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Banerjee R, Zhu Y, Brownrigg GP, Moravcova R, Rogalski JC, Foster LJ, Johnson JD, Kolic J. Beta-Hydroxybutyrate Promotes Basal Insulin Secretion While Decreasing Glucagon Secretion in Mouse and Human Islets. Endocrinology 2024; 165:bqae079. [PMID: 38970533 PMCID: PMC11264143 DOI: 10.1210/endocr/bqae079] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/04/2024] [Revised: 06/17/2024] [Accepted: 06/27/2024] [Indexed: 07/08/2024]
Abstract
Dietary carbohydrates raise blood glucose levels, and limiting carbohydrate intake improves glycemia in patients with type 2 diabetes. Low carbohydrate intake (< 25 g) allows the body to utilize fat as its primary fuel. As a consequence of increased fatty acid oxidation, the liver produces ketones to serve as an alternative energy source. β-Hydroxybutyrate (βHB) is the most abundant ketone. While βHB has a wide range of functions outside of the pancreas, its direct effects on islet cell function remain understudied. We examined human islet secretory response to acute racemic βHB treatment and observed increased insulin secretion at a low glucose concentration of 3 mM. Because βHB is a chiral molecule, existing as both R and S forms, we further studied insulin and glucagon secretion following acute treatment with individual βHB enantiomers in human and C57BL/6J mouse islets. We found that acute treatment with R-βHB increased insulin secretion and decreased glucagon secretion at physiological glucose concentrations in both human and mouse islets. Proteomic analysis of human islets treated with R-βHB over 72 hours showed altered abundance of proteins that may promote islet cell health and survival. Collectively, our data show that physiological concentrations of βHB influence hormone secretion and signaling within pancreatic islets.
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Affiliation(s)
- Risha Banerjee
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, BC V6T 2A1, Canada
| | - Ying Zhu
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, BC V6T 2A1, Canada
| | - George P Brownrigg
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, BC V6T 2A1, Canada
| | - Renata Moravcova
- Department of Biochemistry and Molecular Biology, Life Sciences Institute, University of British Columbia, Vancouver, BC V6T 2A1, Canada
| | - Jason C Rogalski
- Department of Biochemistry and Molecular Biology, Life Sciences Institute, University of British Columbia, Vancouver, BC V6T 2A1, Canada
| | - Leonard J Foster
- Department of Biochemistry and Molecular Biology, Life Sciences Institute, University of British Columbia, Vancouver, BC V6T 2A1, Canada
| | - James D Johnson
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, BC V6T 2A1, Canada
| | - Jelena Kolic
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, Vancouver, BC V6T 2A1, Canada
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2
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Muñoz F, Fex M, Moritz T, Mulder H, Cataldo LR. Unique features of β-cell metabolism are lost in type 2 diabetes. Acta Physiol (Oxf) 2024; 240:e14148. [PMID: 38656044 DOI: 10.1111/apha.14148] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2023] [Revised: 02/28/2024] [Accepted: 04/05/2024] [Indexed: 04/26/2024]
Abstract
Pancreatic β cells play an essential role in the control of systemic glucose homeostasis as they sense blood glucose levels and respond by secreting insulin. Upon stimulating glucose uptake in insulin-sensitive tissues post-prandially, this anabolic hormone restores blood glucose levels to pre-prandial levels. Maintaining physiological glucose levels thus relies on proper β-cell function. To fulfill this highly specialized nutrient sensor role, β cells have evolved a unique genetic program that shapes its distinct cellular metabolism. In this review, the unique genetic and metabolic features of β cells will be outlined, including their alterations in type 2 diabetes (T2D). β cells selectively express a set of genes in a cell type-specific manner; for instance, the glucose activating hexokinase IV enzyme or Glucokinase (GCK), whereas other genes are selectively "disallowed", including lactate dehydrogenase A (LDHA) and monocarboxylate transporter 1 (MCT1). This selective gene program equips β cells with a unique metabolic apparatus to ensure that nutrient metabolism is coupled to appropriate insulin secretion, thereby avoiding hyperglycemia, as well as life-threatening hypoglycemia. Unlike most cell types, β cells exhibit specialized bioenergetic features, including supply-driven rather than demand-driven metabolism and a high basal mitochondrial proton leak respiration. The understanding of these unique genetically programmed metabolic features and their alterations that lead to β-cell dysfunction is crucial for a comprehensive understanding of T2D pathophysiology and the development of innovative therapeutic approaches for T2D patients.
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Affiliation(s)
- Felipe Muñoz
- Clinical Research Center, Department of Clinical Sciences in Malmö, Lund University Diabetes Centre, Lund, Sweden
| | - Malin Fex
- Clinical Research Center, Department of Clinical Sciences in Malmö, Lund University Diabetes Centre, Lund, Sweden
| | - Thomas Moritz
- Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Hindrik Mulder
- Clinical Research Center, Department of Clinical Sciences in Malmö, Lund University Diabetes Centre, Lund, Sweden
| | - Luis Rodrigo Cataldo
- Clinical Research Center, Department of Clinical Sciences in Malmö, Lund University Diabetes Centre, Lund, Sweden
- Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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3
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Lee K, Kuang A, Bain JR, Hayes MG, Muehlbauer MJ, Ilkayeva OR, Newgard CB, Powe CE, Hivert MF, Scholtens DM, Lowe WL. Metabolomic and genetic architecture of gestational diabetes subtypes. Diabetologia 2024; 67:895-907. [PMID: 38367033 DOI: 10.1007/s00125-024-06110-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/14/2023] [Accepted: 01/12/2024] [Indexed: 02/19/2024]
Abstract
AIMS/HYPOTHESIS Physiological gestational diabetes mellitus (GDM) subtypes that may confer different risks for adverse pregnancy outcomes have been defined. The aim of this study was to characterise the metabolome and genetic architecture of GDM subtypes to address the hypothesis that they differ between GDM subtypes. METHODS This was a cross-sectional study of participants in the Hyperglycemia and Adverse Pregnancy Outcome (HAPO) study who underwent an OGTT at approximately 28 weeks' gestation. GDM was defined retrospectively using International Association of Diabetes and Pregnancy Study Groups/WHO criteria, and classified as insulin-deficient GDM (insulin secretion <25th percentile with preserved insulin sensitivity) or insulin-resistant GDM (insulin sensitivity <25th percentile with preserved insulin secretion). Metabolomic analyses were performed on fasting and 1 h serum samples in 3463 individuals (576 with GDM). Genome-wide genotype data were obtained for 8067 individuals (1323 with GDM). RESULTS Regression analyses demonstrated striking differences between the metabolomes for insulin-deficient or insulin-resistant GDM compared to those with normal glucose tolerance. After adjustment for covariates, 33 fasting metabolites, including 22 medium- and long-chain acylcarnitines, were uniquely associated with insulin-deficient GDM; 23 metabolites, including the branched-chain amino acids and their metabolites, were uniquely associated with insulin-resistant GDM; two metabolites (glycerol and 2-hydroxybutyrate) were associated with the same direction of association with both subtypes. Subtype differences were also observed 1 h after a glucose load. In genome-wide association studies, variants within MTNR1B (rs10830963, p=3.43×10-18, OR 1.55) and GCKR (rs1260326, p=5.17×10-13, OR 1.43) were associated with GDM. Variants in GCKR (rs1260326, p=1.36×10-13, OR 1.60) and MTNR1B (rs10830963, p=1.22×10-9, OR 1.49) demonstrated genome-wide significant association with insulin-resistant GDM; there were no significant associations with insulin-deficient GDM. The lead SNP in GCKR, rs1260326, was associated with the levels of eight of the 25 fasting metabolites that were associated with insulin-resistant GDM and ten of 41 1 h metabolites that were associated with insulin-resistant GDM. CONCLUSIONS/INTERPRETATION This study demonstrates that physiological GDM subtypes differ in their metabolome and genetic architecture. These findings require replication in additional cohorts, but suggest that these differences may contribute to subtype-related adverse pregnancy outcomes.
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Affiliation(s)
- Kristen Lee
- Department of Medicine, Northwestern University Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
| | - Alan Kuang
- Department of Preventive Medicine, Northwestern University Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
| | - James R Bain
- Duke Molecular Physiology Institute, Durham, NC, USA
- Department of Medicine, Duke University School of Medicine, Duke University, Durham, NC, USA
| | - M Geoffrey Hayes
- Department of Medicine, Northwestern University Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
| | | | - Olga R Ilkayeva
- Duke Molecular Physiology Institute, Durham, NC, USA
- Department of Medicine, Duke University School of Medicine, Duke University, Durham, NC, USA
| | - Christopher B Newgard
- Duke Molecular Physiology Institute, Durham, NC, USA
- Department of Medicine, Duke University School of Medicine, Duke University, Durham, NC, USA
| | - Camille E Powe
- Department of Medicine, Massachusetts General Hospital, Boston, MA, USA
- Department of Obstetrics and Gynecology, Massachusetts General Hospital, Boston, MA, USA
- Broad Institute of MIT and Harvard, Boston, MA, USA
| | - Marie-France Hivert
- Department of Medicine, Massachusetts General Hospital, Boston, MA, USA
- Department of Population Medicine, Harvard Pilgrim Health Care Institute, Harvard Medical School, Boston, MA, USA
- Department of Medicine, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, QC, Canada
- Centre de Recherche du Centre Hospitalier Universitaire de Sherbrooke, Sherbrooke, QC, Canada
| | - Denise M Scholtens
- Department of Preventive Medicine, Northwestern University Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
| | - William L Lowe
- Department of Medicine, Northwestern University Feinberg School of Medicine, Northwestern University, Chicago, IL, USA.
