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Dessureault LM, Tod RA, McClelland GB. Metabolic recovery from submaximal exercise in hypoxia acclimated high altitude deer mice (Peromyscus maniculatus). Comp Biochem Physiol B Biochem Mol Biol 2024; 274:111004. [PMID: 38945522 DOI: 10.1016/j.cbpb.2024.111004] [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: 03/21/2024] [Revised: 06/17/2024] [Accepted: 06/23/2024] [Indexed: 07/02/2024]
Abstract
Animals living at high-altitude are faced with unremitting low oxygen availability. This can make it difficult to perform daily tasks that require increases in aerobic metabolism. An activity important for survival is aerobic locomotion, and the rapid recovery of muscle metabolism post exercise. Past work shows that hypoxia acclimated high-altitude mice (Peromyscus maniculatus) have a greater reliance on carbohydrates to power exercise than low altitude mice. However, it is unclear how quickly after aerobic exercise these mice can recovery and replenish muscle glycogen stores. The gastrocnemius muscle of high-altitude deer mice has a more aerobic phenotype and a greater capacity to oxidize lipids than low altitude deer mice. This suggests that high altitude mice may recover more rapidly from exercise than their lowland counterparts due to a greater capacity to support glycogen replenishment using intramuscular triglycerides (IMTG). To explore this possibility, we used low- and high-altitude native deer mice born and raised in common lab conditions and acclimated to chronic hypoxia. We determined changes in oxygen consumption following 15 min of aerobic exercise in 12% O2 and sampled skeletal muscles and liver at various time points during recovery to examine changes in key metabolites, including glycogen and IMTG. We found depletion in glycogen stores during exercise only in lowlanders, which returned to resting levels following 90 min of recovery. In contrast, IMTG did not change significantly with exercise or during recovery in either population. These data suggest that exercise recovery is influenced by altitude ancestry in deer mice.
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Affiliation(s)
- Lauren M Dessureault
- Department of Biology, McMaster University, 1280 Main Street West, Hamilton, Ontario L8S 4K1, Canada
| | - Reegan A Tod
- Department of Biology, McMaster University, 1280 Main Street West, Hamilton, Ontario L8S 4K1, Canada
| | - Grant B McClelland
- Department of Biology, McMaster University, 1280 Main Street West, Hamilton, Ontario L8S 4K1, Canada.
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2
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Hughey CC, Bracy DP, Rome FI, Goelzer M, Donahue EP, Viollet B, Foretz M, Wasserman DH. Exercise training adaptations in liver glycogen and glycerolipids require hepatic AMP-activated protein kinase in mice. Am J Physiol Endocrinol Metab 2024; 326:E14-E28. [PMID: 37938177 PMCID: PMC11193517 DOI: 10.1152/ajpendo.00289.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/01/2023] [Revised: 11/06/2023] [Accepted: 11/06/2023] [Indexed: 11/09/2023]
Abstract
Regular exercise elicits adaptations in glucose and lipid metabolism that allow the body to meet energy demands of subsequent exercise bouts more effectively and mitigate metabolic diseases including fatty liver. Energy discharged during the acute exercise bouts that comprise exercise training may be a catalyst for liver adaptations. During acute exercise, liver glycogenolysis and gluconeogenesis are accelerated to supply glucose to working muscle. Lower liver energy state imposed by gluconeogenesis and related pathways activates AMP-activated protein kinase (AMPK), which conserves ATP partly by promoting lipid oxidation. This study tested the hypothesis that AMPK is necessary for liver glucose and lipid adaptations to training. Liver-specific AMPKα1α2 knockout (AMPKα1α2fl/fl+AlbCre) mice and littermate controls (AMPKα1α2fl/fl) completed sedentary and exercise training protocols. Liver nutrient fluxes were quantified at rest or during acute exercise following training. Liver metabolites and molecular regulators of metabolism were assessed. Training increased liver glycogen in AMPKα1α2fl/fl mice, but not in AMPKα1α2fl/fl+AlbCre mice. The inability to increase glycogen led to lower glycogenolysis, glucose production, and circulating glucose during acute exercise in trained AMPKα1α2fl/fl+AlbCre mice. Deletion of AMPKα1α2 attenuated training-induced declines in liver diacylglycerides. In particular, training lowered the concentration of unsaturated and elongated fatty acids comprising diacylglycerides in AMPKα1α2fl/fl mice, but not in AMPKα1α2fl/fl+AlbCre mice. Training increased liver triacylglycerides and the desaturation and elongation of fatty acids in triacylglycerides of AMPKα1α2fl/fl+AlbCre mice. These lipid responses were independent of differences in tricarboxylic acid cycle fluxes. In conclusion, AMPK is required for liver training adaptations that are critical to glucose and lipid metabolism.NEW & NOTEWORTHY This study shows that the energy sensor and transducer, AMP-activated protein kinase (AMPK), is necessary for an exercise training-induced: 1) increase in liver glycogen that is necessary for accelerated glycogenolysis during exercise, 2) decrease in liver glycerolipids independent of tricarboxylic acid (TCA) cycle flux, and 3) decline in the desaturation and elongation of fatty acids comprising liver diacylglycerides. The mechanisms defined in these studies have implications for use of regular exercise or AMPK-activators in patients with fatty liver.
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Affiliation(s)
- Curtis C Hughey
- Division of Molecular Medicine, Department of Medicine, University of Minnesota, Minneapolis, Minnesota, United States
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee, United States
| | - Deanna P Bracy
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee, United States
- Mouse Metabolic Phenotyping Center, Vanderbilt University, Nashville, Tennessee, United States
| | - Ferrol I Rome
- Division of Molecular Medicine, Department of Medicine, University of Minnesota, Minneapolis, Minnesota, United States
| | - Mickael Goelzer
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee, United States
| | - E Patrick Donahue
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee, United States
| | - Benoit Viollet
- Université Paris Cité, CNRS, Inserm, Institut Cochin, Paris, France
| | - Marc Foretz
- Université Paris Cité, CNRS, Inserm, Institut Cochin, Paris, France
| | - David H Wasserman
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee, United States
- Mouse Metabolic Phenotyping Center, Vanderbilt University, Nashville, Tennessee, United States
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3
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Townsend LK, Steinberg GR. AMPK and the Endocrine Control of Metabolism. Endocr Rev 2023; 44:910-933. [PMID: 37115289 DOI: 10.1210/endrev/bnad012] [Citation(s) in RCA: 13] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/10/2023] [Revised: 03/10/2023] [Accepted: 04/24/2023] [Indexed: 04/29/2023]
Abstract
Complex multicellular organisms require a coordinated response from multiple tissues to maintain whole-body homeostasis in the face of energetic stressors such as fasting, cold, and exercise. It is also essential that energy is stored efficiently with feeding and the chronic nutrient surplus that occurs with obesity. Mammals have adapted several endocrine signals that regulate metabolism in response to changes in nutrient availability and energy demand. These include hormones altered by fasting and refeeding including insulin, glucagon, glucagon-like peptide-1, catecholamines, ghrelin, and fibroblast growth factor 21; adipokines such as leptin and adiponectin; cell stress-induced cytokines like tumor necrosis factor alpha and growth differentiating factor 15, and lastly exerkines such as interleukin-6 and irisin. Over the last 2 decades, it has become apparent that many of these endocrine factors control metabolism by regulating the activity of the AMPK (adenosine monophosphate-activated protein kinase). AMPK is a master regulator of nutrient homeostasis, phosphorylating over 100 distinct substrates that are critical for controlling autophagy, carbohydrate, fatty acid, cholesterol, and protein metabolism. In this review, we discuss how AMPK integrates endocrine signals to maintain energy balance in response to diverse homeostatic challenges. We also present some considerations with respect to experimental design which should enhance reproducibility and the fidelity of the conclusions.
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Affiliation(s)
- Logan K Townsend
- Centre for Metabolism Obesity and Diabetes Research, Hamilton, ON L8S 4L8, Canada
- Division of Endocrinology and Metabolism, Department of Medicine, McMaster University, Hamilton, ON L8S 4L8, Canada
| | - Gregory R Steinberg
- Centre for Metabolism Obesity and Diabetes Research, Hamilton, ON L8S 4L8, Canada
- Division of Endocrinology and Metabolism, Department of Medicine, McMaster University, Hamilton, ON L8S 4L8, Canada
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, ON L8S 4L8, Canada
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4
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Hall LG, Thyfault JP, Johnson JD. Exercise and inactivity as modifiers of β cell function and type 2 diabetes risk. J Appl Physiol (1985) 2023; 134:823-839. [PMID: 36759159 PMCID: PMC10042613 DOI: 10.1152/japplphysiol.00472.2022] [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: 08/15/2022] [Revised: 01/31/2023] [Accepted: 01/31/2023] [Indexed: 02/11/2023] Open
Abstract
Exercise and regular physical activity are beneficial for the prevention and management of metabolic diseases such as obesity and type 2 diabetes, whereas exercise cessation, defined as deconditioning from regular exercise or physical activity that has lasted for a period of months to years, can lead to metabolic derangements that drive disease. Adaptations to the insulin-secreting pancreatic β-cells are an important benefit of exercise, whereas less is known about how exercise cessation affects these cells. Our aim is to review the impact that exercise and exercise cessation have on β-cell function, with a focus on the evidence from studies examining glucose-stimulated insulin secretion (GSIS) using gold-standard techniques. Potential mechanisms by which the β-cell adapts to exercise, including exerkine and incretin signaling, autonomic nervous system signaling, and changes in insulin clearance, will also be explored. We will highlight areas for future research.
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Affiliation(s)
- Liam G Hall
- Department of Cellular and Physiological Sciences, Life Sciences Institute, The University of British Columbia, Vancouver, British Columbia, Canada
| | - John P Thyfault
- Department of Cell Biology and Physiology, University of Kansas Medical Center, Kansas City, Kansas, United States
- Division of Endocrinology and Metabolism, Department of Internal Medicine, University of Kansas Medical Center, Kansas City, Kansas, United States
- KU Diabetes Institute, University of Kansas Medical Center, Kansas City, Kansas, United States
| | - James D Johnson
- Department of Cellular and Physiological Sciences, Life Sciences Institute, The University of British Columbia, Vancouver, British Columbia, Canada
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Rome FI, Shobert GL, Voigt WC, Stagg DB, Puchalska P, Burgess SC, Crawford PA, Hughey CC. Loss of hepatic phosphoenolpyruvate carboxykinase 1 dysregulates metabolic responses to acute exercise but enhances adaptations to exercise training in mice. Am J Physiol Endocrinol Metab 2023; 324:E9-E23. [PMID: 36351254 PMCID: PMC9799143 DOI: 10.1152/ajpendo.00222.2022] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/06/2022] [Revised: 11/07/2022] [Accepted: 11/07/2022] [Indexed: 11/10/2022]
Abstract
Acute exercise increases liver gluconeogenesis to supply glucose to working muscles. Concurrently, elevated liver lipid breakdown fuels the high energetic cost of gluconeogenesis. This functional coupling between liver gluconeogenesis and lipid oxidation has been proposed to underlie the ability of regular exercise to enhance liver mitochondrial oxidative metabolism and decrease liver steatosis in individuals with nonalcoholic fatty liver disease. Herein we tested whether repeated bouts of increased hepatic gluconeogenesis are necessary for exercise training to lower liver lipids. Experiments used diet-induced obese mice lacking hepatic phosphoenolpyruvate carboxykinase 1 (KO) to inhibit gluconeogenesis and wild-type (WT) littermates. 2H/13C metabolic flux analysis quantified glucose and mitochondrial oxidative fluxes in untrained mice at rest and during acute exercise. Circulating and tissue metabolite levels were determined during sedentary conditions, acute exercise, and refeeding postexercise. Mice also underwent 6 wk of treadmill running protocols to define hepatic and extrahepatic adaptations to exercise training. Untrained KO mice were unable to maintain euglycemia during acute exercise resulting from an inability to increase gluconeogenesis. Liver triacylglycerides were elevated after acute exercise and circulating β-hydroxybutyrate was higher during postexercise refeeding in untrained KO mice. In contrast, exercise training prevented liver triacylglyceride accumulation in KO mice. This was accompanied by pronounced increases in indices of skeletal muscle mitochondrial oxidative metabolism in KO mice. Together, these results show that hepatic gluconeogenesis is dispensable for exercise training to reduce liver lipids. This may be due to responses in ketone body metabolism and/or metabolic adaptations in skeletal muscle to exercise.NEW & NOTEWORTHY Exercise training reduces hepatic steatosis partly through enhanced hepatic terminal oxidation. During acute exercise, hepatic gluconeogenesis is elevated to match the heightened rate of muscle glucose uptake and maintain glucose homeostasis. It has been postulated that the hepatic energetic stress induced by elevating gluconeogenesis during acute exercise is a key stimulus underlying the beneficial metabolic responses to exercise training. This study shows that hepatic gluconeogenesis is not necessary for exercise training to lower liver lipids.
