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Hatch K, Lischka F, Wang M, Xu X, Stimpson CD, Barvir T, Cramer NP, Perl DP, Yu G, Browne CA, Dickstein DL, Galdzicki Z. The role of microglia in neuronal and cognitive function during high altitude acclimatization. Sci Rep 2024; 14:18981. [PMID: 39152179 PMCID: PMC11329659 DOI: 10.1038/s41598-024-69694-9] [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: 03/15/2024] [Accepted: 08/07/2024] [Indexed: 08/19/2024] Open
Abstract
Due to their interactions with the neurovasculature, microglia are implicated in maladaptive responses to hypobaric hypoxia at high altitude (HA). To explore these interactions at HA, pharmacological depletion of microglia with the colony-stimulating factor-1 receptor inhibitor, PLX5622, was employed in male C57BL/6J mice maintained at HA or sea level (SL) for 3-weeks, followed by assessment of ex-vivo hippocampal long-term potentiation (LTP), fear memory recall and microglial dynamics/physiology. Our findings revealed that microglia depletion decreased LTP and reduced glucose levels by 25% at SL but did not affect fear memory recall. At HA, the absence of microglia did not significantly alter HA associated deficits in fear memory or HA mediated decreases in peripheral glucose levels. In regard to microglial dynamics in the cortex, HA enhanced microglial surveillance activity, ablation of microglia resulted in increased chemotactic responses and decreased microglia tip proliferation during ball formation. In contrast, vessel ablation increased cortical microglia tip path tortuosity. In the hippocampus, changes in microglial dynamics were only observed in response to vessel ablation following HA. As the hippocampus is critical for learning and memory, poor hippocampal microglial context-dependent adaptation may be responsible for some of the enduring neurological deficits associated with HA.
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Affiliation(s)
- Kathleen Hatch
- Neuroscience Graduate Program, Uniformed Services University of the Health Sciences, Bethesda, MD, 20814, USA
- The Henry M. Jackson Foundation for the Advancement of Military Medicine Inc. (HJF), 6720A Rockledge Drive, Bethesda, MD, 20817, USA
- Department of Anatomy, Physiology and Genetics, Uniformed Services University of the Health Sciences, Bethesda, MD, 20814, USA
- Department of Pathology, Uniformed Services University of the Health Sciences, Bethesda, MD, 20814, USA
| | - Fritz Lischka
- The Henry M. Jackson Foundation for the Advancement of Military Medicine Inc. (HJF), 6720A Rockledge Drive, Bethesda, MD, 20817, USA
- Department of Anatomy, Physiology and Genetics, Uniformed Services University of the Health Sciences, Bethesda, MD, 20814, USA
| | - Mengfan Wang
- Department of Electrical and Computer Engineering, Virginia Tech, Arlington, VA, USA
| | - Xiufen Xu
- The Henry M. Jackson Foundation for the Advancement of Military Medicine Inc. (HJF), 6720A Rockledge Drive, Bethesda, MD, 20817, USA
- Department of Anatomy, Physiology and Genetics, Uniformed Services University of the Health Sciences, Bethesda, MD, 20814, USA
| | - Cheryl D Stimpson
- The Henry M. Jackson Foundation for the Advancement of Military Medicine Inc. (HJF), 6720A Rockledge Drive, Bethesda, MD, 20817, USA
- Department of Pathology, Uniformed Services University of the Health Sciences, Bethesda, MD, 20814, USA
| | - Tara Barvir
- The Henry M. Jackson Foundation for the Advancement of Military Medicine Inc. (HJF), 6720A Rockledge Drive, Bethesda, MD, 20817, USA
- Department of Anatomy, Physiology and Genetics, Uniformed Services University of the Health Sciences, Bethesda, MD, 20814, USA
| | - Nathan P Cramer
- The Henry M. Jackson Foundation for the Advancement of Military Medicine Inc. (HJF), 6720A Rockledge Drive, Bethesda, MD, 20817, USA
- Department of Anatomy, Physiology and Genetics, Uniformed Services University of the Health Sciences, Bethesda, MD, 20814, USA
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, 655 W. Baltimore Street, Baltimore, MD, 21201, USA
| | - Daniel P Perl
- Department of Pathology, Uniformed Services University of the Health Sciences, Bethesda, MD, 20814, USA
| | - Guoqiang Yu
- Department of Electrical and Computer Engineering, Virginia Tech, Arlington, VA, USA
| | - Caroline A Browne
- Neuroscience Graduate Program, Uniformed Services University of the Health Sciences, Bethesda, MD, 20814, USA
- The Henry M. Jackson Foundation for the Advancement of Military Medicine Inc. (HJF), 6720A Rockledge Drive, Bethesda, MD, 20817, USA
- Department of Pharmacology and Molecular Therapeutics, Uniformed Services University of the Health Sciences, Bethesda, MD, 20814, USA
| | - Dara L Dickstein
- Neuroscience Graduate Program, Uniformed Services University of the Health Sciences, Bethesda, MD, 20814, USA
- The Henry M. Jackson Foundation for the Advancement of Military Medicine Inc. (HJF), 6720A Rockledge Drive, Bethesda, MD, 20817, USA
- Department of Pathology, Uniformed Services University of the Health Sciences, Bethesda, MD, 20814, USA
| | - Zygmunt Galdzicki
- Neuroscience Graduate Program, Uniformed Services University of the Health Sciences, Bethesda, MD, 20814, USA.
