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Caldwell HG, Hoiland RL, Bain AR, Howe CA, Carr JMJR, Gibbons TD, Durrer CG, Tymko MM, Stacey BS, Bailey DM, Sekhon MS, MacLeod DB, Ainslie PN. Evidence for direct CO 2-mediated alterations in cerebral oxidative metabolism in humans. Acta Physiol (Oxf) 2024:e14197. [PMID: 38958262 DOI: 10.1111/apha.14197] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2023] [Revised: 06/18/2024] [Accepted: 06/20/2024] [Indexed: 07/04/2024]
Abstract
AIM How the cerebral metabolic rates of oxygen and glucose utilization (CMRO2 and CMRGlc, respectively) are affected by alterations in arterial PCO2 (PaCO2) is equivocal and therefore was the primary question of this study. METHODS This retrospective analysis involved pooled data from four separate studies, involving 41 healthy adults (35 males/6 females). Participants completed stepwise steady-state alterations in PaCO2 ranging between 30 and 60 mmHg. The CMRO2 and CMRGlc were assessed via the Fick approach (CBF × arterial-internal jugular venous difference of oxygen or glucose content, respectively) utilizing duplex ultrasound of the internal carotid artery and vertebral artery to calculate cerebral blood flow (CBF). RESULTS The CMRO2 was altered by 0.5 mL × min-1 (95% CI: -0.6 to -0.3) per mmHg change in PaCO2 (p < 0.001) which corresponded to a 9.8% (95% CI: -13.2 to -6.5) change in CMRO2 with a 9 mmHg change in PaCO2 (inclusive of hypo- and hypercapnia). The CMRGlc was reduced by 7.7% (95% CI: -15.4 to -0.08, p = 0.045; i.e., reduction in net glucose uptake) and the oxidative glucose index (ratio of oxygen to glucose uptake) was reduced by 5.6% (95% CI: -11.2 to 0.06, p = 0.049) with a + 9 mmHg increase in PaCO2. CONCLUSION Collectively, the CMRO2 is altered by approximately 1% per mmHg change in PaCO2. Further, glucose is incompletely oxidized during hypercapnia, indicating reductions in CMRO2 are either met by compensatory increases in nonoxidative glucose metabolism or explained by a reduction in total energy production.
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Affiliation(s)
- Hannah G Caldwell
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia Okanagan, Kelowna, British Columbia, Canada
| | - Ryan L Hoiland
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia Okanagan, Kelowna, British Columbia, Canada
- Department of Anesthesiology, Pharmacology and Therapeutics, Vancouver General Hospital, University of British Columbia, Vancouver, British Columbia, Canada
- Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, British Columbia, Canada
- International Collaboration on Repair Discoveries, University of British Columbia, Vancouver, British Columbia, Canada
- Collaborative Entity for REsearching Brain Ischemia (CEREBRI), University of British Columbia, Vancouver, British Columbia, Canada
| | - Anthony R Bain
- Department of Kinesiology, Faculty of Human Kinetics, University of Windsor, Windsor, Ontario, Canada
| | - Connor A Howe
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia Okanagan, Kelowna, British Columbia, Canada
| | - Jay M J R Carr
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia Okanagan, Kelowna, British Columbia, Canada
| | - Travis D Gibbons
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia Okanagan, Kelowna, British Columbia, Canada
| | - Cody G Durrer
- Centre for Physical Activity Research, Rigshospitalet, Copenhagen, Denmark
| | - Michael M Tymko
- Division of Critical Care Medicine, Department of Medicine, Faculty of Medicine, Vancouver General Hospital, University of British Columbia, Vancouver, British Columbia, Canada
- Human Cerebrovascular Physiology Laboratory, Department of Human Health and Nutritional Sciences, College of Biological Science, University of Guelph, Guelph, Ontario, Canada
| | - Benjamin S Stacey
- Neurovascular Research Laboratory, Faculty of Life Sciences and Education, University of South Wales, Pontypridd, UK
| | - Damian M Bailey
- Neurovascular Research Laboratory, Faculty of Life Sciences and Education, University of South Wales, Pontypridd, UK
| | - Mypinder S Sekhon
- International Collaboration on Repair Discoveries, University of British Columbia, Vancouver, British Columbia, Canada
- Collaborative Entity for REsearching Brain Ischemia (CEREBRI), University of British Columbia, Vancouver, British Columbia, Canada
- Division of Critical Care Medicine, Department of Medicine, Faculty of Medicine, Vancouver General Hospital, University of British Columbia, Vancouver, British Columbia, Canada
- Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, British Columbia, Canada
| | - David B MacLeod
- Human Pharmacology and Physiology Lab, Department of Anesthesiology, Duke University Medical Center, Durham, North Carolina, USA
| | - Philip N Ainslie
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia Okanagan, Kelowna, British Columbia, Canada
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2
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Theriault JE, Shaffer C, Dienel GA, Sander CY, Hooker JM, Dickerson BC, Barrett LF, Quigley KS. A functional account of stimulation-based aerobic glycolysis and its role in interpreting BOLD signal intensity increases in neuroimaging experiments. Neurosci Biobehav Rev 2023; 153:105373. [PMID: 37634556 PMCID: PMC10591873 DOI: 10.1016/j.neubiorev.2023.105373] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2023] [Revised: 07/28/2023] [Accepted: 08/23/2023] [Indexed: 08/29/2023]
Abstract
In aerobic glycolysis, oxygen is abundant, and yet cells metabolize glucose without using it, decreasing their ATP per glucose yield by 15-fold. During task-based stimulation, aerobic glycolysis occurs in localized brain regions, presenting a puzzle: why produce ATP inefficiently when, all else being equal, evolution should favor the efficient use of metabolic resources? The answer is that all else is not equal. We propose that a tradeoff exists between efficient ATP production and the efficiency with which ATP is spent to transmit information. Aerobic glycolysis, despite yielding little ATP per glucose, may support neuronal signaling in thin (< 0.5 µm), information-efficient axons. We call this the efficiency tradeoff hypothesis. This tradeoff has potential implications for interpretations of task-related BOLD "activation" observed in fMRI. We hypothesize that BOLD "activation" may index local increases in aerobic glycolysis, which support signaling in thin axons carrying "bottom-up" information, or "prediction error"-i.e., the BIAPEM (BOLD increases approximate prediction error metabolism) hypothesis. Finally, we explore implications of our hypotheses for human brain evolution, social behavior, and mental disorders.
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Affiliation(s)
- Jordan E Theriault
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA, USA; Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA, USA.
| | - Clare Shaffer
- Northeastern University, Department of Psychology, Boston, MA, USA
| | - Gerald A Dienel
- Department of Neurology, University of Arkansas for Medical Sciences, Little Rock, AR, USA; Department of Cell Biology and Physiology, University of New Mexico, Albuquerque, NM, USA
| | - Christin Y Sander
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA, USA; Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA, USA
| | - Jacob M Hooker
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA, USA; Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA, USA
| | - Bradford C Dickerson
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA, USA; Department of Neurology, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA, USA; Department of Psychiatry, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA, USA
| | - Lisa Feldman Barrett
- Northeastern University, Department of Psychology, Boston, MA, USA; Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA, USA; Department of Psychiatry, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA, USA
| | - Karen S Quigley
- Northeastern University, Department of Psychology, Boston, MA, USA; VA Bedford Healthcare System, Bedford, MA, USA
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3
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Caldwell HG, Hoiland RL, Smith KJ, Brassard P, Bain AR, Tymko MM, Howe CA, Carr JM, Stacey BS, Bailey DM, Drapeau A, Sekhon MS, MacLeod DB, Ainslie PN. Trans-cerebral HCO 3- and PCO 2 exchange during acute respiratory acidosis and exercise-induced metabolic acidosis in humans. J Cereb Blood Flow Metab 2022; 42:559-571. [PMID: 34904461 PMCID: PMC8943603 DOI: 10.1177/0271678x211065924] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
This study investigated trans-cerebral internal jugular venous-arterial bicarbonate ([HCO3-]) and carbon dioxide tension (PCO2) exchange utilizing two separate interventions to induce acidosis: 1) acute respiratory acidosis via elevations in arterial PCO2 (PaCO2) (n = 39); and 2) metabolic acidosis via incremental cycling exercise to exhaustion (n = 24). During respiratory acidosis, arterial [HCO3-] increased by 0.15 ± 0.05 mmol ⋅ l-1 per mmHg elevation in PaCO2 across a wide physiological range (35 to 60 mmHg PaCO2; P < 0.001). The narrowing of the venous-arterial [HCO3-] and PCO2 differences with respiratory acidosis were both related to the hypercapnia-induced elevations in cerebral blood flow (CBF) (both P < 0.001; subset n = 27); thus, trans-cerebral [HCO3-] exchange (CBF × venous-arterial [HCO3-] difference) was reduced indicating a shift from net release toward net uptake of [HCO3-] (P = 0.004). Arterial [HCO3-] was reduced by -0.48 ± 0.15 mmol ⋅ l-1 per nmol ⋅ l-1 increase in arterial [H+] with exercise-induced acidosis (P < 0.001). There was no relationship between the venous-arterial [HCO3-] difference and arterial [H+] with exercise-induced acidosis or CBF; therefore, trans-cerebral [HCO3-] exchange was unaltered throughout exercise when indexed against arterial [H+] or pH (P = 0.933 and P = 0.896, respectively). These results indicate that increases and decreases in systemic [HCO3-] - during acute respiratory/exercise-induced metabolic acidosis, respectively - differentially affect cerebrovascular acid-base balance (via trans-cerebral [HCO3-] exchange).
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Affiliation(s)
- Hannah G Caldwell
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia Okanagan, Kelowna, BC, Canada
| | - Ryan L Hoiland
- Department of Anesthesiology, Pharmacology and Therapeutics, Vancouver General Hospital, University of British Columbia, Vancouver, BC, Canada.,Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, BC, Canada
| | - Kurt J Smith
- Department of Exercise Science, Physical and Health Education, Faculty of Education, University of Victoria, Victoria, British Columbia, Canada
| | - Patrice Brassard
- Department of Kinesiology, Faculty of Medicine, Université Laval, Québec, Canada.,Research Center of the Institut Universitaire de Cardiologie et de Pneumologie de Québec, QC, Canada
| | - Anthony R Bain
- Faculty of Human Kinetics, Department of Kinesiology, University of Windsor, Windsor, ON, Canada
| | - Michael M Tymko
- Neurovascular Health Laboratory, Faculty of Kinesiology, Sport and Recreation, University of Alberta, Edmonton, AB, Canada
| | - Connor A Howe
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia Okanagan, Kelowna, BC, Canada
| | - Jay Mjr Carr
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia Okanagan, Kelowna, BC, Canada
| | - Benjamin S Stacey
- Neurovascular Research Laboratory, Faculty of Life Sciences and Education, University of South Wales, Pontypridd, UK
| | - Damian M Bailey
- Neurovascular Research Laboratory, Faculty of Life Sciences and Education, University of South Wales, Pontypridd, UK
| | - Audrey Drapeau
- Department of Kinesiology, Faculty of Medicine, Université Laval, Québec, Canada.,Research Center of the Institut Universitaire de Cardiologie et de Pneumologie de Québec, QC, Canada
| | - Mypinder S Sekhon
- Division of Critical Care Medicine, Department of Medicine, 8167Vancouver General Hospital, Vancouver General Hospital, University of British Columbia, Vancouver, BC, Canada
| | - David B MacLeod
- Human Pharmacology and Physiology Lab, Department of Anesthesiology, Duke University Medical Center, Durham, NC, USA
| | - Philip N Ainslie
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia Okanagan, Kelowna, BC, Canada
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4
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Passarella S, Schurr A, Portincasa P. Mitochondrial Transport in Glycolysis and Gluconeogenesis: Achievements and Perspectives. Int J Mol Sci 2021; 22:ijms222312620. [PMID: 34884425 PMCID: PMC8657705 DOI: 10.3390/ijms222312620] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Revised: 11/16/2021] [Accepted: 11/19/2021] [Indexed: 01/22/2023] Open
Abstract
Some metabolic pathways involve two different cell components, for instance, cytosol and mitochondria, with metabolites traffic occurring from cytosol to mitochondria and vice versa, as seen in both glycolysis and gluconeogenesis. However, the knowledge on the role of mitochondrial transport within these two glucose metabolic pathways remains poorly understood, due to controversial information available in published literature. In what follows, we discuss achievements, knowledge gaps, and perspectives on the role of mitochondrial transport in glycolysis and gluconeogenesis. We firstly describe the experimental approaches for quick and easy investigation of mitochondrial transport, with respect to cell metabolic diversity. In addition, we depict the mitochondrial shuttles by which NADH formed in glycolysis is oxidized, the mitochondrial transport of phosphoenolpyruvate in the light of the occurrence of the mitochondrial pyruvate kinase, and the mitochondrial transport and metabolism of L-lactate due to the L-lactate translocators and to the mitochondrial L-lactate dehydrogenase located in the inner mitochondrial compartment.