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Affiliation(s)
- Ferrol I Rome
- Division of Molecular Medicine, Department of Medicine, University of Minnesota, Minneapolis, Minnesota
| | - Gregory L Shobert
- Division of Molecular Medicine, Department of Medicine, University of Minnesota, Minneapolis, Minnesota
| | - William C Voigt
- Division of Molecular Medicine, Department of Medicine, University of Minnesota, Minneapolis, Minnesota
| | - David B Stagg
- Division of Molecular Medicine, Department of Medicine, University of Minnesota, Minneapolis, Minnesota
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, Minnesota
| | - Patrycja Puchalska
- Division of Molecular Medicine, Department of Medicine, University of Minnesota, Minneapolis, Minnesota
| | - Shawn C Burgess
- Center for Human Nutrition, The University of Texas Southwestern Medical Center, Dallas, Texas
- Department of Pharmacology, The University of Texas Southwestern Medical Center, Dallas, Texas
| | - Peter A Crawford
- Division of Molecular Medicine, Department of Medicine, University of Minnesota, Minneapolis, Minnesota
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, Minnesota
| | - Curtis C Hughey
- Division of Molecular Medicine, Department of Medicine, University of Minnesota, Minneapolis, Minnesota
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Takahashi K, Kitaoka Y, Hatta H. Effects of endurance training on metabolic enzyme activity and transporter protein levels in the skeletal muscles of orchiectomized mice. J Physiol Sci 2022; 72:14. [PMID: 35768774 PMCID: PMC10717707 DOI: 10.1186/s12576-022-00839-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2022] [Accepted: 06/18/2022] [Indexed: 12/20/2022]
Abstract
This study investigated whether endurance training attenuates orchiectomy (ORX)-induced metabolic alterations. At 7 days of recovery after sham operation or ORX surgery, the mice were randomized to remain sedentary or undergo 5 weeks of treadmill running training (15-20 m/min, 60 min, 5 days/week). ORX decreased glycogen concentration in the gastrocnemius muscle, enhanced phosphofructokinase activity in the plantaris muscle, and decreased lactate dehydrogenase activity in the plantaris and soleus muscles. Mitochondrial enzyme activities and protein content in the plantaris and soleus muscles were also decreased after ORX, but preserved, in part, by endurance training. In the treadmill running test (15 m/min, 60 min) after 4 weeks of training, orchiectomized sedentary mice showed impaired exercise performance, which was restored by endurance training. Thus, endurance training could be a potential therapeutic strategy to prevent the hypoandrogenism-induced decline in muscle mitochondrial content and physical performance.
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Affiliation(s)
- Kenya Takahashi
- Department of Sports Sciences, Graduate School of Arts and Sciences, The University of Tokyo, 3-8-1, Komaba, Meguro-ku, Tokyo, 153-8902, Japan.
| | - Yu Kitaoka
- Department of Human Sciences, Kanagawa University, 3-27-1, Rokkakubashi, Kanagawa-ku, Yokohama, Kanagawa, 221-8686, Japan
| | - Hideo Hatta
- Department of Sports Sciences, Graduate School of Arts and Sciences, The University of Tokyo, 3-8-1, Komaba, Meguro-ku, Tokyo, 153-8902, Japan
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7
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Zmazek J, Grubelnik V, Markovič R, Marhl M. Modeling the Amino Acid Effect on Glucagon Secretion from Pancreatic Alpha Cells. Metabolites 2022; 12:metabo12040348. [PMID: 35448534 PMCID: PMC9028923 DOI: 10.3390/metabo12040348] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2022] [Revised: 04/08/2022] [Accepted: 04/12/2022] [Indexed: 11/29/2022] Open
Abstract
Type 2 Diabetes Mellitus (T2DM) is a burdensome problem in modern society, and intensive research is focused on better understanding the underlying cellular mechanisms of hormone secretion for blood glucose regulation. T2DM is a bi-hormonal disease, and in addition to 100 years of increasing knowledge about the importance of insulin, the second hormone glucagon, secreted by pancreatic alpha cells, is becoming increasingly important. We have developed a mathematical model for glucagon secretion that incorporates all major metabolic processes of glucose, fatty acids, and glutamine as the most abundant postprandial amino acid in blood. In addition, we consider cAMP signaling in alpha cells. The model predictions quantitatively estimate the relative importance of specific metabolic and signaling pathways and particularly emphasize the important role of glutamine in promoting glucagon secretion, which is in good agreement with known experimental data.
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Affiliation(s)
- Jan Zmazek
- Faculty of Natural Sciences and Mathematics, University of Maribor, 2000 Maribor, Slovenia; (J.Z.); (R.M.)
| | - Vladimir Grubelnik
- Faculty of Electrical Engineering and Computer Science, University of Maribor, 2000 Maribor, Slovenia;
| | - Rene Markovič
- Faculty of Natural Sciences and Mathematics, University of Maribor, 2000 Maribor, Slovenia; (J.Z.); (R.M.)
- Faculty of Electrical Engineering and Computer Science, University of Maribor, 2000 Maribor, Slovenia;
| | - Marko Marhl
- Faculty of Natural Sciences and Mathematics, University of Maribor, 2000 Maribor, Slovenia; (J.Z.); (R.M.)
- Faculty of Education, University of Maribor, 2000 Maribor, Slovenia
- Faculty of Medicine, University of Maribor, 2000 Maribor, Slovenia
- Correspondence:
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8
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Abstract
Noncommunicable diseases are chronic diseases that contribute to death worldwide, but these diseases can be prevented and mitigated with regular exercise. Exercise activates signaling molecules and the transcriptional network to promote physiological adaptations, such as fiber type transformation, angiogenesis, and mitochondrial biogenesis. AMP-activated protein kinase (AMPK) is a master regulator that senses the energy state, promotes metabolism for glucose and fatty acid utilization, and mediates beneficial cellular adaptations in many vital tissues and organs. This review focuses on the current, integrative understanding of the role of exercise-induced activation of AMPK in the regulation of system metabolism and promotion of health benefits.
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Affiliation(s)
- Hannah R. Spaulding
- Center for Skeletal Muscle Research at Robert M. Berne Cardiovascular Research Center, University of Virginia School of Medicine, Charlottesville, Virginia, USA
| | - Zhen Yan
- Center for Skeletal Muscle Research at Robert M. Berne Cardiovascular Research Center, University of Virginia School of Medicine, Charlottesville, Virginia, USA; .,Departments of Medicine, Pharmacology, and Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville, Virginia, USA
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9
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Interactions between insulin and exercise. Biochem J 2021; 478:3827-3846. [PMID: 34751700 DOI: 10.1042/bcj20210185] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2021] [Revised: 10/11/2021] [Accepted: 10/13/2021] [Indexed: 02/06/2023]
Abstract
The interaction between insulin and exercise is an example of balancing and modifying the effects of two opposing metabolic regulatory forces under varying conditions. While insulin is secreted after food intake and is the primary hormone increasing glucose storage as glycogen and fatty acid storage as triglycerides, exercise is a condition where fuel stores need to be mobilized and oxidized. Thus, during physical activity the fuel storage effects of insulin need to be suppressed. This is done primarily by inhibiting insulin secretion during exercise as well as activating local and systemic fuel mobilizing processes. In contrast, following exercise there is a need for refilling the fuel depots mobilized during exercise, particularly the glycogen stores in muscle. This process is facilitated by an increase in insulin sensitivity of the muscles previously engaged in physical activity which directs glucose to glycogen resynthesis. In physically trained individuals, insulin sensitivity is also higher than in untrained individuals due to adaptations in the vasculature, skeletal muscle and adipose tissue. In this paper, we review the interactions between insulin and exercise during and after exercise, as well as the effects of regular exercise training on insulin action.
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10
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Regulation of Energy Substrate Metabolism in Endurance Exercise. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2021; 18:ijerph18094963. [PMID: 34066984 PMCID: PMC8124511 DOI: 10.3390/ijerph18094963] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Revised: 04/24/2021] [Accepted: 04/26/2021] [Indexed: 12/25/2022]
Abstract
The human body requires energy to function. Adenosine triphosphate (ATP) is the cellular currency for energy-requiring processes including mechanical work (i.e., exercise). ATP used by the cells is ultimately derived from the catabolism of energy substrate molecules—carbohydrates, fat, and protein. In prolonged moderate to high-intensity exercise, there is a delicate interplay between carbohydrate and fat metabolism, and this bioenergetic process is tightly regulated by numerous physiological, nutritional, and environmental factors such as exercise intensity and duration, body mass and feeding state. Carbohydrate metabolism is of critical importance during prolonged endurance-type exercise, reflecting the physiological need to regulate glucose homeostasis, assuring optimal glycogen storage, proper muscle fuelling, and delaying the onset of fatigue. Fat metabolism represents a sustainable source of energy to meet energy demands and preserve the ‘limited’ carbohydrate stores. Coordinated neural, hormonal and circulatory events occur during prolonged endurance-type exercise, facilitating the delivery of fatty acids from adipose tissue to the working muscle for oxidation. However, with increasing exercise intensity, fat oxidation declines and is unable to supply ATP at the rate of the exercise demand. Protein is considered a subsidiary source of energy supporting carbohydrates and fat metabolism, contributing to approximately 10% of total ATP turnover during prolonged endurance-type exercise. In this review we present an overview of substrate metabolism during prolonged endurance-type exercise and the regulatory mechanisms involved in ATP turnover to meet the energetic demands of exercise.
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11
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Li W, Kirchner T, Ho G, Bonilla F, D'Aquino K, Littrell J, Zhang R, Jian W, Qiu X, Zheng S, Gao B, Wong P, Leonard JN, Camacho RC. Amino acids are sensitive glucagon receptor-specific biomarkers for glucagon-like peptide-1 receptor/glucagon receptor dual agonists. Diabetes Obes Metab 2020; 22:2437-2450. [PMID: 33463043 DOI: 10.1111/dom.14173] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/20/2020] [Revised: 08/10/2020] [Accepted: 08/12/2020] [Indexed: 12/31/2022]
Abstract
AIM The aim of this study was to evaluate amino acids as glucagon receptor (GCGR)-specific biomarkers in rodents and cynomolgus monkeys in the presence of agonism of both glucagon-like peptide-1 receptor (GLP1R) and GCGR with a variety of dual agonist compounds. MATERIALS AND METHODS Primary hepatocytes, rodents (normal, diet-induced obese and GLP1R knockout) and cynomolgus monkeys were treated with insulin (hepatocytes only), glucagon (hepatocytes and cynomolgus monkeys), the GLP1R agonist, dulaglutide, or a variety of dual agonists with varying GCGR potencies. RESULTS A long-acting dual agonist, Compound 2, significantly decreased amino acids in both wild-type and GLP1R knockout mice in the absence of changes in food intake, body weight, glucose or insulin, and increased expression of hepatic amino acid transporters. Dulaglutide, or a variant of Compound 2 lacking GCGR agonism, had no effect on amino acids. A third variant with ~31-fold less GCGR potency than Compound 2 significantly decreased amino acids, albeit to a significantly lesser extent than Compound 2. Dulaglutide (with saline infusion) had no effect on amino acids, but an infusion of glucagon dose-dependently decreased amino acids on the background of GLP1R engagement (dulaglutide) in cynomolgus monkeys, as did Compound 2. CONCLUSIONS These results show that amino acids are sensitive and translatable GCGR-specific biomarkers.
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Affiliation(s)
- Wenyu Li
- Cardiovascular Metabolism Discovery, Janssen R&D, Spring House, Pennsylvania, USA
| | - Thomas Kirchner
- Cardiovascular Metabolism Discovery, Janssen R&D, Spring House, Pennsylvania, USA
| | - George Ho
- Cardiovascular Metabolism Discovery, Janssen R&D, Spring House, Pennsylvania, USA
| | - Fany Bonilla
- Cardiovascular Metabolism Discovery, Janssen R&D, Spring House, Pennsylvania, USA
| | - Katharine D'Aquino
- Cardiovascular Metabolism Discovery, Janssen R&D, Spring House, Pennsylvania, USA
| | - James Littrell
- Cardiovascular Metabolism Discovery, Janssen R&D, Spring House, Pennsylvania, USA
| | - Rui Zhang
- Cardiovascular Metabolism Discovery, Janssen R&D, Spring House, Pennsylvania, USA
| | - Wenying Jian
- Pharmacokinetics, Dynamics, and Metabolism, Janssen R&D, Spring House, Pennsylvania, USA
| | - Xi Qiu
- Pharmacokinetics, Dynamics, and Metabolism, Janssen R&D, Spring House, Pennsylvania, USA
| | - Songmao Zheng
- Janssen Biotherapeutics, Janssen R&D, Spring House, Pennsylvania, USA
| | - Bin Gao
- Translational Medicine and Early Development Statistics, Janssen R&D, Spring House, Pennsylvania, USA
| | - Peggy Wong
- Quantitative Sciences, Janssen R&D, Raritan, New Jersey, USA
| | - James N Leonard
- Cardiovascular Metabolism Discovery, Janssen R&D, Spring House, Pennsylvania, USA
| | - Raul C Camacho
- Cardiovascular Metabolism Discovery, Janssen R&D, Spring House, Pennsylvania, USA
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12
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Thyfault JP, Rector RS. Exercise Combats Hepatic Steatosis: Potential Mechanisms and Clinical Implications. Diabetes 2020; 69:517-524. [PMID: 32198195 PMCID: PMC7085252 DOI: 10.2337/dbi18-0043] [Citation(s) in RCA: 46] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/02/2019] [Accepted: 01/22/2020] [Indexed: 12/17/2022]
Abstract
Hepatic steatosis, the excess storage of intrahepatic lipids, is a rampant clinical problem associated with the obesity epidemic. Hepatic steatosis is linked to increased risk for insulin resistance, type 2 diabetes, and cardiovascular and advanced liver disease. Accumulating evidence shows that physical activity, exercise, and aerobic capacity have profound effects on regulating intrahepatic lipids and mediating susceptibility for hepatic steatosis. Moreover, exercise can effectively reduce hepatic steatosis independent of changes in body mass. In this perspective, we highlight 1) the relationship between obesity and metabolic pathways putatively driving hepatic steatosis compared with changes induced by exercise; 2) the impact of physical activity, exercise, and aerobic capacity compared with caloric restriction on regulating intrahepatic lipids and steatosis risk; 3) the effects of exercise training (modalities, volume, intensity) for treatment of hepatic steatosis, and 4) evidence for a sustained protection against steatosis induced by exercise. Overall, evidence clearly indicates that exercise powerfully regulates intrahepatic storage of fat and risk for steatosis.
