1
|
Li X, Shen Y, Li D, Zhang K, Liu J, Yao L, Yang J, Qian J. PEG300 Protects Mitochondrial Function By Upregulating PGC-1α to Delay Central Nervous System Oxygen Toxicity in Mice. Neurotox Res 2024; 42:30. [PMID: 38884699 DOI: 10.1007/s12640-024-00708-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2023] [Revised: 04/04/2024] [Accepted: 06/01/2024] [Indexed: 06/18/2024]
Abstract
Central nervous system oxygen toxicity (CNS-OT) is a complication of hyperbaric oxygen (HBO) treatment, with limited prevention and treatment options available. In this study, we aimed to explore the effect of polyethylene glycol 300 (PEG300) on CNS-OT and underlying mechanisms. Motor and cognitive functions of mice in normobaric conditions were evaluated by Morris water maze, passive active avoidance, and rotarod tests. HBO was applied at 6 atmospheres absolute (ATA) for 30 min after drug administration. The latency period of convulsion in mice was recorded, and hippocampal tissues were extracted for biochemical experiments. Our experimental results showed that PEG300 extended the convulsion latencies in CNS-OT mice, reduced oxidative stress and inflammation levels in hippocampal tissues. Furthermore, PEG300 preserved mitochondrial integrity and maintained mitochondrial membrane potential in hippocampal tissue by upregulating Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha (PGC-1α). This protective effect was enhanced following the administration of ZLN005, an agonist of PGC-1a. Hence, our study suggests that PEG300 might exert protective effects by upregulating PGC-1α expression and preserving mitochondrial health, offering promising prospects for CNS-OT treatment.
Collapse
Affiliation(s)
- Xin Li
- Department of Pharmacy, The First Affiliated Hospital (Changhai Hospital), Naval Medical University, Shanghai, China
| | - Yue Shen
- Department of Pharmacy, The First Affiliated Hospital (Changhai Hospital), Naval Medical University, Shanghai, China
| | - Dan Li
- Naval Medical University, Shanghai, China
| | - Kun Zhang
- Department of Diving and Hyperbaric Medicine, Naval Special Medicine Center, Naval Medical University, Shanghai, China
| | - Jia Liu
- Department of Dermatology, The First Affiliated Hospital (Changhai Hospital), Naval Medical University, Shanghai, China
| | - Lu Yao
- Department of Obstetrics and Gynecology, People's Hospital of Rugao City, Rugao, China
| | - Jun Yang
- Department of Orthopedics, The Second Affiliated Hospital (Changzheng Hospital), Naval Medical University, Shanghai, China.
| | - Jiao Qian
- Department of Pharmacy, The First Affiliated Hospital (Changhai Hospital), Naval Medical University, Shanghai, China.
| |
Collapse
|
2
|
Hencz AJ, Magony A, Thomas C, Kovacs K, Szilagyi G, Pal J, Sik A. Short-term hyperoxia-induced functional and morphological changes in rat hippocampus. Front Cell Neurosci 2024; 18:1376577. [PMID: 38686017 PMCID: PMC11057248 DOI: 10.3389/fncel.2024.1376577] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2024] [Accepted: 03/27/2024] [Indexed: 05/02/2024] Open
Abstract
Excess oxygen (O2) levels may have a stimulating effect, but in the long term, and at high concentrations of O2, it is harmful to the nervous system. The hippocampus is very sensitive to pathophysiological changes and altered O2 concentrations can interfere with hippocampus-dependent learning and memory functions. In this study, we investigated the hyperoxia-induced changes in the rat hippocampus to evaluate the short-term effect of mild and severe hyperoxia. Wistar male rats were randomly divided into control (21% O2), mild hyperoxia (30% O2), and severe hyperoxia groups (100% O2). The O2 exposure lasted for 60 min. Multi-channel silicon probes were used to study network oscillations and firing properties of hippocampal putative inhibitory and excitatory neurons. Neural damage was assessed using the Gallyas silver impregnation method. Mild hyperoxia (30% O2) led to the formation of moderate numbers of silver-impregnated "dark" neurons in the hippocampus. On the other hand, exposure to 100% O2 was associated with a significant increase in the number of "dark" neurons located mostly in the hilus. The peak frequency of the delta oscillation decreased significantly in both mild and severe hyperoxia in urethane anesthetized rats. Compared to normoxia, the firing activity of pyramidal neurons under hyperoxia increased while it was more heterogeneous in putative interneurons in the cornu ammonis area 1 (CA1) and area 3 (CA3). These results indicate that short-term hyperoxia can change the firing properties of hippocampal neurons and network oscillations and damage neurons. Therefore, the use of elevated O2 concentration inhalation in hospitals (i.e., COVID treatment and surgery) and in various non-medical scenarios (i.e., airplane emergency O2 masks, fire-fighters, and high altitude trekkers) must be used with extreme caution.
