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Langhans W, Watts AG, Spector AC. The elusive cephalic phase insulin response: triggers, mechanisms, and functions. Physiol Rev 2023; 103:1423-1485. [PMID: 36422994 PMCID: PMC9942918 DOI: 10.1152/physrev.00025.2022] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2022] [Revised: 11/04/2022] [Accepted: 11/20/2022] [Indexed: 11/25/2022] Open
Abstract
The cephalic phase insulin response (CPIR) is classically defined as a head receptor-induced early release of insulin during eating that precedes a postabsorptive rise in blood glucose. Here we discuss, first, the various stimuli that elicit the CPIR and the sensory signaling pathways (sensory limb) involved; second, the efferent pathways that control the various endocrine events associated with eating (motor limb); and third, what is known about the central integrative processes linking the sensory and motor limbs. Fourth, in doing so, we identify open questions and problems with respect to the CPIR in general. Specifically, we consider test conditions that allow, or may not allow, the stimulus to reach the potentially relevant taste receptors and to trigger a CPIR. The possible significance of sweetness and palatability as crucial stimulus features and whether conditioning plays a role in the CPIR are also discussed. Moreover, we ponder the utility of the strict classical CPIR definition based on what is known about the effects of vagal motor neuron activation and thereby acetylcholine on the β-cells, together with the difficulties of the accurate assessment of insulin release. Finally, we weigh the evidence of the physiological and clinical relevance of the cephalic contribution to the release of insulin that occurs during and after a meal. These points are critical for the interpretation of the existing data, and they support a sharper focus on the role of head receptors in the overall insulin response to eating rather than relying solely on the classical CPIR definition.
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Affiliation(s)
- Wolfgang Langhans
- Physiology and Behavior Laboratory, ETH Zürich, Schwerzenbach, Switzerland
| | - Alan G Watts
- Department of Biological Sciences, USC Dornsife College of Letters, Arts and Sciences, University of Southern California, Los Angeles, California
| | - Alan C Spector
- Department of Psychology and Program in Neuroscience, Florida State University, Tallahassee, Florida
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2
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Samovski D, Jacome-Sosa M, Abumrad NA. Fatty Acid Transport and Signaling: Mechanisms and Physiological Implications. Annu Rev Physiol 2023; 85:317-337. [PMID: 36347219 DOI: 10.1146/annurev-physiol-032122-030352] [Citation(s) in RCA: 23] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Long-chain fatty acids (FAs) are components of plasma membranes and an efficient fuel source and also serve as metabolic regulators through FA signaling mediated by membrane FA receptors. Impaired tissue FA uptake has been linked to major complications of obesity, including insulin resistance, cardiovascular disease, and type 2 diabetes. Fatty acid interactions with a membrane receptor and the initiation of signaling can modify pathways related to nutrient uptake and processing, cell proliferation or differentiation, and secretion of bioactive factors. Here, we review the major membrane receptors involved in FA uptake and FA signaling. We focus on two types of membrane receptors for long-chain FAs: CD36 and the G protein-coupled FA receptors FFAR1 and FFAR4. We describe key signaling pathways and metabolic outcomes for CD36, FFAR1, and FFAR4 and highlight the parallels that provide insight into FA regulation of cell function.
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Affiliation(s)
- Dmitri Samovski
- Center for Human Nutrition, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, USA;
| | - Miriam Jacome-Sosa
- Center for Human Nutrition, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, USA;
| | - Nada A Abumrad
- Center for Human Nutrition, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, USA; .,Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, Missouri, USA
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3
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Hampton RF, Jimenez-Gonzalez M, Stanley SA. Unravelling innervation of pancreatic islets. Diabetologia 2022; 65:1069-1084. [PMID: 35348820 PMCID: PMC9205575 DOI: 10.1007/s00125-022-05691-9] [Citation(s) in RCA: 27] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/15/2021] [Accepted: 02/08/2022] [Indexed: 01/05/2023]
Abstract
The central and peripheral nervous systems play critical roles in regulating pancreatic islet function and glucose metabolism. Over the last century, in vitro and in vivo studies along with examination of human pancreas samples have revealed the structure of islet innervation, investigated the contribution of sympathetic, parasympathetic and sensory neural pathways to glucose control, and begun to determine how the structure and function of pancreatic nerves are disrupted in metabolic disease. Now, state-of-the art techniques such as 3D imaging of pancreatic innervation and targeted in vivo neuromodulation provide further insights into the anatomy and physiological roles of islet innervation. Here, we provide a summary of the published work on the anatomy of pancreatic islet innervation, its roles, and evidence for disordered islet innervation in metabolic disease. Finally, we discuss the possibilities offered by new technologies to increase our knowledge of islet innervation and its contributions to metabolic regulation.
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Affiliation(s)
- Rollie F Hampton
- Diabetes, Obesity and Metabolism Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Maria Jimenez-Gonzalez
- Diabetes, Obesity and Metabolism Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Sarah A Stanley
- Diabetes, Obesity and Metabolism Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA.
- Nash Family Department of Neuroscience and Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA.
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4
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Al-Alsheikh AS, Alabdulkader S, Johnson B, Goldstone AP, Miras AD. Effect of Obesity Surgery on Taste. Nutrients 2022; 14:866. [PMID: 35215515 PMCID: PMC8878262 DOI: 10.3390/nu14040866] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2021] [Revised: 02/07/2022] [Accepted: 02/15/2022] [Indexed: 12/03/2022] Open
Abstract
Obesity surgery is a highly efficacious treatment for obesity and its comorbidities. The underlying mechanisms of weight loss after obesity surgery are not yet fully understood. Changes to taste function could be a contributing factor. However, the pattern of change in different taste domains and among obesity surgery operations is not consistent in the literature. A systematic search was performed to identify all articles investigating gustation in human studies following bariatric procedures. A total of 3323 articles were identified after database searches, searching references and deduplication, and 17 articles were included. These articles provided evidence of changes in the sensory and reward domains of taste following obesity procedures. No study investigated the effect of obesity surgery on the physiological domain of taste. Taste detection sensitivity for sweetness increases shortly after Roux-en-Y gastric bypass. Additionally, patients have a reduced appetitive reward value to sweet stimuli. For the subgroup of patients who experience changes in their food preferences after Roux-en-Y gastric bypass or vertical sleeve gastrectomy, changes in taste function may be underlying mechanisms for changing food preferences which may lead to weight loss and its maintenance. However, data are heterogeneous; the potential effect dilutes over time and varies significantly between different procedures.
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Affiliation(s)
- Alhanouf S. Al-Alsheikh
- Department of Metabolism, Digestion and Reproduction, Imperial College London, Hammersmith Hospital, London W12 0NN, UK; (A.S.A.-A.); (S.A.); (B.J.); (A.D.M.)