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Affiliation(s)
- John P Thyfault
- Department of Molecular and Integrative Physiology, University of Kansas Medical Center, Kansas City, KS
- Research Service, Kansas City VA Medical Center, Kansas City, MO
- Center for Children's Healthy Lifestyles and Nutrition, Children's Mercy Hospital, Kansas City, MO
| | - R Scott Rector
- Division of Gastroenterology and Hepatology, Department of Medicine, and Department of Nutrition and Exercise Physiology, University of Missouri, Columbia, MO
- Research Service, Harry S. Truman Memorial VA Medical Center, Columbia, MO
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13
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Hill CM, Qualls-Creekmore E, Berthoud HR, Soto P, Yu S, McDougal DH, Münzberg H, Morrison CD. FGF21 and the Physiological Regulation of Macronutrient Preference. Endocrinology 2020; 161:5734531. [PMID: 32047920 PMCID: PMC7053867 DOI: 10.1210/endocr/bqaa019] [Citation(s) in RCA: 52] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/22/2019] [Accepted: 02/06/2020] [Indexed: 12/15/2022]
Abstract
The ability to respond to variations in nutritional status depends on regulatory systems that monitor nutrient intake and adaptively alter metabolism and feeding behavior during nutrient restriction. There is ample evidence that the restriction of water, sodium, or energy intake triggers adaptive responses that conserve existing nutrient stores and promote the ingestion of the missing nutrient, and that these homeostatic responses are mediated, at least in part, by nutritionally regulated hormones acting within the brain. This review highlights recent research that suggests that the metabolic hormone fibroblast growth factor 21 (FGF21) acts on the brain to homeostatically alter macronutrient preference. Circulating FGF21 levels are robustly increased by diets that are high in carbohydrate but low in protein, and exogenous FGF21 treatment reduces the consumption of sweet foods and alcohol while alternatively increasing the consumption of protein. In addition, while control mice adaptively shift macronutrient preference and increase protein intake in response to dietary protein restriction, mice that lack either FGF21 or FGF21 signaling in the brain fail to exhibit this homeostatic response. FGF21 therefore mediates a unique physiological niche, coordinating adaptive shifts in macronutrient preference that serve to maintain protein intake in the face of dietary protein restriction.
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Affiliation(s)
| | | | | | - Paul Soto
- Pennington Biomedical Research Center, Baton Rouge, LA
| | - Sangho Yu
- Pennington Biomedical Research Center, Baton Rouge, LA
| | | | | | - Christopher D Morrison
- Pennington Biomedical Research Center, Baton Rouge, LA
- Correspondence: Christopher D. Morrison, Pennington Biomedical Research Center, 6400 Perkins Road, Baton Rouge, LA, 70808. E-mail:
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Dibe HA, Townsend LK, McKie GL, Wright DC. Epinephrine responsiveness is reduced in livers from trained mice. Physiol Rep 2020; 8:e14370. [PMID: 32061187 PMCID: PMC7023888 DOI: 10.14814/phy2.14370] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2019] [Revised: 01/12/2020] [Accepted: 01/21/2020] [Indexed: 12/12/2022] Open
Abstract
The liver is the primary metabolic organ involved in the endogenous production of glucose through glycogenolysis and gluconeogenesis. Hepatic glucose production (HGP) is increased via neural-hormonal mechanisms such as increases in catecholamines. To date, the effects of prior exercise training on the hepatic response to epinephrine have not been fully elucidated. To examine the role of epinephrine signaling on indices of HGP in trained mice, male C57BL/6 mice were either subjected to 12 days of voluntary wheel running or remained sedentary. Epinephrine, or vehicle control, was injected intraperitoneally on day 12 prior to sacrifice with blood glucose being measured 15 min postinjection. Epinephrine caused a larger glucose response in sedentary mice and this was paralleled by a greater reduction in liver glycogen in sedentary compared to trained mice. There was a main effect of epinephrine to increase the phosphorylation of protein kinase-A (p-PKA) substrates in the liver, which was driven by increases in the sedentary, but not trained, mice. Similarly, epinephrine-induced increases in the mRNA expression of hepatic adrenergic receptors (Adra1/2a, Adrb1), and glucose-6-phosphatase (G6pc) were greater in sedentary compared to trained mice. The mRNA expression of cAMP-degrading enzymes phosphodiesterase 3B and 4B (Pde3b, Pde4b) was greater in trained compared to sedentary mice. Taken together, our data suggest that prior exercise training reduces the liver's response to epinephrine. This could be beneficial in the context of training-induced glycogen sparing during exercise.
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Affiliation(s)
- Hana A Dibe
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, ON, Canada
| | - Logan K Townsend
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, ON, Canada
| | - Greg L McKie
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, ON, Canada
| | - David C Wright
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, ON, Canada
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15
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Rajasekaran R, Felser A, Nuoffer JM, Dufour JF, St-Pierre MV. The histidine triad nucleotide-binding protein 2 (HINT-2) positively regulates hepatocellular energy metabolism. FASEB J 2018; 32:5143-5161. [PMID: 29913563 DOI: 10.1096/fj.201701429r] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The histidine triad nucleotide-binding protein 2 (HINT-2) is a mitochondrial adenosine phosphoramidase expressed in hepatocytes. The phenotype of Hint2 knockout ( Hint2-/-) mice includes progressive hepatic steatosis and lysine hyperacetylation of mitochondrial proteins, which are features of respiratory chain malfunctions. We postulated that the absence of HINT-2 induces a defect in mitochondria bioenergetics. Isolated Hint2-/- hepatocytes produced less ATP and generated a lower mitochondrial membrane potential than did Hint2+/+ hepatocytes. In extracellular flux analyses with glucose, the basal, ATP-linked, and maximum oxygen consumption rates (OCRs) were decreased in Hint2-/- hepatocytes and in HepG2 cells lacking HINT-2. Conversely, in HINT-2 overexpressing SNU-449 and HepG2 cells, the basal, ATP-linked, and maximum OCRs were increased. Similarly, with palmitate, basal and maximum OCRs were decreased in Hint2-/- hepatocytes, but they were increased in HINT-2 overexpressing HepG2 cells. When assayed with radiolabeled substrate, palmitate oxidation was reduced by 25% in Hint2-/- mitochondria. In respirometry assays, complex I- and II-driven, coupled and uncoupled respirations and complex IV KCN-sensitive respiration were reduced in Hint2-/- mitochondria. Furthermore, HINT-2 associated with cardiolipin and glucose-regulated protein 75 kDa. Our study shows decreased electron transfer and oxidative phosphorylation capacity in the absence of HINT-2. The bioenergetics deficit accumulated over time in hepatocytes lacking HINT-2 likely leads to the secondary outcome of steatosis.-Rajasekaran, R., Felser, A., Nuoffer, J.-M., Dufour, J.-F., St-Pierre, M. V. The histidine triad nucleotide-binding protein 2 (HINT-2) positively regulates hepatocellular energy metabolism.
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Affiliation(s)
| | - Andrea Felser
- University Institute of Clinical Chemistry, University of Bern, Bern, Switzerland; and
| | - Jean-Marc Nuoffer
- University Institute of Clinical Chemistry, University of Bern, Bern, Switzerland; and
| | - Jean-François Dufour
- Department of Biomedical Research, University of Bern, Bern, Switzerland.,University Clinic of Visceral Surgery and Medicine, University Hospital Bern, Bern, Switzerland
| | - Marie V St-Pierre
- Department of Biomedical Research, University of Bern, Bern, Switzerland
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16
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Hughey CC, James FD, Bracy DP, Donahue EP, Young JD, Viollet B, Foretz M, Wasserman DH. Loss of hepatic AMP-activated protein kinase impedes the rate of glycogenolysis but not gluconeogenic fluxes in exercising mice. J Biol Chem 2017; 292:20125-20140. [PMID: 29038293 DOI: 10.1074/jbc.m117.811547] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2017] [Revised: 10/10/2017] [Indexed: 11/06/2022] Open
Abstract
Pathologies including diabetes and conditions such as exercise place an unusual demand on liver energy metabolism, and this demand induces a state of energy discharge. Hepatic AMP-activated protein kinase (AMPK) has been proposed to inhibit anabolic processes such as gluconeogenesis in response to cellular energy stress. However, both AMPK activation and glucose release from the liver are increased during exercise. Here, we sought to test the role of hepatic AMPK in the regulation of in vivo glucose-producing and citric acid cycle-related fluxes during an acute bout of muscular work. We used 2H/13C metabolic flux analysis to quantify intermediary metabolism fluxes in both sedentary and treadmill-running mice. Additionally, liver-specific AMPK α1 and α2 subunit KO and WT mice were utilized. Exercise caused an increase in endogenous glucose production, glycogenolysis, and gluconeogenesis from phosphoenolpyruvate. Citric acid cycle fluxes, pyruvate cycling, anaplerosis, and cataplerosis were also elevated during this exercise. Sedentary nutrient fluxes in the postabsorptive state were comparable for the WT and KO mice. However, the increment in the endogenous rate of glucose appearance during exercise was blunted in the KO mice because of a diminished glycogenolytic flux. This lower rate of glycogenolysis was associated with lower hepatic glycogen content before the onset of exercise and prompted a reduction in arterial glucose during exercise. These results indicate that liver AMPKα1α2 is required for maintaining glucose homeostasis during an acute bout of exercise.
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Affiliation(s)
- Curtis C Hughey
- Department of Molecular Physiology and Biophysics, Nashville, Tennessee 37232
| | - Freyja D James
- Department of Molecular Physiology and Biophysics, Nashville, Tennessee 37232; Mouse Metabolic Phenotyping Center, Nashville, Tennessee 37232
| | - Deanna P Bracy
- Department of Molecular Physiology and Biophysics, Nashville, Tennessee 37232; Mouse Metabolic Phenotyping Center, Nashville, Tennessee 37232
| | - E Patrick Donahue
- Department of Molecular Physiology and Biophysics, Nashville, Tennessee 37232
| | - Jamey D Young
- Department of Molecular Physiology and Biophysics, Nashville, Tennessee 37232; Department of Chemical and Biomolecular Engineering, Vanderbilt University, Nashville, Tennessee 37232
| | - Benoit Viollet
- INSERM, U1016, Institut Cochin, 75014 Paris, France; CNRS, UMR 8104, 75014 Paris, France; Université Paris Descartes, Sorbonne Paris Cité, 75014 Paris, France
| | - Marc Foretz
- INSERM, U1016, Institut Cochin, 75014 Paris, France; CNRS, UMR 8104, 75014 Paris, France; Université Paris Descartes, Sorbonne Paris Cité, 75014 Paris, France
| | - David H Wasserman
- Department of Molecular Physiology and Biophysics, Nashville, Tennessee 37232; Mouse Metabolic Phenotyping Center, Nashville, Tennessee 37232.
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17
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Liver AMP-Activated Protein Kinase Is Unnecessary for Gluconeogenesis but Protects Energy State during Nutrient Deprivation. PLoS One 2017; 12:e0170382. [PMID: 28107516 PMCID: PMC5249187 DOI: 10.1371/journal.pone.0170382] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2016] [Accepted: 01/04/2017] [Indexed: 11/28/2022] Open
Abstract
AMPK is an energy sensor that protects cellular energy state by attenuating anabolic and promoting catabolic processes. AMPK signaling is purported to regulate hepatic gluconeogenesis and substrate oxidation; coordination of these processes is vital during nutrient deprivation or pathogenic during overnutrition. Here we directly test hepatic AMPK function in regulating metabolic fluxes that converge to produce glucose and energy in vivo. Flux analysis was applied in mice with a liver-specific deletion of AMPK (L-KO) or floxed control littermates to assess rates of hepatic glucose producing and citric acid cycle (CAC) fluxes. Fluxes were assessed in short and long term fasted mice; the latter condition is a nutrient stressor that increases liver AMP/ATP. The flux circuit connecting anaplerosis with gluconeogenesis from the CAC was unaffected by hepatic AMPK deletion in short and long term fasting. Nevertheless, depletion of hepatic ATP was exacerbated in L-KO mice, corresponding to a relative elevation in citrate synthase flux and accumulation of branched-chain amino acid-related metabolites. L-KO mice also had a physiological reduction in flux from glycogen to G6P. These results demonstrate AMPK is unnecessary for maintaining gluconeogenic flux from the CAC yet is critical for stabilizing liver energy state during nutrient deprivation.
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18
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Pesl P, Herrero P, Reddy M, Oliver N, Johnston DG, Toumazou C, Georgiou P. Case-Based Reasoning for Insulin Bolus Advice. J Diabetes Sci Technol 2017; 11:37-42. [PMID: 26862136 PMCID: PMC5375057 DOI: 10.1177/1932296816629986] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
BACKGROUND Insulin bolus calculators assist people with Type 1 diabetes (T1D) to calculate the amount of insulin required for meals to achieve optimal glucose levels but lack adaptability and personalization. We have proposed enhancing bolus calculators by the means of case-based reasoning (CBR), an established problem-solving methodology, by individualizing and optimizing insulin therapy for various meal situations. CBR learns from experiences of past similar meals, which are described in cases through a set of parameters (eg, time of meal, alcohol, exercise). This work discusses the selection, representation and effect of case parameters used for a CBR-based Advanced Bolus Calculator for Diabetes (ABC4D). METHODS We analyzed the usage and effect of selected parameters during a pilot study (n = 10), where participants used ABC4D for 6 weeks. Retrospectively, we evaluated the effect of glucose rate of change before the meal on the glycemic excursion. Feedback from study participants about the choice of parameters was obtained through a nonvalidated questionnaire. RESULTS Exercise and alcohol were the most frequently used parameters, which was congruent with the feedback from study participants, who found these parameters most useful. Furthermore, cases including either exercise or alcohol as parameter showed a trend in reduction of insulin at the end of the study. A significant difference ( P < .01) was found in glycemic outcomes for meals where glucose rate of change was rising compared to stable rate of change. CONCLUSIONS Results from the 6-week study indicate the potential benefit of including parameters exercise, alcohol and glucose-rate of change for insulin dosing decision support.