- Department of Anatomy, Physiology and Genetics, Uniformed Services University of the Health Sciences, Bethesda, MD, 20814, USA.
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Costalat G, Lemaitre F, Ramos S, Renshaw GMC. Intermittent normobaric hypoxia alters substrate partitioning and muscle oxygenation in individuals with obesity: implications for fat burning. Am J Physiol Regul Integr Comp Physiol 2024; 326:R147-R159. [PMID: 38047315 DOI: 10.1152/ajpregu.00153.2023] [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: 06/23/2023] [Revised: 11/28/2023] [Accepted: 11/29/2023] [Indexed: 12/05/2023]
Abstract
This single-blind, crossover study aimed to measure and evaluate the short-term metabolic responses to continuous and intermittent hypoxic patterns in individuals with obesity. Indirect calorimetry was used to quantify changes in resting metabolic rate (RMR), carbohydrate (CHOox, %CHO), and fat oxidation (FATox, %FAT) in nine individuals with obesity pre and post: 1) breathing normoxic air [normoxic sham control (NS-control)], 2) breathing continuous hypoxia (CH), or 3) breathing intermittent hypoxia (IH). A mean peripheral oxygen saturation ([Formula: see text]) of 80-85% was achieved over a total of 45 min of hypoxia. Throughout each intervention, pulmonary gas exchanges, oxygen consumption (V̇o2) carbon dioxide production (V̇co2), and deoxyhemoglobin concentration (Δ[HHb]) in the vastus lateralis were measured. Both RMR and CHOox measured pre- and postinterventions were unchanged following each treatment: NS-control, CH, or IH (all P > 0.05). Conversely, a significant increase in FATox was evident between pre- and post-IH (+44%, P = 0.048). Although the mean Δ[HHb] values significantly increased during both IH and CH (P < 0.05), the greatest zenith of Δ[HHb] was achieved in IH compared with CH (P = 0.002). Furthermore, there was a positive correlation between Δ[HHb] and the shift in FATox measured pre- and postintervention. It is suggested that during IH, the increased bouts of muscle hypoxia, revealed by elevated Δ[HHb], coupled with cyclic periods of excess posthypoxia oxygen consumption (EPHOC, inherent to the intermittent pattern) played a significant role in driving the increase in FATox post-IH.
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Affiliation(s)
- Guillaume Costalat
- Adaptations Physiologiques à l'Exercice et Réadaptation à l'Effort Laboratory, Faculty of Sport Sciences, University of Picardie Jules Verne, Amiens, France
| | - Frederic Lemaitre
- Centre d'Etude des Transformations des Activités Physiques et Sportives Laboratory, Faculty of Sport Sciences, Normandy University, Rouen, France
- Centre de Recherche Insulaire et Observatoire de l'Environnement, Centre National de la Recherche Scientifique-Ecole Pratique des Hautes Etudes-Université de Perpignan Via Domitia, Moorea, French Polynesia
| | - Sandra Ramos
- School of Medicine and Dentistry, Griffith University, Gold Coast, Queensland, Australia
| | - Gillian M C Renshaw
- Hypoxia and Ischemia Research Unit, School of Health Sciences and Social Work, Griffith University, Gold Coast, Queensland, Australia
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Chan JS, Chiew AE, Rimke AN, Chan G, Rampuri ZH, Kozak MD, Boulé NG, Steinback CD, Davenport MH, Day TA. Blood glucose concentration is unchanged during exposure to acute normobaric hypoxia in healthy humans. Physiol Rep 2021; 9:e14932. [PMID: 34337893 PMCID: PMC8327160 DOI: 10.14814/phy2.14932] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2020] [Revised: 05/24/2021] [Accepted: 05/25/2021] [Indexed: 11/24/2022] Open
Abstract
Normal blood [glucose] regulation is critical to support metabolism, particularly in contexts of metabolic stressors (e.g., exercise, high altitude hypoxia). Data regarding blood [glucose] regulation in hypoxia are inconclusive. We aimed to characterize blood [glucose] over 80 min following glucose ingestion during both normoxia and acute normobaric hypoxia. In a randomized cross-over design, on two separate days, 28 healthy participants (16 females; 21.8 ± 1.6 years; BMI 22.8 ± 2.5 kg/m2 ) were randomly exposed to either NX (room air; fraction of inspired [FI ]O2 ~0.21) or HX (FI O2 ~0.148) in a normobaric hypoxia chamber. Measured FI O2 and peripheral oxygen saturation were both lower at baseline in hypoxia (p < 0.001), which was maintained over 80 min, confirming the hypoxic intervention. Following a 10-min baseline (BL) under both conditions, participants consumed a standardized glucose beverage (75 g, 296 ml) and blood [glucose] and physiological variables were measured at BL intermittently over 80 min. Blood [glucose] was measured from finger capillary samples via glucometer. Initial fasted blood [glucose] was not different between trials (NX:4.8 ± 0.4 vs. HX:4.9 ± 0.4 mmol/L; p = 0.47). Blood [glucose] was sampled every 10 min (absolute, delta, and percent change) following glucose ingestion over 80 min, and was not different between conditions (p > 0.77). In addition, mean, peak, and time-to-peak responses during the 80 min were not different between conditions (p > 0.14). There were also no sex differences in these blood [glucose] responses in hypoxia. We conclude that glucose regulation is unchanged in young, healthy participants with exposure to acute steady-state normobaric hypoxia, likely due to counterbalancing mechanisms underlying blood [glucose] regulation in hypoxia.