Collapse
Affiliation(s)
| | - Andor Magony
- Institute of Physiology, Medical School, University of Pécs, Pécs, Hungary
| | - Chloe Thomas
- Institute of Clinical Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, United Kingdom
| | - Krisztina Kovacs
- Institute of Clinical Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, United Kingdom
| | - Gabor Szilagyi
- Institute of Biochemistry and Medical Chemistry, Medical School, University of Pécs, Pécs, Hungary
| | - Jozsef Pal
- Institute of Physiology, Medical School, University of Pécs, Pécs, Hungary
| | - Attila Sik
- Institute of Physiology, Medical School, University of Pécs, Pécs, Hungary
- Institute of Clinical Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, United Kingdom
| |
Collapse
|
3
|
Simon Machado R, Mathias K, Joaquim L, de Quadros RW, Rezin GT, Petronilho F. Hyperoxia and brain: the link between necessity and injury from a molecular perspective. Neurotox Res 2024; 42:25. [PMID: 38619632 DOI: 10.1007/s12640-024-00702-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2023] [Revised: 11/15/2023] [Accepted: 03/25/2024] [Indexed: 04/16/2024]
Abstract
Oxygen (O2) supplementation is commonly used to treat hypoxia in patients with respiratory failure. However, indiscriminate use can lead to hyperoxia, a condition detrimental to living tissues, particularly the brain. The brain is sensitive to reactive oxygen species (ROS) and inflammation caused by high concentrations of O2, which can result in brain damage and mitochondrial dysfunction, common features of neurodegenerative disorders. Hyperoxia leads to increased production of ROS, causing oxidative stress, an imbalance between oxidants and antioxidants, which can damage tissues. The brain is particularly vulnerable to oxidative stress due to its lipid composition, high O2 consumption rate, and low levels of antioxidant enzymes. Moreover, hyperoxia can cause vasoconstriction and decreased O2 supply to the brain, posing a challenge to redox balance and neurodegenerative processes. Studies have shown that the severity of hyperoxia-induced brain damage varies with inspired O2 concentration and duration of exposure. Therefore, careful evaluation of the balance between benefits and risks of O2 supplementation, especially in clinical settings, is crucial.
Collapse
Affiliation(s)
- Richard Simon Machado
- Laboratory of Experimental Neurology, Graduate Program in Health Sciences, Health Sciences Unit, University of Southern Santa Catarina, Criciuma, SC, Brazil.
- Laboratory of Neurobiology of Inflammatory and Metabolic Processes, Graduate Program in Health Sciences, Health Sciences Unit, University of South Santa Catarina, Tubarão, SC, Brazil.
