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Anjom-Shoae J, Fitzgerald PC, Horowitz M, Mohammadpour Z, Hall GV, Holst JJ, Rehfeld JF, Veedfald S, Feinle-Bisset C. Intraduodenal calcium enhances the effects of L-tryptophan to stimulate gut hormone secretion and suppress energy intake in healthy males: a randomized, crossover, clinical trial. Am J Clin Nutr 2024:S0002-9165(24)00602-6. [PMID: 38996913 DOI: 10.1016/j.ajcnut.2024.07.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2024] [Revised: 06/05/2024] [Accepted: 07/08/2024] [Indexed: 07/14/2024] Open
Abstract
BACKGROUND In humans, intraduodenal infusion of L-tryptophan (Trp) increases plasma concentrations of gastrointestinal hormones and stimulates pyloric pressures, both key determinants of gastric emptying and associated with potent suppression of energy intake. The stimulation of gastrointestinal hormones by Trp has been shown, in preclinical studies, to be enhanced by extracellular calcium and mediated in part by the calcium-sensing receptor. OBJECTIVES This study aim was to determine whether intraduodenal calcium can enhance the effects of Trp to stimulate gastrointestinal hormones and pyloric pressures and, if so, whether it is associated with greater suppression of energy intake, in healthy males. METHODS Fifteen males with normal weight (mean ± standard deviation; age: 26 ± 7 years; body mass index: 22 ± 2 kg/m2), received on 3 separate occasions, 150-min intraduodenal infusions of 0, 500, or 1000 mg calcium (Ca), each combined with Trp (load: 0.1 kcal/min, with submaximal energy intake-suppressant effects) from t = 75-150 min, in a randomized, double-blind, crossover study. Plasma concentrations of GI hormones [gastrin, cholecystokinin, glucose-dependent insulinotropic polypeptide (GIP), glucagon-like peptide (GLP)-1, and peptide tyrosine-tyrosine (PYY)], and Trp and antropyloroduodenal pressures were measured throughout. Immediately postinfusions (t = 150-180 min), energy intake at a standardized buffet-style meal was quantified. RESULTS In response to calcium alone, both 500- and 1000-mg doses stimulated PYY, while only the 1000-mg dose stimulated GLP-1 and pyloric pressures (all P < 0.05). The 1000-mg dose also enhanced the effects of Trp to stimulate cholecystokinin and GLP-1, and both doses stimulated PYY but, surprisingly, reduced the stimulation of GIP (all P < 0.05). Both doses substantially and dose dependently enhanced the effects of Trp to suppress energy intake (Ca-0+Trp: 1108 ± 70 kcal; Ca-500+Trp: 961 ± 90 kcal; and Ca-1000+Trp: 922 ± 96 kcal; P < 0.05). CONCLUSIONS Intraduodenal administration of calcium enhances the effect of Trp to stimulate plasma cholecystokinin, GLP-1, and PYY and suppress energy intake in healthy males. These findings have potential implications for novel nutrient-based approaches to energy intake regulation in obesity. The trial was registered at the Australian New Zealand Clinical Trial Registry (www.anzctr.org.au) as ACTRN12620001294943).
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Affiliation(s)
- Javad Anjom-Shoae
- Adelaide Medical School and Center of Research Excellence in Translating Nutritional Science to Good Health, University of Adelaide, Adelaide, Australia
| | - Penelope Ce Fitzgerald
- Adelaide Medical School and Center of Research Excellence in Translating Nutritional Science to Good Health, University of Adelaide, Adelaide, Australia
| | - Michael Horowitz
- Adelaide Medical School and Center of Research Excellence in Translating Nutritional Science to Good Health, University of Adelaide, Adelaide, Australia; Endocrine and Metabolic Unit, Royal Adelaide Hospital, Adelaide, Australia
| | - Zinat Mohammadpour
- South Australian Health and Medical Research Institute, Adelaide, Australia
| | - Gerrit van Hall
- Department of Biomedical Sciences and the Novo Nordisk Foundation Center for Basic Metabolic Research, University of Copenhagen, Copenhagen, Denmark; Department of Clinical Biochemistry, Rigshospitalet, Copenhagen, Denmark
| | - Jens J Holst
- Department of Biomedical Sciences and the Novo Nordisk Foundation Center for Basic Metabolic Research, University of Copenhagen, Copenhagen, Denmark
| | - Jens F Rehfeld
- Department of Clinical Biochemistry, Rigshospitalet, Copenhagen, Denmark
| | - Simon Veedfald
- Department of Biomedical Sciences and the Novo Nordisk Foundation Center for Basic Metabolic Research, University of Copenhagen, Copenhagen, Denmark
| | - Christine Feinle-Bisset
- Adelaide Medical School and Center of Research Excellence in Translating Nutritional Science to Good Health, University of Adelaide, Adelaide, Australia.
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Mabilleau G, Bouvard B. Gut hormone analogues and skeletal health in diabetes and obesity: Evidence from preclinical models. Peptides 2024; 177:171228. [PMID: 38657908 DOI: 10.1016/j.peptides.2024.171228] [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: 01/22/2024] [Revised: 04/17/2024] [Accepted: 04/22/2024] [Indexed: 04/26/2024]
Abstract
Diabetes mellitus and obesity are rapidly growing worldwide. Aside from metabolic disturbances, these two disorders also affect bone with a higher prevalence of bone fractures. In the last decade, a growing body of evidence suggested that several gut hormones, including ghrelin, gastrin, glucose-dependent insulinotropic polypeptide (GIP), glucagon, and glucagon-like peptide-1 and 2 (GLP-1 and GLP-2, respectively) may affect bone physiology. Several gut hormone analogues have been developed for the treatment of type 2 diabetes and obesity, and could represent a new alternative in the therapeutic arsenal against bone fragility. In the present review, a summary of the physiological roles of these gut hormones and their analogues is presented at the cellular level but also in several preclinical models of bone fragility disorders including type 2 diabetes mellitus, especially on bone mineral density, microarchitecture and bone material properties. The present review also summarizes the impact of GLP-1 receptor agonists approved for the treatment of type 2 diabetes mellitus and the more recent dual or triple analogue on bone physiology and strength.
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Affiliation(s)
- Guillaume Mabilleau
- Univ Angers, Nantes Université, ONIRIS, Inserm, RMeS, UMR 1229, SFR ICAT, Angers F-49000, France; CHU Angers, Département de Pathologie Cellulaire et Tissulaire, UF de Pathologie osseuse, Angers F-49933, France.
| | - Béatrice Bouvard
- Univ Angers, Nantes Université, ONIRIS, Inserm, RMeS, UMR 1229, SFR ICAT, Angers F-49000, France; CHU Angers, Service de Rhumatologie, Angers F-49933, France
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3
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Vose J, Jaffey J, Akin C, Spitzer A, DeCicco B, Bassiouny E, LaClair A, Petroff B, Brudvig J, Cridge H. Serum gastrin concentrations in dogs with primary hyperparathyroidism. J Vet Intern Med 2024; 38:123-129. [PMID: 38031928 PMCID: PMC10800197 DOI: 10.1111/jvim.16940] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2023] [Accepted: 11/02/2023] [Indexed: 12/01/2023] Open
Abstract
BACKGROUND Hypercalcemia has been associated with hypergastrinemia in humans. Hypergastrinemia could be responsible for gastrointestinal (GI) signs in dogs with primary hyperparathyroidism (PHPT). HYPOTHESIS/OBJECTIVES (a) Determine whether hypergastrinemia occurs in dogs with PHPT, (b) assess for potential correlations among ionized calcium (iCa), parathyroid hormone (PTH), and serum gastrin concentrations, and (c) determine whether gastrin concentrations decrease after management of PHPT. ANIMALS Phase 1: 151 client-owned dogs at the time of PHPT diagnosis, Phase 2: 24 dogs that underwent treatment for PHPT. METHODS Dogs with azotemia, concurrent disease, or those receiving acid suppressants were excluded. Twenty-four treated dogs had baseline and repeat quantification of serum gastrin, PTH, and iCa concentrations 4 weeks after treatment. The effect of treatment on gastrin, iCa, and PTH concentrations was assessed using Wilcoxon signed rank sum tests. Fisher exact testing was used to compare the proportion of dogs with hypergastrinemia in dogs with and without GI signs. RESULTS Twenty-seven of 151 PHPT dogs (17.9%) had increased pre-treatment serum gastrin concentrations (median, 45.0 ng/L; interquartile range [IQR], 20.0 ng/L). Gastrin concentrations were not correlated with iCa (P = .92) or PTH (P = .60). Treatment of PHPT decreased PTH (P < .001) and iCa concentrations (P < .001), but not gastrin concentrations (P = .15). The proportion of dogs with hypergastrinemia with and without GI signs did not differ (P = 1.00). CONCLUSIONS AND CLINICAL IMPORTANCE Mild increases in serum gastrin concentrations may be seen in dogs with PHPT, but this finding is independent of the presence of GI signs.
