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Biomolecules Dec 2023Oxygen level is a key regulator of organogenesis and its modification in postnatal life alters the maturation process of organs, including the intestine, which do not...
Oxygen level is a key regulator of organogenesis and its modification in postnatal life alters the maturation process of organs, including the intestine, which do not completely develop in utero. The β3-adrenoreceptor (β3-AR) is expressed in the colon and has an oxygen-dependent regulatory mechanism. This study shows the effects of the β3-AR agonist BRL37344 in a neonatal model of hyperoxia-driven colonic injury. For the first 14 days after birth, Sprague-Dawley rat pups were exposed to ambient oxygen levels (21%) or hyperoxia (85%) and treated daily with BRL37344 at 1, 3, 6 mg/kg or untreated. At the end of day 14, proximal colon samples were collected for analysis. Hyperoxia deeply influences the proximal colon development by reducing β3-AR-expressing cells (27%), colonic length (26%) and mucin production (47%), and altering the neuronal chemical coding in the myenteric plexus without changes in the neuron number. The administration of BRL37344 at 3 mg/kg, but not at 1 mg/kg, significantly prevented these alterations. Conversely, it was ineffective in preventing hyperoxia-induced body weight loss. BRL37344 at 6 mg/kg was toxic. These findings pave the way for β3-AR pharmacological targeting as a therapeutic option for diseases caused by hyperoxia-impaired development, typical prematurity disorders.
Topics: Rats; Animals; Ethanolamines; Hyperoxia; Rats, Sprague-Dawley; Adrenergic Agonists; Receptors, Adrenergic, beta-3; Oxygen
PubMed: 38136626
DOI: 10.3390/biom13121755 -
Scientific Reports Dec 2023Previously, the presence of a blood-myenteric plexus barrier and its disruption was reported in experimentally induced colitis via a macrophage-dependent process. The...
Previously, the presence of a blood-myenteric plexus barrier and its disruption was reported in experimentally induced colitis via a macrophage-dependent process. The aim of this study is to reveal how myenteric barrier disruption and subsequent neuronal injury affects gut motility in vivo in a murine colitis model. We induced colitis with dextran sulfate sodium (DSS), with the co-administration of liposome-encapsulated clodronate (L-clodronate) to simultaneously deplete blood monocytes contributing to macrophage infiltration in the inflamed muscularis of experimental mice. DSS-treated animals receiving concurrent L-clodronate injection showed significantly decreased blood monocyte numbers and colon muscularis macrophage (MM) density compared to DSS-treated control (DSS-vehicle). DSS-clodronate-treated mice exhibited significantly slower whole gut transit time than DSS-vehicle-treated animals and comparable to that of controls. Experiments with oral gavage-fed Evans-blue dye showed similar whole gut transit times in DSS-clodronate-treated mice as in control animals. Furthermore, qPCR-analysis and immunofluorescence on colon muscularis samples revealed that factors associated with neuroinflammation and neurodegeneration, including Bax1, Hdac4, IL-18, Casp8 and Hif1a are overexpressed after DSS-treatment, but not in the case of concurrent L-clodronate administration. Our findings highlight that MM-infiltration in the muscularis layer is responsible for colitis-associated dysmotility and enteric neuronal dysfunction along with the release of mediators associated with neurodegeneration in a murine experimental model.
Topics: Mice; Animals; Clodronic Acid; Colitis; Inflammation; Macrophages; Colon; Dextran Sulfate; Mice, Inbred C57BL; Disease Models, Animal
PubMed: 38105266
DOI: 10.1038/s41598-023-50059-7 -
Folia Morphologica Dec 2023Neurons of the enteric nervous system are characterised by high neuronal plasticity, with their number likely to change in response to various endogenous and exogenous...
BACKGROUND
Neurons of the enteric nervous system are characterised by high neuronal plasticity, with their number likely to change in response to various endogenous and exogenous substances.
MATERIALS AND METHODS
Fifteen sexually immature gilts divided into 3 groups were used: control - animals receiving empty gelatin capsules; G1 - animals receiving a low dose of glyphosate - 0.05 mg/kg bw/day; G2 - animals receiving a higher dose of glyphosate-0.5 mg/kg/day in gelatin capsules orally for 28 days. Frozen sections were then subjected to the procedure of double immunofluorescent staining.
