1
|
Shahin NN, Shaker OG, Mahmoud MO. GOAT rs10096097 and CREB1 rs6740584 single nucleotide polymorphisms are associated with type 2 diabetes mellitus in Egyptians. Arch Pharm (Weinheim) 2024:e2400011. [PMID: 38713912 DOI: 10.1002/ardp.202400011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2024] [Revised: 04/14/2024] [Accepted: 04/17/2024] [Indexed: 05/09/2024]
Abstract
Diabetes mellitus (DM) is a chronic disorder that affects nearly half a billion people around the world and causes millions of deaths annually. Treatment of diabetes or related complications represents an economic burden not only for developing countries but also for the developed ones. Hence, new efficient therapeutic and preventive strategies and screening tools are necessary. The current work aimed to assess the potential association of single nucleotide polymorphisms (SNPs) in ghrelin O-acyltransferase (GOAT) rs10096097, cyclic adenosine monophosphate (cAMP) response element binding protein (CREB) rs6740584, and v-maf musculoaponeurotic fibrosarcoma oncogene homolog A (MafA) rs62521874 genes with type 2 DM susceptibility in Egyptians. A total of 96 patients with type 2 DM along with 72 healthy individuals participated in this study. Genotyping was executed via real-time polymerase chain reaction (PCR), and the serum protein levels of GOAT, CREB, and MafA were measured by enzyme-linked immunosorbent assay (ELISA). Genotyping revealed a significant association of GOAT rs10096097 and CREB1 rs6740584 SNPs with type 2 diabetes risk, with significantly higher GOAT rs10096097 G allele and CREB1 rs6740584 T allele frequencies in diabetic patients than in controls. However, insignificant association was identified between the MafA rs62521874 SNP and diabetes in the examined sample of the Egyptian residents. Serum GOAT, CREB1, and MafA protein levels did not vary significantly between diabetic and control individuals. Yet, significant variation in serum GOAT and CREB1 levels was detected between CREB1 rs6740584 genotypes within the diabetic group, with CT and TT genotype carriers showing higher levels than AA genotype patients. GOAT rs10096097 and CREB1 rs6740584, but not MafA rs62521874, SNPs are associated with type 2 diabetes risk in the studied Egyptians.
Collapse
Affiliation(s)
- Nancy N Shahin
- Biochemistry Department, Faculty of Pharmacy, Cairo University, Cairo, Egypt
| | - Olfat G Shaker
- Medical Biochemistry and Molecular Biology Department, Faculty of Medicine, Cairo University, Cairo, Egypt
| | - Mohamed O Mahmoud
- Biochemistry Department, Faculty of Pharmacy, Beni-Suef University, Beni-Suef, Egypt
| |
Collapse
|
2
|
Hill TG, Hill DJ. The Importance of Intra-Islet Communication in the Function and Plasticity of the Islets of Langerhans during Health and Diabetes. Int J Mol Sci 2024; 25:4070. [PMID: 38612880 PMCID: PMC11012451 DOI: 10.3390/ijms25074070] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2024] [Revised: 03/27/2024] [Accepted: 03/27/2024] [Indexed: 04/14/2024] Open
Abstract
Islets of Langerhans are anatomically dispersed within the pancreas and exhibit regulatory coordination between islets in response to nutritional and inflammatory stimuli. However, within individual islets, there is also multi-faceted coordination of function between individual beta-cells, and between beta-cells and other endocrine and vascular cell types. This is mediated partly through circulatory feedback of the major secreted hormones, insulin and glucagon, but also by autocrine and paracrine actions within the islet by a range of other secreted products, including somatostatin, urocortin 3, serotonin, glucagon-like peptide-1, acetylcholine, and ghrelin. Their availability can be modulated within the islet by pericyte-mediated regulation of microvascular blood flow. Within the islet, both endocrine progenitor cells and the ability of endocrine cells to trans-differentiate between phenotypes can alter endocrine cell mass to adapt to changed metabolic circumstances, regulated by the within-islet trophic environment. Optimal islet function is precariously balanced due to the high metabolic rate required by beta-cells to synthesize and secrete insulin, and they are susceptible to oxidative and endoplasmic reticular stress in the face of high metabolic demand. Resulting changes in paracrine dynamics within the islets can contribute to the emergence of Types 1, 2 and gestational diabetes.
Collapse
Affiliation(s)
- Thomas G. Hill
- Oxford Centre for Diabetes, Endocrinology, and Metabolism, Radcliffe Department of Medicine, University of Oxford, Oxford OX3 9DU, UK
| | - David J. Hill
- Lawson Health Research Institute, St. Joseph’s Health Care, London, ON N6A 4V2, Canada;
- Departments of Medicine, Physiology and Pharmacology, Western University, London, ON N6A 3K7, Canada
| |
Collapse
|
3
|
Bora RR, Prasad R, Khatib MN. Cardio-Protective Role of a Gut Hormone Obestatin: A Narrative Review. Cureus 2023; 15:e37972. [PMID: 37223200 PMCID: PMC10202687 DOI: 10.7759/cureus.37972] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2022] [Accepted: 04/22/2023] [Indexed: 05/25/2023] Open
Abstract
Obestatin is a gut hormone composed of 23 amino acids that play a role in protecting the heart. It is synthesized from the same preproghrelin gut hormone gene as another gut hormone. The function and receptor of obestatin remain controversial, despite being present in various organs such as the liver, heart, mammary gland, pancreas, and more. The activity of obestatin is opposite to that of ghrelin, another hormone. The GPR-39 receptor is used by obestatin to exert its effects. Obestatin's cardioprotective role can be attributed to its ability to affect various factors, including adipose tissue, blood pressure regulation, heart, ischemia-reperfusion injury, endothelial cells, and diabetes. Because these factors are related to the cardiovascular system, modifying them via obestatin can provide cardioprotection. Furthermore, ghrelin, its antagonist hormone, regulates cardiovascular health. Diabetes mellitus, hypertension, and ischemia-reperfusion injury can all alter ghrelin/obestatin levels. Obestatin has also been shown to impact other organs, reducing weight and appetite, inhibiting food intake, and increasing adipogenesis. Obestatin has a brief half-life and is quickly degraded by proteases in the blood, liver, and kidneys after entering circulation. This article offers insights into the cardiac function of obestatin.
Collapse
Affiliation(s)
- Rajal R Bora
- Physiology, Jawaharlal Nehru Medical College, Datta Meghe Institute of Higher Education and Research, Wardha, IND
| | - Roshan Prasad
- Medicine and Surgery, Jawaharlal Nehru Medical College, Datta Meghe Institute of Higher Education and Research, Wardha, IND
| | - Mahalaqua Nazli Khatib
- Epidemiology and Public Health, Jawaharlal Nehru Medical College, Datta Meghe Institute of Higher Education and Research, Wardha, IND
| |
Collapse
|
4
|
Qian Y, Xia F, Zuo Y, Zhong M, Yang L, Jiang Y, Zou C. Do patients with Prader-Willi syndrome have favorable glucose metabolism? Orphanet J Rare Dis 2022; 17:187. [PMID: 35525976 PMCID: PMC9077846 DOI: 10.1186/s13023-022-02344-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2022] [Accepted: 04/26/2022] [Indexed: 11/26/2022] Open
Abstract
Background In recent years, more studies have observed that patients with Prader–Willi syndrome have lower insulin levels and lower insulin resistance than body mass index-matched controls, which may suggest protected glucose metabolism. Method The PubMed and Web of Science online databases were searched to identify relevant studies published in the English language using the terms “Prader–Willi syndrome” with “glucose”, “insulin”, “diabetes mellitus”, “fat”, “adipo*”, “ghrelin”, “oxytocin”, “irisin” or “autonomic nervous system”. Results The prevalence of impaired glucose intolerance, type 2 diabetes mellitus and some other obesity-associated complications in patients with Prader–Willi syndrome tends to be lower when compared to that in general obesity, which is consistent with the hypothetically protected glucose metabolism. Factors including adipose tissue, adiponectin, ghrelin, oxytocin, irisin, growth hormone and the autonomic nervous system possibly modulate insulin sensitivity in patients with Prader–Willi syndrome. Conclusion Although lower insulin levels, lower IR and protected glucose metabolism are widely reported in PWS patients, the causes are still mysterious. Based on existing knowledge, we cannot determine which factor is of utmost importance and what are the underlying mechanisms, and further research is in urgent need.
Collapse
Affiliation(s)
- Yanjie Qian
- Department of Endocrinology, The Children's Hospital of Zhejiang University School of Medicine, National Clinical Research Center for Child Health, No 3333 Binsheng Road, Hangzhou, 310051, China
| | - Fangling Xia
- Department of Endocrinology, The Children's Hospital of Zhejiang University School of Medicine, National Clinical Research Center for Child Health, No 3333 Binsheng Road, Hangzhou, 310051, China
| | - Yiming Zuo
- Department of Endocrinology, The Children's Hospital of Zhejiang University School of Medicine, National Clinical Research Center for Child Health, No 3333 Binsheng Road, Hangzhou, 310051, China
| | - Mianling Zhong
- Department of Endocrinology, The Children's Hospital of Zhejiang University School of Medicine, National Clinical Research Center for Child Health, No 3333 Binsheng Road, Hangzhou, 310051, China
| | - Lili Yang
- Department of Endocrinology, The Children's Hospital of Zhejiang University School of Medicine, National Clinical Research Center for Child Health, No 3333 Binsheng Road, Hangzhou, 310051, China
| | - Yonghui Jiang
- Department of Genetics, Yale University School of Medicine, New Haven, USA
| | - Chaochun Zou
- Department of Endocrinology, The Children's Hospital of Zhejiang University School of Medicine, National Clinical Research Center for Child Health, No 3333 Binsheng Road, Hangzhou, 310051, China.
| |
Collapse
|
5
|
Villarreal D, Pradhan G, Zhou Y, Xue B, Sun Y. Diverse and Complementary Effects of Ghrelin and Obestatin. Biomolecules 2022; 12:biom12040517. [PMID: 35454106 PMCID: PMC9028691 DOI: 10.3390/biom12040517] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2022] [Revised: 03/21/2022] [Accepted: 03/25/2022] [Indexed: 02/06/2023] Open
Abstract
Ghrelin and obestatin are two “sibling proteins” encoded by the same preproghrelin gene but possess an array of diverse and complex functions. While there are ample literature documenting ghrelin’s functions, the roles of obestatin are less clear and controversial. Ghrelin and obestatin have been perceived to be antagonistic initially; however, recent studies challenge this dogma. While they have opposing effects in some systems, they function synergistically in other systems, with many functions remaining debatable. In this review, we discuss their functional relationship under three “C” categories, namely complex, complementary, and contradictory. Their functions in food intake, weight regulation, hydration, gastrointestinal motility, inflammation, and insulin secretion are complex. Their functions in pancreatic beta cells, cardiovascular, muscle, neuroprotection, cancer, and digestive system are complementary. Their functions in white adipose tissue, thermogenesis, and sleep regulation are contradictory. Overall, this review accumulates the multifaceted functions of ghrelin and obestatin under both physiological and pathological conditions, with the intent of contributing to a better understanding of these two important gut hormones.