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4
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Quinones MD, Weiman K, Lemon PWR. Ketone Monoester Followed by Carbohydrate Ingestion after Glycogen-Lowering Exercise Does Not Improve Subsequent Endurance Cycle Time Trial Performance. Nutrients 2024; 16:932. [PMID: 38612966 PMCID: PMC11013615 DOI: 10.3390/nu16070932] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2024] [Revised: 03/20/2024] [Accepted: 03/21/2024] [Indexed: 04/14/2024] Open
Abstract
Relative to carbohydrate (CHO) alone, exogenous ketones followed by CHO supplementation during recovery from glycogen-lowering exercise have been shown to increase muscle glycogen resynthesis. However, whether this strategy improves subsequent exercise performance is unknown. The objective of this study was to assess the efficacy of ketone monoester (KME) followed by CHO ingestion after glycogen-lowering exercise on subsequent 20 km (TT20km) and 5 km (TT5km) best-effort time trials. Nine recreationally active men (175.6 ± 5.3 cm, 72.9 ± 7.7 kg, 28 ± 5 y, 12.2 ± 3.2% body fat, VO2max = 56.2 ± 5.8 mL· kg BM-1·min-1; mean ± SD) completed a glycogen-lowering exercise session, followed by 4 h of recovery and subsequent TT20km and TT5km. During the first 2 h of recovery, participants ingested either KME (25 g) followed by CHO at a rate of 1.2 g·kg-1·h-1 (KME + CHO) or an iso-energetic placebo (dextrose) followed by CHO (PLAC + CHO). Blood metabolites during recovery and performance during the subsequent two-time trials were measured. In comparison to PLAC + CHO, KME + CHO displayed greater (p < 0.05) blood beta-hydroxybutyrate concentration during the first 2 h, lower (p < 0.05) blood glucose concentrations at 30 and 60 min, as well as greater (p < 0.05) blood insulin concentration 2 h following ingestion. However, no treatment differences (p > 0.05) in power output nor time to complete either time trial were observed vs. PLAC + CHO. These data indicate that the metabolic changes induced by KME + CHO ingestion following glycogen-lowering exercise are insufficient to enhance subsequent endurance time trial performance.
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Affiliation(s)
| | | | - Peter W. R. Lemon
- Exercise Nutrition Research Laboratory, School of Kinesiology, The University of Western Ontario, London, ON N6A 3K7, Canada; (M.D.Q.); (K.W.)
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5
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Alemany M. The Metabolic Syndrome, a Human Disease. Int J Mol Sci 2024; 25:2251. [PMID: 38396928 PMCID: PMC10888680 DOI: 10.3390/ijms25042251] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2023] [Revised: 01/29/2024] [Accepted: 01/31/2024] [Indexed: 02/25/2024] Open
Abstract
This review focuses on the question of metabolic syndrome (MS) being a complex, but essentially monophyletic, galaxy of associated diseases/disorders, or just a syndrome of related but rather independent pathologies. The human nature of MS (its exceptionality in Nature and its close interdependence with human action and evolution) is presented and discussed. The text also describes the close interdependence of its components, with special emphasis on the description of their interrelations (including their syndromic development and recruitment), as well as their consequences upon energy handling and partition. The main theories on MS's origin and development are presented in relation to hepatic steatosis, type 2 diabetes, and obesity, but encompass most of the MS components described so far. The differential effects of sex and its biological consequences are considered under the light of human social needs and evolution, which are also directly related to MS epidemiology, severity, and relations with senescence. The triggering and maintenance factors of MS are discussed, with especial emphasis on inflammation, a complex process affecting different levels of organization and which is a critical element for MS development. Inflammation is also related to the operation of connective tissue (including the adipose organ) and the widely studied and acknowledged influence of diet. The role of diet composition, including the transcendence of the anaplerotic maintenance of the Krebs cycle from dietary amino acid supply (and its timing), is developed in the context of testosterone and β-estradiol control of the insulin-glycaemia hepatic core system of carbohydrate-triacylglycerol energy handling. The high probability of MS acting as a unique complex biological control system (essentially monophyletic) is presented, together with additional perspectives/considerations on the treatment of this 'very' human disease.
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Affiliation(s)
- Marià Alemany
- Faculty of Biology, Universitat de Barcelona, 08028 Barcelona, Catalonia, Spain
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6
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Margolis LM, Pasiakos SM, Howard EE. High-fat ketogenic diets and ketone monoester supplements differentially affect substrate metabolism during aerobic exercise. Am J Physiol Cell Physiol 2023; 325:C1144-C1153. [PMID: 37721006 PMCID: PMC10635661 DOI: 10.1152/ajpcell.00359.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2023] [Revised: 09/07/2023] [Accepted: 09/07/2023] [Indexed: 09/19/2023]
Abstract
Chronically adhering to high-fat ketogenic diets or consuming ketone monoester supplements elicits ketosis. Resulting changes in substrate metabolism appear to be drastically different between ketogenic diets and ketone supplements. Consuming a ketogenic diet increases fatty acid oxidation with concomitant decreases in endogenous carbohydrate oxidation. Increased fat oxidation eventually results in an accumulation of circulating ketone bodies, which are metabolites of fatty acids that serve as an alternative source of fuel. Conversely, consuming ketone monoester supplements rapidly increases circulating ketone body concentrations that typically exceed those achieved by adhering to ketogenic diets. Rapid increases in ketone body concentrations with ketone monoester supplementation elicit a negative feedback inhibition that reduces fatty acid mobilization during aerobic exercise. Supplement-derived ketosis appears to have minimal impact on sparing of muscle glycogen or minimizing of carbohydrate oxidation during aerobic exercise. This review will discuss the substrate metabolic and associated aerobic performance responses to ketogenic diets and ketone supplements.
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Affiliation(s)
- Lee M Margolis
- Military Nutrition Division, US Army Research Institute of Environmental Medicine, Natick, Massachusetts, United States
| | - Stefan M Pasiakos
- Office of Dietary Supplements, U.S. Department of Health and Human Services, National Institutes of Health, Bethesda, Maryland, United States
| | - Emily E Howard
- Military Nutrition Division, US Army Research Institute of Environmental Medicine, Natick, Massachusetts, United States
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Tabatabaei Dakhili SA, Yang K, Locatelli CAA, Saed CT, Greenwell AA, Chan JSF, Chahade JJ, Scharff J, Al-Imarah S, Eaton F, Crawford PA, Gopal K, Mulvihill EE, Ussher JR. Ketone ester administration improves glycemia in obese mice. Am J Physiol Cell Physiol 2023; 325:C750-C757. [PMID: 37575059 DOI: 10.1152/ajpcell.00300.2023] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2023] [Revised: 08/04/2023] [Accepted: 08/07/2023] [Indexed: 08/15/2023]
Abstract
During periods of prolonged fasting/starvation, the liver generates ketones [i.e., β-hydroxybutyrate (βOHB)] that primarily serve as alternative substrates for ATP production. Previous studies have demonstrated that elevations in skeletal muscle ketone oxidation contribute to obesity-related hyperglycemia, whereas inhibition of succinyl CoA:3-ketoacid CoA transferase (SCOT), the rate-limiting enzyme of ketone oxidation, can alleviate obesity-related hyperglycemia. As circulating ketone levels are a key determinant of ketone oxidation rates, we tested the hypothesis that increases in circulating ketone levels would worsen glucose homeostasis secondary to increases in muscle ketone oxidation. Accordingly, male C57BL/6J mice were subjected to high-fat diet-induced obesity, whereas their lean counterparts received a standard chow diet. Lean and obese mice were orally administered either a ketone ester (KE) or placebo, followed by a glucose tolerance test. In tandem, we conducted isolated islet perifusion experiments to quantify insulin secretion in response to ketones. We observed that exogenous KE administration robustly increases circulating βOHB levels, which was associated with an improvement in glucose tolerance only in obese mice. These observations were independent of muscle ketone oxidation, as they were replicated in mice with a skeletal muscle-specific SCOT deficiency. Furthermore, the R-isomer of βOHB produced greater increases in perifusion insulin levels versus the S-isomer in isolated islets from obese mice. Taken together, acute elevations in circulating ketones promote glucose-lowering in obesity. Given that only the R-isomer of βOHB is oxidized, further studies are warranted to delineate the precise role of β-cell ketone oxidation in regulating insulin secretion.NEW & NOTEWORTHY It has been demonstrated that increased skeletal muscle ketone metabolism contributes to obesity-related hyperglycemia. Since increases in ketone supply are key determinants of organ ketone oxidation rates, we determined whether acute elevations in circulating ketones following administration of an oral ketone ester may worsen glucose homeostasis in lean or obese mice. Our work demonstrates the opposite, as acute elevations in circulating ketones improved glucose tolerance in obese mice.