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Affiliation(s)
- Julieann Vose
- Department of Small Animal Clinical Sciences, College of Veterinary MedicineMichigan State UniversityEast Lansing, MichiganUSA
| | - Jared Jaffey
- Department of Specialty Medicine, College of Veterinary MedicineMidwestern UniversityGlendale, ArizonaUSA
| | - Camille Akin
- Department of Small Animal Clinical Sciences, College of Veterinary MedicineMichigan State UniversityEast Lansing, MichiganUSA
| | - Alexander Spitzer
- Department of Small Animal Clinical Sciences, College of Veterinary MedicineMichigan State UniversityEast Lansing, MichiganUSA
| | - Barry DeCicco
- Center for Statistical Training and Consulting (CSTAT)Michigan State UniversityEast Lansing, MichiganUSA
| | - Enass Bassiouny
- Veterinary Diagnostic LaboratoryMichigan State UniversityLansing, MichiganUSA
| | - Ashley LaClair
- Veterinary Diagnostic LaboratoryMichigan State UniversityLansing, MichiganUSA
| | - Brian Petroff
- Veterinary Diagnostic LaboratoryMichigan State UniversityLansing, MichiganUSA
| | - Jean Brudvig
- Veterinary Diagnostic LaboratoryMichigan State UniversityLansing, MichiganUSA
| | - Harry Cridge
- Department of Small Animal Clinical Sciences, College of Veterinary MedicineMichigan State UniversityEast Lansing, MichiganUSA
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Băetu M, Olariu CA, Moldoveanu G, Corneci C, Badiu C. Calcitonin Stimulation Tests: Rationale, Technical Issues and Side Effects: A Review. Horm Metab Res 2021; 53:355-363. [PMID: 34154026 DOI: 10.1055/a-1487-6449] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Calcitonin (CT) stimulation tests have great value and could help to: differentiate thyroid causes of elevated CT apart from non-thyroid sources, determine whether the patients with slightly elevated basal CT could/could not be candidates for surgery, and indicate the right moment for prophylactic thyroidectomy in children with MEN syndromes when with normal basal CT. This triggered the requests for development of CT stimulation tests, taking into consideration their safety and aimed us to write a systematic review of literature regarding the rationale, technical issues, and side effects of CT stimulating tests used for diagnosis of MTC. After a thorough review of the literature, we classified the reported side effects by severity, as defined by United States Food and Drug Administration. A statistical analysis was performed using IBM SPSS Statistics version 20. Various side effects were noticed during stimulation tests that differ by intensity, duration and severity, depending on types of substances and protocols used. The side effects after pentagastrin test were significantly more severe than those reported after calcium stimulation test (p=0.0396). There are also significant gender-specific differences in side effects induced by stimulation tests. In conclusion, we recommend performing Ca CT stimulation test when needed, considering preventive evaluation of some clinical, instrumental, and biochemical aspects of each patient. Precise instructions should be followed before a stimulation test and furthermore continuous cardiac monitoring is essential during and after the test to minimize the possibility of a serious event.
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Affiliation(s)
- Mara Băetu
- "C.I. Parhon" National Institute of Endocrinology, Bucharest, Romania
| | | | - Gabriel Moldoveanu
- "C.I. Parhon" National Institute of Endocrinology, Bucharest, Romania
- "Carol Davila" University of Medicine and Pharmacy, Bucharest, Romania
| | - Cristina Corneci
- "C.I. Parhon" National Institute of Endocrinology, Bucharest, Romania
| | - Corin Badiu
- "C.I. Parhon" National Institute of Endocrinology, Bucharest, Romania
- "Carol Davila" University of Medicine and Pharmacy, Bucharest, Romania
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Castle C, Tietjens J. Perforated gastric ulcer as the initial manifestation of hyperparathyroidism. BMJ Case Rep 2021; 14:14/4/e240570. [PMID: 33849869 PMCID: PMC8051396 DOI: 10.1136/bcr-2020-240570] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
Primary hyperparathyroidism is characterised by autonomous production of parathyroid hormone resulting in hypercalcaemia. It is estimated that 12% of these patients present with peptic ulcer-related symptoms. The pathophysiological mechanism is not well established, but studies reveal serum calcium activating gastrin cell calcium receptors ultimately resulting in increased gastric acid production leading to peptic ulcer disease. A patient presented acutely to our service with peptic ulcer perforation in the context of incidentally elevated serum calcium levels. Further inpatient investigations lead to the diagnosis of primary hyperparathyroidism as the first manifestation of this patient's disease.
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Affiliation(s)
- Cameron Castle
- General Surgery, Hutt Valley District Health Board, Lower Hutt, New Zealand
| | - James Tietjens
- General Surgery, Hutt Valley District Health Board, Lower Hutt, New Zealand.,University of Otago, Wellington, New Zealand
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Hackeng WM, Dreijerink KMA, Offerhaus GJA, Brosens LAA. A Parathyroid-Gut Axis: Hypercalcemia and the Pathogenesis of Gastrinoma in Multiple Endocrine Neoplasia 1. Mol Cancer Res 2021; 19:946-949. [PMID: 33771883 DOI: 10.1158/1541-7786.mcr-21-0073] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2021] [Revised: 02/24/2021] [Accepted: 03/23/2021] [Indexed: 11/16/2022]
Abstract
Patients with multiple endocrine neoplasia 1 (MEN1) syndrome have a germline mutation in the MEN1 gene. Loss of the wild-type allele can initiate endocrine tumorigenesis. Microscopic and macroscopic pituitary, parathyroid, and pancreatic tumors (referred to as the 3 P's) show loss of the wild-type MEN1 allele up to 100%. In contrast, the duodenal gastrinoma pathogenesis in MEN1 syndrome follows a hyperplasia-to-neoplasia sequence. Gastrinomas have loss of heterozygosity of the MEN1 locus in <50%, and invariably coincide with linear, diffuse, or micronodular gastrin-cell hyperplasia. The factor initiating the gastrin-cell hyperplasia-to-neoplasia sequence is unknown. In this perspective, we argue that hypercalcemia may promote the gastrin-cell hyperplasia-to-neoplasia sequence through the calcium sensing receptor. Hypercalcemia is present in almost all patients with MEN1 syndrome due to parathyroid adenomas. We propose a parathyroid-gut axis, which could well explain why patients with MEN1 syndrome are regularly cured of duodenal gastrinoma after parathyroid surgery, and might cause MEN1 syndrome phenocopies in MEN1-mutation negative individuals with parathyroid adenomas. This perspective on the pathogenesis of the gastrin-cell hyperplasia and neoplasia sequence sheds new light on tumorigenic mechanisms in neuroendocrine tumors and might open up novel areas of gastrinoma research. It may also shift focus in the treatment of MEN1 syndrome-related gastrinoma to biochemical prevention.
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Affiliation(s)
- Wenzel M Hackeng
- Department of Pathology, University Medical Center Utrecht, the Netherlands.
| | - Koen M A Dreijerink
- Department of Endocrinology, Amsterdam University Medical Center, the Netherlands
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Jedidi S, Aloui F, Rtibi K, Sammari H, Selmi H, Rejeb A, Toumi L, Sebai H. Individual and synergistic protective properties of Salvia officinalis decoction extract and sulfasalazine against ethanol-induced gastric and small bowel injuries. RSC Adv 2020; 10:35998-36013. [PMID: 35517119 PMCID: PMC9056994 DOI: 10.1039/d0ra03265d] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2020] [Accepted: 09/22/2020] [Indexed: 12/12/2022] Open
Abstract
The present study was carried out to determine the phytochemical composition of Salvia officinalis flowers decoction extract (SOFDE) as well as its individual and/or synergistic actions with sulfasalazine against ethanol (EtOH)-induced peptic ulcer in Wistar rats. In this respect, rats were divided into six groups of eight animals each: control, EtOH, EtOH + sulfasalazine (SULF, 100 mg kg-1, b.w., p.o.), mixture: MIX (SOFDE, 50 mg kg-1 b.w., p.o. + SULF, 50 mg kg-1, b.w., p.o.) and EtOH + two doses of SOFDE (100 and 200 mg kg-1 b.w., p.o.). In vitro, the phytochemical and the antioxidant properties were determined using colorimetric analysis. HPLC-PDA/ESI-MS assay was used to identify the distinctive qualitative profile of phenolic compounds. Our results firstly indicated that SOFDE is rich in total tannins, flavonols, anthocyanins and a moderate concentration of total carotenoids. Chromatographic techniques allowed the identification of 13 phenolic compounds and the major ones are quinic acid, protocatechuic acid, gallic acid and salviolinic acid. SOFDE also exhibited an important in vitro antioxidant activity using the β-carotene bleaching method. In vivo, SOFDE and the mixture provide significant protection against ethanol-induced gastric and duodenal macroscopic and histological alterations. Also, SOFDE alone or in combination with SULF, showed a significant protection against the secretory profile disturbances, lipid peroxidation, antioxidant enzyme activities and non-enzymatic antioxidant level depletion induced by alcohol administration. Importantly, we showed that EtOH acute intoxication increased gastric and intestinal calcium, free iron, magnesium and hydrogen peroxide (H2O2) levels, while SOFDE/MIX treatment protected against all these intracellular mediators' deregulation. We also showed that alcohol treatment significantly increased the C-reactive protein (CRP) and alkaline phosphatase (ALP) activities in plasma. The SOFDE and MIX treatment significantly protected against alcohol-induced inflammation. More importantly, we showed in the present work that the mixture exerted a more important effect than SOFDE and SULF each alone indicating a possible synergism between these two molecules. In conclusion, our data suggests that SOFDE and SULF exerted a potential synergistic protective effect against all the macroscopic, histological and biochemical disturbances induced by EtOH intoxication. This protection might be related in part to its antioxidant and anti-inflammatory properties as well as by negatively regulating Fenton reaction components such as H2O2 and free iron.
