Interstitial Cells Of Cajal Research Articles

Electromechanical Coupling and Anatomy of the In-Vivo Gastroduodenal Junction.

Few biomarkers support diagnosis and treatment of disorders of gut-brain interaction (DGBI), although gastroduodenal junction (GDJ) electromechanical coupling is a target for novel interventions. Rhythmic 'slow waves', generated by interstitial cells of Cajal (ICC), and myogenic 'spikes' are bioelectrical mechanisms underpinning motility. In this study, simultaneous in-vivo high-resolution electrophysiological and impedance planimetry measurements were paired with immunohistochemistry to elucidate GDJ electromechanical coupling. Following ethical approval, the GDJ of anaesthetized pigs (N=12) was exposed. Anatomically-specific, high-resolution electrode arrays (256 electrodes) were applied to the serosa. EndoFLIP catheters (16 electrodes; Medtronic, MN, USA) were positioned luminally to estimate diameter. Post-mortem tissue samples were stained with Masson's trichrome and Ano1 to quantify musculature and ICC. Electrical mapping captured slow-waves (N=512) and spikes (N=1071). Contractions paralleled electrical patterns. Localized slow waves and spikes preceded rhythmic contractions of the antrum, and non-rhythmic contractions of the duodenum. Slow-wave and spike amplitudes were correlated in the antrum (r=0.74, p<0.001) and duodenum (r=0.42, p<0.001). Slow-wave and contractile amplitudes were correlated in the antrum (r=0.48, p<0.001) and duodenum (r=0.35, p<0.001). Distinct longitudinal and circular muscle layers of the antrum and duodenum had a total thickness of (2.8 ± 0.9) mm and (0.4 ± 0.1) mm, respectively. At the pylorus, muscle layers merged and thickened to (3.5 ± 1.6) mm. Pyloric myenteric ICC covered less area (1.5 ± 1.1 %) compared to the antrum (4.2 ± 3.0 %) and duodenum (5.3 ± 2.8 %). Further characterization of electromechanical coupling and ICC biopsies may generate DGBI biomarkers.

Interstitial cell of Cajal-like cells (ICC-LC) exhibit dynamic spontaneous activity but are not functionally innervated in mouse urethra

Urethral smooth muscle cells (USMC) contract to occlude the internal urethral sphincter during bladder filling. Interstitial cells also exist in urethral smooth muscles and are hypothesized to influence USMC behaviours and neural responses. These cells are similar to Kit+ interstitial cells of Cajal (ICC), which are gastrointestinal pacemakers and neuroeffectors. Isolated urethral ICC-like cells (ICC-LC) exhibit spontaneous intracellular Ca2+ signalling behaviours that suggest these cells may serve as pacemakers or neuromodulators similar to ICC in the gut, although observation and direct stimulation of ICC-LC within intact urethral tissues is lacking. We used mice with cell-specific expression of the Ca2+ indicator, GCaMP6f, driven off the endogenous promoter for Kit (Kit-GCaMP6f mice) to identify ICC-LC in situ within urethra muscles and to characterize spontaneous and nerve-evoked Ca2+ signalling. ICC-LC generated Ca2+ waves spontaneously that propagated on average 40.1 ± 0.7 μm, with varying amplitudes, durations, and spatial spread. These events originated from multiple firing sites in cells and the activity between sites was not coordinated. ICC-LC in urethra formed clusters but not interconnected networks. No evidence for entrainment of Ca2+ signalling between ICC-LC was obtained. Ca2+ events in ICC-LC were unaffected by nifedipine but were abolished by cyclopiazonic acid and decreased by an antagonist of Orai Ca2+ channels (GSK-7975A). Phenylephrine increased Ca2+ event frequency but a nitric oxide donor (DEA-NONOate) had no effect. Electrical field stimulation (EFS, 10 Hz) of intrinsic nerves, which evoked contractions of urethral rings and increased Ca2+ event firing in USMC, failed to evoke responses in ICC-LC. Our data suggest that urethral ICC-LC are spontaneously active but are not regulated by autonomic neurons.

Neoadjuvant Imatinib in Gastrointestinal Stromal Tumors (GIST): The First Analysis of a Mexican Population.

