the conventional approach. The highest calculated (c)Spm values were found in the poststimulatory period of the small bowel with both the conventional and robotic approaches. Six of the 20 Poisson test results in the open setup reached statistical significance and 12 were significant in the robotic experiments.

CONCLUSIONS

The robotic setup was less invasive, revealed more consistent effects of multilocular ES in several GI segments, and is a promising option for future preclinical and clinical studies of GI motility disorders.

Potential of Electrical Neuromodulation for Inflammatory Bowel Disease

Inflammatory bowel disease (IBD) is a common chronic inflammatory disease of the digestive tract that is often debilitating. It affects patients' quality of life and imposes a financial burden. Despite advances in treatment with medications such as biologics, a large proportion of patients do not respond to medical therapy or develop adverse events. Therefore, alternative treatment options such as electrical neuromodulation are currently being investigated. Electrical neuromodulation, also called bioelectronic medicine, is emerging as a potential new treatment for IBD. Over the past decade, advancements have been made in electrical neuromodulation. A number of electrical neuromodulation methods, such as vagus nerve stimulation, sacral nerve stimulation, and tibial nerve stimulation, have been tested to treat IBD. A series of animal and clinical trials have been performed to evaluate efficacy with promising results. Although the exact underlying mechanisms of action for electrical neuromodulation remain to be explored, this modality is promising. Further randomized controlled trials and basic experiments are needed to investigate efficacy and clarify intrinsic mechanisms.

Transcutaneous Electrical Acustimulation Improves Gastrointestinal Disturbances Induced by Transcatheter Arterial Chemoembolization in Patients With Liver Cancers

BACKGROUND

Gastrointestinal (GI) disturbances occur in patients who receive chemotherapy via transcatheter arterial chemoembolization (TACE) and could last for an extended period of time in some cases. Antiemetic drugs have a potential risk of developing hepatic failure and are ineffective for delayed nausea and emesis. Transcutaneous electrical acustimulation (TEA) has recently been reported to exert antiemetic and prokinetic effects, but it is unknown whether it has an ameliorating effect on TACE-induced GI disturbances.

AIM

This study was designed to evaluate effects and mechanisms of noninvasive TEA on GI symptoms in patients treated with TACE.

MATERIALS AND METHODS

Seventy-four patients with liver cancers (eighteen female; age 63.4 ± 1.1 years) scheduled for TACE were randomized to TEA (n = 37) or sham-TEA (n = 37). TEA was performed via acupoints, ST36 and PC6 using parameters previously optimized for GI motility (1 h, bid) from the postoperative day 0 (POD0) to POD2. Sham-TEA was performed using the same parameters via non-acupoints. Symptom questionnaires were completed daily. The electrogastrogram (EGG) and electrocardiogram (ECG) were recorded in the fasting state for 30 mins to assess gastric slow waves and autonomic functions, respectively, before and after the 3-day treatment.

RESULTS

1) In the acute phase (<24 h), TEA showed no effects on any of GI symptoms, compared with sham-TEA. 2) In the delayed phase (>24 h), TEA, compared with sham-TEA, decreased the percentage of patients who experienced nausea on POD3 (0% vs. 13.5%, p = 0.021), the nausea score on POD3 (p = 0.022), the anorexia score on POD2 (p = 0.040) and POD3 (p = 0.004), and the bloating score (POD1-3: p < 0.01). 3) In comparison with sham-TEA, TEA increased the number of spontaneous bowel movements (p = 0.001) and the Bristol score of the first stool (p = 0.014) and decreased the number of patients with the use of laxatives (p = 0.022). 4) Physiologically, the 3-day TEA but not sham-TEA increased the percentage of normal gastric slow waves (p < 0.001) and vagal activity (p = 0.006). The vagal activity was negatively correlated with the anorexia score (r = -0.267, p = 0.026). It was found that the sympathovagal ratio and tumor size>5 cm were independent risk factors predicting the occurrence of nausea in patients after TACE.

CONCLUSION

TEA improves major TACE-induced GI disturbances in the delayed phase, including nausea, bloating, impaired gastric pace-making activity, and constipation in patients with liver cancers via the autonomic pathway.

Technical, Medical and Ethical Challenges in Networks of Smart Active Implants

Networks of distributed interactive micro-implants could enhance the treatment of otoneurological conditions such as tinnitus or restore impaired complex physiological/ motor functions such as gastrointestinal motility or grasping. For this, an electrical stimulation of neural and muscular tissue is a key prerequisite. Challenges in the development of such interactive micro-implants are the complex human-machine interface, the wireless power supply, and the long-term stability of implants as well as secure and safe signal transmission. This paper addresses all these topics as well as the ethical, legal and social implications of smart implant networks in general. First achievements of the German innovation cluster INTAKT will be presented.