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Affiliation(s)
- Jason S. Chan
- Department of BiologyFaculty of Science and TechnologyMount Royal UniversityCalgaryABCanada
| | - Alexandra E. Chiew
- Department of BiologyFaculty of Science and TechnologyMount Royal UniversityCalgaryABCanada
| | - Alexander N. Rimke
- Department of BiologyFaculty of Science and TechnologyMount Royal UniversityCalgaryABCanada
| | - Garrick Chan
- Department of BiologyFaculty of Science and TechnologyMount Royal UniversityCalgaryABCanada
| | - Zahrah H. Rampuri
- Department of BiologyFaculty of Science and TechnologyMount Royal UniversityCalgaryABCanada
| | - Mackenzie D. Kozak
- Department of BiologyFaculty of Science and TechnologyMount Royal UniversityCalgaryABCanada
| | - Normand G. Boulé
- Alberta Diabetes InstituteFaculty of Kinesiology, Sport, and RecreationUniversity of AlbertaEdmontonABCanada
| | - Craig D. Steinback
- Alberta Diabetes InstituteFaculty of Kinesiology, Sport, and RecreationUniversity of AlbertaEdmontonABCanada
| | - Margie H. Davenport
- Alberta Diabetes InstituteFaculty of Kinesiology, Sport, and RecreationUniversity of AlbertaEdmontonABCanada
| | - Trevor A. Day
- Department of BiologyFaculty of Science and TechnologyMount Royal UniversityCalgaryABCanada
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Corrado PA, Barton GP, Razalan-Krause FC, François CJ, Chesler NC, Wieben O, Eldridge M, McMillan AB, Goss KN. Dynamic FDG PET Imaging to Probe for Cardiac Metabolic Remodeling in Adults Born Premature. J Clin Med 2021; 10:1301. [PMID: 33809883 PMCID: PMC8004130 DOI: 10.3390/jcm10061301] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2021] [Revised: 03/17/2021] [Accepted: 03/19/2021] [Indexed: 11/20/2022] Open
Abstract
Individuals born very premature have an increased cardiometabolic and heart failure risk. While the structural differences of the preterm heart are now well-described, metabolic insights into the physiologic mechanisms underpinning this risk are needed. Here, we used dynamic fluorodeoxyglucose (FDG) positron emission tomography/magnetic resonance imaging (PET-MRI) in young adults born term and preterm during normoxic (N = 28 preterm; 18 term) and hypoxic exposure (12% O2; N = 26 preterm; 17 term) to measure the myocardial metabolic rate of glucose (MMRglc) in young adults born term (N = 18) and preterm (N = 32), hypothesizing that young adults born preterm would have higher rates of MMRglc under normoxic conditions and a reduced ability to augment glucose metabolism under hypoxic conditions. MMRglc was calculated from the myocardial and blood pool time-activity curves by fitting the measured activities to the 3-compartment model of FDG kinetics. MMRglc was similar at rest between term and preterm subjects, and decreased during hypoxia exposure in both groups (p = 0.02 for MMRglc hypoxia effect). There were no differences observed between groups in the metabolic response to hypoxia, either globally (serum glucose and lactate measures) or within the myocardium. Thus, we did not find evidence of altered myocardial metabolism in the otherwise healthy preterm-born adult. However, whether subtle changes in myocardial metabolism may preceed or predict heart failure in this population remains to be determined.
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Affiliation(s)
- Philip A. Corrado
- Department of Medical Physics, University of Wisconsin-Madison, Madison, WI 53705, USA; (P.A.C.); (G.P.B.); (O.W.); (A.B.M.)
| | - Gregory P. Barton
- Department of Medical Physics, University of Wisconsin-Madison, Madison, WI 53705, USA; (P.A.C.); (G.P.B.); (O.W.); (A.B.M.)
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
- Department of Pediatrics, University of Wisconsin-Madison, Madison, WI 53705, USA;
| | | | | | - Naomi C. Chesler
- Edwards Lifesciences Center for Advanced Cardiovascular Technology, University of California, Irvine, CA 92697, USA;
- Department of Biomedical Engineering, University of California, Irvine, CA 92697, USA
| | - Oliver Wieben
- Department of Medical Physics, University of Wisconsin-Madison, Madison, WI 53705, USA; (P.A.C.); (G.P.B.); (O.W.); (A.B.M.)
- Department of Radiology, University of Wisconsin-Madison, Madison, WI 53705, USA;
| | - Marlowe Eldridge
- Department of Pediatrics, University of Wisconsin-Madison, Madison, WI 53705, USA;
- Department of Medicine, University of Wisconsin-Madison, Madison, WI 53705, USA;
| | - Alan B. McMillan
- Department of Medical Physics, University of Wisconsin-Madison, Madison, WI 53705, USA; (P.A.C.); (G.P.B.); (O.W.); (A.B.M.)
