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Sun X, Chen B, Qi Y, Wei M, Chen W, Wu X, Wang Q, Li J, Lei X, Luo G. Multi-omics Mendelian randomization integrating GWAS, eQTL and pQTL data revealed GSTM4 as a potential drug target for migraine. J Headache Pain 2024; 25:117. [PMID: 39039470 PMCID: PMC11265128 DOI: 10.1186/s10194-024-01828-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2024] [Accepted: 07/12/2024] [Indexed: 07/24/2024] Open
Abstract
INTRODUCTION Migraine, as a complex neurological disease, brings heavy burden to patients and society. Despite the availability of established therapies, existing medications have limited efficacy. Thus, we aimed to find the drug targets that improve the prognosis of migraine. METHOD We used Mendelian Randomization (MR) and Summary-data-based MR (SMR) analyses to study possible drug targets of migraine by summary statistics from FinnGen cohorts (nCase = 44,616, nControl = 367,565), with further replication in UK Biobank (nCase = 26,052, nControl = 487,214). Genetic instruments were obtained from eQTLGen and UKB-PPP to verify the drug targets at the gene expression and protein levels. The additional analyses including Bayesian co-localization, the heterogeneity in dependent instruments(HEIDI), Linkage Disequilibrium Score(LDSC), bidirectional MR, multivariate MR(MVMR), heterogeneity test, horizontal pleiotropy test, and Steiger filtering were implemented to consolidate the findings further. Lastly, drug prediction analysis and phenome-wide association study(PheWAS) were employed to imply the possibility of drug targets for future clinical applications. RESULT The MR analysis of eQTL data showed that four drug targets (PROCR, GSTM4, SLC4A1, and TNFRSF10A) were significantly associated with migraine risk in both the FinnGen and UK Biobank cohorts. However, only GSTM4 exhibited consistent effect directions across the two outcomes(Discovery cohort: OR(95%CI) = 0.94(0.93-0.96); p = 2.70e - 10; Replication cohort: OR(95%CI) = 0.93(0.91-0.94); p = 4.21e - 17). Furthermore, GSTM4 passed the SMR at p < 0.05 and HEIDI test at p > 0.05 at both the gene expression and protein levels. The protein-level MR analysis revealed a strong correlation between genetically predicted GSTM4 with a lower incidence of migraine and its subtypes(Overall migraine: OR(95%CI) = 0.91(0.87-0.95); p = 6.98e-05; Migraine with aura(MA): OR(95%CI) = 0.90(0.85-0.96); p = 2.54e-03; Migraine without aura(MO): OR(95%CI) = 0.90(0.83-0.96); p = 2.87e-03), indicating a strong co-localization relationship (PPH4 = 0.86). Further analyses provided additional validation for the possibility of GSTM4 as a migraine treatment target. CONCLUSION This study identifies GSTM4 as a potential druggable gene and promising therapeutic target for migraine.
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Affiliation(s)
- Xinyue Sun
- Department of Neurology, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, Shaanxi, 710061, China
| | - Bohong Chen
- Department of Urology, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, Shaanxi, 710061, China
| | - Yi Qi
- Department of Neurology, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, Shaanxi, 710061, China
| | - Meng Wei
- Department of Neurology, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, Shaanxi, 710061, China
| | - Wanying Chen
- Department of Neurology, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, Shaanxi, 710061, China
| | - Xiaoyu Wu
- Department of Neurology, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, Shaanxi, 710061, China
| | - Qingfan Wang
- Department of Neurology, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, Shaanxi, 710061, China
| | - Jiahao Li
- Department of Neurology, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, Shaanxi, 710061, China
| | - Xiangyu Lei
- Department of Neurology, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, Shaanxi, 710061, China.
| | - Guogang Luo
- Department of Neurology, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, Shaanxi, 710061, China.
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Fani N, Fulton T, Botzanowski B. The Neurophysiology of Interoceptive Disruptions in Trauma-Exposed Populations. Curr Top Behav Neurosci 2024. [PMID: 38678141 DOI: 10.1007/7854_2024_469] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/29/2024]
Abstract
In the aftermath of psychological trauma, many individuals experience perturbations in interoception, a term that broadly references the ability to accurately detect body signals and integrate these signals with emotional states. These interoceptive disruptions can manifest in different ways, including blunting or amplification of sensitivity to internal physiological signals. In this chapter we review extant neurophysiological research on interoception in trauma-exposed populations, with a particular focus on the effects of chronic interpersonal trauma, such as childhood maltreatment and racial discrimination. We explore research that used different types of interoceptive assays, from self-report measures to electrophysiological and neuroimaging tools to characterize the disruptions in pain perception, interoceptive acuity, and physiological responses that may arise after a traumatic event. Finally, we discuss interventions that are designed to target interoceptive mechanisms, from exposure-based therapies to mindfulness-based practices, as well as future directions in trauma interoception research.
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Affiliation(s)
- Negar Fani
- Department of Psychiatry and Behavioral Sciences, Emory University School of Medicine, Atlanta, GA, USA.
| | - Travis Fulton
- Department of Psychiatry and Behavioral Sciences, Emory University School of Medicine, Atlanta, GA, USA
| | - Boris Botzanowski
- Department of Psychiatry and Behavioral Sciences, Emory University School of Medicine, Atlanta, GA, USA
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Krupnik V. I like therefore I can, and I can therefore I like: the role of self-efficacy and affect in active inference of allostasis. Front Neural Circuits 2024; 18:1283372. [PMID: 38322807 PMCID: PMC10839114 DOI: 10.3389/fncir.2024.1283372] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2023] [Accepted: 01/02/2024] [Indexed: 02/08/2024] Open
Abstract
Active inference (AIF) is a theory of the behavior of information-processing open dynamic systems. It describes them as generative models (GM) generating inferences on the causes of sensory input they receive from their environment. Based on these inferences, GMs generate predictions about sensory input. The discrepancy between a prediction and the actual input results in prediction error. GMs then execute action policies predicted to minimize the prediction error. The free-energy principle provides a rationale for AIF by stipulating that information-processing open systems must constantly minimize their free energy (through suppressing the cumulative prediction error) to avoid decay. The theory of homeostasis and allostasis has a similar logic. Homeostatic set points are expectations of living organisms. Discrepancies between set points and actual states generate stress. For optimal functioning, organisms avoid stress by preserving homeostasis. Theories of AIF and homeostasis have recently converged, with AIF providing a formal account for homeo- and allostasis. In this paper, we present bacterial chemotaxis as molecular AIF, where mutual constraints by extero- and interoception play an essential role in controlling bacterial behavior supporting homeostasis. Extending this insight to the brain, we propose a conceptual model of the brain homeostatic GM, in which we suggest partition of the brain GM into cognitive and physiological homeostatic GMs. We outline their mutual regulation as well as their integration based on the free-energy principle. From this analysis, affect and self-efficacy emerge as the main regulators of the cognitive homeostatic GM. We suggest fatigue and depression as target neurocognitive phenomena for studying the neural mechanisms of such regulation.
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Affiliation(s)
- Valery Krupnik
- Department of Mental Health, Naval Hospital Camp Pendleton, Camp Pendleton, Oceanside, CA, United States
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4
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Kawamura M, Yoshimoto A, Ikegaya Y, Matsumoto N. Low Atmospheric Oxygen Attenuates Alpha Oscillations in the Primary Motor Cortex of Awake Rats. Biol Pharm Bull 2024; 47:462-468. [PMID: 38382999 DOI: 10.1248/bpb.b23-00863] [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] [Indexed: 02/23/2024]
Abstract
Oxygen is pivotal for survival of animals. Their cellular activity and cognitive behavior are impaired when atmospheric oxygen is insufficient, called hypoxia. However, concurrent effects of hypoxia on physiological signals are poorly understood. To address this question, we simultaneously recorded local field potentials in the primary motor cortex, primary somatosensory, and anterior cingulate cortex, electrocardiograms, electroolfactograms, and electromyograms of rats under acute hypoxic conditions (i.e., 5.0% O2). Exposure to acute hypoxia significantly attenuated alpha oscillations alone in the primary motor cortex, while we failed to find any effects of acute hypoxia on the oscillatory power in the somatosensory cortex or anterior cingulate cortex. These area- and frequency-specific effects by hypoxia may be accounted for by neural innervation from the brainstem to each cortical area via thalamic relay nuclei. Moreover, we found that heart rate and respiratory rate were increased during acute hypoxia and high heart rate was maintained even after the oxygen level returned to the baseline. Altogether, our study characterizes a systemic effect of atmospheric hypoxia on neural and peripheral signals from physiological viewpoints, leading to bridging a gap between cellular and behavioral levels.
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Affiliation(s)
- Masashi Kawamura
- Graduate School of Pharmaceutical Sciences, The University of Tokyo
| | - Airi Yoshimoto
- Graduate School of Pharmaceutical Sciences, The University of Tokyo
| | - Yuji Ikegaya
- Graduate School of Pharmaceutical Sciences, The University of Tokyo
- Institute for AI and Beyond, The University of Tokyo
- Center for Information and Neural Networks, National Institute of Information and Communications Technology
| | - Nobuyoshi Matsumoto
- Graduate School of Pharmaceutical Sciences, The University of Tokyo
- Institute for AI and Beyond, The University of Tokyo
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5
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Guluzade NA, Huggard JD, Duffin J, Keir DA. A test of the interaction between central and peripheral respiratory chemoreflexes in humans. J Physiol 2023; 601:4591-4609. [PMID: 37566804 DOI: 10.1113/jp284772] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2023] [Accepted: 07/25/2023] [Indexed: 08/13/2023] Open
Abstract
How central and peripheral chemoreceptor drives to breathe interact in humans remains contentious. We measured the peripheral chemoreflex sensitivity to hypoxia (PChS) at various isocapnic CO2 tensions (P C O 2 ${P_{{\mathrm{C}}{{\mathrm{O}}_{\mathrm{2}}}}}$ ) to determine the form of the relationship between PChS and centralP C O 2 ${P_{{\mathrm{C}}{{\mathrm{O}}_{\mathrm{2}}}}}$ . Twenty participants (10F) completed three repetitions of modified rebreathing tests with end-tidalP O 2 ${P_{{{\mathrm{O}}_{\mathrm{2}}}}}$ (P ET O 2 ${P_{{\mathrm{ET}}{{\mathrm{O}}_{\mathrm{2}}}}}$ ) clamped at 150, 70, 60 and 45 mmHg. End-tidalP C O 2 ${P_{{\mathrm{C}}{{\mathrm{O}}_{\mathrm{2}}}}}$ (P ETC O 2 ${P_{{\mathrm{ETC}}{{\mathrm{O}}_{\mathrm{2}}}}}$ ),P ET O 2 ${P_{{\mathrm{ET}}{{\mathrm{O}}_{\mathrm{2}}}}}$ , ventilation (V ̇ $\dot{V}$ E ) and calculated oxygen saturation (SC O2 ) were measured breath-by-breath by gas-analyser and pneumotach. TheV ̇ $\dot{V}$ E -P ETC O 2 ${P_{{\mathrm{ETC}}{{\mathrm{O}}_{\mathrm{2}}}}}$ relationship of repeat-trials were linear-interpolated, combined, averaged into 1 mmHg bins, and fitted with a double-linear function (V ̇ $\dot{V}$ E S, L min-1 mmHg-1 ). PChS was computed at intervals of 1 mmHg ofP ETC O 2 ${P_{{\mathrm{ETC}}{{\mathrm{O}}_{\mathrm{2}}}}}$ as follows: the difference inV ̇ $\dot{V}$ E between the three hypoxic profiles and the hyperoxic profile (∆V ̇ $\dot{V}$ E ) was calculated; three ∆V ̇ $\dot{V}$ E values were plotted against corresponding SC O2 ; and linear regression determined PChS (Lmin-1 mmHg-1 %SC O2 -1 ). These processing steps were repeated at eachP ETC O 2 ${P_{{\mathrm{ETC}}{{\mathrm{O}}_{\mathrm{2}}}}}$ to produce the PChS vs. isocapnicP C O 2 ${P_{{\mathrm{C}}{{\mathrm{O}}_{\mathrm{2}}}}}$ relationship. These were fitted with linear and polynomial functions, and Akaike information criterion identified the best-fit model. One-way repeated measures analysis of variance assessed between-condition differences.V ̇ $\dot{V}$ E S increased (P < 0.0001) with isoxicP ET O 2 ${P_{{\mathrm{ET}}{{\mathrm{O}}_{\mathrm{2}}}}}$ from 3.7 ± 1.5 L min-1 mmHg-1 at 150 mmHg to 4.4 ± 1.8, 5.0 ± 1.6 and 6.0 ± 2.2 Lmin-1 mmHg-1 at 70, 60 and 45 mmHg, respectively. Mean SC O2 fell progressively (99.3 ± 0%, 93.7 ± 0.1%, 90.4 ± 0.1% and 80.5 ± 0.1%; P < 0.0001). In all individuals, PChS increased withP ETC O 2 ${P_{{\mathrm{ETC}}{{\mathrm{O}}_{\mathrm{2}}}}}$ , and this relationship was best described by a linear model in 75%. Despite increasing central chemoreflex activation, PChS increased linearly withP ETC O 2 ${P_{{\mathrm{ETC}}{{\mathrm{O}}_{\mathrm{2}}}}}$ indicative of an additive central-peripheral chemoreflex response. KEY POINTS: How central and peripheral chemoreceptor drives to breathe interact in humans remains contentious. We measured peripheral chemoreflex sensitivity to hypoxia (PChS) at various isocapnic carbon dioxide tensions (P C O 2 ${P_{{\mathrm{C}}{{\mathrm{O}}_{\mathrm{2}}}}}$ ) to determine the form of the relationship between PChS and centralP C O 2 ${P_{{\mathrm{C}}{{\mathrm{O}}_{\mathrm{2}}}}}$ . Participants performed three repetitions of modified rebreathing with end-tidalP O 2 ${P_{{{\mathrm{O}}_{\mathrm{2}}}}}$ fixed at 150, 70, 60 and 45 mmHg. PChS was computed at intervals of 1 mmHg of end-tidalP C O 2 ${P_{{\mathrm{C}}{{\mathrm{O}}_{\mathrm{2}}}}}$ (P ETC O 2 ${P_{{\mathrm{ETC}}{{\mathrm{O}}_{\mathrm{2}}}}}$ ) as follows: the difference inV ̇ $\dot{V}$ E between the three hypoxic profiles and the hyperoxic profile (∆V ̇ $\dot{V}$ E ) was calculated; three ∆V ̇ $\dot{V}$ E values were plotted against corresponding calculated oxygen saturation (SC O2 ); and linear regression determined PChS (Lmin-1 mmHg-1 %SC O2 -1 ). In all individuals, PChS increased withP ETC O 2 ${P_{{\mathrm{ETC}}{{\mathrm{O}}_{\mathrm{2}}}}}$ , and this relationship was best described by a linear (rather than polynomial) model in 15 of 20. Most participants did not exhibit a hypo- or hyper-additive effect of central chemoreceptors on the peripheral chemoreflex indicating that the interaction was additive.
