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Ruan H, Mandla R, Ravi N, Galang G, Soe AW, Olgin JE, Lang D, Vedantham V. Cholecystokinin-A signaling regulates automaticity of pacemaker cardiomyocytes. Front Physiol 2023; 14:1284673. [PMID: 38179138 PMCID: PMC10764621 DOI: 10.3389/fphys.2023.1284673] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2023] [Accepted: 12/08/2023] [Indexed: 01/06/2024] Open
Abstract
Aims: The behavior of pacemaker cardiomyocytes (PCs) in the sinoatrial node (SAN) is modulated by neurohormonal and paracrine factors, many of which signal through G-protein coupled receptors (GPCRs). The aims of the present study are to catalog GPCRs that are differentially expressed in the mammalian SAN and to define the acute physiological consequences of activating the cholecystokinin-A signaling system in isolated PCs. Methods and results: Using bulk and single cell RNA sequencing datasets, we identify a set of GPCRs that are differentially expressed between SAN and right atrial tissue, including several whose roles in PCs and in the SAN have not been thoroughly characterized. Focusing on one such GPCR, Cholecystokinin-A receptor (CCKAR), we demonstrate expression of Cckar mRNA specifically in mouse PCs, and further demonstrate that subsets of SAN fibroblasts and neurons within the cardiac intrinsic nervous system express cholecystokinin, the ligand for CCKAR. Using mouse models, we find that while baseline SAN function is not dramatically affected by loss of CCKAR, the firing rate of individual PCs is slowed by exposure to sulfated cholecystokinin-8 (sCCK-8), the high affinity ligand for CCKAR. The effect of sCCK-8 on firing rate is mediated by reduction in the rate of spontaneous phase 4 depolarization of PCs and is mitigated by activation of beta-adrenergic signaling. Conclusion: (1) PCs express many GPCRs whose specific roles in SAN function have not been characterized, (2) Activation of the cholecystokinin-A signaling pathway regulates PC automaticity.
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Affiliation(s)
- Hongmei Ruan
- *Correspondence: Hongmei Ruan, Vasanth Vedantham,
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2
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Harikumar KG, Coudrat T, Desai AJ, Dong M, Dengler DG, Furness SGB, Christopoulos A, Wootten D, Sergienko EA, Sexton PM, Miller LJ. Discovery of a Positive Allosteric Modulator of Cholecystokinin Action at CCK1R in Normal and Elevated Cholesterol. Front Endocrinol (Lausanne) 2021; 12:789957. [PMID: 34950108 PMCID: PMC8689142 DOI: 10.3389/fendo.2021.789957] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/05/2021] [Accepted: 11/11/2021] [Indexed: 11/13/2022] Open
Abstract
Drugs useful in prevention/treatment of obesity could improve health. Cholecystokinin (CCK) is a key regulator of appetite, working through the type 1 CCK receptor (CCK1R); however, full agonists have not stimulated more weight loss than dieting. We proposed an alternate strategy to target this receptor, while reducing likelihood of side effects and/or toxicity. Positive allosteric modulators (PAMs) with minimal intrinsic agonist activity would enhance CCK action, while maintaining spatial and temporal characteristics of physiologic signaling. This could correct abnormal stimulus-activity coupling observed in a high-cholesterol environment observed in obesity. We utilized high-throughput screening to identify a molecule with this pharmacological profile and studied its basis of action. Compound 1 was a weak partial agonist, with PAM activity to enhance CCK action at CCK1R, but not CCK2R, maintained in both normal and high cholesterol. Compound 1 (10 µM) did not exhibit agonist activity or stimulate internalization of CCK1R. It enhanced CCK activity by slowing the off-rate of bound hormone, increasing its binding affinity. Computational docking of Compound 1 to CCK1R yielded plausible poses. A radioiodinatable photolabile analogue retained Compound 1 pharmacology and covalently labeled CCK1R Thr211, consistent with one proposed pose. Our study identifies a novel, selective, CCK1R PAM that binds to the receptor to enhance action of CCK-8 and CCK-58 in both normal and disease-mimicking high-cholesterol environments. This facilitates the development of compounds that target the physiologic spatial and temporal engagement of CCK1R by CCK that underpins its critical role in metabolic regulation.
