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Yang X, Yao L, Fu X, Mukherjee R, Xia Q, Jakubowska MA, Ferdek PE, Huang W. Experimental Acute Pancreatitis Models: History, Current Status, and Role in Translational Research. Front Physiol 2020; 11:614591. [PMID: 33424638 PMCID: PMC7786374 DOI: 10.3389/fphys.2020.614591] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2020] [Accepted: 11/30/2020] [Indexed: 02/05/2023] Open
Abstract
Acute pancreatitis is a potentially severe inflammatory disease that may be associated with a substantial morbidity and mortality. Currently there is no specific treatment for the disease, which indicates an ongoing demand for research into its pathogenesis and development of new therapeutic strategies. Due to the unpredictable course of acute pancreatitis and relatively concealed anatomical site in the retro-peritoneum, research on the human pancreas remains challenging. As a result, for over the last 100 years studies on the pathogenesis of this disease have heavily relied on animal models. This review aims to summarize different animal models of acute pancreatitis from the past to present and discuss their main characteristics and applications. It identifies key studies that have enhanced our current understanding of the pathogenesis of acute pancreatitis and highlights the instrumental role of animal models in translational research for developing novel therapies.
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Affiliation(s)
- Xinmin Yang
- Department of Integrated Traditional Chinese Medicine and Western Medicine, Sichuan Provincial Pancreatitis Center and West China-Liverpool Biomedical Research Center, West China Hospital, Sichuan University, Chengdu, China
| | - Linbo Yao
- Department of Integrated Traditional Chinese Medicine and Western Medicine, Sichuan Provincial Pancreatitis Center and West China-Liverpool Biomedical Research Center, West China Hospital, Sichuan University, Chengdu, China
| | - Xianghui Fu
- Division of Endocrinology and Metabolism, State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University and Collaborative Innovation Center of Biotherapy, Chengdu, China
| | - Rajarshi Mukherjee
- Liverpool Pancreatitis Research Group, Liverpool University Hospitals National Health Service Foundation Trust and Institute of Systems, Molecular and Integrative Biology, University of Liverpool, Liverpool, United Kingdom
| | - Qing Xia
- Department of Integrated Traditional Chinese Medicine and Western Medicine, Sichuan Provincial Pancreatitis Center and West China-Liverpool Biomedical Research Center, West China Hospital, Sichuan University, Chengdu, China
| | | | - Pawel E. Ferdek
- Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Krakow, Poland
| | - Wei Huang
- Department of Integrated Traditional Chinese Medicine and Western Medicine, Sichuan Provincial Pancreatitis Center and West China-Liverpool Biomedical Research Center, West China Hospital, Sichuan University, Chengdu, China
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2
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Verbeke F, Bracke N, Debunne N, Wynendaele E, De Spiegeleer B. LC-MS Compatible Antiadsorption Diluent for Peptide Analysis. Anal Chem 2020; 92:1712-1719. [PMID: 31874035 DOI: 10.1021/acs.analchem.9b01840] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Analytical method development for peptides often proves challenging since these molecules can adsorb to the plastic or glass consumables used in the analysis. This adsorption causes considerable loss and unreliable results, especially in the lower concentration range. Therefore, a variety of antiadsorption strategies have previously been developed to cope with this adsorption, often however incompatible with direct liquid chromatography-mass spectrometry (LC-MS) analysis. Here, a novel antiadsorption diluent is introduced, based on controlled hydrolysis and precipitation of bovine serum albumin. This diluent considerably decreases the adsorption of certain peptides to glass. Moreover, it is LC-MS compatible and can also be used in combination with formic acid and/or acetonitrile addition.
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Affiliation(s)
- Frederick Verbeke
- Drug Quality and Registration (DruQuaR) Group, Faculty of Pharmaceutical Sciences , Ghent University , Ottergemsesteenweg 460 , B-9000 Ghent , Belgium
| | - Nathalie Bracke
- Drug Quality and Registration (DruQuaR) Group, Faculty of Pharmaceutical Sciences , Ghent University , Ottergemsesteenweg 460 , B-9000 Ghent , Belgium
| | - Nathan Debunne
- Drug Quality and Registration (DruQuaR) Group, Faculty of Pharmaceutical Sciences , Ghent University , Ottergemsesteenweg 460 , B-9000 Ghent , Belgium
| | - Evelien Wynendaele
- Drug Quality and Registration (DruQuaR) Group, Faculty of Pharmaceutical Sciences , Ghent University , Ottergemsesteenweg 460 , B-9000 Ghent , Belgium
| | - Bart De Spiegeleer
- Drug Quality and Registration (DruQuaR) Group, Faculty of Pharmaceutical Sciences , Ghent University , Ottergemsesteenweg 460 , B-9000 Ghent , Belgium
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Steinert RE, Feinle-Bisset C, Asarian L, Horowitz M, Beglinger C, Geary N. Ghrelin, CCK, GLP-1, and PYY(3-36): Secretory Controls and Physiological Roles in Eating and Glycemia in Health, Obesity, and After RYGB. Physiol Rev 2017; 97:411-463. [PMID: 28003328 PMCID: PMC6151490 DOI: 10.1152/physrev.00031.2014] [Citation(s) in RCA: 353] [Impact Index Per Article: 50.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The efficacy of Roux-en-Y gastric-bypass (RYGB) and other bariatric surgeries in the management of obesity and type 2 diabetes mellitus and novel developments in gastrointestinal (GI) endocrinology have renewed interest in the roles of GI hormones in the control of eating, meal-related glycemia, and obesity. Here we review the nutrient-sensing mechanisms that control the secretion of four of these hormones, ghrelin, cholecystokinin (CCK), glucagon-like peptide-1 (GLP-1), and peptide tyrosine tyrosine [PYY(3-36)], and their contributions to the controls of GI motor function, food intake, and meal-related increases in glycemia in healthy-weight and obese persons, as well as in RYGB patients. Their physiological roles as classical endocrine and as locally acting signals are discussed. Gastric emptying, the detection of specific digestive products by small intestinal enteroendocrine cells, and synergistic interactions among different GI loci all contribute to the secretion of ghrelin, CCK, GLP-1, and PYY(3-36). While CCK has been fully established as an endogenous endocrine control of eating in healthy-weight persons, the roles of all four hormones in eating in obese persons and following RYGB are uncertain. Similarly, only GLP-1 clearly contributes to the endocrine control of meal-related glycemia. It is likely that local signaling is involved in these hormones' actions, but methods to determine the physiological status of local signaling effects are lacking. Further research and fresh approaches are required to better understand ghrelin, CCK, GLP-1, and PYY(3-36) physiology; their roles in obesity and bariatric surgery; and their therapeutic potentials.