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Affiliation(s)
- Nasimi A Guluzade
- School of Kinesiology, The University of Western Ontario, London, ON, Canada
| | - Joshua D Huggard
- School of Kinesiology, The University of Western Ontario, London, ON, Canada
| | - James Duffin
- Department of Anaesthesia and Pain Management, University of Toronto, Toronto, ON, Canada
- Department of Physiology, University of Toronto, Toronto, ON, Canada
- Thornhill Research Inc., Toronto, ON, Canada
| | - Daniel A Keir
- School of Kinesiology, The University of Western Ontario, London, ON, Canada
- Toronto General Research Institute, Toronto General Hospital, Toronto, ON, Canada
- Lawson Health Research Institute, London, ON, Canada
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6
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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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7
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Fernandes J, Uppal K, Liu KH, Hu X, Orr M, Tran V, Go YM, Jones DP. Antagonistic Interactions in Mitochondria ROS Signaling Responses to Manganese. Antioxidants (Basel) 2023; 12:804. [PMID: 37107179 PMCID: PMC10134992 DOI: 10.3390/antiox12040804] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2023] [Revised: 03/17/2023] [Accepted: 03/21/2023] [Indexed: 03/29/2023] Open
Abstract
Antagonistic interaction refers to opposing beneficial and adverse signaling by a single agent. Understanding opposing signaling is important because pathologic outcomes can result from adverse causative agents or the failure of beneficial mechanisms. To test for opposing responses at a systems level, we used a transcriptome-metabolome-wide association study (TMWAS) with the rationale that metabolite changes provide a phenotypic readout of gene expression, and gene expression provides a phenotypic readout of signaling metabolites. We incorporated measures of mitochondrial oxidative stress (mtOx) and oxygen consumption rate (mtOCR) with TMWAS of cells with varied manganese (Mn) concentration and found that adverse neuroinflammatory signaling and fatty acid metabolism were connected to mtOx, while beneficial ion transport and neurotransmitter metabolism were connected to mtOCR. Each community contained opposing transcriptome-metabolome interactions, which were linked to biologic functions. The results show that antagonistic interaction is a generalized cell systems response to mitochondrial ROS signaling.
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Affiliation(s)
- Jolyn Fernandes
- Section of Neonatal-Perinatal Medicine, Department of Pediatrics, College of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA;
- Division of Pulmonary, Allergy, Critical Care and Sleep Medicine, Department of Medicine, Emory University, Atlanta, GA 30322, USA
| | - Karan Uppal
- Division of Pulmonary, Allergy, Critical Care and Sleep Medicine, Department of Medicine, Emory University, Atlanta, GA 30322, USA
| | - Ken H. Liu
- Division of Pulmonary, Allergy, Critical Care and Sleep Medicine, Department of Medicine, Emory University, Atlanta, GA 30322, USA
| | - Xin Hu
- Division of Pulmonary, Allergy, Critical Care and Sleep Medicine, Department of Medicine, Emory University, Atlanta, GA 30322, USA
| | - Michael Orr
- Division of Pulmonary, Allergy, Critical Care and Sleep Medicine, Department of Medicine, Emory University, Atlanta, GA 30322, USA
| | - ViLinh Tran
- Division of Pulmonary, Allergy, Critical Care and Sleep Medicine, Department of Medicine, Emory University, Atlanta, GA 30322, USA
| | - Young-Mi Go
- Division of Pulmonary, Allergy, Critical Care and Sleep Medicine, Department of Medicine, Emory University, Atlanta, GA 30322, USA
| | - Dean P. Jones
- Division of Pulmonary, Allergy, Critical Care and Sleep Medicine, Department of Medicine, Emory University, Atlanta, GA 30322, USA
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8
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Zhang Q, Haselden WD, Charpak S, Drew PJ. Could respiration-driven blood oxygen changes modulate neural activity? Pflugers Arch 2023; 475:37-48. [PMID: 35761104 PMCID: PMC9794637 DOI: 10.1007/s00424-022-02721-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2022] [Revised: 05/26/2022] [Accepted: 06/16/2022] [Indexed: 01/31/2023]
Abstract
Oxygen is critical for neural metabolism, but under most physiological conditions, oxygen levels in the brain are far more than are required. Oxygen levels can be dynamically increased by increases in respiration rate that are tied to the arousal state of the brain and cognition, and not necessarily linked to exertion by the body. Why these changes in respiration occur when oxygen is already adequate has been a long-standing puzzle. In humans, performance on cognitive tasks can be affected by very high or very low oxygen levels, but whether the physiological changes in blood oxygenation produced by respiration have an appreciable effect is an open question. Oxygen has direct effects on potassium channels, increases the degradation rate of nitric oxide, and is rate limiting for the synthesis of some neuromodulators. We discuss whether oxygenation changes due to respiration contribute to neural dynamics associated with attention and arousal.
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Affiliation(s)
- Qingguang Zhang
- Center for Neural Engineering, Department of Engineering Science and Mechanics, The Pennsylvania State University, University Park, PA, 16802, USA
| | - William D Haselden
- Medical Scientist Training Program, College of Medicine, The Pennsylvania State University, Hershey, PA, 17033, USA
| | - Serge Charpak
- Institut de La Vision, INSERM, CNRS, Sorbonne Université, Paris, France
- Department of Biomedical Engineering, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Patrick J Drew
- Center for Neural Engineering, Department of Engineering Science and Mechanics, The Pennsylvania State University, University Park, PA, 16802, USA.
- Department of Biomedical Engineering, The Pennsylvania State University, University Park, PA, 16802, USA.
- Department of Neurosurgery, The Pennsylvania State University, University Park, PA, 16802, USA.
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9
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Yoshizawa M, Fukushi I, Takeda K, Kono Y, Hasebe Y, Koizumi K, Ikeda K, Pokorski M, Toda T, Okada Y. Role of microglia in blood pressure and respiratory responses to acute hypoxic exposure in rats. J Physiol Sci 2022; 72:26. [PMID: 36229778 DOI: 10.1186/s12576-022-00848-y] [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: 10/21/2021] [Accepted: 09/02/2022] [Indexed: 11/10/2022]
Abstract
Microglia modulate cardiorespiratory activities during chronic hypoxia. It has not been clarified whether microglia are involved in the cardiorespiratory responses to acute hypoxia. Here we investigated this issue by comparing cardiorespiratory responses to two levels of acute hypoxia (13% O2 for 4 min and 7% O2 for 5 min) in conscious unrestrained rats before and after systemic injection of minocycline (MINO), an inhibitor of microglia activation. MINO increased blood pressure but not lung ventilation in the control normoxic condition. Acute hypoxia stimulated cardiorespiratory responses in MINO-untreated rats. MINO failed to significantly affect the magnitude of hypoxia-induced blood pressure elevation. In contrast, MINO tended to suppress the ventilatory responses to hypoxia. We conclude that microglia differentially affect cardiorespiratory regulation depending on the level of blood oxygenation. Microglia suppressively contribute to blood pressure regulation in normoxia but help maintain ventilatory augmentation in hypoxia, which underscores the dichotomy of central regulatory pathways for both systems.
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Affiliation(s)
- Masashi Yoshizawa
- Department of Pediatrics, Faculty of Medicine, University of Yamanashi, Yamanashi, Japan.,Clinical Research Center, Murayama Medical Center, Tokyo, Japan
| | - Isato Fukushi
- Clinical Research Center, Murayama Medical Center, Tokyo, Japan.,Faculty of Health Sciences, Aomori University of Health and Welfare, Aomori, Japan
| | - Kotaro Takeda
- Clinical Research Center, Murayama Medical Center, Tokyo, Japan.,Faculty of Rehabilitation, School of Health Sciences, Fujita Health University, Toyoake, Japan
| | - Yosuke Kono
- Department of Pediatrics, Faculty of Medicine, University of Yamanashi, Yamanashi, Japan.,Clinical Research Center, Murayama Medical Center, Tokyo, Japan
| | - Yohei Hasebe
- Department of Pediatrics, Faculty of Medicine, University of Yamanashi, Yamanashi, Japan.,Clinical Research Center, Murayama Medical Center, Tokyo, Japan
| | - Keiichi Koizumi
- Department of Pediatrics, Fujiyoshida Municipal Hospital, Yamanashi, Japan
| | - Keiko Ikeda
- Institute of Innovative Research, Homeostatic Mechanism Research Unit, Tokyo Institute of Technology, Yokohama, Japan
| | | | - Takako Toda
- Department of Pediatrics, Faculty of Medicine, University of Yamanashi, Yamanashi, Japan
| | - Yasumasa Okada
- Clinical Research Center, Murayama Medical Center, Tokyo, Japan.
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10
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Seizures during prolonged high-altitude exposure. Seizure 2022; 99:176-177. [DOI: 10.1016/j.seizure.2022.04.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2022] [Accepted: 04/12/2022] [Indexed: 11/17/2022] Open
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11
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Barioni NO, Derakhshan F, Tenorio Lopes L, Onimaru H, Roy A, McDonald F, Scheibli E, Baghdadwala MI, Heidari N, Bharadia M, Ikeda K, Yazawa I, Okada Y, Harris MB, Dutschmann M, Wilson RJA. Novel oxygen sensing mechanism in the spinal cord involved in cardiorespiratory responses to hypoxia. SCIENCE ADVANCES 2022; 8:eabm1444. [PMID: 35333571 PMCID: PMC8956269 DOI: 10.1126/sciadv.abm1444] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/28/2021] [Accepted: 02/04/2022] [Indexed: 05/05/2023]
Abstract
As blood oxygenation decreases (hypoxemia), mammals mount cardiorespiratory responses, increasing oxygen to vital organs. The carotid bodies are the primary oxygen chemoreceptors for breathing, but sympathetic-mediated cardiovascular responses to hypoxia persist in their absence, suggesting additional high-fidelity oxygen sensors. We show that spinal thoracic sympathetic preganglionic neurons are excited by hypoxia and silenced by hyperoxia, independent of surrounding astrocytes. These spinal oxygen sensors (SOS) enhance sympatho-respiratory activity induced by CNS asphyxia-like stimuli, suggesting they bestow a life-or-death advantage. Our data suggest the SOS use a mechanism involving neuronal nitric oxide synthase 1 (NOS1) and nicotinamide adenine dinucleotide phosphate (NADPH) oxidase (NOX). We propose NOS1 serves as an oxygen-dependent sink for NADPH in hyperoxia. In hypoxia, NADPH catabolism by NOS1 decreases, increasing availability of NADPH to NOX and launching reactive oxygen species-dependent processes, including transient receptor potential channel activation. Equipped with this mechanism, SOS are likely broadly important for physiological regulation in chronic disease, spinal cord injury, and cardiorespiratory crisis.
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Affiliation(s)
- Nicole O. Barioni
- Department of Physiology and Pharmacology, Hotchkiss Brain Institute and Alberta Children’s Hospital Research Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Fatemeh Derakhshan
- Department of Physiology and Pharmacology, Hotchkiss Brain Institute and Alberta Children’s Hospital Research Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Luana Tenorio Lopes
- Department of Physiology and Pharmacology, Hotchkiss Brain Institute and Alberta Children’s Hospital Research Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Hiroshi Onimaru
- Department of Physiology, Showa University School of Medicine, Tokyo, Japan
| | - Arijit Roy
- Department of Physiology and Pharmacology, Hotchkiss Brain Institute and Alberta Children’s Hospital Research Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Fiona McDonald
- Department of Physiology and Pharmacology, Hotchkiss Brain Institute and Alberta Children’s Hospital Research Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Erika Scheibli
- Department of Physiology and Pharmacology, Hotchkiss Brain Institute and Alberta Children’s Hospital Research Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Mufaddal I. Baghdadwala
- Department of Physiology and Pharmacology, Hotchkiss Brain Institute and Alberta Children’s Hospital Research Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Negar Heidari
- Department of Physiology and Pharmacology, Hotchkiss Brain Institute and Alberta Children’s Hospital Research Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Manisha Bharadia
- Department of Physiology and Pharmacology, Hotchkiss Brain Institute and Alberta Children’s Hospital Research Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Keiko Ikeda
- Division of Internal Medicine, Murayama Medical Center, Musashimurayama, Tokyo, Japan
| | - Itaru Yazawa
- Global Research Center for Innovative Life Science, Peptide Drug Innovation, Hoshi University School of Pharmacy and Pharmaceutical Sciences, Tokyo 142-8501, Japan
| | - Yasumasa Okada
- Division of Internal Medicine, Murayama Medical Center, Musashimurayama, Tokyo, Japan
| | - Michael B. Harris
- Department of Biological Sciences, California State University Long Beach, Long Beach, CA 90840, USA
| | - Mathias Dutschmann
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Melbourne, Victoria, 3052, Australia
| | - Richard J. A. Wilson
- Department of Physiology and Pharmacology, Hotchkiss Brain Institute and Alberta Children’s Hospital Research Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
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12
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Kalc M, Mikl S, Žökš F, Vogrin M, Stöggl T. Effects of Different Tissue Flossing Applications on Range of Motion, Maximum Voluntary Contraction, and H-Reflex in Young Martial Arts Fighters. Front Physiol 2021; 12:752641. [PMID: 34721076 PMCID: PMC8554323 DOI: 10.3389/fphys.2021.752641] [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: 08/03/2021] [Accepted: 09/21/2021] [Indexed: 11/24/2022] Open
Abstract
The purpose of this study was to investigate the effects of tissue flossing applied to the ankle joint or to the calf muscles, on ankle joint flexibility, plantarflexor strength and soleus H reflex. Eleven young (16.6 ± 1.2 years) martial arts fighters were exposed to three different intervention protocols in distinct sessions. The interventions consisted of wrapping the ankle (ANKLE) or calf (CALF) with an elastic band for 3 sets of 2 min (2 min rest) to create vascular occlusion. A third intervention without wrapping the elastic band served as a control condition (CON). Active range of motion for ankle (AROM), plantarflexor maximum voluntary contraction (MVC), and soleus H reflex were assessed before (PRE), after (POST), and 10 min after (POST10) the intervention. The H reflex, level of pain (NRS) and wrapping pressure were also assessed during the intervention. Both CALF and ANKLE protocols induced a significant drop in H reflex during the intervention. However, the CALF protocol resulted in a significantly larger H reflex reduction during and after the flossing intervention (medium to large effect size). H reflexes returned to baseline levels 10 min after the intervention in all conditions. AROM and MVC were unaffected by any intervention. The results of this study suggest that tissue flossing can decrease the muscle soleus H reflex particularly when elastic band is wrapped around the calf muscles. However, the observed changes at the spinal level did not translate into higher ankle joint flexibility or plantarflexor strength.
