A protocol for the induction of experimental necrotizing enterocolitis in neonatal mice.

Recapitulating human NEC using animal models has been insightful in dissecting the signaling pathways, immune-mediated mechanisms, genetic signatures, and the intestinal architecture of NEC. This protocol describes an in vivo murine NEC model, using hypoxia and formula containing lipopolysaccharide and enteric bacteria derived from an infant with NEC. With this mouse model, we aim to further dissect NEC pathogenesis and develop new therapeutic strategies. For complete details on the use and execution of this protocol, please refer to Mihi et al. (2021).

Cross-sectional imaging of intestinal barrier dysfunction by confocal laser endomicroscopy can identify patients with food allergy in vivo with high sensitivity.

Food allergy (FA) affects approximately 3 to 4% of the adult population in westernized countries. Suspected FA is even more prevalent and requires extensive diagnostic work-up. Within this study, we evaluated whether assessment of the integrity of the epithelial barrier by confocal laser endomicroscopy (CLE) during colonoscopy can be used as a screening tool to identify patients with FA. 60 patients with suspected FA were prospectively included. Serology with total and food-specific IgE, anti-tissue transglutaminase, skin prick testing, food intolerance tests, food intake registration and assessment of clinical complaints were performed. During colonocopy, standardized CLE was performed in the terminal ileum and at two colorectal sites. Analysis of CLE images included functional (i.e. presence of epithelial barrier dysfunction) and quantitative parameters of intestinal architecture. 27 of 60 patients (45%) were diagnosed with FA. Barrier dysfunction was analyzed on 65.837 ileal and on 93.251 colonic images. 96% of patients with FA exhibited functional and structural barrier defects while barrier dysfunction was found in only 33% of patients without FA (p < 0.0001). Visualizing barrier dysfunction with CLE for in vivo diagnosis of FA had a sensitivity and specificity of 96% and 67%, respectively, with a positive and negative prediction of 70% and 96%, respectively. Parameters intrinsic to the crypt architecture including crypt diameter, intercrypt distance, crypt lumen diameter and colonic vasculature were not different between patients with and without FA. CLE-based imaging of the intestinal barrier during colonoscopy might help in stratifying patients with suspected FA for further diagnostic work-up.

Differential Recovery of Small Intestinal Segments after Partial-Body Irradiation in Non-Human Primates.

In the event of a radiological attack or accident, it is more likely that the absorbed radiation dose will be heterogeneous, rather than uniformly distributed throughout the body. This type of uneven dose distribution is known as partial-body irradiation (PBI). Partial exposure of the vital organs, specifically the highly radiosensitive intestines, may cause death, if the injury is significant and the post-exposure recovery is considerably compromised. Here we investigated the recovery rate and extent of recovery from PBI-induced intestinal damage in large animals. Rhesus macaques (Macaca mulatta) were randomly divided into four groups: sham-irradiated (0 Gy), 8 Gy PBI, 11 Gy PBI and 14 Gy PBI. A single dose of ionizing radiation was delivered in the abdominal region using a uniform bilateral anteroposterior and posteroanterior technique. Irradiated animals were scheduled for euthanasia on days 10, 28 or 60 postirradiation, and sham-irradiated animals on day 60. Intestinal structural injuries were assessed via crypt depth, villus height, and mucosal surface length in the four different intestinal regions (duodenum, proximal jejunum, distal jejunum and ileum) using H&E staining. Higher radiation doses corresponded with more injury at 10 days post-PBI and a faster recovery rate. However, at 60 days post-PBI, damage was still evident in all regions of the intestine. The proximal and distal ends (duodenum and ileum, respectively) sustained less damage and recovered more fully than the jejunum.

Deoxycholic acid enhancement of lymphocyte migration through direct interaction with the intestinal vascular endothelium.

