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Abstract
Gastric acid secretion (i) facilitates digestion of protein as well as absorption of micronutrients and certain medications, (ii) kills ingested microorganisms, including Helicobacter pylori, and (iii) prevents bacterial overgrowth and enteric infection. The principal regulators of acid secretion are the gastric peptides gastrin and somatostatin. Gastrin, the major hormonal stimulant for acid secretion, is synthesized in pyloric mucosal G cells as a 101-amino acid precursor (preprogastrin) that is processed to yield biologically active amidated gastrin-17 and gastrin-34. The C-terminal active site of gastrin (Trp-Met-Asp-Phe-NH2 ) binds to gastrin/CCK2 receptors on parietal and, more importantly, histamine-containing enterochromaffin-like (ECL) cells, located in oxyntic mucosa, to induce acid secretion. Histamine diffuses to the neighboring parietal cells where it binds to histamine H2 -receptors coupled to hydrochloric acid secretion. Gastrin is also a trophic hormone that maintains the integrity of gastric mucosa, induces proliferation of parietal and ECL cells, and is thought to play a role in carcinogenesis. Somatostatin, present in D cells of the gastric pyloric and oxyntic mucosa, is the main inhibitor of acid secretion, particularly during the interdigestive period. Somatostatin exerts a tonic paracrine restraint on gastrin secretion from G cells, histamine secretion from ECL cells, and acid secretion from parietal cells. Removal of this restraint, for example by activation of cholinergic neurons during ingestion of food, initiates and maximizes acid secretion. Knowledge regarding the structure and function of gastrin, somatostatin, and their respective receptors is providing novel avenues to better diagnose and manage acid-peptic disorders and certain cancers. Published 2020. Compr Physiol 10:197-228, 2020.
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Affiliation(s)
- Mitchell L Schubert
- Division of Gastroenterology, Department of Medicine, Virginia Commonwealth University Health System, Richmond, Virginia, USA.,Hunter Holmes McGuire Veterans Affairs Medical Center, Richmond, Virginia, USA
| | - Jens F Rehfeld
- Department of Clinical Biochemistry, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
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2
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Laval M, Dumesny C, Eutick M, Baldwin GS, Marshall KM. Oral trivalent bismuth ions decrease, and trivalent indium or ruthenium ions increase, intestinal tumor burden in Apc Δ14/+ mice. Metallomics 2018; 10:194-200. [PMID: 29296993 DOI: 10.1039/c7mt00272f] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Immature forms of the peptide hormone gastrin have been implicated in the development of colorectal cancer (CRC). The biological activity of glycine-extended gastrin (Ggly) is dependent on the binding of Fe3+ ions in vitro and in vivo. The aim of the present study was to determine the effect of blocking Fe3+ ion binding to Ggly, using Bi3+, In3+ or Ru3+ ions, on the development of intestinal tumors in APCΔ14/+ mice. APCΔ14/+ mice were treated orally with Bi3+, In3+ or Ru3+ ions for up to 60 days, serum trace metals were analyzed by inductively coupled plasma mass spectrometry, and the incidence and size of intestinal tumors were assessed. Bi3+ treatment significantly decreased the number of tumors larger than 3 mm in male mice. In3+ or Ru3+ treatment significantly increased the tumor burden in all animals and In3+ increased the number of tumors larger than 3 mm or 5 mm in male mice alone. The fact that binding of In3+ or Ru3+ ions to Ggly was orders of magnitude stronger than the binding of Bi3+ ions implies that the inhibitory effect of Bi3+ ions is not a consequence of a reduction in Ggly activity. However, further testing of higher doses of Bi3+ ions for longer periods as an oral treatment for intestinal tumors is warranted.
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Affiliation(s)
- Marie Laval
- University of Melbourne Department of Surgery, Austin Health, Heidelberg, Victoria, Australia.