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Affiliation(s)
- Robert E Steinert
- University of Adelaide Discipline of Medicine and National Health and Medical Research Council of Australia Centre of Research Excellence in Translating Nutritional Science to Good Health, Adelaide, Australia; DSM Nutritional Products, R&D Human Nutrition and Health, Basel, Switzerland; Institute of Veterinary Physiology, University of Zurich, Zurich, Switzerland; Department of Biomedicine and Division of Gastroenterology, University Hospital Basel, Basel, Switzerland; and Department of Psychiatry, Weill Medical College of Cornell University, New York, New York
| | - Christine Feinle-Bisset
- University of Adelaide Discipline of Medicine and National Health and Medical Research Council of Australia Centre of Research Excellence in Translating Nutritional Science to Good Health, Adelaide, Australia; DSM Nutritional Products, R&D Human Nutrition and Health, Basel, Switzerland; Institute of Veterinary Physiology, University of Zurich, Zurich, Switzerland; Department of Biomedicine and Division of Gastroenterology, University Hospital Basel, Basel, Switzerland; and Department of Psychiatry, Weill Medical College of Cornell University, New York, New York
| | - Lori Asarian
- University of Adelaide Discipline of Medicine and National Health and Medical Research Council of Australia Centre of Research Excellence in Translating Nutritional Science to Good Health, Adelaide, Australia; DSM Nutritional Products, R&D Human Nutrition and Health, Basel, Switzerland; Institute of Veterinary Physiology, University of Zurich, Zurich, Switzerland; Department of Biomedicine and Division of Gastroenterology, University Hospital Basel, Basel, Switzerland; and Department of Psychiatry, Weill Medical College of Cornell University, New York, New York
| | - Michael Horowitz
- University of Adelaide Discipline of Medicine and National Health and Medical Research Council of Australia Centre of Research Excellence in Translating Nutritional Science to Good Health, Adelaide, Australia; DSM Nutritional Products, R&D Human Nutrition and Health, Basel, Switzerland; Institute of Veterinary Physiology, University of Zurich, Zurich, Switzerland; Department of Biomedicine and Division of Gastroenterology, University Hospital Basel, Basel, Switzerland; and Department of Psychiatry, Weill Medical College of Cornell University, New York, New York
| | - Christoph Beglinger
- University of Adelaide Discipline of Medicine and National Health and Medical Research Council of Australia Centre of Research Excellence in Translating Nutritional Science to Good Health, Adelaide, Australia; DSM Nutritional Products, R&D Human Nutrition and Health, Basel, Switzerland; Institute of Veterinary Physiology, University of Zurich, Zurich, Switzerland; Department of Biomedicine and Division of Gastroenterology, University Hospital Basel, Basel, Switzerland; and Department of Psychiatry, Weill Medical College of Cornell University, New York, New York
| | - Nori Geary
- University of Adelaide Discipline of Medicine and National Health and Medical Research Council of Australia Centre of Research Excellence in Translating Nutritional Science to Good Health, Adelaide, Australia; DSM Nutritional Products, R&D Human Nutrition and Health, Basel, Switzerland; Institute of Veterinary Physiology, University of Zurich, Zurich, Switzerland; Department of Biomedicine and Division of Gastroenterology, University Hospital Basel, Basel, Switzerland; and Department of Psychiatry, Weill Medical College of Cornell University, New York, New York
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Sayegh AI, Washington MC, Johnson RE, Johnson-Rouse T, Freeman C, Harrison A, Lucas J, Shelby M, Fisher B, Willis W, Reeve JJ. Celiac and the cranial mesenteric arteries supply gastrointestinal sites that regulate meal size and intermeal interval length via cholecystokinin-58 in male rats. Horm Behav 2015; 67:48-53. [PMID: 25479193 DOI: 10.1016/j.yhbeh.2014.11.011] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/10/2014] [Revised: 11/23/2014] [Accepted: 11/24/2014] [Indexed: 11/28/2022]
Abstract
The site(s) of action that control meal size and intermeal interval (IMI) length by cholecystokinin-58 (CCK-58), the only detectable endocrine form of CCK in the rat, are not known. To test the hypothesis that the gastrointestinal tract may contain such sites, we infused low doses of CCK-58 (0.01, 0.05, 0.15 and 0.25nmol/kg) into the celiac artery (CA, supplying stomach and upper duodenum), the cranial mesenteric artery (CMA, supplying small and most of the large intestines), the femoral artery (FA, control) and the portal vein (PV, draining the gastrointestinal tract) prior to the onset of the dark cycle in freely fed male rats. We measured the first meal size (chow), second meal size, IMI and satiety ratio (SR, IMI/meal size). We found that (1) all doses of CCK-58 given in the CA and the highest dose given in the CMA reduced the first meal size, (2) all doses of CCK-58 given in the CA reduced the second meal size, (3) a CCK-58 dose of 0.15nmol/kg given in the CA and 0.15 and 0.25nmol/kg given in the CMA prolonged the IMI, (4) CCK-58 (0.05, 0.15, 0.25nmol/kg) given in the CA and 0.25nmol/kg given in the CMA increased the SR, and (5) CCK-58 given in the FA and PV had no effect on the meal size or intermeal interval. These results support our hypothesis that the gastrointestinal tract contains sites of action that regulate meal size and IMI length via CCK-58. The stomach and upper duodenum may contain sites regulating meal size, whereas the small intestine and part of the large intestine may contain sites regulating the IMI.
