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Frontiers in Neuroscience 2022In the human large bowel, sacral parasympathetic nerves arise from S2 to S4, project to the pelvic plexus ("hypogastric plexus") and have post-ganglionic axons entering...
BACKGROUND
In the human large bowel, sacral parasympathetic nerves arise from S2 to S4, project to the pelvic plexus ("hypogastric plexus") and have post-ganglionic axons entering the large bowel near the rectosigmoid junction. They then run long distances orally or aborally within the bowel wall forming "ascending nerves" or "shunt fascicles" running in the plane of the myenteric plexus. They form bundles of nerve fibres that can be distinguished from the myenteric plexus by their straight orientation, tendency not to merge with myenteric ganglia and greater width.
AIM
To identify reliable marker(s) to distinguish these bundles of ascending nerves from other extrinsic and intrinsic nerves in human colon.
METHODS
Human colonic segments were obtained with informed consent, from adult patients undergoing elective surgery ( = 21). Multi-layer immunohistochemical labelling with neurofilament-H (NF200), myelin basic protein (MBP), von Willebrand factor (vWF), and glucose transporter 1 (GLUT1), and rapid anterograde tracing with biotinamide, were used to compare ascending nerves and lumbar colonic nerves.
RESULTS
The rectosigmoid and rectal specimens had 6-11 ascending nerves spaced around their circumference. Distal colon specimens typically had 1-3 ascending nerves, with one located near the mesenteric taenia coli. No ascending nerves were observed in ascending colon specimens. GLUT1 antisera labelled both sympathetic lumbar colonic nerves and ascending nerves in the gut wall. Lumbar colonic nerves joined the myenteric plexus and quickly lost GLUT1 labelling, whereas GLUT1 staining labelled parasympathetic ascending nerves over many centimetres.
CONCLUSION
Ascending nerves can be distinguished in the colorectum of humans using GLUT1 labelling combined with NF200.
PubMed: 36532291
DOI: 10.3389/fnins.2022.1072002 -
Physiological Reports Feb 2021Obesity is associated with the development of insulin resistance (IR) and type-2 diabetes mellitus (T2DM); however, not all patients with T2DM are obese. The... (Comparative Study)
Comparative Study
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-1β 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-1β 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.
Topics: Animals; Blood Glucose; Cytokines; Diabetes Mellitus, Type 2; Disease Models, Animal; Duodenum; Gastrointestinal Transit; Ileum; Inflammation Mediators; Insulin Resistance; Intestine, Small; Jejunum; Male; Myenteric Plexus; Rats, Wistar; Submucous Plexus; Rats
PubMed: 33580916
DOI: 10.14814/phy2.14755 -
Animals : An Open Access Journal From... Jan 2021An important piece of evidence has shown that molecules acting on cannabinoid receptors influence gastrointestinal motility and induce beneficial effects on...
An important piece of evidence has shown that molecules acting on cannabinoid receptors influence gastrointestinal motility and induce beneficial effects on gastrointestinal inflammation and visceral pain. The aim of this investigation was to immunohistochemically localize the distribution of canonical cannabinoid receptor type 1 (CB1R) and type 2 (CB2R) and the cannabinoid-related receptors transient potential vanilloid receptor 1 (TRPV1), transient potential ankyrin receptor 1 (TRPA1), and serotonin receptor 5-HT1a (5-HT1aR) in the myenteric plexus (MP) of pig ileum. CB1R, TRPV1, TRPA1, and 5-HT1aR were expressed, with different intensities in the cytoplasm of MP neurons. For each receptor, the proportions of the immunoreactive neurons were evaluated using the anti-HuC/HuD antibody. These receptors were also localized on nerve fibers (CB1R, TRPA1), smooth muscle cells of (CB1R, 5-HT1aR), and endothelial cells of blood vessels (TRPV1, TRPA1, 5-HT1aR). The nerve varicosities were also found to be immunoreactive for both TRPV1 and 5-HT1aR. No immunoreactivity was documented for CB2R. Cannabinoid and cannabinoid-related receptors herein investigated showed a wide distribution in the enteric neurons and nerve fibers of the pig MP. These results could provide an anatomical basis for additional research, supporting the therapeutic use of cannabinoid receptor agonists in relieving motility disorders in porcine enteropathies.
PubMed: 33494452
DOI: 10.3390/ani11020263 -
International Journal of Molecular... Jan 2018Calbindin (CALB) is well established as immunohistochemical marker for intrinsic primary afferent neurons in the guinea pig gut. Its expression by numerous human enteric...
