1
|
Adams JD, Egan AM, Laurenti MC, Schembri Wismayer D, Bailey KR, Cobelli C, Dalla Man C, Vella A. Insulin secretion and action and the response of endogenous glucose production to a lack of glucagon suppression in nondiabetic subjects. Am J Physiol Endocrinol Metab 2021; 321:E728-E736. [PMID: 34658253 PMCID: PMC8782666 DOI: 10.1152/ajpendo.00284.2021] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Type 2 diabetes is a disease characterized by impaired insulin secretion and defective glucagon suppression in the postprandial period. We examined the effect of impaired glucagon suppression on glucose concentrations and endogenous glucose production (EGP) at different degrees of insulin secretory impairment. The contribution of anthropometric characteristics, peripheral, and hepatic insulin action to this variability was also examined. To do so, we studied 54 nondiabetic subjects on two occasions in which endogenous hormone secretion was inhibited by somatostatin, with glucagon infused at a rate of 0.65 ng/kg/min, at 0 min to prevent a fall in glucagon (nonsuppressed day) or at 120 min to create a transient fall in glucagon (suppressed day). Subjects received glucose (labeled with [3-3H]-glucose) infused to mimic the systemic appearance of 50-g oral glucose. Insulin was infused to mimic a prandial insulin response in 18 subjects, another 18 received 80% of the dose, and the remaining 18 received 60%. EGP was measured using the tracer-dilution technique. Decreased prandial insulin resulted in greater % increase in peak glucose but not in integrated glucose concentrations attributable to nonsuppressed glucagon. The % change in integrated EGP was unaffected by insulin dose. Multivariate regression analysis, adjusted for age, sex, weight, and insulin dose, did not show a relationship between the EGP response to impaired suppression of glucagon and insulin action as measured at the time of screening by oral glucose tolerance. A similar analysis for hepatic insulin action also did not show a relationship with the EGP response. These data indicate that the effect of impaired glucagon suppression on EGP is independent of anthropometric characteristics and insulin action.NEW & NOTEWORTHY In prediabetes, anthropometric characteristics as well as insulin action do not alter the hepatic response to glucagon. The postprandial suppression or lack of suppression of glucagon secretion is an important factor governing postprandial glucose tolerance independent of insulin secretion.
Collapse
Affiliation(s)
- Jon D Adams
- Division of Endocrinology, Diabetes & Metabolism, Mayo Clinic College of Medicine, Rochester, Minnesota
- Department of Health and Human Performance, College of Charleston, Charleston, South Carolina
| | - Aoife M Egan
- Division of Endocrinology, Diabetes & Metabolism, Mayo Clinic College of Medicine, Rochester, Minnesota
| | - Marcello C Laurenti
- Division of Endocrinology, Diabetes & Metabolism, Mayo Clinic College of Medicine, Rochester, Minnesota
| | - Daniel Schembri Wismayer
- Division of Endocrinology, Diabetes & Metabolism, Mayo Clinic College of Medicine, Rochester, Minnesota
| | - Kent R Bailey
- Division of Biomedical Statistics and Informatics, Mayo Clinic, Rochester, Minnesota
| | - Claudio Cobelli
- Department of Woman and Child's Health, University of Padova, Padova, Italy
| | - Chiara Dalla Man
- Department of Information Engineering, University of Padova, Padova, Italy
| | - Adrian Vella
- Division of Endocrinology, Diabetes & Metabolism, Mayo Clinic College of Medicine, Rochester, Minnesota
| |
Collapse
|
2
|
Ahrén B, Yamada Y, Seino Y. The mediation by GLP-1 receptors of glucagon-induced insulin secretion revisited in GLP-1 receptor knockout mice. Peptides 2021; 135:170434. [PMID: 33172827 DOI: 10.1016/j.peptides.2020.170434] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/10/2020] [Revised: 10/20/2020] [Accepted: 10/20/2020] [Indexed: 12/28/2022]
Abstract
To study whether activation of GLP-1 receptors importantly contributes to the insulinotropic action of exogenously administered glucagon, we have performed whole animal experiments in normal mice and in mice with GLP-1 receptor knockout. Glucagon (1, 3 or 10 μg/kg), the GLP-1 receptor antagonist exendin 9-39 (30 nmol/kg), glucose (0.35 g/kg) or the incretin hormone glucose-dependent insulinotropic polypeptide (GIP; 3 nmol/kg) was injected intravenously or glucose (75 mg) was given orally through gavage. Furthermore, islets were isolated and incubated in the presence of glucose with or without glucagon. It was found that the insulin response to intravenous glucagon was preserved in GLP-1 receptor knockout mice but that glucagon-induced insulin secretion was markedly suppressed in islets from GLP-1 receptor knockout mice. Similarly, the GLP-1 receptor antagonist markedly suppressed glucagon-induced insulin secretion in wildtype mice. These data suggest that GLP-1 receptors contribute to the insulinotropic action of glucagon and that there is a compensatory mechanism in GLP-1 receptor knockout mice that counteracts a reduced effect of glucagon. Two potential compensatory mechanisms (glucose and GIP) were explored. However, neither of these seemed to explain why the insulin response to glucagon is not suppressed in GLP-1 receptor knockout mice. Based on these data we confirm the hypothesis that glucagon-induced insulin secretion is partially mediated by GLP-1 receptors on the beta cells and we propose that a compensatory mechanism, the nature of which remains to be established, is induced in GLP-1 receptor knockout mice to counteract the expected impaired insulin response to glucagon in these mice.
Collapse
Affiliation(s)
- Bo Ahrén
- Department of Clinical Sciences Lund, Lund University, C11 BMC, Sölvegatan 19, 221 84 Lund, Sweden.
| | - Yuichiro Yamada
- Department of Endocrinology, Diabetes and Geriatric Medicine, Graduate School of Medicine, Akita University, Akita, Japan
| | | |
Collapse
|
3
|
Morettini M, Burattini L, Göbl C, Pacini G, Ahrén B, Tura A. Mathematical Model of Glucagon Kinetics for the Assessment of Insulin-Mediated Glucagon Inhibition During an Oral Glucose Tolerance Test. Front Endocrinol (Lausanne) 2021; 12:611147. [PMID: 33828527 PMCID: PMC8020816 DOI: 10.3389/fendo.2021.611147] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/28/2020] [Accepted: 01/26/2021] [Indexed: 01/29/2023] Open
Abstract
Glucagon is secreted from the pancreatic alpha cells and plays an important role in the maintenance of glucose homeostasis, by interacting with insulin. The plasma glucose levels determine whether glucagon secretion or insulin secretion is activated or inhibited. Despite its relevance, some aspects of glucagon secretion and kinetics remain unclear. To gain insight into this, we aimed to develop a mathematical model of the glucagon kinetics during an oral glucose tolerance test, which is sufficiently simple to be used in the clinical practice. The proposed model included two first-order differential equations -one describing glucagon and the other describing C-peptide in a compartment remote from plasma - and yielded a parameter of possible clinical relevance (i.e., SGLUCA(t), glucagon-inhibition sensitivity to glucose-induced insulin secretion). Model was validated on mean glucagon data derived from the scientific literature, yielding values for SGLUCA(t) ranging from -15.03 to 2.75 (ng of glucagon·nmol of C-peptide-1). A further validation on a total of 100 virtual subjects provided reliable results (mean residuals between -1.5 and 1.5 ng·L-1) and a negative significant linear correlation (r = -0.74, p < 0.0001, 95% CI: -0.82 - -0.64) between SGLUCA(t) and the ratio between the areas under the curve of suprabasal remote C-peptide and glucagon. Model reliability was also proven by the ability to capture different patterns in glucagon kinetics. In conclusion, the proposed model reliably reproduces glucagon kinetics and is characterized by sufficient simplicity to be possibly used in the clinical practice, for the estimation in the single individual of some glucagon-related parameters.
Collapse
Affiliation(s)
- Micaela Morettini
- Department of Information Engineering, Università Politecnica delle Marche, Ancona, Italy
- *Correspondence: Micaela Morettini,
| | - Laura Burattini
- Department of Information Engineering, Università Politecnica delle Marche, Ancona, Italy
| | - Christian Göbl
- Division of Obstetrics and Feto-Maternal Medicine, Department of Obstetrics and Gynecology, Medical University of Vienna, Vienna, Austria
| | - Giovanni Pacini
- Metabolic Unit, CNR Institute of Neuroscience, Padova, Italy
| | - Bo Ahrén
- Department of Clinical Sciences, Faculty of Medicine, Lund University, Lund, Sweden
| | - Andrea Tura
- Metabolic Unit, CNR Institute of Neuroscience, Padova, Italy
| |
Collapse
|
4
|
Hughes JW, Ustione A, Lavagnino Z, Piston DW. Regulation of islet glucagon secretion: Beyond calcium. Diabetes Obes Metab 2018; 20 Suppl 2:127-136. [PMID: 30230183 PMCID: PMC6148361 DOI: 10.1111/dom.13381] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/18/2018] [Revised: 05/03/2018] [Accepted: 05/23/2018] [Indexed: 12/19/2022]
Abstract
The islet of Langerhans plays a key role in glucose homeostasis through regulated secretion of the hormones insulin and glucagon. Islet research has focused on the insulin-secreting β-cells, even though aberrant glucagon secretion from α-cells also contributes to the aetiology of diabetes. Despite its importance, the mechanisms controlling glucagon secretion remain controversial. Proper α-cell function requires the islet milieu, where β- and δ-cells drive and constrain α-cell dynamics. The response of glucagon to glucose is similar between isolated islets and that measured in vivo, so it appears that the glucose dependence requires only islet-intrinsic factors and not input from blood flow or the nervous system. Elevated intracellular free Ca2+ is needed for α-cell exocytosis, but interpreting Ca2+ data is tricky since it is heterogeneous among α-cells at all physiological glucose levels. Total Ca2+ activity in α-cells increases slightly with glucose, so Ca2+ may serve a permissive, rather than regulatory, role in glucagon secretion. On the other hand, cAMP is a more promising candidate for controlling glucagon secretion and is itself driven by paracrine signalling from β- and δ-cells. Another pathway, juxtacrine signalling through the α-cell EphA receptors, stimulated by β-cell ephrin ligands, leads to a tonic inhibition of glucagon secretion. We discuss potential combinations of Ca2+ , cAMP, paracrine and juxtacrine factors in the regulation of glucagon secretion, focusing on recent data in the literature that might unify the field towards a quantitative understanding of α-cell function.