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Affiliation(s)
- Ayman I Sayegh
- Gastroenterology Laboratory, Department of Biomedical Sciences, College of Veterinary Medicine, Tuskegee University, Tuskegee, AL, USA.
| | - Martha C Washington
- Gastroenterology Laboratory, Department of Biomedical Sciences, College of Veterinary Medicine, Tuskegee University, Tuskegee, AL, USA
| | - Ruth E Johnson
- Gastroenterology Laboratory, Department of Biomedical Sciences, College of Veterinary Medicine, Tuskegee University, Tuskegee, AL, USA
| | - Tanisha Johnson-Rouse
- Gastroenterology Laboratory, Department of Biomedical Sciences, College of Veterinary Medicine, Tuskegee University, Tuskegee, AL, USA
| | - Corren Freeman
- Gastroenterology Laboratory, Department of Biomedical Sciences, College of Veterinary Medicine, Tuskegee University, Tuskegee, AL, USA
| | - Anna Harrison
- Gastroenterology Laboratory, Department of Biomedical Sciences, College of Veterinary Medicine, Tuskegee University, Tuskegee, AL, USA
| | - Jennifer Lucas
- Gastroenterology Laboratory, Department of Biomedical Sciences, College of Veterinary Medicine, Tuskegee University, Tuskegee, AL, USA
| | - Mandy Shelby
- Gastroenterology Laboratory, Department of Biomedical Sciences, College of Veterinary Medicine, Tuskegee University, Tuskegee, AL, USA
| | - Brittley Fisher
- Gastroenterology Laboratory, Department of Biomedical Sciences, College of Veterinary Medicine, Tuskegee University, Tuskegee, AL, USA
| | - William Willis
- Gastroenterology Laboratory, Department of Biomedical Sciences, College of Veterinary Medicine, Tuskegee University, Tuskegee, AL, USA
| | - Joseph J Reeve
- Gastroenterology Laboratory, Department of Biomedical Sciences, College of Veterinary Medicine, Tuskegee University, Tuskegee, AL, USA; CURE: Digestive Diseases Research Center, Veterans Administration Greater Los Angeles Healthcare System, Los Angeles, CA, USA; Digestive Diseases Division, School of Medicine, University of California, Los Angeles, CA, USA
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5
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Ahmed ASF, Dai L, Ho W, Ferguson AV, Sharkey KA. The subfornical organ: a novel site of action of cholecystokinin. Am J Physiol Regul Integr Comp Physiol 2014; 306:R363-73. [PMID: 24430886 DOI: 10.1152/ajpregu.00462.2013] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The subfornical organ (SFO) is an important sensory circumventricular organ implicated in the regulation of fluid homeostasis and energy balance. We investigated whether the SFO is activated by the hormone cholecystokinin (CCK). CCK₁ and CCK₂ receptors were identified in the SFO by RT-PCR. Dissociated SFO neurons that responded to CCK (40/77), were mostly depolarized (9.2 ± 0.9 mV, 30/77), but some were hyperpolarized (-7.3 ± 1.1 mV, 10/77). We next examined the responses of SFO neurons in vivo to CCK (16 μg/kg ip), in the presence and absence of CCK₁ or CCK₂ receptor antagonists (devazepide; 600 μg/kg and L-365,260; 100 μg/kg, respectively), using the functional activation markers c-Fos and phosphorylated extracellular signal-related kinase (p-ERK). The nucleus of the solitary tract (NTS) served as a control for CCK-induced activity. There was a significant increase in c-Fos expression in the NTS (259.2 ± 20.8 neurons) compared with vehicle (47.5 ± 2.5). Similarly, in the SFO, c-Fos was expressed in 40.5 ± 10.6 neurons in CCK-treated compared with 6.6 ± 2.7 in vehicle-treated rats (P < 0.01). Devazepide significantly reduced the effects of CCK in the NTS but not in SFO. L-365,260 blocked the effects of CCK in both brain regions. CCK increased the number of p-ERK neurons in NTS (27.0 ± 4.0) as well as SFO (18.0 ± 4.0), compared with vehicle (8.0 ± 2.6 and 4.3 ± 0.6, respectively; P < 0.05). Both devazepide and L-365,260 reduced CCK-induced p-ERK in NTS, but only L-365,260 reduced it in the SFO. In conclusion, the SFO represents a novel brain region at which circulating CCK may act via CCK₂ receptors to influence central autonomic control.
