Enteric nervous system and inflammatory bowel diseases:Correlated impacts and therapeutic approaches through the P2X7 receptor

The enteric nervous system(ENS)consists of thousands of small ganglia arranged in the submucosal and myenteric plexuses,which can be negatively affected by Crohn’s disease and ulcerative colitis-inflammatory bowel diseases(IBDs).IBDs are complex and multifactorial disorders characterized by chronic and recurrent inflammation of the intestine,and the symptoms of IBDs may include abdominal pain,diarrhea,rectal bleeding,and weight loss.The P2X7 receptor has become a promising therapeutic target for IBDs,especially owing to its wide expression and,in the case of other purinergic receptors,in both human and model animal enteric cells.However,little is known about the actual involvement between the activation of the P2X7 receptor and the cascade of subsequent events and how all these activities associated with chemical signals interfere with the functionality of the affected or treated intestine.In this review,an integrated view is provided,correlating the structural organization of the ENS and the effects of IBDs,focusing on cellular constituents and how therapeutic approaches through the P2X7 receptor can assist in both protection from damage and tissue preservation.

The crosstalk between enteric nervous system and immune system in intestinal development,homeostasis and diseases

The gut is the largest digestive and absorptive organ,which is essential for induction of mucosal and systemic immune responses,and maintenance of metabolic-immune homeostasis.The intestinal components contain the epithelium,stromal cells,immune cells,and enteric nervous system(ENS),as well as the outers,such as gut microbiota,metabolites,and nutrients.The dyshomeostasis of intestinal microenvironment induces abnormal intestinal development and functions,even colon diseases including dysplasia,inflammation and tumor.Several recent studies have identified that ENS plays a crucial role in maintaining the immune homeostasis of gastrointestinal(GI)microenvironment.The crosstalk between ENS and immune cells,mainly macrophages,T cells,and innate lymphoid cells(ILCs),has been found to exert important regulatory roles in intestinal tissue programming,homeostasis,function,and inflammation.In this review,we mainly summarize the critical roles of the interactions between ENS and immune cells in intestinal homeostasis during intestinal development and diseases progression,to provide theoretical bases and ideas for the exploration of immunotherapy for gastrointestinal diseases with the ENS as potential novel targets.

Sarm1-mediated neurodegeneration within the enteric nervous system protects against local inflammation of the colon

Axonal degeneration is one of the key features of neu-rodegenerative disorders.In the canonical view,axonal degeneration destructs neural connections and promotes detrimental disease defects.Here,we assessed the enteric nervous system(ENS)of the mouse,nonhuman primate,and human by advanced 3D imaging.We observed the profound neurodegeneration of catecholaminergic axons in human colons with ulcerative colitis,and similarly,in mouse colons during acute dextran sulfate sodium-induced colitis.However,we unexpectedly revealed that blockage of such axonal degeneration by the Sarml deletion in mice exacerbated the colitis condition.In contrast,pharmacologic ablation or chemogenetic inhibition of catecholaminergic axons suppressed the colon inflammation.We further showed that the catecholaminergic neurotransmitter norepinephrine exerted a pro-inflammatory function by enhancing the expression of IL-17 cytokines.Together,this study demonstrated that Sarm1-mediated neurodegeneration within the ENS mitigated local inflammation of the colon,uncovering a previously-unrecognized beneficial role of axonal degeneration in this disease context.

Efficacy of Qihuang decoction(芪黄煎剂) on enteric nervous system in rats after gastrectomy