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Affiliation(s)
- Peter Pesl
- Centre for Bio-Inspired Technology, Institute of Biomedical Engineering, Imperial College London, London, UK
- Peter Pesl, Dipl-Ing(FH), Centre for Bio-Inspired Technology, Institute of Biomedical Engineering, Imperial College London, United Kingdom, SW7 2AZ, London, UK.
| | - Pau Herrero
- Centre for Bio-Inspired Technology, Institute of Biomedical Engineering, Imperial College London, London, UK
| | - Monika Reddy
- Division of Medicine, Imperial College London, London, UK
| | - Nick Oliver
- Division of Medicine, Imperial College London, London, UK
| | | | - Christofer Toumazou
- Centre for Bio-Inspired Technology, Institute of Biomedical Engineering, Imperial College London, London, UK
| | - Pantelis Georgiou
- Centre for Bio-Inspired Technology, Institute of Biomedical Engineering, Imperial College London, London, UK
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19
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Morris EM, Meers GME, Koch LG, Britton SL, Fletcher JA, Fu X, Shankar K, Burgess SC, Ibdah JA, Rector RS, Thyfault JP. Aerobic capacity and hepatic mitochondrial lipid oxidation alters susceptibility for chronic high-fat diet-induced hepatic steatosis. Am J Physiol Endocrinol Metab 2016; 311:E749-E760. [PMID: 27600823 PMCID: PMC5241560 DOI: 10.1152/ajpendo.00178.2016] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/03/2016] [Accepted: 08/30/2016] [Indexed: 12/24/2022]
Abstract
Rats selectively bred for high capacity running (HCR) or low capacity running (LCR) display divergence for intrinsic aerobic capacity and hepatic mitochondrial oxidative capacity, both factors associated with susceptibility for nonalcoholic fatty liver disease. Here, we tested if HCR and LCR rats display differences in susceptibility for hepatic steatosis after 16 wk of high-fat diets (HFD) with either 45% or 60% of kcals from fat. HCR rats were protected against HFD-induced hepatic steatosis, whereas only the 60% HFD induced steatosis in LCR rats, as marked by a doubling of liver triglycerides. Hepatic complete fatty acid oxidation (FAO) and mitochondrial respiratory capacity were all lower in LCR compared with HCR rats. LCR rats also displayed lower hepatic complete and incomplete FAO in the presence of etomoxir, suggesting a reduced role for noncarnitine palmitoyltransferase-1-mediated lipid catabolism in LCR versus HCR rats. Hepatic complete FAO and mitochondrial respiration were largely unaffected by either chronic HFD; however, 60% HFD feeding markedly reduced 2-pyruvate oxidation, a marker of tricarboxylic acid (TCA) cycle flux, and mitochondrial complete FAO only in LCR rats. LCR rats displayed lower levels of hepatic long-chain acylcarnitines than HCR rats but maintained similar levels of hepatic acetyl-carnitine levels, further supporting lower rates of β-oxidation, and TCA cycle flux in LCR than HCR rats. Finally, only LCR rats displayed early reductions in TCA cycle genes after the acute initiation of a HFD. In conclusion, intrinsically high aerobic capacity confers protection against HFD-induced hepatic steatosis through elevated hepatic mitochondrial oxidative capacity.
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Affiliation(s)
- E Matthew Morris
- Molecular and Integrative Physiology, University of Kansas Medical Center, Kansas City, Kansas
| | - Grace M E Meers
- Medicine and Division of Gastroenterology and Hepatology, University of Missouri, Columbia, Missouri
| | - Lauren G Koch
- Anesthesiology, University of Michigan, Ann Arbor, Michigan
| | | | - Justin A Fletcher
- Pharmacology and Advanced Imaging Research, University of Texas Southwestern, Dallas, Texas
| | - Xiaorong Fu
- Pharmacology and Advanced Imaging Research, University of Texas Southwestern, Dallas, Texas
| | - Kartik Shankar
- Arkansas Children's Nutrition Center and the Department of Pediatrics, University of Arkansas for Medical Sciences, Little Rock, Arkansas
| | - Shawn C Burgess
- Pharmacology and Advanced Imaging Research, University of Texas Southwestern, Dallas, Texas
| | - Jamal A Ibdah
- Medicine and Division of Gastroenterology and Hepatology, University of Missouri, Columbia, Missouri
| | - R Scott Rector
- Medicine and Division of Gastroenterology and Hepatology, University of Missouri, Columbia, Missouri; Nutrition and Exercise Physiology, University of Missouri, Columbia, Missouri; Research Service, Harry S. Truman Memorial Veterans Affairs Hospital, Columbia, Missouri
| | - John P Thyfault
- Molecular and Integrative Physiology, University of Kansas Medical Center, Kansas City, Kansas; Research Service, Kansas City Veterans Affairs Medical Center, Kansas City, Missourit; and
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20
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Di Meo S, Reed TT, Venditti P, Victor VM. Role of ROS and RNS Sources in Physiological and Pathological Conditions. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2016; 2016:1245049. [PMID: 27478531 PMCID: PMC4960346 DOI: 10.1155/2016/1245049] [Citation(s) in RCA: 756] [Impact Index Per Article: 94.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/01/2015] [Revised: 05/04/2016] [Accepted: 05/23/2016] [Indexed: 12/19/2022]
Abstract
There is significant evidence that, in living systems, free radicals and other reactive oxygen and nitrogen species play a double role, because they can cause oxidative damage and tissue dysfunction and serve as molecular signals activating stress responses that are beneficial to the organism. Mitochondria have been thought to both play a major role in tissue oxidative damage and dysfunction and provide protection against excessive tissue dysfunction through several mechanisms, including stimulation of opening of permeability transition pores. Until recently, the functional significance of ROS sources different from mitochondria has received lesser attention. However, the most recent data, besides confirming the mitochondrial role in tissue oxidative stress and protection, show interplay between mitochondria and other ROS cellular sources, so that activation of one can lead to activation of other sources. Thus, it is currently accepted that in various conditions all cellular sources of ROS provide significant contribution to processes that oxidatively damage tissues and assure their survival, through mechanisms such as autophagy and apoptosis.
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Affiliation(s)
- Sergio Di Meo
- Dipartimento di Biologia, Università di Napoli “Federico II”, 80126 Napoli, Italy
| | - Tanea T. Reed
- Department of Chemistry, Eastern Kentucky University, Richmond, KY 40475, USA
| | - Paola Venditti
- Dipartimento di Biologia, Università di Napoli “Federico II”, 80126 Napoli, Italy
| | - Victor Manuel Victor
- Service of Endocrinology, University Hospital Dr. Peset, Foundation for the Promotion of Health and Biomedical Research in the Valencian Region (FISABIO), 46010 Valencia, Spain
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21
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Akhmedov D, Rajendran K, Mendoza-Rodriguez MG, Berdeaux R. Knock-in Luciferase Reporter Mice for In Vivo Monitoring of CREB Activity. PLoS One 2016; 11:e0158274. [PMID: 27336479 PMCID: PMC4940169 DOI: 10.1371/journal.pone.0158274] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2016] [Accepted: 06/13/2016] [Indexed: 11/18/2022] Open
Abstract
The cAMP response element binding protein (CREB) is induced during fasting in the liver, where it stimulates transcription of rate-limiting gluconeogenic genes to maintain metabolic homeostasis. Adenoviral and transgenic CREB reporters have been used to monitor hepatic CREB activity non-invasively using bioluminescence reporter imaging. However, adenoviral vectors and randomly inserted transgenes have several limitations. To overcome disadvantages of the currently used strategies, we created a ROSA26 knock-in CREB reporter mouse line (ROSA26-CRE-luc). cAMP-inducing ligands stimulate the reporter in primary hepatocytes and myocytes from ROSA26-CRE-luc animals. In vivo, these animals exhibit little hepatic CREB activity in the ad libitum fed state but robust induction after fasting. Strikingly, CREB was markedly stimulated in liver, but not in skeletal muscle, after overnight voluntary wheel-running exercise, uncovering differential regulation of CREB in these tissues under catabolic states. The ROSA26-CRE-luc mouse line is a useful resource to study dynamics of CREB activity longitudinally in vivo and can be used as a source of primary cells for analysis of CREB regulatory pathways ex vivo.
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Affiliation(s)
- Dmitry Akhmedov
- Department of Integrative Biology and Pharmacology, McGovern Medical School at the University of Texas Health Science Center at Houston (UTHealth), Houston, Texas, United States of America
| | - Kavitha Rajendran
- Department of Integrative Biology and Pharmacology, McGovern Medical School at the University of Texas Health Science Center at Houston (UTHealth), Houston, Texas, United States of America
| | - Maria G. Mendoza-Rodriguez
- Department of Integrative Biology and Pharmacology, McGovern Medical School at the University of Texas Health Science Center at Houston (UTHealth), Houston, Texas, United States of America
| | - Rebecca Berdeaux
- Department of Integrative Biology and Pharmacology, McGovern Medical School at the University of Texas Health Science Center at Houston (UTHealth), Houston, Texas, United States of America
- Center for Metabolic and Degenerative Diseases, Institute of Molecular Medicine, University of Texas Health Science Center at Houston (UTHealth), Houston, Texas, United States of America
- Cell and Regulatory Biology Program, The University of Texas Graduate School of Biomedical Sciences at Houston, McGovern Medical School at the University of Texas Health Science Center at Houston (UTHealth), Houston, Texas, United States of America
- * E-mail:
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22
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Hansen JS, Clemmesen JO, Secher NH, Hoene M, Drescher A, Weigert C, Pedersen BK, Plomgaard P. Glucagon-to-insulin ratio is pivotal for splanchnic regulation of FGF-21 in humans. Mol Metab 2015; 4:551-60. [PMID: 26266087 PMCID: PMC4529499 DOI: 10.1016/j.molmet.2015.06.001] [Citation(s) in RCA: 91] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/22/2015] [Revised: 05/31/2015] [Accepted: 06/05/2015] [Indexed: 01/08/2023] Open
Abstract
BACKGROUND & AIMS Fibroblast growth factor 21 (FGF-21) is a liver-derived metabolic regulator induced by energy deprivation. However, its regulation in humans is incompletely understood. We addressed the origin and regulation of FGF-21 secretion in humans. METHODS By determination of arterial-to-venous differences over the liver and the leg during exercise, we evaluated the organ-specific secretion of FGF-21 in humans. By four different infusion models manipulating circulating glucagon and insulin, we addressed the interaction of these hormones on FGF-21 secretion in humans. RESULTS We demonstrate that the splanchnic circulation secretes FGF-21 at rest and that it is rapidly enhanced during exercise. In contrast, the leg does not contribute to the systemic levels of FGF-21. To unravel the mechanisms underlying the regulation of exercise-induced hepatic release of FGF-21, we manipulated circulating glucagon and insulin. These studies demonstrated that in humans glucagon stimulates splanchnic FGF-21 secretion whereas insulin has an inhibitory effect. CONCLUSIONS Collectively, our data reveal that 1) in humans, the splanchnic bed contributes to the systemic FGF-21 levels during rest and exercise; 2) under normo-physiological conditions FGF-21 is not released from the leg; 3) a dynamic interaction of glucagon-to-insulin ratio regulates FGF-21 secretion in humans.
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Affiliation(s)
- Jakob Schiøler Hansen
- The Centre of Inflammation and Metabolism and the Centre for Physical Activity Research, Department of Infectious Diseases, Rigshospitalet, University of Copenhagen, Denmark ; Department of Clinical Biochemistry, Rigshospitalet, Copenhagen, Denmark
| | | | - Niels Henry Secher
- Department of Anaesthesiology, The Copenhagen Muscle Research Centre, Rigshospitalet, Copenhagen, Denmark
| | - Miriam Hoene
- Division of Pathobiochemistry and Clinical Chemistry, University Tuebingen, Germany
| | - Andrea Drescher
- Division of Pathobiochemistry and Clinical Chemistry, University Tuebingen, Germany
| | - Cora Weigert
- Division of Pathobiochemistry and Clinical Chemistry, University Tuebingen, Germany ; Institute for Diabetes Research and Metabolic Diseases of the Helmholtz Zentrum München at the University of Tuebingen, Tuebingen, Germany ; German Center for Diabetes Research (DZD), Germany
| | - Bente Klarlund Pedersen
- The Centre of Inflammation and Metabolism and the Centre for Physical Activity Research, Department of Infectious Diseases, Rigshospitalet, University of Copenhagen, Denmark
| | - Peter Plomgaard
- The Centre of Inflammation and Metabolism and the Centre for Physical Activity Research, Department of Infectious Diseases, Rigshospitalet, University of Copenhagen, Denmark ; Department of Clinical Biochemistry, Rigshospitalet, Copenhagen, Denmark
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Abstract
Skeletal muscle has the capacity to increase energy turnover by ∼1000 times its resting rate when contracting at the maximum force/power output. Since ATP is not stored in any appreciable quantity, the muscle requires a coordinated metabolic response to maintain an adequate supply of ATP to sustain contractile activity. The integration of intracellular metabolic pathways is dependent upon the cross-bridge cycling rate of myosin and actin, substrate availability and the accumulation of metabolic byproducts, all of which can influence the maintenance of contractile activity or result in the onset of fatigue. In addition, the mobilisation of extracellular substrates is dependent upon the integration of both the autonomic nervous system and endocrine systems to coordinate an increase in both carbohydrate and fat availability. The current review examines the evidence for skeletal muscle to generate power over short and long durations and discusses the metabolic response to sustain these processes. The review also considers the endocrine response from the perspective of the sympathoadrenal system to integrate extracellular substrate availability with the increased energy demands made by contracting skeletal muscle. Finally, the review briefly discusses the evidence that muscle acts in an endocrine manner during exercise and what role this might play in mobilising extracellular substrates to augment the effects of the sympathoadrenal system.