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Affiliation(s)
- Seyed Amirhossein Tabatabaei Dakhili
- Faculty of Pharmacy and Pharmaceutical Sciences, University of Alberta, Edmonton, Alberta, Canada
- Alberta Diabetes Institute, University of Alberta, Edmonton, Alberta, Canada
| | - Kunyan Yang
- Faculty of Pharmacy and Pharmaceutical Sciences, University of Alberta, Edmonton, Alberta, Canada
- Alberta Diabetes Institute, University of Alberta, Edmonton, Alberta, Canada
| | - Cassandra A A Locatelli
- Department of Biochemistry, Microbiology, and Immunology, University of Ottawa, Ottawa, Ontario, Canada
- University of Ottawa Heart Institute, Ottawa, Ontario, Canada
| | - Christina T Saed
- Faculty of Pharmacy and Pharmaceutical Sciences, University of Alberta, Edmonton, Alberta, Canada
- Alberta Diabetes Institute, University of Alberta, Edmonton, Alberta, Canada
| | - Amanda A Greenwell
- Faculty of Pharmacy and Pharmaceutical Sciences, University of Alberta, Edmonton, Alberta, Canada
- Alberta Diabetes Institute, University of Alberta, Edmonton, Alberta, Canada
| | - Jordan S F Chan
- Faculty of Pharmacy and Pharmaceutical Sciences, University of Alberta, Edmonton, Alberta, Canada
- Alberta Diabetes Institute, University of Alberta, Edmonton, Alberta, Canada
| | - Jadin J Chahade
- Faculty of Pharmacy and Pharmaceutical Sciences, University of Alberta, Edmonton, Alberta, Canada
- Alberta Diabetes Institute, University of Alberta, Edmonton, Alberta, Canada
| | - Jared Scharff
- Faculty of Pharmacy and Pharmaceutical Sciences, University of Alberta, Edmonton, Alberta, Canada
- Alberta Diabetes Institute, University of Alberta, Edmonton, Alberta, Canada
| | - Shahad Al-Imarah
- Faculty of Pharmacy and Pharmaceutical Sciences, University of Alberta, Edmonton, Alberta, Canada
- Alberta Diabetes Institute, University of Alberta, Edmonton, Alberta, Canada
| | - Farah Eaton
- Faculty of Pharmacy and Pharmaceutical Sciences, University of Alberta, Edmonton, Alberta, Canada
- Alberta Diabetes Institute, University of Alberta, Edmonton, Alberta, Canada
| | - Peter A Crawford
- Division of Molecular Medicine, Department of Medicine, University of Minnesota, Minneapolis, Minnesota, United States
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, Minnesota, United States
| | - Keshav Gopal
- Faculty of Pharmacy and Pharmaceutical Sciences, University of Alberta, Edmonton, Alberta, Canada
- Alberta Diabetes Institute, University of Alberta, Edmonton, Alberta, Canada
| | - Erin E Mulvihill
- Department of Biochemistry, Microbiology, and Immunology, University of Ottawa, Ottawa, Ontario, Canada
- University of Ottawa Heart Institute, Ottawa, Ontario, Canada
| | - John R Ussher
- Faculty of Pharmacy and Pharmaceutical Sciences, University of Alberta, Edmonton, Alberta, Canada
- Alberta Diabetes Institute, University of Alberta, Edmonton, Alberta, Canada
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8
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Falkenhain K, Islam H, Little JP. Exogenous ketone supplementation: an emerging tool for physiologists with potential as a metabolic therapy. Exp Physiol 2023; 108:177-187. [PMID: 36533967 PMCID: PMC10103874 DOI: 10.1113/ep090430] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2022] [Accepted: 11/28/2022] [Indexed: 12/23/2022]
Abstract
NEW FINDINGS What is the topic of this review? The integrative physiological response to exogenous ketone supplementation. What advances does it highlight? The physiological effects and therapeutic potential of exogenous ketones on metabolic health, cardiovascular function, cognitive processing, and modulation of inflammatory pathways and immune function. Also highlighted are current challenges and future directions of the field. ABSTRACT Exogenous oral ketone supplements, primarily in form of ketone salts or esters, have emerged as a useful research tool for manipulating metabolism with potential therapeutic application targeting various aspects of several common chronic diseases. Recent literature has investigated the effects of exogenously induced ketosis on metabolic health, cardiovascular function, cognitive processing, and modulation of inflammatory pathways and immune function. This narrative review provides an overview of the integrative physiological effects of exogenous ketone supplementation and highlights current challenges and future research directions. Much of the existing research on therapeutic applications - particularly mechanistic studies - has involved pre-clinical rodent and/or cellular models, requiring further validation in human clinical studies. Existing human studies report that exogenous ketones can lower blood glucose and improve some aspects of cognitive function, highlighting the potential therapeutic application of exogenous ketones for type 2 diabetes and neurological diseases. There is also support for the ability of exogenous ketosis to improve cardiac metabolism in rodent models of heart failure with supporting human studies emerging; long-terms effects of exogenous ketone supplementation on the human cardiovascular system and lipid profiles are needed. An important avenue for future work is provided by research accelerating technologies that enable continuous ketone monitoring and/or the development of more palatable ketone mixtures that optimize plasma ketone kinetics to enable sustained ketosis. Lastly, research exploring the physiological interactions between exogenous ketones and varying metabolic states (e.g., exercise, fasting, metabolic disease) should yield important insights that can be used to maximize the health benefits of exogenous ketosis.
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Affiliation(s)
- Kaja Falkenhain
- School of Health and Exercise SciencesUniversity of British Columbia OkanaganKelownaBritish ColumbiaCanada
| | - Hashim Islam
- School of Health and Exercise SciencesUniversity of British Columbia OkanaganKelownaBritish ColumbiaCanada
| | - Jonathan P. Little
- School of Health and Exercise SciencesUniversity of British Columbia OkanaganKelownaBritish ColumbiaCanada
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9
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Soto‐Mota A, Norwitz NG, Evans RD, Clarke K. Exogenous
d
‐β‐hydroxybutyrate lowers blood glucose in part by decreasing the availability of L‐alanine for gluconeogenesis. Endocrinol Diabetes Metab 2022; 5:e00300. [PMID: 34787952 PMCID: PMC8754249 DOI: 10.1002/edm2.300] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Revised: 09/08/2021] [Accepted: 09/11/2021] [Indexed: 12/28/2022] Open
Abstract
Background Interventions that induce ketosis simultaneously lower blood glucose and the explanation for this phenomenon is unknown. Additionally, the glucose‐lowering effect of acute ketosis is greater in people with type 2 diabetes (T2D). On the contrary, L‐alanine is a gluconeogenic substrate secreted by skeletal muscle at higher levels in people with T2D and infusing of ketones lower circulating L‐alanine blood levels. In this study, we sought to determine whether supplementation with L‐alanine would attenuate the glucose‐lowering effect of exogenous ketosis using a ketone ester (KE). Methods This crossover study involved 10 healthy human volunteers who fasted for 24 h prior to the ingestion of 25 g of d‐β‐hydroxybutyrate (βHB) in the form of a KE drink (ΔG®) on two separate visits. During one of the visits, participants additionally ingested 2 g of L‐alanine to see whether L‐alanine supplementation would attenuate the glucose‐lowering effect of the KE drink. Blood L‐alanine, L‐glutamine, glucose, βHB, free fatty acids (FFA), lactate and C‐peptide were measured for 120 min after ingestion of the KE, with or without L‐alanine. Findings The KE drinks elevated blood βHB concentrations from negligible levels to 4.52 ± 1.23 mmol/L, lowered glucose from 4.97 ± SD 0.39 to 3.77 ± SD 0.40 mmol/L, and lowered and L‐alanine from 0.56 ± SD 0.88 to 0.41 ± SD 0.91 mmol/L. L‐alanine in the KE drink elevated blood L‐Alanine by 0.68 ± SD 0.15 mmol/L, but had no significant effect on blood βHB, L‐glutamine, FFA, lactate, nor C‐peptide concentrations. By contrast, L‐alanine supplementation significantly attenuated the ketosis‐induced drop in glucose from 28% ± SD 8% to 16% ± SD 7% (p < .01). Conclusions The glucose‐lowering effect of acutely elevated βHB is partially due to βHB decreasing L‐alanine availability as a substrate for gluconeogenesis.
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Affiliation(s)
- Adrian Soto‐Mota
- Department of Physiology, Anatomy and Genetics University of Oxford Oxford UK
| | - Nicholas G. Norwitz
- Department of Physiology, Anatomy and Genetics University of Oxford Oxford UK
| | - Rhys D. Evans
- Department of Physiology, Anatomy and Genetics University of Oxford Oxford UK
| | - Kieran Clarke
- Department of Physiology, Anatomy and Genetics University of Oxford Oxford UK
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10
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Bharmal SH, Cho J, Alarcon Ramos GC, Ko J, Cameron-Smith D, Petrov MS. Acute Nutritional Ketosis and Its Implications for Plasma Glucose and Glucoregulatory Peptides in Adults with Prediabetes: A Crossover Placebo-Controlled Randomized Trial. J Nutr 2021; 151:921-929. [PMID: 33561274 DOI: 10.1093/jn/nxaa417] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Revised: 07/30/2020] [Accepted: 12/01/2020] [Indexed: 12/25/2022] Open
Abstract
BACKGROUND The potential of a ketone monoester (β-hydroxybutyrate; KEβHB) supplement to rapidly mimic a state of nutritional ketosis offers a new therapeutic possibility for diabetes prevention and management. While KEβHB supplementation has a glucose-lowering effect in adults with obesity, its impact on glucose control in other insulin-resistant states is unknown. OBJECTIVES The primary objective was to investigate the effect of KEβHB-supplemented drink on plasma glucose in adults with prediabetes. The secondary objective was to determine its impact on plasma glucoregulatory peptides. METHODS This randomized controlled trial [called CETUS (Cross-over randomizEd Trial of β-hydroxybUtyrate in prediabeteS)] included 18 adults [67% men, mean age = 55 y, mean BMI (kg/m2) = 28.4] with prediabetes (glycated hemoglobin between 5.7% and 6.4% and/or fasting plasma glucose between 100 and 125 mg/dL). Participants were randomly assigned to receive KEβHB-supplemented and placebo drinks in a crossover sequence (washout period of 7-10 d between the drinks). Blood samples were collected from 0 to 150 min, at intervals of 30 min. Paired-samples t tests were used to investigate the change in the outcome variables [β-hydroxybutyrate (βHB), glucose, and glucoregulatory peptides] after both drinks. Repeated measures analyses were conducted to determine the change in concentrations of the prespecified outcomes over time. RESULTS Blood βHB concentrations increased to 3.5 mmol/L within 30 minutes after KEβHB supplementation. Plasma glucose AUC was significantly lower after KEβHB supplementation than after the placebo [mean difference (95% CI): -59 (-85.3, -32.3) mmol/L × min]. Compared with the placebo, KEβHB supplementation led to significantly greater AUCs for plasma insulin [0.237 (0.044, 0.429) nmol/L × min], C-peptide [0.259 (0.114, 0.403) nmol/L × min], and glucose-dependent insulinotropic peptide [0.243 (0.085, 0.401) nmol/L × min], with no significant differences in the AUCs for amylin, glucagon, and glucagon-like peptide 1. CONCLUSIONS Ingestion of the KEβHB-supplemented drink acutely increased the blood βHB concentrations and lowered the plasma glucose concentrations in adults with prediabetes. Further research is needed to investigate the dynamics of repeated ingestions of a KEβHB supplement by individuals with prediabetes, with a view to preventing new-onset diabetes. This trial was registered at www.clinicaltrials.gov as NCT03889210.
