Homeoprotein OTX1 and OTX2 involvement in rat myenteric neuron adaptation after DNBS-induced colitis

Background Inflammatory bowel diseases are associated with remodeling of neuronal circuitries within the enteric nervous system, occurring also at sites distant from the acute site of inflammation and underlying disturbed intestinal functions. Homeoproteins orthodenticle OTX1 and OTX2 are neuronal transcription factors participating to adaptation during inflammation and underlying tumor growth both in the central nervous system and in the periphery. In this study, we evaluated OTX1 and OTX2 expression in the rat small intestine and distal colon myenteric plexus after intrarectal dinitro-benzene sulfonic (DNBS) acid-induced colitis. Methods OTX1 and OTX2 distribution was immunohistochemically investigated in longitudinal muscle myenteric plexus (LMMP)-whole mount preparations. mRNAs and protein levels of both OTX1 and OTX2 were evaluated by qRT-PCR and Western blotting in LMMPs. Results DNBS-treatment induced major gross morphology and histological alterations in the distal colon, while the number of myenteric neurons was significantly reduced both in the small intestine and colon. mRNA levels of the inflammatory markers, TNFα, pro-IL1β, IL6, HIF1α and VEGFα and myeloperoxidase activity raised in both regions. In both small intestine and colon, an anti-OTX1 antibody labeled a small percentage of myenteric neurons, and prevalently enteric glial cells, as evidenced by co-staining with the glial marker S100β. OTX2 immunoreactivity was present only in myenteric neurons and was highly co-localized with neuronal nitric oxide synthase. Both in the small intestine and distal colon, the number of OTX1- and OTX2-immunoreactive myenteric neurons significantly increased after DNBS treatment. In these conditions, OTX1 immunostaining was highly superimposable with inducible nitric oxide synthase in both regions. OTX1 and OTX2 mRNA and protein levels significantly enhanced in LMMP preparations of both regions after DNBS treatment. Conclusions These data suggest that colitis up-regulates OTX1 and OTX2 in myenteric plexus both on site and distantly from the injury, potentially participating to inflammatory-related myenteric ganglia remodeling processes involving nitrergic transmission.

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Notable postnatal alterations in the myenteric plexus of normal human bowel

Gut ◽

10.1136/gut.44.5.666 ◽

1999 ◽

Vol 44 (5) ◽

pp. 666-674 ◽

Cited By ~ 84

Author(s):

T Wester ◽

D S O’Briain ◽

P Puri

Keyword(s):

Nitric Oxide ◽

Nervous System ◽

Nitric Oxide Synthase ◽

Enteric Nervous System ◽

Myenteric Plexus ◽

Nadph Diaphorase ◽

Intestinal Neuronal Dysplasia ◽

Neuronal Marker ◽

Normal Human ◽

Oxide Synthase

BACKGROUNDNitric oxide is the most important transmitter in non-adrenergic non-cholinergic nerves in the human gastrointestinal tract. Impaired nitrergic innervation has been described in Hirschsprung’s disease, hypertrophic pyloric stenosis, and intestinal neuronal dysplasia (IND). Recent findings indicate that hyperganglionosis, one of the major criteria of IND, is age dependent. However, information is scanty regarding the neurone density in normal human bowel in the paediatric age group.AIMSTo determine neurone density, morphology, and nitric oxide synthase distribution of the normal myenteric plexus at different ages during infancy and childhood.METHODSSpecimens were obtained from small bowel and colon in 20 children, aged one day to 15 years, at postmortem examination. Whole mount preparations were made of the myenteric plexus, which were subsequently stained using NADPH diaphorase histochemistry (identical to nitric oxide synthase) and cuprolinic blue (a general neuronal marker). The morphology of the myenteric plexus was described and the neurone density estimated.RESULTSThe myenteric plexus meshwork becomes less dense during the first years of life. The density of ganglion cells in the myenteric plexus decreases significantly with age during the first three to four years of life. The NADPH diaphorase positive (nitrergic) subpopulation represents about 34% of all neurones in the myenteric plexus.CONCLUSIONSThe notable decrease in neurone density in the myenteric plexus during the first years of life indicates that development is still an ongoing process in the postnatal enteric nervous system. Applied to the clinical situation, this implies that interpretation of enteric nervous system pathology is dependent on the age of the patient.