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Affiliation(s)
- Derek Ball
- School of Life SciencesHeriot-Watt University, Edinburgh EH14 4AS, UK
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24
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Alghannam AF, Tsintzas K, Thompson D, Bilzon J, Betts JA. Exploring mechanisms of fatigue during repeated exercise and the dose dependent effects of carbohydrate and protein ingestion: study protocol for a randomised controlled trial. Trials 2014; 15:95. [PMID: 24670140 PMCID: PMC3986903 DOI: 10.1186/1745-6215-15-95] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2013] [Accepted: 03/03/2014] [Indexed: 12/22/2022] Open
Abstract
Background Muscle glycogen has been well established as the primary metabolic energy substrate during physical exercise of moderate- to high-intensity and has accordingly been implicated as a limiting factor when such activity is sustained for a prolonged duration. However, the role of this substrate during repeated exercise after limited recovery is less clear, with ongoing debate regarding how recovery processes can best be supported via nutritional intervention. The aim of this project is to examine the causes of fatigue during repeated exercise bouts via manipulation of glycogen availability through nutritional intervention, thus simultaneously informing aspects of the optimal feeding strategy for recovery from prolonged exercise. Methods/Design The project involves two phases with each involving two treatment arms administered in a repeated measures design. For each treatment, participants will be required to exercise to the point of volitional exhaustion on a motorised treadmill at 70% of previously determined maximal oxygen uptake, before a four hour recovery period in which participants will be prescribed solutions providing 1.2 grams of sucrose per kilogram of body mass per hour of recovery (g.kg-1.h-1) relative to either a lower rate of sucrose ingestion (that is, 0.3 g.kg-1. h-1; Phase I) or a moderate dose (that is, 0.8 g.kg-1.h-1) rendered isocaloric via the addition of 0.4 g.kg-1.h-1 whey protein hydrolysate (Phase II); the latter administered in a double blind manner as part of a randomised and counterbalanced design. Muscle biopsies will be sampled at the beginning and end of recovery for determination of muscle glycogen resynthesis rates, with further biopsies taken following a second bout of exhaustive exercise to determine differences in substrate availability relative to the initial sample taken following the first exercise bout. Discussion Phase I will inform whether a dose–response relationship exists between carbohydrate ingestion rate and muscle glycogen availability and/or the subsequent capacity for physical exercise. Phase II will determine whether such effects are dependent on glycogen availability per se or energy intake, potentially via protein mediated mechanisms. Trial registration ISRCTN87937960.
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Affiliation(s)
- Abdullah F Alghannam
- Human Physiology Research Group, Department for Health, University of Bath, Bath BA2 7AY, UK.
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Zhu Z, Spicer EG, Gavini CK, Goudjo-Ako AJ, Novak CM, Shi H. Enhanced sympathetic activity in mice with brown adipose tissue transplantation (transBATation). Physiol Behav 2014; 125:21-9. [PMID: 24291381 PMCID: PMC3896387 DOI: 10.1016/j.physbeh.2013.11.008] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2013] [Accepted: 11/19/2013] [Indexed: 12/22/2022]
Abstract
Brown adipose tissue (BAT) burns calories to produce heat, and is thus relevant to energy balance. Interscapular BAT (IBAT) of donor mice was transplanted into recipient mice (transBATation). To test whether transBATation counteracts high-fat diet (HFD)-induced obesity, some sham-operated and recipient mice were fed a HFD (HFD-sham, HFD-trans) while others remained on a standard chow (chow-sham, chow-trans). HFD-trans mice had lower body weight and fat and greater energy expenditure, but similar caloric intake compared with HFD-sham mice. We hypothesized that HFD-trans mice had elevated sympathetic activity compared with HFD-sham mice, contributing to increased energy expenditure and fuel mobilization. This was supported by findings that HFD-trans mice had greater energy expenditure during a norepinephrine challenge test and higher core temperatures after cold exposure than did HFD-sham mice, implicating enhanced whole-body metabolic response and elevated sympathetic activity. Additionally, transBATation selectively increased sympathetic drive to some, but not all, white adipose tissue depots and skeletal muscles, as well as the endogenous IBAT, heart, and liver. Collectively, transBATation confers resistance to HFD-induced obesity via increase in whole-body sympathetic activity, and differential activation of sympathetic drive to some of the tissues involved in energy expenditure and fuel mobilization.
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Affiliation(s)
- Zheng Zhu
- Physiology and Neuroscience, Department of Biology, Miami University, OH, United States; Department of Statistics, Miami University, OH, United States
| | - Elizabeth G Spicer
- Physiology and Neuroscience, Department of Biology, Miami University, OH, United States; Department of Nursing, School of Engineering and Applied Sciences, Miami University, OH, United States
| | | | - Ashley J Goudjo-Ako
- Physiology and Neuroscience, Department of Biology, Miami University, OH, United States
| | - Colleen M Novak
- Department of Biological Sciences, Kent State University, OH, United States
| | - Haifei Shi
- Physiology and Neuroscience, Department of Biology, Miami University, OH, United States.
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Hasenour CM, Ridley DE, Hughey CC, James FD, Donahue EP, Shearer J, Viollet B, Foretz M, Wasserman DH. 5-Aminoimidazole-4-carboxamide-1-β-D-ribofuranoside (AICAR) effect on glucose production, but not energy metabolism, is independent of hepatic AMPK in vivo. J Biol Chem 2014; 289:5950-9. [PMID: 24403081 DOI: 10.1074/jbc.m113.528232] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Metabolic stress, as well as several antidiabetic agents, increases hepatic nucleotide monophosphate (NMP) levels, activates AMP-activated protein kinase (AMPK), and suppresses glucose production. We tested the necessity of hepatic AMPK for the in vivo effects of an acute elevation in NMP on metabolism. 5-Aminoimidazole-4-carboxamide 1-β-D-ribofuranoside (AICAR; 8 mg·kg(-1)·min(-1))-euglycemic clamps were performed to elicit an increase in NMP in wild type (α1α2(lox/lox)) and liver-specific AMPK knock-out mice (α1α2(lox/lox) + Albcre) in the presence of fixed glucose. Glucose kinetics were equivalent in 5-h fasted α1α2(lox/lox) and α1α2(lox/lox) + Albcre mice. AMPK was not required for AICAR-mediated suppression of glucose production and increased glucose disappearance. These results demonstrate that AMPK is unnecessary for normal 5-h fasting glucose kinetics and AICAR-mediated inhibition of glucose production. Moreover, plasma fatty acids and triglycerides also decreased independently of hepatic AMPK during AICAR administration. Although the glucoregulatory effects of AICAR were shown to be independent of AMPK, these studies provide in vivo support for the AMPK energy sensor paradigm. AICAR reduced hepatic energy charge by ∼20% in α1α2(lox/lox), which was exacerbated by ∼2-fold in α1α2(lox/lox) + Albcre. This corresponded to a ∼6-fold rise in AMP/ATP in α1α2(lox/lox) + Albcre. Consistent with the effects on adenine nucleotides, maximal mitochondrial respiration was ∼30% lower in α1α2(lox/lox) + Albcre than α1α2(lox/lox) livers. Mitochondrial oxidative phosphorylation efficiency was reduced by 25%. In summary, these results demonstrate that the NMP capacity to inhibit glucose production in vivo is independent of liver AMPK. In contrast, AMPK promotes mitochondrial function and protects against a more precipitous fall in ATP during AICAR administration.
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McDonald MW, Murray MR, Hall KE, Noble EG, Melling CWJ. Morphological assessment of pancreatic islet hormone content following aerobic exercise training in rats with poorly controlled Type 1 diabetes mellitus. Islets 2014; 6:e29221. [PMID: 25483959 PMCID: PMC4594201 DOI: 10.4161/isl.29221] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Regular exercise has been shown to improve many complications of Type 1 diabetes mellitus (T1DM) including enhanced glucose tolerance and increased cardiac function. While exercise training has been shown to increase insulin content in pancreatic islets of rats with T1DM, experimental models were severely hyperglycemic and not undergoing insulin treatment. Further, research to date has yet to determine how exercise training alters glucagon content in pancreatic islets. The purpose of the present investigation was to determine the impact of a 10-week aerobic training program on pancreatic islet composition in insulin-treated rats with T1DM. Second, it was determined whether the acute, exercise-mediated reduction in blood glucose experienced in rats with T1DM would become larger in magnitude following aerobic exercise training. Diabetes was induced in male Sprague-Dawley rats by multiple low dose injections of streptozotocin (20mg/kg i.p.) and moderate intensity aerobic exercise training was performed on a motorized treadmill for one hour per day for a total of 10 weeks. Rats with T1DM demonstrated significantly less islet insulin, and significantly more islet glucagon hormone content compared with non-T1DM rats, which did not significantly change following aerobic training. The reduction in blood glucose in response to a single exercise bout was similar across 10 weeks of training. Results also support the view that different subpopulations of islets exist, as small islets (<50 μm diameter) had significantly more insulin and glucagon in rats with and without T1DM.
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Affiliation(s)
- Matthew W McDonald
- School of Kinesiology; Faculty of Health Sciences; University of Western Ontario; London, ON Canada
| | - Michael R Murray
- School of Kinesiology; Faculty of Health Sciences; University of Western Ontario; London, ON Canada
| | - Katharine E Hall
- Health and Rehabilitation Sciences; Faculty of Health Sciences; University of Western Ontario; London, ON Canada
| | - Earl G Noble
- School of Kinesiology; Faculty of Health Sciences; University of Western Ontario; London, ON Canada
- Lawson Health Research Institute; University of Western Ontario; London, ON Canada
| | - CW James Melling
- School of Kinesiology; Faculty of Health Sciences; University of Western Ontario; London, ON Canada
- Correspondence to: CW James Melling,
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Abstract
Physical exercise is firmly incorporated in the management of type 1 diabetes (T1DM), due to multiple recognized beneficial health effects (cardiovascular disease prevention being preeminent). When glycemic values are not excessively low or high at the time of exercise, few absolute contraindications exist; practical guidelines regarding amount, type, and duration of age-appropriate exercise are regularly updated by entities such as the American Diabetes Association and the International Society for Pediatric and Adolescent Diabetes. Practical implementation of exercise regimens, however, may at times be problematic. In the poorly controlled patient, specific structural changes may occur within skeletal muscle fiber, which is considered by some to be a disease-specific myopathy. Further, even in well-controlled patients, several homeostatic mechanisms regulating carbohydrate metabolism often become impaired, causing hypo- or hyperglycemia during and/or after exercise. Some altered responses may be related to inappropriate exogenous insulin administration, but are often also partly caused by the "metabolic memory" of prior glycemic events. In this context, prior hyperglycemia correlates with increased inflammatory and oxidative stress responses, possibly modulating key exercise-associated cardio-protective pathways. Similarly, prior hypoglycemia correlates with impaired glucose counterregulation, resulting in greater likelihood of further hypoglycemia to develop. Additional exercise responses that may be altered in T1DM include growth factor release, which may be especially important in children and adolescents. These multiple alterations in the exercise response should not discourage physical activity in patients with T1DM, but rather should stimulate the quest for the identification of the exercise formats that maximize beneficial health effects.
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Affiliation(s)
- Pietro Galassetti
- Department of Pediatrics, University of California Irvine, Irvine, California, USA.
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Zampar GG, Kümmel A, Ewald J, Jol S, Niebel B, Picotti P, Aebersold R, Sauer U, Zamboni N, Heinemann M. Temporal system-level organization of the switch from glycolytic to gluconeogenic operation in yeast. Mol Syst Biol 2013; 9:651. [PMID: 23549479 PMCID: PMC3693829 DOI: 10.1038/msb.2013.11] [Citation(s) in RCA: 85] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2012] [Accepted: 02/21/2013] [Indexed: 01/16/2023] Open
Abstract
The diauxic shift in Saccharomyces cerevisiae is an ideal model to study how eukaryotic cells readjust their metabolism from glycolytic to gluconeogenic operation. In this work, we generated time-resolved physiological data, quantitative metabolome (69 intracellular metabolites) and proteome (72 enzymes) profiles. We found that the diauxic shift is accomplished by three key events that are temporally organized: (i) a reduction in the glycolytic flux and the production of storage compounds before glucose depletion, mediated by downregulation of phosphofructokinase and pyruvate kinase reactions; (ii) upon glucose exhaustion, the reversion of carbon flow through glycolysis and onset of the glyoxylate cycle operation triggered by an increased expression of the enzymes that catalyze the malate synthase and cytosolic citrate synthase reactions; and (iii) in the later stages of the adaptation, the shutting down of the pentose phosphate pathway with a change in NADPH regeneration. Moreover, we identified the transcription factors associated with the observed changes in protein abundances. Taken together, our results represent an important contribution toward a systems-level understanding of how this adaptation is realized.