- Department of Community Health Sciences, College of Applied Medical Sciences, King Saud University, Riyadh 11451, Saudi Arabia
| | - Shahd Alabdulkader
- Department of Metabolism, Digestion and Reproduction, Imperial College London, Hammersmith Hospital, London W12 0NN, UK; (A.S.A.-A.); (S.A.); (B.J.); (A.D.M.)
- Department of Health Sciences, College of Health and Rehabilitation Sciences, Princess Nourah Bint Abdulrahman University, Riyadh 84428, Saudi Arabia
| | - Brett Johnson
- Department of Metabolism, Digestion and Reproduction, Imperial College London, Hammersmith Hospital, London W12 0NN, UK; (A.S.A.-A.); (S.A.); (B.J.); (A.D.M.)
| | - Anthony P. Goldstone
- PsychoNeuroEndocrinology Research Group, Division of Psychiatry, Department of Brain Sciences, Imperial College London, Hammersmith Hospital, London W12 0NN, UK
| | - Alexander Dimitri Miras
- Department of Metabolism, Digestion and Reproduction, Imperial College London, Hammersmith Hospital, London W12 0NN, UK; (A.S.A.-A.); (S.A.); (B.J.); (A.D.M.)
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Al-Najim W, Docherty NG, le Roux CW. Food Intake and Eating Behavior After Bariatric Surgery. Physiol Rev 2018; 98:1113-1141. [PMID: 29717927 DOI: 10.1152/physrev.00021.2017] [Citation(s) in RCA: 108] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Obesity is an escalating global chronic disease. Bariatric surgery is a very efficacious treatment for obesity and its comorbidities. Alterations to gastrointestinal anatomy during bariatric surgery result in neurological and physiological changes affecting hypothalamic signaling, gut hormones, bile acids, and gut microbiota, which coalesce to exert a profound influence on eating behavior. A thorough understanding of the mechanisms underlying eating behavior is essential in the management of patients after bariatric surgery. Studies investigating candidate mechanisms have expanded dramatically in the last decade. Herein we review the proposed mechanisms governing changes in eating behavior, food intake, and body weight after bariatric surgery. Additive or synergistic effects of both conditioned and unconditioned factors likely account for the complete picture of changes in eating behavior. Considered application of strategies designed to support the underlying principles governing changes in eating behavior holds promise as a means of optimizing responses to surgery and long-term outcomes.
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Affiliation(s)
- Werd Al-Najim
- Diabetes Complications Research Centre, Conway Institute, School of Medicine and Medical Sciences, University College Dublin , Dublin , Ireland ; Department of Gastrosurgical Research and Education, Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg , Gothenburg , Sweden ; and Investigative Science, Imperial College London , London , United Kingdom
| | - Neil G Docherty
- Diabetes Complications Research Centre, Conway Institute, School of Medicine and Medical Sciences, University College Dublin , Dublin , Ireland ; Department of Gastrosurgical Research and Education, Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg , Gothenburg , Sweden ; and Investigative Science, Imperial College London , London , United Kingdom
| | - Carel W le Roux
- Diabetes Complications Research Centre, Conway Institute, School of Medicine and Medical Sciences, University College Dublin , Dublin , Ireland ; Department of Gastrosurgical Research and Education, Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg , Gothenburg , Sweden ; and Investigative Science, Imperial College London , London , United Kingdom
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Virtanen KA. Activation of Human Brown Adipose Tissue (BAT): Focus on Nutrition and Eating. Handb Exp Pharmacol 2018; 251:349-357. [PMID: 30141098 DOI: 10.1007/164_2018_136] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
Brown adipose tissue activation occurs most effectively by cold exposure. In the modern world, we do not spend long periods in cold environment, and eating and meals may be other activators of brown fat function. Short-term regulation of brown fat functional activity by eating involves most importantly insulin. Insulin is capable to increase glucose uptake in human brown adipose tissue fivefold to fasting conditions. Oxidative metabolism in brown fat is doubled both by cold and by a meal. Human brown adipose tissue is an insulin-sensitive tissue type, and insulin resistance impairs the function, as is found in obesity. Body weight reduction improves cold-induced activation of human brown adipose tissue.
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Affiliation(s)
- Kirsi A Virtanen
- Turku PET Centre, Turku University Hospital and University of Turku, Turku, Finland. .,Clinical Nutrition, Institute of Public Health and Clinical Nutrition, University of Eastern Finland (UEF), Kuopio, Finland.
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7
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Taste of glucose elicits cephalic-phase insulin release in mice. Physiol Behav 2018; 192:200-205. [DOI: 10.1016/j.physbeh.2018.04.002] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2017] [Revised: 03/31/2018] [Accepted: 04/01/2018] [Indexed: 01/08/2023]
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Shibao CA, Celedonio JE, Tamboli R, Sidani R, Love-Gregory L, Pietka T, Xiong Y, Wei Y, Abumrad NN, Abumrad NA, Flynn CR. CD36 Modulates Fasting and Preabsorptive Hormone and Bile Acid Levels. J Clin Endocrinol Metab 2018; 103:1856-1866. [PMID: 29546316 PMCID: PMC6446573 DOI: 10.1210/jc.2017-01982] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/06/2017] [Accepted: 03/07/2018] [Indexed: 01/16/2023]
Abstract
CONTEXT Abnormal fatty acid (FA) metabolism contributes to diabetes and cardiovascular disease. The FA receptor CD36 has been linked to risk of metabolic syndrome. In rodents CD36 regulates various aspects of fat metabolism, but whether it has similar actions in humans is unknown. We examined the impact of a coding single-nucleotide polymorphism in CD36 on postprandial hormone and bile acid (BA) responses. OBJECTIVE To examine whether the minor allele (G) of coding CD36 variant rs3211938 (G/T), which reduces CD36 level by ∼50%, influences hormonal responses to a high-fat meal (HFM). DESIGN Obese African American (AA) women carriers of the G allele of rs3211938 (G/T) and weight-matched noncarriers (T/T) were studied before and after a HFM. SETTING Two-center study. PARTICIPANTS Obese AA women. INTERVENTION HFM. MAIN OUTCOME MEASURES Early preabsorptive responses (10 minutes) and extended excursions in plasma hormones [C-peptide, insulin, incretins, ghrelin fibroblast growth factor (FGF)19, FGF21], BAs, and serum lipoproteins (chylomicrons, very-low-density lipoprotein) were determined. RESULTS At fasting, G-allele carriers had significantly reduced cholesterol and glycodeoxycholic acid and consistent but nonsignificant reductions of serum lipoproteins. Levels of GLP-1 and pancreatic polypeptide (PP) were reduced 60% to 70% and those of total BAs were 1.8-fold higher. After the meal, G-allele carriers displayed attenuated early (-10 to 10 minute) responses in insulin, C-peptide, GLP-1, gastric inhibitory peptide, and PP. BAs exhibited divergent trends in G allele carriers vs noncarriers concomitant with differential FGF19 responses. CONCLUSIONS CD36 plays an important role in the preabsorptive hormone and BA responses that coordinate brain and gut regulation of energy metabolism.