RESULTS
With low-dose supplementation, no effect on the SP- and CART-positive neuron population was observed. However, a reduction in the number of VAChT-positive neurons in the internal submucosal plexus was described, while the number of CGRP-positive neurons increased in all enteric plexuses. In response to a high glyphosate dose, the quantitative variability of the neurons was significantly more pronounced than that for a low dose. There was an increase in the number of SP- and CGRP-positive neurons and a decrease in the number of VAChT-positive neurons in both the myenteric plexus and the submucosal plexuses. The response of CART-positive neurons was the weakest, as a high dose of glyphosate led to an increase in the number of neurons only in the myenteric plexus.
CONCLUSIONS
The above data show that glyphosate is an exogenous substance that affects neuronal populations of the enteric nervous system, in this case, the descending colon.
PubMed: 38078736
DOI: 10.5603/fm.97761 -
International Journal of Molecular... Nov 2023Environmental contamination and the resulting food contamination represent a serious problem and pose a major threat to animal and human health. The gastrointestinal...
Environmental contamination and the resulting food contamination represent a serious problem and pose a major threat to animal and human health. The gastrointestinal tract is directly exposed to a variety of substances. One is glyphosate, whose presence in the soil is commonly observed. This study demonstrates the effects of low and high glyphosate doses on the populations of intramural neurons of the porcine descending colon. An analysis was performed on neurons ex-pressing the vasoactive intestinal peptide, pituitary adenylate cyclase-activating peptide, a neuronal isoform of nitrogen oxide synthase, and galanin. Even a low dose of glyphosate increased the number of neurons immunoreactive against the studied substances. However, the changes depended on both the plexus analysed and the substance tested. Meanwhile, a high glyphosate dose resulted in quantitative changes (an increase in the number) within neurons immunoreactive against all the studied neuropeptides/enzymes in the myenteric plexus and both submucosal plexuses. The response of the enteric nervous system in the form of an increase in the number of neurons immunoreactive against neuroprotective substances may suggest that glyphosate has a toxic effect on enteric neurons which attempt to increase their survivability through the released neuroprotective substances.
Topics: Humans; Swine; Animals; Colon, Descending; Enteric Nervous System; Vasoactive Intestinal Peptide; Pituitary Adenylate Cyclase-Activating Polypeptide; Neurons; Phenotype
PubMed: 38069321
DOI: 10.3390/ijms242316998 -
Cell and Tissue Research Jan 2024The pig is an important translational model for studying intestinal physiology and disorders for its many homologies with humans, including the organization of the...
The pig is an important translational model for studying intestinal physiology and disorders for its many homologies with humans, including the organization of the enteric nervous system (ENS), the major regulator of gastrointestinal functions. This study focused on the quantification and neurochemical characterization of substance P (SP) neurons in the pig ascending (AC) and descending colon (DC) in wholemount preparations of the inner submucosal plexus (ISP), outer submucosal plexus (OSP), and myenteric plexus (MP). We used antibodies for the pan-neuronal marker HuCD, and choline acetyltransferase (ChAT) and neuronal nitric oxide synthase (nNOS), markers for excitatory and inhibitory transmitters, for multiple labeling immunofluorescence and high-resolution confocal microscopy. The highest density of SP immunoreactive (IR) neurons was in the ISP (222/mm in the AC, 166/mm in the DC), where they make up about a third of HuCD-IR neurons, compared to the OSP and MP (19-22% and 13-17%, respectively, P < 0.001-0.0001). HuCD/SP/ChAT-IR neurons (up to 23%) were overall more abundant than HuCD/SP/nNOS-IR neurons (< 10%). Most SP-IR neurons contained ChAT-IR (62-85%), whereas 18-38% contained nNOS-IR with the highest peak in the OSP. A subpopulation of SP-IR neurons contains both ChAT- and nNOS-IR with the highest peak in the OSP and ISP of DC (33-36%) and the lowest in the ISP of AC (< 10%, P < 0.001). SP-IR varicose fibers were abundant in the ganglia. This study shows that SP-IR neurons are functionally distinct with variable proportions in different plexuses in the AC and DC reflecting diverse functions of specific colonic regions.
Topics: Humans; Swine; Animals; Myenteric Plexus; Submucous Plexus; Substance P; Neurons; Colon; Choline O-Acetyltransferase
PubMed: 37982872
DOI: 10.1007/s00441-023-03842-x -
Biomolecules Oct 2023No standard diagnostic method or surgical treatment for congenital isolated hypoganglionosis (CIHG) has been established. This study aimed to analyze the clinical...