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Affiliation(s)
- Kaleeckal G. Harikumar
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Scottsdale, AZ, United States
| | - Thomas Coudrat
- Drug Discovery Biology Theme, Monash Institute for Pharmaceutical Sciences, Monash University, Parkville, VIC, Australia
- ARC (Australian Research Council) Centre for Cryo-electron Microscopy of Membrane Proteins, Monash Institute for Pharmaceutical Sciences, Monash University, Parkville, VIC, Australia
| | - Aditya J. Desai
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Scottsdale, AZ, United States
| | - Maoqing Dong
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Scottsdale, AZ, United States
| | - Daniela G. Dengler
- Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA, United States
| | - Sebastian G. B. Furness
- Drug Discovery Biology Theme, Monash Institute for Pharmaceutical Sciences, Monash University, Parkville, VIC, Australia
| | - Arthur Christopoulos
- Drug Discovery Biology Theme, Monash Institute for Pharmaceutical Sciences, Monash University, Parkville, VIC, Australia
- ARC (Australian Research Council) Centre for Cryo-electron Microscopy of Membrane Proteins, Monash Institute for Pharmaceutical Sciences, Monash University, Parkville, VIC, Australia
| | - Denise Wootten
- Drug Discovery Biology Theme, Monash Institute for Pharmaceutical Sciences, Monash University, Parkville, VIC, Australia
- ARC (Australian Research Council) Centre for Cryo-electron Microscopy of Membrane Proteins, Monash Institute for Pharmaceutical Sciences, Monash University, Parkville, VIC, Australia
| | - Eduard A. Sergienko
- Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA, United States
| | - Patrick M. Sexton
- Drug Discovery Biology Theme, Monash Institute for Pharmaceutical Sciences, Monash University, Parkville, VIC, Australia
- ARC (Australian Research Council) Centre for Cryo-electron Microscopy of Membrane Proteins, Monash Institute for Pharmaceutical Sciences, Monash University, Parkville, VIC, Australia
| | - Laurence J. Miller
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Scottsdale, AZ, United States
- *Correspondence: Laurence J. Miller,
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3
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Wang R, Lu Y, Cicha MZ, Singh MV, Benson CJ, Madden CJ, Chapleau MW, Abboud FM. TMEM16B determines cholecystokinin sensitivity of intestinal vagal afferents of nodose neurons. JCI Insight 2019; 4:122058. [PMID: 30843875 DOI: 10.1172/jci.insight.122058] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2018] [Accepted: 01/17/2019] [Indexed: 12/11/2022] Open
Abstract
The satiety effects and metabolic actions of cholecystokinin (CCK) have been recognized as potential therapeutic targets in obesity for decades. We identified a potentially novel Ca2+-activated chloride (Cl-) current (CaCC) that is induced by CCK in intestinal vagal afferents of nodose neurons. The CaCC subunit Anoctamin 2 (Ano2/TMEM16B) is the dominant contributor to this current. Its expression is reduced, as is CCK current activity in obese mice on a high-fat diet (HFD). Reduced expression of TMEM16B in the heterozygote KO of the channel in sensory neurons results in an obese phenotype with a loss of CCK sensitivity in intestinal nodose neurons, a loss of CCK-induced satiety, and metabolic changes, including decreased energy expenditure. The effect on energy expenditure is further supported by evidence in rats showing that CCK enhances sympathetic nerve activity and thermogenesis in brown adipose tissue, and these effects are abrogated by a HFD and vagotomy. Our findings reveal that Ano2/TMEM16B is a Ca2+-activated chloride channel in vagal afferents of nodose neurons and a major determinant of CCK-induced satiety, body weight control, and energy expenditure, making it a potential therapeutic target in obesity.