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Affiliation(s)
- Al-Shaimaa F Ahmed
- Hotchkiss Brain Institute, Department of Physiology and Pharmacology, University of Calgary, Calgary, Alberta, Canada; and
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Goebel-Stengel M, Stengel A, Wang L, Ohning G, Taché Y, Reeve JR. CCK-8 and CCK-58 differ in their effects on nocturnal solid meal pattern in undisturbed rats. Am J Physiol Regul Integr Comp Physiol 2012; 303:R850-60. [PMID: 22874423 DOI: 10.1152/ajpregu.00365.2011] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Various molecular forms of CCK reduce food intake in rats. Although CCK-8 is the most studied form, we reported that CCK-58 is the only detectable endocrine peptide form in rats. We investigated the dark-phase rat chow intake pattern following injection of CCK-8 and CCK-58. Ad libitum-fed male Sprague-Dawley rats were intraperitoneally injected with CCK-8, CCK-58 (0.6, 1.8, and 5.2 nmol/kg), or vehicle. Food intake pattern was assessed during the dark phase using an automated weighing system that allowed continuous undisturbed monitoring of physiological eating behavior. Both CCK-8 and CCK-58 dose dependently reduced 1-h, dark-phase food intake, with an equimolar dose of 1.8 nmol being similarly effective (-49% and -44%). CCK-58 increased the latency to the first meal, whereas CCK-8 did not. The intermeal interval was reduced after CCK-8 (1.8 nmol/kg, -41%) but not after CCK-58. At this dose, CCK-8 increased the satiety ratio by 80% and CCK-58 by 160%, respectively, compared with vehicle. When behavior was assessed manually, CCK-8 reduced locomotor activity (-31%), whereas grooming behavior was increased (+59%). CCK-58 affected neither grooming nor locomotor activity. In conclusion, reduction of food intake by CCK-8 and CCK-58 is achieved by differential modulation of food intake microstructure and behavior. These data highlight the importance of studying the molecular forms of peptides that exist in vivo in tissue and circulation of the animal being studied.
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Affiliation(s)
- Miriam Goebel-Stengel
- CURE: Digestive Diseases Research Center, Digestive Diseases Division, Department of Medicine, University of California, Los Angeles 90073, USA
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Viard E, Rogers RC, Hermann GE. Systemic cholecystokinin amplifies vago-vagal reflex responses recorded in vagal motor neurones. J Physiol 2011; 590:631-46. [PMID: 22155934 DOI: 10.1113/jphysiol.2011.224477] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Cholecystokinin (CCK) is a potent regulator of visceral functions as a consequence of its actions on vago-vagal reflex circuit elements. This paper addresses three current controversies regarding the role of CCK to control gastric function via vago-vagal reflexes. Specifically: (a) whether CNS vs. peripheral (vagal afferent) receptors are dominant, (b) whether the long (58) vs. short (8) isoform is more potent and (c) whether nutritional status impacts the gain or even the direction of vago-vagal reflexes. Our in vivo recordings of physiologically identified gastric vagal motor neurones (gastric-DMN) involved in the gastric accommodation reflex (GAR) show unequivocally that: (a) receptors in the coeliac-portal circulation are more sensitive in amplifying gastric vagal reflexes; (b) in the periphery, CCK8 is more potent than CCK58; and (c) the nutritional status has a marginal effect on gastric reflex control. While the GAR reflex is more sensitive in the fasted rat, CCK amplifies this sensitivity. Thus, our results are in stark contrast to recent reports which have suggested that vago-vagal reflexes are inverted by the metabolic status of the animal and that this inversion could be mediated by CCK within the CNS.
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Affiliation(s)
- Edouard Viard
- Pennington Biomedical Research Centre, 6400 Perkins Rd, Baton Rouge, LA 70808, USA
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Stengel A, Taché Y. Interaction between gastric and upper small intestinal hormones in the regulation of hunger and satiety: ghrelin and cholecystokinin take the central stage. Curr Protein Pept Sci 2011; 12:293-304. [PMID: 21428875 PMCID: PMC3670092 DOI: 10.2174/138920311795906673] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2011] [Accepted: 03/23/2011] [Indexed: 12/13/2022]
Abstract
Several peptides are produced and released from endocrine cells scattered within the gastric oxyntic and the small intestinal mucosa. These peptide hormones are crucially involved in the regulation of gastrointestinal functions and food intake by conveying their information to central regulatory sites located in the brainstem as well as in the forebrain, such as hypothalamic nuclei. So far, ghrelin is the only known hormone that is peripherally produced in gastric X/A-like cells and centrally acting to stimulate food intake, whereas the suppression of feeding seems to be much more redundantly controlled by a number of gut peptides. Cholecystokinin produced in the duodenum is a well established anorexigenic hormone that interacts with ghrelin to modulate food intake indicating a regulatory network located at the first site of contact with nutrients in the stomach and upper small intestine. In addition, a number of peptides including leptin, urocortin 2, amylin and glucagon-like peptide 1 interact synergistically with CCK to potentiate its satiety signaling effect. New developments have led to the identification of additional peptides in X/A-like cells either derived from the pro-ghrelin gene by alternative splicing and posttranslational processing (obestatin) or a distinct gene (nucleobindin2/nesfatin-1) which have been investigated for their influence on food intake.
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Affiliation(s)
- Andreas Stengel
- Department of Medicine, CURE Digestive Diseases Research Center, Center for Neurobiology of Stress, Digestive Diseases Division UCLA, and VA Greater Los Angeles Healthcare System, Los Angeles, CA, USA
| | - Yvette Taché
- Department of Medicine, CURE Digestive Diseases Research Center, Center for Neurobiology of Stress, Digestive Diseases Division UCLA, and VA Greater Los Angeles Healthcare System, Los Angeles, CA, USA
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Goebel-Stengel M, Stengel A, Taché Y, Reeve JR. The importance of using the optimal plasticware and glassware in studies involving peptides. Anal Biochem 2011; 414:38-46. [PMID: 21315060 DOI: 10.1016/j.ab.2011.02.009] [Citation(s) in RCA: 120] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2010] [Revised: 02/02/2011] [Accepted: 02/04/2011] [Indexed: 12/22/2022]
Abstract
The unpredictable nature of peptide binding to surfaces requires optimization of experimental containers to be used. To demonstrate the variable recoveries of peptides from multiple surfaces commonly employed in peptide research, we tested the recovery of radiolabeled (125)I endocrine peptides under different conditions and provide guidelines for determining the surfaces to use for other peptides. (125)I-labeled peptides (ghrelin, sulfated cholecystokinin-8, corticotropin-releasing factor, glucagon-like peptide-1 [GLP-1], insulin, leptin, nesfatin-1, and peptide YY), representing a wide spectrum in net charge, size, end group, and modification, were incubated for 48 h in glass and plastic tubes untreated or coated with siliconizing fluid. Best surfaces were chosen and peptides were incubated with bovine serum albumin (BSA, 1%) with or without subsequent lyophilization. Recovery of (125)I-labeled peptides was determined by gamma counting. Important differences in (125)I-labeled peptide binding capacities to various types of surfaces exist. Siliconization decreased, whereas the addition of BSA improved recovery from surfaces tested. Lyophilizing solutions containing (125)I-labeled peptides and BSA in the tubes best suited for individual peptides rendered more than 89% recovery for all peptides. Ghrelin specifically displaced (125)I-ghrelin from borosilicate glass, whereas GLP-1 and Fmoc-arginine did not. Choosing the appropriate experimental container avoids unpredictable peptide loss that results in inaccurate measurements and false conclusions.
