Role of vasoactive intestinal peptide and inflammatory mediators in enteric neuronal plasticity

Mechanisms underlying dose-limiting toxicities of conventional chemotherapeutic agents

Dose-limiting toxicities (DLTs) are severe adverse effects that define the maximum tolerated dose of a cancer drug. In addition to the specific mechanisms of each drug, common contributing factors include inflammation, apoptosis, ion imbalances, and tissue-specific enzyme deficiencies. Among various DLTs are bleomycin-induced pulmonary fibrosis, doxorubicin-induced cardiomyopathy, cisplatin-induced nephrotoxicity, methotrexate-induced hepatotoxicity, vincristine-induced neurotoxicity, paclitaxel-induced peripheral neuropathy, and irinotecan, which elicits severe diarrhea. Currently, specific treatments beyond dose reduction are lacking for most toxicities. Further research on cellular and molecular pathways is imperative to improve their management. This review synthesizes preclinical and clinical data on the pharmacological mechanisms underlying DLTs and explores possible treatment approaches. A comprehensive perspective reveals knowledge gaps and emphasizes the need for future studies to develop more targeted strategies for mitigating these dose-dependent adverse effects. This could allow the safer administration of fully efficacious doses to maximize patient survival.

Acrylamide-Induced Changes in the Pituitary Adenylate Cyclase-Activating Polypeptide (PACAP) Immunoreactivity in Small Intestinal Intramural Neurons in Pigs

BACKGROUND

A particularly pressing problem is determining consumer-safe doses of potentially health- and life-threatening substances, such as acrylamide. The aim of the study was to determine how acrylamide affects the pituitary adenylate cyclase-activating polypeptide (PACAP)-immunoreactive intramural neurons in the small intestine of sexually immature gilts.

METHODS

The study was conducted on 15 sexually immature Danish gilts receiving for 28 days empty gelatin capsules or acrylamide in low (0.5 µg/kg of body weight (b.w.)/day) and high (5 µg/kg b.w./day) doses. After euthanasia, intestinal sections were stained using the double immunofluorescence staining procedure.

RESULTS

Studies have shown that oral administration of acrylamide in both doses induced a response of intramural neurons expressed as an increase in the population of PACAP-immunoreactive neurons in the small intestine. In the duodenum, only in the myenteric plexus (MP) was an increase in the number of PACAP-immunoreactive (IR) neurons observed in both experimental groups, while in the outer submucous plexus (OSP) and inner submucous plexus (ISP), an increase was noted only in the high-dose group. In the jejunum, both doses of acrylamide led to an increase in the population of PACAP-IR neurons in each enteric plexus (MP, OSP, ISP), while in the ileum, only supplementation with the higher dose of acrylamide increased the number of PACAP-IR enteric neurons in the MP, OSP, and ISP.

CONCLUSIONS

The obtained results suggest the participation of PACAP in acrylamide-induced plasticity of enteric neurons, which may be an important line of defence from the harmful action of acrylamide on the small intestines.

Altered Bioavailability and Pharmacokinetics in Crohn's Disease: Capturing Systems Parameters for PBPK to Assist with Predicting the Fate of Orally Administered Drugs

Backgrond and Objective

Crohn’s disease (CD) is a chronic inflammatory bowel disease that affects a wide age range. Hence, CD patients receive a variety of drugs over their life beyond those used for CD itself. The changes to the integrity of the intestine and its drug metabolising enzymes and transporters (DMETs) can alter the oral bioavailability of drugs. However, there are other changes in systems parameters determining the fate of drugs in CD, and understanding these is essential for dose adjustment in patients with CD.

Methods

The current analysis gathered all the available clinical data on the kinetics of drugs in CD (by March 2021), focusing on orally administered small molecule drugs. A meta-analysis of the systems parameters affecting oral drug pharmacokinetics was conducted. The systems information gathered on intestine, liver and blood proteins and other physiological parameters was incorporated into a physiologically based pharmacokinetic (PBPK) platform to create a virtual population of CD patients, with a view for guiding dose adjustment in the absence of clinical data in CD.

Results

There were no uniform trends in the reported changes in reported oral bioavailability. The nature of the drug as well as the formulation affected the direction and magnitude of variation in kinetics in CD patients relative to healthy volunteers. Even for the same drug, the reported changes in exposure varied, possibly due to a lack of distinction between the activity states of CD. The highest alteration was seen with S-verapamil and midazolam, 8.7- and 5.3-fold greater exposure, respectively, in active CD patients relative to healthy volunteers. Only one report was available on liver DMETs in CD, and indicated reduced CYP3A4 activity. In a number of reports, mRNA expression of DMETs in the ileum and colon of CD patients was measured, focussing on P-glycoprotein (p-gp) transporter and CYP3A4 enzyme, and showed contradictory results. No data were available on protein expression in duodenum and jejunum despite their dominant role in oral drug absorption.

Conclusion

There are currently inadequate dedicated clinical or quantitative proteomic studies in CD to enable predictive PBPK models with high confidence and adequate verification. The PBPK models for CD with the available systems parameters were able to capture the major physiological influencers and the gaps to be filled by future research. Quantification of DMETs in the intestine and the liver in CD is warranted, alongside well-defined clinical drug disposition studies with a number of index drugs as biomarkers of changes in DMETs in these patients, to avoid large-scale dedicated studies for every drug to determine the effects of disease on the drug’s metabolism and disposition and the consequential safety and therapeutic concerns.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40262-022-01169-4.

Roles of gastrointestinal polypeptides in intestinal barrier regulation

The intestinal barrier is a dynamic entity that is organized as a multilayer system and includes various intracellular and extracellular elements. The gut barrier functions in a coordinated manner to impede the passage of antigens, toxins, and microbiome components and simultaneously preserves the balanced development of the epithelial barrier and the immune system and the acquisition of tolerance to dietary antigens and intestinal pathogens.Numerous scientific studies have shown a significant association between gut barrier damage and gastrointestinal and extraintestinal diseases such as inflammatory bowel disease, celiac disease and hepatic fibrosis. Various internal and external factors regulate the intestinal barrier. Gastrointestinal peptides originate from enteroendocrine cells in the luminal digestive tract and are critical gut barrier regulators. Recent studies have demonstrated that gastrointestinal peptides have a therapeutic effect on digestive tract diseases, enhancing epithelial barrier activity and restoring the gut barrier. This review demonstrates the roles and mechanisms of gastrointestinal polypeptides, especially somatostatin (SST) and vasoactive intestinal peptide (VIP), in intestinal barrier regulation.

Ebselen prevents cigarette smoke-induced gastrointestinal dysfunction in mice

Gastrointestinal (GI) dysfunction is a common comorbidity of chronic obstructive pulmonary disease (COPD) for which a major cause is cigarette smoking (CS). The underlying mechanisms and precise effects of CS on gut contractility, however, are not fully characterised. Therefore, the aim of the present study was to investigate whether CS impacts GI function and structure in a mouse model of CS-induced COPD. We also aimed to investigate GI function in the presence of ebselen, an antioxidant that has shown beneficial effects on lung inflammation resulting from CS exposure. Mice were exposed to CS for 2 or 6 months. GI structure was analysed by histology and immunofluorescence. After 2 months of CS exposure, ex vivo gut motility was analysed using video-imaging techniques to examine changes in colonic migrating motor complexes (CMMCs). CS decreased colon length in mice. Mice exposed to CS for 2 months had a higher frequency of CMMCs and a reduced resting colonic diameter but no change in enteric neuron numbers. Ten days cessation after 2 months CS reversed CMMC frequency changes but not the reduced colonic diameter phenotype. Ebselen treatment reversed the CS-induced reduction in colonic diameter. After 6 months CS, the number of myenteric nitric-oxide producing neurons was significantly reduced. This is the first evidence of colonic dysmotility in a mouse model of CS-induced COPD. Dysmotility after 2 months CS is not due to altered neuron numbers; however, prolonged CS-exposure significantly reduced enteric neuron numbers in mice. Further research is needed to assess potential therapeutic applications of ebselen in GI dysfunction in COPD.

Effect of Acrylamide Supplementation on the Population of Vasoactive Intestinal Peptide (VIP)-Like Immunoreactive Neurons in the Porcine Small Intestine

Acrylamide is one of the harmful substances present in food. The present study aimed to establish the effect of acrylamide supplementation in tolerable daily intake (TDI) dose (0.5 µg/kg b.w./day) and a dose ten times higher than TDI (5 µg/kg b.w./day) on the population of vasoactive intestinal peptide-like immunoreactive (VIP-LI) neurons in the porcine small intestine and the degree of the co-localization of VIP with other neuroactive substances (neuronal nitric oxide synthase (nNOS), substance P (SP), and cocaine- and amphetamine-regulated transcript peptide (CART)). In our work, 15 Danish landrace gilts (5 in each experimental group) received capsules (empty or with low or high doses of acrylamide) for a period of 28 days with their morning feeding. Using double immunofluorescence staining, we established that acrylamide supplementation increased the number of neurons showing immunoreactivity towards VIP in all types of enteric nervous system (ENS) plexuses and fragments of the small intestine studied. Moreover, both doses of acrylamide led to changes in the degree of co-localization of VIP with nNOS, SP, and CART in intramural neurons. The observed changes may be the adaptation of neurons to local inflammation, oxidative stress, or the direct toxic effects of acrylamide on intestinal neurons, also referred to as neuronal plasticity.