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Affiliation(s)
- Runping Wang
- Department of Internal Medicine.,Abboud Cardiovascular Research Center, and
| | - Yongjun Lu
- Department of Internal Medicine.,Abboud Cardiovascular Research Center, and
| | - Michael Z Cicha
- Department of Internal Medicine.,Abboud Cardiovascular Research Center, and
| | - Madhu V Singh
- Department of Internal Medicine.,Abboud Cardiovascular Research Center, and
| | - Christopher J Benson
- Department of Internal Medicine.,Abboud Cardiovascular Research Center, and.,Department of Molecular Physiology and Biophysics, University of Iowa, Iowa City, Iowa, USA.,Veterans Affairs Medical Center, Iowa City, Iowa, USA
| | - Christopher J Madden
- Department of Neurological Surgery, Oregon Health & Science University, Portland, Oregon, USA
| | - Mark W Chapleau
- Department of Internal Medicine.,Abboud Cardiovascular Research Center, and.,Department of Molecular Physiology and Biophysics, University of Iowa, Iowa City, Iowa, USA.,Veterans Affairs Medical Center, Iowa City, Iowa, USA
| | - François M Abboud
- Department of Internal Medicine.,Abboud Cardiovascular Research Center, and.,Department of Molecular Physiology and Biophysics, University of Iowa, Iowa City, Iowa, USA
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4
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Miller LJ, Desai AJ. Metabolic Actions of the Type 1 Cholecystokinin Receptor: Its Potential as a Therapeutic Target. Trends Endocrinol Metab 2016; 27:609-619. [PMID: 27156041 PMCID: PMC4992613 DOI: 10.1016/j.tem.2016.04.002] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/18/2016] [Revised: 03/31/2016] [Accepted: 04/05/2016] [Indexed: 12/13/2022]
Abstract
Cholecystokinin (CCK) regulates appetite and reduces food intake by activating the type 1 CCK receptor (CCK1R). Attempts to develop CCK1R agonists for obesity have yielded active agents that have not reached clinical practice. Here we discuss why, along with new strategies to target CCK1R more effectively. We examine signaling events and the possibility of developing agents that exhibit ligand-directed bias, to dissociate satiety activity from undesirable side effects. Potential allosteric sites of modulation are also discussed, along with desired properties of a positive allosteric modulator (PAM) without intrinsic agonist action as another strategy to treat obesity. These new types of CCK1R-active drugs could be useful as standalone agents or as part of a rational drug combination for management of obesity.
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Affiliation(s)
- Laurence J Miller
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Scottsdale, AZ, 85259, USA.
| | - Aditya J Desai
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Scottsdale, AZ, 85259, USA
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5
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Staljanssens D, Rico CA, Park M, Van Camp J, Yu N, Huber T, Sakmar TP, Smagghe G. Development of a CCK1R-membrane nanoparticle as a fish-out tool for bioactive peptides. Peptides 2015; 68:219-27. [PMID: 25451329 DOI: 10.1016/j.peptides.2014.10.015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/27/2014] [Revised: 10/17/2014] [Accepted: 10/20/2014] [Indexed: 11/22/2022]
Abstract
The cholecystokinin receptor type 1 (CCK1R) is a G protein-coupled receptor (GPCR) that is involved in several biological processes including the regulation of the secretion of digestive enzymes. The peptide hormone cholecystokinin (CCK) binds to CCK1R, which is an important pharmacological target for several diseases, including obesity. Interestingly, nutritional dietary peptides also appear to activate CCK1R, and may play a role in CCK1R signaling in the gut. In this study, a novel technique to screen for CCK1R ligands based on affinity-selection is described. Functional expressed CCK1R is reconstituted into membrane nanoparticles called NABBs (nanoscale apo-lipoprotein bound bilayers). NABBs are native-like bilayer membrane systems for incorporation of GPCRs. CCK1R-NABBs were characterized using a fluorescently labeled CCK analog and can be used as a cutting-edge technology to screen for CCK1R ligands using affinity-selection mass spectrometry.