OBJECTIVE:To investigate the influence of Qihuang decoction(芪黄煎剂)on enteric nervous system after gastrectomy in rats.METHODS:The morphology,distribution and number of intestinal neurons in enteric nervous system(ENS)were observed by immunofluorescence labeling and confocal laser scanning microscopy.Reverse transcriptionpolymerase chain reaction and Western blot were used to detect the mRNA and protein expression of intestinal neurotransmitters and corresponding receptors in ENS.RESULTS:The morphology and distribution of enteric neurons in ENS were changed after gastrectomy,and these neurons in Qihuang decoction group were similar with that of sham operation group.The number of ACh and SP positive neurons,mRNA and protein expression of excitatory neurotransmitters(ACh E,SP)and receptors(M3R,NK1R)were decreased after gastrectomy.And the intervention of Qihuang decoction could increase the number of ACh and SP positive neurons and promote the expression of their mRNA and protein.For vasoactive intestinal peptide(VIP)and nitric oxide synthase(NOS),the number of neurons and mRNA and protein expression of inhibitory neurotransmitters(VIP and NOS)and receptors(VIP2R)were increased after gastrectomy.And these rising indexes fall back after the intervention of Qihuang decoction.Besides,the intestinal propulsion rate in QH group was significantly increased than that in SEN and IEN group.CONCLUSIONS:These experimental results showed that after gastrectomy,early intervention with Qihuang decoction in small intestine will contribute to the postoperative recovery of enteric nervous system and intestinal propulsion rate,and consequently enhance gastrointestinal motility.

Study of the roles of caspase-3 and nuclear factor kappa B in myenteric neurons in a P2X7 receptor knockout mouse model of ulcerative colitis

BACKGROUND The literature indicates that the enteric nervous system is affected in inflammatory bowel diseases(IBDs)and that the P2X7 receptor triggers neuronal death.However,the mechanism by which enteric neurons are lost in IBDs is unknown.AIM To study the role of the caspase-3 and nuclear factor kappa B(NF-κB)pathways in myenteric neurons in a P2X7 receptor knockout(KO)mouse model of IBDs.METHODS Forty male wild-type(WT)C57BL/6 and P2X7 receptor KO mice were euthanized 24 h or 4 d after colitis induction by 2,4,6-trinitrobenzene sulfonic acid(colitis group).Mice in the sham groups were injected with vehicle.The mice were divided into eight groups(n=5):The WT sham 24 h and 4 d groups,the WT colitis 24 h and 4 d groups,the KO sham 24 h and 4 d groups,and the KO colitis 24 h and 4 d groups.The disease activity index(DAI)was analyzed,the distal colon was collected for immunohistochemistry analyses,and immunofluorescence was performed to identify neurons immunoreactive(ir)for calretinin,P2X7 receptor,cleaved caspase-3,total caspase-3,phospho-NF-κB,and total NF-κB.We analyzed the number of calretinin-ir and P2X7 receptor-ir neurons per ganglion,the neuronal profile area(μm^(2)),and corrected total cell fluorescence(CTCF).RESULTS Cells double labeled for calretinin and P2X7 receptor,cleaved caspase-3,total caspase-3,phospho-NF-κB,or total NF-κB were observed in the WT colitis 24 h and 4 d groups.The number of calretinin-ir neurons per ganglion was decreased in the WT colitis 24 h and 4 d groups compared to the WT sham 24 h and 4 d groups,respectively(2.10±0.13 vs 3.33±0.17,P<0.001;2.92±0.12 vs 3.70±0.11,P<0.05),but was not significantly different between the KO groups.The calretinin-ir neuronal profile area was increased in the WT colitis 24 h group compared to the WT sham 24 h group(312.60±7.85 vs 278.41±6.65,P<0.05),and the nuclear profile area was decreased in the WT colitis 4 d group compared to the WT sham 4 d group(104.63±2.49 vs 117.41±1.14,P<0.01).The number of P2X7 receptor-ir neurons per ganglion was decreased in the WT colitis 24 h and 4 d groups compared to the WT sham 24 h and 4 d groups,respectively(19.49±0.35 vs 22.21±0.18,P<0.001;20.35±0.14 vs 22.75±0.51,P<0.001),and no P2X7 receptor-ir neurons were observed in the KO groups.Myenteric neurons showed ultrastructural changes in the WT colitis 24 h and 4 d groups and in the KO colitis 24 h group.The cleaved caspase-3 CTCF was increased in the WT colitis 24 h and 4 d groups compared to the WT sham 24 h and 4 d groups,respectively(485949±14140 vs 371371±16426,P<0.001;480381±11336 vs 378365±4053,P<0.001),but was not significantly different between the KO groups.The total caspase-3 CTCF,phospho-NF-κB CTCF,and total NF-κB CTCF were not significantly different among the groups.The DAI was recovered in the KO groups.Furthermore,we demonstrated that the absence of the P2X7 receptor attenuated inflammatory infiltration,tissue damage,collagen deposition,and the decrease in the number of goblet cells in the distal colon.CONCLUSION Ulcerative colitis affects myenteric neurons in WT mice but has a weaker effect in P2X7 receptor KO mice,and neuronal death may be associated with P2X7 receptor-mediated caspase-3 activation.The P2X7 receptor can be a therapeutic target for IBDs.

