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Zhang CY, Yang YS, Pei MQ, Chen XL, Chen WC, He HF. The Association of Cerebral Oxygen Desaturation with Postoperative Cognitive Dysfunction in Older Patients: A Review. Clin Interv Aging 2024; 19:1067-1078. [PMID: 38911674 PMCID: PMC11192837 DOI: 10.2147/cia.s462471] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2024] [Accepted: 05/15/2024] [Indexed: 06/25/2024] Open
Abstract
Postoperative cognitive dysfunction (POCD) is a neurological complication associated with surgery and anesthesia that is commonly observed in older patients, and it can significantly affect patient prognosis and survival. Therefore, predicting and preventing POCD is important. Regional cerebral oxygen saturation (rSO2) reflects cerebral perfusion and oxygenation, and decreased intraoperative cerebral oxygen saturation has been reported to increase the risk of POCD. In this review, we elucidated the important relationship between the decline in rSO2 and risk of POCD in older patients. We also emphasized the importance of monitoring rSO2 during surgery to predict and prevent adverse perioperative cognitive outcomes. The findings reveal that incorporating intraoperative rSO2 monitoring into clinical practice has potential benefits, such as protecting cognitive function, reducing perioperative adverse outcomes, and ultimately improving the overall quality of life of older adults.
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Affiliation(s)
- Chun-Yan Zhang
- Department of Anesthesiology, The Second Affiliated Hospital of Fujian Medical University, Quanzhou, Fujian Province, People’s Republic of China
| | - Yu-Shen Yang
- Department of Anesthesiology, The Second Affiliated Hospital of Fujian Medical University, Quanzhou, Fujian Province, People’s Republic of China
| | - Meng-Qin Pei
- Department of Anesthesiology, The Second Affiliated Hospital of Fujian Medical University, Quanzhou, Fujian Province, People’s Republic of China
| | - Xin-Li Chen
- Department of Anesthesiology, The Second Affiliated Hospital of Fujian Medical University, Quanzhou, Fujian Province, People’s Republic of China
| | - Wei-can Chen
- Department of Anesthesiology, The Second Affiliated Hospital of Fujian Medical University, Quanzhou, Fujian Province, People’s Republic of China
| | - He-Fan He
- Department of Anesthesiology, The Second Affiliated Hospital of Fujian Medical University, Quanzhou, Fujian Province, People’s Republic of China
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Guan S, Li Y, Xin Y, Wang D, Lu P, Han F, Xu H. Deciphering the dual role of N-methyl-D-Aspartate receptor in postoperative cognitive dysfunction: A comprehensive review. Eur J Pharmacol 2024; 971:176520. [PMID: 38527701 DOI: 10.1016/j.ejphar.2024.176520] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2023] [Revised: 03/03/2024] [Accepted: 03/20/2024] [Indexed: 03/27/2024]
Abstract
Postoperative cognitive dysfunction (POCD) is a common complication following surgery, adversely impacting patients' recovery, increasing the risk of negative outcomes, prolonged hospitalization, and higher mortality rates. The N-methyl-D-aspartate (NMDA) receptor, crucial for learning, memory, and synaptic plasticity, plays a significant role in the development of POCD. Various perioperative factors, including age and anesthetic use, can reduce NMDA receptor function, while surgical stress, inflammation, and pain may lead to its excessive activation. This review consolidates preclinical and clinical research to explore the intricate relationship between perioperative factors affecting NMDA receptor functionality and the onset of POCD. It discusses the influence of aging, anesthetic administration, perioperative injury, pain, and inflammation on the NMDA receptor-related pathophysiology of POCD. The comprehensive analysis presented aims to identify effective treatment targets for POCD, contributing to the improvement of patient outcomes post-surgery.
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Affiliation(s)
- Shaodi Guan
- Department of Anesthesiology and Pain Medicine, Hubei Key Laboratory of Geriatric Anesthesia and Perioperative Brain Health, and Wuhan Clinical Research Center for Geriatric Anesthesia, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China
| | - Yali Li
- Department of Anesthesiology and Pain Medicine, Hubei Key Laboratory of Geriatric Anesthesia and Perioperative Brain Health, and Wuhan Clinical Research Center for Geriatric Anesthesia, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China
| | - Yueyang Xin
- Department of Anesthesiology and Pain Medicine, Hubei Key Laboratory of Geriatric Anesthesia and Perioperative Brain Health, and Wuhan Clinical Research Center for Geriatric Anesthesia, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China
| | - Danning Wang
- Department of Anesthesiology and Pain Medicine, Hubei Key Laboratory of Geriatric Anesthesia and Perioperative Brain Health, and Wuhan Clinical Research Center for Geriatric Anesthesia, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China
| | - Pei Lu
- Department of Anesthesiology and Pain Medicine, Hubei Key Laboratory of Geriatric Anesthesia and Perioperative Brain Health, and Wuhan Clinical Research Center for Geriatric Anesthesia, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China
| | - Fanglong Han
- Department of Anesthesiology, Xiangyang Maternal and Child Health Hospital, Xiangyang, 441003, China
| | - Hui Xu
- Department of Anesthesiology and Pain Medicine, Hubei Key Laboratory of Geriatric Anesthesia and Perioperative Brain Health, and Wuhan Clinical Research Center for Geriatric Anesthesia, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China.
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3
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Wang Y, Zhang Q, Ma Q, Wang Q, Huang D, Ji X. Intermittent hypoxia preconditioning can attenuate acute hypoxic injury after a sustained normobaric hypoxic exposure: A randomized clinical trial. CNS Neurosci Ther 2024; 30:e14662. [PMID: 38477221 PMCID: PMC10934266 DOI: 10.1111/cns.14662] [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: 10/10/2023] [Revised: 01/02/2024] [Accepted: 02/17/2024] [Indexed: 03/14/2024] Open
Abstract
BACKGROUND Intermittent hypoxia (IH) is emerging as a cost-effective nonpharmacological method for vital organ protection. We aimed to assess the effects of a short-term moderate intermittent hypoxia preconditioning protocol (four cycles of 13% hypoxia lasting for 10 min with 5-min normoxia intervals) on acute hypoxic injury induced by sustained hypoxic exposure (oxygen concentration of 11.8% for 6 h). METHODS One hundred healthy volunteers were recruited and randomized to the IH group and the control group to receive IH or sham-IH preconditioning for 5 days, respectively, and then were sent to a hypoxic chamber for simulated acute high-altitude exposure (4500 m). RESULTS The overall incidence of acute mountain sickness was 27% (27/100), with 14% (7/50) in the IH group and 40% (20/50) in the control group (p = 0.003). After 6-h simulated high-altitude exposure, the mean Lake Louise Score was lower in the IH group as compared to controls (1.30 ± 1.27 vs. 2.04 ± 1.89, p = 0.024). Mean peripheral oxygen saturations (SpO2 ) and intracranial pressure (ICP) measures after acute hypoxic exposure exhibited significant differences, with the IH group showing significantly greater SpO2 values (85.47 ± 5.14 vs. 83.10 ± 5.15%, p = 0.026) and lower ICP levels than the control group (115.59 ± 32.15 vs. 130.36 ± 33.83 mmH2 O, p = 0.028). IH preconditioning also showed greater effects on serum protein gene product 9.5 (3.89 vs. 29.16 pg/mL; p = 0.048) and C-reactive protein (-0.28 vs. 0.41 mg/L; p = 0.023). CONCLUSION The short-term moderate IH improved the tolerance to hypoxia and exerted protection against acute hypoxic injury induced by exposure to sustained normobaric hypoxia, which provided a novel method and randomized controlled trial evidence to develop treatments for hypoxia-related disease.
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Affiliation(s)
- Yuan Wang
- Department of Neurology, Xuanwu HospitalCapital Medical UniversityBeijingChina
| | - Qihan Zhang
- Department of Neurology, Xuanwu HospitalCapital Medical UniversityBeijingChina
| | - Qingfeng Ma
- Department of Neurology, Xuanwu HospitalCapital Medical UniversityBeijingChina
| | - Qing Wang
- Department of Neurology, Xuanwu HospitalCapital Medical UniversityBeijingChina
| | - Dan Huang
- Development Coordination OfficeBeijing Xiaotangshan HospitalBeijingChina
| | - Xunming Ji
- Department of Neurosurgery, Xuanwu HospitalCapital Medical UniversityBeijingChina
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Williams TB, Badariotti JI, Corbett J, Miller-Dicks M, Neupert E, McMorris T, Ando S, Parker MO, Thelwell RC, Causer AJ, Young JS, Mayes HS, White DK, de Carvalho FA, Tipton MJ, Costello JT. The effects of sleep deprivation, acute hypoxia, and exercise on cognitive performance: A multi-experiment combined stressors study. Physiol Behav 2024; 274:114409. [PMID: 37977251 DOI: 10.1016/j.physbeh.2023.114409] [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: 10/20/2023] [Revised: 11/08/2023] [Accepted: 11/11/2023] [Indexed: 11/19/2023]
Abstract
INTRODUCTION Both sleep deprivation and hypoxia have been shown to impair executive function. Conversely, moderate intensity exercise is known to improve executive function. In a multi-experiment study, we tested the hypotheses that moderate intensity exercise would ameliorate any decline in executive function after i) three consecutive nights of partial sleep deprivation (PSD) (Experiment 1) and ii) the isolated and combined effects of a single night of total sleep deprivation (TSD) and acute hypoxia (Experiment 2). METHODS Using a rigorous randomised controlled crossover design, 12 healthy participants volunteered in each experiment (24 total, 5 females). In both experiments seven executive function tasks (2-choice reaction time, logical relations, manikin, mathematical processing, 1-back, 2-back, 3-back) were completed at rest and during 20 min semi-recumbent, moderate intensity cycling. Tasks were completed in the following conditions: before and after three consecutive nights of PSD and habitual sleep (Experiment 1) and in normoxia and acute hypoxia (FIO2 = 0.12) following one night of habitual sleep and one night of TSD (Experiment 2). RESULTS Although the effects of three nights of PSD on executive functions were inconsistent, one night of TSD (regardless of hypoxic status) reduced executive functions. Significantly, regardless of sleep or hypoxic status, executive functions are improved during an acute bout of moderate intensity exercise. CONCLUSION These novel data indicate that moderate intensity exercise improves executive function performance after both PSD and TSD, regardless of hypoxic status. The key determinants and/or mechanism(s) responsible for this improvement still need to be elucidated. Future work should seek to identify these mechanisms and translate these significant findings into occupational and skilled performance settings.
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Affiliation(s)
- Thomas B Williams
- School of Sport, Health and Exercise Science, University of Portsmouth, Portsmouth, United Kingdom
| | - Juan I Badariotti
- School of Sport, Health and Exercise Science, University of Portsmouth, Portsmouth, United Kingdom; Department of Psychology, University of Portsmouth, Portsmouth, United Kingdom
| | - Jo Corbett
- School of Sport, Health and Exercise Science, University of Portsmouth, Portsmouth, United Kingdom
| | - Matt Miller-Dicks
- School of Sport, Health and Exercise Science, University of Portsmouth, Portsmouth, United Kingdom
| | - Emma Neupert
- School of Sport, Health and Exercise Science, University of Portsmouth, Portsmouth, United Kingdom
| | - Terry McMorris
- School of Sport, Health and Exercise Science, University of Portsmouth, Portsmouth, United Kingdom; Department of Sport and Exercise Sciences, University of Chichester, Chichester, United Kingdom
| | - Soichi Ando
- Graduate School of Informatics and Engineering, The University of Electro-Communications, Tokyo, Japan
| | - Matthew O Parker
- Surrey Sleep Research Centre, School of Biosciences, University of Surrey, Guildford, United Kingdom
| | - Richard C Thelwell
- School of Sport, Health and Exercise Science, University of Portsmouth, Portsmouth, United Kingdom
| | - Adam J Causer
- School of Sport, Health and Exercise Science, University of Portsmouth, Portsmouth, United Kingdom
| | - John S Young
- National Horizons Centre, Teesside University, Darlington, United Kingdom; School of Health and Life Sciences, Teesside University, Middlesbrough, United Kingdom
| | - Harry S Mayes
- School of Sport, Health and Exercise Science, University of Portsmouth, Portsmouth, United Kingdom
| | - Danny K White
- School of Sport, Health and Exercise Science, University of Portsmouth, Portsmouth, United Kingdom
| | | | - Michael J Tipton
- School of Sport, Health and Exercise Science, University of Portsmouth, Portsmouth, United Kingdom
| | - Joseph T Costello
- School of Sport, Health and Exercise Science, University of Portsmouth, Portsmouth, United Kingdom.
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Ando S, Tsukamoto H, Stacey BS, Washio T, Owens TS, Calverley TA, Fall L, Marley CJ, Iannetelli A, Hashimoto T, Ogoh S, Bailey DM. Acute hypoxia impairs posterior cerebral bioenergetics and memory in man. Exp Physiol 2023; 108:1516-1530. [PMID: 37898979 PMCID: PMC10988469 DOI: 10.1113/ep091245] [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: 04/06/2023] [Accepted: 10/03/2023] [Indexed: 10/31/2023]
Abstract
Hypoxia has the potential to impair cognitive function; however, it is still uncertain which cognitive domains are adversely affected. We examined the effects of acute hypoxia (∼7 h) on central executive (Go/No-Go) and non-executive (memory) tasks and the extent to which impairment was potentially related to regional cerebral blood flow and oxygen delivery (CDO2 ). Twelve male participants performed cognitive tasks following 0, 2, 4 and 6 h of passive exposure to both normoxia and hypoxia (12% O2 ), in a randomized block cross-over single-blinded design. Middle cerebral artery (MCA) and posterior cerebral artery (PCA) blood velocities and corresponding CDO2 were determined using bilateral transcranial Doppler ultrasound. In hypoxia, MCA DO2 was reduced during the Go/No-Go task (P = 0.010 vs. normoxia, main effect), and PCA DO2 was attenuated during memorization (P = 0.005 vs. normoxia) and recall components (P = 0.002 vs. normoxia) in the memory task. The accuracy of the memory task was also impaired in hypoxia (P = 0.049 vs. normoxia). In contrast, hypoxia failed to alter reaction time (P = 0.19 vs. normoxia) or accuracy (P = 0.20 vs. normoxia) during the Go/No-Go task, indicating that selective attention and response inhibition were preserved. Hypoxia did not affect cerebral blood flow or corresponding CDO2 responses to cognitive activity (P > 0.05 vs. normoxia). Collectively, these findings highlight the differential sensitivity of cognitive domains, with memory being selectively vulnerable in hypoxia. NEW FINDINGS: What is the central question of this study? We sought to examine the effects of acute hypoxia on central executive (selective attention and response inhibition) and non-executive (memory) performance and the extent to which impairments are potentially related to reductions in regional cerebral blood flow and oxygen delivery. What is the main finding and its importance? Memory was impaired in acute hypoxia, and this was accompanied by a selective reduction in posterior cerebral artery oxygen delivery. In contrast, selective attention and response inhibition remained well preserved. These findings suggest that memory is selectively vulnerable to hypoxia.