Investigating associations between intestinal alterations and parasite load according to Bifidobacterium spp. and Lactobacillus spp. abundance in the gut microbiota of hamsters infected by Leishmania infantum

BACKGROUND

Visceral leishmaniasis (VL) is a tropical neglected disease with high associated rates of mortality. Several studies have highlighted the importance of the intestinal tract (IT) and gut microbiota (GM) in the host immunological defense. Data in the literature on parasite life cycle and host immune defense against VL are scarce regarding the effects of infection on the IT and GM.

OBJECTIVES

This study aimed to investigate changes observed in the colon of Leishmania infantum-infected hamsters, including alterations in the enteric nervous system (ENS) and GM (specifically, levels of bifidobacteria and lactobacilli).

METHODS

Male hamsters were inoculated with L. infantum and euthanised at four or eight months post-infection. Intestines were processed for histological analysis and GM analysis. Quantitative polymerase chain reaction (qPCR) was performed to quantify each group of bacteria: Bifidobacterium spp. (Bf) and Lactobacillus spp (LacB).

FINDINGS

Infected hamsters showed histoarchitectural loss in the colon wall, with increased thickness in the submucosa and the mucosa layer, as well as greater numbers of intraepithelial lymphocytes. Forms suggestive of amastigotes were seen inside mononuclear cells. L. infantum infection induced changes in ENS, as evidenced by increases in the area of colonic enteric ganglia. Despite the absence of changes in the levels of Bf and LacB during the course of infection, the relative abundance of these bacteria was associated with parasite load and histological alterations.

MAIN CONCLUSIONS

Our results indicate that L. infantum infection leads to important changes in the colon and suggest that bacteria in the GM play a protective role.

GLP-2 Prevents Neuronal and Glial Changes in the Distal Colon of Mice Chronically Treated with Cisplatin

Cisplatin is a chemotherapeutic agent widely used for the treatment of solid cancers. Its administration is commonly associated with acute and chronic gastrointestinal dysfunctions, likely related to mucosal and enteric nervous system (ENS) injuries, respectively. Glucagon-like peptide-2 (GLP-2) is a pleiotropic hormone exerting trophic/reparative activities on the intestine, via antiapoptotic and pro-proliferating pathways, to guarantee mucosal integrity, energy absorption and motility. Further, it possesses anti-inflammatory properties. Presently, cisplatin acute and chronic damages and GLP-2 protective effects were investigated in the mouse distal colon using histological, immunohistochemical and biochemical techniques. The mice received cisplatin and the degradation-resistant GLP-2 analog ([Gly2]GLP-2) for 4 weeks. Cisplatin-treated mice showed mucosal damage, inflammation, IL-1β and IL-10 increase; decreased number of total neurons, ChAT- and nNOS-immunoreactive (IR) neurons; loss of SOX-10-IR cells and reduced expression of GFAP- and S100β-glial markers in the myenteric plexus. [Gly2]GLP-2 co-treatment partially prevented mucosal damage and counteracted the increase in cytokines and the loss of nNOS-IR and SOX-10-IR cells but not that of ChAT-IR neurons. Our data demonstrate that cisplatin causes mucosal injuries, neuropathy and gliopathy and that [Gly2]GLP-2 prevents these injuries, partially reducing mucosal inflammation and inducing ENS remodeling. Hence, this analog could represent an effective strategy to overcome colonic injures induced by cisplatin.

Vasoactive Intestinal Polypeptide (VIP) in the Intestinal Mucosal Nerve Fibers in Dogs with Inflammatory Bowel Disease

Simple Summary

Canine inflammatory bowel disease (IBD)—a group of gastrointestinal disorders—is a serious problem in veterinary medicine. The etiology of IBD remains unknown, and its diagnosis and effective treatment are difficult. One of the less-known aspects of IBD pathology is the influence of this disease on the enteric nervous system, which is located in the intestinal wall and regulates most of the gastrointestinal functions. Therefore, the aim of the present study was to evaluate the influence of IBD on the intramucosal nerve fibers containing vasoactive intestinal polypeptide (VIP). VIP is one of the most important substances produced by the enteric nervous structures that is involved in many regulatory processes in the gastrointestinal tract. The obtained results show that IBD induces changes in the density of intramucosal VIP-positive nerve fibers in the canine gastrointestinal tract. It suggests that VIP is involved in the pathological processes occurring during this disease. Observed changes may be a result of neuroprotective and/or adaptive processes regulated by VIP, aimed at the homeostasis maintenance in the inflamed gastrointestinal (GI) tract and induced by proinflammatory factors.

Abstract

Canine inflammatory bowel disease (IBD) is a group of enteropathies with nonspecific chronic symptoms and poorly understood etiology. Many aspects connected with IBD are not understood. One of them is the participation of the intestinal nervous system in the development of pathological processes. Thus, this study aimed to demonstrate changes in the density of intramucosal nerve fibers containing vasoactive intestinal polypeptide (VIP)—one of the most important intestinal nervous factors caused by the various stages of IBD development. Mucosal biopsy specimens collected from the duodenum, jejunum and descending colon of healthy dogs and dogs with varied severity of IBD were included in the experiment. The density of VIP-like immunoreactive (VIP-LI) nerves was determined by a single immunofluorescence technique and a semi-quantitative method consisting in VIP-LI fiber counts in the field of view (0.1 mm²). The obtained results indicate that IBD induces changes in the density of mucosal VIP-LI nerve fibers in the canine gastrointestinal tract. The initial decrease is followed by an increase in VIP-like immunoreactivity in successive stages of the disease. These observations show that VIP is a neuronal factor that participates in the pathological processes connected with canine IBD. The observed changes probably result from the neuroprotective and/or adaptive properties of VIP. Protective and adaptive reactions induced by inflammation aim to protect the GI tract against damage by proinflammatory factors and ensure the homeostasis in the enteric nervous system (ENS) under the conditions changed by the disease process.

Effect of Acrylamide Supplementation on the CART-, VAChT-, and nNOS-Immunoreactive Nervous Structures in the Porcine Stomach

Simple Summary

The progress of civilization has provided people with virtually unlimited access to food products. However, while the pace of life has increased, the consumption of products with high levels of acrylamide (e.g., chips, corn flakes or coffee) has also increased. The gastrointestinal tract is the first-exposure site for noxious substances ingested with food and it is also often the first defence mechanism. Changes in the expression of neuroactive substances in the intramural neurons of the enteric nervous system (ENS) are a common preclinical symptom of the harmful effect of pathological factors on the body. Using the double immunofluorescence staining method, it was established that supplementation with low and high doses of acrylamide resulted in alterations of the porcine stomach neuron phenotype, which was reflected in an increased number of the cocaine- and amphetamine-regulated transcript (CART)-, vesicular acetylcholine transporter (VAChT)-, and neuronal isoform of nitric oxide synthase (nNOS)-immunoreactive neurons. The recorded changes revealed that even low doses of acrylamide influence the nervous structures located in the porcine gastric wall. This may result from the neurotoxicity of acrylamide or from the response of the ENS to acrylamide-induced inflammation and suggests an important role of the ENS in protecting the gastrointestinal tract during acrylamide intoxication.

Abstract

Acrylamide is found in food products manufactured with high-temperature processing, and exposure to acrylamide contained in food products may cause a potential risk to human health. The aim of this investigation was to demonstrate the changes in the population of CART-, nNOS-, and VAChT-immunoreactive enteric neurons in the porcine stomach in response to supplementation of low and high acrylamide doses. The study was carried out with 15 Danish landrace gilts divided into three experimental groups: the control group—animals were administered empty gelatine capsules; the low-dose group—animals were administrated a tolerable daily intake (TDI) dose (0.5 µg/kg of body weight (b.w.)/day) of acrylamide capsules, and the high-dose group—animals were administrated high-dose (ten times higher than TDI: 5 µg/kg b.w./day) acrylamide capsules for 28 days. Using the double immunofluorescence staining method, it was established that supplementation with low and high doses of acrylamide resulted in alterations of the porcine stomach neuron phenotype, which was reflected in an increased number of CART-, VAChT-, and nNOS-immunoreactive neurons. These changes were accompanied by an increased density of CART-, VAChT-, and nNOS-positive fibres. The results suggest that the enteric nervous system plays an important role in protecting the gastrointestinal tract during acrylamide intoxication.

Neurochemical Plasticity of nNOS-, VIP- and CART-Immunoreactive Neurons Following Prolonged Acetylsalicylic Acid Supplementation in the Porcine Jejunum

Aspirin, also known as acetylsalicylic acid (ASA), is a commonly used anti-inflammatory drug that has analgesic and antipyretic properties. The side effects are well known, however, knowledge concerning its influence on gastric and intestinal innervation is limited. The enteric nervous system (ENS) innervates the whole gastrointestinal tract (GIT) and is comprised of more than one hundred million neurons. The capacity of neurons to adapt to microenvironmental influences, termed as an enteric neuronal plasticity, is an essential adaptive response to various pathological stimuli. Therefore, the goal of the present study was to determine the influence of prolonged ASA supplementation on the immunolocalization of neuronal nitric oxide synthase (nNOS), vasoactive intestinal peptide (VIP) and cocaine- and amphetamine- regulated transcript peptide (CART) in the porcine jejunum. The experiment was performed on 8 Pietrain × Duroc immature gilts. Using routine double-labelling immunofluorescence, we revealed that the ENS nerve cells underwent adaptive changes in response to the induced inflammation, which was manifested by upregulated or downregulated expression of the studied neurotransmitters. Our results suggest the participation of nNOS, VIP and CART in the development of inflammation and may form the basis for further neuro-gastroenterological research.