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Affiliation(s)
- Sakina H Bharmal
- School of Medicine, University of Auckland, Auckland, New Zealand
| | - Jaelim Cho
- School of Medicine, University of Auckland, Auckland, New Zealand
| | | | - Juyeon Ko
- School of Medicine, University of Auckland, Auckland, New Zealand
| | - David Cameron-Smith
- Singapore Institute for Clinical Sciences, Agency for Science, Technology, and Research, Singapore
| | - Maxim S Petrov
- School of Medicine, University of Auckland, Auckland, New Zealand
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11
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Locatelli CAA, Mulvihill EE. Islet Health, Hormone Secretion, and Insulin Responsivity with Low-Carbohydrate Feeding in Diabetes. Metabolites 2020; 10:E455. [PMID: 33187118 PMCID: PMC7697690 DOI: 10.3390/metabo10110455] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2020] [Revised: 11/05/2020] [Accepted: 11/07/2020] [Indexed: 12/25/2022] Open
Abstract
Exploring new avenues to control daily fluctuations in glycemia has been a central theme for diabetes research since the Diabetes Control and Complications Trial (DCCT). Carbohydrate restriction has re-emerged as a means to control type 2 diabetes mellitus (T2DM), becoming increasingly popular and supported by national diabetes associations in Canada, Australia, the USA, and Europe. This approval comes from many positive outcomes on HbA1c in human studies; yet mechanisms underlying their success have not been fully elucidated. In this review, we discuss the preclinical and clinical studies investigating the role of carbohydrate restriction and physiological elevations in ketone bodies directly on pancreatic islet health, islet hormone secretion, and insulin sensitivity. Included studies have clearly outlined diet compositions, including a diet with 30% or less of calories from carbohydrates.
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Affiliation(s)
- Cassandra A. A. Locatelli
- Energy Substrate Laboratory, The University of Ottawa Heart Institute, 40 Ruskin Street, H-3229A, Ottawa, ON KIY 4W7, Canada;
- Department of Biochemistry, Microbiology and Immunology, The University of Ottawa, Faculty of Medicine, 451 Smyth Rd, Ottawa, ON K1H 8L1, Canada
| | - Erin E. Mulvihill
- Energy Substrate Laboratory, The University of Ottawa Heart Institute, 40 Ruskin Street, H-3229A, Ottawa, ON KIY 4W7, Canada;
- Department of Biochemistry, Microbiology and Immunology, The University of Ottawa, Faculty of Medicine, 451 Smyth Rd, Ottawa, ON K1H 8L1, Canada
- Montreal Diabetes Research Centre CRCHUM-Pavillion R, 900 Saint-Denis-Room R08.414, Montreal, QC H2X 0A9, Canada
- Centre for Infection, Immunity and Inflammation, The University of Ottawa, 451 Smyth Rd, Ottawa, ON K1H 8M5, Canada
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12
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Cardiac ketone body metabolism. Biochim Biophys Acta Mol Basis Dis 2020; 1866:165739. [PMID: 32084511 DOI: 10.1016/j.bbadis.2020.165739] [Citation(s) in RCA: 59] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2020] [Revised: 02/11/2020] [Accepted: 02/15/2020] [Indexed: 12/14/2022]
Abstract
The ketone bodies, d-β-hydroxybutyrate and acetoacetate, are soluble 4-carbon compounds derived principally from fatty acids, that can be metabolised by many oxidative tissues, including heart, in carbohydrate-depleted conditions as glucose-sparing energy substrates. They also have important signalling functions, acting through G-protein coupled receptors and histone deacetylases to regulate metabolism and gene expression including that associated with anti-oxidant activity. Their concentration, and hence availability, increases in diabetes mellitus and heart failure. Whilst known to be substrates for ATP production, especially in starvation, their role(s) in the heart, and in heart disease, is uncertain. Recent evidence, reviewed here, indicates that increased ketone body metabolism is a feature of heart failure, and is accompanied by other changes in substrate selection. Whether the change in myocardial ketone body metabolism is adaptive or maladaptive is unknown, but it offers the possibility of using exogenous ketones to treat the failing heart.
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13
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Pujol JB, Christinat N, Ratinaud Y, Savoia C, Mitchell SE, Dioum EHM. Coordination of GPR40 and Ketogenesis Signaling by Medium Chain Fatty Acids Regulates Beta Cell Function. Nutrients 2018; 10:nu10040473. [PMID: 29649104 PMCID: PMC5946258 DOI: 10.3390/nu10040473] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2018] [Revised: 03/26/2018] [Accepted: 04/10/2018] [Indexed: 12/16/2022] Open
Abstract
Diabetes prevalence increases with age, and β-cell dysfunction contributes to the incidence of the disease. Dietary lipids have been recognized as contributory factors in the development and progression of the disease. Unlike long chain triglycerides, medium chain triglycerides (MCT) increase fat burning in animal and human subjects as well as serum C-peptide in type 2 diabetes patients. We evaluated the beneficial effects of MCT on β-cells in vivo and in vitro. MCT improved glycemia in aged rats via β-cell function assessed by measuring insulin secretion and content. In β-cells, medium chain fatty acid (MCFA)-C10 activated fatty acid receptor 1 FFAR1/GPR40, while MCFA-C8 induced mitochondrial ketogenesis and the C8:C10 mixture improved β cell function. We showed that GPR40 signaling positively impacts ketone body production in β-cells, and chronic treatment with β-hydroxybutyrate (BHB) improves β-cell function. We also showed that BHB and MCFA help β-cells recover from lipotoxic stress by improving mitochondrial function and increasing the expression of genes involved in β-cell function and insulin biogenesis, such as Glut2, MafA, and NeuroD1 in primary human islets. MCFA offers a therapeutic advantage in the preservation of β-cell function as part of a preventative strategy against diabetes in at risk populations.
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Affiliation(s)
- Julien Benjamin Pujol
- Islet Function, Nestlé Institute of Health Sciences (NIHS), EPFL Innovation Park, 1015 Lausanne, Switzerland.
| | - Nicolas Christinat
- Lipidomics, Nestlé Institute of Health Sciences (NIHS), EPFL Innovation Park, 1015 Lausanne, Switzerland.
| | - Yann Ratinaud
- Natural Bioactives Screening, Nestlé Institute of Health Sciences (NIHS), EPFL Innovation Park, 1015 Lausanne, Switzerland.
| | - Claudia Savoia
- Islet Function, Nestlé Institute of Health Sciences (NIHS), EPFL Innovation Park, 1015 Lausanne, Switzerland.
| | - Siobhan E Mitchell
- Brain Health, Nestlé Institute of Health Sciences (NIHS), EPFL Innovation Park, 1015 Lausanne, Switzerland.
| | - El Hadji M Dioum
- Islet Function, Nestlé Institute of Health Sciences (NIHS), EPFL Innovation Park, 1015 Lausanne, Switzerland.
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14
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Holdsworth DA, Cox PJ, Kirk T, Stradling H, Impey SG, Clarke K. A Ketone Ester Drink Increases Postexercise Muscle Glycogen Synthesis in Humans. Med Sci Sports Exerc 2018; 49:1789-1795. [PMID: 28398950 PMCID: PMC5556006 DOI: 10.1249/mss.0000000000001292] [Citation(s) in RCA: 58] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Introduction Physical endurance can be limited by muscle glycogen stores, in that glycogen depletion markedly reduces external work. During carbohydrate restriction, the liver synthesizes the ketone bodies, d-β-hydroxybutyrate, and acetoacetate from fatty acids. In animals and in the presence of glucose, d-β-hydroxybutyrate promotes insulin secretion and increases glycogen synthesis. Here we determined whether a dietary ketone ester, combined with plentiful glucose, can increase postexercise glycogen synthesis in human skeletal muscle. Methods After an interval-based glycogen depletion exercise protocol, 12 well-trained male athletes completed a randomized, three-arm, blinded crossover recovery study that consisted of consumption of either a taste-matched, zero-calorie control or a ketone monoester drink, followed by a 10-mM glucose clamp or saline infusion for 2 h. The three postexercise conditions were control drink then saline infusion, control drink then hyperglycemic clamp, or ketone ester drink then hyperglycemic clamp. Skeletal muscle glycogen content was determined in muscle biopsies of vastus lateralis taken before and after the 2-h clamps. Results The ketone ester drink increased blood d-β-hydroxybutyrate concentrations to a maximum of 5.3 versus 0.7 mM for the control drink (P < 0.0001). During the 2-h glucose clamps, insulin levels were twofold higher (31 vs 16 mU·L−1, P < 0.01) and glucose uptake 32% faster (1.66 vs 1.26 g·kg−1, P < 0.001). The ketone drink increased by 61 g, the total glucose infused for 2 h, from 197 to 258 g, and muscle glycogen was 50% higher (246 vs 164 mmol glycosyl units per kilogram dry weight, P < 0.05) than after the control drink. Conclusion In the presence of constant high glucose concentrations, a ketone ester drink increased endogenous insulin levels, glucose uptake, and muscle glycogen synthesis.