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Affiliation(s)
- Cyndya A Shibao
- Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee
- Correspondence and Reprint Requests: Charles Robb Flynn, PhD, Department of Surgery, MRBIV Room 8465A, 2213 Garland Avenue, Vanderbilt University Medical Center, Nashville, Tennessee 37232. E-mail: ; or Cyndya Shibao, MD, Department of Medicine, Division of Medicine, 562 Preston Research Building, Vanderbilt University Medical Center, Nashville, Tennessee 37232. E-mail:
| | - Jorge E Celedonio
- Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Robyn Tamboli
- Department of Surgery, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Reem Sidani
- Department of Surgery, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Latisha Love-Gregory
- Department of Medicine, Center for Human Nutrition, Washington University School of Medicine, St. Louis, Missouri
| | - Terri Pietka
- Department of Medicine, Center for Human Nutrition, Washington University School of Medicine, St. Louis, Missouri
| | - Yanhua Xiong
- Department of Surgery, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Yan Wei
- Department of Surgery, Vanderbilt University Medical Center, Nashville, Tennessee
- Department of General Surgery, Beijing Shijitan Hospital, Capital Medical University, Beijing, China
| | - Naji N Abumrad
- Department of Surgery, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Nada A Abumrad
- Department of Medicine, Center for Human Nutrition, Washington University School of Medicine, St. Louis, Missouri
| | - Charles Robb Flynn
- Department of Surgery, Vanderbilt University Medical Center, Nashville, Tennessee
- Correspondence and Reprint Requests: Charles Robb Flynn, PhD, Department of Surgery, MRBIV Room 8465A, 2213 Garland Avenue, Vanderbilt University Medical Center, Nashville, Tennessee 37232. E-mail: ; or Cyndya Shibao, MD, Department of Medicine, Division of Medicine, 562 Preston Research Building, Vanderbilt University Medical Center, Nashville, Tennessee 37232. E-mail:
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9
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Eliasson B, Rawshani A, Axelsen M, Hammarstedt A, Smith U. Cephalic phase of insulin secretion in response to a meal is unrelated to family history of type 2 diabetes. PLoS One 2017; 12:e0173654. [PMID: 28288176 PMCID: PMC5348013 DOI: 10.1371/journal.pone.0173654] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2016] [Accepted: 02/20/2017] [Indexed: 11/29/2022] Open
Abstract
The pre-absorptive cephalic phase of insulin secretion is elicited during the first ten min of a meal and before glucose levels rise. Its importance for insulin release during the post-absorptive phase has been well documented in animals but its presence or importance in man has become increasingly controversial. We here examined the presence of an early cephalic phase of insulin release in 31 well matched individuals without (n = 15) or with (n = 16) a known family history of type 2 diabetes (first-degree relatives; FDR). We also examined the potential differences in individuals with or without impaired fasting (IFG) and impaired glucose tolerance (IGT). We here demonstrate that a cephalic phase of insulin secretion was present in all individuals examined and without any differences between control persons and FDR or IFG/IGT. However, the overall importance of the cephalic phase is conjectural since it was unrelated to the subsequent post-absorptive insulin release or glucose tolerance. One of the best predictors of the incremental cephalic phase of insulin release was fasting insulin level and, thus, a relation to degree of insulin sensitivity is likely. In conclusion, an early pre-absorptive and cephalic phase of insulin release is robustly present in man. However, we could not document any relation to family history of Type 2 diabetes nor to the post-absorptive phase and, thus, confirm its importance for subsequent degree of insulin release or glucose tolerance.
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Affiliation(s)
- Björn Eliasson
- The Lundberg Laboratory for Diabetes Research, Department of Molecular and Clinical Medicine, Institute of Medicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Araz Rawshani
- The Lundberg Laboratory for Diabetes Research, Department of Molecular and Clinical Medicine, Institute of Medicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Mette Axelsen
- Department of Clinical Nutrition, Institute of Medicine; Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Ann Hammarstedt
- The Lundberg Laboratory for Diabetes Research, Department of Molecular and Clinical Medicine, Institute of Medicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Ulf Smith
- The Lundberg Laboratory for Diabetes Research, Department of Molecular and Clinical Medicine, Institute of Medicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
- * E-mail:
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Glendinning JI, Frim YG, Hochman A, Lubitz GS, Basile AJ, Sclafani A. Glucose elicits cephalic-phase insulin release in mice by activating K ATP channels in taste cells. Am J Physiol Regul Integr Comp Physiol 2017; 312:R597-R610. [PMID: 28148491 DOI: 10.1152/ajpregu.00433.2016] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2016] [Revised: 01/17/2017] [Accepted: 01/17/2017] [Indexed: 12/25/2022]
Abstract
The taste of sugar elicits cephalic-phase insulin release (CPIR), which limits the rise in blood glucose associated with meals. Little is known, however, about the gustatory mechanisms that trigger CPIR. We asked whether oral stimulation with any of the following taste stimuli elicited CPIR in mice: glucose, sucrose, maltose, fructose, Polycose, saccharin, sucralose, AceK, SC45647, or a nonmetabolizable sugar analog. The only taste stimuli that elicited CPIR were glucose and the glucose-containing saccharides (sucrose, maltose, Polycose). When we mixed an α-glucosidase inhibitor (acarbose) with the latter three saccharides, the mice no longer exhibited CPIR. This revealed that the carbohydrates were hydrolyzed in the mouth, and that the liberated glucose triggered CPIR. We also found that increasing the intensity or duration of oral glucose stimulation caused a corresponding increase in CPIR magnitude. To identify the components of the glucose-specific taste-signaling pathway, we examined the necessity of Calhm1, P2X2+P2X3, SGLT1, and Sur1. Among these proteins, only Sur1 was necessary for CPIR. Sur1 was not necessary, however, for taste-mediated attraction to sugars. Given that Sur1 is a subunit of the ATP-sensitive K+ channel (KATP) channel and that this channel functions as a part of a glucose-sensing pathway in pancreatic β-cells, we asked whether the KATP channel serves an analogous role in taste cells. We discovered that oral stimulation with drugs known to increase (glyburide) or decrease (diazoxide) KATP signaling produced corresponding changes in glucose-stimulated CPIR. We propose that the KATP channel is part of a novel signaling pathway in taste cells that mediates glucose-induced CPIR.