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Affiliation(s)
- Miloš Kalc
- Institute of Sports Medicine, Faculty of Medicine, University of Maribor, Maribor, Slovenia
| | - Samo Mikl
- Institute of Sports Medicine, Faculty of Medicine, University of Maribor, Maribor, Slovenia
| | - Franci Žökš
- Institute of Sports Medicine, Faculty of Medicine, University of Maribor, Maribor, Slovenia
| | - Matjaž Vogrin
- Institute of Sports Medicine, Faculty of Medicine, University of Maribor, Maribor, Slovenia.,Department of Orthopaedics, University Medical Centre Maribor, Maribor, Slovenia
| | - Thomas Stöggl
- Department of Sport and Exercise Science, University of Salzburg, Salzburg, Austria.,Athlete Performance Center, Red Bull Sports, Thalgau, Austria
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13
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Vestergaard MB, Ghanizada H, Lindberg U, Arngrim N, Paulson OB, Gjedde A, Ashina M, Larsson HBW. Human Cerebral Perfusion, Oxygen Consumption, and Lactate Production in Response to Hypoxic Exposure. Cereb Cortex 2021; 32:1295-1306. [PMID: 34448827 PMCID: PMC8924433 DOI: 10.1093/cercor/bhab294] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2021] [Revised: 07/16/2021] [Accepted: 07/17/2021] [Indexed: 01/01/2023] Open
Abstract
Exposure to moderate hypoxia in humans leads to cerebral lactate production, which occurs even when the cerebral metabolic rate of oxygen (CMRO2) is unaffected. We searched for the mechanism of this lactate production by testing the hypothesis of upregulation of cerebral glycolysis mediated by hypoxic sensing. Describing the pathways counteracting brain hypoxia could help us understand brain diseases associated with hypoxia. A total of 65 subjects participated in this study: 30 subjects were exposed to poikilocapnic hypoxia, 14 were exposed to isocapnic hypoxia, and 21 were exposed to carbon monoxide (CO). Using this setup, we examined whether lactate production reacts to an overall reduction in arterial oxygen concentration or solely to reduced arterial oxygen partial pressure. We measured cerebral blood flow (CBF), CMRO2, and lactate concentrations by magnetic resonance imaging and spectroscopy. CBF increased (P < 10-4), whereas the CMRO2 remained unaffected (P > 0.076) in all groups, as expected. Lactate increased in groups inhaling hypoxic air (poikilocapnic hypoxia: $0.0136\ \frac{\mathrm{mmol}/\mathrm{L}}{\Delta{\mathrm{S}}_{\mathrm{a}}{\mathrm{O}}_2}$, P < 10-6; isocapnic hypoxia: $0.0142\ \frac{\mathrm{mmol}/\mathrm{L}}{\Delta{\mathrm{S}}_{\mathrm{a}}{\mathrm{O}}_2}$, P = 0.003) but was unaffected by CO (P = 0.36). Lactate production was not associated with reduced CMRO2. These results point toward a mechanism of lactate production by upregulation of glycolysis mediated by sensing a reduced arterial oxygen pressure. The released lactate may act as a signaling molecule engaged in vasodilation.
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Affiliation(s)
- Mark B Vestergaard
- Functional Imaging Unit, Department of Clinical Physiology, Nuclear Medicine, and PET, Copenhagen University Hospital Rigshospitalet, Glostrup 2600, Denmark
| | - Hashmat Ghanizada
- Danish Headache Center, Department of Neurology, Copenhagen University Hospital Rigshospitalet, Glostrup 2600, Denmark
| | - Ulrich Lindberg
- Functional Imaging Unit, Department of Clinical Physiology, Nuclear Medicine, and PET, Copenhagen University Hospital Rigshospitalet, Glostrup 2600, Denmark
| | - Nanna Arngrim
- Danish Headache Center, Department of Neurology, Copenhagen University Hospital Rigshospitalet, Glostrup 2600, Denmark
| | - Olaf B Paulson
- Neurobiology Research Unit, Department of Neurology, Copenhagen University Hospital Rigshospitalet, Copenhagen 2100, Denmark.,Faculty of Health and Medical Science, Department of Clinical Medicine, University of Copenhagen, Copenhagen 2100, Denmark
| | - Albert Gjedde
- Faculty of Health and Medical Science, Department of Neuroscience, University of Copenhagen, Copenhagen 2100, Denmark.,Translational Neuropsychiatry Unit, Department of Clinical Medicine, Aarhus University, Aarhus 8000, Denmark
| | - Messoud Ashina
- Danish Headache Center, Department of Neurology, Copenhagen University Hospital Rigshospitalet, Glostrup 2600, Denmark.,Faculty of Health and Medical Science, Department of Clinical Medicine, University of Copenhagen, Copenhagen 2100, Denmark
| | - Henrik B W Larsson
- Functional Imaging Unit, Department of Clinical Physiology, Nuclear Medicine, and PET, Copenhagen University Hospital Rigshospitalet, Glostrup 2600, Denmark.,Faculty of Health and Medical Science, Department of Clinical Medicine, University of Copenhagen, Copenhagen 2100, Denmark
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14
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Xiang ZQ, Huang YL, Luo GL, Ma HL, Zhang DL. Decreased Event-Related Desynchronization of Mental Rotation Tasks in Young Tibetan Immigrants. Front Hum Neurosci 2021; 15:664039. [PMID: 34276324 PMCID: PMC8278785 DOI: 10.3389/fnhum.2021.664039] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2021] [Accepted: 05/14/2021] [Indexed: 11/26/2022] Open
Abstract
The present study aimed to explore the cortical activity underlying mental rotation in high-altitude immigrants via the event-related desynchronization (ERD), the electroencephalogram time–frequency analysis, and source localization based on electroencephalographic data. When compared with the low-altitude individuals, the reaction time of mental rotation tasks was significantly slower in immigrants who had lived in high-altitude areas for 3 years. The time–frequency analysis showed that the alpha ERD and the beta ERD within the time window (400–700 ms) were decreased during the mental rotation tasks in these immigrants. The decreased ERD was observed at the parietal–occipital regions within the alpha band and at the central–parietal regions within the beta band. The decreased ERD might embody the sensorimotor-related cortical activity from hypoxia, which might be involved in cognitive control function in high-altitude immigrants, which provided insights into the neural mechanism of spatial cognition change on aspect of embodied cognition due to high-altitude exposure.
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Affiliation(s)
- Zu-Qiang Xiang
- Department of Psychology, School of Education, Guangzhou University, Guangzhou, China
| | - Yi-Lin Huang
- Department of Psychology, School of Education, Guangzhou University, Guangzhou, China
| | - Guang-Li Luo
- Department of Psychology, School of Education, Guangzhou University, Guangzhou, China.,The Fourth Primary School of Qiaotou Town, Dongguan, China
| | - Hai-Lin Ma
- Plateau Brain Science Research Center, Tibet University, Lhasa, China.,Plateau Brain Science Research Center, South China Normal University, Guangzhou, China
| | - De-Long Zhang
- Plateau Brain Science Research Center, Tibet University, Lhasa, China.,Plateau Brain Science Research Center, South China Normal University, Guangzhou, China.,Key Laboratory of Brain, Cognition and Education Sciences, Ministry of Education, Guangzhou, China.,School of Psychology, Center for Studies of Psychological Application, and Guangdong Key Laboratory of Mental Health and Cognitive Science, South China Normal University, Guangzhou, China
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15
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Fukushi I, Pokorski M, Okada Y. Mechanisms underlying the sensation of dyspnea. Respir Investig 2020; 59:66-80. [PMID: 33277231 DOI: 10.1016/j.resinv.2020.10.007] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2020] [Revised: 10/13/2020] [Accepted: 10/17/2020] [Indexed: 01/17/2023]
Abstract
Dyspnea is defined as a subjective experience of breathing discomfort that consists of qualitatively distinct sensations that vary in intensity. It is a common symptom among patients with respiratory diseases that reduces daily activities, induces deconditioning, and is self-perpetuating. Although clinical interventions are needed to reduce dyspnea, its underlying mechanism is poorly understood depending on the intertwined peripheral and central neural mechanisms as well as emotional factors. Nonetheless, experimental and clinical observations suggest that dyspnea results from dissociation or a mismatch between the intended respiratory motor output set caused by the respiratory neuronal network in the lower brainstem and the ventilatory output accomplished. The brain regions responsible for detecting the mismatch between the two are not established. The mechanism underlying the transmission of neural signals for dyspnea to higher sensory brain centers is not known. Further, information from central and peripheral chemoreceptors that control the milieu of body fluids is summated at higher brain centers, which modify dyspneic sensations. The mental status also affects the sensitivity to and the threshold of dyspnea perception. The currently used methods for relieving dyspnea are not necessarily fully effective. The search for more effective therapy requires further insights into the pathophysiology of dyspnea.
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Affiliation(s)
- Isato Fukushi
- Faculty of Health Sciences, Uekusa Gakuen University, 1639-3 Ogura-cho, Wakaba-ku, Chiba, 264-0007, Japan; Clinical Research Center, Murayama Medical Center, 2-37-1 Gakuen, Musashimurayama, Tokyo, 208-0011, Japan.
| | - Mieczyslaw Pokorski
- Clinical Research Center, Murayama Medical Center, 2-37-1 Gakuen, Musashimurayama, Tokyo, 208-0011, Japan; Faculty of Health Sciences, The Jan Dlugosz University in Czestochowa, 4/8 Jerzego Waszyngtona Street, 42-200, Czestochowa, Poland
| | - Yasumasa Okada
- Clinical Research Center, Murayama Medical Center, 2-37-1 Gakuen, Musashimurayama, Tokyo, 208-0011, Japan
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16
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Leon-Ariza DS, Leon-Ariza JS, Gualdron MA, Bayona-Prieto J, Leon-Sarmiento FE. Territorial and Extraterritorial Trigeminocardiac Reflex: A Review for the Neurosurgeon and a Type IV Reflex Vignette. Cureus 2020; 12:e11646. [PMID: 33376657 PMCID: PMC7755611 DOI: 10.7759/cureus.11646] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The trigeminocardiac reflex (TCR) is a complex and, sometimes, fatal event triggered by overstimulation of the trigeminal nerve (TN) and its territorial and spinal cord branches. We reviewed and compiled for the neurosurgeon key aspects of the TCR that include a novel and straightforward classification, as well as morphophysiology, pathophysiology, neuromonitoring and neuromodulation features. Further, we present intraoperative data from a patient who developed extraterritorial, or type IV, TCR while undergoing a cervical surgery. TCR complexity, severity and unwanted outcomes indicate that this event should not be underestimated or overlooked in the surgical room. Timely TCR recognition in surgical settings is valuable for applying effective intraoperative management to prevent catastrophic outcomes.
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Affiliation(s)
| | | | | | | | - Fidias E Leon-Sarmiento
- Environmental Health, Florida International University, Miami, USA.,Neurology, Baptist Health South Florida, Miami Neuroscience Institute, Miami, USA.,Internal Medicine, National University, Bogota, COL
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17
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Allen LA, Harper RM, Vos SB, Scott CA, Lacuey N, Vilella L, Winston JS, Whatley BP, Kumar R, Ogren J, Hampson JS, Rani S, Winston GP, Lemieux L, Lhatoo SD, Diehl B. Peri-ictal hypoxia is related to extent of regional brain volume loss accompanying generalized tonic-clonic seizures. Epilepsia 2020; 61:1570-1580. [PMID: 32683693 PMCID: PMC7496610 DOI: 10.1111/epi.16615] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2020] [Revised: 06/24/2020] [Accepted: 06/24/2020] [Indexed: 02/07/2023]
Abstract
OBJECTIVES Hypoxia, or abnormally low blood-oxygen levels, often accompanies seizures and may elicit brain structural changes in people with epilepsy which contribute to central processes underlying sudden unexpected death in epilepsy (SUDEP). The extent to which hypoxia may be related to brain structural alterations in this patient group remains unexplored. METHODS We analyzed high-resolution T1-weighted magnetic resonance imaging (MRI) to determine brain morphometric and volumetric alterations in people with generalized tonic-clonic seizures (GTCS) recorded during long-term video-electroencephalography (VEEG), recruited from two sites (n = 22), together with data from age- and sex-matched healthy controls (n = 43). Subjects were sub-divided into those with mild/moderate (GTCS-hypox-mild/moderate, n = 12) and severe (GTCS-hypox-severe, n = 10) hypoxia, measured by peripheral oxygen saturation (SpO2 ) during VEEG. Whole-brain voxel-based morphometry (VBM) and regional volumetry were used to assess group comparisons and correlations between brain structural measurements as well as the duration and extent of hypoxia during GTCS. RESULTS Morphometric and volumetric alterations appeared in association with peri-GTCS hypoxia, including volume loss in the periaqueductal gray (PAG), thalamus, hypothalamus, vermis, cerebellum, parabrachial pons, and medulla. Thalamic and PAG volume was significantly reduced in GTCS patients with severe hypoxia compared with GTCS patients with mild/moderate hypoxia. Brainstem volume loss appeared in both hypoxia groups, although it was more extensive in those with severe hypoxia. Significant negative partial correlations emerged between thalamic and hippocampal volume and extent of hypoxia, whereas vermis and accumbens volumes declined with increasing hypoxia duration. SIGNIFICANCE Brain structural alterations in patients with GTCS are related to the extent of hypoxia in brain sites that serve vital functions. Although the changes are associative only, they provide evidence of injury to regulatory brain sites related to respiratory manifestations of seizures.