Introduction Gastrointestinal stromal tumors (GISTs) are neoplasms originating from the interstitial cells of Cajal, pacemaker cells responsible for intestinal motility. Patients with locally advanced GISTs and those with borderline resections due to the proximity of vital anatomical structures, which could result in unacceptable post-surgical morbidity, require special therapeutic consideration. Imatinib, a tyrosine kinase inhibitor, has demonstrated significant successin the non-surgical management of metastatic GIST, and its favorable impact on overall survival in the adjuvant setting makes it logical to speculate on the benefit it could provide as a neoadjuvant medication in patients with locally advanced disease. Methods Patients aged 18-90 years with a diagnosis of GIST confirmed by immunohistochemistry (CD117 positivity) who were treated at the Oncology Hospital of Centro Médico Nacional Siglo XXI in Mexico City from January 2012 to December 2016 were included in the study. It is a retrospective study with a duration of four years. Clinical data were collected from the medical records, which included sex, age, tumor location, initial resectability, reason for unresectability, initial tumor size, and mitotic rate. In the case of unresectable disease, patients who were evaluated by medical oncology and who had received treatment with 400 mg of imatinib daily were evaluated. Results A total of 312 patients diagnosed with GIST were analyzed. One hundred thirty-one were men (42%) with a mean age of 57 years, and 181 were women (58%) with a mean age of 59 years. The most frequent anatomical location was the stomach (n=185, 59.2%). At the time of diagnosis, 210 patients (67.3%) presented with resectable disease, while n=102 patients (32.7%) had unresectable disease. A total of 102 patients with unresectable disease received therapy with 400 mg of imatinib per day. Sixteen patients (15.7%) presented a reduction in tumor dimensions and underwent surgery. Conclusion The study highlights the importance of complete surgical resection and the potential benefit of neoadjuvant imatinib therapy in converting unresectable to resectable disease. The results suggest that imatinib can be effective in converting unresectable GISTs to resectable ones, allowing for a complete resection to be performed and obtaining an R0 resection in 93.7% of these cases.

Ameliorative effects of the mixed aqueous extract of Aurantii Fructus Immaturus and Magnoliae Officinalis Cortex on loperamide-induced STC mice

Aurantii fructus immaturus (AFI) and Magnoliae Officinalis Cortex (MOC) have been used to treat constipation in China for thousands of years. In this study, a mouse model of slow transit constipation (STC) was established by gavage of loperamide at a dose of 10 mg/kg bw/day for seven days. Seventy-two mice were randomly allocated to six groups (control, STC model, 3 g/kg AFI + MOC, 6 g/kg AFI + MOC, 12 g/kg AFI + MOC, and mosapride). A mixed aqueous extract of AFI and MOC was administered to the STC mice at the corresponding doses from the first day of modelling. Body weight, faecal water content, gastrointestinal transit time, and intestinal propulsion rate were evaluated. Serum levels of neurotransmitters and gastrointestinal hormones, colonic expression of aquaporins (AQP), and interstitial cells of Cajal (ICC) were assessed using ELISA, immunohistochemistry, and Western blot analysis. The abundance and diversity of the gut microbiota were analysed by 16S rRNA gene sequencing. The mixed aqueous extract significantly increased faecal water content and intestinal propulsion rate and shortened gastrointestinal transit time in STC mice. Furthermore, the administration of AFI and MOC significantly decreased serum vasoactive intestinal peptide (VIP), nitric oxide (NO), and somatostatin (SS) levels and increased serum motilin (MTL) levels in STC mice. The protein expression levels of AQP3 and AQP4 in the colon tissue of STC mice significantly decreased following AFI + MOC treatment, whereas those of AQP9 significantly increased. Moreover, the AFI + MOC treatment led to an increase in the number and functionality of ICCs. In addition, the relative abundances of Ruminococcus and Oscillospira increased in response to the administration of AFI + MOC in STC mice. In conclusion, the mixed aqueous extract of AFI and MOC promoted defaecation and increased intestinal mobility in STC mice. Its mechanisms of action involve modulatory effects on neurotransmitters, gastrointestinal hormones, AQPs, and ICCs. AFI + MOC treatment also improved the diversity and abundance of the gut microbiota in STC mice, particularly short-chain fatty acid-producing bacteria, which may play an important role in its beneficial effect on constipation.

Gastro Intestinal Stromal Tumor: Cases Series Report

Gastrointestinal stromal tumors (GISTs) are rare mesenchymal tumors of the alimentary tract. Now a day GISTs represents 0.1-3% of all gastrointestinal malignancies, making it a diagnostic challenge. Lesions are frequently located in stomach and proximal small intestine but rarely elsewhere in the abdomen. They are believed to result from mutations of protooncogenes c-Kit or platelet-derived growth factor receptor alpha polypeptide, this increase tyrosine kinase receptor activity, leading to uncontrolled proliferation of stem cells that differentiate into cells of Cajal. They can occur at any age but predominantly in middle-aged people and in elderly. We reported the cases presented to our hospital with progressively distension of the abdomen, finding in diagnostic image suggested GIST without evidence of metastasis disease, total excision was done, Cytologic and immunohistochemistry analysis confirm diagnosis of GISTs.