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Zhang H, Wang J, Liu Y, Sun B. Glutinous rice amylopectin can adjust the plasma gut-regulated peptide levels in rhubarb-induced spleen deficiency rats. Food Funct 2016; 7:938-42. [PMID: 26698151 DOI: 10.1039/c5fo00859j] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The pharmacological effects of glutinous rice (GR) and GR amylopectin (GRA) on the gastrointestine were investigated in rhubarb-induced spleen deficiency rats by determining the levels of gastrointestinal hormones such as the peptides serum gastrin, amylase motilin, and somatostatin. GR and GRA were given by gavage at various doses of GR (7.5, 15, and 30 g per kg body weight) and GRA (3.8, 7.6, and 15 g per kg body weight) every day for 4 weeks, respectively. The results indicated that the final body weight of rats in the highest-dose GR (GRH) group and all the GRA groups significantly (P < 0.05) increased (7.2-12.1%) compared with the model control (MC) group. All the GR and GRA treated groups had significantly (P < 0.05) higher gastrin contents (32.8-51.2%), motilin levels (13.8-39.2%), and amylase contents (22.5-39.4%) and the GRH and highest-dose GRA (GRAH) groups had significantly (P < 0.05) lower somatostatin contents compared with the MC group. Meanwhile, the somatostatin contents were negatively correlated with the motilin levels (r = -0.964, P < 0.01) and amylase contents (r = -0.981, P < 0.01). The GRAH treatment group had the highest final body weight, gastrin contents, motilin levels, and amylase contents and the lowest somatostatin contents, which demonstrated that GRA might play the most important role in the spleen-regulating activities of GR.
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Affiliation(s)
- Huijuan Zhang
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, Beijing Higher Institution Engineering Research Center of Food Additives and Ingredients, Beijing Laboratory for Food Quality and Safety, Beijing Technology & Business University (BTBU), Beijing 100048, China.
| | - Jing Wang
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, Beijing Higher Institution Engineering Research Center of Food Additives and Ingredients, Beijing Laboratory for Food Quality and Safety, Beijing Technology & Business University (BTBU), Beijing 100048, China.
| | - Yingli Liu
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, Beijing Higher Institution Engineering Research Center of Food Additives and Ingredients, Beijing Laboratory for Food Quality and Safety, Beijing Technology & Business University (BTBU), Beijing 100048, China.
| | - Baoguo Sun
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, Beijing Higher Institution Engineering Research Center of Food Additives and Ingredients, Beijing Laboratory for Food Quality and Safety, Beijing Technology & Business University (BTBU), Beijing 100048, China.
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Laval M, Baldwin GS, Shulkes A, Marshall KM. Increased gastrin gene expression provides a physiological advantage to mice under hypoxic conditions. Am J Physiol Gastrointest Liver Physiol 2015; 308:G76-84. [PMID: 25394662 DOI: 10.1152/ajpgi.00344.2014] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Hypoxia, or a low concentration of O2, is encountered in humans undertaking activities such as mountain climbing and scuba diving and is important pathophysiologically as a limiting factor in tumor growth. Although data on the interplay between hypoxia and gastrins are limited, gastrin expression is upregulated by hypoxia in gastrointestinal cancer cell lines, and gastrins counterbalance hypoxia by stimulating angiogenesis in vitro and in vivo. The aim of this study was to determine if higher concentrations of the gastrin precursor progastrin are protective against hypoxia in vivo. hGAS mice, which overexpress progastrin in the liver, and mice of the corresponding wild-type FVB/N strain were exposed to normoxia or hypoxia. Iron status was assessed by measurement of serum iron parameters, real-time PCR for mRNAs encoding critical iron regulatory proteins, and Perls' stain and atomic absorption spectrometry for tissue iron concentrations. FVB/N mice lost weight at a faster rate and had higher sickness scores than hGAS mice exposed to hypoxia. Serum iron levels were lower in hGAS than FVB/N mice and decreased further when the animals were exposed to hypoxia. The concentration of iron in the liver was strikingly lower in hGAS than FVB/N mice. We conclude that increased circulating concentrations of progastrin provide a physiological advantage against systemic hypoxia in mice, possibly by increasing the availability of iron stores. This is the first report of an association between progastrin overexpression, hypoxia, and iron homeostasis.