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Affiliation(s)
- Guillermo G Zampar
- Molecular Systems Biology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Groningen, The Netherlands
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Stokes KA, Gilbert KL, Hall GM, Andrews RC, Thompson D. Different responses of selected hormones to three types of exercise in young men. Eur J Appl Physiol 2012; 113:775-83. [PMID: 22971724 DOI: 10.1007/s00421-012-2487-5] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2012] [Accepted: 08/29/2012] [Indexed: 11/30/2022]
Abstract
Exercise is a potent stimulus for release of growth hormone (GH), cortisol, testosterone and prolactin, and prolonged exercise inhibits insulin secretion. These responses seem to be specific to the type of exercise but this has been poorly characterised primarily because they have not been compared during exercise performed by the same individuals. We investigated hormone responses to resistance, sprint and endurance exercise in young men using a repeated measures design in which each subject served as their own control. Eight healthy non-obese young adults (18-25 years) were studied on four occasions in random order: 30-s cycle ergometer sprint (Sprint), 30-min resistance exercise bout (Resistance), 30-min cycle at 70 % VO(2max) (Endurance), and seated rest in the laboratory (Rest). Cortisol, GH, testosterone, prolactin, insulin and glucose concentrations were measured for 60 min after the four different interventions. Endurance and sprint exercise significantly increased GH, cortisol, prolactin and testosterone. Sprint exercise also increased insulin concentrations, whereas this decreased in response to endurance exercise. Resistance exercise significantly increased only testosterone and glucose. Sprint exercise elicited the largest response per unit of work, but the smallest response relative to mean work rate in all hormones. In conclusion, the nature and magnitude of the hormone response were influenced by exercise type, perhaps reflecting the roles of these hormones in regulating metabolism during and after resistance, sprint and endurance exercise.
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Affiliation(s)
- Keith A Stokes
- Department for Health, University of Bath, Claverton Down, Bath BA2-7AY, UK.
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Burmeister MA, Bracy DP, James FD, Holt RM, Ayala J, King EM, Wasserman DH, Drucker DJ, Ayala JE. Regulation of glucose kinetics during exercise by the glucagon-like peptide-1 receptor. J Physiol 2012; 590:5245-55. [PMID: 22890715 DOI: 10.1113/jphysiol.2012.234914] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
In response to oral glucose, glucagon-like peptide-1 receptor (Glp1r) knockout (Glp1r−/−) mice become hyperglycaemic due to impaired insulin secretion. Exercise also induces hyperglycaemia in Glp1r−/− mice. In contrast to oral glucose, exercise decreases insulin secretion. This implies that exercise-induced hyperglycaemia in Glp1r−/− mice results from the loss of a non-insulinotropic effect mediated by the Glp1r. Muscle glucose uptake (MGU) is normal in exercising Glp1r−/− mice. Thus, we hypothesize that exercise-induced hyperglycaemia in Glp1r−/− mice is due to excessive hepatic glucose production (HGP). Wild-type (Glp1r+/+) and Glp1r−/− mice implanted with venous and arterial catheters underwent treadmill exercise or remained sedentary for 30 min. [3-3H]glucose was used to estimate rates of glucose appearance (Ra), an index of HGP, and disappearance (Rd). 2[14C]deoxyglucose was used to assess MGU. Glp1r−/− mice displayed exercise-induced hyperglycaemia due to an excessive increase in Ra but normal Rd and MGU. Exercise-induced glucagon levels were ∼2-fold higher in Glp1r−/− mice, resulting in a ∼2-fold higher glucagon:insulin ratio. Since inhibition of the central Glp1r stimulates HGP, we tested whether intracerebroventricular (ICV) infusion of the Glp1r antagonist exendin(9–39) (Ex9) in Glp1r+/+ mice would result in exercise-induced hyperglycaemia. ICV Ex9 did not enhance glucose levels or HGP during exercise, suggesting that glucoregulatory effects of Glp1 during exercise are mediated via the pancreatic Glp1r. In conclusion, functional disruption of the Glp1r results in exercise-induced hyperglycaemia associated with an excessive increase in glucagon secretion and HGP. These results suggest an essential role for basal Glp1r signalling in the suppression of alpha cell secretion during exercise.
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Affiliation(s)
- M A Burmeister
- Metabolic Signaling and Disease Program, Diabetes and Obesity Research Center, Sanford-Burnham Medical Research Institute at Lake Nona, 6400 Sanger Road, Orlando, FL 32827, USA
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Exercise intensity modulation of hepatic lipid metabolism. J Nutr Metab 2012; 2012:809576. [PMID: 22545209 PMCID: PMC3321535 DOI: 10.1155/2012/809576] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2011] [Accepted: 01/11/2012] [Indexed: 12/12/2022] Open
Abstract
Lipid metabolism in the liver is complex and involves the synthesis and secretion of very low density lipoproteins (VLDL), ketone bodies, and high rates of fatty acid oxidation, synthesis, and esterification. Exercise training induces several changes in lipid metabolism in the liver and affects VLDL secretion and fatty acid oxidation. These alterations are even more conspicuous in disease, as in obesity, and cancer cachexia. Our understanding of the mechanisms leading to metabolic adaptations in the liver as induced by exercise training has advanced considerably in the recent years, but much remains to be addressed. More recently, the adoption of high intensity exercise training has been put forward as a means of modulating hepatic metabolism. The purpose of the present paper is to summarise and discuss the merit of such new knowledge.
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Park MY, Jang HH, Kim JB, Yoon HN, Lee JY, Lee YM, Kim JH, Park DS. Hog millet (Panicum miliaceum L.)-supplemented diet ameliorates hyperlipidemia and hepatic lipid accumulation in C57BL/6J-ob/ob mice. Nutr Res Pract 2011; 5:511-9. [PMID: 22259675 PMCID: PMC3259293 DOI: 10.4162/nrp.2011.5.6.511] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2011] [Revised: 11/28/2011] [Accepted: 12/01/2011] [Indexed: 01/18/2023] Open
Abstract
Dietary intake of whole grains reduces the incidence of chronic diseases such as obesity, diabetes, cardiovascular disease, and cancer. In an earlier study, we showed that Panicum miliaceum L. extract (PME) exhibited the highest anti-lipogenic activity in 3T3-L1 cells among extracts of nine different cereal grains tested. In this study, we hypothesized that PME in the diet would lead to weight loss and augmentation of hyperlipidemia by regulating fatty acid metabolism. PME was fed to ob/ob mice at 0%, 0.5%, or 1% (w/w) for 4 weeks. After the experimental period, body weight changes, blood serum and lipid profiles, hepatic fatty acid metabolism-related gene expression, and white adipose tissue (WAT) fatty acid composition were determined. We found that the 1% PME diet, but not the 0.5%, effectively decreased body weight, liver weight, and blood triglyceride and total cholesterol levels (P < 0.05) compared to obese ob/ob mice on a normal diet. Hepatic lipogenic-related gene (PPARα, L-FABP, FAS, and SCD1) expression decreased, whereas lipolysis-related gene (CPT1) expression increased in animals fed the 1% PME diet (P < 0.05). Long chain fatty acid content and the ratio of C18:1/C18:0 fatty acids decreased significantly in adipose tissue of animals fed the 1% PME diet (P < 0.05). Serum inflammatory mediators also decreased significantly in animals fed the 1% PME diet compared to those of the ob/ob control group (P < 0.05). These results suggest that PME is useful in the chemoprevention or treatment of obesity and obesity-related disorders.
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Affiliation(s)
- Mi-Young Park
- Functional Food & Nutrition Division, National Academy of Agricultural Science, Rural Develpoment Administration, Seodun-dong, Gwonseon-gu, Suwon-si 88-2, Gyeonggi 441-707, Korea
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34
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Wasserman DH, Cherrington AD. Regulation of Extramuscular Fuel Sources During Exercise. Compr Physiol 2011. [DOI: 10.1002/cphy.cp120123] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Van Proeyen K, Szlufcik K, Nielens H, Ramaekers M, Hespel P. Beneficial metabolic adaptations due to endurance exercise training in the fasted state. J Appl Physiol (1985) 2010; 110:236-45. [PMID: 21051570 DOI: 10.1152/japplphysiol.00907.2010] [Citation(s) in RCA: 122] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Training with limited carbohydrate availability can stimulate adaptations in muscle cells to facilitate energy production via fat oxidation. Here we investigated the effect of consistent training in the fasted state, vs. training in the fed state, on muscle metabolism and substrate selection during fasted exercise. Twenty young male volunteers participated in a 6-wk endurance training program (1-1.5 h cycling at ∼70% Vo(₂max), 4 days/wk) while receiving isocaloric carbohydrate-rich diets. Half of the subjects trained in the fasted state (F; n = 10), while the others ingested ample carbohydrates before (∼160 g) and during (1 g·kg body wt⁻¹·h⁻¹) the training sessions (CHO; n = 10). The training similarly increased Vo(₂max) (+9%) and performance in a 60-min simulated time trial (+8%) in both groups (P < 0.01). Metabolic measurements were made during a 2-h constant-load exercise bout in the fasted state at ∼65% pretraining Vo(₂max). In F, exercise-induced intramyocellular lipid (IMCL) breakdown was enhanced in type I fibers (P < 0.05) and tended to be increased in type IIa fibers (P = 0.07). Training did not affect IMCL breakdown in CHO. In addition, F (+21%) increased the exercise intensity corresponding to the maximal rate of fat oxidation more than did CHO (+6%) (P < 0.05). Furthermore, maximal citrate synthase (+47%) and β-hydroxyacyl coenzyme A dehydrogenase (+34%) activity was significantly upregulated in F (P < 0.05) but not in CHO. Also, only F prevented the development exercise-induced drop in blood glucose concentration (P < 0.05). In conclusion, F is more effective than CHO to increase muscular oxidative capacity and at the same time enhances exercise-induced net IMCL degradation. In addition, F but not CHO prevented drop of blood glucose concentration during fasting exercise.
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Affiliation(s)
- Karen Van Proeyen
- Research Centre for Exercise and Health, Department of Biomedical Kinesiology, K. U. Leuven, Leuven, Belgium
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Matiello R, Fukui RT, Silva ME, Rocha DM, Wajchenberg BL, Azhar S, Santos RF. Differential regulation of PGC-1alpha expression in rat liver and skeletal muscle in response to voluntary running. Nutr Metab (Lond) 2010; 7:36. [PMID: 20433743 PMCID: PMC2874794 DOI: 10.1186/1743-7075-7-36] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2010] [Accepted: 04/30/2010] [Indexed: 12/23/2022] Open
Abstract
BACKGROUND The beneficial actions of exercise training on lipid, glucose and energy metabolism and insulin sensitivity appear to be in part mediated by PGC-1alpha. Previous studies have shown that spontaneously exercised rats show at rest enhanced responsiveness to exogenous insulin, lower plasma insulin levels and increased skeletal muscle insulin sensitivity. This study was initiated to examine the functional interaction between exercise-induced modulation of skeletal muscle and liver PGC-1alpha protein expression, whole body insulin sensitivity, and circulating FFA levels as a measure of whole body fatty acid (lipid) metabolism. METHODS Two groups of male Wistar rats (2 Mo of age, 188.82 +/- 2.77 g BW) were used in this study. One group consisted of control rats placed in standard laboratory cages. Exercising rats were housed individually in cages equipped with running wheels and allowed to run at their own pace for 5 weeks. At the end of exercise training, insulin sensitivity was evaluated by comparing steady-state plasma glucose (SSPG) concentrations at constant plasma insulin levels attained during the continuous infusion of glucose and insulin to each experimental group. Subsequently, soleus and plantaris muscle and liver samples were collected and quantified for PGC-1alpha protein expression by Western blotting. Collected blood samples were analyzed for glucose, insulin and FFA concentrations. RESULTS Rats housed in the exercise wheel cages demonstrated almost linear increases in running activity with advancing time reaching to maximum value around 4 weeks. On an average, the rats ran a mean (Mean +/- SE) of 4.102 +/- 0.747 km/day and consumed significantly more food as compared to sedentary controls (P < 0.001) in order to meet their increased caloric requirement. Mean plasma insulin (P < 0.001) and FFA (P < 0.006) concentrations were lower in the exercise-trained rats as compared to sedentary controls. Mean steady state plasma insulin (SSPI) and glucose (SSPG) concentrations were not significantly different in sedentary control rats as compared to exercise-trained animals. Plantaris PGC-1alpha protein expression increased significantly from a 1.11 +/- 0.12 in the sedentary rats to 1.74 +/- 0.09 in exercising rats (P < 0.001). However, exercise had no effect on PGC-1alpha protein content in either soleus muscle or liver tissue. These results indicate that exercise training selectively up regulates the PGC-1alpha protein expression in high-oxidative fast skeletal muscle type such as plantaris muscle. CONCLUSION These data suggest that PGC-1alpha most likely plays a restricted role in exercise-mediated improvements in insulin resistance (sensitivity) and lowering of circulating FFA levels.
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Affiliation(s)
- Renata Matiello
- Laboratory of Medical Investigation, LIM-18, Division of Endocrinology and Metabolism, Hospital of Clinics, School of Medicine, University of Sao Paulo, Av Dr Arnaldo, 455, 3rd floor, room 3324, Sao Paulo, 01246-903, Brazil.