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Affiliation(s)
- Soichi Ando
- Graduate School of Informatics and EngineeringThe University of Electro‐CommunicationsTokyoJapan
| | - Hayato Tsukamoto
- Neurovascular Research Laboratory, Faculty of Life Sciences and EducationUniversity of South WalesPontypriddUK
- Faculty of Sports ScienceWaseda UniversitySaitamaJapan
| | - Benjamin S. Stacey
- Neurovascular Research Laboratory, Faculty of Life Sciences and EducationUniversity of South WalesPontypriddUK
| | - Takuro Washio
- Department of Biomedical EngineeringToyo UniversityKawagoeSaitamaJapan
| | - Thomas S. Owens
- Neurovascular Research Laboratory, Faculty of Life Sciences and EducationUniversity of South WalesPontypriddUK
| | - Thomas A. Calverley
- Neurovascular Research Laboratory, Faculty of Life Sciences and EducationUniversity of South WalesPontypriddUK
| | - Lewis Fall
- Neurovascular Research Laboratory, Faculty of Life Sciences and EducationUniversity of South WalesPontypriddUK
| | - Christopher J. Marley
- Neurovascular Research Laboratory, Faculty of Life Sciences and EducationUniversity of South WalesPontypriddUK
| | - Angelo Iannetelli
- Neurovascular Research Laboratory, Faculty of Life Sciences and EducationUniversity of South WalesPontypriddUK
| | | | - Shigehiko Ogoh
- Neurovascular Research Laboratory, Faculty of Life Sciences and EducationUniversity of South WalesPontypriddUK
- Department of Biomedical EngineeringToyo UniversityKawagoeSaitamaJapan
| | - Damian M. Bailey
- Neurovascular Research Laboratory, Faculty of Life Sciences and EducationUniversity of South WalesPontypriddUK
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Bakker ME, Djerourou I, Belanger S, Lesage F, Vanni MP. Alteration of functional connectivity despite preserved cerebral oxygenation during acute hypoxia. Sci Rep 2023; 13:13269. [PMID: 37582847 PMCID: PMC10427674 DOI: 10.1038/s41598-023-40321-3] [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: 04/06/2023] [Accepted: 08/08/2023] [Indexed: 08/17/2023] Open
Abstract
Resting state networks (RSN), which show the connectivity in the brain in the absence of any stimuli, are increasingly important to assess brain function. Here, we investigate the changes in RSN as well as the hemodynamic changes during acute, global hypoxia. Mice were imaged at different levels of oxygen (21, 12, 10 and 8%) over the course of 10 weeks, with hypoxia and normoxia acquisitions interspersed. Simultaneous GCaMP and intrinsic optical imaging allowed tracking of both neuronal and hemodynamic changes. During hypoxic conditions, we found a global increase of both HbO and HbR in the brain. The saturation levels of blood dropped after the onset of hypoxia, but surprisingly climbed back to levels similar to baseline within the 10-min hypoxia period. Neuronal activity also showed a peak at the onset of hypoxia, but dropped back to baseline as well. Despite regaining baseline sO2 levels, changes in neuronal RSN were observed. In particular, the connectivity as measured with GCaMP between anterior and posterior parts of the brain decreased. In contrast, when looking at these same connections with HbO measurements, an increase in connectivity in anterior-posterior brain areas was observed suggesting a potential neurovascular decoupling.
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Affiliation(s)
- Marleen E Bakker
- École d'Optométrie, Université de Montréal, 2500 Chem. De Polytechnique, Montréal, QC, H3T 1J4, Canada.
- Institute of Biomedical Engineering, École Polytechnique de Montréal, Montréal, Canada.
| | - Ismaël Djerourou
- École d'Optométrie, Université de Montréal, 2500 Chem. De Polytechnique, Montréal, QC, H3T 1J4, Canada
| | | | - Frédéric Lesage
- Institute of Biomedical Engineering, École Polytechnique de Montréal, Montréal, Canada
- Montréal Heart Institute, Montréal, Canada
| | - Matthieu P Vanni
- École d'Optométrie, Université de Montréal, 2500 Chem. De Polytechnique, Montréal, QC, H3T 1J4, Canada
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Ovsenik A, Podbregar M, Lakič N, Brešar M, Boškoski P, Verdenik I, Fabjan A. Neurovascular coupling in severe aortic valve stenosis. Brain Behav 2023; 13:e3155. [PMID: 37475651 PMCID: PMC10454277 DOI: 10.1002/brb3.3155] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Revised: 05/18/2023] [Accepted: 07/06/2023] [Indexed: 07/22/2023] Open
Abstract
OBJECTIVES Aortic stenosis (AS) is characterized by obstruction of blood outflow from the left ventricle, which can impair target organ perfusion such as the brain. We hypothesized that hemodynamic changes in AS may lead to dysfunction of cerebral blood flow regulatory mechanisms. The aim of our study was to evaluate neurovascular coupling in patients with AS by Transcranial Doppler ultrasonography. METHODS Neurovascular coupling was assessed using visually evoked cerebral blood flow velocity responses (VEFR) calculated as relative blood flow velocity changes in the posterior cerebral artery upon visual stimulation. We analyzed peak systolic, mean and end diastolic VEFR in 54 patients with severe AS and 43 controls in 10 consecutive cycles of visual stimulation. Repeated-measures ANOVA test was used to compare cerebral hemodynamic data by group. RESULTS Patients with AS had significantly higher peak systolic (12.9% ± 5.6% and 10.5% ± 4.5%; p = .009) and mean VEFR (14.4% ± 5.8% and 12.2% ± 4.9%; p = .021) compared to controls, whereas only a tendency for higher end diastolic VEFR was observed (16.7% ± 6.9% and 14.4% ± 6.2%; p = .061). CONCLUSION We have shown for the first time that patients with severe AS exhibit higher VEFR than controls indicating dysregulation of neurovascular coupling, which can be one of the factors contributing to development of cognitive decline.
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Affiliation(s)
- Ana Ovsenik
- Faculty of Medicine, Department of BiomedicineUniversity of LjubljanaLjubljanaSlovenia
- Department of CardiologyUniversity Medical Centre LjubljanaLjubljanaSlovenia
| | - Matej Podbregar
- Faculty of Medicine, Department of Internal MedicineUniversity of LjubljanaLjubljanaSlovenia
- Department of Intensive CareGeneral Hospital CeljeCeljeSlovenia
| | - Nikola Lakič
- Department of Cardiovascular SurgeryUniversity Medical Centre LjubljanaLjubljanaSlovenia
| | - Martin Brešar
- Jožef Stefan International Postgraduate SchoolLjubljanaSlovenia
- Department of Systems and ControlJožef Stefan InstituteLjubljanaSlovenia
| | - Pavle Boškoski
- Department of Systems and ControlJožef Stefan InstituteLjubljanaSlovenia
| | - Ivan Verdenik
- Department of Obstetrics and Gynaecology, Division for ResearchUniversity Medical Centre LjubljanaLjubljanaSlovenia
| | - Andrej Fabjan
- Faculty of Medicine, Institute for PhysiologyUniversity of LjubljanaLjubljanaSlovenia
- Department of Vascular Neurology and Neurological Intensive CareUniversity Medical Centre LjubljanaLjubljanaSlovenia
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Cui J, Ma Q, Zhang C, Li Y, Liu J, Xie K, Luo E, Zhai M, Tang C. Keratin 18 Depletion as a Possible Mechanism for the Induction of Apoptosis and Ferroptosis in the Rat Hippocampus After Hypobaric Hypoxia. Neuroscience 2023; 513:64-75. [PMID: 36395917 DOI: 10.1016/j.neuroscience.2022.11.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2022] [Revised: 11/03/2022] [Accepted: 11/08/2022] [Indexed: 11/16/2022]
Abstract
Memory impairment is one of the neuropsychological effects of hypobaric hypoxia (HH), which can be associated with programmed cell death, such as apoptosis and ferroptosis. Emerging evidence indicates crosstalk between apoptosis and ferroptosis, while the crosstalk between HH-induced apoptosis and ferroptosis in the hippocampus has not been clarified. Here, microarray profiles were extracted to analyze the differentially expressed genes with and without HH exposure, and keratin 18 (Krt18) was found to be a potential gene related to both apoptosis and ferroptosis. Then, we conducted morphological observations that showed that apoptosis and ferroptosis coexisted in the rat hippocampus after HH exposure. Combined with the real-time q-PCR analysis, the mRNA expression of Krt18 decreased significantly after HH exposure for 1 day and 3 days, and Mapk10 (JNK3) was upregulated at the corresponding time points. After exposure for 7 days, Krt18 and JNK3 showed no significant change. In conclusion, Krt18 may regulate apoptosis and ferroptosis simultaneously, possibly via the JNK signaling pathway, which might provide a potential central target for apoptosis and ferroptosis in hippocampal injury after HH exposure.
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Affiliation(s)
- Jinxiu Cui
- Department of Military Medical Equipment and Metrology, School of Military Biomedical Engineering, Fourth Military Medical University, 710032 Xi'an, Shaanxi, PR China
| | - Qianqian Ma
- Department of Military Medical Equipment and Metrology, School of Military Biomedical Engineering, Fourth Military Medical University, 710032 Xi'an, Shaanxi, PR China; The College of Life Sciences, Northwest University, 710069 Xi'an, Shaanxi, PR China
| | - Chenxu Zhang
- Department of Military Medical Equipment and Metrology, School of Military Biomedical Engineering, Fourth Military Medical University, 710032 Xi'an, Shaanxi, PR China
| | - Yuanzhe Li
- Department of Military Medical Equipment and Metrology, School of Military Biomedical Engineering, Fourth Military Medical University, 710032 Xi'an, Shaanxi, PR China
| | - Juan Liu
- Department of Military Medical Equipment and Metrology, School of Military Biomedical Engineering, Fourth Military Medical University, 710032 Xi'an, Shaanxi, PR China
| | - Kangning Xie
- Department of Military Medical Equipment and Metrology, School of Military Biomedical Engineering, Fourth Military Medical University, 710032 Xi'an, Shaanxi, PR China
| | - Erping Luo
- Department of Military Medical Equipment and Metrology, School of Military Biomedical Engineering, Fourth Military Medical University, 710032 Xi'an, Shaanxi, PR China
| | - Mingming Zhai
- Department of Military Medical Equipment and Metrology, School of Military Biomedical Engineering, Fourth Military Medical University, 710032 Xi'an, Shaanxi, PR China.
| | - Chi Tang
- Department of Military Medical Equipment and Metrology, School of Military Biomedical Engineering, Fourth Military Medical University, 710032 Xi'an, Shaanxi, PR China; Shaanxi Provincial Key Laboratory of Bioelectromagnetic Detection and Intelligent Perception, School of Military Biomedical Engineering, Fourth Military Medical University, 710032 Xi'an, Shaanxi, PR China.
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9
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Li G, Guan Y, Gu Y, Guo M, Ma W, Shao Q, Liu J, Ji X. Intermittent hypoxic conditioning restores neurological dysfunction of mice induced by long-term hypoxia. CNS Neurosci Ther 2022; 29:202-215. [PMID: 36401601 PMCID: PMC9804074 DOI: 10.1111/cns.13996] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2022] [Revised: 09/18/2022] [Accepted: 09/20/2022] [Indexed: 11/21/2022] Open
Abstract
BACKGROUND Central nervous system diseases are associated with hypoxia, which usually cause irreversible nerve damage, but the underlying mechanism is unclear and effective intervention strategies are lacking. This study was designed to explore the mechanism and treatment strategy of hypoxia-induced nerve injury. METHODS In this study, 13% O2 was used to treat mice for 0, 1, 3 7, and 14 days, Morris water maze and other animal behavior experiments were used to evaluate the neurological function of mice. TUNEL, BrdU, PCNA, DCX, and SOX2 staining were used to observe the apoptosis and proliferation of mouse neurons. RT-PCR and Iba1 staining were used to evaluate the release of inflammatory factors IL-1β, IL-6, and TNF-α and the activation of microglia. RESULTS Short-term hypoxia promotes neurogenesis, while long-term hypoxia inhibits neurogenesis. The changes in hypoxia-induced neurogenesis were positively correlated with neurological functions, but negatively correlated with apoptosis. Moreover, intermittent hypoxic conditioning restored long-term hypoxia-induced neurological dysfunction by promoting neural stem cell generation and inhibiting the release of inflammatory factors IL-1β, IL-6, and TNF-α and the activation of microglia. CONCLUSION Hypoxia promoted neurogenesis in a time-dependent manner, and intermittent hypoxic conditioning exerted a neuroprotective effect through promoting neural stem cell generation and suppressing inflammation induced by long-term hypoxia stress, which provided a novel concept to develop a treatment for hypoxia-related brain injury.
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Affiliation(s)
- Gaifen Li
- Beijing Institute of Brain Disorders, Laboratory of Brain Disorders, Ministry of Science and Technology, Collaborative Innovation Center for Brain Disorders, Beijing Advanced Innovation Center for Big Data‐based Precision MedicineCapital Medical UniversityBeijingChina,Department of Neurosurgery, Xuanwu HospitalCapital Medical UniversityBeijingChina
| | - Yuying Guan
- Beijing Institute of Brain Disorders, Laboratory of Brain Disorders, Ministry of Science and Technology, Collaborative Innovation Center for Brain Disorders, Beijing Advanced Innovation Center for Big Data‐based Precision MedicineCapital Medical UniversityBeijingChina,Department of Neurosurgery, Xuanwu HospitalCapital Medical UniversityBeijingChina
| | - Yakun Gu
- Beijing Institute of Brain Disorders, Laboratory of Brain Disorders, Ministry of Science and Technology, Collaborative Innovation Center for Brain Disorders, Beijing Advanced Innovation Center for Big Data‐based Precision MedicineCapital Medical UniversityBeijingChina
| | - Mengyuan Guo
- Beijing Institute of Brain Disorders, Laboratory of Brain Disorders, Ministry of Science and Technology, Collaborative Innovation Center for Brain Disorders, Beijing Advanced Innovation Center for Big Data‐based Precision MedicineCapital Medical UniversityBeijingChina
| | - Wei Ma
- Beijing Institute of Brain Disorders, Laboratory of Brain Disorders, Ministry of Science and Technology, Collaborative Innovation Center for Brain Disorders, Beijing Advanced Innovation Center for Big Data‐based Precision MedicineCapital Medical UniversityBeijingChina
| | - Qianqian Shao
- Beijing Institute of Brain Disorders, Laboratory of Brain Disorders, Ministry of Science and Technology, Collaborative Innovation Center for Brain Disorders, Beijing Advanced Innovation Center for Big Data‐based Precision MedicineCapital Medical UniversityBeijingChina
| | - Jia Liu
- Beijing Institute of Brain Disorders, Laboratory of Brain Disorders, Ministry of Science and Technology, Collaborative Innovation Center for Brain Disorders, Beijing Advanced Innovation Center for Big Data‐based Precision MedicineCapital Medical UniversityBeijingChina
| | - Xunming Ji
- Beijing Institute of Brain Disorders, Laboratory of Brain Disorders, Ministry of Science and Technology, Collaborative Innovation Center for Brain Disorders, Beijing Advanced Innovation Center for Big Data‐based Precision MedicineCapital Medical UniversityBeijingChina,Department of Neurosurgery, Xuanwu HospitalCapital Medical UniversityBeijingChina
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10
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Mikkelsen ACD, Thomsen KL, Mookerjee RP, Hadjihambi A. The role of brain inflammation and abnormal brain oxygen homeostasis in the development of hepatic encephalopathy. Metab Brain Dis 2022; 38:1707-1716. [PMID: 36326976 DOI: 10.1007/s11011-022-01105-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/30/2022] [Accepted: 10/10/2022] [Indexed: 11/06/2022]
Abstract
Hepatic encephalopathy (HE) is a frequent complication of chronic liver disease (CLD) and has a complex pathogenesis. Several preclinical and clinical studies have reported the presence of both peripheral and brain inflammation in CLD and their potential impact in the development of HE. Altered brain vascular density and tone, as well as compromised cerebral and systemic blood flow contributing to the development of brain hypoxia, have also been reported in animal models of HE, while a decrease in cerebral metabolic rate of oxygen and cerebral blood flow has consistently been observed in patients with HE. Whilst significant strides in our understanding have been made over the years, evaluating all these mechanistic elements in vivo and showing causal association with development of HE, have been limited through the practical constraints of experimentation. Nonetheless, improvements in non-invasive assessments of different neurophysiological parameters, coupled with techniques to assess changes in inflammatory and metabolic pathways, will help provide more granular insights on these mechanisms. In this special issue we discuss some of the emerging evidence supporting the hypothesis that brain inflammation and abnormal oxygen homeostasis occur interdependently during CLD and comprise important contributors to the development of HE. This review aims at furnishing evidence for further research in brain inflammation and oxygen homeostasis as additional therapeutic targets and potentially diagnostic markers for HE.