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Affiliation(s)
- Saber Jedidi
- Unité de Physiologie Fonctionnelle et Valorisation des Bio-Ressources, Université de Jendouba, Institut Superieur de Biotechnologie de Beja Avenue Habib Bourguiba, B.P. 382 9000 Beja Tunisia +216 78 459 098 +216 97 249 486.,Laboratoire des Ressources Sylvo-Pastorales, Université de Jendouba, Institut Sylvo-Pastoral de Tabarka B.P. 345 8110 Tabarka Tunisia.,Universite de Carthage, Faculté des Sciences de Bizerte 7021 Jarzouna Tunisia
| | - Foued Aloui
- Laboratoire des Ressources Sylvo-Pastorales, Université de Jendouba, Institut Sylvo-Pastoral de Tabarka B.P. 345 8110 Tabarka Tunisia
| | - Kais Rtibi
- Unité de Physiologie Fonctionnelle et Valorisation des Bio-Ressources, Université de Jendouba, Institut Superieur de Biotechnologie de Beja Avenue Habib Bourguiba, B.P. 382 9000 Beja Tunisia +216 78 459 098 +216 97 249 486
| | - Houcem Sammari
- Laboratoire des Ressources Sylvo-Pastorales, Université de Jendouba, Institut Sylvo-Pastoral de Tabarka B.P. 345 8110 Tabarka Tunisia
| | - Houcine Selmi
- Laboratoire des Ressources Sylvo-Pastorales, Université de Jendouba, Institut Sylvo-Pastoral de Tabarka B.P. 345 8110 Tabarka Tunisia
| | - Ahmed Rejeb
- Laboratoire d'Anatomie Pathologique, Université de Manouba, Ecole Nationale de Médecine Vétérinaire de Sidi Thabet 2020 Sidi Thabet Tunisia
| | - Lamjed Toumi
- Laboratoire des Ressources Sylvo-Pastorales, Université de Jendouba, Institut Sylvo-Pastoral de Tabarka B.P. 345 8110 Tabarka Tunisia
| | - Hichem Sebai
- Unité de Physiologie Fonctionnelle et Valorisation des Bio-Ressources, Université de Jendouba, Institut Superieur de Biotechnologie de Beja Avenue Habib Bourguiba, B.P. 382 9000 Beja Tunisia +216 78 459 098 +216 97 249 486
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8
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Leach K, Hannan FM, Josephs TM, Keller AN, Møller TC, Ward DT, Kallay E, Mason RS, Thakker RV, Riccardi D, Conigrave AD, Bräuner-Osborne H. International Union of Basic and Clinical Pharmacology. CVIII. Calcium-Sensing Receptor Nomenclature, Pharmacology, and Function. Pharmacol Rev 2020; 72:558-604. [PMID: 32467152 PMCID: PMC7116503 DOI: 10.1124/pr.119.018531] [Citation(s) in RCA: 50] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The calcium-sensing receptor (CaSR) is a class C G protein-coupled receptor that responds to multiple endogenous agonists and allosteric modulators, including divalent and trivalent cations, L-amino acids, γ-glutamyl peptides, polyamines, polycationic peptides, and protons. The CaSR plays a critical role in extracellular calcium (Ca2+ o) homeostasis, as demonstrated by the many naturally occurring mutations in the CaSR or its signaling partners that cause Ca2+ o homeostasis disorders. However, CaSR tissue expression in mammals is broad and includes tissues unrelated to Ca2+ o homeostasis, in which it, for example, regulates the secretion of digestive hormones, airway constriction, cardiovascular effects, cellular differentiation, and proliferation. Thus, although the CaSR is targeted clinically by the positive allosteric modulators (PAMs) cinacalcet, evocalcet, and etelcalcetide in hyperparathyroidism, it is also a putative therapeutic target in diabetes, asthma, cardiovascular disease, and cancer. The CaSR is somewhat unique in possessing multiple ligand binding sites, including at least five putative sites for the "orthosteric" agonist Ca2+ o, an allosteric site for endogenous L-amino acids, two further allosteric sites for small molecules and the peptide PAM, etelcalcetide, and additional sites for other cations and anions. The CaSR is promiscuous in its G protein-coupling preferences, and signals via Gq/11, Gi/o, potentially G12/13, and even Gs in some cell types. Not surprisingly, the CaSR is subject to biased agonism, in which distinct ligands preferentially stimulate a subset of the CaSR's possible signaling responses, to the exclusion of others. The CaSR thus serves as a model receptor to study natural bias and allostery. SIGNIFICANCE STATEMENT: The calcium-sensing receptor (CaSR) is a complex G protein-coupled receptor that possesses multiple orthosteric and allosteric binding sites, is subject to biased signaling via several different G proteins, and has numerous (patho)physiological roles. Understanding the complexities of CaSR structure, function, and biology will aid future drug discovery efforts seeking to target this receptor for a diversity of diseases. This review summarizes what is known to date regarding key structural, pharmacological, and physiological features of the CaSR.
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Affiliation(s)
- Katie Leach
- Drug Discovery Biology, Monash Institute of Pharmaceutical Science, Monash University, Parkville, Australia (K.L., T.M.J., A.N.K.); Nuffield Department of Women's & Reproductive Health (F.M.H.) and Academic Endocrine Unit, Radcliffe Department of Clinical Medicine (F.M.H., R.V.T.), University of Oxford, Oxford, United Kingdom; Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark (T.C.M., H.B.-O.); Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, United Kingdom (D.T.W.); Department of Pathophysiology and Allergy Research, Medical University of Vienna, Vienna, Austria (E.K.); Physiology, School of Medical Sciences and Bosch Institute (R.S.M.) and School of Life & Environmental Sciences, Charles Perkins Centre (A.D.C.), University of Sydney, Sydney, Australia; and School of Biosciences, Cardiff University, Cardiff, United Kingdom (D.R.)
| | - Fadil M Hannan
- Drug Discovery Biology, Monash Institute of Pharmaceutical Science, Monash University, Parkville, Australia (K.L., T.M.J., A.N.K.); Nuffield Department of Women's & Reproductive Health (F.M.H.) and Academic Endocrine Unit, Radcliffe Department of Clinical Medicine (F.M.H., R.V.T.), University of Oxford, Oxford, United Kingdom; Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark (T.C.M., H.B.-O.); Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, United Kingdom (D.T.W.); Department of Pathophysiology and Allergy Research, Medical University of Vienna, Vienna, Austria (E.K.); Physiology, School of Medical Sciences and Bosch Institute (R.S.M.) and School of Life & Environmental Sciences, Charles Perkins Centre (A.D.C.), University of Sydney, Sydney, Australia; and School of Biosciences, Cardiff University, Cardiff, United Kingdom (D.R.)
| | - Tracy M Josephs
- Drug Discovery Biology, Monash Institute of Pharmaceutical Science, Monash University, Parkville, Australia (K.L., T.M.J., A.N.K.); Nuffield Department of Women's & Reproductive Health (F.M.H.) and Academic Endocrine Unit, Radcliffe Department of Clinical Medicine (F.M.H., R.V.T.), University of Oxford, Oxford, United Kingdom; Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark (T.C.M., H.B.-O.); Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, United Kingdom (D.T.W.); Department of Pathophysiology and Allergy Research, Medical University of Vienna, Vienna, Austria (E.K.); Physiology, School of Medical Sciences and Bosch Institute (R.S.M.) and School of Life & Environmental Sciences, Charles Perkins Centre (A.D.C.), University of Sydney, Sydney, Australia; and School of Biosciences, Cardiff University, Cardiff, United Kingdom (D.R.)
| | - Andrew N Keller
- Drug Discovery Biology, Monash Institute of Pharmaceutical Science, Monash University, Parkville, Australia (K.L., T.M.J., A.N.K.); Nuffield Department of Women's & Reproductive Health (F.M.H.) and Academic Endocrine Unit, Radcliffe Department of Clinical Medicine (F.M.H., R.V.T.), University of Oxford, Oxford, United Kingdom; Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark (T.C.M., H.B.-O.); Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, United Kingdom (D.T.W.); Department of Pathophysiology and Allergy Research, Medical University of Vienna, Vienna, Austria (E.K.); Physiology, School of Medical Sciences and Bosch Institute (R.S.M.) and School of Life & Environmental Sciences, Charles Perkins Centre (A.D.C.), University of Sydney, Sydney, Australia; and School of Biosciences, Cardiff University, Cardiff, United Kingdom (D.R.)
| | - Thor C Møller
- Drug Discovery Biology, Monash Institute of Pharmaceutical Science, Monash University, Parkville, Australia (K.L., T.M.J., A.N.K.); Nuffield Department of Women's & Reproductive Health (F.M.H.) and Academic Endocrine Unit, Radcliffe Department of Clinical Medicine (F.M.H., R.V.T.), University of Oxford, Oxford, United Kingdom; Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark (T.C.M., H.B.-O.); Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, United Kingdom (D.T.W.); Department of Pathophysiology and Allergy Research, Medical University of Vienna, Vienna, Austria (E.K.); Physiology, School of Medical Sciences and Bosch Institute (R.S.M.) and School of Life & Environmental Sciences, Charles Perkins Centre (A.D.C.), University of Sydney, Sydney, Australia; and School of Biosciences, Cardiff University, Cardiff, United Kingdom (D.R.)
| | - Donald T Ward
- Drug Discovery Biology, Monash Institute of Pharmaceutical Science, Monash University, Parkville, Australia (K.L., T.M.J., A.N.K.); Nuffield Department of Women's & Reproductive Health (F.M.H.) and Academic Endocrine Unit, Radcliffe Department of Clinical Medicine (F.M.H., R.V.T.), University of Oxford, Oxford, United Kingdom; Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark (T.C.M., H.B.-O.); Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, United Kingdom (D.T.W.); Department of Pathophysiology and Allergy Research, Medical University of Vienna, Vienna, Austria (E.K.); Physiology, School of Medical Sciences and Bosch Institute (R.S.M.) and School of Life & Environmental Sciences, Charles Perkins Centre (A.D.C.), University of Sydney, Sydney, Australia; and School of Biosciences, Cardiff University, Cardiff, United Kingdom (D.R.)
| | - Enikö Kallay
- Drug Discovery Biology, Monash Institute of Pharmaceutical Science, Monash University, Parkville, Australia (K.L., T.M.J., A.N.K.); Nuffield Department of Women's & Reproductive Health (F.M.H.) and Academic Endocrine Unit, Radcliffe Department of Clinical Medicine (F.M.H., R.V.T.), University of Oxford, Oxford, United Kingdom; Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark (T.C.M., H.B.-O.); Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, United Kingdom (D.T.W.); Department of Pathophysiology and Allergy Research, Medical University of Vienna, Vienna, Austria (E.K.); Physiology, School of Medical Sciences and Bosch Institute (R.S.M.) and School of Life & Environmental Sciences, Charles Perkins Centre (A.D.C.), University of Sydney, Sydney, Australia; and School of Biosciences, Cardiff University, Cardiff, United Kingdom (D.R.)
