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Ghatak S, Kumar Sikdar S. Prolonged exposure to lactate causes TREK1 channel clustering in rat hippocampal astrocytes. Neurosci Lett 2024; 821:137613. [PMID: 38157928 DOI: 10.1016/j.neulet.2023.137613] [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: 11/27/2023] [Accepted: 12/21/2023] [Indexed: 01/03/2024]
Abstract
Increased concentrations of lactate (15-30 mM) are associated with and found to be neuroprotective in various brain pathophysiology. In our earlier studies we showed that high levels of lactate can increase TREK1 channel activity and expression within 1 h. TREK1 channels are two pore domain leak potassium ion channels that are upregulated during cerebral ischemia, epilepsy and other brain pathologies. They play a prominent neuroprotective role against excitotoxicity. Although it has been previously shown that chronic application of lactate (6 h) causes increased gene transcription and protein expression, we observe clustering of TREK1 channels that is dependent on time of exposure (3-6 h) and concentration of lactate (15-30 mM). Using immunofluorescence techniques and image analysis, we show that the clustering of TREK1 channels is dependent on the actin cytoskeletal network of the astrocytes. Clustering of TREK1 channels can augment astrocytic functions during pathophysiological conditions and have significant implications in lactate mediated neuroprotection.
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Affiliation(s)
- Swagata Ghatak
- School of Biological Sciences, National Institute of Science Education and Research (NISER)-Bhubaneswar, an OCC of Homi Bhabha National Institute, Jatani, Odisha 752050, India; Molecular Biophysics Unit, Indian Institute of Science, Bangalore, Karnataka 560012, India.
| | - Sujit Kumar Sikdar
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore, Karnataka 560012, India.
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2
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Huang Y, Li S, Wang Y, Yan Z, Guo Y, Zhang L. A Novel 5-Chloro-N-phenyl-1H-indole-2-carboxamide Derivative as Brain-Type Glycogen Phosphorylase Inhibitor: Potential Therapeutic Effect on Cerebral Ischemia. Molecules 2022; 27:molecules27196333. [PMID: 36234871 PMCID: PMC9572471 DOI: 10.3390/molecules27196333] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2022] [Revised: 09/20/2022] [Accepted: 09/23/2022] [Indexed: 11/16/2022] Open
Abstract
Brain-type glycogen phosphorylase inhibitors are potential new drugs for treating ischemic brain injury. In our previous study, we reported compound 1 as a novel brain-type glycogen phosphorylase inhibitor with cardioprotective properties. We also found that compound 1 has high blood–brain barrier permeability through the ADMET prediction website. In this study, we deeply analyzed the protective effect of compound 1 on hypoxic-ischemic brain injury, finding that compound 1 could alleviate the hypoxia/reoxygenation (H/R) injury of astrocytes by improving cell viability and reducing LDH leakage rate, intracellular glucose content, and post-ischemic ROS level. At the same time, compound 1 could reduce the level of ATP in brain cells after ischemia, improve cellular energy metabolism, downregulate the degree of extracellular acidification, and improve metabolic acidosis. It could also increase the level of mitochondrial aerobic energy metabolism during brain cell reperfusion, reduce anaerobic glycolysis, and inhibit apoptosis and the expression of apoptosis-related proteins. The above results indicated that compound 1 is involved in the regulation of glucose metabolism, can control cell apoptosis, and has protective and potential therapeutic effects on cerebral ischemia-reperfusion injury, which provides a new reference and possibility for the development of novel drugs for the treatment of ischemic brain injury.