The impact of low and high doses of acrylamide on the intramural neurons of the porcine ileum

The present study was designed to assess the influence of acrylamide supplementation, in tolerable daily intake (TDI) dose and a dose ten times higher than TDI, on the neurochemical phenotype of the ENS neurons and synthesis of proinflammatory cytokines in the wall of the porcine ileum. The study was performed on 15 juvenile female Danish Landrace pigs, divided into three groups: C group- animals receiving empty gelatine capsules, LD group- animals receiving capsules with the TDI dose (0.5 μg/kg b.w./day) of acrylamide and HD group- animals receiving acrylamide in a dose ten times higher than the TDI (5 μg/kg b.w./day) in a morning meal for 28 days. It was established that supplementation of acrylamide led to an increase in substance P (SP)-, calcitonin gene-related peptide (CGRP)-, galanin (GAL)- and vesicular acetylcholine transporter (VAChT)-like immunoreactive (LI) neurons as well as a decrease in neuronal nitric oxide synthase (nNOS) -like immunoreactivity in all types of ileum intramural plexuses. Moreover, using ELISA method, an increase in the level of proinflammatory cytokines (IL-1β, IL-6 and TNF- α) was noted in the ileum wall. The results suggest that SP, CGRP, GAL, nNOS and VACHT participate in the regulation of inflammatory conditions induced by acrylamide supplementation.

Co-treatment With BGP-15 Exacerbates 5-Fluorouracil-Induced Gastrointestinal Dysfunction

Gastrointestinal (GI) side-effects of chemotherapy present a constant impediment to efficient and tolerable treatment of cancer. GI symptoms often lead to dose reduction, delays and cessation of treatment. Chemotherapy-induced nausea, bloating, vomiting, constipation, and/or diarrhea can persist up to 10 years post-treatment. We have previously reported that long-term 5-fluorouracil (5-FU) administration results in enteric neuronal loss, acute inflammation and intestinal dysfunction. In this study, we investigated whether the cytoprotectant, BGP-15, has a neuroprotective effect during 5-FU treatment. Balb/c mice received tri-weekly intraperitoneal 5-FU (23 mg/kg/d) administration with and without BGP-15 (15 mg/kg/d) for up to 14 days. GI transit was analyzed via in vivo serial X-ray imaging prior to and following 3, 7, and 14 days of treatment. On day 14, colons were collected for assessment of ex vivo colonic motility, neuronal mitochondrial superoxide, and cytochrome c levels as well as immunohistochemical analysis of myenteric neurons. BGP-15 did not inhibit 5-FU-induced neuronal loss, but significantly increased the number and proportion of choline acetyltransferase (ChAT)-immunoreactive (IR) and neuronal nitric oxide synthase (nNOS)-IR neurons in the myenteric plexus. BGP-15 co-administration significantly increased mitochondrial superoxide production, mitochondrial depolarization and cytochrome c release in myenteric plexus and exacerbated 5-FU-induced colonic inflammation. BGP-15 exacerbated 5-FU-induced colonic dysmotility by reducing the number and proportion of colonic migrating motor complexes and increasing the number and proportion of fragmented contractions and increased fecal water content indicative of diarrhea. Taken together, BGP-15 co-treatment aggravates 5-FU-induced GI side-effects, in contrast with our previous findings that BGP-15 alleviates GI side-effects of oxaliplatin.

Distribution Patterns of Cocaine- and Amphetamine-Regulated Transcript- and/or Galanin-Containing Neurons and Nerve Fibers Located in the Human Stomach Wall Affected by Tumor

The aim of the study was to investigate the distribution patterns of cocaine- and amphetamine-regulated transcript- (CART-) and galanin-immunoreactive (GAL-IR) neuronal structures in the human stomach wall, focusing on differences observed in regions directly affected by the cancer process, and those from the surgical margin. Samples from the stomach wall were collected from 10 patients (3 women and 7 men, the mean age 67.0 ± 11.9). Next, triple-immunofluorescence staining was used to visualize the changes in the frequency of neurons inside myenteric plexi and intramural fibers containing CART and/or GAL, as well as protein gene product 9.5 (as panneuronal marker). Tumor into the stomach wall caused a decrease in the number of CART-positive (+) nerve fibers in the longitudinal (LML) and circular muscle layers (CML). Notable changes in the dense network of CART+/GAL+ nerve fibers (an increase) were observed in the LML and lamina muscularis mucosae (LMM) within carcinoma-affected areas of the human stomach. Additionally, an elevated number of these nerve fibers from LMM were accompanied by an increase in the number of fibers containing GAL in the vicinity of the neoplastic proliferation. Obtained results suggest that a carcinoma invasion may affect the innervation pattern of the human stomach wall and their function(s).

Changes in VIP-, SP- and CGRP- like immunoreactivity in intramural neurons within the pig stomach following supplementation with low and high doses of acrylamide

Acrylamide is one of the food toxins to which the human body is exposed. Although researchers' interest in acrylamide has been growing in recent years, the knowledge of its effect on the gastrointestinal tract, especially on intramural neurons which form the enteric nervous system is scarce. The aim of this experiment was to determine the influence of acrylamide, administered at doses equivalent to the human tolerable daily intake (TDI, 0.5 μg/kg b.w./day) and ten times higher than the TDI (5 μg/kg b.w./day), on the distribution of vasoactive intestinal peptide (VIP), substance P (SP), and calcitonin gene related peptide (CGRP) in intramural neurons of the domestic pig stomach. Using double immunofluorescent labelling we revealed that the ENS neurons underwent adaptive changes in response to the supplementation of acrylamide, which manifested themselves as increased expression of VIP, SP and CGRP, both in intramural neurons and by an increase in the nerve density in submucous and muscular layers in the porcine stomach. These substances take part in defensive reactions of neurons and transmission of sensory reactions may play an important role in protecting the stomach against the harmful effect of acrylamide. Moreover, it has been shown that acrylamide induces a significant response of ENS neurons even in TDI dose, which suggests that it is not neutral to the body. These findings may be the basis for further toxicological studies addressing the question if currently permitted minimal content of acrylamide in the food does jeopardize the health of human consumers?

Toxoplasma gondii promotes changes in VIPergic submucosal neurons, mucosal intraepithelial lymphocytes, and goblet cells during acute infection in the ileum of rats

BACKGROUND

The intestinal mucosa plays an important role in the mechanical barrier against pathogens. During Toxoplasma gondii infection, however, the parasites invade the epithelial cells of the small intestine and initiate a local immune response. In the submucosal plexus, this response promotes an imbalance of neurotransmitters and induces neuroplasticity, which can change the integrity of the epithelium and its secretory function. This study evaluated the submucosal neurons throughout acute T. gondii infection and the relationship between possible alterations and the epithelial and immune defense cells of the mucosa.

METHODS

Forty Wistar rats were randomly assigned to 8 groups (n = 5): 1 control group, uninfected, and 7 groups infected with an inoculation of 5000 sporulated T. gondii oocysts (ME-49 strain, genotype II). Segments of the ileum were collected for standard histological processing, histochemical techniques, and immunofluorescence.

KEY RESULTS

The infection caused progressive neuronal loss in the submucosal general population and changed the proportion of VIPergic neurons throughout the infection periods. These changes may be related to the observed reduction in goblet cells that secret sialomucins and increase in intraepithelial lymphocytes after 24 hours, and the increase in immune cells in the lamina propria after 10 days of infection. The submucosa also presented fibrogenesis, characterizing injury and tissue repair.

CONCLUSIONS AND INFERENCES

The acute T. gondii infection in the ileum of rats changes the proportion of VIPergic neurons and the epithelial cells, which can compromise the mucosal defense during infection.

Focal, but not global, cerebral ischaemia causes loss of myenteric neurons and upregulation of vasoactive intestinal peptide in mouse ileum

Reduced blood flow to the brain induces cerebral ischaemia, potentially causing central injury and peripheral complications including gastrointestinal (GI) dysfunction. The pathophysiology behind GI symptoms is suspected to be neuropathy in the enteric nervous system (ENS), which is essential in regulating GI function. This study investigates if enteric neuropathy occurs after cerebral ischaemia, by analysing neuronal survival and relative numbers of vasoactive intestinal peptide (VIP) and neuronal nitric oxide synthase (nNOS) expressing neurons in mouse ileum after three types of cerebral ischaemia. Focal cerebral ischaemia, modelled by permanent middle cerebral artery occlusion (pMCAO) and global cerebral ischaemia, modelled with either transient occlusion of both common carotid arteries followed by reperfusion (GCIR) or chronic cerebral hypoperfusion (CCH) was performed on C56BL/6 mice. Sham-operated mice for each ischaemia model served as control. Ileum was collected after 1-17 weeks, depending on model, and analysed using morphometry and immunocytochemistry. For each group, intestinal mucosa and muscle layer thicknesses, neuronal numbers and relative proportions of neurons immunoreactive (IR) for nNOS or VIP were estimated. No alterations in mucosa or muscle layer thicknesses were noted in any of the groups. Loss of myenteric neurons and an increased number of VIP-IR submucous neurons were found in mouse ileum 7 days after pMCAO. None of the global ischaemia models showed any alterations in neuronal survival or relative numbers of VIP- and nNOS-IR neurons. We conclude that focal cerebral ischaemia and global cerebral ischaemia influence enteric neuronal survival differently. This is suggested to reflect differences in peripheral neuro-immune responses.