Quantitative MRI approach in the preoperative evaluation of a rare large-mass abdominal GIST tumor

Gastrointestinal stromal tumors (GISTs) are rare cancers originating from the gastrointestinal tract's interstitial cells of Cajal. This study explores the utility of quantitative Magnetic Resonance Imaging (MRI), particularly volumetric lesion segmentation, in the preoperative evaluation of large-mass abdominal GISTs. MRI offers high-resolution imaging without ionizing radiation, which is crucial for oncology patients requiring repeated scans. Advanced semi-automatic segmentation techniques were employed in this study from different MRI sequences to enhance precision in tumor boundary delineation and volumetric analysis, and aid personalized surgical planning. In addition, this study demonstrates that using different clinical imaging protocols and comparing volumetric data from CT and various MRI sequences yields consistent results with minimal volumetric error. Finally, integrating MRI data into real-time surgical navigation systems underscored the synergy between radiology, surgical oncology, and computer science, improving tumor margin assessment and reducing recurrence risk. This approach highlights a pivotal shift towards technology-enhanced healthcare, promising better patient outcomes.

A Rare Case Of Early Gastrointestinal Stromal Tumor In 34-Year-Old Woman: A Caution For Adnexal Tumor Mimicry

Introduction: Gastrointestinal Stromal Tumors (GISTs) are the leading type of mesenchymal tumor in the gastrointestinal (GI) tract, constituting 80% of these tumors and 0.1% to 3% of all gastrointestinal malignancies. They arise from spindle-shaped mesenchymal cells known as interstitial cells of Cajal. Its onset can be at any age, with the peak occurring in the sixth decade. Case Presentation: We report the case of a 34-year-old woman with a complaint about a lump in her lower abdomen that has been progressively enlarging over the past year without any significant symptoms following the lump. Findings in the ultrasound suggest an ovarian mass. Laparotomy was carried out, and while no ovarian mass was found, instead a mass was identified in the mesentery of the small bowel. As a result, a complete excision of the tumor was performed, with histopathologic and immunohistochemical results confirming a GIST diagnosis. Conclusion: Representing a tiny percentage of gastrointestinal tumors, GISTs are rare. GISTs may be asymptomatic or present without any typical symptoms. Sole reliance on clinical and radiological investigations can cause them to be easily overlooked. Awareness of GIST is critical and care must be taken in diagnosis since other tumor can mimic GISTs in endoscopic, imaging, and histological findings.

Immunohistochemical characterization of interstitial cells and their relationship to motor neurons within the mouse esophagus.

Interstitial cells of Cajal (ICC) and PDGFRα+ cells regulate smooth muscle motility in the gastrointestinal (GI) tract. However, their role(s) in esophageal motility are still unclear. The mouse esophagus has traditionally been described as almost entirely skeletal muscle in nature though ICC have been identified along its entire length. The current study evaluated the distribution of skeletal and smooth muscle within the esophagus using a mouse selectively expressing eGFP in smooth muscle cells (SMCs). The relationship of SMCs to ICC and PDGFRα+ cells was also examined. SMCs declined in density in the oral direction however SMCs represented ~ 25% of the area in the distal esophagus suggesting a likeness to the transition zone observed in humans. ANO1+ intramuscular ICC (ICC-IM) were distributed along the length of the esophagus though like SMCs, declined proximally. ICC-IM were closely associated with SMCs but were also found in regions devoid of SMCs. Intramuscular and submucosal PDGFRα+ cells were densely distributed throughout the esophagus though only intramuscular PDGFRα+ cells within the LES and distal esophagus highly expressed SK3. ICC-IM and PDGFRα+ cells were closely associated with nNOS+, VIP+, VAChT+ and TH+ neurons throughout the LES and distal esophagus. GFAP+ cells resembling intramuscular enteric glia were observed within the muscle and were closely associated with ICC-IM and PDGFRα+ cells, occupying a similar location to c. These data suggest that the mouse esophagus is more similar to the human than thought previously and thus set the foundation for future functional and molecular studies using transgenic mice.

Modulation of intracellular calcium activity in interstitial cells of Cajal by inhibitory neural pathways within the internal anal sphincter.