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Nitric oxide regulates homeoprotein OTX1 and OTX2 expression in the rat myenteric plexus after intestinal ischemia-reperfusion injury

AJP Gastrointestinal and Liver Physiology ◽

10.1152/ajpgi.00386.2016 ◽

2017 ◽

Vol 312 (4) ◽

pp. G374-G389 ◽

Cited By ~ 20

Author(s):

Viviana Filpa ◽

Elisa Carpanese ◽

Silvia Marchet ◽

Cristina Pirrone ◽

Andrea Conti ◽

...

Keyword(s):

Nitric Oxide ◽

Myenteric Plexus ◽

Intestinal Ischemia ◽

Ischemia Reperfusion ◽

Myenteric Neurons ◽

Protein Levels ◽

Intestinal Ischemia Reperfusion ◽

Oxide Synthase ◽

Myenteric Ganglia ◽

Inducible Nitric Oxide

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 Nω-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. NEW & NOTEWORTHY 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.

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Analysis of connections between nitric oxide synthase neurons in the myenteric plexus of the guinea-pig small intestine

Journal of Neurocytology ◽

10.1007/bf01186538 ◽

1995 ◽

Vol 24 (4) ◽

pp. 257-263 ◽

Cited By ~ 28

Author(s):

H. M. Young ◽

J. B. Furness ◽

J. M. Povey

Keyword(s):

Nitric Oxide ◽

Small Intestine ◽

Nitric Oxide Synthase ◽

Guinea Pig ◽

Myenteric Plexus ◽

Oxide Synthase

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Sulphydryl blocker induced small intestinal inflammation in rats: a new model mimicking Crohn’s disease

Gut ◽

10.1136/gut.41.3.358 ◽

1997 ◽

Vol 41 (3) ◽

pp. 358-365 ◽

Cited By ~ 22

Author(s):

D Rachmilewitz ◽

E Okon ◽

F Karmeli

Keyword(s):

Nitric Oxide ◽

Body Weight ◽

Small Intestine ◽

Crohn’S Disease ◽

Nitric Oxide Synthase ◽

Crohn's Disease ◽

Inflammatory Mediators ◽

Myeloperoxidase Activity ◽

Oxide Synthase ◽

Nitric Oxide Synthase Activity

Background—Sulphydryl compounds are essential for maintaining mucosal integrity in the gastrointestinal tract.Aim—To characterise a model of experimental inflammation in the small intestine induced by a sulphydryl blocker.Methods—Inflammation in the small intestine was induced in rats by intrajejunal administration of 0.1 ml 2% iodoacetamide. The possible amelioration of the damage induced was modulated by intragastric administration of TEMPOL (4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl; 50 mg/100 g body weight), ketotifen (200 μg/100 g body weight) or by addition ofl-NAME (NG-nitro-l-arginine methyl ester; 0.1 mg/ml) or apocynin (120 μg/ml) to the drinking water. Rats were sacrificed at various time intervals, the small intestine resected, weighed, macroscopic lesions were assessed, and mucosal generation of inflammatory mediators and nitric oxide synthase activity were determined.Results—Intrajejunal administration of iodoacetamide induced, after one week, multifocal mucosal erosions, ulcerations with granulomas and giant Langhans cells. At two weeks, the mucosa was almost macroscopically intact but histologically epithelial granuloma and giant cells were present. Myeloperoxidase activity was increased in the first 24 hours, one week later mucosal nitric oxide synthase activity and generation of leukotriene B4, leukotriene C4 and thromboxane B2 were increased, whereas prostaglandin E2 generation was decreased notably. Ketotifen and apocynin significantly decreased the extent of injury which was not affected by TEMPOL orl-NAME.Conclusions—Jejunal inflammation induced by the sulphydryl blocker, iodoacetamide, resembles the pathological changes in Crohn’s disease. The protective effect of ketotifen and apocynin indicates the contribution of O2− and pro-inflammatory mediators to the pathogenesis of the damage, and may be a novel approach to the treatment of inflammatory bowel disease.

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