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Affiliation(s)
- Marie Laval
- Department of Surgery, University of Melbourne, Austin Health, Melbourne, Victoria, Australia
| | - Graham S Baldwin
- Department of Surgery, University of Melbourne, Austin Health, Melbourne, Victoria, Australia
| | - Arthur Shulkes
- Department of Surgery, University of Melbourne, Austin Health, Melbourne, Victoria, Australia
| | - Kathryn M Marshall
- Department of Surgery, University of Melbourne, Austin Health, Melbourne, Victoria, Australia
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Abstract
Iron deficiency anemia arises when the balance of iron intake, iron stores, and the body's loss of iron are insufficient to fully support production of erythrocytes. Iron deficiency anemia rarely causes death, but the impact on human health is significant. In the developed world, this disease is easily identified and treated, but frequently overlooked by physicians. In contrast, it is a health problem that affects major portions of the population in underdeveloped countries. Overall, the prevention and successful treatment for iron deficiency anemia remains woefully insufficient worldwide, especially among underprivileged women and children. Here, clinical and laboratory features of the disease are discussed, and then focus is placed on relevant economic, environmental, infectious, and genetic factors that converge among global populations.
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Affiliation(s)
- Jeffery L Miller
- Molecular Medicine Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA.
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Thomson MJ, Pritchard DM, Boxall SA, Abuderman AA, Williams JM, Varro A, Crabtree JE. Gastric Helicobacter infection induces iron deficiency in the INS-GAS mouse. PLoS One 2012. [PMID: 23185574 PMCID: PMC3501456 DOI: 10.1371/journal.pone.0050194] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
There is increasing evidence from clinical and population studies for a role of H. pylori infection in the aetiology of iron deficiency. Rodent models of Helicobacter infection are helpful for investigating any causal links and mechanisms of iron deficiency in the host. The aim of this study was to investigate the effects of gastric Helicobacter infection on iron deficiency and host iron metabolism/transport gene expression in hypergastrinemic INS-GAS mice. INS-GAS mice were infected with Helicobacter felis for 3, 6 and 9 months. At post mortem, blood was taken for assessment of iron status and gastric mucosa for pathology, immunohistology and analysis of gene expression. Chronic Helicobacter infection of INS- GAS mice resulted in decreased serum iron, transferrin saturation and hypoferritinemia and increased Total iron binding capacity (TIBC). Decreased serum iron concentrations were associated with a concomitant reduction in the number of parietal cells, strengthening the association between hypochlorhydria and gastric Helicobacter-induced iron deficiency. Infection with H. felis for nine months was associated with decreased gastric expression of iron metabolism regulators hepcidin, Bmp4 and Bmp6 but increased expression of Ferroportin 1, the iron efflux protein, iron absorption genes such as Divalent metal transporter 1, Transferrin receptor 1 and also Lcn2 a siderophore-binding protein. The INS-GAS mouse is therefore a useful model for studying Helicobacter-induced iron deficiency. Furthermore, the marked changes in expression of gastric iron transporters following Helicobacter infection may be relevant to the more rapid development of carcinogenesis in the Helicobacter infected INS-GAS model.