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Affiliation(s)
| | - Karen Louise Thomsen
- Department of Hepatology and Gastroenterology, Aarhus University Hospital, Aarhus, Denmark
- UCL Institute of Liver and Digestive Health, University College London, London, UK
| | - Rajeshwar Prosad Mookerjee
- Department of Hepatology and Gastroenterology, Aarhus University Hospital, Aarhus, Denmark
- UCL Institute of Liver and Digestive Health, University College London, London, UK
| | - Anna Hadjihambi
- The Roger Williams Institute of Hepatology London, Foundation for Liver Research, London, SE5 9NT, UK.
- Faculty of Life Sciences and Medicine, King's College London, London, UK.
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11
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Rogan M, Friend AT, Rossetti GM, Edden R, Mikkelsen M, Oliver SJ, Macdonald JH, Mullins PG. Hypoxia alters posterior cingulate cortex metabolism during a memory task: A 1H fMRS study. Neuroimage 2022; 260:119397. [PMID: 35752413 PMCID: PMC9513808 DOI: 10.1016/j.neuroimage.2022.119397] [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] [Received: 05/20/2022] [Accepted: 06/16/2022] [Indexed: 11/16/2022] Open
Abstract
Environmental hypoxia (fraction of inspired oxygen (FIO2) ∼ 0.120) is known to trigger a global increase in cerebral blood flow (CBF). However, regionally, a heterogeneous response is reported, particularly within the posterior cingulate cortex (PCC) where decreased CBF is found after two hours of hypoxic exposure. Furthermore, hypoxia reverses task-evoked BOLD signals within the PCC, and other regions of the default mode network, suggesting a reversal of neurovascular coupling. An alternative explanation is that the neural architecture supporting cognitive tasks is reorganised. Therefore, to confirm if this previous result is neural or vascular in origin, a measure of neural activity that is not haemodynamic-dependant is required. To achieve this, we utilised functional magnetic resonance spectroscopy to probe the glutamate response to memory recall in the PCC during normoxia (FIO2 = 0.209) and after two hours of poikilocapnic hypoxia (FIO2 = 0.120). We also acquired ASL-based measures of CBF to confirm previous findings of reduced CBF within the PCC in hypoxia. Consistent with previous findings, hypoxia induced a reduction in CBF within the PCC and other regions of the default mode network. Under normoxic conditions, memory recall was associated with an 8% increase in PCC glutamate compared to rest (P = 0.019); a change which was not observed during hypoxia. However, exploratory analysis of other neurometabolites showed that PCC glucose was reduced during hypoxia compared to normoxia both at rest (P = 0.039) and during the task (P = 0.046). We conclude that hypoxia alters the activity-induced increase in glutamate, which may reflect a reduction in oxidative metabolism within the PCC. The reduction in glucose in hypoxia reflects continued metabolism, presumably by non-oxidative means, without replacement of glucose due to reduced CBF.
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Affiliation(s)
- Matthew Rogan
- School of Human and Behavioural Sciences, Bangor University, Bangor, United Kingdom; The Bangor Imaging Unit, Bangor University, Bangor, United Kingdom; Institute for Applied Human Physiology, Bangor University, Bangor, United Kingdom
| | - Alexander T Friend
- School of Human and Behavioural Sciences, Bangor University, Bangor, United Kingdom; Institute for Applied Human Physiology, Bangor University, Bangor, United Kingdom
| | - Gabriella Mk Rossetti
- Centre for Integrative Neuroscience and Neurodynamics, University of Reading, Reading, United Kingdom
| | - Richard Edden
- Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins University School of Medicine, Baltimore, MD, United States; F. M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD, United States
| | - Mark Mikkelsen
- Department of Radiology, Weill Cornell Medicine, New York, NY, United States
| | - Samuel J Oliver
- School of Human and Behavioural Sciences, Bangor University, Bangor, United Kingdom; Institute for Applied Human Physiology, Bangor University, Bangor, United Kingdom
| | - Jamie H Macdonald
- School of Human and Behavioural Sciences, Bangor University, Bangor, United Kingdom; Institute for Applied Human Physiology, Bangor University, Bangor, United Kingdom
| | - Paul G Mullins
- School of Human and Behavioural Sciences, Bangor University, Bangor, United Kingdom; The Bangor Imaging Unit, Bangor University, Bangor, United Kingdom; Institute for Applied Human Physiology, Bangor University, Bangor, United Kingdom.
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12
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Chen X, Zhou A, Li J, Chen B, Zhou X, Ma H, Lu C, Weng X. Effects of Long-Term Exposure to 2260 m Altitude on Working Memory and Resting-State Activity in the Prefrontal Cortex: A Large-Sample Cross-Sectional Study. Brain Sci 2022; 12:brainsci12091148. [PMID: 36138884 PMCID: PMC9496949 DOI: 10.3390/brainsci12091148] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2022] [Revised: 08/06/2022] [Accepted: 08/25/2022] [Indexed: 11/16/2022] Open
Abstract
It has been well established that very-high-altitude (>4000 m) environments can affect human cognitive function and brain activity. However, the effects of long-term exposure to moderate altitudes (2000−3000 m) on cognitive function and brain activity are not well understood. In the present cross-sectional study, we utilized an N-back working memory task and resting-state functional near-infrared spectroscopy to examine the effects of two years of exposure to 2260 m altitude on working memory and resting-state brain activity in 208 college students, compared with a control group at the sea level. The results showed that there was no significant change in spatial working memory performance after two years of exposure to 2260 m altitude. In contrast, the analysis of resting-state brain activity revealed changes in functional connectivity patterns in the prefrontal cortex (PFC), with the global efficiency increased and the local efficiency decreased after two years of exposure to 2260 m altitude. These results suggest that long-term exposure to moderate altitudes has no observable effect on spatial working memory performance, while significant changes in functional connectivity and brain network properties could possibly occur to compensate for the effects of mild hypoxic environments. To our knowledge, this study is the first to examine the resting state activity in the PFC associated with working memory in people exposed to moderate altitudes.
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Affiliation(s)
- Xin Chen
- Key Laboratory of Brain, Cognition and Education Sciences, Ministry of Education, South China Normal University, Guangzhou 510631, China
- School of Psychology, South China Normal University, Guangzhou 510631, China
- Institute for Brain Research and Rehabilitation, South China Normal University, Guangzhou 510631, China
- Research Center of Plateau Brain Science, Tibet University/South China University, Guangzhou 510631, China
| | - Aibao Zhou
- College of Psychology, Northwest Normal University, Lanzhou 730070, China
| | - Junle Li
- Institute for Brain Research and Rehabilitation, South China Normal University, Guangzhou 510631, China
| | - Bing Chen
- Jing Hengyi School of Education, Hangzhou Normal University, Hangzhou 311121, China
| | - Xin Zhou
- Center for Cognition and Brain Disorders, The Affiliated Hospital of Hangzhou Normal University, Hangzhou 311121, China
| | - Hailin Ma
- Plateau Brain Science Research Center, Tibet University/South China Normal University, Lhasa 850012, China
| | - Chunming Lu
- State Key Laboratory of Cognitive Neuroscience and Learning and IDG/McGovern Institute for Brain Research, Faculty of Psychology, Beijing Normal University, Beijing 100875, China
- Correspondence: (C.L.); (X.W.)
| | - Xuchu Weng
- Key Laboratory of Brain, Cognition and Education Sciences, Ministry of Education, South China Normal University, Guangzhou 510631, China
- Institute for Brain Research and Rehabilitation, South China Normal University, Guangzhou 510631, China
- Research Center of Plateau Brain Science, Tibet University/South China University, Guangzhou 510631, China
- Correspondence: (C.L.); (X.W.)
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13
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Lee JW, Sreepada LP, Bevers MB, Li K, Scirica BM, Santana da Silva D, Henderson GV, Bay C, Lin AP. Magnetic Resonance Spectroscopy of Hypoxic-Ischemic Encephalopathy After Cardiac Arrest. Neurology 2022; 98:e1226-e1237. [PMID: 35017308 PMCID: PMC8967333 DOI: 10.1212/wnl.0000000000013297] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2021] [Accepted: 12/27/2021] [Indexed: 11/15/2022] Open
Abstract
BACKGROUND AND OBJECTIVES To correlate brain metabolites with clinical outcome using magnetic resonance spectroscopy (MRS) in patients undergoing targeted temperature management (TTM) after cardiac arrest and assess their relationships to MRI and EEG variables. METHODS A prospective cohort of 50 patients was studied. The primary outcome was coma recovery to follow commands. Comparison of MRS measures in the posterior cingulate gyrus, parietal white matter, basal ganglia, and brainstem were also made to 25 normative controls. RESULTS Fourteen of 50 patients achieved coma recovery before hospital discharge. There was a significant decrease in total N-acetylaspartate (NAA/Cr) and an increase in lactate/creatine (Lac/Cr) in patients who did not recover, with changes most prominent in the posterior cingulate gyrus. Patients who recovered had decrease in NAA/Cr as compared to controls. NAA/Cr had a strong monotonic relationship with MRI cortical apparent diffusion coefficient (ADC); Lac level exponentially increased with decreasing ADC. EEG suppression/burst suppression was strongly associated with Lac elevation. DISCUSSION NAA and Lac changes are associated with clinical/MRI/EEG changes consistent with hypoxic-ischemic encephalopathy (HIE) and are most prominent in the posterior cingulate gyrus. NAA/Cr decrease observed in patients with good outcomes suggests mild HIE in patients asymptomatic at hospital discharge. The appearance of cortical Lac represents a deterioration of aerobic energy metabolism and is associated with EEG background suppression, synaptic transmission failure, and severe, potentially irreversible HIE. CLASSIFICATION OF EVIDENCE This study provides Class IV evidence that in patients undergoing TTM after cardiac arrest, brain MRS-determined decrease in total NAA/Cr and an increase in Lac/Cr are associated with an increased risk of not recovering.
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Affiliation(s)
- Jong Woo Lee
- From the Department of Neurology (J.W.L., M.B., K.L., G.V.H.), Department of Radiology (L.S., C.B., A.P.L.), and Department of Medicine, Division of Cardiology (B.S., D.S.d.S.), Brigham and Women's Hospital, Boston, MA
| | - Lasya P Sreepada
- From the Department of Neurology (J.W.L., M.B., K.L., G.V.H.), Department of Radiology (L.S., C.B., A.P.L.), and Department of Medicine, Division of Cardiology (B.S., D.S.d.S.), Brigham and Women's Hospital, Boston, MA
| | - Matthew B Bevers
- From the Department of Neurology (J.W.L., M.B., K.L., G.V.H.), Department of Radiology (L.S., C.B., A.P.L.), and Department of Medicine, Division of Cardiology (B.S., D.S.d.S.), Brigham and Women's Hospital, Boston, MA
| | - Karen Li
- From the Department of Neurology (J.W.L., M.B., K.L., G.V.H.), Department of Radiology (L.S., C.B., A.P.L.), and Department of Medicine, Division of Cardiology (B.S., D.S.d.S.), Brigham and Women's Hospital, Boston, MA.
| | - Benjamin M Scirica
- From the Department of Neurology (J.W.L., M.B., K.L., G.V.H.), Department of Radiology (L.S., C.B., A.P.L.), and Department of Medicine, Division of Cardiology (B.S., D.S.d.S.), Brigham and Women's Hospital, Boston, MA
| | - Danuzia Santana da Silva
- From the Department of Neurology (J.W.L., M.B., K.L., G.V.H.), Department of Radiology (L.S., C.B., A.P.L.), and Department of Medicine, Division of Cardiology (B.S., D.S.d.S.), Brigham and Women's Hospital, Boston, MA
| | - Galen V Henderson
- From the Department of Neurology (J.W.L., M.B., K.L., G.V.H.), Department of Radiology (L.S., C.B., A.P.L.), and Department of Medicine, Division of Cardiology (B.S., D.S.d.S.), Brigham and Women's Hospital, Boston, MA
| | - Camden Bay
- From the Department of Neurology (J.W.L., M.B., K.L., G.V.H.), Department of Radiology (L.S., C.B., A.P.L.), and Department of Medicine, Division of Cardiology (B.S., D.S.d.S.), Brigham and Women's Hospital, Boston, MA
| | - Alexander P Lin
- From the Department of Neurology (J.W.L., M.B., K.L., G.V.H.), Department of Radiology (L.S., C.B., A.P.L.), and Department of Medicine, Division of Cardiology (B.S., D.S.d.S.), Brigham and Women's Hospital, Boston, MA.