Collapse
Affiliation(s)
- Daniel Villarreal
- Department of Nutrition, Texas A & M University, College Station, TX 77843, USA;
| | - Geetali Pradhan
- USDA/ARS Children’s Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX 77030, USA;
- Interdepartmental Program in Translational Biology and Molecular Medicine, Baylor College of Medicine, Houston, TX 77030, USA
| | - Yu Zhou
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Qingdao University, Qingdao 266071, China;
| | - Bingzhong Xue
- Department of Biology, Georgia State University, Atlanta, GA 30303, USA;
| | - Yuxiang Sun
- Department of Nutrition, Texas A & M University, College Station, TX 77843, USA;
- USDA/ARS Children’s Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX 77030, USA;
- Correspondence: ; Tel.: +1-979-862-9143
| |
Collapse
|
6
|
Gupta D, Dowsett GKC, Mani BK, Shankar K, Osborne-Lawrence S, Metzger NP, Lam BYH, Yeo GSH, Zigman JM. High Coexpression of the Ghrelin and LEAP2 Receptor GHSR With Pancreatic Polypeptide in Mouse and Human Islets. Endocrinology 2021; 162:6325122. [PMID: 34289060 PMCID: PMC8379901 DOI: 10.1210/endocr/bqab148] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/06/2021] [Indexed: 02/07/2023]
Abstract
Islets represent an important site of direct action of the hormone ghrelin, with expression of the ghrelin receptor (growth hormone secretagogue receptor; GHSR) having been localized variably to alpha cells, beta cells, and/or somatostatin (SST)-secreting delta cells. To our knowledge, GHSR expression by pancreatic polypeptide (PP)-expressing gamma cells has not been specifically investigated. Here, histochemical analyses of Ghsr-IRES-Cre × Cre-dependent ROSA26-yellow fluorescent protein (YFP) reporter mice showed 85% of GHSR-expressing islet cells coexpress PP, 50% coexpress SST, and 47% coexpress PP + SST. Analysis of single-cell transcriptomic data from mouse pancreas revealed 95% of Ghsr-expressing cells coexpress Ppy, 100% coexpress Sst, and 95% coexpress Ppy + Sst. This expression was restricted to gamma-cell and delta-cell clusters. Analysis of several single-cell human pancreatic transcriptome data sets revealed 59% of GHSR-expressing cells coexpress PPY, 95% coexpress SST, and 57% coexpress PPY + SST. This expression was prominent in delta-cell and beta-cell clusters, also occurring in other clusters including gamma cells and alpha cells. GHSR expression levels were upregulated by type 2 diabetes mellitus in beta cells. In mice, plasma PP positively correlated with fat mass and with plasma levels of the endogenous GHSR antagonist/inverse agonist LEAP2. Plasma PP also elevated on LEAP2 and synthetic GHSR antagonist administration. These data suggest that in addition to delta cells, beta cells, and alpha cells, PP-expressing pancreatic cells likely represent important direct targets for LEAP2 and/or ghrelin both in mice and humans.
Collapse
Affiliation(s)
- Deepali Gupta
- Center for Hypothalamic Research, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas 75390-9077, USA
| | - Georgina K C Dowsett
- Medical Research Council (MRC) Metabolic Diseases Unit, University of Cambridge Metabolic Research Laboratories, Wellcome Trust–MRC Institute of Metabolic Science, Addenbrooke’s Hospital, Cambridge CB2 0QQ, UK
| | - Bharath K Mani
- Center for Hypothalamic Research, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas 75390-9077, USA
| | - Kripa Shankar
- Center for Hypothalamic Research, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas 75390-9077, USA
| | - Sherri Osborne-Lawrence
- Center for Hypothalamic Research, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas 75390-9077, USA
| | - Nathan P Metzger
- Center for Hypothalamic Research, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas 75390-9077, USA
| | - Brian Y H Lam
- Medical Research Council (MRC) Metabolic Diseases Unit, University of Cambridge Metabolic Research Laboratories, Wellcome Trust–MRC Institute of Metabolic Science, Addenbrooke’s Hospital, Cambridge CB2 0QQ, UK
| | - Giles S H Yeo
- Medical Research Council (MRC) Metabolic Diseases Unit, University of Cambridge Metabolic Research Laboratories, Wellcome Trust–MRC Institute of Metabolic Science, Addenbrooke’s Hospital, Cambridge CB2 0QQ, UK
- Correspondence: Giles S. H. Yeo, PhD, Metabolic Diseases Unit, University of Cambridge Metabolic Research Laboratories, Wellcome–MRC Institute of Metabolic Science, Box 289, Addenbrooke’s Hospital, Hills Rd, Cambridge, CB2 0QQ, UK.
| | - Jeffrey M Zigman
- Center for Hypothalamic Research, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas 75390-9077, USA
- Division of Endocrinology, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas 75390-9077, USA
- Department of Psychiatry, University of Texas Southwestern Medical Center, Dallas, Texas 75390-9077, USA
- Correspondence: Jeffrey M. Zigman, MD, PhD, Center for Hypothalamic Research, Department of Internal Medicine, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, MC9077, Dallas, TX 75390-9077, USA.
| |
Collapse
|
7
|
Rachdaoui N. Insulin: The Friend and the Foe in the Development of Type 2 Diabetes Mellitus. Int J Mol Sci 2020; 21:ijms21051770. [PMID: 32150819 PMCID: PMC7084909 DOI: 10.3390/ijms21051770] [Citation(s) in RCA: 68] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2020] [Revised: 02/29/2020] [Accepted: 03/02/2020] [Indexed: 12/14/2022] Open
Abstract
Insulin, a hormone produced by pancreatic β-cells, has a primary function of maintaining glucose homeostasis. Deficiencies in β-cell insulin secretion result in the development of type 1 and type 2 diabetes, metabolic disorders characterized by high levels of blood glucose. Type 2 diabetes mellitus (T2DM) is characterized by the presence of peripheral insulin resistance in tissues such as skeletal muscle, adipose tissue and liver and develops when β-cells fail to compensate for the peripheral insulin resistance. Insulin resistance triggers a rise in insulin demand and leads to β-cell compensation by increasing both β-cell mass and insulin secretion and leads to the development of hyperinsulinemia. In a vicious cycle, hyperinsulinemia exacerbates the metabolic dysregulations that lead to β-cell failure and the development of T2DM. Insulin and IGF-1 signaling pathways play critical roles in maintaining the differentiated phenotype of β-cells. The autocrine actions of secreted insulin on β-cells is still controversial; work by us and others has shown positive and negative actions by insulin on β-cells. We discuss findings that support the concept of an autocrine action of secreted insulin on β-cells. The hypothesis of whether, during the development of T2DM, secreted insulin initially acts as a friend and contributes to β-cell compensation and then, at a later stage, becomes a foe and contributes to β-cell decompensation will be discussed.
Collapse
Affiliation(s)
- Nadia Rachdaoui
- Department of Animal Sciences, Room 108, Foran Hall, Rutgers, the State University of New Jersey, 59 Dudley Rd, New Brunswick, NJ 08901, USA
| |
Collapse
|
8
|
Konarska K, Cieszkowski J, Warzecha Z, Ceranowicz P, Chmura A, Kuśnierz-Cabala B, Gałązka K, Kowalczyk P, Miskiewicz A, Konturek TJ, Pędziwiatr M, Dembiński A. Treatment with Obestatin-A Ghrelin Gene-Encoded Peptide-Reduces the Severity of Experimental Colitis Evoked by Trinitrobenzene Sulfonic Acid. Int J Mol Sci 2018; 19:ijms19061643. [PMID: 29865176 PMCID: PMC6032262 DOI: 10.3390/ijms19061643] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2018] [Revised: 05/25/2018] [Accepted: 05/28/2018] [Indexed: 02/06/2023] Open
Abstract
Obestatin is a 23-amino acid peptide derived from proghrelin, a common prohormone for ghrelin and obestatin. Previous studies showed that obestatin exhibited some protective and therapeutic effects in the gut. The aim of our presented study was to examine the effect of treatment with obestatin on trinitrobenzene sulfonic acid (TNBS)-induced colitis. In rats anesthetized with ketamine, colitis was induced through intrarectal administration of 25 mg of 2,4,6-trinitrobenzene sulfonic acid (TNBS). Obestatin was administered intraperitoneally at doses of 4, 8, or 16 nmol/kg, twice per day for four consecutive days. The first dose of obestatin was given one day before the induction of colitis, and the last one was given two days after administration of TNBS. Fourteen days after the induction of colitis, rats were anesthetized again with ketamine, and the severity of colitis was determined. The administration of obestatin had no effect on the parameters tested in rats without the induction of colitis. In rats with colitis, administration of obestatin at doses of 8 or 16 nmol/kg reduced the area of colonic damage, and improved mucosal blood flow in the colon. These effects were accompanied by a reduction in the colitis-evoked increase in the level of blood leukocytes, and mucosal concentration of pro-inflammatory interleukin-1β. Moreover, obestatin administered at doses of 8 or 16 nmol/kg reduced histological signs of colonic damage. The administration of obestatin at a dose of 4 nmol/kg failed to significantly affect the parameters tested. Overall, treatment with obestatin reduced the severity of TNBS-induced colitis in rats. This effect was associated with an improvement in mucosal blood flow in the colon, and a decrease in local and systemic inflammatory processes.
Collapse
Affiliation(s)
- Katarzyna Konarska
- Department of Physiology, Faculty of Medicine, Jagiellonian University Medical College, 31-531 Cracow, Poland.
| | - Jakub Cieszkowski
- Department of Physiology, Faculty of Medicine, Jagiellonian University Medical College, 31-531 Cracow, Poland.
| | - Zygmunt Warzecha
- Department of Physiology, Faculty of Medicine, Jagiellonian University Medical College, 31-531 Cracow, Poland.
| | - Piotr Ceranowicz
- Department of Physiology, Faculty of Medicine, Jagiellonian University Medical College, 31-531 Cracow, Poland.
| | - Anna Chmura
- Department of Physiology, Faculty of Medicine, Jagiellonian University Medical College, 31-531 Cracow, Poland.
| | - Beata Kuśnierz-Cabala
- Department of Clinical Biochemistry, Faculty of Medicine, Jagiellonian University Medical College, 31-501 Cracow, Poland.
| | - Krystyna Gałązka
- Department of Pathomorphology, Faculty of Medicine, Jagiellonian University Medical College, 31-531 Cracow, Poland.
| | - Paweł Kowalczyk
- Department of Animal Nutrition, The Kielanowski Institute of Animal Physiology and Nutrition, Polish Academy of Sciences, 05-110 Jablonna, Poland.
| | - Andrzej Miskiewicz
- Department of Periodontology and Oral Diseases, Medical University of Warsaw, 00-246 Warsaw, Poland.
| | - Thomas Jan Konturek
- Department of Medicine, St. Elizabeth's Medical Center, Tufts University School of Medicine, Boston, MA 02135, USA.
| | - Michał Pędziwiatr
- Second Department of General Surgery, Faculty of Medicine, Jagiellonian University Medical College, 31-501 Cracow, Poland.
| | - Artur Dembiński
- Department of Physiology, Faculty of Medicine, Jagiellonian University Medical College, 31-531 Cracow, Poland.
| |
Collapse
|
9
|
Kapica M, Puzio I, Kato I, Kuwahara A, Zabielski R, Antushevich H. Exogenous obestatin affects pancreatic enzyme secretion in rat through two opposite mechanisms, direct inhibition and vagally-mediated stimulation. JOURNAL OF ANIMAL AND FEED SCIENCES 2018. [DOI: 10.22358/jafs/89734/2018] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
|
10
|
Green BD, Grieve DJ. Biochemical properties and biological actions of obestatin and its relevence in type 2 diabetes. Peptides 2018; 100:249-259. [PMID: 29412827 DOI: 10.1016/j.peptides.2017.12.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/27/2017] [Revised: 12/05/2017] [Accepted: 12/06/2017] [Indexed: 12/15/2022]
Abstract
Obestatin was initially discovered in rat stomach extract, and although it is principally produced in the gastric mucosa, it can be found throughout the gastrointestinal tract. This 23-amino acid C-terminally amidated peptide is derived from preproghrelin and has been ascribed a wide range of metabolic effects relevant to type 2 diabetes. Obestatin reportedly inhibits gastrointestinal motility, reduces food intake and lowers body weight and improves lipid metabolism. Furthermore, it appears to exert actions on the pancreatic β-cell, most notably increasing β-cell mass and upregulating genes associated with insulin production and β-cell regeneration, with relevance to type 2 diabetes. It is becoming evident that obestatin also exerts pleiotropic effects on the cardiovascular system, possibly modulating blood pressure, endothelial function and triggering cardioprotective mechanisms, which may be important in determining cardiovascular outcomes in type 2 diabetes. Furthermore, it seems that like other gut peptides obestatin has neuroprotective properties. This review examines the biochemical properties of the obestatin peptide (its structure, sequence, stability and distribution) and the candidate receptors through which it may act. It provides a balanced examination of the reported pancreatic and extrapancreatic actions of obestatin and evaluates its potential relevance with respect to diabetes therapy, together with discussion of direct evidence linking alterations in obestatin signalling with obesity/diabetes and other diseases.
