- Email: [email protected]
139 The Mechanism of Intestinal Barrier Dysfunction Induced by Bowel Manipulation in a Model for Postoperative Ileus
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CRF2-/- mice and their WT littermates at baseline. By contrast, after 10 days of exposure to repeated PRS, CRD-induced VMR was increased (p<0.05) at 40 mmHg (+99%) and 60 mmHg (+69%) in CRF2-/- mice compared to their WT littermates. Conclusion: In conscious mice, activation of CRF2 pathway prevents acute stress-stimulated colonic contractility through direct inhibitory actions and/or through recruitment of inhibitory pathways such as VIP. CRF2 pathway also reduces chronic stress- and CRD-induced visceral hyperalgesia. The data suggest that CRF2 signaling plays role in the sensori-motor coping response of the colon to stress and could be a target in the management of stress-related functional gut diseases. Supported by NIH grants RO1 DK078676 (MM), DK-57238 (YT), SNFGE fellowship (GG).
AGA Abstracts
Overexpression of Smoothened Activates the Sonic Hedgehog Signaling Pathway in Pancreatic Cancer Associated Fibroblasts Kimberly Walter, Noriyuki Omura, Seung-Mo Hong, Margaret Griffith, Audrey Vincent, Michael Borges, Michael G. Goggins Although Hedgehog signaling pathway components are aberrantly expressed in pancreatic cancers, accumulating evidence from mouse models suggests that the Sonic Hedgehog ligand (Shh) is often not active in pancreatic cancer cells and instead requires a paracrine signaling mechanism. However, it is not known if this paracrine mechanism of Hedgehog signaling can be extended to human stroma. We performed gene expression profiling of human pancreatic cancer associated fibroblasts (CAFs) and non-neoplastic pancreatic fibroblasts to identify differentially expressed genes in CAFs. Among the genes upregulated in cancer associated fibroblasts relative to control fibroblasts was the Hedgehog receptor Smoothened (SMO). We find that CAFs expressing SMO can transduce the Shh signal to activate Gli1 expression, and siRNA knockdown of SMO blocks the induction of Gli1 in these cells. We further find overexpression of Smo in stromal fibroblasts of human primary pancreatic adenocarcinomas compared to normal pancreatic fibroblasts. These findings implicate overexpression of Smo as a mechanism for the activation of Hedgehog signaling in human pancreatic CAFs and suggest that stromal cells may be a therapeutic target for Smo antagonists in pancreatic cancer.
138 Norepinephrine Release Following Chronic Stress Rapidly Enhances L-Type Calcium Channel α1c Subunit Through PI3K/AKT/GSK-3 Signaling Pathway in Colonic Circular Smooth Muscle Cells Qingjie Li, Sushil K. Sarna Background and Aims: Pathogenic stimuli, such as intermittent chronic stress require rapid expression of their target proteins to modulate organ function. We reported recently that chronic stress elevates plasma norepinephrine (NE), which enhances expression of the poreforming α1C subunit of the Ca v1.2 channels in colonic circular smooth muscle cells, resulting in accelerated colonic transit. The up-regulation of the α1C subunit in response to chronic stress is rapid, which is usually not explained by transcriptional up-regulation. Therefore, we investigated whether chronic stress-induced NE triggers post-transcription mechanisms to rapidly enhance the expression of α1C subunit. Methods: We used rat colonic circular muscle strips and rat colonic circular smooth muscle cells (RCCSMCs). Results: The incubation of rat colonic muscularis externa with 1 μM NE enhanced α1C protein expression within 1-hour; the expression peaked at about 6-hours and declined thereafter. Real-time RT-PCR showed that α1C mRNA did not increase during this period, indicating post-transcriptional regulation of α1C by NE. We confirmed this by showing that NE enhances α1C subunit in the presence of actinomycin D, which blocks transcription, or cycloheximide, which blocks new protein synthesis. Therefore, we tested the hypothesis that constitutively active GSK3 phosphorylates α1C, which makes it susceptible to ubiquitination and proteasomal degradation. NE may increase α1C by inhibiting its ubiquitination followed by degradation. We incubated colonic muscularis externa with NE or with 20 mM LiCl, which phosphorylates GSK-3. Both enhanced pGSK-3 and α1C time-dependently. Using enrichment of phosphoproteins and ubiquitinated proteins, we found that both NE and LiCl significantly decreased α1C phosphorylation and ubiquitination after 3-hr treatment. NE induction of α1C was completely abrogated by inhibition of two upstream kinases, PI3 kinase and Akt by LY294002 and Akti-1/2 respectively. To further identify adrenergic receptors (AR) involved in α1C induction by NE, antagonists phentolamine, propranolol or cyanopindolol were applied to muscle strips together with NE. Cyanopindolol, a β3 AR-antagonist almost completely suppressed and propranolol (β2 AR antagonist) partially abrogated NE-induced α1C, while phentolamine (α AR antagonist) had no significant effect. Conclusions: NE rapidly increases α1C protein by inhibiting GSK-3 activity through β2/3AR/PI3K/Akt/GSK-3 signaling pathway and attenuating α1C phosphorylation, ubiquitination and proteasomal degradation. This signaling pathway is critical to inducing rapid expression of proteins for homeostasis under chronic stress.