Collapse
Affiliation(s)
- Jing W. Hughes
- Division of Endocrinology, Metabolism, and Lipid Research, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri
| | - Alessandro Ustione
- Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, Missouri
| | - Zeno Lavagnino
- Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, Missouri
| | - David W. Piston
- Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, Missouri
| |
Collapse
|
5
|
Martinez R, Al-Jobori H, Ali AM, Adams J, Abdul-Ghani M, Triplitt C, DeFronzo RA, Cersosimo E. Endogenous Glucose Production and Hormonal Changes in Response to Canagliflozin and Liraglutide Combination Therapy. Diabetes 2018; 67:1182-1189. [PMID: 29602791 PMCID: PMC7301339 DOI: 10.2337/db17-1278] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/20/2017] [Accepted: 03/27/2018] [Indexed: 12/13/2022]
Abstract
The decrement in plasma glucose concentration with SGLT2 inhibitors (SGLT2i) is blunted by a rise in endogenous glucose production (EGP). We investigated the ability of incretin treatment to offset the EGP increase. Subjects with type 2 diabetes (n = 36) were randomized to 1) canagliflozin (CANA), 2) liraglutide (LIRA), or 3) CANA plus LIRA (CANA/LIRA). EGP was measured with [3-3H]glucose with or without drugs for 360 min. In the pretreatment studies, EGP was comparable and decreased (2.2 ± 0.1 to 1.7 ± 0.2 mg/kg ⋅ min) during a 300- to 360-min period (P < 0.01). The decrement in EGP was attenuated with CANA (2.1 ± 0.1 to 1.9 ± 0.1 mg/kg ⋅ min) and CANA/LIRA (2.2 ± 0.1 to 2.0 ± 0.1 mg/kg ⋅ min), whereas with LIRA it was the same (2.4 ± 0.2 to 1.8 ± 0.2 mg/kg ⋅ min) (all P < 0.05 vs. baseline). After CANA, the fasting plasma insulin concentration decreased (18 ± 2 to 12 ± 2 μU/mL, P < 0.05), while it remained unchanged in LIRA (18 ± 2 vs. 16 ± 2 μU/mL) and CANA/LIRA (17 ± 1 vs. 15 ± 2 μU/mL). Mean plasma glucagon did not change during the pretreatment studies from 0 to 360 min, while it increased with CANA (69 ± 3 to 78 ± 2 pg/mL, P < 0.05), decreased with LIRA (93 ± 6 to 80 ± 6 pg/mL, P < 0.05), and did not change in CANA/LIRA. LIRA prevented the insulin decline and blocked the glucagon rise observed with CANA but did not inhibit the increase in EGP. Factors other than insulin and glucagon contribute to the stimulation of EGP after CANA-induced glucosuria.
Collapse
Affiliation(s)
- Robert Martinez
- Division of Diabetes, Department of Medicine, University of Texas Health Science Center and Texas Diabetes Institute, University Health System, San Antonio, TX
| | - Hussein Al-Jobori
- Division of Diabetes, Department of Medicine, University of Texas Health Science Center and Texas Diabetes Institute, University Health System, San Antonio, TX
| | - Ali M Ali
- Division of Diabetes, Department of Medicine, University of Texas Health Science Center and Texas Diabetes Institute, University Health System, San Antonio, TX
| | - John Adams
- Division of Diabetes, Department of Medicine, University of Texas Health Science Center and Texas Diabetes Institute, University Health System, San Antonio, TX
| | - Muhammad Abdul-Ghani
- Division of Diabetes, Department of Medicine, University of Texas Health Science Center and Texas Diabetes Institute, University Health System, San Antonio, TX
| | - Curtis Triplitt
- Division of Diabetes, Department of Medicine, University of Texas Health Science Center and Texas Diabetes Institute, University Health System, San Antonio, TX
| | - Ralph A DeFronzo
- Division of Diabetes, Department of Medicine, University of Texas Health Science Center and Texas Diabetes Institute, University Health System, San Antonio, TX
| | - Eugenio Cersosimo
- Division of Diabetes, Department of Medicine, University of Texas Health Science Center and Texas Diabetes Institute, University Health System, San Antonio, TX
| |
Collapse
|
6
|
Abstract
Glucagon is a peptide hormone secreted from the pancreatic alpha cells in response to hypoglycemia but in some patients with type 2 diabetes a paradoxical hypersecretion results from the intake of glucose. In rodent, antagonizing the actions of glucagon have been shown to be effective for lowering blood glucose levels and this has recently have been solidified in patients with type 2 diabetes. Although the reported increases of liver enzymes, hyperglucagonemia, and alpha cell hyperplasia resulting from glucagon receptor antagonism may potentially limit the clinical applicability of glucagon receptor antagonists, they may serve as an instrumental toolbox for delineating the physiology of glucagon. Agonizing glucagon receptor signaling may be relevant, in particular when combined with glucagon-like peptide-1 receptor analogues in the perspective of body weight lowering therapy. Here, we will focus on new conceptual aspects of glucagon biology and how this may led to new diagnostics and treatment of metabolic diseases.
Collapse
Affiliation(s)
- Nicolai J Wewer Albrechtsen
- Department of Biomedical Sciences, Novo Nordisk Foundation Center for Basic Metabolic Research, and the Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3B, 2200, Copenhagen, Denmark.
| |
Collapse
|
7
|
Okuma H, Bouchi R, Masuda S, Takeuchi T, Murakami M, Minami I, Izumiyama H, Hashimoto K, Yoshimoto T, Ogawa Y. Suppression of Extrapancreatic Glucagon by Octreotide May Reduce the Fasting and Postprandial Glucose Levels in a Diabetic Patient after Total Pancreatectomy. Intern Med 2017; 56:3061-3066. [PMID: 28943578 PMCID: PMC5725861 DOI: 10.2169/internalmedicine.8963-17] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
A 52-year-old woman was treated with sensor augmented pump therapy after undergoing total pancreatectomy for a nonfunctional pancreatic neuroendocrine tumor (NET). The secretion of both endogenous insulin and pancreatic glucagon were completely depleted. Octreotide long acting repeatable (Oct-LAR) was administered for the treatment of liver metastasis of NET. Both the fasting and postprandial glucagon levels decreased immediately after the administration of Oct-LAR. In a continuous glucose monitoring analysis, episodes of nocturnal hypoglycemia was found to increase and an improvement of postprandial hyperglycemia was observed. This case suggests that octreotide may reduce the glucose level in both the fasting and postprandial states, in part by the suppression of extrapancreatic glucagon.
Collapse
Affiliation(s)
- Hideyuki Okuma
- Department of Molecular Endocrinology and Metabolism, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Japan
| | - Ryotaro Bouchi
- Department of Molecular Endocrinology and Metabolism, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Japan
| | - Seizaburo Masuda
- Department of Molecular Endocrinology and Metabolism, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Japan
| | - Takato Takeuchi
- Department of Molecular Endocrinology and Metabolism, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Japan
| | - Masanori Murakami
- Department of Molecular Endocrinology and Metabolism, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Japan
| | - Isao Minami
- Department of Molecular Endocrinology and Metabolism, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Japan
| | - Hajime Izumiyama
- Department of Molecular Endocrinology and Metabolism, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Japan
- Center for Medical Welfare and Liaison Services, Tokyo Medical and Dental University, Japan
| | - Koshi Hashimoto
- Department of Molecular Endocrinology and Metabolism, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Japan
- Department of Preemptive Medicine and Metabolism, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Japan
| | - Takanobu Yoshimoto
- Department of Molecular Endocrinology and Metabolism, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Japan
| | - Yoshihiro Ogawa
- Department of Molecular Endocrinology and Metabolism, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Japan
| |
Collapse
|
8
|
Huang WQ, Guo JH, Zhang XH, Yu MK, Chung YW, Ruan YC, Chan HC. Glucose-Sensitive CFTR Suppresses Glucagon Secretion by Potentiating KATP Channels in Pancreatic Islet α Cells. Endocrinology 2017; 158:3188-3199. [PMID: 28977595 DOI: 10.1210/en.2017-00282] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/24/2017] [Accepted: 07/18/2017] [Indexed: 12/14/2022]
Abstract
The secretion of glucagon by islet α cells is normally suppressed by high blood glucose, but this suppressibility is impaired in patients with diabetes or cystic fibrosis (CF), a disease caused by mutations in the gene encoding CF transmembrane conductance regulator (CFTR), a cyclic adenosine monophosphate-activated Cl- channel. However, precisely how glucose regulates glucagon release remains controversial. Here we report that elevated glucagon secretion, together with increased glucose-induced membrane depolarization and Ca2+ response, is found in CFTR mutant (DF508) mice/islets compared with the wild-type. Overexpression of CFTR in AlphaTC1-9 cells results in membrane hyperpolarization and reduced glucagon release, which can be reversed by CFTR inhibition. CFTR is found to potentiate the adenosine triphosphate-sensitive K+ (KATP) channel because membrane depolarization and whole-cell currents sensitive to KATP blockers are significantly greater in wild-type/CFTR-overexpressed α cells compared with that in DF508/non-overexpressed cells. KATP knockdown also reverses the suppressive effect of CFTR overexpression on glucagon secretion. The results reveal that by potentiating KATP channels, CFTR acts as a glucose-sensing negative regulator of glucagon secretion in α cells, a defect of which may contribute to glucose intolerance in CF and other types of diabetes.
Collapse
Affiliation(s)
- Wen Qing Huang
- Epithelial Cell Biology Research Center, School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong
| | - Jing Hui Guo
- Epithelial Cell Biology Research Center, School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong
- Department of Pathophysiology, Key Laboratory of State Administration of Traditional Chinese Medicine of the People's Republic of China, School of Medicine, Jinan University, Guangzhou 510632, People's Republic of China
| | - Xiao Hu Zhang
- Epithelial Cell Biology Research Center, School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong
- Sichuan University-The Chinese University of Hong Kong Joint Laboratory for Reproductive Medicine, Key Laboratory of Obstetric, Gynecologic and Pediatric Diseases and Birth Defects of Ministry of Education, West China Second University Hospital, Sichuan University, Chengdu 610041, People's Republic of China
| | - Mei Kuen Yu
- Epithelial Cell Biology Research Center, School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong
| | - Yiu Wa Chung
- Epithelial Cell Biology Research Center, School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong
| | - Ye Chun Ruan
- Epithelial Cell Biology Research Center, School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong
- Interdisciplinary Division of Biomedical Engineering, the Hong Kong Polytechnic University, Hong Kong, Hong Kong
| | - Hsiao Chang Chan
- Epithelial Cell Biology Research Center, School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong
- Sichuan University-The Chinese University of Hong Kong Joint Laboratory for Reproductive Medicine, Key Laboratory of Obstetric, Gynecologic and Pediatric Diseases and Birth Defects of Ministry of Education, West China Second University Hospital, Sichuan University, Chengdu 610041, People's Republic of China
| |
Collapse
|
9
|
Garg M, Ghanim H, Kuhadiya ND, Green K, Hejna J, Abuaysheh S, Torre B, Batra M, Makdissi A, Chaudhuri A, Dandona P. Liraglutide acutely suppresses glucagon, lipolysis and ketogenesis in type 1 diabetes. Diabetes Obes Metab 2017; 19:1306-1311. [PMID: 28304146 DOI: 10.1111/dom.12944] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/13/2017] [Revised: 03/13/2017] [Accepted: 03/14/2017] [Indexed: 01/17/2023]
Abstract
In view of the occurrence of diabetic ketoacidosis associated with the use of sodium-glucose transport protein-2 inhibitors in patients with type 1 diabetes (T1DM) and the relative absence of this complication in patients treated with liraglutide in spite of reductions in insulin doses, we investigated the effect of liraglutide on ketogenesis. Twenty-six patients with inadequately controlled T1DM were randomly divided into 2 groups of 13 patients each. After an overnight fast, patients were injected, subcutaneously, with either liraglutide 1.8 mg or with placebo. They were maintained on their basal insulin infusion and were followed up in our clinical research unit for 5 hours. The patients injected with placebo maintained their glucose and glucagon concentrations without an increase, but there was a significant increase in free fatty acids (FFA), acetoacetate and β-hydoxybutyrate concentrations. In contrast, liraglutide significantly reduced the increase in FFA, and totally prevented the increase in acetoacetate and β-hydroxybutyrate concentrations while suppressing glucagon and ghrelin concentrations. Thus, a single dose of liraglutide is acutely inhibitory to ketogenesis.