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Affiliation(s)
- Miriam Goebel-Stengel
- Department of Medicine and Institute of Neurogastroenterology, Martin Luther Hospital, Berlin, Germany
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Loffredo C, Assunção NA, Gerhardt J, Miranda MTM. Microwave-assisted solid-phase peptide synthesis at 60 degrees C: alternative conditions with low enantiomerization. J Pept Sci 2010; 15:808-17. [PMID: 19827081 DOI: 10.1002/psc.1178] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Several conditions have been used in the coupling reaction of stepwise SPPS at elevated temperature (SPPS-ET), but we have elected the following as our first choice: 2.5-fold molar excess of 0.04-0.08 M Boc or Fmoc-amino acid derivative, equimolar amount of DIC/HOBt (1:1) or TBTU/DIPEA (1:3), 25% DMSO/toluene, 60 degrees C, conventional heating. In this study, aimed to further examine enantiomerization under such condition and study the applicability of our protocols to microwave-SPPS, peptides containing L-Ser, L-His, L-Cys and/or L-Met were manually synthesized traditionally, at 60 degrees C using conventional heating and at 60 degrees C using microwave heating. Detailed assessment of all crude peptides (in their intact and/or fully hydrolyzed forms) revealed that, except for the microwave-assisted coupling of L-Cys, all other reactions occurred with low levels of amino acid enantiomerization (<2%). Therefore, herein we (i) provide new evidences that our protocols for SPPS at 60 degrees C using conventional heating are suitable for routine use, (ii) demonstrate their appropriateness for microwave-assisted SPPS by Boc and Fmoc chemistries, (iii) disclose advantages and limitations of the three synthetic approaches employed. Thus, this study complements our past research on SPPS-ET and suggests alternative conditions for microwave-assisted SPPS.
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Affiliation(s)
- Carina Loffredo
- Department of Biochemistry, Institute of Chemistry, University of São Paulo, P.O. Box 26077, 05513-970, São Paulo, Brazil
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Criddle DN, Booth DM, Mukherjee R, McLaughlin E, Green GM, Sutton R, Petersen OH, Reeve JR. Cholecystokinin-58 and cholecystokinin-8 exhibit similar actions on calcium signaling, zymogen secretion, and cell fate in murine pancreatic acinar cells. Am J Physiol Gastrointest Liver Physiol 2009; 297:G1085-92. [PMID: 19815626 PMCID: PMC2850092 DOI: 10.1152/ajpgi.00119.2009] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The gastrointestinal hormone CCK exists in various molecular forms, with differences in bioactivity between the well-characterized CCK-8 and larger CCK-58 previously reported. We have compared the effects of these peptides on cytosolic calcium concentration ([Ca(2+)](c)), mitochondrial metabolism, enzyme secretion, and cell fate in murine isolated pancreatic acinar cells using fluorescence confocal microscopy and patch-clamp electrophysiology. CCK-58 (1-10 pM) induced transient, oscillatory increases of [Ca(2+)](c), which showed apical to basolateral progression and were associated with a rise of mitochondrial NAD(P)H. CCK-58 (10 pM) induced zymogen exocytosis in isolated cells and amylase secretion from isolated cells and whole tissues. Hyperstimulation with supraphysiological CCK-58 (5 nM) induced a single large increase of [Ca(2+)](c) that declined to a plateau, which remained above the basal level 20 min after application and was dependent on external Ca(2+) entry. In cells dispersed from the same tissues, CCK-8 induced similar patterns of responses to those of CCK-58, with oscillatory increases of [Ca(2+)](c) at lower (pM) concentrations and sustained responses at 5 nM. CCK-58 and CCK-8 exhibited similar profiles of action on cell death, with increases in necrosis at high CCK-58 and CCK-8 (10 nM) that were not significantly different between peptides. The present experiments indicate that CCK-8 and CCK-58 have essentially identical actions on the acinar cell at high and low agonist concentrations, suggesting an action via the same receptor and that the differences observed in an intact rat model may result from indirect effects of the peptides. Our data strengthen the argument that CCK-58 is an important physiological form of this gastrointestinal hormone.
