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Cell and Tissue Research Apr 2022We investigated the distributions and targets of nitrergic neurons in the rat stomach, using neuronal nitric oxide synthase (NOS) immunohistochemistry and nicotinamide...
We investigated the distributions and targets of nitrergic neurons in the rat stomach, using neuronal nitric oxide synthase (NOS) immunohistochemistry and nicotinamide adenine dinucleotide phosphate (NADPH) diaphorase histochemistry. Nitrergic neurons comprised similar proportions of myenteric neurons, about 30%, in all gastric regions. Small numbers of nitrergic neurons occurred in submucosal ganglia. In total, there were ~ 125,000 neuronal nitric oxide synthase (nNOS) neurons in the stomach. The myenteric cell bodies had single axons, type I morphology and a wide range of sizes. Five targets were identified, the longitudinal, circular and oblique layers of the external muscle, the muscularis mucosae and arteries within the gastric wall. The circular and oblique muscle layers had nitrergic fibres throughout their thickness, while the longitudinal muscle was innervated at its inner surface by fibres of the tertiary plexus, a component of the myenteric plexus. There was a very dense innervation of the pyloric sphincter, adjacent to the duodenum. The muscle strands that run between mucosal glands rarely had closely associated nNOS nerve fibres. Both nNOS immunohistochemistry and NADPH histochemistry showed that nitrergic terminals did not provide baskets of terminals around myenteric neurons. Thus, the nitrergic neuron populations in the stomach supply the muscle layers and intramural arteries, but, unlike in the intestine, gastric interneurons do not express nNOS. The large numbers of nNOS neurons and the density of innervation of the circular muscle and pyloric sphincter suggest that there is a finely graded control of motor function in the stomach by the recruitment of different numbers of inhibitory motor neurons.
Topics: Animals; Myenteric Plexus; Neurons; Nitric Oxide; Nitric Oxide Synthase; Nitric Oxide Synthase Type I; Rats; Stomach; Submucous Plexus
PubMed: 35146560
DOI: 10.1007/s00441-022-03594-0 -
Anatomical Record (Hoboken, N.J. : 2007) Apr 2018Duchenne-like muscular dystrophy (canine dystrophinopathy) is a hereditary degenerative disease characterized by muscle changes similar to those described for Duchenne...
Duchenne-like muscular dystrophy (canine dystrophinopathy) is a hereditary degenerative disease characterized by muscle changes similar to those described for Duchenne muscular dystrophy (DMD) and by alterations in the smooth muscles of the gastrointestinal tract. Some authors have suggested that these abnormalities may be associated with intestinal motility. This study analyzed the nitrergic and cholinergic neurons and P2X7 receptor expression in the myenteric plexus of the ileum and distal colon of dogs with muscular dystrophy. Immunohistochemical techniques were used to detect nitric oxide synthase (NOS) and acetylcholine transferase (ChAT) expression and to label all HuC/D- and P2X7 receptor-immunoreactive (IR) neurons. Transmission electron microscopy and basic histology were performed for further analysis. The results showed that nitrergic neurons exhibited a Dogiel type I morphology in the ileum and distal colon. The neuronal profile results showed that there were fewer NOS-, ChAT-, and HuC/D-IR neurons in the ileum than in the distal colon in the dystrophic (DT) dogs. Additionally, there were more NOS-, ChAT- and HuC/D-IR neurons per ganglion in the distal colon than in the ileum. The P2X7 receptor-expressing neurons colocalized with nitrergic and cholinergic neurons. Transmission and light microscopy revealed collagen between the muscle fibers, between the circular and longitudinal muscle layers and within the myenteric ganglia of dogs with muscular dystrophy. These findings provide a morphological description of the myenteric neurons in the ileum and distal colon of these DT dogs and may contribute to a better understanding of the gastrointestinal disorders found in patients with DMD. Anat Rec, 301:673-685, 2018. © 2017 Wiley Periodicals, Inc.