Chronic treatment with fluoride affects the jejunum: insights from proteomics and enteric innervation analysis

Gastrointestinal symptoms are the first signs of fluoride (F) toxicity. In the present study, the jejunum of rats chronically exposed to F was evaluated by proteomics, as well as by morphological analysis. Wistar rats received water containing 0, 10 or 50 mgF/L during 30 days. HuC/D, neuronal Nitric Oxide (nNOS), Vasoactive Intestinal Peptide (VIP), Calcitonin Gene Related Peptide (CGRP), and Substance P (SP) were detected in the myenteric plexus of the jejunum by immunofluorescence. The density of nNOS-IR neurons was significantly decreased (compared to both control and 10 mgF/L groups), while the VIP-IR varicosities were significantly increased (compared to control) in the group treated with the highest F concentration. Significant morphological changes were seen observed in the density of HUC/D-IR neurons and in the area of SP-IR varicosities for F-treated groups compared to control. Changes in the abundance of various proteins correlated with relevant biological processes, such as protein synthesis, glucose homeostasis and energy metabolism were revealed by proteomics.

Modulation of VIPergic phenotype of enteric neurons by colonic biopsy supernatants from patients with inflammatory bowel diseases: Involvement of IL-6 in Crohn's disease

BACKGROUND

Neuroplastic changes in the enteric nervous system (ENS) observed during IBD might participate in physiopathological processes. Vasoactive intestinal polypeptide has been shown to be involved in intestinal inflammation and barrier functions. We aimed to investigate the modulation of VIP expression in colonic biopsies of IBD patient, the ability of soluble factors from biopsies to reproduce in vitro these modulations and identify soluble factors responsible.

METHODS

VIP and cytokines mRNA expressions were assessed in colonic biopsies of healthy subjects (HS) and IBD patients from inflamed (I) and non-inflamed areas (NI). Supernatants (SUP) of biopsies were applied to primary culture of ENS and VIP and cytokines mRNA expressions were assessed. The role of cytokines in SUP induced changes in VIP expression was evaluated.

KEY RESULTS

VIP mRNA expression was lower in biopsies of patients with Crohn's disease (CD) than Ulcerative Colitis (UC) but unchanged as compared to HS. VIP mRNA and protein expression were lower in primary culture of ENS incubated with SUP-CD than with SUP-UC. Furthermore, in CD but not UC, SUP-I reduced VIP expression in the ENS as compared to SUP-NI. Next, IL-6 but not IL-5, IL-10, IL-17, IFN-γ or TNF-α reduced VIP expression in the ENS. Finally, in CD, SUP-I incubated with anti-IL-6 antibody increased VIP expression as compared to SUP-I alone.

CONCLUSIONS & INFERENCES

Mucosal soluble factors from IBD induce VIP neuroplastic changes in the ENS. IL-6 was identified as a putative soluble factor responsible in part for changes in VIP expression in CD.

Oxaliplatin-induced enteric neuronal loss and intestinal dysfunction is prevented by co-treatment with BGP-15

BACKGROUND AND PURPOSE

Gastrointestinal side effects of chemotherapy are an under-recognized clinical problem, leading to dose reduction, delays and cessation of treatment, presenting a constant challenge for efficient and tolerated anti-cancer treatment. We have found that oxaliplatin treatment results in intestinal dysfunction, oxidative stress and loss of enteric neurons. BGP-15 is a novel cytoprotective compound with potential HSP72 co-inducing and PARP inhibiting properties. In this study, we investigated the potential of BGP-15 to alleviate oxaliplatin-induced enteric neuropathy and intestinal dysfunction.

EXPERIMENTAL APPROACH

Balb/c mice received oxaliplatin (3 mg·kg^-1 ·day^-1 ) with and without BGP-15 (15 mg·kg^-1 ·day^-1 : i.p.) tri-weekly for 14 days. Gastrointestinal transit was analysed via in vivo X-ray imaging, before and after treatment. Colons were collected to assess ex vivo motility, neuronal mitochondrial superoxide and cytochrome c levels and for immunohistochemical analysis of myenteric neurons.

KEY RESULTS

Oxaliplatin-induced neuronal loss increased the proportion of neuronal NO synthase-immunoreactive neurons and increased levels of mitochondrial superoxide and cytochrome c in the myenteric plexus. These changes were correlated with an increase in PARP-2 immunoreactivity in the colonic mucosa and were attenuated by BGP-15 co-treatment. Significant delays in gastrointestinal transit, intestinal emptying and pellet formation, impaired colonic motor activity, reduced faecal water content and lack of weight gain associated with oxaliplatin treatment were restored to sham levels in mice co-treated with BGP-15.

CONCLUSION AND IMPLICATIONS

Our results showed that BGP-15 ameliorated oxidative stress, increased enteric neuronal survival and alleviated oxaliplatin-induced intestinal dysfunction, suggesting that BGP-15 may relieve the gastrointestinal side effects of chemotherapy.

Myenteric neuroprotective role of aspirin in acute and chronic experimental infections with Trypanosoma cruzi

BACKGROUND

Experimental and clinical studies have shown that myenteric neuron cell death during infection with Trypanosoma cruzi mainly occurs in the esophagus and colon, resulting in megaesophagus and megacolon, respectively. Evidence suggests that the cyclooxygenase enzyme (COX) is involved in the T. cruzi invasion process. The use of low-dose aspirin (ASA), a COX-1/COX-2 inhibitor, has been shown to reduce infection with T. cruzi. Therefore, in this study, we evaluated the effects of treatment with low-dose ASA on myenteric colonic neurons during murine infection with T. cruzi.

METHODS

Swiss mice were assigned into groups treated with either phosphate-buffered saline or low doses of ASA during the acute phase (20 mg/kg ASA) and chronic phase (50 mg/kg ASA) of infection with the Y strain of T. cruzi. Seventy-five days after infection, colon samples were collected to quantify inflammatory foci in histological sections and also general (myosin-V⁺ ), nitrergic, and VIPergic myenteric neurons in whole mounts. Gastrointestinal transit time was also measured.

KEY RESULTS

Aspirin treatment during the acute phase of infection reduced parasitemia (P<.05). Aspirin treatment during the acute or chronic phase of the infection reduced the intensity of inflammatory foci in the colon, protected myenteric neurons from cell death and plastic changes, and recovered the gastrointestinal transit of mice infected with T. cruzi (P<.05).

CONCLUSION & INFERENCES

Early and delayed treatment with low-dose ASA can reduce the morphofunctional damage of colonic myenteric neurons caused by murine T. cruzi infection.

The role of enteric neurons in the development and progression of colorectal cancer

The enteric nervous system (ENS) is the intrinsic neural network of the gastrointestinal tract, which is essential for regulating gut functions and intestinal homeostasis. The importance of the ENS is underscored by the existence of severe gastrointestinal diseases, such as Hirschsprung's disease and intestinal pseudo-obstruction, which arise when the ENS fails to develop normally or becomes dysregulated. Moreover, it is known that enteric neurons are involved in intestinal inflammation. However, the role of the ENS in colorectal cancer (CRC) carcinogenesis remains poorly understood, even though processes like perineural invasion and neoneurogenesis are important factors in CRC. Here we summarize how enteric neurons are affected during CRC and discuss the influence of enteric neurons, either direct or indirect, on the development and/or progression of CRC. Finally, we illustrate how the ENS could be targeted as a potential anti-cancer therapy, establishing the ENS as an integral part of the tumor microenvironment.

Toll-Like Receptor 4 Modulates Small Intestine Neuromuscular Function through Nitrergic and Purinergic Pathways

Objective: Toll-like receptors (TLRs) play a pivotal role in the homeostatic microflora-host crosstalk. TLR4-mediated modulation of both motility and enteric neuronal survival has been reported mainly for colon with limited information on the role of TLR4 in tuning structural and functional integrity of enteric nervous system (ENS) and in controlling small bowel motility. Methods: Male TLR4 knockout (TLR4^-/-, 9 ± 1 weeks old) and sex- and age-matched wild-type (WT) C57BL/6J mice were used for the experiments. Alterations in ENS morphology and neurochemical code were assessed by immunohistochemistry whereas neuromuscular function was evaluated by isometric mechanical activity of ileal preparations following receptor and non-receptor-mediated stimuli and by gastrointestinal transit. Results: The absence of TLR4 induced gliosis and reduced the total number of neurons, mainly nNOS⁺ neurons, in ileal myenteric plexus. Furthermore, a lower cholinergic excitatory response with an increased inhibitory neurotransmission was found together with a delayed gastrointestinal transit. These changes were dependent on increased ileal non-adrenergic non-cholinergic (NANC) relaxations mediated by a complex neuronal-glia signaling constituted by P2X7 and P2Y1 receptors, and NO produced by nNOS and iNOS. Conclusion: We provide novel evidence that TLR4 signaling is involved in the fine-tuning of P2 receptors controlling ileal contractility, ENS cell distribution, and inhibitory NANC neurotransmission via the combined action of NO and adenosine-5'-triphosphate (ATP). For the first time, this study implicates TLR4 at regulating the crosstalk between glia and neurons in small intestine and helps to define its role in gastrointestinal motor abnormalities during dysbiosis.

