CRF receptor type 1 and 2 expression and anatomical distribution in the rat colon (original) (raw)
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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 ...
American Journal of Physiology-regulatory Integrative and Comparative Physiology, 2006
Corticotropin releasing factor (CRF) is one of the most important factors in the mechanism of stress-induced stimulation of colonic motility. However, it is controversial whether stress-induced stimulation of colonic motility is mediated via central or peripheral CRF receptors. We investigated the hypothesis that peripherally injected CRF accelerates colonic motility through the central CRF receptor, but not the peripheral CRF receptor. A strain gauge transducer was sutured on the serosal surface of the proximal colon. Colonic motility was monitored before and after the peripheral injection of CRF. An in vitro muscle strip study was also performed to investigate the peripheral effects of CRF. Subcutaneous injection of CRF (30-100 g/kg) stimulated colonic motility in a dose-dependent manner. The stimulatory effect of peripherally administered CRF on colonic motility was abolished by truncal vagotomy, hexamethonium, atropine, and intracisternal injection of astressin (a CRF receptor antagonist). No responses to CRF (10 Ϫ9 Ϫ10 Ϫ7 M) of the muscle strips of the proximal colon were observed. These results suggest that the stimulatory effect of colonic motility in response to peripheral administration of CRF is mediated by the vagus nerve, nicotinic receptors, muscarinic receptors, and CRF receptors of the brain stem. It is concluded that peripherally administered CRF reaches the area postrema and activates the dorsal nucleus of vagi via central CRF receptors, resulting in stimulation of the vagal efferent and cholinergic transmission of the proximal colon.
Brain Research, 2005
Corticotropin-releasing factor (CRF) receptors have been reported to play a role in tonic colorectal distension (CRD)-induced activation of locus coeruleus (LC) neurons. We examined the influence of repeated phasic CRDs and intracisternal (ic) CRF on the spontaneous discharge rate of LC neurons in chloral hydrate-anesthetized rats and the role of CRF receptors using the nonselective CRF 1 /CRF 2 antagonist, astressin, and the water-soluble CRF 1 receptor antagonist, NBI-35965. Two consecutive phasic CRDs (43.7 T 1.1 mm Hg, 30 s each) at a 10-min interval increased LC activity to 184.9 T 15% and 171.9 T 12.2%, respectively. There was no difference in magnitude, onset (within 1 s), and duration (5-7 min) of the LC responses between the 1st and 2nd CRDs. CRF (300 ng/rat, ic) injected 10 min after the 2nd CRD increased LC activity to 191.1 T 11.2%. Astressin (3 Ag, ic) completely blocked the 2nd CRD-and ic CRF-induced LC activation. Neither ic vehicle nor astressin influenced basal LC neuronal activity. NBI-35965 (10 mg/kg, iv) prevented the 2nd CRD-and ic CRF-induced LC neuronal activation, while at 5 mg significantly reduced the LC response to the 2nd CRD by 80%, but did not block that of ic CRF injected 30 min later. These findings indicate a primary role of brain CRF interacting with CRF 1 receptors in mediating the activation of LC neurons in response to a phasic CRD within the nociceptive range (>40 mm Hg). This activation may have relevance to irritable bowel syndrome characterized by lower pain threshold to CRD and hypervigilance to colonic input.