No standard diagnostic method or surgical treatment for congenital isolated hypoganglionosis (CIHG) has been established. This study aimed to analyze the clinical outcomes of patients with CIHG and identify the best surgical interventions provided thus far. Data on surgical interventions in 19 patients were collected between 1992 and 2020, including the type of enterostomy, type of revision, and length of the intestines. Ganglion cells in the myenteric plexus were enumerated using Hu C/D staining. The ratio of the length of the small intestine to its height was defined as the intestinal ratio (IR). The outcomes were assessed using the stoma output, growth parameters including the body mass index (BMI), and parenteral nutrition (PN) dependency. All patients required a diverting enterostomy. The IR ranged from 0.51 to 1.75 after multiple non-transplant surgeries. The stoma types were tube-stoma, end-stoma, Santulli-type, and Bishop-Koop (BK)-type. Patients with Santulli- or BK-type stomas had better BMIs and less PN dependency in terms of volume than those with end-stomas or tube-stomas. Two patients with BK-type stomas were off PN, and three who underwent an intestinal transplantation (Itx) achieved enteral autonomy. The management of CIHG involves a precise diagnosis using Hu C/D staining, neonatal enterostomy, and stoma revision using the adjusted IR and Itx if other treatments do not enable enteral autonomy.
Topics: Infant, Newborn; Humans; Cohort Studies; Retrospective Studies; Intestines; Enterostomy; Surgical Stomas
PubMed: 37892242
DOI: 10.3390/biom13101560 -
Frontiers in Immunology 2023Intestinal macrophages are well-studied for their conventional roles in the immune response against pathogens and protecting the gut from chronic inflammation. However,...
Macrophage regulation of the "second brain": CD163 intestinal macrophages interact with inhibitory interneurons to regulate colonic motility - evidence from the rat model.
Intestinal macrophages are well-studied for their conventional roles in the immune response against pathogens and protecting the gut from chronic inflammation. However, these macrophages may also have additional functional roles in gastrointestinal motility under typical conditions. This is likely to occur via both direct and indirect influences on gastrointestinal motility through interaction with myenteric neurons that contribute to the gut-brain axis, but this mechanism is yet to be properly characterised. The CX3CR1 chemokine receptor is expressed in the majority of intestinal macrophages, so we used a conditional knockout (diphtheria toxin receptor) rat model to transiently ablate these cells. We then utilized video imaging to evaluate colonic motility. Our previous studies in brain suggested that -expressing cells repopulate by 7 days after depletion in this model, so we performed our experiments at both the 48 hr (macrophage depletion) and 7-day (macrophage repopulation) time points. We also investigated whether inhibitory neuronal input driven by nitric oxide from the enteric nervous system is required for the regulation of colonic motility by intestinal macrophages. Our results demonstrated that CD163-positive resident intestinal macrophages are important in regulating colonic motility in the absence of this major inhibitory neuronal input. In addition, we show that intestinal macrophages are indispensable in maintaining a healthy intestinal structure. Our study provides a novel understanding of the interplay between the enteric nervous system and intestinal macrophages in colonic motility. We highlight intestinal macrophages as a potential therapeutic target for gastrointestinal motility disorders when inhibitory neuronal input is suppressed.
Topics: Animals; Rats; Brain; Heparin-binding EGF-like Growth Factor; Interneurons; Macrophages
PubMed: 37868978
DOI: 10.3389/fimmu.2023.1269890 -
Cureus Sep 2023Achalasia, a neurodegenerative disease caused by the progressive destruction of ganglion cells in the myenteric plexus, is accompanied by incomplete relaxation of the... (Review)
Review
Comparison of the Clinical Efficacy, Safety, and Postoperative Outcomes Between Peroral Esophageal Myotomy and Laparoscopic Heller's Myotomy With Fundoplication: A Systematic Review.