Experimental Cancer Cachexia Changes Neuron Numbers and Peptide Levels in the Intestine: Partial Protective Effects after Dietary Supplementation with L-Glutamine

Gastrointestinal dysmotility frequently occurs in cancer cachexia and may result from damage to enteric innervation caused by oxidative stress, especially due to glutathione depletion. We assessed the effect of dietary supplementation with 20 g/kg l-glutamine (a glutathione precursor) on the intrinsic innervation of the enteric nervous system in healthy and Walker 256 tumor-bearing Wistar rats during the development of experimental cachexia (14 days), in comparison with non-supplemented rats, by using immunohistochemical methods and Western blotting. The total neural population and cholinergic subpopulation densities in the myenteric plexus, as well as the total population and VIPergic subpopulation in the submucosal plexus of the jejunum and ileum, were reduced in cachectic rats, resulting in adaptive morphometric alterations and an increase in vasoactive intestinal peptide (VIP) and calcitonin gene-related peptide (CGRP) expression, suggesting a neuroplastic response. l-glutamine supplementation prevented decrease in myenteric neuronal density in the ileum, morphometric alterations in the neurons and nerve fibers (in both the plexuses of the jejunum and ileum), and the overexpression of VIP and CGRP. Cancer cachexia severely affected the intrinsic innervation of the jejunum and ileum to various degrees and this injury seems to be associated with adaptive neural plasticity. l-glutamine supplementation presented partial protective effects on the enteric innervation against cancer cachexia, possibly by attenuating oxidative stress.

Differential effects in CGRPergic, nitrergic, and VIPergic myenteric innervation in diabetic rats supplemented with 2% L-glutamine

ABSTRACT The objective of this study was to investigate the effects of 2% L-glutamine supplementation on myenteric innervation in the ileum of diabetic rats, grouped as follows: normoglycemic (N); normoglycemic supplemented with L-glutamine (NG); diabetic (D); and diabetic supplemented with L-glutamine (DG). The ileums were subjected to immunohistochemical techniques to localize neurons immunoreactive to HuC/D protein (HuC/D-IR) and neuronal nitric oxide synthase enzyme (nNOS-IR) and to analyze varicosities immunoreactive to vasoactive intestinal polypeptide (VIP-IR) and calcitonin gene-related peptide (CGRP-IR). L-Glutamine in the DG group (i) prevented the increase in the cell body area of nNOS-IR neurons, (ii) prevented the increase in the area of VIP-IR varicosities, (iii) did not prevent the loss of HuC/D-IR and nNOS-IR neurons per ganglion, and (iv) reduced the size of CGRP-IR varicosities. L-Glutamine in the NG group reduced (i) the number of HuC/D-IR and nNOS-IR neurons per ganglion, (ii) the cell body area of nNOS-IR neurons, and (iii) the size of VIP-IR and CGRP-IR varicosities. 2% L-glutamine supplementation exerted differential neuroprotective effects in experimental diabetes neuropathy that depended on the type of neurotransmitter analyzed. However, the effects of this dose of L-glutamine on normoglycemic animals suggests there are additional actions of this beyond its antioxidant capacity.

The Influence of Prolonged Acetylsalicylic Acid Supplementation-Induced Gastritis on the Neurochemistry of the Sympathetic Neurons Supplying Prepyloric Region of the Porcine Stomach

This experiment was designed to establish the localization and neurochemical phenotyping of sympathetic neurons supplying prepyloric area of the porcine stomach in a physiological state and during acetylsalicylic acid (ASA) induced gastritis. In order to localize the sympathetic perikarya the stomachs of both control and acetylsalicylic acid treated (ASA group) animals were injected with neuronal retrograde tracer Fast Blue (FB). Seven days post FB injection, animals were divided into a control and ASA supplementation group. The ASA group was given 100 mg/kg of b.w. ASA orally for 21 days. On the 28^th day all pigs were euthanized with gradual overdose of anesthetic. Then fourteen-micrometer-thick cryostat sections were processed for routine double-labeling immunofluorescence, using primary antisera directed towards tyrosine hydroxylase (TH), dopamine β-hydroxylase (DβH), neuropeptide Y (NPY), galanin (GAL), neuronal nitric oxide synthase (nNOS), leu 5-enkephalin (LENK), cocaine- and amphetamine- regulated transcript peptide (CART), calcitonin gene-related peptide (CGRP), substance P (SP) and vasoactive intestinal peptide (VIP). The data obtained in this study indicate that postganglionic sympathetic nerve fibers supplying prepyloric area of the porcine stomach originate from the coeliac-cranial mesenteric ganglion complex (CCMG). In control animals, the FB-labelled neurons expressed TH (94.85 ± 1.01%), DβH (97.10 ± 0.97%), NPY (46.88 ± 2.53%) and GAL (8.40 ± 0.53%). In ASA group, TH- and DβH- positive nerve cells were reduced (85.78 ± 2.65% and 88.82 ± 1.63% respectively). Moreover, ASA- induced gastritis resulted in increased expression of NPY (76.59 ± 3.02%) and GAL (26.45 ± 2.75%) as well as the novo-synthesis of nNOS (6.13 ± 1.11%) and LENK (4.77 ± 0.42%) in traced CCMG neurons. Additionally, a network of CART-, CGRP-, SP-, VIP-, LENK-, nNOS- immunoreactive (IR) nerve fibers encircling the FB-positive perikarya were observed in both intact and ASA-treated animals. The results of this study indicate involvement of these neuropeptides in the development or presumably counteraction of gastric inflammation.

Resveratrol Reduces Morphologic Changes in the Myenteric Plexus and Oxidative Stress in the Ileum in Rats with Ischemia/Reperfusion Injury

BACKGROUND

Intestinal ischemia/reperfusion injury can be caused by surgical procedures and inflammatory bowel disease. It is normally associated with the increased production of free radicals and changes in the enteric nervous system.

AIMS

Given the antioxidant and neuroprotective properties of resveratrol, the present study assessed its influence on oxidative stress in the intestinal wall and the morphology of myenteric neurons in the ileum of rats subjected to ischemia/reperfusion.

METHODS

Resveratrol was orally administered daily at a dose of 10 mg/kg for 5 days. Changes in the ileum response to ischemia after 45 min were investigated followed by 3 h reperfusion. Lipoperoxide and carbonylated protein levels, and the activity of the antioxidant enzymes glutathione reductase, glutathione peroxidase, and glucose-6-phosphate dehydrogenase were measured following ischemia/reperfusion injury.

RESULTS

The density and morphometry of the general neuronal population, nitrergic neurons and glial cells, and morphometry of VIP varicosities in the ileum were also studied. Lipoperoxide and carbonylated protein levels were 171 and 40% higher during the ischemia/reperfusion, respectively, compared to control cohorts, and resveratrol attenuated these values. The glutathione ratio was 64% lower during ischemia/reperfusion, compared to control cohorts. Resveratrol increased the reduced/oxidized glutathione ratio, attenuated the changes in the activity of the antioxidant enzymes and the detrimental morphologic changes caused by ischemia/reperfusion in the general neuronal population and nitrergic neurons.

CONCLUSIONS

Oral treatment with resveratrol reduced the oxidative stress in the ileum and attenuated the morphologic changes that occurred in the myenteric plexus of the ileum in rats subjected to ischemia/reperfusion.

Toxoplasma gondii causes death and plastic alteration in the jejunal myenteric plexus

AIM: To assess the effects of ME-49 Toxoplasma gondii (T. gondii) strain infection on the myenteric plexus and external muscle of the jejunum in rats.

METHODS: Thirty rats were distributed into two groups: the control group (CG) (n = 15) received 1 mL of saline solution orally, and the infected group (IG) (n = 15) inoculated with 1 mL of saline solution containing 500 oocysts of M-49 T. gondii strain orally. After 36 d of infection, the rats were euthanized. Infection with T. gondii was confirmed by blood samples collected from all rats at the beginning and end of the experiment. The jejunum of five animals was removed and submitted to routine histological processing (paraffin) for analysis of external muscle thickness. The remaining jejunum from the others animals was used to analyze the general population and the NADH-diaphorase, VIPergic and nitrergic subpopulations of myenteric neurons; and the enteric glial cells (S100-IR).

RESULTS: Serological analysis showed that animals from the IG were infected with the parasite. Hypertrophy affecting jejunal muscle thickness was observed in the IG rats (77.02 ± 42.71) in relation to the CG (51.40 ± 12.34), P < 0.05. In addition, 31.2% of the total number of myenteric neurons died (CG: 39839.3 ± 5362.3; IG: 26766.6 ± 2177.6; P < 0.05); hyperplasia of nitrergic myenteric neurons was observed (CG: 7959.0 ± 1290.4; IG: 10893.0 ± 1156.3; P < 0.05); general hypertrophy of the cell body in the remaining myenteric neurons was noted [CG: 232.5 (187.2-286.0); IG: 248.2 (204.4-293.0); P < 0.05]; hypertrophy of the smallest varicosities containing VIP neurotransmitter was seen (CG: 0.46 ± 0.10; IG: 0.80 ± 0.16; P < 0.05) and a reduction of 25.3% in enteric glia cells (CG: 12.64 ± 1.27; IG: 10.09 ± 2.10; P < 0.05) was observed in the infected rats.

CONCLUSION: It was concluded that infection with oocysts of ME-49 T. gondii strain caused quantitative and plastic alterations in the myenteric plexus of the jejunum in rats.