The internal anal sphincter (IAS) functions to maintain continence. Previous studies utilizing mice with cell-specific expression of GCaMP6f revealed two distinct subtypes of intramuscular interstitial cells of Cajal (ICC-IM) with differing Ca2+ activities in the IAS. The present study further examined Ca2+ activity in ICC-IM and its modulation by inhibitory neurotransmission. The spatiotemporal properties of Ca2+ transients in Type II ICC-IM mimicked those of smooth muscle cells (SMCs), indicating their joint participation in the "SIP" syncytium. Electrical field stimulation (EFS; atropine present) abolished localized and whole cell Ca2+ transients in Type I and II ICC-IM. The purinergic antagonist MRS2500 did not abolish EFS responses in either cell type, whereas the nitric oxide synthase (NOS) inhibitor NG-nitro-l-arginine (l-NNA) abolished responses in Type I but not Type II ICC-IM. Combined antagonists abolished EFS responses in Type II ICC-IM. In both ICC-IM subtypes, the ability of EFS to inhibit Ca2+ release was abolished by l-NNA but not MRS2500, suggesting that the nitrergic pathway directly inhibits ICC-IM by blocking Ca2+ release from intracellular stores. Since inositol (1,4,5)-trisphosphate receptor-associated cGMP kinase substrate I (IRAG1) is expressed in ICC-IM, it is possible that it participates in the inhibition of Ca2+ release by nitric oxide. Platelet-derived growth factor receptor α (PDGFRα)+ cells but not ICC-IM expressed P2Y1 receptors (P2Y1R) and small-conductance Ca2+-activated K+ channels (SK3), suggesting that the purinergic pathway indirectly blocks whole cell Ca2+ transients in Type II ICC-IM via PDGFRα+ cells. This study provides the first direct evidence for functional coupling between inhibitory motor neurons and ICC-IM subtypes in the IAS, with contractile inhibition ultimately dependent upon electrical coupling between SMCs, ICC, and PDGFRα+ cells via the SIP syncytium.NEW & NOTEWORTHY Two intramuscular interstitial cells of Cajal (ICC-IM) subtypes exist within the internal anal sphincter (IAS). This study provides the first evidence for direct coupling between nitrergic motor neurons and both ICC-IM subtypes as well as indirect coupling between purinergic inputs and Type II ICC-IM. The spatiotemporal properties of whole cell Ca2+ transients in Type II ICC-IM mimic those of smooth muscle cells (SMCs), suggesting that ICC-IM modulate the activity of SMCs via their joint participation in a SIP syncytium (SMCs, ICC, and PDGFRα+ cells).

Addressing the Gap: Racial Disparities and Public Health Strategies in the Epidemiology of Gastrointestinal Stromal Tumors.

Background Gastrointestinal stromal tumors (GISTs) represent the most common mesenchymal neoplasms of the gastrointestinal tract, arising from the interstitial cells of Cajal. These tumors bridge the nervous system and muscular layers of the gastrointestinal tract, playing a crucial role in the digestive process. The incidence of GISTs demonstrates notable variations across different racial and ethnic groups, underscoring the need for in-depth analysis to understand the interplay of genetic, environmental, and socioeconomic factors behind these disparities. Linear regression analysis is a pivotal statistical tool in such epidemiological studies, offering insights into the temporal dynamics of disease incidence and the impact of public health interventions. Methodology This investigation employed a detailed dataset from 2009 to 2020, documenting GIST incidences across Asian, African American, Hispanic, and White populations. A meticulous preprocessing routine prepared the dataset for analysis, which involved data cleaning, normalization of racial terminologies, and aggregation by year and race. Linear regression models and Pearson correlation coefficients were applied to analyze trends and correlations in GIST incidences across the different racial groups, emphasizing an understanding of temporal patterns and racial disparities in disease incidence. Results The study analyzed GIST cases among four racial groups, revealing a male predominance (53.19%) and an even distribution of cases across racial categories: Whites (27.66%), Hispanics (25.53%), African Americans (24.47%), and Asians (22.34%). Hypertension was the most common comorbidity (32.98%), followed by heart failure (28.72%). The linear regression analysis for Asians showed a decreasing trend in GIST incidences with a slope of -0.576, an R-squared value of 0.717, and a non-significant p-value of 0.153. A significant increasing trend was observed for Whites, with a slope of 0.581, an R-squared value of 0.971, and a p-value of 0.002. African Americans exhibited a moderate positive slope of 0.277 with an R-squared value of 0.470 and a p-value of 0.201, indicating a non-significant increase. Hispanics showed negligible change over time with a slope of -0.095, an R-squared value of 0.009, and a p-value of 0.879, suggesting no significant trend. Conclusions This study examines GIST incidences across racial groups, revealing significant disparities. Whites show an increasing trend (p = 0.002), while Asians display a decreasing trend (p = 0.153), with stable rates in African Americans and Hispanics. Such disparities suggest a complex interplay of genetics, environment, and socioeconomic factors, highlighting the need for targeted research and interventions that address these differences and the systemic inequalities influencing GIST outcomes.