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Affiliation(s)
- Yatao Huang
- Laboratory of Traditional Chinese Medicine Research and Development of Hebei Province, Institute of Traditional Chinese Medicine, Chengde Medical University, Chengde 067000, China
| | - Shuai Li
- Laboratory of Traditional Chinese Medicine Research and Development of Hebei Province, Institute of Traditional Chinese Medicine, Chengde Medical University, Chengde 067000, China
| | - Youde Wang
- Laboratory of Traditional Chinese Medicine Research and Development of Hebei Province, Institute of Traditional Chinese Medicine, Chengde Medical University, Chengde 067000, China
| | - Zhiwei Yan
- Laboratory of Traditional Chinese Medicine Research and Development of Hebei Province, Institute of Traditional Chinese Medicine, Chengde Medical University, Chengde 067000, China
| | - Yachun Guo
- Department of Pathogen Biology, Chengde Medical University, Chengde 067000, China
- Correspondence: (Y.G.); (L.Z.); Tel.: +86-0314-229-1000 (L.Z.)
| | - Liying Zhang
- Laboratory of Traditional Chinese Medicine Research and Development of Hebei Province, Institute of Traditional Chinese Medicine, Chengde Medical University, Chengde 067000, China
- Correspondence: (Y.G.); (L.Z.); Tel.: +86-0314-229-1000 (L.Z.)
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Spees WM, Sukstanskii AL, Bretthorst GL, Neil JJ, Ackerman JJH. Rat Brain Global Ischemia-Induced Diffusion Changes Revisited: Biophysical Modeling of the Water and NAA MR "Diffusion Signal". Magn Reson Med 2022; 88:1333-1346. [PMID: 35452137 DOI: 10.1002/mrm.29262] [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: 10/12/2021] [Revised: 03/18/2022] [Accepted: 03/20/2022] [Indexed: 11/06/2022]
Abstract
PURPOSE To assess changes in intracellular diffusion as a mechanism for the reduction in water ADC that accompanies brain injury. Using NAA as a marker of neuronal cytoplasmic diffusion, NAA diffusion was measured before and after global ischemia (immediately postmortem) in the female Sprague-Dawley rat. METHODS Diffusion-weighted PRESS spectra, with diffusion encoding in a single direction, were acquired from large voxels of rat brain gray matter in vivo and postischemia employing either pairs of pulsed half-sine-shaped gradients (in vivo and postischemia, bmax = 19 ms/μm2 ) or sinusoidal oscillating gradients (in vivo only) with frequencies of 99.2-250 Hz. A 2D randomly oriented cylinder (neurite) model gave estimates of longitudinal and transverse diffusivities (DL and DT , respectively). In this model, DL represents the "free" diffusivity of NAA, whereas DT reflects highly restricted diffusion. Using oscillating gradients, the frequency dependence of DT [DT (ω)] gave estimates of the cylinder (axon/dendrite) radius. RESULTS A 10% decrease in DL,NAA followed global ischemia, dropping from 0.391 ± 0.012 μm2 /ms to 0.350 ± 0.009 μm2 /ms. Modeling DT,NAA (ω) provided an estimate of the neurite radius of 1.0 ± 0.6 μm. CONCLUSION Whereas the increase in apparent intraneuronal viscosity suggested by changes in DL,NAA may contribute to the overall reduction in water ADC associated with brain injury, it is not sufficient to be the sole explanation. Estimates of neurite radius based on DT (ω) were consistent with literature values.