Collapse
Affiliation(s)
- Brian D Green
- Institute for Global Food Security, School of Biological Sciences, Queen's University Belfast, Belfast, BT9 5BN, UK.
| | - David J Grieve
- Centre for Experimental Medicine, Queen's University Belfast, Belfast, BT9 7AE, UK
| |
Collapse
|
11
|
Pradhan G, Wu CS, Han Lee J, Kanikarla P, Guo S, Yechoor VK, Samson SL, Sun Y. Obestatin stimulates glucose-induced insulin secretion through ghrelin receptor GHS-R. Sci Rep 2017; 7:979. [PMID: 28428639 PMCID: PMC5430520 DOI: 10.1038/s41598-017-00888-0] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2016] [Accepted: 03/07/2017] [Indexed: 11/19/2022] Open
Abstract
Orexigenic hormone ghrelin and anorexic hormone obestatin are encoded by the same preproghrelin gene. While it is known that ghrelin inhibits glucose-stimulated insulin secretion (GSIS), the effect of obestatin on GSIS is unclear. Ghrelin’s effect is mediated by its receptor Growth Hormone Secretagogue Receptor (GHS-R), but the physiologically relevant receptor of obestatin remains debatable. Here we have investigated the effect of obestatin on GSIS in vitro, in vivo and ex vivo, and tested whether obestatin regulates insulin secretion through GHS-R. We found that under hyperglycemic condition, obestatin augments GSIS in rat insulinoma cells (INS-1) and in pancreatic islets from ghrelin−/− mice. Surprisingly, obestatin-induced GSIS was absent in β-cells in which GHS-R was suppressed. Obestatin-induced insulin secretion was abolished in the circulation of Ghsr−/− mice, and in pancreatic islets isolated from Ghsr−/− mice. We also found that obestatin-induced GSIS was attenuated in islets isolated from β-cell-specific Ghsr knockout MIP-Cre/ERT;Ghsrf/f mice. Our data collectively demonstrate that obestatin is a potent insulin secretagogue under hyperglycemic condition, and obestatin’s effect on insulin secretion is mediated by GHS-R in pancreatic β-cells. Our findings reveal an intriguing insight that obestatin and ghrelin have opposing effects on insulin secretion, and both are mediated through ghrelin receptor GHS-R.
Collapse
Affiliation(s)
- Geetali Pradhan
- USDA/ARS Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX, USA.,Interdepartmental Program in Translational Biology and Molecular Medicine, Baylor College of Medicine, Houston, TX, USA
| | - Chia-Shan Wu
- USDA/ARS Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX, USA.,Department of Nutrition and Food Science, Texas A&M University, College Station, TX, USA
| | - Jong Han Lee
- USDA/ARS Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX, USA.,College of Pharmacy, Gachon University, Incheon, 21936, Korea
| | - Preeti Kanikarla
- USDA/ARS Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX, USA
| | - Shaodong Guo
- Department of Nutrition and Food Science, Texas A&M University, College Station, TX, USA
| | - Vijay K Yechoor
- Department of Medicine, Baylor College of Medicine, Houston, TX, USA
| | - Susan L Samson
- Department of Medicine, Baylor College of Medicine, Houston, TX, USA
| | - Yuxiang Sun
- USDA/ARS Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX, USA. .,Department of Nutrition and Food Science, Texas A&M University, College Station, TX, USA.
| |
Collapse
|
12
|
Kolodziejski PA, Pruszynska-Oszmalek E, Sassek M, Kaczmarek P, Szczepankiewicz D, Billert M, Mackowiak P, Strowski MZ, Nowak KW. Changes in obestatin gene and GPR39 receptor expression in peripheral tissues of rat models of obesity, type 1 and type 2 diabetes. J Diabetes 2017; 9:353-361. [PMID: 27106635 DOI: 10.1111/1753-0407.12417] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/09/2015] [Revised: 03/13/2016] [Accepted: 04/15/2016] [Indexed: 12/28/2022] Open
Abstract
BACKGROUND Obestatin has a role in regulating food intake and energy expenditure, but the roles of obestatin and the GPR39 receptor in obesity and type 1 and type 2 diabetes mellitus (T1DM and T2DM, respectively) are not well understood. The aim of the present study was to investigate changes in obestatin and GPR39 in pathophysiological conditions like obesity, T1DM, and T2DM. METHODS Using rat models of diet-induced obesity (DIO), T1DM and T2DM (n = 14 per group), obestatin, its precursor protein preproghrelin, and GPR39 expression was investigated in tissues involved in glucose and lipid homeostasis regulation. Furthermore, serum obestatin and ghrelin concentrations were determined. RESULTS Serum obestatin concentrations were positively correlated with glucagon (r = 0.6456; P < 0.001) and visfatin (r = 0.5560; P < 0.001), and negatively correlated with insulin (r = -0.4362; P < 0.05), adiponectin (r = -0.3998; P < 0.05), and leptin (r = -0.4180; P < 0.05). There were differences in GPR39 and preproghrelin expression in the three animal models. Hepatic GPR39 and preproghrelin mRNA expression was greater in T1DM, T2DM, and obese rats than in lean controls, whereas pancreatic GPR39 mRNA and protein and preproghrelin mRNA expression was decreased in T1DM, T2DM, and DIO rats. Higher GPR39 and preproghrelin protein and mRNA levels were found in adipose tissues of T1DM compared with control. In adipose tissues of T2DM and DIO rats, GPR39 protein levels were lower than in lean or T1DM rats. Preproghrelin mRNA was higher in adipose tissues of T1DM, T2DM, and DIO than lean rats. CONCLUSION We hypothesize that changes in obestatin, GPR39, and ghrelin may contribute to metabolic abnormalities in T1DM, T2DM, and obesity.
Collapse
Affiliation(s)
- Pawel Antoni Kolodziejski
- Department of Animal Physiology and Biochemistry, Poznan University of Life Sciences, Poznan, Poland
- Department of Hepatology and Gastroenterology and the Interdisciplinary Centre of Metabolism: Endocrinology, Diabetes and Metabolism, Charité-University Medicine Berlin, Berlin, Germany
| | - Ewa Pruszynska-Oszmalek
- Department of Animal Physiology and Biochemistry, Poznan University of Life Sciences, Poznan, Poland
| | - Maciej Sassek
- Department of Animal Physiology and Biochemistry, Poznan University of Life Sciences, Poznan, Poland
| | - Przemyslaw Kaczmarek
- Department of Animal Physiology and Biochemistry, Poznan University of Life Sciences, Poznan, Poland
| | - Dawid Szczepankiewicz
- Department of Animal Physiology and Biochemistry, Poznan University of Life Sciences, Poznan, Poland
| | - Maria Billert
- Department of Animal Physiology and Biochemistry, Poznan University of Life Sciences, Poznan, Poland
| | - Paweł Mackowiak
- Department of Animal Physiology and Biochemistry, Poznan University of Life Sciences, Poznan, Poland
| | - Mathias Z Strowski
- Department of Hepatology and Gastroenterology and the Interdisciplinary Centre of Metabolism: Endocrinology, Diabetes and Metabolism, Charité-University Medicine Berlin, Berlin, Germany
- Medical Clinic 1, Department of Gastroenterology, Elblandklinik, Meissen, Germany
| | - Krzysztof W Nowak
- Department of Animal Physiology and Biochemistry, Poznan University of Life Sciences, Poznan, Poland
| |
Collapse
|
13
|
McGovern-Gooch KR, Mahajani NS, Garagozzo A, Schramm AJ, Hannah LG, Sieburg MA, Chisholm JD, Hougland JL. Synthetic Triterpenoid Inhibition of Human Ghrelin O-Acyltransferase: The Involvement of a Functionally Required Cysteine Provides Mechanistic Insight into Ghrelin Acylation. Biochemistry 2017; 56:919-931. [PMID: 28134508 DOI: 10.1021/acs.biochem.6b01008] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
The peptide hormone ghrelin plays a key role in regulating hunger and energy balance within the body. Ghrelin signaling presents a promising and unexploited target for development of small molecule therapeutics for treatment of obesity, diabetes, and other health conditions. Inhibition of ghrelin O-acyltransferase (GOAT), which catalyzes an essential octanoylation step in ghrelin maturation, offers a potential avenue for controlling ghrelin signaling. Through screening a small molecule library, we have identified a class of synthetic triterpenoids that efficiently inhibit ghrelin acylation by the human isoform of GOAT (hGOAT). These compounds function as covalent reversible inhibitors of hGOAT, providing the first evidence of the involvement of a nucleophilic cysteine residue in substrate acylation by a MBOAT family acyltransferase. Surprisingly, the mouse form of GOAT does not exhibit susceptibility to cysteine-modifying electrophiles, revealing an important distinction in the activity and behavior between these closely related GOAT isoforms. This study establishes these compounds as potent small molecule inhibitors of ghrelin acylation and provides a foundation for the development of novel hGOAT inhibitors as therapeutics targeting diabetes and obesity.
Collapse
Affiliation(s)
| | - Nivedita S Mahajani
- Department of Chemistry, Syracuse University , Syracuse, New York 13244, United States
| | - Ariana Garagozzo
- Department of Chemistry, Syracuse University , Syracuse, New York 13244, United States
| | - Anthony J Schramm
- Department of Chemistry, Syracuse University , Syracuse, New York 13244, United States
| | - Lauren G Hannah
- Department of Chemistry, Syracuse University , Syracuse, New York 13244, United States
| | - Michelle A Sieburg
- Department of Chemistry, Syracuse University , Syracuse, New York 13244, United States
| | - John D Chisholm
- Department of Chemistry, Syracuse University , Syracuse, New York 13244, United States
| | - James L Hougland
- Department of Chemistry, Syracuse University , Syracuse, New York 13244, United States
| |
Collapse
|
14
|
Xing YX, Yang L, Kuang HY, Gao XY, Liu HL. Function of obestatin in the digestive system. Nutrition 2017; 34:21-28. [DOI: 10.1016/j.nut.2016.08.009] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2015] [Revised: 04/18/2016] [Accepted: 08/29/2016] [Indexed: 02/07/2023]
|
15
|
Xu X, Wang J, Li L, Wang C, Li W, Zhang Q, Yang L. The role of obestatin in Roux-en-Y gastric bypass surgery in the obese, type 2 diabetes Zucker rat. Diabetes Res Clin Pract 2016; 119:57-64. [PMID: 27449711 DOI: 10.1016/j.diabres.2016.06.024] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/21/2016] [Revised: 04/20/2016] [Accepted: 06/05/2016] [Indexed: 12/25/2022]
Abstract
AIMS Roux-en-Y gastric bypass (RYGB) is a novel therapy for diabetes and the exact mechanisms of this procedure remain unclear. Obestatin is an important gut hormone. We aimed to explore the role of obestatin in the therapeutic mechanism of RYGB. METHODS Twenty obese Zucker rats and twenty Wistar rats were randomly assigned to two groups: RYGB and sham surgery. We evaluated plasma obestatin and insulin levels pre- and post-RYGB. Additionally, obestatin expression levels in the gastrointestinal tract were assessed using immunohistochemical staining. RESULTS In Zucker rats, plasma obestatin and insulin levels gradually increased after RYGB. At post-operation week 7, plasma levels of obestatin were higher in the RYGB group than the sham operation group, and fasting plasma insulin levels were significantly increased the in RYGB group compared with the sham operation group. Furthermore, we observed a positive relationship between obestatin and insulin plasma levels. Among 10 zucker rats, high expression of obestatin was only seen in the jejunum of 2 rats before the operation; however, high expression of obestatin was seen in the Roux limb of 8 rats and in the ileum of 7 rats after RYGB. The expression of obestatin was significantly higher in the intestine in the RYGB group than the sham operation group postoperatively. CONCLUSIONS We propose that obestatin maybe a potential mediator to improve glucose homeostasis after RYGB. The increase of obestatin secretion may be an important mechanism through which RYGB alleviates obesity and type 2 diabetes mellitus.
