Anti-inflammatory effects of vagal nerve stimulation with a special attention to intestinal barrier dysfunction

Bidirectional regulation of the brain-gut-microbiota axis following traumatic brain injury

JOURNAL/nrgr/04.03/01300535-202508000-00002/figure1/v/2024-09-30T120553Z/r/image-tiff Traumatic brain injury is a prevalent disorder of the central nervous system. In addition to primary brain parenchymal damage, the enduring biological consequences of traumatic brain injury pose long-term risks for patients with traumatic brain injury; however, the underlying pathogenesis remains unclear, and effective intervention methods are lacking. Intestinal dysfunction is a significant consequence of traumatic brain injury. Being the most densely innervated peripheral tissue in the body, the gut possesses multiple pathways for the establishment of a bidirectional "brain-gut axis" with the central nervous system. The gut harbors a vast microbial community, and alterations of the gut niche contribute to the progression of traumatic brain injury and its unfavorable prognosis through neuronal, hormonal, and immune pathways. A comprehensive understanding of microbiota-mediated peripheral neuroimmunomodulation mechanisms is needed to enhance treatment strategies for traumatic brain injury and its associated complications. We comprehensively reviewed alterations in the gut microecological environment following traumatic brain injury, with a specific focus on the complex biological processes of peripheral nerves, immunity, and microbes triggered by traumatic brain injury, encompassing autonomic dysfunction, neuroendocrine disturbances, peripheral immunosuppression, increased intestinal barrier permeability, compromised responses of sensory nerves to microorganisms, and potential effector nuclei in the central nervous system influenced by gut microbiota. Additionally, we reviewed the mechanisms underlying secondary biological injury and the dynamic pathological responses that occur following injury to enhance our current understanding of how peripheral pathways impact the outcome of patients with traumatic brain injury. This review aimed to propose a conceptual model for future risk assessment of central nervous system-related diseases while elucidating novel insights into the bidirectional effects of the "brain-gut-microbiota axis."

Enteric nervous system dysfunction as a driver of central nervous system disorders: The Forgotten brain in neurological disease

The Enteric Nervous System (ENS), often called the "second brain," is a complex network of neurons and glial cells within the gastrointestinal (GI) tract. It functions autonomously while maintaining close communication with the central nervous system (CNS) via the gut-brain axis (GBA). ENS dysfunction plays a crucial role in neurodegenerative and neurodevelopmental disorders, including Parkinson's disease, Alzheimer's disease, and autism spectrum disorder. Disruptions such as altered neurotransmission, gut microbiota imbalance, and neuroinflammation contribute to disease pathogenesis. The GBA enables bidirectional communication through the vagus nerve, gut hormones, immune signaling, and microbial metabolites, linking gut health to neurological function. ENS dysregulation is implicated in conditions like irritable bowel syndrome (IBS) and inflammatory bowel disease (IBD), influencing systemic and CNS pathology through neuroinflammation and impaired barrier integrity. This review highlights emerging therapeutic strategies targeting ENS dysfunction, including prebiotics, probiotics, fecal microbiota transplantation (FMT), and vagus nerve stimulation, which offer novel ways to modulate gut-brain interactions. Unlike previous perspectives that view the ENS as a passive disease marker, this review repositions it as an active driver of neurological disorders. By integrating advances in ENS biomarkers, therapeutic targets, and GBA modulation, this article presents a paradigm shift-emphasizing ENS dysfunction as a fundamental mechanism in neurodegeneration and neurodevelopmental disorders. This perspective paves the way for innovative diagnostics, personalized gut-targeted therapies, and a deeper understanding of the ENS's role in brain health and disease.

Role of Antioxidants in Modulating the Microbiota-Gut-Brain Axis and Their Impact on Neurodegenerative Diseases

This narrative review presents the role of antioxidants in regulating the gut microbiota and the impact on the gut-brain axis, with a particular focus on neurodegenerative diseases, such as Alzheimer's (AD) and Parkinson's disease (PD). These diseases are characterised by cognitive decline, motor dysfunction, and neuroinflammation, all of which are significantly exacerbated by oxidative stress. This review elucidates the contribution of oxidative damage to disease progression and explores the potential of antioxidants to mitigate these pathological processes through modulation of the gut microbiota and associated pathways. Based on recent studies retrieved from reputable databases, including PubMed, Web of Science, and Scopus, this article outlines the mechanisms by which antioxidants influence gut health and exert neuroprotective effects. Specifically, it discusses how antioxidants, including polyphenols, vitamins, and flavonoids, contribute to the reduction in reactive oxygen species (ROS) production and neuroinflammation, thereby promoting neuronal survival and minimising oxidative damage in the brain. In addition, the article explores the role of antioxidants in modulating key molecular pathways involved in oxidative stress and neuroinflammation, such as the NF-κB, Nrf2, MAPK, and PI3K/AKT pathways, which regulate ROS generation, inflammatory cytokine expression, and antioxidant responses essential for maintaining cellular homeostasis in both the gut and the central nervous system. In addition, this review explores the complex relationship between gut-derived metabolites, oxidative stress, and neurodegenerative diseases, highlighting how dysbiosis-an imbalance in the gut microbiota-can exacerbate oxidative stress and contribute to neuroinflammation, thereby accelerating the progression of such diseases as AD and PD. The review also examines the role of short-chain fatty acids (SCFAs) produced by beneficial gut bacteria in modulating these pathways to attenuate neuroinflammation and oxidative damage. Furthermore, the article explores the therapeutic potential of microbiota-targeted interventions, including antioxidant delivery by probiotics and prebiotics, as innovative strategies to restore microbial homeostasis and support brain health. By synthesising current knowledge on the interplay between antioxidants, the gut-brain axis, and the molecular mechanisms underlying neurodegeneration, this review highlights the therapeutic promise of antioxidant-based interventions in mitigating oxidative stress and neurodegenerative disease progression. It also highlights the need for further research into antioxidant-rich dietary strategies and microbiota-focused therapies as promising avenues for the prevention and treatment of neurodegenerative diseases.