136 Distal Esophageal Emptying: A Mechanistic Analysis Using a Novel 3-D High Resolution Manometry (3-D HRM) Coupled With Videofluoroscopy and a Squamocolumnar Junction Endoclip Monika A. Kwiatek, John E. Pandolfino, Thomas B. Nealis, Peter J. Kahrilas BACKGROUND AND AIM: High resolution esophageal pressure topography (HREPT) recordings reveal a deceleration point (DP) as peristalsis approaches the esophagogastric junction. Concurrent fluoroscopy suggests that the DP demarcates transition from peristaltic transport to phrenic ampulla (PA) emptying (Pandolfino JE, et al. NGM 2010; In Press). We aimed to further resolve the anatomy and physiology of this transition. METHODS: 4 subjects had an endoclip placed at the squamocolumnar junction (SCJ). Barium swallows were recorded using a hybrid 3-D HRM assembly directly coupled with videofluoroscopy (Sierra). The distal 9 cm 3-D HRM component had 12 rings of 8 radially dispersed sensors, 7.5 mm apart on center, totaling 96 independent solid-state sensors; 28 HR circumferential sensors (1 cm apart) were proximal to the 3-D segment. Peristaltic and PA emptying were independently analyzed, demarcated by fluoroscopic characteristics. RESULTS: Resting position of the SCJ was 5 ± 1 mm distal to the CD. The proximal and distal margins of the LES were 21 ± 1 mm proximal and 10 ± 1 mm distal to the CD as isolated by 3-D HRM, respectively. HREPT/fluoroscopy confirmed that the onset of PA emptying coincided with the DP. Most of the PA was proximal to the CD and SCJ (Table) suggesting that “physiological herniation” accounted for only a minor fraction of the PA structure. Pressure within the PA (28 ± 1 mmHg) was less than at the DP (81 ± 4 mmHg) (p < 0.01) consistent with the PA being mainly comprised of the LES. PA emptying progressed at the same rate as SCJ descent. Cross-referencing fluoroscopy with HREPT suggested that “S3” by Clouse description included both distal esophagus and proximal LES. CONCLUSION: Combining the novel 3-D HRM, videofluoroscopy, and SCJ endoclipping permits isolation of CD, LES, and esophageal shortening contributions to esophageal emptying. Findings suggest that peristalsis slows and terminates before the proximal margin of the LES, about 26 mm proximal to the SCJ, with subsequent emptying attributable to LES contraction during restoration of the pre-swallow esophageal configuration.