Effects of Saikosaponin D on Apoptosis, Autophagy, and Morphological Structure of Intestinal Cells of Cajal with Functional Dyspepsia.

Functional dyspepsia (FD) is one of the most common gastrointestinal diseases, with a global prevalence of 10%-30%. However, the specific pathogenesis of FD has not yet been determined. As such, the aim of this study was to investigate the effects of saikosaponin D (SSD) administration on the apoptosis, autophagy, and morphological structure of the intestinal cells of Cajal (ICCs) in FD. A rat model of FD was constructed by stimulating the rat tail with a sponge clamp at one-third of the distal tail length. An autophagy model was constructed for ICCs using glutamate. The apoptosis rate in each group of cells was determined using flow cytometry. The expressions of ghrelin and substance P (SP) were detected using ELISA. The body weight and food intake of male and female rats in the SSD group were consistently higher than those in the model group. The SSD group showed substantial improvement compared with the model group, with no inflammatory cell infiltration and normal gastric mucosal structures. After intervention with SSD, the ultrastructure of the ICCs considerably improved and was clear. Compared with the model group, the expressions of LC3 I/II, ghrelin, and SP proteins in the SSD group were significantly upregulated, and the apoptosis rate was significantly reduced. The administration of SSD improved ICC morphology and structure, inhibited excessive autophagy, and improved FD, a gastrointestinal motility disorder, by regulating ghrelin and SP levels.

A bibliometric analysis of interstitial cells of Cajal research.

The significance of interstitial cells of Cajal (ICC) in the gastrointestinal tract has garnered increasing attention. In recent years, approximately 80 articles on ICC have been published annually in various journals. However, no bibliometric study has specifically focused on the literature related to ICC. Therefore, we conducted a comprehensive bibliometric analysis of ICC to reveal dynamic scientific developments, assisting researchers in exploring hotspots and emerging trends while gaining a global perspective. We conducted a literature search in the Web of Science Core Collection (WoSCC) from January 1, 2013, to December 31, 2023, to identify relevant literature on ICC. We employed bibliometric software, namely VOSviewer and CiteSpace, to analyze various aspects including annual publication output, collaborations, research hotspots, current status, and development trends in this domain. A total of 891 English papers were published in 359 journals by 928 institutions from 57 countries/regions. According to the keyword analysis of the literature, researchers mainly focused on "c-Kit," "expression," "smooth muscle," and "nitric oxide" related to ICC over the past 11 years. However, with "SIP syncytium," "ANO1," "enteric neurons," "gastrointestinal stromal tumors (GIST)," and "functional dyspepsia (FD)," there has been a growing interest in the relationship between ANO1, SIP syncytium, and ICC, as well as the role of ICC in the treatment of GIST and FD. Bibliometric analysis has revealed the current status of ICC research. The association between ANO1, SIP syncytium, enteric neurons and ICC, as well as the role of ICC in the treatment of GIST versus FD has become the focus of current research. However, further research and collaboration on a global scale are still needed. Our analysis is particularly valuable to researchers in gastroenterology, oncology, and cell biology, providing insights that can guide future research directions.

Isolation of Myenteric and Submucosal Plexus from Mouse Gastrointestinal Tract and Subsequent Co-Culture with Small Intestinal Organoids.

Intestinal homeostasis results from the proper interplay among epithelial cells, the enteric nervous system (ENS), interstitial cells of Cajal (ICCs), smooth muscle cells, the immune system, and the microbiota. The disruption of this balance underpins the onset of gastrointestinal-related diseases. The scarcity of models replicating the intricate interplay between the ENS and the intestinal epithelium highlights the imperative for developing novel methods. We have pioneered a sophisticated tridimensional in vitro technique, coculturing small intestinal organoids with myenteric and submucosal neurons. Notably, we have made significant advances in (1) refining the isolation technique for culturing the myenteric plexus, (2) enhancing the isolation of the submucosal plexus-both yielding mixed cultures of enteric neurons and glial cells from both plexuses, and (3) subsequently co-culturing myenteric and submucosal neurons with small intestinal organoids. This co-culture system establishes neural innervations with intestinal organoids, allowing for the investigation of regulatory interactions in the context of gastrointestinal diseases. Furthermore, we have developed a method for microinjecting the luminal space of small intestinal organoids with fluorescently labeled compounds. This technique possesses broad applicability such as the assessment of intestinal permeability, transcytosis, and immunocytochemical and immunofluorescence applications. This microinjection method could be extended to alternative experimental setups, incorporating bacterial species, or applying treatments to study ENS-small intestinal epithelium interactions. Therefore, this technique serves as a valuable tool for evaluating the intricate interplay between neuronal and intestinal epithelial cells (IECs) and shows great potential for drug screening, gene editing, the development of novel therapies, the modeling of infectious diseases, and significant advances in regenerative medicine. The co-culture establishment process spans twelve days, making it a powerful asset for comprehensive research in this critical field.