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Affiliation(s)
- Dorien Staljanssens
- Department of Crop Protection, Faculty of Bioscience Engineering, Ghent University, Ghent, Belgium; Department of Food Safety and Food Quality, Faculty of Bioscience Engineering, Ghent University, Ghent, Belgium
| | - Carlos A Rico
- Laboratory of Chemical Biology & Signal Transduction, The Rockefeller University, New York, NY 10065, USA
| | - Minyoung Park
- Laboratory of Chemical Biology & Signal Transduction, The Rockefeller University, New York, NY 10065, USA
| | - John Van Camp
- Department of Food Safety and Food Quality, Faculty of Bioscience Engineering, Ghent University, Ghent, Belgium
| | - Na Yu
- Department of Crop Protection, Faculty of Bioscience Engineering, Ghent University, Ghent, Belgium
| | - Thomas Huber
- Laboratory of Chemical Biology & Signal Transduction, The Rockefeller University, New York, NY 10065, USA
| | - Thomas P Sakmar
- Laboratory of Chemical Biology & Signal Transduction, The Rockefeller University, New York, NY 10065, USA; Center for Alzheimer Research, Division for Neurogeriatrics, Department of Neurobiology, Care Sciences and Society, Karolinska Institute, SE-141 57 Huddinge, Sweden
| | - Guy Smagghe
- Department of Crop Protection, Faculty of Bioscience Engineering, Ghent University, Ghent, Belgium.
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Sayegh AI, Washington MC, Raboin SJ, Aglan AH, Reeve JR. CCK-58 prolongs the intermeal interval, whereas CCK-8 reduces this interval: not all forms of cholecystokinin have equal bioactivity. Peptides 2014; 55:120-5. [PMID: 24607725 DOI: 10.1016/j.peptides.2014.02.014] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/12/2014] [Revised: 02/20/2014] [Accepted: 02/20/2014] [Indexed: 01/09/2023]
Abstract
It has been accepted for decades that "all forms of cholecystokinin (CCK) have equal bioactivity," despite accumulating evidence to the contrary. To challenge this concept, we compared two feeding responses, meal size (MS, 10% sucrose) and intermeal interval (IMI), in response to CCK-58, which is the major endocrine form of CCK, and CCK-8, which is the most abundantly utilized form. Doses (0, 0.1, 0.5, 0.75, 1, 3 and 5 nmol/kg) were administered intraperitoneally over a 210-min test to Sprague Dawley rats that had been food-deprived overnight. We found that (1) all doses of CCK-58, except the lowest dose, and all doses of CCK-8, except the lowest two doses, reduced food intake more than vehicle did; (2) at two doses, 0.75 and 3 nmol/kg, CCK-58 increased the IMI, while CCK-8 failed to alter this feeding response; and (3) CCK-58, at all but the lowest two doses, increased the satiety ratio (IMI between first and second meals (min) divided by first MS (ml)) relative to vehicle, while CCK-8 did not affect this value. These findings demonstrate that the only circulating form of CCK in rats, CCK-58, prolongs the IMI more than CCK-8, the peptide generally utilized in feeding studies. Taken together, these results add to a growing list of functions where CCK-8 and CCK-58 express qualitatively different bioactivities. In conclusion, the hypothesis that "all forms of cholecystokinin (CCK) have equal bioactivity" is not supported.
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Affiliation(s)
- Ayman I Sayegh
- Gastroenterology Laboratory, Department of Biomedical Sciences, College of Veterinary Medicine, Tuskegee University, Tuskegee, AL, United States.