139 The Mechanism of Intestinal Barrier Dysfunction Induced by Bowel Manipulation in a Model for Postoperative Ileus Susanne A. Snoek, Oana I. Stanisor, Francisca W. Hilbers, Sjoerd van Bree, Esmerij P. van der Zanden, Caroline Verseyden, Anneke Koeman, Rene M. van den Wijngaard, Coert J. Zuurbier, Guy E. Boeckxstaens, Wouter de Jonge BACKGROUND AND AIMS: Postoperative ileus (POI) is mediated by a mast cell dependent neutrophilic immune response localized to the muscularis externa. POI is commonly associated with intestinal stasis and bacterial overgrowth. We studied the mechanisms of intestinal barrier dysfunction in a mouse model for POI. METHODS: Experiments were performed in C57Bl/6 mice, mast cell deficient Kit/Kitv and their controls Kit/WT. Mice underwent laparotomy (L) or L followed by a gentle manipulation of the small bowel (IM). Twenty four hours after surgery, intestinal inflammation was assessed by the number of MPOpositive cells per mm2 and cytokine production in the muscularis externa of the small intestine. Bacterial translocation was expressed as the number of colony forming units (CFU) cultured from the mesenteric lymph node (MLN). Epithelial permeability to horse radish peroxidase (HRP) was assessed in ussing chambers. The carotid artery was cannulated using a heparinized saline-filled catheter to record mean arterial pressure (MAP). RESULTS: IM induced bacterial translocation (L: 0.33±0.33; IM: 27.94±9.36 CFU/mg) and an increased permeability to HRP (L: 0.48±0.20; IM: 1.52±0.58 pMol/h/cm2). In conjunction, IM led to a neutrophil infiltrate in the intestinal muscle layer in C57Bl/6 (WT) mice (L: 21±10; IM: 219±24 cells/mm2). The neutrophil influx was dependent on the presence of mast cells (IM: Kit/Kitv: 112±59; Kit/WT: 242±20 cells/mm2), but this was not associated with reduced bacterial translocation (IM: Kit/Kitv: 0.52±0.18; Kit/WT: 0.52±0.20 CFU/mg) or differences in epithelial permeability (IM: Kit/Kitv: 2.4±2.0, Kit/WT: 3.83±1.67 pMol/h/cm2). The inflammatory reaction is restricted to the muscle layer as we observed IM-induced production of cytokines MCP-1 (L: 44±2; IM: 801±121 pg/mg protein), IL-6 (L:0.7±0.4; IM:30±11 pg/ mg protein) and KC (L: 23±1; IM: 203±89 pg/mg protein) in the muscle layer but not in the mucosa. A loss of tissue perfusion could explain for a noxious stimulant. Indeed, when assessing the blood pressure changes we observed a drop in MAP during IM (22.9±4.4 % decrease) but not during L (4.4±2.8 % decrease). CONCLUSIONS: IM during abdominal surgery induces bacterial translocation and an increase in epithelial permeability. However, these events are not dependent on mast cell activation or the subsequent inflammatory reaction in the muscularis externa. IM induced barrier dysfunction most likely rests on the result of intestinal hypoperfusion, which may result in epithelial cell damage. Measures should be taken to reduce the drop in blood pressure during surgery.
*p < 0.01 vs. peristaltic emptying velocity, all cells mean ± SEM 137 Role of CRF2 Pathway in the Prevention of Stress-Induced Colonic SensoriMotor Alterations in Mice Guillaume Gourcerol, Muriel H. Larauche, Tomofumi Amano, Stephan Brunhuber, Joseph R. Pisegna, Jean E. Rivier, Yvette Tache, Mulugeta Million Background: Convergent evidence indicates that activation of corticotropin-releasing factor 1 (CRF1) receptor signaling pathway plays a key role in stress-related gut sensori- and secreto-motor function alterations. Despite the presence of CRF2 receptors in gut tissues, their function is not well known. Exogenous urocortin-2 (Ucn 2), a selective CRF2 receptor agonist, dampened visceral hyperalgesia induced by repeated colorectal distensions (CRD) in rats (Gut 2006;55:172-). Aim: Determine the role of endogenous CRF2 pathway in stressaltered colonic motility and visceral pain response in conscious mice. Method: Male CRF2-/and vasoactive intestinal peptide (VIP)-/- mice and their respective wild type (WT) littermates were exposed to 1h acute partial restraint stress (PRS). CRF over-expressing (OE) mice and repeated daily acute PRS were used as chronic stress models. Distal intracolonic pressure (ICP) was monitored in conscious mice using a novel method (AJP. 2009;296:G992-). Visceral pain response was measured in conscious mice by quantifying visceromotor response (VMR) as ICP in response to repeated phasic CRD (10-20-40-60 mmHg) (AJP 2009;297:G215-). Result: Compared to vehicle (0.1 ml), intraperitoneal (ip) Ucn 2, (10 μg/kg, 0.1 ml) prevented acute PRS stimulated colonic contractility in conscious WT as well as in chronically stressed CRF-OE mice but not in VIP-/- mice. When exposed to an acute PRS, CRF2-/- mice displayed increased (p<0.05) colonic contractility (272±62 mmHgxmin) and fecal pellet output (11.5±0.8 pellet/h) compared to their WT littermates (169±21 mmHgxmin and 4.2±1.1 pellet/h, respectively). Chronic PRS for 10 days did not modify acute PRS-stimulated colonic contractility in CRF2-/- mice. CRD-induced VMR was comparable in
AGA Abstracts
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CRF2-/- mice and their WT littermates at baseline. By contrast, after 10 days of exposure to repeated PRS, CRD-induced VMR was increased (p<0.05) at 40 mmHg (+99%) and 60 mmHg (+69%) in CRF2-/- mice compared to their WT littermates. Conclusion: In conscious mice, activation of CRF2 pathway prevents acute stress-stimulated colonic contractility through direct inhibitory actions and/or through recruitment of inhibitory pathways such as VIP. CRF2 pathway also reduces chronic stress- and CRD-induced visceral hyperalgesia. The data suggest that CRF2 signaling plays role in the sensori-motor coping response of the colon to stress and could be a target in the management of stress-related functional gut diseases. Supported by NIH grants RO1 DK078676 (MM), DK-57238 (YT), SNFGE fellowship (GG).