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Affiliation(s)
- David A Holdsworth
- 1Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UNITED KINGDOM; and 2Research Institute for Sport and Exercise Sciences, Liverpool John Moore's University, Liverpool, UNITED KINGDOM
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15
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Stubbs BJ, Cox PJ, Evans RD, Santer P, Miller JJ, Faull OK, Magor-Elliott S, Hiyama S, Stirling M, Clarke K. On the Metabolism of Exogenous Ketones in Humans. Front Physiol 2017; 8:848. [PMID: 29163194 PMCID: PMC5670148 DOI: 10.3389/fphys.2017.00848] [Citation(s) in RCA: 235] [Impact Index Per Article: 33.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2017] [Accepted: 10/11/2017] [Indexed: 12/13/2022] Open
Abstract
Background and aims: Currently there is considerable interest in ketone metabolism owing to recently reported benefits of ketosis for human health. Traditionally, ketosis has been achieved by following a high-fat, low-carbohydrate "ketogenic" diet, but adherence to such diets can be difficult. An alternative way to increase blood D-β-hydroxybutyrate (D-βHB) concentrations is ketone drinks, but the metabolic effects of exogenous ketones are relatively unknown. Here, healthy human volunteers took part in three randomized metabolic studies of drinks containing a ketone ester (KE); (R)-3-hydroxybutyl (R)-3-hydroxybutyrate, or ketone salts (KS); sodium plus potassium βHB. Methods and Results: In the first study, 15 participants consumed KE or KS drinks that delivered ~12 or ~24 g of βHB. Both drinks elevated blood D-βHB concentrations (D-βHB Cmax: KE 2.8 mM, KS 1.0 mM, P < 0.001), which returned to baseline within 3-4 h. KS drinks were found to contain 50% of the L-βHB isoform, which remained elevated in blood for over 8 h, but was not detectable after 24 h. Urinary excretion of both D-βHB and L-βHB was <1.5% of the total βHB ingested and was in proportion to the blood AUC. D-βHB, but not L-βHB, was slowly converted to breath acetone. The KE drink decreased blood pH by 0.10 and the KS drink increased urinary pH from 5.7 to 8.5. In the second study, the effect of a meal before a KE drink on blood D-βHB concentrations was determined in 16 participants. Food lowered blood D-βHB Cmax by 33% (Fed 2.2 mM, Fasted 3.3 mM, P < 0.001), but did not alter acetoacetate or breath acetone concentrations. All ketone drinks lowered blood glucose, free fatty acid and triglyceride concentrations, and had similar effects on blood electrolytes, which remained normal. In the final study, participants were given KE over 9 h as three drinks (n = 12) or a continuous nasogastric infusion (n = 4) to maintain blood D-βHB concentrations greater than 1 mM. Both drinks and infusions gave identical D-βHB AUC of 1.3-1.4 moles.min. Conclusion: We conclude that exogenous ketone drinks are a practical, efficacious way to achieve ketosis.
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Affiliation(s)
- Brianna J Stubbs
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
| | - Pete J Cox
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
| | - Rhys D Evans
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
| | - Peter Santer
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
| | - Jack J Miller
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom.,Clarendon Laboratory, Department of Physics, University of Oxford, Oxford, United Kingdom
| | - Olivia K Faull
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
| | - Snapper Magor-Elliott
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
| | | | - Matthew Stirling
- Innovative Physical Organic Solutions (IPOS), University of Huddersfield, Huddersfield, United Kingdom
| | - Kieran Clarke
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
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16
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Stubbs BJ, Cox PJ, Evans RD, Santer P, Miller JJ, Faull OK, Magor-Elliott S, Hiyama S, Stirling M, Clarke K. On the Metabolism of Exogenous Ketones in Humans. Front Physiol 2017. [PMID: 29163194 DOI: 10.3389/fphys.2017.00848,] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Background and aims: Currently there is considerable interest in ketone metabolism owing to recently reported benefits of ketosis for human health. Traditionally, ketosis has been achieved by following a high-fat, low-carbohydrate "ketogenic" diet, but adherence to such diets can be difficult. An alternative way to increase blood D-β-hydroxybutyrate (D-βHB) concentrations is ketone drinks, but the metabolic effects of exogenous ketones are relatively unknown. Here, healthy human volunteers took part in three randomized metabolic studies of drinks containing a ketone ester (KE); (R)-3-hydroxybutyl (R)-3-hydroxybutyrate, or ketone salts (KS); sodium plus potassium βHB. Methods and Results: In the first study, 15 participants consumed KE or KS drinks that delivered ~12 or ~24 g of βHB. Both drinks elevated blood D-βHB concentrations (D-βHB Cmax: KE 2.8 mM, KS 1.0 mM, P < 0.001), which returned to baseline within 3-4 h. KS drinks were found to contain 50% of the L-βHB isoform, which remained elevated in blood for over 8 h, but was not detectable after 24 h. Urinary excretion of both D-βHB and L-βHB was <1.5% of the total βHB ingested and was in proportion to the blood AUC. D-βHB, but not L-βHB, was slowly converted to breath acetone. The KE drink decreased blood pH by 0.10 and the KS drink increased urinary pH from 5.7 to 8.5. In the second study, the effect of a meal before a KE drink on blood D-βHB concentrations was determined in 16 participants. Food lowered blood D-βHB Cmax by 33% (Fed 2.2 mM, Fasted 3.3 mM, P < 0.001), but did not alter acetoacetate or breath acetone concentrations. All ketone drinks lowered blood glucose, free fatty acid and triglyceride concentrations, and had similar effects on blood electrolytes, which remained normal. In the final study, participants were given KE over 9 h as three drinks (n = 12) or a continuous nasogastric infusion (n = 4) to maintain blood D-βHB concentrations greater than 1 mM. Both drinks and infusions gave identical D-βHB AUC of 1.3-1.4 moles.min. Conclusion: We conclude that exogenous ketone drinks are a practical, efficacious way to achieve ketosis.
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Affiliation(s)
- Brianna J Stubbs
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
| | - Pete J Cox
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
| | - Rhys D Evans
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
| | - Peter Santer
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
| | - Jack J Miller
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom.,Clarendon Laboratory, Department of Physics, University of Oxford, Oxford, United Kingdom
| | - Olivia K Faull
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
| | - Snapper Magor-Elliott
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
| | | | - Matthew Stirling
- Innovative Physical Organic Solutions (IPOS), University of Huddersfield, Huddersfield, United Kingdom
| | - Kieran Clarke
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
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17
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O’Malley T, Myette-Cote E, Durrer C, Little JP. Nutritional ketone salts increase fat oxidation but impair high-intensity exercise performance in healthy adult males. Appl Physiol Nutr Metab 2017; 42:1031-1035. [DOI: 10.1139/apnm-2016-0641] [Citation(s) in RCA: 67] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
This study investigated the impact of raising plasma beta-hydroxybutyrate (β-OHB) through ingestion of ketone salts on substrate oxidation and performance during cycling exercise. Ten healthy adult males (age, 23 ± 3 years; body mass index, 25 ± 3 kg/m2, peak oxygen uptake, 45 ± 10 mL/(kg·min)−1) were recruited to complete 2 experimental trials. Before enrollment in the experimental conditions, baseline anthropometrics and cardiorespiratory fitness (peak oxygen uptake) were assessed and familiarization to the study protocol was provided. On experimental days, participants reported to the laboratory in the fasted state and consumed either 0.3 g/kg β-OHB ketone salts or a flavour-matched placebo at 30 min prior to engaging in cycling exercise. Subjects completed steady-state exercise at 30%, 60%, and 90% ventilatory threshold (VT) followed by a 150-kJ cycling time-trial. Respiratory exchange ratio (RER) and total substrate oxidation were derived from indirect calorimetry. Plasma glucose, lactate, and ketones were measured at baseline, 30 min post-supplement, post–steady-state exercise, and immediately following the time-trial. Plasma β-OHB was elevated from baseline and throughout the entire protocol in the ketone condition (p < 0.05). RER was lower at 30% and 60% VT in the ketone compared with control condition. Total fat oxidation was greater in the ketone versus control (p = 0.05). Average time-trial power output was ∼7% lower (–16 W, p = 0.029) in the ketone condition. Ingestion of ketone salts prior to exercise increases fat oxidation during steady-state exercise but impairs high-intensity exercise performance.
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Affiliation(s)
- Trevor O’Malley
- School of Health and Exercise Sciences, University of British Columbia Okanagan, Kelowna, BC V1V 1V7, Canada
- School of Health and Exercise Sciences, University of British Columbia Okanagan, Kelowna, BC V1V 1V7, Canada
| | - Etienne Myette-Cote
- School of Health and Exercise Sciences, University of British Columbia Okanagan, Kelowna, BC V1V 1V7, Canada
- School of Health and Exercise Sciences, University of British Columbia Okanagan, Kelowna, BC V1V 1V7, Canada
| | - Cody Durrer
- School of Health and Exercise Sciences, University of British Columbia Okanagan, Kelowna, BC V1V 1V7, Canada
- School of Health and Exercise Sciences, University of British Columbia Okanagan, Kelowna, BC V1V 1V7, Canada
| | - Jonathan P. Little
- School of Health and Exercise Sciences, University of British Columbia Okanagan, Kelowna, BC V1V 1V7, Canada
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18
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Sampson M, Lathen DR, Dallon BW, Draney C, Ray JD, Kener KB, Parker BA, Gibbs JL, Gropp JS, Tessem JS, Bikman BT. β-Hydroxybutyrate improves β-cell mitochondrial function and survival. JOURNAL OF INSULIN RESISTANCE 2017. [DOI: 10.4102/jir.v2i1.25] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
Pharmacological interventions aimed at improving outcomes in type 2 diabetes and achieving normoglycaemia, including insulin therapy, are increasingly common, despite the potential for substantial side effects. Carbohydrate-restricted diets that result in increased ketogenesis have effectively been used to improve insulin resistance, a fundamental feature of type 2 diabetes. In addition, limited evidence suggests that states of ketogenesis may also improve β-cell function in type 2 diabetics. Considering how little is known regarding the effects of ketones on β-cell function, we sought to determine the specific effects of β-Hydroxybutyrate (βHB) on pancreatic β-cell physiology and mitochondrial function. βHB treatment increased β-cell survival and proliferation, while also increasing mitochondrial mass, respiration and adenosine triphosphate (ATP) production. Despite these improvements, were unable to detect an increase in β-cell or islet insulin production and secretion. Collectively, these findings have two implications. Firstly, they indicate that β-cells have improved survival and proliferation in the midst of βHB, the circulating form of ketones. Secondly, insulin secretion does not appear to be directly related to apparent improvements in mitochondrial function and cellular proliferation.