Vagal Nerve Biofeedback Intervention for Improving Health Outcomes Among Ukrainian Forced Migrants: A Proof-of-Concept Study

BACKGROUND

The ongoing conflict in Ukraine has forced numerous migrants into neighboring countries, many suffering from pre-existing or newly acquired physical and mental health conditions. Addressing these complex challenges in humanitarian settings requires innovative, evidence-based interventions that are cost-effective and easy to administer. Drawing upon research highlighting the vagus nerve's role in regulating well-being, we hypothesized that vagal nerve activation could offer a promising therapeutic approach.

METHOD

We conducted a proof-of-concept study in which 21 Ukrainian forced migrants were trained in a biofeedback-guided paced breathing intervention designed to stimulate the vagus nerve and promote self-regulation of stress response systems. Changes in pain perception, perceived stress, blood pressure, and heart rate were assessed before and after the vagal breathing intervention using a t-test. Correlations were examined at baseline.

RESULTS

Statistically significant improvements were observed in all measures except systolic blood pressure, providing preliminary evidence for the efficacy of vagal nerve activation in alleviating stress-related health symptoms.

CONCLUSIONS

This study demonstrates the feasibility and therapeutic potential of a vagal nerve-activating intervention in a humanitarian setting. These findings warrant replication in larger, controlled trials. If substantiated, this low-cost, scalable intervention could help mitigate health burdens among forced migrant populations worldwide.

Mediating Role of Negative Affectivity in the Association Between Lifetime Trauma and Gastrointestinal Symptoms

Background/Objectives: It is increasingly recognized that traumatic life experiences render individuals more vulnerable to gastrointestinal (GI) symptoms and chronic bowel conditions like inflammatory bowel disease (IBD) and irritable bowel syndrome (IBS). In this study, we examined whether this effect is mediated by negative affectivity. Methods: A total of 281 participants recruited in the Netherlands, including 94 with IBD, 95 with IBS and 92 controls, were assessed for lifetime trauma, trait anxiety, depression, and GI (IBD/IBS) disease activity. Results: The results confirmed that negative affectivity fully mediated the association between trauma and GI symptomatology, with trauma and depression explaining 38-40% (IBD|IBS) of the variance in disease activity and trauma and anxiety explaining 31-33% (IBD|IBS) of the variance in disease activity. Upon correction for condition (patient/controls), the predictive capacity increased even further, with trauma and depression now accounting for 43-44% (IBD|IBS) and trauma and anxiety for 40% (IBD and IBS) of the GI symptom heterogeneity. Conclusions: The results are in line with studies linking trauma to negative affectivity and negative affectivity to a more aggressive GI disease course. More generally, they show that the somatic and affective consequences of trauma should not be considered in isolation but must be treated as a covariant whole.

Advancing Therapeutic Solutions for Burn Wounds: Potential Use of Noninvasive Ultrasound-Driven Splenic Stimulation

Significance: Burn wound injuries are a global health challenge, affecting millions annually and resulting in significant morbidity, mortality, and economic burden. The urgent need for accessible and cost-effective therapeutic alternatives, especially for underserved populations, has driven interest in novel approaches such as noninvasive splenic stimulation using pulsed-focused ultrasound (pFUS). This technique targets systemic inflammation, a key factor in delayed wound healing, offering a potential shift in burn care management. Recent Advances: Preclinical studies have shown that pFUS applied to the spleen can accelerate wound healing by activating the cholinergic anti-inflammatory pathway, promoting pro-angiogenic and anti-inflammatory responses. While current treatments-including biologics, antioxidants, and growth factors-have limitations, pFUS presents a noninvasive alternative. One interventional study and ongoing clinical trials are now investigating its application in burn wound care, marking an important step toward clinical translation. Critical Issues: Despite encouraging results, research on splenic stimulation for wound healing remains limited. The small number of studies highlights the need for further investigation into the underlying mechanisms, optimal treatment parameters, and potential risks. Additionally, the scalability and cost-effectiveness of pFUS in diverse clinical settings require thorough evaluation. Future Directions: Ongoing clinical trials will provide critical data on the efficacy and safety of splenic pFUS in burn patients. Future research should focus on expanding clinical studies, refining stimulation protocols, and exploring its broader application in tissue repair. If validated, this approach could offer a cost-effective, noninvasive treatment, particularly valuable in socioeconomically challenged regions.

The dopamine receptor agonist rotigotine attenuated indomethacin-induced enteropathy in the small intestinal mucosa of mice

BACKGROUND

Nonsteroidal anti-inflammatory drugs induced enteropathy is characterized by disruption of the epithelial barrier and immune homeostasis, resulting in symptoms such as congestion, ulcers and inflammation. Research has suggested that dopamine (DA) exerts a protective effect on the gastroduodenal and colonic mucosa. The present study aimed to explore the effect of DA on NSAID-induced injury to the small intestinal mucosa.

METHODS

A mouse model of enteropathy induced by indomethacin (Indo, which is a commonly used NSAID) was established by gavage. The DA agonist rotigotine (Roti) was administered alone or in combination with the DA receptor 2 (DRD2) antagonist domperidone (Domp) to model mice to determine the effect of Roti and the key role of DRD2 in this effect. Bilateral vagotomy was performed to determine whether the effect of Roti was mediated by the brain‒gut axis.

RESULTS

Roti administration attenuated small intestinal injury in Indo-induced model mice. However, Domp administration alone exacerbated this injury. Moreover, Roti mitigated small intestinal injury by increasing Occludin and zonula occludens-1 (ZO-1) expression and decreasing TNF-α and cyclooxygenase 2 (COX-2) expression. However, the effects of Roti were abrogated by Domp. In contrast to Domp, vagotomy before Indo administration did not alter the enteroprotective effects of Roti.

CONCLUSION

The DA receptor agonist Roti attenuated Indo-induced enteropathy via peripheral DRD2 and could be a potential drug for treating NSAID-mediated enteropathy.