Ameliorating Effects and Autonomic Mechanisms of Transcutaneous Electrical Acustimulation in Patients With Gastroesophageal Reflux Disease

BACKGROUND/AIM

Gastric dysmotility is one of pathophysiologies of gastroesophageal reflux disease (GERD). The aim of this study was to investigate the effects of transcutaneous electrical acustimulation (TEA) on gastric accommodation and gastric slow waves, and evaluate possible mechanisms in patients with GERD.

METHODS

Thirty patients were studied in two randomized sessions of sham-TEA and TEA with the measurements of esophageal high-resolution manometry (HRM), gastric accommodation assessed by a nutrient-drinking test, electrogastrogram (EGG), electrocardiogram (ECG), and postprandial dyspeptic symptoms.

RESULTS

Compared with sham-TEA, TEA improved nutrient drinking-induced fullness (42.0 ± 3.3 vs. 31.0 ± 3.5, P = 0.003) at 10 min after the drink, and belching right after the drink (22.0 ± 4.6 vs. 11.7 ± 3.1, P = 0.012) and at 10 min (16.0 ± 3.8 vs. 3.0 ± 1.5, P = 0.002) after the drink. TEA also improved gastric accommodation (954 ± 37 mL vs. 857 ± 47 mL, P = 0.001) and normalized maximal drink-induced impairment in gastric slow waves. Concurrently, TEA enhanced vagal activity assessed from spectral analysis of heart rate variability in the postprandial state (0.42 ± 0.03 vs. 0.49 ± 0.04, P = 0.039). The vagal activity was positively correlated with the percentage of normal slow waves (r = 0.528; P = 0.003) and negatively correlated with the regurgitation score (r = -0.408, P = 0.025).

CONCLUSIONS

Acute TEA increases gastric accommodation, improves gastric slow waves, and reduces postprandial fullness and belching, possibly mediated via the vagal mechanisms.

Hypoglycemic Effects of Intestinal Electrical Stimulation by Enhancing Nutrient-Stimulated Secretion of GLP-1 in Rats

PURPOSE

To find out the best location for intestinal electrical stimulation (IES) to decrease hyperglycemia, and mechanisms involving intraluminal nutrients and plasma glucagon-like peptide-1 (GLP-1) MATERIALS AND METHODS: Eight rats had electrodes implanted at the duodenum and ileums for IES. The oral glucose tolerance test (OGTT) was performed with IES and sham-IES and with/without GLP-1 antagonist, exendin. To study the role of intraluminal nutrients, the experiment was repeated using intraperitoneal glucose tolerance test (IPGTT). Glucagon was administrated in the OGTT/IPGTT to induce temporary hyperglycemia.

RESULTS

(1) In the OGTT, IES at the duodenum reduced blood glucose from 30 to 120 min after oral glucose (P < 0.05, vs. sham-IES) and the hypoglycemic effect was more potent than IES at the ileum. (2) The hypoglycemic effect of IES was absent in IPGTT experiment, suggesting the important role of intraluminal nutrients. (3) An increase in GLP-1 was noted in the OGTT with IES at the duodenum in comparison with sham-IES. Moreover, the blocking effect of exendin suggested the role of GLP-1 in the hypoglycemic effect of IES.

CONCLUSIONS

The best stimulation location for IES to decrease hyperglycemia is in the duodenum. The hypoglycemic effect of IES is attributed to the enhancement in nutrient-stimulated release of GLP-1.

Use of Bioelectronics in the Gastrointestinal Tract

Gastrointestinal (GI) motility disorders are major contributing factors to functional GI diseases that account for >40% of patients seen in gastroenterology clinics and affect >20% of the general population. The autonomic and enteric nervous systems and the muscles within the luminal GI tract have key roles in motility. In health, this complex integrated system works seamlessly to transport liquid, solid, and gas through the GI tract. However, major and minor motility disorders occur when these systems fail. Common functional GI motility disorders include dysphagia, gastroesophageal reflux disease, functional dyspepsia, gastroparesis, chronic intestinal pseudo-obstruction, postoperative ileus, irritable bowel syndrome, functional diarrhea, functional constipation, and fecal incontinence. Although still in its infancy, bioelectronic therapy in the GI tract holds great promise through the targeted stimulation of nerves and muscles.

Vagal Nerve Stimulation for Glycemic Control in a Rodent Model of Type 2 Diabetes

BACKGROUND

Vagal nerve stimulation (VNS) has been reported to reduce body weight and improve sympathovagal imbalance in both basic and clinical studies. Its effects on glycemic control were however unclear. The aims of this study were to investigate the effects of VNS with various parameters on blood glucose and its possible mechanisms in rats.