| | - Rebecca S Mason
- Drug Discovery Biology, Monash Institute of Pharmaceutical Science, Monash University, Parkville, Australia (K.L., T.M.J., A.N.K.); Nuffield Department of Women's & Reproductive Health (F.M.H.) and Academic Endocrine Unit, Radcliffe Department of Clinical Medicine (F.M.H., R.V.T.), University of Oxford, Oxford, United Kingdom; Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark (T.C.M., H.B.-O.); Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, United Kingdom (D.T.W.); Department of Pathophysiology and Allergy Research, Medical University of Vienna, Vienna, Austria (E.K.); Physiology, School of Medical Sciences and Bosch Institute (R.S.M.) and School of Life & Environmental Sciences, Charles Perkins Centre (A.D.C.), University of Sydney, Sydney, Australia; and School of Biosciences, Cardiff University, Cardiff, United Kingdom (D.R.)
| | - Rajesh V Thakker
- Drug Discovery Biology, Monash Institute of Pharmaceutical Science, Monash University, Parkville, Australia (K.L., T.M.J., A.N.K.); Nuffield Department of Women's & Reproductive Health (F.M.H.) and Academic Endocrine Unit, Radcliffe Department of Clinical Medicine (F.M.H., R.V.T.), University of Oxford, Oxford, United Kingdom; Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark (T.C.M., H.B.-O.); Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, United Kingdom (D.T.W.); Department of Pathophysiology and Allergy Research, Medical University of Vienna, Vienna, Austria (E.K.); Physiology, School of Medical Sciences and Bosch Institute (R.S.M.) and School of Life & Environmental Sciences, Charles Perkins Centre (A.D.C.), University of Sydney, Sydney, Australia; and School of Biosciences, Cardiff University, Cardiff, United Kingdom (D.R.)
| | - Daniela Riccardi
- Drug Discovery Biology, Monash Institute of Pharmaceutical Science, Monash University, Parkville, Australia (K.L., T.M.J., A.N.K.); Nuffield Department of Women's & Reproductive Health (F.M.H.) and Academic Endocrine Unit, Radcliffe Department of Clinical Medicine (F.M.H., R.V.T.), University of Oxford, Oxford, United Kingdom; Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark (T.C.M., H.B.-O.); Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, United Kingdom (D.T.W.); Department of Pathophysiology and Allergy Research, Medical University of Vienna, Vienna, Austria (E.K.); Physiology, School of Medical Sciences and Bosch Institute (R.S.M.) and School of Life & Environmental Sciences, Charles Perkins Centre (A.D.C.), University of Sydney, Sydney, Australia; and School of Biosciences, Cardiff University, Cardiff, United Kingdom (D.R.)
| | - Arthur D Conigrave
- Drug Discovery Biology, Monash Institute of Pharmaceutical Science, Monash University, Parkville, Australia (K.L., T.M.J., A.N.K.); Nuffield Department of Women's & Reproductive Health (F.M.H.) and Academic Endocrine Unit, Radcliffe Department of Clinical Medicine (F.M.H., R.V.T.), University of Oxford, Oxford, United Kingdom; Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark (T.C.M., H.B.-O.); Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, United Kingdom (D.T.W.); Department of Pathophysiology and Allergy Research, Medical University of Vienna, Vienna, Austria (E.K.); Physiology, School of Medical Sciences and Bosch Institute (R.S.M.) and School of Life & Environmental Sciences, Charles Perkins Centre (A.D.C.), University of Sydney, Sydney, Australia; and School of Biosciences, Cardiff University, Cardiff, United Kingdom (D.R.)
| | - Hans Bräuner-Osborne
- Drug Discovery Biology, Monash Institute of Pharmaceutical Science, Monash University, Parkville, Australia (K.L., T.M.J., A.N.K.); Nuffield Department of Women's & Reproductive Health (F.M.H.) and Academic Endocrine Unit, Radcliffe Department of Clinical Medicine (F.M.H., R.V.T.), University of Oxford, Oxford, United Kingdom; Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark (T.C.M., H.B.-O.); Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, United Kingdom (D.T.W.); Department of Pathophysiology and Allergy Research, Medical University of Vienna, Vienna, Austria (E.K.); Physiology, School of Medical Sciences and Bosch Institute (R.S.M.) and School of Life & Environmental Sciences, Charles Perkins Centre (A.D.C.), University of Sydney, Sydney, Australia; and School of Biosciences, Cardiff University, Cardiff, United Kingdom (D.R.)
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9
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Hannan FM, Kallay E, Chang W, Brandi ML, Thakker RV. The calcium-sensing receptor in physiology and in calcitropic and noncalcitropic diseases. Nat Rev Endocrinol 2018; 15:33-51. [PMID: 30443043 PMCID: PMC6535143 DOI: 10.1038/s41574-018-0115-0] [Citation(s) in RCA: 191] [Impact Index Per Article: 31.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The Ca2+-sensing receptor (CaSR) is a dimeric family C G protein-coupled receptor that is expressed in calcitropic tissues such as the parathyroid glands and the kidneys and signals via G proteins and β-arrestin. The CaSR has a pivotal role in bone and mineral metabolism, as it regulates parathyroid hormone secretion, urinary Ca2+ excretion, skeletal development and lactation. The importance of the CaSR for these calcitropic processes is highlighted by loss-of-function and gain-of-function CaSR mutations that cause familial hypocalciuric hypercalcaemia and autosomal dominant hypocalcaemia, respectively, and also by the fact that alterations in parathyroid CaSR expression contribute to the pathogenesis of primary and secondary hyperparathyroidism. Moreover, the CaSR is an established therapeutic target for hyperparathyroid disorders. The CaSR is also expressed in organs not involved in Ca2+ homeostasis: it has noncalcitropic roles in lung and neuronal development, vascular tone, gastrointestinal nutrient sensing, wound healing and secretion of insulin and enteroendocrine hormones. Furthermore, the abnormal expression or function of the CaSR is implicated in cardiovascular and neurological diseases, as well as in asthma, and the CaSR is reported to protect against colorectal cancer and neuroblastoma but increase the malignant potential of prostate and breast cancers.
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Affiliation(s)
- Fadil M Hannan
- Department of Musculoskeletal Biology, Institute of Ageing and Chronic Disease, University of Liverpool, Liverpool, UK
- Academic Endocrine Unit, Radcliffe Department of Medicine, University of Oxford, Oxford, UK
| | - Enikö Kallay
- Department of Pathophysiology and Allergy Research, Medical University of Vienna, Vienna, Austria
| | - Wenhan Chang
- Endocrine Research Unit, Veterans Affairs Medical Center, University of California, San Francisco, San Francisco, CA, USA
| | - Maria Luisa Brandi
- Metabolic Bone Diseases Unit, Department of Surgery and Translational Medicine, University of Florence, Florence, Italy.
| | - Rajesh V Thakker
- Academic Endocrine Unit, Radcliffe Department of Medicine, University of Oxford, Oxford, UK.
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10
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Li XN, Rao T, Xu YF, Hu KR, Zhu ZP, Li HF, Kang D, Shao YH, Shen BY, Yin XX, Xie L, Wang GJ, Liang Y. Pharmacokinetic and pharmacodynamic evidence for developing an oral formulation of octreotide against gastric mucosal injury. Acta Pharmacol Sin 2018; 39:1373-1385. [PMID: 29188801 DOI: 10.1038/aps.2017.159] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2017] [Accepted: 10/18/2017] [Indexed: 12/30/2022] Open
Abstract
Among the somatostatin analogues, octreotide (OCT) is the most commonly used in clinic via intravenous or subcutaneous injection to treat various diseases caused by increased secretion of growth hormone, gastrin or insulin. In order to assesse the feasibility of developing oral formulations of OCT, we conducted systematical pharmacokinetic and pharmacodynamic analyses of OCT in several animal models. The pharmacokinetic studies in rats showed that intragastric administration of OCT had extremely low bioavailability (<0.5%), but it could specifically distribute to the gastric mucosa due to the high expression of somatostatin receptor 2 (SSTR2) in the rat stomach. The pharmacodynamic studies revealed that intragastric administration of OCT dose-dependently protected against gastric mucosal injury (GMI) in mice with WIRS-induced mouse gastric ulcers, which were comparable to those achieved by intravenous injection of OCT, and this effect was markedly attenuated by co-administration of CYN-154806, an antagonist of SSTR2. In pyloric ligation-induced ulcer mice, we further demonstrated that OCT significantly reduced the secretion of gastric acid via down-regulating the level of gastrin, which was responsible for the protective effect of OCT against GMI. Overall, we have provided pharmacokinetic and pharmacodynamic evidence for the feasibility of developing an oral formulation of OCT. Most importantly, the influence of SSTR2 on the pharmacokinetics and pharmacodynamics of OCT suggested that an oral formulation of OCT might be applicable for other clinical indications, including neuroendocrine neoplasms and pituitary adenoma due to the overexpression of SSTR2 on these tumor cells.