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14
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Comparative transcriptome analysis provides novel insights into the molecular mechanism of the silver carp (Hypophthalmichthys molitrix) brain in response to hypoxia stress. COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY. PART D, GENOMICS & PROTEOMICS 2022; 41:100951. [PMID: 34923202 DOI: 10.1016/j.cbd.2021.100951] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/21/2021] [Revised: 12/06/2021] [Accepted: 12/08/2021] [Indexed: 02/05/2023]
Abstract
The brain of fish plays an important role in regulating growth and adapting to environmental changes. However, few studies have been performed to address the changes in gene expression profiles in fish brains under hypoxic stress. In the present study, silver carp (Hypophthalmichthys molitrix) were kept under hypoxic experimental conditions by using the method of natural oxygen consumption, which resulted in a significant decrease in malondialdehyde (MDA) and glutathione (GSH) content and superoxide dismutase (SOD) activity in the brain. In addition, RNA sequencing (RNA-Seq) was performed to analyze transcriptional regulation in the brains of silver carp under normoxia (control group), hypoxia, semi-asphyxia, and asphyxia conditions. The results of KEGG enrichment pathway analysis showed that the immune system, such as antigen processing and presentation, natural killer cell-mediated cytotoxicity, was enriched in the hypoxia group; the nervous system (e.g., "glutamatergic synapse"), signal transduction (e.g., "calcium signaling pathway"; "foxo signaling pathway"), and signaling molecules and interactions (e.g., "neuroactive ligand-receptor interaction") were enriched in the semi-asphyxia group; and signaling molecules and interactions (e.g., "neuroactive ligand-receptor interaction") were enriched in the asphyxia group. These results provide novel insights into the molecular regulatory mechanism of the fish brain coping with hypoxia stress.
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15
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Horiuchi M, Rossetti GM, Oliver SJ. Dietary nitrate supplementation effect on dynamic cerebral autoregulation in normoxia and acute hypoxia. J Cereb Blood Flow Metab 2022; 42:486-494. [PMID: 32151227 PMCID: PMC8985441 DOI: 10.1177/0271678x20910053] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
We tested the hypothesis that increasing the nitric oxide (NO) bioavailability by dietary nitrate would recover the hypoxia-induced reduction in dynamic cerebral autoregulation (CA). Twelve healthy males (age 21 ± 2 years) completed four days of dietary supplementation with a placebo or inorganic nitrate drink (140-ml beetroot juice per day) followed by 60-min of normoxia or hypoxia (fraction of inspired oxygen [FiO2] = 13%). Duplex ultrasonography was used to perform volumetric change-based assessment of dynamic CA in the internal carotid artery (ICA). Dynamic CA was assessed by rate of regulation (RoR) of vascular conductance using the thigh-cuff method. Four days of beetroot supplementation increased circulating nitrate by 208 [171,245] μM (mean difference [95% confidence interval]) compared with placebo. Dynamic CA was lower in hypoxia than normoxia (RoR Δ-0.085 [-0.116, -0.054]). Compared with placebo, nitrate did not alter dynamic CA in normoxia (RoR Δ-0.022 [-0.060, 0.016]) or hypoxia (RoR Δ0.017 [-0.019, 0.053]). Further, nitrate did not affect ICA vessel diameter, blood velocity or flow in either normoxia or hypoxia. Increased bioavailability of NO through dietary nitrate supplementation did not recover the hypoxia-induced reduction in dynamic CA. This suggests the mechanism of hypoxia-induced reduction in dynamic CA does not relate to the availability of NO.
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Affiliation(s)
- Masahiro Horiuchi
- Division of Human Environmental Science, Mt. Fuji Research Institute, Fujiyoshida, Japan
| | - Gabriella Mk Rossetti
- Extremes Research Group, College of Human Sciences, Bangor University, Bangor, Wales
| | - Samuel J Oliver
- Extremes Research Group, College of Human Sciences, Bangor University, Bangor, Wales
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16
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Vakharia RJ, Jani I, Yadav S, Kurian T. To Study Acute Changes in Brain Oxygenation on MRI in Healthcare Workers Using N95 Mask and PPE Kits for Six Hours a Day. Indian J Radiol Imaging 2022; 31:893-900. [PMID: 35136502 PMCID: PMC8817801 DOI: 10.1055/s-0041-1741086] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
Background
Due to long working hours wearing an N95 mask and PPE kit during the COVID-19 pandemic, the healthcare workers (HCWs) complained of headaches, confusion, and exhaustion. This study was therefore performed to study the changes in brain oxygenation.
Aim
To compare brain oxygenation in health care workers wearing an N95 mask with a PPE kit versus a three-ply mask during an intensive care setting for 6 hours.
Materials and Methods
Thirty clinicians and 30 paramedical staff participated in the study. The control (three-ply mask) and subject (N95 mask with PPE) groups included 15 clinicians and 15 paramedical staff. A comparative analysis of brain oxygenation using a 3T magnetic resonance imaging (MRI) machine was performed in these two groups at the beginning and the end of their work shift.
Results
The mean age of the individuals in the control and subject groups was 30.8 and 30.13 years, respectively. The median value of brain oxygenation in the control and subject groups in the pre-shift was between 33 and 31 and post-shift was 30 and 24. The drop in brain oxygenation in subjects was more than the controls (
p
= 0.004) in the post-shift assessments. The cerebral blood flow (CBF) in the bilateral middle cerebral artery (MCA) using arterial spin labeling (ASL) showed a rise in CBF in both groups post-shift as compared with the pre-shift values. The median values of the right and left MCA in the control and subject groups pre-shift were 82.75/83.45 and 89.75/106.65. The post-shift median values of both MCAs of the control and subject groups were 115.65/115.55 and 109.60/119.49.
Conclusion
MRI-BOLD imaging revealed a significant drop in brain oxygenation in the subject group as compared with the control group. Multiphasic-ASL showed a compensatory rise in CBF in both groups.
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Affiliation(s)
| | - Ishaan Jani
- Department of Radiodiagnosis, Wockhardt Hospital, Mumbai, Maharashtra, India
| | - Shashibala Yadav
- Department of Radiodiagnosis, Wockhardt Hospital, Mumbai, Maharashtra, India
| | - Thomas Kurian
- MRI Applications, Philips India Limited, Mumbai, Maharashtra, India
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17
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Wang X, Cui L, Ji X. Cognitive impairment caused by hypoxia: from clinical evidences to molecular mechanisms. Metab Brain Dis 2022; 37:51-66. [PMID: 34618295 DOI: 10.1007/s11011-021-00796-3] [Citation(s) in RCA: 22] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Accepted: 07/09/2021] [Indexed: 12/23/2022]
Abstract
Hypoxia is a state of reduced oxygen supply and excessive oxygen consumption. According to the duration of hypoxic period, it can be classified as acute and chronic hypoxia. Both acute and chronic hypoxia could induce abundant neurological deficits. Although there have been significant advances in the pathophysiological injuries, few studies have focused on the cognitive dysfunction. In this review, we focused on the clinical evidences and molecular mechanisms of cognitive impairment under acute and chronic hypoxia. Hypoxia can impair several cognitive domains such as attention, learning and memory, procession speed and executive function, which are similar in acute and chronic hypoxia. The severity of cognitive deficit correlates with the duration and degree of hypoxia. Recovery can be achieved after acute hypoxia, while sequelae or even dementia can be observed after chronic hypoxia, perhaps due to the different molecular mechanisms. Cardiopulmonary compensatory response, glycolysis, oxidative stress, calcium overload, adenosine, mitochondrial disruption, inflammation and excitotoxicity contribute to the molecular mechanisms of cognitive deficit after acute hypoxia. During the chronic stage of hypoxia, different adaptive responses, impaired neurovascular coupling, apoptosis, transcription factors-mediated inflammation, as well as Aβ accumulation and tau phosphorylation account for the neurocognitive deficit. Moreover, brain structural changes with hippocampus and cortex atrophy, ventricle enlargement, senile plaque and neurofibrillary tangle deposition can be observed under chronic hypoxia rather than acute hypoxia.
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Affiliation(s)
- Xiaoyin Wang
- Department of Neurology, Xuanwu Hospital of Capital Medical University, Beijing, China
- Beijing Institute for Brain Disorders, Capital Medical University, Beijing, China
| | - Lili Cui
- Department of Neurology, Xuanwu Hospital of Capital Medical University, Beijing, China
| | - Xunming Ji
- Beijing Institute for Brain Disorders, Capital Medical University, Beijing, China.
- Department of Neurosurgery, Xuanwu Hospital of Capital Medical University, No 45, Changchun Street, Beijing, 100053, Xicheng District, China.
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18
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Effects of hyperventilation with face mask on brain network in patients with epilepsy. Epilepsy Res 2021; 176:106741. [PMID: 34418857 DOI: 10.1016/j.eplepsyres.2021.106741] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2021] [Revised: 07/20/2021] [Accepted: 08/12/2021] [Indexed: 12/28/2022]
Abstract
OBJECTIVES During the ongoing pandemic of COVID-19, wearing face masks was recommended, including patients with epilepsy doing the hyperventilation (HV) test during electroencephalogram (EEG) examination somewhere. However, evidence was still limited about the effect of HV with face mask on cortical excitability of patients with epilepsy. The motivation of this work is to make use of the graph theory of EEG to characterize the cortical excitability of patients with epilepsy when they did HV under the condition wearing a surgical face mask. METHODS We recruited 19 patients with epilepsy and 17 normal controls. All of participants completed two HV experiments, including HV with face mask (HV+) and HV without a mask (HV). The interval was 30 min and the sequence was random. Each experiment consisted of three segments: resting EEG, EEG of HV, and EEG of post-HV. EEG were recorded successively during each experiment. Participants were asked to evaluate the discomfort degree using a questionnaire when every HV is completed. RESULTS All of the participants felt more uncomfortable after HV + . Moreover, not only HV decreased small-worldness index in patients with epilepsy, but also HV + significantly increased the clustering coefficient in patients with epilepsy. Importantly, the three-way of Mask*HV*Epilepsy showed interaction in the clustering coefficient in the delta band, as well as in the path length and the small-worldness index in the theta band. CONCLUSIONS The results of this study indicated that patients with epilepsy showed the increased excitability of brain network during HV + . We should pay more attention to the adverse effect on brain network excitability caused by HV + in patients with epilepsy. In the clinical practice under the COVID-19 pandemic, it is important that the wearing face mask remain cautious for the individuals with epilepsy when they carried out HV behavior such as exercise (e.g., running, etc.).
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19
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Keough JRG, Cates VC, Tymko MM, Boulet LM, Jamieson AN, Foster GE, Day TA. Regional differences in cerebrovascular reactivity in response to acute isocapnic hypoxia in healthy humans: Methodological considerations. Respir Physiol Neurobiol 2021; 294:103770. [PMID: 34343693 DOI: 10.1016/j.resp.2021.103770] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2021] [Revised: 07/15/2021] [Accepted: 07/29/2021] [Indexed: 11/30/2022]
Abstract
The cerebrovasculature responds to blood gas challenges. Regional differences (anterior vs. posterior) in cerebrovascular responses to increases in CO2 have been extensively studied. However, regional cerebrovascular reactivity (CVR) responses to low O2 (hypoxia) are equivocal, likely due to differences in analysis. We assessed the effects of acute isocapnic hypoxia on regional CVR comparing absolute and relative (%-change) responses in the middle cerebral artery (MCA) and posterior cerebral artery (PCA). We instrumented 14 healthy participants with a transcranial Doppler ultrasound (cerebral blood velocity), finometer (beat-by-beat blood pressure), dual gas analyzer (end-tidal CO2 and O2), and utilized a dynamic end-tidal forcing system to elicit a single 5-min bout of isocapnic hypoxia (∼45 Torr PETO2, ∼80 % SpO2). During exposure to acute hypoxia, absolute responses were larger in the anterior compared to posterior cerebral circulation (P < 0.001), but were not different when comparing relative responses (P = 0.45). Consistent reporting of CVR to hypoxia will aid understanding normative responses, particularly in assessing populations with impaired cerebrovascular function.
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Affiliation(s)
- Joanna R G Keough
- Department of Biology, Faculty of Science and Technology, Mount Royal University, Calgary, Alberta, Canada
| | - Valerie C Cates
- Department of Biology, Faculty of Science and Technology, Mount Royal University, Calgary, Alberta, Canada
| | - Michael M Tymko
- Department of Biology, Faculty of Science and Technology, Mount Royal University, Calgary, Alberta, Canada; Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, British Columbia, Canada; Faculty of Kinesiology, Sport and Recreation, University of Alberta, Edmonton, Alberta, Canada
| | - Lindsey M Boulet
- Department of Biology, Faculty of Science and Technology, Mount Royal University, Calgary, Alberta, Canada; Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, British Columbia, Canada
| | - Alenna N Jamieson
- Department of Biology, Faculty of Science and Technology, Mount Royal University, Calgary, Alberta, Canada
| | - Glen E Foster
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, British Columbia, Canada
| | - Trevor A Day
- Department of Biology, Faculty of Science and Technology, Mount Royal University, Calgary, Alberta, Canada.
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20
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Troy AM, Cheng HM. Human microvascular reactivity: a review of vasomodulating stimuli and non-invasive imaging assessment. Physiol Meas 2021; 42. [PMID: 34325417 DOI: 10.1088/1361-6579/ac18fd] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Accepted: 07/29/2021] [Indexed: 11/11/2022]
Abstract
The microvasculature serves an imperative function in regulating perfusion and nutrient exchange throughout the body, adaptively altering blood flow to preserve hemodynamic and metabolic homeostasis. Its normal functioning is vital to tissue health, whereas its dysfunction is present in many chronic conditions, including diabetes, heart disease, and cognitive decline. As microvascular dysfunction often appears early in disease progression, its detection can offer early diagnostic information. To detect microvascular dysfunction, one uses imaging to probe the microvasculature's ability to react to a stimulus, also known as microvascular reactivity (MVR). An assessment of MVR requires an integrated understanding of vascular physiology, techniques for stimulating reactivity, and available imaging methods to capture the dynamic response. Practical considerations, including compatibility between the selected stimulus and imaging approach, likewise require attention. In this review, we provide a comprehensive foundation necessary for informed imaging of MVR, with a particular focus on the challenging endeavor of assessing microvascular function in deep tissues.
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Affiliation(s)
- Aaron M Troy
- Institute of Biomedical Engineering, University of Toronto, Toronto, CANADA
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21
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Friend AT, Rogan M, Rossetti GMK, Lawley JS, Mullins PG, Sandoo A, Macdonald JH, Oliver SJ. Bilateral regional extracranial blood flow regulation to hypoxia and unilateral duplex ultrasound measurement error. Exp Physiol 2021; 106:1535-1548. [PMID: 33866627 DOI: 10.1113/ep089196] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2020] [Accepted: 04/14/2021] [Indexed: 02/05/2023]
Abstract
NEW FINDINGS What is the central question of this study? Is blood flow regulation to hypoxia different between the internal carotid arteries (ICAs) and vertebral arteries (VAs), and what is the measurement error in unilateral extracranial artery assessments compared to bilateral? What is the main finding and its importance? ICA and VA blood flow regulation to hypoxia is comparable when factoring for vessel type and vessel side. Compared to bilateral assessment, vessels assessed unilaterally had individual measurement errors of up to 37%. Assessing the vessel with the larger resting blood flow, not the left or right vessel, reduces unilateral measurement error. ABSTRACT Whether blood flow regulation to hypoxia is similar between left and right internal carotid arteries (ICAs) and vertebral arteries (VAs) is unclear. Extracranial blood flow is regularly calculated by doubling a unilateral assessment; however, lateral artery differences may lead to measurement error. This study aimed to determine extracranial blood flow regulation to hypoxia when factoring for vessel type (ICAs or VAs) and vessel side (left or right) effects, and to investigate unilateral assessment measurement error compared to bilateral assessment. In a repeated-measures crossover design, extracranial arteries of 44 participants were assessed bilaterally by duplex ultrasound during 90 min of normoxic and poikilocapnic hypoxic (12.0% fraction of inspired oxygen) conditions. Linear mixed model analyses revealed no Condition × Vessel Type × Vessel Side interaction for blood flow, vessel diameter and flow velocity (all P > 0.05) indicating left and right ICA and VA blood flow regulation to hypoxia was similar. Bilateral hypoxic reactivity was comparable (ICAs, 1.4 (1.0) vs. VAs, 1.7 (1.1) Δ%·Δ S p O 2 -1 ; P = 0.12). Compared to bilateral assessment, unilateral mean measurement error of the relative blood flow response to hypoxia was up to 5%, but individual errors reached 37% and were greatest in ICAs and VAs with the smaller resting blood flow due to a ratio-scaling problem. In conclusion, left and right ICA and VA regulation to hypoxia is comparable when factoring for vessel type and vessel side. Assessing the ICA and VA vessels with the larger resting blood flow, not the left or right vessel, reduces unilateral measurement error.