Secretin Inhibits Small Intestinal Motility via Interstitial Cells of Cajal and cAMP Mechanisms

Background: Secretin is a member of the secretin-glucagon-vasoactive intestinal peptide hormone superfamily and is a multifunctional gastrointestinal- (GI) and neuro- peptide hormone. Secretin is primarily secreted postprandially from the crypts of Lieberkühn of duodenal enteroendocrine S cells into circulation where it reaches secretin receptor targets in the central nervous system and periphery. This dynamic hormone has been shown to act as a key signaling molecule in the regulation of digestion, metabolism and energy expenditure, water retention, reproduction, thermogenesis in adipose tissue, and in gastric and intestinal motility. Secretin’s canonical role in the GI tract is to stimulate the secretion of bicarbonate and bile from pancreatic ducts and bile ducts to neutralize acidic chyme exiting the stomach. Secretin has also been shown to slow intestinal motility, but its targets and mechanism of action is poorly understood. Aims: Several studies have proposed that secretin acts to slow intestinal motility in the intestines primarily through the many secretin receptors present on vagal afferents in the GI tract, here we discuss new data that suggests an alternate and complementary signaling pathway via interstitial cells of Cajal (ICC). ICC act as a liaison to facilitate a reduction in force of GI smooth muscle contraction through the activation of the secretin receptor (SCTR) and subsequent stimulation of the second messenger, cyclic adenosine monophosphate (cAMP). Here we provide evidence to show how ICC mediates changes in myogenic activity and motility in the small intestine. Methods: Spinning-disk confocal microscopy was used to monitor Ca2+ signaling in ICC from small intestinal muscles of GCaMP6f x KitiCre mice. Additionally, cAMP levels were evaluated using CAMPER mice. Intestinal muscle contractility was assessed using muscle strip myography experiments. Results: Secretin reduced small intestinal force of contraction in the presence of tetrodotoxin (TTX) and dampened the effect of cholinergic transmission. The secretin receptor (SCTR) is expressed primarily on ICC, specifically ICC within the deep muscular plexus (ICC-DMP) in the small intestine and Ca2+ imaging confirmed the effects are primarily localized within ICC-DMP. Secretin reduced carbachol-induced contractions and Ca2+ transients in ICC-DMP in response to electrical field stimulation (EFS) in the presence of LNNA (NO synthase inhibitor) and MRS2500 (P2Y1 antagonist). Secretin caused an increase in cAMP levels in ICC-DMP in muscles from Kit-iCre-CAMPER mice. PKA inhibitors rescued some of the effects of secretin on ICC-DMP Ca2+ signaling. Measurements of diameter change in large, intact, intestinal segments (4-5 cm) showed a significant decrease in response to Secretin. Conclusions: Secretin can inhibit small intestinal motility through the activation SCTRs on ICC-DMP via cAMP-mediated mechanisms. These results show how novel secretin targets on ICC influence GI muscles and reduce propulsive and segmental motility to facilitate nutrient absorption and digestion after a meal. Funding: This project was supported by R01 DK-120759 from the National Institute of Diabetes and digestive and Kidney (NIDDK). This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Distribution of interstitial cells within the mouse esophagus and their spatial relationship to enteric neurons