| | - Khiany Mathias
- Laboratory of Experimental Neurology, Graduate Program in Health Sciences, Health Sciences Unit, University of Southern Santa Catarina, Criciuma, SC, Brazil
| | - Larissa Joaquim
- Laboratory of Experimental Neurology, Graduate Program in Health Sciences, Health Sciences Unit, University of Southern Santa Catarina, Criciuma, SC, Brazil
| | | | - Gislaine Tezza Rezin
- Laboratory of Neurobiology of Inflammatory and Metabolic Processes, Graduate Program in Health Sciences, Health Sciences Unit, University of South Santa Catarina, Tubarão, SC, Brazil
| | - Fabricia Petronilho
- Laboratory of Experimental Neurology, Graduate Program in Health Sciences, Health Sciences Unit, University of Southern Santa Catarina, Criciuma, SC, Brazil
| |
Collapse
|
4
|
Rabinovitz R, Eynan M. CNS-oxygen toxicity and blood glucose levels in MnSOD enzyme knockdown mice. Respir Physiol Neurobiol 2023; 316:104122. [PMID: 37481014 DOI: 10.1016/j.resp.2023.104122] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2023] [Revised: 07/04/2023] [Accepted: 07/18/2023] [Indexed: 07/24/2023]
Abstract
Many studies have been conducted in the search for the mechanism underlying CNS-oxygen toxicity (OT), which may be fatal when diving with a closed-circuit apparatus. We investigated the influence of hyperbaric oxygen (HBO) on blood glucose level (BGL) in Mn-superoxide dismutase (SOD2) knockdown mice regarding CNS-OT in particular under stress conditions such as hypoglycemia or hyperglycemia. Two groups of mice were used: SOD2 knockdown (Heterozygous, HET) mice and their WT family littermates. Animals were exposed to HBO from 2 up to 5 atmosphere absolute (ATA). Blood samples were drawn before and after each exposure for measurement of BGL. The mice were sacrificed following the final exposure, which was at 5 ATA. We used RT-PCR and Western blot to measure levels of glucose transporter 1 (GLUT1) and hypoxia inducible factor (HIF)1a in the cortex and hippocampus. In the hypoglycemic condition, the HET mice were more sensitive to oxidative stress than the WT. In addition, following exposure to sub-toxic HBO, which does not induce CNS-OT, BGL were higher in the HET mice compared with the WT. The expression of mRNA of GLUT1 and HIF-1a decreased in the hippocampus in the HET mice, while the protein level decreased in the HET and WT following HBO exposure. The results suggest that the higher BGL following HBO exposure especially at SOD2 HET mice is in part due to reduction in GLUT1 as a consequence of lower HIF-1a expression. This may add part to the puzzle of the understanding the mechanism leading to CNS-OT.
Collapse
Affiliation(s)
- Ricarina Rabinovitz
- Israel Naval Medical Institute, Israel Defense Forces Medical Corps, Haifa, Israel
| | - Mirit Eynan
- Israel Naval Medical Institute, Israel Defense Forces Medical Corps, Haifa, Israel.
| |
Collapse
|
5
|
Wang W, Wang X, Tao F, Hu K, Zhang J, Wu J, You L, Zhao W. Fluorinated Hyaluronic Acid Encapsulated Perfluorocarbon Nanoparticles as Tumor-Targeted Oxygen Carriers to Enhance Radiotherapy. Mol Pharm 2022; 19:3948-3958. [PMID: 36194775 DOI: 10.1021/acs.molpharmaceut.2c00432] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The efficacy of radiotherapy is significantly constricted by tumor hypoxia. To overcome this obstacle, one promising approach is to use the perfluorocarbon-based O2 carriers combined with hyperoxic respiration to relieve tumor hypoxia. However, this passively transported oxygen carrier during hyperoxic respiration is prone to cause systemic oxidative stress and toxicity, which further limits its clinical application. Herein, we fabricate O2@PFC@FHA NPs for safe and specific oxygen delivery into tumors by using the fluorinated hyaluronic acid to encapsulate O2-saturated perfluorocarbon. Due to the interaction between HA and CD44 receptors, more FHA@PFC NPs accumulated in the tumor and the O2@PFC@FHA NPs significantly relieved tumor hypoxia. Notably, RT plus O2@PFC@FHA NPs resulted in almost threefold therapeutic improvement compared with RT without obvious systemic toxicity. Therefore, the O2@FHA@PFC NPs may have great potential to enhance the therapeutic efficacy of radiotherapy in the clinic.