AGA Abstracts
Overexpression of Smoothened Activates the Sonic Hedgehog Signaling Pathway in Pancreatic Cancer Associated Fibroblasts Kimberly Walter, Noriyuki Omura, Seung-Mo Hong, Margaret Griffith, Audrey Vincent, Michael Borges, Michael G. Goggins Although Hedgehog signaling pathway components are aberrantly expressed in pancreatic cancers, accumulating evidence from mouse models suggests that the Sonic Hedgehog ligand (Shh) is often not active in pancreatic cancer cells and instead requires a paracrine signaling mechanism. However, it is not known if this paracrine mechanism of Hedgehog signaling can be extended to human stroma. We performed gene expression profiling of human pancreatic cancer associated fibroblasts (CAFs) and non-neoplastic pancreatic fibroblasts to identify differentially expressed genes in CAFs. Among the genes upregulated in cancer associated fibroblasts relative to control fibroblasts was the Hedgehog receptor Smoothened (SMO). We find that CAFs expressing SMO can transduce the Shh signal to activate Gli1 expression, and siRNA knockdown of SMO blocks the induction of Gli1 in these cells. We further find overexpression of Smo in stromal fibroblasts of human primary pancreatic adenocarcinomas compared to normal pancreatic fibroblasts. These findings implicate overexpression of Smo as a mechanism for the activation of Hedgehog signaling in human pancreatic CAFs and suggest that stromal cells may be a therapeutic target for Smo antagonists in pancreatic cancer.
138 Norepinephrine Release Following Chronic Stress Rapidly Enhances L-Type Calcium Channel α1c Subunit Through PI3K/AKT/GSK-3 Signaling Pathway in Colonic Circular Smooth Muscle Cells Qingjie Li, Sushil K. Sarna Background and Aims: Pathogenic stimuli, such as intermittent chronic stress require rapid expression of their target proteins to modulate organ function. We reported recently that chronic stress elevates plasma norepinephrine (NE), which enhances expression of the poreforming α1C subunit of the Ca v1.2 channels in colonic circular smooth muscle cells, resulting in accelerated colonic transit. The up-regulation of the α1C subunit in response to chronic stress is rapid, which is usually not explained by transcriptional up-regulation. Therefore, we investigated whether chronic stress-induced NE triggers post-transcription mechanisms to rapidly enhance the expression of α1C subunit. Methods: We used rat colonic circular muscle strips and rat colonic circular smooth muscle cells (RCCSMCs). Results: The incubation of rat colonic muscularis externa with 1 μM NE enhanced α1C protein expression within 1-hour; the expression peaked at about 6-hours and declined thereafter. Real-time RT-PCR showed that α1C mRNA did not increase during this period, indicating post-transcriptional regulation of α1C by NE. We confirmed this by showing that NE enhances α1C subunit in the presence of actinomycin D, which blocks transcription, or cycloheximide, which blocks new protein synthesis. Therefore, we tested the hypothesis that constitutively active GSK3 phosphorylates α1C, which makes it susceptible to ubiquitination and proteasomal degradation. NE may increase α1C by inhibiting its ubiquitination followed by degradation. We incubated colonic muscularis externa with NE or with 20 mM LiCl, which phosphorylates GSK-3. Both enhanced pGSK-3 and α1C time-dependently. Using enrichment of phosphoproteins and ubiquitinated proteins, we found that both NE and LiCl significantly decreased α1C phosphorylation and ubiquitination after 3-hr treatment. NE induction of α1C was completely abrogated by inhibition of two upstream kinases, PI3 kinase and Akt by LY294002 and Akti-1/2 respectively. To further identify adrenergic receptors (AR) involved in α1C induction by NE, antagonists phentolamine, propranolol or cyanopindolol were applied to muscle strips together with NE. Cyanopindolol, a β3 AR-antagonist almost completely suppressed and propranolol (β2 AR antagonist) partially abrogated NE-induced α1C, while phentolamine (α AR antagonist) had no significant effect. Conclusions: NE rapidly increases α1C protein by inhibiting GSK-3 activity through β2/3AR/PI3K/Akt/GSK-3 signaling pathway and attenuating α1C phosphorylation, ubiquitination and proteasomal degradation. This signaling pathway is critical to inducing rapid expression of proteins for homeostasis under chronic stress.