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Affiliation(s)
- John I Glendinning
- Department of Biology, Barnard College, Columbia University, New York, New York;
| | - Yonina G Frim
- Department of Biology, Barnard College, Columbia University, New York, New York
| | - Ayelet Hochman
- Department of Biology, Barnard College, Columbia University, New York, New York
| | - Gabrielle S Lubitz
- Department of Biology, Barnard College, Columbia University, New York, New York
| | - Anthony J Basile
- Department of Biology, Barnard College, Columbia University, New York, New York.,Institute of Human Nutrition, Columbia University, New York, New York; and
| | - Anthony Sclafani
- Department of Psychology, Brooklyn College of City University of New York, Brooklyn, New York
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Veedfald S, Plamboeck A, Deacon CF, Hartmann B, Knop FK, Vilsbøll T, Holst JJ. Cephalic phase secretion of insulin and other enteropancreatic hormones in humans. Am J Physiol Gastrointest Liver Physiol 2016; 310:G43-51. [PMID: 26492921 DOI: 10.1152/ajpgi.00222.2015] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/06/2015] [Accepted: 10/17/2015] [Indexed: 01/31/2023]
Abstract
Enteropancreatic hormone secretion is thought to include a cephalic phase, but the evidence in humans is ambiguous. We studied vagally induced gut hormone responses with and without muscarinic blockade in 10 glucose-clamped healthy men (age: 24.5 ± 0.6 yr, means ± SE; body mass index: 24.0 ± 0.5 kg/m(2); HbA1c: 5.1 ± 0.1%/31.4 ± 0.5 mmol/mol). Cephalic activation was elicited by modified sham feeding (MSF, aka "chew and spit") with or without atropine (1 mg bolus 45 min before MSF + 80 ng·kg(-1)·min(-1) for 2 h). To mimic incipient prandial glucose excursions, glucose levels were clamped at 6 mmol/l on all days. The meal stimulus for the MSF consisted of an appetizing breakfast. Participants (9/10) also had a 6 mmol/l glucose clamp without MSF. Pancreatic polypeptide (PP) levels rose from 6.3 ± 1.1 to 19.9 ± 6.8 pmol/l (means ± SE) in response to MSF and atropine lowered basal PP levels and abolished the MSF response. Neither insulin, C-peptide, glucose-dependent insulinotropic polypeptide (GIP), nor glucagon-like peptide-1 (GLP-1) levels changed in response to MSF or atropine. Glucagon and ghrelin levels were markedly attenuated by atropine prior to and during the clamp: at t = 105 min on the atropine (ATR) + clamp (CLA) + MSF compared with the saline (SAL) + CLA and SAL + CLA + MSF days; baseline-subtracted glucagon levels were -10.7 ± 1.1 vs. -4.0 ± 1.1 and -4.7 ± 1.9 pmol/l (means ± SE), P < 0.0001, respectively; corresponding baseline-subtracted ghrelin levels were 303 ± 36 vs. 39 ± 38 and 3.7 ± 21 pg/ml (means ± SE), P < 0.0001. Glucagon and ghrelin levels were unaffected by MSF. Despite adequate PP responses, a cephalic phase response was absent for insulin, glucagon, GLP-1, GIP, and ghrelin.
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Affiliation(s)
- Simon Veedfald
- Center for Diabetes Research, Gentofte Hospital, University of Copenhagen, Hellerup, Denmark; Department of Biomedical Sciences, The Panum Institute, University of Copenhagen, Copenhagen, Denmark; NNF Center for Basic Metabolic Research, The Panum Institute, University of Copenhagen, Copenhagen, Denmark; and Department of Surgical Gastroenterology, Rigshospitalet, University of Copenhagen, Denmark
| | - Astrid Plamboeck
- Center for Diabetes Research, Gentofte Hospital, University of Copenhagen, Hellerup, Denmark; Department of Biomedical Sciences, The Panum Institute, University of Copenhagen, Copenhagen, Denmark; NNF Center for Basic Metabolic Research, The Panum Institute, University of Copenhagen, Copenhagen, Denmark; and
| | - Carolyn F Deacon
- Department of Biomedical Sciences, The Panum Institute, University of Copenhagen, Copenhagen, Denmark; NNF Center for Basic Metabolic Research, The Panum Institute, University of Copenhagen, Copenhagen, Denmark; and
| | - Bolette Hartmann
- Department of Biomedical Sciences, The Panum Institute, University of Copenhagen, Copenhagen, Denmark; NNF Center for Basic Metabolic Research, The Panum Institute, University of Copenhagen, Copenhagen, Denmark; and
| | - Filip K Knop
- Center for Diabetes Research, Gentofte Hospital, University of Copenhagen, Hellerup, Denmark; Department of Biomedical Sciences, The Panum Institute, University of Copenhagen, Copenhagen, Denmark; NNF Center for Basic Metabolic Research, The Panum Institute, University of Copenhagen, Copenhagen, Denmark; and
| | - Tina Vilsbøll
- Center for Diabetes Research, Gentofte Hospital, University of Copenhagen, Hellerup, Denmark
| | - Jens J Holst
- Department of Biomedical Sciences, The Panum Institute, University of Copenhagen, Copenhagen, Denmark; NNF Center for Basic Metabolic Research, The Panum Institute, University of Copenhagen, Copenhagen, Denmark; and
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Abstract
The sense of taste is stimulated when nutrients or other chemical compounds activate specialized receptor cells within the oral cavity. Taste helps us decide what to eat and influences how efficiently we digest these foods. Human taste abilities have been shaped, in large part, by the ecological niches our evolutionary ancestors occupied and by the nutrients they sought. Early hominoids sought nutrition within a closed tropical forest environment, probably eating mostly fruit and leaves, and early hominids left this environment for the savannah and greatly expanded their dietary repertoire. They would have used their sense of taste to identify nutritious food items. The risks of making poor food selections when foraging not only entail wasted energy and metabolic harm from eating foods of low nutrient and energy content, but also the harmful and potentially lethal ingestion of toxins. The learned consequences of ingested foods may subsequently guide our future food choices. The evolved taste abilities of humans are still useful for the one billion humans living with very low food security by helping them identify nutrients. But for those who have easy access to tasty, energy-dense foods our sensitivities for sugary, salty and fatty foods have also helped cause over nutrition-related diseases, such as obesity and diabetes.
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Affiliation(s)
- Paul A S Breslin
- Rutgers University, Department of Nutrition, New Brunswick, NJ, USA.
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13
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Grill HJ, Hayes MR. Hindbrain neurons as an essential hub in the neuroanatomically distributed control of energy balance. Cell Metab 2012; 16:296-309. [PMID: 22902836 PMCID: PMC4862653 DOI: 10.1016/j.cmet.2012.06.015] [Citation(s) in RCA: 323] [Impact Index Per Article: 26.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/30/2011] [Revised: 03/20/2012] [Accepted: 06/08/2012] [Indexed: 02/07/2023]
Abstract
This Review highlights the processing and integration performed by hindbrain nuclei, focusing on the inputs received by nucleus tractus solitarius (NTS) neurons. These inputs include vagally mediated gastrointestinal satiation signals, blood-borne energy-related hormonal and nutrient signals, and descending neural signals from the forebrain. We propose that NTS (and hindbrain neurons, more broadly) integrate these multiple energy status signals and issue-output commands controlling the behavioral, autonomic, and endocrine responses that collectively govern energy balance. These hindbrain-mediated controls are neuroanatomically distributed; they involve endemic hindbrain neurons and circuits, hindbrain projections to peripheral circuits, and projections to and from midbrain and forebrain nuclei.