| | - Martha C Washington
- Gastroenterology Laboratory, Department of Biomedical Sciences, College of Veterinary Medicine, Tuskegee University, Tuskegee, AL, United States
| | - Shannon J Raboin
- Gastroenterology Laboratory, Department of Biomedical Sciences, College of Veterinary Medicine, Tuskegee University, Tuskegee, AL, United States
| | - Amnah H Aglan
- School of Medicine, Wayne State University, Detroit, MI, United States
| | - Joseph R Reeve
- CURE: Digestive Diseases Research Center, Veterans Administration Greater Los Angeles Healthcare System, and Digestive Diseases Division, School of Medicine, University of California, Los Angeles, CA, United States
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7
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Overduin J, Gibbs J, Cummings DE, Reeve JR. CCK-58 elicits both satiety and satiation in rats while CCK-8 elicits only satiation. Peptides 2014; 54:71-80. [PMID: 24468546 PMCID: PMC3989439 DOI: 10.1016/j.peptides.2014.01.008] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/16/2013] [Revised: 01/14/2014] [Accepted: 01/15/2014] [Indexed: 11/18/2022]
Abstract
Reduction of food intake by exogenous cholecystokinin (CCK) has been demonstrated primarily for its short molecular form, CCK-8. Mounting evidence, however, implicates CCK-58 as a major physiologically active CCK form, with different neural and exocrine response profiles than CCK-8. In three studies, we compared meal-pattern effects of intraperitoneal injections CCK-8 vs. CCK-58 in undeprived male Sprague-Dawley rats consuming sweetened condensed milk. In study 1, rats (N=10) received CCK-8, CCK-58 (0.45, 0.9, 1.8 and 3.6 nmol/kg) or vehicle before a 4-h test-food presentation. At most doses, both CCK-8 and CCK-58 similarly reduced meal size relative to vehicle. Meal-size reduction prompted a compensatory shortening of the intermeal interval (IMI) after CCK-8, but not after CCK-58, which uniquely increased the satiety ratio (IMI/size of the preceding meal). In the second study, lick patterns were monitored after administration of 0.9 nmol/kg CCK-58, CCK-8 or vehicle. Lick cluster size, lick efficiency and interlick-interval distribution remained unaltered compared to vehicle, implying natural satiation, rather than illness, following both CCK forms. In study 3, threshold satiating doses of the two CCK forms were given at 5 and 30 min after meal termination, respectively. CCK 58, but not CCK-8 increased the intermeal interval and satiety ratio compared to vehicle. In conclusion, while CCK 58 and CCK-8 both stimulate satiation, thereby reducing meal size, CCK-58 consistently exerts a satiety effect, prolonging IMI. Given the physiological prominence of CCK-58, these results suggest that CCK's role in food intake regulation may require re-examination.
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Affiliation(s)
- Joost Overduin
- Weill Medical College, Cornell University, White Plains, NY 10605, USA; Veterans Administration Puget Sound Health Care System, Office of Research and Development Medical Research Service, Seattle, WA 98108, USA; Division of Metabolism, Endocrinology and Nutrition, Department of Medicine, University of Washington School of Medicine, Seattle, WA 98195, USA
| | - James Gibbs
- Weill Medical College, Cornell University, White Plains, NY 10605, USA
| | - David E Cummings
- Veterans Administration Puget Sound Health Care System, Office of Research and Development Medical Research Service, Seattle, WA 98108, USA; Division of Metabolism, Endocrinology and Nutrition, Department of Medicine, University of Washington School of Medicine, Seattle, WA 98195, USA
| | - Joseph R Reeve
- Division of Digestive Diseases, David Geffen School of Medicine at UCLA and CURE: Digestive Diseases Research Center, Veterans Administration, Los Angeles, CA 90073, USA.
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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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Cevik-Aras H, Ekström J. Anti-inflammatory action of cholecystokinin and melatonin in the rat parotid gland. Oral Dis 2010; 16:661-7. [PMID: 20846152 DOI: 10.1111/j.1601-0825.2010.01672.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
OBJECTIVE To define the influence of cholecystokinin and melatonin on the inflammatory response of the lipopolysaccharide-exposed rat parotid gland. MATERIALS AND METHODS Bacterial lipopolysaccharide was infused retrogradely into the parotid duct. The degree of inflammation three hours postadministration was estimated from the activity of myeloperoxidase, reflecting glandular neutrophil infiltration. RESULTS The myeloperoxidase activity of the lipopolysaccharide-exposed gland was 10-fold greater than that of the contralateral gland. Combined with sulphated cholecystokinin-8 (10 or 25 μg kg(-1) , given twice intraperitoneally) or melatonin (10 or 25 mg kg(-1) x 2) the lipopolysaccharide-induced response was elevated 4.6- and 3.5-folds at the most. The cholecystokinin-A receptor antagonist lorglumide reduced the inhibitory effect of cholecystokinin-8, while the melatonin 2-preferring receptor antagonist luzindole had no effect on the melatonin-induced inhibition. Unselective nitric oxide-synthase inhibition abolished the increase in myeloperoxidase activity, whereas inhibition of inducible or neuronal nitric oxide-synthase (of non-nervous origin) halved the inflammatory response. CONCLUSION Some hormones may contribute to anti-inflammatory action in salivary glands in physiological conditions. They are potential pharmacological tools for treating gland inflammation. The inflammation, as judged from the myeloperoxidase activity, was entirely dependent on nitric oxide-synthase activity, indicating that the hormones directly or indirectly reduced the generation of nitric oxide.