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Affiliation(s)
- Luke A. Allen
- Department of Clinical and Experimental EpilepsyUCL Institute of NeurologyUniversity College LondonLondonUK
- Epilepsy Society MRI UnitChalfont St PeterUK
- The Center for SUDEP ResearchNational Institute of Neurological Disorders and StrokeBethesdaMDUSA
| | - Ronald M. Harper
- The Center for SUDEP ResearchNational Institute of Neurological Disorders and StrokeBethesdaMDUSA
- UCLA Brain Research InstituteLos AngelesCAUSA
- Department of NeurobiologyDavid Geffen School of Medicine at UCLALos AngelesCAUSA
| | - Sjoerd B. Vos
- The Center for SUDEP ResearchNational Institute of Neurological Disorders and StrokeBethesdaMDUSA
- Centre for Medical Image ComputingUniversity College LondonLondonUK
- Neuroradiological Academic UnitUCL Institute of NeurologyUniversity College LondonLondonUK
| | - Catherine A. Scott
- Department of Clinical and Experimental EpilepsyUCL Institute of NeurologyUniversity College LondonLondonUK
- The Center for SUDEP ResearchNational Institute of Neurological Disorders and StrokeBethesdaMDUSA
- Department of Clinical NeurophysiologyNational Hospital for Neurology and NeurosurgeryUCLHLondonUK
| | - Nuria Lacuey
- The Center for SUDEP ResearchNational Institute of Neurological Disorders and StrokeBethesdaMDUSA
- Department of NeurologyUniversity of Texas Health Sciences Center at HoustonHoustonTXUSA
| | - Laura Vilella
- The Center for SUDEP ResearchNational Institute of Neurological Disorders and StrokeBethesdaMDUSA
- Department of NeurologyUniversity of Texas Health Sciences Center at HoustonHoustonTXUSA
| | - Joel S. Winston
- Department of Clinical and Experimental EpilepsyUCL Institute of NeurologyUniversity College LondonLondonUK
| | - Benjamin P. Whatley
- Department of Clinical and Experimental EpilepsyUCL Institute of NeurologyUniversity College LondonLondonUK
| | - Rajesh Kumar
- The Center for SUDEP ResearchNational Institute of Neurological Disorders and StrokeBethesdaMDUSA
- Department of NeurobiologyDavid Geffen School of Medicine at UCLALos AngelesCAUSA
- Department of AnaesthesiologyDavid Geffen School of Medicine at UCLALos AngelesCAUSA
| | - Jennifer Ogren
- The Center for SUDEP ResearchNational Institute of Neurological Disorders and StrokeBethesdaMDUSA
- UCLA Brain Research InstituteLos AngelesCAUSA
- Department of NeurobiologyDavid Geffen School of Medicine at UCLALos AngelesCAUSA
| | - Jaison S. Hampson
- Department of NeurologyUniversity of Texas Health Sciences Center at HoustonHoustonTXUSA
| | - Sandhya Rani
- Department of NeurologyUniversity of Texas Health Sciences Center at HoustonHoustonTXUSA
| | - Gavin P. Winston
- Department of Clinical and Experimental EpilepsyUCL Institute of NeurologyUniversity College LondonLondonUK
- Epilepsy Society MRI UnitChalfont St PeterUK
- Division of NeurologyDepartment of MedicineQueen's UniversityKingstonOntarioCanada
| | - Louis Lemieux
- Department of Clinical and Experimental EpilepsyUCL Institute of NeurologyUniversity College LondonLondonUK
| | - Samden D. Lhatoo
- The Center for SUDEP ResearchNational Institute of Neurological Disorders and StrokeBethesdaMDUSA
- Department of NeurologyUniversity of Texas Health Sciences Center at HoustonHoustonTXUSA
| | - Beate Diehl
- Department of Clinical and Experimental EpilepsyUCL Institute of NeurologyUniversity College LondonLondonUK
- The Center for SUDEP ResearchNational Institute of Neurological Disorders and StrokeBethesdaMDUSA
- Department of Clinical NeurophysiologyNational Hospital for Neurology and NeurosurgeryUCLHLondonUK
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18
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Uchiyama M, Nakao A, Kurita Y, Fukushi I, Takeda K, Numata T, Tran HN, Sawamura S, Ebert M, Kurokawa T, Sakaguchi R, Stokes AJ, Takahashi N, Okada Y, Mori Y. O 2-Dependent Protein Internalization Underlies Astrocytic Sensing of Acute Hypoxia by Restricting Multimodal TRPA1 Channel Responses. Curr Biol 2020; 30:3378-3396.e7. [PMID: 32679097 DOI: 10.1016/j.cub.2020.06.047] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2019] [Revised: 04/14/2020] [Accepted: 06/12/2020] [Indexed: 01/18/2023]
Abstract
Hypoxia sensors are essential for regulating local oxygen (O2) homeostasis within the body. This is especially pertinent within the CNS, which is particularly vulnerable to O2 deprivation due to high energetic demand. Here, we reveal hypoxia-monitoring function exerted by astrocytes through an O2-regulated protein trafficking mechanism within the CNS. Strikingly, cultured mouse astrocytes isolated from the parafacial respiratory group (pFRG) and retrotrapezoid nucleus (RTN) region are capable of rapidly responding to moderate hypoxia via the sensor cation channel transient receptor potential (TRP) A1 but, unlike multimodal sensory neurons, are inert to hyperoxia and other TRPA1 activators (carbon dioxide, electrophiles, and oxidants) in normoxia. Mechanistically, O2 suppresses TRPA1 channel activity by protein internalization via O2-dependent proline hydroxylation and subsequent ubiquitination by an E3 ubiquitin ligase, NEDD4-1 (neural precursor cell-expressed developmentally down-regulated protein 4). Hypoxia inhibits this process and instantly accumulates TRPA1 proteins at the plasma membrane, inducing TRPA1-mediated Ca2+ influx that triggers ATP release from pFRG/RTN astrocytes, potentiating respiratory center activity. Furthermore, astrocyte-specific Trpa1 disruption in a mouse brainstem-spinal cord preparation impedes the amplitude augmentation of the central autonomic respiratory output during hypoxia. Thus, reversible coupling of the TRPA1 channels with O2-dependent protein translocation allows astrocytes to act as acute hypoxia sensors in the medullary respiratory center.
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Affiliation(s)
- Makoto Uchiyama
- Laboratory of Molecular Biology, Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Kyoto 615-8510, Japan
| | - Akito Nakao
- Laboratory of Molecular Biology, Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Kyoto 615-8510, Japan
| | - Yuki Kurita
- Laboratory of Molecular Biology, Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Kyoto 615-8510, Japan
| | - Isato Fukushi
- Clinical Research Center, Murayama Medical Center, Musashimurayama, Tokyo 208-0011, Japan; Faculty of Health Sciences, Uekusa Gakuen University, Chiba 264-0007, Japan
| | - Kotaro Takeda
- Clinical Research Center, Murayama Medical Center, Musashimurayama, Tokyo 208-0011, Japan; Faculty of Rehabilitation, School of Healthcare, Fujita Health University, 1-98, Dengakugakubo, Kutsukake-cho, Toyoake, Aichi 470-1192, Japan
| | - Tomohiro Numata
- Department of Physiology, School of Medicine, Fukuoka University, Fukuoka 814-0180, Japan
| | - Ha Nam Tran
- Department of Technology and Ecology, Graduate School of Global Environmental Studies, Kyoto University, Kyoto 606-8501, Japan
| | - Seishiro Sawamura
- Laboratory of Molecular Biology, Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Kyoto 615-8510, Japan
| | - Maximilian Ebert
- Laboratory of Molecular Biology, Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Kyoto 615-8510, Japan
| | - Tatsuki Kurokawa
- Laboratory of Molecular Biology, Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Kyoto 615-8510, Japan
| | - Reiko Sakaguchi
- Laboratory of Molecular Biology, Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Kyoto 615-8510, Japan; World Premier International Research Initiative Institute for Integrated Cell-Material Sciences, Kyoto University, Kyoto 606-8501, Japan
| | - Alexander J Stokes
- Chaminade University, Honolulu, HI 96816, USA; Laboratory of Experimental Medicine, John A. Burns School of Medicine, University of Hawaii, Honolulu, HI 96813, USA
| | - Nobuaki Takahashi
- Laboratory of Molecular Biology, Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Kyoto 615-8510, Japan
| | - Yasumasa Okada
- Clinical Research Center, Murayama Medical Center, Musashimurayama, Tokyo 208-0011, Japan
| | - Yasuo Mori
- Laboratory of Molecular Biology, Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Kyoto 615-8510, Japan.
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19
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Erickson JT. Central serotonin and autoresuscitation capability in mammalian neonates. Exp Neurol 2020; 326:113162. [DOI: 10.1016/j.expneurol.2019.113162] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2019] [Revised: 11/04/2019] [Accepted: 12/23/2019] [Indexed: 01/08/2023]
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20
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Malenfant S, Brassard P, Paquette M, Le Blanc O, Chouinard A, Bonnet S, Provencher S. Continuous reduction in cerebral oxygenation during endurance exercise in patients with pulmonary arterial hypertension. Physiol Rep 2020; 8:e14389. [PMID: 32189447 PMCID: PMC7080869 DOI: 10.14814/phy2.14389] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2020] [Accepted: 02/13/2020] [Indexed: 01/03/2023] Open
Abstract
BACKGROUND Patients with pulmonary arterial hypertension (PAH) have lower cerebral blood flow (CBF) and oxygenation compared to healthy sedentary subjects, the latter negatively correlating with exercise capacity during incremental cycling exercise. We hypothesized that patients would also exhibit altered CBF and oxygenation during endurance exercise, which would correlate with endurance time. METHODS Resting and exercise cardiorespiratory parameters, blood velocity in the middle cerebral artery (MCAv; transcranial doppler) and cerebral oxygenation (relative changes in cerebral tissue oxygenation index (ΔcTOI) and cerebral deoxyhemoglobin (ΔcHHb); near-infrared spectroscopy) were continuously monitored in nine PAH patients and 10 healthy-matched controls throughout endurance exercise. Cardiac output (CO), systemic blood pressure (BP) and oxygen saturation (SpO2 ), ventilatory metrics and end-tidal CO2 pressure (PET CO2 ) were also assessed noninvasively. RESULTS Despite a lower workload and endurance oxygen consumption, similar CO and systemic BP, ΔcTOI was lower in PAH patients compared to controls (p < .01 for interaction). As expected during exercise, patients were characterized by an altered MCAv response to exercise, a lower PET CO2 and SpO2 , as wells as a higher minute-ventilation/CO2 production ratio ( V ˙ E / V ˙ CO 2 ratio). An uncoupling between changes in MCAv and PET CO2 during the cycling endurance exercise was also progressively apparent in PAH patients, but absent in healthy controls. Both cHHb and ΔcTOI correlated with V ˙ E / V ˙ CO 2 ratio (r = 0.50 and r = -0.52; both p < .05 respectively), but not with endurance time. CONCLUSION PAH patients present an abnormal cerebrovascular profile during endurance exercise with a lower cerebral oxygenation that correlate with hyperventilation but not endurance exercise time. These findings complement the physiological characterization of the cerebral vascular responses to exercise in PAH patients.
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Affiliation(s)
- Simon Malenfant
- Pulmonary Hypertension and Vascular Biology Research GroupQuebec CityQCCanada
- Quebec Heart and Lung Institute Research CenterUniversité LavalQuebec CityQCCanada
- Department of MedicineFaculty of MedicineUniversité LavalQuebec CityQCCanada
- Department of KinesiologyFaculty of MedicineUniversité LavalQuebec CityQCCanada
| | - Patrice Brassard
- Quebec Heart and Lung Institute Research CenterUniversité LavalQuebec CityQCCanada
- Department of KinesiologyFaculty of MedicineUniversité LavalQuebec CityQCCanada
| | - Myriam Paquette
- Quebec Heart and Lung Institute Research CenterUniversité LavalQuebec CityQCCanada
- Department of KinesiologyFaculty of MedicineUniversité LavalQuebec CityQCCanada
| | - Olivier Le Blanc
- Quebec Heart and Lung Institute Research CenterUniversité LavalQuebec CityQCCanada
- Department of KinesiologyFaculty of MedicineUniversité LavalQuebec CityQCCanada
| | - Audrey Chouinard
- Quebec Heart and Lung Institute Research CenterUniversité LavalQuebec CityQCCanada
- Department of KinesiologyFaculty of MedicineUniversité LavalQuebec CityQCCanada
| | - Sébastien Bonnet
- Pulmonary Hypertension and Vascular Biology Research GroupQuebec CityQCCanada
- Quebec Heart and Lung Institute Research CenterUniversité LavalQuebec CityQCCanada
- Department of MedicineFaculty of MedicineUniversité LavalQuebec CityQCCanada
| | - Steeve Provencher
- Pulmonary Hypertension and Vascular Biology Research GroupQuebec CityQCCanada
- Quebec Heart and Lung Institute Research CenterUniversité LavalQuebec CityQCCanada
- Department of MedicineFaculty of MedicineUniversité LavalQuebec CityQCCanada
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21
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Postnatal changes in O2 and CO2 sensitivity in rodents. Respir Physiol Neurobiol 2020; 272:103313. [DOI: 10.1016/j.resp.2019.103313] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2019] [Revised: 08/31/2019] [Accepted: 10/02/2019] [Indexed: 02/06/2023]
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22
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The metabolic face of migraine - from pathophysiology to treatment. Nat Rev Neurol 2019; 15:627-643. [PMID: 31586135 DOI: 10.1038/s41582-019-0255-4] [Citation(s) in RCA: 127] [Impact Index Per Article: 25.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/12/2019] [Indexed: 12/11/2022]
Abstract
Migraine can be regarded as a conserved, adaptive response that occurs in genetically predisposed individuals with a mismatch between the brain's energy reserve and workload. Given the high prevalence of migraine, genotypes associated with the condition seem likely to have conferred an evolutionary advantage. Technological advances have enabled the examination of different aspects of cerebral metabolism in patients with migraine, and complementary animal research has highlighted possible metabolic mechanisms in migraine pathophysiology. An increasing amount of evidence - much of it clinical - suggests that migraine is a response to cerebral energy deficiency or oxidative stress levels that exceed antioxidant capacity and that the attack itself helps to restore brain energy homeostasis and reduces harmful oxidative stress levels. Greater understanding of metabolism in migraine offers novel therapeutic opportunities. In this Review, we describe the evidence for abnormalities in energy metabolism and mitochondrial function in migraine, with a focus on clinical data (including neuroimaging, biochemical, genetic and therapeutic studies), and consider the relationship of these abnormalities with the abnormal sensory processing and cerebral hyper-responsivity observed in migraine. We discuss experimental data to consider potential mechanisms by which metabolic abnormalities could generate attacks. Finally, we highlight potential treatments that target cerebral metabolism, such as nutraceuticals, ketone bodies and dietary interventions.
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Bailey DM. Oxygen, evolution and redox signalling in the human brain; quantum in the quotidian. J Physiol 2018; 597:15-28. [PMID: 30315729 DOI: 10.1113/jp276814] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2018] [Accepted: 09/27/2018] [Indexed: 12/20/2022] Open
Abstract
Rising atmospheric oxygen (O2 ) levels provided a selective pressure for the evolution of O2 -dependent micro-organisms that began with the autotrophic eukaryotes. Since these primordial times, the respiring mammalian cell has become entirely dependent on the constancy of electron flow, with molecular O2 serving as the terminal electron acceptor in mitochondrial oxidative phosphorylation. Indeed, the ability to 'sense' O2 and maintain homeostasis is considered one of the most important roles of the central nervous system (CNS) and probably represented a major driving force in the evolution of the human brain. Today, modern humans have evolved with an oversized brain committed to a continually active state and, as a consequence, paradoxically vulnerable to failure if the O2 supply is interrupted. However, our pre-occupation with O2 , the elixir of life, obscures the fact that it is a gas with a Janus face, capable of sustaining life in physiologically controlled amounts yet paradoxically deadly to the CNS when in excess. A closer look at its quantum structure reveals precisely why; the triplet ground state diatomic O2 molecule is paramagnetic and exists in air as a free radical, constrained from reacting aggressively with the brain's organic molecules due to its 'spin restriction', a thermodynamic quirk of evolutionary fate. By further exploring O2 's free radical 'quantum quirkiness', including emergent (quantum) physiological phenomena, our understanding of precisely how the human brain senses O2 deprivation (hypoxia) and the elaborate redox-signalling defence mechanisms that defend O2 homeostasis has the potential to offer unique insights into the pathophysiology and treatment of human brain disease.
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Affiliation(s)
- Damian Miles Bailey
- Neurovascular Research Laboratory, Faculty of Life Sciences and Education, University of South Wales, Wales, UK
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Bailey DM. RETRACTED ARTICLE: The quantum physiology of oxygen; from electrons to the evolution of redox signaling in the human brain. Bioelectron Med 2018; 4:13. [PMID: 32232089 PMCID: PMC7098224 DOI: 10.1186/s42234-018-0014-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2018] [Accepted: 09/19/2018] [Indexed: 12/11/2022] Open
Abstract
Rising atmospheric oxygen (O2) levels provided a selective pressure for the evolution of O2-dependent micro-organisms that began with the autotrophic eukaryotes. Since these primordial times, the respiring mammalian cell has become entirely dependent on the constancy of electron flow with molecular O2 serving as the terminal electron acceptor in mitochondrial oxidative phosphorylation. Indeed, the ability to “sense” O2 and maintain homeostasis is considered one of the most important roles of the central nervous system (CNS) and likely represented a major driving force in the evolution of the human brain. Today, modern humans have evolved with an oversized brain committed to a continually active state and as a consequence, paradoxically vulnerable to failure if the O2 supply is interrupted. However, our pre-occupation with O2, the elixir of life, obscures the fact that it is a gas with a Janus Face, capable of sustaining life in physiologically controlled amounts yet paradoxically deadly to the CNS when in excess. A closer look at its quantum structure reveals precisely why; the triplet ground state diatomic O2 molecule is paramagnetic and exists in air as a free radical, constrained from reacting aggressively with the brain’s organic molecules due to its “spin restriction”, a thermodynamic quirk of evolutionary fate. By further exploring O2’s free radical “quantum quirkiness” including emergent quantum physiological phenomena, our understanding of precisely how the human brain senses O2 deprivation (hypoxia) and the elaborate redox-signaling defense mechanisms that defend O2 homeostasis has the potential to offer unique insights into the pathophysiology and treatment of human brain disease.