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Affiliation(s)
- Harvey J Grill
- Graduate Group of Psychology, University of Pennsylvania, Philadelphia, PA 19104, USA.
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Berthoud HR, Shin AC, Zheng H. Obesity surgery and gut-brain communication. Physiol Behav 2011; 105:106-19. [PMID: 21315095 PMCID: PMC3118403 DOI: 10.1016/j.physbeh.2011.01.023] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2010] [Revised: 01/25/2011] [Accepted: 01/26/2011] [Indexed: 12/15/2022]
Abstract
The prevalence of obesity, and the cluster of serious metabolic diseases it is associated with, continues to rise globally, and hopes for effective treatment with drugs have been considerably set back. Thus, success with bariatric surgeries to induce sustained body weight loss and effectively cure most of the associated co-morbidities appears almost "miraculous" and systematic investigation of the mechanisms at work has gained momentum. Here, we will discuss the basic organization of gut-brain communication and review clinical and pre-clinical investigations on the potential mechanisms by which gastric bypass surgery leads to its beneficial effects on energy balance and glucose homeostasis. Although a lot has been learned regarding changes in energy intake and expenditure, secretion of gut hormones, and improvement in glucose homeostasis, there has not yet been the "breakthrough observation" of identifying a key signaling component common to the beneficial effects of the surgery. However, given the complexity and redundancy of gut-brain signaling and gut signaling to other relevant organs, it is perhaps more realistic to expect a number of key signaling changes that act in concert to bring about the "miracle".
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Affiliation(s)
- Hans-Rudolf Berthoud
- Neurobiology of Nutrition Laboratory, Pennington Biomedical Research Center, Louisiana State University System, Baton Rouge, LA, USA.
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15
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Teff KL. How neural mediation of anticipatory and compensatory insulin release helps us tolerate food. Physiol Behav 2011; 103:44-50. [PMID: 21256146 PMCID: PMC3056926 DOI: 10.1016/j.physbeh.2011.01.012] [Citation(s) in RCA: 93] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2010] [Revised: 01/06/2011] [Accepted: 01/12/2011] [Indexed: 11/18/2022]
Abstract
Learned anticipatory and compensatory responses allow the animal and human to maintain metabolic homeostasis during periods of nutritional challenges, either acutely within each meal or chronically during periods of overnutrition. This paper discusses the role of neurally-mediated anticipatory responses in humans and their role in glucoregulation, focusing on cephalic phase insulin and pancreatic polypeptide release as well as compensatory insulin release during the etiology of insulin resistance. The necessary stimuli required to elicit CPIR and vagal activation are discussed and the role of CPIR and vagal efferent activation in intra-meal metabolic homeostasis and during chronic nutritional challenges are reviewed.
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Affiliation(s)
- Karen L Teff
- Monell Chemical Senses Center, 3500 Market Street, Philadelphia, PA 19104, United States.
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16
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Woods SC, Taborsky GJ, Porte D. Central Nervous System Control of Nutrient Homeostasis. Compr Physiol 2011. [DOI: 10.1002/cphy.cp010407] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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17
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Ranawana V, Henry CJK. Liquid and solid carbohydrate foods: comparative effects on glycemic and insulin responses, and satiety. Int J Food Sci Nutr 2010; 62:71-81. [DOI: 10.3109/09637486.2010.520011] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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18
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The vagus nerve, food intake and obesity. ACTA ACUST UNITED AC 2008; 149:15-25. [PMID: 18482776 DOI: 10.1016/j.regpep.2007.08.024] [Citation(s) in RCA: 211] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2006] [Accepted: 08/08/2007] [Indexed: 01/01/2023]
Abstract
Food interacts with sensors all along the alimentary canal to provide the brain with information regarding its composition, energy content, and beneficial effect. Vagal afferents innervating the gastrointestinal tract, pancreas, and liver provide a rapid and discrete account of digestible food in the alimentary canal, as well as circulating and stored fuels, while vagal efferents, together with the sympathetic nervous system and hormonal mechanisms, codetermine the rate of nutrient absorption, partitioning, storage, and mobilization. Although vagal sensory mechanisms play a crucial role in the neural mechanism of satiation, there is little evidence suggesting a significant role in long-term energy homeostasis. However, increasing recognition of vagal involvement in the putative mechanisms making bariatric surgeries the most effective treatment for obesity should greatly stimulate future research to uncover the many details regarding the specific transduction mechanisms in the periphery and the inter- and intra-neuronal signaling cascades disseminating vagal information across the neuraxis.
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Kissler HJ, Gepp H, Schmiedl A, Schwille PO. Preservation of the incretin effect after orthotopic pancreas transplantation in inbred rats. Metabolism 1999; 48:645-50. [PMID: 10337868 DOI: 10.1016/s0026-0495(99)90065-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
To establish whether the incretin effect is under neural control, insulin, C-peptide, and glucose-dependent insulinotropic peptide (GIP) responses and hepatic insulin clearance were investigated after oral and "isoglycemic" intravenous glucose in 12 inbred rats after denervation of the pancreas by orthotopic transplantation with portal venous drainage (Tx group) and in 12 laparotomized controls (sham group). Effective pancreas denervation was documented by a decreased pancreatic polypeptide (PP) response to insulin-induced hypoglycemia and by decreased levels of norepinephrine and calcitonin gene-related peptide (CGRP) in pancreatic tissue. Basal and incremental arterial plasma glucose integrated over 180 minutes did not differ between oral and intravenous glucose, but the integrated insulin response (mean +/- SEM) was significantly greater with oral versus intravenous glucose (Tx group, 104.9 +/- 22.0 v 31.0 +/- 4.9 nmol x L(-1) x min, P < .01; sham group, 79.5 +/- 10.6 v 36.6 +/- 5.8 nmol x L(-1) x min, P < .01). The integrated response of C-peptide was similar during both tests (Tx group, 105 +/- 14 v 79 +/- 8 pmol x mL(-1) x min; sham group, 112 +/- 10 v 121 +/- 12 pmol x mL(-1) x min). Hepatic insulin clearance was significantly decreased in both groups by oral compared with intravenous glucose administration (Tx group, 1.3 +/- 0.2 v 3.3 +/- 0.6 mmol/mmol, P < .01; sham group, 1.6 +/- 0.1 v 3.9 +/- 0.6 mmol/mmol, P < .02). The incretin effects for insulin (Tx group, 5.6 +/- 2.7; sham group, 3.0 +/- 0.8) and C-peptide (Tx group, 1.4 +/- 0.2; sham group, 1.1 +/- 0.2), calculated as the ratio of the integrated oral response and integrated intravenous response, and GIP responses to oral and intravenous glucose were not significantly different between the two groups. We conclude that there is preservation of the incretin effect in rats with orthotopically transplanted and hence extrinsically denervated pancreas, thus ruling out the possibility that the autonomic nervous system substantially contributes. Hepatic insulin clearance and insulinotropic hormones such as GIP appear to be more important.