METHODS

A hyperglycemic rodent model induced by glucagon was used initially to optimize the VNS parameters; then, a type 2 diabetic rodent model induced by high-fat diet combined with streptozotocin was used to validate the VNS method. The VNS electrodes were implanted at the dorsal subdiaphragmatic vagus; three subcutaneous electrodes were implanted at the chest area for recording electrocardiogram in rats induced by glucagon.

RESULTS

(1) VNS with short pulse width of 0.3 ms but not 3 ms reduced blood glucose during an oral glucose tolerance test (OGTT), with a 38.4% reduction at 15 min and 26.9% at 30 min (P < 0.05, vs. sham-VNS respectively). (2) VNS at low frequency of 5 Hz but not 14 Hz or 40 Hz reduced blood glucose during the OGTT (P < 0.05, vs. sham-VNS). (3) Intermittent VNS was more potent than continuous VNS (P < 0.01). (4) No difference was found between unilateral VNS and bilateral VNS. (5) VNS enhanced vagal activity (P = 0.005). (6) The hypoglycemic effect of VNS was blocked by glucagon-like peptide-1 (GLP-1) antagonist exendin-4.

CONCLUSIONS

VNS at 5 Hz reduces blood glucose in diabetic rats by enhancing vagal efferent activity and the release of GLP-1.

Colonic electrical stimulation improves colonic transit in rotenone-induced Parkinson's disease model through affecting enteric neurons

AIMS

The aims of this study were to investigate the effect of colonic electrical stimulation (CES) on delayed colonic transit in Parkinson's disease (PD) model induced by rotenone and its possible mechanisms.

MAIN METHODS

Sprague-Dawley male rats were implanted with a pair of electrodes on the serosa at the proximal colon and rotenone was subcutaneously injected for 6 weeks to induce the PD model. Behavior activity, stool volume and open-field test were recorded during the injection. Colonic propulsion rate was measured 6 weeks after rotenone injection. Colon samples of all rats were collected for the measurement of phosphorylated alpha-synuclein, choline acetyltransferase (CHAT), neuronal nitric oxide synthase (nNOS), and tyrosine hydroxylase (TH). The protocols of control rats were the same as the PD rats except that no electrodes were implanted and no rotenone was injected.

KEY FINDINGS

(1) Rotenone-induced PD rats demonstrated weight loss, significant decrease of the dopaminergic neurons in substantia nigra, and impairment of colon movement. (2) CES significantly accelerated the delayed colonic transmit (91.67 ± 5.58% vs 51.33 ± 4.18%), superior to Macrogol-4000. (3) CES significantly upregulated the expression of CHAT, nNOS and TH protein in colon of PD rats. (4) In colon of PD rats, the phosphorylated alpha-synuclein was significantly upregulated, but CES had no significant effect on phosphorylated alpha-synuclein.

SIGNIFICANCE

Our data show that CES can normalize the delayed colonic transit and this normalization may attribute to affecting enteric excitatory and inhibitory neurons.

Bioelectronics for mapping gut activity

Gastric peristalsis is initiated and coordinated by an underlying bioelectrical activity, termed slow waves. High-resolution (HR) mapping of the slow waves has become a fundamental tool for accurately defining electrophysiological properties in gastroenterology, including dysrhythmias in gastric disorders such as gastroparesis and functional dyspepsia. Currently, HR mapping is achieved via acquisition of slow waves taken directly from the serosa of fasted subjects undergoing invasive abdominal surgery. Recently, a minimally invasive retractable catheter and electrode has been developed for HR mapping that can only be used in short-term studies in subjects undergoing laparoscopy. Noninvasive mapping has also emerged from multichannel cutaneous electrogastrography; however, it lacks sufficient resolution and is prone to artifacts. Bioelectronics that can map slow waves in conscious subjects, postprandially and long-term, are in high demand. Due to the low signal-to-noise ratio of cutaneous electrogastrography, electrodes for HR mapping of gut activity have to acquire slow waves directly from the gut; hence, development of novel device implantation methods has inevitably accompanied development of the devices themselves. Initial efforts that have paved the way toward achieving these goals have included development of miniature wireless systems with a limited number of acquisition channels using commercially available off-the-shelf electronic components, flexible HR electrodes, and endoscopic methods for minimally invasive device implantation. To further increase the spatial resolution of HR mapping, and to minimize the size and power consumption of the implant for long-term studies, application-specific integrated circuitry, wireless power transfer, and stretchable electronics technologies have had to be integrated into a single system.

Electroceutical Targeting of the Autonomic Nervous System

Autonomic nerves are attractive targets for medical therapies using electroceutical devices because of the potential for selective control and few side effects. These devices use novel materials, electrode configurations, stimulation patterns, and closed-loop control to treat heart failure, hypertension, gastrointestinal and bladder diseases, obesity/diabetes, and inflammatory disorders. Critical to progress is a mechanistic understanding of multi-level controls of target organs, disease adaptation, and impact of neuromodulation to restore organ function.