Collapse
Affiliation(s)
- Xianhui Xu
- Department of General Surgery, No. 401 Hospital of People's Liberation Army, Min Jiang Road No. 22, Qingdao, Shandong, China
| | - Jianli Wang
- Department of General Surgery 1, The Affiliated Hospital of Chengde Medical College, Chengde, Hebei, China
| | - Ling Li
- Department of Endocrinology, No. 401 Hospital of People's Liberation Army, Min Jiang Road No. 22, Qingdao, Shandong, China
| | - Chunbin Wang
- Department of Endocrinology, No. 401 Hospital of People's Liberation Army, Min Jiang Road No. 22, Qingdao, Shandong, China
| | - Weihua Li
- Department of General Surgery, No. 401 Hospital of People's Liberation Army, Min Jiang Road No. 22, Qingdao, Shandong, China
| | - Qin Zhang
- Department of General Surgery, No. 401 Hospital of People's Liberation Army, Min Jiang Road No. 22, Qingdao, Shandong, China.
| | - Linghui Yang
- Department of Endocrinology, No. 401 Hospital of People's Liberation Army, Min Jiang Road No. 22, Qingdao, Shandong, China.
| |
Collapse
|
16
|
Cowan E, Burch KJ, Green BD, Grieve DJ. Obestatin as a key regulator of metabolism and cardiovascular function with emerging therapeutic potential for diabetes. Br J Pharmacol 2016; 173:2165-81. [PMID: 27111465 DOI: 10.1111/bph.13502] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2016] [Revised: 04/05/2016] [Accepted: 04/15/2016] [Indexed: 01/01/2023] Open
Abstract
Obestatin is a 23-amino acid C-terminally amidated gastrointestinal peptide derived from preproghrelin and which forms an α helix. Although obestatin has a short biological half-life and is rapidly degraded, it is proposed to exert wide-ranging pathophysiological actions. Whilst the precise nature of many of its effects is unclear, accumulating evidence supports positive actions on both metabolism and cardiovascular function. For example, obestatin has been reported to inhibit food and water intake, body weight gain and gastrointestinal motility and also to mediate promotion of cell survival and prevention of apoptosis. Obestatin-induced increases in beta cell mass, enhanced adipogenesis and improved lipid metabolism have been noted along with up-regulation of genes associated with beta cell regeneration, insulin production and adipogenesis. Furthermore, human circulating obestatin levels generally demonstrate an inverse association with obesity and diabetes, whilst the peptide has been shown to confer protective metabolic effects in experimental diabetes, suggesting that it may hold therapeutic potential in this setting. Obestatin also appears to be involved in blood pressure regulation and to exert beneficial effects on endothelial function, with experimental studies indicating that it may also promote cardioprotective actions against, for example, ischaemia-reperfusion injury. This review will present a critical appraisal of the expanding obestatin research area and discuss the emerging therapeutic potential of this peptide for both metabolic and cardiovascular complications of diabetes.
Collapse
Affiliation(s)
- Elaine Cowan
- Queen's University Belfast, Institute for Global Food Security, School of Biological Sciences, Belfast, UK
| | - Kerry J Burch
- Queen's University Belfast, Wellcome-Wolfson Institute for Experimental Medicine, Belfast, UK
| | - Brian D Green
- Queen's University Belfast, Institute for Global Food Security, School of Biological Sciences, Belfast, UK
| | - David J Grieve
- Queen's University Belfast, Wellcome-Wolfson Institute for Experimental Medicine, Belfast, UK
| |
Collapse
|
17
|
Suzuki H, Yamamoto T. CXCL14-Like Immunoreactivity Exists in Somatostatin-Containing Cells of Mouse Pancreas. Acta Histochem Cytochem 2015; 48:173-8. [PMID: 26855449 PMCID: PMC4731851 DOI: 10.1267/ahc.15016] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2015] [Accepted: 09/28/2015] [Indexed: 01/11/2023] Open
Abstract
Immunohistochemical techniques were employed to investigate the distribution of the chemokine CXCL14, in the mouse pancreas. CXCL14-immunoreactive cells were detected in the peripheral region of the pancreatic islets and were immunoreactive for somatostatin, but not for glucagon, insulin, and pancreatic polypeptide. Immunoelectron microscopy indicated that the CXCL14-like peptide and somatostatin co-existed in the secretory granules. CXCL14, secreted from somatostatin-containing cells, may modulate insulin secretion in a paracrine fashion, and play a novel role in glucose homeostasis in addition to its well-known chemotactic activities.
Collapse
Affiliation(s)
| | - Toshiharu Yamamoto
- Brain Functions and Neuroscience Unit, Department of Oral Science, Graduate School of Dentistry, Kanagawa Dental University
| |
Collapse
|
18
|
Kang S, Moon NR, Kim DS, Kim SH, Park S. Central acylated ghrelin improves memory function and hippocampal AMPK activation and partly reverses the impairment of energy and glucose metabolism in rats infused with β-amyloid. Peptides 2015; 71:84-93. [PMID: 26188171 DOI: 10.1016/j.peptides.2015.07.005] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/18/2015] [Revised: 06/09/2015] [Accepted: 07/03/2015] [Indexed: 02/08/2023]
Abstract
Ghrelin is a gastric hormone released during the fasting state that targets the hypothalamus where it induces hunger; however, emerging evidence suggests it may also affect memory function. We examined the effect of central acylated-ghrelin and DES-acetylated ghrelin (native ghrelin) on memory function and glucose metabolism in an experimentally induced Alzheimer's disease (AD) rat model. AD rats were divided into 3 groups and Non-AD rats were used as a normal-control group. Each rat in the AD groups had intracerebroventricular (ICV) infusion of β-amyloid (25-35; 16.8nmol/day) into the lateral ventricle for 3 days, and then the pumps were changed to infuse either acylated-ghrelin (0.2nmol/h; AD-G), DES-acylated ghrelin (0.2nmol/h; AD-DES-G), or saline (control; AD-C) for 3 weeks. The Non-AD group had ICV infusion of β-amyloid (35-25) which does not deposit in the hippocampus. During the next 3 weeks memory function, food intake, body weight gain, body fat composition, and glucose metabolism were measured. AD-C exhibited greater β-amyloid deposition compared to Non-AD-C, and AD-G suppressed the increased β-amyloid deposition and potentiated the phosphorylation AMPK. In addition, AD-G increased the phosphorylation GSK and decreased the phosphorylation of Tau in comparison to AD-C and AD-DES-G. Cognitive function, measured by passive avoidance and water maze tests, was much lower in AD-C than Non-AD-C whereas AD-G but not AD-DES-G prevented the decrease (p<0.021). Body weight gain was lower in AD-C group than Non-AD-C group without changing epididymal fat mass. AD-G reversed the decrease in body weight which was due to increased energy intake and decreased energy expenditure. The AD-G group exhibited a decrease in the second part of serum glucose levels during an oral glucose tolerance test (OGTT) compared to the AD-C and AD-DES-G group (p<0.009). However, area under the curve of insulin during the first part of OGTT was higher in AD-DES-G than other groups, whereas during the second part it was suppressed in AD-G as much as Non-AD. In conclusion, central acylated ghrelin in rats prevented the deterioration of memory function, and energy and glucose metabolisms were partially improved, possibly due to less β-amyloid accumulation. This research suggests that interventions such as intermittent fasting to facilitate sustained elevations of acyl-ghrelin should be investigated for cognitive and metabolic benefits, especially in person with early symptoms of memory impairment.
Collapse
Affiliation(s)
- Suna Kang
- Food & Nutrition, Obesity/Diabetes Center, Hoseo University, Asan, Republic of Korea
| | - Na Rang Moon
- Food & Nutrition, Obesity/Diabetes Center, Hoseo University, Asan, Republic of Korea
| | - Da Sol Kim
- Food & Nutrition, Obesity/Diabetes Center, Hoseo University, Asan, Republic of Korea
| | - Sung Hoon Kim
- Division of Endocrinology & Metabolism, Cheil General Hospital & Women's Healthcare Center, Dankook University College of Medicine, Seoul, Republic of Korea
| | - Sunmin Park
- Food & Nutrition, Obesity/Diabetes Center, Hoseo University, Asan, Republic of Korea.
| |
Collapse
|
19
|
Heppner KM, Tong J. Mechanisms in endocrinology: regulation of glucose metabolism by the ghrelin system: multiple players and multiple actions. Eur J Endocrinol 2014; 171:R21-32. [PMID: 24714083 DOI: 10.1530/eje-14-0183] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Ghrelin is a 28-amino acid peptide secreted mainly from the X/A-like cells of the stomach. Ghrelin is found in circulation in both des-acyl (dAG) and acyl forms (AG). Acylation is catalyzed by the enzyme ghrelin O-acyltransferase (GOAT). AG acts on the GH secretagogue receptor (GHSR) in the CNS to promote feeding and adiposity and also acts on GHSR in the pancreas to inhibit glucose-stimulated insulin secretion. These well-described actions of AG have made it a popular target for obesity and type 2 diabetes mellitus pharmacotherapies. However, despite the lack of a cognate receptor, dAG appears to have gluco-regulatory action, which adds an additional layer of complexity to ghrelin's regulation of glucose metabolism. This review discusses the current literature on the gluco-regulatory action of the ghrelin system (dAG, AG, GHSR, and GOAT) with specific emphasis aimed toward distinguishing AG vs dAG action.
Collapse
Affiliation(s)
- Kristy M Heppner
- Division of DiabetesObesity and Metabolism, Oregon National Primate Research Center, Oregon Health and Science University, Beaverton, Oregon, USA andDivision of EndocrinologyDiabetes and Metabolism, Department of Medicine, University of Cincinnati, 260 Stetson Street, Suite 4200, Cincinnati, Ohio 45219-0547, USA
| | - Jenny Tong
- Division of DiabetesObesity and Metabolism, Oregon National Primate Research Center, Oregon Health and Science University, Beaverton, Oregon, USA andDivision of EndocrinologyDiabetes and Metabolism, Department of Medicine, University of Cincinnati, 260 Stetson Street, Suite 4200, Cincinnati, Ohio 45219-0547, USA
| |
Collapse
|
20
|
Affiliation(s)
- Rocco Barazzoni
- Internal Medicine, Department of Medical, Surgical and Health Sciences, University of Trieste, Trieste, Italy
| |
Collapse
|
21
|
Chabot F, Caron A, Laplante M, St-Pierre DH. Interrelationships between ghrelin, insulin and glucose homeostasis: Physiological relevance. World J Diabetes 2014; 5:328-341. [PMID: 24936254 PMCID: PMC4058737 DOI: 10.4239/wjd.v5.i3.328] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/09/2013] [Accepted: 05/08/2014] [Indexed: 02/05/2023] Open
Abstract
Ghrelin is a 28 amino acid peptide mainly derived from the oxyntic gland of the stomach. Both acylated (AG) and unacylated (UAG) forms of ghrelin are found in the circulation. Initially, AG was considered as the only bioactive form of ghrelin. However, recent advances indicate that both AG and UAG exert distinct and common effects in organisms. Soon after its discovery, ghrelin was shown to promote appetite and adiposity in animal and human models. In response to these anabolic effects, an impressive number of elements have suggested the influence of ghrelin on the regulation of metabolic functions and the development of obesity-related disorders. However, due to the complexity of its biochemical nature and the physiological processes it governs, some of the effects of ghrelin are still debated in the literature. Evidence suggests that ghrelin influences glucose homeostasis through the modulation of insulin secretion and insulin receptor signaling. On the other hand, insulin was also shown to influence circulating levels of ghrelin. Here, we review the relationship between ghrelin and insulin and we describe the impact of this interaction on the modulation of glucose homeostasis.