Chagasic megacolon: enteric neurons and related structures

Megacolon, the irreversible dilation of a colonic segment, is a structural sign associated with various gastrointestinal disorders. In its hereditary, secondary form (e.g. in Hirschsprung's disease), dilation occurs in an originally healthy colonic segment due to an anally located, aganglionic zone. In contrast, in chronic Chagas' disease, the dilated segment itself displays pathohistological changes, and the earliest and most prominent being found was massive loss of myenteric neurons. This neuron loss was partial and selective, i.e. some neurons containing neuronal nitric oxide synthase and/or vasoactive intestinal peptide (VIP) were spared from neuron death. This disproportionate survival of inhibitory neurons, however, did not completely correlate with the calibre change along the surgically removed, megacolonic segments. A better correlation was observed as to potentially contractile muscle tissue elements and the interstitial cells of Cajal. Therefore, the decreased densities of α-smooth muscle actin- and c-kit-immunoreactive profiles were estimated along resected megacolonic segments. Their lowest values were observed in the megacolonic zones itself, whereas less pronounced decreases were found in the non-dilated, transitional zones (oral and anal to dilation). In contrast to the myenteric plexus, the submucosal plexus displayed only a moderate neuron loss. Neurons co-immunoreactive for VIP and calretinin survived disproportionately. As a consequence, these neurons may have contributed to maintain the epithelial barrier and allowed the chagasic patients to survive for decades, despite their severe disturbance of colonic motility. Due to its neuroprotective and neuroeffectory functions, VIP may play a key role in the development and duration of chagasic megacolon.

Region-specific differences in the human myenteric plexus: an immunohistochemical study using donated elderly cadavers

PURPOSE AND METHODS

To identify site-dependent and individual differences in neuronal nitric oxide synthase (nNOS)-positive nerves of the myenteric plexus, we examined full-thickness walls of the stomach, pylorus, duodenum, ileum, colon, and rectum in 7 male and 8 female cadavers (mean ages, 80 and 87 years, respectively).

RESULTS

The areas occupied by nNOS-positive nerve fibers in the myenteric plexus were fragmentary and overlapped with areas occupied by vasoactive intestinal polypeptide-positive fibers. The nNOS-positive fiber-containing areas per 1-mm length of intermuscular space tended to be larger at more anal sites, with positive areas four times greater in the rectum than in the stomach. Interindividual differences in rectal areas were extremely large, ranging from 0.017 mm(2) in one 80-year-old man to 0.067 mm(2) in another 80-year-old man. Similarly, the numbers of nNOS-positive ganglion cell bodies per 1-mm length in the rectum ranged from 4 to 28. These areas and numbers were weakly correlated (r = 0.62; p = 0.02). Interindividual differences in the rectum appeared not to depend on either age or gender.

CONCLUSIONS

Anatomic studies using donated cadavers carried the advantage of obtaining any parts of intestine within an individual, in contrast to surgically removed specimens. We speculated excess control of evacuation with laxatives as one of causes of atrophy of the rectal myenteric plexus.

Mucosal layers and related nerve fibres in non-chagasic and chagasic human colon--a quantitative immunohistochemical study

Chagasic megacolon is accompanied by extensive myenteric and, simultaneously, moderate submucosal neuron loss. Here, we examined changes of the innervation pattern of the lamina propria (LP) and muscularis mucosae (MM). Two alternating sets of cryosections were taken from seven non-chagasic colonic and seven chagasic megacolonic specimens (the latter included both the dilated megacolonic and the non-dilated transitional oral and anal zones) and were immunohistochemically triple-stained for smooth-muscle actin (SMA), synaptophysin (SYN) and glial acid protein S100 and, alternatively, for SMA, vasoactive intestinal peptide (VIP) and somatostatin (SOM). Subsequent image analysis and statistical evaluation of nervous tissue profile areas revealed that, in LP, the most extreme differences (i.e. increase in thickness or decrease in nerve, glia and muscle tissue profile area, respectively) compared with control values occurred in the dilated megacolonic zone itself. In contrast, the most extreme differences in the MM were in the anal-to-megacolonic zone (except the profile area of muscle tissue, which was lowest in the megacolonic zone). This parallels our previous results in the external muscle coat. A partial and selective survival of VIP-immunoreactive in contrast to SOM-immunoreactive nerve fibres was observed in both mucosal layers investigated. Thus, VIPergic nerve elements might be crucial for the maintenance of the mucosal barrier. The differential changes of neural tissue parameters in LP and MM might reflect a multifactorial rather than a pure neurogenic development of megacolon in chronic Chagas' disease.

Topohistology of sympathetic and parasympathetic nerve fibers in branches of the pelvic plexus: an immunohistochemical study using donated elderly cadavers

Although the pelvic autonomic plexus may be considered a mixture of sympathetic and parasympathetic nerves, little information on its composite fibers is available. Using 10 donated elderly cadavers, we investigated in detail the topohistology of nerve fibers in the posterior part of the periprostatic region in males and the infero-anterior part of the paracolpium in females. Neuronal nitric oxide synthase (nNOS) and vasoactive intestinal polypeptide (VIP) were used as parasympathetic nerve markers, and tyrosine hydroxylase (TH) was used as a marker of sympathetic nerves. In the region examined, nNOS-positive nerves (containing nNOS-positive fibers) were consistently predominant numerically. All fibers positive for these markers appeared to be thin, unmyelinated fibers. Accordingly, the pelvic plexus branches were classified into 5 types: triple-positive mixed nerves (nNOS+, VIP+, TH+, thick myelinated fibers + or -); double-positive mixed nerves (nNOS+, VIP-, TH+, thick myelinated fibers + or -); nerves in arterial walls (nNOS-, VIP+, TH+, thick myelinated fibers-); non-parasympathetic nerves (nNOS-, VIP-, TH+, thick myelinated fibers + or -); (although rare) pure sensory nerve candidates (nNOS-, VIP-, TH-, thick myelinated fibers+). Triple-positive nerves were 5-6 times more numerous in the paracolpium than in the periprostatic region. Usually, the parasympathetic nerve fibers did not occupy a specific site in a nerve, and were intermingled with sympathetic fibers. This morphology might be the result of an "incidentally" adopted nerve fiber route, rather than a target-specific pathway.

What neurons hide behind calretinin immunoreactivity in the human gut?

Calretinin (CALR) is often used as an immunohistochemical marker for the histopathological diagnosis of human intestinal neuropathies. However, little is known about its distribution pattern with respect to specific human enteric neuron types. Prior studies revealed CALR in both myenteric and submucosal neurons, most of which colabel with choline acetyl transferase (ChAT). Here, we specified the chemical code of CALR-positive neurons in small and large intestinal wholemounts in a series of 28 patients. Besides other markers, we evaluated the labeling pattern of CALR in combination with vasoactive intestinal peptide (VIP). In colonic submucosa, CALR and VIP were almost completely colocalized in about three-quarters of all submucosal neurons. In the small intestinal submucosa, both the colocalization rate of CALR and VIP as well as the proportion of these neurons were lower (about one-third). In the myenteric plexus of both small intestine and colon, CALR amounted to 11 and 10 %, respectively, whereas VIP to 5 and 4 % of the whole neuron population, respectively. Colocalization of both markers was found in only 2 and 3 % of myenteric neurons, respectively. In section specimens, nerve fibers coreactive for CALR and VIP were found in the mucosa but not in the muscle coat. Summarizing the present and earlier results, CALR was found in at least one submucosal and two myenteric neuron populations. Submucosal CALR+/VIP+/ChAT± neurons innervate mucosal structures. Furthermore, CALR immunoreactivity in the myenteric plexus was observed in morphological type II (supposed primary afferent) and spiny type I (supposed inter- or motor-) neurons.

Immunolocalization of NOS, VIP, galanin and SP in the small intestine of suckling pigs treated with red kidney bean (Phaseolus vulgaris) lectin

Lectins belong to a family of glycoproteins that can act both beneficially and detrimentally on the morphology of the small intestine. The aim of the study was to determine whether experimental treatment with red kidney bean (Phaseolus vulgaris) lectin influences the chemical code of the small intestine nervous system of suckling pigs. The immunolocalization sites of vasoactive intestinal polypeptide (VIP), nitric oxide synthase (NOS), substance P (SP) and galanin were determined in control and lectin-treated animals. In all segments of the small intestine (duodenum, jejunum, ileum), the subpopulations of VIP-, NOS-, SP- and galanin-immunoreactive (IR) myenteric neurons were unchanged. After lectin stimulation, increased proportions of NOS-IR and decreased numbers of VIP-IR submucous neurons/mucosa innervating nerve fibers were observed in the duodenum, jejunum and ileum. In lectin-treated animals down-regulation of submucous neurons expressing SP and up-regulation of galanin-IR submucous neurons were seen in the duodenum and jejunum (but not in the ileum). The distribution patterns of NOS-IR, galanin-IR and SP-IR nerve fibers supplying the duodenum, jejunum and ileum of the lectin-treated animals showed no substantial differences in relation to control piglets. We conclude that exposure to red kidney bean (P. vulgaris) lectin substantially changes the chemical content of VIP, NOS, SP and galanin in submucous neurons of the small intestine. These results are in line with previous findings outlining the key role(s) of these substances in enteric neuroplasticity processes and may constitute the basis for further functional studies on maturation of the gut.

Gonadotropin-releasing hormone analog buserelin causes neuronal loss in rat gastrointestinal tract

Gonadotropin-releasing hormone (GnRH) analogs are given to women undergoing in vitro fertilization. Case reports describing the development of chronic intestinal pseudo-obstruction and auto-antibodies against GnRH after such treatment suggest a strong association between intestinal dysfunction and GnRH analogs. No experimental model for studying such a relationship is currently at hand. Our main goal was to investigate possible enteric neurodegeneration and titers of GnRH antibodies in response to repeated administration of the GnRH analog buserelin in rat. Rats were treated for 1-4 sessions with daily subcutaneous injections of buserelin or saline for 5 days, followed by 3 weeks of recovery. Buserelin treatment caused significant loss of submucous and myenteric neurons in the fundus, ileum, and colon. The loss of enteric neurons can, at least partly, be explained by increased apoptosis. No GnRH- or GnRH-receptor-immunoreactive (IR) enteric neurons but numerous luteinizing hormone (LH)-receptor-IR neurons were detected. After buserelin treatment, the relative number of enteric LH-receptor-IR neurons decreased, whereas that of nitric-oxide-synthase-IR neurons increased. No intestinal inflammation or increased levels of circulating interleukins/cytokines were noted in response to buserelin treatment. Serum GnRH antibody titers were undetectable or extremely low in all rats. Thus, repeated administrations of buserelin induce neurodegeneration in rat gastrointestinal tract, possibly by way of LH-receptor hyperactivation. The present findings suggest that enteric neurodegenerative effects of GnRH analog treatment in man can be mimicked in rat. However, in contrast to man, no production of GnRH auto-antibodies has been noted in rat.

