Corticotropin releasing factor in the rat colon: Expression, localization and upregulation by endotoxin (original) (raw)
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The Journal of Comparative Neurology, 2006
Immunofluorescence was used to study immunoreactivity (IR) for corticotropin releasing factor (CRF) in the guinea-pig enteric nervous system. CRF-IR was expressed in both the myenteric and submucosal plexuses of all regions of the large and small intestine and the myenteric plexus of the stomach. CRF-IR-nerve fibers were present in the myenteric and submucosal plexuses, in the circular muscle coat and surrounding submucosal arterioles. Most of the CRF-IR fibers persisted in the myenteric and submucosal plexuses after 7 days in organotypic culture. CRF-IR was not coexpressed with tyrosine hydroxylase-IR or calcitonin gene-related peptide-IR fibers. The proportions of CRF-IR cell bodies in the myenteric plexus increased progressively from the stomach (0.6%) to the distal colon (2.8%). Most of the CRF-IR myenteric neurons (95%) had uniaxonal morphology; the remainder had Dogiel type II multipolar morphology. CRF-IR cell bodies in the myenteric plexus of the ileum expressed IR for choline acetyltransferase (56.9%), substance P (55.0%), and nitric oxide synthase (37.9%). CRF-IR never co-localized with IR for calbindin, calretinin, neuropeptide Y, serotonin or somatostatin in the myenteric plexus. CRF-IR cell bodies were more abundant in the submucosal plexus (29.9-38.0%) than in the myenteric plexus. All CRF-IR neurons in submucosal ganglia expressed vasoactive intestinal peptide-IR and were likely to be secretomotor/vasodilator neurons. CRF-IR neurons did not express IR for the CRF 1 receptor. CRF 1-IR was expressed in neuronal neighbors of those with CRF-IR. Collective evidence suggests that VIPergic secretomotor neurons might provide synaptic input to neighboring cholinergic neurons.
Neurogastroenterology and motility : the official journal of the European Gastrointestinal Motility Society, 2010
BACKGROUND A growing body of data implicates increased life stresses with the initiation, persistence and severity of symptoms associated with functional gut disorders such as irritable bowel syndrome (IBS). Activation of central and peripheral corticotropin-releasing factor (CRF) receptors is key to stress-induced changes in gastrointestinal (GI) function. METHODS This study utilised immunofluorescent and Western blotting techniques to investigate colonic expression of CRF receptors in stress-sensitive Wistar Kyoto (WKY) and control Sprague Dawley (SD) rats. KEY RESULTS No intra-strain differences were observed in the numbers of colonic CRFR1 and CRFR2 positive cells. Protein expression of functional CRFR1 was found to be comparable in control proximal and distal colon samples. Sham levels of CRFR1 were also similar in the proximal colon but significantly higher in WKY distal colons (SD: 0.38 +/- 0.14, WKY: 2.06 +/- 0.52, P < 0.01). Control levels of functional CRFR2 were simila...
Journal of neurogastroenterology and motility, 2015
The corticotropin-releasing factor (CRF) signaling systems encompass CRF and the structurally related peptide urocortin (Ucn) 1, 2, and 3 along with 2 G-protein coupled receptors, CRF₁ and CRF₂. CRF binds with high and moderate affinity to CRF₁ and CRF₂ receptors, respectively while Ucn1 is a high-affinity agonist at both receptors, and Ucn2 and Ucn3 are selective CRF₂ agonists. The CRF systems are expressed in both the brain and the colon at the gene and protein levels. Experimental studies established that the activation of CRF₁ pathway in the brain or the colon recaptures cardinal features of diarrhea predominant irritable bowel syndrome (IBS) (stimulation of colonic motility, activation of mast cells and serotonin, defecation/watery diarrhea, and visceral hyperalgesia). Conversely, selective CRF1 antagonists or CRF₁/CRF₂ antagonists, abolished or reduced exogenous CRF and stress-induced stimulation of colonic motility, defecation, diarrhea and colonic mast cell activation and vi...