Calbindin (CALB) is well established as immunohistochemical marker for intrinsic primary afferent neurons in the guinea pig gut. Its expression by numerous human enteric neurons has been demonstrated but little is known about particular types of neurons immunoreactive for CALB. Here we investigated small and large intestinal wholemount sets of 26 tumor patients in order to evaluate (1) the proportion of CALB⁺ neurons in the total neuron population, (2) the colocalization of CALB with calretinin (CALR), somatostatin (SOM) and vasoactive intestinal peptide (VIP) and (3) the morphology of CALB neurons. CALB neurons represented a minority of myenteric neurons (small intestine: 31%; large intestine: 25%) and the majority of submucosal neurons (between 72 and 95%). In the submucosa, most CALB⁺ neurons co-stained for CALR and VIP (between 69 and 80%) or for SOM (between 20 and 3%). In the myenteric plexus, 85% of CALB neurons did not co-stain with the other markers investigated. An unequivocal correlation between CALB reactivity and neuronal morphology was found for myenteric type III neurons in the small intestine: uniaxonal neurons with long, slender and branched dendrites were generally positive for CALB. Since also other neurons displayed occasional CALB reactivity, this protein is not suited as an exclusive marker for type III neurons.
Topics: Adult; Aged; Aged, 80 and over; Calbindin 1; Female; Humans; Male; Middle Aged; Myenteric Plexus; Neurons; Somatostatin; Submucous Plexus; Vasoactive Intestinal Peptide
PubMed: 29316719
DOI: 10.3390/ijms19010194 -
Acta Pharmacologica Sinica May 2018In this brief review we summarize the current fndings relative to the discovery of a small peptide ligand, phoenixin (PNX). Using a bioinformatic approach, two novel... (Review)
Review
In this brief review we summarize the current fndings relative to the discovery of a small peptide ligand, phoenixin (PNX). Using a bioinformatic approach, two novel peptides PNX-14 and PNX-20 containing 14 and 20 amino acids, respectively, were isolated from diverse tissues including the brain, heart, lung and stomach. Mass spectrometry analysis identified a major and minor peak corresponding to PNX-14 and PNX-20, in rat or mouse spinal cord extracts. With the use of a rabbit polyclonal antiserum, phoenixin immunoreactivity (irPNX) was detected in discrete areas of the rodent brain including several hypothalamic subnuclei and dorsal motor nucleus of the vagus. In addition, irPNX was detected in a population of sensory ganglion cells including dorsal root ganglion, nodose ganglion and trigeminal ganglion, and in cell processes densely distributed to the superficial layers of the dorsal horn, nucleus of the solitary tract and spinal trigeminal tract. irPNX cell processes were also detected in the skin and myenteric plexus, suggesting a brain-gut and/or brain-skin connection. Pharmacological studies show that PNX-14 injected subcutaneously to the nape of the neck of mice provoked dose-dependent repetitive scratching bouts directed to the back of the neck with the hindpaws. Our result suggests that the peptide PNX-14 and/or PNX-20, may serve as one of the endogenous signal molecules transducing itch sensation. Additionally, results from other laboratories show that exogenous PNX may affect a number of diverse behaviors such as memory formation, depression, reproduction, food-intake and anxiolytic-like behaviors.
Topics: Amino Acid Sequence; Animals; Humans; Hypothalamic Hormones; Hypothalamus; Memory; Myenteric Plexus; Peptide Hormones; Peptides; Pruritus; Spinal Cord
PubMed: 29542680
DOI: 10.1038/aps.2017.195 -
Advances in Experimental Medicine and... 2022ATP is an excitatory and inhibitory neurotransmitter, while nitric oxide (NO) is an inhibitory neurotransmitter in the enteric nervous system (ENS). We used a vesicular...
ATP is an excitatory and inhibitory neurotransmitter, while nitric oxide (NO) is an inhibitory neurotransmitter in the enteric nervous system (ENS). We used a vesicular nucleotide transporter (SLC17A9, VNUT) antibody and a nitric oxide synthase (NOS) antibody to identify purinergic and nitrergic nerves in mouse and guinea ileum. Mouse: VNUT-immunoreactivity (ir) was detected in nerve fibers in myenteric ganglia and circular muscle. VNUT-ir fibers surrounded choline acetyltransferase (ChAT), nitric oxide synthase (nNOS), and calretinin-ir neurons. VNUT-ir nerve cell bodies were not detected. Tyrosine hydroxylase (TH)-ir nerves were detected in myenteric ganglia and the tertiary plexus. Guinea pig: VNUT-ir was detected in neurons and nerves fibers and did not overlap with NOS-ir nerve fibers. VNUT-ir was detected in nerve fibers in ganglia but not nerve cell bodies. VNUT-ir nerve fibers surrounded NOS-ir and NOS neurons. NOS-ir and VNUT-ir nerve fibers did not overlap in myenteric ganglia or circular muscle. VNUT-ir nerves surrounded some ChAT-ir neurons. VNUT-ir and ChAT-ir were detected in separate nerves in the CM. VNUT-ir nerve fibers surrounded calretinin-ir neurons.Conclusions: VNUT-ir neurons likely mediate purinergic signaling in small intestinal myenteric ganglia and circular muscle. ATP and NO are likely released from different inhibitory motorneurons. VNUT-ir and ChAT-ir interneurons mediate cholinergic and purinergic synaptic transmission in the myenteric plexus.