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Affiliation(s)
- Salvatore Passarella
- Department of Biomedical Sciences and Human Oncology, University of Bari “Aldo Moro”, 70124 Bari, Italy
- Correspondence: ; Tel.: +39-3293606374
| | - Avital Schurr
- Department of Anesthesiology and Perioperative Medicine, School of Medicine, University of Louisville, Louisville, KY 40202, USA;
| | - Piero Portincasa
- Clinica Medica “A. Murri”, Department of Biomedical Sciences and Human Oncology, University of Bari “Aldo Moro”, 70124 Bari, Italy;
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5
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Siebenmann C, Sorensen H, Bonne TC, Zaar M, Aachmann-Andersen NJ, Nordsborg NB, Nielsen HB, Secher NH, Lundby C, Rasmussen P. Cerebral lactate uptake during exercise is driven by the increased arterial lactate concentration. J Appl Physiol (1985) 2021; 131:1824-1830. [PMID: 34734784 DOI: 10.1152/japplphysiol.00505.2021] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Exercise facilitates cerebral lactate uptake, likely by increasing arterial lactate concentration and hence the diffusion gradient across the blood brain barrier. However, non-specific β-adrenergic blockade by propranolol has previously reduced the arterio-jugular venous lactate difference (AVLac) during exercise, suggesting β-adrenergic control of cerebral lactate uptake. Alternatively, we hypothesize that propranolol reduces cerebral lactate uptake by decreasing arterial lactate concentration. To test that hypothesis, we evaluated cerebral lactate uptake taking changes in arterial concentration into account. Nine healthy males performed incremental cycling exercise to exhaustion with and without intravenous propranolol (18.7 ± 1.9 mg). Lactate concentration was determined in arterial and internal jugular venous blood at the end of each workload. To take changes in arterial lactate into account we calculated the fractional extraction (FELac) defined as AVLac divided by the arterial lactate concentration. Arterial lactate concentration was reduced by propranolol at any workload (p<0.05), reaching 14 ± 3 and 11 ± 3 mmol l-1 during maximal exercise without and with propranolol, respectively. While AVLac and FELac increased during exercise (both p<0.05), they were both unaffected by propranolol at any workload (p=0.68 and p=0.26) or for any given arterial lactate concentration (p=0.78 and p=0.22). These findings support that, while propranolol may reduce cerebral lactate uptake, this effect reflects the propranolol-induced reduction in arterial lactate concentration and not inhibition of a β-adrenergic mechanism within the brain. We hence conclude that cerebral lactate uptake during exercise is directly driven by the increasing arterial concentration with work rate.
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Affiliation(s)
- Christoph Siebenmann
- Zurich Center for Integrative Human Physiology (ZIHP), Institute of Physiology, University of Zurich, Zurich, Switzerland.,Institute of Mountain Emergency Medicine, EURAC Research, Bolzano, Italy
| | - Henrik Sorensen
- Department of Anaesthesia, The Copenhagen Muscle Research Centre, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark.,Department of Nutrition, Exercise and Sports, University of Copenhagen, Copenhagen, Denmark
| | - Thomas Christian Bonne
- Department of Nutrition, Exercise and Sports, University of Copenhagen, Copenhagen, Denmark
| | - Morten Zaar
- Department of Anaesthesia, The Copenhagen Muscle Research Centre, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | | | | | | | - Niels Henry Secher
- Department of Anaesthesia, The Copenhagen Muscle Research Centre, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - Carsten Lundby
- Zurich Center for Integrative Human Physiology (ZIHP), Institute of Physiology, University of Zurich, Zurich, Switzerland.,Innland Norway University of Applied Sciences, Lillehammer, Norway
| | - Peter Rasmussen
- Zurich Center for Integrative Human Physiology (ZIHP), Institute of Physiology, University of Zurich, Zurich, Switzerland
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6
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Matsui T. Exhaustive endurance exercise activates brain glycogen breakdown and lactate production more than insulin-induced hypoglycemia. Am J Physiol Regul Integr Comp Physiol 2021; 320:R500-R507. [PMID: 33533310 DOI: 10.1152/ajpregu.00119.2020] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2020] [Accepted: 01/29/2021] [Indexed: 11/22/2022]
Abstract
Brain glycogen localized in astrocytes produces lactate via cAMP signaling, which regulates memory functions and endurance capacity. Exhaustive endurance exercise with hypoglycemia decreases brain glycogen, although the mechanism underlying this phenomenon remains unclear. Since insulin-induced hypoglycemia decreases brain glycogen, this study tested the hypothesis that hypoglycemia mediates exercise-induced brain glycogen decrease. To test the hypothesis, the effects of insulin- and exhaustive exercise-induced hypoglycemia on brain glycogen levels were compared using the microwave irradiation method in adult Wistar rats. The insulin challenge and exhaustive exercise induced similar levels of severe hypoglycemia. Glycogen in the hypothalamus and cerebellum decreased similarly with the insulin challenge and exhaustive exercise; however, glycogen in the cortex, hippocampus, and brainstem of the exercise group were lower compared with the insulin group. Brain lactate and cAMP levels in the hypothalamus and cerebellum increased similarly with the insulin challenge and exhaustive exercise, but those in the cortex, hippocampus, and brainstem of the exercise group were higher compared with the insulin group. Blood glucose correlated positively with brain glycogen, but the slope of regression lines was greater in the exercise group compared with the insulin group in the cortex, hippocampus, and brainstem, but not the hypothalamus and cerebellum. These findings support the hypothesis that hypoglycemia mediates the exercise-induced reduction in brain glycogen, at least in the hypothalamus and cerebellum. However, glycogen reduction during exhaustive endurance exercise in the cortex, hippocampus, and brainstem is not due to hypoglycemia alone, implicating the role of exercise-specific neuronal activity in brain glycogen decrease.
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Affiliation(s)
- Takashi Matsui
- Exercise Biochemistry Division, Institute of Health and Sport Sciences, University of Tsukuba, Tsukuba, Japan
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7
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Burma JS, Copeland P, Macaulay A, Khatra O, Wright AD, Smirl JD. Dynamic cerebral autoregulation across the cardiac cycle during 8 hr of recovery from acute exercise. Physiol Rep 2021; 8:e14367. [PMID: 32163235 PMCID: PMC7066871 DOI: 10.14814/phy2.14367] [Citation(s) in RCA: 43] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2019] [Revised: 12/28/2019] [Accepted: 12/30/2019] [Indexed: 01/02/2023] Open
Abstract
Current protocols examining cerebral autoregulation (CA) parameters require participants to refrain from exercise for 12–24 hr, however there is sparse objective evidence examining the recovery trajectory of these measures following exercise across the cardiac cycle (diastole, mean, and systole). Therefore, this study sought to determine the duration acute exercise impacts CA and the within‐day reproducibility of these measures. Nine participants performed squat–stand maneuvers at 0.05 and 0.10 Hz at baseline before three interventions: 45‐min moderate‐continuous exercise (at 50% heart‐rate reserve), 30‐min high‐intensity intervals (ten, 1‐min at 85% heart‐rate reserve), and a control day (30‐min quiet rest). Squat–stands were repeated at hours zero, one, two, four, six, and eight after each condition. Transcranial doppler ultrasound of the middle cerebral artery (MCA) and the posterior cerebral artery (PCA) was used to characterize CA parameters across the cardiac cycle. At baseline, the systolic CA parameters were different than mean and diastolic components (ps < 0.015), however following both exercise protocols in both frequencies this disappeared until hour four within the MCA (ps > 0.079). In the PCA, phase values were affected only following high‐intensity intervals until hour four (ps > 0.055). Normalized gain in all cardiac cycle domains remained different following both exercise protocols (ps < 0.005) and across the control day (p < .050). All systolic differences returned by hour six across all measures (ps < 0.034). Future CA studies may use squat–stand maneuvers to assess the cerebral pressure–flow relationship 6 hr after exercise. Finally, CA measures under this paradigm appear to have negligible within‐day variation, allowing for reproducible interpretations to be drawn.
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Affiliation(s)
- Joel S Burma
- Concussion Research Laboratory, Faculty of Health and Exercise Science, University of British Columbia, Kelowna, BC, Canada.,Sport Injury Prevention Research Center, Faculty of Kinesiology, University of Calgary, Calgary, AB, Canada.,Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, Calgary, AB, Canada.,Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada
| | - Paige Copeland
- Concussion Research Laboratory, Faculty of Health and Exercise Science, University of British Columbia, Kelowna, BC, Canada
| | - Alannah Macaulay
- Concussion Research Laboratory, Faculty of Health and Exercise Science, University of British Columbia, Kelowna, BC, Canada
| | - Omeet Khatra
- Faculty of Medicine, University of British Columbia, Vancouver, BC, Canada
| | - Alexander D Wright
- Concussion Research Laboratory, Faculty of Health and Exercise Science, University of British Columbia, Kelowna, BC, Canada.,MD/PhD Program, Faculty of Medicine, University of British Columbia, Vancouver, BC, Canada.,Experimental Medicine Program, Faculty of Medicine, University of British Columbia, Vancouver, BC, Canada.,Southern Medical Program, University of British Columbia, Kelowna, BC, Canada
| | - Jonathan D Smirl
- Concussion Research Laboratory, Faculty of Health and Exercise Science, University of British Columbia, Kelowna, BC, Canada.,Sport Injury Prevention Research Center, Faculty of Kinesiology, University of Calgary, Calgary, AB, Canada.,Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, Calgary, AB, Canada.,Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada.,Southern Medical Program, University of British Columbia, Kelowna, BC, Canada.,Alberta Children's Hospital Research Institute, University of Calgary, Calgary, AB, Canada.,Libin Cardiovascular Institute of Alberta, University of Calgary, Calgary, AB, Canada
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8
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Ashley JD, Shelley JH, Sun J, Song J, Trent JA, Ambrosio LD, Larson DJ, Larson RD, Yabluchanskiy A, Kellawan JM. Cerebrovascular responses to graded exercise in young healthy males and females. Physiol Rep 2020; 8:e14622. [PMID: 33112497 PMCID: PMC7592493 DOI: 10.14814/phy2.14622] [Citation(s) in RCA: 4] [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: 09/12/2020] [Accepted: 10/04/2020] [Indexed: 01/06/2023] Open
Abstract
Although systemic sex-specific differences in cardiovascular responses to exercise are well established, the comparison of sex-specific cerebrovascular responses to exercise has gone under-investigated especially, during high intensity exercise. Therefore, our purpose was to compare cerebrovascular responses in males and females throughout a graded exercise test (GXT). Twenty-six participants (13 Females and 13 Males, 24 ± 4 yrs.) completed a GXT on a recumbent cycle ergometer consisting of 3-min stages. Each sex completed 50W, 75W, 100W stages. Thereafter, power output increased 30W/stage for females and 40W/stage for males until participants were unable to maintain 60-80 RPM. The final stage completed by the participant was considered maximum workload(Wmax ). Respiratory gases (End-tidal CO2 , EtCO2 ), middle cerebral artery blood velocity (MCAv), heart rate (HR), non-invasive mean arterial pressure (MAP), cardiac output (CO), and stroke volume (SV) were continuously recorded on a breath-by-breath or beat-by-beat basis. Cerebral perfusion pressure, CPP = MAP (0. 7,355 distance from heart-level to doppler probe) and cerebral vascular conductance index, CVCi = MCAv/CPP 100mmHg were calculated. The change from baseline (Δ) in MCAv was similar between the sexes during the GXT (p = .091, ωp2 = 0.05). However, ΔCPP (p < .001, ωp2 = 0.25) was greater in males at intensities ≥ 80% Wmax and ΔCVCi (p = .005, ωp2 = 0.15) was greater in females at 100% Wmax . Δ End-tidal CO2 (ΔEtCO2 ) was not different between the sexes during exercise (p = .606, ωp2 = -0.03). These data suggest there are sex-specific differences in cerebrovascular control, and these differences may only be identifiable at high and severe intensity exercise.
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Affiliation(s)
- John D. Ashley
- Department of Health and Exercise ScienceHuman Circulation Research LaboratoryUniversity of OklahomaNormanOKUSA
| | - Joe H. Shelley
- Department of Health and Exercise ScienceHuman Circulation Research LaboratoryUniversity of OklahomaNormanOKUSA
| | - Jongjoo Sun
- Department of Health and Exercise ScienceHuman Circulation Research LaboratoryUniversity of OklahomaNormanOKUSA
| | - Jiwon Song
- Department of Health and Exercise ScienceHuman Circulation Research LaboratoryUniversity of OklahomaNormanOKUSA
| | - Jacob A. Trent
- Department of Health and Exercise ScienceHuman Circulation Research LaboratoryUniversity of OklahomaNormanOKUSA
| | - Luis D. Ambrosio
- Department of Health and Exercise ScienceHuman Circulation Research LaboratoryUniversity of OklahomaNormanOKUSA
| | - Daniel J. Larson
- Department of Health and Exercise Science, Sport, Health, and Exercise Data Analytics LaboratoryUniversity of OklahomaNormanOKUSA
| | - Rebecca D. Larson
- Department of Health and Exercise ScienceBody Composition and Physical Performance Research LaboratoryUniversity of OklahomaNormanOKUSA
| | - Andriy Yabluchanskiy
- Oklahoma Center for GeroscienceDepartment of Biochemistry and Molecular BiologyUniversity of Oklahoma Health Sciences CenterOklahoma CityOKUSA
| | - J. Mikhail Kellawan
- Department of Health and Exercise ScienceHuman Circulation Research LaboratoryUniversity of OklahomaNormanOKUSA
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9
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Triantafyllou GA, Dipla K, Triantafyllou A, Gkaliagkousi E, Douma S. Measurement and Changes in Cerebral Oxygenation and Blood Flow at Rest and During Exercise in Normotensive and Hypertensive Individuals. Curr Hypertens Rep 2020; 22:71. [PMID: 32852614 DOI: 10.1007/s11906-020-01075-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
PURPOSE OF REVIEW Summarize the methods used for measurement of cerebral blood flow and oxygenation; describe the effects of hypertension on cerebral blood flow and oxygenation. RECENT FINDINGS Information regarding the effects of hypertension on cerebrovascular circulation during exercise is very limited, despite a plethora of methods to help with its assessment. In normotensive individuals performing incremental exercise testing, total blood flow to the brain increases. In contrast, the few studies performed in hypertensive patients suggest a smaller increase in cerebral blood flow, despite higher blood pressure levels. Endothelial dysfunction and increased vasoconstrictor concentration, as well as large vessel atherosclerosis and decreased small vessel number, have been proposed as the underlying mechanisms. Hypertension may adversely impact oxygen and blood delivery to the brain, both at rest and during exercise. Future studies should utilize the newer, noninvasive techniques to better characterize the interplay between the brain and exercise in hypertension.