Background/Objectives: The esophagus is a conduit for the passage of ingested material into the stomach. In humans, it is divided into thirds; the proximal portion is composed of skeletal muscle, the distal is composed of smooth muscle and the middle is a transition zone between skeletal and smooth muscles. In other species such as the mouse, the esophagus has been described to consist entirely of skeletal muscle. Despite this, interstitial cells of Cajal (ICC), cells that regulate gastrointestinal (GI) smooth muscle contractility, have been identified throughout the mouse esophageal body (Rumessen et al., 2001; PMID:11683170). Additional studies in the human esophagus have identified another interstitial cell type, PDGFRa+ cells (Chen et al., 2013; PMID:23734090). However, the distribution of interstitial cells, motor and sensory neurons and their spatial relationship to one another have never been examined. Since interstitial cells modulate contractility of smooth muscle in other GI regions, the presence of these cells leads to the hypothesis that the mouse esophagus also contains smooth muscle cells (SMCs). Therefore, the aims of our study were to 1) determine if SMCs are found within the mouse esophagus, 2) characterize the distribution of ICC and PDGFRa+ cells, and 3) examine the relationship of interstitial cells to enteric motor and sensory neurons. Methods: Wildtype (C57Bl/6) and smooth muscle eGFP (smMHC-eGFP) mouse esophagus was used for dual labeling immunohistochemistry. ICC were labeled with antibodies against Kit or ANO1. PDGFRa+ cells were labeled with antibodies against PDGFRa or SK3. Extrinsic sympathetic neurons were labeled with tyrosine hydroxylase (TH). Motor neurons were labeled with antibodies against NOS, VIP (inhibitory) and vChAT (excitatory). Sensory neurons were labeled with CGRP. Images were taken with a Leica Stellaris 5 confocal microscope and processed using LasX software. Results: SMCs were found throughout the length of the esophagus, although their density declined proximally. Intramuscular ICC expressed ANO1 and were distributed throughout the length of the esophagus with the greatest density in the gastroesophageal junction (GEJ). Submucosal and intramuscular PDGFRa+ cells were distributed throughout the esophagus and GEJ. Intramuscular PDGFRa+ cells expressed SK3 though this expression declined proximally. SMCs, intramuscular ICC and PDGFRa+ cells were closely associated with one another as well as with neurons. Discussion/Conclusions: This study is the first to systematically characterize SMCs, ICC, PDGFRa+ cells and neurons in the mouse esophagus. These findings suggest that the mouse may represent a better translational model for studying esophageal motility than previously assumed. NIH DK129528 and P20GM130459. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Preventive effect of kiwi berry (Actinidia arguta) on loperamide-induced constipation

Constipation is a common intestinal disease. Kiwi berries can effectively prevent constipation. However, studies have yet to be done to determine how kiwi berries prevent constipation. For 2 weeks, mice in this study were continually orally gavaged with kiwi berry, loperamide, or a combination of the two. This study found that the kiwi group's feces had more water than the constipated mice. In addition, kiwi berries can speed up gastrointestinal transit (GI), shorten the time it takes to pass the first dark stool, and dramatically enhance body weight gain. In the interstitial cells of Cajal (ICC) cells and colon tissues, alterations in the protein expression of vasoactive intestinal peptide (VIP), cyclic adenosine monophosphate (cAMP), protein kinase A (PKA), and aquaporin-3 (AQP3) were found. At 3, 6, and 12 h of ICC cells and mouse colon, the kiwi group’s VIP, cAMP, PKA, and AQP3 protein expression levels were lower than those of the constipated mice. The kiwi berry can decrease the Firmicutes to Bacteroidetes ratio and boost the diversity and quantity of gut microbiota. By influencing the gut microbiota and VIP-cAMP-PKA-AQP3 signaling pathway, kiwi berries prevent constipation.

Common Pathophysiological Mechanisms and Treatment of Diabetic Gastroparesis.

Diabetic gastroparesis (DGP) is a common complication of diabetes mellitus, marked by gastrointestinal motility disorder, a delayed gastric emptying present in the absence of mechanical obstruction. Clinical manifestations include postprandial fullness and epigastric discomfort, bloating, nausea, and vomiting. DGP may significantly affect the quality of life and productivity of patients. Research on the relationship between gastrointestinal dynamics and DGP has received much attention because of the increasing prevalence of DGP. Gastrointestinal motility disorders are closely related to a variety of factors including the absence and destruction of interstitial cells of Cajal, abnormalities in the neuro-endocrine system and hormone levels. Therefore, this study will review recent literature on the mechanisms of DGP and gastrointestinal motility disorders as well as the development of prokinetic treatment of gastrointestinal motility disorders in order to give future research directions and identify treatment strategies for DGP.

Interstitial Cells of Cajal and P2X3 Receptors at Ureteropelvic Junction Obstruction and Their Relationship with Pain Response.