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Banzet S, Koulmann N, Simler N, Sanchez H, Chapot R, Serrurier B, Peinnequin A, Bigard X. Control of gluconeogenic genes during intense/prolonged exercise: hormone-independent effect of muscle-derived IL-6 on hepatic tissue and PEPCK mRNA. J Appl Physiol (1985) 2009; 107:1830-9. [PMID: 19850730 DOI: 10.1152/japplphysiol.00739.2009] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Prolonged intense exercise is challenging for the liver to maintain plasma glucose levels. Hormonal changes cannot fully account for exercise-induced hepatic glucose production (HGP). Contracting skeletal muscles release interleukin-6 (IL-6), a cytokine able to increase endogenous glucose production during exercise. However, whether this is attributable to a direct effect of IL-6 on liver remains unknown. Here, we studied hepatic glycogen, gluconeogenic genes, and IL-6 signaling in response to one bout of exhaustive running exercise in rats. To determine whether IL-6 can modulate gluconeogenic gene mRNA independently of exercise, we injected resting rats with recombinant IL-6. Exhaustive exercise resulted in a profound decrease in liver glycogen and an increase in gluconeogenic gene mRNA levels, phosphoenolpyruvate-carboxykinase (PEPCK), glucose-6-phosphatase (G6P), and peroxisome proliferator-activated receptor-gamma coactivator-1alpha (PGC-1alpha), suggesting a key role for gluconeogenesis in hepatic glucose production. This was associated to an active IL-6 signaling in liver tissue, as shown by signal transducer and activator of transcription and CAAT/enhancer binding protein-beta phosphorylation and IL-6-responsive gene mRNA levels at the end of exercise. Recombinant IL-6 injection resulted in an increase in IL-6-responsive gene mRNA levels in the liver. We found a dose-dependent increase in PEPCK gene mRNA strongly correlated with IL-6-induced gene mRNA levels. No changes in G6P and PGC-1alpha mRNA levels were found. Taken together, our results suggest that, during very demanding exercise, muscle-derived IL-6 could help increase HGP by directly upregulating PEPCK mRNA abundance.
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Affiliation(s)
- Sébastien Banzet
- Department of Human Factors, Military Health Service Research Center, La Tronche, France.
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Gomes FR, Rezende EL, Malisch JL, Lee SK, Rivas DA, Kelly SA, Lytle C, Yaspelkis BB, Garland T. Glycogen storage and muscle glucose transporters (GLUT-4) of mice selectively bred for high voluntary wheel running. J Exp Biol 2009; 212:238-48. [PMID: 19112143 PMCID: PMC2721000 DOI: 10.1242/jeb.025296] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/10/2008] [Indexed: 01/09/2023]
Abstract
To examine the evolution of endurance-exercise behaviour, we have selectively bred four replicate lines of laboratory mice (Mus domesticus) for high voluntary wheel running (;high runner' or HR lines), while also maintaining four non-selected control (C) lines. By generation 16, HR mice ran approximately 2.7-fold more than C mice, mainly by running faster (especially in females), a differential maintained through subsequent generations, suggesting an evolutionary limit of unknown origin. We hypothesized that HR mice would have higher glycogen levels before nightly running, show greater depletion of those depots during their more intense wheel running, and have increased glycogen synthase activity and GLUT-4 protein in skeletal muscle. We sampled females from generation 35 at three times (photophase 07:00 h-19:00 h) during days 5-6 of wheel access, as in the routine selection protocol: Group 1, day 5, 16:00 h-17:30 h, wheels blocked from 13:00 h; Group 2, day 6, 02:00 h-03:30 h (immediately after peak running); and Group 3, day 6, 07:00 h-08:30 h. An additional Group 4, sampled 16:00 h-17:30 h, never had wheels. HR individuals with the mini-muscle phenotype (50% reduced hindlimb muscle mass) were distinguished for statistical analyses comparing C, HR normal, and HR mini. HR mini ran more than HR normal, and at higher speeds, which might explain why they have been favored by the selective-breeding protocol. Plasma glucose was higher in Group 1 than in Group 4, indicating a training effect (phenotypic plasticity). Without wheels, no differences in gastrocnemius GLUT-4 were observed. After 5 days with wheels, all mice showed elevated GLUT-4, but HR normal and mini were 2.5-fold higher than C. At all times and irrespective of wheel access, HR mini showed approximately three-fold higher [glycogen] in gastrocnemius and altered glycogen synthase activity. HR mini also showed elevated glycogen in soleus when sampled during peak running. All mice showed some glycogen depletion during nightly wheel running, in muscles and/or liver, but the magnitude of this depletion was not large and hence does not seem to be limiting to the evolution of even-higher wheel running.
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Affiliation(s)
- Fernando R Gomes
- Department of Biology, University of California, Riverside, CA 92521, USA
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Hoene M, Lehmann R, Hennige AM, Pohl AK, Häring HU, Schleicher ED, Weigert C. Acute regulation of metabolic genes and insulin receptor substrates in the liver of mice by one single bout of treadmill exercise. J Physiol 2008; 587:241-52. [PMID: 19001047 DOI: 10.1113/jphysiol.2008.160275] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Acute exercise performance represents a major metabolic challenge for the skeletal muscle, but also for the liver as the most important source of energy. However the molecular adaptation of the liver to one single bout of exercise is largely unknown. C57BL/6 mice performed a 60 min treadmill run at high aerobic intensity. Liver, soleus and white gastrocnemius muscle were removed immediately after exercise. The single bout of exercise resulted in a very rapid and pronounced induction of hepatic metabolic enzymes and regulators of metabolism or transcription: glucose-6-phosphatase (G6Pase; 3-fold), pyruvate dehydrogenase kinase-4 (PDK4; 4.8-fold), angiopoietin-like 4 (2.1-fold), insulin receptor substrate (IRS)-2 (5.1-fold), peroxisome proliferator activated receptor-gamma coactivator 1alpha (PGC-1alpha; 3-fold). In soleus and white gastrocnemius muscle the up-regulation of IRS-2 and PDK4 was less pronounced compared with the liver and no significant induction of PGC-1alpha could be detected at this early time point. Activation of AMPK was found in both liver and white gastrocnemius muscle as phosphorylation of Thr-172. The induction of endogenous insulin secretion by a glucose load directly after the exercise bout resulted in a significantly higher PKB/Akt phosphorylation in the liver of exercised mice. The markedly enhanced IRS-2 protein amount, and presumably reduced serine/threonine phosphorylation of the IRS proteins induced by the acute exercise could be responsible for this enhanced action of insulin. In conclusion, acute exercise induced a rapid and pronounced transcriptional adaptation in the liver, and regulated hepatic IRS proteins leading to improved cellular insulin signal transduction.
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Affiliation(s)
- Miriam Hoene
- Division of Pathobiochemistry and Clinical Chemistry, University of Tuebingen, Otfried-Mueller-Strasse 10, D-72076 Tuebingen, Germany
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Dietze GJ, Henriksen EJ. Angiotensin-converting enzyme in skeletal muscle: sentinel of blood pressure control and glucose homeostasis. J Renin Angiotensin Aldosterone Syst 2008; 9:75-88. [PMID: 18584583 DOI: 10.3317/jraas.2008.011] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
Recent evidence suggests a coordinated regulation by the local renin-angiotensin system (RAS) and tissue kallikrein-kinin system (TKKS) of blood flow and substrate supply in oxidative red myofibres of skeletal muscle tissue during endurance exercise. The performance of these myofibres is dependent on the increased oxidation of substrates facilitated by augmenting nutritive blood flow and glucose uptake. Humoral factors released by the contracting fibres, such as adenosine and kinins, are suggested to be responsible for this metabolic adjustment. The considerable drain of blood volume and the enormous consumption of glucose during endurance exercise require a control mechanism for the maintenance of blood pressure (BP) and glucose homeostasis. This is achieved by the sympathetic nervous system and its subordinate RAS, which is located in the nutritive vessels and parenchyma of the red myofibres. The angiotensin-converting enzyme (ACE) is the primary enzyme responsible for kinin degradation during exercise, underscoring the important interrelationship between the RAS and the TKKS in the critical role of kinins in the multifactorial regulation of muscle bioenergetics and glucose and BP homeostasis. Importantly, overactivity of the ACE, as occurs in individuals displaying risk factors such as overweight, causes exaggerated BP response and reduced glucose disposal. If they persist over years, compensatory responses to this ACE overactivity, such as hypersecretion of insulin and compliance of the vessel walls, will inevitably be exhausted, leading ultimately to the manifestation of type 2 diabetes and hypertension. This concept also provides a unifying explanation for the beneficial effects of ACE-inhibitors and Angiotensin II receptor antagonists in the treatment of hypertension and insulin resistance.
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Affiliation(s)
- Guenther J Dietze
- Hypertension and Diabetes Research Unit, Max Grundig Clinic, Buehl, Germany
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Abstract
BACKGROUND Regulation of plasma glucose concentration for type 1 diabetic patients is challenging, and exercise is an added complication. From a metabolic prospective, the significant exercise-induced effects are increased glucose uptake rate by the working tissues, increased hepatic glucose release to maintain overall glucose homeostasis, and decreased plasma insulin concentration. During prolonged exercise, glucose levels drop significantly because of the decrease in hepatic glucose production. With the long-term goal of developing a closed-loop insulin delivery system operating under various physiological conditions, it is necessary to develop a model that is capable of predicting blood glucose concentration at rest and during physical activity. METHODS A minimal model developed previously was extended to include the major effects of exercise on plasma glucose and insulin levels. Differential equations were developed to capture the exercise-induced dynamics of plasma insulin clearance and the elevation of glucose uptake and hepatic glucose production rates. The decreasing liver glucose output resulting from prolonged exercise was modeled using an equation depending on exercise intensity and duration. RESULTS The exercise model successfully captured the glucose and insulin dynamics during short- and long-term exercise. Model predictions of glucose and insulin dynamics during the postexercise recovery period were also consistent with literature data. CONCLUSION The model successfully emulated the physiological effects of exercise on blood glucose and insulin levels. This extended model may provide a new disturbance test platform for the development of closed-loop glucose control algorithms.
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Affiliation(s)
- Anirban Roy
- Department of Chemical and Petroleum Engineering, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, USA.
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Shibakusa T, Mizunoya W, Okabe Y, Matsumura S, Iwaki Y, Okuno A, Shibata K, Inoue K, Fushiki T. Transforming growth factor-beta in the brain is activated by exercise and increases mobilization of fat-related energy substrates in rats. Am J Physiol Regul Integr Comp Physiol 2007; 292:R1851-61. [PMID: 17303681 DOI: 10.1152/ajpregu.00632.2006] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We have recently reported that inhibition of transforming growth factor (TGF)-beta in the brain reduced fat-related energy substrates concentrations in response to exercise. We investigated the relevance between the mobilization of fat-related energy substrates (nonesterified fatty acid and ketone bodies) during exercise and the effects of TGF-beta in the brain. Low-intensity exercise was simulated by contraction of the hindlimbs, induced by electrical stimulation at 2 Hz in anesthetized rats (Sim-Ex). As with actual exercise, it was confirmed that mobilization of carbohydrate-related energy substrates (glucose and lactic acid) occurred immediately after the onset of Sim-Ex, and mobilization of fat-related energy substrates followed thereafter. The timing of mobilization of fat-related substrates corresponded to that of the increase in TGF-beta in cerebrospinal fluid (CSF) in Sim-Ex. The level of TGF-beta in CSF significantly increased after 10 min of Sim-Ex and remained elevated until 30 min of Sim-Ex. Intracisternal administration of TGF-beta caused rapid mobilization of fat-related energy substrates. Meanwhile, there were no effects on the changes in carbohydrate-related substrates. The levels of catecholamines were slightly elevated after TGF-beta administration, and, although not significantly in statistical terms, we consider that at least a part of TGF-beta signal was transducted via the sympathetic nervous system because of these increases. These data indicate that TGF-beta in the brain is closely related to the mobilization of fat-related energy substrates during low-intensity exercise. We hypothesized that the central nervous system plays a role in the regulation of energy metabolism during low-intensity exercise and this may be mediated by TGF-beta.
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Affiliation(s)
- Tetsuro Shibakusa
- Laboratory of Nutrition Chemistry, Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto Univ, Kitashirakawa, Sakyo, Kyoto, Japan
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Camacho RC, Donahue EP, James FD, Berglund ED, Wasserman DH. Energy state of the liver during short-term and exhaustive exercise in C57BL/6J mice. Am J Physiol Endocrinol Metab 2006; 290:E405-8. [PMID: 16219665 DOI: 10.1152/ajpendo.00385.2005] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
A portal venous 5-aminoimidazole-4-carboxamide-1-beta-D-ribofuranoside infusion that results in hepatic 5-aminoimidazole-4-carboxamide-1-beta-D-ribosyl-5-monophosphate (ZMP) concentrations of approximately 4 micromol/g liver increases hepatic glycogenolysis and glucose output. ZMP is an AMP analog that mimics the regulatory actions of this nucleotide. The aim of this study was to measure hepatic AMP concentrations in response to increasing energy requirements to test the hypothesis that AMP achieves concentrations during exercise, consistent with a role in stimulation of hepatic glucose metabolism. Male C57BL/6J mice (27.4+/- 0.4 g) were subjected to 35 min of rest [sedentary (SED), n=8], underwent short-term (ST, 35 min) moderate (20 m/min, 5% grade) exercise (n=8), or underwent treadmill exercise under similar conditions but until exhaustion (EXH, n=8). Hepatic AMP concentrations were 0.82+/- 0.05, 1.17+/- 0.11, and 2.52+/- 0.16 micromol/g liver in SED, ST, and EXH mice, respectively (P< 0.05). Hepatic energy charge was 0.66+/- 0.01, 0.58+/- 0.02, and 0.33+/- 0.22 in SED, ST, and EXH mice, respectively (P< 0.05). Hepatic glycogen was 11.6+/- 1.0, 8.8+/- 2.2, and 0.0+/- 0.1 mg/g liver in SED, ST, and EXH mice, respectively (P< 0.05). Hepatic AMPK (Thr(172)) phosphorylation was 1.00+/- 0.14, 1.96+/- 0.16, and 7.44+/- 0.63 arbitrary units in SED, ST, and EXH mice, respectively (P< 0.05). Thus exercise increases hepatic AMP concentrations. These data suggest that the liver is highly sensitive to metabolic demands, as evidenced by dramatic changes in cellular energy indicators (AMP) and sensors thereof (AMP-activated protein kinase). In conclusion, AMP is sensitively regulated, consistent with it having an important role in hepatic metabolism.