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Affiliation(s)
- Damian Miles Bailey
- Neurovascular Research Laboratory, Alfred Russel Wallace Building, Faculty of Life Sciences and Education, University of South Wales, Pontypridd, CF37 4AT UK
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25
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Decroix L, De Pauw K, Van Cutsem J, Pattyn N, Heyman E, Meeusen R. Acute cocoa flavanols intake improves cerebral hemodynamics while maintaining brain activity and cognitive performance in moderate hypoxia. Psychopharmacology (Berl) 2018; 235:2597-2608. [PMID: 29951768 DOI: 10.1007/s00213-018-4952-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/27/2018] [Accepted: 06/18/2018] [Indexed: 12/11/2022]
Abstract
INTRODUCTION Acute cocoa flavanols (CF) intake has been suggested to modulate cognitive function and neurovascular coupling (NVC). Whether increased NVC is solely driven by improved vascular responsiveness or also by neuronal activity remains unknown. This study investigated the effects of acute CF intake on cognitive performance, NVC, and neuronal activity in healthy subjects in normoxia and hypoxia (4000 m simulated altitude; 12.7% O2). METHODS Twenty healthy subjects (age 23.2 ± 4.3 years) performed four trials. Participants performed a Stroop task and "cognition" battery 2 h after acute CF (530 mg CF, 100 mg epicatechin) or placebo intake, and 30 min after initial exposure to hypoxia or normoxia. Electroencephalogram and functional near-infrared spectroscopy were used to analyze hemodynamic changes and neuronal activity. RESULTS CF enhanced NVC in the right prefrontal cortex during several tasks (risk decision making, visual tracking, complex scanning, spatial orientation), while neuronal activity was not affected. CF improved abstract thinking in normoxia, but not in hypoxia and did not improve other cognitive performances. Hypoxia decreased accuracy on the Stroop task, but performance on other cognitive tasks was preserved. NVC and neuronal activity during cognitive tasks were similar in hypoxia vs. normoxia, with the exception of increased β activity in the primary motor cortex during abstract thinking. CONCLUSIONS Acute CF intake improved NVC, but did not affect neuronal activity and cognitive performance in both normoxia and hypoxia. Most cognitive functions, as well as NVC and neuronal activity, did not decline by acute exposure to moderate hypoxia in healthy subjects.
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Affiliation(s)
- L Decroix
- Human Physiology research group, Faculty of Physical Education and Physical Therapy, Vrije Universiteit Brussel, Pleinlaan 2, 1050, Brussel, Belgium.,Multi-disciplinary Research Unit of Sport, Heath and Society, URePSSS, University of Lille, Artois, Littoral Cote d'Opale, EA7369, 413 rue Eugène Avinée, 59120, Loos, France
| | - K De Pauw
- Human Physiology research group, Faculty of Physical Education and Physical Therapy, Vrije Universiteit Brussel, Pleinlaan 2, 1050, Brussel, Belgium
| | - J Van Cutsem
- Human Physiology research group, Faculty of Physical Education and Physical Therapy, Vrije Universiteit Brussel, Pleinlaan 2, 1050, Brussel, Belgium
| | - N Pattyn
- Human Physiology research group, Faculty of Physical Education and Physical Therapy, Vrije Universiteit Brussel, Pleinlaan 2, 1050, Brussel, Belgium.,Vital Signs and Performance Research Unit, Royal Military Academy, Renaissancelaan 30, 1000, Brussels, Belgium
| | - E Heyman
- Multi-disciplinary Research Unit of Sport, Heath and Society, URePSSS, University of Lille, Artois, Littoral Cote d'Opale, EA7369, 413 rue Eugène Avinée, 59120, Loos, France
| | - R Meeusen
- Human Physiology research group, Faculty of Physical Education and Physical Therapy, Vrije Universiteit Brussel, Pleinlaan 2, 1050, Brussel, Belgium.
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Yao C, He Z, Nakano T, Shuai J. Spiking patterns of a neuron model to stimulus: Rich dynamics and oxygen's role. CHAOS (WOODBURY, N.Y.) 2018; 28:083112. [PMID: 30180647 DOI: 10.1063/1.5018707] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2017] [Accepted: 07/23/2018] [Indexed: 06/08/2023]
Abstract
Neuronal spiking patterns, which are of fundamental importance for the understanding of information processing in neural systems, can be generated in response to different stimuli. We here investigate in detail the stimulus-induced spiking patterns in a biologically plausible neuron model in which the oxygen concentration and the dynamical concentrations of potassium, sodium, and chloride are considered. Various types of spiking patterns can be induced by the different external potassium accumulations in response to the stimulus, including two different types of epileptic seizure (SZ) and spreading depression (SD) states, two different mixed states of SD and SZ, SZ state with multi-burst, and tonic firing behaviors. Interestingly, we show that these rich spiking patterns can also be induced by the current stimulus with a low oxygen concentration. Furthermore, we reveal that the stimulus can induce two different phase transitions from the SD state to the SZ state according to the phase transition theory, which results in the different electrical activities. All these findings may provide insight into information processing in neural systems.
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Affiliation(s)
- Chenggui Yao
- Department of Mathematics, Shaoxing University, Shaoxing 312000, China
| | - Zhiwei He
- Department of Mathematics, Shaoxing University, Shaoxing 312000, China
| | - Tadashi Nakano
- Graduate School of Frontier Biosciences, Osaka University, 1-1 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Jianwei Shuai
- Department of Physics, Xiamen University, Xiamen 361005, People's Republic of China
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Fukushi I, Yokota S, Okada Y. The role of the hypothalamus in modulation of respiration. Respir Physiol Neurobiol 2018; 265:172-179. [PMID: 30009993 DOI: 10.1016/j.resp.2018.07.003] [Citation(s) in RCA: 46] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2018] [Revised: 06/17/2018] [Accepted: 07/10/2018] [Indexed: 01/18/2023]
Abstract
The hypothalamus is a higher center of the autonomic nervous system and maintains essential body homeostasis including respiration. The paraventricular nucleus, perifornical area, dorsomedial hypothalamus, and lateral and posterior hypothalamus are the primary nuclei of the hypothalamus critically involved in respiratory control. These hypothalamic nuclei are interconnected with respiratory nuclei located in the midbrain, pons, medulla and spinal cord. We provide an extensive review of the role of the above hypothalamic nuclei in the maintenance of basal ventilation, and modulation of respiration in hypoxic and hypercapnic conditions, during dynamic exercise, in awake and sleep states, and under stress. Dysfunction of the hypothalamus causes abnormal breathing and hypoventilation. However, the cellular and molecular mechanisms how the hypothalamus integrates and modulates autonomic and respiratory functions remain to be elucidated.
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Affiliation(s)
- Isato Fukushi
- Clinical Research Center, Murayama Medical Center, 2-37-1 Gakuen, Musashimurayama, Tokyo 208-0011, Japan.
| | - Shigefumi Yokota
- Department of Anatomy and Neuroscience, Shimane University School of Medicine, 89-1 Enya-cho, Izumo 693-8501, Japan
| | - Yasumasa Okada
- Clinical Research Center, Murayama Medical Center, 2-37-1 Gakuen, Musashimurayama, Tokyo 208-0011, Japan
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28
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Bartman ME, Johnson SM. Isolated adult turtle brainstems exhibit central hypoxic chemosensitivity. Comp Biochem Physiol A Mol Integr Physiol 2018; 225:65-73. [PMID: 30003967 DOI: 10.1016/j.cbpa.2018.07.001] [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: 01/31/2018] [Revised: 06/27/2018] [Accepted: 07/03/2018] [Indexed: 10/28/2022]
Abstract
During hypoxia, red-eared slider turtles increase ventilation and decrease episodic breathing, but whether these responses are due to central mechanisms is not known. To test this question, isolated adult turtle brainstems were exposed to 240 min of hypoxic solution (bath PO2 = 32.6 ± 1.2 mmHg) and spontaneous respiratory-related motor bursts (respiratory event) were recorded on hypoglossal nerve roots. During hypoxia, burst frequency increased during the first 15 min, and then decreased during the remaining 35-240 min of hypoxia. Burst amplitude was maintained for 120 min, but then decreased during the last 120 min. The number of bursts/respiratory event decreased within 30 min and remained decreased. Pretreatment with either prazosin (α1-adrenergic antagonist) or MDL7222 (5-HT3 antagonist) blocked the hypoxia-induced short-term increase and the longer duration decrease in burst frequency. MDL7222, but not prazosin, blocked the hypoxia-induced decrease in bursts/respiratory event. Thus, during bath hypoxia, isolated turtle brainstems continued to produce respiratory motor output, but the frequency and pattern were altered in a manner that required endogenous α1-adrenergic and serotonin 5-HT3 receptor activation. This is the first example of isolated reptile brainstems exhibiting central hypoxic chemosensitivity similar to other vertebrate species.
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Affiliation(s)
- Michelle E Bartman
- Department of Comparative Biosciences, School of Veterinary Medicine, University of Wisconsin, Madison, WI 53706, USA
| | - Stephen M Johnson
- Department of Comparative Biosciences, School of Veterinary Medicine, University of Wisconsin, Madison, WI 53706, USA.
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Docio I, Olea E, Prieto-LLoret J, Gallego-Martin T, Obeso A, Gomez-Niño A, Rocher A. Guinea Pig as a Model to Study the Carotid Body Mediated Chronic Intermittent Hypoxia Effects. Front Physiol 2018; 9:694. [PMID: 29922183 PMCID: PMC5996279 DOI: 10.3389/fphys.2018.00694] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2018] [Accepted: 05/18/2018] [Indexed: 12/12/2022] Open
Abstract
Clinical and experimental evidence indicates a positive correlation between chronic intermittent hypoxia (CIH), increased carotid body (CB) chemosensitivity, enhanced sympatho-respiratory coupling and arterial hypertension and cardiovascular disease. Several groups have reported that both the afferent and efferent arms of the CB chemo-reflex are enhanced in CIH animal models through the oscillatory CB activation by recurrent hypoxia/reoxygenation episodes. Accordingly, CB ablation or denervation results in the reduction of these effects. To date, no studies have determined the effects of CIH treatment in chemo-reflex sensitization in guinea pig, a rodent with a hypofunctional CB and lacking ventilatory responses to hypoxia. We hypothesized that the lack of CB hypoxia response in guinea pig would suppress chemo-reflex sensitization and thereby would attenuate or eliminate respiratory, sympathetic and cardiovascular effects of CIH treatment. The main purpose of this study was to assess if guinea pig CB undergoes overactivation by CIH and to correlate CIH effects on CB chemoreceptors with cardiovascular and respiratory responses to hypoxia. We measured CB secretory activity, ventilatory parameters, systemic arterial pressure and sympathetic activity, basal and in response to acute hypoxia in two groups of animals: control and 30 days CIH exposed male guinea pigs. Our results indicated that CIH guinea pig CB lacks activity elicited by acute hypoxia measured as catecholamine (CA) secretory response or intracellular calcium transients. Plethysmography data showed that only severe hypoxia (7% O2) and hypercapnia (5% CO2) induced a significant increased ventilatory response in CIH animals, together with higher oxygen consumption. Therefore, CIH exposure blunted hyperventilation to hypoxia and hypercapnia normalized to oxygen consumption. Increase in plasma CA and superior cervical ganglion CA content was found, implying a CIH induced sympathetic hyperactivity. CIH promoted cardiovascular adjustments by increasing heart rate and mean arterial blood pressure without cardiac ventricle hypertrophy. In conclusion, CIH does not sensitize CB chemoreceptor response to hypoxia but promotes cardiovascular adjustments probably not mediated by the CB. Guinea pigs could represent an interesting model to elucidate the mechanisms that underlie the long-term effects of CIH exposure to provide evidence for the role of the CB mediating pathological effects in sleep apnea diseases.
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Affiliation(s)
- Inmaculada Docio
- Departamento de Bioquímica y Biología Molecular y Fisiología, Universidad de Valladolid, Valladolid, Spain
- Instituto de Biología y Genética Molecular, Consejo Superior de Investigaciones Científicas, Universidad de Valladolid, Valladolid, Spain
- CIBER de Enfermedades Respiratorias, Instituto de Salud Carlos III, Madrid, Spain
| | - Elena Olea
- Instituto de Biología y Genética Molecular, Consejo Superior de Investigaciones Científicas, Universidad de Valladolid, Valladolid, Spain
- CIBER de Enfermedades Respiratorias, Instituto de Salud Carlos III, Madrid, Spain
- Departamento de Enfermería, Universidad de Valladolid, Valladolid, Spain
| | - Jesus Prieto-LLoret
- Departamento de Bioquímica y Biología Molecular y Fisiología, Universidad de Valladolid, Valladolid, Spain
- Instituto de Biología y Genética Molecular, Consejo Superior de Investigaciones Científicas, Universidad de Valladolid, Valladolid, Spain
- CIBER de Enfermedades Respiratorias, Instituto de Salud Carlos III, Madrid, Spain
| | - Teresa Gallego-Martin
- Departamento de Bioquímica y Biología Molecular y Fisiología, Universidad de Valladolid, Valladolid, Spain
- Instituto de Biología y Genética Molecular, Consejo Superior de Investigaciones Científicas, Universidad de Valladolid, Valladolid, Spain
- CIBER de Enfermedades Respiratorias, Instituto de Salud Carlos III, Madrid, Spain
| | - Ana Obeso
- Departamento de Bioquímica y Biología Molecular y Fisiología, Universidad de Valladolid, Valladolid, Spain
- Instituto de Biología y Genética Molecular, Consejo Superior de Investigaciones Científicas, Universidad de Valladolid, Valladolid, Spain
- CIBER de Enfermedades Respiratorias, Instituto de Salud Carlos III, Madrid, Spain
| | - Angela Gomez-Niño
- Instituto de Biología y Genética Molecular, Consejo Superior de Investigaciones Científicas, Universidad de Valladolid, Valladolid, Spain
- CIBER de Enfermedades Respiratorias, Instituto de Salud Carlos III, Madrid, Spain
- Departamento de Biología Celular, Histología y Farmacología, Universidad de Valladolid, Valladolid, Spain
| | - Asuncion Rocher
- Departamento de Bioquímica y Biología Molecular y Fisiología, Universidad de Valladolid, Valladolid, Spain
- Instituto de Biología y Genética Molecular, Consejo Superior de Investigaciones Científicas, Universidad de Valladolid, Valladolid, Spain
- CIBER de Enfermedades Respiratorias, Instituto de Salud Carlos III, Madrid, Spain
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Abstract
In some organisms and cells, oxygen availability influences oxygen consumption. In this review, we examine this phenomenon of hypoxic hypometabolism (HH), discussing its features, mechanisms, and implications. Small mammals and other vertebrate species exhibit "oxyconformism," a downregulation of metabolic rate and body temperature during hypoxia which is sensed by the central nervous system. Smaller body mass and cooler ambient temperature contribute to a high metabolic rate in mammals. It is this hypermetabolic state that is suppressed by hypoxia leading to HH. Larger mammals including humans do not exhibit HH. Tissues and cells also exhibit reductions in respiration during hypoxia in vitro, even at oxygen levels ample for mitochondrial oxidative phosphorylation. The mechanisms of cellular HH involve intracellular oxygen sensors including hypoxia-inducible factors, AMP-activated protein kinase (AMPK), and mitochondrial reactive oxygen species (ROS) which downregulate mitochondrial activity and ATP utilization. HH has a profound impact on cardiovascular, respiratory, and metabolic physiology in rodents. Therefore, caution should be exercised when extrapolating the results of rodent hypoxia studies to human physiology.
