The way you move

Glial cells in the gut are specialized to fine-tune intestinal function.

Improving Bowel Function Recovery and Quality of Life in Han Chinese Patients with Spinal Cord Injuries: A Quantitative Assessment-Based Nursing Intervention Study

BACKGROUND Neurological bowel dysfunction (NBD) due to spinal cord injuries (SCIs) is common and significantly impacts patients' quality of life. This study evaluated the efficacy of quantitative assessment-based nursing interventions on bowel function recovery, quality of life, and caregivers' satisfaction with SCI patients with NBD. MATERIAL AND METHODS The study included 418 SCI patients with NBD. Patients were categorized into 3 cohorts: quantitative assessment-based nursing intervention (QN, n=114), conventional nursing intervention (CN, n=125), or no nursing intervention (DN, n=189). The 3 cohorts were followed over a 6-month period. RESULTS At 6 months post-intervention, patients in the QN and CN cohorts showed significant reductions in symptoms of fecal incontinence, constipation, and abdominal distension compared to the DN cohort. Additionally, defecation time decreased significantly in the QN and CN cohorts compared to both initial measures and the DN cohort. Notably, patients in the QN cohort demonstrated substantial improvement in overall quality of life scores compared to baseline, CN, and DN cohorts. The QN cohort also reported marked improvement in caregivers' satisfaction, surpassing that of caregivers in the CN and DN cohorts. CONCLUSIONS Six months of quantitative assessment-based nursing interventions significantly improved bowel function, quality of life, and caregiver satisfaction in SCI patients with NBD. This intervention appears beneficial for managing NBD in SCI patients and improving their quality of life and caregiver satisfaction.

Galanin Receptors (GALR1, GALR2, and GALR3) Immunoexpression in Enteric Plexuses of Colorectal Cancer Patients: Correlation with the Clinico-Pathological Parameters

Galanin (GAL) is an important neurotransmitter released by the enteric nervous system (ENS) neurons located in the muscularis externa and submucosa enteric plexuses that acts by binding to GAL receptors 1, 2 and 3 (GALR1, 2 and 3). In our previous studies, the GAL immunoexpression was compared in colorectal cancer (CRC) tissue and the adjacent parts of the large intestine wall including myenteric and submucosal plexuses. Recently we have also found that expression levels of GALR1 and GALR3 proteins are elevated in CRC tissue as compared with their expression in epithelial cells of unchanged mucosa. Moreover, higher GALR3 immunoreactivity in CRC cells correlated with better prognosis of CRC patients. To understand the distribution of GALRs in enteric plexuses distal and close to CRC invasion, in the present study we decided to evaluate GALRs expression within the myenteric and submucosal plexuses located proximally and distally to the cancer invasion and correlated the GALRs expression levels with the clinico-pathological data of CRC patients. The immunohistochemical and immunofluorescent methods showed only slightly decreased immunoexpression of GALR1 and GALR3 in myenteric plexuses close to cancer but did not reveal any correlation in the immunoexpression of all three GAL receptors in myenteric plexuses and tumour progression. No significant changes were found between the expression levels of GALRs in submucosal plexuses distal and close to the tumour. However, elevated GALR1 expression in submucosal plexuses in vicinity of CRC correlated with poor prognosis, higher tumour grading and shorter overall survival. When myenteric plexuses undergo morphological and functional alterations characteristic for atrophy, GALRs maintain or only slightly decrease their expression status. In contrast, the correlation between high expression of GALR1 in the submucosal plexuses and overall survival of CRC patients suggest that GAL and GALRs can act as a components of local neuro-paracrine pro-proliferative pathways accelerating the invasion and metastasis of cancer cell. The obtained results suggest an important role of GALR1 in submucosal plexuses function during the progression of CRC and imply that GALR1 expression in submucosal plexuses of ENS could be an important predictive factor for CRC progression.

Avian ceca are indispensable for hindgut enteric nervous system development

The enteric nervous system (ENS), which is derived from enteric neural crest cells (ENCCs), represents the neuronal innervation of the intestine. Compromised ENCC migration can lead to Hirschsprung disease, which is characterized by an aganglionic distal bowel. During the craniocaudal migration of ENCCs along the gut, we find that their proliferation is greatest as the ENCC wavefront passes through the ceca, a pair of pouches at the midgut-hindgut junction in avian intestine. Removal of the ceca leads to hindgut aganglionosis, suggesting that they are required for ENS development. Comparative transcriptome profiling of the cecal buds compared with the interceca region shows that the non-canonical Wnt signaling pathway is preferentially expressed within the ceca. Specifically, WNT11 is highly expressed, as confirmed by RNA in situ hybridization, leading us to hypothesize that cecal expression of WNT11 is important for ENCC colonization of the hindgut. Organ cultures using embryonic day 6 avian intestine show that WNT11 inhibits enteric neuronal differentiation. These results reveal an essential role for the ceca during hindgut ENS formation and highlight an important function for non-canonical Wnt signaling in regulating ENCC differentiation.

Cells of the human intestinal tract mapped across space and time

The cellular landscape of the human intestinal tract is dynamic throughout life, developing in utero and changing in response to functional requirements and environmental exposures. Here, to comprehensively map cell lineages, we use single-cell RNA sequencing and antigen receptor analysis of almost half a million cells from up to 5 anatomical regions in the developing and up to 11 distinct anatomical regions in the healthy paediatric and adult human gut. This reveals the existence of transcriptionally distinct BEST4 epithelial cells throughout the human intestinal tract. Furthermore, we implicate IgG sensing as a function of intestinal tuft cells. We describe neural cell populations in the developing enteric nervous system, and predict cell-type-specific expression of genes associated with Hirschsprung's disease. Finally, using a systems approach, we identify key cell players that drive the formation of secondary lymphoid tissue in early human development. We show that these programs are adopted in inflammatory bowel disease to recruit and retain immune cells at the site of inflammation. This catalogue of intestinal cells will provide new insights into cellular programs in development, homeostasis and disease.

Dietary Influences on the Microbiota-Gut-Brain Axis

Over unimaginable expanses of evolutionary time, our gut microbiota have co-evolved with us, creating a symbiotic relationship in which each is utterly dependent upon the other. Far from confined to the recesses of the alimentary tract, our gut microbiota engage in complex and bi-directional communication with their host, which have far-reaching implications for overall health, wellbeing and normal physiological functioning. Amongst such communication streams, the microbiota–gut–brain axis predominates. Numerous complex mechanisms involve direct effects of the microbiota, or indirect effects through the release and absorption of the metabolic by-products of the gut microbiota. Proposed mechanisms implicate mitochondrial function, the hypothalamus–pituitary–adrenal axis, and autonomic, neuro-humeral, entero-endocrine and immunomodulatory pathways. Furthermore, dietary composition influences the relative abundance of gut microbiota species. Recent human-based data reveal that dietary effects on the gut microbiota can occur rapidly, and that our gut microbiota reflect our diet at any given time, although much inter-individual variation pertains. Although most studies on the effects of dietary macronutrients on the gut microbiota report on associations with relative changes in the abundance of particular species of bacteria, in broad terms, our modern-day animal-based Westernized diets are relatively high in fats and proteins and impoverished in fibres. This creates a perfect storm within the gut in which dysbiosis promotes localized inflammation, enhanced gut wall permeability, increased production of lipopolysaccharides, chronic endotoxemia and a resultant low-grade systemic inflammatory milieu, a harbinger of metabolic dysfunction and many modern-day chronic illnesses. Research should further focus on the colony effects of the gut microbiota on health and wellbeing, and dysbiotic effects on pathogenic pathways. Finally, we should revise our view of the gut microbiota from that of a seething mass of microbes to one of organ-status, on which our health and wellbeing utterly depends. Future guidelines on lifestyle strategies for wellbeing should integrate advice on the optimal establishment and maintenance of a healthy gut microbiota through dietary and other means. Although we are what we eat, perhaps more importantly, we are what our gut microbiota thrive on and they thrive on what we eat.