Collapse
|
22
|
Gahete MD, Rincón-Fernández D, Villa-Osaba A, Hormaechea-Agulla D, Ibáñez-Costa A, Martínez-Fuentes AJ, Gracia-Navarro F, Castaño JP, Luque RM. Ghrelin gene products, receptors, and GOAT enzyme: biological and pathophysiological insight. J Endocrinol 2014; 220:R1-24. [PMID: 24194510 DOI: 10.1530/joe-13-0391] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Ghrelin is a 28-amino acid acylated hormone, highly expressed in the stomach, which binds to its cognate receptor (GHSR1a) to regulate a plethora of relevant biological processes, including food intake, energy balance, hormonal secretions, learning, inflammation, etc. However, ghrelin is, in fact, the most notorious component of a complex, intricate regulatory system comprised of a growing number of alternative peptides (e.g. obestatin, unacylated ghrelin, and In1-ghrelin, etc.), known (GHSRs) and, necessarily unknown receptors, as well as modifying enzymes (e.g. ghrelin-O-acyl-transferase), which interact among them as well as with other regulatory systems in order to tightly modulate key (patho)-physiological processes. This multiplicity of functions and versatility of the ghrelin system arise from a dual, genetic and functional, complexity. Importantly, a growing body of evidence suggests that dysregulation in some of the components of the ghrelin system can lead to or influence the development and/or progression of highly concerning pathologies such as endocrine-related tumors, inflammatory/cardiovascular diseases, and neurodegeneration, wherein these altered components could be used as diagnostic, prognostic, or therapeutic targets. In this context, the aim of this review is to integrate and comprehensively analyze the multiple components and functions of the ghrelin system described to date in order to define and understand its biological and (patho)-physiological significance.
Collapse
Affiliation(s)
- Manuel D Gahete
- Department of Cell Biology, Physiology and Immunology, Campus Universitario de Rabanales, Edificio Severo Ochoa (C6), Planta 3, University of Córdoba, 14014-Córdoba; Instituto Maimónides de Investigación Biomédica de Córdoba (IMIBIC), University of Córdoba; Reina Sofia University Hospital, Córdoba; and CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), Córdoba, Spain
| | | | | | | | | | | | | | | | | |
Collapse
|
23
|
Gu PY, Kang DM, Wang WD, Chen Y, Zhao ZH, Zheng H, Ye SD. Relevance of plasma obestatin and early arteriosclerosis in patients with type 2 diabetes mellitus. J Diabetes Res 2013; 2013:563919. [PMID: 24350300 PMCID: PMC3855972 DOI: 10.1155/2013/563919] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/22/2013] [Revised: 09/04/2013] [Accepted: 09/10/2013] [Indexed: 11/18/2022] Open
Abstract
We investigated the correlation between obestatin and metabolic parameters and carotid intima-media thickness (IMT) in plasma of patients with type 2 diabetes mellitus (T2DM). We collected 103 patients aged from 60 to 83 years (69.26 ± 5.83 years) form January, 2007 to May, 2009. All patients were divided into normal glucose tolerance (NGT), impaired glucose tolerance (IGT), and T2DM according to the oral glucose tolerance test (OGTT). We found that higher levels of fasting insulin (Fins), fasting blood glucose, 2 h OGTT glucose, homeostasis model assessment of insulin resistance (HOMA-IR), low density lipoprotein cholesterol, glycated haemoglobin, and C-reactive protein (CRP), as well as lower obestatin level and higher intima-media thickness level (IMT), existed in T2DM group compared with NGT group and IGT group (P < 0.01). Also, obestatin level was independently associated with HOMA-IR and CRP, while IMT level was independently associated with HOMA-IR, triglyceride, Fins, and obestatin (P < 0.01), based on stepwise multiple regression analysis. Therefore, we deduced that the low level of plasma obestatin might be related to early arteriosclerosis in patients with T2DM via increasing IMT level, and elevated plasma obestatin levels might protect T2DM patients against carotid atherosclerosis to some extent.
Collapse
Affiliation(s)
- Peng-ying Gu
- Department of Geriatric Medicine, Anhui Provincial Hospital Affiliated to Anhui Medical University, Hefei, Anhui 230001, China
| | - Dong-mei Kang
- Department of Geriatric Medicine, Anhui Provincial Hospital Affiliated to Anhui Medical University, Hefei, Anhui 230001, China
| | - Wei-dong Wang
- Department of Geriatric Medicine, Anhui Provincial Hospital Affiliated to Anhui Medical University, Hefei, Anhui 230001, China
| | - Yan Chen
- Department of Endocrine Laboratory, Anhui Provincial Hospital Affiliated to Anhui Medical University, Hefei, Anhui 230001, China
| | - Zhi-hong Zhao
- Department of Ultrasonic Medicine, Anhui Provincial Hospital Affiliated to Anhui Medical University, Hefei, Anhui 230001, China
| | - Hui Zheng
- Department of Clinical Laboratory, Anhui Provincial Hospital Affiliated to Anhui Medical University, Hefei, Anhui 230001, China
| | - Shan-dong Ye
- Department of Endocrinology, Anhui Provincial Hospital Affiliated to Anhui Medical University, Hefei, Anhui 230001, China
| |
Collapse
|
24
|
Gesmundo I, Gallo D, Favaro E, Ghigo E, Granata R. Obestatin: a new metabolic player in the pancreas and white adipose tissue. IUBMB Life 2013; 65:976-82. [PMID: 24217898 DOI: 10.1002/iub.1226] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2013] [Revised: 10/10/2013] [Accepted: 10/11/2013] [Indexed: 01/14/2023]
Abstract
Obestatin is a 23 amino acid amidated peptide, member of the preproghrelin gene-derived peptides. Initially, obestatin was reported to exert opposite effects to those of ghrelin on food intake and body weight gain, through interaction with GPR39; however, these findings are still strongly debated and obestatin biological role remains largely unknown. Interestingly, binding of obestatin to the glucagon-like peptide 1 receptor has been recently suggested. Despite being a controversial peptide, recent findings have clearly indicated that obestatin is indeed a multifunctional peptide, exerting a variety of effects, such as stimulation of cell proliferation, survival and differentiation, influence on glucose and lipid metabolism, as well as anti-inflammatory and cardioprotective actions. Its positive effects on glucose and lipid metabolism candidate this peptide as a potential therapeutic tool in pathological conditions such as insulin resistance and diabetes.
Collapse
Affiliation(s)
- Iacopo Gesmundo
- Division of Endocrinology, Diabetology and Metabolism, Department of Medical Sciences, University of Torino, Torino, Italy
| | | | | | | | | |
Collapse
|
25
|
Amisten S, Salehi A, Rorsman P, Jones PM, Persaud SJ. An atlas and functional analysis of G-protein coupled receptors in human islets of Langerhans. Pharmacol Ther 2013; 139:359-91. [DOI: 10.1016/j.pharmthera.2013.05.004] [Citation(s) in RCA: 143] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2013] [Accepted: 05/03/2013] [Indexed: 12/17/2022]
|
26
|
Yagi T, Asakawa A, Ueda H, Miyawaki S, Inui A. The role of ghrelin in patients with functional dyspepsia and its potential clinical relevance (Review). Int J Mol Med 2013; 32:523-31. [PMID: 23778458 DOI: 10.3892/ijmm.2013.1418] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2013] [Accepted: 06/03/2013] [Indexed: 12/31/2022] Open
Abstract
Functional dyspepsia (FD) is a functional gastrointestinal disorder (FGID). According to the Rome III consensus, FD is divided into 2 subgroups: epigastric pain syndrome (EPS) and postprandial distress syndrome (PDS). Although multiple mechanisms of FD pathogenesis have been suggested, its underlying etiology and pharmacological therapy remain unclear. Ghrelin is a gut-derived peptide found in the stomach. It plays a role in the regulation of gastric motility and appetite. The ghrelin gene encodes 3 molecular forms, acyl ghrelin, des-acyl ghrelin and obestatin. Acyl ghrelin acts as an endogenous ligand for growth hormone secretagogue receptor; furthermore, it is orexigenic, with effects on food intake, energy homeostasis and gastrointestinal motility. Des-acyl ghrelin exerts an opposite effect to acyl ghrelin. Obestatin exerts an inhibitory effect on the motor activity of the antrum and duodenum in fed animals. These peptides exert differential effects on gut motility and food intake. The therapeutic potential of ghrelin has attracted attention due to its varied bioactivities. Certain studies have shown that total ghrelin levels are significantly lower in patients with FD compared with healthy volunteers and that the acyl ghrelin levels of patients with FD are higher compared with healthy volunteers. However, a recent study demonstrated that acyl ghrelin levels in patients with PDS were lower compared with healthy volunteers; the association between FD and other ghrelin family gene products also remains unclear. Although certain studies have demonstrated the beneficial effects of acyl ghrelin administration and its agonist in patients with FD, only a few clinical reports exist. Further studies are required in order to examine the effects of ghrelin on FD.
Collapse
Affiliation(s)
- Takakazu Yagi
- Department of Orthodontics and Dentofacial Orthopedics, Medical and Dental Hospital, Kagoshima University, Kagoshima 890-8544, Japan
| | | | | | | | | |
Collapse
|
27
|
Yu H, Xu G, Fan X. The effect of ghrelin on cell proliferation in small intestinal IEC-6 cells. Biomed Pharmacother 2013; 67:235-9. [DOI: 10.1016/j.biopha.2013.01.007] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2012] [Accepted: 01/24/2013] [Indexed: 11/16/2022] Open
|
28
|
|
29
|
Atalayer D, Gibson C, Konopacka A, Geliebter A. Ghrelin and eating disorders. Prog Neuropsychopharmacol Biol Psychiatry 2013; 40:70-82. [PMID: 22960103 PMCID: PMC3522761 DOI: 10.1016/j.pnpbp.2012.08.011] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/06/2012] [Revised: 08/03/2012] [Accepted: 08/19/2012] [Indexed: 12/25/2022]
Abstract
There is growing evidence supporting a multifactorial etiology that includes genetic, neurochemical, and physiological components for eating disorders above and beyond the more conventional theories based on psychological and sociocultural factors. Ghrelin is one of the key gut signals associated with appetite, and the only known circulating hormone that triggers a positive energy balance by stimulating food intake. This review summarizes recent findings and several conflicting reports on ghrelin in eating disorders. Understanding these findings and inconsistencies may help in developing new methods to prevent and treat patients with these disorders.
Collapse
Affiliation(s)
- Deniz Atalayer
- Department of Medicine, New York Obesity Research and Nutrition Center, St. Luke's-Roosevelt Hospital, New York, NY, USA.
| | - Charlisa Gibson
- Department of Medicine, New York Obesity Research and Nutrition Center, St. Luke’s-Roosevelt Hospital, New York NY, USA
| | - Alexandra Konopacka
- Department of Medicine, New York Obesity Research and Nutrition Center, St. Luke’s-Roosevelt Hospital, New York NY, USA
| | - Allan Geliebter
- Department of Medicine, New York Obesity Research and Nutrition Center, St. Luke’s-Roosevelt Hospital, New York NY, USA,Department of Psychiatry, Columbia University College of Physicians and Surgeons, New York, NY, USA,Department of Psychology, Touro College, New York, NY, USA
| |
Collapse
|
30
|
Smitka K, Papezova H, Vondra K, Hill M, Hainer V, Nedvidkova J. The role of "mixed" orexigenic and anorexigenic signals and autoantibodies reacting with appetite-regulating neuropeptides and peptides of the adipose tissue-gut-brain axis: relevance to food intake and nutritional status in patients with anorexia nervosa and bulimia nervosa. Int J Endocrinol 2013; 2013:483145. [PMID: 24106499 PMCID: PMC3782835 DOI: 10.1155/2013/483145] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/28/2013] [Accepted: 07/11/2013] [Indexed: 12/13/2022] Open
Abstract
Eating disorders such as anorexia (AN) and bulimia nervosa (BN) are characterized by abnormal eating behavior. The essential aspect of AN is that the individual refuses to maintain a minimal normal body weight. The main features of BN are binge eating and inappropriate compensatory methods to prevent weight gain. The gut-brain-adipose tissue (AT) peptides and neutralizing autoantibodies play an important role in the regulation of eating behavior and growth hormone release. The mechanisms for controlling food intake involve an interplay between gut, brain, and AT. Parasympathetic, sympathetic, and serotoninergic systems are required for communication between brain satiety centre, gut, and AT. These neuronal circuits include neuropeptides ghrelin, neuropeptide Y (NPY), peptide YY (PYY), cholecystokinin (CCK), leptin, putative anorexigen obestatin, monoamines dopamine, norepinephrine (NE), serotonin, and neutralizing autoantibodies. This extensive and detailed report reviews data that demonstrate that hunger-satiety signals play an important role in the pathogenesis of eating disorders. Neuroendocrine dysregulations of the AT-gut-brain axis peptides and neutralizing autoantibodies may result in AN and BN. The circulating autoantibodies can be purified and used as pharmacological tools in AN and BN. Further research is required to investigate the orexigenic/anorexigenic synthetic analogs and monoclonal antibodies for potential treatment of eating disorders in clinical practice.