- Department of Radiology, University of Wisconsin-Madison, Madison, WI 53705, USA;
| | - Kara N. Goss
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
- Department of Pediatrics, University of Wisconsin-Madison, Madison, WI 53705, USA;
- Department of Medicine, University of Wisconsin-Madison, Madison, WI 53705, USA;
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Feng S, Ma J, Long K, Zhang J, Qiu W, Li Y, Jin L, Wang X, Jiang A, Liu L, Xiao W, Li X, Tang Q, Li M. Comparative microRNA Transcriptomes in Domestic Goats Reveal Acclimatization to High Altitude. Front Genet 2020; 11:809. [PMID: 32849809 PMCID: PMC7411263 DOI: 10.3389/fgene.2020.00809] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2020] [Accepted: 07/06/2020] [Indexed: 01/30/2023] Open
Abstract
High-altitude acclimatization is a representative example of vertebrates' acclimatization to harsh and extreme environments. Previous studies reported sufficient evidence for a molecular genetic basis of high-altitude acclimatization, and genomic patterns of genetic variation among populations and species have been widely elucidated in recent years. However, understanding of the miRNA role in high-altitude acclimatization have lagged behind, especially in non-model species. To investigate miRNA expression alterations of goats that were induced by high-altitude stress, we performed comparative miRNA transcriptome analysis on six hypoxia-sensitive tissues (heart, kidney, liver, lung, skeletal muscle, and spleen) in two goat populations from distinct altitudes (600 and 3000 m). We obtained the expression value of 1391 mature miRNAs and identified 138 differentially expressed (DE) miRNAs between high and low altitudes. Combined with tissue specificity analysis, we illustrated alterations of expression levels among altitudes and tissues, and found that there were coexisting tissue-specific and -conserved mechanisms for hypoxia acclimatization. Notably, the interplay between DE miRNA and DE target genes strongly indicated post-transcriptional regulation in the hypoxia inducible factor 1, insulin, and p53 signaling pathways, which might play significant roles in high-altitude acclimatization in domestic goats. It's also worth noting that we experimentally confirmed miR-106a-5p to have a negative regulation effect on angiogenesis by directly targeting FLT-1. These results provide insight into the complicated miRNA expression patterns and regulatory mechanisms of high-altitude acclimatization in domestic goats.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | | | | | | | - Qianzi Tang
- Institute of Animal Genetics and Breeding, College of Animal Science and Technology, Sichuan Agricultural University, Chengdu, China
| | - Mingzhou Li
- Institute of Animal Genetics and Breeding, College of Animal Science and Technology, Sichuan Agricultural University, Chengdu, China
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6
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Ferrero KM, Koch WJ. Metabolic Crosstalk between the Heart and Fat. Korean Circ J 2020; 50:379-394. [PMID: 32096362 PMCID: PMC7098822 DOI: 10.4070/kcj.2019.0400] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Accepted: 12/27/2019] [Indexed: 12/14/2022] Open
Abstract
It is now recognized that the heart can behave as a true endocrine organ, which can modulate the function of other tissues. Emerging evidence has shown that visceral fat is one such distant organ the heart communicates with. In fact, it appears that bi-directional crosstalk between adipose tissue and the myocardium is crucial to maintenance of normal function in both organs. In particular, factors secreted from the heart are now known to influence the metabolic activity of adipose tissue and other organs, as well as modulate the release of metabolic substrates and signaling molecules from the periphery. This review summarizes current knowledge regarding primary cardiokines and adipokines involved in heart-fat crosstalk, as well as implications of their dysregulation for cardiovascular health.
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Affiliation(s)
- Kimberly M Ferrero
- Center for Translational Medicine, Department of Pharmacology, Lewis Katz School of Medicine, Temple University, Philadelphia, PA, USA
| | - Walter J Koch
- Center for Translational Medicine, Department of Pharmacology, Lewis Katz School of Medicine, Temple University, Philadelphia, PA, USA.
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Barton GP, Vildberg L, Goss K, Aggarwal N, Eldridge M, McMillan AB. Simultaneous determination of dynamic cardiac metabolism and function using PET/MRI. J Nucl Cardiol 2019; 26:1946-1957. [PMID: 29717407 PMCID: PMC7851880 DOI: 10.1007/s12350-018-1287-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2017] [Accepted: 04/13/2018] [Indexed: 11/29/2022]
Abstract
BACKGROUND Cardiac metabolic changes in heart disease precede overt contractile dysfunction. However, metabolism and function are not typically assessed together in clinical practice. The purpose of this study was to develop a cardiac positron emission tomography/magnetic resonance (PET/MR) stress test to assess the dynamic relationship between contractile function and metabolism in a preclinical model. METHODS Following an overnight fast, healthy pigs (45-50 kg) were anesthetized and mechanically ventilated. 18F-fluorodeoxyglucose (18F-FDG) solution was administered intravenously at a constant rate of 0.01 mL/s for 60 minutes. A cardiac PET/MR stress test was performed using normoxic gas (FIO2 = .209) and hypoxic gas (FIO2 = .12). Simultaneous cardiac imaging was performed on an integrated 3T PET/MR scanner. RESULTS Hypoxic stress induced a significant increase in heart rate, cardiac output, left ventricular (LV) ejection fraction (EF), and peak torsion. There was a significant decline in arterial SpO2, LV end-diastolic and end-systolic volumes in hypoxia. Increased LV systolic function was coupled with an increase in myocardial FDG uptake (Ki) during hypoxic stress. CONCLUSION PET/MR with continuous FDG infusion captures dynamic changes in both cardiac metabolism and contractile function. This technique warrants evaluation in human cardiac disease for assessment of subtle functional and metabolic abnormalities.