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Affiliation(s)
- H Cevik-Aras
- Division of Pharmacology, Institute of Neuroscience and Physiology, Sahlgrenska Academy at the University of Gothenburg, Göteborg, Sweden
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Abstract
PURPOSE OF REVIEW This review identifies and puts into context the recent articles which have advanced understanding of the functions of pancreatic acinar cells and the mechanisms by which these functions are regulated. RECENT FINDINGS Receptors present on acinar cells, particularly those for cholecystokinin and secretin, have been better characterized as to the molecular nature of the ligand-receptor interaction. Other reports have described the potential regulation of acinar cells by GLP-1 and cannabinoids. Intracellular Ca2+ signaling remains at the center of stimulus secretion coupling and its regulation has been further defined. Recent studies have identified specific channels mediating Ca2+ release from intracellular stores and influx across the plasma membrane. Work downstream of intracellular mediators has focused on molecular mechanisms of exocytosis particularly involving small G proteins, SNARE proteins and chaperone molecules. In addition to secretion, recent studies have further defined the regulation of pancreatic growth both in adaptive regulation to diet and hormones in the regeneration that occurs after pancreatic damage. Lineage tracing has been used to show the contribution of different cell types. The importance of specific amino acids as signaling molecules to activate the mTOR pathway is being elucidated. SUMMARY Understanding the mechanisms that regulate pancreatic acinar cell function is contributing to knowledge of normal pancreatic function and alterations in disease.
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Teubner BJ, Bartness TJ. Cholecystokinin-33 acutely attenuates food foraging, hoarding and intake in Siberian hamsters. Peptides 2010; 31:618-24. [PMID: 20025915 PMCID: PMC2837760 DOI: 10.1016/j.peptides.2009.12.010] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/21/2009] [Revised: 12/04/2009] [Accepted: 12/07/2009] [Indexed: 11/26/2022]
Abstract
Neurochemicals that stimulate food foraging and hoarding in Siberian hamsters are becoming more apparent, but we do not know if cessation of these behaviors is due to waning of excitatory stimuli and/or the advent of inhibitory factors. Cholecystokinin (CCK) may be such an inhibitory factor as it is the prototypic gastrointestinal satiety peptide and is physiologically important in decreasing food intake in several species including Siberian hamsters. Systemic injection of CCK-33 in laboratory rats decreases food intake, doing so to a greater extent than CCK-8. We found minimal effects of CCK-8 on food foraging and hoarding previously in Siberian hamsters, but have not tested CCK-33. Therefore, we asked: Does CCK-33 decrease normal levels or food deprivation-induced increases in food foraging, hoarding and intake? Hamsters were housed in a wheel running-based foraging system with simulated burrows to test the effects of peripheral injections of CCK-33 (13.2, 26.4, or 52.8 microg/kg body mass), with or without a preceding 56 h food deprivation. The highest dose of CCK-33 caused large baseline reductions in all three behaviors for the 1st hour post-injection compared with saline; in addition, the intermediate CCK-33 dose was sufficient to curtail food intake and foraging during the 1st hour. In food-deprived hamsters, we used a 52.8 microg/kg body mass dose of CCK-33 which decreased food intake, hoarding, and foraging almost completely compared with saline controls for 1h. Therefore, CCK-33 appears to be a potent inhibitor of food intake, hoarding, and foraging in Siberian hamsters.
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Affiliation(s)
| | - Timothy J. Bartness
- To whom correspondence should be addressed: Dr. Timothy J. Bartness, Department of Biology, Georgia State University, 24 Peachtree Center Ave. NE, Atlanta, GA 30302-4010, Fax: 404 413-5334,
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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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