RET compound inheritance in Chinese patients with Hirschsprung disease: lack of penetrance from insufficient gene dysfunction

Hirschsprung disease (HSCR) is a neurocristopathy characterized by the absence of enteric ganglia along variable lengths of the intestine. Genetic defects play a major role in HSCR pathogenesis with nearly 50% of patients having a structural or regulatory deficiency in the major susceptibility gene RET. However, complete molecular defects remain poorly characterized in most patients. Here, we performed detailed genetic, molecular, and populational investigations of rare null mutations and modifiers at the RET locus. We first verified the pathogenicity of three RET splice site mutants (c.1879 + 1G > A, c.2607 + 5G > A and c.2608-3C > G) at the RNA level. We also identified significantly higher risk allele (genotype) frequencies, and their over-transmission, from unaffected parents to affected offspring of three functionally independent enhancer variants (rs2506030, rs7069590 and rs2435357, with odd ratios (OR) of 2.09, 2.71 and 7.59, respectively, P < 0.001). These three common variants are in significant (P < 4.64 × 10^-186) linkage disequilibrium in the Han Chinese population with ~ 60% of them carrying at least one copy and > 10% with two copies. We show that RET compound inheritance of rare and common variants prevails in 64% (seven out of 11) of Chinese HSCR families. This study supports the idea that common RET variants can modify the penetrance of rare null RET mutations in HSCR, and the combined high susceptibility allele dosage may constitute the unique raised "risk baseline" among the Chinese population.

The Gut-Brain Axis: How Microbiota and Host Inflammasome Influence Brain Physiology and Pathology

The human microbiota has a fundamental role in host physiology and pathology. Gut microbial alteration, also known as dysbiosis, is a condition associated not only with gastrointestinal disorders but also with diseases affecting other distal organs. Recently it became evident that the intestinal bacteria can affect the central nervous system (CNS) physiology and inflammation. The nervous system and the gastrointestinal tract are communicating through a bidirectional network of signaling pathways called the gut-brain axis, which consists of multiple connections, including the vagus nerve, the immune system, and bacterial metabolites and products. During dysbiosis, these pathways are dysregulated and associated with altered permeability of the blood-brain barrier (BBB) and neuroinflammation. However, numerous mechanisms behind the impact of the gut microbiota in neuro-development and -pathogenesis remain poorly understood. There are several immune pathways involved in CNS homeostasis and inflammation. Among those, the inflammasome pathway has been linked to neuroinflammatory conditions such as multiple sclerosis, Alzheimer's and Parkinson's diseases, but also anxiety and depressive-like disorders. The inflammasome complex assembles upon cell activation due to exposure to microbes, danger signals, or stress and lead to the production of pro-inflammatory cytokines (interleukin-1β and interleukin-18) and to pyroptosis. Evidences suggest that there is a reciprocal influence of microbiota and inflammasome activation in the brain. However, how this influence is precisely working is yet to be discovered. Herein, we discuss the status of the knowledge and the open questions in the field focusing on the function of intestinal microbial metabolites or products on CNS cells during healthy and inflammatory conditions, such as multiple sclerosis, Alzheimer's and Parkinson's diseases, and also neuropsychiatric disorders. In particular, we focus on the innate inflammasome pathway as immune mechanism that can be involved in several of these conditions, upon exposure to certain microbes.

Chronic high fat diet impairs glucagon like peptide-1 sensitivity in vagal afferents

Dysfunction of the gut-brain axis is one of the potential contributors to the pathophysiology of obesity and is therefore a potential target for treatment. Vagal afferents innervating the gut play an important role in controlling energy homeostasis. There is an increasing evidence for the role of vagal afferents in mediating the anorexigenic effects of glucagon-like peptide-1 (GLP-1), an important satiety and incretin hormone. This study aimed to examine the effect of chronic high fat diet on GLP-1 sensitivity in vagal afferents. C57/BL6 mice were fed either a high-fat or low-fat diet for 6-8 weeks. To evaluate gastrointestinal afferent sensitivity and nodose neurons' response to GLP-1, extracellular afferent recordings and patch clamp were performed, respectively. Exendin-4 (Ex-4) was used as an agonist of the GLP-1 receptor. C-Fos Expression was examined as an indication of afferent input to the nucleus tractus solitarius (NTS). Food intake was monitored in real-time before and after Ex-4 treatment to monitor the consequence of the high fat diet on the satiating effect of GLP-1. In high fat fed (HFF) mice, GLP-1 caused lower activation of intestinal afferent nerves, and failed to potentiate mechanosensitive nerve responses compared to low fat fed (LFF). GLP-1 increased excitability in LFF and this effect was reduced in HFF neurons. Consistent with these findings on vagal afferent nerves, GLP-1 receptor stimulation given systemically, had a reduced satiating effect in HFF compared to LFF mice, and neuronal activation in the NTS was also reduced. The present study demonstrated chronic high fat diet impaired vagal afferent responses to GLP-1, resulting in impaired satiety signaling. GLP-1 sensitivity may account for the impairment of satiety signaling in obesity and thus a therapeutic target for obesity treatment.

Neuronal programming by microbiota regulates intestinal physiology

Neural control of the function of visceral organs is essential for homeostasis and health. Intestinal peristalsis is critical for digestive physiology and host defence, and is often dysregulated in gastrointestinal disorders¹. Luminal factors, such as diet and microbiota, regulate neurogenic programs of gut motility^2-5, but the underlying molecular mechanisms remain unclear. Here we show that the transcription factor aryl hydrocarbon receptor (AHR) functions as a biosensor in intestinal neural circuits, linking their functional output to the microbial environment of the gut lumen. Using nuclear RNA sequencing of mouse enteric neurons that represent distinct intestinal segments and microbiota states, we demonstrate that the intrinsic neural networks of the colon exhibit unique transcriptional profiles that are controlled by the combined effects of host genetic programs and microbial colonization. Microbiota-induced expression of AHR in neurons of the distal gastrointestinal tract enables these neurons to respond to the luminal environment and to induce expression of neuron-specific effector mechanisms. Neuron-specific deletion of Ahr, or constitutive overexpression of its negative feedback regulator CYP1A1, results in reduced peristaltic activity of the colon, similar to that observed in microbiota-depleted mice. Finally, expression of Ahr in the enteric neurons of mice treated with antibiotics partially restores intestinal motility. Together, our experiments identify AHR signalling in enteric neurons as a regulatory node that integrates the luminal environment with the physiological output of intestinal neural circuits to maintain gut homeostasis and health.

Potato-Resistant Starch Supplementation Improves Microbiota Dysbiosis, Inflammation, and Gut-Brain Signaling in High Fat-Fed Rats

(1) High-fat (HF) diet leads to gut microbiota dysbiosis which is associated with systemic inflammation. Bacterial-driven inflammation is sufficient to alter vagally mediated satiety and induce hyperphagia. Promoting bacterial fermentation improves gastrointestinal (GI) epithelial barrier function and reduces inflammation. Resistant starch escape digestion and can be fermented by bacteria in the distal gut. Therefore, we hypothesized that potato RS supplementation in HF-fed rats would lead to compositional changes in microbiota composition associated with improved inflammatory status and vagal signaling. (2) Male Wistar rats (n = 8/group) were fed a low-fat chow (LF, 13% fat), HF (45% fat), or an isocaloric HF supplemented with 12% potato RS (HFRS) diet. (3) The HFRS-fed rats consumed significantly less energy than HF animals throughout the experiment. Systemic inflammation and glucose homeostasis were improved in the HFRS compared to HF rats. Cholecystokinin-induced satiety was abolished in HF-fed rats and restored in HFRS rats. HF feeding led to a significant decrease in positive c fiber staining in the brainstem which was averted by RS supplementation. (4) The RS supplementation prevented dysbiosis and systemic inflammation. Additionally, microbiota manipulation via dietary potato RS prevented HF-diet-induced reorganization of vagal afferent fibers, loss in CCK-induced satiety, and hyperphagia.