Collapse
Affiliation(s)
- Wenguang Wang
- Vaccine Center, School of Basic Medicine and Clinical Pharmacy, China Pharmaceutical University, Nanjing 211198, China.,Center for New Drug Safety Evaluation and Research, China Pharmaceutical University, Nanjing 211198, China
| | - Xingli Wang
- School of Traditional Chinese Pharmacy, China Pharmaceutical University, Nanjing 211198, China
| | - Feng Tao
- State Key Laboratory of Pharmaceutical Biotechnology, Medical School of Nanjing University & School of Life Sciences, Nanjing University, Nanjing 210093, China
| | - Kaiyuan Hu
- Vaccine Center, School of Basic Medicine and Clinical Pharmacy, China Pharmaceutical University, Nanjing 211198, China.,Center for New Drug Safety Evaluation and Research, China Pharmaceutical University, Nanjing 211198, China
| | - Junying Zhang
- School of Traditional Chinese Pharmacy, China Pharmaceutical University, Nanjing 211198, China
| | - Jinhui Wu
- State Key Laboratory of Pharmaceutical Biotechnology, Medical School of Nanjing University & School of Life Sciences, Nanjing University, Nanjing 210093, China.,Jiangsu Provincial Key Laboratory for Nano Technology, Nanjing University, Nanjing 210093, China
| | - Linjun You
- Center for New Drug Safety Evaluation and Research, China Pharmaceutical University, Nanjing 211198, China
| | - Weijun Zhao
- Vaccine Center, School of Basic Medicine and Clinical Pharmacy, China Pharmaceutical University, Nanjing 211198, China.,Center for New Drug Safety Evaluation and Research, China Pharmaceutical University, Nanjing 211198, China
| |
Collapse
|
6
|
Machado RS, Tenfen L, Joaquim L, Lanzzarin EVR, Bernardes GC, Bonfante SR, Mathias K, Biehl E, Bagio É, Stork SDS, Denicol T, de Oliveira MP, da Silva MR, Danielski LG, de Quadros RW, Rezin GT, Terra SR, Balsini JN, Gava FF, Petronilho F. Hyperoxia by short-term promotes oxidative damage and mitochondrial dysfunction in rat brain. Respir Physiol Neurobiol 2022; 306:103963. [PMID: 36041716 DOI: 10.1016/j.resp.2022.103963] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2022] [Revised: 07/29/2022] [Accepted: 08/21/2022] [Indexed: 11/17/2022]
Abstract
Oxygen (O2) therapy is used as a therapeutic protocol to prevent or treat hypoxia. However, a high inspired fraction of O2 (FIO2) promotes hyperoxia, a harmful condition for the central nervous system (CNS). The present study evaluated parameters of oxidative stress and mitochondrial dysfunction in the brain of rats exposed to different FIO2. Male Wistar rats were exposed to hyperoxia (FIO2 40 % and 60 %) compared to the control group (FIO2 21 %) for 2 h. Oxidative stress, neutrophilic infiltration, and mitochondrial respiratory chain enzymes were determined in the hippocampus, striatum, cerebellum, cortex, and prefrontal cortex after O2 exposure. The animals exposed to hyperoxia showed increased lipid peroxidation, formation of carbonyl proteins, N/N concentration, and neutrophilic infiltration in some brain regions, like hippocampus, striatum, and cerebellum being the most affected. Furthermore, CAT activity and activity of mitochondrial enzyme complexes were also altered after exposure to hyperoxia. Rats exposed to hyperoxia showed increase in oxidative stress parameters and mitochondrial dysfunction in brain structures.