Collapse
Affiliation(s)
- Kvido Smitka
- Institute of Endocrinology, Laboratory of Clinical and Experimental Neuroendocrinology, Narodni 8, 116 94 Prague 1, Czech Republic
| | - Hana Papezova
- Psychiatric Clinic, First Faculty of Medicine, Charles University, Ke Karlovu 11, 121 08 Prague 2, Czech Republic
| | - Karel Vondra
- Institute of Endocrinology, Laboratory of Clinical and Experimental Neuroendocrinology, Narodni 8, 116 94 Prague 1, Czech Republic
| | - Martin Hill
- Institute of Endocrinology, Laboratory of Clinical and Experimental Neuroendocrinology, Narodni 8, 116 94 Prague 1, Czech Republic
| | - Vojtech Hainer
- Institute of Endocrinology, Laboratory of Clinical and Experimental Neuroendocrinology, Narodni 8, 116 94 Prague 1, Czech Republic
| | - Jara Nedvidkova
- Institute of Endocrinology, Laboratory of Clinical and Experimental Neuroendocrinology, Narodni 8, 116 94 Prague 1, Czech Republic
- *Jara Nedvidkova:
| |
Collapse
|
31
|
Méquinion M, Langlet F, Zgheib S, Dickson S, Dehouck B, Chauveau C, Viltart O. Ghrelin: central and peripheral implications in anorexia nervosa. Front Endocrinol (Lausanne) 2013; 4:15. [PMID: 23549309 PMCID: PMC3581855 DOI: 10.3389/fendo.2013.00015] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/15/2012] [Accepted: 02/01/2013] [Indexed: 11/15/2022] Open
Abstract
Increasing clinical and therapeutic interest in the neurobiology of eating disorders reflects their dramatic impact on health. Chronic food restriction resulting in severe weight loss is a major symptom described in restrictive anorexia nervosa (AN) patients, and they also suffer from metabolic disturbances, infertility, osteopenia, and osteoporosis. Restrictive AN, mostly observed in young women, is the third largest cause of chronic illness in teenagers of industrialized countries. From a neurobiological perspective, AN-linked behaviors can be considered an adaptation that permits the endurance of reduced energy supply, involving central and/or peripheral reprograming. The severe weight loss observed in AN patients is accompanied by significant changes in hormones involved in energy balance, feeding behavior, and bone formation, all of which can be replicated in animals models. Increasing evidence suggests that AN could be an addictive behavior disorder, potentially linking defects in the reward mechanism with suppressed food intake, heightened physical activity, and mood disorder. Surprisingly, the plasma levels of ghrelin, an orexigenic hormone that drives food-motivated behavior, are increased. This increase in plasma ghrelin levels seems paradoxical in light of the restrained eating adopted by AN patients, and may rather result from an adaptation to the disease. The aim of this review is to describe the role played by ghrelin in AN focusing on its central vs. peripheral actions. In AN patients and in rodent AN models, chronic food restriction induces profound alterations in the « ghrelin » signaling that leads to the development of inappropriate behaviors like hyperactivity or addiction to food starvation and therefore a greater depletion in energy reserves. The question of a transient insensitivity to ghrelin and/or a potential metabolic reprograming is discussed in regard of new clinical treatments currently investigated.
Collapse
Affiliation(s)
- Mathieu Méquinion
- UMR INSERM 837, Development and Plasticity of Postnatal BrainLille, France
| | - Fanny Langlet
- UMR INSERM 837, Development and Plasticity of Postnatal BrainLille, France
| | - Sara Zgheib
- Pathophysiology of inflammatory of bone diseases, Université Lille Nord de France-ULCO – Lille 2Boulogne sur Mer, France
| | - Suzanne Dickson
- Department of Physiology, Institute of Neuroscience and Physiology, The Sahlgrenska Academy, University of GothenburgGothenburg, Sweden
- Department of Endocrinology, Institute of Neuroscience and Physiology, The Sahlgrenska Academy, University of GothenburgGothenburg, Sweden
| | - Bénédicte Dehouck
- UMR INSERM 837, Development and Plasticity of Postnatal BrainLille, France
- Université Lille Nord de France – Université d’ArtoisLiévin, France
| | - Christophe Chauveau
- Pathophysiology of inflammatory of bone diseases, Université Lille Nord de France-ULCO – Lille 2Boulogne sur Mer, France
| | - Odile Viltart
- UMR INSERM 837, Development and Plasticity of Postnatal BrainLille, France
- Université Lille Nord de France-USTL (Lille 1)Villeneuve d’Ascq, France
- *Correspondence: Odile Viltart, Development and Plasticity of the Postnatal Brain, Team 2, Jean-Pierre Aubert Research Center, UMR INSERM 837, Bât Biserte, 1 place de Verdun, 59,045 Lille cedex, France. e-mail:
| |
Collapse
|
32
|
Unger MM, Ekman R, Björklund AK, Karlsson G, Andersson C, Mankel K, Bohne K, Tebbe JJ, Stiasny-Kolster K, Möller JC, Mayer G, Kann PH, Oertel WH. Unimpaired postprandial pancreatic polypeptide secretion in Parkinson's disease and REM sleep behavior disorder. Mov Disord 2012; 28:529-33. [PMID: 23239509 DOI: 10.1002/mds.25246] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2012] [Revised: 08/31/2012] [Accepted: 09/10/2012] [Indexed: 11/12/2022] Open
Abstract
BACKGROUND Pancreatic polypeptide is released immediately after food ingestion. The release is operated by vagal-abdominal projections and has therefore been suggested as a test for vagal nerve integrity. Pathoanatomical and clinical studies indicate vagal dysfunction in early Parkinson's disease (PD). METHODS We assessed the postprandial secretion of pancreatic polypeptide and motilin in healthy controls (n = 18) and patients with idiopathic rapid-eye-movement sleep behavior disorder (iRBD, n = 10), a potential premotor stage of PD, as well as in drug-naive (n = 19) and treated (n = 19) PD patients. RESULTS The postprandial pancreatic polypeptide secretion showed a physiological pattern in all groups and even an enhanced response in drug-naive PD and iRBD. Motilin concentrations correlated with pancreatic polypeptide concentrations. CONCLUSIONS Postprandial pancreatic polypeptide secretion is not a suitable test for vagal nerve integrity in PD. The unimpaired pancreatic polypeptide response in iRBD and PD might be explained by partially intact vagal-abdominal projections or compensatory mechanisms substituting a defective neuronal brain-gut axis.
Collapse
Affiliation(s)
- Marcus M Unger
- Department of Neurology, Philipps-University Marburg, Marburg, Germany.
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
33
|
Boutsikou T, Briana DD, Boutsikou M, Kafalidis G, Stamati L, Baka S, Hassiakos D, Gourgiotis D, Malamitsi-Puchner A. Cord blood chemerin and obestatin levels in large for gestational age infants. J Matern Fetal Neonatal Med 2012; 26:123-6. [PMID: 22963327 DOI: 10.3109/14767058.2012.728648] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
OBJECTIVE To investigate possible alterations in cord blood levels of adipokines, chemerin and obestatin (secreted by adipose tissue and associated with later development of insulin resistance/metabolic syndrome), as well as insulin, in large for gestational age (LGA) and appropriate for gestational age (AGA) pregnancies, granted that these groups differ in body fat mass and metabolic/endocrine mechanisms. METHODS Cord blood chemerin, obestatin, and insulin concentrations were prospectively measured in 40 LGA (9 born from diabetic and 31 from nondiabetic mothers) and 40 AGA singleton full-term infants. RESULTS Cord blood chemerin concentrations were significantly higher in LGA compared with AGA neonates (b = 38.91, SE 9.29, p < 0.001). In contrast, no significant differences in obestatin concentrations were observed between groups. Insulin levels were significantly elevated as customized centiles increased (b = 0.003, SE = 0.001, p = 0.032). CONCLUSIONS Higher chemerin concentrations in LGA neonates possibly reflect the increased adipose tissue in this group. Lack of difference between the two groups in circulating levels of obestatin-possibly a sensitive marker of insulin resistance-might be due to development of metabolic disorders later in life.
Collapse
Affiliation(s)
- Theodora Boutsikou
- Neonatal Division, 2nd Department of Obstetrics and Gynecology, Athens University, Medical School, Athens, Greece
| | | | | | | | | | | | | | | | | |
Collapse
|
34
|
Asakawa A, Kato I, Inui A. Comment on Short-term effects of sleeve gastrectomy and caloric restriction on blood pressure in diet-induced obese rats. Obes Surg 2012; 22:1788-9; author reply 1786-7. [PMID: 22956252 DOI: 10.1007/s11695-012-0758-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
|
35
|
Ma X, Lin Y, Lin L, Qin G, Pereira FA, Haymond MW, Butte NF, Sun Y. Ablation of ghrelin receptor in leptin-deficient ob/ob mice has paradoxical effects on glucose homeostasis when compared with ablation of ghrelin in ob/ob mice. Am J Physiol Endocrinol Metab 2012; 303:E422-31. [PMID: 22669248 PMCID: PMC3423126 DOI: 10.1152/ajpendo.00576.2011] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The orexigenic hormone ghrelin is important in diabetes because it has an inhibitory effect on insulin secretion. Ghrelin ablation in leptin-deficient ob/ob (Ghrelin(-/-):ob/ob) mice increases insulin secretion and improves hyperglycemia. The physiologically relevant ghrelin receptor is the growth hormone secretagogue receptor (GHS-R), and GHS-R antagonists are thought to be an effective strategy for treating diabetes. However, since some of ghrelin's effects are independent of GHS-R, we have utilized genetic approaches to determine whether ghrelin's effect on insulin secretion is mediated through GHS-R and whether GHS-R antagonism indeed inhibits insulin secretion. We investigated the effects of GHS-R on glucose homeostasis in Ghsr-ablated ob/ob mice (Ghsr(-/-):ob/ob). Ghsr ablation did not rescue the hyperphagia, obesity, or insulin resistance of ob/ob mice. Surprisingly, Ghsr ablation worsened the hyperglycemia, decreased insulin, and impaired glucose tolerance. Consistently, Ghsr ablation in ob/ob mice upregulated negative β-cell regulators (such as UCP-2, SREBP-1c, ChREBP, and MIF-1) and downregulated positive β-cell regulators (such as HIF-1α, FGF-21, and PDX-1) in whole pancreas; this suggests that Ghsr ablation impairs pancreatic β-cell function in leptin deficiency. Of note, Ghsr ablation in ob/ob mice did not affect the islet size; the average islet size of Ghsr(-/-):ob/ob mice is similar to that of ob/ob mice. In summary, because Ghsr ablation in leptin deficiency impairs insulin secretion and worsens hyperglycemia, this suggests that GHS-R antagonists may actually aggravate diabetes under certain conditions. The paradoxical effects of ghrelin ablation and Ghsr ablation in ob/ob mice highlight the complexity of the ghrelin-signaling pathway.