Achalasia, a neurodegenerative disease caused by the progressive destruction of ganglion cells in the myenteric plexus, is accompanied by incomplete relaxation of the lower esophageal sphincter. Laparoscopic Heller's myotomy (LHM) coupled with fundoplication has been the gold standard procedure for achalasia. Peroral esophageal myotomy (POEM) has recently gained popularity as it is minimally invasive, has fewer adverse events, and has excellent short-term outcomes. So, we aimed to compare the clinical efficacy, safety, and postoperative outcomes between LHM and POEM. We did a systematic review by following the Preferred Reporting Items for Systematic Review and Meta-Analyses (PRISMA) guidelines for 2020 and exploring research databases such as PUBMED and PMC Central, Google Scholar, and Research Gate. After appropriate screenings, articles relevant to the review were scrutinized based on the eligibility criteria. Quality assessment tools such as the Newcastle-Ottawa Scale (NOS) and the assessment of multiple systematic reviews (AMSTAR) were used to finalize the articles. A total of 11 articles (seven observational studies, two RCTs, and two systematic reviews) were included in the review after a quality check. The study included 2127 patients, classified into 981 for POEM and 1146 for LHM, who had undergone treatment for achalasia. Most of the studies had a follow-up of ≤ two years. Comparing efficacy, POEM had similar results to LHM in terms of Eckardt scores. However, abnormal DeMeester scores were found in POEM. Adverse events were significantly higher in LHM when compared to POEM in terms of safety. Peroral esophageal myotomy also stood out as having a shorter procedure time, a shorter hospital stay, and lesser odds of being a clinical failure. As for postoperative outcomes, despite treatment with proton pump inhibitors, LHM was more effective in preventing the development of esophagitis compared to POEM due to partial fundoplication.Postoperative reflux and the development of esophagitis remain certain with POEM and need to be followed up with more studies with longer follow-ups. However, POEM still stands as a better choice compared to LHM in terms of efficacy and safety.
PubMed: 37818506
DOI: 10.7759/cureus.44877 -
Frontiers in Physiology 2023A rhythmic expression of clock genes occurs within the cells of multiple organs and tissues throughout the body, termed "peripheral clocks." Peripheral clocks are... (Review)
Review
A rhythmic expression of clock genes occurs within the cells of multiple organs and tissues throughout the body, termed "peripheral clocks." Peripheral clocks are subject to entrainment by a multitude of factors, many of which are directly or indirectly controlled by the light-entrainable clock located in the suprachiasmatic nucleus of the hypothalamus. Peripheral clocks occur in the gastrointestinal tract, notably the epithelia whose functions include regulation of absorption, permeability, and secretion of hormones; and in the myenteric plexus, which is the intrinsic neural network principally responsible for the coordination of muscular activity in the gut. This review focuses on the physiological circadian variation of major colonic functions and their entraining mechanisms, including colonic motility, absorption, hormone secretion, permeability, and pain signalling. Pathophysiological states such as irritable bowel syndrome and ulcerative colitis and their interactions with circadian rhythmicity are also described. Finally, the classic circadian hormone melatonin is discussed, which is expressed in the gut in greater quantities than the pineal gland, and whose exogenous use has been of therapeutic interest in treating colonic pathophysiological states, including those exacerbated by chronic circadian disruption.
PubMed: 37711458
DOI: 10.3389/fphys.2023.1239278 -
The Journal of Comparative Neurology Nov 2023Nociceptive afferent axons innervate the stomach and send signals to the brain and spinal cord. Peripheral nociceptive afferents can be detected with a variety of...
Nociceptive afferent axons innervate the stomach and send signals to the brain and spinal cord. Peripheral nociceptive afferents can be detected with a variety of markers (e.g., substance P [SP] and calcitonin gene-related peptide [CGRP]). We recently examined the topographical organization and morphology of SP-immunoreactive (SP-IR) axons in the whole mouse stomach muscular layer. However, the distribution and morphological structure of CGRP-IR axons remain unclear. We used immunohistochemistry labeling and applied a combination of imaging techniques, including confocal and Zeiss Imager M2 microscopy, Neurolucida 360 tracing, and integration of axon tracing data into a 3D stomach scaffold to characterize CGRP-IR axons and terminals in the whole mouse stomach muscular layers. We found that: (1) CGRP-IR axons formed extensive terminal networks in both ventral and dorsal stomachs. (2) CGRP-IR axons densely innervated the blood vessels. (3) CGRP-IR axons ran in parallel with the longitudinal and circular muscles. Some axons ran at angles through the muscular layers. (4) They also formed varicose terminal contacts with individual myenteric ganglion neurons. (5) CGRP-IR occurred in DiI-labeled gastric-projecting neurons in the dorsal root and vagal nodose ganglia, indicating CGRP-IR axons were visceral afferent axons. (6) CGRP-IR axons did not colocalize with tyrosine hydroxylase or vesicular acetylcholine transporter axons in the stomach, indicating CGRP-IR axons were not visceral efferent axons. (7) CGRP-IR axons were traced and integrated into a 3D stomach scaffold. For the first time, we provided a topographical distribution map of CGRP-IR axon innervation of the whole stomach muscular layers at the cellular/axonal/varicosity scale.
Topics: Animals; Mice; Calcitonin Gene-Related Peptide; Stomach; Axons; Neurons; Nerve Fibers
PubMed: 37694767
DOI: 10.1002/cne.25519