Collapse
Affiliation(s)
- Richard Simon Machado
- Laboratory of Neurobiology of Inflammatory and Metabolic Processes, Graduate Program in Health Sciences, Health Sciences Unit, University of South Santa Catarina, Tubarão, SC, Brazil
| | - Leonardo Tenfen
- Laboratory of Neurobiology of Inflammatory and Metabolic Processes, Graduate Program in Health Sciences, Health Sciences Unit, University of South Santa Catarina, Tubarão, SC, Brazil
| | - Larissa Joaquim
- Laboratory of Neurobiology of Inflammatory and Metabolic Processes, Graduate Program in Health Sciences, Health Sciences Unit, University of South Santa Catarina, Tubarão, SC, Brazil
| | - Everton Venicius Rosa Lanzzarin
- Laboratory of Neurobiology of Inflammatory and Metabolic Processes, Graduate Program in Health Sciences, Health Sciences Unit, University of South Santa Catarina, Tubarão, SC, Brazil
| | - Gabriela Costa Bernardes
- Laboratory of Neurobiology of Inflammatory and Metabolic Processes, Graduate Program in Health Sciences, Health Sciences Unit, University of South Santa Catarina, Tubarão, SC, Brazil
| | - Sandra Regina Bonfante
- Laboratory of Neurobiology of Inflammatory and Metabolic Processes, Graduate Program in Health Sciences, Health Sciences Unit, University of South Santa Catarina, Tubarão, SC, Brazil
| | - Khiany Mathias
- Laboratory of Neurobiology of Inflammatory and Metabolic Processes, Graduate Program in Health Sciences, Health Sciences Unit, University of South Santa Catarina, Tubarão, SC, Brazil
| | - Erica Biehl
- Laboratory of Neurobiology of Inflammatory and Metabolic Processes, Graduate Program in Health Sciences, Health Sciences Unit, University of South Santa Catarina, Tubarão, SC, Brazil
| | - Érick Bagio
- Laboratory of Neurobiology of Inflammatory and Metabolic Processes, Graduate Program in Health Sciences, Health Sciences Unit, University of South Santa Catarina, Tubarão, SC, Brazil
| | - Solange de Souza Stork
- Laboratory of Neurobiology of Inflammatory and Metabolic Processes, Graduate Program in Health Sciences, Health Sciences Unit, University of South Santa Catarina, Tubarão, SC, Brazil
| | - Tais Denicol
- Laboratory of Neurobiology of Inflammatory and Metabolic Processes, Graduate Program in Health Sciences, Health Sciences Unit, University of South Santa Catarina, Tubarão, SC, Brazil
| | - Mariana Pacheco de Oliveira
- Laboratory of Neurobiology of Inflammatory and Metabolic Processes, Graduate Program in Health Sciences, Health Sciences Unit, University of South Santa Catarina, Tubarão, SC, Brazil
| | - Mariella Reinol da Silva
- Laboratory of Neurobiology of Inflammatory and Metabolic Processes, Graduate Program in Health Sciences, Health Sciences Unit, University of South Santa Catarina, Tubarão, SC, Brazil
| | - Lucinéia Gainski Danielski
- Laboratory of Experimental Neurology, Graduate Program in Health Sciences, University of Southern Santa Catarina, Criciuma, SC, Brazil
| | | | - Gislaine Tezza Rezin
- Laboratory of Neurobiology of Inflammatory and Metabolic Processes, Graduate Program in Health Sciences, Health Sciences Unit, University of South Santa Catarina, Tubarão, SC, Brazil
| | - Silvia Resende Terra
- Department of Biochemistry, Federal University of Rio Grande do Sul, Porto Alegre, RS, Brazil
| | - Jairo Nunes Balsini
- Laboratory of Neurobiology of Inflammatory and Metabolic Processes, Graduate Program in Health Sciences, Health Sciences Unit, University of South Santa Catarina, Tubarão, SC, Brazil
| | - Fernanda Frederico Gava
- Laboratory of Experimental Neurology, Graduate Program in Health Sciences, University of Southern Santa Catarina, Criciuma, SC, Brazil
| | - Fabricia Petronilho
- Laboratory of Experimental Neurology, Graduate Program in Health Sciences, University of Southern Santa Catarina, Criciuma, SC, Brazil.
| |
Collapse
|
7
|
Reiterer M, Eakin A, Johnson RS, Branco CM. Hyperoxia Reprogrammes Microvascular Endothelial Cell Response to Hypoxia in an Organ-Specific Manner. Cells 2022; 11:cells11162469. [PMID: 36010546 PMCID: PMC9406746 DOI: 10.3390/cells11162469] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2022] [Revised: 07/27/2022] [Accepted: 08/02/2022] [Indexed: 11/16/2022] Open
Abstract
Organ function relies on microvascular networks to maintain homeostatic equilibrium, which varies widely in different organs and during different physiological challenges. The endothelium role in this critical process can only be evaluated in physiologically relevant contexts. Comparing the responses to oxygen flux in primary murine microvascular EC (MVEC) obtained from brain and lung tissue reveals that supra-physiological oxygen tensions can compromise MVEC viability. Brain MVEC lose mitochondrial activity and undergo significant alterations in electron transport chain (ETC) composition when cultured under standard, non-physiological atmospheric oxygen levels. While glycolytic capacity of both lung and brain MVEC are unchanged by environmental oxygen, the ability to trigger a metabolic shift when oxygen levels drop is greatly compromised following exposure to hyperoxia. This is particularly striking in MVEC from the brain. This work demonstrates that the unique metabolism and function of organ-specific MVEC (1) can be reprogrammed by external oxygen, (2) that this reprogramming can compromise MVEC survival and, importantly, (3) that ex vivo modelling of endothelial function is significantly affected by culture conditions. It further demonstrates that physiological, metabolic and functional studies performed in non-physiological environments do not represent cell function in situ, and this has serious implications in the interpretation of cell-based pre-clinical models.