Implications of Diet and The Gut Microbiome in Neuroinflammatory and Neurodegenerative Diseases

Within the last century, human lifestyle and dietary behaviors have changed dramatically. These changes, especially concerning hygiene, have led to a marked decrease in some diseases, i.e., infectious diseases. However, other diseases that can be attributed to the so-called ‘Western’ lifestyle have increased, i.e., metabolic and cardiovascular disorders. More recently, multifactorial disorders, such as autoimmune and neurodegenerative diseases, have been associated with changes in diet and the gut microbiome. In particular, short chain fatty acid (SCFA)-producing bacteria are of high interest. SCFAs are the main metabolites produced by bacteria and are often reduced in a dysbiotic state, causing an inflammatory environment. Based on advanced technologies, high-resolution investigations of the abundance and composition of the commensal microbiome are now possible. These techniques enable the assessment of the relationship between the gut microbiome, its metabolome and gut-associated immune and neuronal cells. While a growing number of studies have shown the indirect impact of gut metabolites, mediated by alterations of immune-mediated mechanisms, the direct influence of these compounds on cells of the central nervous system needs to be further elucidated. For instance, the SCFA propionic acid (PA) increases the amount of intestine-derived regulatory T cells, which furthermore can positively affect the central nervous system (CNS), e.g., by increasing remyelination. However, the question of if and how PA can directly interact with CNS-resident cells is a matter of debate. In this review, we discuss the impact of an altered microbiome composition in relation to various diseases and discuss how the commensal microbiome is shaped, starting from the beginning of human life.

Nitrergic Enteric Neurons in Health and Disease-Focus on Animal Models

Nitrergic enteric neurons are key players of the descending inhibitory reflex of intestinal peristalsis, therefore loss or damage of these neurons can contribute to developing gastrointestinal motility disturbances suffered by patients worldwide. There is accumulating evidence that the vulnerability of nitrergic enteric neurons to neuropathy is strictly region-specific and that the two main enteric plexuses display different nitrergic neuronal damage. Alterations both in the proportion of the nitrergic subpopulation and in the total number of enteric neurons suggest that modification of the neurochemical character or neuronal death occurs in the investigated gut segments. This review aims to summarize the gastrointestinal region and/or plexus-dependent pathological changes in the number of nitric oxide synthase (NOS)-containing neurons, the NO release and the cellular and subcellular expression of different NOS isoforms. Additionally, some of the underlying mechanisms associated with the nitrergic pathway in the background of different diseases, e.g., type 1 diabetes, chronic alcoholism, intestinal inflammation or ischaemia, will be discussed.

Down syndrome mouse models have an abnormal enteric nervous system

Children with trisomy 21 (Down syndrome [DS]) have a 130-fold increased incidence of Hirschsprung Disease (HSCR), a developmental defect where the enteric nervous system (ENS) is missing from distal bowel (i.e., distal bowel is aganglionic). Treatment for HSCR is surgical resection of aganglionic bowel, but many children have bowel problems after surgery. Post-surgical problems like enterocolitis and soiling are especially common in children with DS. To determine how trisomy 21 affects ENS development, we evaluated the ENS in two DS mouse models, Ts65Dn and Tc1. These mice are trisomic for many chromosome 21 homologous genes, including Dscam and Dyrk1a, which are hypothesized to contribute to HSCR risk. Ts65Dn and Tc1 mice have normal ENS precursor migration at E12.5 and almost normal myenteric plexus structure as adults. However, Ts65Dn and Tc1 mice have markedly reduced submucosal plexus neuron density throughout the bowel. Surprisingly, the submucosal neuron defect in Ts65Dn mice is not due to excess Dscam or Dyrk1a, since normalizing copy number for these genes does not rescue the defect. These findings suggest the possibility that the high frequency of bowel problems in children with DS and HSCR may occur because of additional unrecognized problems with ENS structure.

A new described mechanisms of intestinal glandular atrophy induced by vagal nerve/Auerbach network degeneration following subarachnoid hemorrhage: The first experimental study

Stress ulcers is a trouble complication of subarachnoid hemorrhage (SAH). Although gastrointestinal ulcerations may be attributed to increased HCL secretion in SAH; the exact mechanism of that complication has not been investigated definitively. We studied if vagal network degeneration may cause intestinal atrophy following SAH. Study was conducted on 25 rabbits, with 5 control group (Group-A), 5 SHAM group (Group-B), and 15 SAH group via injection of autologue blood to cisterna magna. Seven animals followed for seven days (Early Decapitated-Group-C) and eight animals followed 21 days (Late Decapitated-Group-D). The vagal nodosal ganglia (NGs), Auerbach plexuses and goblet cells of duodenums were examined by current stereological methods and compared statistically. The mean numbers of degenerated axon density/mm² of gastric branches of vagal nerves was 8 ± 2, 34 ± 11, 189 ± 49 and 322 ± 81 in the Group A, B, C, and D respectively. The mean numbers of degenerated neuron density/mm³ of NGs was 5 ± 2, 54 ± 7, 691 ± 87 and 2930 ± 410 in the Group A, B, C, and D respectively. The mean numbers of degenerated Auerbach neurons 2 ± 1, 4 ± 1, 12 ± 3 and 27 ± 5/mm³ in the Group A, B, C, and D respectively. The mean numbers of degenerated goblet cells/mm³ were 4.3 ± 1.02, 11.5 ± 0.26, 143 ± 26 and 937 ± 65 Group A, B, C, and D respectively. Statistical analysis showed that vagal network ischemia could cause intestinal bleeding and so atrophy in SAH progression. Statistical analyses of groups were; Group-D/Group-A < 0.001, Group-D/Group-B < 0.005, Group-C/Group-A < 0.005. Undiscovered effect of ischemic vagal network injuries should be regarded as a major cause of stress ulcerations following SAH which has not been mentioned in the literature.

Identification of a Rhythmic Firing Pattern in the Enteric Nervous System That Generates Rhythmic Electrical Activity in Smooth Muscle

The enteric nervous system (ENS) contains millions of neurons essential for organization of motor behavior of the intestine. It is well established that the large intestine requires ENS activity to drive propulsive motor behaviors. However, the firing pattern of the ENS underlying propagating neurogenic contractions of the large intestine remains unknown. To identify this, we used high-resolution neuronal imaging with electrophysiology from neighboring smooth muscle. Myoelectric activity underlying propagating neurogenic contractions along murine large intestine [also referred to as colonic migrating motor complexes, (CMMCs)] consisted of prolonged bursts of rhythmic depolarizations at a frequency of ∼2 Hz. Temporal coordination of this activity in the smooth muscle over large spatial fields (∼7 mm, longitudinally) was dependent on the ENS. During quiescent periods between neurogenic contractions, recordings from large populations of enteric neurons, in mice of either sex, revealed ongoing activity. The onset of neurogenic contractions was characterized by the emergence of temporally synchronized activity across large populations of excitatory and inhibitory neurons. This neuronal firing pattern was rhythmic and temporally synchronized across large numbers of ganglia at ∼2 Hz. ENS activation preceded smooth muscle depolarization, indicating rhythmic depolarizations in smooth muscle were controlled by firing of enteric neurons. The cyclical emergence of temporally coordinated firing of large populations of enteric neurons represents a unique neural motor pattern outside the CNS. This is the first direct observation of rhythmic firing in the ENS underlying rhythmic electrical depolarizations in smooth muscle. The pattern of neuronal activity we identified underlies the generation of CMMCs.SIGNIFICANCE STATEMENT How the enteric nervous system (ENS) generates neurogenic contractions of smooth muscle in the gastrointestinal (GI) tract has been a long-standing mystery in vertebrates. It is well known that myogenic pacemaker cells exist in the GI tract [called interstitial cells of Cajal (ICCs)] that generate rhythmic myogenic contractions. However, the mechanisms underlying the generation of rhythmic neurogenic contractions of smooth muscle in the GI tract remains unknown. We developed a high-resolution neuronal imaging method with electrophysiology to address this issue. This technique revealed a novel pattern of rhythmic coordinated neuronal firing in the ENS that has never been identified. Rhythmic neuronal firing in the ENS was found to generate rhythmic neurogenic depolarizations in smooth muscle that underlie contraction of the GI tract.

Intestinal and Gastric Origins for Diabetes Resolution After Bariatric Surgery

PURPOSE OF REVIEW

This paper will review the intestinal and gastric origins for diabetes resolution after bariatric surgery.