BACKGROUND AND AIM: The small intestine plays a central role in gut immunity, and enhanced lymphocyte migration is involved in the pathophysiology of various enteropathy. Bile acid (BA) is closely related to lipid metabolism and gut microbiota and essential for gut homeostasis. However, the effects of BA on gut immunity have not been studied in detail, especially on the small intestine and lymphocyte migration. Therefore, we aimed to investigate the effect of BA on small intestinal lymphocyte microcirculation. METHODS: The effect of deoxycholic acid (DCA), taurocholic acid (tCA), or cholic acid (CA) on the indomethacin (IND)-induced small intestinal enteropathy in mice was investigated. Lymphocyte movements were evaluated after exposure to BA using intravital microscopy. The effects of BA on surface expression of adhesion molecules on the vascular endothelium and lymphocytes through BA receptors were examined in vitro. RESULTS: IND-induced small intestinal enteropathy was histologically aggravated by DCA treatment alone. The expression of adhesion molecules ICAM-1 and VCAM-1 was significantly enhanced by DCA. Exposure to DCA increased lymphocyte adhesion in the microvessels of the ileum, which was partially blocked by anti-α4ß1 integrin antibody in vivo. The expression of ICAM-1 and VCAM-1 was significantly enhanced by DCA in vitro, which was partially suppressed by the sphingosine-1-phosphate receptor 2 (S1PR2) antagonist. The S1PR2 antagonist significantly ameliorated IND-induced and DCA-exaggerated small intestinal injury. CONCLUSION: DCA exacerbated IND-induced small intestinal enteropathy. DCA directly acts on the vascular endothelium and enhances the expression levels of adhesion molecules partially via S1PR2, leading to enhanced small intestinal lymphocyte migration.

Small intestine remodeling in male Goto-Kakizaki rats.

BACKGROUND: Obesity is associated with the development of insulin resistance (IR) and type-2 diabetes mellitus (T2DM); however, not all patients with T2DM are obese. The Goto-Kakizaki (GK) rat is an experimental model of spontaneous and non-obese T2DM. There is evidence that the intestine contributes to IR development in GK animals. This information prompted us to investigate small intestine remodeling in this animal model. METHODS: Four-month-old male Wistar (control) and GK rats were utilized for the present study. After removing the small intestine, the duodenum, proximal jejunum, and distal ileum were separated. We then measured villi and muscular and mucosa layer histomorphometry, goblet cells abundance, total myenteric and submucosal neuron populations, and inflammatory marker expression in the small intestinal segments and intestinal transit of both groups of animals. KEY RESULTS: We found that the GK rats exhibited decreased intestinal area (p < 0.0001), decreased crypt depth in the duodenum (p = 0.01) and ileum (p < 0.0001), increased crypt depth in the jejunum (p < 0.0001), longer villi in the jejunum and ileum (p < 0.0001), thicker villi in the duodenum (p < 0.01) and ileum (p < 0.0001), thicker muscular layers in the duodenum, jejunum, and ileum (p < 0.0001), increased IL-1ß concentrations in the duodenum and jejunum (p < 0.05), and increased concentrations of NF-κB p65 in the duodenum (p < 0.01), jejunum and ileum (p < 0.05). We observed high IL-1ß reactivity in the muscle layer, myenteric neurons, and glial cells of the experimental group. GK rats also exhibited a significant reduction in submucosal neuron density in the jejunum and ileum, ganglionic hypertrophy in all intestinal segments studied (p < 0.0001), and a slower intestinal transit (about 25%) compared to controls. CONCLUSIONS: The development of IR and T2DM in GK rats is associated with small intestine remodeling that includes marked alterations in small intestine morphology, local inflammation, and reduced intestinal transit.

Phosphorylated Tau protein in the myenteric plexus of the ileum and colon of normothermic rats and during synthetic torpor.

Tau protein is of primary importance for neuronal homeostasis and when hyperphosphorylated (PP-Tau), it tends to aggregate in neurofibrillary tangles, as is the case with tauopathies, a class of neurodegenerative disorders. Reversible PP-Tau accumulation occurs in the brain of hibernating rodents and it was recently observed in rats (a non-hibernator) during synthetic torpor (ST), a pharmacological-induced torpor-like condition. To date, the expression of PP-Tau in the rat enteric nervous system (ENS) is still unknown. The present study immunohistochemically investigates the PP-Tau expression in the myenteric plexus of the ileum and colon of normothermic rats (CTRL) and during ST, focusing on the two major subclasses of enteric neurons, i.e., cholinergic and nitrergic.Results showed that both groups of rats expressed PP-Tau, with a significantly increased percentage of PP-Tau immunoreactive (IR) neurons in ST vs. CTRL. In all rats, the majority of PP-Tau-IR neurons were cholinergic. In ST rats, the percentage of PP-Tau-IR neurons expressing a nitrergic phenotype increased, although with no significant differences between groups. In addition, the ileum of ST rats showed a significant decrease in the percentage of nitrergic neurons. In conclusion, our findings suggest an adaptive response of ENS to very low core body temperatures, with changes involving PP-tau expression in enteric neurons, especially the ileal nitrergic subpopulation. In addition, the high presence of PP-Tau in cholinergic neurons, specifically, is very interesting and deserves further investigation. Altogether, these data strengthen the hypothesis of a common cellular mechanism triggered by ST, natural hibernation and tauopathies occurring in ENS neurons.