The Role of Macronutrients and Gut Microbiota in Neuroinflammation Post-Traumatic Brain Injury: A Narrative Review

Traumatic brain injury (TBI) represents a multifaceted pathological condition resulting from external forces that disrupt neuronal integrity and function. This narrative review explores the intricate relationship between dietary macronutrients, gut microbiota (GM), and neuroinflammation in the TBI. We delineate the dual aspects of TBI: the immediate mechanical damage (primary injury) and the subsequent biological processes (secondary injury) that exacerbate neuronal damage. Dysregulation of the gut-brain axis emerges as a critical factor in the neuroinflammatory response, emphasizing the role of the GM in mediating immune responses. Recent evidence indicates that specific macronutrients, including lipids, proteins, and probiotics, can influence microbiota composition and in turn modulate neuroinflammation. Moreover, specialized dietary interventions may promote resilience against secondary insults and support neurological recovery post-TBI. This review aims to synthesize the current preclinical and clinical evidence on the potential of dietary strategies in mitigating neuroinflammatory pathways, suggesting that targeted nutrition and gut health optimization could serve as promising therapeutic modalities in TBI management.

Gut-microbiota-brain Axis and post-traumatic epilepsy

There has been growing evidence that perturbations in gut-microbiota-brain axis (GMBA) are involved in mechanisms of chronic sequelae of traumatic brain injury (TBI). This review discusses the connection between GMBA and post-traumatic epilepsy (PTE), the latter being a common outcome of TBI. The focus is on two aspects of post-TBI GMBA dysfunction that are relevant to epilepsy. First are impairments in intestinal permeability with subsequent translocation of gut bacteria into the bloodstream. Specifically, endotoxemia following TBI may have a serendipitous protective effect against PTE through lipopolysaccharide conditioning, which may be leveraged for the development of therapeutic interventions. Second are changes in microbial composition (i.e., dysbiosis). Here, the GMBA-PTE connection is explored from predictive biomarker perspective, whereby the risk of PTE can be stratified based on specific microbial profiles. Finally, microbiota transplantation is discussed both as a tool to examine the role of gut microbiota in PTE and as a prelude to novel approaches for PTE therapy and prevention.

Non-pharmaceutical treatments for irritable bowel syndrome

Irritable bowel syndrome (IBS) is a chronic disorder of gut-brain interaction that impacts a significant portion of the population and is associated with substantial morbidity, reduced quality of life, and economic impact globally. The pathophysiology of IBS is complex and incompletely understood, and the heterogeneity of IBS is reflected in the variety of pharmaceutical and non-pharmaceutical therapies utilized for the management of IBS. Given limitations with pharmaceutical treatments, many patients with IBS seek non-pharmaceutical options. Several non-pharmaceutical treatments such as the low FODMAP diet and brain-gut behavior interventions such as gut directed hypnosis and cognitive behavioral therapy are now considered standard of care and are part of all major guidelines for the treatment of IBS. However, challenges with access to and optimal implementation of these therapies remain. This review focuses on the current evidence for common non-pharmaceutical treatments for IBS, including the latest advances in dietary and brain-gut behavioral care, in addition other complementary and integrative health practices and emerging therapies.

Mume fructus alters the abundance of intestinal microbiota and alleviates damaged intestinal barrier and inflammation in rats with DSS induced colitis

The gut microbiota plays a crucial role in the development of colitis by influencing the immune response and inflammation in the colon. Previous research has shown that Mume Fructus, a traditional Chinese medicine, can alleviate colitis by reducing the activity of inflammatory pathways. However, the specific connection between Mume Fructus-treated colitis and regulation of gut flora remains unclear, prompting further investigation. This research aims to delve deeper into the possible impact of the gut microbiota in colitis when treated with the aqueous decoction of Mume Fructus (MF). The effects of MF on rats with DSS-induced colitis were assessed through examination of pathological indicators, intestinal barrier proteins, and analysis of 16S rDNA sequencing to investigate its impact on the gut microbiota. In addition, the colon contents of rats after the administration of MF were transplanted into rats with colitis, and the effect of MF on intestinal flora was verified, and "beneficial bacteria" were identified by 16S rDNA sequencing and Spearman's correlation analysis. In summary, our findings suggest that MF has the potential to ameliorate symptoms of colitis through modulation of intestinal microbiota and restoration of intestinal barrier function.

Non-invasive vagus nerve stimulation in anti-inflammatory therapy: mechanistic insights and future perspectives

Non-invasive vagus nerve stimulation (VNS) represents a transformative approach for managing a broad spectrum of inflammatory and autoimmune conditions, including rheumatoid arthritis and inflammatory bowel disease. This comprehensive review delineates the mechanisms underlying VNS, emphasizing the cholinergic anti-inflammatory pathway, and explores interactions within the neuro-immune and vagus-gut axes based on both clinical outcomes and pre-clinical models. Clinical applications have confirmed the efficacy of VNS in managing specific autoimmune diseases, such as rheumatoid arthritis, and chronic inflammatory conditions like inflammatory bowel disease, showcasing the variability in stimulation parameters and patient responses. Concurrently, pre-clinical studies have provided insights into the potential of VNS in modulating cardiovascular and broader inflammatory responses, paving the way for its translational application in clinical settings. Innovations in non-invasive VNS technology and precision neuromodulation are enhancing its therapeutic potential, making it a viable option for patients who are unresponsive to conventional treatments. Nonetheless, the widespread adoption of this promising therapy is impeded by regulatory challenges, patient compliance issues, and the need for extensive studies on long-term efficacy and safety. Future research directions will focus on refining VNS technology, optimizing treatment parameters, and exploring synergistic effects with other therapeutic modalities, which could revolutionize the management of chronic inflammatory and autoimmune disorders.