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Affiliation(s)
- Georgios A Triantafyllou
- 3rd Department of Internal Medicine, Papageorgiou Hospital, Aristotle University of Thessaloniki, Ring Road Nea Eukarpia, 56403, Thessaloniki, Greece.,Division of Pulmonary, Allergy and Critical Care Medicine, University of Pittsburgh Medical Center, 3459 Fifth Avenue, Pittsburgh, PA, 15213, USA
| | - Konstantina Dipla
- Exercise Physiology and Biochemistry Laboratory, Department of Sports Science at Serres, Aristotle University of Thessaloniki, Agios Ioannis, 62122, Serres, Greece
| | - Areti Triantafyllou
- 3rd Department of Internal Medicine, Papageorgiou Hospital, Aristotle University of Thessaloniki, Ring Road Nea Eukarpia, 56403, Thessaloniki, Greece.
| | - Eugenia Gkaliagkousi
- 3rd Department of Internal Medicine, Papageorgiou Hospital, Aristotle University of Thessaloniki, Ring Road Nea Eukarpia, 56403, Thessaloniki, Greece
| | - Stella Douma
- 3rd Department of Internal Medicine, Papageorgiou Hospital, Aristotle University of Thessaloniki, Ring Road Nea Eukarpia, 56403, Thessaloniki, Greece
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10
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Caldwell HG, Coombs GB, Howe CA, Hoiland RL, Patrician A, Lucas SJ, Ainslie PN. Evidence for temperature‐mediated regional increases in cerebral blood flow during exercise. J Physiol 2020; 598:1459-1473. [DOI: 10.1113/jp278827] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2019] [Accepted: 12/20/2019] [Indexed: 12/18/2022] Open
Affiliation(s)
- Hannah G. Caldwell
- Centre for Heart Lung and Vascular Health School of Health and Exercise Sciences University of British Columbia Okanagan Kelowna BC Canada
| | - Geoff B. Coombs
- Centre for Heart Lung and Vascular Health School of Health and Exercise Sciences University of British Columbia Okanagan Kelowna BC Canada
| | - Connor A. Howe
- Centre for Heart Lung and Vascular Health School of Health and Exercise Sciences University of British Columbia Okanagan Kelowna BC Canada
| | - Ryan L. Hoiland
- Centre for Heart Lung and Vascular Health School of Health and Exercise Sciences University of British Columbia Okanagan Kelowna BC Canada
| | - Alexander Patrician
- Centre for Heart Lung and Vascular Health School of Health and Exercise Sciences University of British Columbia Okanagan Kelowna BC Canada
| | - Samuel J.E. Lucas
- School of Sport Exercise and Rehabilitation Sciences & Centre for Human Brain Health University of Birmingham Birmingham UK
| | - Philip N. Ainslie
- Centre for Heart Lung and Vascular Health School of Health and Exercise Sciences University of British Columbia Okanagan Kelowna BC Canada
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11
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Alwatban MR, Liu Y, Perdomo SJ, Ward JL, Vidoni ED, Burns JM, Billinger SA. TCD Cerebral Hemodynamic Changes during Moderate-Intensity Exercise in Older Adults. J Neuroimaging 2020; 30:76-81. [PMID: 31750593 PMCID: PMC6954976 DOI: 10.1111/jon.12675] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2019] [Revised: 10/18/2019] [Accepted: 10/23/2019] [Indexed: 01/14/2023] Open
Abstract
BACKGROUND AND PURPOSE Exercise plays an important role in supporting overall brain health. However, the mechanisms by which exercise supports brain health are imprecisely defined. Further, brain hemodynamic changes during exercise are not clearly understood, especially in older adults. The primary aim of this study was to compare cerebral blood flow velocity and pulsatility index (PI) during moderate-intensity exercise between older adults with normal pulsatile flow (normal PI) and older adults with elevated pulsatile flow (elevated PI). Secondary aims were to compare cardiovascular disease risk and cognitive function between individuals with elevated and nonelevated PI. METHODS Using transcranial Doppler ultrasound (TCD), middle cerebral artery blood velocity (MCAv) and PI were recorded during the rest and moderate-intensity exercise. End tidal carbon dioxide (PET CO2 ) and beat-to-beat mean arterial blood pressure were also recorded. RESULTS We enrolled 104 older adults into the study. The change in PI was greater in normal PI group (35.5% vs. 21.3%, P = .005). The change in MCAv was similar in both groups (11.6% for normal PI vs. 10.6% for elevated PI; P = .22). There was no significant difference in cardiovascular disease risk between the two groups (P = .77). Individuals with elevated PI performed significantly worse in WAIS-R Digit Symbol and Trail Making Test A (P = .04 and = .01, respectively). CONCLUSIONS The percent increase in PI from rest to moderate-intensity exercise was attenuated in the older adults with elevated resting PI. Higher resting PI may negatively affect brain health as evidenced by the slower processing speed scores.
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Affiliation(s)
- Mohammed R. Alwatban
- Department of Physical Therapy and Rehabilitation Science, University of Kansas Medical Center, Kansas City, KS USA
| | - Yumei Liu
- Department of Physical Therapy and Rehabilitation Science, University of Kansas Medical Center, Kansas City, KS USA
- Department of Vascular Ultrasonography, Xuanwu Hospital the Capital Medical University, Beijing China
| | - Sophy J. Perdomo
- Department of Physical Therapy and Rehabilitation Science, University of Kansas Medical Center, Kansas City, KS USA
| | - Jaimie L. Ward
- Department of Physical Therapy and Rehabilitation Science, University of Kansas Medical Center, Kansas City, KS USA
| | - Eric D. Vidoni
- University of Kansas Alzheimer’s Disease Center, Fairway, KS USA
| | - Jeffrey M. Burns
- University of Kansas Alzheimer’s Disease Center, Fairway, KS USA
| | - Sandra A. Billinger
- Department of Physical Therapy and Rehabilitation Science, University of Kansas Medical Center, Kansas City, KS USA
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12
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Matsui T, Soya M, Soya H. Endurance and Brain Glycogen: A Clue Toward Understanding Central Fatigue. ADVANCES IN NEUROBIOLOGY 2019; 23:331-346. [PMID: 31667814 DOI: 10.1007/978-3-030-27480-1_11] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Brain glycogen stored in astrocytes produces lactate as a neuronal energy source transported by monocarboxylate transporters (MCTs) to maintain neuronal functions, such as hippocampus-regulated memory formation. Although exercise activates brain neurons, the role of astrocytic glycogen in the brain during exercise remains unknown. Since muscle glycogen fuels active muscles during exercise, we hypothesized that astrocytic glycogen plays an energetic role in the brain during exercise to maintain endurance capacity through lactate transport. To explore this hypothesis, we have used a rat model of prolonged exercise, microwave irradiation for the accurate detection of brain glycogen, capillary electrophoresis-mass spectrometry-based metabolomics, and inhibitors of glycogenolysis (1,4-dideoxy-1,4-imino-D-arabinitol; DAB) and lactate transport (α-cyano-4-hydroxycinnamate; 4-CIN). During prolonged exhaustive exercise, muscle glycogen was depleted and brain glycogen decreased when associated with decreased blood glucose levels and increased serotonergic activity known as central fatigue factors, suggesting brain glycogen decrease as an integrative factor for central fatigue. Prolonged exhaustive exercise also increased MCT2 protein in the brain, which takes up lactate in neurons, just as muscle MCTs are increased. Metabolomics revealed that brain but not muscle adenosine triphosphate (ATP) was maintained with lactate and other glycogenolytic and glycolytic sources. Intracerebroventricular (icv) injection of DAB suppressed brain lactate production and decreased hippocampal ATP levels at exhaustion. An icv injection of 4-CIN also decreased hippocampal ATP, resulting in lower endurance capacity. Our findings provide direct evidence that astrocytic glycogen-derived lactate fuels the brain to maintain endurance capacity during exhaustive exercise. Brain ATP levels maintained by glycogen might serve as a possible defense mechanism for neurons in the exhausted state.
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Affiliation(s)
- Takashi Matsui
- Sport Neuroscience Division, Faculty of Health and Sport Sciences, Advanced Research Initiative for Human High Performance (ARIHHP), University of Tsukuba, Ibaraki, Japan.
| | - Mariko Soya
- Sport Neuroscience Division, Faculty of Health and Sport Sciences, Advanced Research Initiative for Human High Performance (ARIHHP), University of Tsukuba, Ibaraki, Japan
| | - Hideaki Soya
- Sport Neuroscience Division, Faculty of Health and Sport Sciences, Advanced Research Initiative for Human High Performance (ARIHHP), University of Tsukuba, Ibaraki, Japan.
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13
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Abstract
Glucose is the long-established, obligatory fuel for brain that fulfills many critical functions, including ATP production, oxidative stress management, and synthesis of neurotransmitters, neuromodulators, and structural components. Neuronal glucose oxidation exceeds that in astrocytes, but both rates increase in direct proportion to excitatory neurotransmission; signaling and metabolism are closely coupled at the local level. Exact details of neuron-astrocyte glutamate-glutamine cycling remain to be established, and the specific roles of glucose and lactate in the cellular energetics of these processes are debated. Glycolysis is preferentially upregulated during brain activation even though oxygen availability is sufficient (aerobic glycolysis). Three major pathways, glycolysis, pentose phosphate shunt, and glycogen turnover, contribute to utilization of glucose in excess of oxygen, and adrenergic regulation of aerobic glycolysis draws attention to astrocytic metabolism, particularly glycogen turnover, which has a high impact on the oxygen-carbohydrate mismatch. Aerobic glycolysis is proposed to be predominant in young children and specific brain regions, but re-evaluation of data is necessary. Shuttling of glucose- and glycogen-derived lactate from astrocytes to neurons during activation, neurotransmission, and memory consolidation are controversial topics for which alternative mechanisms are proposed. Nutritional therapy and vagus nerve stimulation are translational bridges from metabolism to clinical treatment of diverse brain disorders.
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Affiliation(s)
- Gerald A Dienel
- Department of Neurology, University of Arkansas for Medical Sciences , Little Rock, Arkansas ; and Department of Cell Biology and Physiology, University of New Mexico , Albuquerque, New Mexico
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14
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Evaluating the methods used for measuring cerebral blood flow at rest and during exercise in humans. Eur J Appl Physiol 2018; 118:1527-1538. [DOI: 10.1007/s00421-018-3887-y] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2018] [Accepted: 05/09/2018] [Indexed: 10/16/2022]
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15
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Smith KJ, Ainslie PN. Regulation of cerebral blood flow and metabolism during exercise. Exp Physiol 2017; 102:1356-1371. [PMID: 28786150 DOI: 10.1113/ep086249] [Citation(s) in RCA: 191] [Impact Index Per Article: 27.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2017] [Accepted: 07/31/2017] [Indexed: 12/18/2022]
Abstract
NEW FINDINGS What is the topic of this review? The manuscript collectively combines the experimental observations from >100 publications focusing on the regulation of cerebral blood flow and metabolism during exercise from 1945 to the present day. What advances does it highlight? This article highlights the importance of traditional and historical assessments of cerebral blood flow and metabolism during exercise, as well as traditional and new insights into the complex factors involved in the integrative regulation of brain blood flow and metabolism during exercise. The overarching theme is the importance of quantifying cerebral blood flow and metabolism during exercise using techniques that consider multiple volumetric cerebral haemodynamics (i.e. velocity, diameter, shear and flow). Cerebral function in humans is crucially dependent upon continuous oxygen delivery, metabolic nutrients and active regulation of cerebral blood flow (CBF). As a consequence, cerebrovascular function is precisely titrated by multiple physiological mechanisms, characterized by complex integration, synergism and protective redundancy. At rest, adequate CBF is regulated through reflexive responses in the following order of regulatory importance: fluctuating arterial blood gases (in particularly, partial pressure of carbon dioxide), cerebral metabolism, arterial blood pressure, neurogenic activity and cardiac output. Unfortunately, the magnitude that these integrative and synergistic relationships contribute to governing the CBF during exercise remains unclear. Despite some evidence indicating that CBF regulation during exercise is dependent on the changes of blood pressure, neurogenic activity and cardiac output, their role as a primary governor of the CBF response to exercise remains controversial. In contrast, the balance between the partial pressure of carbon dioxide and cerebral metabolism continues to gain empirical support as the primary contributor to the intensity-dependent changes in CBF observed during submaximal, moderate and maximal exercise. The goal of this review is to summarize the fundamental physiology and mechanisms involved in regulation of CBF and metabolism during exercise. The clinical implications of a better understanding of CBF during exercise and new research directions are also outlined.