Collapse
Affiliation(s)
- Xiaojun Ma
- US Department of Agriculture/Agricultural Research Service Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX 77030, USA
| | | | | | | | | | | | | | | |
Collapse
|
36
|
Verhulst PJ, Depoortere I. Ghrelin's second life: From appetite stimulator to glucose regulator. World J Gastroenterol 2012; 18:3183-95. [PMID: 22783041 PMCID: PMC3391754 DOI: 10.3748/wjg.v18.i25.3183] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/01/2011] [Revised: 12/01/2011] [Accepted: 01/18/2012] [Indexed: 02/06/2023] Open
Abstract
Ghrelin, a 28 amino acid peptide hormone produced by the stomach, was the first orexigenic hormone to be discovered from the periphery. The octanoyl modification at Ser3, mediated by ghrelin O-acyltransferase (GOAT), is essential for ghrelin’s biological activity. Ghrelin stimulates food intake through binding to its receptor (GRLN-R) on neurons in the arcuate nucleus of the hypothalamus. Ghrelin is widely expressed throughout the body; accordingly, it is implicated in several other physiological functions, which include growth hormone release, gastric emptying, and body weight regulation. Ghrelin and GRLN-R expression are also found in the pancreas, suggesting a local physiological role. Accordingly, several recent studies now point towards an important role for ghrelin and its receptor in the regulation of blood glucose homeostasis, which is the main focus of this review. Several mechanisms of this regulation by ghrelin have been proposed, and one possibility is through the regulation of insulin secretion. Despite some controversy, most studies suggest that ghrelin exerts an inhibitory effect on insulin secretion, resulting in increased circulating glucose levels. Ghrelin may thus be a diabetogenic factor. Obesity-related type 2 diabetes has become an increasingly important health problem, almost reaching epidemic proportions in the world; therefore, antagonists of the ghrelin-GOAT signaling pathway, which will tackle both energy- and glucose homeostasis, may be considered as promising new therapies for this disease.
Collapse
|
37
|
Obestatin and insulin in pancreas of newborn diabetic rats treated with exogenous ghrelin. Acta Histochem 2012; 114:349-57. [PMID: 21803403 DOI: 10.1016/j.acthis.2011.07.003] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2011] [Revised: 07/06/2011] [Accepted: 07/07/2011] [Indexed: 01/24/2023]
Abstract
The aim of the study was to evaluate the effect of ghrelin treatment on obestatin, insulin gene expression and biochemical parameters in the pancreas of newborn-streptozocin (STZ) diabetic rats. Rats were divided into 4 groups. Group I: control rats treated with physiological saline; group II: control rats treated with 100 μg/kg/day ghrelin; group III: two days after birth rats that received 100mg/kg STZ injected as a single dose to induce neonatal diabetes; group IV: neonatal-STZ-diabetic rats treated with ghrelin for four weeks. Sections of the pancreas were examined with immunohistochemistry for the expression of obestatin and insulin and in situ hybridization for the expression of insulin mRNA. The blood glucose levels were measured. Tissue homogenates were used for protein, glutathione, lipid peroxidation and non-enzymatic glycosylation levels and antioxidant enzyme analysis. There was a significant difference in blood glucose levels in newborn-STZ-diabetic rats compared to ghrelin treated diabetic rats at weeks 1, 2 and 4. In group IV, pancreatic non-enzymatic glycosylation and lipid peroxidation levels were decreased, however, glutathione levels and enzymatic activities were increased. Insulin peptide and mRNA (+) signals in islets of Langerhans and obestatin immunopositive cell numbers showed an increase in group IV compared to group III. These results suggest that administration of ghrelin to newborn rats may prevent effects of diabetes.
Collapse
|
38
|
Plasma ghrelin isoforms and gastric ghrelin O-acyltransferase expression are influenced by Helicobacter pylori status. Nutrition 2012; 28:967-72. [PMID: 22483414 DOI: 10.1016/j.nut.2011.11.023] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2011] [Revised: 11/21/2011] [Accepted: 11/21/2011] [Indexed: 12/14/2022]
Abstract
OBJECTIVE Helicobacter pylori is known to affect the host's nutritional status. This study was performed to elucidate the relationship between H. pylori status and the dynamics of the ghrelin system, in the context of ghrelin O-acyltransferase (GOAT) expression. METHODS We conducted a clinical study of 30 subjects focusing on the following points: 1) the effects of H. pylori infection on the concentrations of circulating ghrelin isoforms and on ghrelin and GOAT mRNA expression in the gastric mucosa, and 2) the effects of H. pylori eradication on the same parameters. RESULTS The plasma acyl-ghrelin and desacyl-ghrelin concentrations of 16 H. pylori positive participants were significantly lower than those of 14 H. pylori negative controls. The acyl-ghrelin/desacyl-ghrelin ratio was not significantly different between the H. pylori positive and H. pylori negative participants. The levels of ghrelin and GOAT mRNA in the gastric mucosa were significantly lower in the H. pylori positive participants than in the H. pylori negative controls. In 11 subjects in whom H. pylori eradication was successful, their plasma acyl-ghrelin levels tended to increase after H. pylori eradication, but the difference was not significant; however, their plasma desacyl-ghrelin levels were significantly reduced. Although gastric ghrelin mRNA expression increased significantly after H. pylori eradication, gastric GOAT mRNA expression tended to increase but was not significantly altered. CONCLUSION H. pylori status might affect the host's nutritional status through changes in the plasma levels of ghrelin isoforms and the gastric expression levels of ghrelin and GOAT mRNA.
Collapse
|
39
|
Association of obestatin, ghrelin, and inflammatory cytokines in obese patients with non-alcoholic fatty liver disease. Obes Surg 2012; 21:1750-7. [PMID: 21744131 DOI: 10.1007/s11695-011-0475-1] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
BACKGROUND Three protein products of ghrelin gene (acylated ghrelin, des-acylated ghrelin, and obestatin) are involved in appetite stimulation and suppression. Additionally, there is some evidence suggesting their involvement in metabolic and inflammatory pathways which may be implicated in the pathogenesis of non-alcoholic fatty liver disease (NAFLD). The aim of this study was to examine the relationships of ghrelin gene products in patients with NAFLD. METHODS We included 75 morbidly obese patients with biopsy-proven NAFLD (41 with histologic non-alcoholic steatohepatitis (NASH)) with clinical and laboratory data as well as frozen serum samples from the time of liver biopsy. Fasting serum was assayed for obestatin as well as acylated and des-acyl-ghrelin concentrations using ELISA. Bio-Plex inflammatory cytokine assays were used to profile expression of 17 inflammatory mediators, including IL-6, IL-7, IL-8, G-CSF, CCL2, and MIP-1β. RESULTS Patients with NASH had twofold higher concentration of des-acyl-ghrelin than patients with non-NASH (2.58 vs. 1.24 pg/ml, P < 0.02). Ghrelin concentrations in NASH patients with fibrosis stage ≥2 were almost double the concentration of NASH patients with fibrosis stage <2 (8.73 vs. 4.22 pg/ml, P < 0.04). Obestatin levels also increased with the fibrosis stage (2.54 vs. 3.46 pg/ml, P < 0.03). NAFLD patients with higher fibrosis stage had lower IL-7 concentrations (16.89 vs. 10.68 pg/ml, P = 0.014). Obestatin levels at baseline significantly correlated with rate of weight loss after bariatric surgery at various time points. CONCLUSIONS This study suggests that products of the GHRL gene may be important for the pathogenesis of NASH and fibrosis. Additional confirmatory studies are needed.
Collapse
|
40
|
Baykus Y, Gurates B, Aydin S, Celik H, Kavak B, Aksoy A, Sahin İ, Deniz R, Gungor S, Guzel SP, Minareci Y. Changes in serum obestatin, preptin and ghrelins in patients with Gestational Diabetes Mellitus. Clin Biochem 2012; 45:198-202. [DOI: 10.1016/j.clinbiochem.2011.08.1131] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2011] [Revised: 08/10/2011] [Accepted: 08/15/2011] [Indexed: 11/29/2022]
|
41
|
Heppner KM, Müller TD, Tong J, Tschöp MH. Ghrelin in the control of energy, lipid, and glucose metabolism. Methods Enzymol 2012; 514:249-60. [PMID: 22975057 DOI: 10.1016/b978-0-12-381272-8.00015-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The discovery of ghrelin as the endogenous ligand for the growth hormone secretagogue receptor (GHS-R) led to subsequent studies characterizing the endogenous action of this gastrointestinal hormone. Accordingly, exogenous administration of ghrelin was found to increase food intake and adiposity in a variety of species, including rodents, nonhuman primates, and humans. Later work supported these findings and confirmed that ghrelin acts through hypothalamic neurons to mediate its effects on energy metabolism. Ghrelin acts specifically through GHS-R to promote a positive energy balance as demonstrated by loss of ghrelin action after pharmacological blockade or genetic deletion of GHS-R. More recently, ghrelin was found to be a mediator of glucose metabolism and acts to inhibit insulin secretion from pancreatic β-cells. Together, the literature highlights a predominant role of ghrelin in regulating energy and glucose metabolism.
Collapse
Affiliation(s)
- Kristy M Heppner
- Metabolic Diseases Institute, Department of Medicine, University of Cincinnati, Cincinnati, Ohio, USA
| | | | | | | |
Collapse
|
42
|
Beléen C, Martínez-Fuentes AJ, Gracia-Navarro F. Role of SST, CORT and ghrelin and its receptors at the endocrine pancreas. Front Endocrinol (Lausanne) 2012; 3:114. [PMID: 23162532 PMCID: PMC3444847 DOI: 10.3389/fendo.2012.00114] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/10/2012] [Accepted: 09/03/2012] [Indexed: 12/21/2022] Open
Abstract
Somatostatin (SST), cortistatin (CORT), and its receptors (sst1-5), and ghrelin and its receptors (GHS-R) are two highly interrelated neuropeptide systems with a broad range of overlapping biological actions at central, cardiovascular, and immune levels among others. Besides their potent regulatory role on GH release, its endocrine actions are highlighted by SST/CORT and ghrelin influence on insulin secretion, glucose homeostasis, and insulin resistance. Interestingly, most components of these systems are expressed at the endocrine pancreas and are actively involved in the modulation of pancreatic islet function and, consequently influence glucose homeostasis. In addition, some of them also participate in islet survival and regeneration. Furthermore, under severe metabolic condition as well as in endocrine pathologies, their expression profile is severely deregulated. These findings suggest that SST/CORT and ghrelin systems could play a relevant role in pancreatic function under metabolic and endocrine pathologies. Accordingly, these systems have been therapeutically targeted for the prevention or amelioration of certain metabolic conditions (obesity) as well as for tumor growth inhibition and/or hormonal regulation in endocrine pathologies (neuroendocrine tumors). This review focuses on the interrelationship between SST/CORT and ghrelin systems and their role in severe metabolic conditions and some endocrine disorders.