Intestinal Permeability In Subjects With Rheumatoid Arthritis: A Critical Therapeutic Priority

Rheumatoid arthritis is increasingly being recognized as the synovial manifestation of a group of systemic autoinflammatory conditions known as immune-mediated inflammatory diseases. While each of these conditions displays unique diagnostic signs and symptoms based on the tissue targeted by inflammation, most immune-mediated inflammatory diseases share common features, including their immune-signaling pathways. Owing to these similarities, great advances have emerged in the past few decades using therapies designed to block downstream inflammatory mediators (eg, cytokine-blocking biologics, Janus Kinase (JAK) inhibitors). Unfortunately, fewer advances have been made in therapies that have the potential to target the upstream antecedents and triggers of these complex inflammatory diseases, such as the immunologic chain of events triggered by intestinal hyperpermeability (ie, leaky gut) or gastrointestinal dysbiosis (ie, alterations in the gut microbiota). In the past few decades, intestinal hyperpermeability has emerged as an important antecedent for a wide range of chronic immunological and metabolic conditions, including celiac disease, obesity, cardiovascular disease, and a number of immune-mediated inflammatory diseases such as inflammatory bowel disease, psoriasis, and rheumatoid arthritis. In this narrative review, we discuss the growing awareness that biomarkers of intestinal permeability are frequently associated with non-gastrointestinal immune-mediated inflammatory diseases, particularly those associated with the gut-joint axis, such as rheumatoid arthritis. We suggest that measures of intestinal permeability, along with lifestyle and nutrient interventions that target gut-barrier function, may be important adjunctive clinical tools to help patients with rheumatoid arthritis achieve and maintain remission.

A review of the pathogenesis of epilepsy based on the microbiota-gut-brain-axis theory

The pathogenesis of epilepsy is related to the microbiota-gut-brain axis, but the mechanism has not been clarified. The microbiota-gut-brain axis is divided into the microbiota-gut-brain axis (upward pathways) and the brain-gut-microbiota axis (downward pathways) according to the direction of conduction. Gut microorganisms are involved in pathological and physiological processes in the human body and participate in epileptogenesis through neurological, immunological, endocrine, and metabolic pathways, as well as through the gut barrier and blood brain barrier mediated upward pathways. After epilepsy, the downward pathway mediated by the HPA axis and autonomic nerves triggers "leaky brain "and "leaky gut," resulting in the formation of microbial structures and enterobacterial metabolites associated with epileptogenicity, re-initiating seizures via the upward pathway. Characteristic changes in microbial and metabolic pathways in the gut of epileptic patients provide new targets for clinical prevention and treatment of epilepsy through the upward pathway. Based on these changes, this review further redescribes the pathogenesis of epilepsy and provides a new direction for its prevention and treatment.

Vagus nerve electrical stimulation in the recovery of upper limb motor functional impairment after ischemic stroke

Ischemic stroke (IS) is characterized by high mortality, disability rates, and a high risk of recurrence. Motor dysfunction, such as limb hemiparesis, dysphagia, auditory disorders, and speech disorders, usually persists after stroke, which imposes a heavy burden on society and the health care system. Traditional rehabilitation therapies may be ineffective in promoting functional recovery after stroke, and alternative strategies are urgently needed. The Food and Drug Administration (FDA) has approved invasive vagus nerve stimulation (iVNS) for the improvement of refractory epilepsy, treatment-resistant depression, obesity, and moderate to severe upper limb motor impairment following chronic ischemic stroke. Additionally, the FDA has approved transcutaneous vagus nerve stimulation (tVNS) for the improvement of cluster headaches and acute migraines. Recent studies have demonstrated that vagus nerve stimulation (VNS) has neuroprotective effects in both transient and permanent cerebral ischemia animal models, significantly improving upper limb motor impairments, auditory deficits, and swallowing difficulties. Firstly, this article reviews two potential neuronal death pathways following IS, including autophagy and inflammatory responses. Then delves into the current status of preclinical and clinical research on the functional recovery following IS with VNS, as well as the potential mechanisms mediating its neuroprotective effects. Finally, the optimal parameters and timing of VNS application are summarized, and the future challenges and directions of VNS in the treatment of IS are discussed. The application of VNS in stroke rehabilitation research has reached a critical stage, and determining how to safely and effectively translate this technology into clinical practice is of utmost importance. Further preclinical and clinical studies are needed to elucidate the therapeutic mechanisms of VNS.

Intestinal Microbiota Interventions to Enhance Athletic Performance-A Review

Recent years have witnessed an uptick in research highlighting the gut microbiota's role as a primary determinant of athletes' health, which has piqued interest in the hypothesis that it correlates with athletes' physical performance. Athletes' physical performances could be impacted by the metabolic activity of the assortment of microbes found in their gut. Intestinal microbiota impacts multiple facets of an athlete's physiology, including immune response, gut membrane integrity, macro- and micronutrient absorption, muscle endurance, and the gut-brain axis. Several physiological variables govern the gut microbiota; hence, an intricately tailored and complex framework must be implemented to comprehend the performance-microbiota interaction. Emerging evidence underscores the intricate relationship between the gut microbiome and physical fitness, revealing that athletes who engage in regular physical activity exhibit a richer diversity of gut microbes, particularly within the Firmicutes phylum, e.g., Ruminococcaceae genera, compared to their sedentary counterparts. In elite sport, it is challenging to implement an unconventional strategy whilst simultaneously aiding an athlete to accomplish feasible, balanced development. This review compiles the research on the effects of gut microbiota modulation on performance in sports and illustrates how different supplementation strategies for gut microbiota have the ability to improve athletic performance by enhancing physical capacities. In addition to promoting athletes' overall health, this study evaluates the existing literature in an effort to shed light on how interventions involving the gut microbiota can dramatically improve performance on the field. The findings should inform both theoretical and practical developments in the fields of sports nutrition and training.

Role of stress and early-life stress in the pathogeny of inflammatory bowel disease

Numerous preclinical and clinical studies have shown that stress is one of the main environmental factor playing a significant role in the pathogeny and life-course of bowel diseases. However, stressful events that occur early in life, even during the fetal life, leave different traces within the central nervous system, in area involved in stress response and autonomic network but also in emotion, cognition and memory regulation. Early-life stress can disrupt the prefrontal-amygdala circuit thus favoring an imbalance of the autonomic nervous system and the hypothalamic-pituitary adrenal axis, resulting in anxiety-like behaviors. The down regulation of vagus nerve and cholinergic anti-inflammatory pathway favors pro-inflammatory conditions. Recent data suggest that emotional abuse at early life are aggravating risk factors in inflammatory bowel disease. This review aims to unravel the mechanisms that explain the consequences of early life events and stress in the pathophysiology of inflammatory bowel disease and their mental co-morbidities. A review of therapeutic potential will also be covered.