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Affiliation(s)
| | | | - Rajarshi Mukherjee
- 2Liverpool National Institute of Health Research Pancreatic Biomedical Research Unit, Royal Liverpool and Broadgreen University Hospitals, National Health Service Trust, Liverpool, United Kingdom;
| | - Euan McLaughlin
- 2Liverpool National Institute of Health Research Pancreatic Biomedical Research Unit, Royal Liverpool and Broadgreen University Hospitals, National Health Service Trust, Liverpool, United Kingdom;
| | - Gary M. Green
- 3University of Texas Health Science Center, San Antonio, Texas;
| | - Robert Sutton
- 2Liverpool National Institute of Health Research Pancreatic Biomedical Research Unit, Royal Liverpool and Broadgreen University Hospitals, National Health Service Trust, Liverpool, United Kingdom;
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Stengel A, Keire D, Goebel M, Evilevitch L, Wiggins B, Taché Y, Reeve JR. The RAPID method for blood processing yields new insight in plasma concentrations and molecular forms of circulating gut peptides. Endocrinology 2009; 150:5113-8. [PMID: 19819958 PMCID: PMC2775981 DOI: 10.1210/en.2009-0697] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
The correct identification of circulating molecular forms and measurement of peptide levels in blood entails that the endocrine peptide being studied is stable and recovered in good yields during blood processing. However, it is not clear whether this is achieved in studies using standard blood processing. Therefore, we compared peptide concentration and form of 12 (125)I-labeled peptides using the standard procedure (EDTA-blood on ice) and a new method employing Reduced temperatures, Acidification, Protease inhibition, Isotopic exogenous controls, and Dilution (RAPID). During standard processing there was at least 80% loss for calcitonin-gene-related peptide and cholecystokinin-58 (CCK-58) and more than 35% loss for amylin, insulin, peptide YY forms (PYY((1-36)) and PYY((3-36))), and somatostatin-28. In contrast, the RAPID method significantly improved the recovery for 11 of 12 peptides (P < 0.05) and eliminated the breakdown of endocrine peptides occurring after standard processing as reflected in radically changed molecular forms for CCK-58, gastrin-releasing peptide, somatostatin-28, and ghrelin. For endogenous ghrelin, this led to an acyl/total ghrelin ratio of 1:5 instead of 1:19 by the standard method. These results show that the RAPID method enables accurate assessment of circulating gut peptide concentrations and forms such as CCK-58, acylated ghrelin, and somatostatin-28. Therefore, the RAPID method represents an efficacious means to detect circulating variations in peptide concentrations and form relevant to the understanding of physiological function of endocrine peptides.
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Affiliation(s)
- Andreas Stengel
- University of California and CURE Digestive Disease Research Center, Building 115, Room 117, Veterans Affairs Greater Los Angeles Healthcare System, 11301 Wilshire Boulevard, Los Angeles, California 90073, USA
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13
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Wu SV, Harikumar KG, Burgess RJ, Reeve JR, Miller LJ. Effects of cholecystokinin-58 on type 1 cholecystokinin receptor function and regulation. Am J Physiol Gastrointest Liver Physiol 2008; 295:G641-7. [PMID: 18776046 PMCID: PMC2536789 DOI: 10.1152/ajpgi.90390.2008] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Cholecystokinin, like many peptide hormones, is present as multiple molecular forms. CCK-58 has been identified as the dominant form in the circulation, whereas most of the studies of CCK-receptor interactions have been performed with CCK-8. Despite both sharing the pharmacophoric region of CCK, representing its carboxy terminal heptapeptide amide, studies in vivo have demonstrated biological diversity of action of the two peptides, with CCK-58, but not CCK-8, stimulating pancreatic fluid secretion and lengthening the interval between meals. Here, we have directly studied the ability of these two CCK peptides to bind to the type 1 CCK receptor and to stimulate it to elicit an intracellular calcium response. The calcium response relative to receptor occupation was identical for CCK-58 and CCK-8, with the longer peptide binding with approximately fivefold lower affinity. We also examined the ability of the two peptides to elicit receptor internalization using morphological techniques and to disrupt the constitutive oligomerization of the CCK receptor using receptor bioluminescence resonance energy transfer. Here, both full agonist peptides had similar effects on these regulatory processes. These data suggest that both molecular forms of CCK act at the CCK1 receptor quite similarly and elicit similar regulatory processes for that receptor, suggesting that the differences in biological activity observed in vivo most likely reflect differences in the clearance and/or metabolism of these long and short forms of CCK peptides.
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Affiliation(s)
- S. Vincent Wu
- Mayo Clinic, Department of Molecular Pharmacology and Experimental Therapeutics, Scottsdale, Arizona; and CURE: Digestive Diseases Research Center, Veterans Affairs Greater Los Angeles Healthcare System, and Digestive Diseases Division, UCLA School of Medicine, Los Angeles, California
| | - Kaleeckal G. Harikumar
- Mayo Clinic, Department of Molecular Pharmacology and Experimental Therapeutics, Scottsdale, Arizona; and CURE: Digestive Diseases Research Center, Veterans Affairs Greater Los Angeles Healthcare System, and Digestive Diseases Division, UCLA School of Medicine, Los Angeles, California
| | - Rebecca J. Burgess
- Mayo Clinic, Department of Molecular Pharmacology and Experimental Therapeutics, Scottsdale, Arizona; and CURE: Digestive Diseases Research Center, Veterans Affairs Greater Los Angeles Healthcare System, and Digestive Diseases Division, UCLA School of Medicine, Los Angeles, California
| | - Joseph R. Reeve
- Mayo Clinic, Department of Molecular Pharmacology and Experimental Therapeutics, Scottsdale, Arizona; and CURE: Digestive Diseases Research Center, Veterans Affairs Greater Los Angeles Healthcare System, and Digestive Diseases Division, UCLA School of Medicine, Los Angeles, California
| | - Laurence J. Miller
- Mayo Clinic, Department of Molecular Pharmacology and Experimental Therapeutics, Scottsdale, Arizona; and CURE: Digestive Diseases Research Center, Veterans Affairs Greater Los Angeles Healthcare System, and Digestive Diseases Division, UCLA School of Medicine, Los Angeles, California
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14
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Green GM, Reeve JR. Unique activities of cholecystokinin-58; physiological and pathological relevance. Curr Opin Endocrinol Diabetes Obes 2008; 15:48-53. [PMID: 18185062 DOI: 10.1097/med.0b013e3282f3d92b] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
PURPOSE OF REVIEW Cholecystokinin, a regulatory peptide found in multiple molecular forms in brain and small intestine, is responsible for integration of functions associated with the intake, digestion and absorption of food. Whether the different molecular forms have identical biological activities is controversial. New information suggests that CCK58, the largest form of cholecystokinin detected in blood and tissue, has unique functions compared with other forms, and may be the predominant, perhaps only, circulating form in mammals. RECENT FINDINGS CCK58 has highly distinctive actions compared with shorter forms, most notably the strong stimulation of water secretion from the pancreas, and the lack of induction of pancreatitis by supramaximal doses of the peptide. Because CCK58 may be the main endogenous form of cholecystokinin, these recent findings have far reaching implications because almost all studies carried out with cholecystokinin have been done with shorter forms, predominately CCK8. Conclusions of studies using CCK8 or other shorter forms of cholecystokinin, therefore, may need to be reevaluated. SUMMARY There is a compelling reason to reevaluate the role of cholecystokinin in health and disease because the predominant form of cholecystokinin, CCK58, has unique biological activities compared with forms of cholecystokinin used in previous basic and clinical studies.