RECENT FINDINGS

In addition to the known metabolic effects of changes in the gut hormonal milieu, more recent studies investigating the role of the microbiome and bile acids and changes in nutrient sensing mechanisms have been shown to have glycemic effects in human and animal models. Independent of weight loss, there are multiple mechanisms that may lead to amelioration or resolution of diabetes following bariatric surgery. There is abundant evidence pointing to changes in gut hormones, bile acids, gut microbiome, and intestinal nutrient sensing; more research is needed to clearly delineate their role in regulating energy and glucose homeostasis after bariatric surgery.

Sourcebook update: intestinal smooth muscle contractility and autonomic control

This laboratory practical requires first-year students to anticipate the effects of drugs active at cholinergic and adrenergic receptors on gut motility in order to design experiments during an authentic inquiry exercise. Rather than specifying a strict sequence of drug additions that aim to provide ideal demonstrations of pharmacological and physiological antagonism, I have instead designed switches into the drugs provided and set students, working in small teams, the task of identifying the switched drugs, an inquiry activity. To extend the teamwork aspect, laboratory reports were submitted by the student teams rather than individual students. Staff observed that discussions within the teams were stimulated by the inquiry-led nature of the practical. The quality of the laboratory reports submitted by teams were substantially improved over the individual reports submitted in previous years. (Students previously worked in teams, but simply followed a list of prescribed experiments and wrote individual reports.) Although, in conversation, teams of students had an improved understanding of the regulation of gut motility by the parasympathetic and sympathetic divisions of the autonomic nervous system and could readily distinguish between pharmacological and functional antagonism, no attempt was made to evaluate learning because the revision was triggered by the observed effect of a technical error and was not otherwise planned. It is likely that laboratory practicals, in general, would benefit from inclusion of inquiry.

Electro-acupuncture attenuates inflammatory responses and intraabdominal pressure in septic patients: A randomized controlled trial

BACKGROUND

A pathological increase in intraabdominal pressure (IAP) and inflammatory responses have negative effects on splanchnic, respiratory, cardiovascular, renal, and neurological function in septic patients with intestinal dysfunction. Electro-acupuncture (EA) has been evidenced to have a bidirectional neuron-endocrine-immune system regulating effect in patients with intestinal dysfunction. The purpose of current study was to evaluate the effects of EA at "Zusanli" (ST36) and "Shangjuxu" (ST37) on inflammatory responses and IAP in septic patients with intestinal dysfunction manifested syndrome of obstruction of the bowels Qi.

METHODS

Eighty-two septic patients with intestinal dysfunction manifested syndrome of obstruction of the bowels Qi were randomly assigned to control group (n = 41) and EA group (n = 41). Patients in control group were given conventional therapies including fluid resuscitation, antiinfection, vasoactive agents, mechanical ventilation (MV), supply of enteral nutrition, and glutamine as soon as possible. In addition to conventional therapies, patients in EA group underwent 20-minutes of EA at ST36-ST37 twice a day for 5 days. At baseline, posttreatment 1, 3, and 7 days, serum levels of tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) and IAP levels, were measured, respectively. And days on MV, length of stay in intensive care unit (ICU) and 28 days mortality were recorded.

RESULTS

The serum levels of TNF-α and IL-1β and IAP levels at posttreatment 1, 3, and 7 days were lower significantly in the EA group compared with the control group (mean [SD]; 61.03 [20.39] vs 79.28 [20.69]; P < .005, mean [SD]; 35.34 [18.75] vs 66.53 [30.43]; P < .005 and mean [SD]; 20.32 [11.30] vs 32.99 [20.62]; P = .001, respectively, TNF-α. Mean [SD]; 14.11 [5.21] vs 16.72 [5.59]; P = .032, mean [SD]; 9.02 [3.62] vs 12.10 [4.13]; P = .001 and mean [SD]; 5.11 [1.79] vs 8.19 [2.99]; P < .005, respectively, IL-1β. Mean [SD]; 14.83 [5.58] vs 17.55 [3.37]; P = .009, mean [SD]; 11.20 [2.57] vs 14.85 [3.01]; P < .005 and mean [SD]; 8.62 [2.55] vs 11.25 [2.72]; P < .005, respectively, IAP). There were no significant differences in the duration of MV, length of stay in ICU, and 28d mortality between the groups.

CONCLUSION

EA at ST36-ST37 attenuated inflammatory responses through reduction in serum levels of TNF-α and IL-1β and IAP in septic patients with intestinal dysfunction manifested syndrome of obstruction of the bowels Qi.

A gut feeling: Microbiome-brain-immune interactions modulate social and affective behaviors

The expression of a wide range of social and affective behaviors, including aggression and investigation, as well as anxiety- and depressive-like behaviors, involves interactions among many different physiological systems, including the neuroendocrine and immune systems. Recent work suggests that the gut microbiome may also play a critical role in modulating behavior and likely functions as an important integrator across physiological systems. Microbes within the gut may communicate with the brain via both neural and humoral pathways, providing numerous avenues of research in the area of the gut-brain axis. We are now just beginning to understand the intricate relationships among the brain, microbiome, and immune system and how they work in concert to influence behavior. The effects of different forms of experience (e.g., changes in diet, immune challenge, and psychological stress) on the brain, gut microbiome, and the immune system have often been studied independently. Though because these systems do not work in isolation, it is essential to shift our focus to the connections among them as we move forward in our investigations of the gut-brain axis, the shaping of behavioral phenotypes, and the possible clinical implications of these interactions. This review summarizes the recent progress the field has made in understanding the important role the gut microbiome plays in the modulation of social and affective behaviors, as well as some of the intricate mechanisms by which the microbiome may be communicating with the brain and immune system.

Rictor/TORC2 mediates gut-to-brain signaling in the regulation of phenotypic plasticity in C. elegans

Animals integrate external cues with information about internal conditions such as metabolic state to execute the appropriate behavioral and developmental decisions. Information about food quality and quantity is assessed by the intestine and transmitted to modulate neuronal functions via mechanisms that are not fully understood. The conserved Target of Rapamycin complex 2 (TORC2) controls multiple processes in response to cellular stressors and growth factors. Here we show that TORC2 coordinates larval development and adult behaviors in response to environmental cues and feeding state in the bacterivorous nematode C. elegans. During development, pheromone, bacterial food, and temperature regulate expression of the daf-7 TGF-β and daf-28 insulin-like peptide in sensory neurons to promote a binary decision between reproductive growth and entry into the alternate dauer larval stage. We find that TORC2 acts in the intestine to regulate neuronal expression of both daf-7 and daf-28, which together reflect bacterial-diet dependent feeding status, thus providing a mechanism for integration of food signals with external cues in the regulation of neuroendocrine gene expression. In the adult, TORC2 similarly acts in the intestine to modulate food-regulated foraging behaviors via a PDF-2/PDFR-1 neuropeptide signaling-dependent pathway. We also demonstrate that genetic variation affects food-dependent larval and adult phenotypes, and identify quantitative trait loci (QTL) associated with these traits. Together, these results suggest that TORC2 acts as a hub for communication of feeding state information from the gut to the brain, thereby contributing to modulation of neuronal function by internal state.

Decision-making in all animals, including humans, involves weighing available information about the external environment as well as the animals’ internal conditions. Information about the environment is obtained via the sensory nervous system, whereas internal state can be assessed via cues such as levels of hormones or nutrients. How multiple external and internal inputs are processed in the nervous system to drive behavior or development is not fully understood. In this study, we examine how the nematode C. elegans integrates dietary information received by the gut with environmental signals to alter nervous system function. We have found that a signaling complex, called TORC2, acts in the gut to relay nutrition signals to alter hormonal signaling by the nervous system in C. elegans. Altered neuronal signaling in turn affects a food-dependent binary developmental decision in larvae, as well as food-dependent foraging behaviors in adults. Our results provide a mechanism by which animals prioritize specific signals such as feeding status to appropriately alter their development and/or behavior.

Gut-brain signaling in energy homeostasis: the unexpected role of microbiota-derived succinate

In the context of the obesity epidemic, dietary fibers that are found essentially in fruit and vegetables attract more and more attention, since they exert numerous metabolic benefits resulting in the moderation of body weight. Short-chain fatty acids, such as propionate and butyrate, produced through their fermentation by the intestinal microbiota, have long been thought to be the mediators of these benefits. In fact, propionate and butyrate were recently shown to activate intestinal gluconeogenesis, a function exerting metabolic benefits via its capacity of signaling to the brain by gastrointestinal nerves. Recently, succinate, the precursor of propionate in the bacterial metabolism, has also been shown to exert signaling properties, including the activation of intestinal gluconeogenesis.