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Affiliation(s)
- Kurt J Smith
- Cardiovascular Research Group, School of Sports Science, Exercise and Health, University of Western Australia, Crawley, WA, Australia.,Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, BC, Canada
| | - Philip N Ainslie
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, BC, Canada
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16
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Rokamp KZ, Staalsø JM, Zaar M, Rasmussen P, Petersen LG, Nielsen RV, Secher NH, Olsen NV, Nielsen HB. The Gly 16 Allele of the G16R Single Nucleotide Polymorphism in the β 2 -Adrenergic Receptor Gene Augments the Glycemic Response to Adrenaline in Humans. Front Physiol 2017; 8:661. [PMID: 28928674 PMCID: PMC5591882 DOI: 10.3389/fphys.2017.00661] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2016] [Accepted: 08/21/2017] [Indexed: 11/25/2022] Open
Abstract
Cerebral non-oxidative carbohydrate consumption may be driven by a β2-adrenergic mechanism. This study tested whether the 46G > A (G16R) single nucleotide polymorphism of the β2-adrenergic receptor gene (ADRB2) influences the metabolic and cerebrovascular responses to administration of adrenaline. Forty healthy Caucasian men were included from a group of genotyped individuals. Cardio- and cerebrovascular variables at baseline and during a 60-min adrenaline infusion (0.06 μg kg−1 min−1) were measured by Model flow, near-infrared spectroscopy and transcranial Doppler sonography. Blood samples were obtained from an artery and a retrograde catheter in the right internal jugular vein. The ADRB2 G16R variation had no effect on baseline arterial glucose, but during adrenaline infusion plasma glucose was up to 1.2 mM (CI95: 0.36–2.1, P < 0.026) higher in the Gly16 homozygotes compared with Arg16 homozygotes. The extrapolated steady-state levels of plasma glucose was 1.9 mM (CI95: 1.0 –2.9, PNLME < 0.0026) higher in the Gly16 homozygotes compared with Arg16 homozygotes. There was no change in the cerebral oxygen glucose index and the oxygen carbohydrate index during adrenaline infusion and the two indexes were not affected by G16R polymorphism. No difference between genotype groups was found in cardiac output at baseline or during adrenaline infusion. The metabolic response of glucose during adrenergic stimulation with adrenaline is associated to the G16R polymorphism of ADRB2, although without effect on cerebral metabolism. The differences in adrenaline-induced blood glucose increase between genotypes suggest an elevated β2-adrenergic response in the Gly16 homozygotes with increased adrenaline-induced glycolysis compared to Arg16 homozygotes.
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Affiliation(s)
- Kim Z Rokamp
- Department of Anesthesia, Rigshospitalet, University of CopenhagenCopenhagen, Denmark
| | - Jonatan M Staalsø
- Department of Neuroanesthesia, Rigshospitalet, University of CopenhagenCopenhagen, Denmark
| | - Morten Zaar
- Department of Anesthesia, Rigshospitalet, University of CopenhagenCopenhagen, Denmark
| | - Peter Rasmussen
- Department of Anesthesia, Rigshospitalet, University of CopenhagenCopenhagen, Denmark
| | - Lonnie G Petersen
- Department of Anesthesia, Rigshospitalet, University of CopenhagenCopenhagen, Denmark
| | - Rikke V Nielsen
- Department of Neuroanesthesia, Rigshospitalet, University of CopenhagenCopenhagen, Denmark
| | - Niels H Secher
- Department of Anesthesia, Rigshospitalet, University of CopenhagenCopenhagen, Denmark
| | - Niels V Olsen
- Department of Neuroanesthesia, Rigshospitalet, University of CopenhagenCopenhagen, Denmark.,Department of Neuroscience and Pharmacology, University of CopenhagenCopenhagen, Denmark
| | - Henning B Nielsen
- Department of Anesthesia, Rigshospitalet, University of CopenhagenCopenhagen, Denmark
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17
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Astrocytic glycogen-derived lactate fuels the brain during exhaustive exercise to maintain endurance capacity. Proc Natl Acad Sci U S A 2017; 114:6358-6363. [PMID: 28515312 DOI: 10.1073/pnas.1702739114] [Citation(s) in RCA: 102] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Brain glycogen stored in astrocytes provides lactate as an energy source to neurons through monocarboxylate transporters (MCTs) to maintain neuronal functions such as hippocampus-regulated memory formation. Although prolonged exhaustive exercise decreases brain glycogen, the role of this decrease and lactate transport in the exercising brain remains less clear. Because muscle glycogen fuels exercising muscles, we hypothesized that astrocytic glycogen plays an energetic role in the prolonged-exercising brain to maintain endurance capacity through lactate transport. To test this hypothesis, we used a rat model of exhaustive exercise and capillary electrophoresis-mass spectrometry-based metabolomics to observe comprehensive energetics of the brain (cortex and hippocampus) and muscle (plantaris). At exhaustion, muscle glycogen was depleted but brain glycogen was only decreased. The levels of MCT2, which takes up lactate in neurons, increased in the brain, as did muscle MCTs. Metabolomics revealed that brain, but not muscle, ATP was maintained with lactate and other glycogenolytic/glycolytic sources. Intracerebroventricular injection of the glycogen phosphorylase inhibitor 1,4-dideoxy-1,4-imino-d-arabinitol did not affect peripheral glycemic conditions but suppressed brain lactate production and decreased hippocampal ATP levels at exhaustion. An MCT2 inhibitor, α-cyano-4-hydroxy-cinnamate, triggered a similar response that resulted in lower endurance capacity. These findings provide direct evidence for the energetic role of astrocytic glycogen-derived lactate in the exhaustive-exercising brain, implicating the significance of brain glycogen level in endurance capacity. Glycogen-maintained ATP in the brain is a possible defense mechanism for neurons in the exhausted brain.
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18
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Sun SH, Yang L, Sun DF, Wu Y, Han J, Liu RC, Wang LJ. Effects of vasodilator and esmolol-induced hemodynamic stability on early post-operative cognitive dysfunction in elderly patients: a randomized trial. Afr Health Sci 2016; 16:1056-1066. [PMID: 28479899 DOI: 10.4314/ahs.v16i4.23] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
OBJECTIVE To investigate the effect of continuous intravenous injection of nicardipine and/or nitroglycerin with or without esmolol on the occurrence of early post-operative cognitive dysfunction (POCD) in elderly patients. METHODS Elderly patients (n=340) who underwent radiofrequency ablation for atrial fibrillation were randomized into five groups: A, nicardipine; B nicardipine+esmolol; C, (nitroglycerin) group; D nitroglycerin+esmolol; E (control) groups. The hemodynamic parameters were recorded, and Mini Mental State Examination was used to assess cognitive function. RESULTS At 30 min and 60 minutes after anesthesia and at the conclusion of surgery, the rate pressure product value was significantly lower in Groups B (10621.1±321.7, 10544.2±321.8, and 10701.3±325.5, respectively) and D (10807.4±351.1, 10784.3±360.3, and 10771.7±345.7, respectively) than in Group E (13217.1±377.6, 13203.5±357.3, and 13119.2±379.5, respectively). The heart rate was significantly higher in Groups A (104.1±10.3, 104.9±11.1, and 103.9±11.8, respectively) and C (103.7±11.3, 105.5±10.5, and 107.7±11.7, respectively) than in Group E (89.3±12.0, 88.5±11.5, and 85.5±11.6, respectively). The incidence of POCD was significantly lower in Groups A and B than in Groups C, D, and E. Univariate regression analysis showed that regimens in Groups A, B, and E and doses of propofol and fentanyl were risk factors for POCD. Multivariate logistic regression analysis revealed significant associations between the incidence of POCD and interventions in Groups A and B. CONCLUSION Maintenance of stable intraoperative hemodynamics using nicardipine and nitroglycerin or their combinations with esmolol, especially nicardipine with esmolol, reduced the incidence of POCD in the elderly with potential cardiovascular diseases.
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Affiliation(s)
- Sheng-Hui Sun
- Class twelve Grade two, The Middle School Attached to Liaoning Normal University, Dalian, Liaoning, China
| | - Lin Yang
- Department of Nerve Electroneurophysiology, The First Affiliated Hospital of Dalian Medical University, Dalian, Liaoning, China
| | - De-Feng Sun
- Department of Anesthesiology, The First Affiliated Hospital of Dalian Medical University, Dalian, Liaoning, China
| | - Yue Wu
- Department of Anesthesiology, The First Affiliated Hospital of Dalian Medical University, Dalian, Liaoning, China
| | - Jun Han
- Department of Anesthesiology, The First Affiliated Hospital of Dalian Medical University, Dalian, Liaoning, China
| | - Ruo-Chuan Liu
- Department of Anesthesiology, The First Affiliated Hospital of Dalian Medical University, Dalian, Liaoning, China
| | - Li-Jie Wang
- Department of Anesthesiology, The First Affiliated Hospital of Dalian Medical University, Dalian, Liaoning, China
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19
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Bain AR, Ainslie PN, Hoiland RL, Barak OF, Cavar M, Drvis I, Stembridge M, MacLeod DM, Bailey DM, Dujic Z, MacLeod DB. Cerebral oxidative metabolism is decreased with extreme apnoea in humans; impact of hypercapnia. J Physiol 2016; 594:5317-28. [PMID: 27256521 DOI: 10.1113/jp272404] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2016] [Accepted: 05/18/2016] [Indexed: 12/25/2022] Open
Abstract
KEY POINTS The present study describes the cerebral oxidative and non-oxidative metabolism in man during a prolonged apnoea (ranging from 3 min 36 s to 7 min 26 s) that generates extremely low levels of blood oxygen and high levels of carbon dioxide. The cerebral oxidative metabolism, measured from the product of cerebral blood flow and the radial artery-jugular venous oxygen content difference, was reduced by ∼29% at the termination of apnoea, although there was no change in the non-oxidative metabolism. A subset study with mild and severe hypercapnic breathing at the same level of hypoxia suggests that hypercapnia can partly explain the cerebral metabolic reduction near the apnoea breakpoint. A hypercapnia-induced oxygen-conserving response may protect the brain against severe oxygen deprivation associated with prolonged apnoea. ABSTRACT Prolonged apnoea in humans is reflected in progressive hypoxaemia and hypercapnia. In the present study, we explore the cerebral metabolic responses under extreme hypoxia and hypercapnia associated with prolonged apnoea. We hypothesized that the cerebral metabolic rate for oxygen (CMRO2 ) will be reduced near the termination of apnoea, attributed in part to the hypercapnia. Fourteen elite apnoea-divers performed a maximal apnoea (range 3 min 36 s to 7 min 26 s) under dry laboratory conditions. In a subset study with the same divers, the impact of hypercapnia on cerebral metabolism was determined using varying levels of hypercapnic breathing, against the background of similar hypoxia. In both studies, the CMRO2 was calculated from the product of cerebral blood flow (ultrasound) and the radial artery-internal jugular venous oxygen content difference. Non-oxidative cerebral metabolism was calculated from the ratio of oxygen and carbohydrate (lactate and glucose) metabolism. The CMRO2 was reduced by ∼29% (P < 0.01, Cohen's d = 1.18) near the termination of apnoea compared to baseline, although non-oxidative metabolism remained unaltered. In the subset study, in similar backgrounds of hypoxia (arterial O2 tension: ∼38.4 mmHg), severe hypercapnia (arterial CO2 tension: ∼58.7 mmHg), but not mild-hypercapnia (arterial CO2 tension: ∼46.3 mmHg), depressed the CMRO2 (∼17%, P = 0.04, Cohen's d = 0.87). Similarly to the apnoea, there was no change in the non-oxidative metabolism. These data indicate that hypercapnia can partly explain the reduction in CMRO2 near the apnoea breakpoint. This hypercapnic-induced oxygen conservation may protect the brain against severe hypoxaemia associated with prolonged apnoea.