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Affiliation(s)
- Alexander T Friend
- Extremes Research Group, School of Sport, Health and Exercise Sciences, College of Human Sciences, Bangor University, Bangor, UK
| | - Matthew Rogan
- Bangor Imaging Unit, School of Psychology, College of Human Sciences, Bangor University, Bangor, UK
| | - Gabriella M K Rossetti
- Extremes Research Group, School of Sport, Health and Exercise Sciences, College of Human Sciences, Bangor University, Bangor, UK.,Centre for Integrative Neuroscience and Neurodynamics, School of Psychology and Clinical Language Sciences, University of Reading, Reading, UK
| | - Justin S Lawley
- Department of Sport Science, Division of Physiology, University of Innsbruck, Innsbruck, Austria
| | - Paul G Mullins
- Bangor Imaging Unit, School of Psychology, College of Human Sciences, Bangor University, Bangor, UK
| | - Aamer Sandoo
- Extremes Research Group, School of Sport, Health and Exercise Sciences, College of Human Sciences, Bangor University, Bangor, UK
| | - Jamie H Macdonald
- Extremes Research Group, School of Sport, Health and Exercise Sciences, College of Human Sciences, Bangor University, Bangor, UK
| | - Samuel J Oliver
- Extremes Research Group, School of Sport, Health and Exercise Sciences, College of Human Sciences, Bangor University, Bangor, UK
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22
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Turner REF, Gatterer H, Falla M, Lawley JS. High-altitude cerebral edema: its own entity or end-stage acute mountain sickness? J Appl Physiol (1985) 2021; 131:313-325. [PMID: 33856254 DOI: 10.1152/japplphysiol.00861.2019] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
High-altitude cerebral edema (HACE) and acute mountain sickness (AMS) are neuropathologies associated with rapid exposure to hypoxia. However, speculation remains regarding the exact etiology of both HACE and AMS and whether they share a common mechanistic pathology. This review outlines the basic principles of HACE development, highlighting how edema could develop from 1) a progression from cytotoxic swelling to ionic edema or 2) permeation of the blood brain barrier (BBB) with or without ionic edema. Thereafter, discussion turns to the available neuroimaging literature in the context of cytotoxic, ionic, or vasogenic edema in both HACE and AMS. Although HACE is clearly caused by an increase in brain water of ionic and/or vasogenic origin, there is very little evidence that this type of edema is present when AMS develops. However, cerebral vasodilation, increased intracranial blood volume, and concomitant intracranial fluid shifts from the extracellular to the intracellular space, as interpreted from changes in diffusion indices within white matter, are observed consistently in persons acutely exposed to hypoxia and with AMS. Therefore, herein we explore the idea that intracellular swelling occurs alongside AMS, and is a critical precursor to extracellular ionic edema formation. We propose that this process produces a subtle modulation of the BBB, which either together with or independent of vasogenic edema provides a transvascular segue from the end-stage of AMS to HACE. Ultimately, this review seeks to shed light on the possible processes underlying HACE pathophysiology, and thus highlights potential avenues for future prevention and treatment.
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Affiliation(s)
- Rachel E F Turner
- Institute of Mountain Emergency Medicine, Eurac Research, Bolzano, Italy
| | - Hannes Gatterer
- Institute of Mountain Emergency Medicine, Eurac Research, Bolzano, Italy
| | - Marika Falla
- Center for Mind/Brain Sciences and Centre for Neurocognitive Rehabilitation, University of Trento, Rovereto, Italy
| | - Justin S Lawley
- Division of Performance Physiology & Prevention, Department of Sport Science, University of Innsbruck, Innsbruck, Austria
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23
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Rossetti GM, d'Avossa G, Rogan M, Macdonald JH, Oliver SJ, Mullins PG. Reversal of neurovascular coupling in the default mode network: Evidence from hypoxia. J Cereb Blood Flow Metab 2021; 41:805-818. [PMID: 32538282 PMCID: PMC7983511 DOI: 10.1177/0271678x20930827] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Local changes in cerebral blood flow are thought to match changes in neuronal activity, a phenomenon termed neurovascular coupling. Hypoxia increases global resting cerebral blood flow, but regional cerebral blood flow (rCBF) changes are non-uniform. Hypoxia decreases baseline rCBF to the default mode network (DMN), which could reflect either decreased neuronal activity or altered neurovascular coupling. To distinguish between these hypotheses, we characterized the effects of hypoxia on baseline rCBF, task performance, and the hemodynamic (BOLD) response to task activity. During hypoxia, baseline CBF increased across most of the brain, but decreased in DMN regions. Performance on memory recall and motion detection tasks was not diminished, suggesting task-relevant neuronal activity was unaffected. Hypoxia reversed both positive and negative task-evoked BOLD responses in the DMN, suggesting hypoxia reverses neurovascular coupling in the DMN of healthy adults. The reversal of the BOLD response was specific to the DMN. Hypoxia produced modest increases in activations in the visual attention network (VAN) during the motion detection task, and had no effect on activations in the visual cortex during visual stimulation. This regional specificity may be particularly pertinent to clinical populations characterized by hypoxemia and may enhance understanding of regional specificity in neurodegenerative disease pathology.
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Affiliation(s)
- Gabriella Mk Rossetti
- Extremes Research Group, School of Sport, Health and Exercise Sciences, College of Human Sciences, Bangor University, Bangor, UK
| | - Giovanni d'Avossa
- Bangor Imaging Centre, School of Psychology, College of Human Sciences, Bangor University, Bangor, UK
| | - Matthew Rogan
- Bangor Imaging Centre, School of Psychology, College of Human Sciences, Bangor University, Bangor, UK
| | - Jamie H Macdonald
- Extremes Research Group, School of Sport, Health and Exercise Sciences, College of Human Sciences, Bangor University, Bangor, UK
| | - Samuel J Oliver
- Extremes Research Group, School of Sport, Health and Exercise Sciences, College of Human Sciences, Bangor University, Bangor, UK
| | - Paul G Mullins
- Bangor Imaging Centre, School of Psychology, College of Human Sciences, Bangor University, Bangor, UK
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24
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Sadlon A, Ensslin A, Freystätter G, Gagesch M, Bischoff-Ferrari HA. Are patients with cognitive impairment fit to fly? Current evidence and practical recommendations. J Travel Med 2021; 28:5876266. [PMID: 32710619 DOI: 10.1093/jtm/taaa123] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/02/2020] [Revised: 07/05/2020] [Accepted: 07/20/2020] [Indexed: 12/13/2022]
Abstract
BACKGROUND The worldwide prevalence of dementia is increasing and represents a major public health concern. In the last decades, air travel services have undergone an impressive expansion and one of ten passengers is aged 65 years and older. While air travel can be stressful at all ages and health conditions, older individuals with cognitive impairment carry a greater risk for air-travel-related complications. Consequently, demands to general practitioners for assessing their older patient's fitness to fly are increasing. METHODS We conducted a search of the literature in PubMed on the impact of in-flight environmental changes on passengers with cognitive impairment and possible resulting complications. This set the base for a discussion on pharmacological and non-pharmacological interventions aimed at preventing in-flight complications in this vulnerable population. RESULTS While our research strategy identified a total of 11 articles related to older age and air travel, only three focused on passengers with cognitive impairment. Our literature review showed that the airplane environment may lead to a large spectrum of symptoms in passengers of all age groups. However, passengers with cognitive impairment due to neurodegenerative diseases are at increased risk for experiencing the most extreme symptoms such as acute confusional state. Non-pharmacological and pharmacological interventions at different stages of the travel process (before, during and after) can help prevent complications in this vulnerable population. CONCLUSION The decision to let a patient with cognitive impairment fly requires a solid understanding of the in-flight environmental changes and their impact on older patients with cognitive impairment. Moreover, a sound weighing of the risks and benefits while considering different aspects of the patient's history is demanded. In this regard, the role of the treating physicians and caregivers is essential along with the support of the medical department of the airline.
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Affiliation(s)
- Angélique Sadlon
- Department of Geriatrics, University Hospital Zürich, Switzerland.,Centre on Aging and Mobility, University of Zürich, Switzerland.,Ageing Epidemiology Research Unit, School of Public Health, Imperial College London, UK
| | - Angela Ensslin
- Medical Services, Swiss International Air Lines Ltd., Zürich Airport, Kloten, Switzerland
| | - Gregor Freystätter
- Department of Geriatrics, University Hospital Zürich, Switzerland.,Centre on Aging and Mobility, University of Zürich, Switzerland
| | - Michael Gagesch
- Department of Geriatrics, University Hospital Zürich, Switzerland.,Centre on Aging and Mobility, University of Zürich, Switzerland
| | - Heike A Bischoff-Ferrari
- Department of Geriatrics, University Hospital Zürich, Switzerland.,Centre on Aging and Mobility, University of Zürich, Switzerland
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25
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Liu J, Li S, Qian L, Xu X, Zhang Y, Cheng J, Zhang W. Effects of acute mild hypoxia on cerebral blood flow in pilots. Neurol Sci 2020; 42:673-680. [PMID: 32654008 DOI: 10.1007/s10072-020-04567-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2020] [Accepted: 07/02/2020] [Indexed: 11/30/2022]
Abstract
BACKGROUND Pilots often face and need to overcome a diverse range of unfavorable conditions, of which hypoxic exposure is the most common. Studies have reported that hypoxia can induce a decrease in cerebral blood flow (CBF) in the brains of both humans and animals. Hypoxia and the associated cerebral hemodynamic changes can contribute to cognitive performance deficits that may endanger flight safety and increase the risk of accidents. AIM In this study, we aimed to identify region-specific alterations in CBF in male pilots after exposure to hypoxia. MATERIAL AND METHODS We used 3D pseudo-continuous arterial spin labeling sequences in 35 healthy male pilots (mean age: 30.6 ± 4.82 years) under simulated hypoxic conditions with a 3.0-T magnetic resonance imaging scanner. The generated CBF maps were measured and averaged in several regions of interest. RESULTS Hypoxia decreased CBF in various brain regions, including the right temporal and bilateral occipital lobes, the anterior and posterior lobes of the cerebellum, the culmen and declive, and the inferior semilunar lobule of the cerebellum. CONCLUSION These changes may impact the functional activity of the brains of pilots experiencing hypoxia in flight, but the related mechanisms require further investigation.
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Affiliation(s)
- Jie Liu
- Department of MRI, The First Affiliated Hospital of Zhengzhou University, No.1 Jianshe Dong Road, Erqi District, Zhengzhou, Henan Province, China
| | - Shujian Li
- Department of MRI, The First Affiliated Hospital of Zhengzhou University, No.1 Jianshe Dong Road, Erqi District, Zhengzhou, Henan Province, China
| | - Long Qian
- GE Healthcare China, Floor 1, Yongchang North Road, Beijing Economic and Technological Development Zone, Beijing, China
| | - Xianrong Xu
- Department of Air Duty, The Air Force General Hospital in Beijing, No. 30 Fucheng Road, Haidian District, Beijing, West Diaoyutai, China
| | - Yong Zhang
- Department of MRI, The First Affiliated Hospital of Zhengzhou University, No.1 Jianshe Dong Road, Erqi District, Zhengzhou, Henan Province, China
| | - Jingliang Cheng
- Department of MRI, The First Affiliated Hospital of Zhengzhou University, No.1 Jianshe Dong Road, Erqi District, Zhengzhou, Henan Province, China.
| | - Wanshi Zhang
- Department of Radiology, The Air Force General Hospital in Beijing, No. 30 Fucheng Road, Haidian District, Beijing, West Diaoyutai, China
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26
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Jung M, Brizes I, Wages S, Ponce P, Kang M, Loprinzi PD. Combined effects of acute exercise and hypoxia on memory. Physiol Int 2020; 107:337-348. [PMID: 32644939 DOI: 10.1556/2060.2020.00017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2020] [Accepted: 05/27/2020] [Indexed: 11/19/2022]
Abstract
No previous studies have evaluated the potential combined effects of acute exercise and acute hypoxia exposure on memory function, which was the purpose of this study. Twenty-five participants (Mage = 21.2 years) completed two laboratory visits in a counterbalanced order, involving 1) acute exercise (a 20-min bout of moderate-intensity exercise) and then 30 min of exposure to hypoxia (FIO2 = 0.12), and 2) exposure to hypoxia alone (FIO2 = 0.12) for 30 min. Following this, participants completed a cued-recall and memory interference task (AB/AC paradigm), assessing cued-recall memory (recall 1 and recall 2) and memory interference (proactive and retroactive interference). For cued-recall memory, we observed a significant main effect for condition, with Exercise + Hypoxia condition having significantly greater cued-recall performance than Hypoxia alone. Memory interference did not differ as a function of the experimental condition. This experiment demonstrates that engaging in an acute bout of exercise prior to acute hypoxia exposure had an additive effect in enhancing cued-recall memory performance.