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31
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Ruggiero L, Yacyshyn AF, Nettleton J, McNeil CJ. UBC-Nepal expedition: acclimatization to high-altitude increases spinal motoneurone excitability during fatigue in humans. J Physiol 2017; 596:3327-3339. [PMID: 29130497 DOI: 10.1113/jp274872] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2017] [Accepted: 11/09/2017] [Indexed: 01/28/2023] Open
Abstract
KEY POINTS Acute exposure and acclimatization to hypoxia are associated with an impairment and partial recovery, respectively, of the capability of the central nervous system to drive muscles during prolonged efforts. Motoneurones play a vital role in muscle contraction and in fatigue, although the effect of hypoxia on motoneurone excitability during exercise has not been assessed in humans. We studied the impact of fatigue on motoneurone excitability in normoxia, acute and chronic exposure (5050 m) to hypoxia. Performance was worse in acute hypoxia but recovered to the normoxic standard in chronic hypoxia, in parallel with an increased excitability of the motoneurones compared to acute exposure to hypoxia. These findings reveal that prolonged hypoxia causes a heightened motoneurone responsiveness during fatiguing exercise; such an adaptation might favour the restoration of performance where low pressures of oxygen are chronically present. ABSTRACT The fatigue-induced failure of the motor cortex to drive muscles maximally increases in acute hypoxia (AH) compared to normoxia (N) but improves with acclimatization (chronic hypoxia; CH). Despite their importance to muscle output, it is unknown how locomotor motoneurones in humans are affected by hypoxia and acclimatization. Eleven participants performed 16 min of submaximal [25% maximal torque (maximal voluntary contraction, MVC)] intermittent isometric elbow flexions in N, AH (environmental chamber) and CH (7-14 days at 5050 m) (PI O2 = 140, 74 and 76 mmHg, respectively). For each minute of the fatigue protocol, motoneurone responsiveness was measured with cervicomedullary stimulation delivered 100 ms after transcranial magnetic stimulation (TMS) used to transiently silence voluntary drive. Every 2 min, cortical voluntary activation (cVA) was measured with TMS. After the task, MVC torque declined more in AH (∼20%) than N and CH (∼11% and 14%, respectively, P < 0.05), with no differences between N and CH. cVA was lower in AH than N and CH at baseline (∼92%, 95% and 95%, respectively) and at the end of the protocol (∼82%, 90% and 90%, P < 0.05). During the fatiguing task, motoneurone excitability in N and AH declined to ∼65% and 40% of the baseline value (P < 0.05). In CH, motoneurone excitability did not decline and, late in the protocol, was ∼40% higher compared to AH (P < 0.05). These novel data reveal that acclimatization to hypoxia leads to a heightened motoneurone responsiveness during fatiguing exercise. Positive spinal and supraspinal adaptations during extended periods at altitude might therefore play a vital role for the restoration of performance after acclimatization to hypoxia.
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Affiliation(s)
- Luca Ruggiero
- Integrated Neuromuscular Physiology Laboratory, Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, BC, Canada
| | - Alexandra F Yacyshyn
- Integrated Neuromuscular Physiology Laboratory, Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, BC, Canada
| | - Jane Nettleton
- Integrated Neuromuscular Physiology Laboratory, Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, BC, Canada
| | - Chris J McNeil
- Integrated Neuromuscular Physiology Laboratory, Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, BC, Canada
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Integrity of Cerebellar Fastigial Nucleus Intrinsic Neurons Is Critical for the Global Ischemic Preconditioning. Brain Sci 2017; 7:brainsci7100121. [PMID: 28934119 PMCID: PMC5664048 DOI: 10.3390/brainsci7100121] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2017] [Revised: 09/15/2017] [Accepted: 09/18/2017] [Indexed: 01/25/2023] Open
Abstract
Excitation of intrinsic neurons of cerebellar fastigial nucleus (FN) renders brain tolerant to local and global ischemia. This effect reaches a maximum 72 h after the stimulation and lasts over 10 days. Comparable neuroprotection is observed following sublethal global brain ischemia, a phenomenon known as preconditioning. We hypothesized that FN may participate in the mechanisms of ischemic preconditioning as a part of the intrinsic neuroprotective mechanism. To explore potential significance of FN neurons in brain ischemic tolerance we lesioned intrinsic FN neurons with excitotoxin ibotenic acid five days before exposure to 20 min four-vessel occlusion (4-VO) global ischemia while analyzing neuronal damage in Cornu Ammoni area 1 (CA1) hippocampal area one week later. In FN-lesioned animals, loss of CA1 cells was higher by 22% compared to control (phosphate buffered saline (PBS)-injected) animals. Moreover, lesion of FN neurons increased morbidity following global ischemia by 50%. Ablation of FN neurons also reversed salvaging effects of five-minute ischemic preconditioning on CA1 neurons and morbidity, while ablation of cerebellar dentate nucleus neurons did not change effect of ischemic preconditioning. We conclude that FN is an important part of intrinsic neuroprotective system, which participates in ischemic preconditioning and may participate in naturally occurring neuroprotection, such as "diving response".
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Intermittent Hypoxia Enhances Functional Connectivity of Midcervical Spinal Interneurons. J Neurosci 2017; 37:8349-8362. [PMID: 28751456 DOI: 10.1523/jneurosci.0992-17.2017] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2017] [Revised: 06/20/2017] [Accepted: 07/18/2017] [Indexed: 12/20/2022] Open
Abstract
Brief, intermittent oxygen reductions [acute intermittent hypoxia (AIH)] evokes spinal plasticity. Models of AIH-induced neuroplasticity have focused on motoneurons; however, most midcervical interneurons (C-INs) also respond to hypoxia. We hypothesized that AIH would alter the functional connectivity between C-INs and induce persistent changes in discharge. Bilateral phrenic nerve activity was recorded in anesthetized and ventilated adult male rats and a multielectrode array was used to record C4/5 spinal discharge before [baseline (BL)], during, and 15 min after three 5 min hypoxic episodes (11% O2, H1-H3). Most C-INs (94%) responded to hypoxia by either increasing or decreasing firing rate. Functional connectivity was examined by cross-correlating C-IN discharge. Correlograms with a peak or trough were taken as evidence for excitatory or inhibitory connectivity between C-IN pairs. A subset of C-IN pairs had increased excitatory cross-correlations during hypoxic episodes (34%) compared with BL (19%; p < 0.0001). Another subset had a similar response following each episode (40%) compared with BL (19%; p < 0.0001). In the latter group, connectivity remained elevated 15 min post-AIH (30%; p = 0.0002). Inhibitory C-IN connectivity increased during H1-H3 (4.5%; p = 0.0160), but was reduced 15 min post-AIH (0.5%; p = 0.0439). Spike-triggered averaging indicated that a subset of C-INs is synaptically coupled to phrenic motoneurons and excitatory inputs to these "pre-phrenic" cells increased during AIH. We conclude that AIH alters connectivity of the midcervical spinal network. To our knowledge, this is the first demonstration that AIH induces plasticity within the propriospinal network.SIGNIFICANCE STATEMENT Acute intermittent hypoxia (AIH) can trigger spinal plasticity associated with sustained increases in respiratory, somatic, and/or autonomic motor output. The impact of AIH on cervical spinal interneuron (C-IN) discharge and connectivity is unknown. Our results demonstrate that AIH recruits excitatory C-INs into the spinal respiratory (phrenic) network. AIH also enhances excitatory and reduces inhibitory connections among the C-IN network. We conclude that C-INs are part of the respiratory, somatic, and/or autonomic response to AIH, and that propriospinal plasticity may contribute to sustained increases in motor output after AIH.
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Effects of high-altitude exposure on supraspinal fatigue and corticospinal excitability and inhibition. Eur J Appl Physiol 2017. [PMID: 28647868 DOI: 10.1007/s00421-017-3669-y] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
PURPOSE While acute hypoxic exposure enhances exercise-induced central fatigue and can alter corticospinal excitability and inhibition, the effect of prolonged hypoxic exposure on these parameters remains to be clarified. We hypothesized that 5 days of altitude exposure would (i) normalize exercise-induced supraspinal fatigue during isolated muscle exercise to sea level (SL) values and (ii) increase corticospinal excitability and inhibition. METHODS Eleven male subjects performed intermittent isometric elbow flexions at 50% of maximal voluntary contraction to task failure at SL and after 1 (D1) and 5 (D5) days at 4350 m. Transcranial magnetic stimulation and peripheral electrical stimulation were used to assess supraspinal and peripheral fatigues. Pre-frontal cortex and biceps brachii oxygenation was monitored by near-infrared spectroscopy. RESULTS Exercise duration was not statistically different between SL (1095 ± 562 s), D1 (1132 ± 516 s), and D5 (1440 ± 689 s). No significant differences were found between the three experimental conditions in maximal voluntary activation declines at task failure (SL -16.8 ± 9.5%; D1 -25.5 ± 11.2%; D5 -21.8 ± 7.0%; p > 0.05). Exercise-induced peripheral fatigue was larger at D5 versus SL (100 Hz doublet at task failure: -58.8 ± 16.6 versus -41.8 ± 20.1%; p < 0.05). Corticospinal excitability at 50% maximal voluntary contraction was lower at D5 versus SL (brachioradialis p < 0.05, biceps brachii p = 0.055). Cortical silent periods were shorter at SL versus D1 and D5 (p < 0.05). CONCLUSIONS The present results show similar patterns of supraspinal fatigue development during isometric elbow flexions at SL and after 1 and 5 days at high altitude, despite larger amount of peripheral fatigue at D5, lowered corticospinal excitability and enhanced corticospinal inhibition at altitude.
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Gourine AV, Funk GD. On the existence of a central respiratory oxygen sensor. J Appl Physiol (1985) 2017; 123:1344-1349. [PMID: 28522760 DOI: 10.1152/japplphysiol.00194.2017] [Citation(s) in RCA: 72] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2017] [Revised: 05/04/2017] [Accepted: 05/16/2017] [Indexed: 11/22/2022] Open
Abstract
A commonly held view that dominates both the scientific and educational literature is that in terrestrial mammals the central nervous system lacks a physiological hypoxia sensor capable of triggering increases in lung ventilation in response to decreases in Po2 of the brain parenchyma. Indeed, a normocapnic hypoxic ventilatory response has never been observed in humans following bilateral resection of the carotid bodies. In contrast, almost complete or partial recovery of the hypoxic ventilatory response after denervation/removal of the peripheral respiratory oxygen chemoreceptors has been demonstrated in many experimental animals when assessed in an awake state. In this essay we review the experimental evidence obtained using in vitro and in vivo animal models, results of human studies, and discuss potential mechanisms underlying the effects of CNS hypoxia on breathing. We consider experimental limitations and discuss potential reasons why the recovery of the hypoxic ventilatory response has not been observed in humans. We review recent experimental evidence suggesting that the lower brain stem contains functional oxygen sensitive elements capable of stimulating respiratory activity independently of peripheral chemoreceptor input.
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Affiliation(s)
- Alexander V Gourine
- Centre for Cardiovascular and Metabolic Neuroscience, Department of Neuroscience, Physiology & Pharmacology, University College London, London, United Kingdom; and
| | - Gregory D Funk
- Department of Physiology, Women and Children's Health Research Institute, Neuroscience and Mental Health Institute, University of Alberta, Edmonton, Alberta, Canada
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Gonzalez-Obeso E, Docio I, Olea E, Cogolludo A, Obeso A, Rocher A, Gomez-Niño A. Guinea Pig Oxygen-Sensing and Carotid Body Functional Properties. Front Physiol 2017; 8:285. [PMID: 28533756 PMCID: PMC5420588 DOI: 10.3389/fphys.2017.00285] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2017] [Accepted: 04/19/2017] [Indexed: 01/06/2023] Open
Abstract
Mammals have developed different mechanisms to maintain oxygen supply to cells in response to hypoxia. One of those mechanisms, the carotid body (CB) chemoreceptors, is able to detect physiological hypoxia and generate homeostatic reflex responses, mainly ventilatory and cardiovascular. It has been reported that guinea pigs, originally from the Andes, have a reduced ventilatory response to hypoxia compared to other mammals, implying that CB are not completely functional, which has been related to genetically/epigenetically determined poor hypoxia-driven CB reflex. This study was performed to check the guinea pig CB response to hypoxia compared to the well-known rat hypoxic response. These experiments have explored ventilatory parameters breathing different gases mixtures, cardiovascular responses to acute hypoxia, in vitro CB response to hypoxia and other stimuli and isolated guinea pig chemoreceptor cells properties. Our findings show that guinea pigs are hypotensive and have lower arterial pO2 than rats, probably related to a low sympathetic tone and high hemoglobin affinity. Those characteristics could represent a higher tolerance to hypoxic environment than other rodents. We also find that although CB are hypo-functional not showing chronic hypoxia sensitization, a small percentage of isolated carotid body chemoreceptor cells contain tyrosine hydroxylase enzyme and voltage-dependent K+ currents and therefore can be depolarized. However hypoxia does not modify intracellular Ca2+ levels or catecholamine secretion. Guinea pigs are able to hyperventilate only in response to intense acute hypoxic stimulus, but hypercapnic response is similar to rats. Whether other brain areas are also activated by hypoxia in guinea pigs remains to be studied.