Foodborne botulism presenting as small bowel obstruction: a case report.

BACKGROUND: Small bowel obstruction is one of the leading reasons for accessing to the Emergency Department. Food poisoning from Clostridium botulinum has emerged as a very rare potential cause of small bowel obstruction. The relevance of this case report regards the subtle onset of pathognomonic neurological symptoms, which can delay diagnosis and subsequent life-saving treatment. CASE PRESENTATION: A 24-year-old man came to our Emergency Department complaining of abdominal pain, fever and sporadic self-limiting episodes of diplopia, starting 4 days earlier. Clinical presentation and radiological imaging suggested a case of small bowel obstruction. Non-operative management was adopted, which was followed by worsening of neurological signs. On specifically questioning the patient, we discovered that his parents had experienced similar, but milder symptoms. The patient also recalled eating home-made preserves some days earlier. A clinical diagnosis of foodborne botulism was established and antitoxin was promptly administered with rapid clinical resolution. CONCLUSIONS: Though very rare, botulism can mimic small bowel obstruction, and could be associated with a rapid clinical deterioration if misdiagnosed. An accurate family history, frequent clinical reassessments and involvement of different specialists can guide to identify this unexpected diagnosis.

Lubeluzole: from anti-ischemic drug to preclinical antidiarrheal studies.

BACKGROUND: Lubeluzole, a neuroprotective anti-ischemic drug, was tested for its ability to act as both antibiotic chemosensitizing and antipropulsive agent for the treatment of infectious diarrhea. METHODS: In the present report, the effect of lubeluzole against antidiarrheal target was tested. The antimicrobial activity towards Gram-positive and Gram-negative bacteria was investigated together with its ability to affect ileum and colon contractility. RESULTS: Concerning the antimicrobial activity, lubeluzole showed synergistic effects when used in combination with minocycline against four common Gram-positive and Gram-negative bacteria (Enterococcus faecalis ATCC 29212, Staphylococcus aureus ATCC 29213, Pseudomonas aeruginosa ATCC 27853, and Escherichia coli ATCC 25922), although relatively high doses of lubeluzole were required. In ex vivo experiments on sections of gut smooth muscles, lubeluzole reduced the intestinal contractility in a dose-dependent manner, with greater effects observed on colon than on ileum, and being more potent than reference compounds otilonium bromide and loperamide. CONCLUSION: All above results identify lubeluzole as a possible starting compound for the development of a novel class of antibacterial adjuvants endowed with spasmolytic activity.

Quantified small bowel motility in patients with ulcerative colitis and gastrointestinal symptoms: a pilot study.

BACKGROUND: Gastrointestinal (GI) symptoms are common in patients with ulcerative colitis (UC), even when the disease is in remission, possibly due to abnormalities in GI motility. Small bowel motility can be assessed globally and in specific intestinal regions during magnetic resonance enterography (MRE) using a displacement mapping technique. PURPOSE: To investigate whether small bowel motility in MRE differs between patients with UC and controls, and if altered motility correlates with GI symptoms. MATERIAL AND METHODS: In 2016-2018, patients who were admitted for MRE, regardless of clinical indication, were consecutively invited to the study. Healthy volunteers were recruited. The participants completed a questionnaire regarding GI symptoms and relevant clinical data were reviewed in the medical records. The dynamic imaging series obtained during MRE were sent for motility mapping and a motility index (MI) was calculated in jejunum, ileum and terminal ileum in all participants. RESULTS: In total, 224 patients and healthy volunteers were enrolled in the study. Fifteen were diagnosed with UC and 22 were considered healthy controls. In UC, the prevalence of GI symptoms was higher than in controls (P < 0.001), both in remission and in active disease. There was no correlation between GI symptoms and small bowel motility in UC. Jejunal motility was lower in UC than in controls (P = 0.049). CONCLUSION: Jejunal motility is decreased in UC compared with healthy controls, but there is no relationship between small bowel motility and GI symptoms in UC.