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Affiliation(s)
- H J Kissler
- Department of Surgery, University of Erlangen, Germany
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20
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Karhunen LJ, Lappalainen RI, Niskanen LK, Turpeinen AK, Uusitupa MI. Determinants of the cephalic-phase insulin response in obese nondiabetic subjects. Metabolism 1996; 45:168-73. [PMID: 8596484 DOI: 10.1016/s0026-0495(96)90048-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Large interindividual variation is characteristic of the cephalic-phase insulin response (CPIR). Our aim was to examine the largely unknown determinants of CPIR in obese nondiabetic subjects before and after weight reduction. After a 12-hour overnight fast, 20 healthy, obese (body mass index, 31.1 to 41.4 kg/m2) subjects were individually exposed to food without being allowed to eat it. Levels of insulin, glucose, C-peptide, free fatty acids, and salivation, together with assessments of feeling of hunger and desire to eat, were measured during the experiment. Subjects were divided into three groups according to CPIR before the weight reduction: positive (PR), intermediate (IR), and negative (NR) responders. CPIR measurements before and after weight reduction correlated significantly with each other (r = .61, P < . 01,n=18). At the beginning of the study, NR had higher fasting plasma glucose and insulin values, as well as higher postload plasma glucose values, as compared with PR and IR. These differences disappeared after weight reduction. In an intravenous glucose tolerance test (IVGTT) performed 9 to 12 months afterward, first-phase insulin secretion was significantly lower in NR. Thus, the negative CPIR during visual and olfactory exposure to food-related stimuli may be related to the attenuated first-phase insulin secretion and mildly impaired glucose metabolism, possibly related to insulin resistance.
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Affiliation(s)
- L J Karhunen
- Department of Clinical Nutrition, A.I. Virtanen Institute, University of Kuopio, Finland
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21
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Ikeda T, Ochi H, Ohtani I, Fujiyama K, Hoshino T, Tanaka Y, Takeuchi T, Mashiba H. Possible role of the adrenergic mechanism in gastric inhibitory polypeptide- and glucagon-like peptide-1 (7-36) amide-induced insulin release in the rat. Metabolism 1993; 42:209-13. [PMID: 8386288 DOI: 10.1016/0026-0495(93)90037-o] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Gastric inhibitory polypeptide (GIP) and glucagon-like peptide-1(7-36) amide (GLP-1) are thought to be the most probable candidates for incretin. However, the precise mechanism of incretin effect is unclear. In the present study, to elucidate the possible role of the autonomic nervous system in incretin effect, the effects of atropine, propranolol, metoprolol, and phentolamine on GIP- or GLP-1-induced insulin release were investigated in the rat. The GIP-induced (2 or 20 micrograms) insulin release was partly inhibited by propranolol pretreatment (0.5 mg/kg subcutaneously [SC]), and GLP-1-induced (2 or 20 micrograms) insulin release was partly inhibited by propranolol or metoprolol (35 mg/kg SC). These results suggest that a beta-adrenergic mechanism may be involved in the incretin effect, probably through a modulating effect on GIP- or GLP-1-induced insulin secretion.
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Affiliation(s)
- T Ikeda
- First Department of Internal Medicine, Tottori University School of Medicine, Yonago, Japan
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22
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Nauck MA, Büsing M, Orskov C, Siegel EG, Talartschik J, Baartz A, Baartz T, Hopt UT, Becker HD, Creutzfeldt W. Preserved incretin effect in type 1 diabetic patients with end-stage nephropathy treated by combined heterotopic pancreas and kidney transplantation. Acta Diabetol 1993; 30:39-45. [PMID: 8329730 DOI: 10.1007/bf00572873] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Insulin secretion is stimulated better by oral than by intravenous glucose (incretin effect). The contribution of the autonomic nervous system to the incretin effect after oral glucose in humans is unclear. We therefore examined nine type 1 diabetic (insulin-dependent) patients with end-stage nephropathy, studied after combined heterotopic pancreas and kidney transplantation, and 7 non-diabetic kidney recipients (matched for creatinine clearance and immunosuppressive medication). The release of gastric inhibitory polypeptide (GIP) and glucagon-like peptide 1 (GLP-1) immunoreactivity and B cell secretory responses (IR insulin and C-peptide) to oral (50 g) and "isoglycaemic" intravenous glucose (identical glycaemic profile) were measured by radioimmunoassay. The difference in B cell responses between the two tests represents the contribution of the enteroinsular axis to the response after oral glucose (incretin effect). Insulin responses after the oral glucose challenge were similar in the two patient groups despite systemic venous drainage of the pancreas graft in the pancreas-kidney-transplanted group. In both groups GIP and GLP-1 increased after oral but not after intravenous glucose, and B cell secretory responses were significantly smaller (by 55.2 +/- 7.7% and 46.5 +/- 12.5%, respectively) with "isoglycaemic" intravenous glucose infusions. The lack of reduction in the incretin effect in pancreas-kidney-transplanted patients, whose functioning pancreas is denervated, indicates a lesser role for the nervous system and a more important contribution of circulating incretin hormones in mediating the enteroinsular axis in man.
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Affiliation(s)
- M A Nauck
- Department of Medicine, Georg August University, Göttingen, Germany
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23
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Affiliation(s)
- W Creutzfeldt
- Department of Internal Medicine, Georg-August-University, Göttingen, Germany
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24
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Köhler H, Schröter-Printzen I, Nustede R, Barthel M, Ebert R, Schafmayer A. Endocrine response to intragastric and intravenous glucose challenge in the denervated dog pancreas. INTERNATIONAL JOURNAL OF PANCREATOLOGY : OFFICIAL JOURNAL OF THE INTERNATIONAL ASSOCIATION OF PANCREATOLOGY 1992; 11:117-24. [PMID: 1607729 DOI: 10.1007/bf02925983] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The functional connection between the gut and the islet cells comprises nerves and gastrointestinal hormones. In this study, we quantified the incretin effect and the glucose tolerance (KG value) before and after denervation of the pancreas in dogs in order to find out whether the incretin effect is mediated by nerves. The participation of nerves was estimated by comparing metabolic tests before and after total extrinsic pancreatic denervation in 10 dogs. Fifty-nine percent of the insulin response after intragastric glucose was calculated preoperatively to be the result of incretin factors, a value similar to the 62% found in the postoperative series (with denervated pancreas). The response of GIP to intragastric glucose was not significantly different between pre- and postoperative tests. The KG values pre- and postoperative were in the same range. From our data, we conclude that extrinsic nerves of the pancreas do not seem to play an important role in mediating glucose homeostasis in dogs.