Calcium/calcimimetic via calcium-sensing receptor ameliorates cholera toxin-induced secretory diarrhea in mice

BACKGROUND Enterotoxins produce diarrhea through direct epithelial action and indirectly by activating the enteric nervous system.Calcium-sensing receptor(CaSR)inhibits both actions.The latter has been well documented in vitro but not in vivo.The hypothesis to be tested was that activating CaSR inhibits diarrhea in vivo.AIM To determine whether CaSR agonists ameliorate secretory diarrhea evoked by cholera toxin(CTX)in mice.METHODS CTX was given orally to C57BL/6 mice to induce diarrhea.Calcium and calci-mimetic R568 were used to activate CaSR.To maximize their local intestinal actions,calcium was administered luminally via oral rehydration solution(ORS),whereas R568 was applied serosally using an intraperitoneal route.To verify that their actions resulted from the intestine,effects were also examined on Cre-lox intestine-specific CaSR knockouts.Diarrhea outcome was measured biochemically by monitoring changes in fecal Cl-or clinically by assessing stool consistency and weight loss.RESULTS CTX induced secretory diarrhea,as evidenced by increases in fecal Cl-,stool consistency,and weight loss following CTX exposure,but did not alter CaSR,neither in content nor in function.Accordingly,calcium and R568 were each able to ameliorate diarrhea when applied to diseased intestines.Intestinal CaSR involvement is suggested by gene knockout experiments where the anti-diarrheal actions of R568 were lost in intestinal epithelial CaSR knockouts(villinCre/Casrflox/flox)and neuronal CaSR knockouts(nestinCre/Casrflox/flox).CONCLUSION Treatment of acute secretory diarrheas remains a global challenge.Despite advances in diarrhea research,few have been made in the realm of diarrhea therapeutics.ORS therapy has remained the standard of care,although it does not halt the losses of intestinal fluid and ions caused by pathogens.There is no cost-effective therapeutic for diarrhea.This and other studies suggest that adding calcium to ORS or using calcimimetics to activate intestinal CaSR might represent a novel approach for treating secretory diarrheal diseases.

The Gut Brain Connection

The gut-brain connection is a bidirectional communication system that links the gut microbiome to the central nervous system (CNS). The gut-brain axis communicates through a variety of mechanisms, including the release of hormones, neurotransmitters, and cytokines. These signaling molecules can travel from the gut to the brain and vice versa, influencing various physiological and cognitive functions. Emerging therapeutic strategies targeting the gut-brain connection include probiotics, prebiotics, and faecal microbiota transplantation (FMT). Probiotics are live microorganisms that are similar to the beneficial bacteria that are naturally found in the gut. Prebiotics are non-digestible fibers that feed the beneficial bacteria in the gut. FMT is a procedure in which faecal matter from a healthy donor is transplanted into the gut of a person with a diseased microbiome. Probiotics, prebiotics, and FMT have been shown to be effective in treating a variety of gastrointestinal disorders, and there is growing evidence that they may also be effective in treating neurological and psychiatric disorders. This review explores the emerging field of the gut-brain connection, focusing on the communication pathways between the gut microbiome and the central nervous system. We summarize the potential roles of gut dysbiosis in various neurological and psychiatric disorders. Additionally, we discuss potential therapeutic strategies, research limitations, and future directions in this exciting area of research. More research is needed to fully understand the mechanisms underlying the gut-brain connection and to develop safe and effective therapies that target this pathway. However, the findings to date are promising, and there is the potential to revolutionize the way we diagnose and treat a variety of neurological and psychiatric disorders.