American journal of physiology. Gastrointestinal and liver physiology, 2016
Urocortin 1, 2 and 3 (Ucns) and corticotropin releasing factor receptor 2 (CRF2) are prominently expressed in various layers of the upper gut while current knowledge of their expression and regulation in the colonic layers are limited. We investigated Ucns and CRF2 isoforms expression by RT-PCR in the proximal colon separated into mucosa and submucosa plus muscle (S+M), or in laser captured layers, their regulations by lipopolysaccharide (LPS, 100 μg/kg ip) and the effects of the CRF2 antagonist astresssin2-B on colonic immune response to LPS in rats. Transcripts of Ucns and CRF2b, the most common wild-type isoform in the periphery, were detected in all layers including myenteric neurons. LPS increased Ucn 1, Ucn 2 or Ucn 3 mRNA and decreased CRF2b mRNA levels in both colonic mucosa and S+M layers at 2, 6, 9 h after injection with a return to the basal level at 24 h. In addition, CRF2a, another wild-type isoform more prominently in the CNS, and a novel truncated splice variant CRF2a...
American Journal of Physiology-Gastrointestinal and Liver Physiology, 2009
Corticotropin-releasing factor (CRF) 1 receptor (CRF1) activation in the brain is a core pathway orchestrating the stress response. Anatomical data also support the existence of CRF signaling components within the colon. We investigated the colonic response to intraperitoneal (ip) injection of cortagine, a newly developed selective CRF1 peptide agonist. Colonic motor function and visceral motor response (VMR) were monitored by using a modified miniaturized pressure transducer catheter in adult conscious male Sprague-Dawley rats and C57Bl/6 mice. Colonic permeability was monitored by the Evans blue method and myenteric neurons activation by Fos immunohistochemistry. Compared with vehicle, cortagine (10 μg/kg ip) significantly decreased the distal colonic transit time by 45% without affecting gastric transit, increased distal and transverse colonic contractility by 35.6 and 66.2%, respectively, and induced a 7.1-fold increase in defecation and watery diarrhea in 50% of rats during the...
American journal of physiology. Gastrointestinal and liver physiology, 2002
Corticotropin-releasing factor (CRF) injected peripherally induces clustered spike-burst activity in the proximal colon through CRF(1) receptors in rats. We investigated the effect of intraperitoneal CRF on proximal colon ganglionic myenteric cell activity in conscious rats using Fos immunohistochemistry on the colonic longitudinal muscle/myenteric plexus whole mount preparation. In vehicle-pretreated rats, there were only a few Fos immunoreactive (IR) cells per ganglion (1.2 +/- 0.6). CRF (10 microg/kg ip) induced Fos expression in 19.6 +/- 2.1 cells/ganglion. The CRF(1)/CRF(2) antagonist astressin (33 microg/kg ip) and the selective CRF(1) antagonist CP-154,526 (20 mg/kg sc) prevented intraperitoneal CRF-induced Fos expression in the proximal colon (number of Fos-IR cells/ganglion: 2.7 +/- 1.2 and 1.0 +/- 1.0, respectively), whereas atropine (1 mg/kg sc) had no effect. Double labeling of Fos with protein gene product 9.5 revealed the neuronal identity of activated cells that were ...
CRF receptor type 1 and 2 expression and anatomical distribution in the rat colon
Journal of Neurochemistry, 2004
Corticotropin-releasing factor (CRF) receptor agonists administered peripherally increase colonic propulsive motility and fecal output in experimental animals. In addition, endogenous CRF-related peptides are found in the lower gastrointestinal (GI) tissues, suggesting a local expression of CRF receptors. In the present study, we report the expression of both CRF receptor type 1 (CRF 1 ) and 2 (CRF 2 ) in the rat colon at the mRNA and protein levels. For the purpose of receptor protein mapping, a specific antiserum against the C-terminus of CRF 2 (2064a-CRF 2 ) was generated and characterized. This antiserum in conjunction with a selective anti-CRF 1 antiserum (4467a-CRF 1 ) was used in immunofluorescent staining to demonstrate the anatomical distribution of receptor protein expression. Using RT-PCR for the CRF 1 and CRF 2 genes, both receptor gene transcripts were found in RNA isolated from crude colonic samples. CRF 1 was found in the goblet and stem cells of the colonic crypts and in scattered cells of the surface epithelium and the lamina propria of the proximal colonic mucosa. In addition, double staining against neuron-specific antigens revealed CRF 1 expression in the myenteric and submucosal nervous plexus. CRF 2 expression was localized mainly in the luminal surface of the crypts and in blood vessels of the submucosal layer. These results demonstrate expression of both CRF receptor types in the rat colon and support a role for their involvement in regulating peripheral effects of CRF ligands.