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Affiliation(s)
- Gary M Green
- Department of Physiology, University of Texas Health Science Center, San Antonio, Texas 78229-3900, USA.
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Sullivan CN, Raboin SJ, Gulley S, Sinzobahamvya NT, Green GM, Reeve JR, Sayegh AI. Endogenous cholecystokinin reduces food intake and increases Fos-like immunoreactivity in the dorsal vagal complex but not in the myenteric plexus by CCK1 receptor in the adult rat. Am J Physiol Regul Integr Comp Physiol 2007; 292:R1071-80. [PMID: 17082351 DOI: 10.1152/ajpregu.00490.2006] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
We hypothesized that endogenous CCK reduces food intake by activating the dorsal vagal complex (DVC) and the myenteric neurons of the gut. To test this hypothesis, adult rats were given camostat mesilate; a nonnutrient releaser of endogenous CCK, by orogastric gavage, and Fos-like immunoreactivity (Fos-LI) was quantified in the DVC and the myenteric plexus. The results for endogenous CCK were compared with those for exogenous CCK-8. Exogenous CCK-8 reduced food intake and stimulated Fos-LI in the DVC and in myenteric neurons of the duodenum and jejunum. In comparison, endogenous CCK reduced food intake and increased DVC Fos-LI but did not increase Fos-LI in the myenteric plexus. Similar to CCK-8, devazepide, a specific CCK1 receptor antagonist, and not L365,260, a specific CCK2 receptor antagonist, attenuated the reduction of food intake by camostat. In addition, Fos-LI in the DVC in response to both exogenous CCK-8 and camostat administration was significantly attenuated by vagotomy, as well as by blocking CCK1 receptors. These results demonstrate for the first time that reduction of food intake in adult rats by endogenous CCK released by a nonnutrient mechanism requires CCK1 receptors, the vagus nerve, and activation of the DVC, but not the myenteric plexus.
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Affiliation(s)
- Cherese N Sullivan
- Department of Biomedical Sciences, College of Veterinary Medicine, Tuskegee University, Tuskegee, AL 36088, USA
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Reeve JR, Rosenquist GL, Keire DA, Chew P, Nicholas HB, Davis MT, Lee TD, Shively JE, Backus RC. Crucial role of position 40 for interactions of CCK-58 revealed by sequence of cat CCK-58. Biochem Biophys Res Commun 2006; 348:819-25. [PMID: 16904071 DOI: 10.1016/j.bbrc.2006.07.081] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2006] [Accepted: 07/17/2006] [Indexed: 11/18/2022]
Abstract
Evidence suggests that amino terminal extensions of CCK-8 affect the carboxyl terminal bioactive region of CCK. Cat CCK-58 was purified by low pressure reverse phase and ion-exchange chromatography steps and several reverse phase HPLC steps. The purified peptide and its tryptic fragments were characterized by mass spectral analysis and microsequence analysis. The structure of cat CCK-58 is: AVQKVDGEPRAHLGALLARYIQQARKAPSGRMSVIKNLQSLDPSHRISDRDY(SO3) MGWMDF-amide. Cat and dog CCK-58 are identical except for position 40 which is serine in cat and asparagine in dog. Radioimmunoassay detected cat CCK-58 about 1/10th as well as dog CCK-58, indicating a marked effect on C-terminal immunoreactivity. Cat CCK-58 with a serine at position 40, the same residue found in pig, mouse, cow and rabbit CCK-58, can be used as a unique bioprobe for defining how amino terminal amino acids influence the structure and bioactivity of the carboxyl terminal region of CCK.
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Affiliation(s)
- Joseph R Reeve
- CURE: Digestive Diseases Research Center, Veterans Administration Greater Los Angeles Healthcare System, Los Angeles, CA 90073, USA
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Aras HC, Ekström J. Cholecystokinin- and gastrin-induced protein and amylase secretion from the parotid gland of the anaesthetized rat. ACTA ACUST UNITED AC 2006; 134:89-96. [PMID: 16515811 DOI: 10.1016/j.regpep.2006.01.004] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2005] [Revised: 01/26/2006] [Accepted: 01/27/2006] [Indexed: 10/25/2022]
Abstract
I.V. infusion of pentagastrin (20 microg/kg/h) or cholecystokinin (CCK)-8 (1 microg/kg/h) for 10 min caused secretion of salivary proteins from the parotid gland in the anaesthetized rat without any accompanying overt fluid secretion. This "occult" response was revealed by a subsequent wash-out injection of methacholine (5 microg/kg, I.V.) 10 min after the end of the infusion period (aiming at avoiding synergistic interactions). While the fluid response to methacholine was unaffected by the preceding infusion of pentagastrin and CCK-8, the output of protein increased by 147% (pentagastrin) and 74% (CCK-8) and that of amylase by 45% (CCK-8) compared to the responses to methacholine upon saline infusion. Those increases were abolished by the CCK-A receptor blocker (lorglumide), but not by the CCK-B receptor blocker (itriglumide). Evisceration, combined sympathetic and parasympathetic denervation of the glands and assay under adrenoceptor blockade excluded contribution from the gastro-intestinal tract, central or ganglionic mechanisms and circulating catecholamines to the increase in protein/amylase. Furthermore, Western blot demonstrated CCK receptors for both A and B subtypes in normal and chronically denervated glands. In the submandibular gland, both pentagastrin and CCK-8 evoked a trace secretion of saliva but, under the present experimental set-up, no statistically significant increase in protein output. Thus, in addition to the autonomic nervous system, gastrointestinal hormones may, in some types of glands, be involved in the secretion of salivary gland proteins.