Topics: Guinea Pigs; Animals; Myenteric Plexus; Calbindin 2; Nitric Oxide Synthase; Muscles; Neurotransmitter Agents; Adenosine Triphosphate
PubMed: 36587144
DOI: 10.1007/978-3-031-05843-1_4 -
Neurogastroenterology and Motility Nov 2023Early-life events impact maturation of the gut microbiome, enteric nervous system, and gastrointestinal motility. We examined three regions of gastric tissue to...
BACKGROUND
Early-life events impact maturation of the gut microbiome, enteric nervous system, and gastrointestinal motility. We examined three regions of gastric tissue to determine how maternal separation and gut microbes influence the structure and motor function of specific regions of the neonatal mouse stomach.
METHODS
Germ-free and conventionally housed C57BL/6J mouse pups underwent timed maternal separation (TmSep) or nursed uninterrupted (controls) until 14 days of life. We assessed gastric emptying by quantifying the progression of gavaged fluorescein isothiocyanate (FITC)-dextran. With isolated rings of forestomach, corpus, and antrum, we measured tone and contractility by force transduction, gastric wall thickness by light microscopy, and myenteric plexus neurochemistry by whole-mount immunostaining.
KEY RESULTS
Regional gastric sampling revealed site-specific differences in contractile patterns and myenteric plexus structure. In neonatal mice, TmSep prolonged gastric emptying. In the forestomach, TmSep increased contractile responses to carbachol, decreased muscularis externa and mucosa thickness, and increased the relative proportion of myenteric plexus nNOS+ neurons. Germ-free conditions did not appreciably alter the structure or function of the neonatal mouse stomach and did not impact the changes caused by TmSep.
CONCLUSIONS AND INFERENCES
A regional sampling approach facilitates site-specific investigations of murine gastric motor physiology and histology to identify site-specific alterations that may impact gastrointestinal function. Delayed gastric emptying in TmSep is associated with a thinner muscle wall, exaggerated cholinergic contractile responses, and increased proportions of inhibitory myenteric plexus nNOS+ neurons in the forestomach. Gut microbes do not profoundly affect the development of the neonatal mouse stomach or the gastric pathophysiology that results from TmSep.
Topics: Mice; Animals; Animals, Newborn; Gastroparesis; Maternal Deprivation; Mice, Inbred C57BL; Stomach; Myenteric Plexus; Disease Models, Animal; Gastric Emptying
PubMed: 37772676
DOI: 10.1111/nmo.14676 -
Journal of Neurogastroenterology and... Jan 2017Myenteric plexus interstitial cells of Cajal (ICC-MY) are involved in the generation of gut pacemaker activity and neuronal communication. We performed patch clamp on...
BACKGROUND/AIMS
Myenteric plexus interstitial cells of Cajal (ICC-MY) are involved in the generation of gut pacemaker activity and neuronal communication. We performed patch clamp on ICC-MY in situ to observe the changes of pacemaker activity in response to neural modulations.
METHODS
A fresh longitudinal muscle with myenteric plexus (LMMP) from mouse jejunum was prepared. ICC-MY and ganglion neurons embedded in the layer of longitudinal muscles were targeted by patch clamping in whole-cell configuration in a model of current or voltage clamp. Neurogenic modulators were applied to evaluate their effects on ICC pacemaker activity.
RESULTS
In situ ICC-MY showed spontaneous and rhythmical voltage oscillations with a frequency of 27.2 ± 3.9 cycles/min, amplitude of 32.6 ± 6.3 mV, and resting membrane potential of -62.2 ± 2.8 mV. In situ neurons showed electrically evocable action potential in single or multiple spikes. Pacemaker activity was modulated by neuronal activators through receiving a neuronal input. Application of tetrodotoxin depolarized pacemaker potentials in a dose dependent manner, and decreased the amplitude at tetrodotoxin 0.3 μM for about 40 ± 10%; capsaicin (1 μM) ameliorated ICC-MY K⁺ current for about 49 ± 14.8%; and, nitric oxide hyperpolarized pacemaker potential and decreased the amplitude and frequency.