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MESH Headings
- Acute-Phase Proteins/genetics
- Acute-Phase Proteins/metabolism
- Anemia, Iron-Deficiency/complications
- Anemia, Iron-Deficiency/metabolism
- Anemia, Iron-Deficiency/microbiology
- Anemia, Iron-Deficiency/pathology
- Animals
- Antimicrobial Cationic Peptides/genetics
- Antimicrobial Cationic Peptides/metabolism
- Bone Morphogenetic Protein 4/genetics
- Bone Morphogenetic Protein 4/metabolism
- Bone Morphogenetic Protein 6/genetics
- Bone Morphogenetic Protein 6/metabolism
- Cation Transport Proteins/genetics
- Cation Transport Proteins/metabolism
- Gastrins/genetics
- Gene Expression Regulation
- Helicobacter Infections/complications
- Helicobacter Infections/metabolism
- Helicobacter Infections/microbiology
- Helicobacter Infections/pathology
- Helicobacter felis/metabolism
- Helicobacter felis/pathogenicity
- Hepcidins
- Insulin/genetics
- Iron/metabolism
- Lipocalin-2
- Lipocalins/genetics
- Lipocalins/metabolism
- Male
- Mice
- Mice, Transgenic
- Oncogene Proteins/genetics
- Oncogene Proteins/metabolism
- Parietal Cells, Gastric/metabolism
- Parietal Cells, Gastric/microbiology
- Parietal Cells, Gastric/pathology
- Receptors, Transferrin/genetics
- Receptors, Transferrin/metabolism
- Signal Transduction
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Affiliation(s)
- Melanie J. Thomson
- Molecular Gastroenterology, Leeds Institute of Molecular Medicine, St. James’s University Hospital, Leeds, United Kingdom
| | - D. Mark Pritchard
- Institute of Translational Medicine, University of Liverpool, Liverpool, United Kingdom
| | - Sally A. Boxall
- Molecular Gastroenterology, Leeds Institute of Molecular Medicine, St. James’s University Hospital, Leeds, United Kingdom
| | - Abdul A. Abuderman
- Institute of Translational Medicine, University of Liverpool, Liverpool, United Kingdom
| | - Jonathan M. Williams
- Institute of Translational Medicine, University of Liverpool, Liverpool, United Kingdom
| | - Andrea Varro
- Institute of Translational Medicine, University of Liverpool, Liverpool, United Kingdom
| | - Jean E. Crabtree
- Molecular Gastroenterology, Leeds Institute of Molecular Medicine, St. James’s University Hospital, Leeds, United Kingdom
- * E-mail:
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Abstract
PURPOSE OF REVIEW This review summarizes the past year's literature regarding the regulation of gastric exocrine and endocrine secretion, both basic science and clinical. RECENT FINDINGS Gastric acid secretion facilitates the digestion of protein as well as the absorption of iron, calcium, vitamin B12, and certain medications as well as prevents bacterial overgrowth, enteric infection, and possibly community-acquired pneumonia, spontaneous bacterial peritonitis, and IgE-mediated food allergy. It is regulated by neural (e.g., pituitary adenylate cyclase-activating peptide), hormonal (e.g., gastrin, ghrelin, and apelin), and paracrine (e.g., histamine) pathways as well as by chemical (e.g., amino acids) and bacterial stimuli (e.g., Helicobacter pylori). Novel peptides, which may possess physiologic function, have been identified in gastric mucosal neuroendocrine cells including parathyroid hormone-like hormone in histamine-secreting enterochromaffin-like cells and hepcidin in acid-secreting parietal cells. The secretion of hydrochloric acid by parietal cells involves translocation of the proton pump, HK-ATPase, to the apical membrane along with activation of apical chloride and potassium channels. Serum markers include chromogranin A for neuroendocrine tumors, pepsinogen I for gastric atrophy, and pepsinogen II for H. pylori infection. SUMMARY We continue to make progress in our understanding of the regulation of gastric acid secretion in health and disease.
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Camaschella C. How I manage patients with atypical microcytic anaemia. Br J Haematol 2012; 160:12-24. [PMID: 23057559 DOI: 10.1111/bjh.12081] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2012] [Accepted: 09/07/2012] [Indexed: 01/19/2023]
Abstract
Microcytic hypochromic anaemias are a result of defective iron handling by erythroblasts that decrease the haemoglobin content per red cell. Recent advances in our knowledge of iron metabolism and its homeostasis have led to the discovery of novel inherited anaemias that need to be distinguished from common iron deficiency or other causes of microcytosis. These atypical microcytic anaemias can be classified as: (i) defects of intestinal iron absorption (ii) disorders of the transferrin receptor cycle that impair erythroblast iron uptake (iii) defects of mitochondrial iron utilization for haem or iron sulphur cluster synthesis and (iv) defects of iron recycling. A careful patient history and evaluation of laboratory tests may enable these rare conditions to be distinguished from the more common iron deficiency anaemia. Molecular studies allow distinction of the different types, a prerequisite for differentiated therapy.