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19
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Hepler C, Foy CE, Higgins MR, Renquist BJ. The hypophagic response to heat stress is not mediated by GPR109A or peripheral β-OH butyrate. Am J Physiol Regul Integr Comp Physiol 2016; 310:R992-8. [PMID: 26936786 DOI: 10.1152/ajpregu.00513.2015] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2015] [Accepted: 03/01/2016] [Indexed: 01/09/2023]
Abstract
Rising temperatures resulting from climate change will increase the incidence of heat stress, negatively impacting the labor force and food animal production. Heat stress elevates circulating β-OH butyrate, which induces vasodilation through GPR109a. Interestingly, both heat stress and intraperitoneal β-OH butyrate administration induce hypophagia. Thus, we aimed to investigate the role of β-OH butyrate in heat stress hypophagia in mice. We found that niacin, a β-OH butyrate mimetic that cannot be oxidized to generate ATP, also reduces food intake. Interestingly, the depression in food intake as a result of 8-h intraperitoneal niacin or 48-h heat exposure did not result from changes in hypothalamic expression of orexigenic or anorexigenic signals (AgRP, NPY, or POMC). Genetically eliminating GPR109a expression did not prevent the hypophagic response to heat exposure, intraperitoneal β-OH butyrate (5.7 mmol/kg), or niacin (0.8 mmol/kg). Hepatic vagotomy eliminated the hypophagic response to β-OH butyrate and niacin but did not affect the hypophagic response to heat exposure. We subsequently hypothesized that the hypophagic response to heat stress may depend on direct effects of β-OH butyrate at the central nervous system: β-OH butyrate induced hormonal changes (hyperinsulinemia, hypercorticosteronemia, and hyperleptinemia), or gene expression changes. To test these possibilities, we blocked expression of hepatic hydroxyl methyl glutaryl CoA synthase II (HMGCS2) to prevent hepatic β-OH butyrate synthesis. Mice that lack HMGCS2 maintain a hypophagic response to heat stress. Herein, we establish that the hypophagia of heat stress is independent of GPR109a, the hepatic vagus afferent nerve, and hepatic ketone body synthesis.
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Affiliation(s)
- Chelsea Hepler
- School of Animal and Comparative Biomedical Sciences, University of Arizona, Tucson, Arizona
| | - Caroline E Foy
- School of Animal and Comparative Biomedical Sciences, University of Arizona, Tucson, Arizona
| | - Mark R Higgins
- School of Animal and Comparative Biomedical Sciences, University of Arizona, Tucson, Arizona
| | - Benjamin J Renquist
- School of Animal and Comparative Biomedical Sciences, University of Arizona, Tucson, Arizona
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20
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Akbar H, Batistel F, Drackley JK, Loor JJ. Alterations in Hepatic FGF21, Co-Regulated Genes, and Upstream Metabolic Genes in Response to Nutrition, Ketosis and Inflammation in Peripartal Holstein Cows. PLoS One 2015; 10:e0139963. [PMID: 26451842 PMCID: PMC4599736 DOI: 10.1371/journal.pone.0139963] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2015] [Accepted: 09/18/2015] [Indexed: 12/29/2022] Open
Abstract
In rodents, fibroblast growth factor 21 (FGF21) has emerged as a key metabolic regulator produced by liver. To gather preliminary data on the potential importance of FGF1, co-regulated genes, and upstream metabolic genes, we examined the hepatic mRNA expression in response to nutrition and inflammation in dairy cows. In experiment 1, induction of ketosis through feed restriction on d 5 postpartum upregulated FGF21, its co-receptor KLB, and PPARA but only elicited a numerical increase in serum FGF21 concentration. In experiment 2, cows in control (CON) or receiving 50 g/d of L-carnitine (C50) from -14 through 21 d had increased FGF21, PPARA, and NFIL3 on d 10 compared with d 2 postpartum. In contrast, compared with CON and C50, 100 g/d L-carnitine (C100) resulted in lower FGF21, KLB, ANGPTL4, and ARNTL expression on d 10. In experiment 3, cows were fed during the dry period either a higher-energy (OVE; 1.62 Mcal/kg DM) or lower-energy (CON; 1.34 Mcal/kg DM) diet and received 0 (OVE:N, CON:N) or 200 μg of LPS (OVE:Y, CON:Y) into the mammary gland at d 7 postpartum. For FGF21 mRNA expression in CON, the LPS challenge (CON:Y) prevented a decrease in expression between d 7 and 14 postpartum such that cows in CON:N had a 4-fold lower expression on d 14 compared with d 7. The inflammatory stimulus induced by LPS in CON:Y resulted in upregulation of PPARA on d 14 to a similar level as cows in OVE:N. In OVE:Y, expression of PPARA was lower than CON:N on d 7 and remained unchanged on d 14. On d 7, LPS led to a 4-fold greater serum FGF21 only in OVE but not in CON cows. In fact, OVE:Y reached the same serum FGF21 concentration as CON:N, suggesting a carryover effect of dietary energy level on signaling mechanisms within liver. Overall, results indicate that nutrition, ketosis, and inflammation during the peripartal period can alter hepatic FGF21, co-regulated genes, and upstream metabolic genes to various extents. The functional outcome of these changes merits further study, and in particular the mechanisms regulating transcription in response to changes in energy balance and feed intake.
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Affiliation(s)
- Haji Akbar
- Department of Animal Sciences and Division of Nutritional Sciences, University of Illinois, Urbana, Illinois, United States of America
| | - Fernanda Batistel
- Department of Animal Sciences and Division of Nutritional Sciences, University of Illinois, Urbana, Illinois, United States of America
| | - James K. Drackley
- Department of Animal Sciences and Division of Nutritional Sciences, University of Illinois, Urbana, Illinois, United States of America
| | - Juan J. Loor
- Department of Animal Sciences and Division of Nutritional Sciences, University of Illinois, Urbana, Illinois, United States of America
- * E-mail:
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Puisac B, Arnedo M, Casale CH, Ribate MP, Castiella T, Ramos FJ, Ribes A, Pérez-Cerdá C, Casals N, Hegardt FG, Pié J. Differential HMG-CoA lyase expression in human tissues provides clues about 3-hydroxy-3-methylglutaric aciduria. J Inherit Metab Dis 2010; 33:405-10. [PMID: 20532825 PMCID: PMC2903694 DOI: 10.1007/s10545-010-9097-3] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/29/2009] [Revised: 03/30/2010] [Accepted: 04/01/2010] [Indexed: 12/31/2022]
Abstract
3-Hydroxy-3-methylglutaric aciduria is a rare human autosomal recessive disorder caused by deficiency of 3-hydroxy-3-methylglutaryl CoA lyase (HL). This mitochondrial enzyme catalyzes the common final step of leucine degradation and ketogenesis. Acute symptoms include vomiting, seizures and lethargy, accompanied by metabolic acidosis and hypoketotic hypoglycaemia. Such organs as the liver, brain, pancreas, and heart can also be involved. However, the pathophysiology of this disease is only partially understood. We measured mRNA levels, protein expression and enzyme activity of human HMG-CoA lyase from liver, kidney, pancreas, testis, heart, skeletal muscle, and brain. Surprisingly, the pancreas is, after the liver, the tissue with most HL activity. However, in heart and adult brain, HL activity was not detected in the mitochondrial fraction. These findings contribute to our understanding of the enzyme function and the consequences of its deficiency and suggest the need for assessment of pancreatic damage in these patients.
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Affiliation(s)
- Beatriz Puisac
- Laboratory of Clinical Genetics and Functional Genomics, Department of Pharmacology and Physiology, School of Medicine, University of Zaragoza, C/ Domingo Miral s/n, 50009 Zaragoza, Spain
| | - María Arnedo
- Laboratory of Clinical Genetics and Functional Genomics, Department of Pharmacology and Physiology, School of Medicine, University of Zaragoza, C/ Domingo Miral s/n, 50009 Zaragoza, Spain
| | - Cesar H. Casale
- Department of Molecular Biology, National University of Rio Cuarto, 5800 Rio Cuarto, Cordoba Argentina
| | - María Pilar Ribate
- Laboratory of Clinical Genetics and Functional Genomics, Department of Pharmacology and Physiology, School of Medicine, University of Zaragoza, C/ Domingo Miral s/n, 50009 Zaragoza, Spain
| | - Tomás Castiella
- Department of Pathology, School of Medicine, University of Zaragoza, 50009 Zaragoza, Spain
| | - Feliciano J. Ramos
- Laboratory of Clinical Genetics and Functional Genomics, Department of Pharmacology and Physiology, School of Medicine, University of Zaragoza, C/ Domingo Miral s/n, 50009 Zaragoza, Spain
| | - Antonia Ribes
- Division of Inborn Errors of Metabolism (IBC), Department of Biochemistry and Molecular Genetics, Hospital Clinic and CIBERER, 08036 Barcelona, Spain
| | - Celia Pérez-Cerdá
- Department of Molecular Biology, Molecular Biological Center Severo Ochoa CSIC-UAM, University Autonoma of Madrid, CIBERER, 28049 Madrid, Spain
| | - Nuria Casals
- Department of Biochemistry and Molecular Biology, School of Health Sciences, International University of Catalonia, 08190 Sant Cugat, Barcelona Spain
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBEROBN), Instituto de la Salud Carlos III, 28029 Madrid, Spain
| | - Fausto G. Hegardt
- Department of Biochemistry and Molecular Biology, School of Pharmacy, University of Barcelona, 08028 Barcelona, Spain
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBEROBN), Instituto de la Salud Carlos III, 28029 Madrid, Spain
| | - Juan Pié
- Laboratory of Clinical Genetics and Functional Genomics, Department of Pharmacology and Physiology, School of Medicine, University of Zaragoza, C/ Domingo Miral s/n, 50009 Zaragoza, Spain
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22
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Martens GA, Pipeleers D. Glucose, regulator of survival and phenotype of pancreatic beta cells. VITAMINS AND HORMONES 2009; 80:507-39. [PMID: 19251048 DOI: 10.1016/s0083-6729(08)00617-1] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
The key role of glucose in regulating insulin release by the pancreatic beta cell population is not only dependent on acute stimulus-secretion coupling mechanisms but also on more long-term influences on beta cell survival and phenotype. Glucose serves as a major survival factor for beta cells via at least three actions: it prevents an oxidative redox state, it suppresses a mitochondrial apoptotic program that is triggered at reduced mitochondrial metabolic activity and it induces genes needed for the cellular responsiveness to glucose and to growth factors. Glucose-regulated pathways may link protein synthetic and proliferative activities, making glucose a permissive factor for beta cell proliferation, in check with metabolic needs. Conditions of inadequate glucose metabolism in beta cells are not only leading to deregulation of acute secretory responses but should also be considered as causes for increased apoptosis and reduced formation of beta cells, and loss of their normal differentiated state.