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Affiliation(s)
- Elvira Gonzalez-Obeso
- Servicio de Anatomía Patológica, Hospital Clínico Universitario de ValladolidValladolid, Spain
| | - Inmaculada Docio
- Departamento de Bioquímica y Biología Molecular y Fisiología, Universidad de Valladolid, IBGM, CSICValladolid, Spain.,CIBER de Enfermedades Respiratorias, ISCiiiSpain
| | - Elena Olea
- CIBER de Enfermedades Respiratorias, ISCiiiSpain.,Departamento de Enfermería, Universidad de Valladolid, IBGM, CSICValladolid, Spain
| | - Angel Cogolludo
- CIBER de Enfermedades Respiratorias, ISCiiiSpain.,Departamento de Farmacología, Instituto de Investigación Sanitaria Gregorio Marañón, Universidad Complutense de MadridMadrid, Spain
| | - Ana Obeso
- Departamento de Bioquímica y Biología Molecular y Fisiología, Universidad de Valladolid, IBGM, CSICValladolid, Spain.,CIBER de Enfermedades Respiratorias, ISCiiiSpain
| | - Asuncion Rocher
- Departamento de Bioquímica y Biología Molecular y Fisiología, Universidad de Valladolid, IBGM, CSICValladolid, Spain.,CIBER de Enfermedades Respiratorias, ISCiiiSpain
| | - Angela Gomez-Niño
- CIBER de Enfermedades Respiratorias, ISCiiiSpain.,Departamento de Biología Celular, Histología y Farmacología, Universidad de Valladolid, IBGM, CSICValladolid, Spain
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Zhao B, Zheng Z. Insulin Growth Factor 1 Protects Neural Stem Cells Against Apoptosis Induced by Hypoxia Through Akt/Mitogen-Activated Protein Kinase/Extracellular Signal-Regulated Kinase (Akt/MAPK/ERK) Pathway in Hypoxia-Ishchemic Encephalopathy. Med Sci Monit 2017; 23:1872-1879. [PMID: 28420864 PMCID: PMC5405785 DOI: 10.12659/msm.901055] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Background Insulin growth factor 1 (IGF-1) is reported to modulate cell growth and acts as potential therapy for traumatic brain injury. This study was designed to investigate the effect of IGF-1 on hypoxia-induced apoptosis in neural stem cells (NSCs). Material/Methods A hypoxia model was constructed using NSCs separated from the hippocampus of rat. NSCs were divided into four groups: cells under normoxic conditions that acted as controls (C group), cells under hypoxia (H group), cells under hypoxia with IGF-1 (HI group), and cells under hypoxia with IGF-1 as well as picropodophyllin (PPP), which acts as an inhibitor of the IGF-1 receptor (HIP group). The cell viability and apoptosis were respectively measured by 3-(4,5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay and flow cytometry. Finally, the phosphorylation levels of apoptosis-associated proteins and key kinases in the phosphatidylinositol-3-kinase (PI3K)/AKT and the mitogen-activated protein kinase/extracellular signal-regulated kinase (MAPK/ERK) pathways were detected by Western blot analysis. Results In comparison with the H group, the cell viability was increased while the cell apoptosis was reduced by IGF-1 in the HI group. Besides, the expression levels of Bax, cytochrome c, and activated caspase-3 were all improved in the H group, and the remarkable differences were eliminated in the HI group compared with the C group. The expression level of Bcl-2 was the opposite. Additionally, down-regulations of phosphorylated AKT, MAPK, and ERK induced by hypoxia were all improved by IGF-1. All the influences of IGF-1 were weakened by addition of PPP. Conclusions IGF-1 increased cell viability while decreasing apoptosis in hypoxic NSCs through the PI3K/AKT and MAPK/ERK pathways.
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Affiliation(s)
- Bing Zhao
- Department of Children Rehabilitation, Jining No.1 People's Hospital, Jining, Shandong, China (mainland)
| | - Zebao Zheng
- Department of Children Rehabilitation, Jining No.1 People's Hospital, Jining, Shandong, China (mainland)
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Santin JM, Hartzler LK. Environmentally induced return to juvenile-like chemosensitivity in the respiratory control system of adult bullfrog, Lithobates catesbeianus. J Physiol 2016; 594:6349-6367. [PMID: 27444338 DOI: 10.1113/jp272777] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2016] [Accepted: 07/19/2016] [Indexed: 12/25/2022] Open
Abstract
KEY POINTS The degree to which developmental programmes or environmental signals determine physiological phenotypes remains a major question in physiology. Vertebrates change environments during development, confounding interpretation of the degree to which development (i.e. permanent processes) or phenotypic plasticity (i.e. reversible processes) produces phenotypes. Tadpoles mainly breathe water for gas exchange and frogs may breathe water or air depending on their environment and are, therefore, exemplary models to differentiate the degree to which life-stage vs. environmental context drives developmental phenotypes associated with neural control of lung breathing. Using isolated brainstem preparations and patch clamp electrophysiology, we demonstrate that adult bullfrogs acclimatized to water-breathing conditions do not exhibit CO2 and O2 chemosensitivity of lung breathing, similar to water-breathing tadpoles. Our results establish that phenotypes associated with developmental stage may arise from plasticity per se and suggest that a developmental trajectory coinciding with environmental change obscures origins of stage-dependent physiological phenotypes by masking plasticity. ABSTRACT An unanswered question in developmental physiology is to what extent does the environment vs. a genetic programme produce phenotypes? Developing animals inhabit different environments and switch from one to another. Thus a developmental time course overlapping with environmental change confounds interpretations as to whether development (i.e. permanent processes) or phenotypic plasticity (i.e. reversible processes) generates phenotypes. Tadpoles of the American bullfrog, Lithobates catesbeianus, breathe water at early life-stages and minimally use lungs for gas exchange. As adults, bullfrogs rely on lungs for gas exchange, but spend months per year in ice-covered ponds without lung breathing. Aquatic submergence, therefore, removes environmental pressures requiring lung breathing and enables separation of adulthood from environmental factors associated with adulthood that necessitate control of lung ventilation. To test the hypothesis that postmetamorphic respiratory control phenotypes arise through permanent developmental changes vs. reversible environmental signals, we measured respiratory-related nerve discharge in isolated brainstem preparations and action potential firing from CO2 -sensitive neurons in bullfrogs acclimatized to semi-terrestrial (air-breathing) and aquatic-overwintering (no air-breathing) habitats. We found that aquatic overwintering significantly reduced neuroventilatory responses to CO2 and O2 involved in lung breathing. Strikingly, this gas sensitivity profile reflects that of water-breathing tadpoles. We further demonstrated that aquatic overwintering reduced CO2 -induced firing responses of chemosensitive neurons. In contrast, respiratory rhythm generating processes remained adult-like after submergence. Our results establish that phenotypes associated with life-stage can arise from phenotypic plasticity per se. This provides evidence that developmental time courses coinciding with environmental changes obscure interpretations regarding origins of stage-dependent physiological phenotypes by masking plasticity.
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Affiliation(s)
- Joseph M Santin
- Department of Biological Sciences, Wright State University, 3640 Colonel Glenn Highway, Dayton, OH, 45435, USA. .,Biomedical Sciences PhD Program, Wright State University, 3640 Colonel Glenn Highway, Dayton, OH, 45435, USA.
| | - Lynn K Hartzler
- Department of Biological Sciences, Wright State University, 3640 Colonel Glenn Highway, Dayton, OH, 45435, USA
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Sunderram J, Semmlow J, Patel P, Rao H, Chun G, Agarwala P, Bhaumik M, Le-Hoang O, Lu SE, Neubauer JA. Heme oxygenase-1-dependent central cardiorespiratory adaptations to chronic intermittent hypoxia in mice. J Appl Physiol (1985) 2016; 121:944-952. [PMID: 27609199 DOI: 10.1152/japplphysiol.00036.2016] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2016] [Accepted: 09/06/2016] [Indexed: 11/22/2022] Open
Abstract
Chronic intermittent hypoxia (CIH) increases sympathetic tone and respiratory instability. Our previous work showed that chronic hypoxia induces the oxygen-sensing enzyme heme oxygenase-1 (HO-1) within the C1 sympathoexcitatory region and the pre-Bötzinger complex (pre-BötC). We therefore examined the effect of CIH on time course of induced expression of HO-1 within these regions and determined whether the induction of HO-1 correlated with changes in respiratory, sigh frequency, and sympathetic responses (spectral analysis of heart rate) to acute hypoxia (10% O2) during 10 days of exposure to CIH in chronically instrumented awake wild-type (WT) and HO-1 null mice (HO-1-/-). HO-1 was induced within the C1 and pre-BötC regions after 1 day of CIH. There were no significant differences in the baseline respiratory parameters between WT and HO-1-/- Prior to CIH, acute hypoxia increased respiratory frequency in both WT and HO-1-/-; however, minute diaphragm electromyogram activity increased in WT but not HO-1-/- The hypoxic respiratory response after 1 and 10 days of CIH was restored in HO-1-/- CIH resulted in an initial significant decline in 1) the hypoxic sigh frequency response, which was restored in WT but not HO-1-/-, and 2) the baseline sympathetic activity in WT and HO-1-/-, which remained stable subsequently in WT but not in HO-1-/- We conclude that 1) CIH induces expression of HO-1 in the C1 and pre-BötC regions within 1 day and 2) HO-1 is necessary for hypoxia respiratory response and contributes to the maintenance of the hypoxic sigh responses and baseline sympathetic activity during CIH.
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Affiliation(s)
- Jag Sunderram
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Rutgers Robert Wood Johnson Medical School, New Brunswick, New Jersey;
| | - John Semmlow
- Department of Surgery, Rutgers Robert Wood Johnson Medical School, New Brunswick, New Jersey
| | - Pranav Patel
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Rutgers Robert Wood Johnson Medical School, New Brunswick, New Jersey
| | - Harshit Rao
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Rutgers Robert Wood Johnson Medical School, New Brunswick, New Jersey
| | - Glen Chun
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Rutgers Robert Wood Johnson Medical School, New Brunswick, New Jersey
| | - Priya Agarwala
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Rutgers Robert Wood Johnson Medical School, New Brunswick, New Jersey
| | - Mantu Bhaumik
- Department of Pediatrics, Rutgers Robert Wood Johnson Medical School, New Brunswick, New Jersey; and
| | - Oanh Le-Hoang
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Rutgers Robert Wood Johnson Medical School, New Brunswick, New Jersey
| | - Shou-En Lu
- Department of Biostatistics, Rutgers School of Public Health, Piscataway, New Jersey
| | - Judith A Neubauer
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Rutgers Robert Wood Johnson Medical School, New Brunswick, New Jersey
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Partial Raphe Dysfunction in Neurotransmission Is Sufficient to Increase Mortality after Anoxic Exposures in Mice at a Critical Period in Postnatal Development. J Neurosci 2016; 36:3943-53. [PMID: 27053202 DOI: 10.1523/jneurosci.1796-15.2016] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2015] [Accepted: 02/26/2016] [Indexed: 12/22/2022] Open
Abstract
UNLABELLED Sudden infant death syndrome (SIDS) cases often have abnormalities of the brainstem raphe serotonergic (5-HT) system. We hypothesize that raphe dysfunction contributes to a failure to autoresuscitate from multiple hypoxic events, leading to SIDS. We studied autoresuscitation in two transgenic mouse models in which exocytic neurotransmitter release was impaired via conditional expression of the light chain from tetanus toxin (tox) in raphe neurons expressing serotonergic bacterial artificial chromosome drivers Pet1 or Slc6a4. These used recombinase drivers targeted different portions of medullary raphe serotonergic, tryptophan hydroxylase 2 (Tph2)(+) neurons by postnatal day (P) 5 through P12: approximately one-third in triple transgenic Pet1::Flpe, hβactin::cre, RC::PFtox mice; approximately three-fourths inSlc6a4::cre, RC::Ptox mice; with the first model capturing a near equal number of Pet1(+),Tph2(+) versus Pet1(+),Tph2(low or negative) raphe cells. At P5, P8, and P12, "silenced" mice and controls were exposed to five, ∼37 s bouts of anoxia. Mortality was 5-10 times greater in "silenced" pups compared with controls at P5 and P8 (p = 0.001) but not P12, with cumulative survival not differing between experimental transgenic models. "Silenced" pups that eventually died took longer to initiate gasping (p = 0.0001), recover heart rate (p = 0.0001), and recover eupneic breathing (p = 0.011) during the initial anoxic challenges. Variability indices for baseline breathing distinguished "silenced" from controls but did not predict mortality. We conclude that dysfunction of even a portion of the raphe, as observed in many SIDS cases, can impair ability to autoresuscitate at critical periods in postnatal development and that baseline indices of breathing variability can identify mice at risk. SIGNIFICANCE STATEMENT Many sudden infant death syndrome (SIDS) cases exhibit a partial (∼26%) brainstem serotonin deficiency. Using recombinase drivers, we targeted different fractions of serotonergic and raphe neurons in mice for tetanus toxin light chain expression, which prevented vesicular neurotransmitter release. In one model, approximately one-third of medullary Tph2(+) neurons are silenced by postnatal (P) days 5 and 12, along with some Pet1(+),Tph2(low or negative) raphe cells; in the other, approximately three-fourths of medullary Tph2(+) neurons, also with some Tph2(low or negative) cells. Both models demonstrated excessive mortality to anoxia (a postulated SIDS stressor) at P5 and P8. We demonstrated fatal vulnerability to anoxic stress at a specific time in postnatal life induced by a partial defect in raphe function. This models features of SIDS.
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Affiliation(s)
- Jean Schoenen
- University of Liège, Department of Neurology, Headache Research Unit, 4000 Liège, Belgium
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Pamenter ME, Powell FL. Time Domains of the Hypoxic Ventilatory Response and Their Molecular Basis. Compr Physiol 2016; 6:1345-85. [PMID: 27347896 DOI: 10.1002/cphy.c150026] [Citation(s) in RCA: 91] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Ventilatory responses to hypoxia vary widely depending on the pattern and length of hypoxic exposure. Acute, prolonged, or intermittent hypoxic episodes can increase or decrease breathing for seconds to years, both during the hypoxic stimulus, and also after its removal. These myriad effects are the result of a complicated web of molecular interactions that underlie plasticity in the respiratory control reflex circuits and ultimately control the physiology of breathing in hypoxia. Since the time domains of the physiological hypoxic ventilatory response (HVR) were identified, considerable research effort has gone toward elucidating the underlying molecular mechanisms that mediate these varied responses. This research has begun to describe complicated and plastic interactions in the relay circuits between the peripheral chemoreceptors and the ventilatory control circuits within the central nervous system. Intriguingly, many of these molecular pathways seem to share key components between the different time domains, suggesting that varied physiological HVRs are the result of specific modifications to overlapping pathways. This review highlights what has been discovered regarding the cell and molecular level control of the time domains of the HVR, and highlights key areas where further research is required. Understanding the molecular control of ventilation in hypoxia has important implications for basic physiology and is emerging as an important component of several clinical fields. © 2016 American Physiological Society. Compr Physiol 6:1345-1385, 2016.
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Affiliation(s)
| | - Frank L Powell
- Physiology Division, Department of Medicine, University of California San Diego, La Jolla, California, USA
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Rajani V, Zhang Y, Revill A, Funk G. The role of P2Y1 receptor signaling in central respiratory control. Respir Physiol Neurobiol 2016; 226:3-10. [DOI: 10.1016/j.resp.2015.10.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2015] [Accepted: 10/06/2015] [Indexed: 12/24/2022]
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Yu L, De Mazancourt M, Hess A, Ashadi FR, Klein I, Mal H, Courbage M, Mangin L. Functional connectivity and information flow of the respiratory neural network in chronic obstructive pulmonary disease. Hum Brain Mapp 2016; 37:2736-54. [PMID: 27059277 PMCID: PMC5071657 DOI: 10.1002/hbm.23205] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2015] [Revised: 02/15/2016] [Accepted: 03/23/2016] [Indexed: 01/06/2023] Open
Abstract
Breathing involves a complex interplay between the brainstem automatic network and cortical voluntary command. How these brain regions communicate at rest or during inspiratory loading is unknown. This issue is crucial for several reasons: (i) increased respiratory loading is a major feature of several respiratory diseases, (ii) failure of the voluntary motor and cortical sensory processing drives is among the mechanisms that precede acute respiratory failure, (iii) several cerebral structures involved in responding to inspiratory loading participate in the perception of dyspnea, a distressing symptom in many disease. We studied functional connectivity and Granger causality of the respiratory network in controls and patients with chronic obstructive pulmonary disease (COPD), at rest and during inspiratory loading. Compared with those of controls, the motor cortex area of patients exhibited decreased connectivity with their contralateral counterparts and no connectivity with the brainstem. In the patients, the information flow was reversed at rest with the source of the network shifted from the medulla towards the motor cortex. During inspiratory loading, the system was overwhelmed and the motor cortex became the sink of the network. This major finding may help to understand why some patients with COPD are prone to acute respiratory failure. Network connectivity and causality were related to lung function and illness severity. We validated our connectivity and causality results with a mathematical model of neural network. Our findings suggest a new therapeutic strategy involving the modulation of brain activity to increase motor cortex functional connectivity and improve respiratory muscles performance in patients. Hum Brain Mapp 37:2736–2754, 2016. © 2016 The Authors Human Brain Mapping Published by Wiley Periodicals, Inc.