Topics: Animals; Choline O-Acetyltransferase; Colon; Dog Diseases; Dogs; Ileum; Muscular Dystrophy, Animal; Myenteric Plexus; Neurons; Nitric Oxide Synthase; Receptors, Purinergic P2X7
PubMed: 29059716
DOI: 10.1002/ar.23708 -
Anatomical Record (Hoboken, N.J. : 2007) Aug 2012The longitudinal muscle in the large intestine in humans and some other mammalian species is concentrated in regions known as "tenia coli." The myenteric plexus under...
The longitudinal muscle in the large intestine in humans and some other mammalian species is concentrated in regions known as "tenia coli." The myenteric plexus under the tenia is believed to be highly developed to control the adjacent large muscle mass, however, data on the innervation of this region are very scarce. We used whole mount preparations of human colon to characterize the organization of the myenteric plexus under the tenia coli (UT) and compared it with the plexus between the tenia (BT). Using histochemical staining for NADPH diaphorase, we found that the meshwork UT was 50% denser than BT, and that the ganglia UT were 30% wider. The density and size of the NADPH-d positive neurons UT were similar to those of BT. We conclude that the myenteric plexus UT is considerably more developed than BT, and suggest to understand the control of colonic motility, the myenteric plexus UT needs to be further investigated.
Topics: Adult; Aged; Aged, 80 and over; Colon; Female; Humans; Male; Middle Aged; Myenteric Plexus; NADPH Dehydrogenase
PubMed: 22678779
DOI: 10.1002/ar.22511 -
Neurogastroenterology and Motility Jan 2021The enteric nervous system contains multiple classes of neurons, distinguishable by morphology, immunohistochemical markers, and projections; however, specific...
BACKGROUND
The enteric nervous system contains multiple classes of neurons, distinguishable by morphology, immunohistochemical markers, and projections; however, specific combinations differ between species. Here, types of enteric neurons in human colon were characterized immunohistochemically, using retrograde tracing combined with multiple labeling immunohistochemistry, focussing on non-motor neurons.
METHODS
The fluorescent carbocyanine tracer, DiI, was applied to the myenteric plexus in ex vivo preparations, filling neurons projecting within the plexus. Limits of projection lengths of motor neurons were established, allowing them to be excluded from the analysis. Long ascending and descending interneurons were then distinguished by labeling for discriminating immunohistochemical markers: calbindin, calretinin, enkephalin, 5-hydroxytryptamine, nitric oxide synthase, and substance P. These results were combined with a previous published study in which nitric oxide synthase and choline acetyltransferase immunoreactivities were established.
KEY RESULTS
Long ascending neurons (with projections longer than 8 mm, which excludes more than 95% motor neurons) formed four types, in descending order of abundance, defined by immunoreactivity for: (a) ChAT+/ENK+, (b) ChAT+/ENK+/SP+, (c) ChAT+/Calb+, and (d) ChAT+/ENK+/Calb+. Long descending neurons, up to 70 mm long also formed at least four types, distinguished by immunoreactivity for (a) NOS + cells (without ChAT), (b) ChAT+/NOS+, (c) ChAT+/Calret+, and (d) ChAT+/5HT + cells (with or without NOS).
CONCLUSIONS AND INFERENCES
Long interneurons, which do not innervate muscularis externa, are likely to coordinate neural activity over distances of many centimeters along the colon. Characterizing their neurochemical coding provides a basis for understanding their roles, investigating their connectivity, and building a comprehensive account of human colonic enteric neurons.
Topics: Aged; Calbindin 2; Calbindins; Choline O-Acetyltransferase; Colon; Enkephalins; Female; Humans; Interneurons; Male; Middle Aged; Motor Neurons; Myenteric Plexus; Neurons, Afferent; Neurons, Efferent; Nitric Oxide Synthase; Serotonin; Substance P
PubMed: 32839997
DOI: 10.1111/nmo.13964 -
World Journal of Gastroenterology Apr 2015To assess the effects of ME-49 Toxoplasma gondii (T. gondii) strain infection on the myenteric plexus and external muscle of the jejunum in rats.
AIM
To assess the effects of ME-49 Toxoplasma gondii (T. gondii) strain infection on the myenteric plexus and external muscle of the jejunum in rats.