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Affiliation(s)
- William M Spees
- Biomedical MR Laboratory, Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, Missouri
| | - Alex L Sukstanskii
- Biomedical MR Laboratory, Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, Missouri
| | - G Larry Bretthorst
- Biomedical MR Laboratory, Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, Missouri
| | - Jeffrey J Neil
- Biomedical MR Laboratory, Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, Missouri.,Department of Neurology, Washington University School of Medicine, St. Louis, Missouri.,Department of Pediatrics, Washington University School of Medicine, St. Louis, Missouri
| | - Joseph J H Ackerman
- Biomedical MR Laboratory, Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, Missouri.,Department of Chemistry, Washington University, St. Louis, Missouri.,Department of Internal Medicine, Washington University School of Medicine, St. Louis, Missouri.,Alvin J Siteman Cancer Center, Washington University School of Medicine, St. Louis, Missouri
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Lactate Supply from Astrocytes to Neurons and its Role in Ischemic Stroke-induced Neurodegeneration. Neuroscience 2022; 481:219-231. [PMID: 34843897 DOI: 10.1016/j.neuroscience.2021.11.035] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2021] [Revised: 11/19/2021] [Accepted: 11/22/2021] [Indexed: 01/10/2023]
Abstract
Glucose transported to the brain is metabolized to lactate in astrocytes and supplied to neuronal cells via a monocarboxylic acid transporter (MCT). Lactate is used in neuronal cells for various functions, including learning and memory formation. Furthermore, lactate can block stroke-induced neurodegeneration. We aimed to clarify the effect of astrocyte-produced lactate on stroke-induced neurodegeneration. Previously published in vivo and in vitro animal and cell studies, respectively, were searched in PubMed, ScienceDirect, and Web of Science. Under physiological conditions, lactate production and release by astrocytes are regulated by changes in lactate dehydrogenase (LDH) and MCT expression. Moreover, considering stroke, lactate production and supply are regulated through hypoxia-inducible factor (HIF)-1α expression, especially with hypoxic stimulation, which may promote neuronal apoptosis; contrastingly, neuronal survival may be promoted via HIF-1α. Stroke stimulation could prevent neurodegeneration through the strong enhancement of lactate production, as well as upregulation of MCT4 expression to accelerate lactate supply. However, studies using astrocytes derived from animal stroke models revealed significantly reduced lactate production and MCT expression. These findings suggest that the lack of lactate supply may strongly contribute to hypoxia-induced neurodegeneration. Furthermore, diminished lactate supply from astrocytes could facilitate stroke-induced neurodegeneration. Therefore, astrocyte-derived lactate may contribute to stroke prevention.
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Nguyen H, Zerimech S, Baltan S. Astrocyte Mitochondria in White-Matter Injury. Neurochem Res 2021; 46:2696-2714. [PMID: 33527218 PMCID: PMC8935665 DOI: 10.1007/s11064-021-03239-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Revised: 01/05/2021] [Accepted: 01/06/2021] [Indexed: 12/11/2022]
Abstract
This review summarizes the diverse structure and function of astrocytes to describe the bioenergetic versatility required of astrocytes that are situated at different locations. The intercellular domain of astrocyte mitochondria defines their roles in supporting and regulating astrocyte-neuron coupling and survival against ischemia. The heterogeneity of astrocyte mitochondria, and how subpopulations of astrocyte mitochondria adapt to interact with other glia and regulate axon function, require further investigation. It has become clear that mitochondrial permeability transition pores play a key role in a wide variety of human diseases, whose common pathology may be based on mitochondrial dysfunction triggered by Ca2+ and potentiated by oxidative stress. Reactive oxygen species cause axonal degeneration and a reduction in axonal transport, leading to axonal dystrophies and neurodegeneration including Alzheimer's disease, amyotrophic lateral sclerosis, Parkinson's disease, and Huntington's disease. Developing new tools to allow better investigation of mitochondrial structure and function in astrocytes, and techniques to specifically target astrocyte mitochondria, can help to unravel the role of mitochondrial health and dysfunction in a more inclusive context outside of neuronal cells. Overall, this review will assess the value of astrocyte mitochondria as a therapeutic target to mitigate acute and chronic injury in the CNS.
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Affiliation(s)
- Hung Nguyen
- Anesthesiology and Peri-Operative Medicine (APOM), Oregon Health and Science University, Portland, OR, 97239, USA
| | - Sarah Zerimech
- Anesthesiology and Peri-Operative Medicine (APOM), Oregon Health and Science University, Portland, OR, 97239, USA
| | - Selva Baltan
- Anesthesiology and Peri-Operative Medicine (APOM), Oregon Health and Science University, Portland, OR, 97239, USA.