Collapse
Affiliation(s)
- Chanclón Beléen
- Department of Cell Biology, Physiology and Immunology, University of CórdobaCórdoba, Spain
- Instituto Maimónides de Investigación Biomédica de CórdobaCórdoba, Spain
- Centro de Investigación Biomédica en Red Fisiopatología de la Obesidad y NutriciónCórdoba, Spain
| | - Antonio J. Martínez-Fuentes
- Department of Cell Biology, Physiology and Immunology, University of CórdobaCórdoba, Spain
- Instituto Maimónides de Investigación Biomédica de CórdobaCórdoba, Spain
- Centro de Investigación Biomédica en Red Fisiopatología de la Obesidad y NutriciónCórdoba, Spain
| | - Francisco Gracia-Navarro
- Department of Cell Biology, Physiology and Immunology, University of CórdobaCórdoba, Spain
- Instituto Maimónides de Investigación Biomédica de CórdobaCórdoba, Spain
- Centro de Investigación Biomédica en Red Fisiopatología de la Obesidad y NutriciónCórdoba, Spain
- *Correspondence: Francisco Gracia-Navarro, Department of Cell Biology, Physiology and Immunology, University of Córdoba, Campus de Rabanales, Edificio Severo-Ochoa, Planta 3, E-14014 Córdoba, Spain. e-mail:
| |
Collapse
|
43
|
Baragli A, Lanfranco F, Allasia S, Granata R, Ghigo E. Neuroendocrine and metabolic activities of ghrelin gene products. Peptides 2011; 32:2323-32. [PMID: 22056513 DOI: 10.1016/j.peptides.2011.10.024] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/06/2011] [Revised: 10/03/2011] [Accepted: 10/25/2011] [Indexed: 12/15/2022]
Abstract
Acylated ghrelin (AG) is a 28 amino acid gastric peptide a natural ligand for the growth hormone secretagogue (GHS) receptor type 1a (GHS-R1a), endowed with GH-secreting and orexigenic properties. Besides, ghrelin exerts several peripheral metabolic actions, including modulation of glucose homeostasis and stimulation of adipogenesis. Notably, AG administration causes hyperglycemia in rodents as in humans. Ghrelin pleiotropy is supported by a widespread expression of the ghrelin gene, of GHS-R1a and other unknown ghrelin binding sites. The existence of alternative receptors for AG, of several natural ligands for GHS-R1a and of acylation-independent ghrelin non-neuroendocrine activities, suggests that there might be a complex 'ghrelin system' not yet completely explored. Moreover, the patho-physiological implications of unacylated ghrelin (UAG), and obestatin (Ob), the other two ghrelin gene-derived peptides, need to be clarified. Within the next few years, we may better understand the 'ghrelin system', where we might envisage clinical applications.
Collapse
Affiliation(s)
- Alessandra Baragli
- Laboratory of Molecular and Cellular Endocrinology, Division of Endocrinology, Department of Internal Medicine, University of Turin, Turin, Italy.
| | | | | | | | | |
Collapse
|
44
|
Kang K, Zmuda E, Sleeman MW. Physiological role of ghrelin as revealed by the ghrelin and GOAT knockout mice. Peptides 2011; 32:2236-41. [PMID: 21600256 DOI: 10.1016/j.peptides.2011.04.028] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/27/2011] [Revised: 03/26/2011] [Accepted: 04/29/2011] [Indexed: 11/27/2022]
Abstract
Ghrelin is a gastric hormone that has been shown to regulate food intake and energy metabolism. One unique feature of ghrelin is that its activity is regulated post transcriptionally by ghrelin O-acyltransferase (GOAT) through the addition of fatty acid to the serine residue in the N terminal region. Despite much biochemical characterization, to date no other proteins have been shown to be specifically octonylated by GOAT, suggesting a unique matching of the acyl transferase for a single ligand, ghrelin. If this is indeed correct, then genetic deletion of ghrelin or GOAT should produce near identical phenotypes and there should be extensive overlap in expression patterns. This review summarizes the similarities and differences in the phenotypes with the genetic deletion of ghrelin and GOAT in the various knockout mouse lines reported to date. While there is considerable overlap in expression pattern between ghrelin and GOAT, the latter does exhibit some unique tissue expression that could suggest that additional peptides may be acylated and await discovery and characterization.
Collapse
Affiliation(s)
- Kihwa Kang
- Regeneron Pharmaceuticals, Inc, 777 Old Saw Mill River Road, Tarrytown, NY 10591, USA
| | | | | |
Collapse
|
45
|
Suzuki H, Yamamoto T. Ghrelin- and growth hormone secretagogue receptor-immunoreactive cells in Xenopus pancreas. ACTA ACUST UNITED AC 2011; 169:64-9. [DOI: 10.1016/j.regpep.2011.04.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2010] [Revised: 04/07/2011] [Accepted: 04/16/2011] [Indexed: 10/18/2022]
|
46
|
Chuang JC, Sakata I, Kohno D, Perello M, Osborne-Lawrence S, Repa JJ, Zigman JM. Ghrelin directly stimulates glucagon secretion from pancreatic alpha-cells. Mol Endocrinol 2011; 25:1600-11. [PMID: 21719535 DOI: 10.1210/me.2011-1001] [Citation(s) in RCA: 97] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Previous work has demonstrated that the peptide hormone ghrelin raises blood glucose. Such has been attributed to ghrelin's ability to enhance GH secretion, restrict insulin release, and/or reduce insulin sensitivity. Ghrelin's reported effects on glucagon have been inconsistent. Here, both animal- and cell-based systems were used to determine the role of glucagon in mediating ghrelin's effects on blood glucose. The tissue and cell distribution of ghrelin receptors (GHSR) was evaluated by quantitative PCR and histochemistry. Plasma glucagon levels were determined following acute acyl-ghrelin injections and in pharmacological and/or transgenic mouse models of ghrelin overexpression and GHSR deletion. Isolated mouse islets and the α-cell lines αTC1 and InR1G9 were used to evaluate ghrelin's effects on glucagon secretion and the role of calcium and ERK in this activity. GHSR mRNA was abundantly expressed in mouse islets and colocalized with glucagon in α-cells. Elevation of acyl-ghrelin acutely (after sc administration, such that physiologically relevant plasma ghrelin levels were achieved) and chronically (by slow-releasing osmotic pumps and as observed in transgenic mice harboring ghrelinomas) led to higher plasma glucagon and increased blood glucose. Conversely, genetic GHSR deletion was associated with lower plasma glucagon and reduced fasting blood glucose. Acyl-ghrelin increased glucagon secretion in a dose-dependent manner from mouse islets and α-cell lines, in a manner requiring elevation of intracellular calcium and phosphorylation of ERK. Our study shows that ghrelin's regulation of blood glucose involves direct stimulation of glucagon secretion from α-cells and introduces the ghrelin-glucagon axis as an important mechanism controlling glycemia under fasting conditions.
Collapse
Affiliation(s)
- Jen-Chieh Chuang
- Department of Internal Medicine, Division of Hypothalamic Research, University of Texas Southwestern Medical Center, Dallas, Texas 75390-9077, USA
| | | | | | | | | | | | | |
Collapse
|
47
|
Seim I, Walpole C, Amorim L, Josh P, Herington A, Chopin L. The expanding roles of the ghrelin-gene derived peptide obestatin in health and disease. Mol Cell Endocrinol 2011; 340:111-7. [PMID: 21459124 DOI: 10.1016/j.mce.2011.03.018] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/25/2011] [Revised: 03/23/2011] [Accepted: 03/25/2011] [Indexed: 01/18/2023]
Abstract
Obestatin is a 23 amino acid, ghrelin gene-derived peptide hormone produced in the stomach and a range of other tissues throughout the body. While it was initially reported that obestatin opposed the actions of ghrelin with regards to appetite and food intake, it is now clear that obestatin is not an endogenous ghrelin antagonist, but it is a multi-functional peptide hormone in its own right. In this review we will discuss the controversies associated with the discovery of obestatin and explore emerging central and peripheral roles of obestatin, which includes adipogenesis, pancreatic homeostasis and cancer.
Collapse
Affiliation(s)
- Inge Seim
- Queensland University of Technology, Queensland, Brisbane, Australia
| | | | | | | | | | | |
Collapse
|
48
|
Li JB, Asakawa A, Cheng K, Li Y, Chaolu H, Tsai M, Inui A. Biological effects of obestatin. Endocrine 2011; 39:205-11. [PMID: 21424587 DOI: 10.1007/s12020-011-9453-6] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/04/2011] [Accepted: 02/05/2011] [Indexed: 10/18/2022]
Abstract
Obestatin, a 23-amino-acid peptide, is derived from the preproghrelin precursor. Obestatin was identified in 2005 as a hormone regulating food intake and energy, and having opposite effects to those of ghrelin. However, as studies have progressed, many disputes on the physiological function of obestatin have emerged. The food intake suppressive effects of obestatin have not been replicated in many studies. Nonetheless, many biological roles of obestatin have been revealed, and obestatin is thought to be associated with a variety of biological functions such as feeding, drinking, incretion, memory, and sleep, and with neuropsychiatric manifestations. The biological effects of obestatin will be reviewed in this article.
Collapse
Affiliation(s)
- Jiang-Bo Li
- Department of Social and Behavioral Medicine, Kagoshima University Graduate School of Medical and Dental Sciences, 8-35-1 Sakuragaoka, Kagoshima, 890-8520, Japan
| | | | | | | | | | | | | |
Collapse
|
49
|
Asakawa A, Ataka K, Fujino K, Chen CY, Kato I, Fujimiya M, Inui A. Ghrelin family of peptides and gut motility. J Gastroenterol Hepatol 2011; 26 Suppl 3:73-4. [PMID: 21443714 DOI: 10.1111/j.1440-1746.2011.06638.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Acyl ghrelin, des-acyl ghrelin, and obestatin are three peptides isolated from the gastrointestinal tract and encoded by the same preproghrelin gene. Three ghrelin gene products participate in modulating appetite, adipogenesis, glucose metabolism, cell proliferation, immune, sleep, memory, anxiety, cognition, and stress. We have investigated the effects of ghrelin family of peptides on fed and fasted motor activities in the stomach and duodenum of freely moving conscious rats by manometric method. Intracerebroventricular (ICV) and intravenous (IV) administration of acyl ghrelin induced fasted motor activity in the duodenum in fed rats. ICV and IV administration of des-acyl ghrelin disrupted fasted motor activity in the antrum. Changes in gastric motility induced by IV administration of des-acyl ghrelin were antagonized by ICV administration of a corticotropin-releasing factor (CRF) 2 receptor antagonist. IV administration of obestatin decreased the percentage motor index in the antrum and prolonged the time taken to return to fasted motility in the duodenum in fed rats. ICV administration of CRF 1 and 2 receptor antagonists prevented the effects of obestatin on gastroduodenal motility. Ghrelin gene products regulate feeding-associated gastroduodenal motility. Stomach may regulate various functions including gastrointestinal motility via acyl ghrelin, des-acyl ghrelin and obestatin as an endocrine organ. Increasing knowledge of the effects of ghrelin family of peptides on gastrointestinal motility could lead to innovative new therapies for functional gastrointestinal disorders.
Collapse
Affiliation(s)
- Akihiro Asakawa
- Department of Social and Behavioral Medicine, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan.
| | | | | | | | | | | | | |
Collapse
|
50
|
Heppner KM, Tong J, Kirchner H, Nass R, Tschöp MH. The ghrelin O-acyltransferase-ghrelin system: a novel regulator of glucose metabolism. Curr Opin Endocrinol Diabetes Obes 2011; 18:50-5. [PMID: 21150588 DOI: 10.1097/med.0b013e328341e1d3] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
PURPOSE OF REVIEW Ghrelin, an orexigenic hormone secreted from the stomach, exists in the circulation in two isoforms: des-acyl and acyl ghrelin. Acylation by the enzyme ghrelin O-acyl-transferase (GOAT) enables ghrelin to activate the ghrelin receptor. This review discusses recent findings illustrating the role of acyl ghrelin, des-acyl ghrelin and GOAT in regulating glucose homeostasis. RECENT FINDINGS Recent publications support a role of ghrelin in modulating glucose homeostasis. Novel cellular mechanisms have been proposed to explain these effects. Controversy on this topic continues to exist owing to inconsistent observations made in both rodents and humans. Many recent studies are uncovering a role of des-acyl ghrelin in glucose metabolism specifically in modulating insulin sensitivity and glucose uptake into adipocytes. A novel role of ghrelin acylation by the enzyme GOAT in regulating glucose metabolism during caloric deprivation has newly been discovered. SUMMARY Ghrelin plays a role in regulating glucose homeostasis through the modulation of insulin secretion and insulin sensitivity. Acyl ghrelin and des-acyl ghrelin appear to have opposing glucoregulatory effects and regulation of acylation by the enzyme GOAT appears to play a role in mediating glucose metabolism. Modulation of GOAT or ghrelin signaling may be a clinically relevant strategy to treat metabolic diseases such as type II diabetes.
Collapse
Affiliation(s)
- Kristy M Heppner
- Department of Medicine, Metabolic Diseases Institute, University of Cincinnati, Cincinnati, Ohio, USA
| | | | | | | | | |
Collapse
|