Collapse
Affiliation(s)
- Moritz Reiterer
- Patrick G Johnston Centre for Cancer Research, Queen’s University, Belfast BT9 7AE, UK
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge CB2 3EG, UK
| | - Amanda Eakin
- Patrick G Johnston Centre for Cancer Research, Queen’s University, Belfast BT9 7AE, UK
| | - Randall S. Johnson
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge CB2 3EG, UK
| | - Cristina M. Branco
- Patrick G Johnston Centre for Cancer Research, Queen’s University, Belfast BT9 7AE, UK
- Correspondence:
| |
Collapse
|
8
|
Svedung Wettervik T, Hånell A, Howells T, Ronne-Engström E, Enblad P, Lewén A. Association of Arterial Metabolic Content with Cerebral Blood Flow Regulation and Cerebral Energy Metabolism-A Multimodality Analysis in Aneurysmal Subarachnoid Hemorrhage. J Intensive Care Med 2022; 37:1442-1450. [PMID: 35171061 PMCID: PMC9548938 DOI: 10.1177/08850666221080054] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Background In this study, the association of the arterial content of oxygen, carbon
dioxide, glucose, and lactate with cerebral pressure reactivity, energy
metabolism and clinical outcome after aneurysmal subarachnoid hemorrhage
(aSAH) was investigated. Methods In this retrospective study, 60 patients with aSAH, treated at the
neurointensive care (NIC), Uppsala University Hospital, Sweden, between 2016
and 2021 with arterial blood gas (ABG), intracranial pressure, and cerebral
microdialysis (MD) monitoring were included. The first 10 days were divided
into an early phase (day 1 to 3) and a vasospasm phase (day 4 to 10). Results Higher arterial lactate was independently associated with higher/worse
pressure reactivity index (PRx) in the early phase (β = 0.32,
P = .02), whereas higher pO2 had the
opposite association in the vasospasm phase (β = −0.30,
P = .04). Arterial glucose and pCO2 were not
associated with PRx. Higher arterial lactate (β = 0.29,
P = .05) was independently associated with higher
MD-glucose in the vasospasm phase, whereas higher pO2 had the
opposite association in the vasospasm phase (β = −0.33,
P = .03). Arterial glucose and pCO2 were not
associated with MD-glucose. Higher pCO2 in the early phase, lower
arterial glucose in both phases, and lower arterial lactate in the vasospasm
phase were associated (P < .05) with better clinical
outcome. Conclusions Arterial variables associated with more vasoconstriction (higher
pO2 and lower arterial lactate) were associated with better
cerebral pressure reactivity, but worse energy metabolism. In severe aSAH,
when cerebral large-vessel vasospasm with exhausted distal vasodilation is
common, more vasoconstriction could increase distal vasodilatory reserve and
pressure reactivity, but also reduce cerebral blood flow and metabolic
supply. The MD may be useful to monitor the net effects on cerebral
metabolism in PRx-targeted NIC.