CONCLUSIONS
The in situ preparation patch clamp study further demonstrates that the pacemaker activity is an intrinsic property of ICC. The neurogenic activators change and shape pacemaker potential and activity in situ. LMMP preparation in situ patch clamp provides an ideal platform to study the functional innervation of the ICC and the enteric neural system, thereby, for evaluating the neural regulation of pacemaker activity, especially in disorder models.
PubMed: 27436346
DOI: 10.5056/jnm16012 -
The Journal of Pathology Jun 2022SARS-CoV-2, the causative agent of COVID-19, typically manifests as a respiratory illness, although extrapulmonary involvement, such as in the gastrointestinal tract and...
SARS-CoV-2, the causative agent of COVID-19, typically manifests as a respiratory illness, although extrapulmonary involvement, such as in the gastrointestinal tract and nervous system, as well as frequent thrombotic events, are increasingly recognised. How this maps onto SARS-CoV-2 organ tropism at the histological level, however, remains unclear. Here, we perform a comprehensive validation of a monoclonal antibody against the SARS-CoV-2 nucleocapsid protein (NP) followed by systematic multisystem organ immunohistochemistry analysis of the viral cellular tropism in tissue from 36 patients, 16 postmortem cases and 16 biopsies with polymerase chain reaction (PCR)-confirmed SARS-CoV-2 status from the peaks of the pandemic in 2020 and four pre-COVID postmortem controls. SARS-CoV-2 anti-NP staining in the postmortem cases revealed broad multiorgan involvement of the respiratory, digestive, haematopoietic, genitourinary and nervous systems, with a typical pattern of staining characterised by punctate paranuclear and apical cytoplasmic labelling. The average time from symptom onset to time of death was shorter in positively versus negatively stained postmortem cases (mean = 10.3 days versus mean = 20.3 days, p = 0.0416, with no cases showing definitive staining if the interval exceeded 15 days). One striking finding was the widespread presence of SARS-CoV-2 NP in neurons of the myenteric plexus, a site of high ACE2 expression, the entry receptor for SARS-CoV-2, and one of the earliest affected cells in Parkinson's disease. In the bone marrow, we observed viral SARS-CoV-2 NP within megakaryocytes, key cells in platelet production and thrombus formation. In 15 tracheal biopsies performed in patients requiring ventilation, there was a near complete concordance between immunohistochemistry and PCR swab results. Going forward, our findings have relevance to correlating clinical symptoms with the organ tropism of SARS-CoV-2 in contemporary cases as well as providing insights into potential long-term complications of COVID-19. © 2022 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.
Topics: COVID-19; Humans; Megakaryocytes; Myenteric Plexus; Neurons; SARS-CoV-2
PubMed: 35107828
DOI: 10.1002/path.5878 -
Anatomical Record (Hoboken, N.J. : 2007) Sep 2023The enteric nervous system, a major subdivision of the autonomic nervous system, is known for its neurochemical heterogeneity and complexity. The myenteric plexus, one...
The enteric nervous system, a major subdivision of the autonomic nervous system, is known for its neurochemical heterogeneity and complexity. The myenteric plexus, one of its two principal components, primarily controls peristalsis and its dysfunction may lead to a number of gastrointestinal motility disorders. The myenteric neurons have been described to use a wide variety of neurotransmitters although no evidence has been reported for the existence of adrenergic neurons in the hindgut. This study aims at elucidating the chemical coding of neurons in the myenteric plexus of the rat colon and anorectal region with particular emphasis on cholinergic and the so-called nonadrenergic, noncholinergic (NANC) transmitter systems. The immunostaining for choline acetyltransferase revealed an intense staining of the myenteric ganglia with clear delineation of their neuronal cell bodies and without local distributional differences in the colonic region. The myenteric ATPergic structures were mostly limited to fiber bundles surrounding unstained myenteric neurons and penetrating the two muscle layers. We also observed an abundance of intensely stained varicose substance P-immunopositive fibers, ensheathing the immunonegative myenteric neuronal cell bodies in a basket-like manner. Applying NADPH-diaphorase histochemistry and nitric oxide synthase immunohistochemistry, we were able to demonstrate numerous nitrergic somata of myenteric neurons with Dogiel Type I morphology. Apart from the observed nitrergic distributional patterns, no distinct variations were found in the staining intensity or distribution of myenteric structures in the colon and anorectal area. Our results suggest that myenteric neurons in the distal intestinal portion utilize a broad spectrum of enteric transmitters, including classical and NANC transmitters.
Topics: Animals; Rats; Myenteric Plexus; Enteric Nervous System; Neurons; Intestines; Nitric Oxide Synthase; Colorectal Neoplasms
PubMed: 35716375
DOI: 10.1002/ar.25019