Intraepithelial lymphocytes, goblet cells and VIP-IR submucosal neurons of jejunum rats infected with Toxoplasma gondii

Toxoplasma gondii (T. gondii) crosses the intestinal barrier in oral infections and can lead to changes in different cell types, including the neurons located there. In the gastrointestinal system, the autonomous nervous system component that regulate blood flow and mucous secretion is the submucosal plexus. The aim of this study was to examine the effects of T. gondii infection on intraepithelial lymphocytes (IELs), goblet cells and submucosal neurons that are immunoreactive to vasoactive intestinal peptide (VIP-IR) of rat jejunum. Twenty male rats distributed as a control group (CG) and an infected group (IG), which received a suspension with 500 parasite oocysts (strain ME-49, genotype II) orally, were assessed. Routine histological sections were used to quantify IELs and to detect mucins secreted by goblet cells. Whole mounts including the submucosal layer were examined using immunofluorescence to detect the VIP neurotransmitter. Quantitative alterations in IELs were not observed. However, the reduction (P < 0.05) in the number of goblet cells that produce neutral mucins (PAS+) and sulphomucins (AB pH 1.0) and the maintenance of sialomucin-secreting cells (AB pH 2.5) resulting in a more fluid mucous were observed. Concerning the VIP-IR submucosal neurons, an increase in fluorescence on IG animals was observed. There was a reduction (P < 0.05) in the number of VIP-IR submucosal neurons and atrophy of their cell bodies in IG rats. Infection with T. gondii caused alterations in the chemical composition of the intestinal mucous and reduction in the neuron number and atrophy of the remaining neurons in this cell subpopulation.

Preponderance of inhibitory versus excitatory intramuscular nerve fibres in human chagasic megacolon

INTRODUCTION

Megacolon, chronic dilation of a colonic segment, is a frequent sign of Chagas disease. It is accompanied by an extensive neuron loss which, as shown recently, results in a partial, selective survival of nitrergic myenteric neurons. Here, we focused on the balance of intramuscular excitatory (choline acetyltransferase [ChAT]-immunoreactive) and inhibitory (neuronal nitric oxide synthase [NOS]- as well as vasoactive intestinal peptide [VIP]-immunoreactive) nerve fibres.

MATERIALS AND METHODS

From surgically removed megacolonic segments of seven patients, three sets of cryosections (from non-dilated oral, megacolonic and non-dilated anal parts) were immunhistochemically triple-stained for ChAT, NOS and VIP. Separate area measurements of nerve profiles within the circular and longitudinal muscle layers, respectively, were compared with those of seven non-chagasic control patients. Additionally, wholemounts from the same regions were stained for NOS, VIP and neurofilaments (NF).

RESULTS

The intramuscular nerve fibre density was significantly reduced in all three chagasic segments. The proportions of inhibitory (NOS only, VIP only, or NOS/VIP-coimmunoreactive) intramuscular nerves were 68 %/58 % (circular/longitudinal muscle, respectively) in the controls and increased to 75 %/69 % (oral parts), 84 %/76 % (megacolonic) and 87 %/94 % (anal) in chagasic specimens. In the myenteric plexus, NF-positive neurons co-staining for NOS and VIP also increased proportionally. The almost complete lack of dendritic structures in ganglia of chagasic specimens hampered morphological identification.

DISCUSSION AND CONCLUSION

We suggest that preponderance of inhibitory, intramuscular nerve fibres may be one factor explaining the chronic dilation. Since the nerve fibre imbalance is most pronounced in the anal, non-dilated segment, other components of the motor apparatus (musculature, interstitial cells, submucosal neurons) have to be considered.

Intestinal dysmotility and enteric neurochemical changes in a Parkinson's disease rat model

Gastrointestinal disorders, constipation in particular, are the most common non-motor dysfunctions affecting Parkinson's disease (PD) patients. We have previously reported that rats bearing unilateral nigrostriatal lesion caused by 6-hydroxydopamine (6-OHDA) stereotaxic injection develop severe constipation together with a region-specific decrease of neuronal nitric oxide synthase (nNOS) in enteric neurons of the lower intestinal tract. Here, we extend these observations on other enteric neuronal subpopulations, investigating also the propulsive activity of isolated colonic specimens. Four weeks post 6-OHDA injection, lesioned rats showed a significant increase of vasoactive intestinal polypeptide (VIP) concomitant with the reduced expression of nNOS in the myenteric plexus of distal ileum and proximal colon; in particular VIP increased in a subpopulation of neurons actively expressing nNOS. On the other hand, choline acetyltransferase (ChAT) was not modified in any of the intestinal segments analyzed. Interestingly, we found a reduced expression of dopamine receptor type 2 (D2R) in proximal (-66.8%) and distal (-54.5%) colon, together with reduced peristalsis efficiency (decrease in intraluminal pressure and frequency of peristaltic events) in the 6-OHDA-lesioned rats. The selective depletion of dopaminergic nigrostriatal neurons is associated with changes in the expression of enteric inhibitory neurotransmitters, as well as of the D2R in intestinal specific regions. Moreover, 6-OHDA-lesioned rats demonstrated altered colon propulsive activity referable to the D2R decrease. Our findings unveil subtle mechanisms underlying the enteric neurochemical plasticity events evoked by disruption of the normal brain-gut cross-talk, giving a peculiar point of view on the pathophysiology of the severe constipation that frequently affects PD patients.

Selective survival of calretinin- and vasoactive-intestinal-peptide-containing nerve elements in human chagasic submucosa and mucosa

Chronic Chagas' disease is frequently characterized by massive myenteric neuron loss resulting in megacolon with severely and irreversibly disturbed motility. Here, we focused on two submucosal neuron populations, immunoreactive for calretinin (CALR) or somatostatin (SOM), and their respective mucosal nerve fibres in chagasic megacolon. Surgically removed megacolonic segments of seven chagasic patients were compared with seven age- and region-matched non-chagasic control segments. Evaluation included immunohistochemical triple-staining of cryosections for CALR, SOM and peripherin or for CALR and vasoactive intestinal peptide (VIP) and of submucosal whole-mounts for CALR, SOM and the pan-neuronal marker anti-HuC/D. Submucosal neuron counts in chagasic tissue revealed neuron numbers reduced to 51.2 % of control values. In cryosections, nerve fibre area measurements revealed 8.6 % nerve fibre per mucosal area in control segments, but this value decreased to 1.5 % in megacolonic segments. In both evaluations, a disproportionate decrease of SOM-reactive nerve elements was observed. The proportions of SOM-positive neurons related to the total neuron number declined to 2 % (control 10 %) and the proportion of SOM-reactive mucosal nerve fibres related to the whole mucosal area to 0.014 % (control 1.8 %)in chagasic tissue. The second set of cryosections revealed extensive colocalization of CALR with VIP in both surviving submucosal perikarya and mucosal nerve fibres. We suggest that VIP, a neuroprotective and neuroeffectory peptide typically contained in submucosal neurons, allows both the VIP-containing neurons to endure and the patients to survive by maintaining their mucosal barrier, despite the almost complete loss of colonic motility for decades.

Increased proportion of nitric oxide synthase immunoreactive neurons in rat ileal myenteric ganglia after severe acute pancreatitis

BACKGROUND

Severe acute pancreatitis (SAP) remains a potentially life-threatening disease. Gastrointestinal motility disturbance such as intestinal ileus is seen in every case. By now, the mechanisms of pancreatitis-induced ileus are largely unknown. The main purpose of the present study was to observe changes of nitric oxide synthase-immunoreactive (NOS-IR) neurons in ileal myenteric ganglia in SAP rats with gastrointestinal dysmotility, trying to explore underlying nervous mechanisms of pancreatitis-induced ileus.

METHODS

Twenty Sprague Dawley rats were randomly divided into sham operated group and SAP group. SAP was induced by retrograde cholangiopancreatic duct injection of 5% sodium taurocholate. Abdominal X-ray and intestinal transit were performed to detect the existence of paralytic ileus and intestinal dysmotility. Pathological damage of pancreas was evaluated. Double-immunolabeling was employed for the whole-mount preparations of ileal myenteric ganglia. The morphology of NOS-IR neurons were observed and the percentage of NOS-IR neurons was calculated based on the total Hu-immunoreactive neurons. Total RNA of ileum was extracted according to Trizol reagent protocol. Neuronal NOS (nNOS) mRNA expression was evaluated by RT-PCR.

RESULTS

The small intestinal transit index in the SAP group was significantly lower compared with the sham operated group (29.21±3.68% vs 52.48±6.76%, P<0.01). The percentage of NOS-IR neurons in ileal myenteric ganglia in the SAP group was significantly higher than that in the sham operated group (37.5±12.28% vs 26.32±16.15%, P<0.01). nNOS mRNA expression in ileum of SAP group was significantly higher than that in the sham operated group (1.02±0.10 vs 0.70±0.06, P<0.01).