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Sadowska M, Mehlhorn C, Średniawa W, Szewczyk ŁM, Szlachcic A, Urban P, Winiarski M, Jabłonka JA. Spreading Depressions and Periinfarct Spreading Depolarizations in the Context of Cortical Plasticity. Neuroscience 2020; 453:81-101. [PMID: 33227236 DOI: 10.1016/j.neuroscience.2020.10.032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2019] [Revised: 10/26/2020] [Accepted: 10/27/2020] [Indexed: 11/17/2022]
Abstract
Studies of cortical function-recovery require a comparison between normal and post-stroke conditions that lead to changes in cortical metaplasticity. Focal cortical stroke impairs experience-dependent plasticity in the neighboring somatosensory cortex and usually evokes periinfarct depolarizations (PiDs) - spreading depression-like waves. Experimentally induced spreading depressions (SDs) affect gene expression and some of these changes persist for at least 30 days. In this study we compare the effects of non-stroke depolarizations that impair cortical experience-dependent plasticity to the effects of stroke, by inducing experience-dependent plasticity in rats with SDs or PiDs by a month of contralateral partial whiskers deprivation. We found that whiskers' deprivation after SDs resulted in normal cortical representation enlargement suggesting that SDs and PiDs depolarization have no influence on experience-dependent plasticity cortical map reorganization. PiDs and the MMP-9, -3, -2 or COX-2 proteins, which are assumed to influence metaplasticity in rats after stroke were compared between SDs induced by high osmolarity KCl solution and the PiDs that followed cortical photothrombotic stroke (PtS). We found that none of these factors directly caused cortical post-stroke metaplasticity changes. The only significant difference between stoke and induced SD was a greater imbalance in interhemispheric activity equilibrium after stroke. The interhemispheric interactions that were modified by stroke may therefore be promising targets for future studies of post-stroke experience-dependent plasticity and of recuperation studies.
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Affiliation(s)
- Maria Sadowska
- Laboratory of Animal Physiology, Faculty of Biology, University of Warsaw, Warsaw, Poland
| | | | - Władysław Średniawa
- Laboratory of Neuroinformatics, Nencki Institute of Experimental Biology of PAS, Warsaw, Poland; Laboratory of Animal Physiology, Faculty of Biology, University of Warsaw, Warsaw, Poland; College of Inter-Faculty Individual Studies in Mathematics and Natural Sciences, University of Warsaw, Warsaw, Poland
| | - Łukasz M Szewczyk
- Laboratory of Molecular Neurobiology, Centre of New Technologies, University of Warsaw, Warsaw, Poland
| | - Aleksandra Szlachcic
- Laboratory of Animal Physiology, Faculty of Biology, University of Warsaw, Warsaw, Poland
| | - Paulina Urban
- Laboratory of Functional and Structural Genomics, Center of New Technologies, University of Warsaw, Warsaw, Poland; College of Inter-Faculty Individual Studies in Mathematics and Natural Sciences, University of Warsaw, Warsaw, Poland
| | - Maciej Winiarski
- Laboratory of Emotions Neurobiology, Nencki Institute of Experimental Biology, PAS, Warsaw, Poland
| | - Jan A Jabłonka
- Laboratory of Animal Physiology, Faculty of Biology, University of Warsaw, Warsaw, Poland.