Gastric and sacral electrical stimulation for motility disorders-A clinical perspective

BACKGROUND

Electrical stimulation of the gut has been investigated in recent decades with a view to treating various gastro-intestinal motility disorders including, among others, gastric electrical stimulation to relieve nausea and vomiting associated with gastroparesis and sacral neuromodulation to treat fecal incontinence and/or constipation. Although their symptomatic efficacy has been ascertained by randomized controlled trials, their mechanisms of action are not fully understood.

PURPOSE

This review summarizes the past year's literature on the mechanisms of action of gut electrical stimulation therapies, including their impact on the gut-brain axis.

Research progress on intestinal microbiota regulating cognitive function through the gut-brain axis

The intestinal microbiota community is a fundamental component of the human body and plays a significant regulatory role in maintaining overall health and in the management disease states.The intestinal microbiota-gut-brain axis represents a vital connection in the cognitive regulation of the central nervous system by the intestinal microbiota.The impact of intestinal microbiota on cognitive function is hypothesized to manifest through both the nervous system and circulatory system. Imbalances in intestinal microbiota during the perioperative period could potentially contribute to perioperative neurocognitive dysfunction. This article concentrates on a review of existing literature to explore the potential influence of intestinal microbiota on brain and cognitive functions via the nervous and circulatory systems.Additionally, it summarizes recent findings on the impact of perioperative intestinal dysbacteriosis on perioperative neurocognitive dysfunction and suggests novel approaches for prevention and treatment of this condition.

Electroceuticals and Magnetoceuticals in Gastroenterology

In the realm of gastroenterology, the inadequacy of current medical treatments for gastrointestinal (GI) motility disorders and inflammatory bowel disease (IBD), coupled with their potential side effects, necessitates novel therapeutic approaches. Neuromodulation, targeting the nervous system's control of GI functions, emerges as a promising alternative. This review explores the promising effects of vagal nerve stimulation (VNS), magnetic neuromodulation, and acupuncture in managing these challenging conditions. VNS offers targeted modulation of GI motility and inflammation, presenting a potential solution for patients not fully relieved from traditional medications. Magnetic neuromodulation, through non-invasive means, aims to enhance neurophysiological processes, showing promise in improving GI function and reducing inflammation. Acupuncture and electroacupuncture, grounded in traditional medicine yet validated by modern science, exert comprehensive effects on GI physiology via neuro-immune-endocrine mechanisms, offering relief from motility and inflammatory symptoms. This review highlights the need for further research to refine these interventions, emphasizing their prospective role in advancing patient-specific management strategies for GI motility disorders and IBD, thus paving the way for a new therapeutic paradigm.

Enteric neuropathy and the vagus nerve: Therapeutic implications

Enteric neuropathies are characterized by abnormalities of gut innervation, which includes the enteric nervous system, inducing severe gut dysmotility among other dysfunctions. Most of the gastrointestinal tract is innervated by the vagus nerve, the efferent branches of which have close interconnections with the enteric nervous system and whose afferents are distributed throughout the different layers of the digestive wall. The vagus nerve is a key element of the autonomic nervous system, involved in the stress response, at the interface of the microbiota-gut-brain axis, has anti-inflammatory and prokinetic properties, modulates intestinal permeability, and has a significant capacity of plasticity and regeneration. Targeting these properties of the vagus nerve, with vagus nerve stimulation (or non-stimulation/ pharmacological methods), could be of interest in the therapeutic management of enteric neuropathies.

State- and frequency-dependence in autonomic rebalance mediated by intradermal auricular electroacupuncture stimulation

Background

Vagus nerve stimulation (VNS) improves diseases such as refractory epilepsy and treatment-resistant depression, likely by rebalancing the autonomic nervous system (ANS). Intradermal auricular electro-acupuncture stimulation (iaES) produces similar effects. The aim of this study was to determine the effects of different iaES frequencies on the parasympathetic and sympathetic divisions in different states of ANS imbalance.

Methods

We measured heart rate variability (HRV) and heart rate (HR) of non-modeled (normal) rats with the treatment of various frequencies to determine the optimal iaES frequency. The optimized iaES frequency was then applied to ANS imbalance model rats to elucidate its effects.

Results

30 Hz and 100 Hz iaES clearly affected HRV and HR in normal rats. 30 Hz iaES increased HRV, and decreased HR. 100 Hz iaES decreased HRV, and increased HR. In sympathetic excited state rats, 30 Hz iaES increased HRV. 100 Hz iaES increased HRV, and decreased HR. In parasympathetic excited state rats, 30 Hz and 100 Hz iaES decreased HRV. In sympathetic inhibited state rats, 30 Hz iaES decreased HRV, while 100 Hz iaES decreased HR. In parasympathetic inhibited rats, 30 Hz iaES decreased HR and 100 Hz iaES increased HRV.

Conclusion

30 Hz and 100 Hz iaES contribute to ANS rebalance by increasing vagal and sympathetic activity with different amplifications. The 30 Hz iaES exhibited positive effects in all the imbalanced states. 100 Hz iaES suppressed the sympathetic arm in sympathetic excitation and sympathetic/parasympathetic inhibition and suppressed the vagal arm and promoted the sympathetic arm in parasympathetic excitation and normal states.