CONCLUSIONS

The increased quantity of NOS-IR neurons in ileal myenteric ganglia and increased nNOS mRNA expression may suggest nNOS over expression as one of the nervous mechanisms of gastrointestinal dysmotility in SAP rat.

Dysfunction of neurogenic VIP-mediated relaxation in mouse distal colon with dextran sulfate sodium-induced colitis

Vasoactive intestinal peptide (VIP) regulates various functions including motility and immune homeostasis in colon. The VIP system including its receptors has been established to control the development of ulcerative colitis, but the functional changes of the system-regulated motility in colon with ulcerative colitis are not well understood. In this study, we investigated VIP-related contractile responses in distal colon from mice with dextran sulfate sodium (DSS)-induced acute colitis. Electrical stimulation (ES) under our conditions caused relaxation during ES and contraction after withdrawal of ES in a tetrodotoxin-sensitive manner. Pharmacological analyses showed two phases of ES-induced relaxation: a transient neuronal nitric oxide (NO) synthase-dependent phase (I), and a continued VIP receptor-mediated phase (II). Inhibition of VIP receptors and protein kinase A decreased both phases. In colon from DSS-treated mice, ES-induced phase II (also phase I) and VIP-induced, but not cyclic AMP analog-induced, relaxation were decreased. Stimulation with VIP significantly increased cyclic AMP formation in colon preparations from control but not DSS-treated mice. In colon from DSS-treated mice, the basal cyclic AMP level was markedly greater without changes in the level of VIP receptor VPAC(2). Isoprenaline- and forskolin-induced relaxation and cyclic AMP formation were not changed by DSS treatment. These findings suggest that dysfunction of VIP receptors in muscles, in addition to loss of the neuronal VIP and NO pathways, are involved in abnormal motility in mouse colon with DSS-induced colitis.

Inflammation-induced changes in the chemical coding pattern of colon-projecting neurons in the inferior mesenteric ganglia of the pig

The present study examines the chemical coding of the inferior mesenteric ganglia after chemically induced colitis in the pig animal model. In all animals (n = 6), a median laparotomy was performed under anesthesia, and the Fast Blue retrograde tracer was injected into the descending colon wall. In experimental animals (n = 3), the thick descending colon were injected with formalin solution to induce inflammation. The animals were euthanized and the inferior mesenteric ganglion was harvested and processed for double-labeling immunofluorescence for calbindin-D28k (CB) in combination with either tyrosine hydroxylase (TH), neuropeptide Y (NPY), somatostatin (SOM), vasoactive intestinal polypeptide (VIP), nitric oxide synthase (NOS), Leu-enkephalin (LENK), substance P (SP), vesicular acetylcholine transporter (VAChT), or galanin (GAL). Immunohistochemistry revealed significant changes in the chemical coding pattern of inferior mesenteric ganglion neurons. In control animals, Fast Blue-positive neurons were immunoreactive to TH, NPY, SOM, VIP, LENK, CB, and NOS. In the experimental group, TH, NPY, SOM, VIP, and LENK expressing neurons were reduced, whereas the number of neurons immunoreactive to CB, NOS, and GAL were increased. The increase of so-called neuroprotective neuropeptides suggests that the changes in the chemical coding of inferior mesenteric ganglion neurons reflect adaption under pathological conditions to promote their own survival.

Distribution, organization and innervation of gastric MALT in conventional piglet

Mucosa-associated lymphoid tissue (MALT) is the initial inductive site for mucosal immunity. It is present in the different layers of the mucosal wall and consists of organized lymphoid tissue which may occur as isolated or aggregated lymphoid follicles (LFs) and interfollicular areas. It is present in many organs, including the pig stomach. Gastric MALT has been intensely studied in experimentally infected pigs but few data are available in healthy, non-gnotobiotic or germ-free animals. In the present study we described the gastric MALT in conventional piglets in the cardiac mucosa of the gastric diverticulum, in the pyloric mucosa, and in the sites of transition from cardiac to oxyntic and from cardiac to pyloric mucosa by means of histological and immunohistochemical stains. The majority of LFs were located in the cardiac mucosa and in the transition from the cardiac to the oxyntic mucosa. Here the LFs were mainly located in the submucosa and reached the mucosa; we called these submucosal lymphoid follicles (SLFs). In the pyloric mucosa and in the transition sites from the cardiac to the pyloric mucosa, LFs were located in the mucosa; we called these mucosal lymphoid follicles (MLFs). In SLFs, a compartmental organization of T and B lymphocytes was present; by contrast, in the MLFs, the T and B cells were intermingled, suggesting the possibility of different roles for the two types of follicles. In the epithelium overlying the lymphoid tissue, numerous T lymphocytes and some cells immunoreactive to cytokeratin-18 were observed. Following the application of the fluorescent tracer DiI into the SLFs of the diverticulum, enteric neurones located in the submucosal plexus were labelled, confirming the interplay between the immune and the enteric nervous system.

Toxoplasma gondii: myenteric neurons of intraperitoneally inoculated rats show quantitative and morphometric alterations

Several studies have demonstrated that the myenteric plexus experiences quantitative and morphometric changes in rats inoculated orally with Toxoplasma gondii. This paper aims to verify if these alterations are also seen when the same animals are inoculated intraperitoneally with the parasite. In order to do that, six Wistar rats (Rattus norvegicus) 60 days of age were infected intraperitoneally with 10(6) tachyzoites of a genotype I T. gondii strain (BTU IV). After 60 days, the animals were anaesthetised and underwent laparotomy. All organs from the small and large intestines were removed, measured, dissected and underwent whole-mount Giemsa technique to stain the neurons in the myenteric plexus. A quantitative and morphometric analysis of these cells was made, and it showed that the parasite causes the death of myenteric neurons in the jejunum and morphometric alterations in these cells throughout the intestine. However, the cellular response of myenteric neurons to T. gondii is heterogeneous compared the different organs from the gut.

Quantitative estimation and chemical coding of spiny type I neurons in human intestines

Previous studies have shown that most human myenteric neurons co-staining for vasoactive intestinal peptide (VIP), neuronal nitric oxide synthase (nNOS) and neurofilaments (NF) display the morphology of spiny type I neurons displaying a descending projection pattern. Here, we estimated the proportions of spiny neurons in human intestines, the amount of congruence of VIP/nNOS-immunoreactive with spiny neurons and whether galanin (GAL) is co-localized with VIP. Three sets of colchicine-pretreated and fixed whole mounts of 21 patients or body donors (median age 65 years; 10 female, 11 male) were stained for VIP, nNOS and NF, for VIP, nNOS and the human neuronal protein Hu C/D (HU) as well as for VIP, nNOS and GAL. The majority of VIP/nNOS-co-reactive neurons were spiny neurons (79/80% in small/large intestine, respectively) and the majority of spiny neurons co-stained for VIP and nNOS (82/69%). Neurons co-immunoreactive for VIP/nNOS/HU amounted to 7 and 4%, respectively. GAL/VIP-co-immunoreactivity was demonstrated in 69 and 27% of spiny neurons, respectively. We conclude that the number of neurons displaying co-reactivity for VIP and nNOS is a quantitative indicator of spiny neurons in both small and large intestine and that the proportion of spiny neurons is about 7% in small and 4% in large intestines. Since nerve fibres co-staining for NF/VIP/nNOS were found mainly in the circular muscle layer but not the surrounding perikarya of spiny neurons, we suggest that they may represent inhibitory motor neurons rather than descending interneurons.

Corticotropin releasing factor-distribution in rat intestine and role in neuroprotection

Aims of the present study were to describe the distribution of corticotropin releasing factor (CRF) immunoreactivity in rat small and large intestines, to quantify the percentage of CRF-immunoreactive (CRF-IR) enteric neurons, to reveal possible CRF immunoreactivity in cultured myenteric neurons from rat ileum and to examine if additions of CRF, urocortin 1 (Ucn1), CRF antagonist or vasoactive intestinal peptide (VIP) affect neuronal survival in vitro. Co-localization of CRF- and VIP-immunoreactivity was examined, as well as a possible interplay between CRF and VIP in neuroprotection. Further we wanted to elucidate if mast cells affect neuronal survival via CRF signaling. Networks of CRF-containing nerve cell bodies and fibers were detected in rat intestine. CRF-IR neurons contained to a high degree also VIP. A low number of cultured myenteric neurons was CRF-IR. CRF, Ucn1 or CRF-antagonist did not promote neuronal survival of cultured myenteric neurons, while VIP significantly enhanced neuronal survival. Simultaneous presence of CRF attenuated the VIP mediated increase in neuronal survival. Co-culturing neurons and mast cells resulted in a marked reduction in neuronal survival, not executed via CRF signaling pathways.

CONCLUSION

CRF is present in enteric neurons and counteracts the neuroprotective effect of VIP in vitro.

Quantitative and morphometric changes of subpopulations of myenteric neurons in swines with toxoplasmosis

The consequences of the infection caused by Toxoplasma gondii in myenteric neurons of the jejunum of swines reactive to NADH-diaphorase and NADPH-diaphorase were evaluated in this study. Ten 88-day-old mixed-breed swines (Pietrain and Wessex) were assigned into two groups: Control (n=5) and Experimental (n=5), which orally received 5000 sporulated oocysts from a genotype III T. gondii strain. After 30days, the animals were anesthetized, having part of their jejunum removed and stained with NADPH-diaphorase and NADH-diaphorase. NADPHd-p neurons (nitrergic) presented increase of the number of cells per ganglion and hypertrophy. The number of NADHd-p neurons (metabolic more active) and their nuclear area decreased.