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11
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Kitay AM, Schneebacher MT, Schmitt A, Heschl K, Kopic S, Alfadda T, Alsaihati A, Link A, Geibel JP. Modulations in extracellular calcium lead to H +-ATPase-dependent acid secretion: a clarification of PPI failure. Am J Physiol Gastrointest Liver Physiol 2018. [PMID: 29517927 DOI: 10.1152/ajpgi.00132.2017] [Citation(s) in RCA: 5] [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
The H+,K+-ATPase was identified as the primary proton secretory pathway in the gastric parietal cell and is the pharmacological target of agents suppressing acid secretion. Recently, we identified a second acid secretory protein expressed in the parietal cell, the vacuolar H+-ATPase (V-type ATPase). The aim of the present study was to further characterize H+-ATPase activation by modulations in extracellular calcium via the calcium sensing receptor (CaSR). Isolated gastric glands were loaded with the pH indicator dye BCECF-AM [2',7'-bis-(2-carboxyethyl)-5-(and-6)-carboxyfluorescein acetoxymethyl ester] to measure intracellular pH. Experiments were conducted in the absence of sodium and potassium to monitor H+-ATPase-specific transport activity. CaSR was activated with the calcimimetic R568 (400 nM) and/or by modulations in extracellular Ca2+. Elevation in calcium concentrations increased proton extrusion from the gastric parietal cell. Allosteric modification of the CaSR via R568 and calcium increased vacuolar H+-ATPase activity significantly (ΔpH/minlowCa2+(0.1mM) = 0.001 ± 0.001, ΔpH/minnormalCa2+(1.0mM) = 0.033 ± 0.004, ΔpH/minhighCa2+(5.0mM) = 0.051 ± 0.005). Carbachol significantly suppressed calcium-induced gastric acid secretion via the H+-ATPase under sodium- and potassium-free conditions. We conclude that the V-type H+-ATPase is tightly linked to CaSR activation. We observed that proton pump inhibitor (PPI) exposure does not modulate H+-ATPase activity. This elevated blood calcium activation of the H+-ATPase could provide an explanation for recurrent reflux symptoms while taking a PPI therapy. NEW & NOTEWORTHY This study emphasizes the role of the H+-ATPase in acid secretion. We further demonstrate the modification of this proton excretion pathway by extracellular calcium and the activation of the calcium sensing receptor CaSR. The novelty of this paper is based on the modulation of the H+-ATPase via both extracellular Ca (activation) and the classical secretagogues histamine and carbachol (inactivation). Both activation and inactivation of this proton pump are independent of PPI modulation.
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Affiliation(s)
- Alice Miriam Kitay
- Department of Surgery, Yale University School of Medicine , New Haven, Connecticut.,Department of Gastroenterology, Hepatology and Infectious Diseases, Otto-von-Guericke University, Magdeburg, Gemany
| | | | - Anne Schmitt
- Department of Surgery, Yale University School of Medicine , New Haven, Connecticut
| | - Katharina Heschl
- Department of Surgery, Yale University School of Medicine , New Haven, Connecticut
| | - Sascha Kopic
- Department of Surgery, Yale University School of Medicine , New Haven, Connecticut.,Department of Cellular and Molecular Physiology, Yale University School of Medicine , New Haven, Connecticut
| | - Tariq Alfadda
- Department of Surgery, Yale University School of Medicine , New Haven, Connecticut
| | - Abrar Alsaihati
- Department of Surgery, Yale University School of Medicine , New Haven, Connecticut
| | - Alexander Link
- Department of Gastroenterology, Hepatology and Infectious Diseases, Otto-von-Guericke University, Magdeburg, Gemany
| | - John Peter Geibel
- Department of Surgery, Yale University School of Medicine , New Haven, Connecticut.,Department of Cellular and Molecular Physiology, Yale University School of Medicine , New Haven, Connecticut
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12
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Kuczera P, Adamczak M, Machnik G, Okopien B, Wiecek A. Treatment Based on Cinacalcet Reduces Oxidative Stress in Hemodialysis Patients with Secondary Hyperparathyroidism. Nephron Clin Pract 2018; 139:286-292. [PMID: 29879701 DOI: 10.1159/000489278] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2018] [Accepted: 04/13/2018] [Indexed: 01/08/2023] Open
Abstract
BACKGROUND/AIMS Oxidative stress is one of the leading factors contributing to increased mortality in patients with chronic kidney disease (CKD) and secondary hyperparathyroidism (sHPT). Cinacalcet is now commonly used in the treatment of sHPT in patients with CKD. The aim of this study was to assess the influence of treatment with cinacalcet on the oxidative stress markers in patients on hemodialysis with sHPT. METHODS In 58 hemodialysed patients with sHPT (parathyroid hormone [PTH] > 300 pg/mL) plasma Advanced Oxidation Protein Products (AOPP), serum total antioxidant capacity - ImAnOx (TAS/TAC), serum PTH, calcium and phosphate concentrations were assessed before the first dose of cinacalcet and after 6 months of treatment. RESULTS Serum PTH concentration decreased significantly from 895 (748-1,070) to 384 (289-510) pg/mL after 6 months of treatment; p < 0.0001. Mean serum concentrations of -calcium and phosphate remained stable. Plasma AOPP concentration decreased significantly from 152 (126-185) to 49 -(43-57) µmol/L after 6 months of treatment; p < 0.0001. ImAnOx significantly increased from 260 (251-270) to 272 (264-280) µmol/L; p = 0.04. After 6 months of treatment, a significant, positive correlation was found between ImAnOx and the daily dose of cinacalcet (r = 0.30; p = 0.02). Also, the change of serum ImAnOx during treatment with cinacalcet significantly correlated with the daily dose of cinacalcet r = 0.35; p = 0.01. No significant correlations were found between plasma AOPP concentration or ImAnOx and PTH, or their changes in time. CONCLUSIONS (1) Six-month treatment based on cinacalcet seems to reduce oxidative stress markers in maintenance hemodialysis patients with sHPT. (2) This benefit may be related rather to the direct action of cinacalcet than to the serum PTH concentration decrease.
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Affiliation(s)
- Piotr Kuczera
- Department of Nephrology, Transplantation and Internal Medicine, Katowice, Poland
| | - Marcin Adamczak
- Department of Nephrology, Transplantation and Internal Medicine, Katowice, Poland
| | - Grzegorz Machnik
- Department of Internal Medicine and Clinical Pharmacology, Medical University of Silesia, Katowice, Poland
| | - Boguslaw Okopien
- Department of Internal Medicine and Clinical Pharmacology, Medical University of Silesia, Katowice, Poland
| | - Andrzej Wiecek
- Department of Nephrology, Transplantation and Internal Medicine, Katowice, Poland
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13
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Otsuka K, Ohno Y, Oshima J. Gallstones were associated with the gastrointestinal adverse events of cinacalcet in hemodialysis patients with secondary hyperparathyroidism. Ren Fail 2018; 40:38-42. [PMID: 29301445 PMCID: PMC6014369 DOI: 10.1080/0886022x.2017.1419971] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
This study aimed to investigate the association of gastrointestinal (GI) adverse events of cinacalcet with gallstones in the hemodialysis (HD) patients with secondary hyperparathyroidism (SHPT). A total of 23 HD patients under the treatment with cinacalcet and 101 control patients were enrolled in this cross-sectional study. We investigated the prevalence of gallstones and the association of GI adverse events of cinacalcet with gallstones. The prevalence of gallstones was significantly higher in the HD patients with cinacalcet compared with the controls (47.8% vs. 15.8%). The longer time on HD, hypercalcemia, hyperphosphatemia and elevated parathyroid hormone level were observed in the HD patients with cinacalcet. Besides, GI adverse events of cinacalcet were observed more frequently in the HD patients with gallstones compared with those without gallstones (odds ratio 13.5, 95% CI: 1.80–101). Therefore, screening for gallstones before dosing cinacalcet may reduce the risk of GI adverse events in SHPT patients.
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Affiliation(s)
- Keiichi Otsuka
- a Department of Internal Medicine, Oshima Clinic , Saitama , Japan
| | - Yoichi Ohno
- b Department of Nephrology , Saitama Medical School , Saitama , Japan
| | - Joji Oshima
- a Department of Internal Medicine, Oshima Clinic , Saitama , Japan
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14
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Massy ZA, Hénaut L, Larsson TE, Vervloet MG. Calcium-sensing receptor activation in chronic kidney disease: effects beyond parathyroid hormone control. Semin Nephrol 2015; 34:648-59. [PMID: 25498383 DOI: 10.1016/j.semnephrol.2014.10.001] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Secondary hyperparathyroidism (SHPT) is an important complication of advanced chronic kidney disease (CKD). Cinacalcet, an allosteric modulator of the calcium-sensing receptor (CaSR) expressed in parathyroid glands, is the only calcimimetic approved to treat SHPT in patients on dialysis. By enhancing CaSR sensitivity for plasma extracellular calcium (Ca(2+)0), cinacalcet reduces serum parathyroid hormone, Ca(2+)0, and serum inorganic phosphorous concentrations, allowing better control of SHPT and CKD-mineral and bone disorders. Of interest, the CaSR also is expressed in a variety of tissues where its activation regulates diverse cellular processes, including secretion, apoptosis, and proliferation. Thus, the existence of potential off-target effects of cinacalcet cannot be neglected. This review summarizes our current knowledge concerning the potential role(s) of the CaSR expressed in various tissues in CKD-related disorders, independently of parathyroid hormone control.