Phenotypic and functional comparison of rat enteric neural crest-derived cells during fetal and earlypostnatal stages

In our previous study,we showed that with increasing time in culture,the growth characteristics of enteric neural crest-derived cells(ENCCs)change,and that the proliferation,migration and neural differentiation potential of these cells in vitro notably diminish.However,there are no studies on the developmental differences in these characteristics between fetal and early-postnatal stages in vitro or in vivo.In this study,we isolated fetal(embryonic day 14.5)and postnatal(postnatal day 2)ENCCs from the intestines of rats.Fetal ENCCs had greater maximum cross-sectional area of the neurospheres,stronger migration ability,and reduced apoptosis,compared with postnatal ENCCs.However,fetal and postnatal ENCCs had a similar differentiation ability.Fetal and postnatal ENCCs both survived after transplant into a rat model of Hirschsprung’s disease.In these rats with Hirschsprung’s disease,the number of ganglionic cells in the myenteric plexus was higher and the distal intestinal pressure change was greater in animals treated with fetal ENCCs compared with those treated with postnatal ENCCs.These findings suggest that,compared with postnatal ENCCs,fetal ENCCs exhibit higher survival and proliferation and migration abilities,and are therefore a more appropriate seed cell for the treatment of Hirschsprung’s disease.This study was approved by the Animal Ethics Committee of the Second Affiliated Hospital of Xi’an Jiaotong University(approval No.2016086)on March 3,2016.

Effects of perinatal protein deprivation and recovery on esophageal myenteric plexus

AIM:To evaluate effects of preand postnatal protein deprivation and postnatal recovery on the myenteric plexus of the rat esophagus. METHODS: Three groups of young Wistar rats (aged 42 d) were studied: normalfed (N42), proteindeprived (D42), and proteinrecovered (R42). The myenteric neurons of their esophagi were evaluated by histochemical reactions for nicotinamide adenine dinucleotide (NADH), nitrergic neurons (NADPH)diaphorase and acetylcholinesterase (AChE), immunohistochemical reaction for vasoactive intestinal polypeptide (VIP), and ultrastructural analysis by transmission electron microscopy.RESULTS: The cytoplasms of large and medium neurons from the N42 and R42 groups were intensely reactive for NADH. Only a few large neurons from the D42 group exhibited this aspect. NADPH detected in the D42 group exhibited low reactivity. The AChE reactivity was diffuse in neurons from the D42 and R42 groups. The density of large and small varicosities detected by immunohistochemical staining of VIP was low in ganglia from the D42 group. In many neurons from the D42 group, the double membrane of the nuclear envelope and the perinuclear cisterna were not detectable. NADH and NADPH histochemistry revealed no group differences in the prof ile of nerve cell perikarya (ranging from 200 to 400 μm2).CONCLUSION: Protein deprivation causes a delay in neuronal maturation but postnatal recovery can almost completely restore the normal morphology of myenteric neurons.

Structure of the myenteric plexus in normal and diseased human ileum analyzed by X-ray virtual histology slices