136 Distal Esophageal Emptying: A Mechanistic Analysis Using a Novel 3-D High Resolution Manometry (3-D HRM) Coupled With Videofluoroscopy and a Squamocolumnar Junction Endoclip Monika A. Kwiatek, John E. Pandolfino, Thomas B. Nealis, Peter J. Kahrilas BACKGROUND AND AIM: High resolution esophageal pressure topography (HREPT) recordings reveal a deceleration point (DP) as peristalsis approaches the esophagogastric junction. Concurrent fluoroscopy suggests that the DP demarcates transition from peristaltic transport to phrenic ampulla (PA) emptying (Pandolfino JE, et al. NGM 2010; In Press). We aimed to further resolve the anatomy and physiology of this transition. METHODS: 4 subjects had an endoclip placed at the squamocolumnar junction (SCJ). Barium swallows were recorded using a hybrid 3-D HRM assembly directly coupled with videofluoroscopy (Sierra). The distal 9 cm 3-D HRM component had 12 rings of 8 radially dispersed sensors, 7.5 mm apart on center, totaling 96 independent solid-state sensors; 28 HR circumferential sensors (1 cm apart) were proximal to the 3-D segment. Peristaltic and PA emptying were independently analyzed, demarcated by fluoroscopic characteristics. RESULTS: Resting position of the SCJ was 5 ± 1 mm distal to the CD. The proximal and distal margins of the LES were 21 ± 1 mm proximal and 10 ± 1 mm distal to the CD as isolated by 3-D HRM, respectively. HREPT/fluoroscopy confirmed that the onset of PA emptying coincided with the DP. Most of the PA was proximal to the CD and SCJ (Table) suggesting that “physiological herniation” accounted for only a minor fraction of the PA structure. Pressure within the PA (28 ± 1 mmHg) was less than at the DP (81 ± 4 mmHg) (p < 0.01) consistent with the PA being mainly comprised of the LES. PA emptying progressed at the same rate as SCJ descent. Cross-referencing fluoroscopy with HREPT suggested that “S3” by Clouse description included both distal esophagus and proximal LES. CONCLUSION: Combining the novel 3-D HRM, videofluoroscopy, and SCJ endoclipping permits isolation of CD, LES, and esophageal shortening contributions to esophageal emptying. Findings suggest that peristalsis slows and terminates before the proximal margin of the LES, about 26 mm proximal to the SCJ, with subsequent emptying attributable to LES contraction during restoration of the pre-swallow esophageal configuration.