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Affiliation(s)
- Ziad A Massy
- Inserm U-1088, University of Picardie Jules Verne, Amiens, France; Division of Nephrology, Ambroise Paré Hospital, Paris-Ile-de-France-Ouest University (University of Versailles Saint-Quentin-En-Yvelines), Paris-Boulogne Billancourt, France.
| | - Lucie Hénaut
- Inserm U-1088, University of Picardie Jules Verne, Amiens, France
| | - Tobias E Larsson
- Department of Clinical Science, Intervention and Technology, Renal Unit, Karolinska Institutet, Stockholm, Sweden; Department of Nephrology, Karolinska University Hospital, Stockholm, Sweden
| | - Marc G Vervloet
- Department of Nephrology and Institute of Cardiovascular Research VU (Institute for Cardiovascular Research of the Vrije Universiteit of Amsterdam), VU University Medical Center, Amsterdam, The Netherlands
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15
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Mace OJ, Tehan B, Marshall F. Pharmacology and physiology of gastrointestinal enteroendocrine cells. Pharmacol Res Perspect 2015. [PMID: 26213627 PMCID: PMC4506687 DOI: 10.1002/prp2.155] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Gastrointestinal (GI) polypeptides are secreted from enteroendocrine cells (EECs). Recent technical advances and the identification of endogenous and synthetic ligands have enabled exploration of the pharmacology and physiology of EECs. Enteroendocrine signaling pathways stimulating hormone secretion involve multiple nutrient transporters and G protein-coupled receptors (GPCRs), which are activated simultaneously under prevailing nutrient conditions in the intestine following a meal. The majority of studies investigate hormone secretion from EECs in response to single ligands and although the mechanisms behind how individual signaling pathways generate a hormonal output have been well characterized, our understanding of how these signaling pathways converge to generate a single hormone secretory response is still in its infancy. However, a picture is beginning to emerge of how nutrients and full, partial, or allosteric GPCR ligands differentially regulate the enteroendocrine system and its interaction with the enteric and central nervous system. So far, activation of multiple pathways underlies drug discovery efforts to harness the therapeutic potential of the enteroendocrine system to mimic the phenotypic changes observed in patients who have undergone Roux-en-Y gastric surgery. Typically obese patients exhibit ∼30% weight loss and greater than 80% of obese diabetics show remission of diabetes. Targeting combinations of enteroendocrine signaling pathways that work synergistically may manifest with significant, differentiated EEC secretory efficacy. Furthermore, allosteric modulators with their increased selectivity, self-limiting activity, and structural novelty may translate into more promising enteroendocrine drugs. Together with the potential to bias enteroendocrine GPCR signaling and/or to activate multiple divergent signaling pathways highlights the considerable range of therapeutic possibilities available. Here, we review the pharmacology and physiology of the EEC system.
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Affiliation(s)
- O J Mace
- Heptares Therapeutics Ltd BioPark, Broadwater Road, Welwyn Garden City, AL7 3AX, United Kingdom
| | - B Tehan
- Heptares Therapeutics Ltd BioPark, Broadwater Road, Welwyn Garden City, AL7 3AX, United Kingdom
| | - F Marshall
- Heptares Therapeutics Ltd BioPark, Broadwater Road, Welwyn Garden City, AL7 3AX, United Kingdom
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16
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Alfadda TI, Saleh AMA, Houillier P, Geibel JP. Calcium-sensing receptor 20 years later. Am J Physiol Cell Physiol 2014; 307:C221-31. [PMID: 24871857 PMCID: PMC4121584 DOI: 10.1152/ajpcell.00139.2014] [Citation(s) in RCA: 72] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2014] [Accepted: 05/23/2014] [Indexed: 12/19/2022]
Abstract
The calcium-sensing receptor (CaSR) has played an important role as a target in the treatment of a variety of disease states over the past 20 plus years. In this review, we give an overview of the receptor at the cellular level and then provide details as to how this receptor has been targeted to modulate cellular ion transport mechanisms. As a member of the G protein-coupled receptor (GPCR) family, it has a high degree of homology with a variety of other members in this class, which could explain why this receptor has been identified in so many different tissues throughout the body. This diversity of locations sets it apart from other members of the family and may explain how the receptor interacts with so many different organ systems in the body to modulate the physiology and pathophysiology. The receptor is unique in that it has two large exofacial lobes that sit in the extracellular environment and sense changes in a wide variety of environmental cues including salinity, pH, amino acid concentration, and polyamines to name just a few. It is for this reason that there has been a great deal of research associated with normal receptor physiology over the past 20 years. With the ongoing research, in more recent years a focus on the pathophysiology has emerged and the effects of receptor mutations on cellular and organ physiology have been identified. We hope that this review will enhance and update the knowledge about the importance of this receptor and stimulate future potential investigations focused around this receptor in cellular, organ, and systemic physiology and pathophysiology.
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Affiliation(s)
- Tariq I Alfadda
- Department of Surgery, Yale School of Medicine, New Haven, Connecticut
| | - Ahmad M A Saleh
- Department of Surgery, Yale School of Medicine, New Haven, Connecticut
| | - Pascal Houillier
- INSERM UMR_S1138, Paris, France; Paris Descartes University, Paris, France; Assistance Publique-Hopitaux de Paris, Hopital Europeen Georges Pompidou, Paris, France
| | - John P Geibel
- Department of Surgery, Yale School of Medicine, New Haven, Connecticut; Department of Cellular and Molecular Physiology, Yale School of Medicine, New Haven, Connecticut; and
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17
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Ubl P, Gincu T, Keilani M, Ponhold L, Crevenna R, Niederle B, Hacker M, Li S. Comparison of side effects of pentagastrin test and calcium stimulation test in patients with increased basal calcitonin concentration: the gender-specific differences. Endocrine 2014; 46:549-53. [PMID: 24272596 DOI: 10.1007/s12020-013-0109-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/26/2013] [Accepted: 10/29/2013] [Indexed: 11/28/2022]
Abstract
The aim of this study was to compare the side effects of the pentagastrin test and the calcium stimulation test in patients with increased basal calcitonin concentration, especially the gender-specific differences of side effects. A total of 256 patients (123 females and 133 males, mean age of 56 ± 27 years, range 21-83 years) had both pentagastrin and calcium stimulation tests. All patients filled in a questionnaire regarding the side effects within 30 min after completion of the stimulation tests. The differences of side effects between female and male patients as well as between the pentagastrin stimulation test and the calcium stimulation test were evaluated. Warmth feeling was the most frequent occurring side effect in all patients who had both pentagastrin and calcium stimulation tests, followed by nausea, altered gustatory sensation, and dizziness. The incidences of urgency to micturate (p < 0.05) and dizziness (p < 0.05) were significantly increased in the female patients as compared to male patients by calcium stimulation test. Significant higher incidences of urgency to micturate (p < 0.05) and warmth feeling (p < 0.05) were found by calcium stimulation test as compared with those by pentagastrin test in female patients. The incidences of nausea (p < 0.05) and abdominal cramping (p < 0.05) in male patients were significantly higher by pentagastrin stimulation test than by calcium stimulation test. There is a significant gender-specific difference in side effects induced by calcium stimulation test. Female patients have fewer side effects by pentagastrin test than by calcium stimulation test. Male patients may tolerate the calcium stimulation test better than the pentagastrin test.
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Affiliation(s)
- Philipp Ubl
- Division of Nuclear Medicine, Department of Biomedical Imaging and Image-guided Therapy, Medical University of Vienna, Vienna, Austria
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18
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XIE RUI, TANG BO, YONG XIN, LUO GANG, YANG SHIMING. Roles of the calcium sensing receptor in digestive physiology and pathophysiology (Review). Int J Oncol 2014; 45:1355-62. [DOI: 10.3892/ijo.2014.2560] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2014] [Accepted: 04/30/2014] [Indexed: 11/06/2022] Open
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Muramatsu M, Hira T, Mitsunaga A, Sato E, Nakajima S, Kitahara Y, Eto Y, Hara H. Activation of the gut calcium-sensing receptor by peptide agonists reduces rapid elevation of plasma glucose in response to oral glucose load in rats. Am J Physiol Gastrointest Liver Physiol 2014; 306:G1099-107. [PMID: 24812056 DOI: 10.1152/ajpgi.00155.2014] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The calcium-sensing receptor (CaSR) is expressed in various tissues, including the gastrointestinal tract. To investigate the role of gut CaSR on glycemic control, we examined whether single oral administration of CaSR agonist peptides affected the glycemic response in rats. Glucose tolerance tests were performed under oral or duodenal administration of various CaSR agonist peptides (γGlu-Cys, protamine, and poly-d-lysine hydrobromide) in conscious rats. Involvement of CaSR was determined by using a CaSR antagonist. Signaling pathways underlying CaSR agonist-modified glycemia were investigated using gut hormone receptor antagonists. The gastric emptying rate after the administration of CaSR agonist peptides was measured by the phenol red recovery method. Oral and duodenal administration of CaSR agonist peptides attenuated glycemic responses under the oral glucose tolerance test, but the administration of casein did not. The promotive effect on glucose tolerance was weakened by luminal pretreatment with a CaSR antagonist. Treatment with a 5-HT3 receptor antagonist partially diminished the glucose-lowering effect of peptides. Furthermore, the gastric emptying rate was decreased by duodenal administration of CaSR agonist peptides. These results demonstrate that activation of the gut CaSR by peptide agonists promotes glucose tolerance in conscious rats. 5-HT3 receptor and the delayed gastric emptying rate appear to be involved in the glucose-lowering effect of CaSR agonist peptides. Thus, activation of gut CaSR by dietary peptides reduces glycemic responses so that gut CaSR may be a potential target for the improvement of postprandial glycemia.
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Affiliation(s)
- Maya Muramatsu
- Graduate School of Agriculture, Hokkaido University, Sapporo, Japan
| | - Tohru Hira
- Research Faculty of Agriculture, Hokkaido University, Sapporo, Japan;
| | - Arimi Mitsunaga
- Faculty of Agriculture, Hokkaido University, Sapporo, Japan; and
| | - Eri Sato
- Graduate School of Agriculture, Hokkaido University, Sapporo, Japan
| | - Shingo Nakajima
- Research Faculty of Agriculture, Hokkaido University, Sapporo, Japan
| | - Yoshiro Kitahara
- Faculty of Agriculture, Hokkaido University, Sapporo, Japan; and
| | - Yuzuru Eto
- Faculty of Agriculture, Hokkaido University, Sapporo, Japan; and
| | - Hiroshi Hara
- Research Faculty of Agriculture, Hokkaido University, Sapporo, Japan
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20
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Liou AP. DIGESTIVE PHYSIOLOGY OF THE PIG SYMPOSIUM: G protein-coupled receptors in nutrient chemosensation and gastrointestinal hormone secretion1. J Anim Sci 2013; 91:1946-56. [DOI: 10.2527/jas.2012-5910] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Affiliation(s)
- A. P. Liou
- Obesity, Metabolism & Nutrition Institute and Gastrointestinal Unit, Massachusetts General Hospital, Boston 02114
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21
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Kopic S, Geibel JP. Gastric acid, calcium absorption, and their impact on bone health. Physiol Rev 2013; 93:189-268. [PMID: 23303909 DOI: 10.1152/physrev.00015.2012] [Citation(s) in RCA: 102] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Calcium balance is essential for a multitude of physiological processes, ranging from cell signaling to maintenance of bone health. Adequate intestinal absorption of calcium is a major factor for maintaining systemic calcium homeostasis. Recent observations indicate that a reduction of gastric acidity may impair effective calcium uptake through the intestine. This article reviews the physiology of gastric acid secretion, intestinal calcium absorption, and their respective neuroendocrine regulation and explores the physiological basis of a potential link between these individual systems.