Neuromodulation and the Gut-Brain Axis: Therapeutic Mechanisms and Implications for Gastrointestinal and Neurological Disorders

The gut-brain axis (GBA) represents a complex, bidirectional communication network that intricately connects the gastrointestinal tract with the central nervous system (CNS). Understanding and intervening in this axis opens a pathway for therapeutic advancements for neurological and gastrointestinal diseases where the GBA has been proposed to play a role in the pathophysiology. In light of this, the current review assesses the effectiveness of neuromodulation techniques in treating neurological and gastrointestinal disorders by modulating the GBA, involving key elements such as gut microbiota, neurotrophic factors, and proinflammatory cytokines. Through a comprehensive literature review encompassing PubMed, Google Scholar, Web of Science, and the Cochrane Library, this research highlights the role played by the GBA in neurological and gastrointestinal diseases, in addition to the impact of neuromodulation on the management of these conditions which include both gastrointestinal (irritable bowel syndrome (IBS), inflammatory bowel disease (IBD), and gastroesophageal reflux disease (GERD)) and neurological disorders (Parkinson's disease (PD), Alzheimer's disease (AD), autism spectrum disorder (ASD), and neuropsychiatric disorders). Despite existing challenges, the ability of neuromodulation to adjust disrupted neural pathways, alleviate pain, and mitigate inflammation is significant in improving the quality of life for patients, thereby offering exciting prospects for future advancements in patient care.

Gut microbiota and intestinal immunity-A crosstalk in irritable bowel syndrome

Irritable bowel syndrome (IBS), one of the most prevalent functional gastrointestinal disorders, is characterized by recurrent abdominal pain and abnormal defecation habits, resulting in a severe healthcare burden worldwide. The pathophysiological mechanisms of IBS are multi-factorially involved, including food antigens, visceral hypersensitivity reactions, and the brain-gut axis. Numerous studies have found that gut microbiota and intestinal mucosal immunity play an important role in the development of IBS in crosstalk with multiple mechanisms. Therefore, based on existing evidence, this paper elaborates that the damage and activation of intestinal mucosal immunity and the disturbance of gut microbiota are closely related to the progression of IBS. Combined with the application prospect, it also provides references for further in-depth exploration and clinical practice.

A gut (microbiome) feeling about addiction: Interactions with stress and social systems

In recent years, an increasing attention has given to the intricate and diverse connection of microorganisms residing in our gut and their impact on brain health and central nervous system disease. There has been a shift in mindset to understand that drug addiction is not merely a condition that affects the brain, it is now being recognized as a disorder that also involves external factors such as the intestinal microbiota, which could influence vulnerability and the development of addictive behaviors. Furthermore, stress and social interactions, which are closely linked to the intestinal microbiota, are powerful modulators of addiction. This review delves into the mechanisms through which the microbiota-stress-immune axis may shape drug addiction and social behaviors. This work integrates preclinical and clinical evidence that demonstrate the bidirectional communication between stress, social behaviors, substance use disorders and the gut microbiota, suggesting that gut microbes might modulate social stress having a significance in drug addiction.

Exploring Electrical Neuromodulation as an Alternative Therapeutic Approach in Inflammatory Bowel Diseases

Background and Objectives: This review systematically evaluates the potential of electrical neuromodulation techniques-vagus nerve stimulation (VNS), sacral nerve stimulation (SNS), and tibial nerve stimulation (TNS)-as alternative treatments for inflammatory bowel disease (IBD), including ulcerative colitis (UC) and Crohn's Disease (CD). It aims to synthesize current evidence on the efficacy and safety of these modalities, addressing the significant burden of IBD on patient quality of life and the limitations of existing pharmacological therapies. Materials and Methods: We conducted a comprehensive analysis of studies from PubMed, focusing on research published between 1978 and 2024. The review included animal models and clinical trials investigating the mechanisms, effectiveness, and safety of VNS, SNS, and TNS in IBD management. Special attention was given to the modulation of inflammatory responses and its impact on gastrointestinal motility and functional gastrointestinal disorders associated with IBD. Results: Preliminary findings suggest that VNS, SNS, and TNS can significantly reduce inflammatory markers and improve symptoms in IBD patients. These techniques also show potential in treating related gastrointestinal disorders during IBD remission phases. However, the specific mechanisms underlying these benefits remain to be fully elucidated, and there is considerable variability in treatment parameters. Conclusions: Electrical neuromodulation holds promise as a novel therapeutic avenue for IBD, offering an alternative to patients who do not respond to traditional treatments or experience adverse effects. The review highlights the need for further rigorous studies to optimize stimulation parameters, understand long-term outcomes, and integrate neuromodulation effectively into IBD treatment protocols.

Unmet needs of drugs for irritable bowel syndrome and inflammatory bowel diseases: interest of vagus nerve stimulation and hypnosis

The gut and the brain communicate bidirectionally through the autonomic nervous system. The vagus nerve is a key component of this gut-brain axis, and has numerous properties such as anti-inflammatory, antinociceptive, anti-depressive effects. A perturbation of this gut-brain communication is involved in the pathogeny of functional digestive disorders, such as irritable bowel syndrome, and inflammatory bowel diseases. Stress plays a role in the pathogeny of these diseases, which are biopsychosocial models. There are presently unmet needs of pharmacological treatments of these chronic debilitating diseases. Treatments are not devoid of side effects, cost-effective, do not cure the diseases, can lose effects over time, thus explaining the poor satisfaction of patients, their lack of compliance, and their interest for non-drug therapies. The gut-brain axis can be targeted for therapeutic purposes in irritable bowel syndrome and inflammatory bowel disease through non-drug therapies, such as hypnosis and vagus nerve stimulation, opening up possibilities for responding to patient expectations.

Transcutaneous vagus nerve stimulation: a new strategy for Alzheimer's disease intervention through the brain-gut-microbiota axis?

Transcutaneous vagus nerve stimulation (tVNS) is an emerging non-invasive technique designed to stimulate branches of the vagus nerve distributed over the body surface. Studies suggest a correlation between the brain-gut-microbiota (BGM) axis and the pathogenesis of Alzheimer's disease (AD). The BGM axis represents a complex bidirectional communication system, with the vagus nerve being a crucial component. Therefore, non-invasive electrical stimulation of the vagus nerve might have the potential to modify-most of the time probably in a non-physiological way-the signal transmission within the BGM axis, potentially influencing the progression or symptoms of AD. This review explores the interaction between percutaneous vagus nerve stimulation and the BGM axis, emphasizing its potential effects on AD. It examines various aspects, such as specific brain regions, gut microbiota composition, maintenance of intestinal environmental homeostasis, inflammatory responses, brain plasticity, and hypothalamic-pituitary-adrenal (HPA) axis regulation. The review suggests that tVNS could serve as an effective strategy to modulate the BGM axis and potentially intervene in the progression or treatment of Alzheimer's disease in the future.