Collapse
Affiliation(s)
- Manisha Garg
- Division of Endocrinology, Diabetes and Metabolism, State University of New York at Buffalo, Buffalo, New York
| | - Husam Ghanim
- Division of Endocrinology, Diabetes and Metabolism, State University of New York at Buffalo, Buffalo, New York
| | - Nitesh D Kuhadiya
- Division of Endocrinology, Diabetes and Metabolism, State University of New York at Buffalo, Buffalo, New York
| | - Kelly Green
- Division of Endocrinology, Diabetes and Metabolism, State University of New York at Buffalo, Buffalo, New York
| | - Jeanne Hejna
- Division of Endocrinology, Diabetes and Metabolism, State University of New York at Buffalo, Buffalo, New York
| | - Sanaa Abuaysheh
- Division of Endocrinology, Diabetes and Metabolism, State University of New York at Buffalo, Buffalo, New York
| | - Barrett Torre
- Division of Endocrinology, Diabetes and Metabolism, State University of New York at Buffalo, Buffalo, New York
| | - Manav Batra
- Division of Endocrinology, Diabetes and Metabolism, State University of New York at Buffalo, Buffalo, New York
| | - Antoine Makdissi
- Division of Endocrinology, Diabetes and Metabolism, State University of New York at Buffalo, Buffalo, New York
| | - Ajay Chaudhuri
- Division of Endocrinology, Diabetes and Metabolism, State University of New York at Buffalo, Buffalo, New York
| | - Paresh Dandona
- Division of Endocrinology, Diabetes and Metabolism, State University of New York at Buffalo, Buffalo, New York
| |
Collapse
|
10
|
Holst JJ, Holland W, Gromada J, Lee Y, Unger RH, Yan H, Sloop KW, Kieffer TJ, Damond N, Herrera PL. Insulin and Glucagon: Partners for Life. Endocrinology 2017; 158:696-701. [PMID: 28323959 PMCID: PMC6061217 DOI: 10.1210/en.2016-1748] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/11/2016] [Accepted: 01/25/2017] [Indexed: 12/28/2022]
Abstract
In August 2016, several leaders in glucagon biology gathered for the European Association for the Study of Diabetes Hagedorn Workshop in Oxford, England. A key point of discussion focused on the need for basal insulin to allow for the therapeutic benefit of glucagon blockade in the treatment of diabetes. Among the most enlightening experimental results presented were findings from studies in which glucagon receptor-deficient mice were administered streptozotocin to destroy pancreatic β cells or had undergone diphtheria toxin-induced β cell ablation. This article summarizes key features of the discussion as a consensus was reached. Agents that antagonize glucagon may be of great benefit for the treatment of diabetes; however, sufficient levels of basal insulin are required for their therapeutic efficacy.
Collapse
Affiliation(s)
- Jens Juul Holst
- Novo Nordisk Foundation Center for Basic Metabolic Research and Department of Biomedical Sciences, Faculty of Health Sciences, University of Copenhagen, DK-2200 Copenhagen, Denmark
| | - William Holland
- Touchstone Diabetes Center, Department of Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, Texas 75390
| | | | - Young Lee
- Touchstone Diabetes Center, Department of Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, Texas 75390
| | - Roger H Unger
- Touchstone Diabetes Center, Department of Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, Texas 75390
| | - Hai Yan
- REMD Biotherapeutics Inc., Camarillo, California
| | - Kyle W Sloop
- Endocrine Discovery, Lilly Research Laboratories, Indianapolis, Indiana
| | - Timothy J Kieffer
- Department of Cellular & Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada
| | - Nicolas Damond
- Department of Genetic Medicine & Development, Faculty of Medicine, University of Geneva, CH-1211 Geneva 4, Switzerland
| | - Pedro L Herrera
- Department of Genetic Medicine & Development, Faculty of Medicine, University of Geneva, CH-1211 Geneva 4, Switzerland
| |
Collapse
|
11
|
Cao T, Yang D, Zhang X, Wang Y, Qiao Z, Gao L, Liang Y, Yu B, Zhang P. FAM3D inhibits glucagon secretion via MKP1-dependent suppression of ERK1/2 signaling. Cell Biol Toxicol 2017; 33:457-466. [PMID: 28247283 DOI: 10.1007/s10565-017-9387-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2016] [Accepted: 02/13/2017] [Indexed: 12/28/2022]
Abstract
Dysregulated glucagon secretion is a hallmark of type 2 diabetes (T2D). To date, few effective therapeutic agents target on deranged glucagon secretion. Family with sequence similarity 3 member D (FAM3D) is a novel gut-derived cytokine-like protein, and its secretion timing is contrary to that of glucagon. However, the roles of FAM3D in metabolic disorder and its biological functions are largely unknown. In the present study, we investigated whether FAM3D modulates glucagon production in mouse pancreatic alpha TC1 clone 6 (αTC1-6) cells. Glucagon secretion, prohormone convertase 2 (PC2) activity, and mitogen-activated protein kinase (MAPK) pathway were assessed. Exogenous FAM3D inhibited glucagon secretion, PC2 activity, as well as extracellular-regulated protein kinase 1/2 (ERK1/2) signaling and induced MAPK phosphatase 1 (MKP1) expression. Moreover, knockdown of MKP1 and inhibition of ERK1/2 abolished and potentiated the inhibitory effect of FAM3D on glucagon secretion, respectively. Taken together, FAM3D inhibits glucagon secretion via MKP1-dependent suppression of ERK1/2 signaling. These results provide rationale for developing the therapeutic potential of FAM3D for dysregulated glucagon secretion and T2D.
Collapse
Affiliation(s)
- Ting Cao
- Center for Medical Research and Innovation, Shanghai Pudong Hospital, Fudan University Pudong Medical Center, 2800 Gongwei Road, Pudong, Shanghai, 201399, China
| | - Dan Yang
- Center for Medical Research and Innovation, Shanghai Pudong Hospital, Fudan University Pudong Medical Center, 2800 Gongwei Road, Pudong, Shanghai, 201399, China
| | - Xiong Zhang
- Department of Surgery, Shanghai Pudong Hospital, Fudan University Pudong Medical Center, Shanghai, China
| | - Yueqian Wang
- Center for Medical Research and Innovation, Shanghai Pudong Hospital, Fudan University Pudong Medical Center, 2800 Gongwei Road, Pudong, Shanghai, 201399, China
| | - Zhengdong Qiao
- Center for Medical Research and Innovation, Shanghai Pudong Hospital, Fudan University Pudong Medical Center, 2800 Gongwei Road, Pudong, Shanghai, 201399, China
| | - Lili Gao
- Center for Medical Research and Innovation, Shanghai Pudong Hospital, Fudan University Pudong Medical Center, 2800 Gongwei Road, Pudong, Shanghai, 201399, China
| | - Yongjun Liang
- Center for Medical Research and Innovation, Shanghai Pudong Hospital, Fudan University Pudong Medical Center, 2800 Gongwei Road, Pudong, Shanghai, 201399, China
| | - Bo Yu
- Department of Surgery, Shanghai Pudong Hospital, Fudan University Pudong Medical Center, Shanghai, China.
| | - Peng Zhang
- Center for Medical Research and Innovation, Shanghai Pudong Hospital, Fudan University Pudong Medical Center, 2800 Gongwei Road, Pudong, Shanghai, 201399, China.
- Department of Surgery, Shanghai Pudong Hospital, Fudan University Pudong Medical Center, Shanghai, China.
| |
Collapse
|
12
|
Davidson JA, Holland WL, Roth MG, Wang MY, Lee Y, Yu X, McCorkle SK, Scherer PE, Unger RH. Glucagon therapeutics: Dawn of a new era for diabetes care. Diabetes Metab Res Rev 2016; 32:660-665. [PMID: 26729301 DOI: 10.1002/dmrr.2773] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/27/2015] [Accepted: 12/30/2015] [Indexed: 11/11/2022]
Abstract
Although insulin monotherapy prevents death from ketoacidosis, it does not prevent either the hyperglycemic surges or the hypoglycemic plunges of glucose levels that plague the majority of patients with type 1 diabetes. However, significant improvements have occurred with the combination of continuous insulin delivery matched by continuous glucose monitoring, but the technology is not available for all patients, requires extensive education, is expensive and moreover, while much better than standard care, it almost never reduces haemoglobin A1c (HbA1c ) to below 6%. This may indicate that an improved diabetes therapy involving antagonism of glucagon action will for the first time control glucose levels to normal and eradicate the long-term complications of diabetes. Although one can never predict that results in animals will be reproduced in humans, the available evidence suggests that patients with type 1 and type 2 diabetes may expect far superior control of the metabolic abnormalities without the need for significant monitoring of glucose, a very important but expensive part of any insulin regimen.
Collapse
Affiliation(s)
- Jaime A Davidson
- Touchstone Diabetes Centre, Department of Internal Medicine, University of Texas Southwestern Medical Centre, Dallas, TX, USA
| | - William L Holland
- Touchstone Diabetes Centre, Department of Internal Medicine, University of Texas Southwestern Medical Centre, Dallas, TX, USA
| | - Michael G Roth
- Department of Biochemistry, University of Texas Southwestern Medical Centre, Dallas, TX, USA
| | - May-Yun Wang
- Touchstone Diabetes Centre, Department of Internal Medicine, University of Texas Southwestern Medical Centre, Dallas, TX, USA
| | - Young Lee
- Touchstone Diabetes Centre, Department of Internal Medicine, University of Texas Southwestern Medical Centre, Dallas, TX, USA
| | - Xinxin Yu
- Touchstone Diabetes Centre, Department of Internal Medicine, University of Texas Southwestern Medical Centre, Dallas, TX, USA
| | | | - Philipp E Scherer
- Touchstone Diabetes Centre, Department of Internal Medicine, University of Texas Southwestern Medical Centre, Dallas, TX, USA
| | - Roger H Unger
- Touchstone Diabetes Centre, Department of Internal Medicine, University of Texas Southwestern Medical Centre, Dallas, TX, USA.
- VA North Texas Health Care System, Dallas, TX, USA.
| |
Collapse
|
13
|
Evans MR, Wei S, Posner BA, Unger RH, Roth MG. An AlphaScreen Assay for the Discovery of Synthetic Chemical Inhibitors of Glucagon Production. J Biomol Screen 2016; 21:325-32. [PMID: 26676097 PMCID: PMC5226228 DOI: 10.1177/1087057115622201] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2015] [Accepted: 11/23/2015] [Indexed: 11/15/2022]
Abstract
Glucose homeostasis is primarily controlled by two opposing hormones, insulin and glucagon, and diabetes results when insulin fails to inhibit glucagon action. Recent efforts to control glucagon in diabetes have focused on antagonizing the glucagon receptor, which is effective in lowering blood glucose levels but leads to hyperglucogonemia in rodents. An alternative strategy would be to control glucagon production with small molecules. In pursuit of this goal, we developed a homogeneous AlphaScreen assay for measuring glucagon in cell culture media and used this in a high-throughput screen to discover synthetic compounds that inhibited glucagon secretion from an alpha cell-like cell line. Some of these compounds inhibited transcription of the glucagon gene.