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Affiliation(s)
- Lianchun Yu
- Department of PhysicsMatter and Complex Systems Research Laboratory, UMR 7057, CNRSParis 7 UniversityFrance
- Institute of Theoretical Physics, Lanzhou UniversityLanzhouChina
| | - Marine De Mazancourt
- Department of PhysicsMatter and Complex Systems Research Laboratory, UMR 7057, CNRSParis 7 UniversityFrance
- Ecole Normale SupérieureParisFrance
| | - Agathe Hess
- Neuroradiology DepartmentAPHP, Hôpital BichatFrance
| | - Fakhrul R. Ashadi
- Department of PhysicsMatter and Complex Systems Research Laboratory, UMR 7057, CNRSParis 7 UniversityFrance
| | | | - Hervé Mal
- Respiratory Disease DepartmentAPHP, Hôpital BichatFrance
| | - Maurice Courbage
- Department of PhysicsMatter and Complex Systems Research Laboratory, UMR 7057, CNRSParis 7 UniversityFrance
| | - Laurence Mangin
- Department of PhysicsMatter and Complex Systems Research Laboratory, UMR 7057, CNRSParis 7 UniversityFrance
- Department of PhysiologyAPHP, Hôpital BichatFrance
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Guyenet PG, Bayliss DA, Stornetta RL, Ludwig MG, Kumar NN, Shi Y, Burke PGR, Kanbar R, Basting TM, Holloway BB, Wenker IC. Proton detection and breathing regulation by the retrotrapezoid nucleus. J Physiol 2016; 594:1529-51. [PMID: 26748771 PMCID: PMC4799966 DOI: 10.1113/jp271480] [Citation(s) in RCA: 56] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2015] [Accepted: 01/04/2016] [Indexed: 01/26/2023] Open
Abstract
We discuss recent evidence which suggests that the principal central respiratory chemoreceptors are located within the retrotrapezoid nucleus (RTN) and that RTN neurons are directly sensitive to [H(+) ]. RTN neurons are glutamatergic. In vitro, their activation by [H(+) ] requires expression of a proton-activated G protein-coupled receptor (GPR4) and a proton-modulated potassium channel (TASK-2) whose transcripts are undetectable in astrocytes and the rest of the lower brainstem respiratory network. The pH response of RTN neurons is modulated by surrounding astrocytes but genetic deletion of RTN neurons or deletion of both GPR4 and TASK-2 virtually eliminates the central respiratory chemoreflex. Thus, although this reflex is regulated by innumerable brain pathways, it seems to operate predominantly by modulating the discharge rate of RTN neurons, and the activation of RTN neurons by hypercapnia may ultimately derive from their intrinsic pH sensitivity. RTN neurons increase lung ventilation by stimulating multiple aspects of breathing simultaneously. They stimulate breathing about equally during quiet wake and non-rapid eye movement (REM) sleep, and to a lesser degree during REM sleep. The activity of RTN neurons is regulated by inhibitory feedback and by excitatory inputs, notably from the carotid bodies. The latter input operates during normo- or hypercapnia but fails to activate RTN neurons under hypocapnic conditions. RTN inhibition probably limits the degree of hyperventilation produced by hypocapnic hypoxia. RTN neurons are also activated by inputs from serotonergic neurons and hypothalamic neurons. The absence of RTN neurons probably underlies the sleep apnoea and lack of chemoreflex that characterize congenital central hypoventilation syndrome.
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Affiliation(s)
- Patrice G Guyenet
- Department of Pharmacology, University of Virginia, Charlottesville, VA, 22908, USA
| | - Douglas A Bayliss
- Department of Pharmacology, University of Virginia, Charlottesville, VA, 22908, USA
| | - Ruth L Stornetta
- Department of Pharmacology, University of Virginia, Charlottesville, VA, 22908, USA
| | | | - Natasha N Kumar
- Department of Pharmacology, University of Virginia, Charlottesville, VA, 22908, USA
| | - Yingtang Shi
- Department of Pharmacology, University of Virginia, Charlottesville, VA, 22908, USA
| | - Peter G R Burke
- Department of Pharmacology, University of Virginia, Charlottesville, VA, 22908, USA
| | - Roy Kanbar
- Department of Pharmaceutical Sciences, Lebanese American University, Beyrouth, Lebanon
| | - Tyler M Basting
- Department of Pharmacology, University of Virginia, Charlottesville, VA, 22908, USA
| | - Benjamin B Holloway
- Department of Pharmacology, University of Virginia, Charlottesville, VA, 22908, USA
| | - Ian C Wenker
- Department of Pharmacology, University of Virginia, Charlottesville, VA, 22908, USA
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Shoemaker JK, Badrov MB, Al-Khazraji BK, Jackson DN. Neural Control of Vascular Function in Skeletal Muscle. Compr Physiol 2015; 6:303-29. [PMID: 26756634 DOI: 10.1002/cphy.c150004] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
The sympathetic nervous system represents a fundamental homeostatic system that exerts considerable control over blood pressure and the distribution of blood flow. This process has been referred to as neurovascular control. Overall, the concept of neurovascular control includes the following elements: efferent postganglionic sympathetic nerve activity, neurotransmitter release, and the end organ response. Each of these elements reflects multiple levels of control that, in turn, affect complex patterns of change in vascular contractile state. Primarily, this review discusses several of these control layers that combine to produce the integrative physiology of reflex vascular control observed in skeletal muscle. Beginning with three reflexes that provide somewhat dissimilar vascular patterns of response despite similar changes in efferent sympathetic nerve activity, namely, the baroreflex, chemoreflex, and muscle metaboreflex, the article discusses the anatomical and physiological bases of postganglionic sympathetic discharge patterns and recruitment, neurotransmitter release and management, and details of regional variations of receptor density and responses within the microvascular bed. Challenges are addressed regarding the fundamentals of measurement and how conclusions from one response or vascular segment should not be used as an indication of neurovascular control as a generalized physiological dogma. Whereas the bulk of the article focuses on the vasoconstrictor function of sympathetic neurovascular integration, attention is also given to the issues of sympathetic vasodilation as well as the impact of chronic changes in sympathetic activation and innervation on vascular health. © 2016 American Physiological Society.
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Affiliation(s)
- J K Shoemaker
- School of Kinesiology, Western University, London, Ontario, Canada.,Department of Physiology and Pharmacology, Western University, London, Ontario, Canada
| | - M B Badrov
- School of Kinesiology, Western University, London, Ontario, Canada
| | - B K Al-Khazraji
- Department of Medical Biophysics, Western University, London, Ontario, Canada
| | - D N Jackson
- Department of Medical Biophysics, Western University, London, Ontario, Canada
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47
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Neuromuscular fatigue during hypoxia is mediated by the hypoxic ventilatory response. EXTREME PHYSIOLOGY & MEDICINE 2015. [PMCID: PMC4580788 DOI: 10.1186/2046-7648-4-s1-a41] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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48
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Wang L, Cui S, Ma L, Kong L, Geng X. Current advances in the novel functions of hypoxia-inducible factor and prolyl hydroxylase in invertebrates. INSECT MOLECULAR BIOLOGY 2015; 24:634-648. [PMID: 26387499 DOI: 10.1111/imb.12189] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Oxygen is essential for aerobic life, and hypoxia has very severe consequences. Organisms need to overcome low oxygen levels to maintain biological functions during normal development and in disease states. The mechanism underlying the hypoxic response has been widely investigated in model animals such as Drosophila melanogaster and Caenorhabditis elegans. Hypoxia-inducible factor (HIF), a key gene product in the response to oxygen deprivation, is primarily regulated by prolyl hydroxylase domain enzymes (PHDs). However, recent findings have uncovered novel HIF-independent functions of PHDs. This review provides an overview of how invertebrates are able to sustain hypoxic damages, and highlights some recent discoveries in the regulation of cellular signalling by PHDs. Given that some core genes and major pathways are evolutionarily conserved, these research findings could provide insight into oxygen-sensitive signalling in mammals, and have biomedical implications for human diseases.
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Affiliation(s)
- L Wang
- School of Agriculture and Biology, Shanghai Jiao Tong University, Key Laboratory of Urban Agriculture (South), Ministry of Agriculture, Shanghai, China
| | - S Cui
- School of Agriculture and Biology, Shanghai Jiao Tong University, Key Laboratory of Urban Agriculture (South), Ministry of Agriculture, Shanghai, China
| | - L Ma
- School of Agriculture and Biology, Shanghai Jiao Tong University, Key Laboratory of Urban Agriculture (South), Ministry of Agriculture, Shanghai, China
| | - L Kong
- School of Agriculture and Biology, Shanghai Jiao Tong University, Key Laboratory of Urban Agriculture (South), Ministry of Agriculture, Shanghai, China
| | - X Geng
- School of Agriculture and Biology, Shanghai Jiao Tong University, Key Laboratory of Urban Agriculture (South), Ministry of Agriculture, Shanghai, China
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Feddersen B, Neupane P, Thanbichler F, Hadolt I, Sattelmeyer V, Pfefferkorn T, Waanders R, Noachtar S, Ausserer H. Regional differences in the cerebral blood flow velocity response to hypobaric hypoxia at high altitudes. J Cereb Blood Flow Metab 2015; 35:1846-51. [PMID: 26082017 PMCID: PMC4635241 DOI: 10.1038/jcbfm.2015.142] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/29/2015] [Revised: 03/16/2015] [Accepted: 05/15/2015] [Indexed: 11/09/2022]
Abstract
Symptoms of acute mountain sickness (AMS) may appear above 2,500 m altitude, if the time allowed for acclimatization is insufficient. As the mechanisms underlying brain adaptation to the hypobaric hypoxic environment are not fully understood, a prospective study was performed investigating neurophysiological changes by means of near infrared spectroscopy, electroencephalograpy (EEG), and transcranial doppler sonography at 100, 3,440 and 5,050 m above sea level in the Khumbu Himal, Nepal. Fourteen of the 26 mountaineers reaching 5,050 m altitude developed symptoms of AMS between 3,440 and 5,050 m altitude (Lake-Louise Score ⩾3). Their EEG frontal beta activity and occipital alpha activity increased between 100 and 3,440 m altitude, i.e., before symptoms appeared. Cerebral blood flow velocity (CBFV) in the anterior and middle cerebral arteries (MCAs) increased in all mountaineers between 100 and 3,440 m altitude. During further ascent to 5,050 altitude, mountaineers with AMS developed a further increase in CBFV in the MCA, whereas in all mountaineers CBFV decreased continuously with increasing altitude in the posterior cerebral arteries. These results indicate that hypobaric hypoxia causes different regional changes in CBFV despite similar electrophysiological changes.
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Affiliation(s)
- Berend Feddersen
- Department of Neurology, Klinikum Grosshadern, University of Munich, Munich, Germany.,Department of Palliative Medicine, Specialized Palliative Home Care Team, University of Munich, Munich, Germany
| | - Pritam Neupane
- Department of Internal Medicine, Sinai Hospital, Johns Hopkins University, Baltimore, Maryland, USA
| | - Florian Thanbichler
- Department of Neurology, Klinikum Grosshadern, University of Munich, Munich, Germany
| | - Irmgard Hadolt
- Research Unit of Biomedical Engineering in Anesthesia and Intensive Care Medicine, Medical University of Graz, Graz, Austria
| | - Vera Sattelmeyer
- Klinik für Neurochirurgie, Dr Horst Schmidt Klinik, Wiesbaden, Germany
| | - Thomas Pfefferkorn
- Department of Neurology, Klinikum Grosshadern, University of Munich, Munich, Germany
| | - Robb Waanders
- Department of Neuropsychology, Landeskrankenhaus Rankweil, Rankweil, Austria
| | - Soheyl Noachtar
- Department of Neurology, Klinikum Grosshadern, University of Munich, Munich, Germany
| | - Harald Ausserer
- Department of Neurology, Klinikum Grosshadern, University of Munich, Munich, Germany.,Department of Neurology, Franz-Tappeiner Krankenhaus, Meran, Italy
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50
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Abstract
In terrestrial mammals, the oxygen storage capacity of the CNS is limited, and neuronal function is rapidly impaired if oxygen supply is interrupted even for a short period of time. However, oxygen tension monitored by the peripheral (arterial) chemoreceptors is not sensitive to regional CNS differences in partial pressure of oxygen (PO2 ) that reflect variable levels of neuronal activity or local tissue hypoxia, pointing to the necessity of a functional brain oxygen sensor. This experimental animal (rats and mice) study shows that astrocytes, the most numerous brain glial cells, are sensitive to physiological changes in PO2 . Astrocytes respond to decreases in PO2 a few millimeters of mercury below normal brain oxygenation with elevations in intracellular calcium ([Ca(2+)]i). The hypoxia sensor of astrocytes resides in the mitochondria in which oxygen is consumed. Physiological decrease in PO2 inhibits astroglial mitochondrial respiration, leading to mitochondrial depolarization, production of free radicals, lipid peroxidation, activation of phospholipase C, IP3 receptors, and release of Ca(2+) from the intracellular stores. Hypoxia-induced [Ca(2+)]i increases in astrocytes trigger fusion of vesicular compartments containing ATP. Blockade of astrocytic signaling by overexpression of ATP-degrading enzymes or targeted astrocyte-specific expression of tetanus toxin light chain (to interfere with vesicular release mechanisms) within the brainstem respiratory rhythm-generating circuits reveals the fundamental physiological role of astroglial oxygen sensitivity; in low-oxygen conditions (environmental hypoxia), this mechanism increases breathing activity even in the absence of peripheral chemoreceptor oxygen sensing. These results demonstrate that astrocytes are functionally specialized CNS oxygen sensors tuned for rapid detection of physiological changes in brain oxygenation. Significance statement: Most, if not all, animal cells possess mechanisms that allow them to detect decreases in oxygen availability leading to slow-timescale, adaptive changes in gene expression and cell physiology. To date, only two types of mammalian cells have been demonstrated to be specialized for rapid functional oxygen sensing: glomus cells of the carotid body (peripheral respiratory chemoreceptors) that stimulate breathing when oxygenation of the arterial blood decreases; and pulmonary arterial smooth muscle cells responsible for hypoxic pulmonary vasoconstriction to limit perfusion of poorly ventilated regions of the lungs. Results of the present study suggest that there is another specialized oxygen-sensitive cell type in the body, the astrocyte, that is tuned for rapid detection of physiological changes in brain oxygenation.
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