Molecular Changes in the Non-Inflamed Terminal Ileum of Patients with Ulcerative Colitis.

Ulcerative colitis is a chronic inflammatory disease confined to the colon. Although the etiopathogenesis remains unknown, small bowel dysfunctions like histological and permeability alterations have been described in ulcerative colitis. We evaluated the molecular gene signature in the non-inflamed terminal ileum of 36 ulcerative colitis patients (7 active, with Mayo endoscopic subscore ≥2, and 29 inactive) as compared to 15 non-inflammatory bowel disease controls. Differential gene expression analysis with DESeq2 showed distinct expression patterns depending on disease activity and maximal disease extent. We found 84 dysregulated genes in patients with active extensive colitis and 20 in inactive extensive colitis, compared to controls. There was an overlap of 5 genes: REG1B, REG1A, MUC4, GRAMD2, and CASP10. In patients with left-sided colitis, ileal gene expression levels were similar to controls. Based on gene co-expression analysis, ileal changes in active ulcerative colitis patients were related to immune functions. The ileal changes in the inactive ulcerative colitis subjects converged into the maintenance of the intestinal barrier through increased mitochondrial function and dampened immune functions. In conclusion, we identified molecular changes in the non-inflamed ileum of ulcerative colitis that are dependent on colonic inflammation.

Volumetric analysis of small bowel motility in an unselected cohort of patients with Crohn's disease.

BACKGROUND: Quantified terminal ileal motility during magnetic resonance enterography (MRE) has been suggested to be used as a biomarker of Crohn's disease (CD). The aim of the present study was to evaluate this method in clinical practice. METHODS: Healthy volunteers and all consecutive patients referred to MRE during a 2-year period were asked to participate and complete the Irritable Bowel Syndrome-Symptom Severity Scale (IBS-SSS) to assess gastrointestinal symptoms. Medical records were scrutinized, and motility indices (MIs) were calculated from MR images. KEY RESULTS: Twenty-two healthy controls and 134 examinations with CD were included (inclusion rate: 76.3%). Patients with CD had increased mural thickness of the terminal ileum, increased fecal calprotectin, and more symptoms than controls. Patients with active CD had increased mural thickness of ileum and terminal ileum, higher MR activity indices, and signs of inflammation in laboratory analyses, but similar symptoms, compared with inactive disease. After exclusion of sole colon disease (n = 13), MI inversely correlated with mural thickness in terminal ileum, and MI was lower in active disease versus controls in ileum (P = .019) and terminal ileum (P = .005), and versus inactive disease in terminal ileum (P = .044). The area under the curve of MI in terminal ileum was 0.736 for active CD against healthy controls (P = .002) and 0.682 for active against inactive CD (P = .001). MIs were similar in controls and inactive CD. CONCLUSIONS AND INTERFERENCES: MI reflects inflammatory activity in the intestine. Alterations in MI did not explain symptomatology in inactive CD, without measurable inflammatory parameters in morphology or laboratory analyses.

Involvement of Enteric Glia in Small Intestine Neuromuscular Dysfunction of Toll-Like Receptor 4-Deficient Mice.

Enteric glial cells (EGCs) influence nitric oxide (NO)- and adenosine diphosphate (ADP)- mediated signaling in the enteric nervous system (ENS). Since Toll-like receptor 4 (TLR4) participates to EGC homoeostasis, this study aimed to evaluate the possible involvement of EGCs in the alterations of the inhibitory neurotransmission in TLR4-/- mice. Ileal segments from male TLR4-/- and wild-type (WT) C57BL/6J mice were incubated with the gliotoxin fluoroacetate (FA). Alterations in ENS morphology and neurochemical coding were investigated by immunohistochemistry whereas neuromuscular responses were determined by recording non-adrenergic non-cholinergic (NANC) relaxations in isometrically suspended isolated ileal preparations. TLR4-/- ileal segments showed increased iNOS immunoreactivity associated with enhanced NANC relaxation, mediated by iNOS-derived NO and sensitive to P2Y1 inhibition. Treatment with FA diminished iNOS immunoreactivity and partially abolished NO- and ADP- mediated relaxation in the TLR4-/- mouse ileum, with no changes of P2Y1 and connexin-43 immunofluorescence distribution in the ENS. After FA treatment, S100ß and GFAP immunoreactivity in TLR4-/- myenteric plexus was reduced to levels comparable to those observed in WT. Our findings show the involvement of EGCs in the alterations of ENS architecture and in the increased purinergic and nitrergic-mediated relaxation, determining gut dysmotility in TLR4-/- mice.