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Affiliation(s)
- M Jung
- 1Exercise & Memory Laboratory, Department of Health, Exercise Science and Recreation Management, The University of Mississippi, University, MS 38677, USA.,2Health and Sport Analytics Laboratory, Department of Health, Exercise Science and Recreation Management, The University of Mississippi, University, MS 38677, USA
| | - I Brizes
- 1Exercise & Memory Laboratory, Department of Health, Exercise Science and Recreation Management, The University of Mississippi, University, MS 38677, USA
| | - S Wages
- 1Exercise & Memory Laboratory, Department of Health, Exercise Science and Recreation Management, The University of Mississippi, University, MS 38677, USA
| | - P Ponce
- 1Exercise & Memory Laboratory, Department of Health, Exercise Science and Recreation Management, The University of Mississippi, University, MS 38677, USA
| | - M Kang
- 2Health and Sport Analytics Laboratory, Department of Health, Exercise Science and Recreation Management, The University of Mississippi, University, MS 38677, USA
| | - P D Loprinzi
- 1Exercise & Memory Laboratory, Department of Health, Exercise Science and Recreation Management, The University of Mississippi, University, MS 38677, USA
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27
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Gibbons TD, Tymko MM, Thomas KN, Wilson LC, Stembridge M, Caldwell HG, Howe CA, Hoiland RL, Akerman AP, Dawkins TG, Patrician A, Coombs GB, Gasho C, Stacey BS, Ainslie PN, Cotter JD. Global REACH 2018: The influence of acute and chronic hypoxia on cerebral haemodynamics and related functional outcomes during cold and heat stress. J Physiol 2020; 598:265-284. [PMID: 31696936 DOI: 10.1113/jp278917] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2019] [Accepted: 10/28/2019] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS Thermal and hypoxic stress commonly coexist in environmental, occupational and clinical settings, yet how the brain tolerates these multi-stressor environments is unknown Core cooling by 1.0°C reduced cerebral blood flow (CBF) by 20-30% and cerebral oxygen delivery (CDO2 ) by 12-19% at sea level and high altitude, whereas core heating by 1.5°C did not reliably reduce CBF or CDO2 Oxygen content in arterial blood was fully restored with acclimatisation to 4330 m, but concurrent cold stress reduced CBF and CDO2 Gross indices of cognition were not impaired by any combination of thermal and hypoxic stress despite large reductions in CDO2 Chronic hypoxia renders the brain susceptible to large reductions in oxygen delivery with concurrent cold stress, which might make monitoring core temperature more important in this context ABSTRACT: Real-world settings are composed of multiple environmental stressors, yet the majority of research in environmental physiology investigates these stressors in isolation. The brain is central in both behavioural and physiological responses to threatening stimuli and, given its tight metabolic and haemodynamic requirements, is particularly susceptible to environmental stress. We measured cerebral blood flow (CBF, duplex ultrasound), cerebral oxygen delivery (CDO2 ), oesophageal temperature, and arterial blood gases during exposure to three commonly experienced environmental stressors - heat, cold and hypoxia - in isolation, and in combination. Twelve healthy male subjects (27 ± 11 years) underwent core cooling by 1.0°C and core heating by 1.5°C in randomised order at sea level; acute hypoxia ( P ET , O 2 = 50 mm Hg) was imposed at baseline and at each thermal extreme. Core cooling and heating protocols were repeated after 16 ± 4 days residing at 4330 m to investigate any interactions with high altitude acclimatisation. Cold stress decreased CBF by 20-30% and CDO2 by 12-19% (both P < 0.01) irrespective of altitude, whereas heating did not reliably change either CBF or CDO2 (both P > 0.08). The increases in CBF with acute hypoxia during thermal stress were appropriate to maintain CDO2 at normothermic, normoxic values. Reaction time was faster and slower by 6-9% with heating and cooling, respectively (both P < 0.01), but central (brain) processes were not impaired by any combination of environmental stressors. These findings highlight the powerful influence of core cooling in reducing CDO2 . Despite these large reductions in CDO2 with cold stress, gross indices of cognition remained stable.
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Affiliation(s)
- T D Gibbons
- School of Physical Education, Sport & Exercise Science, University of Otago, 55/47 Union St W, Dunedin, 9016, New Zealand
| | - M M Tymko
- Centre for Heart, Lung and Vascular Health, University of British Columbia-Okanagan Campus, School of Health and Exercise Sciences, 3333 University Way, Kelowna, British Columbia, Canada, V1V 1V7
| | - K N Thomas
- Department of Surgical Sciences, University of Otago, 201 Great King St, Dunedin, 9016, New Zealand
| | - L C Wilson
- Department of Medicine, University of Otago, 201 Great King St, Dunedin, 9016, New Zealand
| | - M Stembridge
- Cardiff Centre for Exercise and Health, Cardiff Metropolitan University, Cyncoed Road, Cardiff, CF23 6XD, UK
| | - H G Caldwell
- Centre for Heart, Lung and Vascular Health, University of British Columbia-Okanagan Campus, School of Health and Exercise Sciences, 3333 University Way, Kelowna, British Columbia, Canada, V1V 1V7
| | - C A Howe
- Centre for Heart, Lung and Vascular Health, University of British Columbia-Okanagan Campus, School of Health and Exercise Sciences, 3333 University Way, Kelowna, British Columbia, Canada, V1V 1V7
| | - R L Hoiland
- Centre for Heart, Lung and Vascular Health, University of British Columbia-Okanagan Campus, School of Health and Exercise Sciences, 3333 University Way, Kelowna, British Columbia, Canada, V1V 1V7
| | - A P Akerman
- Faculty of Health Sciences, University of Ottawa, 125 University St, Ottawa, Ontario, Canada, K1N 6N5
| | - T G Dawkins
- Cardiff Centre for Exercise and Health, Cardiff Metropolitan University, Cyncoed Road, Cardiff, CF23 6XD, UK
| | - A Patrician
- Centre for Heart, Lung and Vascular Health, University of British Columbia-Okanagan Campus, School of Health and Exercise Sciences, 3333 University Way, Kelowna, British Columbia, Canada, V1V 1V7
| | - G B Coombs
- Centre for Heart, Lung and Vascular Health, University of British Columbia-Okanagan Campus, School of Health and Exercise Sciences, 3333 University Way, Kelowna, British Columbia, Canada, V1V 1V7
| | - C Gasho
- Division of Pulmonary, Critical Care, Hyperbaric and Sleep Medicine, Loma Linda University School of Medicine, Loma Linda, CA, USA
| | - B S Stacey
- Neurovascular Research Laboratory, Faculty of Life Sciences and Education, University of South Wales, UK
| | - P N Ainslie
- Centre for Heart, Lung and Vascular Health, University of British Columbia-Okanagan Campus, School of Health and Exercise Sciences, 3333 University Way, Kelowna, British Columbia, Canada, V1V 1V7
| | - J D Cotter
- School of Physical Education, Sport & Exercise Science, University of Otago, 55/47 Union St W, Dunedin, 9016, New Zealand
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28
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Kellawan JM, Peltonen GL, Harrell JW, Roldan-Alzate A, Wieben O, Schrage WG. Differential contribution of cyclooxygenase to basal cerebral blood flow and hypoxic cerebral vasodilation. Am J Physiol Regul Integr Comp Physiol 2019; 318:R468-R479. [PMID: 31868517 DOI: 10.1152/ajpregu.00132.2019] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Cyclooxygenase (COX) is proposed to regulate cerebral blood flow (CBF); however, accurate regional contributions of COX are relatively unknown at baseline and particularly during hypoxia. We hypothesized that COX contributes to both basal and hypoxic cerebral vasodilation, but COX-mediated vasodilation is greater in the posterior versus anterior cerebral circulation. CBF was measured in 9 healthy adults (28 ± 4 yr) during normoxia and isocapnic hypoxia (fraction of inspired oxygen = 0.11), with COX inhibition (oral indomethacin, 100mg) or placebo. Four-dimensional flow magnetic resonance imaging measured cross-sectional area (CSA) and blood velocity to quantify CBF in 11 cerebral arteries. Cerebrovascular conductance (CVC) was calculated (CVC = CBF × 100/mean arterial blood pressure) and hypoxic reactivity was expressed as absolute and relative change in CVC [ΔCVC/Δ pulse oximetry oxygen saturation (SpO2)]. At normoxic baseline, indomethacin reduced CVC by 44 ± 5% (P < 0.001) and artery CSA (P < 0.001), which was similar across arteries. Hypoxia (SpO2 80%-83%) increased CVC (P < 0.01), reflected as a similar relative increase in reactivity (% ΔCVC/-ΔSpO2) across arteries (P < 0.05), in part because of increases in CSA (P < 0.05). Indomethacin did not alter ΔCVC or ΔCVC/ΔSpO2 to hypoxia. These findings indicate that 1) COX contributes, in a largely uniform fashion, to cerebrovascular tone during normoxia and 2) COX is not obligatory for hypoxic vasodilation in any regions supplied by large extracranial or intracranial arteries.
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Affiliation(s)
- J Mikhail Kellawan
- Department of Kinesiology, University of Wisconsin, Madison, Wisconsin.,Department of Health and Exercise Science, University of Oklahoma, Norman, OK
| | - Garrett L Peltonen
- Department of Kinesiology, University of Wisconsin, Madison, Wisconsin.,Department of Kinesiology, Western New Mexico University, Silver City, New Mexico
| | - John W Harrell
- Department of Kinesiology, University of Wisconsin, Madison, Wisconsin
| | - Alejandro Roldan-Alzate
- Department of Radiology, University of Wisconsin, Madison, Wisconsin.,Department of Mechanical Engineering, University of Wisconsin, Madison, Wisconsin
| | - Oliver Wieben
- Department of Medical Physics, University of Wisconsin, Madison, Wisconsin
| | - William G Schrage
- Department of Kinesiology, University of Wisconsin, Madison, Wisconsin
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29
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Ando S, Komiyama T, Sudo M, Higaki Y, Ishida K, Costello JT, Katayama K. The interactive effects of acute exercise and hypoxia on cognitive performance: A narrative review. Scand J Med Sci Sports 2019; 30:384-398. [PMID: 31605635 DOI: 10.1111/sms.13573] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2019] [Revised: 09/09/2019] [Accepted: 10/04/2019] [Indexed: 12/13/2022]
Abstract
Acute moderate intensity exercise has been shown to improve cognitive performance. In contrast, hypoxia is believed to impair cognitive performance. The detrimental effects of hypoxia on cognitive performance are primarily dependent on the severity and duration of exposure. In this review, we describe how acute exercise under hypoxia alters cognitive performance, and propose that the combined effects of acute exercise and hypoxia on cognitive performance are mainly determined by interaction among exercise intensity and duration, the severity of hypoxia, and duration of exposure to hypoxia. We discuss the physiological mechanism(s) of the interaction and suggest that alterations in neurotransmitter function, cerebral blood flow, and possibly cerebral metabolism are the primary candidates that determine cognitive performance when acute exercise is combined with hypoxia. Furthermore, acclimatization appears to counteract impaired cognitive performance during prolonged exposure to hypoxia although the precise physiological mechanism(s) responsible for this amelioration remain to be elucidated. This review has implications for sporting, occupational, and recreational activities at terrestrial high altitude where cognitive performance is essential. Further studies are required to understand physiological mechanisms that determine cognitive performance when acute exercise is performed in hypoxia.
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Affiliation(s)
- Soichi Ando
- Graduate School of Informatics and Engineering, The University of Electro-Communications, Tokyo, Japan
| | - Takaaki Komiyama
- Center for Education in Liberal Arts and Sciences, Osaka University, Osaka, Japan
| | - Mizuki Sudo
- Meiji Yasuda Life Foundation of Health and Welfare, Tokyo, Japan
| | - Yasuki Higaki
- Faculty of Sports Science, Fukuoka University, Fukuoka, Japan
| | - Koji Ishida
- Research Center of Health, Physical Fitness and Sports, Nagoya University, Nagoya, Japan
| | - Joseph T Costello
- Extreme Environments Laboratory, Department of Sport and Exercise Science, University of Portsmouth, Portsmouth, UK
| | - Keisho Katayama
- Research Center of Health, Physical Fitness and Sports, Nagoya University, Nagoya, Japan
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30
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Steady-state cerebral blood flow regulation at altitude: interaction between oxygen and carbon dioxide. Eur J Appl Physiol 2019; 119:2529-2544. [DOI: 10.1007/s00421-019-04206-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2018] [Accepted: 08/06/2019] [Indexed: 02/07/2023]
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31
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Howe CA, Ainslie PN, Tremblay JC, Carter HH, Patrician A, Stembridge M, Williams A, Drane AL, Delorme E, Rieger MG, Tymko MM, Gasho C, Santoro A, MacLeod DB, Hoiland RL. UBC-Nepal Expedition: Haemoconcentration underlies the reductions in cerebral blood flow observed during acclimatization to high altitude. Exp Physiol 2019; 104:1963-1972. [PMID: 31410899 DOI: 10.1113/ep087663] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2019] [Accepted: 08/13/2019] [Indexed: 12/16/2022]
Abstract
NEW FINDINGS What is the central question of this study? The aim was to evaluate the degree to which increases in haematocrit alter cerebral blood flow and cerebral oxygen delivery during acclimatization to high altitude. What is the main finding and its importance? Through haemodilution, we determined that, after 1 week of acclimatization, the primary mechanism contributing to the cerebral blood flow response during acclimatization is an increase in haemoglobin and haematocrit. The remaining contribution to the cerebral blood flow response during acclimatization is likely to be attributable to ventilatory acclimatization. ABSTRACT At high altitude, an increase in haematocrit (Hct) is achieved through altitude-induced diuresis and erythropoiesis, both of which result in increased arterial oxygen content. Given the impact of alterations in Hct on oxygen content, haemoconcentration has been hypothesized to mediate, in part, the attenuation of the initial elevation in cerebral blood flow (CBF) at high altitude. To test this hypothesis, healthy men (n = 13) ascended to 5050 m over 9 days without the aid of prophylactic acclimatization medications. After 1 week of acclimatization at 5050 m, participants were haemodiluted by rapid saline infusion (2.10 ± 0.28 l) to return Hct towards pre-acclimatization values. Arterial blood gases, Hct, global CBF (duplex ultrasound) and haemodynamic variables were measured after initial arrival at 5050 m and after 1 week of acclimatization at high altitude, before and after the haemodilution protocol. After 1 week at 5050 m, the Hct increased from 42.5 ± 2.5 to 49.6 ± 2.5% (P < 0.001), and it was subsequently reduced to 45.6 ± 2.3% (P < 0.001) after haemodilution. Global CBF decreased from 844 ± 160 to 619 ± 136 ml min-1 (P = 0.033) after 1 week of acclimatization and increased to 714 ± 204 ml min -1 (P = 0.045) after haemodilution. Despite the significant changes in Hct, and thus oxygen content, cerebral oxygen delivery was unchanged at all time points. Furthermore, these observations occurred in the absence of any changes in mean arterial blood pressure, cardiac output, arterial blood pH or oxygen saturation pre- and posthaemodilution. These data highlight the influence of Hct in the regulation of CBF and are the first to demonstrate experimentally that haemoconcentration contributes to the reduction in CBF during acclimatization to altitude.