Muscularis macrophages: Key players in intestinal homeostasis and disease

•

Muscularis macrophages densily colonize the outermost layer of the gastrointestinal tract.

•

Muscularis macrophages communicate with enteric neurons in a bidirectional matter.

•

Muscularis macrophages are tissue-protective but can contribute to disease.

•

Current challenges are to decipher therapeutic potentials of muscularis macrophages.

Macrophages residing in the muscularis externa of the gastrointestinal tract are highly specialized cells that are essential for tissue homeostasis during steady-state conditions as well as during disease. They are characterized by their unique protective functional phenotype that is undoubtedly a consequence of the reciprocal interaction with their environment, including the enteric nervous system. This muscularis macrophage-neuron interaction dictates intestinal motility and promotes tissue-protection during injury and infection, but can also contribute to tissue damage in gastrointestinal disorders such as post-operative ileus and gastroparesis. Although the importance of muscularis macrophages is clearly recognized, different aspects of these cells remain largely unexplored such their origin, longevity and instructive signals that determine their function and phenotype. In this review, we will discuss the phenotype, functions and origin of muscularis macrophages during steady-state and disease conditions. We will highlight the bidirectional crosstalk with neurons and potential therapeutic strategies that target and manipulate muscularis macrophages to restore their protective signature as a treatment for disease.

Endocrine cells producing peptide hormones in the intestine of Nile tilapia: distribution and effects of feeding and fasting on the cell density

Endocrine cells (ECs) act as a luminal surveillance system responding to either the presence or absence of food in the gut through the secretion of peptide hormones. The aim of this study was to analyze the effects of feeding and fasting on the EC peptide-specific distribution along the intestine of Nile tilapia. We assessed the density of ECs producing gastrin (GAS), cholecystokinin-8 (CCK-8), neuropeptide Y (NPY), and calcitonin gene-related peptide (CGRP) in nine segments of the intestine using immunohistochemistry. Our results show that ECs immunoreactive to CCK-8, GAS, NPY, and CGRP can be found along all the intestinal segments sampled, from the midgut to hindgut, although differences in their distribution along the gut were observed. Regarding nutrient status, we found that the anterior segments of the midgut seem to be the main site responding to luminal changes in Nile tilapia. The NPY+ and CGRP+ EC densities increased in the fasted group, while the amount of CCK-8+ ECs were higher in the fed group. No effects of fasting or feeding were found in the GAS+ EC densities. Changes in ECs density were found only at the anterior segments of the intestine which may be due to the correlation between vagus nerve anatomy, EC location, and peptide turnover. Lastly, ECs may need to be considered an active cell subpopulation that may adapt and respond to different nutrient status as stimuli. Due to the complexity of the enteroendocrine system and its importance in fish nutrition, much remains to be elucidated and it deserves closer attention.

Abdominal massage for neurogenic bowel dysfunction in people with multiple sclerosis (AMBER - Abdominal Massage for Bowel Dysfunction Effectiveness Research): study protocol for a randomised controlled trial

BACKGROUND

Multiple sclerosis (MS) is a life-long condition primarily affecting younger adults. Neurogenic bowel dysfunction (NBD) occurs in 50-80% of these patients and is the term used to describe constipation and faecal incontinence, which often co-exist. Data from a pilot study suggested feasibility of using abdominal massage for the relief of constipation, but the effectiveness remains uncertain.

METHODS/DESIGN

This is a multi-centred patient randomised superiority trial comparing an experimental strategy of once daily abdominal massage for 6 weeks against a control strategy of no massage in people with MS who have stated that their constipation is bothersome. The primary outcome is the Neurogenic Bowel Dysfunction Score at 24 weeks. Both groups will receive optimised advice plus the MS Society booklet on bowel management in MS, and will continue to receive usual care. Participants and their clinicians will not be blinded to the allocated intervention. Outcome measures are primarily self-reported and submitted anonymously. Central trial staff who will manage and analyse the trial data will be unaware of participant allocations. Analysis will follow intention-to-treat principles.

DISCUSSION

This pragmatic randomised controlled trial will demonstrate if abdominal massage is an effective, cost-effective and viable addition to the treatment of NBD in people with MS.

TRIAL REGISTRATION

ClinicalTrials.gov, ISRCTN85007023 . Registered on 10 June 2014.

Constipation: Pathophysiology and Current Therapeutic Approaches

Chronic constipation is a common, persistent condition affecting many patients worldwide, presenting significant economic burden and resulting in substantial healthcare utilization. In addition to infrequent bowel movements, the definition of constipation includes excessive straining, a sense of incomplete evacuation, failed or lengthy attempts to defecate, use of digital manoeuvres for evacuation of stool, abdominal bloating, and hard consistency of stools. After excluding secondary causes of constipation, chronic idiopathic or primary constipation can be classified as functional defecation disorder, slow-transit constipation (STC), and constipation-predominant irritable bowel syndrome (IBS-C). These classifications are not mutually exclusive and significant overlap exists. Initial therapeutic approach to primary constipation, regardless of aetiology, consists of diet and lifestyle changes such as encouraging adequate fluid and fibre intake, regular exercise, and dietary modification. Laxatives are the mainstay of pharmacologic treatment for potential long-term therapy in patients who do not respond to lifestyle or dietary modification. After a failed empiric trial of laxatives, diagnostic testing is necessary to understand underlying anorectal and/or colonic pathophysiology. No single test provides a comprehensive assessment for primary constipation; therefore, multiple tests are used to provide complementary information to one another. Dyssynergic defecation, a functional defecation disorder, is an acquired behavioural disorder of defecation present in two-thirds of adult patients, where an inability to coordinate the abdominal, recto-anal, and pelvic floor muscles during attempted defecation exists. Biofeedback therapy is the mainstay treatment for dyssynergic defecation aimed at improving coordination of abdominal and anorectal muscles. A large percentage of patients with dyssynergic defecation also exhibit rectal hyposensitivity and may benefit from the addition of sensory retraining. Our understanding of the pathophysiology of STC is evolving. The advent of high-resolution colonic manometry allows for the improved identification of colonic motor patterns and may provide further insight into pathophysiological mechanisms. In a minority of cases of STC, identification of colonic neuropathy suggests a medically refractory condition, warranting consideration of colectomy. The pathophysiology of IBS-C is poorly understood with multiple etiological factors implicated. Pharmacological advances in the treatment of primary constipation have added therapeutic options to the armamentarium of this disorder. Drug development in the secretagogue, serotonergic prokinetic, and ileal bile acid transporter inhibition pathways has yielded current and future medical treatment options for primary chronic constipation.

Irritable Bowel Syndrome: Pathophysiology and Current Therapeutic Approaches

Irritable bowel syndrome (IBS) is a prevalent condition affecting 10-20% of adults in most countries; IBS results in significant morbidity and health care costs. IBS is a disorder of the brain-gut axis, and recent insights into the pathophysiological mechanisms include altered bile acid metabolism, neurohormonal regulation, immune dysfunction, alterations in the epithelial barrier, and secretory properties of the gut. There remains a significant unmet need for effective treatments, particularly for the pain component of IBS, although the introduction of drugs directed at secretion, motility, and a nonabsorbable antibiotic provides an option for the bowel dysfunction in IBS.

Visceral hypersensitivity in inflammatory bowel diseases and irritable bowel syndrome: The role of proteases

Proteases, enzymes catalyzing the hydrolysis of peptide bonds, are present at high concentrations in the gastrointestinal tract. Besides their well-known role in the digestive process, they also function as signaling molecules through the activation of protease-activated receptors (PARs). Based on their chemical mechanism for catalysis, proteases can be classified into several classes: serine, cysteine, aspartic, metallo- and threonine proteases represent the mammalian protease families. In particular, the class of serine proteases will play a significant role in this review. In the last decades, proteases have been suggested to play a key role in the pathogenesis of visceral hypersensitivity, which is a major factor contributing to abdominal pain in patients with inflammatory bowel diseases and/or irritable bowel syndrome. So far, only a few preclinical animal studies have investigated the effect of protease inhibitors specifically on visceral sensitivity while their effect on inflammation is described in more detail. In our accompanying review we describe their effect on gastrointestinal permeability. On account of their promising results in the field of visceral hypersensitivity, further research is warranted. The aim of this review is to give an overview on the concept of visceral hypersensitivity as well as on the physiological and pathophysiological functions of proteases herein.