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23
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Volek JS, Fernandez ML, Feinman RD, Phinney SD. Dietary carbohydrate restriction induces a unique metabolic state positively affecting atherogenic dyslipidemia, fatty acid partitioning, and metabolic syndrome. Prog Lipid Res 2008; 47:307-18. [DOI: 10.1016/j.plipres.2008.02.003] [Citation(s) in RCA: 159] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2007] [Revised: 02/22/2008] [Accepted: 02/29/2008] [Indexed: 01/14/2023]
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24
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Morgan LM, Flatt PR, Marks V. Nutrient Regulation of the Enteroinsular Axis And Insulin Secretion. Nutr Res Rev 2007; 1:79-97. [DOI: 10.1079/nrr19880008] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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25
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Duska F, Tůma P, Mokrejs P, Kubena A, Andel M. Analysis of factors influencing nitrogen balance during acute starvation in obese subject with and without type 2 diabetes. Clin Nutr 2007; 26:552-8. [PMID: 17374420 DOI: 10.1016/j.clnu.2007.01.011] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2006] [Revised: 12/31/2006] [Accepted: 01/25/2007] [Indexed: 11/22/2022]
Abstract
BACKGROUND & AIMS Patients with type 2 diabetes (T2DM) tend to loose more lean body mass during both long-term weight reduction and short-term very-low-calorie diet. We ask what factors influence protein loss during acute starvation in T2DM. METHODS In a prospective in-hospital observational study, we compared 10 subjects with T2DM and 10 age-weight-sex matched obese controls (OB) during 60 h of fasting and used frequent blood sampling and indirect calorimetry to describe metabolic and endocrine response. We analyzed factors influencing nitrogen balance using stepwise multiple regressions. RESULTS Despite comparable pattern of plasma insulin, free fatty acid, 3-hydroxybutyrate and almost identical behavior of growth hormone axis, our T2DM subjects remained hyperglycaemic and in contrast to OB subjects they failed to reduce the rate of protein oxidation, even though muscle protein breakdown rate declined similarly in both groups. Regression analysis revealed that protein oxidation rate in T2DM group was enhanced by hyperglycemia and sympathetic activity and suppressed by circulating insulin and 3-hydroxybutyrate. Liver insulin resistance increases peripheral insulin concentrations and enhances the conversion of non-esterified fatty acids (NEFA) to ketones and thus it might be a protein-saving factor. CONCLUSION Relative deficiency of circulating insulin and hyperglycemia play a pivotal role in the impairment of protein sparing in T2DM during a short-term fasting.
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Affiliation(s)
- Frantisek Duska
- Department of Internal Medicine II, 3rd Faculty of Medicine, Charles University, Prague, Czech Republic.
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26
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Takehiro M, Fujimoto S, Shimodahira M, Shimono D, Mukai E, Nabe K, Radu RG, Kominato R, Aramaki Y, Seino Y, Yamada Y. Chronic exposure to beta-hydroxybutyrate inhibits glucose-induced insulin release from pancreatic islets by decreasing NADH contents. Am J Physiol Endocrinol Metab 2005; 288:E372-80. [PMID: 15479955 DOI: 10.1152/ajpendo.00157.2004] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
To investigate the effects of chronic exposure to ketone bodies on glucose-induced insulin secretion, we evaluated insulin release, intracellular Ca2+ and metabolism, and Ca2+ efficacy of the exocytotic system in rat pancreatic islets. Fifteen-hour exposure to 5 mM d-beta-hydroxybutyrate (HB) reduced high glucose-induced insulin secretion and augmented basal insulin secretion. Augmentation of basal release was derived from promoting the Ca2+-independent and ATP-independent component of insulin release, which was suppressed by the GDP analog. Chronic exposure to HB affected mostly the second phase of glucose-induced biphasic secretion. Dynamic experiments showed that insulin release and NAD(P)H fluorescence were lower, although the intracellular Ca2+ concentration ([Ca2+](i)) was not affected 10 min after exposure to high glucose. Additionally, [Ca2+](i) efficacy in exocytotic system at clamped concentrations of ATP was not affected. NADH content, ATP content, and ATP-to-ADP ratio in the HB-cultured islets in the presence of high glucose were lower, whereas glucose utilization and oxidation were not affected. Mitochondrial ATP production shows that the respiratory chain downstream of complex II is not affected by chronic exposure to HB, and that the decrease in ATP production is due to decreased NADH content in the mitochondrial matrix. Chronic exposure to HB suppresses glucose-induced insulin secretion by lowering the ATP level, at least partly by inhibiting ATP production by reducing the supply of NADH to the respiratory chain. Glucose-induced insulin release in the presence of aminooxyacetate was not reduced, which implies that chronic exposure to HB affects the malate/aspartate shuttle and thus reduces NADH supply to mitochondria.
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Affiliation(s)
- Mihoko Takehiro
- Dept. of Diabetes and Clinical Nutrition, Graduate School of Medicine, Kyoto University, 54 Shogoin Kawahara-cho, Sakyo-ku, Kyoto 606-8507, Japan
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28
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Murdock DJL, Clarke J, Flatt PR, Barnett YA, Barnett CR. Role of CYP2E1 in ketone-stimulated insulin release in pancreatic B-cells. Biochem Pharmacol 2004; 67:875-84. [PMID: 15104240 DOI: 10.1016/j.bcp.2003.10.011] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The role of CYP2E1 in ketone-stimulated insulin release was investigated using isolated pancreatic islets of Langerhans and two mammalian insulin secreting pancreatic beta-cell lines engineered to stably express human CYP2E1 (designated BRIN BD11h2E1 and INS-1h2E1). Isolated rat pancreatic islets were shown to express the CYP2E1 isoform which was inducible by pretreatment of animals with acetone. The cDNA encoded CYP2E1 was expressed and inducible in the engineered cells as shown by Western blotting. The transfected protein was enzymatically active in the heterologous cells as determined by p-nitrophenol hydroxylation rates (0.176 +/- 0.08 vs. 0.341 +/- 0.08 nmol/min/mg microsomal protein in BRIN BD11 control cells and BRIN BD11h2E1 cells respectively, P < 0.001; 0.204 +/- 0.03 vs. 0.633 +/- 0.102 nmol/min/mg microsomal protein in INS-1 and INS-1h2E1, respectively, P < 0.001). Cultivation of CYP2E1 expressing BRIN BD11h2E1 and INS-1h2E1 cells in 40 mM ethanol increased the rate of p-nitrophenol hydroxylation (0.968 +/- 0.09 nmol/min/mg microsomal protein, P < 0.001 and 0.846 +/- 0.103 nmol/min/mg microsomal protein, P < 0.001, respectively) providing further evidence that the heterologous protein is inducible. Cultivation of control cells with ethanol had no observable effect (0.186 +/- 0.05 and 0.195 +/- 0.03 in BRIN BD11 and INS-1, respectively). These cell lines also express NADPH-cytochrome P450 reductase protein which was enzymatically active (0.632 +/- 0.023 in parental BRIN BD11 vs. 0.657 +/- 0.066 without ethanol and 0.824 +/- 0.014 nmol/min/mg microsomal protein with ethanol in BRIN BD11h2E1, P < 0.05; and 1.568 +/- 0.118 in parental INS-1 vs. 1.607 +/- 0.093 without ethanol and 1.805 +/- 0.066 nmol/min/mg microsomal protein with ethanol in INS-1h2E1, P < 0.05) thereby providing a functional cytochrome P450 system. The insulin secretory response of control cell lines and islets was similar to cell lines and islets which had been chemically pretreated, to induce CYP2E1 expression, in response to known nutrient secretagogues. However, insulin output was significantly higher in pretreated islets (1.3-fold, P < 0.05) and CYP2E1 expressing cell lines (BRIN BD11h2E1 2.3-fold, P < 0.001; INS1-1h2E1 1.6-fold, P < 0.001) when stimulated with the ketone 3-hydroxybutyrate than control islets and parental cell lines respectively. Similar acute exposure to acetoacetate enhanced insulin secretion by 1.3-fold (P < 0.05) in pretreated islets, 2.6-fold (P < 0.001) in ethanol pretreated BRIN BD11h2E1 and 1.4-fold (P < 0.001) in ethanol pretreated INS-1h2E1 cells compared to the respective control islets or ethanol pretreated control parental cells. Therefore, these studies highlight a possible role for CYP2E1 in pancreatic cell dysfunction.
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Affiliation(s)
- Diane J Lees Murdock
- School of Biomedical Sciences, University of Ulster, Coleraine, Co. Londonderry, N. Ireland, BT52 1SA, UK.