Castleman's disease presenting with mechanical intestinal obstruction: A rare case.

Castleman's disease (CD) is a lymphoproliferative disorder and the occurrence of CD in the small bowel is rare. In this study, we present one case of CD causing mechanical intestinal obstruction due to involvement of terminal ileum. A 50-year-old man was admitted to the hospital with signs and symptoms of mechanical intestinal obstruction without history previous surgery. After examination and obtaining abdominal computed tomography, diagnosis of mechanical intestinal obstruction was reached and emergency surgery was performed with a median incision. On abdominal exploration a tumor like mass that also held distal small intestine mesentery, and ileocecal valve causing complet intestinal obstruction was observed. Ileocecal resection and ileocolonic anastomosis were performed. CD is a rare entity and should be kept in mind during the differential diagnosis of mechanical intestinal obstruction provided that wall thickening in terminal ileum mimicking mass, and accompanying enlargement mesenteric lymph nodes observed during preoperative investigations or intraoperative exploration.

Proteomics Highlights Common and Distinct Pathophysiological Processes Associated with Ileal and Colonic Ulcers in Crohn's Disease.

BACKGROUND AND AIMS: Based on genetics and natural history, Crohn's disease can be separated into two entities, an ileal and a colonic disease. Protein-based approaches are needed to elucidate whether such subphenotypes are related to distinct pathophysiological processes. METHODS: The proteome of ulcer edges was compared with that of paired control tissue samples [n = 32 biopsies] by differential proteomics in the ileum and the colon of Crohn's disease patients [n = 16]. The results were analysed using a hypothesis-driven approach [based on the literature] and a hypothesis-free approach [pathway enrichment analyses] to determine common and segment-specific pathophysiological processes associated with ileal and colonic CD ulcer edges. To confirm the involvement of a key pathway highlighted by proteomics, two proteins were also studied by immunochemistry. RESULTS: In the ileum and the colon, 4428 and 5204 proteins, respectively, were identified and quantified. Ileal and colonic ulcer edges differed in having a distinct distribution of proteins associated with epithelial-mesenchymal transition, neutrophil degranulation, and ribosomes. Ileal and colonic ulcer edges were similarly characterized by an increase in the proteins implicated in the endoplasmic reticulum protein-processing pathway and a decrease in mitochondrial proteins. Immunochemistry confirmed the presence of endoplasmic reticulum stress in the mucosa of ileal and colonic ulcer edges. CONCLUSION: This study provides protein-based evidence for partially distinct pathophysiological processes being associated with ileal and colonic ulcer edges in Crohn's disease patients. This could constitute a first step toward the development of gut segment-specific diagnostic markers and therapeutics.

Burn-Induced Impairment of Ileal Muscle Contractility Is Associated with Increased Extracellular Matrix Components.

INTRODUCTION: Severe burns lead to marked impairment of gastrointestinal motility, such as delayed gastric emptying and small and large intestinal ileus. However, the cellular mechanism of these pathologic changes remains largely unknown. METHODS: Male Sprague Dawley rats approximately 3 months old and weighing 300-350 g were randomized to either a 60% total body surface area full-thickness scald burn or sham procedure and were sacrificed 24 h after the procedure. Gastric emptying, gastric antrum contractility ileal smooth muscle contractility, and colonic contractility were measured. Muscularis externa was isolated from the ileal segment to prepare smooth muscle protein extracts for Western blot analysis. RESULTS: Compared with sham controls, the baseline rhythmic contractile activities of the antral, ileal, and colonic smooth muscle strips were impaired in the burned rats. Simultaneously, our data showed that ileal muscularis ECM proteins fibronectin and laminin were significantly up-regulated in burned rats compared with sham rats. TGF-ß signaling is an important stimulating factor for ECM protein expression. Our results revealed that TGF-ß signaling was activated in the ileal muscle of burned rats evidenced by the activation of Smad2/3 expression and phosphorylation. In addition, the total and phosphorylated AKT, which is an important downstream factor of ECM signaling in smooth muscle cells, was also up-regulated in burned rats' ileal muscle. Notably, these changes were not seen in the colonic or gastric tissues. CONCLUSION: Deposition of fibrosis-related proteins after severe burn is contributors to decreased small intestinal motility.