ILC3s and the Willow Tree of Voices

Type 3 innate lymphoid cells (ILC3s) and enteric glia, an essential structural component of gut innervation, are well-known regulators of intestinal homeostasis. Ibiza et al. (2016) uncover a new link between commensal bacteria, enteric glial cells, and ILC3s that is required for intestinal homeostasis and defense.

Expression of Cystic Fibrosis Transmembrane Conductance Regulator in Ganglia of Human Gastrointestinal Tract

CF is caused by mutations of the gene encoding the cystic fibrosis transmembrane conductance regulator (CFTR) which is an anion selective transmembrane ion channel that mainly regulates chloride transport, expressed in the epithelia of various organs. Recently, we have demonstrated CFTR expression in the brain, the spinal cord and the sympathetic ganglia. This study aims to investigate the expression and distribution of CFTR in the ganglia of the human gastrointestinal tract. Fresh tissue and formalin-fixed paraffin-embedded normal gastrointestinal tract samples were collected from eleven surgical patients and five autopsy cases. Immunohistochemistry, in situ hybridization, laser-assisted microdissection and nested reverse transcriptase polymerase chain reaction were performed. Expression of CFTR protein and mRNA was detected in neurons of the ganglia of all segments of the human gastrointestinal tract examined, including the stomach, duodenum, jejunum, ileum, cecum, appendix, colon and rectum. The extensive expression of CFTR in the enteric ganglia suggests that CFTR may play a role in the physiology of the innervation of the gastro-intestinal tract. The presence of dysfunctional CFTRs in enteric ganglia could, to a certain extent, explain the gastrointestinal symptoms frequently experienced by CF patients.

Changes in the sympathetic innervation of the gut in rotenone treated mice as possible early biomarker for Parkinson's disease

Introduction

Involvement of the peripheral nervous system (PNS) is relatively common in Parkinson’s disease (PD) patients. PNS alterations appear early in the course of the disease and are responsible for some of the non-motor symptoms observed in PD patients. In previous studies, we have shown that environmental toxins can trigger the disease by acting on the enteric nervous system.

Material and methods

Here, we analyzed the effect of mitochondrial Complex I inhibition on sympathetic neuritis in vivo and sympathetic neurons in vitro. Combining in vivo imaging and protein expression profiling.

Results

we found that rotenone, a widely used mitochondrial Complex I inhibitor decreases the density of sympathetic neurites innervating the gut in vivo, while in vitro, it induces the redistribution of intracellular alpha-synuclein and neurite degeneration. Interestingly, sympathetic neurons are much more resistant to rotenone exposure than mesencephalic dopaminergic neurons.

Conclusion

Altogether, these results suggest that enteric sympathetic denervation could be an initial pre-motor alteration in PD progression that could be used as an early biomarker of the disease.

Electronic supplementary material

The online version of this article (doi:10.1007/s10286-016-0358-6) contains supplementary material, which is available to authorized users.

Holothurian Nervous System Diversity Revealed by Neuroanatomical Analysis

The Echinodermata comprise an interesting branch in the phylogenetic tree of deuterostomes. Their radial symmetry which is reflected in their nervous system anatomy makes them a target of interest in the study of nervous system evolution. Until recently, the study of the echinoderm nervous system has been hindered by a shortage of neuronal markers. However, in recent years several markers of neuronal and fiber subpopulations have been described. These have been used to identify subpopulations of neurons and fibers, but an integrative study of the anatomical relationship of these subpopulations is wanting. We have now used eight commercial antibodies, together with three antibodies produced by our group to provide a comprehensive and integrated description and new details of the echinoderm neuroanatomy using the holothurian Holothuria glaberrima (Selenka, 1867) as our model system. Immunoreactivity of the markers used showed: (1) specific labeling patterns by markers in the radial nerve cords, which suggest the presence of specific nerve tracts in holothurians. (2) Nerves directly innervate most muscle fibers in the longitudinal muscles. (3) Similar to other deuterostomes (mainly vertebrates), their enteric nervous system is composed of a large and diverse repertoire of neurons and fiber phenotypes. Our results provide a first blueprint of the anatomical organization of cells and fibers that form the holothurian neural circuitry, and highlight the fact that the echinoderm nervous system shows unexpected diversity in cell and fiber types and their distribution in both central and peripheral nervous components.

Irritable bowel syndrome and visceral hypersensitivity : risk factors and pathophysiological mechanisms

Irritable bowel syndrome (IBS) is a common functional gastro-intestinal disorder, characterized by abdominal pain and altered intestinal motility. Visceral hypersensitivity is an important hallmark feature of IBS and is believed to underlie abdominal pain in patients with IBS. The two main risk factors associated with the development of IBS are gastrointestinal inflammation and psychological distress. On a peripheral level, visceral sensitivity seems to be modulated by several mechanisms. Immune cells in the mucosal wall, such as mast cells, and enterochromaffin cells may sensitize afferent nerves by release of their mediators. Furthermore, increased mucosal permeability, altered intestinal microflora and dietary habits may contribute to this feature. On a central level, an increased prevalence of psychiatric comorbidities is demonstrated in IBS patients, alongside alterations in the hormonal brain-gut axis, increased vigilance towards intestinal stimuli and functional and structural changes in the brain. The pathogenesis of IBS is complicated and multifactorial and the treatment remains clinically challenging. Dietary measures and symptomatic control are the cornerstones for IBS treatment and may be sufficient for patients experiencing mild symptoms, alongside education, reassurance and an effective therapeutic physician-patient relationship. New pharmacological therapies are aimed at interfering with mediator release and/or blockade of the relevant receptors within the gut wall, while modulation of the intestinal flora and diet may also be of therapeutic benefit. Tricyclic anti-depressants and serotonin reuptake inhibitors act both on a central and peripheral level by modulating pain signalling pathways.

Knockdown of GLP-1 Receptors in Vagal Afferents Affects Normal Food Intake and Glycemia

Nutrient stimulation of enteroendocrine L cells induces the release of the incretin and satiating peptide glucagon-like peptide 1 (GLP-1). The vagus nerve innervates visceral organs and may contribute to the mediation of gut-derived GLP-1's effects on food intake, energy homeostasis, and glycemic control. To test the hypothesis that vagal afferent neuron (VAN) GLP-1 receptors (GLP-1Rs) are necessary for these effects of endogenous GLP-1, we established a novel bilateral nodose ganglia injection technique to deliver a lentiviral vector and to knock down VAN GLP-1Rs in male Sprague Dawley rats. We found that a full expression of VAN GLP-1Rs is not necessary for the maintenance of long-term energy balance in normal eating conditions. VAN GLP-1R knockdown (kd) did, however, increase meal size and accelerated gastric emptying. Moreover, postmeal glycemia was elevated and insulin release was blunted in GLP-1R kd rats, suggesting that VAN GLP-1Rs are physiological contributors to the neuroincretin effect after a meal. Collectively, our results highlight a crucial role for the VANs in mediating the effects of endogenous GLP-1 on food intake and glycemia and may promote the further development of GLP-1-based therapies.

Irritable bowel syndrome in quiescent inflammatory bowel disease: a review

Ongoing troublesome bowel symptoms despite quiescent inflammatory disease are a frequent management challenge when caring for patients with inflammatory bowel disease (IBD). Even when active disease has been excluded the prevalence of residual gastrointestinal symptoms is surprisingly high and the cause often obscure. The presence of a concurrent functional disorder such as irritable bowel syndrome (IBS) is associated with worse quality of life, worse physical functioning, higher prevalence of anxiety and greater health care utilization. Potential etiological mechanisms leading to the development of IBS like symptoms include the development of visceral hypersensitivity following the original inflammatory insult, alteration in cortical processing, dysbiosis and residual subacute inflammation. Therapeutic options for managing IBS in patients with IBD include dietary modification, interventions targeted at correction of visceral sensory dysfunction or cortical processing and modulation of the gut microbiota. As there are few studies specifically examining the treatment of IBS in patients with IBD, the majority of therapeutic interventions are extrapolated from the IBS literature. Given the frequency of residual functional symptoms in IBS, significantly more research is warranted in this field.