Collapse
Affiliation(s)
- Matthew R Evans
- Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Shuguang Wei
- Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Bruce A Posner
- Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Roger H Unger
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX, USA Department of Medical Service, Veteran's Administration North Texas Health Care System, Dallas, TX, USA
| | - Michael G Roth
- Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX, USA Touchstone Diabetes Center, University of Texas Southwestern Medical Center, Dallas, TX, USA
| |
Collapse
|
14
|
Steenberg VR, Jensen SM, Pedersen J, Madsen AN, Windeløv JA, Holst B, Quistorff B, Poulsen SS, Holst JJ. Acute disruption of glucagon secretion or action does not improve glucose tolerance in an insulin-deficient mouse model of diabetes. Diabetologia 2016; 59:363-70. [PMID: 26537124 DOI: 10.1007/s00125-015-3794-2] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/09/2015] [Accepted: 09/29/2015] [Indexed: 12/25/2022]
Abstract
AIMS/HYPOTHESIS Normal glucose metabolism depends on pancreatic secretion of insulin and glucagon. The bihormonal hypothesis states that while lack of insulin leads to glucose underutilisation, glucagon excess is the principal factor in diabetic glucose overproduction. A recent study reported that streptozotocin-treated glucagon receptor knockout mice have normal glucose tolerance. We investigated the impact of acute disruption of glucagon secretin or action in a mouse model of severe diabetes by three different approaches: (1) alpha cell elimination; (2) glucagon immunoneutralisation; and (3) glucagon receptor antagonism, in order to evaluate the effect of these on glucose tolerance. METHODS Severe diabetes was induced in transgenic and wild-type mice by streptozotocin. Glucose metabolism was investigated using OGTT in transgenic mice with the human diphtheria toxin receptor expressed in proglucagon producing cells allowing for diphtheria toxin (DT)-induced alpha cell ablation and in mice treated with either a specific high affinity glucagon antibody or a specific glucagon receptor antagonist. RESULTS Near-total alpha cell elimination was induced in transgenic mice upon DT administration and resulted in a massive decrease in pancreatic glucagon content. Oral glucose tolerance in diabetic mice was neither affected by glucagon immunoneutralisation, glucagon receptor antagonism, nor alpha cell removal, but did not deteriorate further compared with mice with intact alpha cell mass. CONCLUSIONS/INTERPRETATION Disruption of glucagon action/secretion did not improve glucose tolerance in diabetic mice. Near-total alpha cell elimination may have prevented further deterioration. Our findings support insulin lack as the major factor underlying hyperglycaemia in beta cell-deficient diabetes.
Collapse
Affiliation(s)
- Vivi R Steenberg
- Section for Translational Metabolic Physiology, Novo Nordisk Foundation Center for Basic Metabolic Research and Department of Biomedical Sciences, University of Copenhagen, Blegdamsvej 3, building 12.2, DK-2200, Copenhagen, Denmark
| | - Signe M Jensen
- Section for Translational Metabolic Physiology, Novo Nordisk Foundation Center for Basic Metabolic Research and Department of Biomedical Sciences, University of Copenhagen, Blegdamsvej 3, building 12.2, DK-2200, Copenhagen, Denmark
| | - Jens Pedersen
- Section for Translational Metabolic Physiology, Novo Nordisk Foundation Center for Basic Metabolic Research and Department of Biomedical Sciences, University of Copenhagen, Blegdamsvej 3, building 12.2, DK-2200, Copenhagen, Denmark
| | - Andreas N Madsen
- Section for Metabolic Receptology, Novo Nordisk Foundation Center for Basic Metabolic Research, University of Copenhagen, Copenhagen, Denmark
| | - Johanne A Windeløv
- Section for Translational Metabolic Physiology, Novo Nordisk Foundation Center for Basic Metabolic Research and Department of Biomedical Sciences, University of Copenhagen, Blegdamsvej 3, building 12.2, DK-2200, Copenhagen, Denmark
| | - Birgitte Holst
- Section for Metabolic Receptology, Novo Nordisk Foundation Center for Basic Metabolic Research, University of Copenhagen, Copenhagen, Denmark
| | - Bjørn Quistorff
- Section for Translational Metabolic Physiology, Novo Nordisk Foundation Center for Basic Metabolic Research and Department of Biomedical Sciences, University of Copenhagen, Blegdamsvej 3, building 12.2, DK-2200, Copenhagen, Denmark
| | - Steen S Poulsen
- Section for Translational Metabolic Physiology, Novo Nordisk Foundation Center for Basic Metabolic Research and Department of Biomedical Sciences, University of Copenhagen, Blegdamsvej 3, building 12.2, DK-2200, Copenhagen, Denmark
| | - Jens J Holst
- Section for Translational Metabolic Physiology, Novo Nordisk Foundation Center for Basic Metabolic Research and Department of Biomedical Sciences, University of Copenhagen, Blegdamsvej 3, building 12.2, DK-2200, Copenhagen, Denmark.
| |
Collapse
|
15
|
Vondra K. [Glucagon antagonists open a new way in treatment of type 2 diabetes Mellitus]. Vnitr Lek 2016; 62:661-666. [PMID: 27627094] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
UNLABELLED Excessive hepatic glucose production resulting from dysregulated glucagon secretion associated with inappropriate fasting and postprandial hyperglucagonemia is common feature in type 2 diabetes (DM2T). The effects of some currently widely used anti-diabetic agents, especially concerning metformin, GLP1 agonists and inhibitors of DPP4, comprise partial supression of glucagon secretion and/or action. Complete supression of glucagon action is recently widely investigated in experiments, and also results of phase 1 and 2 of the clinical trials are available. The experimental studies proved expected therapeutical potential of this approach. Blockade of glucagon action in diabetic animals resulted in decreased hepatic glucose production, reduction of fasting and prandial hyperglycemia, and improved glucose tolerance. On the other hand, the complete supression of glucagon action is associated with possible risk of pancreatic A-cell hyperplasia, hyperglucagonemia, increased sensitivity to the development of liver steatosis or other liver damage, higher risk of hypoglycemia and other potential side effects. Thus evaluation of safety profile must represent the high priority in the development of new molecules affecting glucagon secretion and intracellular action. A number of molecules antagonising glucagon action were prepared in recent years; some of them are already reviewed successfully in phase 2 of clinical testing; however no molecule is used in clinical practice so far. The presented article briefly sums up contemporary knowledge about glucagon dysregulation in T2DM, and gained experience with pharmacological supression of glucagon action in those patients. Anti-sense oligo-nucleotides, and monoclonal anti-bodies against glucagon and glucagon receptor are mentioned. The glucagon receptor antagonists are discussed in a greater detail as well. KEY WORDS glucagon antagonism - potential side effects - type 2 diabetes mellitus.
Collapse
|
16
|
Miuchi M, Miyagawa JI, Namba M. [Significance of the regulation of hyperglucagonemia in type 2 diabetes mellitus]. Nihon Rinsho 2015; 73:1988-1994. [PMID: 26666142] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Abstract Generally, pancreatic β-cell dysfunction and hypoinsulinemia have been known as the cause of development of hyperglycemia in diabetes mellitus. Pancreatic α-cell dysfunction, particularly hyperglucagonemia is also serious problem to increase hepatic glucose production in type 2 diabetes mellitus (T2DM). β-cell mass decrement and α-cell mass increment in T2DM have been reported in many reports inclusive of our study. Those might be the background to the pancreatic cells dysfunction in T2DM. Glucagon secretion from α-cells could not be suppressed by insufficient insulin, and hyperglucagonemia has been worsening in T2DM. Incretin, particularly glucagon like peptide-1 (GLP-1) could control both α- and β-cell dysfunction, via the decrease of glucagon and the increase of insulin respectively. We believe that incretin therapy(GLP-1 receptor agonists and DPP-4 inhibitors) is the best strategy to control hyperglucagonemia caused by α-cell dysfunction in T2DM.
Collapse
|
17
|
Lefèbvre PJ, Paquot N, Scheen AJ. Inhibiting or antagonizing glucagon: making progress in diabetes care. Diabetes Obes Metab 2015; 17:720-5. [PMID: 25924114 DOI: 10.1111/dom.12480] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/24/2015] [Revised: 04/27/2015] [Accepted: 04/27/2015] [Indexed: 01/07/2023]
Abstract
Absolute or relative hyperglucagonaemia has been recognized for years in all experimental or clinical forms of diabetes. It has been suggested that excess secretion of glucagon by the islet α cells is a direct consequence of intra-islet insulin secretory defects. Recent studies have shown that knockout of the glucagon receptor or administration of a monoclonal specific glucagon receptor antibody make insulin-deficient type 1 diabetic rodents thrive without insulin. These observations suggest that glucagon plays an essential role in the pathophysiology of diabetes and that targeting the α cell and glucagon are innovative approaches in the management of diabetes. Despite active research and identification of promising compounds, no one selective glucagon antagonist is presently used in the treatment of diabetes. Interestingly, besides insulin, several drugs used today in the management of diabetes appear to exert their effects, in part, by inhibiting glucagon secretion (glucagon-like peptide-1 receptor agonists, dipeptidyl peptidase-4 inhibitors, α-glucosidase inhibitors and, possibly, sulphonylureas) or glucagon action (metformin). The potential risks associated with total glucagon suppression include α-cell hyperplasia, increased mass of the pancreas, increased susceptibility to hepatosteatosis and hepatocellular injury and increased risk of hypoglycaemia, and these should be considered in the search and development of new compounds reducing glucagon receptor signalling. More than 40 years after its initial description, hyperglucagonaemia in diabetes can no longer be ignored or minimized, and its correction represents an attractive way to improve diabetes management.
Collapse
Affiliation(s)
- P J Lefèbvre
- Division of Diabetes, Nutrition and Metabolic Disorders, Department of Medicine, University of Liège, Liège, Belgium
| | - N Paquot
- Division of Diabetes, Nutrition and Metabolic Disorders, Department of Medicine, University of Liège, Liège, Belgium
| | - A J Scheen
- Division of Diabetes, Nutrition and Metabolic Disorders, Department of Medicine, University of Liège, Liège, Belgium
- Division of Clinical Pharmacology, Department of Medicine, University of Liège, Liège, Belgium
| |
Collapse
|
18
|
Kitamura T. [Significance of glucagon control in the diabetes treatment]. Nihon Rinsho 2015; 73:509-516. [PMID: 25812382] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Among islet cell types, much less attention has been paid to α cells than to β cells, but glucagon, the product of α cells, has been shown to play a major role in the development of hyperglycemia in T2DM. Recent clinical application of DPP4 inhibitor and GLP-1 receptor agonist gave attention to glucagon again. Furthermore, recently metformin has been also reported to suppress glucagon's function on hepatic glucose production. One of the critical issues in the glucagon research is the poor specificity of current assay systems. Our newly developed glucagon sandwich ELISA, having higher specificity than conventional systems, revealed that T2DM patients have more severe hyperglucagonemia than currently assumed. Thus, in the future diabetes treatment, we should pay more attention to plasma glucagon levels in diabetes patients.
Collapse
|
19
|
Otsuka Y, Yamaguchi S, Furukawa A, Kosuda M, Nakazaki M, Ishihara H. Addition of sitagliptin or metformin to insulin monotherapy improves blood glucose control via different effects on insulin and glucagon secretion in hyperglycemic Japanese patients with type 2 diabetes. Endocr J 2015; 62:133-43. [PMID: 25328079 DOI: 10.1507/endocrj.ej14-0148] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
This study aimed to explore the effects of the dipeptidyl peptidase-4 inhibitor sitagliptin and the biguanide metformin on the secretion of insulin and glucagon, as well as incretin levels, in Japanese subjects with type 2 diabetes mellitus poorly controlled with insulin monotherapy. This was a single-center, randomized, open-label, parallel group study, enrolling 25 subjects. Eleven patients (hemoglobin A1c [HbA1c] 8.40 ± 0.96%) and 10 patients (8.10 ± 0.54%) on insulin monotherapy completed 12-week treatment with sitagliptin (50 mg) and metformin (750 mg), respectively. Before and after treatment, each subject underwent a meal tolerance test. The plasma glucose, glucagon-like peptide-1 (GLP-1), glucose-dependent insulinotropic polypeptide (GIP), C-peptide, and glucagon responses to a meal challenge were measured. HbA1c reductions were similar in patients treated with sitagliptin (0.76 ± 0.18%) and metformin (0.77 ± 0.17%). In the sitagliptin group, glucose excursion during a meal tolerance test was reduced and accompanied by elevations in active GLP-1 and active GIP concentrations. C-peptide levels were unaltered despite reduced glucose responses, while glucagon responses were significantly suppressed (-7.93 ± 1.95% of baseline). In the metformin group, glucose excursion and incretin responses were unaltered. C-peptide levels were slightly increased but glucagon responses were unchanged. Our data indicate that sitagliptin and metformin exert different effects on islet hormone secretion in Japanese type 2 diabetic patients on insulin monotherapy. A glucagon suppressing effect of sitagliptin could be one of the factors improving blood glucose control in patients inadequately controlled with insulin therapy.