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Affiliation(s)
- Anthony R Bain
- Centre for Heart Lung and Vascular Health, University of British Columbia, Kelowna, BC, Canada. ,
| | - Philip N Ainslie
- Centre for Heart Lung and Vascular Health, University of British Columbia, Kelowna, BC, Canada
| | - Ryan L Hoiland
- Centre for Heart Lung and Vascular Health, University of British Columbia, Kelowna, BC, Canada
| | - Otto F Barak
- School of Medicine, University of Split, Split, Croatia.,Faculty of Medicine, University of Novi Sad, Serbia
| | - Marija Cavar
- School of Medicine, University of Split, Split, Croatia
| | - Ivan Drvis
- School of Kinesiology, University of Zagreb, Zagreb, Croatia
| | | | | | - Damian M Bailey
- Faculty of Life Sciences and Education, University of South Wales, Glamorgan, UK
| | - Zeljko Dujic
- School of Medicine, University of Split, Split, Croatia
| | - David B MacLeod
- Department of Anesthesiology, Duke University Medical Center, Durham, NC, USA
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20
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Dienel GA, Cruz NF. Aerobic glycolysis during brain activation: adrenergic regulation and influence of norepinephrine on astrocytic metabolism. J Neurochem 2016; 138:14-52. [DOI: 10.1111/jnc.13630] [Citation(s) in RCA: 99] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2016] [Revised: 03/24/2016] [Accepted: 03/31/2016] [Indexed: 12/17/2022]
Affiliation(s)
- Gerald A. Dienel
- Department of Cell Biology and Physiology; University of New Mexico; Albuquerque; New Mexico USA
- Department of Neurology; University of Arkansas for Medical Sciences; Little Rock Arkansas USA
| | - Nancy F. Cruz
- Department of Neurology; University of Arkansas for Medical Sciences; Little Rock Arkansas USA
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21
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Brooks GA. Energy Flux, Lactate Shuttling, Mitochondrial Dynamics, and Hypoxia. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 903:439-55. [DOI: 10.1007/978-1-4899-7678-9_29] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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22
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Matsui T, Soya S, Kawanaka K, Soya H. Brain Glycogen Decreases During Intense Exercise Without Hypoglycemia: The Possible Involvement of Serotonin. Neurochem Res 2015; 40:1333-40. [PMID: 26037553 DOI: 10.1007/s11064-015-1594-1] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2015] [Revised: 04/21/2015] [Accepted: 04/28/2015] [Indexed: 11/25/2022]
Abstract
Brain glycogen stored in astrocytes, a source of lactate as a neuronal energy source, decreases during prolonged exercise with hypoglycemia. However, brain glycogen dynamics during exercise without hypoglycemia remain unknown. Since intense exercise increases brain noradrenaline and serotonin as known inducers for brain glycogenolysis, we hypothesized that brain glycogen decreases with intense exercise not accompanied by hypoglycemia. To test this hypothesis, we employed a well-established acute intense exercise model of swimming in rats. Rats swam for fourteen 20 s bouts with a weight equal to 8 % of their body mass and were sacrificed using high-power (10 kW) microwave irradiation to inactivate brain enzymes for accurate detection of brain glycogen and monoamines. Intense exercise did not alter blood glucose, but did increase blood lactate levels. Immediately after exercise, brain glycogen decreased and brain lactate increased in the hippocampus, cerebellum, cortex, and brainstem. Simultaneously, serotonin turnover in the hippocampus and brainstem mutually increased and were associated with decreased brain glycogen. Intense swimming exercise that does not induce hypoglycemia decreases brain glycogen associated with increased brain lactate, implying an importance of glycogen in brain energetics during intense exercise even without hypoglycemia. Activated serotonergic regulation is a possible underlying mechanism for intense exercise-induced glycogenolysis at least in the hippocampus and brainstem.
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Affiliation(s)
- Takashi Matsui
- Laboratory of Exercise Biochemistry and Neuroendocrinology, Institute for Health and Sport Sciences, University of Tsukuba, 1-1-1 Tennoudai, Tsukuba, Ibaraki, 305-8574, Japan
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23
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Jalloh I, Carpenter KLH, Helmy A, Carpenter TA, Menon DK, Hutchinson PJ. Glucose metabolism following human traumatic brain injury: methods of assessment and pathophysiological findings. Metab Brain Dis 2015; 30:615-32. [PMID: 25413449 PMCID: PMC4555200 DOI: 10.1007/s11011-014-9628-y] [Citation(s) in RCA: 66] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/26/2014] [Accepted: 11/03/2014] [Indexed: 02/02/2023]
Abstract
The pathophysiology of traumatic brain (TBI) injury involves changes to glucose uptake into the brain and its subsequent metabolism. We review the methods used to study cerebral glucose metabolism with a focus on those used in clinical TBI studies. Arterio-venous measurements provide a global measure of glucose uptake into the brain. Microdialysis allows the in vivo sampling of brain extracellular fluid and is well suited to the longitudinal assessment of metabolism after TBI in the clinical setting. A recent novel development is the use of microdialysis to deliver glucose and other energy substrates labelled with carbon-13, which allows the metabolism of glucose and other substrates to be tracked. Positron emission tomography and magnetic resonance spectroscopy allow regional differences in metabolism to be assessed. We summarise the data published from these techniques and review their potential uses in the clinical setting.
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Affiliation(s)
- Ibrahim Jalloh
- Division of Neurosurgery, Department of Clinical Neurosciences, University of Cambridge, Box 167 Cambridge Biomedical Campus, Cambridge, CB2 0QQ, UK,
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Adeva-Andany M, López-Ojén M, Funcasta-Calderón R, Ameneiros-Rodríguez E, Donapetry-García C, Vila-Altesor M, Rodríguez-Seijas J. Comprehensive review on lactate metabolism in human health. Mitochondrion 2014; 17:76-100. [PMID: 24929216 DOI: 10.1016/j.mito.2014.05.007] [Citation(s) in RCA: 359] [Impact Index Per Article: 35.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2013] [Revised: 03/19/2014] [Accepted: 05/05/2014] [Indexed: 02/07/2023]
Abstract
Metabolic pathways involved in lactate metabolism are important to understand the physiological response to exercise and the pathogenesis of prevalent diseases such as diabetes and cancer. Monocarboxylate transporters are being investigated as potential targets for diagnosis and therapy of these and other disorders. Glucose and alanine produce pyruvate which is reduced to lactate by lactate dehydrogenase in the cytoplasm without oxygen consumption. Lactate removal takes place via its oxidation to pyruvate by lactate dehydrogenase. Pyruvate may be either oxidized to carbon dioxide producing energy or transformed into glucose. Pyruvate oxidation requires oxygen supply and the cooperation of pyruvate dehydrogenase, the tricarboxylic acid cycle, and the mitochondrial respiratory chain. Enzymes of the gluconeogenesis pathway sequentially convert pyruvate into glucose. Congenital or acquired deficiency on gluconeogenesis or pyruvate oxidation, including tissue hypoxia, may induce lactate accumulation. Both obese individuals and patients with diabetes show elevated plasma lactate concentration compared to healthy subjects, but there is no conclusive evidence of hyperlactatemia causing insulin resistance. Available evidence suggests an association between defective mitochondrial oxidative capacity in the pancreatic β-cells and diminished insulin secretion that may trigger the development of diabetes in patients already affected with insulin resistance. Several mutations in the mitochondrial DNA are associated with diabetes mellitus, although the pathogenesis remains unsettled. Mitochondrial DNA mutations have been detected in a number of human cancers. d-lactate is a lactate enantiomer normally formed during glycolysis. Excess d-lactate is generated in diabetes, particularly during diabetic ketoacidosis. d-lactic acidosis is typically associated with small bowel resection.
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Affiliation(s)
- M Adeva-Andany
- Nephrology Division, Hospital General Juan Cardona, Ave. Pardo Bazán, s/n, 15406 Ferrol, La Coruña, Spain.
| | - M López-Ojén
- Internal Medicine Division, Policlínica Assistens, c/Federico García, 4-planta baja, 15009 La Coruña, Spain
| | - R Funcasta-Calderón
- Nephrology Division, Hospital General Juan Cardona, Ave. Pardo Bazán, s/n, 15406 Ferrol, La Coruña, Spain
| | - E Ameneiros-Rodríguez
- Nephrology Division, Hospital General Juan Cardona, Ave. Pardo Bazán, s/n, 15406 Ferrol, La Coruña, Spain
| | - C Donapetry-García
- Nephrology Division, Hospital General Juan Cardona, Ave. Pardo Bazán, s/n, 15406 Ferrol, La Coruña, Spain
| | - M Vila-Altesor
- Nephrology Division, Hospital General Juan Cardona, Ave. Pardo Bazán, s/n, 15406 Ferrol, La Coruña, Spain
| | - J Rodríguez-Seijas
- Nephrology Division, Hospital General Juan Cardona, Ave. Pardo Bazán, s/n, 15406 Ferrol, La Coruña, Spain
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Fabricius-Bjerre A, Overgaard A, Winther-Olesen M, Lönn L, Secher NH, Nielsen HB. Reduced cerebral oxygen-carbohydrate index during endotracheal intubation in vascular surgical patients. Clin Physiol Funct Imaging 2014; 35:404-10. [PMID: 24903076 DOI: 10.1111/cpf.12176] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2013] [Accepted: 05/05/2014] [Indexed: 11/27/2022]
Abstract
Brain activation reduces balance between cerebral consumption of oxygen versus carbohydrate as expressed by the so-called cerebral oxygen-carbohydrate-index (OCI). We evaluated whether preparation for surgery, anaesthesia including tracheal intubation and surgery affect OCI. In patients undergoing aortic surgery, arterial to internal jugular venous (a-v) concentration differences for oxygen versus lactate and glucose were determined from before anaesthesia to when the patient left the recovery room. Intravenous anaesthesia was supplemented with thoracic epidural anaesthesia for open aortic surgery (n = 5) and infiltration with bupivacaine for endovascular procedures (n = 14). The a-v difference for O2 decreased throughout anaesthesia and in the recovery room (1.6 ± 1.9 versus 3.2 ± 0.8 mmol l(-1), mean ± SD), and while a-v glucose decreased during surgery and into the recovery (0.4 ± 0.2 versus 0.7 ± 0.2 mmol l(-1) , P<0.05), a-v lactate did not change significantly (0.03 ± 0.16 versus -0.03 ± 0.09 mmol l(-1)). Thus, OCI decreased from 5.2 ± 1.8 before induction of anaesthesia to 3.2 ± 1.0 following tracheal intubation (P<0.05) because of the decrease in a-v O2 with a recovery for OCI to 4.6 ± 1.4 during surgery and to 5.6 ± 1.7 in the recovery room. In conclusion, preparation for surgery and tracheal intubation decrease OCI that recovers during surgery under the influence of sensory blockade.
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Affiliation(s)
- Andreas Fabricius-Bjerre
- Departments of Anaesthesia, Radiology, and Vascular Surgery, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - Anders Overgaard
- Departments of Anaesthesia, Radiology, and Vascular Surgery, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - Marie Winther-Olesen
- Departments of Anaesthesia, Radiology, and Vascular Surgery, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - Lars Lönn
- Departments of Anaesthesia, Radiology, and Vascular Surgery, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - Niels H Secher
- Departments of Anaesthesia, Radiology, and Vascular Surgery, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - Henning B Nielsen
- Departments of Anaesthesia, Radiology, and Vascular Surgery, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
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Jalloh I, Helmy A, Shannon RJ, Gallagher CN, Menon DK, Carpenter KLH, Hutchinson PJ. Lactate uptake by the injured human brain: evidence from an arteriovenous gradient and cerebral microdialysis study. J Neurotrauma 2013; 30:2031-7. [PMID: 23968221 DOI: 10.1089/neu.2013.2947] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Lactate has been regarded as a waste product of anaerobic metabolism of glucose. Evidence also suggests, however, that the brain may use lactate as an alternative fuel. Our aim was to determine the extent of lactate uptake from the circulation into the brain after traumatic brain injury (TBI) and to compare it with levels of lactate in the brain extracellular fluid. We recruited 19 patients with diffuse TBI, monitored with cerebral microdialysis and jugular bulb catheters. Serial arteriovenous (AV) concentration differences of glucose and lactate were calculated from arterial and jugular blood samples, providing a measure of net uptake or export by the brain. Microdialysis was used to measure brain extracellular glucose and lactate. In 17/19 patients studied for 5 days post-injury, there were periods of net lactate uptake into the brain, most frequently on day 3 after injury. Brain microdialysate lactate had a median (interquartile range [IQR]) concentration of 2.5 (1.5-3.2) mmol/L during lactate uptake and 2.2 (1.7-3.0) mmol/L during lactate export. Lactate uptake into the brain occurred at a median (IQR) arterial lactate concentration of 1.6 (1.0-2.2) mmol/L. Lactate uptake was associated with significantly higher AV difference in glucose values with a median (IQR) of 0.4 (0.03-0.7) mmol/L during uptake and 0.1 (-0.2-0.3) mmol/L during lactate export (Mann-Whitney U p=0.003). Despite relatively high brain lactate compared with arterial lactate concentrations, the brain appears to up-regulate lactate transport into the brain after TBI. This may serve to satisfy greater demands for energy substrate from the brain after TBI.
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Affiliation(s)
- Ibrahim Jalloh
- 1 Division of Neurosurgery, Department of Clinical Neurosciences, University of Cambridge , Cambridge, United Kingdom
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Fisher JP, Hartwich D, Seifert T, Olesen ND, McNulty CL, Nielsen HB, van Lieshout JJ, Secher NH. Cerebral perfusion, oxygenation and metabolism during exercise in young and elderly individuals. J Physiol 2012; 591:1859-70. [PMID: 23230234 DOI: 10.1113/jphysiol.2012.244905] [Citation(s) in RCA: 82] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
We evaluated cerebral perfusion, oxygenation and metabolism in 11 young (22 ± 1 years) and nine older (66 ± 2 years) individuals at rest and during cycling exercise at low (25% W(max)), moderate (50% Wmax), high (75% W(max)) and exhaustive (100% W(max)) workloads. Mean middle cerebral artery blood velocity (MCA V(mean)), mean arterial pressure (MAP), cardiac output (CO) and partial pressure of arterial carbon dioxide (P(aCO2)) were measured. Blood samples were obtained from the right internal jugular vein and brachial artery to determine concentration differences for oxygen (O2), glucose and lactate across the brain. The molar ratio between cerebral uptake of O2 versus carbohydrate (O2-carbohydrate index; O2/[glucose + 1/2 lactate]; OCI), the cerebral metabolic rate of O2 (CMRO2) and changes in mitochondrial O2 tension ( P(mitoO2)) were calculated. 100% W(max) was ~33% lower in the older group. Exercise increased MAP and CO in both groups (P < 0.05 vs. rest), but at each intensity MAP was higher and CO lower in the older group (P < 0.05). MCA V(mean), P(aCO2) and cerebral vascular conductance index (MCA V(mean)/MAP) were lower in the older group at each exercise intensity (P < 0.05). In contrast, young and older individuals exhibited similar increases in CMRO2 (by ~30 μmol (100 g(-1)) min(-1)), and decreases in OCI (by ~1.5) and (by ~10 mmHg) during exercise at 75% W(max). Thus, despite the older group having reduced cerebral perfusion and maximal exercise capacity, cerebral oxygenation and uptake of lactate and glucose are similar during exercise in young and older individuals.