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Affiliation(s)
- Gregory P Barton
- Department of Pediatrics, UW School of Medicine and Public Health, University of Wisconsin-Madison, 600 Highland Ave. H6/551 CSC, Madison, WI, 53792, USA.
- Rankin Laboratory of Pulmonary Medicine, University of Wisconsin-Madison, Madison, USA.
| | - Lauren Vildberg
- Department of Pediatrics, UW School of Medicine and Public Health, University of Wisconsin-Madison, 600 Highland Ave. H6/551 CSC, Madison, WI, 53792, USA
- Rankin Laboratory of Pulmonary Medicine, University of Wisconsin-Madison, Madison, USA
| | - Kara Goss
- Department of Pediatrics, UW School of Medicine and Public Health, University of Wisconsin-Madison, 600 Highland Ave. H6/551 CSC, Madison, WI, 53792, USA
- Department of Medicine, University of Wisconsin-Madison, Madison, USA
- Rankin Laboratory of Pulmonary Medicine, University of Wisconsin-Madison, Madison, USA
| | - Niti Aggarwal
- Division of Cardiovascular Disease Department of Medicine, University of Wisconsin-Madison, Madison, USA
- Department of Radiology, University of Wisconsin-Madison, Madison, USA
| | - Marlowe Eldridge
- Department of Pediatrics, UW School of Medicine and Public Health, University of Wisconsin-Madison, 600 Highland Ave. H6/551 CSC, Madison, WI, 53792, USA
- Department of Biomedical Engineering, University of Wisconsin-Madison, Madison, USA
- Rankin Laboratory of Pulmonary Medicine, University of Wisconsin-Madison, Madison, USA
| | - Alan B McMillan
- Department of Radiology, University of Wisconsin-Madison, Madison, USA
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Tumor necrosis factor inhibition increases the revascularization of ischemic hind-limbs in diabetic mice. Naunyn Schmiedebergs Arch Pharmacol 2015; 388:1053-60. [DOI: 10.1007/s00210-015-1138-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2015] [Accepted: 05/21/2015] [Indexed: 02/08/2023]
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9
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Successive exposure to moderate hypoxia does not affect glucose metabolism and substrate oxidation in young healthy men. SPRINGERPLUS 2014; 3:370. [PMID: 25089253 PMCID: PMC4117865 DOI: 10.1186/2193-1801-3-370] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/29/2014] [Accepted: 07/03/2014] [Indexed: 12/03/2022]
Abstract
Introduction Exposure to hypoxia has been suggested to acutely alter glucose regulation. However, the effects of successive exposure to moderate hypoxia on postprandial glucose regulation and substrate oxidation pattern after multiple meals have not been elucidated. Purpose We examined the effects of successive exposure to moderate hypoxia on metabolic responses and substrate oxidation pattern. Methods Eight healthy men (21.0 ± 0.6 yrs, 173 ± 2.3 cm, 70.6 ± 5.0 kg, 23.4 ± 1.1 kg/m2) completed two experimental trials on separate days: a rest trial under normoxic conditions (FiO2 = 20.9%) and a rest trial under hypoxic conditions (FiO2 = 15.0%). Experimental trials were performed over 7 h in an environmental chamber. Blood and respiratory gas samples were collected over 7 h. Standard meals were provided 1 h (745 kcal) and 4 h (731 kcal) after entering the chamber. Results Although each meal significantly increased blood glucose and serum insulin concentrations (P < 0.05), these responses did not differ significantly between the trials. There were no significant differences in areas under the curves for glucose or insulin concentrations over 7 h between the trials. No significant differences were observed in blood lactate, serum cortisol, free fatty acid, or glycerol concentrations over 7 h between the trials. The oxygen consumption (
) and carbon dioxide production (
) 3 h after entering the chamber were significantly higher in the hypoxic trial than in the normoxic trial (P < 0.05). However, the differences did not affect respiratory exchange ratio (RER). The average values of
,
, and RER did not differ between the trials. Conclusion Seven hours of moderate hypoxia did not alter postprandial glucose responses or substrate oxidation in young healthy men.