Collapse
|
9
|
Wilson DF, Matschinsky FM. Metabolic Homeostasis in Life as We Know It: Its Origin and Thermodynamic Basis. Front Physiol 2021; 12:658997. [PMID: 33967829 PMCID: PMC8104125 DOI: 10.3389/fphys.2021.658997] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Accepted: 03/19/2021] [Indexed: 12/25/2022] Open
Abstract
Living organisms require continuous input of energy for their existence. As a result, life as we know it is based on metabolic processes that extract energy from the environment and make it available to support life (energy metabolism). This metabolism is based on, and regulated by, the underlying thermodynamics. This is important because thermodynamic parameters are stable whereas kinetic parameters are highly variable. Thermodynamic control of metabolism is exerted through near equilibrium reactions that determine. (1) the concentrations of metabolic substrates for enzymes that catalyze irreversible steps and (2) the concentrations of small molecules (AMP, ADP, etc.) that regulate the activity of irreversible reactions in metabolic pathways. The result is a robust homeostatic set point (−ΔGATP) with long term (virtually unlimited) stability. The rest of metabolism and its regulation is constrained to maintain this set point. Thermodynamic control is illustrated using the ATP producing part of glycolysis, glyceraldehyde-3-phosphate oxidation to pyruvate. Flux through the irreversible reaction, pyruvate kinase (PK), is primarily determined by the rate of ATP consumption. Change in the rate of ATP consumption causes mismatch between use and production of ATP. The resulting change in [ATP]/[ADP][Pi], through near equilibrium of the reactions preceding PK, alters the concentrations of ADP and phosphoenolpyruvate (PEP), the substrates for PK. The changes in ADP and PEP alter flux through PK appropriately for restoring equality of ATP production and consumption. These reactions appeared in the very earliest lifeforms and are hypothesized to have established the set point for energy metabolism. As evolution included more metabolic functions, additional layers of control were needed to integrate new functions into existing metabolism without changing the homeostatic set point. Addition of gluconeogenesis, for example, resulted in added regulation to PK activity to prevent futile cycling; PK needs to be turned off during gluconeogenesis because flux through the enzyme would waste energy (ATP), subtracting from net glucose synthesis and decreasing overall efficiency.
Collapse
Affiliation(s)
- David F Wilson
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
| | - Franz M Matschinsky
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
| |
Collapse
|
10
|
Wilson DF, Matschinsky FM. Cerebrovascular Blood Flow Design and Regulation; Vulnerability in Aging Brain. Front Physiol 2020; 11:584891. [PMID: 33178048 PMCID: PMC7596697 DOI: 10.3389/fphys.2020.584891] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2020] [Accepted: 09/24/2020] [Indexed: 12/24/2022] Open
Abstract
Nutrient delivery to the brain presents a unique challenge because the tissue functions as a computer system with in the order of 200,000 neurons/mm3. Penetrating arterioles bud from surface arteries of the brain and penetrate downward through the cortex. Capillary networks spread from penetrating arterioles through the surrounding tissue. Each penetrating arteriole forms a vascular unit, with little sharing of flow among vascular units (collateral flow). Unlike cells in other tissues, neurons have to be operationally isolated, interacting with other neurons through specific electrical connections. Neuronal activation typically involves only a few of the cells within a vascular unit, but the local increase in nutrient consumption is substantial. The metabolic response to activation is transmitted to the feeding arteriole through the endothelium of neighboring capillaries and alters calcium permeability of smooth muscle in the wall resulting in modulation of flow through the entire vascular unit. Many age and trauma related brain pathologies can be traced to vascular malfunction. This includes: 1. Physical damage such as in traumatic injury with imposed shear stress as soft tissue moves relative to the skull. Lack of collateral flow among vascular units results in death of the cells in that vascular unit and loss of brain tissue. 2. Age dependent changes lead to progressive increase in vascular resistance and decrease in tissue levels of oxygen and glucose. Chronic hypoxia/hypoglycemia compromises tissue energy metabolism and related regulatory processes. This alters stem cell proliferation and differentiation, undermines vascular integrity, and suppresses critical repair mechanisms such as oligodendrocyte generation and maturation. Reduced structural integrity results in local regions of acute hypoxia and microbleeds, while failure of oligodendrocytes to fully mature leads to poor axonal myelination and defective neuronal function. Understanding and treating age related pathologies, particularly in brain, requires better knowledge of why and how vasculature changes with age. That knowledge will, hopefully, make possible drugs/methods for protecting vascular function, substantially alleviating the negative health and cognitive deficits associated with growing old.