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Affiliation(s)
- Connor A Howe
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia - Okanagan Campus, Kelowna, BC, Canada
| | - Philip N Ainslie
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia - Okanagan Campus, Kelowna, BC, Canada
| | - Joshua C Tremblay
- Cardiovascular Stress Response Laboratory, School of Kinesiology and Health Studies, Queen's University, Kingston, ON, Canada
| | - Howard H Carter
- Department of Nutrition, Exercise and Sports, University of Copenhagen, Copenhagen, Denmark
| | - Alex Patrician
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia - Okanagan Campus, Kelowna, BC, Canada
| | - Mike Stembridge
- Cardiff Centre for Exercise and Health, Cardiff Metropolitan University, Cardiff, UK
| | - Alex Williams
- International Collaboration on Repair Discoveries, University of British Columbia, Vancouver, BC, Canada
| | - Aimee L Drane
- Cardiff Centre for Exercise and Health, Cardiff Metropolitan University, Cardiff, UK
| | - Eric Delorme
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia - Okanagan Campus, Kelowna, BC, Canada
| | - Mathew G Rieger
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia - Okanagan Campus, Kelowna, BC, Canada
| | - Michael M Tymko
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia - Okanagan Campus, Kelowna, BC, Canada
| | - Chris Gasho
- VA Loma Linda Healthcare System and Loma Linda University School of Medicine, Loma Linda, CA, USA
| | - Antoinette Santoro
- Department of Anesthesiology, Duke University Medical Center, Durham, NC, USA
| | - David B MacLeod
- Department of Anesthesiology, Duke University Medical Center, Durham, NC, USA
| | - Ryan L Hoiland
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia - Okanagan Campus, Kelowna, BC, Canada
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Friend AT, Balanos GM, Lucas SJ. Isolating the independent effects of hypoxia and hyperventilation‐induced hypocapnia on cerebral haemodynamics and cognitive function. Exp Physiol 2019; 104:1482-1493. [DOI: 10.1113/ep087602] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2019] [Accepted: 06/25/2019] [Indexed: 11/08/2022]
Affiliation(s)
- Alexander T. Friend
- School of SportExercise and Rehabilitation SciencesUniversity of Birmingham Edgbaston UK
| | - George M. Balanos
- School of SportExercise and Rehabilitation SciencesUniversity of Birmingham Edgbaston UK
| | - Samuel J.E. Lucas
- School of SportExercise and Rehabilitation SciencesUniversity of Birmingham Edgbaston UK
- Centre for Human Brain HealthUniversity of Birmingham Edgbaston UK
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De Bels D, Pierrakos C, Bruneteau A, Reul F, Crevecoeur Q, Marrone N, Vissenaeken D, Borgers G, Balestra C, Honoré PM, Theunissen S. Variation of Cognitive Function During a Short Stay at Hypobaric Hypoxia Chamber (Altitude: 3842 M). Front Physiol 2019; 10:806. [PMID: 31316394 PMCID: PMC6611417 DOI: 10.3389/fphys.2019.00806] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2019] [Accepted: 06/06/2019] [Indexed: 12/12/2022] Open
Abstract
Objective To observe the effects of a fast-acute ascent to high altitude on brain cognitive function and transcranial doppler parameters in order to understand the physiological countermeasures of hypoxia. Methods 17 high-altitude-naïve male subjects (mean age was 26.3 ± 8.1 years) participated in the study. We measured Critical Flicker Fusion Frequency (CFFF), blood oxygen saturation, Psychology Experiment Building (PEBL) including three tests (Modified Math Processing Task, Perceptual Vigilance Task, and Time Estimation Task), as well as Cerebral Blood Flow index (CBFi), mean cerebral artery Systolic and diastolic velocities, Cerebral Pulsatility index (CPi), and heart Rate. All were measured at sea level, at least 1 h after arrival at the hypobaric hypoxia equivalent of 3842 m and 1 h after return to sea level. Results Under acute exposure to hypobaric hypoxic conditions, significant decrease in CFFF [42.1 ± 1 vs. 43.5 ± 1.7 Hz at sea level (asl), p < 0.01], CBFi (611 ± 51 vs. 665 ± 71 asl, p < 0.01) and blood oxygen saturation (83 ± 4% vs. 98 ± 1% asl, p < 0.001) as compared to pre-ascent values were observed. Physiological countermeasures to hypoxia could be involved as there was no significant change in neuropsychometric tests, Systolic and Diastolic velocities and CPi. A significant increase in Heart Rate (81 ± 15 bpm vs. 66 ± 15 bpm asl, p < 0.001) was observed. All parameters returned to their basal values 1 h after regaining sea level. Conclusion Hypoxia results in a decrease in CFFF, CBFi and oxygen saturation and in an increase in heart rate. As it decreased, Cerebral Blood Flow index does not seem to be the physiological measurement of choice to hypoxia explaining the maintenance of cognitive performance after acute exposure to hypobaric hypoxia and requires further investigation. Cerebral oxygen delivery and extraction could be one of the underlying mechanisms.
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Affiliation(s)
- D De Bels
- Department of Intensive Care Medicine, Brugmann University Hospital, Brussels, Belgium.,Unit of Oxygen Study, Translational Research Laboratory, Université Libre de Bruxelles, Brussels, Belgium.,Laboratory of Integrative Physiology, Haute Ecole Bruxelles-Brabant, Brussels, Belgium
| | - C Pierrakos
- Department of Intensive Care Medicine, Brugmann University Hospital, Brussels, Belgium.,Unit of Oxygen Study, Translational Research Laboratory, Université Libre de Bruxelles, Brussels, Belgium
| | - A Bruneteau
- Laboratory of Integrative Physiology, Haute Ecole Bruxelles-Brabant, Brussels, Belgium
| | - F Reul
- Faculty of Medicine, Université catholique de Louvain, Brussels, Belgium
| | - Q Crevecoeur
- Laboratory of Integrative Physiology, Haute Ecole Bruxelles-Brabant, Brussels, Belgium
| | - N Marrone
- Laboratory of Integrative Physiology, Haute Ecole Bruxelles-Brabant, Brussels, Belgium
| | - D Vissenaeken
- Hypobaric Chamber, Queen Astrid Military Hospital, Brussels, Belgium
| | - G Borgers
- Hypobaric Chamber, Queen Astrid Military Hospital, Brussels, Belgium
| | - C Balestra
- Laboratory of Integrative Physiology, Haute Ecole Bruxelles-Brabant, Brussels, Belgium
| | - P M Honoré
- Department of Intensive Care Medicine, Brugmann University Hospital, Brussels, Belgium
| | - S Theunissen
- Laboratory of Integrative Physiology, Haute Ecole Bruxelles-Brabant, Brussels, Belgium
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Hoiland RL, Fisher JA, Ainslie PN. Regulation of the Cerebral Circulation by Arterial Carbon Dioxide. Compr Physiol 2019; 9:1101-1154. [DOI: 10.1002/cphy.c180021] [Citation(s) in RCA: 101] [Impact Index Per Article: 20.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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35
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Koester-Hegmann C, Bengoetxea H, Kosenkov D, Thiersch M, Haider T, Gassmann M, Schneider Gasser EM. High-Altitude Cognitive Impairment Is Prevented by Enriched Environment Including Exercise via VEGF Signaling. Front Cell Neurosci 2019; 12:532. [PMID: 30687018 PMCID: PMC6335396 DOI: 10.3389/fncel.2018.00532] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2018] [Accepted: 12/24/2018] [Indexed: 01/17/2023] Open
Abstract
Exposure to hypobaric hypoxia at high altitude (above 2500 m asl) causes cognitive impairment, mostly attributed to changes in brain perfusion and consequently neuronal death. Enriched environment and voluntary exercise has been shown to improve cognitive function, to enhance brain microvasculature and neurogenesis, and to be neuroprotective. Here we show that high-altitude exposure (3540 m asl) of Long Evans rats during early adulthood (P48-P59) increases brain microvasculature and neurogenesis but impairs spatial and visual memory along with an increase in neuronal apoptosis. We tested whether enriched environment including a running wheel for voluntary exercise (EE) can prevent cognitive impairment at high-altitude and whether apoptosis is prevented. We found that EE retained spatial and visual memory at high altitude, and prevented neuronal apoptosis. Further, we tested whether vascular endothelial growth factor (VEGF) signaling is required for the EE-mediated recovery of spatial and visual memory and the reduction in apoptosis. Pharmacological inhibition of VEGF signaling by oral application of a tyrosine kinase inhibitor (Vandetanib) prevented the recovery of spatial and visual memory in animals housed in EE, along with an increase in apoptosis and a reduction in neurogenesis. Surprisingly, inhibition of VEGF signaling also caused impairment in spatial memory in EE-housed animals reared at low altitude, affecting mainly dentate gyrus microvasculature but not neurogenesis. We conclude that EE-mediated VEGF signaling is neuroprotective and essential for the maintenance of cognition and neurogenesis during high-altitude exposure, and for the maintenance of spatial memory at low altitude. Finally, our data also underlines the potential risk of cognitive impairment and disturbed high altitude adaption from the use of VEGF-signaling inhibitors for therapeutic purposes.
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Affiliation(s)
- Christina Koester-Hegmann
- Neuroprotection Group, Institute of Pharmacology and Toxicology, University of Zurich, Zurich, Switzerland
| | - Harkaitz Bengoetxea
- Laboratory of Clinical and Experimental Neuroscience (LaNCE), Department of Neuroscience, Faculty of Medicine and Nursing, University of the Basque Country (UPV/EHU), Bilbao, Spain
| | - Dmitry Kosenkov
- Institute of Veterinary Physiology, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland
| | - Markus Thiersch
- Institute of Veterinary Physiology, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland.,Zurich Center for Integrative Human Physiology (ZIHP), University of Zurich, Zurich, Switzerland
| | - Thomas Haider
- Institute of Veterinary Physiology, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland.,Zurich Center for Integrative Human Physiology (ZIHP), University of Zurich, Zurich, Switzerland
| | - Max Gassmann
- Institute of Veterinary Physiology, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland.,Zurich Center for Integrative Human Physiology (ZIHP), University of Zurich, Zurich, Switzerland.,Universidad Peruana Cayetano Heredia (UPCH), Lima, Peru
| | - Edith M Schneider Gasser
- Neuroprotection Group, Institute of Pharmacology and Toxicology, University of Zurich, Zurich, Switzerland.,Institute of Veterinary Physiology, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland.,Center for Neuroscience Zurich (ZNZ), Zurich, Switzerland
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36
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Jóhannesson G, Eklund A, Lindén C. Intracranial and Intraocular Pressure at the Lamina Cribrosa: Gradient Effects. Curr Neurol Neurosci Rep 2018; 18:25. [PMID: 29651628 PMCID: PMC5897485 DOI: 10.1007/s11910-018-0831-9] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
PURPOSE OF REVIEW A pressure difference between the intraocular and intracranial compartments at the site of the lamina cribrosa has been hypothesized to have a pathophysiological role in several optic nerve head diseases. This paper reviews the current literature on the translamina cribrosa pressure difference (TLCPD), the associated pressure gradient, and its potential pathophysiological role, as well as the methodology to assess TLCPD. RECENT FINDINGS For normal-tension glaucoma (NTG), initial studies indicated low intracranial pressure (ICP) while recent findings indicate that a reduced ICP is not mandatory. Data from studies on the elevated TLCPD as a pathophysiological factor of NTG are equivocal. From the identification of potential postural effects on the cerebrospinal fluid (CSF) communication between the intracranial and retrolaminar space, we hypothesize that the missing link could be a dysfunction of an occlusion mechanism of the optic nerve sheath around the optic nerve. In upright posture, this could cause an elevated TLCPD even with normal ICP and we suggest that this should be investigated as a pathophysiological component in NTG patients.
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Affiliation(s)
- Gauti Jóhannesson
- Department of Clinical Sciences, Ophthalmology, Umeå University, Umeå, Sweden. .,Wallenberg Centre for Molecular Medicine, Umeå University, Umeå, Sweden.
| | - Anders Eklund
- Department of Radiation Sciences, Biomedical Engineering, Umeå University, Umeå, Sweden
| | - Christina Lindén
- Department of Clinical Sciences, Ophthalmology, Umeå University, Umeå, Sweden
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37
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Ventilatory and cerebrovascular regulation and integration at high-altitude. Clin Auton Res 2018; 28:423-435. [PMID: 29574504 DOI: 10.1007/s10286-018-0522-2] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2017] [Accepted: 03/09/2018] [Indexed: 01/17/2023]
Abstract
Ascent to high-altitude elicits compensatory physiological adaptations in order to improve oxygenation throughout the body. The brain is particularly vulnerable to the hypoxemia of terrestrial altitude exposure. Herein we review the ventilatory and cerebrovascular changes at altitude and how they are both implicated in the maintenance of oxygen delivery to the brain. Further, the interdependence of ventilation and cerebral blood flow at altitude is discussed. Following the acute hypoxic ventilatory response, acclimatization leads to progressive increases in ventilation, and a partial mitigation of hypoxemia. Simultaneously, cerebral blood flow increases during initial exposure to altitude when hypoxemia is the greatest. Following ventilatory acclimatization to altitude, and an increase in hemoglobin concentration-which both underscore improvements in arterial oxygen content over time at altitude-cerebral blood flow progressively decreases back to sea-level values. The complimentary nature of these responses (ventilatory, hematological and cerebral) lead to a tightly maintained cerebral oxygen delivery while at altitude. Despite this general maintenance of global cerebral oxygen delivery, the manner in which this occurs reflects integration of these physiological responses. Indeed, ventilation directly influences cerebral blood flow by determining the prevailing blood gas and acid/base stimuli at altitude, but cerebral blood flow may also influence ventilation by altering central chemoreceptor stimulation via central CO2 washout. The causes and consequences of the integration of ventilatory and cerebral blood flow regulation at high altitude are outlined.
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38
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Wang X, Wei W, Yuan F, Li S, Lin J, Zhang J. Regional cerebral blood flow in natives at high altitude: An arterial spin labeled MRI study. J Magn Reson Imaging 2018; 48:708-717. [PMID: 29493838 DOI: 10.1002/jmri.25996] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2017] [Accepted: 02/13/2018] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND It is known that a neurologic sequence occurs at high altitudes (HA); hence, cerebral blood flow (CBF) might vary by altitude. PURPOSE To use arterial spin labeled (ASL) MRI to evaluate absolute CBF differences between subjects who live at HA and lowlands. STUDY TYPE Cohort prospective trial. POPULATION In all, 64 HA Tibetans, 19 lowland Tibetans, and 25 lowland Han subjects. FIELD STRENGTH/SEQUENCE CBF was measured with the pulsed ASL sequence at 3T. ASSESSMENT CBF was correlated with abode altitude in HA Tibetans; CBF differences among HA Tibetans, lowland Tibetans, and lowland Han subjects was assessed. STATISTICAL TESTS Pearson correlation assessed the correlation. Independent t-tests analyzed group differences. RESULTS In HA Tibetans, CBF decreased with altitude in the bilateral anterior and posterior cingulate gyri, fusiform gyrus, cerebellar tonsil and cortices, and thalamus as well as left middle and inferior temporal gyri and right insula (P < 0.05); HA Tibetans (vs. lowland Tibetans) had lower CBF in the left hemisphere (precuneus, anterior cingulate gyrus, fusiform gyrus, and lingual gyrus) and right hemisphere (superior parietal lobule, precuneus, posterior cingulate gyrus, and cerebellar tonsil), while they had higher CBF in the left inferior parietal lobule, lentiform nucleus, and inferior frontal gyrus (P < 0.05). The overlapping regions, in which CBF in HA Tibetans correlated with altitude and decreased (vs. lowland Tibetans), were selected for region of interest analysis, and the results showed lower CBF in HA Tibetans than lowland Han subjects (P < 0.05). DATA CONCLUSION HA adaptation in Tibetans is associated with a decrease of regional CBF. LEVEL OF EVIDENCE 2 Technical Efficacy: Stage 4 J. Magn. Reson. Imaging 2018.