Neurogastroenterology & Motility, 2008
Meconium passage is frequently observed in association with feto-maternal stress factors such as hypoxia and infection, but the triggering mechanism is unknown. We hypothesize that differential regulation of corticotrophin-releasing factor (CRF) receptors during gestation play an important role in determining the susceptibilities of the fetus to stress-induced in utero meconium passage at term. We examined the innervation patterns of CRF-receptor type 1 (CRF-R1), a stimulator of gastrointestinal motility and CRFreceptor type II (CRF-R2), an inhibitor of gastrointestinal motility in ovine fetal distal colonic segments from very preterm to term gestation. Both CRF-R1 and CRF-R2 receptors were present in muscularis mucosa as well as in longitudinal and circular smooth muscle layers in fetal distal colonic segments at all gestational ages. Quantitative image analysis indicated a 42% increase in CRF-R1 receptor immunoreactivity in muscularis mucosa and a 30% in longitudinal smooth muscle layers from very preterm to term. In contrast, CRF-R2 receptor immunoreactivity in muscularis mucosa as well as in longitudinal and circular smooth muscle layers decreased by 38%, 55% and 51%, respectively, at term. The percentage of enteric ganglia and the number of enteric neurons expressing CRF-R1 receptors were high at term. Western blot analysis identified 235 and 50 kDa molecular species of CRF-R1 receptors and 37 and 28 kDa molecular species of CRF-R2 receptors. In summary, we speculate that downregulation of CRF-R2 receptor abundance with concurrent increases in CRF-R1 receptor levels in myenteric-smooth muscle unit with advancing gestation sensitizes the colonic motility responses to stressors.
Peptides, 2010
Little is known about CRF expression and regulation in the rat colon compared to the brain. We investigated CRF gene expression, cellular location, and regulation by endotoxin and corticosterone in the male rat colon at 6 h after intraperitoneal (ip) injection. CRF mRNA level, detected by reverse transcription-polymerase chain reaction (RT-PCR) was 1.3-fold higher in the distal than proximal colon and 3.4-fold higher in the proximal colonic submucosa plus muscle layers than in mucosa. CRF immunoreactivity was located in the epithelia, lamina propria and crypts, and co-localized with tryptophan hydroxylase, a marker for enterochromaffin (EC) cells, and in enteric neurons. Lipopolysaccharide (LPS, 100 mg/kg, ip) increased defecation by 2.9-fold and upregulated CRF mRNA
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.
The Journal of physiology, 2004
Recently characterized selective agonists and developed antagonists for the corticotropin releasing factor (CRF) receptors are new tools to investigate stress-related functional changes. The influence of mammalian CRF and related peptides injected intracerebroventricularly (i.c.v.) on gastric and colonic motility, and the CRF receptor subtypes involved and their role in colonic response to stress were studied in conscious mice. The CRF(1)/CRF(2) agonists rat urocortin 1 (rUcn 1) and rat/human CRF (r/h CRF), the preferential CRF(1) agonist ovine CRF (oCRF), and the CRF(2) agonist mouse (m) Ucn 2, injected i.c.v. inhibited gastric emptying and stimulated distal colonic motor function (bead transit and defecation) while oCRF(9-33)OH (devoid of CRF receptor affinity) showed neither effects. mUcn 2 injected peripherally had no colonic effect. The selective CRF(2) antagonist astressin(2)-B (i.c.v.), at a 20 : 1 antagonist: agonist ratio, blocked i.c.v. r/hCRF and rUcn 1 induced inhibition...
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, 2018
We investigated whether vasoactive intestinal peptide (VIP) and/or prostaglandins contribute to peripheral corticotropin-releasing factor (CRF)-induced CRF receptor-mediated stimulation of colonic motor function and diarrhea in rats. The VIP antagonist, [4Cl-D-Phe, Leu]VIP injected intraperitoneally completely prevented CRF (10 µg/kg ip)-induced fecal output and diarrhea occurring within the first hour after injection, whereas pretreatment with the prostaglandins synthesis inhibitor, indomethacin, had no effect. In submucosal plexus neurons, CRF induced significant c-Fos expression most prominently in the terminal ileum compared with duodenum and jejunum, whereas no c-Fos was observed in the proximal colon. c-Fos expression in ileal submucosa was colocalized in 93.4% of VIP-positive neurons and 31.1% of non-VIP-labeled neurons. CRF receptor immunoreactivity was found on the VIP neurons. In myenteric neurons, CRF induced only a few c-Fos-positive neurons in the ileum and a robust exp...