139 The Mechanism of Intestinal Barrier Dysfunction Induced by Bowel Manipulation in a Model for Postoperative Ileus Susanne A. Snoek, Oana I. Stanisor, Francisca W. Hilbers, Sjoerd van Bree, Esmerij P. van der Zanden, Caroline Verseyden, Anneke Koeman, Rene M. van den Wijngaard, Coert J. Zuurbier, Guy E. Boeckxstaens, Wouter de Jonge BACKGROUND AND AIMS: Postoperative ileus (POI) is mediated by a mast cell dependent neutrophilic immune response localized to the muscularis externa. POI is commonly associated with intestinal stasis and bacterial overgrowth. We studied the mechanisms of intestinal barrier dysfunction in a mouse model for POI. METHODS: Experiments were performed in C57Bl/6 mice, mast cell deficient Kit/Kitv and their controls Kit/WT. Mice underwent laparotomy (L) or L followed by a gentle manipulation of the small bowel (IM). Twenty four hours after surgery, intestinal inflammation was assessed by the number of MPOpositive cells per mm2 and cytokine production in the muscularis externa of the small intestine. Bacterial translocation was expressed as the number of colony forming units (CFU) cultured from the mesenteric lymph node (MLN). Epithelial permeability to horse radish peroxidase (HRP) was assessed in ussing chambers. The carotid artery was cannulated using a heparinized saline-filled catheter to record mean arterial pressure (MAP). RESULTS: IM induced bacterial translocation (L: 0.33±0.33; IM: 27.94±9.36 CFU/mg) and an increased permeability to HRP (L: 0.48±0.20; IM: 1.52±0.58 pMol/h/cm2). In conjunction, IM led to a neutrophil infiltrate in the intestinal muscle layer in C57Bl/6 (WT) mice (L: 21±10; IM: 219±24 cells/mm2). The neutrophil influx was dependent on the presence of mast cells (IM: Kit/Kitv: 112±59; Kit/WT: 242±20 cells/mm2), but this was not associated with reduced bacterial translocation (IM: Kit/Kitv: 0.52±0.18; Kit/WT: 0.52±0.20 CFU/mg) or differences in epithelial permeability (IM: Kit/Kitv: 2.4±2.0, Kit/WT: 3.83±1.67 pMol/h/cm2). The inflammatory reaction is restricted to the muscle layer as we observed IM-induced production of cytokines MCP-1 (L: 44±2; IM: 801±121 pg/mg protein), IL-6 (L:0.7±0.4; IM:30±11 pg/ mg protein) and KC (L: 23±1; IM: 203±89 pg/mg protein) in the muscle layer but not in the mucosa. A loss of tissue perfusion could explain for a noxious stimulant. Indeed, when assessing the blood pressure changes we observed a drop in MAP during IM (22.9±4.4 % decrease) but not during L (4.4±2.8 % decrease). CONCLUSIONS: IM during abdominal surgery induces bacterial translocation and an increase in epithelial permeability. However, these events are not dependent on mast cell activation or the subsequent inflammatory reaction in the muscularis externa. IM induced barrier dysfunction most likely rests on the result of intestinal hypoperfusion, which may result in epithelial cell damage. Measures should be taken to reduce the drop in blood pressure during surgery.
*p < 0.01 vs. peristaltic emptying velocity, all cells mean ± SEM 137 Role of CRF2 Pathway in the Prevention of Stress-Induced Colonic SensoriMotor Alterations in Mice Guillaume Gourcerol, Muriel H. Larauche, Tomofumi Amano, Stephan Brunhuber, Joseph R. Pisegna, Jean E. Rivier, Yvette Tache, Mulugeta Million Background: Convergent evidence indicates that activation of corticotropin-releasing factor 1 (CRF1) receptor signaling pathway plays a key role in stress-related gut sensori- and secreto-motor function alterations. Despite the presence of CRF2 receptors in gut tissues, their function is not well known. Exogenous urocortin-2 (Ucn 2), a selective CRF2 receptor agonist, dampened visceral hyperalgesia induced by repeated colorectal distensions (CRD) in rats (Gut 2006;55:172-). Aim: Determine the role of endogenous CRF2 pathway in stressaltered colonic motility and visceral pain response in conscious mice. Method: Male CRF2-/and vasoactive intestinal peptide (VIP)-/- mice and their respective wild type (WT) littermates were exposed to 1h acute partial restraint stress (PRS). CRF over-expressing (OE) mice and repeated daily acute PRS were used as chronic stress models. Distal intracolonic pressure (ICP) was monitored in conscious mice using a novel method (AJP. 2009;296:G992-). Visceral pain response was measured in conscious mice by quantifying visceromotor response (VMR) as ICP in response to repeated phasic CRD (10-20-40-60 mmHg) (AJP 2009;297:G215-). Result: Compared to vehicle (0.1 ml), intraperitoneal (ip) Ucn 2, (10 μg/kg, 0.1 ml) prevented acute PRS stimulated colonic contractility in conscious WT as well as in chronically stressed CRF-OE mice but not in VIP-/- mice. When exposed to an acute PRS, CRF2-/- mice displayed increased (p<0.05) colonic contractility (272±62 mmHgxmin) and fecal pellet output (11.5±0.8 pellet/h) compared to their WT littermates (169±21 mmHgxmin and 4.2±1.1 pellet/h, respectively). Chronic PRS for 10 days did not modify acute PRS-stimulated colonic contractility in CRF2-/- mice. CRD-induced VMR was comparable in
AGA Abstracts
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