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Functional validation of a human GLUD2 variant in a murine model of Parkinson's disease. Cell Death Dis 2020; 11:897. [PMID: 33093440 PMCID: PMC7582183 DOI: 10.1038/s41419-020-03043-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2020] [Revised: 09/17/2020] [Accepted: 09/21/2020] [Indexed: 02/06/2023]
Abstract
Parkinson's disease (PD) is a common neurodegenerative disease characterized by Lewy body formation and progressive dopaminergic neuron death in the substantia nigra (SN). Genetic susceptibility is a strong risk factor for PD. Previously, a rare gain-of-function variant of GLUD2 glutamate dehydrogenase (T1492G) was reported to be associated with early onset in male PD patients; however, the function and underlying mechanism of this variant remains elusive. In the present study, we generated adeno-associated virus expressing GLUD2 and its mutant under the control of the glial fibrillary acidic protein promotor and injected the virus into the SN pars compacta of either untreated mice or 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced PD model mice. Our results demonstrate that GLUD2 mutation in MPTP-induced PD mice exacerbates movement deficits and nigral dopaminergic neuron death and reduces glutamate transporters expression and function. Using GC-Q-TOF/MS-based metabolomics, we determined that GLUD2 mutation damages mitochondrial function by decreasing succinate dehydrogenase activity to impede the tricarboxylic acid cycle in the SN of MPTP-induced PD mice. Accordingly, GLUD2 mutant mice had reduced energy metabolism and increased apoptosis, possibly due to downregulation of brain-derived neurotrophic factor/nuclear factor E2-related factor 2 signaling in in vitro and in vivo PD models. Collectively, our findings verify the function of GLUD2 in PD and unravel a mechanism by which a genetic variant in human GLUD2 may contribute to disease onset.
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Zhu J, Yang LK, Wang QH, Lin W, Feng Y, Xu YP, Chen WL, Xiong K, Wang YH. NDRG2 attenuates ischemia-induced astrocyte necroptosis via the repression of RIPK1. Mol Med Rep 2020; 22:3103-3110. [PMID: 32945444 PMCID: PMC7453600 DOI: 10.3892/mmr.2020.11421] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2019] [Accepted: 11/20/2019] [Indexed: 12/25/2022] Open
Abstract
Cerebral ischemia results in severe brain damage, and is a leading cause of death and long-term disability. Previous studies have investigated methods to activate astrocytes in order to promote repair in injured brain tissue and inhibit cell death. It has previously been shown that N-myc downstream-regulated gene 2 (NDRG2) was highly expressed in astrocytes and associated with cell activity, but the underlying mechanism is largely unknown. The present study generated NDRG2 conditional knockout (Ndrg2-/-) mice to investigate whether NDRG2 can block ischemia-induced astrocyte necroptosis by suppressing receptor interacting protein kinase 1 (RIPK1) expression. This study investigated astrocyte activity in cerebral ischemia, and identified that ischemic brain injuries could trigger RIP-dependent astrocyte necroptosis. The depletion of NDRG2 was found to accelerate permanent middle cerebral artery occlusion-induced necroptosis in the brain tissue of Ndrg2-/- mice, indicating that NDRG2 may act as a neuroprotector during cerebral ischemic injury. The present study suggested that NDRG2 attenuated astrocytic cell death via the suppression of RIPK1. The pharmacological inhibition of astrocyte necroptosis by necrostatin-1 provided neuroprotection against ischemic brain injuries after NDRG2 knockdown. Therefore, NDRG2 could be considered as a potential target for the treatment of cerebral ischemia.