Aspects of the non-pharmacological treatment of irritable bowel syndrome

Irritable bowel syndrome (IBS) is one of the most commonly diagnosed gastrointestinal conditions. It represents a significant healthcare burden and remains a clinical challenge. Over the years IBS has been described from a variety of different perspectives; from a strict illness of the gastrointestinal tract (medical model) to a more complex multi-symptomatic disorder of the brain-gut axis (biopsychosocial/psychosomatic model). In this article we present aspects of the pathophysiology and the non-pharmacological treatment of IBS based on current knowledge. Effects of conditioned stress and/or traumatic influences on the emotional system (top-down) as well as effects on the intestine through stressors, infection, inflammation, food and dysbiosis (bottom-up) can affect brain-gut communication and result in dysregulation of the autonomic nervous system (ANS), playing an important role in the pathophysiology of IBS. Conditioned stress together with dysregulation of the autonomic nervous system and the emotional system may involve reactions in which the distress inside the body is not recognized due to low body awareness. This may explain why patients have difficulty identifying their symptoms despite dysfunction in muscle tension, movement patterns, and posture and biochemical functions in addition to gastrointestinal symptoms. IBS shares many features with other idiopathic conditions, such as fibromyalgia, chronic fatigue syndrome and somatoform disorders. The key to effective treatment is a thorough examination, including a gastroenterological examination to exclude other diseases along with an assessment of body awareness by a body-mind therapist. The literature suggests that early interdisciplinary diagnostic co-operation between gastroenterologists and body-mind therapists is necessary. Re-establishing balance in the ANS is an important component of IBS treatment. This article discusses the current knowledge of body-mind treatment, addressing the topic from a practical point of view.

The gut microbiota and its correlations with the central nervous system disorders

A mutual impact of gastrointestinal tract (GIT) and central nervous system (CNS) functions has been recognized since the mid-twentieth century. It is accepted that the so-called gut-brain axis provides a two-way homeostatic communication, through immunological, hormonal and neuronal signals. A dysfunction of this axis has been associated with the pathogenesis of some diseases both within and outside the GIT, that have shown an increase in incidence over the last decades. Studies comparing germ-free animals and animals exposed to pathogenic bacterial infections, probiotics or antibiotics suggest the participation of the microbiota in this communication and a role in host defense, regulation of immunity and autoimmune disease appearance. The GIT could represent a vulnerable area through which pathogens influence all aspects of physiology and even induce CNS neuro-inflammation. All those concepts may suggest the modulation of the gut microbiota as an achievable strategy for innovative therapies in complex disorders. Moving from this background, the present review discusses the relationship between intestinal microbiota and CNS and the effects in health and disease. We particularly look at how the commensal gut microbiota influences systemic immune response in some neurological disorders, highlighting its impact on pain and cognition in multiple sclerosis, Guillain-Barrè Syndrome, neurodevelopmental and behavioral disorders and Alzheimer's disease. In this review we discuss recent studies showing that the potential microbiota-gut-brain dialogue is implicated in neurodegenerative diseases. Gaining a better understanding of the relationship between microbiota and CNS could provide an insight on the pathogenesis and therapeutic strategies of these disorders.

Immunomodulation of enteric neural function in irritable bowel syndrome

Irritable bowel syndrome (IBS) is a common functional gastrointestinal disorder which is characterised by symptoms such as bloating, altered bowel habit and visceral pain. It’s generally accepted that miscommunication between the brain and gut underlies the changes in motility, absorpto-secretory function and pain sensitivity associated with IBS. However, partly due to the lack of disease-defining biomarkers, understanding the aetiology of this complex and multifactorial disease remains elusive. Anecdotally, IBS patients have noted that periods of stress can result in symptom flares and many patients exhibit co-morbid stress-related mood disorders such as anxiety and depression. However, in addition to psychosocial stressors, infection-related stress has also been linked with the initiation, persistence and severity of symptom flares. Indeed, prior gastrointestinal infection is one of the strongest predictors of developing IBS. Despite a lack of overt morphological inflammation, the importance of immune factors in the pathophysiology of IBS is gaining acceptance. Subtle changes in the numbers of mucosal immune cell infiltrates and elevated levels of circulating pro-inflammatory cytokines have been reproducibly demonstrated in IBS populations. Moreover, these immune mediators directly affect neural signalling. An exciting new area of research is the role of luminal microbiota in the modulation of neuro-immune signalling, resulting in local changes in gastrointestinal function and alterations in central neural functioning. Progress in this area has begun to unravel some of the complexities of neuroimmune and neuroendocrine interactions and how these molecular exchanges contribute to GI dysfunction

Orcokinin-like immunoreactivity in central neurons innervating the salivary glands and hindgut of ixodid ticks

Orcokinins are conserved neuropeptides within the Arthropoda but their cellular distribution and functions in ticks are unknown. We use an antibody against the highly conserved N-terminal (NFDEIDR) of mature orcokinin peptides to examine their distribution in six ixodid species: Amblyomma variegatum, Dermacentor reticulatus, Hyalomma anatolicum, Ixodes scapularis, Ixodes ricinus and Rhipicephalus appendiculatus. Numerous immunoreactive neurons (~100) were detected in various regions of the synganglion (central nervous system) in all examined tick species. Immunoreactive projections of two prominent groups of efferent neurons in the post-oesophageal region were examined in detail: (1) neurons innervating the salivary glands; (2) neurons innervating the hindgut. Using matrix-assisted laser desorption/ionisation-time-of-flight (MALDI-TOF), we detected orcokinin peaks in extracts of the synganglia and hindguts but not in the salivary glands of I. scapularis females. Our data provide further evidence of the presence of orcokinin in ixodid ticks and establish a morphological basis for functional studies of identified peptidergic neuronal networks.

Intestinal lipid-derived signals that sense dietary fat

Fat is a vital macronutrient, and its intake is closely monitored by an array of molecular sensors distributed throughout the alimentary canal. In the mouth, dietary fat constituents such as mono- and diunsaturated fatty acids give rise to taste signals that stimulate food intake, in part by enhancing the production of lipid-derived endocannabinoid messengers in the gut. As fat-containing chyme enters the small intestine, it causes the formation of anorexic lipid mediators, such as oleoylethanolamide, which promote satiety. These anatomically and functionally distinct responses may contribute to the homeostatic control and, possibly, the pathological dysregulation of food intake.

Vascular and neural stem cells in the gut: do they need each other?

Enteric neurons and blood vessels form intricate networks throughout the gastrointestinal tract. To support the hypothesis of a possible interaction of both networks, we investigated whether primary mesenteric vascular cells (MVCs) and enteric nervous system (ENS)-derived cells (ENSc) depend on each other using two- and three-dimensional in vitro assays. In a confrontation assay, both cell types migrated in a target-oriented manner towards each other. The migration of MVCs was significantly increased when cultured in ENSc-conditioned medium. Co-cultures of ENSc with MVCs resulted in an improved ENSc proliferation and differentiation. Moreover, we analysed the formation of the vascular and nervous system in developing mice guts. It was found that the patterning of newly formed microvessels and neural stem cells, as confirmed by nestin and SOX2 stainings, is highly correlated in all parts of the developing gut. In particular in the distal colon, nestin/SOX2-positive cells were found in the tissues adjacent to the capillaries and in the capillaries themselves. Finally, in order to provide evidences for a mutual interaction between endothelial and neural cells, the vascular patterns of a RET((-/-)) knockout mouse model as well as human Hirschsprung's cases were analysed. In the distal colon of postnatal RET((-/-)) knockout mice, the vascular and neural networks were similarly disrupted. In aganglionic zones of Hirschsprung's patients, the microvascular density was significantly increased compared with the ganglionic zone within the submucosa. Taken together, these findings indicate a strong interaction between the enteric nervous and vascular system.