Bioelectric neuromodulation for gastrointestinal disorders: effectiveness and mechanisms

The gastrointestinal tract has extensive, surgically accessible nerve connections with the central nervous system. This provides the opportunity to exploit rapidly advancing methods of nerve stimulation to treat gastrointestinal disorders. Bioelectric neuromodulation technology has considerably advanced in the past decade, but sacral nerve stimulation for faecal incontinence currently remains the only neuromodulation protocol in general use for a gastrointestinal disorder. Treatment of other conditions, such as IBD, obesity, nausea and gastroparesis, has had variable success. That nerves modulate inflammation in the intestine is well established, but the anti-inflammatory effects of vagal nerve stimulation have only recently been discovered, and positive effects of this approach were seen in only some patients with Crohn's disease in a single trial. Pulses of high-frequency current applied to the vagus nerve have been used to block signalling from the stomach to the brain to reduce appetite with variable outcomes. Bioelectric neuromodulation has also been investigated for postoperative ileus, gastroparesis symptoms and constipation in animal models and some clinical trials. The clinical success of this bioelectric neuromodulation therapy might be enhanced through better knowledge of the targeted nerve pathways and their physiological and pathophysiological roles, optimizing stimulation protocols and determining which patients benefit most from this therapy.

GASTROINTESTINAL MOTILITY DISORDERS IN OBESITY

The gastrointestinal (GI) motility, which is important for the digestion and absorption, may be altered in obesity. The aim of this review is to present the GI motility changes occurring in obesity, as well as their underlying mechanisms. We have conducted a systematic review of the published literature concerning GI motility and obesity and have described recent published data on the changes throughout the entire GI tract. Most recent discoveries include evidence supporting the increase of gastroesophageal reflux disease in obesity and inhibition of gastric motility. Intestinal transit of the distal small bowel generally slows down, ensuring enough time for digestion and absorption. Constipation is more frequent in obese patients than in those with a normal weight. The gut-brain axis plays an important role in the pathophysiology of GI motility disorders in obesity. This bidirectional communication is achieved by way of neurons, hormones, metabolites derived from intestinal microbiota and cytokines. The molecular mechanisms of GI motility changes in obesity are complex. Current data offer a starting point for further research needed to clarify the association of obesity with GI motility disorders.

Neural Prosthetics:A Review of Empirical vs. Systems Engineering Strategies

Implantable electrical interfaces with the nervous system were first enabled by cardiac pacemaker technology over 50 years ago and have since diverged into almost all of the physiological functions controlled by the nervous system. There have been a few major clinical and commercial successes, many contentious claims, and some outright failures. These tend to be reviewed within each clinical subspecialty, obscuring the many commonalities of neural control, biophysics, interface materials, electronic technologies, and medical device regulation that they share. This review cites a selection of foundational and recent journal articles and reviews for all major applications of neural prosthetic interfaces in clinical use, trials, or development. The hard-won knowledge and experience across all of these fields can now be amalgamated and distilled into more systematic processes for development of clinical products instead of the often empirical (trial and error) approaches to date. These include a frank assessment of a specific clinical problem, the state of its underlying science, the identification of feasible targets, the availability of suitable technologies, and the path to regulatory and reimbursement approval. Increasing commercial interest and investment facilitates this systematic approach, but it also motivates projects and products whose claims are dubious.

Computational motility models of neurogastroenterology and neuromodulation

The success of neuromodulation therapies, particularly in the brain, spinal cord, and peripheral nerves, has been greatly aided by computational, biophysical models. However, treating gastrointestinal disorders with electrical stimulation has been much less explored, partly because the mode of action of such treatments is unclear, and selection of stimulation parameters is often empirical. Progress in gut neuromodulation is limited by the comparative lack of biophysical models capable of simulating neuromodulation of gastrointestinal function. Here, we review the recently developed biophysical models of electrically-active cells in the gastrointestinal system that contribute to motility. Biophysical models are replacing phenomenologically-defined models due to advancements in electrophysiological characterization of key players in the gut: enteric neurons, smooth muscle fibers, and interstitial cells of Cajal. In this review, we explore existing biophysically-defined cellular and network models that contribute to gastrointestinal motility. We focus on recent models that are laying the groundwork for modeling electrical stimulation of the gastrointestinal system. Developing models of gut neuromodulation will improve our mechanistic understanding of these treatments, leading to better parameterization, selectivity, and efficacy of neuromodulation to treat gastrointestinal disorders. Such models may have direct clinical translation to current neuromodulation therapies, such as sacral nerve stimulation.