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Breckenridge RA, Piotrowska I, Ng KE, Ragan TJ, West JA, Kotecha S, Towers N, Bennett M, Kienesberger PC, Smolenski RT, Siddall HK, Offer JL, Mocanu MM, Yelon DM, Dyck JRB, Griffin JL, Abramov AY, Gould AP, Mohun TJ. Hypoxic regulation of hand1 controls the fetal-neonatal switch in cardiac metabolism. PLoS Biol 2013; 11:e1001666. [PMID: 24086110 PMCID: PMC3782421 DOI: 10.1371/journal.pbio.1001666] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2013] [Accepted: 08/15/2013] [Indexed: 12/15/2022] Open
Abstract
This study reveals a novel pathway that responds to hypoxia and modulates energy metabolism by cardiomyocytes in the mouse heart, thereby determining oxygen consumption. Cardiomyocytes are vulnerable to hypoxia in the adult, but adapted to hypoxia in utero. Current understanding of endogenous cardiac oxygen sensing pathways is limited. Myocardial oxygen consumption is determined by regulation of energy metabolism, which shifts from glycolysis to lipid oxidation soon after birth, and is reversed in failing adult hearts, accompanying re-expression of several “fetal” genes whose role in disease phenotypes remains unknown. Here we show that hypoxia-controlled expression of the transcription factor Hand1 determines oxygen consumption by inhibition of lipid metabolism in the fetal and adult cardiomyocyte, leading to downregulation of mitochondrial energy generation. Hand1 is under direct transcriptional control by HIF1α. Transgenic mice prolonging cardiac Hand1 expression die immediately following birth, failing to activate the neonatal lipid metabolising gene expression programme. Deletion of Hand1 in embryonic cardiomyocytes results in premature expression of these genes. Using metabolic flux analysis, we show that Hand1 expression controls cardiomyocyte oxygen consumption by direct transcriptional repression of lipid metabolising genes. This leads, in turn, to increased production of lactate from glucose, decreased lipid oxidation, reduced inner mitochondrial membrane potential, and mitochondrial ATP generation. We found that this pathway is active in adult cardiomyocytes. Up-regulation of Hand1 is protective in a mouse model of myocardial ischaemia. We propose that Hand1 is part of a novel regulatory pathway linking cardiac oxygen levels with oxygen consumption. Understanding hypoxia adaptation in the fetal heart may allow development of strategies to protect cardiomyocytes vulnerable to ischaemia, for example during cardiac ischaemia or surgery. Regulation of oxygen usage in cardiomyocytes is of great medical interest, because adult cardiac tissue is extremely vulnerable to hypoxia during myocardial infarction and cardiac surgery. While some progress has been made toward protecting cardiomyocytes from hypoxia in these circumstances, it has been limited by a lack of understanding of endogenous oxygen-sensing pathways. In contrast to adult cardiac tissue, embryonic cardiomyocytes are highly resistant to hypoxia, although the mechanisms underlying this have hitherto been unclear. Using mice we show that the transcription factor Hand1 is expressed at high levels in the fetal heart, under direct control of HIF1α signaling, a pathway well known to respond to hypoxia. We show that Hand1 expression decreases at birth as the neonate is exposed to higher levels of oxygen. By experimentally increasing Hand1 expression in the neonatal heart, we see lower oxygen consumption in cardiomyocytes and this is caused by Hand1 repressing key regulatory genes involved in cardiomyocyte lipid metabolism. This has the effect of decreasing mitochondrial ATP generation via the tricarboxylic acid cycle. Furthermore, we show that increasing Hand1 expression in adult transgenic hearts is protective against myocardial infarction, suggesting that a hypoxia–Hand1 pathway may also be of importance in the adult heart.
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Affiliation(s)
- Ross A. Breckenridge
- Developmental Biology, MRC–National Institute for Medical Research, London, United Kingdom
- Division of Medicine, University College London, London, United Kingdom
- * E-mail:
| | - Izabela Piotrowska
- Developmental Biology, MRC–National Institute for Medical Research, London, United Kingdom
| | - Keat-Eng Ng
- Developmental Biology, MRC–National Institute for Medical Research, London, United Kingdom
| | - Timothy J. Ragan
- Division of Molecular Structure, MRC–National Institute for Medical Research, London, United Kingdom
| | - James A. West
- Department of Biochemistry, Cambridge University, Cambridge, United Kingdom
| | - Surendra Kotecha
- Developmental Biology, MRC–National Institute for Medical Research, London, United Kingdom
| | - Norma Towers
- Developmental Biology, MRC–National Institute for Medical Research, London, United Kingdom
| | - Michael Bennett
- Developmental Biology, MRC–National Institute for Medical Research, London, United Kingdom
| | - Petra C. Kienesberger
- Cardiovascular Research Centre, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
| | | | - Hillary K. Siddall
- Hatter Institute, Institute of Cardiovascular Sciences, University College London, London, United Kingdom
| | - John L. Offer
- Physical Biochemistry, MRC–National Institute for Medical Research, London, United Kingdom
| | - Mihaela M. Mocanu
- Hatter Institute, Institute of Cardiovascular Sciences, University College London, London, United Kingdom
| | - Derek M. Yelon
- Hatter Institute, Institute of Cardiovascular Sciences, University College London, London, United Kingdom
| | - Jason R. B. Dyck
- Cardiovascular Research Centre, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
| | - Jules L. Griffin
- Department of Biochemistry, Cambridge University, Cambridge, United Kingdom
| | - Andrey Y. Abramov
- Institute of Neurology, University College London, London, United Kingdom
| | - Alex P. Gould
- Division of Physiology and Metabolism, MRC–National Institute for Medical Research, London, United Kingdom