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Affiliation(s)
- Sascha Kopic
- Department of Surgery and Cellular and Molecular Physiology, Yale School of Medicine, New Haven, Connecticut, USA
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22
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Cifuentes M, Fuentes C, Tobar N, Acevedo I, Villalobos E, Hugo E, Ben-Jonathan N, Reyes M. Calcium sensing receptor activation elevates proinflammatory factor expression in human adipose cells and adipose tissue. Mol Cell Endocrinol 2012; 361:24-30. [PMID: 22449852 PMCID: PMC3761973 DOI: 10.1016/j.mce.2012.03.006] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/06/2011] [Revised: 02/15/2012] [Accepted: 03/08/2012] [Indexed: 12/28/2022]
Abstract
The proinflammatory status of adipose tissue has been linked to the metabolic and cardiovascular consequences of obesity. Human adipose cells express the calcium sensing receptor (CaSR), and its expression is elevated in inflammatory states, such as that associated with obesity. Given the CaSR's association with inflammation in other tissues, we evaluated its role elevating the adipose expression of inflammatory factors. The CaSR activation by the calcimimatic cinacalcet (5μM) in adipose tissue and in vitro cultured LS14 adipose cells elicited an elevation in the expression of the proinflammatory cytokines IL6, IL1β, TNFα, and the chemoattractant CCL2. This was in part reverted by SN50, an inhibitor of the inflammatory mediator nuclear factor kappa B (NFκB). Our observations suggest that CaSR activation elevates cytokine and chemokine production, partially mediated by NFκB. These findings support the relevance of the CaSR in the pathophysiology of obesity-induced adipose tissue dysfunction, with an interesting potential for pharmacological manipulation.
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Affiliation(s)
- Mariana Cifuentes
- Institute of Nutrition and Food Technology (INTA), Universidad de Chile, Santiago, Chile.
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23
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Mace OJ, Schindler M, Patel S. The regulation of K- and L-cell activity by GLUT2 and the calcium-sensing receptor CasR in rat small intestine. J Physiol 2012; 590:2917-36. [PMID: 22495587 DOI: 10.1113/jphysiol.2011.223800] [Citation(s) in RCA: 183] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Intestinal enteroendocrine cells (IECs) secrete gut peptides in response to both nutrients and non-nutrients. Glucose and amino acids both stimulate gut peptide secretion. Our hypothesis was that the facilitative glucose transporter, GLUT2, could act as a glucose sensor and the calcium-sensing receptor, CasR, could detect amino acids in the intestine to modify gut peptide secretion. We used isolated loops of rat small intestine to study the secretion of gluco-insulinotropic peptide (GIP), glucagon-like peptide-1 (GLP-1) and peptide tyrosine tyrosine (PYY) secretion stimulated by luminal perfusion of nutrients or bile acid. Inhibition of the sodium-dependent glucose cotransporter 1 (SGLT1) with phloridzin partially inhibited GIP, GLP-1 and PYY secretion by 45%, suggesting another glucose sensor might be involved in modulating peptide secretion. The response was completely abolished in the presence of the GLUT2 inhibitors phloretin or cytochalasin B. Given that GLUT2 modified gut peptide secretion stimulated by glucose, we investigated whether it was involved in the secretion of gut peptide by other gut peptide secretagogues. Phloretin completely abolished gut peptide secretion stimulated by artificial sweetener (sucralose), dipeptide (glycylsarcosine), lipid (oleoylethanolamine), short chain fatty acid (propionate) and major rat bile acid (taurocholate) indicating a fundamental position for GLUT2 in the gut peptide secretory mechanism. We investigated how GLUT2 was able to influence gut peptide secretion mediated by a diverse range of stimulators and discovered that GLUT2 affected membrane depolarisation through the closure of K+(ATP)-sensitive channels. In the absence of SGLT1 activity (or presence of phloridzin), the secretion of GIP, GLP-1 and PYY was sensitive to K+(ATP)-sensitive channel modulators tolbutamide and diazoxide. L-amino acids phenylalanine (Phe), tryptophan (Trp), asparagine (Asn), arginine (Arg) and glutamine (Gln) also stimulated GIP, GLP-1 and PYY secretion, which was completely abolished when extracellular Ca2+ was absent. The gut peptide response stimulated by the amino acids was also blocked by the CasR inhibitor Calhex 231 and augmented by the CasR agonist NPS-R568. GLUT2 and CasR regulate K- and L-cell activity in response to nutrient and non-nutrient stimuli.
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24
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Riccardi D, Kemp PJ. The Calcium-Sensing Receptor Beyond Extracellular Calcium Homeostasis: Conception, Development, Adult Physiology, and Disease. Annu Rev Physiol 2012; 74:271-97. [DOI: 10.1146/annurev-physiol-020911-153318] [Citation(s) in RCA: 111] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Daniela Riccardi
- Division of Pathophysiology and Repair, School of Biosciences, Cardiff University, Cardiff, CF10 3AX, United Kingdom; ,
| | - Paul J. Kemp
- Division of Pathophysiology and Repair, School of Biosciences, Cardiff University, Cardiff, CF10 3AX, United Kingdom; ,
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25
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Signaling through the extracellular calcium-sensing receptor (CaSR). ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2012; 740:103-42. [PMID: 22453940 DOI: 10.1007/978-94-007-2888-2_5] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The extracellular calcium ([Formula: see text])-sensing receptor (CaSR) was the first GPCR identified whose principal physiological ligand is an ion, namely extracellular Ca(2+). It maintains the near constancy of [Formula: see text] that complex organisms require to ensure normal cellular function. A wealth of information has accumulated over the past two decades about the CaSR's structure and function, its role in diseases and CaSR-based therapeutics. This review briefly describes the CaSR and key features of its structure and function, then discusses the extracellular signals modulating its activity, provides an overview of the intracellular signaling pathways that it controls, and, finally, briefly describes CaSR signaling both in tissues participating in [Formula: see text] homeostasis as well as those that do not. Factors controlling CaSR signaling include various factors affecting the expression of the CaSR gene as well as modulation of its trafficking to and from the cell surface. The dimeric cell surface CaSR, in turn, links to various heterotrimeric and small molecular weight G proteins to regulate intracellular second messengers, lipid kinases, various protein kinases, and transcription factors that are part of the machinery enabling the receptor to modulate the functions of the wide variety of cells in which it is expressed. CaSR signaling is impacted by its interactions with several binding partners in addition to signaling elements per se (i.e., G proteins), including filamin-A and caveolin-1. These latter two proteins act as scaffolds that bind signaling components and other key cellular elements (e.g., the cytoskeleton). Thus CaSR signaling likely does not take place randomly throughout the cell, but is compartmentalized and organized so as to facilitate the interaction of the receptor with its various signaling pathways.
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26
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Wang Y, Chandra R, Samsa LA, Gooch B, Fee BE, Cook JM, Vigna SR, Grant AO, Liddle RA. Amino acids stimulate cholecystokinin release through the Ca2+-sensing receptor. Am J Physiol Gastrointest Liver Physiol 2011; 300:G528-37. [PMID: 21183662 PMCID: PMC3074989 DOI: 10.1152/ajpgi.00387.2010] [Citation(s) in RCA: 125] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Cholecystokinin (CCK) is produced by discrete endocrine cells in the proximal small intestine and is released following the ingestion of food. CCK is the primary hormone responsible for gallbladder contraction and has potent effects on pancreatic secretion, gastric emptying, and satiety. In addition to fats, digested proteins and aromatic amino acids are major stimulants of CCK release. However, the cellular mechanism by which amino acids affect CCK secretion is unknown. The Ca(2+)-sensing receptor (CaSR) that was originally identified on parathyroid cells is not only sensitive to extracellular Ca(2+) but is activated by extracellular aromatic amino acids. It has been postulated that this receptor may be involved in gastrointestinal hormone secretion. Using transgenic mice expressing a CCK promoter driven/enhanced green fluorescent protein (GFP) transgene, we have been able to identify and purify viable intestinal CCK cells. Intestinal mucosal CCK cells were enriched >200-fold by fluorescence-activated cell sorting. These cells were then used for real-time PCR identification of CaSR. Immunohistochemical staining with an antibody specific for CaSR confirmed colocalization of CaSR to CCK cells. In isolated CCK cells loaded with a Ca(2+)-sensitive dye, the amino acids phenylalanine and tryptophan, but not nonaromatic amino acids, caused an increase in intracellular Ca(2+) ([Ca(2+)](i)). The increase in [Ca(2+)](i) was blocked by the CaSR inhibitor Calhex 231. Phenylalanine and tryptophan stimulated CCK release from intestinal CCK cells, and this stimulation was also blocked by CaSR inhibition. Electrophysiological recordings from isolated CCK-GFP cells revealed these cells to possess a predominant outwardly rectifying potassium current. Administration of phenylalanine inhibited basal K(+) channel activity and caused CCK cell depolarization, consistent with changes necessary for hormone secretion. These findings indicate that amino acids have a direct effect on CCK cells to stimulate CCK release by activating CaSR and suggest that CaSR is the physiological mechanism through which amino acids regulate CCK secretion.