Impact of psychological stress on irritable bowel syndrome

Psychological stress is an important factor for the development of irritable bowel syndrome (IBS). More and more clinical and experimental evidence showed that IBS is a combination of irritable bowel and irritable brain. In the present review we discuss the potential role of psychological stress in the pathogenesis of IBS and provide comprehensive approaches in clinical treatment. Evidence from clinical and experimental studies showed that psychological stresses have marked impact on intestinal sensitivity, motility, secretion and permeability, and the underlying mechanism has a close correlation with mucosal immune activation, alterations in central nervous system, peripheral neurons and gastrointestinal microbiota. Stress-induced alterations in neuro-endocrine-immune pathways acts on the gut-brain axis and microbiota-gut-brain axis, and cause symptom flare-ups or exaggeration in IBS. IBS is a stress-sensitive disorder, therefore, the treatment of IBS should focus on managing stress and stress-induced responses. Now, non-pharmacological approaches and pharmacological strategies that target on stress-related alterations, such as antidepressants, antipsychotics, miscellaneous agents, 5-HT synthesis inhibitors, selective 5-HT reuptake inhibitors, and specific 5-HT receptor antagonists or agonists have shown a critical role in IBS management. A integrative approach for IBS management is a necessary.

Irritable bowel syndrome: A microbiome-gut-brain axis disorder?

Irritable bowel syndrome (IBS) is an extremely prevalent but poorly understood gastrointestinal disorder. Consequently, there are no clear diagnostic markers to help diagnose the disorder and treatment options are limited to management of the symptoms. The concept of a dysregulated gut-brain axis has been adopted as a suitable model for the disorder. The gut microbiome may play an important role in the onset and exacerbation of symptoms in the disorder and has been extensively studied in this context. Although a causal role cannot yet be inferred from the clinical studies which have attempted to characterise the gut microbiota in IBS, they do confirm alterations in both community stability and diversity. Moreover, it has been reliably demonstrated that manipulation of the microbiota can influence the key symptoms, including abdominal pain and bowel habit, and other prominent features of IBS. A variety of strategies have been taken to study these interactions, including probiotics, antibiotics, faecal transplantations and the use of germ-free animals. There are clear mechanisms through which the microbiota can produce these effects, both humoral and neural. Taken together, these findings firmly establish the microbiota as a critical node in the gut-brain axis and one which is amenable to therapeutic interventions.

Epidermal growth factor upregulates serotonin transporter and its association with visceral hypersensitivity in irritable bowel syndrome

AIM: To investigate the role of epidermal growth factor (EGF) in visceral hypersensitivity and its effect on the serotonin transporter (SERT).

METHODS: A rat model for visceral hypersensitivity was established by intra-colonic infusion of 0.5% acetic acid in 10-d-old Sprague-Dawley rats. The visceral sensitivity was assessed by observing the abdominal withdrawal reflex and recording electromyographic activity of the external oblique muscle in response to colorectal distension. An enzyme-linked immunosorbent assay was used to measure the EGF levels in plasma and colonic tissues. SERT mRNA expression was detected by real-time PCR while protein level was determined by Western blot. The correlation between EGF and SERT levels in colon tissues was analyzed by Pearson’s correlation analysis. SERT function was examined by tritiated serotonin (5-HT) uptake experiments. Rat intestinal epithelial cells (IEC-6) were used to examine the EGF regulatory effect on SERT expression and function via the EGF receptor (EGFR).

RESULTS: EGF levels were significantly lower in the rats with visceral hypersensitivity as measured in plasma (2.639 ± 0.107 ng/mL vs 4.066 ± 0.573 ng/mL, P < 0.01) and in colonic tissue (3.244 ± 0.135 ng/100 mg vs 3.582 ± 0.197 ng/100 mg colon tissue, P < 0.01) compared with controls. Moreover, the EGF levels were positively correlated with SERT levels (r = 0.820, P < 0.01). EGF displayed dose- and time-dependent increased SERT gene expressions in IEC-6 cells. An EGFR kinase inhibitor inhibited the effect of EGF on SERT gene upregulation. SERT activity was enhanced following treatment with EGF (592.908 ± 31.515 fmol/min per milligram vs 316.789 ± 85.652 fmol/min per milligram protein, P < 0.05) and blocked by the EGFR kinase inhibitor in IEC-6 cells (590.274 ± 25.954 fmol/min per milligram vs 367.834 ± 120.307 fmol/min per milligram protein, P < 0.05).

CONCLUSION: A decrease in EGF levels may contribute to the formation of visceral hypersensitivity through downregulation of SERT-mediated 5-HT uptake into enterocytes.

Microbiota-host interactions in irritable bowel syndrome: Epithelial barrier, immune regulation and brain-gut interactions

Irritable bowel syndrome (IBS) is a common, sometimes debilitating, gastrointestinal disorder worldwide. While altered gut motility and sensation, as well as aberrant brain perception of visceral events, are thought to contribute to the genesis of symptoms in IBS, a search for an underlying aetiology has, to date, proven unsuccessful. Recently, attention has been focused on the microbiota as a possible factor in the pathogenesis of IBS. Prompted by a number of clinical observations, such as the recognition of the de novo development of IBS following enteric infections, as well as descriptions of changes in colonic bacterial populations in IBS and supported by clinical responses to interventions, such as antibiotics and probiotics, that modify the microbiota, various approaches have been taken to investigating the microbiota-host response in IBS, as well as in animal models thereof. From such studies a considerable body of evidence has accumulated to indicate the activation or upregulation of both factors involved in bacterial engagement with the host as well host defence mechanisms against bacteria. Alterations in gut barrier function, occurring in response, or in parallel, to changes in the microbiota, have also been widely described and can be seen to play a pivotal role in generating and sustaining host immune responses both within and beyond the gut. In this manner a plausible hypothesis, based on an altered microbiota and/or an aberrant host response, for the pathogenesis, of at least some instances of IBS, can be generated.

Convergence of neuro-endocrine-immune pathways in the pathophysiology of irritable bowel syndrome

Disordered signalling between the brain and the gut are generally accepted to underlie the functional bowel disorder, irritable bowel syndrome (IBS). However, partly due to the lack of disease-defining biomarkers, understanding the aetiology of this complex and multifactorial disease remains elusive. This common gastrointestinal disorder is characterised by alterations in bowel habit such as diarrhoea and/or constipation, bloating and abdominal pain, and symptom exacerbation has been linked with periods of stress, both psychosocial and infection-related. Indeed, a high level of comorbidity exists between IBS and stress-related mood disorders such as anxiety and depression. Moreover, studies have observed alterations in autonomic output and neuro-endocrine signalling in IBS patients. Accumulating evidence indicates that a maladaptive stress response, probably mediated by the stress hormone, corticotropin-releasing factor contributes to the initiation, persistence and severity of symptom flares. Other risk factors for developing IBS include a positive family history, childhood trauma, dietary factors and prior gastrointestinal infection. An emerging role has been attributed to the importance of immune factors in the pathophysiology of IBS with evidence of altered cytokine profiles and increased levels of mucosal immune cells. These factors have also been shown to have direct effects on neural signalling. This review discusses how pathological changes in neural, immune and endocrine pathways, and communication between these systems, contribute to symptom flares in IBS.

Role of negative affects in pathophysiology and clinical expression of irritable bowel syndrome

Irritable bowel syndrome (IBS) is regarded as a multifactorial disease in which alterations in the brain-gut axis signaling play a major role. The biopsychosocial model applied to the understanding of IBS pathophysiology assumes that psychosocial factors, interacting with peripheral/central neuroendocrine and immune changes, may induce symptoms of IBS, modulate symptom severity, influence illness experience and quality of life, and affect outcome. The present review focuses on the role of negative affects, including depression, anxiety, and anger, on pathogenesis and clinical expression of IBS. The potential role of the autonomic nervous system, stress-hormone system, and immune system in the pathophysiology of both negative affects and IBS are taken into account. Psychiatric comorbidity and subclinical variations in levels of depression, anxiety, and anger are further discussed in relation to the main pathophysiological and symptomatic correlates of IBS, such as sensorimotor functions, gut microbiota, inflammation/immunity, and symptom reporting.