Twice subacute MPTP administrations induced time-dependent dopaminergic neurodegeneration and inflammation in midbrain and ileum, as well as gut microbiota disorders in PD mice.

Parkinson's disease (PD) is a common progressive neurodegenerative disease. PD produces a pathological state in the intestine and disordered gut microbiota (GM), which may be important for the pathogenesis and progression of PD, but it is not clear. To explore the conditions and characteristics of intestinal pathology and GM disorders when PD-related injuries occur, we used twice 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) subacute administration with an interval of 3 weeks (each was an intraperitoneal injection of 25 mg/kg MPTP for 5 consecutive days). We observed the changes in intestinal and brain immune status, intestinal barrier function and GM in different injury states one day, one week, and three weeks after the first stimulus and one day and one week after the second stimulus. Our study found that two subacute administrations of MPTP induced dopaminergic (DAergic) neuron injury and inflammation in the midbrain and ileum, impaired intestinal barrier function and GM disorders closely related to administration. These changes recovered after the first administration, but after repeated administration, some indicators showed more dramatic changes than during the first administration. Our results suggest that the intestinal tract is sensitive to PD-related injury, and the GM is susceptible to disturbances caused by intestinal function, which may be concerned in local immune disorders of the intestine.

Studies on antidiarrheal and laxative activities of aqueous-ethanol extract of Asphodelus tenuifolius and underlying mechanisms.

BACKGROUND: Asphodelus tenuifolius Cav. (Asphodelaceae) has traditional reputability in treatment of diarrhea and constipation but no scientific study has been reported for its gastrointestinal effects. Present study was conducted to evaluate antidiarrheal and laxative activities of the plant. METHODS: Aqueous-ethanol crude extract of Asphodelus tenuifolius (At.Cr) was subjected to phytochemical screening and liquid-liquid fractionation. In vivo studies of charcoal meal intestinal transit test, antidiarrheal activity against castor oil induced diarrhea and laxative activity were performed in mice. In vitro experiments were conducted upon rabbit jejunum preparations using standard tissue bath techniques. RESULTS: Phytochemical screening indicated presence of alkaloids, anthraquinones, flavonoids, saponins, steroids, tannins and phenols in At.Cr. In charcoal meal intestinal transit test, At.Cr increased (p < 0.001) intestinal motility at 100 mg/kg dose, but decreased (p < 0.001) it at 500 mg/kg dose, when compared to the control group. At.Cr (300-700 mg/kg) provided protection from castor oil induced diarrhea in mice, which was significant (p < 0.001) at 500 and 700 mg/kg doses, as compared to the saline treated control group. At.Cr (50 and 100 mg/kg) enhanced total and wet feces counts in normal mice, as compared to saline treated control. In jejunum preparations, At.Cr inhibited spontaneous, K+ (80 mM) and K+ (25 mM) mediated contractions, similar to verapamil. Pre-incubation of jejunum preparations with At.Cr resulted in rightward nonparallel shift in Ca+ 2 concentration response curves, similar to verapamil. The spasmolytic activity was concentrated in ethylacetate fraction. Aqueous fraction exhibited spasmogenicity upon spontaneous contractions, which was blocked in presence of verapamil, but remained unaffected by other tested antagonists. CONCLUSION: The Asphodelus tenuifolius crude extract possesses gut modulatory activity, which may normalize gut functions in diarrhea and constipation. The spasmolytic activity of the extract was found to be mediated through Ca+ 2 channel blocking action. The spasmogenic activity, found partitioned in aqueous fraction, possibly involves Ca+ 2 influx through voltage gated Ca+ 2 channels. The study supports ethnic uses of the plant in diarrhea and constipation.

The protective effect of endothelin receptor antagonists against surgically induced impairment of gastrointestinal motility in rats.