Collapse
Affiliation(s)
- Yuichiro Otsuka
- Division of Diabetes and Metabolic Diseases, Nihon University School of Medicine, Tokyo 173-8610, Japan
| | | | | | | | | | | |
Collapse
|
20
|
Tsuchimochi W, Ueno H, Yamashita E, Tsubouchi C, Sakoda H, Nakamura S, Nakazato M. Teneligliptin improves glycemic control with the reduction of postprandial insulin requirement in Japanese diabetic patients. Endocr J 2015; 62:13-20. [PMID: 25252844 DOI: 10.1507/endocrj.ej14-0393] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Teneligliptin is a novel peptidomimetic-chemotype prolylthiazolidine-based inhibitor of dipeptidyl peptidase-4 (DPP-4). The aim of this study was to evaluate the effects of teneligliptin on 24 h blood glucose control and gastrointestinal hormone responses to a meal tolerance test, and to investigate the glucose-lowering mechanisms of teneligliptin. Ten patients with type 2 diabetes mellitus (T2DM) were treated for 3 days with teneligliptin (20 mg/day). Postprandial profiles for glucose, insulin, glucagon, active glucagon-like peptide-1 (GLP-1), active glucose-dependent insulinotropic polypeptide (GIP), ghrelin, des-acyl ghrelin, and 24 h glycemic fluctuations were measured via continuous glucose monitoring for 4 days. Once daily teneligliptin administration for 3 days significantly lowered postprandial and fasting glucose levels. Significant elevations of fasting and postprandial active GLP-1 and postprandial active GIP levels were observed. Teneligliptin lowered postprandial glucose elevations, 24 h mean blood glucose levels, standard deviation of 24 h glucose levels and mean amplitude of glycemic excursions (MAGE) without hypoglycemia. Serum insulin levels in the fasting state and 30 min after a meal were similar before and after teneligliptin treatment; however significant reductions at 60 to 180 min after treatment were observed. A significant elevation in early-phase insulin secretion estimated by insulinogenic and oral disposition indices, and a significant reduction in postprandial glucagon AUC were observed. Both plasma ghrelin and des-acyl ghrelin levels were unaltered following teneligliptin treatment. Teneligliptin improved 24 h blood glucose levels by increasing active incretin levels and early-phase insulin secretion, reducing the postprandial insulin requirement, and reducing glucagon secretion. Even short-term teneligliptin treatment may offer benefits for patients with T2DM.
Collapse
Affiliation(s)
- Wakaba Tsuchimochi
- Division of Neurology, Respirology, Endocrinology and Metabolism, Department of Internal Medicine, Faculty of Medicine, University of Miyazaki, Miyazaki 889-1692, Japan
| | | | | | | | | | | | | |
Collapse
|
21
|
Berg EG. Insulin's sidekicks. Developing alternative medications for type 1 diabetes. Diabetes Forecast 2013; 66:38-40. [PMID: 24156144] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
|
22
|
Vater A, Sell S, Kaczmarek P, Maasch C, Buchner K, Pruszynska-Oszmalek E, Kolodziejski P, Purschke WG, Nowak KW, Strowski MZ, Klussmann S. A mixed mirror-image DNA/RNA aptamer inhibits glucagon and acutely improves glucose tolerance in models of type 1 and type 2 diabetes. J Biol Chem 2013; 288:21136-21147. [PMID: 23744070 PMCID: PMC3774380 DOI: 10.1074/jbc.m112.444414] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2012] [Revised: 06/04/2013] [Indexed: 11/23/2022] Open
Abstract
Excessive secretion of glucagon, a functional insulin antagonist, significantly contributes to hyperglycemia in type 1 and type 2 diabetes. Accordingly, immunoneutralization of glucagon or genetic deletion of the glucagon receptor improved glucose homeostasis in animal models of diabetes. Despite this strong evidence, agents that selectively interfere with endogenous glucagon have not been implemented in clinical practice yet. We report the discovery of mirror-image DNA-aptamers (Spiegelmer®) that bind and inhibit glucagon. The affinity of the best binding DNA oligonucleotide was remarkably increased (>25-fold) by the introduction of oxygen atoms at selected 2'-positions through deoxyribo- to ribonucleotide exchanges resulting in a mixed DNA/RNA-Spiegelmer (NOX-G15) that binds glucagon with a Kd of 3 nm. NOX-G15 shows no cross-reactivity with related peptides such as glucagon-like peptide-1, glucagon-like peptide-2, gastric-inhibitory peptide, and prepro-vasoactive intestinal peptide. In vitro, NOX-G15 inhibits glucagon-stimulated cAMP production in CHO cells overexpressing the human glucagon receptor with an IC50 of 3.4 nm. A single injection of NOX-G15 ameliorated glucose excursions in intraperitoneal glucose tolerance tests in mice with streptozotocin-induced (type 1) diabetes and in a non-genetic mouse model of type 2 diabetes. In conclusion, the data suggest NOX-G15 as a therapeutic candidate with the potential to acutely attenuate hyperglycemia in type 1 and type 2 diabetes.
Collapse
MESH Headings
- Animals
- Aptamers, Nucleotide/blood
- Aptamers, Nucleotide/pharmacokinetics
- Aptamers, Nucleotide/pharmacology
- Aptamers, Nucleotide/therapeutic use
- Blood Glucose/metabolism
- Body Weight/drug effects
- CHO Cells
- Cricetinae
- Cricetulus
- Cyclic AMP/biosynthesis
- Diabetes Mellitus, Type 1/blood
- Diabetes Mellitus, Type 1/drug therapy
- Diabetes Mellitus, Type 2/blood
- Diabetes Mellitus, Type 2/drug therapy
- Disease Models, Animal
- Fasting/blood
- Glucagon/antagonists & inhibitors
- Glucagon/metabolism
- Glucose Tolerance Test
- Humans
- Kinetics
- Male
- Mice
- Mice, Inbred BALB C
- RNA/metabolism
Collapse
Affiliation(s)
- Axel Vater
- From the NOXXON Pharma AG, Max-Dohrn-Strasse 8-10, 10589 Berlin, Germany
| | - Simone Sell
- From the NOXXON Pharma AG, Max-Dohrn-Strasse 8-10, 10589 Berlin, Germany
| | - Przemyslaw Kaczmarek
- the Department of Animal Physiology and Biochemistry, Poznan University of Life Sciences, 35 Wolynska Street, 60637 Poznan, Poland, and
| | - Christian Maasch
- From the NOXXON Pharma AG, Max-Dohrn-Strasse 8-10, 10589 Berlin, Germany
| | - Klaus Buchner
- From the NOXXON Pharma AG, Max-Dohrn-Strasse 8-10, 10589 Berlin, Germany
| | - Ewa Pruszynska-Oszmalek
- the Department of Animal Physiology and Biochemistry, Poznan University of Life Sciences, 35 Wolynska Street, 60637 Poznan, Poland, and
| | - Pawel Kolodziejski
- the Department of Animal Physiology and Biochemistry, Poznan University of Life Sciences, 35 Wolynska Street, 60637 Poznan, Poland, and
| | - Werner G Purschke
- From the NOXXON Pharma AG, Max-Dohrn-Strasse 8-10, 10589 Berlin, Germany
| | - Krzysztof W Nowak
- the Department of Animal Physiology and Biochemistry, Poznan University of Life Sciences, 35 Wolynska Street, 60637 Poznan, Poland, and
| | - Mathias Z Strowski
- the Department of Hepatology and Gastroenterology and Interdisciplinary Centre of Metabolism: Endocrinology, Diabetes and Metabolism, Charité-Universitätsmedizin Berlin, Augustenburger Platz 1, 13353 Berlin, Germany
| | - Sven Klussmann
- From the NOXXON Pharma AG, Max-Dohrn-Strasse 8-10, 10589 Berlin, Germany,.
| |
Collapse
|
23
|
|
24
|
|
25
|
|
26
|
|
27
|
|
28
|
|
29
|
Miller RA, Chu Q, Xie J, Foretz M, Viollet B, Birnbaum MJ. Biguanides suppress hepatic glucagon signalling by decreasing production of cyclic AMP. Nature 2013; 494:256-60. [PMID: 23292513 PMCID: PMC3573218 DOI: 10.1038/nature11808] [Citation(s) in RCA: 595] [Impact Index Per Article: 54.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2012] [Accepted: 11/22/2012] [Indexed: 01/19/2023]
Abstract
Glucose production by the liver is essential for providing a substrate for the brain during fasting. The inability of insulin to suppress hepatic glucose output is a major aetiological factor in the hyperglycaemia of type-2 diabetes mellitus and other diseases of insulin resistance. For fifty years, one of the few classes of therapeutics effective in reducing glucose production has been the biguanides, which include phenformin and metformin, the latter the most frequently prescribed drug for type-2 diabetes. Nonetheless, the mechanism of action of biguanides remains imperfectly understood. The suggestion a decade ago that metformin reduces glucose synthesis through activation of the enzyme AMP-activated protein kinase (AMPK) has recently been challenged by genetic loss-of-function experiments. Here we provide a novel mechanism by which metformin antagonizes the action of glucagon, thus reducing fasting glucose levels. In mouse hepatocytes, metformin leads to the accumulation of AMP and related nucleotides, which inhibit adenylate cyclase, reduce levels of cyclic AMP and protein kinase A (PKA) activity, abrogate phosphorylation of critical protein targets of PKA, and block glucagon-dependent glucose output from hepatocytes. These data support a mechanism of action for metformin involving antagonism of glucagon, and suggest an approach for the development of antidiabetic drugs.
Collapse
Affiliation(s)
- Russell A. Miller
- Institute for Diabetes, Obesity, and Metabolism, Perelman School of Medicine, University of Pennsylvania, Philadelphia PA
| | - Qingwei Chu
- Institute for Diabetes, Obesity, and Metabolism, Perelman School of Medicine, University of Pennsylvania, Philadelphia PA
| | - Jianxin Xie
- Cell Signaling Technology, Inc., 3 Trask Lane, Danvers, Massachusetts 01923
| | - Marc Foretz
- Inserm, U1016, Institut Cochin, Paris, France
- Cnrs, UMR8104, Paris, France
- Université Paris Descartes, Sorbonne Paris cité, Paris, France
| | - Benoit Viollet
- Inserm, U1016, Institut Cochin, Paris, France
- Cnrs, UMR8104, Paris, France
- Université Paris Descartes, Sorbonne Paris cité, Paris, France
| | - Morris J. Birnbaum
- Institute for Diabetes, Obesity, and Metabolism, Perelman School of Medicine, University of Pennsylvania, Philadelphia PA
| |
Collapse
|
30
|
van der Klauw MM, Wolffenbuttel BHR. The combination of insulin and GLP-1 analogues in the treatment of type 2 diabetes. Neth J Med 2012; 70:436-443. [PMID: 23230012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
GLP-1 analogues have been proven to be effective in the treatment of type 2 diabetes mellitus. They stimulate insulin production and secretion, and suppress glucagon secretion, depending on the blood glucose level. They also have an effect on the brain, enhancing satiety, and on the gut, where they delay gastric emptying. Theoretically, in type 2 diabetes mellitus patients, the combination of a GLP-1 analogue with insulin seems attractive, because of the weight loss perceived in users of GLP-1 analogues in contrast to the weight gain seen in most patients starting insulin therapy, leading to even more insulin resistance. There are only a few randomised controlled trials which have studied this combination and several uncontrolled studies, which will be reviewed here.