| | - Timothy J. Mohun
- Developmental Biology, MRC–National Institute for Medical Research, London, United Kingdom
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Kolamunne RT, Dias IHK, Vernallis AB, Grant MM, Griffiths HR. Nrf2 activation supports cell survival during hypoxia and hypoxia/reoxygenation in cardiomyoblasts; the roles of reactive oxygen and nitrogen species. Redox Biol 2013; 1:418-26. [PMID: 24191235 PMCID: PMC3814985 DOI: 10.1016/j.redox.2013.08.002] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2013] [Revised: 08/07/2013] [Accepted: 08/09/2013] [Indexed: 02/06/2023] Open
Abstract
Adaptive mechanisms involving upregulation of cytoprotective genes under the control of transcription factors such as Nrf2 exist to protect cells from permanent damage and dysfunction under stress conditions. Here we explore of the hypothesis that Nrf2 activation by reactive oxygen and nitrogen species modulates cytotoxicity during hypoxia (H) with and without reoxygenation (H/R) in H9C2 cardiomyoblasts. Using MnTBap as a cell permeable superoxide dismutase (SOD) mimetic and peroxynitrite scavenger and L-NAME as an inhibitor of nitric oxide synthase (NOS), we have shown that MnTBap inhibited the cytotoxic effects of hypoxic stress with and without reoxygenation. However, L-NAME only afforded protection during H. Under reoxygenation, conditions, cytotoxicity was increased by the presence of L-NAME. Nrf2 activation was inhibited independently by MnTBap and L-NAME under H and H/R. The increased cytotoxicity and inhibition of Nrf2 activation by the presence of L-NAME during reoxygenation suggests that NOS activity plays an important role in cell survival at least in part via Nrf2-independent pathways. In contrast, O2−• scavenging by MnTBap prevented both toxicity and Nrf2 activation during H and H/R implying that toxicity is largely dependent on O2−•.To confirm the importance of Nrf2 for myoblast metabolism, Nrf2 knockdown with siRNA reduced cell survival by 50% during 4 h hypoxia with and without 2 h of reoxygenation and although cellular glutathione (GSH) was depleted during H and H/R, GSH loss was not exacerbated by Nrf2 knockdown. These data support distinctive roles for ROS and RNS during H and H/R for Nrf2 induction which are important for survival independently of GSH salvage. Cardiomyoblast toxicity during hypoxia is dependent on O2−• and NO•. Nrf2 activation is important for cardiomyoblast survival during hypoxia or hypoxia/reoxygenation, but, restoration of GSH is not required. NOS activity is essential for the adaptation of cardiomyoblasts to hypoxia/reoxygenation but survival may be independent of Nrf2.
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Key Words
- Adaptive
- CREB, cAMP-responsive element-binding protein
- DAF-2-DA, 4,5-diaminofluorescein diacetate
- DHE, dihydroethidium
- Glutathione
- HIF-1, hypoxia-inducible factor
- KEAP1, Kelch-like ECH-associated protein 1
- L-NAME
- L-NAME, L-NG-nitroarginine methyl ester
- MnTBap
- MnTBap, manganese [III] tetrakis (4-benzoic acid) porphyrin
- NFκB, nuclear factor kappa B
- NO, nitric oxide
- NOS, nitric oxide synthase
- NOX, NADPH oxidase
- Nrf2, nuclear factor erythroid 2-related factor 2
- RNS
- RNS, reactive nitrogen species
- ROS
- ROS, reactive oxygen species
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Affiliation(s)
- Rajitha T Kolamunne
- Life and Health Sciences, Aston University, Birmingham, B4 7ET, UK ; Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK
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Hantson P, Beauloye C. Myocardial metabolism in toxin-induced heart failure and therapeutic implications. Clin Toxicol (Phila) 2012; 50:166-71. [DOI: 10.3109/15563650.2012.658472] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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13
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Heinonen I, Kemppainen J, Kaskinoro K, Peltonen JE, Sipilä HT, Nuutila P, Knuuti J, Boushel R, Kalliokoski KK. Effects of adenosine, exercise, and moderate acute hypoxia on energy substrate utilization of human skeletal muscle. Am J Physiol Regul Integr Comp Physiol 2011; 302:R385-90. [PMID: 22129615 DOI: 10.1152/ajpregu.00245.2011] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Glucose metabolism increases in hypoxia and can be influenced by endogenous adenosine, but the role of adenosine for regulating glucose metabolism at rest or during exercise in hypoxia has not been elucidated in humans. We studied the effects of exogenous adenosine on human skeletal muscle glucose uptake and other blood energy substrates [free fatty acid (FFA) and lactate] by infusing adenosine into the femoral artery in nine healthy young men. The role of endogenous adenosine was studied by intra-arterial adenosine receptor inhibition (aminophylline) during dynamic one-leg knee extension exercise in normoxia and acute hypoxia corresponding to ∼3,400 m of altitude. Extraction and release of energy substrates were studied by arterial-to-venous (A-V) blood samples, and total uptake or release was determined by the product of A-V differences and muscle nutritive perfusion measured by positron emission tomography. The results showed that glucose uptake increased from a baseline value of 0.2 ± 0.2 to 2.0 ± 2.2 μmol·100 g(-1)·min(-1) during adenosine infusion (P < 0.05) at rest. Although acute hypoxia enhanced arterial FFA levels, it did not affect muscle substrate utilization at rest. During exercise, glucose uptake was higher (195%) during acute hypoxia compared with normoxia (P = 0.058), and aminophylline had no effect on energy substrate utilization during exercise, despite that arterial FFA levels were increased. In conclusion, exogenous adenosine at rest and acute moderate hypoxia during low-intensity knee-extension exercise increases skeletal muscle glucose uptake, but the increase in hypoxia appears not to be mediated by adenosine.