METHODS
Thirty rats were distributed into two groups: the control group (CG) (n = 15) received 1 mL of saline solution orally, and the infected group (IG) (n = 15) inoculated with 1 mL of saline solution containing 500 oocysts of M-49 T. gondii strain orally. After 36 d of infection, the rats were euthanized. Infection with T. gondii was confirmed by blood samples collected from all rats at the beginning and end of the experiment. The jejunum of five animals was removed and submitted to routine histological processing (paraffin) for analysis of external muscle thickness. The remaining jejunum from the others animals was used to analyze the general population and the NADH-diaphorase, VIPergic and nitrergic subpopulations of myenteric neurons; and the enteric glial cells (S100-IR).
RESULTS
Serological analysis showed that animals from the IG were infected with the parasite. Hypertrophy affecting jejunal muscle thickness was observed in the IG rats (77.02 ± 42.71) in relation to the CG (51.40 ± 12.34), P < 0.05. In addition, 31.2% of the total number of myenteric neurons died (CG: 39839.3 ± 5362.3; IG: 26766.6 ± 2177.6; P < 0.05); hyperplasia of nitrergic myenteric neurons was observed (CG: 7959.0 ± 1290.4; IG: 10893.0 ± 1156.3; P < 0.05); general hypertrophy of the cell body in the remaining myenteric neurons was noted [CG: 232.5 (187.2-286.0); IG: 248.2 (204.4-293.0); P < 0.05]; hypertrophy of the smallest varicosities containing VIP neurotransmitter was seen (CG: 0.46 ± 0.10; IG: 0.80 ± 0.16; P < 0.05) and a reduction of 25.3% in enteric glia cells (CG: 12.64 ± 1.27; IG: 10.09 ± 2.10; P < 0.05) was observed in the infected rats.
CONCLUSION
It was concluded that infection with oocysts of ME-49 T. gondii strain caused quantitative and plastic alterations in the myenteric plexus of the jejunum in rats.
Topics: Animals; Biomarkers; Dihydrolipoamide Dehydrogenase; Disease Models, Animal; Jejunum; Male; Muscle, Smooth; Myenteric Plexus; Neuroglia; Neuronal Plasticity; Nitrergic Neurons; Rats, Wistar; Time Factors; Toxoplasma; Toxoplasmosis; Vasoactive Intestinal Peptide
PubMed: 25944996
DOI: 10.3748/wjg.v21.i16.4829 -
Anatomical Record (Hoboken, N.J. : 2007) Dec 2007The specific patterns of gastrointestinal motility in large herbivores may relate to differences in the organization of enteric nerve circuits, compared with other...
The specific patterns of gastrointestinal motility in large herbivores may relate to differences in the organization of enteric nerve circuits, compared with other mammals. To investigate this possibility, we characterized the morphologies, chemical phenotypes, and projections of myenteric plexus (MP) neurons of the sheep ileum. Morphologies and projections were investigated after application of the carbocyanine dye (1,1', di-octadecyl-3,3,3',3',-tetramethylindo-carbocyanine perchlorate, DiI) to fixed tissues. To study chemical phenotypes, the fluorescent tracer Fast Blue (FB) was injected into the wall of the ileum, in vivo, 12-14 cm oral to the ileo-caecal junction. Over 80% of the descending and ascending DiI-labeled neurons had typical Dogiel type I morphology, whereas only a few Dogiel type II neurons were observed. Nevertheless, there were long projections (up to 10 cm) of Dogiel type II neurons in both directions. Both type II and type I neurons were neurofilament immunoreactive (IR). We observed long projections of descending (up to 18 cm) and ascending (up to 12-14 cm) FB-labeled MP neurons. Nitric oxide synthase (NOS)-IR, peripheral choline acetyltransferase (pChAT)-IR, and substance P (SP)-IR occurred in both descending and ascending myenteric neurons. NOS-IR was in approximately 60% of FB-labeled descending and ascending neurons, whereas those expressing pChAT-IR were 67 +/- 15% and 60 +/- 14%, respectively. Descending neurons expressing SP-IR were 48 +/- 15% and ascending were 56 +/- 12%. NOS-IR and pChAT-IR, and SP-IR and pChAT-IR were commonly colocalized in both ascending and descending pathways. In descending pathways, almost all SP-IR neurons were also pChAT-IR (98 +/- 3%) and NOS-IR (99 +/- 2 NOS(+)/SP(+)/pChAT(-)). Many FB-labeled descending neurons showed both NOS- and pChAT-IR. Descending neurons may represent inhibitory motor neurons (NOS(+)/SP(+)/pChAT(-)) and two classes of interneurons (pChAT(+)/NOS(-), and pChAT(+)/NOS(+)/SP(+)). In ascending pathways, most neurons are pChAT(+)/NOS(+)/SP(+). Thus, in sheep, ascending interneurons and ascending excitatory motor neurons both have the same phenotype, and other markers are needed to distinguish them.