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Affiliation(s)
- Xiaochuan Wang
- Department of Neurology, Affiliated Hospital of Hangzhou Normal University, Hangzhou, China
| | - Wenping Wei
- MRI Center, First Affiliated Hospital of Xiamen University, Xiamen, China
| | - Fengjuan Yuan
- Institute of Brain Diseases and Cognition, Medical College of Xiamen University, Xiamen, China
| | - Shanhua Li
- Institute of Brain Diseases and Cognition, Medical College of Xiamen University, Xiamen, China
| | - Jianzhong Lin
- Magnetic Resonance Center, Zhongshan Hospital Xiamen University, Xiamen, China
| | - Jiaxing Zhang
- Institute of Brain Diseases and Cognition, Medical College of Xiamen University, Xiamen, China
- Institute for Brain Research and Rehabilitation, South China Normal University, Guangzhou, China
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39
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Caldwell HG, Coombs GB, Tymko MM, Nowak-Flück D, Ainslie PN. Severity-dependent influence of isocapnic hypoxia on reaction time is independent of neurovascular coupling. Physiol Behav 2018; 188:262-269. [PMID: 29458114 DOI: 10.1016/j.physbeh.2018.02.035] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2018] [Revised: 02/16/2018] [Accepted: 02/16/2018] [Indexed: 12/23/2022]
Abstract
With exposure to acute normobaric hypoxia, global cerebral oxygen delivery is maintained via increases in cerebral blood flow (CBF); therefore, regional and localized changes in oxygen tension may explain neurocognitive impairment. Neurovascular coupling (NVC) is the close temporal and regional relationship of CBF to changes in neural activity and may aid in explaining the localized CBF response with cognitive activation. High-altitude related cognitive impairment is likely affected by hypocapnic cerebral vasoconstriction that may influence regional CBF regulation independent of hypoxia. We assessed neurocognition and NVC following 30 min of acute exposure to isocapnic hypoxia (decreased partial pressure of end-tidal oxygen; PETO2) during moderate hypoxia (MOD HX; 55 mm Hg PETO2), and severe hypoxia (SEV HX; 45 mm Hg PETO2) in 10 healthy individuals (25.5 ± 3.3 yrs). Transcranial Doppler ultrasound was used to assess mean posterior and middle cerebral blood velocity (PCAv and MCAv, respectively) and neurocognitive performance was assessed via validated computerized tests. The main finding was that reaction time (i.e., kinesthetic and visual-motor ability via Stroop test) was selectively impaired in SEV HX (-4.6 ± 5.2%, P = 0.04), but not MOD HX, while complex cognitive performance (e.g., psychomotor speed, cognitive flexibility, processing speed, executive function, and motor speed) was unaffected with hypoxia (P > 0.05). Additionally, severity of hypoxia had no effect on NVC (PCAv CON vs. SEV HX relative peak response 13.7 ± 6.4% vs. 16.2 ± 11.5%, P = 0.71, respectively). In summary, severe isocapnic hypoxia impaired reaction time, but not complex cognitive performance or NVC. These findings have implications for recreational and military personnel who may experience acute hypoxia.
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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, Canada.
| | - Geoff B Coombs
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Okanagan, Kelowna, Canada
| | - Michael M Tymko
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Okanagan, Kelowna, Canada
| | - Daniela Nowak-Flück
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Okanagan, Kelowna, Canada
| | - Philip N Ainslie
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Okanagan, Kelowna, Canada
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Liu X, Xu D, Hall JR, Ross S, Chen S, Liu H, Mallet RT, Shi X. Enhanced cerebral perfusion during brief exposures to cyclic intermittent hypoxemia. J Appl Physiol (1985) 2017; 123:1689-1697. [DOI: 10.1152/japplphysiol.00647.2017] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Cerebral vasodilation and increased cerebral oxygen extraction help maintain cerebral oxygen uptake in the face of hypoxemia. This study examined cerebrovascular responses to intermittent hypoxemia in eight healthy men breathing 10% O2 for 5 cycles, each 6 min, interspersed with 4 min of room air breathing. Hypoxia exposures raised heart rate ( P < 0.01) without altering arterial pressure, and increased ventilation ( P < 0.01) by expanding tidal volume. Arterial oxygen saturation ([Formula: see text]) and cerebral tissue oxygenation ([Formula: see text]) fell ( P < 0.01) less appreciably in the first bout (from 97.0 ± 0.3% and 72.8 ± 1.6% to 75.5 ± 0.9% and 54.5 ± 0.9%, respectively) than the fifth bout (from 94.9 ± 0.4% and 70.8 ± 1.0% to 66.7 ± 2.3% and 49.2 ± 1.5%, respectively). Flow velocity in the middle cerebral artery ( VMCA) and cerebrovascular conductance increased in a sigmoid fashion with decreases in [Formula: see text] and [Formula: see text]. These stimulus-response curves shifted leftward and upward from the first to the fifth hypoxia bouts; thus, the centering points fell from 79.2 ± 1.4 to 74.6 ± 1.1% ( P = 0.01) and from 59.8 ± 1.0 to 56.6 ± 0.3% ( P = 0.002), and the minimum VMCA increased from 54.0 ± 0.5 to 57.2 ± 0.5 cm/s ( P = 0.0001) and from 53.9 ± 0.5 to 57.1 ± 0.3 cm/s ( P = 0.0001) for the [Formula: see text]- VMCA and [Formula: see text]- VMCA curves, respectively. Cerebral oxygen extraction increased from prehypoxia 0.22 ± 0.01 to 0.25 ± 0.02 in minute 6 of the first hypoxia bout, and remained elevated between 0.25 ± 0.01 and 0.27 ± 0.01 throughout the fifth hypoxia bout. These results demonstrate that cerebral vasodilation combined with enhanced cerebral oxygen extraction fully compensated for decreased oxygen content during acute, cyclic hypoxemia. NEW & NOTEWORTHY Five bouts of 6-min intermittent hypoxia (IH) exposures to 10% O2 progressively reduce arterial oxygen saturation ([Formula: see text]) to 67% without causing discomfort or distress. Cerebrovascular responses to hypoxemia are dynamically reset over the course of a single IH session, such that threshold and saturation for cerebral vasodilations occurred at lower [Formula: see text] and cerebral tissue oxygenation ([Formula: see text]) during the fifth vs. first hypoxia bouts. Cerebral oxygen extraction is augmented during acute hypoxemia, which compensates for decreased arterial O2 content.
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Affiliation(s)
- Xiaoli Liu
- Institute of Cardiovascular & Metabolic Disease, University of North Texas Health Science Center, Fort Worth, Texas
- Department of Physical Therapy, University of North Texas Health Science Center, Fort Worth, Texas
| | - Diqun Xu
- Institute of Cardiovascular & Metabolic Disease, University of North Texas Health Science Center, Fort Worth, Texas
| | - James R. Hall
- Hubei University for Nationalities, Enshi, Hubei, China
| | - Sarah Ross
- Hubei University for Nationalities, Enshi, Hubei, China
| | - Shande Chen
- Hubei University for Nationalities, Enshi, Hubei, China
- Institute of Healthy Aging, University of North Texas Health Science Center, Fort Worth, Texas
| | - Howe Liu
- Department of Biostatistics, University of North Texas Health Science Center, Fort Worth, Texas
| | - Robert T. Mallet
- Institute of Cardiovascular & Metabolic Disease, University of North Texas Health Science Center, Fort Worth, Texas
| | - Xiangrong Shi
- Institute of Cardiovascular & Metabolic Disease, University of North Texas Health Science Center, Fort Worth, Texas
- Institute of Healthy Aging, University of North Texas Health Science Center, Fort Worth, Texas
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41
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Rossetti GMK, Macdonald JH, Wylie LJ, Little SJ, Newton V, Wood B, Hawkins KA, Beddoe R, Davies HE, Oliver SJ. Dietary nitrate supplementation increases acute mountain sickness severity and sense of effort during hypoxic exercise. J Appl Physiol (1985) 2017; 123:983-992. [DOI: 10.1152/japplphysiol.00293.2017] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2017] [Revised: 06/28/2017] [Accepted: 07/01/2017] [Indexed: 12/12/2022] Open
Abstract
Dietary nitrate supplementation enhances sea level performance and may ameliorate hypoxemia at high altitude. However, nitrate may exacerbate acute mountain sickness (AMS), specifically headache. This study investigated the effect of nitrate supplementation on AMS symptoms and exercise responses with 6-h hypoxia. Twenty recreationally active men [age, 22 ± 4 yr, maximal oxygen consumption (V̇o2max), 51 ± 6 ml·min−1·kg−1, means ± SD] completed this randomized double-blinded placebo-controlled crossover study. Twelve participants were classified as AMS− on the basis of Environmental Symptoms Questionnaire [Acute Cerebral Mountain Sickness score (AMS-C)] <0.7 in both trials, and five participants were classified as AMS+ on the basis of AMS-C ≥0.7 on placebo. Five days of nitrate supplementation (70-ml beetroot juice containing ~6.4 mmol nitrate daily) increased plasma NO metabolites by 182 µM compared with placebo but did not reduce AMS or improve exercise performance. After 4-h hypoxia [inspired O2 fraction ([Formula: see text]) = 0.124], nitrate increased AMS-C and headache severity (visual analog scale; whole sample ∆10 [1, 20] mm, mean difference [95% confidence interval]; P = 0.03) compared with placebo. In addition, after 5-h hypoxia, nitrate increased sense of effort during submaximal exercise (∆7 [−1, 14]; P = 0.07). In AMS−, nitrate did not alter headache or sense of effort. In contrast, in AMS+, nitrate increased headache severity (∆26 [−3, 56] mm; P = 0.07), sense of effort (∆14 [1, 28]; P = 0.04), oxygen consumption, ventilation, and mean arterial pressure during submaximal exercise. On the next day, in a separate acute hypoxic exercise test ([Formula: see text] = 0.141), nitrate did not improve time to exhaustion at 80% hypoxic V̇o2max. In conclusion, dietary nitrate increases AMS and sense of effort during exercise, particularly in those who experience AMS. Dietary nitrate is therefore not recommended as an AMS prophylactic or ergogenic aid in nonacclimatized individuals at altitude. NEW & NOTEWORTHY This is the first study to identify that the popular dietary nitrate supplement (beetroot) does not reduce acute mountain sickness (AMS) or improve exercise performance during 6-h hypoxia. The consumption of nitrate in those susceptible to AMS exacerbates AMS symptoms (headache) and sense of effort and raises oxygen cost, ventilation, and blood pressure during walking exercise in 6-h hypoxia. These data question the suitability of nitrate supplementation during altitude travel in nonacclimatized people.
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Affiliation(s)
- Gabriella M. K. Rossetti
- Extremes Research Group, College of Health and Behavioural Sciences, Bangor University, Bangor, United Kingdom; and
| | - Jamie H. Macdonald
- Extremes Research Group, College of Health and Behavioural Sciences, Bangor University, Bangor, United Kingdom; and
| | - Lee J. Wylie
- Sport and Health Sciences, College of Life and Environmental Sciences, University of Exeter, St. Luke’s Campus, Exeter, United Kingdom
| | - Samuel J. Little
- Extremes Research Group, College of Health and Behavioural Sciences, Bangor University, Bangor, United Kingdom; and
| | - Victoria Newton
- Extremes Research Group, College of Health and Behavioural Sciences, Bangor University, Bangor, United Kingdom; and
| | - Benjamin Wood
- Extremes Research Group, College of Health and Behavioural Sciences, Bangor University, Bangor, United Kingdom; and
| | - Kieran A. Hawkins
- Extremes Research Group, College of Health and Behavioural Sciences, Bangor University, Bangor, United Kingdom; and
| | - Rhys Beddoe
- Extremes Research Group, College of Health and Behavioural Sciences, Bangor University, Bangor, United Kingdom; and
| | - Hannah E. Davies
- Extremes Research Group, College of Health and Behavioural Sciences, Bangor University, Bangor, United Kingdom; and
| | - Samuel J. Oliver
- Extremes Research Group, College of Health and Behavioural Sciences, Bangor University, Bangor, United Kingdom; and
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Wei W, Wang X, Gong Q, Fan M, Zhang J. Cortical Thickness of Native Tibetans in the Qinghai-Tibetan Plateau. AJNR Am J Neuroradiol 2017; 38:553-560. [PMID: 28104637 DOI: 10.3174/ajnr.a5050] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2016] [Accepted: 10/24/2016] [Indexed: 02/05/2023]
Abstract
BACKGROUND AND PURPOSE High-altitude environmental factors and genetic variants together could have exerted their effects on the human brain. The present study was designed to investigate the cerebral morphology in high-altitude native Tibetans. MATERIALS AND METHODS T1-weighted brain images were obtained from 77 Tibetan adolescents on the Qinghai-Tibetan Plateau (altitude, 2300-5300 m) and 80 matched Han controls living at sea level. Cortical thickness, curvature, and sulcus were analyzed by using FreeSurfer. RESULTS Cortical thickness was significantly decreased in the left posterior cingulate cortex, lingual gyrus, superior parietal cortex, precuneus, and rostral middle frontal cortex and the right medial orbitofrontal cortex, lateral occipital cortex, precuneus, and paracentral lobule. Curvature was significantly decreased in the left superior parietal cortex and right superior marginal gyrus; the depth of the sulcus was significantly increased in the left inferior temporal gyrus and significantly decreased in the right superior marginal gyrus, superior temporal gyrus, and insular cortex. Moreover, cortical thickness was negatively correlated with altitude in the left superior and middle temporal gyri, rostral middle frontal cortex, insular cortex, posterior cingulate cortex, precuneus, lingual gyrus, and the right superior temporal gyrus. Curvature was positively correlated with altitude in the left rostral middle frontal cortex, insular cortex, and middle temporal gyrus. The depth of the sulcus was negatively correlated with altitude in the left lingual gyrus and right medial orbitofrontal cortex. CONCLUSIONS Differences in cortical morphometry in native Tibetans may reflect adaptations related to high altitude.
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Affiliation(s)
- W Wei
- From the MRI Center (W.W.), First Affiliated Hospital of Xiamen University, Xiamen, China.,Institute of Brain Disease and Cognition (W.W., J.Z.), Medical College of Xiamen University, Xiamen, China
| | - X Wang
- Department of Neurology (X.W.), Affiliated Hospital of Hangzhou Normal University, Hangzhou, China
| | - Q Gong
- Huaxi Magnetic Resonance Research Center (Q.G.), West China Hospital, Sichuan University, Chengdu, China
| | - M Fan
- Department of Cognitive Sciences (M.F.), Institute of Basic Medical Sciences, Beijing, China
| | - J Zhang
- Institute of Brain Disease and Cognition (W.W., J.Z.), Medical College of Xiamen University, Xiamen, China
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Sightings, edited by Erik R. Swenson and Peter Bärtsch. High Alt Med Biol 2016; 17:277-280. [PMID: 27801601 DOI: 10.1089/ham.2016.29014.stg] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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