BACKGROUND The enteric nervous system(ENS)is situated along the entire gastrointestinal tract and is divided into myenteric and submucosal plexuses in the small and large intestines.The ENS consists of neurons,glial cells,and nerves assembled into ganglia,surrounded by telocytes,interstitial cells of Cajal,and connective tissue.Owing to the complex spatial organization of several interconnections with nerve fascicles,the ENS is difficult to examine in conventional histological sections of 3-5μm.AIM To examine human ileum full-thickness biopsies using X-ray phase-contrast nanotomography without prior staining to visualize the ENS.METHODS Six patients were diagnosed with gastrointestinal dysmotility and neuropathy based on routine clinical and histopathological examinations.As controls,fullthickness biopsies were collected from healthy resection ileal regions after hemicolectomy for right colon malignancy.From the paraffin blocks,4-μm thick sections were prepared and stained with hematoxylin and eosin for localization of the myenteric ganglia under a light microscope.A 1-mm punch biopsy(up to 1 cm in length)centered on the myenteric plexus was taken and placed into a Kapton®tube for mounting in the subsequent investigation.X-ray phase-contrast tomography was performed using two custom-designed laboratory setups with micrometer resolution for overview scanning.Subsequently,selected regions of interest were scanned at a synchrotron-based end-station,and high-resolution slices were reported.In total,more than 6000 virtual slices were analyzed from nine samples.RESULTS In the overview scans,the general architecture and quality of the samples were studied,and the myenteric plexus was localized.High-resolution scans revealed details,including the ganglia,interganglional nerve fascicles,and surrounding tissue.The ganglia were irregular in shape and contained neurons and glial cells.Spindle-shaped cells with very thin cellular projections could be observed on the surface of the ganglia,which appeared to build a network.In the patients,there were no alterations in the general architecture of the myenteric ganglia.Nevertheless,several pathological changes were observed,including vacuolar degeneration,autophagic activity,the appearance of sequestosomes,chromatolysis,and apoptosis.Furthermore,possible expulsion of pyknotic neurons and defects in the covering cellular network could be observed in serial slices.These changes partly corresponded to previous light microscopy findings.CONCLUSION The analysis of serial virtual slices could provide new information that cannot be obtained by classical light microscopy.The advantages,disadvantages,and future possibilities of this method are also discussed.

P2X7 receptor blockade decreases inflammation,apoptosis,and enteric neuron loss during Clostridioides difficile toxin A-induced ileitis in mice

Clostridioides difficile(C.difficile)is the most common pathogen causing health care-associated infections.C.difficile TcdA and TcdB have been shown to activate enteric neurons;however,what population of these cells is more profoundly influenced and the mechanism underlying these effects remain unknown.AIM To characterize a specific population of TcdA-affected myenteric neurons and investigate the role of the P2X7 receptor in TcdA-induced ileal inflammation,cell death,and the changes in the enteric nervous system in mice.METHODS Swiss mice were used to model TcdA-induced ileitis in ileal loops exposed to TcdA(50μg/Loop)for 4 h.To investigate the role of the P2X7 receptor,Brilliant Blue G(50 mg/kg,i.p.),which is a nonspecific P2X7 receptor antagonist,or A438079(0.7μg/mouse,i.p.),which is a competitive P2X7 receptor antagonist,were injected one hour prior to TcdA challenge.Ileal samples were collected to analyze the expression of the P2X7 receptor(by quantitative real-time polymerase chain reaction and immunohistochemistry),the population of myenteric enteric neurons(immunofluorescence),histological damage,intestinal inflammation,cell death(terminal deoxynucleotidyltransferasemediated dUTP-biotin nick end labeling),neuronal loss,and S100B synthesis(immunohistochemistry).RESULTS TcdA upregulated(P<0.05)the expression of the P2X7 receptor gene in the ileal tissues,increasing the level of this receptor in myenteric neurons compared to that in control mice.Comparison with the control mice indicated that TcdA promoted(P<0.05)the loss of myenteric calretinin+(Calr)and choline acetyltransferase+neurons and increased the number of nitrergic+and Calr+neurons expressing the P2X7 receptor.Blockade of the P2X7 receptor decreased TcdAinduced intestinal damage,cytokine release[interleukin(IL)-1β,IL-6,IL-8,and tumor necrosis factor-α],cell death,enteric neuron loss,and S100B synthesis in the mouse ileum.CONCLUSION Our findings demonstrated that TcdA induced the upregulation of the P2X7 receptor,which promoted enteric neuron loss,S100B synthesis,tissue damage,inflammation,and cell death in the mouse ileum.These findings contribute to the future directions in understanding the mechanism involved in intestinal dysfunction reported in patients after C.difficile infection.