Topics: Amidines; Animals; Carbocyanines; Choline O-Acetyltransferase; Gastrointestinal Motility; Ileum; Immunohistochemistry; Myenteric Plexus; Neurons; Nitric Oxide Synthase; Phenotype; Sheep; Substance P
PubMed: 17972278
DOI: 10.1002/ar.20615 -
The Journal of Physiology Oct 2022
Topics: Gastrointestinal Motility; Myenteric Plexus
PubMed: 35980322
DOI: 10.1113/JP283624 -
Folia Morphologica Aug 2013Oesophagus is a muscular tube that transports food and liquids by coordinated contraction of its muscular lining led by stimuli from the nerve plexus. Its muscularis...
BACKGROUND
Oesophagus is a muscular tube that transports food and liquids by coordinated contraction of its muscular lining led by stimuli from the nerve plexus. Its muscularis proper layer consists of muscle cells, connective tissue and myenteric plexus. The aim of our histomorphometric study was to reveal detailed characteristics of this layer, cell number, volume, orientation, properties of myenteric plexus as well as changes related to aging.
MATERIALS AND METHODS
Oesophagus tissue samples from 17 male cadavers were taken from the cranial and thoracic parts. Samples were divided in 2 groups: younger(ages 21-45) and older (ages 66-78). The tissue was routinely processed,embedded and serially sectioned. Sections were stained with Masson-Goldner and Cresyl-violet dyes. Digital images were analysed with the image analysis software.Statistics were performed with SPSS software.
RESULTS
The average thickness of the cranial part of the oesophageal wall and muscularis proper was 2590 μm and 1197 μm, respectively in the younger and 2453 μm and 1144 μm in the older group. Overall volume of the muscle tissue was slightly larger in the thoracic part, and in the younger group compared to the cranial part and the older group. The average number of the striated muscle cells per 100 μm in the cranial part was 771.5 and 749.7 in the younger and the older group, respectively. Striated cells were significantly less present only in the lower thoracic part of the oesophagus. In the older group,smaller striated muscle cells dominated over the larger ones. In the younger group, majority of the striated muscle cells were mid-sized. The thickness of the circular layer of muscularis proper was more affected by aging than the longitudinal one. Ganglion cells number was lower in the older group, but plexus area was unchanged.
CONCLUSIONS
Aging affects muscularis proper and myenteric plexus of the oesophagus.Major differences can be observed in the striated muscle cells size, volume of the circular layer and number of the ganglionic cells in the myenteric plexus.
Topics: Adult; Age Factors; Aged; Esophagus; Humans; Male; Middle Aged; Muscle, Smooth; Myenteric Plexus; Young Adult
PubMed: 24068684
DOI: 10.5603/fm.2013.0037 -
Proceedings of the National Academy of... Oct 2021Glia in the central nervous system exert precise spatial and temporal regulation over neural circuitry on a synapse-specific basis, but it is unclear if peripheral glia...