Collapse
Affiliation(s)
- M M van der Klauw
- Department of Endocrinology, University of Groningen, University Medical Center Groningen, Groningen, the Netherlands.
| | | |
Collapse
|
31
|
Abstract
Glucagon, a peptide hormone secreted from the α-cells of the pancreatic islets, is critical for blood glucose homeostasis. We reviewed the literature and employed a computational systems analysis of intracellular metabolic and electrical regulation of glucagon secretion to better understand these processes. The mathematical model of α-cell metabolic parameters is based on our previous model for pancreatic β-cells. We also formulated an ionic model for action potentials that incorporates Ca ( 2+) , K (+) , Na (+) and Cl (-) currents. Metabolic and ionic models are coupled to the equations describing Ca ( 2+) homeostasis and glucagon secretion that depends on activation of specific voltage-gated Ca ( 2+) channels. Paracrine and endocrine regulations were analyzed with an emphasis on their effects on a hyperpolarization of membrane potential. This general model simulates and gives insight into the mechanisms of regulation of glucagon secretion under a wide range of experimental conditions. We also reviewed and analyzed dysfunctional mechanisms in α-cells to determine key pharmacological targets for modulating glucagon secretion in type 1 and 2 diabetes.
Collapse
Affiliation(s)
- Leonid E Fridlyand
- The Kovler Diabetes Center, Departments of Medicine and Pediatrics, The University of Chicago, Chicago, IL, USA.
| | | |
Collapse
|
32
|
ThanThan S, Saito T, Yannaing S, Zhao H, Nakashima K, Kuwayama H. Glucagon-like peptide-1 inhibits insulinotropic effects of oxyntomodulin and glucagon in cattle. Domest Anim Endocrinol 2012; 42:155-64. [PMID: 22154917 DOI: 10.1016/j.domaniend.2011.11.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/18/2011] [Revised: 11/08/2011] [Accepted: 11/09/2011] [Indexed: 01/08/2023]
Abstract
Oxyntomodulin (OXM), glucagon, and glucagon-like peptide-1 (GLP-1), peptide hormones derived from the glucagon gene, play an important role in glucose homeostasis. The insulinotropic action of these three homologous peptides has been well documented in monogastric animals. However, information on the relationships among these peptides in insulin-releasing action, specifically in ruminants, is still insufficient. In this regard, we carried out two experiments in cattle. In experiment 1, effects of glucagon and GLP-1 on plasma insulin and glucose were investigated in 10-mo-old Holstein steers (347 ± 8 kg, n = 8) under normoglycemic conditions. Peptides were administered intravenously at dose rates of 0.12, 0.25, 0.50, and 1.25 nmol/kg body weight (BW). In experiment 2, the relationships among OXM, glucagon, and GLP-1 in the insulinotropic and glucoregulatory actions were elucidated in 3-mo-old Holstein steers (94 ± 2 kg, n = 8) using agonist-antagonist strategy. In agonist strategy, these three peptides were administered alone or coadministered at dose rates of 10 μg of OXM/kg BW, 4 μg of glucagon/kg BW, and 2 μg of GLP-1/kg BW. In antagonist strategy, 2 μg of each peptide was administered alone or in combination with 10 μg of [des His1, des Phe6, Glu9] glucagon amide (a glucagon receptor antagonist) or exendin-4 (5-39) amide (a GLP-1 receptor antagonist). Our results showed that OXM, glucagon, and GLP-1 had insulinotropic actions in ruminants under normoglycemic conditions. Our results also showed that the insulin-releasing effects of OXM and glucagon were mediated through both GLP-1 receptors (GLP-1R) and glucagon receptors. These insulinotropic effects of OXM and glucagon through GLP-1R were inhibited by GLP-1. Our findings expand the relationships among OXM, glucagon, and GLP-1 in the insulinotropic and glucoregulatory actions.
Collapse
Affiliation(s)
- S ThanThan
- Department of Life Science and Agriculture, Obihiro University of Agriculture and Veterinary Medicine, Inada, Obihiro 080-8555, Japan
| | | | | | | | | | | |
Collapse
|
33
|
Abstract
Glucagon is a hormone secreted from the alpha cells of the pancreatic islets. Through its effect on hepatic glucose production (HGP), glucagon plays a central role in the regulation of glucose homeostasis. In patients with type 2 diabetes mellitus (T2DM), abnormal regulation of glucagon secretion has been implicated in the development of fasting and postprandial hyperglycaemia. Therefore, new therapeutic agents based on antagonizing glucagon action, and hence blockade of glucagon-induced HGP, could be effective in lowering both fasting and postprandial hyperglycaemia in patients with T2DM. This review focuses on the mechanism of action, safety and efficacy of glucagon antagonists in the treatment of T2DM and discusses the challenges associated with this new potential antidiabetic treatment modality.
Collapse
Affiliation(s)
- J I Bagger
- Diabetes Research Division, Department of Internal Medicine F, Gentofte Hospital, University of Copenhagen, Hellerup, Denmark
| | | | | | | |
Collapse
|
34
|
Shimizu H, Tsuchiya T, Ohtani KI, Shimomura K, Oh-I S, Ariyama Y, Okada S, Kishi M, Mori M. Glucagon plays an important role in the modification of insulin secretion by leptin. Islets 2011; 3:150-4. [PMID: 21623172 DOI: 10.4161/isl.3.4.15733] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Obese people show marked hyerinsulinemia, but the exact mechanism has not been clarified. Hyperleptinemia is one of possible candidates, although there is an obvious difference in the effect of leptin on insulin secretion between isolated pancreatic islets and β-cell line. Since glucagon may modulate the effect of leptin on insulin secretion, we determined the influences of glucagon in the leptin effect on insulin secretion. The influences of glucagon in the leptin effect on insulin secretion for 10 minutes were determined by using isolated mouse islets and HIT-T 15 cells. The influences of 3-isobutyl-1- methylxanthine (IBMX), forskolin, and dibutyryl cyclic AMP were investigated in the leptin effect on insulin secretion. Leptin-inhibited insulin and glucagon secretion in isolated mouse pancreatic islets. In contrast, leptin stimulated insulin secretion in isolated mouse islets previously incubated with monoclonal anti-glucagon antibodies for 18 hours. In HIT-T 15 cells, leptin dose-dependently increased insulin secretion, but this effect was attenuated by the addition of glucagon. The stimulatory effect of leptin on insulin secretion was attenuated by 48 hour pre-incubation with glucagon. In the presence of 100 mM IBMX, leptin decreased insulin secretion from HIT-T 15 cells. Leptin also reduced insulin secretion in the presence of 1mM forskolin or 1mM dibutyryl cyclic AMP. The leptin effects on insulin secretion were affected by the existence of glucagon. Intracellular cyclic AMP concentrations may determine the leptin effects on insulin secretion in pancreatic β-cells.
Collapse
|
35
|
Johnson PM, Chen SS, Santomango TS, Williams PE, Lacy DB, McGuinness OP. Continuous low-dose fructose infusion does not reverse glucagon-mediated decrease in hepatic glucose utilization. Metabolism 2011; 60:867-73. [PMID: 20940071 PMCID: PMC3736817 DOI: 10.1016/j.metabol.2010.08.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/17/2009] [Revised: 08/18/2010] [Accepted: 08/18/2010] [Indexed: 01/04/2023]
Abstract
An adaptation to continuous total parenteral nutrition (TPN; 75% of nonprotein calories as glucose) is the liver becomes a major consumer of glucose with lactate release as a by-product. The liver is able to further increase liver glucose uptake when a small dose of fructose is acutely infused via the portal system. Glucagon, commonly elevated during inflammatory stress, is a potent inhibitor of glucose uptake by the liver during TPN. The aim was to determine if continuous fructose infusion could overcome the glucagon-mediated decrease in hepatic glucose uptake. Studies were performed in conscious, insulin-treated, chronically catheterized, pancreatectomized dogs that adapted to TPN for 33 hours. They were then assigned to 1 of 4 groups: TPN (C), TPN + fructose (4.4 μmol kg(-1) min(-1); F), TPN + glucagon (0.2 pmol kg(-1) min(-1); GGN), or TPN + fructose and glucagon (F + GGN) for an additional 63 hours (33-96 hours). Insulin, fructose, and glucagon were infused into the portal vein. During that period, all animals received a fixed insulin infusion of 0.4 mU·kg(-1)·min(-1) (33-96 hours); and the glucose infusion rates were adjusted to maintain euglycemia (6.6 mmol/L). Continuous fructose infusion was unable to further enhance net hepatic glucose uptake (in micromoles per kilogram per minute) (31.1 ± 2.8 vs 36.1 ± 5.0; C vs F), nor was it able to overcome glucagon-mediated decrease in net hepatic glucose uptake (10.0 ± 4.4 vs 12.2 ± 3.9; GGN vs F + GGN). In summary, continuous fructose infusion cannot augment liver glucose uptake during TPN; nor can it overcome the inhibitory effects of glucagon.
Collapse
Affiliation(s)
- Paulette M Johnson
- Division of Pediatric Critical Care Medicine, Vanderbilt University School of Medicine, Nashville, TN 37232-0615, USA
| | | | | | | | | | | |
Collapse
|
36
|
Asmar M, Bache M, Knop FK, Madsbad S, Holst JJ. Do the actions of glucagon-like peptide-1 on gastric emptying, appetite, and food intake involve release of amylin in humans? J Clin Endocrinol Metab 2010; 95:2367-75. [PMID: 20194711 DOI: 10.1210/jc.2009-2133] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
OBJECTIVE Amylin, cosecreted with insulin, has like glucagon-like peptide-1 (GLP-1) been reported to inhibit glucagon secretion, delay gastric emptying, and reduce appetite and food intake. We investigated whether the effects of GLP-1 on gastric emptying, appetite, and food intake are mediated directly or indirectly via release of amylin. DESIGN Eleven C-peptide and amylin-negative patients with type 1 diabetes mellitus (T1DM) and 12 matched healthy controls participated in a placebo-controlled, randomized, single-blinded, crossover study. With glucose clamped between 6 and 9 mm, near-physiological infusions of GLP-1, human amylin, pramlintide, or saline were given for 270 min during and after a fixed meal. Gastric emptying was measured using paracetamol, appetite using visual analog scales, and food intake during a subsequent ad libitum meal (at 240 min). RESULTS In T1DM, gastric emptying, food intake, and appetite were reduced equally during low GLP-1 and amylin infusion compared with the saline infusion (P < 0.05). The controls showed stronger suppression of gastric emptying (P < 0.0001) and food intake (P < 0.01) with GLP-1 compared to amylin. Postprandial glucagon responses were reduced in controls and T1DM during GLP-1 and amylin infusions (P < 0.05). Amylin and pramlintide infusion had similar effects. CONCLUSIONS GLP-1 exerts its effect on gastric emptying, appetite, food intake, and glucagon secretion directly, although secretion of amylin may contribute to some of these effects in healthy control subjects.