Study of tumor necrosis factor receptor in the inflammatory bowel disease

Ulcerative colitis(UC)and Crohn’s disease(CD)are part of Inflammatory Bowel Diseases(IBD)and have pathophysiological processes such as bowel necrosis and enteric neurons and enteric glial cells.In addition,the main inflammatory mediator is related to the tumor necrosis factor-alpha(TNF-α).TNF-αis a mediator of the intestinal inflammatory processes,thus being one of the main cytokines involved in the pathogenesis of IBD,however,its levels,when measured,are present in the serum of patients with IBD.In addition,TNF-αplays an important role in promoting inflammation,such as the production of interleukins(IL),for instance IL-1βand IL-6.There are two receptors for TNF as following:The tumor necrosis factor 1 receptor(TNFR1);and the tumor necrosis factor 2 receptor(TNFR2).They are involved in the pathogenesis of IBD and their receptors have been detected in IBD and their expression is correlated with disease activity.The soluble TNF form binds to the TNFR1 receptor with,and its activation results in a signaling cascade effects such as apoptosis,cell proliferation and cytokine secretion.In contrast,the transmembrane TNF form can bind both to TNFR1 and TNFR2.Recent studies have suggested that TNF-αis one of the main pro-inflammatory cytokines involved in the pathogenesis of IBD,since TNF levels are present in the serum of both patients with UC and CD.Intravenous and subcutaneous biologics targeting TNF-αhave revolutionized the treatment of IBD,thus becoming the best available agents to induce and maintain IBD remission.The application of antibodies aimed at neutralizing TNF-αin patients with IBD that induce a satisfactory clinical response in up to 60%of patients,and also induced long-term maintenance of disease remission in most patients.It has been suggested that anti-TNF-αagents inactivate the pro-inflammatory cytokine TNF-αby direct neutralization,i.e.,resulting in suppression of inflammation.However,anti-TNF-αantibodies perform more complex functions than a simple blockade.

Analyzing the Prebiotic Potential of Glucosamine for Targeting the Gut Microbiome Health

Recognizing the composition and modulation of the microbiome, a viable therapeutic tool for multi-targeted therapy is a new strategy that has recently been explored. Glucosamine (GS) is being studied for its prebiotic potential in addition to being the most abundant and naturally occurring amino monosaccharide. The current study focuses on glucosamine’s prebiotic potential by assessing the stability of various GS concentrations (1% - 5%) in the gastrointestinal tract (GIT) and its ability to be fermented by the gut microbiota. The results showed that GS stimulated the most growth in L. acidophilus even after a longer incubation time than B. bifidum and L. acidophilus growth was concentration-dependent, with maximum growth at 3% with a simultaneous decrease in pH (5.6 - 1.7). The decrease in GS concentration with time also represented the growth of bacterial species, demonstrating the species’ utilization of GS. Furthermore, at 3%, GS also represented the prebiotic index of 1.9. In addition, the concentration of GS in various simulated GIT fluids was estimated in both fast and fed conditions to examine GS stability at various levels in the gut. The results showed that GS remained unaffected and non-digestible in all of the simulated GIT fluids (salivary, gastric, intestinal, and colonic), but there was a slight decrease in GS concentration (2.8%) in the fasted state of gastric fluid due to low pH levels (1.6). As a result, the findings are conclusive and suggest that GS possesses prebiotic properties.

Enteric neuropathy in diabetes:Implications for gastrointestinal function

Diabetes,commonly known for its metabolic effects,also critically affects the enteric nervous system(ENS),which is essential in regulating gastrointestinal(GI)motility,secretion,and absorption.The development of diabetes-induced enteric neuropathy can lead to various GI dysfunctions,such as gastroparesis and irregular bowel habits,primarily due to disruptions in the function of neuronal and glial cells within the ENS,as well as oxidative stress and inflammation.This editorial explores the pathophysiological mechanisms underlying the development of enteric neuropathy in diabetic patients.Additionally,it discusses the latest advances in diagnostic approaches,emphasizing the need for early detection and intervention to mitigate GI complications in diabetic individuals.The editorial also reviews current and emerging therapeutic strategies,focusing on pharmacological treatments,dietary management,and potential neuromodulatory interventions.Ultimately,this editorial highlights the necessity of a multidisciplinary approach in managing enteric neuropathy in diabetes,aiming to enhance patient quality of life and address a frequently overlooked complication of this widespread disease.