Endothelin (ET) receptor antagonists: BQ-123 (ETA), BQ-788 (ETB), tezosentan (dual ET receptor antagonist) protect against the development of postoperative ileus (POI) evoked by ischemia-reperfusion (I/R). The current experiments explored whether ET antagonists prevent the occurrence of POI evoked by surgical gut manipulation. Intestinal transit was assessed by measuring the rate of dye migration subsequent to skin incision (SI), laparotomy (L), or laparotomy and surgical gut handling (L+M) in diethyl ether anaesthesized rats (E). Experimental animals were randomly sub-divided into two groups depending on the time of recovery following surgery: viz. either 2 or 24 h (early or late phase POI). E and SI did not affect the gastrointestinal (GI) transit. In contrast, L and L+M significantly reduced GI motility in comparison to untreated group (UN). Tezosentan (10 mg/kg), BQ-123 and BQ-788 (1 mg/kg) protected against development of L+M evoked inhibition of intestinal motility in the course of late phase, but not early phase POI. Furthermore, tezosentan alleviated the decrease in the contractile response of the longitudinal jejunal smooth muscle strips to carbachol in vitro induced by L+M. The serum ET(1-21) concentration was not increased in either the early or the late phase POI groups after surgery compared to control animals. This study indicates that delay in the intestinal transit in late phase of surgically induced POI involves an ET-dependent mechanism.

Clinicopathological study of intestinal smooth muscles, interstitial cells of Cajal, and enteric neurons in neonatal jejuno-ileal atresia with special reference to muscle morphometry.

PURPOSE: To assess the thickness of the intestinal smooth muscle layer and analyze the distribution and density of interstitial cells of Cajal (ICC) and enteric neurons in the proximal and distal segments of neonatal jejuno-ileal atresia. METHODS: This is an observational study done over a period of one year in which fifteen cases of jejuno-ileal atresia were included. All the cases underwent laparotomy and resection of the atretic segment with variable portions of the dilated proximal segment and distal segment. Histopathological analysis was done on the sections taken from proximal segments (at 3 cm, 5 cm & 8 cm) and the distal segment (at 2 cm) from the atretic portion. The mean thickness of the inner circular muscle layer (ICML) and outer longitudinal muscle layer (OLML) was assessed in the above segments using image morphometry. In addition, we also analyzed the distribution and density of the ICCs and enteric neurons in the different segments using immunohistochemistry for c-kit and S-100, respectively. Controls included normal jejuno-ileal segments resected from postmortem cases (n=7) and other nonrelated surgeries (n=3). The findings were then compared with each-other and with normal controls. RESULTS: Mean thickness of ICML and OLML of the proximal segments at 8 cm was significantly lower than at 3 cm and 5 cm of ileal and jejunal atresias (p≪ 0.5). The mean thickness of ICML and OLML of distal segments at 2 cm was similar to the controls in all the atretic cases (p≫ 0.5). The mean ICML thickness at proximal 8 cm segment was similar to the distal segment of both ileal & jejunal atresias (p= 0.06 & 0.37 respectively). The mean thickness of the OLML of the proximal 8 cm segments was significantly more than that at the distal segment (p=0.008) in ileal atresias but was similar in cases of jejunal atresias (p=0.07). Both the proximal and distal segments of ileal as well as jejunal atresias showed reduction in distribution and density of ICCs, as compared to normal controls. The density of ICCs in proximal segments at 3 cm and 5 cm was similar in both ileal (p=0.33) and jejunal segments (p=0.41) but was significantly lower than the proximal 8 cm segments (p≪0.05).The distribution of ICCs in the proximal segment at 8 cm was similar to the distal segments (p≪0.05). S-100 staining showed dense expression of neurons and glial cells with presence of submucosal giant ganglia within the proximal dilated segments as compared to the distal segments and the controls, which were more marked at 3 cm and 5 cm levels than at 8 cm level. CONCLUSION: Muscle morphometry using image analysis is a simple technique to assess the thickness of the intestinal smooth muscle layers. There is significant smooth muscle hypertrophy along with marked alteration in density and distribution of ICCs and ENS in the dilated proximal segments up to 5 cm, and relatively milder changes at 8 cm levels, as compared to the distal segments and the controls. TYPE OF STUDY: Prognosis study. LEVEL OF EVIDENCE: Level II.