Collapse
Affiliation(s)
- Meena Asmar
- Department of Endocrinology, Hvidovre Hospital, DK-2650 Hvidovre, Denmark
| | | | | | | | | |
Collapse
|
37
|
Kielgast U, Asmar M, Madsbad S, Holst JJ. Effect of glucagon-like peptide-1 on alpha- and beta-cell function in C-peptide-negative type 1 diabetic patients. J Clin Endocrinol Metab 2010; 95:2492-6. [PMID: 20207828 DOI: 10.1210/jc.2009-2440] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
CONTEXT The mechanism by which glucagon-like peptide-1 (GLP-1) suppresses glucagon secretion is uncertain, and it is not determined whether endogenous insulin is a necessary factor for this effect. OBJECTIVE To characterize the alpha- and beta-cell responses to GLP-1 in type 1 diabetic patients without residual beta-cell function. METHODS Nine type 1 diabetic patients, classified as C-peptide negative by a glucagon test, were clamped at plasma glucose of 20 mmol/liter for 90 min with arginine infusion at time 45 min and concomitant infusion of GLP-1 (1.2 pmol/kg x min) or saline. RESULTS Infusion with GLP-1 increased C-peptide concentration just above the detection limit of 33 pmol/liter in one patient, but C-peptide remained immeasurable in all other patients. In the eight remaining patients, total area under the curve of glucagon was significantly decreased with GLP-1 compared with saline: 485 +/- 72 vs. 760 +/- 97 pmol/liter x min (P < 0.001). In addition, GLP-1 decreased the arginine-stimulated glucagon release (incremental AUC of 103 +/- 21 and 137 +/- 16 pmol/liter x min, with GLP-1 and saline, respectively, P < 0.05). CONCLUSIONS In type 1 diabetic patients without endogenous insulin secretion, GLP-1 decreases the glucagon secretion as well as the arginine-induced glucagon response during hyperglycemia. GLP-1 induced endogenous insulin secretion in one of nine type 1 diabetic patients previously classified as being without endogenous insulin secretion.
Collapse
Affiliation(s)
- Urd Kielgast
- Department of Biomedical Sciences, Panum Institute, University of Copenhagen, 2200 Copenhagen, Denmark.
| | | | | | | |
Collapse
|
38
|
Spellman CW. Pathophysiology of type 2 diabetes: targeting islet cell dysfunction. J Am Osteopath Assoc 2010; 110:S2-S7. [PMID: 20382838] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Type 2 diabetes mellitus (T2DM) continues to be a major health problem worldwide. It is well known that T2DM is a metabolic disorder characterized by hyperglycemia, which arises from insufficient pancreatic insulin secretion, insulin resistance in peripheral tissues, and inadequate suppression of glucagon production. This suppression results in inadequate uptake, storage, and disposal of ingested glucose accompanied by elevated hepatic production of glucose and profound hyperglycemia. Notably, these pathophysiologic processes can progress to a clinically significant degree even in patients with impaired glucose tolerance. As researchers begin to unravel the genetic basis of T2DM, the gradual accumulation of genetic polymorphisms in multiple genes-rather than the mutation of a single "diabetes gene"-appears to be the driving force behind the increase in T2DM risk. Emergent therapies for the management of T2DM include incretin-based agents, which can effectively target two key processes in T2DM by augmenting insulin secretion and inhibiting glucagon production.
Collapse
Affiliation(s)
- Craig W Spellman
- Department of Internal Medicine, Texas Tech University Health Sciences Center, Odessa, TX 79763-4206, USA.
| |
Collapse
|
39
|
Bloom SR. Signals for glucagon secretion. Ciba Found Symp 2008:161-72. [PMID: 247999 DOI: 10.1002/9780470720363.ch9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The normal physiological role of glucagon is in controlling hepatic glucose output. Glucagon subserves the role of homeostasis by maintaining plasma glucose and of a stress hormone by producing hyperglycaemia. While control of glucagon release by circulating metabolites and also other hormones is clearly important, it seems likely that the nervous system exerts an over-riding influence. The parasympathetic nervous system maintains homeostasis and the sympathetic acts in stress. Glucagon levels are found to be high in cirrhosis and also after acute hepatic failure. It is likely that these changes in glucagon concentration are secondary to metabolic abnormalities. While some glucagon is cleared by the liver, a similar clearance is seen by many other tissues and it is not likely that the elevation of glucagon seen in liver failure is due solely to a gross deficiency of glucagon clearance. No liver abnormality is seen in the glucagonoma syndrome, where glucagon concentration are chronically high, or in patients who have had a total pancreatectomy, where plasma glucagon is undetectably low. It thus seems unlikely that liver mass is importantly controlled by glucagon.
Collapse
|
40
|
Abstract
Type-2 diabetes is associated with impaired glucose clearance by the liver in the postprandial state, and with elevated glucose production in the post-absorptive state. New targets within the liver are currently being investigated for development of antihyperglycaemic drugs for type-2 diabetes. They include glucokinase, which catalyses the first step in glucose metabolism, the glucagon receptor, and enzymes of gluconeogenesis and/or glycogenolysis such as glucose 6-phosphatase, fructose 1,6-bisphosphatase and glycogen phosphorylase. Preclinical studies with candidate drugs on animal models or cell-based assays suggest that these targets have the potential for pharmacological glycaemic control. Data from clinical studies is awaited. Further work is required for better understanding of the implications of targeting these sites in terms of possible side-effects or tachyphylaxis. The advantage of combined targeting of two or more sites within the liver for minimizing side-effects and tachyphylaxis caused by single-site targeting is discussed.
Collapse
Affiliation(s)
- Loranne Agius
- Institute of Cellular Medicine, School of Clinical Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, UK.
| |
Collapse
|
41
|
Meier JJ, Deacon CF, Schmidt WE, Holst JJ, Nauck MA. Suppression of glucagon secretion is lower after oral glucose administration than during intravenous glucose administration in human subjects. Diabetologia 2007; 50:806-13. [PMID: 17334652 DOI: 10.1007/s00125-007-0598-z] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/27/2006] [Accepted: 12/27/2006] [Indexed: 01/09/2023]
Abstract
AIMS/HYPOTHESIS The incretin effect describes the augmentation of postprandial insulin secretion by gut hormones. It is not known whether glucagon secretion is also influenced by an incretin effect. A glucagon suppression deficiency has been reported in some patients with type 2 diabetes, but it is unclear whether this abnormality is present prior to diabetes onset. We therefore addressed the questions: (1) Is glucagon secretion different after oral and during intravenous glucose administration? (2) If so, is this related to the secretion of incretin hormones? (3) Is glucagon secretion abnormal in first-degree relatives of patients with type 2 diabetes? MATERIALS AND METHODS We examined 16 first-degree relatives of patients with type 2 diabetes and ten matched control subjects with an oral glucose load (75 g) and with an 'isoglycaemic' intravenous glucose infusion. RESULTS Glucagon levels were significantly suppressed by both oral and intravenous glucose (p < 0.0001), but glucagon suppression was more pronounced during intravenous glucose administration (76 +/- 2%) than after oral glucose administration (48 +/- 4%; p < 0.001). The differences in the glucagon responses to oral and i.v. glucose were correlated with the increments in gastric inhibitory polypeptide (GIP) (r = 0.60, p = 0.001) and glucagon-like peptide (GLP)-1 (r = 0.46, p < 0.05). There were no differences in glucagon levels between first-degree relatives and control subjects. CONCLUSIONS/INTERPRETATION Despite the glucagonostatic actions of GLP-1, the suppression of glucagon secretion by glucose is diminished after oral glucose ingestion, possibly due to the glucagonotropic actions of GIP and GLP-2. Furthermore, in this group of first-degree relatives, abnormalities in glucagon secretion did not precede the development of other defects, such as impaired insulin secretion.
Collapse
Affiliation(s)
- J J Meier
- Department of Medicine I, St. Josef-Hospital, Ruhr-University Bochum, Gudrunstr. 56, 44791, Bochum, Germany.
| | | | | | | | | |
Collapse
|
42
|
Abstract
AIMS/HYPOTHESIS The mechanisms by which glucose regulates glucagon release are poorly understood. The present study aimed to clarify the direct effects of glucose on the glucagon-releasing alpha cells and those effects mediated by paracrine islet factors. MATERIALS AND METHODS Glucagon, insulin and somatostatin release were measured from incubated mouse pancreatic islets and the cytoplasmic Ca(2+) concentration ([Ca(2+)](i)) recorded in isolated mouse alpha cells. RESULTS Glucose inhibited glucagon release with maximal effect at 7 mmol/l. Since this concentration corresponded to threshold stimulation of insulin secretion, it is unlikely that inhibition of glucagon secretion is mediated by beta cell factors. Although somatostatin secretion data seemed consistent with a role of this hormone in glucose-inhibited glucagon release, a somatostatin receptor type 2 antagonist stimulated glucagon release without diminishing the inhibitory effect of glucose. In islets exposed to tolbutamide plus 8 mmol/l K(+), glucose inhibited glucagon secretion without stimulating the release of insulin and somatostatin, indicating a direct inhibitory effect on the alpha cells that was independent of ATP-sensitive K(+) channels. Glucose lowered [Ca(2+)](i) of individual alpha cells independently of somatostatin and beta cell factors (insulin, Zn(2+) and gamma-aminobutyric acid). Glucose suppression of glucagon release was prevented by inhibitors of the sarco(endo)plasmic reticulum Ca(2+)-ATPase, which abolished the [Ca(2+)](i)-lowering effect of glucose on isolated alpha cells. CONCLUSIONS/INTERPRETATION Beta cell factors or somatostatin do not seem to mediate glucose inhibition of glucagon secretion. We instead propose that glucose has a direct inhibitory effect on mouse alpha cells by suppressing a depolarising Ca(2+) store-operated current.
Collapse
Affiliation(s)
- E Vieira
- Department of Medical Cell Biology, Uppsala University, BMC Box 571, SE-751 23, Uppsala, Sweden
| | | | | |
Collapse
|
43
|
Abstract
Glucagon is the key counter-regulatory hormone that opposes the action of insulin. In states of relative hypoglycaemia, glucagon acts to increase blood glucose by stimulating hepatic glycogen breakdown and gluconeogenesis to achieve euglycaemia. Type 2 diabetes is characterised by inappropriate regulation of hepatic glucose production, which is due, at least in part, to an imbalance in the bihormonal relationship between plasma levels of glucagon and insulin. The glucose-lowering effects of glucagon peptide antagonists and antiglucagon neutralising antibodies first demonstrated the potential of glucagon receptor (GCGR) antagonism as a treatment for hyperglycaemia. In recent years, the development of GCGR antisense oligonucleotides and small molecular weight GCGR antagonists have been pursued as possible therapeutic agents to target glucagon action as a treatment for Type 2 diabetes.
Collapse
Affiliation(s)
- Kyle W Sloop
- Endocrine Discovery, Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, Indiana 46285, USA.
| | | | | |
Collapse
|
44
|
Liang R, Abrardo L, Brady EJ, Candelore MR, Ding V, Saperstein R, Tota LM, Wright M, Mock S, Tamvakopolous C, Tong S, Zheng S, Zhang BB, Tata JR, Parmee ER. Design and synthesis of conformationally constrained tri-substituted ureas as potent antagonists of the human glucagon receptor. Bioorg Med Chem Lett 2006; 17:587-92. [PMID: 17126016 DOI: 10.1016/j.bmcl.2006.11.014] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2006] [Revised: 11/02/2006] [Accepted: 11/06/2006] [Indexed: 11/30/2022]
Abstract
A series of conformationally constrained tri-substituted ureas were synthesized, and their potential as glucagon receptor antagonists was evaluated. This effort resulted in the identification of compound 4a, which had a binding IC50 of 4.0 nM and was shown to reduce blood glucose levels at 3 mg/kg in glucagon-challenged mice containing a humanized glucagon receptor. Compound 4a was efficacious in correcting hyperglycemia induced by a high fat diet in transgenic mice at an oral dose as low as 3 mg/kg.