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Affiliation(s)
- Clara Camaschella
- Vita-Salute University and San Raffaele Scientific Institute, Via Olgettina 60, Milan, Italy.
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Bartnikas TB, Fleming MD, Schmidt PJ. Murine mutants in the study of systemic iron metabolism and its disorders: an update on recent advances. BIOCHIMICA ET BIOPHYSICA ACTA 2012; 1823:1444-50. [PMID: 22306267 PMCID: PMC3360922 DOI: 10.1016/j.bbamcr.2012.01.011] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2011] [Revised: 01/09/2012] [Accepted: 01/18/2012] [Indexed: 02/08/2023]
Abstract
Many past and recent advances in the field of iron metabolism have relied upon the use of mouse models of disease. These models have arisen spontaneously in breeder colonies or have been engineered for global or conditional ablation or overexpression of select genes. Full phenotypic characterization of these models typically involves maintenance on iron-loaded or -deficient diets, treatment with oxidative or hemolytic agents, breeding to other mutant lines or other stresses. In this review, we focus on systemic iron biology and the contributions that mouse model-based studies have made to the field. We have divided the field into three broad areas of research: dietary iron absorption, regulation of hepcidin expression and cellular iron metabolism. For each area, we begin with an overview of the current understanding of key molecular and cellular determinants then discuss recent advances. Finally, we conclude with brief comments on prospects for future study. This article is part of a Special Issue entitled: Cell Biology of Metals.
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Xiao L, Kovac S, Chang M, Shulkes A, Baldwin GS, Patel O. Induction of gastrin expression in gastrointestinal cells by hypoxia or cobalt is independent of hypoxia-inducible factor (HIF). Endocrinology 2012; 153:3006-16. [PMID: 22593272 PMCID: PMC3380302 DOI: 10.1210/en.2011-2069] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Gastrin and its precursors have been shown to promote mitogenesis and angiogenesis in gastrointestinal tumors. Hypoxia stimulates tumor growth, but its effect on gastrin gene regulation has not been examined in detail. Here we have investigated the effect of hypoxia on the transcription of the gastrin gene in human gastric cancer (AGS) cells. Gastrin mRNA was measured by real-time PCR, gastrin peptides were measured by RIA, and gastrin promoter activity was measured by dual-luciferase reporter assay. Exposure to a low oxygen concentration (1%) increased gastrin mRNA concentrations in wild-type AGS cells (AGS) and in AGS cells overexpressing the gastrin receptor (AGS-cholecystokinin receptor 2) by 2.1 ± 0.4- and 4.1 ± 0.3-fold (P < 0.05), respectively. The hypoxia mimetic, cobalt chloride (300 μM), increased gastrin promoter activity in AGS cells by 2.4 ± 0.3-fold (P < 0.05), and in AGS-cholecystokinin receptor 2 cells by 4.0 ± 0.3-fold (P < 0.05), respectively. The observations that either deletion from the gastrin promoter of the putative binding sites for the transcription factor hypoxia-inducible factor 1 (HIF-1) or knockdown of either the HIF-1α or HIF-1β subunit did not affect gastrin promoter inducibility under hypoxia indicated that the hypoxic activation of the gastrin gene is likely HIF independent. Mutational analysis of previously identified Sp1 regulatory elements in the gastrin promoter also failed to abrogate the induction of promoter activity by hypoxia. The observations that hypoxia up-regulates the gastrin gene in AGS cells by HIF-independent mechanisms, and that this effect is enhanced by the presence of gastrin receptors, provide potential targets for gastrointestinal cancer therapy.
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Affiliation(s)
- Lin Xiao
- The University of Melbourne, Department of Surgery, Austin Health, Studley Road, Heidelberg, Victoria 3084, Australia
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