Corticotropin-releasing hormone mimics stress-induced colonic epithelial pathophysiology in the rat
American journal of physiology. Gastrointestinal and liver physiology, 1999
We examined the effect of stress on colonic epithelial physiology, the role of corticotropin-releasing hormone (CRH), and the pathways involved. Rats were restrained or injected intraperitoneally with CRH or saline. Colonic segments were mounted in Ussing chambers, in which ion secretion and permeability (conductance and probe fluxes) were measured. To test the pathways involved in CRH-induced changes, rats were pretreated with hexamethonium, atropine, bretylium, doxantrazole, α-helical CRH-(9-41) (all intraperitoneally), or aminoglutethimide (subcutaneously). Restraint stress increased colonic ion secretion and permeability to ions, the bacterial peptide FMLP, and horseradish peroxidase (HRP). These changes were prevented by α-helical CRH-(9-41) and mimicked by CRH (50 μg/kg). CRH-induced changes in ion secretion were abolished by α-helical CRH-(9-41), hexamethonium, atropine, or doxantrazole. CRH-stimulated conductance was significantly inhibited by α-helical CRH-(9-41), hexametho...
Role of Corticotropin-releasing Factor in Gastrointestinal Permeability
Journal of Neurogastroenterology and Motility, 2015
The interface between the intestinal lumen and the mucosa is the location where the majority of ingested immunogenic particles face the scrutiny of the vast gastrointestinal immune system. Upon regular physiological conditions, the intestinal microflora and the epithelial barrier are well prepared to process daily a huge amount of food-derived antigens and non-immunogenic particles. Similarly, they are ready to prevent environmental toxins and microbial antigens to penetrate further and interact with the mucosal-associated immune system. These functions promote the development of proper immune responses and oral tolerance and prevent disease and inflammation. Brain-gut axis structures participate in the processing and execution of response signals to external and internal stimuli. The brain-gut axis integrates local and distant regulatory networks and supersystems that serve key housekeeping physiological functions including the balanced functioning of the intestinal barrier. Disturbance of the brain-gut axis may induce intestinal barrier dysfunction, increasing the risk of uncontrolled immunological reactions, which may indeed trigger transient mucosal inflammation and gut disease. There is a large body of evidence indicating that stress, through the brain-gut axis, may cause intestinal barrier dysfunction, mainly via the systemic and peripheral release of corticotropin-releasing factor. In this review, we describe the role of stress and corticotropin-releasing factor in the regulation of gastrointestinal permeability, and discuss the link to both health and pathological conditions. (J Neurogastroenterol Motil 2015;21:33-50)
Journal of Pharmacology and Experimental Therapeutics, 2002
Peripheral CRF inhibits gastric emptying and stimulates colonic motor function in rats. We investigated the role of CRF 1 and CRF 2 receptors in i.p. CRF-induced alterations of gut transit in conscious mice using selective CRF 1 and CRF 2 ligands injected i.p. Gastric emptying 2 h after ingestion of a solid chow meal and colonic transit (time to expel a bead inserted into the distal colon) were determined simultaneously. Rat/human (r/ h)CRF, which has CRF 1 Ͼ CRF 2 binding affinity, decreased distal colonic transit time at lower doses (6-12 g/kg) than those inhibiting gastric emptying (20-60 g/kg). Ovine CRF, a preferential CRF 1 receptor agonist (6-60 g/kg), reduced significantly the colonic transit time without altering gastric emptying, whereas the selective CRF 2 receptor agonists mouse urocortin II (20-60 g/kg) and urocortin III (120 g/kg) inhibited significantly gastric emptying without modifying colonic transit. The CRF 1 /CRF 2 receptor antagonist, astressin (30-120 g/kg), dose dependently prevented r/hCRF (20 g/kg)-induced inhibition of gastric emptying and reduction of colonic transit time. The selective CRF 1 receptor antagonists, NBI-27914 (C 18 H 20 Cl 4 N 4 C 7 H 8 O 3 S) and CP-154,526 (butyl-[2,5-dimethyl-7-(2,4,6-trimethylphenyl)-7H-pyrrolo[2,3-d]pyrimidin-4-yl]ethylamine) (5-30 mg/kg), dose dependently blocked r/hCRF action on the colon without influencing the gastric response, whereas the CRF 2 receptor antagonist, antisauvagine-30 (30-100 g/ kg), dose dependently abolished r/hCRF-induced delayed gastric emptying and had no effect on colonic response. These data show that i.p. r/hCRF-induced opposite actions on upper and lower gut transit in conscious mice are mediated by different CRF receptor subtypes: the activation of CRF 1 receptors stimulates colonic propulsive activity, whereas activation of CRF 2 receptors inhibits gastric emptying.