Constipation,deficit in colon contractions and alpha-synuclein inclusions within the colon precede motor abnormalities and neurodegeneration in the central nervous system in a mouse model of alphasynucleinopathy

Background:Gastrointestinal dysfunction can affect Parkinson’s disease(PD)patients long before the onset of motor symptoms.However,little is known about the relationship between gastrointestinal abnormalities and the development of PD.Contrary to other animal models,the human A53T alpha-synuclein(αS)transgenic mice,Line G2–3,developsαS-driven neurological and motor impairments after 9 months of age,displaying a long presymptomatic phase free of central nervous system(CNS)dysfunction.Methods:To determine whether this line can be suitable to study constipation as it occurs in prodromal PD,gastrointestinal functionality was assessed in young mice through a multidisciplinary approach,based on behavioral and biochemical analysis combined with electrophysiological recordings of mouse intestinal preparations.Results:We found that the A53TαS mice display remarkable signs of gastrointestinal dysfunction that precede motor abnormalities andαS pathology in the CNS by at least 6 months.YoungαS mice show a drastic delay in food transit along the gastrointestinal tract,of almost 2 h in 3 months old mice that increased to more than 3 h at 6 months.Such impairment was associated with abnormal formation of stools that resulted in less abundant but longer pellets excreted,suggesting a deficit in the intestinal peristalsis.In agreement with this,electrically evoked contractions of the colon,but not of the ileum,showed a reduced motor response in both longitudinal and circular muscle layers inαS mice already at 3 months of age,that was mainly due to an impaired cholinergic transmission of the underlying enteric nervous system.Interestingly,the presence of insoluble and aggregatedαS was found in enteric neurons in both myenteric and submucosal plexi only in the colon of 3 months oldαS mice,but not in the small intestine,and exacerbated with age,mimicking the increase in transit delay and the contraction deficit showed by behavioral and electrical recordings data.Conclusions:Gastrointestinal dysfunction in A53TαS mice represents an early sign ofαS-driven pathology without concomitant CNS involvement.We believe that this model can be very useful to study disease-modifying strategies that could extend the prodromal phase of PD and haltαS pathology from reaching the brain.

The role of glutamine in supporting gut health and neuropsychiatric factors

Recent research has shown that the amino acid glutamine can positively affect gut health by supporting the gut microbiome,gut mucosal wall integrity,and by modulating infiammatory responses.As modulated by the vagus nerve,via the enteric nervous system,the gut-brain connection can impact the brain’s neurochemical environment.Poor gut health can disrupt the balance of neurotransmitters,which can result in neuropsychiatric based conditions such as depression.Glutamine supplementation may provide significant adjunctive nutritional support in cases of depression by promoting proper gut health and function.

Gastrointestinal problems, mechanisms and possible therapeutic directions in Gulf war illness: a mini review

By its nature, Gulf war illness(GWI) is multi-symptomatic and affects several organ systems in the body. Along with other symptoms, veterans who suffer from GWI commonly report chronic gastrointestinal issues such as constipation,pain, indigestion, etc. However, until recently, most attention has been focused on neurological disturbances such as cognitive impairments, chronic fatigue, and chronic pain among affected veterans. With such high prevalence of gastrointestinal problems among Gulf war(GW) veterans, it is surprising that there is little research to investigate the mechanisms behind these issues. This review summarizes all the available works on the mechanisms behind gastrointestinal problems in GWI that have been published to date in various databases. Generally, these studies,which were done in rodent models, in vitro and human cohorts propose that an altered microbiome, a reactive enteric nervous system or a leaky gut among other possible mechanisms are the major drivers of gastrointestinal problems reported in GWI. This review aims to draw attention to the gastrointestinal tract as an important player in GWI disease pathology and a potential therapeutic target.