Collapse
Affiliation(s)
- David F Wilson
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
| | - Franz M Matschinsky
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
| |
Collapse
|
11
|
Dengler F. Activation of AMPK under Hypoxia: Many Roads Leading to Rome. Int J Mol Sci 2020; 21:ijms21072428. [PMID: 32244507 PMCID: PMC7177550 DOI: 10.3390/ijms21072428] [Citation(s) in RCA: 67] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2020] [Revised: 03/26/2020] [Accepted: 03/30/2020] [Indexed: 12/13/2022] Open
Abstract
AMP-activated protein kinase (AMPK) is known as a pivotal cellular energy sensor, mediating the adaptation to low energy levels by deactivating anabolic processes and activating catabolic processes in order to restore the cellular ATP supply when the cellular AMP/ATP ratio is increased. Besides this well-known role, it has also been shown to exert protective effects under hypoxia. While an insufficient supply with oxygen might easily deplete cellular energy levels, i.e., ATP concentration, manifold other mechanisms have been suggested and are heavily disputed regarding the activation of AMPK under hypoxia independently from cellular AMP concentrations. However, an activation of AMPK preceding energy depletion could induce a timely adaptation reaction preventing more serious damage. A connection between AMPK and the master regulator of hypoxic adaptation via gene transcription, hypoxia-inducible factor (HIF), has also been taken into account, orchestrating their concerted protective action. This review will summarize the current knowledge on mechanisms of AMPK activation under hypoxia and its interrelationship with HIF.
Collapse
Affiliation(s)
- Franziska Dengler
- Institute of Veterinary Physiology, University of Leipzig, D-04103 Leipzig, Germany
| |
Collapse
|
12
|
Wilson DF, Matschinsky FM. Ethanol metabolism: The good, the bad, and the ugly. Med Hypotheses 2020; 140:109638. [PMID: 32113062 DOI: 10.1016/j.mehy.2020.109638] [Citation(s) in RCA: 46] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2020] [Revised: 02/14/2020] [Accepted: 02/17/2020] [Indexed: 12/20/2022]
Abstract
Throughout the world, ethanol is both an important commercial commodity and a source of major medical and social problems. Ethanol readily passes through biological membranes and distributes throughout the body. It is oxidized, first to acetaldehyde and then to acetate, and finally by the citric acid cycle in virtually all tissues. The oxidation of ethanol is irreversible and unregulated, making the rate dependent only on local concentration and enzyme activity. This unregulated input of reducing equivalents increases reduction of both cytoplasmic and intramitochondrial NAD and, through the latter, cellular energy state {[ATP]/([ADP][Pi])}. In brain, this increase in energy state stimulates dopaminergic neural activity signalling reward and a sense of well being, while suppressing glutamatergic neural activity signalling anxiety and unease. These positive responses to ethanol ingestion are important to social alcohol consumption. Importantly, decreased free [AMP] decreases AMP-dependent protein kinase (AMPK) activity, an important regulator of cellular energy metabolism. Oxidation of substrates used for energy metabolism in the absence of ethanol is down regulated to accommodate the input from ethanol. In liver, chronic ethanol metabolism results in fatty liver and general metabolic dysfunction. In brain, transport of other oxidizable metabolites through the blood-brain barrier and the enzymes for their oxidation are both down regulated. For exposures of short duration, ethanol induced regulatory changes are rapid and reversible, recovering completely when the concentrations of ethanol and acetate fall again. Longer periods of ethanol exposure and associated chronic suppression of AMPK activity activates regulatory mechanisms, including gene expression, that operate over longer time scales, both in onset and reversal. If chronic alcohol consumption is abruptly ended, metabolism is no longer able to respond rapidly enough to compensate. Glutamatergic neural activity adapts to chronic dysregulation of glutamate metabolism and suppression of glutamatergic neural activity by increasing excitatory and decreasing inhibitory amino acid receptors. A point is reached (ethanol dependence) where withdrawal of ethanol results in significant metabolic energy depletion in neurons and other brain cells as well as hyperexcitation of the glutamatergic system. The extent and regional specificity of energy depletion in the brain, combined with hyperactivity of the glutamatergic neuronal system, largely determines the severity of withdrawal symptoms.
Collapse
Affiliation(s)
- David F Wilson
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, United States.
| | - Franz M Matschinsky
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, United States.
| |
Collapse
|