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29
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Yaney GC, Corkey BE. Fatty acid metabolism and insulin secretion in pancreatic beta cells. Diabetologia 2003; 46:1297-312. [PMID: 13680127 DOI: 10.1007/s00125-003-1207-4] [Citation(s) in RCA: 185] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/14/2003] [Revised: 07/14/2003] [Indexed: 01/16/2023]
Abstract
Increases in glucose or fatty acids affect metabolism via changes in long-chain acyl-CoA formation and chronically elevated fatty acids increase total cellular CoA. Understanding the response of pancreatic beta cells to increased amounts of fuel and the role that altered insulin secretion plays in the development and maintenance of obesity and Type 2 diabetes is important. Data indicate that the activated form of fatty acids acts as an effector molecule in stimulus-secretion coupling. Glucose increases cytosolic long-chain acyl-CoA because it increases the "switch" compound malonyl-CoA that blocks mitochondrial beta-oxidation, thus implementing a shift from fatty acid to glucose oxidation. We present arguments in support of the following: (i) A source of fatty acid either exogenous or endogenous (derived by lipolysis of triglyceride) is necessary to support normal insulin secretion; (ii) a rapid increase of fatty acids potentiates glucose-stimulated secretion by increasing fatty acyl-CoA or complex lipid concentrations that act distally by modulating key enzymes such as protein kinase C or the exocytotic machinery; (iii) a chronic increase of fatty acids enhances basal secretion by the same mechanism, but promotes obesity and a diminished response to stimulatory glucose; (iv) agents which raise cAMP act as incretins, at least in part, by stimulating lipolysis via beta-cell hormone-sensitive lipase activation. Furthermore, increased triglyceride stores can give higher rates of lipolysis and thus influence both basal and stimulated insulin secretion. These points highlight the important roles of NEFA, LC-CoA, and their esterified derivatives in affecting insulin secretion in both normal and pathological states.
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Affiliation(s)
- G C Yaney
- Boston University School of Medicine, Obesity Research Center, 650 Albany Street, Boston, MA 02118, USA
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30
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Abstract
Nutrient secretagogues can increase the production of succinyl-CoA in rat pancreatic islets. When succinate esters are the secretagogue, succinyl-CoA can be generated via the succinate thiokinase reaction. Other secretagogues can increase production of succinyl-CoA secondary to increasing alpha-ketoglutarate production by glutamate dehydrogenase or mitochondrial aspartate aminotransferase followed by the alpha-ketoglutarate dehydrogenase reaction. Although secretagogues can increase the production of succinyl-CoA, they do not increase the level of this metabolite until after they decrease the level of 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA). This suggests that the generated succinyl-CoA initially reacts with acetoacetate to yield acetoacetyl-CoA plus succinate in the succinyl-CoA-acetoacetate transferase reaction. This would be followed by acetoacetyl-CoA reacting with acetyl-CoA to generate HMG-CoA in the HMG-CoA synthetase reaction. HMG-CoA will then be reduced by NADPH to mevalonate in the HMG-CoA reductase reaction and/or cleaved to acetoacetate plus acetyl-CoA by HMG cleavage enzyme. Succinate derived from either exogenous succinate esters or generated by succinyl-CoA-acetoacetate transferase is metabolized to malate followed by the malic enzyme reaction. Increased production of NADPH by the latter reaction then increases reduction of HMG-CoA and accounts for the decrease in the level of HMG-CoA produced by secretagogues. Pyruvate carboxylation catalyzed by pyruvate carboxylase will supply oxaloacetate to mitochondrial aspartate aminotransferase. This would enable this aminotransferase to supply alpha-ketoglutarate to the alpha-ketoglutarate dehydrogenase complex and would, in part, account for secretagogues increasing the islet level of succinyl-CoA after they decrease the level of HMG-CoA. Mevalonate could be a trigger of insulin release as a result of its ability to alter membrane proteins and/or cytosolic Ca(2+). This is consistent with the fact that insulin secretagogues decrease the level of the mevalonate precursor HMG-CoA. In addition, inhibitors of HMG-CoA reductase interfere with insulin release and this inhibition can be reversed by mevalonate.
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Affiliation(s)
- Leonard A Fahien
- Department of Pharmacology, University of Wisconsin Medical School, Madison, Wisconsin 53706, USA.
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31
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Regulation of Ketogenesis in Liver. Compr Physiol 2001. [DOI: 10.1002/cphy.cp070221] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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32
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Flatt PR, Barnett CR, Shibier O, Swanston-Flatt SK. Direct and indirect actions of nutrients in the regulation of insulin secretion from the pancreatic beta cells. Proc Nutr Soc 1991; 50:559-66. [PMID: 1809964 DOI: 10.1079/pns19910069] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
- P R Flatt
- Biomedical Sciences Research Centre, University of Ulster, Coleraine, Northern Ireland
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33
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Thompson JR, Wu G. The effect of ketone bodies on nitrogen metabolism in skeletal muscle. COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY. B, COMPARATIVE BIOCHEMISTRY 1991; 100:209-16. [PMID: 1799962 DOI: 10.1016/0305-0491(91)90363-i] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
1. The ketone bodies, D-beta-hydroxybutyrate and acetoacetate, inhibit glycolysis thereby reducing pyruvate availability which leads to a marked inhibition of branched-chain amino acid metabolism and alanine synthesis in skeletal muscles from fasted mammalian and avian species. 2. The rate of glutamine release from skeletal muscles from fasted birds is increased at the expense of alanine in the presence of elevated concentrations of ketone bodies because of an increase in the availability of glutamate for glutamine synthesis. 3. Ketone bodies inhibit both protein synthesis and protein degradation in skeletal muscles from fasted mammalian and avian species in vitro. The mechanisms involved remain unknown. 4. Inhibition of amino acid metabolism and protein turnover in skeletal muscle by ketone bodies may be an important survival mechanism during adaptation to catabolic states such as prolonged fasting.
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Affiliation(s)
- J R Thompson
- Department of Animal Science, University of Alberta, Edmonton, Canada
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34
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Malaisse WJ, Lebrun P, Yaylali B, Camara J, Valverde I, Sener A. Ketone bodies and islet function: 45Ca handling, insulin synthesis, and release. THE AMERICAN JOURNAL OF PHYSIOLOGY 1990; 259:E117-22. [PMID: 2196820 DOI: 10.1152/ajpendo.1990.259.1.e117] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
D-(-)-beta-Hydroxybutyrate and acetoacetate cause a rapid, sustained, and rapidly reversible stimulation of insulin release from rat pancreatic islets incubated in the presence, but not absence, of D-glucose. This coincides with stimulation of both proinsulin biosynthesis and 45Ca net uptake. The ketone bodies also decrease 45Ca outflow from prelabeled islets perifused in the absence of Ca2+ and, in contrast, enhance effluent radioactivity in the presence of Ca2+. In the presence of D-glucose, the secretory response to D-(-)-beta-hydroxybutyrate is concentration related in the 2.5-20 mM range, abolished in the absence of Ca2+ or presence of KCN, and enhanced by theophylline and forskolin. It corresponds grossly to a shift to the left of the sigmoidal curve relating insulin output to the ambient concentration of D-glucose. The secretory, biosynthetic, and cationic response to acetoacetate is less marked than that evoked by an equimolar concentration of D-(-)-beta-hydroxybutyrate. These features are compatible with the view that the insulinotropic action of ketone bodies would be causally linked to their metabolism in islet cells.
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Affiliation(s)
- W J Malaisse
- Laboratory of Experimental Medicine, Brussels Free University, Belgium
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Malaisse WJ, Lebrun P, Rasschaert J, Blachier F, Yilmaz T, Sener A. Ketone bodies and islet function: 86Rb handling and metabolic data. THE AMERICAN JOURNAL OF PHYSIOLOGY 1990; 259:E123-30. [PMID: 2196821 DOI: 10.1152/ajpendo.1990.259.1.e123] [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
The metabolism of ketone bodies was investigated in rat pancreatic islets incubated in the absence or presence of D-glucose. The generation of 14CO2 from 3-14C-labeled ketone bodies, the interconversion of D-(-)-beta-hydroxybutyrate and acetoacetate (AcAc), the reciprocal effects of ketone bodies and D-glucose on their respective catabolism, and the influence of these exogenous nutrients on the output of 14CO2 from islets preincubated with either L-[U-14C]glutamine or [U-14C]palmitate provided an estimation of the nutrient-induced changes in O2 uptake that was in fair agreement with the observed modifications of islet respiration. There was a close correlation between such changes and the corresponding values for insulin output. Because the stimulation of insulin release by ketone bodies also coincided with a decrease in 86Rb outflow from prelabeled islets, these findings suggest that the insulinotropic action of ketone bodies is causally linked to their catabolism through an increase in ATP generation rate and a subsequent decrease in K+ conductance. A complementary participation of changes in mitochondrial redox state to stimulus-secretion coupling is considered, however, in the light of comparisons between the effects of D-(-)-beta-hydroxybutyrate and AcAc, respectively, on mitochondrial NADH generation, 45Ca net uptake, and D-[6-14C]glucose oxidation.
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Affiliation(s)
- W J Malaisse
- Laboratory of Experimental Medicine, Brussels Free University, Belgium
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Ikeda T, Yoshida T, Ito Y, Murakami I, Mokuda O, Tominaga M, Mashiba H. Effect of beta-hydroxybutyrate and acetoacetate on insulin and glucagon secretion from perfused rat pancreas. Arch Biochem Biophys 1987; 257:140-3. [PMID: 3307630 DOI: 10.1016/0003-9861(87)90552-2] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
To elucidate the physiological significance of ketone bodies on insulin and glucagon secretion, the direct effects of beta-hydroxybutyrate (BOHB) and acetoacetate (AcAc) infusion on insulin and glucagon release from perfused rat pancreas were investigated. The BOHB or AcAc was administered at concentrations of 10, 1, or 0.1 mM for 30 min at 4.0 ml/min. High-concentration infusions of BOHB and AcAc (10 mM) produced significant increases in insulin release in the presence of 4.4 mM glucose, but low-concentration infusions of BOHB and AcAc (1 and 0.1 mM) caused no significant changes in insulin secretion from perfused rat pancreas. BOHB (10, 1, and 0.1 mM) and AcAc (10 and 1 mM) infusion significantly inhibited glucagon secretion from perfused rat pancreas. These results suggest that physiological concentrations of ketone bodies have no direct effect on insulin release but have a direct inhibitory effect on glucagon secretion from perfused rat pancreas.
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37
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Meglasson MD, Matschinsky FM. Pancreatic islet glucose metabolism and regulation of insulin secretion. DIABETES/METABOLISM REVIEWS 1986; 2:163-214. [PMID: 2943567 DOI: 10.1002/dmr.5610020301] [Citation(s) in RCA: 371] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
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