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Affiliation(s)
- James P Fisher
- School of Sport and Exercise Sciences, College of Life and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham, UK.
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Schurr A, Gozal E. Aerobic production and utilization of lactate satisfy increased energy demands upon neuronal activation in hippocampal slices and provide neuroprotection against oxidative stress. Front Pharmacol 2012; 2:96. [PMID: 22275901 PMCID: PMC3257848 DOI: 10.3389/fphar.2011.00096] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2011] [Accepted: 12/23/2011] [Indexed: 12/21/2022] Open
Abstract
Ever since it was shown for the first time that lactate can support neuronal function in vitro as a sole oxidative energy substrate, investigators in the field of neuroenergetics have been debating the role, if any, of this glycolytic product in cerebral energy metabolism. Our experiments employed the rat hippocampal slice preparation with electrophysiological and biochemical methodologies. The data generated by these experiments (a) support the hypothesis that lactate, not pyruvate, is the end-product of cerebral aerobic glycolysis; (b) indicate that lactate plays a major and crucial role in affording neural tissue to respond adequately to glutamate excitation and to recover unscathed post-excitation; (c) suggest that neural tissue activation is accompanied by aerobic lactate and NADH production, the latter being produced when the former is converted to pyruvate by mitochondrial lactate dehydrogenase (mLDH); (d) imply that NADH can be utilized as an endogenous scavenger of reactive oxygen species (ROS) to provide neuroprotection against ROS-induced neuronal damage.
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Affiliation(s)
- Avital Schurr
- Department of Anesthesiology and Perioperative Medicine, School of Medicine, University of Louisville Louisville, KY, USA.
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Errata. J Physiol 2011. [DOI: 10.1113/jphysiol.2011.222901] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
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Seifert T, Secher NH. Sympathetic influence on cerebral blood flow and metabolism during exercise in humans. Prog Neurobiol 2011; 95:406-26. [PMID: 21963551 DOI: 10.1016/j.pneurobio.2011.09.008] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2011] [Revised: 09/13/2011] [Accepted: 09/19/2011] [Indexed: 11/26/2022]
Abstract
This review focuses on the possibility that autonomic activity influences cerebral blood flow (CBF) and metabolism during exercise in humans. Apart from cerebral autoregulation, the arterial carbon dioxide tension, and neuronal activation, it may be that the autonomic nervous system influences CBF as evidenced by pharmacological manipulation of adrenergic and cholinergic receptors. Cholinergic blockade by glycopyrrolate blocks the exercise-induced increase in the transcranial Doppler determined mean flow velocity (MCA Vmean). Conversely, alpha-adrenergic activation increases that expression of cerebral perfusion and reduces the near-infrared determined cerebral oxygenation at rest, but not during exercise associated with an increased cerebral metabolic rate for oxygen (CMRO(2)), suggesting competition between CMRO(2) and sympathetic control of CBF. CMRO(2) does not change during even intense handgrip, but increases during cycling exercise. The increase in CMRO(2) is unaffected by beta-adrenergic blockade even though CBF is reduced suggesting that cerebral oxygenation becomes critical and a limited cerebral mitochondrial oxygen tension may induce fatigue. Also, sympathetic activity may drive cerebral non-oxidative carbohydrate uptake during exercise. Adrenaline appears to accelerate cerebral glycolysis through a beta2-adrenergic receptor mechanism since noradrenaline is without such an effect. In addition, the exercise-induced cerebral non-oxidative carbohydrate uptake is blocked by combined beta 1/2-adrenergic blockade, but not by beta1-adrenergic blockade. Furthermore, endurance training appears to lower the cerebral non-oxidative carbohydrate uptake and preserve cerebral oxygenation during submaximal exercise. This is possibly related to an attenuated catecholamine response. Finally, exercise promotes brain health as evidenced by increased release of brain-derived neurotrophic factor (BDNF) from the brain.
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Affiliation(s)
- Thomas Seifert
- Department of Anaesthesia and The Copenhagen Muscle Research Centre, Rigshospitalet 2041, University of Copenhagen, Blegdamsvej 9, DK-2100 Copenhagen Ø, Denmark.
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Brassard P, Jensen AS, Nordsborg N, Gustafsson F, Møller JE, Hassager C, Boesgaard S, Hansen PB, Olsen PS, Sander K, Secher NH, Madsen PL. Central and Peripheral Blood Flow During Exercise With a Continuous-Flow Left Ventricular Assist Device. Circ Heart Fail 2011; 4:554-60. [DOI: 10.1161/circheartfailure.110.958041] [Citation(s) in RCA: 87] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
- Patrice Brassard
- From the Departments of Anesthesia (P.B., N.N., N.H.S.), Cardiology (P.B., A.S.J., F.G., J.E.M., C.H., S.B., P.L.M.), and Cardiothoracic Surgery (P.B.H., P.O., K.S.), The Heart Centre, Rigshospitalet, University of Copenhagen, Denmark
| | - Annette S. Jensen
- From the Departments of Anesthesia (P.B., N.N., N.H.S.), Cardiology (P.B., A.S.J., F.G., J.E.M., C.H., S.B., P.L.M.), and Cardiothoracic Surgery (P.B.H., P.O., K.S.), The Heart Centre, Rigshospitalet, University of Copenhagen, Denmark
| | - Nikolai Nordsborg
- From the Departments of Anesthesia (P.B., N.N., N.H.S.), Cardiology (P.B., A.S.J., F.G., J.E.M., C.H., S.B., P.L.M.), and Cardiothoracic Surgery (P.B.H., P.O., K.S.), The Heart Centre, Rigshospitalet, University of Copenhagen, Denmark
| | - Finn Gustafsson
- From the Departments of Anesthesia (P.B., N.N., N.H.S.), Cardiology (P.B., A.S.J., F.G., J.E.M., C.H., S.B., P.L.M.), and Cardiothoracic Surgery (P.B.H., P.O., K.S.), The Heart Centre, Rigshospitalet, University of Copenhagen, Denmark
| | - Jacob E. Møller
- From the Departments of Anesthesia (P.B., N.N., N.H.S.), Cardiology (P.B., A.S.J., F.G., J.E.M., C.H., S.B., P.L.M.), and Cardiothoracic Surgery (P.B.H., P.O., K.S.), The Heart Centre, Rigshospitalet, University of Copenhagen, Denmark
| | - Christian Hassager
- From the Departments of Anesthesia (P.B., N.N., N.H.S.), Cardiology (P.B., A.S.J., F.G., J.E.M., C.H., S.B., P.L.M.), and Cardiothoracic Surgery (P.B.H., P.O., K.S.), The Heart Centre, Rigshospitalet, University of Copenhagen, Denmark
| | - Søren Boesgaard
- From the Departments of Anesthesia (P.B., N.N., N.H.S.), Cardiology (P.B., A.S.J., F.G., J.E.M., C.H., S.B., P.L.M.), and Cardiothoracic Surgery (P.B.H., P.O., K.S.), The Heart Centre, Rigshospitalet, University of Copenhagen, Denmark
| | - Peter Bo Hansen
- From the Departments of Anesthesia (P.B., N.N., N.H.S.), Cardiology (P.B., A.S.J., F.G., J.E.M., C.H., S.B., P.L.M.), and Cardiothoracic Surgery (P.B.H., P.O., K.S.), The Heart Centre, Rigshospitalet, University of Copenhagen, Denmark
| | - Peter Skov Olsen
- From the Departments of Anesthesia (P.B., N.N., N.H.S.), Cardiology (P.B., A.S.J., F.G., J.E.M., C.H., S.B., P.L.M.), and Cardiothoracic Surgery (P.B.H., P.O., K.S.), The Heart Centre, Rigshospitalet, University of Copenhagen, Denmark
| | - Kåre Sander
- From the Departments of Anesthesia (P.B., N.N., N.H.S.), Cardiology (P.B., A.S.J., F.G., J.E.M., C.H., S.B., P.L.M.), and Cardiothoracic Surgery (P.B.H., P.O., K.S.), The Heart Centre, Rigshospitalet, University of Copenhagen, Denmark
| | - Niels H. Secher
- From the Departments of Anesthesia (P.B., N.N., N.H.S.), Cardiology (P.B., A.S.J., F.G., J.E.M., C.H., S.B., P.L.M.), and Cardiothoracic Surgery (P.B.H., P.O., K.S.), The Heart Centre, Rigshospitalet, University of Copenhagen, Denmark
| | - Per Lav Madsen
- From the Departments of Anesthesia (P.B., N.N., N.H.S.), Cardiology (P.B., A.S.J., F.G., J.E.M., C.H., S.B., P.L.M.), and Cardiothoracic Surgery (P.B.H., P.O., K.S.), The Heart Centre, Rigshospitalet, University of Copenhagen, Denmark
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Rasmussen P, Wyss MT, Lundby C. Cerebral glucose and lactate consumption during cerebral activation by physical activity in humans. FASEB J 2011; 25:2865-73. [DOI: 10.1096/fj.11-183822] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Peter Rasmussen
- Zurich Centre for Integrative Human PhysiologyDepartment of PhysiologyUniversity of ZurichSwitzerland
| | - Matthias T. Wyss
- Institute of Pharmacology and ToxicologyUniversity of ZurichSwitzerland
| | - Carsten Lundby
- Zurich Centre for Integrative Human PhysiologyDepartment of PhysiologyUniversity of ZurichSwitzerland
- Institute of Pharmacology and ToxicologyUniversity of ZurichSwitzerland
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Matsui T, Soya S, Okamoto M, Ichitani Y, Kawanaka K, Soya H. Brain glycogen decreases during prolonged exercise. J Physiol 2011. [PMID: 21521757 DOI: 10.1113/jphysiol.2011.203570] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Brain glycogen could be a critical energy source for brain activity when the glucose supply from the blood is inadequate (hypoglycaemia). Although untested, it is hypothesized that during prolonged exhaustive exercise that induces hypoglycaemia and muscular glycogen depletion, the resultant hypoglycaemia may cause a decrease in brain glycogen. Here,we tested this hypothesis and also investigated the possible involvement of brain monoamines with the reduced levels of brain glycogen. For this purpose,we exercised male Wistar rats on a treadmill for different durations (30-120 min) at moderate intensity (20 m min⁻¹) and measured their brain glycogen levels using high-power microwave irradiation (10 kW). At the end of 30 and 60 min of running, the brain glycogen levels remained unchanged from resting levels, but liver and muscle glycogen decreased. After 120 min of running, the glycogen levels decreased significantly by ∼37-60% in five discrete brain loci (the cerebellum 60%, cortex 48%, hippocampus 43%, brainstem 37% and hypothalamus 34%) compared to those of the sedentary control. The brain glycogen levels in all five regions after running were positively correlated with the respective blood and brain glucose levels. Further, in the cortex, the levels of methoxyhydroxyphenylglycol (MHPG) and 5-hydroxyindoleacetic acid (5-HIAA), potential involved in degradation of the brain glycogen, increased during prolonged exercise and negatively correlated with the glycogen levels. These results support the hypothesis that brain glycogen could decrease with prolonged exhaustive exercise. Increased monoamines together with hypoglycaemia should be associated with the development of decreased brain glycogen, suggesting a new clue towards the understanding of central fatigue during prolonged exercise.
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Affiliation(s)
- Takashi Matsui
- Laboratory of Exercise Biochemistry and Neuroendocrinology, University of Tsukuba Graduate School of Comprehensive Human Sciences, Tsukuba, Ibaraki, Japan
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Matsui T, Soya S, Okamoto M, Ichitani Y, Kawanaka K, Soya H. Brain glycogen decreases during prolonged exercise. J Physiol 2011; 589:3383-93. [PMID: 21521757 DOI: 10.1113/jphysiol.2010.203570] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Brain glycogen could be a critical energy source for brain activity when the glucose supply from the blood is inadequate (hypoglycaemia). Although untested, it is hypothesized that during prolonged exhaustive exercise that induces hypoglycaemia and muscular glycogen depletion, the resultant hypoglycaemia may cause a decrease in brain glycogen. Here,we tested this hypothesis and also investigated the possible involvement of brain monoamines with the reduced levels of brain glycogen. For this purpose,we exercised male Wistar rats on a treadmill for different durations (30-120 min) at moderate intensity (20 m min⁻¹) and measured their brain glycogen levels using high-power microwave irradiation (10 kW). At the end of 30 and 60 min of running, the brain glycogen levels remained unchanged from resting levels, but liver and muscle glycogen decreased. After 120 min of running, the glycogen levels decreased significantly by ∼37-60% in five discrete brain loci (the cerebellum 60%, cortex 48%, hippocampus 43%, brainstem 37% and hypothalamus 34%) compared to those of the sedentary control. The brain glycogen levels in all five regions after running were positively correlated with the respective blood and brain glucose levels. Further, in the cortex, the levels of methoxyhydroxyphenylglycol (MHPG) and 5-hydroxyindoleacetic acid (5-HIAA), potential involved in degradation of the brain glycogen, increased during prolonged exercise and negatively correlated with the glycogen levels. These results support the hypothesis that brain glycogen could decrease with prolonged exhaustive exercise. Increased monoamines together with hypoglycaemia should be associated with the development of decreased brain glycogen, suggesting a new clue towards the understanding of central fatigue during prolonged exercise.