Neuroimmunomodulation by gut bacteria:Focus on inflammatory bowel diseases

Microbes colonize the gastrointestinal tract are considered as highest complex ecosystem because of having diverse bacterial species and 150 times more genes as compared to the human genome.Imbalance or dysbiosis in gut bacteria can cause dysregulation in gut homeostasis that subsequently activates the immune system,which leads to the development of inflammatory bowel disease(IBD).Neuromediators,including both neurotransmitters and neuropeptides,may contribute to the development of aberrant immune response.They are emerging as a regulator of inflammatory processes and play a key role in various autoimmune and inflammatory diseases.Neuromediators may influence immune cell’s function via the receptors present on these cells.The cytokines secreted by the immune cells,in turn,regulate the neuronal functions by binding with their receptors present on sensory neurons.This bidirectional communication of the enteric nervous system and the enteric immune system is involved in regulating the magnitude of inflammatory pathways.Alterations in gut bacteria influence the level of neuromediators in the colon,which may affect the gastrointestinal inflammation in a disease condition.Changed neuromediators concentration via dysbiosis in gut microbiota is one of the novel approaches to understand the pathogenesis of IBD.In this article,we reviewed the existing knowledge on the role of neuromediators governing the pathogenesis of IBD,focusing on the reciprocal relationship among the gut microbiota,neuromediators,and host immunity.Understanding the neuromediators and host-microbiota interactions would give a better insight in to the disease pathophysiology and help in developing the new therapeutic approaches for the disease.

Quantitative changes of nitrergic neurons during postnatal development of chicken myenteric plexus

Objective: Information regarding the development of the enteric nervous system(ENS) is important for understanding the functional abnormalities of the gut.Because fertilized chicken eggs provide easy access to embryos,chicken models have been widely used to study embryonic development of myenteric plexus;however,no study has been focused on the postnatal period.The aim of this study was to perform a qualitative and quantitative analysis of the nitrergic neurons in the myenteric plexus of developing chickens in the postnatal period.Methods: Whole-mount preparations of the myenteric plexus were made in 7-d,15-d,and 40-d old(adult) chickens of either sex(n=15).The myenteric plexus was studied after nicotinamide adenine dinucleotide phosphate diaphorase(NADPH-d) histochemistry using light microscopy,digital photography,and Image-Pro Plus 6.0 software.The numbers of positively stained neurons and ganglia were counted in the duodenum,jejunum,ileum,caecum,and colon in the different age groups.Data were expressed as mean±standard deviation(SD),and statistical analysis was performed using a one-way analysis of variance(ANOVA) test.Results: The positively stained neurons showed various morphologies and staining intensities,and formed bead-shaped and U-shaped arrangements in the myenteric plexus.The densities of neurons and ganglia increased with age.However,the number of positive neurons per ganglion increased.The number of NADPH-d-positive neurons was highest in the colon,followed by the ileum,the jejunum,the duodenum,and the caeca in all age groups.Conclusions: Developmental changes in the myenteric plexus of chickens continue in the postnatal period,indicating that the maturation process of the gastrointestinal function is gradual.In addition,no significant difference is happening among different intestinal segments during postnatal development,suggesting that the function of different intestinal segments had been determined after birth.

Age-dependent alpha-synuclein accumulation and aggregation in the colon of a transgenic mouse model of Parkinson’s disease

Background:Parkinson’s disease(PD)is one of the most common neurodegenerative diseases,neuropathologically characterized by misfolded protein aggregation,called Lewy bodies and Lewy neurites.PD is a slow-progressive disease with colonic dysfunction appearing in the prodromal stage and lasting throughout the course of the disease.Methods:In order to study PD pathology in the colon,we examined the age-dependent morphological and pathological changes in the colon of a PD mouse model expressing human wildtype α-synuclein(α-syn)fused with the green fluorescent protein(GFP),under the endogenous mouse α-syn promoter.Results:We observed an age-dependent progressive expression and accumulation of α-syn-GFP in the enteric neurons of Meissner’s(submucosal)and Auerbach’s(myenteric)plexuses of the colon.Additionally,the phosphorylation of α-syn at serine 129 also increased with age and the aggregation ofα-syn-GFP coincided with the appearance of motor deficits at 9 months of age.Furthermore,α-syn(-GFP)distinctly co-localized with different subtypes of neurons,as identified by immunohistochemical labeling of vasoactive intestinal peptide(VIP),neuronal nitric oxide synthase(nNOS),and calretinin.Conclusions:Our results show the development of α-syn pathology in the enteric neurons of the colon in a PD mouse model,which coincide with the appearance of motor deficits.Our mouse model possesses the potential and uniqueness for studying PD gastrointestinal dysfunction.