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Affiliation(s)
- Raul C Camacho
- Department of Molecular Physiology and Biolphysics and Mouse Metabolic Phenotyping Center, Vanderbilt University School of Medicine, Nashville, TN, USA.
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Iwashita S, Williams P, Jabbour K, Ueda T, Kobayashi H, Baier S, Flakoll PJ. Impact of glutamine supplementation on glucose homeostasis during and after exercise. J Appl Physiol (1985) 2005; 99:1858-65. [PMID: 16037406 DOI: 10.1152/japplphysiol.00305.2005] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The interaction of glutamine availability and glucose homeostasis during and after exercise was investigated, measuring whole body glucose kinetics with [3-3H]glucose and net organ balances of glucose and amino acids (AA) during basal, exercise, and postexercise hyperinsulinemic-euglycemic clamp periods in six multicatheterized dogs. Dogs were studied twice in random treatment order: once with glutamine (12 micromol.kg(-1).min(-1); Gln) and once with saline (Con) infused intravenously during and after exercise. Plasma glucose fell by 7 mg/dl with exercise in Con (P < 0.05), but it did not fall with Gln. Gln further stimulated whole body glucose production and utilization an additional 24% above a normal exercise response (P < 0.05). Net hepatic uptake of glutamine and alanine was greater with Gln than Con during exercise (P < 0.05). Net hepatic glucose output was increased sevenfold during exercise with Gln (P < 0.05) but not with Con. Net hindlimb glucose uptake was increased similarly during exercise in both groups (P < 0.05). During the postexercise hyperinsulinemic-euglycemic period, glucose production decreased to near zero with Con, but it did not decrease below basal levels with Gln. Gln increased glucose utilization by 16% compared with Con after exercise (P < 0.05). Furthermore, net hindlimb glucose uptake in the postexercise period was increased approximately twofold vs. basal with Gln (P < 0.05) but not with Con. Net hepatic uptake of glutamine during the postexercise period was threefold greater for Gln than Con (P < 0.05). In conclusion, glutamine availability modulates glucose homeostasis during and after exercise, which may have implications for postexercise recovery.
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Affiliation(s)
- Soh Iwashita
- Center for Designing Foods to Improve Nutrition, Department of Food Science and Human Nutrition, Iowa State University, Ames, Iowa 50011, USA
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Pencek RR, Shearer J, Camacho RC, James FD, Lacy DB, Fueger PT, Donahue EP, Snead W, Wasserman DH. 5-Aminoimidazole-4-carboxamide-1-beta-D-ribofuranoside causes acute hepatic insulin resistance in vivo. Diabetes 2005; 54:355-60. [PMID: 15677492 DOI: 10.2337/diabetes.54.2.355] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
The infusion of 5-aminoimidazole-4-carboxamide-1-beta-D-ribofuranoside (AICAR) causes a rise in tissue concentrations of the AMP analog 5-aminoimidazole-4-carboxamide-1-beta-D-ribofuranotide (ZMP), which mimics an elevation of cellular AMP levels. The purpose of this work was to determine the effect of raising hepatic ZMP levels on hepatic insulin action in vivo. Dogs had sampling and infusion catheters as well as flow probes implanted 16 days before an experiment. After an 18-h fast, blood glucose was 82 +/- 1 mg/dl and basal net hepatic glucose output 1.5 +/- 0.2 mg . kg(-1) . min(-1). Dogs received portal venous glucose (3.2 mg . kg(-1) . min(-1)), peripheral venous somatostatin, and basal portal venous glucagon infusions from -90 to 60 min. Physiological hyperinsulinemia was established with a portal insulin infusion (1.2 mU . kg(-1) . min(-1)). Peripheral venous glucose infusion was used to clamp arterial blood glucose at 150 mg/dl. Starting at t = 0 min, dogs received portal venous AICAR infusions of 0, 1, or 2 mg . kg(-1) . min(-1). Net hepatic glucose uptake was 2.4 +/- 0.5 mg . kg(-1) . min(-1) (mean of all groups) before t = 0 min. In the absence of AICAR, net hepatic glucose uptake was 1.9 +/- 0.4 mg . kg(-1) . min(-1) at t = 60 min. The lower-dose AICAR infusion caused a complete suppression of net hepatic glucose uptake (-1.0 +/- 1.7 mg . kg(-1) . min(-1) at t = 60 min). The higher AICAR dose resulted in a profound shift in hepatic glucose balance from net uptake to a marked net output (-6.1 +/- 1.9 mg . kg(-1) . min(-1) at t = 60 min), even in the face of hyperglycemia and hyperinsulinemia. These data show that elevations in hepatic ZMP concentrations, induced by portal venous AICAR infusion, cause acute hepatic insulin resistance. These findings have important implications for the targeting of AMP kinase for the treatment of insulin resistance, using AMP analogs.
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Affiliation(s)
- R Richard Pencek
- Department of Molecular Physiology and Biophysics, Diabetes Research and Training Center, Vanderbilt University School of Medicine, Nashville, TN 37232-0615, USA.
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Pencek RR, James FD, Lacy DB, Jabbour K, Williams PE, Fueger PT, Wasserman DH. Exercise-induced changes in insulin and glucagon are not required for enhanced hepatic glucose uptake after exercise but influence the fate of glucose within the liver. Diabetes 2004; 53:3041-7. [PMID: 15561932 DOI: 10.2337/diabetes.53.12.3041] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
To test whether pancreatic hormonal changes that occur during exercise are necessary for the postexercise enhancement of insulin-stimulated net hepatic glucose uptake, chronically catheterized dogs were exercised on a treadmill or rested for 150 min. At the onset of exercise, somatostatin was infused into a peripheral vein, and insulin and glucagon were infused in the portal vein to maintain basal levels (EX-Basal) or simulate the response to exercise (EX-Sim). Glucose was infused as needed to maintain euglycemia during exercise. After exercise or rest, somatostatin infusion was continued in exercised dogs and initiated in dogs that had remained sedentary. In addition, basal glucagon, glucose, and insulin were infused in the portal vein for 150 min to create a hyperinsulinemic-hyperglycemic clamp in EX-Basal, EX-Sim, and sedentary dogs. Steady-state measurements were made during the final 50 min of the clamp. During exercise, net hepatic glucose output (mg x kg(-1) x min(-1)) rose in EX-Sim (7.6 +/- 2.8) but not EX-Basal (1.9 +/- 0.3) dogs. During the hyperinsulinemic-hyperglycemic clamp that followed either exercise or rest, net hepatic glucose uptake (mg x kg(-1) x min(-1)) was elevated in both EX-Basal (4.0 +/- 0.7) and EX-Sim (4.6 +/- 0.5) dogs compared with sedentary dogs (2.0 +/- 0.3). Despite this elevation in net hepatic glucose uptake after exercise, glucose incorporation into hepatic glycogen, determined using [3-3H]glucose, was not different in EX-Basal and sedentary dogs, but was 50 +/- 30% greater in EX-Sim dogs. Exercise-induced changes in insulin and glucagon, and consequent glycogen depletion, are not required for the increase in net hepatic glucose uptake after exercise but result in a greater fraction of the glucose consumed by the liver being directed to glycogen.
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Affiliation(s)
- R Richard Pencek
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee, USA.
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Mondal M, Prakash BS. Changes in plasma non-esterified fatty acids, glucose and alpha-amino nitrogen and their relationship with body weight and plasma growth hormone in growing buffaloes (Bubalus bubalis). J Anim Physiol Anim Nutr (Berl) 2004; 88:223-8. [PMID: 15189427 DOI: 10.1111/j.1439-0396.2004.00476.x] [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: 11/29/2022]
Abstract
A study was undertaken to investigate the changes of plasma non-esterified fatty acids (NEFA), glucose and alpha-amino nitrogen and their relationship with age, body weight (BW) and plasma growth hormone (GH) in growing buffaloes. For the purpose, six growing female Murrah buffalo calves of 6-8 months of age were selected on the basis of their BW and fed according to Kearl standard (Nutrient Requirements of Ruminants in Developing Countries, International Feedstuffs Institute, Utah State University, Utah, USA, 1982, p. 89) for growing buffaloes (target growth rate 500 g/day) to meet energy and protein requirement of the animals. Blood samples collected at fortnight intervals for 1 year were analysed for plasma NEFA, glucose, alpha-amino nitrogen and GH. The animals were also weighed at fortnight intervals. Plasma NEFA and glucose levels were found to decrease (p < 0.01) with age. Unlike plasma NEFA and glucose, plasma alpha-amino nitrogen level increased (p < 0.01) as the buffaloes become older. Plasma NEFA and glucose concentrations in growing buffaloes were found to be positively correlated with plasma GH (r = 0.379 and 0.420 respectively), but these were non-significant (p > 0.01). However, plasma NEFA and glucose showed a good correlation (p < 0.01; r = 0.780 and 0.652 respectively) with plasma GH per 100 kg live weight. Plasma alpha-amino nitrogen exhibited non-significant (p > 0.01) negative correlation (r = -0.295) with plasma GH but a negative correlation (p < 0.01; r = -0.641) with GH per 100 kg BW. So, plasma metabolites showed a definite pattern of change during growth and these have a significant (p < 0.01) correlation with plasma GH per 100 kg BW than GH.
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Affiliation(s)
- M Mondal
- Dairy Cattle Physiology Division, National Dairy Research Institute, Karnal, Haryana, India.
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Pencek RR, James F, Lacy DB, Jabbour K, Williams PE, Fueger PT, Wasserman DH. Interaction of insulin and prior exercise in control of hepatic metabolism of a glucose load. Diabetes 2003; 52:1897-903. [PMID: 12882903 DOI: 10.2337/diabetes.52.8.1897] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
To determine if prior exercise enhances insulin-stimulated extraction of glucose by the liver, chronically catheterized dogs were submitted to 150 min of treadmill exercise or rest. After exercise or rest, dogs received portal glucose (18 micro mol x kg(-1) x min(-1)), peripheral somatostatin, and basal portal glucagon infusions from t = 0 to 150 min. A peripheral glucose infusion was used to clamp arterial blood glucose at 8.3 mmol/l. Insulin was infused into the portal vein to create either basal levels or mild hyperinsulinemia. Prior exercise did not increase whole-body glucose disposal in the presence of basal insulin (25.5 +/- 1.5 vs. 20.3 +/- 1.7 micro mol x kg(-1) x min(-1)), but resulted in a marked enhancement in the presence of elevated insulin (97.2 +/- 15.1 vs. 64.4 +/- 7.4 micro mol x kg(-1) x min(-1)). Prior exercise also increased net hepatic glucose uptake in the presence of both basal insulin (7.5 +/- 1.2 vs. 2.9 +/- 2.4 micro mol x kg(-1) x min(-1)) and elevated insulin (22.0 +/- 3.5 vs. 11.5 +/- 1.8 micro mol x kg(-1) x min(-1)). Likewise, net hepatic glucose fractional extraction was increased by prior exercise with both basal insulin (0.04 +/- 0.01 vs. 0.01 +/- 0.01 micro mol x kg(-1) x min(-1)) and elevated insulin (0.10 +/- 0.01 vs. 0.05 +/- 0.01). Hepatic glycogen synthesis was increased by elevated insulin, but was not enhanced by prior exercise. Although the increase in glucose extraction after exercise could be ascribed to increased insulin action, the increase in hepatic glycogen synthesis was independent of it.
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Affiliation(s)
- R Richard Pencek
- Department of Molecular Physiology & Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee, USA.
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Roef MJ, de Meer K, Kalhan SC, Straver H, Berger R, Reijngoud DJ. Gluconeogenesis in humans with induced hyperlactatemia during low-intensity exercise. Am J Physiol Endocrinol Metab 2003; 284:E1162-71. [PMID: 12604505 DOI: 10.1152/ajpendo.00425.2002] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We studied the role of lactate in gluconeogenesis (GNG) during exercise in untrained fasting humans. During the final hour of a 4-h cycle exercise at 33-34% maximal O(2) uptake, seven subjects received, in random order, either a sodium lactate infusion (60 micromol x kg(-1) x min(-1)) or an isomolar sodium bicarbonate infusion. The contribution of lactate to gluconeogenic glucose was quantified by measuring (2)H incorporation into glucose after body water was labeled with deuterium oxide, and glucose rate of appearance (R(a)) was measured by [6,6-(2)H(2)]glucose dilution. Infusion of lactate increased lactate concentration to 4.4 +/- 0.6 mM (mean +/- SE). Exercise induced a decrease in blood glucose concentration from 5.0 +/- 0.2 to 4.2 +/- 0.3 mM (P < 0.05); lactate infusion abolished this decrease (5.0 +/- 0.3 mM; P < 0.001) and increased glucose R(a) compared with bicarbonate infusion (P < 0.05). Lactate infusion increased both GNG from lactate (29 +/- 4 to 46 +/- 4% of glucose R(a), P < 0.001) and total GNG. We conclude that lactate infusion during low-intensity exercise in fasting humans 1). increased GNG from lactate and 2). increased glucose production, thus increasing the blood glucose concentration. These results indicate that GNG capacity is available in humans after an overnight fast and can be used to sustain blood glucose levels during low-intensity exercise when lactate, a known precursor of GNG, is available at elevated plasma levels.
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Affiliation(s)
- Mark J Roef
- Department of Pediatric Gastroenterology, VU University Medical Center, 1007 MB Amsterdam, The Netherlands
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