Glia in the central nervous system exert precise spatial and temporal regulation over neural circuitry on a synapse-specific basis, but it is unclear if peripheral glia share this exquisite capacity to sense and modulate circuit activity. In the enteric nervous system (ENS), glia control gastrointestinal motility through bidirectional communication with surrounding neurons. We combined glial chemogenetics with genetically encoded calcium indicators expressed in enteric neurons and glia to study network-level activity in the intact myenteric plexus of the proximal colon. Stimulation of neural fiber tracts projecting in aboral, oral, and circumferential directions activated distinct populations of enteric glia. The majority of glia responded to both oral and aboral stimulation and circumferential pathways, while smaller subpopulations were activated only by ascending and descending pathways. Cholinergic signaling functionally specifies glia to the descending circuitry, and this network plays an important role in repressing the activity of descending neural pathways, with some degree of cross-inhibition imposed upon the ascending pathway. Glial recruitment by purinergic signaling functions to enhance activity within ascending circuit pathways and constrain activity within descending networks. Pharmacological manipulation of glial purinergic and cholinergic signaling differentially altered neuronal responses in these circuits in a sex-dependent manner. Collectively, our findings establish that the balance between purinergic and cholinergic signaling may differentially control specific circuit activity through selective signaling between networks of enteric neurons and glia. Thus, enteric glia regulate the ENS circuitry in a network-specific manner, providing profound insights into the functional breadth and versatility of peripheral glia.
Topics: Animals; Cell Communication; Enteric Nervous System; Female; Gastrointestinal Motility; Male; Mice; Myenteric Plexus; Neuroglia; Neurons; Signal Transduction
PubMed: 34593632
DOI: 10.1073/pnas.2025938118 -
American Journal of Physiology.... Apr 2017Neuronal and inducible nitric oxide synthase (nNOS and iNOS) play a protective and damaging role, respectively, on the intestinal neuromuscular function after...
Neuronal and inducible nitric oxide synthase (nNOS and iNOS) play a protective and damaging role, respectively, on the intestinal neuromuscular function after ischemia-reperfusion (I/R) injury. To uncover the molecular pathways underlying this dichotomy we investigated their possible correlation with the orthodenticle homeobox proteins OTX1 and OTX2 in the rat small intestine myenteric plexus after in vivo I/R. Homeobox genes are fundamental for the regulation of the gut wall homeostasis both during development and in pathological conditions (inflammation, cancer). I/R injury was induced by temporary clamping the superior mesenteric artery under anesthesia, followed by 24 and 48 h of reperfusion. At 48 h after I/R intestinal transit decreased and was further reduced by -propyl-l-arginine hydrochloride (NPLA), a nNOS-selective inhibitor. By contrast this parameter was restored to control values by 1400W, an iNOS-selective inhibitor. In longitudinal muscle myenteric plexus (LMMP) preparations, iNOS, OTX1, and OTX2 mRNA and protein levels increased at 24 and 48 h after I/R. At both time periods, the number of iNOS- and OTX-immunopositive myenteric neurons increased. nNOS mRNA, protein levels, and neurons were unchanged. In LMMPs, OTX1 and OTX2 mRNA and protein upregulation was reduced by 1400W and NPLA, respectively. In myenteric ganglia, OTX1 and OTX2 staining was superimposed with that of iNOS and nNOS, respectively. Thus in myenteric ganglia iNOS- and nNOS-derived NO may promote OTX1 and OTX2 upregulation, respectively. We hypothesize that the neurodamaging and neuroprotective roles of iNOS and nNOS during I/R injury in the gut may involve corresponding activation of molecular pathways downstream of OTX1 and OTX2. Intestinal ischemia-reperfusion (I/R) injury induces relevant alterations in myenteric neurons leading to dismotility. Nitrergic neurons seem to be selectively involved. In the present study the inference that both neuronal and inducible nitric oxide synthase (nNOS and iNOS) expressing myenteric neurons may undergo important changes sustaining derangements of motor function is reinforced. In addition, we provide data to suggest that NO produced by iNOS and nNOS regulates the expression of the vital transcription factors orthodenticle homeobox protein 1 and 2 during an I/R damage.
Topics: Animals; Arginine; Gastrointestinal Transit; Intestine, Small; Male; Myenteric Plexus; Neurons; Nitric Oxide; Nitric Oxide Synthase Type I; Otx Transcription Factors; Rats; Rats, Wistar; Reperfusion Injury
PubMed: 28154013
DOI: 10.1152/ajpgi.00386.2016