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Affiliation(s)
- Hülya Cevik Aras
- Department of Pharmacology, Institute of Physiology and Pharmacology, The Sahlgrenska Academy at Göteborg University, Medicinaregatan 15 D, 413 90 Göteborg, Sweden
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Reeve JR, Liddle RA, Shively JE, Lee TD, Keire DA, Chew P, Vigna SR. Sequence variation outside the "active" region of dog and rabbit cholecystokinin-58 results in bioactivity differences. Pancreas 2006; 32:306-13. [PMID: 16628087 DOI: 10.1097/01.mpa.0000218315.04954.77] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/10/2022]
Abstract
OBJECTIVES We propose that regions outside the bioactive 7-amino acid carboxyl terminus of cholecystokinin (CCK)-58 influence its biological activity. Here we evaluate if sequence variation of the N-terminal regions of rabbit and canine CCK-58 changes their biological activities. METHODS Cholecystokinin-like immunoreactivity was purified from rabbit intestinal extracts by reverse phase and ion-exchange high-performance liquid chromatography steps. The peptide was characterized by microsequence and mass spectral characterizations of the intact and tryptic peptides. Canine and rabbit CCK-58 were evaluated for their CCK1 and CCK2 receptor binding, receptor activation, and immunologic properties. RESULTS The sequence of rabbit CCK-58 differs from that of canine CCK-58 in 9 of the amino terminal 40 residues. Canine CCK-58 was approximately 3-fold more potent than rabbit CCK-58 for CCK1 receptor binding and CCK2 receptor binding, but about the same potency for stimulation of amylase release from purified acinar cells. The canine peptide was 9-fold more immunoreactive than rabbit CCK-58. CONCLUSIONS Canine and rabbit CCK-58 have different biological and immunologic properties that can only result from differences in their N-terminal sequences which influence the properties of their identical carboxyl termini. These results are the first direct demonstration that amino acids outside the C-terminus of CCK-58 influence CCK biological activity.
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Affiliation(s)
- Joseph R Reeve
- CURE: Digestive Diseases Research Center, VA GLAHS, and Digestive Diseases Division, David Geffen School of Medicine at UCLA, Los Angeles, CA 90073, USA.
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Reynolds NA, Blum A, Kitagawa K, Beinfeld MC. Inhibition of PC5 expression decreases CCK secretion and increases PC2 expression. Peptides 2006; 27:901-4. [PMID: 16266771 DOI: 10.1016/j.peptides.2005.09.010] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/04/2005] [Revised: 09/15/2005] [Accepted: 09/26/2005] [Indexed: 10/25/2022]
Abstract
Cholecystokinin (CCK) is produced from pro CCK by a series of enzymatic cleavages. One of the enzymes thought to be important for pro CCK cleavage is prohormone convertase 5 (PC5). STC-1 cells, a mouse intestinal tumor cell line that expresses CCK, PC1, PC2, and PC5 were stably transfected with hairpin loop plasmids encoding siRNA targeting PC5 and clones were selected. CCK secretion was reduced significantly. PC5 mRNA and protein expression as measured by quantitative PCR and Western blot analysis was reduced about 50%. CCK and PC1 mRNA expression were not changed. These cells showed a three-fold increase in PC2 mRNA and protein expression. This increase may represent a compensatory mechanism triggered by the loss of PC5. The decrease in CCK in the media was due largely to loss of CCK 22. These results provide the first direct evidence that PC5 is involved in CCK processing.
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Affiliation(s)
- Nicole A Reynolds
- Department of Pharmacology and Experimental Therapeutics, Tufts School of Medicine, Boston, MA 02111, USA
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Water and enzyme secretion are tightly coupled in pancreatic secretion stimulated by food or CCK-58 but not by CCK-8. Am J Physiol Gastrointest Liver Physiol 2005; 288:G866-79. [PMID: 15550556 DOI: 10.1152/ajpgi.00389.2003] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Pancreatic secretion of protein, water, chloride, and bicarbonate under basal conditions and in response to intravenous and intraduodenal stimuli were studied in awake rats fully recovered from surgery. During the basal phase of pancreatic secretion, protein output and water output were weakly correlated or uncorrelated, consistent with separate regulation and distinct cellular origin of enzyme (acinar cells) and water (duct cells), referred to as the two-component paradigm of pancreatic secretion. When pancreatic secretion was stimulated physiologically, water and protein output abruptly became strongly and significantly correlated, suggesting that protein secretion and water secretion are tightly coupled or that protein secretion is dependent on water secretion. The apparent function of this coupling is to resist or prevent increases in protein concentration as protein output increases. This pattern of secretion was reproduced by intravenous infusion of the CCK-58 form of cholecystokinin, which strongly stimulates pancreatic water and chloride secretion, but not by CCK-8, which only weakly stimulates water and chloride secretion in a non-dose-dependent manner. The remarkably tight association of water and protein secretion in food-stimulated and CCK-58-stimulated pancreatic secretion is consistent with a single cell type as the origin of both water and enzyme secretion, i.e., the acinar cell, and is not consistent with the two-component paradigm of pancreatic secretion. Because CCK-58 is the only detectable endocrine form of cholecystokinin in the rat and its bioactivity pattern is markedly and qualitatively different from CCK-8, actions previously recorded for CCK-8 should be reexamined.
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