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Affiliation(s)
- H Köhler
- Department of General Surgery, University of Göttingen, FRG
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25
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Affiliation(s)
- R Ebert
- Department of Medicine, University of Göttingen, FRG
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26
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Siegel EG. [Normoglycemia as a therapy goal in diabetes treatment--concept and realization]. KLINISCHE WOCHENSCHRIFT 1990; 68:306-12. [PMID: 2110599 DOI: 10.1007/bf01649021] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
In diabetic patients (near-)normoglycemic control of blood glucose can only rarely be achieved by conventional insulin treatment. Novel strategies for this goal include transplantation of pancreatic tissue (whole organ, segment or isolated islets), the artificial pancreas with continuous blood glucose monitoring, insulin pump treatment and the intensified conventional treatment both of the latter including self-measurement of blood glucose and self-adaptation of the insulin dosis. The results of pancreas transplantation in recent years have shown a marked improvement, the one-year survival rate of a functioning organ is in the range of 50-70%. Due to the lifelong immunosuppression pancreas transplantation should be considered in diabetic patients who need a kidney transplantation and for this reason already require immunosuppression. In spite of encouraging results in animals islet transplantation in humans has been disappointing to date. The artificial pancreas at present cannot be used for long-term treatment mainly due to the problems of the glucose sensor. The application of insulin pump treatment without continuous monitoring of blood glucose (open loop) and intensified conventional treatment both can lead to improved glycemic control in spite of a more flexible life style. Only this way of treatment made it possible to perform randomized prospective studies in diabetic patients on the effect of (near-)normoglycemic control on secondary complications. The first results show a tendency towards a positive effect on mild to moderate diabetic retinopathy over 2 years. Thus, every juvenile diabetic patient should be informed about these possibilities of treatment.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- E G Siegel
- Abteilung Gastroenterologie und Endokrinologie, Universität Göttingen
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27
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Siegel EG, Creutzfeldt W. Pancreatic transplantation or intensive insulin therapy? BAILLIERE'S CLINICAL GASTROENTEROLOGY 1989; 3:877-86. [PMID: 2518330 DOI: 10.1016/0950-3528(89)90039-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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28
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The Incretin Concept. ACTA ACUST UNITED AC 1988. [DOI: 10.1016/b978-0-12-027311-9.50014-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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29
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Siegel EG, Creutzfeldt W. Effect of low concentrations of glucagon on insulin release and cyclic AMP content in isolated rat islets. Metabolism 1987; 36:953-7. [PMID: 2443791 DOI: 10.1016/0026-0495(87)90131-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Studies on hormone action in isolated islets have generally been carried out using concentrations far above physiologic levels. This study investigates whether glucagon at concentrations close to the physiologic level is insulinotropic in isolated islets and how this relates to islet cyclic AMP levels. Collagenase isolated rat islets were tested directly after isolation or after a 24-hour tissue culture. Insulin release and islet cyclic AMP content were determined during a 30-minute incubation by radioimmunoassay. After maintenance in tissue culture glucose-induced (16.7 mmol/L) insulin release was clearly enhanced by glucagon concentrations between 2 and 1,000 ng/mL in a dose-related manner. Islet cyclic AMP was increased only by glucagon 1 mumol/L (3.8 micrograms/mL). When phosphodiesterases were inhibited (0.1 mmol/L 3-isobutyl-1-methylxanthine) insulin release was stimulated by 1 ng/mL and cyclic AMP by 100 ng/mL. By contrast, in freshly isolated islets, glucagon concentrations in the range of 1 to 100 micrograms/mL were needed to augment glucose-induced insulin release. These findings demonstrate that the hormone sensitivity of collagenase isolated islets is markedly improved by short-term maintenance in tissue culture. The threshold level for a detectable effect on islet cyclic AMP is considerably higher than for glucose-induced insulin release. Since in hepatocytes two signal transduction systems for glucagon have recently been demonstrated, the results could mean that at low concentrations glucagon effects may not be mediated via cyclic AMP.
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Affiliation(s)
- E G Siegel
- Department of Medicine, University of Göttingen, FRG
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30
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Ebert R, Creutzfeldt W. Gastrointestinal peptides and insulin secretion. DIABETES/METABOLISM REVIEWS 1987; 3:1-26. [PMID: 3552520 DOI: 10.1002/dmr.5610030101] [Citation(s) in RCA: 70] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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31
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Siegel EG, Creutzfeldt W. Stimulation of insulin release in isolated rat islets by GIP in physiological concentrations and its relation to islet cyclic AMP content. Diabetologia 1985; 28:857-61. [PMID: 2417905 DOI: 10.1007/bf00291078] [Citation(s) in RCA: 58] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Several insulinotropic hormones have been shown to increase the level of cyclic AMP in isolated islets. This study was performed to investigate whether gastric inhibitory polypeptide (glucose-dependent insulin-releasing polypeptide) has a similar effect, in particular at concentrations close to the physiological level in blood. Collagenase isolated rat islets were maintained for 24 h in tissue culture (medium 199) and then incubated for 30 min for measurement of insulin release and cyclic AMP content. Glucose-induced (16.7 mmol/l) insulin release was enhanced by gastric inhibitory polypeptide 1-100 ng/ml (0.196-19.6 nmol/l) in a dose-related fashion. The cyclic AMP content was enhanced only by 100 ng/ml. However, when 0.1 mmol/l of the phosphodiesterase inhibitor 3-isobutyl-1-methylxanthine was present, even 1 ng/ml of gastric inhibitory polypeptide increased both cyclic AMP content and insulin release. Such a concentration of the hormone can be measured in human blood after a meal. In contrast, in freshly isolated islets no effect of the hormone on glucose-induced insulin release or cyclic AMP content could be detected for concentrations ranging from 1 to 100 ng/ml. These findings demonstrate that the hormone sensitivity of isolated islets is markedly enhanced by short-term maintenance in tissue culture. The results suggest that an increase in cyclic AMP is seen in response to gastric inhibitory polypeptide and may be causally related to the insulinotropic effect of the hormone.
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32
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Abstract
Experimental and clinical work over the last 6 years has confirmed and broadened, but also challenged, the incretin concept. The nervous component of the entero-insular axis is still poorly defined, especially the peptidergic nerves, of which several contain insulinotropic regulatory peptides. The incretin effect is preserved after complete denervation of the porcine pancreas. Type 2 (non insulin-dependent) diabetic patients have a significantly decreased incretin effect. GIP (gastric inhibitory polypeptide; glucose dependent insulin releasing peptide) remains the strongest incretin factor. Its secretion depends on the absorption of nutrients. However, the correlation between the GIP response and disturbances of the entero-insular axis in some gastrointestinal diseases and, in particular, Type 2 diabetes, is poor. Furthermore, physiological concentrations of exogenous GIP do not produce fully the incretin effect and injection of GIP antibodies does not abolish the incretin effect. This suggests the existence of additional humoral incretin factors. On the other hand, GIP seems to have direct metabolic effects independent of its insulinotropic activity. The incretin effect of oral glucose is smaller if plasma levels of C-peptide rather than insulin are measured. However, decreased hepatic extraction of insulin after glucose ingestion only accounts partially for the incretin effect. GIP is unlikely to be the gut factor which regulates hepatic insulin extraction.