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Affiliation(s)
- Takashi Matsui
- Laboratory of Exercise Biochemistry and Neuroendocrinology, University of Tsukuba Graduate School of Comprehensive Human Sciences, Tsukuba, Ibaraki, Japan
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Rasmussen P, Vedel JC, Olesen J, Adser H, Pedersen MV, Hart E, Secher NH, Pilegaard H. In humans IL-6 is released from the brain during and after exercise and paralleled by enhanced IL-6 mRNA expression in the hippocampus of mice. Acta Physiol (Oxf) 2011; 201:475-82. [PMID: 21083649 DOI: 10.1111/j.1748-1716.2010.02223.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
AIM Plasma interleukin-6 (IL-6) increases during exercise by release from active muscles and during prolonged exercise also from the brain. The IL-6 release from muscles continues into recovery and we tested whether the brain also releases IL-6 in recovery from prolonged exercise in humans. Additionally, it was evaluated in mice whether brain release of IL-6 reflected enhanced IL-6 mRNA expression in the brain as modulated by brain glycogen levels. METHODS Nine healthy male subjects completed 4 h of ergometer rowing while the arterio-jugular venous difference (a-v diff) for IL-6 was determined. The IL-6 mRNA and the glycogen content were determined in mouse hippocampus, cerebellum and cortex before and after 2 h treadmill running (N = 8). RESULTS At rest, the IL-6 a-v diff was negligible but decreased to -2.2 ± 1.9 pg ml(-1) at the end of exercise and remained low (-2.1 ± 2.1 pg ml(-1) ) 1 h into the recovery (P < 0.05 vs. rest). IL-6 mRNA was expressed in the three parts of the brain with the lowest content in the hippocampus (P < 0.05) coupled to the highest glycogen content (3.2 ± 0.8 mmol kg(-1) ). Treadmill running increased the hippocampal IL-6 mRNA content 2-3-fold (P < 0.05), while the hippocampal glycogen content decreased to 2.6 ± 0.6 mmol kg(-1) (P < 0.05) with no significant changes in the two other parts of the brain. CONCLUSION Human brain releases IL-6 both during and in recovery from prolonged exercise and mouse data suggest that concurrent changes in IL-6 mRNA and glycogen levels make the hippocampus a likely source of the IL-6 release from the brain.
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Affiliation(s)
- P Rasmussen
- Department of Anesthesia, Department of Biology, University of Copenhagen, Copenhagen, Denmark.
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Zetterling M, Hallberg L, Hillered L, Karlsson T, Enblad P, Ronne Engström E. Brain energy metabolism in patients with spontaneous subarachnoid hemorrhage and global cerebral edema. Neurosurgery 2010; 66:1102-10. [PMID: 20495425 DOI: 10.1227/01.neu.0000370893.04586.73] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Previous studies of spontaneous subarachnoid hemorrhage (SAH) have shown that global cerebral edema on the first computed tomography scan is associated with a more severe initial injury and is an independent predictor of poor outcome. Effects of secondary ischemic events also influence outcome after SAH. OBJECTIVE This study demonstrates that early global edema is related to markers of an increased cerebral energy metabolism as measured with intracerebral microdialysis, which could increase vulnerability to adverse events. METHODS Fifty-two patients with microdialysis monitoring after spontaneous SAH were stratified according to the occurrence of global cerebral edema on the first computed tomography scan taken a median of 2 hours after the initial bleed. Microdialysis levels of glucose, lactate, and pyruvate were compared between the global edema (n = 31) and no global edema (n = 21) groups. Clinical outcome was assessed with the Glasgow Outcome Scale score at >/= 6 months. RESULTS Patients with global edema showed significantly elevated lactate and pyruvate levels 70 to 79 hours after SAH and marginally significantly higher levels of lactate 60 to 69 hours and 80 to 89 hours after SAH. There was a trend toward worse outcome in the edema group. CONCLUSION Patients with global cerebral edema have higher interstitial levels of lactate and pyruvate. The edema group may have developed a cerebral hypermetabolism to meet the increased energy demand in the recovery phase after SAH. This stress would make the brain more vulnerable to secondary insults, increasing the likelihood of energy failure.
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Affiliation(s)
- Maria Zetterling
- Department of Neuroscience, Neurosurgery, Uppsala University Hospital, Uppsala, Sweden.
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Mental health response to acute stress following wilderness disaster. Wilderness Environ Med 2010; 21:337-44. [PMID: 21168787 DOI: 10.1016/j.wem.2010.06.011] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2010] [Revised: 06/11/2010] [Accepted: 06/15/2010] [Indexed: 11/23/2022]
Abstract
Expedition physicians should be prepared to respond to traumatic stress disorders following wilderness disasters. Stress disorder symptoms include re-experiencing the traumatic event, avoiding stimuli associated with the traumatic event, and increased physical arousal. These symptoms can also be seen in healthy individuals, and should only lead to disorder diagnosis when they cause distress or impairment. Treatment options for stress disorders include observation, psychological interventions, and medication. Approximately half of those with diagnosable stress disorders will return to nondiagnosable status over time without therapeutic intervention. Psychological interventions with empirical support concentrate on providing either noninvasive support in the short term, such as psychological first aid (PFA), or more long-term controlled re-experiencing of the precipitating trauma, such as many exposure-based therapies. Exposure-based treatments can result in temporary increases in symptoms before long-term gains are realized, so they are not recommended for wilderness settings. Medications to treat stress disorders include benzodiazepines, propranolol, and antidepressant medications. Benzodiazepines are often carried in wilderness first aid kits, but they provide very limited stress disorder symptom relief. Propranolol is being explored as a method of preventing traumatic stress disorders, but the data are not currently conclusive. Antidepressant medications are a good long-term strategy for stress disorder treatment, but they are of limited utility in wilderness settings as they are unlikely to be included in expedition medical kits and require approximately 4 weeks of administration for symptom reduction. Recommendations for wilderness treatment of stress disorders focus on increasing knowledge of stress disorder diagnosis and PFA.
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Seifert T, Fisher JP, Young CN, Hartwich D, Ogoh S, Raven PB, Fadel PJ, Secher NH. Experimental Physiology -Research Paper: Glycopyrrolate abolishes the exercise-induced increase in cerebral perfusion in humans. Exp Physiol 2010; 95:1016-25. [DOI: 10.1113/expphysiol.2010.054346] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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Rasmussen P, Foged EM, Krogh-Madsen R, Nielsen J, Nielsen TR, Olsen NV, Petersen NC, Sørensen TA, Secher NH, Lundby C. Effects of erythropoietin administration on cerebral metabolism and exercise capacity in men. J Appl Physiol (1985) 2010; 109:476-83. [DOI: 10.1152/japplphysiol.00234.2010] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Recombinant human erythropoietin (EPO) increases exercise capacity by stimulating erythropoiesis and subsequently enhancing oxygen delivery to the working muscles. In a large dose, EPO crosses the BBB and may reduce central fatigue and improve cognition. In turn, this would augment exercise capacity independent of erythropoiesis. To test this hypothesis, 15 healthy young men (18–34 years old, 74 ± 7 kg) received either 3 days of high-dose (30,000 IU/day; n = 7) double-blinded placebo controlled or 3 mo of low-dose (5,000 IU/wk; n = 8) counter-balanced open but controlled administration of EPO. We recorded exercise capacity, transcranial ultrasonography-derived middle cerebral artery blood velocity, and arterial-internal jugular venous concentration differences of glucose and lactate. In addition, cognitive function, ratings of perceived exertion, ventilation, and voluntary activation by transcranial magnetic stimulation-induced twitch force were evaluated. Although EPO in a high dose increased cerebrospinal fluid EPO concentration ∼20-fold and affected ventilation and cerebral glucose and lactate metabolism ( P < 0.05), 3 days of high-dose EPO administration had no effect on cognition, voluntary activation, or exercise capacity, but ratings of perceived exertion increased ( P < 0.05). We confirmed that 3 mo of administration of EPO increases exercise capacity, but the improvement could not be accounted for by other mechanisms than enhanced oxygen delivery. In conclusion, EPO does not attenuate central fatigue or change cognitive performance strategy, suggesting that EPO enhances exercise capacity exclusively by increased oxygen delivery to the working muscles.
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Affiliation(s)
- P. Rasmussen
- Departments of 1Anesthesia, and
- Copenhagen Muscle Research Centre, and
- Zurich Centre for Integrative Human Physiology, University of Zurich, Zurich, Switzerland
| | | | - R. Krogh-Madsen
- Infectious Diseases,
- Centre of Inflammation and Metabolism, Rigshospitalet, Copenhagen
| | | | | | - N. V. Olsen
- Departments of 1Anesthesia, and
- Neuroscience and Pharmacology, and
| | - N. C. Petersen
- Exercise Sciences, University of Copenhagen, Denmark; and
| | | | - N. H. Secher
- Departments of 1Anesthesia, and
- Copenhagen Muscle Research Centre, and
| | - C. Lundby
- Copenhagen Muscle Research Centre, and
- Zurich Centre for Integrative Human Physiology, University of Zurich, Zurich, Switzerland
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Brassard P, Seifert T, Wissenberg M, Jensen PM, Hansen CK, Secher NH. Phenylephrine decreases frontal lobe oxygenation at rest but not during moderately intense exercise. J Appl Physiol (1985) 2010; 108:1472-8. [DOI: 10.1152/japplphysiol.01206.2009] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Whether sympathetic activity influences cerebral blood flow (CBF) and oxygenation remains controversial. The influence of sympathetic activity on CBF and oxygenation was evaluated by the effect of phenylephrine on middle cerebral artery (MCA) mean flow velocity ( Vmean) and the near-infrared spectroscopy-derived frontal lobe oxygenation (ScO2) at rest and during exercise. At rest, nine healthy male subjects received bolus injections of phenylephrine (0.1, 0.25, and 0.4 mg), and changes in mean arterial pressure (MAP), MCA Vmean, internal jugular venous O2 saturation (SjvO2), ScO2, and arterial Pco2 (PaCO2) were measured and the cerebral metabolic rate for O2 (CMRO2) was calculated. In randomized order, a bolus of saline or 0.3 mg of phenylephrine was then injected during semisupine cycling, eliciting a low (∼110 beats/min) or a high (∼150 beats/min) heart rate. At rest, MAP and MCA Vmean increased ∼20% ( P < 0.001) and ∼10% ( P < 0.001 for 0.25 mg of phenylephrine and P < 0.05 for 0.4 mg of phenylephrine), respectively. ScO2 then decreased ∼7% ( P < 0.001). Phenylephrine had no effect on SjvO2, PaCO2, or CMRO2. MAP increased after the administration of phenylephrine during low-intensity exercise (∼15%), but this was attenuated (∼10%) during high-intensity exercise ( P < 0.001). The reduction in ScO2 after administration of phenylephrine was attenuated during low-intensity exercise (−5%, P < 0.001) and abolished during high-intensity exercise (−3%, P = not significant), where PaCO2 decreased 7% ( P < 0.05) and CMRO2 increased 17% ( P < 0.05). These results suggest that the administration of phenylephrine reduced ScO2 but that the increased cerebral metabolism needed for moderately intense exercise eliminated that effect.
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Affiliation(s)
- Patrice Brassard
- Department of Anesthesia, The Copenhagen Muscle Research Center, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - Thomas Seifert
- Department of Anesthesia, The Copenhagen Muscle Research Center, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - Mads Wissenberg
- Department of Anesthesia, The Copenhagen Muscle Research Center, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - Peter M. Jensen
- Department of Anesthesia, The Copenhagen Muscle Research Center, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - Christian K. Hansen
- Department of Anesthesia, The Copenhagen Muscle Research Center, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - Niels H. Secher
- Department of Anesthesia, The Copenhagen Muscle Research Center, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
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41
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Rasmussen P, Nielsen J, Overgaard M, Krogh-Madsen R, Gjedde A, Secher NH, Petersen NC. Reduced muscle activation during exercise related to brain oxygenation and metabolism in humans. J Physiol 2010; 588:1985-95. [PMID: 20403976 DOI: 10.1113/jphysiol.2009.186767] [Citation(s) in RCA: 131] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Maximal exercise may be limited by central fatigue defined as an inability of the central nervous system to fully recruit the involved muscles. This study evaluated whether a reduction in the cerebral oxygen-to-carbohydrate index (OCI) and in the cerebral mitochondrial oxygen tension relate to the ability to generate a maximal voluntary contraction and to the transcranial magnetic stimulated force generation. To determine the role of a reduced OCI and in central fatigue, 16 males performed low intensity, maximal intensity and hypoxic cycling exercise. Exercise fatigue was evaluated by ratings of perceived exertion (RPE), arm maximal voluntary force (MVC), and voluntary activation of elbow flexor muscles assessed with transcranial magnetic stimulation. Low intensity exercise did not produce any indication of central fatigue or marked cerebral metabolic deviations. Exercise in hypoxia (0.10) reduced cerebral oxygen delivery 25% and decreased 11+/-4 mmHg (P<0.001) together with OCI (6.2+/-0.7 to 4.8+/-0.5, P<0.001). RPE increased while MVC and voluntary activation were reduced (P<0.05). During maximal exercise declined 8+/-4 mmHg (P<0.05) and OCI to 3.8+/-0.5 (P<0.001). RPE was 18.5, and MVC and voluntary activation were reduced (P<0.05). We observed no signs of muscular fatigue in the elbow flexors and all control MVCs were similar to resting values. Exhaustive exercise provoked cerebral deoxygenation, metabolic changes and indices of fatigue similar to those observed during exercise in hypoxia indicating that reduced cerebral oxygenation may play a role in the development of central fatigue and may be an exercise capacity limiting factor.