The gut-brain axis in Parkinson's disease

There is a bi-directional communication between the gut, including the microbiota, and the brain through the autonomic nervous system. Accumulating evidence has suggested a bidirectional link between gastrointestinal inflammation and neurodegeneration, in accordance with the concept of the gut-rain axis. An abnormal microbiota-gut-brain interaction contributes to the pathogeny of Parkinson's disease. This supports the hypothesis that Parkinson's disease originates in the gut to spread to the central nervous system, in particular through the vagus nerve. Targeting the gut-to-brain axis with vagus nerve stimulation, fecal microbiota transplantation, gut-selective antibiotics, as well as drugs targeting the leaky gut might be of interest in the management of Parkinson's disease.

The efficacy and safety of transcutaneous auricular vagus nerve stimulation for patients with minimally conscious state: a sham-controlled randomized double-blind clinical trial

Background

Transcutaneous auricular vagus nerve stimulation (taVNS) has emerged as a potentially effective neuromodulation technique for addressing neurological disorders, including disorders of consciousness. Expanding upon our prior clinical study, which demonstrated the superior effectiveness of a 4-week taVNS treatment in patients with minimally conscious state (MCS) compared to those in a vegetative state/unresponsive wakefulness state, the aim of this investigation was to evaluate the safety and therapeutic efficacy of taVNS in individuals with MCS through a sham-controlled randomized double-blind clinical trial.

Methods

A cohort of 50 adult patients (male = 33, female = 17) diagnosed with a MCS were randomly assigned to either the active taVNS (N = 25) or sham taVNS (N = 25) groups. The treatment period lasted for 4 weeks, followed by an 8-week follow-up period. The Coma Recovery Scale-Revised (CRS-R) and Glasgow Coma Scale (GCS) were administered at baseline and weekly during the initial 4 weeks. Additionally, the Disability Rating Scale (DRS) was used to assess the patients' functional abilities via telephone at week 12. Furthermore, various neurophysiological measures, including electroencephalogram (EEG), upper-limb somatosensory evoked potentials (USEP), brainstem auditory evoked potentials (BAEP), and P300 event-related potentials (P300), were employed to monitor changes in brain activity and neural conduction pathways.

Results

The scores for the active taVNS group in the CRS-R and GCS showed greater improvement over time compared to the sham taVNS group (CRS-R: 1-week, Z = -1.248, p = 0.212; 2-week, Z = -1.090, p = 0.276; 3-week, Z = -2.017, p = 0.044; 4-week, Z = -2.267, p = 0.023. GCS: 1-week, Z = -1.325, p = 0.185; 2-week, Z = -1.245, p = 0.213; 3-week, Z = -1.848, p = 0.065; 4-week, Z = -1.990, p = 0.047). Additionally, the EEG, USEP, BAEP, and P300 also demonstrated significant improvement in the active taVNS group compared to the sham taVNS group at week 4 (EEG, Z = -2.086, p = 0.037; USEP, Z = -2.014, p = 0.044; BAEP, Z = -2.298, p = 0.022; P300 amplitude, Z = -1.974, p = 0.049; P300 latency, t = 2.275, p = 0.027). Subgroup analysis revealed that patients with MCS derived greater benefits from receiving taVNS treatment earlier (CRS-R, Disease duration ≤ 1-month, mean difference = 8.50, 95% CI = [2.22, 14.78], p = 0.027; GCS, Disease duration ≤ 1-month, mean difference = 3.58, 95% CI = [0.14, 7.03], p = 0.044). By week 12, the active taVNS group exhibited lower Disability Rating Scale (DRS) scores compared to the sham taVNS group (Z = -2.105, p = 0.035), indicating a more favorable prognosis for MCS patients who underwent taVNS. Furthermore, no significant adverse events related to taVNS were observed during treatment.

Conclusion

The findings of this study suggest that taVNS may serve as a potentially effective and safe intervention for facilitating the restoration of consciousness in individuals diagnosed with MCS. This therapeutic approach appears to enhance cerebral functioning and optimize neural conduction pathways.

Clinical trial registration

http://www.chictr.org.cn, Identifier ChiCTR2200066629.

Non-invasive vagus nerve stimulation: the future of inflammatory bowel disease treatment?

The vagus nerve regulates inflammation and cytokine release through the inflammatory reflex. Recent pilot clinical trials using implantable bioelectronic devices have demonstrated the efficacy of vagus nerve stimulation (VNS) in adult patients with inflammatory bowel diseases (IBD) as an alternative to drug treatments. However, the use of non-invasive VNS should be of interest in adults with IBD and even more in pediatric IBD. In this issue of Bioelectronic Medicine, Sahn et al. report that non-invasive transcutaneous auricular VNS attenuated signs and symptoms in a pediatric cohort with mild to moderate IBD thus opening new therapeutic avenues in the management of pediatric but also adult IBD patients.