Introduction: Etiopathogenesis and the symptomatology of ureteropelvic junction obstruction (UPJO) in the pediatric population has not yet been definitely clarified, suggesting a multifactorial nature of the condition. The aim was to analyze the association between the number of Interstitial Cells of Cajal (ICCs), as well as P2X3 receptors in ureteropelvic junction (UPJ) and the pain response in pediatric patients with hydronephrosis. Methods: 50 patients with congenital hydronephrosis underwent open or laparoscopic pyeloplasty at one of two departments of pediatric surgery and urology in Poland. Patients were divided into two groups according to the pain symptoms before surgery. A total of 50 samples of UPJ were obtained intraoperatively and underwent histopathological and immunohistochemical (IHC) analysis. Quantitative assessment of ICCs was based on the number of CD117(+) cells of adequate morphology in the subepithelial layer and the muscularis propria. Expression of P2X3 receptors was evaluated as the intensity of IHC staining. Results: Patients with hydronephrosis and accompanying pain were on average 60 months older (77 vs. 17 months) than children with asymptomatic hydronephrosis (p = 0.017). Symptomatic children revealed higher numbers of ICCs in both the subepithelial layer and in the lamina muscularis propria. In particular, symptomatic patients aged 2 years or more exhibited significantly higher numbers of ICCs in the subepithelial layer. Significant differences in the distribution of ICCs between the subepithelial layer and the lamina muscularis propria were observed in both groups. Expression of P2X3 receptors was limited to the urothelium and the muscle layer and correlated between these structures. There was no relationship between pain response and the expression of P2X3 receptors. Conclusions: ICCs and P2X3 receptors may participate in the pathogenesis of UPJO and in the modulation of pain response to a dilatation of the pyelocaliceal system. Explanation of the role of ICCs and P2X3 receptors in propagation of ureteral peristaltic wave and the modulation of pain stimuli requires further studies.

5-Hydroxytryptamine Enhances the Pacemaker Activity of Interstitial Cells of Cajal in Mouse Colon.

We examined the localization of the 5-hydroxytryptamine (5-HT) receptor and its effects on mouse colonic interstitial cells of Cajal (ICCs) using electrophysiological techniques. Treatment with 5-HT increased the pacemaker activity in colonic ICCs with depolarization of membrane potentials in a dose-dependent manner. Hyperpolarization-activated cyclic nucleotide-gated (HCN) channel blockers blocked pacemaker activity and 5-HT-induced effects. Moreover, an adenylate cyclase inhibitor inhibited 5-HT-induced effects, and cell-permeable 8-bromo-cAMP increased the pacemaker activity. Various agonists of the 5-HT receptor subtype were working in colonic ICCs, including the 5-HT4 receptor. In small intestinal ICCs, 5-HT depolarized the membrane potentials transiently. Adenylate cyclase inhibitors or HCN blockers did not show any influence on 5-HT-induced effects. Anoctamin-1 (ANO1) or T-type Ca2+ channel blockers inhibited the pacemaker activity of colonic ICCs and blocked 5-HT-induced effects. A tyrosine protein kinase inhibitor inhibited pacemaker activity in colonic ICCs under controlled conditions but did not show any influence on 5-HT-induced effects. Among mitogen-activated protein kinase (MAPK) inhibitors, a p38 MAPK inhibitor inhibited 5-HT-induced effects on colonic ICCs. Thus, 5-HT's effect on pacemaker activity in small intestinal and colonic ICCs has excitatory but variable patterns. ANO1, T-type Ca2+, and HCN channels are involved in 5-HT-induced effects, and MAPKs are involved in 5-HT effects in colonic ICCs.

Quantification of interstitial cells of Cajal and fibrosis during gastric per-oral endoscopic myotomy and its association with clinical outcomes.

Background and study aims Alterations to interstitial cells of Cajal (ICC) and collagen fibrosis have been implicated in the pathogenesis of gastroparesis. We aimed to evaluate the feasibility and safety of pyloric muscle sampling during gastric peroral endoscopic myotomy (G-POEM) and the association between pyloric ICC density and degree of fibrosis with clinical outcomes. Patients and methods This was a single-center prospective study of gastroparetic patients who underwent G-POEM and intraprocedural pyloric muscle biopsies between January 2022 and April 2023. ICC count was estimated using CD117 stain and trichome for collagen fibrosis. Clinical response to G-POEM was defined as an improvement of ≥ 1 point on the Gastroparesis Cardinal Symptom Index. Results Fifty-six patients (median age 60 years, 71.4% women) underwent G-POEM (100% technical success; 71.4% clinical response). ICC depletion (< 10/high-power field) and fibrosis were encountered in 70.4% and 75% of the cases, respectively. There was no difference in mean ICC count between G-POEM responders vs. non-responders (7±3.6 vs. 7.7±3.3; P = 0.9). There was no association between ICC density or degree of fibrosis with the etiology of gastroparesis, duration of symptoms, gastric emptying rate, or pyloric impedance planimetry. Patients who did not respond to G-POEM had a significantly higher degree of moderate/severe fibrosis when compared with those who responded (81.3% vs. 25%; P = 0.0002). Conclusions Pyloric muscle biopsies during G-POEM was feasible and safe. ICC depletion and pyloric muscle fibrosis are common in gastroparetic patients. The degree of fibrosis may be related to pyloric dysfunction and clinical response to G-POEM. Additional studies are needed to confirm these results.