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Affiliation(s)
- P Rasmussen
- Department of Anaesthesia, The Copenhagen Muscle Research Centre, Rigshospitalet, University of Copenhagen, AN2041, Blegdamsvej 9, DK2100 Copenhagen, Denmark.
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Nissen P, Brassard P, Jørgensen TB, Secher NH. Phenylephrine but not ephedrine reduces frontal lobe oxygenation following anesthesia-induced hypotension. Neurocrit Care 2009; 12:17-23. [PMID: 19957053 DOI: 10.1007/s12028-009-9313-x] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
BACKGROUND Vasopressor agents are used to correct anesthesia-induced hypotension. We describe the effect of phenylephrine and ephedrine on frontal lobe oxygenation (S(c)O(2)) following anesthesia-induced hypotension. METHODS Following induction of anesthesia by fentanyl (0.15 mg kg(-1)) and propofol (2.0 mg kg(-1)), 13 patients received phenylephrine (0.1 mg iv) and 12 patients received ephedrine (10 mg iv) to restore mean arterial pressure (MAP). Heart rate (HR), MAP, stroke volume (SV), cardiac output (CO), and frontal lobe oxygenation (S(c)O(2)) were registered. RESULTS Induction of anesthesia was followed by a decrease in MAP, HR, SV, and CO concomitant with an elevation in S(c)O(2). After administration of phenylephrine, MAP increased (51 +/- 12 to 81 +/- 13 mmHg; P < 0.001; mean +/- SD). However, a 14% (from 70 +/- 8% to 60 +/- 7%) reduction in S(c)O(2) (P < 0.05) followed with no change in CO (3.7 +/- 1.1 to 3.4 +/- 0.9 l min(-1)). The administration of ephedrine led to a similar increase in MAP (53 +/- 9 to 79 +/- 8 mmHg; P < 0.001), restored CO (3.2 +/- 1.2 to 5.0 +/- 1.3 l min(-1)), and preserved S(c)O(2). CONCLUSIONS The utilization of phenylephrine to correct hypotension induced by anesthesia has a negative impact on S(c)O(2) while ephedrine maintains frontal lobe oxygenation potentially related to an increase in CO.
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Affiliation(s)
- Peter Nissen
- Department of Anesthesia, Rigshospitalet 2041, University of Copenhagen, Blegdamsvej 9, 2100, Copenhagen Ø, Denmark.
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Gam CMB, Rasmussen P, Secher NH, Seifert T, Larsen FS, Nielsen HB. Maintained cerebral metabolic ratio during exercise in patients with β-adrenergic blockade. Clin Physiol Funct Imaging 2009; 29:420-6. [DOI: 10.1111/j.1475-097x.2009.00889.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Gallagher CN, Carpenter KLH, Grice P, Howe DJ, Mason A, Timofeev I, Menon DK, Kirkpatrick PJ, Pickard JD, Sutherland GR, Hutchinson PJ. The human brain utilizes lactate via the tricarboxylic acid cycle: a 13C-labelled microdialysis and high-resolution nuclear magnetic resonance study. ACTA ACUST UNITED AC 2009; 132:2839-49. [PMID: 19700417 DOI: 10.1093/brain/awp202] [Citation(s) in RCA: 155] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
Energy metabolism in the human brain is not fully understood. Classically, glucose is regarded as the major energy substrate. However, lactate (conventionally a product of anaerobic metabolism) has been proposed to act as an energy source, yet whether this occurs in man is not known. Here we show that the human brain can indeed utilize lactate as an energy source via the tricarboxylic acid cycle. We used a novel combination of (13)C-labelled cerebral microdialysis both to deliver (13)C substrates into the brain and recover (13)C metabolites from the brain, and high-resolution (13)C nuclear magnetic resonance. Microdialysis catheters were placed in the vicinity of focal lesions and in relatively less injured regions of brain, in patients with traumatic brain injury. Infusion with 2-(13)C-acetate or 3-(13)C-lactate produced (13)C signals for glutamine C4, C3 and C2, indicating tricarboxylic acid cycle operation followed by conversion of glutamate to glutamine. This is the first direct demonstration of brain utilization of lactate as an energy source in humans.
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Affiliation(s)
- Clare N Gallagher
- Division of Neurosurgery, Department of Clinical Neurosciences, University of Cambridge, Addenbrooke's Hospital, Hills Road, Cambridge, UK
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Seifert T, Rasmussen P, Brassard P, Homann PH, Wissenberg M, Nordby P, Stallknecht B, Secher NH, Nielsen HB. Cerebral oxygenation and metabolism during exercise following three months of endurance training in healthy overweight males. Am J Physiol Regul Integr Comp Physiol 2009; 297:R867-76. [PMID: 19605762 DOI: 10.1152/ajpregu.00277.2009] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Endurance training improves muscular and cardiovascular fitness, but the effect on cerebral oxygenation and metabolism remains unknown. We hypothesized that 3 mo of endurance training would reduce cerebral carbohydrate uptake with maintained cerebral oxygenation during submaximal exercise. Healthy overweight males were included in a randomized, controlled study (training: n = 10; control: n = 7). Arterial and internal jugular venous catheterization was used to determine concentration differences for oxygen, glucose, and lactate across the brain and the oxygen-carbohydrate index [molar uptake of oxygen/(glucose + (1/2) lactate); OCI], changes in mitochondrial oxygen tension (DeltaP(Mito)O(2)) and the cerebral metabolic rate of oxygen (CMRO(2)) were calculated. For all subjects, resting OCI was higher at the 3-mo follow-up (6.3 +/- 1.3 compared with 4.7 +/- 0.9 at baseline, mean +/- SD; P < 0.05) and coincided with a lower plasma epinephrine concentration (P < 0.05). Cerebral adaptations to endurance training manifested when exercising at 70% of maximal oxygen uptake (approximately 211 W). Before training, both OCI (3.9 +/- 0.9) and DeltaP(Mito)O(2) (-22 mmHg) decreased (P < 0.05), whereas CMRO(2) increased by 79 +/- 53 micromol x 100 x g(-1) min(-1) (P < 0.05). At the 3-mo follow-up, OCI (4.9 +/- 1.0) and DeltaP(Mito)O(2) (-7 +/- 13 mmHg) did not decrease significantly from rest and when compared with values before training (P < 0.05), CMRO(2) did not increase. This study demonstrates that endurance training attenuates the cerebral metabolic response to submaximal exercise, as reflected in a lower carbohydrate uptake and maintained cerebral oxygenation.
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Affiliation(s)
- T Seifert
- Department of Anesthesia, Section of Systems Biology Research, The Copenhagen Muscle Research Center, University of Copenhagen, Copenhagen, Denmark.
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46
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Affiliation(s)
- S Perrey
- Motor Efficiency and Deficiency Laboratory, EA 2991, UFR STAPS, University of Montpellier 1, Montpellier, France.
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Hertz L, Gibbs ME. What learning in day-old chickens can teach a neurochemist: focus on astrocyte metabolism. J Neurochem 2009; 109 Suppl 1:10-6. [PMID: 19393003 DOI: 10.1111/j.1471-4159.2009.05939.x] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
The learning process sets in motion a prolonged, reproducible, and complicated pattern of brain activation, which provides information about biochemical reactions in activated brain. Study of this pattern during one-trial aversive bead discrimination in day-old chick is facilitated by precise timing of sequential metabolic events occurring between a 10-s learning period, in which the chicks learn to associate a red bead with aversive taste, and memory consolidation, indicated by unwillingness to peck at untainted red beads while freely pecking at corresponding blue beads. Inhibition of learning by metabolic inhibitors and restoration of memory by specific substrates at specific times allow determination of specific metabolic events and their neuronal or astrocytic localization. Downstream metabolism of glycogen and of glucose to pyruvate/lactate is segregated into separate pools. Glucose metabolism via pyruvate dehydrogenation provides energy in both neurons and astrocytes and may include gap junction-mediated lactate transport into astrocytes. A key role is played by glycogenolysis, stimulated by beta2-adrenergic and/or 5-HT2-receptor stimulation along with alpha2-adrenergic stimulation of glycogen synthesis. The importance of glycogen reflects that it selectively supports de novo synthesis of transmitter glutamate by combined pyruvate dehydrogenation and carboxylation in astrocytes.
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Affiliation(s)
- Leif Hertz
- College of Basic Medical Sciences, China Medical University, Shenyang, China.
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Marcora SM, Staiano W, Manning V. Mental fatigue impairs physical performance in humans. J Appl Physiol (1985) 2009; 106:857-64. [PMID: 19131473 DOI: 10.1152/japplphysiol.91324.2008] [Citation(s) in RCA: 650] [Impact Index Per Article: 43.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Mental fatigue is a psychobiological state caused by prolonged periods of demanding cognitive activity. Although the impact of mental fatigue on cognitive and skilled performance is well known, its effect on physical performance has not been thoroughly investigated. In this randomized crossover study, 16 subjects cycled to exhaustion at 80% of their peak power output after 90 min of a demanding cognitive task (mental fatigue) or 90 min of watching emotionally neutral documentaries (control). After experimental treatment, a mood questionnaire revealed a state of mental fatigue (P = 0.005) that significantly reduced time to exhaustion (640 +/- 316 s) compared with the control condition (754 +/- 339 s) (P = 0.003). This negative effect was not mediated by cardiorespiratory and musculoenergetic factors as physiological responses to intense exercise remained largely unaffected. Self-reported success and intrinsic motivation related to the physical task were also unaffected by prior cognitive activity. However, mentally fatigued subjects rated perception of effort during exercise to be significantly higher compared with the control condition (P = 0.007). As ratings of perceived exertion increased similarly over time in both conditions (P < 0.001), mentally fatigued subjects reached their maximal level of perceived exertion and disengaged from the physical task earlier than in the control condition. In conclusion, our study provides experimental evidence that mental fatigue limits exercise tolerance in humans through higher perception of effort rather than cardiorespiratory and musculoenergetic mechanisms. Future research in this area should investigate the common neurocognitive resources shared by physical and mental activity.
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Affiliation(s)
- Samuele M Marcora
- School of Sport, Health and Exercise Sciences, Bangor University, Bangor, Wales, United Kingdom.
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Glenn T. Non-oxidative cerebral carbohydrate metabolism. J Physiol 2009; 587:9. [DOI: 10.1113/jphysiol.2008.166876] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
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Seifert TS, Brassard P, Jørgensen TB, Hamada AJ, Rasmussen P, Quistorff B, Secher NH, Nielsen HB. Cerebral non-oxidative carbohydrate consumption in humans driven by adrenaline. J Physiol 2008; 587:285-93. [PMID: 19015195 DOI: 10.1113/jphysiol.2008.162073] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
During brain activation, the decrease in the ratio between cerebral oxygen and carbohydrate uptake (6 O(2)/(glucose + (1)/(2) lactate); the oxygen-carbohydrate index, OCI) is attenuated by the non-selective beta-adrenergic receptor antagonist propranolol, whereas OCI remains unaffected by the beta(1)-adrenergic receptor antagonist metroprolol. These observations suggest involvement of a beta(2)-adrenergic mechanism in non-oxidative metabolism for the brain. Therefore, we evaluated the effect of adrenaline (0.08 microg kg(-1) min(-1) i.v. for 15 min) and noradrenaline (0.5, 0.1 and 0.15 microg kg(-1) min(-1) i.v. for 20 min) on the arterial to internal jugular venous concentration differences (a-v diff) of O(2), glucose and lactate in healthy humans. Adrenaline (n = 10) increased the arterial concentrations of O(2), glucose and lactate (P < 0.05) and also increased the a-v diff for glucose from 0.6 +/- 0.1 to 0.8 +/- 0.2 mM (mean +/- s.d.; P < 0.05). The a-v diff for lactate shifted from a net cerebral release to an uptake and OCI was lowered from 5.1 +/- 1.5 to 3.6 +/- 0.4 (P < 0.05) indicating an 8-fold increase in the rate of non-oxidative carbohydrate uptake during adrenaline infusion (P < 0.01). Conversely, noradrenaline (n = 8) did not affect the OCI despite an increase in the a-v diff for glucose (P < 0.05). These results support that non-oxidative carbohydrate consumption for the brain is driven by a beta(2)-adrenergic mechanism, giving neurons an abundant provision of energy when plasma adrenaline increases.
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Affiliation(s)
- Thomas S Seifert
- Department of Anaesthesia, The Copenhagen Muscle Research Centre, Rigshospitalet, Faculty of Health Sciences, University of Copenhagen, Denmark.
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