The impact of acute and chronic stress on gastrointestinal physiology and function: a microbiota-gut-brain axis perspective

The physiological consequences of stress often manifest in the gastrointestinal tract. Traumatic or chronic stress is associated with widespread maladaptive changes throughout the gut, although comparatively little is known about the effects of acute stress. Furthermore, these stress-induced changes in the gut may increase susceptibility to gastrointestinal disorders and infection, and impact critical features of the neural and behavioural consequences of the stress response by impairing gut-brain axis communication. Understanding the mechanisms behind changes in enteric nervous system circuitry, visceral sensitivity, gut barrier function, permeability, and the gut microbiota following stress is an important research objective with pathophysiological implications in both neurogastroenterology and psychiatry. Moreover, the gut microbiota has emerged as a key aspect of physiology sensitive to the effects of stress. In this review, we focus on different aspects of the gastrointestinal tract including gut barrier function as well as the immune, humoral and neuronal elements involved in gut-brain communication. Furthermore, we discuss the evidence for a role of stress in gastrointestinal disorders. Existing gaps in the current literature are highlighted, and possible avenues for future research with an integrated physiological perspective have been suggested. A more complete understanding of the spatial and temporal dynamics of the integrated host and microbial response to different kinds of stressors in the gastrointestinal tract will enable full exploitation of the diagnostic and therapeutic potential in the fast-evolving field of host-microbiome interactions.

The enteric nervous system

Of all the organ systems in the body, the gastrointestinal tract is the most complicated in terms of the numbers of structures involved, each with different functions, and the numbers and types of signaling molecules utilized. The digestion of food and absorption of nutrients, electrolytes, and water occurs in a hostile luminal environment that contains a large and diverse microbiota. At the core of regulatory control of the digestive and defensive functions of the gastrointestinal tract is the enteric nervous system (ENS), a complex system of neurons and glia in the gut wall. In this review, we discuss 1) the intrinsic neural control of gut functions involved in digestion and 2) how the ENS interacts with the immune system, gut microbiota, and epithelium to maintain mucosal defense and barrier function. We highlight developments that have revolutionized our understanding of the physiology and pathophysiology of enteric neural control. These include a new understanding of the molecular architecture of the ENS, the organization and function of enteric motor circuits, and the roles of enteric glia. We explore the transduction of luminal stimuli by enteroendocrine cells, the regulation of intestinal barrier function by enteric neurons and glia, local immune control by the ENS, and the role of the gut microbiota in regulating the structure and function of the ENS. Multifunctional enteric neurons work together with enteric glial cells, macrophages, interstitial cells, and enteroendocrine cells integrating an array of signals to initiate outputs that are precisely regulated in space and time to control digestion and intestinal homeostasis.

Bowel inflammatory presentations on computed tomography in adult patients with severe aplastic anemia during flared inflammatory episodes

BACKGROUND

Patients with severe aplastic anemia (SAA) frequently present with inflammatory episodes, and during flared inflammatory episodes, hematopoietic function is further exacerbated. The gastrointestinal tract is the most common site for infectious and inflammatory diseases, and its structural and functional features confer on it the most potent capacity to affect hematopoietic and immune functions. Computed tomography (CT) is a readily accessible approach to provide highly useful information in detecting morphological changes and guiding further work-ups.

AIM

To explore CT imaging presentations of gut inflammatory damage in adult SAA patients during inflammatory episodes.

METHODS

We retrospectively evaluated the abdominal CT imaging presentations of 17 hospitalized adult patients with SAA in search of the inflammatory niche when they presented with systemic inflammatory stress and exacerbated hematopoietic function. In this descriptive manuscript, the characteristic images that suggested the presence of gastrointestinal inflammatory damage and related imaging presentations of individual patients were enumerated, analyzed and described.

RESULTS

All eligible patients with SAA had CT imaging abnormalities that suggested the presence of an impaired intestinal barrier and increased epithelial permeability. The inflammatory damages were concurrently present in the small intestine, the ileocecal region and the large intestines. Some readily identified imaging signs, such as bowel wall thickening with mural stratification (“water holo sign”, “fat holo sign”, intramural gas and subserosal pneumatosis) and mesenteric fat proliferation (fat stranding and “creeping fat sign”), fibrotic bowel wall thickening, “balloon sign”, rugged colonic configuration, heterogeneity in the bowel wall texture, and adhered and clustered small bowel loop (including various patterns of “abdominal cocoon”), occurred at a high incidence, which suggested that the damaged gastrointestinal tract is a common inflammatory niche responsible for the systemic inflammatory stresses and the exacerbated hematopoietic failure in patients with SAA. Particularly, the “fat holo sign” was present in 7 patients, a rugged colonic configuration was present in 10 patients, the adhesive bowel loop was present in 15 patients, and extraintestinal manifestations suggestive of tuberculosis infections were present in 5 patients. According to the imaging features, a suggestive diagnosis of Crohn’s disease was made in 5 patients, ulcerative colitis in 1 patient, chronic periappendiceal abscess in 1 patient, and tuberculosis infection in 5 patients. Other patients were diagnosed with chronic enteroclolitis with acutely aggravated inflammatory damage.

CONCLUSION

Patients with SAA had CT imaging patterns that suggested the presence of active chronic inflammatory conditions and aggravated inflammatory damage during flared inflammatory episodes.

Gut microbiome and neurosurgery: Implications for treatment

Introduction

The aim of this review is to summarize the current understanding of the gut‐brain axis (GBA), its impact on neurosurgery, and its implications for future treatment.

Background

An abundance of research has established the existence of a collection of pathways between the gut microbiome and the central nervous system (CNS), commonly known as the GBA. Complicating this relationship, the gut microbiome bacterial diversity appears to change with age, antibiotic exposure and a number of external and internal factors.

Methods

In this paper, we present the current understanding of the key protective and deleterious roles the gut microbiome plays in the pathogenesis of several common neurosurgical concerns.

Results

Specifically, we examine how spinal cord injury, traumatic brain injury and stroke may cause gut microbial dysbiosis. Furthermore, this link appears to be bidirectional as gut dysbiosis contributes to secondary CNS injury in each of these ailment settings. This toxic cycle may be broken, and the future secondary damage rescued by timely, therapeutic, gut microbiome modification. In addition, a robust gut microbiome appears to improve outcomes in brain tumour treatment. There are several primary routes by which microbiome dysbiosis may be ameliorated, including faecal microbiota transplant, oral probiotics, bacteriophages, genetic modification of gut microbiota and vagus nerve stimulation.

Conclusion

The GBA represents an important component of patient care in the field of neurosurgery. Future research may illuminate ideal methods of therapeutic microbiome modulation in distinct pathogenic settings.