Collapse
Affiliation(s)
- Rui Liang
- Department of Basic Chemistry, Merck Research Laboratories, PO Box 2000, Rahway, NJ 07065, USA.
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
45
|
Meier JJ, Kjems LL, Veldhuis JD, Lefèbvre P, Butler PC. Postprandial suppression of glucagon secretion depends on intact pulsatile insulin secretion: further evidence for the intraislet insulin hypothesis. Diabetes 2006; 55:1051-6. [PMID: 16567528 DOI: 10.2337/diabetes.55.04.06.db05-1449] [Citation(s) in RCA: 104] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Type 2 diabetes is characterized by an approximately 60% loss of beta-cell mass, a marked defect in postprandial insulin secretion, and a failure to suppress postprandial glucagon concentrations. It is possible that postprandial hyperglucagonemia in type 2 diabetes is due to impaired postprandial insulin secretion. To address this, we studied eight adult Goettingen minipigs before and after an approximately 60% reduction in beta-cell mass induced by alloxan. Pigs were studied fasting and after ingestion of a mixed meal. Insulin and glucagon secretion were determined by deconvolution of blood hormone concentrations measured at 1-min intervals. The relationship between insulin and glucagon release was analyzed using cross-correlation and forward versus reverse cross-approximate entropy. We report that glucagon and insulin were secreted in approximately 4-min pulses. Prealloxan, postprandial insulin secretion drove an approximately 20% suppression of glucagon concentrations (P < 0.01), through inhibition of glucagon pulse mass. The alloxan-induced approximately 60% deficit in beta-cell mass lead to an approximately 70% deficit in postprandial insulin secretion and loss of the postprandial insulin-driven suppression of glucagon secretion. We conclude that postprandial hyperglucagonemia in type 2 diabetes is likely due to loss of intraislet postprandial suppression of glucagon secretion by insulin.
Collapse
Affiliation(s)
- Juris J Meier
- Larry Hillblom Islet Research Center, UCLA David Geffen School of Medicine, 24-130 Warren Hall, 900 Veteran Ave., Los Angeles, CA 90095-7073, USA
| | | | | | | | | |
Collapse
|
46
|
Hong J, Chen L, Jeppesen PB, Nordentoft I, Hermansen K. Stevioside counteracts the alpha-cell hypersecretion caused by long-term palmitate exposure. Am J Physiol Endocrinol Metab 2006; 290:E416-22. [PMID: 16204336 DOI: 10.1152/ajpendo.00331.2005] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Long-term exposure to fatty acids impairs beta-cell function in type 2 diabetes, but little is known about the chronic effects of fatty acids on alpha-cells. We therefore studied the prolonged impact of palmitate on alpha-cell function and on the expression of genes related to fuel metabolism. We also investigated whether the antihyperglycemic agent stevioside was able to counteract these effects of palmitate. Clonal alpha-TC1-6 cells were cultured with palmitate in the presence or absence of stevioside. After 72 h, we evaluated glucagon secretion, glucagon content, triglyceride (TG) content, and changes in gene expression. Glucagon secretion was dose-dependently increased after 72-h culture, with palmitate at concentrations >or=0.25 mM (P< 0.05). Palmitate (0.5 mM) enhanced TG content of alpha-cells by 73% (P< 0.01). Interestingly, stevioside (10(-8) and 10(-6) M) reduced palmitate-stimulated glucagon release by 22 and 45%, respectively (P< 0.01). There was no significant change in glucagon content after 72-h culture with palmitate and/or stevioside. Palmitate increased carnitine palmitoyltransferase I (CPT I) mRNA level, whereas stevioside enhanced CPT I, peroxisome proliferator-activated receptor-gamma, and stearoyl-CoA desaturase gene expressions in the presence of palmitate (P<0.05). In conclusion, long-term exposure to elevated fatty acids leads to a hypersecretion of glucagon and an accumulation of TG content in clonal alpha-TC1-6 cells. Stevioside was able to counteract the alpha-cell hypersecretion caused by palmitate and enhanced the expression of genes involved in fatty acid metabolism. This indicates that stevioside may be a promising antidiabetic agent in treatment of type 2 diabetes.
Collapse
Affiliation(s)
- J Hong
- Department of Endocrinology and Metabolism, Aarhus University Hospital, Odense, Denmark
| | | | | | | | | |
Collapse
|
47
|
Xu E, Kumar M, Zhang Y, Ju W, Obata T, Zhang N, Liu S, Wendt A, Deng S, Ebina Y, Wheeler MB, Braun M, Wang Q. Intra-islet insulin suppresses glucagon release via GABA-GABAA receptor system. Cell Metab 2006; 3:47-58. [PMID: 16399504 DOI: 10.1016/j.cmet.2005.11.015] [Citation(s) in RCA: 211] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/11/2005] [Revised: 07/05/2005] [Accepted: 11/29/2005] [Indexed: 12/12/2022]
Abstract
Excessive secretion of glucagon is a major contributor to the development of diabetic hyperglycemia. Secretion of glucagon is regulated by various nutrients, with glucose being a primary determinant of the rate of alpha cell glucagon secretion. The intra-islet action of insulin is essential to exert the effect of glucose on the alpha cells since, in the absence of insulin, glucose is not able to suppress glucagon release in vivo. However, the precise mechanism by which insulin suppresses glucagon secretion from alpha cells is unknown. In this study, we show that insulin induces activation of GABAA receptors in the alpha cells by receptor translocation via an Akt kinase-dependent pathway. This leads to membrane hyperpolarization in the alpha cells and, ultimately, suppression of glucagon secretion. We propose that defects in this pathway(s) contribute to diabetic hyperglycemia.
Collapse
Affiliation(s)
- Elaine Xu
- Department of Medicine, University of Toronto, and Division of Endocrinology and Metabolism, St. Michael's Hospital, Toronto, Ontario, Canada
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
48
|
Ikezawa Y, Yamatani K, Ohnuma H, Daimon M, Manaka H, Sasaki H. Insulin inhibits glucagon-induced glycogenolysis normally in perivenous hepatocytes of Wistar fatty rats. Diabetes Res Clin Pract 2005; 69:120-3. [PMID: 16005360 DOI: 10.1016/j.diabres.2004.12.008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/21/2004] [Revised: 08/01/2004] [Accepted: 12/16/2004] [Indexed: 10/25/2022]
Abstract
Wistar fatty (WF) rats are obese, hyperinsulinemic and hyperglycemic, and thus a model of type 2 diabetes mellitus. Since we have found that insulin specifically inhibits glucagon-induced glycogenolysis in perivenous hepatocytes (PVH) from normal rats, we examined the inhibitory effect of insulin on glucagon-induced glycogenolysis in PVH of hyperinsulinemic WF rats. Basal glucose release was 64.0+/-4.1 nmol/mgprotein/30 min from PVH of lean littermates (WL rats) and 137.0+/-19.3 nmol/mgprotein/30 min from that of WF rats (p<0.01). These were proportional to the glycogen content in PVH of WL and WF rats (56.7+/-7.2 and 131.0+/-20.3 microg/mgprotein, p<0.01), and increased to 109.0+/-8.8 and 225.8+/-17.9nmol/mgprotein/30min, respectively, with 0.1 nmol/l glucagon. When 10 nmol/l insulin was coincubated, 0.1 nmol/l glucagon-induced increase in glucose release decreased to 93.3+/-10.9 nmol/mgprotein/30 min in PVH of WL rats (p<0.01) and to 181+/-20.7 nmol/mgprotein/30 min in PVH of WF rats (p<0.01). Thus, insulin antagonized glucagon-induced glycogenolysis in PVH similarly between WL and WF rats, to 56.7+/-13.3% and to 46.1+/-7.5%, respectively. Thus, the antagonizing effect of insulin on glucagon-induced increase in glycogenolysis was preserved in PVH of hyperinsulinemic and hyperglycemic WF rats.
Collapse
Affiliation(s)
- Yoshihiro Ikezawa
- Third Department of Internal Medicine, Yamagata University School of Medicine, 2-2-2 IidaNishi, Yamagata 990-9585, Japan
| | | | | | | | | | | |
Collapse
|
49
|
Yang YY, Lin HC, Huang YT, Hou MC, Lee FY, Chang FY, Lee SD. Inhibition of glucagon improves splanchnic hyporesponse to terlipressin in cirrhotic rats with blood retention in the gastric lumen. J Hepatol 2005; 42:652-8. [PMID: 15826713 DOI: 10.1016/j.jhep.2004.11.044] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/04/2004] [Revised: 11/22/2004] [Accepted: 11/24/2004] [Indexed: 12/15/2022]
Abstract
BACKGROUND/AIMS Portal hypotensive effect of terlipressin is less effective when given during hemorrhage than in stable state. Blood retention in the stomach can induce splanchnic hyperemia which is mainly a consequence of an increased glucagon release. This study was undertaken to evaluate whether gastric blood retention contributes to the splanchnic hyporesponse to terlipressin. METHODS Plasma glucagon determination was performed under basal conditions and after intragastric blood gavage in sham-operated and cirrhotic rats. Additionally, splanchnic hemodynamic effects to terlipressin were measured in blood-gavaged cirrhotic rats with or without glucagon antiserum or octreotide infusion. Another set of air-gavaged cirrhotic rats was included for comparison. RESULTS Plasma glucagon level increased in both sham-operated and cirrhotic rats following blood gavage. Compared to air-gavaged cirrhotic rats, splanchnic hyporesponse to terlipressin was observed in cirrhotic rats receiving intragastric blood gavage. However, this splanchnic hyporesponse to terlipressin in blood-gavaged cirrhotic rats was overcome by glucagon antiserum or octreotide infusion. CONCLUSIONS Intragastric blood gavage induced an elevation of plasma glucagon level and led to a splanchnic hyporesponse to terlipressin. Glucagon antiserum or octreotide administration overcame this hyporesponse. Excessive release of circulating glucagon may be an important factor for splanchnic hyporesponse to terlipressin in cirrhotic portal hypertension during hemorrhage.
Collapse
Affiliation(s)
- Ying-Ying Yang
- Institute of Clinical Medicine, National Yang-Ming University School of Medicine, Taipei, Taiwan, ROC
| | | | | | | | | | | | | |
Collapse
|
50
|
Wallin E, Akerman ME, Palmblad J. [Targeting--a new way to identify unknown tumor markers in blood vessels]. Lakartidningen 2005; 102:551-2, 554-5. [PMID: 15786906] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
The expression of specific molecules on the surface of vascular endothelial cells in tumours might be a key to anticancer therapy with angiostatic drugs. A new method to find these molecules on tumour vessels, targeting, is presented here. Some of these tumour-specific molecules have been identified by means of so called phage libraries. They are gene-manipulated phages, where the surface is decorated with randomly generated short peptides. After intravenous injection a few of the peptides, expressed on the surface of the phage, attach to complementary structures on the endothelial cell, as a ligand attaches to its receptor. Through biopsies and immunohistochemistry the phage can be isolated and identified. The part of the DNA of the phage that codes for the peptide-sequence of importance is sequenced. This seeking for such vessel-addresses can in the future be used for diagnostic purposes and also for local tumour-treatment. It is envisioned that cytotoxic drugs can be coupled to peptides on nanoparticles and act locally, in order to minimize toxic systemic side effects.
Collapse
|