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Affiliation(s)
- Yu Wang
- Department of Medicine, Duke University and Durham Veterans Affairs Medical Centers, Durham, North Carolina
| | - Rashmi Chandra
- Department of Medicine, Duke University and Durham Veterans Affairs Medical Centers, Durham, North Carolina
| | - Leigh Ann Samsa
- Department of Medicine, Duke University and Durham Veterans Affairs Medical Centers, Durham, North Carolina
| | - Barry Gooch
- Department of Medicine, Duke University and Durham Veterans Affairs Medical Centers, Durham, North Carolina
| | - Brian E. Fee
- Department of Medicine, Duke University and Durham Veterans Affairs Medical Centers, Durham, North Carolina
| | - J. Michael Cook
- Department of Medicine, Duke University and Durham Veterans Affairs Medical Centers, Durham, North Carolina
| | - Steven R. Vigna
- Department of Medicine, Duke University and Durham Veterans Affairs Medical Centers, Durham, North Carolina
| | - Augustus O. Grant
- Department of Medicine, Duke University and Durham Veterans Affairs Medical Centers, Durham, North Carolina
| | - Rodger A. Liddle
- Department of Medicine, Duke University and Durham Veterans Affairs Medical Centers, Durham, North Carolina
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27
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Abstract
Luminal amino acids and lack of luminal acidity as a result of acid neutralization by intragastric foodstuffs are powerful signals for acid secretion. Although the hormonal and neural pathways underlying this regulatory mechanism are well understood, the nature of the gastric luminal pH sensor has been enigmatic. In clinical studies, high pH, tryptic peptides, and luminal divalent metals (Ca2+ and Mg2+) increase gastrin release and acid production. The calcium-sensing receptor (CaSR), first described in the parathyroid gland but expressed on gastric G cells, is a logical candidate for the gastric acid sensor. Because CaSR ligands include amino acids and divalent metals, and because extracellular pH affects ligand binding in the pH range of the gastric content, its pH, metal, and nutrient-sensing functions are consistent with physiologic observations. The CaSR is thus an attractive candidate for the gastric luminal sensor that is part of the neuroendocrine negative regulatory loop for acid secretion.
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Affiliation(s)
- Tyralee Goo
- Greater Los Angeles Veteran Affairs Healthcare System, West Los Angeles VA Medical Center, Los Angeles, CA 90073, USA
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28
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Abstract
Compelling evidence of a cell surface receptor sensitive to extracellular calcium was observed as early as the 1980s and was finally realized in 1993 when the calcium-sensing receptor (CaR) was cloned from bovine parathyroid tissue. Initial studies relating to the CaR focused on its key role in extracellular calcium homeostasis, but as the amount of information about the receptor grew it became evident that it was involved in many biological processes unrelated to calcium homeostasis. The CaR responds to a diverse array of stimuli extending well beyond that merely of calcium, and these stimuli can lead to the initiation of a wide variety of intracellular signaling pathways that in turn are able to regulate a diverse range of biological processes. It has been through the examination of the molecular characteristics of the CaR that we now have an understanding of how this single receptor is able to convert extracellular messages into specific cellular responses. Recent CaR-related reviews have focused on specific aspects of the receptor, generally in the context of the CaR's role in physiology and pathophysiology. This review will provide a comprehensive exploration of the different aspects of the receptor, including its structure, stimuli, signalling, interacting protein partners, and tissue expression patterns, and will relate their impact on the functionality of the CaR from a molecular perspective.
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Affiliation(s)
- Aaron L Magno
- Department of Endocrinology and Diabetes, First Floor, C Block, Sir Charles Gairdner Hospital, Hospital Avenue, Nedlands 6009, Western Australia, Australia
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29
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Abstract
The upper gastrointestinal (GI) mucosa is exposed to endogenous and exogenous chemicals, including gastric acid, CO₂ and nutrients. Mucosal chemical sensors are necessary to exert physiological responses such as secretion, digestion, absorption and motility. We propose the mucosal chemosensing system by which luminal chemicals are sensed to trigger mucosal defence mechanisms via mucosal acid sensors and taste receptors. Luminal acid/CO₂ is sensed via ecto- and cytosolic carbonic anhydrases and ion transporters in the epithelial cells and via acid sensors on the afferent nerves in the duodenum and the oesophagus. Gastric acid sensing is differentially mediated via endocrine cell acid sensors and afferent nerves. Furthermore, a luminal l-glutamate signal is mediated via epithelial l-glutamate receptors, including metabotropic glutamate receptors and taste receptor 1 family heterodimers, with activation of afferent nerves and cyclooxygenase, whereas luminal Ca²(+) is differently sensed via the calcium-sensing receptor in the duodenum. These luminal chemosensors help to activate mucosal defence mechanisms in order to maintain the mucosal integrity and physiological responses of the upper GI tract. Stimulation of luminal chemosensing in the upper GI mucosa may prevent mucosal injury, affect nutrient metabolism and modulate sensory nerve activity.
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Affiliation(s)
- Y Akiba
- Department of Medicine, University of California Los Angeles, Brentwood Biomedical Research Institute, USA.
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30
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Calcium-sensing receptor is a physiologic multimodal chemosensor regulating gastric G-cell growth and gastrin secretion. Proc Natl Acad Sci U S A 2010; 107:17791-6. [PMID: 20876097 DOI: 10.1073/pnas.1009078107] [Citation(s) in RCA: 106] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The calcium-sensing receptor (CaR) is the major sensor and regulator of extracellular Ca(2+), whose activity is allosterically regulated by amino acids and pH. Recently, CaR has been identified in the stomach and intestinal tract, where it has been proposed to function in a non-Ca(2+) homeostatic capacity. Luminal nutrients, such as Ca(2+) and amino acids, have been recognized for decades as potent stimulants for gastrin and acid secretion, although the molecular basis for their recognition remains unknown. The expression of CaR on gastrin-secreting G cells in the stomach and their shared activation by Ca(2+), amino acids, and elevated pH suggest that CaR may function as the elusive physiologic sensor regulating gastrin and acid secretion. The genetic and pharmacologic studies presented here comparing CaR-null mice and wild-type littermates support this hypothesis. Gavage of Ca(2+), peptone, phenylalanine, Hepes buffer (pH 7.4), and CaR-specific calcimimetic, cinacalcet, stimulated gastrin and acid secretion, whereas the calcilytic, NPS 2143, inhibited secretion only in the wild-type mouse. Consistent with known growth and developmental functions of CaR, G-cell number was progressively reduced between 30 and 90 d of age by more than 65% in CaR-null mice. These studies of nutrient-regulated G-cell gastrin secretion and growth provide definitive evidence that CaR functions as a physiologically relevant multimodal sensor. Medicinals targeting diseases of Ca(2+) homeostasis should be reviewed for effects outside traditional Ca(2+)-regulating tissues in view of the broader distribution and function of CaR.
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Cifuentes M, Fuentes C, Mattar P, Tobar N, Hugo E, Ben-Jonathan N, Rojas C, Martínez J. Obesity-associated proinflammatory cytokines increase calcium sensing receptor (CaSR) protein expression in primary human adipocytes and LS14 human adipose cell line. Arch Biochem Biophys 2010; 500:151-6. [PMID: 20595056 DOI: 10.1016/j.abb.2010.05.033] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2010] [Revised: 05/28/2010] [Accepted: 05/28/2010] [Indexed: 12/14/2022]
Abstract
Obesity-associated health complications are thought to be in part due to the low-grade proinflammatory state that characterizes this disease. The calcium sensing receptor (CaSR), which is expressed in human adipose cells, plays an important role in diseases involving inflammation. To assess the relevance of this protein in adipose pathophysiology, we evaluated its expression in adipocytes under obesity-related proinflammatory conditions. As in primary adipose cells, we established that LS14, a recently described human adipose cell line, expresses the CaSR. Differentiated LS14 and primary adipose cells were exposed overnight to cytokines typically involved in obesity-related inflammation (interleukin (IL)1beta, IL6 and tumor necrosis factor (TNF)alpha). The cytokines increased CaSR abundance in differentiated adipocytes. We incubated LS14 cells with medium previously conditioned (CM) by adipose tissue from subjects with a wide range of body mass index (BMI). Cells exposed to CM from subjects of higher BMI underwent a greater increase in CaSR protein, likely resulting from the greater proinflammatory cytokines secreted from obese tissue. Our observations that proinflammatory factors increase CaSR levels in adipocytes, and the reported ability of CaSR to elevate cytokine levels, open new aspects in the study of obesity inflammatory state pathophysiology, providing a potential novel therapeutic prevention and treatment target.
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Affiliation(s)
- Mariana Cifuentes
- Institute of Nutrition and Food Technology, Universidad de Chile, Chile.
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Abstract
The mechanisms by which the gut senses and responds to nutrients involve the interplay of multiple complex pathways. In addition to regulating digestion and absorption, the pathways stimulated by molecules in the gut lumen mediate gastric motility, food intake, and satiety. Furthermore, protective mechanisms are activated as necessary to prevent injury, promote healing, and limit intake and absorption of potentially toxic substances. This review provides an update on the current knowledge and recent findings related to gastric sensing of nutrients, highlighting recent research and future endeavors in the field.
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Affiliation(s)
- Arushi deFonseka
- West Los Angeles VA Medical Center, Building 114, Suite 217, Los Angeles, CA 90073, USA
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Soybean β51–63 peptide stimulates cholecystokinin secretion via a calcium-sensing receptor in enteroendocrine STC-1 cells. ACTA ACUST UNITED AC 2010; 159:148-55. [DOI: 10.1016/j.regpep.2009.11.007] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2009] [Revised: 10/06/2009] [Accepted: 11/01/2009] [Indexed: 11/22/2022]
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