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14
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Komniski MS, Yakushev S, Bogdanov N, Gassmann M, Bogdanova A. Interventricular heterogeneity in rat heart responses to hypoxia: the tuning of glucose metabolism, ion gradients, and function. Am J Physiol Heart Circ Physiol 2011; 300:H1645-52. [PMID: 21398597 DOI: 10.1152/ajpheart.00220.2010] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The matching of energy supply and demand under hypoxic conditions is critical for sustaining myocardial function. Numerous reports indicate that basal energy requirements and ion handling may differ between the ventricles. We hypothesized that ventricular response to hypoxia shows interventricular differences caused by the heterogeneity in glucose metabolism and expression and activity of ion transporters. Thus we assessed glucose utilization rate, ATP, sodium and potassium concentrations, Na, K-ATPase activity, and tissue reduced:oxidized glutathione (GSH/GSSG) content in the right and left ventricles before and after the exposure of either the whole animals or isolated blood-perfused hearts to hypoxia. The hypoxia-induced boost in glucose utilization was more pronounced in the left ventricle compared with the right one. ATP levels in the right ventricle of hypoxic heart were lower than those in the left ventricle. Left ventricular sodium content was higher, and hydrolytic Na, K-ATPase activity was reduced compared with the right ventricle. Administration of the Na, K-ATPase blocker ouabain caused rapid increase in the right ventricular Na(+) and elimination of the interventricular Na(+) gradients. Exposure of the hearts to hypoxia made the interventricular heterogeneity in the Na(+) distribution even more pronounced. Furthermore, systemic hypoxia caused oxidative stress that was more pronounced in the right ventricle as revealed by GSH/GSSG ratios. On the basis of these findings, we suggest that the right ventricle is more prone to hypoxic damage, as it is less efficient in recruiting glucose as an alternative fuel and is particularly dependent on the efficient Na, K-ATPase function.
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Affiliation(s)
- Milena Segato Komniski
- Institute of Veterinary Physiology, Univ. of Zurich, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland
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Chen MT, Lee WC, Chen SC, Chen CC, Chen CY, Lee SD, Jensen J, Kuo CH. Effect of a prolonged altitude expedition on glucose tolerance and abdominal fatness. RESEARCH QUARTERLY FOR EXERCISE AND SPORT 2010; 81:472-477. [PMID: 21268471 DOI: 10.1080/02701367.2010.10599708] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
In the present study, we investigated the effect of a long-term mountain expedition on glucose tolerance and insulin action. Twelve registered mountaineers ages 31 years (SD = 1.1) participated in a 25-day expedition at a 2,200-3,800-m altitude with an average duration of 8 hr per day. Arterial oxygen saturation (SaO2) was substantially reduced during hiking. Glucose tolerance and insulin responses were measured prior to and twice during the expedition period. Maximal oxygen consumption increased from 43.0 +/- 2.7 to 49.1 +/- 2.2 mL/kg/min. Percentage of body fat decreased from 19.4 +/- 6.8% to 16.9 +/- 5.9%. The area under the curves for insulin and glucose during the oral glucose tolerance test were also reduced in Days 3 and 25. The present study demonstrated that altitude hiking activity is an effective lifestyle intervention to improve insulin action.
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Affiliation(s)
- Mu-Tsung Chen
- School of Liberal Education at Shih Chien University, Taiwan
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Kolamunne RT, Clare M, Griffiths HR. Mitochondrial superoxide anion radicals mediate induction of apoptosis in cardiac myoblasts exposed to chronic hypoxia. Arch Biochem Biophys 2010; 505:256-65. [PMID: 20971059 DOI: 10.1016/j.abb.2010.10.015] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2010] [Revised: 09/27/2010] [Accepted: 10/17/2010] [Indexed: 11/16/2022]
Abstract
Both reactive oxygen species (ROS) and ATP depletion may be significant in hypoxia-induced damage and death, either collectively or independently, with high energy requiring, metabolically active cells being the most susceptible to damage. We investigated the kinetics and effects of ROS production in cardiac myoblasts, H9C2 cells, under 2%, 10% and 21% O₂ in the presence or absence of apocynin, rotenone and carbonyl cyanide p-(trifluoromethoxy) phenylhydrazone. H9C2 cells showed significant loss of viability within 30 min of culture at 2% oxygen which was not due to apoptosis, but was associated with an increase in protein oxidation. However, after 4 h, apoptosis induction was observed at 2% oxygen and also to a lesser extent at 10% oxygen; this was dependent on the levels of mitochondrial superoxide anion radicals determined using dihydroethidine. Hypoxia-induced ROS production and cell death could be rescued by the mitochondrial complex I inhibitor, rotenone, despite further depletion of ATP. In conclusion, a change to superoxide anion radical steady state level was not detectable after 30 min but was evident after 4 h of mild or severe hypoxia. Superoxide anion radicals from the mitochondrion and not ATP depletion is the major cause of apoptotic cell death in cardiac myoblasts under chronic, severe hypoxia.
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