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Nauck M, van Hoorn W, Gubernatis G, Ebert R, Siewert JR, Creutzfeldt W. Preserved incretin effect after complete surgical denervation of the pancreas in young pigs. RESEARCH IN EXPERIMENTAL MEDICINE. ZEITSCHRIFT FUR DIE GESAMTE EXPERIMENTELLE MEDIZIN EINSCHLIESSLICH EXPERIMENTELLER CHIRURGIE 1985; 185:291-8. [PMID: 3901165 DOI: 10.1007/bf01851954] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Plasma insulin responses to intragastric (i.g.) (1.5 g/kg b.wt.) and "isoglycemic" intravenous (i.v.) glucose were measured in ten unanesthetized young pigs to assess the contribution of gastrointestinal factors to the total insulin secretion as observed after i.g. glucose. The participation of nerves was estimated by comparing metabolic tests performed before and after total surgical pancreatic denervation. In the five animals which survived the procedure, 52.6% of the insulin response after i.g. glucose was calculated to be due to incretion factors, a value similar to the 54.8% found in the preoperative series (with intact pancreatic innervation). The response of IR-GIP to i.g. glucose was not significantly different between preoperative and postoperative tests, although a subtotal duodenectomy had to be performed in the course of the operation designed to completely denervate the pancreas. Intragastric and i.v. (also tested by bolus glucose injection) glucose tolerance was almost identical before and after the operation. It was concluded that nerves do not seem to play a major role in mediating the incretin effect in pigs. Hormonal factors, including GIP, appear to be more important.
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34
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Berthoud HR. The relative contribution of the nervous system, hormones, and metabolites to the total insulin response during a meal in the rat. Metabolism 1984; 33:18-25. [PMID: 6361448 DOI: 10.1016/0026-0495(84)90157-4] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
An attempt was made to quantitatively determine the relative contribution of the nervous system, hormonal factors, and metabolites to the total peripheral plasma insulin response (integrated incremental area) during a ten-minute liquid meal in conscious freely moving rats. The neurally mediated insulin response, as measured in the gastric-fistula bearing sham-feeding rat, amounted to at least 26%. The possible contribution of neural mechanisms triggered by the gastric, intestinal, and postabsorptive phases of the meal were, however, not determined. Hormonal factors were found to contribute at least 30% to the total insulin response on the basis of the insulin response to real feeding in atropinized rats, in the absence of any increases of plasma glucose and with only small elevations of plasma alpha-amino nitrogen. A possible atropine-suppressible hormonal factor was not isolated in the present study. Finally, the relative contribution of rising plasma glucose as determined by intravenous glucose infusions was found to amount to no more than 20%; however, the contribution of rising plasma amino acids was not determined. Thus, 23% of the total insulin response could not be segregated, but it is thought that a good part of it can be attributed to synergistic mechanisms. Because of such interactions, the sum of the effects of the isolated factors is less than the effect of the combined factors.
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35
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Ebert R, Unger H, Creutzfeldt W. Preservation of incretin activity after removal of gastric inhibitory polypeptide (GIP) from rat gut extracts by immunoadsorption. Diabetologia 1983; 24:449-54. [PMID: 6350081 DOI: 10.1007/bf00257346] [Citation(s) in RCA: 74] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
The action of watery rat gut extracts on glucose-induced insulin release in anaesthetized rats was examined before and after removal of GIP by immunoadsorption. Infusions of GIP-containing rat gut extracts nearly doubled the insulin release induced by intravenous glucose (1 g X kg -1 X h -1). Peak insulin secretion was 98 +/- 11 mU/l (mean +/- SEM) after intravenous glucose and increased to 178 +/- 16 mU/l following infusion of glucose plus gut extract (p less than 0.005). After injection of GIP antiserum in sufficient amounts to neutralize the GIP activity in the gut extract preparation, the additional insulin release due to the gut extract was reduced by only 30%. After complete removal of GIP from gut extracts by immuno-absorption, more than 50% of the incretin effect remained. These data suggest that the insulinotropic activity of rat gut extracts can only be partially related to GIP. The existence of additional insulinotropic gut factors which may also be released following oral glucose is postulated.
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36
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37
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Berthoud HR, Jeanrenaud B. Sham feeding-induced cephalic phase insulin release in the rat. THE AMERICAN JOURNAL OF PHYSIOLOGY 1982; 242:E280-5. [PMID: 7039361 DOI: 10.1152/ajpendo.1982.242.4.e280] [Citation(s) in RCA: 33] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
The effect of the cephalic phase of food ingestion on plasma insulin and glucagon concentration was assessed in the sham-feeding rat, bearing chronically implanted gastric drainage fistulas. It was found that continuous sham feeding produced a significant and phasic peripheral insulin response in the absence of any significant changes of glycemia. The response was almost completely blocked by prior intravenous administration of 2 mg/kg of atropine methyl nitrate and potentiated by prior intravenous administration of 1.0 or 2.5 mg/kg of phentolamine. In spite of the larger insulin response after phentolamine, there was no hypoglycemia detected. Furthermore, continuous sham feeding did not produce a significant glucagon response, whereas real feeling did. The results demonstrate that cholinergic insulin release is triggered phasically by continuous ingestion of familiar food and that this insulin response is inhibited by an alpha-adrenergic sympathetic tone. It is further concluded that the increased glucose disposal produced by the neurally released insulin is not counteracted by a concomitant glucagon response or by direct adrenergic stimulation of hepatic glucose production.
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38
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Trimble ER, Berthoud HR, Siegel EG, Jeanrenaud B, Renold AE. Importance of cholinergic innervation of the pancreas for glucose tolerance in the rat. THE AMERICAN JOURNAL OF PHYSIOLOGY 1981; 241:E337-41. [PMID: 6795929 DOI: 10.1152/ajpendo.1981.241.5.e337] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Because cholinergic innervation of the pancreas is of importance in control of oral glucose tolerance, it seems important to determine whether transplanted pancreatic tissue becomes reinnervated with cholinergic fibers. Oral and intravenous glucose tolerance tests (ivGTT) were performed with and without atropine treatment on streptozotocin-diabetic rats treated by intraportal transplantation of isogenic islets 13-15 wk previously and on sham-operated nondiabetic controls. Atropine had no effect on the ivGTT of transplanted rats or controls. In controls atropine caused a deterioration of the oral glucose tolerance, abolished the preabsorptive insulin release, and also diminished the early part of the glucose-induced insulin release in these animals. In the absence of atropine, transplanted rats had pathological oral glucose tolerance, preabsorptive insulin release was absent, and glucose-induced insulin release was diminished compared to controls. Atropine had little effect on the oral GTT of transplanted rats. The present results underline the importance of the vagus nerve in the control of oral glucose tolerance and show that the vagus nerve in rats, at least under these experimental conditions, does not modulate the insulin response to intravenous glucose. The results suggest that intraportally transplanted islets remain functionally vagotomized.
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