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Affiliation(s)
- Jie Zhu
- Department of Neurosurgery, The 101 Hospital of PLA, School of Medicine, Anhui Medical University, Wuxi, Jiangsu 214044, P.R. China
| | - Li-Kun Yang
- Department of Neurosurgery, The 101 Hospital of PLA, School of Medicine, Anhui Medical University, Wuxi, Jiangsu 214044, P.R. China
| | - Qiu-Hong Wang
- Department of Ophthalmology, Wuxi Second Hospital Affiliated to Nanjing Medical University, Wuxi, Jiangsu 214002, P.R. China
| | - Wei Lin
- Department of Neurosurgery, The 101 Hospital of PLA, School of Medicine, Anhui Medical University, Wuxi, Jiangsu 214044, P.R. China
| | - Yi Feng
- Department of Neurosurgery, The 101 Hospital of PLA, School of Medicine, Anhui Medical University, Wuxi, Jiangsu 214044, P.R. China
| | - Ye-Ping Xu
- Department of Neurosurgery, The 101 Hospital of PLA, School of Medicine, Anhui Medical University, Wuxi, Jiangsu 214044, P.R. China
| | - Wei-Liang Chen
- Department of Neurosurgery, The 101 Hospital of PLA, School of Medicine, Anhui Medical University, Wuxi, Jiangsu 214044, P.R. China
| | - Kun Xiong
- Department of Anatomy and Neurobiology, School of Basic Medical Sciences, Central South University, Changsha, Hunan 410013, P.R. China
| | - Yu-Hai Wang
- Department of Neurosurgery, The 101 Hospital of PLA, School of Medicine, Anhui Medical University, Wuxi, Jiangsu 214044, P.R. China
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Astrocyte glutathione maintains endothelial barrier stability. Redox Biol 2020; 34:101576. [PMID: 32502899 PMCID: PMC7267730 DOI: 10.1016/j.redox.2020.101576] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2020] [Revised: 04/28/2020] [Accepted: 05/10/2020] [Indexed: 12/30/2022] Open
Abstract
Blood-brain barrier (BBB) impairment clearly accelerates brain disease progression. As ways to prevent injury-induced barrier dysfunction remain elusive, better understanding of how BBB cells interact and modulate barrier integrity is needed. Our metabolomic profiling study showed that cell-specific adaptation to injury correlates well with metabolic reprogramming at the BBB. In particular we noted that primary astrocytes (AC) contain comparatively high levels of glutathione (GSH)-related metabolites compared to primary endothelial cells (EC). Injury significantly disturbed redox balance in 10.13039/501100000780EC but not AC motivating us to assess 1) whether an AC-10.13039/501100000780EC GSH shuttle supports barrier stability and 2) the impact of GSH on 10.13039/501100000780EC function. Using an isotopic labeling/tracking approach combined with Time-of-Flight Mass Spectrometry (TOF-MS) we prove that AC constantly shuttle GSH to EC even under resting conditions - a flux accelerated by injury conditions in vitro. In correlation, co-culture studies revealed that blocking AC GSH generation and secretion via siRNA-mediated γ-glutamyl cysteine ligase (GCL) knockdown significantly compromises EC barrier integrity. Using different GSH donors, we further show that exogenous GSH supplementation improves barrier function by maintaining organization of tight junction proteins and preventing injury-induced tight junction phosphorylation. Thus the AC GSH shuttle is key for maintaining EC redox homeostasis and BBB stability suggesting GSH supplementation could improve recovery after brain injury. Astrocytes maintain better redox homeostasis during injury conditions than brain endothelial cells. Astrocyte-secreted glutathione abrogates injury-induced endothelial permeability. Exogenous GSH prevents injury-induced tight junction disruption. Better understanding of metabolic paracellular crosstalk could offer more opportunities to safeguard BBB integrity.
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Song X, Gong Z, Liu K, Kou J, Liu B, Liu K. Baicalin combats glutamate excitotoxicity via protecting glutamine synthetase from ROS-induced 20S proteasomal degradation. Redox Biol 2020; 34:101559. [PMID: 32473460 PMCID: PMC7260594 DOI: 10.1016/j.redox.2020.101559] [Citation(s) in RCA: 64] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2020] [Revised: 04/23/2020] [Accepted: 04/27/2020] [Indexed: 12/21/2022] Open
Abstract
Background Many neuroprotective approaches targeting neurons in animal models fail to provide benefits for the treatment of ischemic stroke in clinic and glial cells have become the targets in some basic studies. Baicalin has neuroprotective effects but the mechanisms related to glial cells are not revealed. This study investigated whether and how baicalin can combat excitotoxicity via protecting the functions of astrocytes in early stage of ischemia/reperfusion (I/R) insult by focusing on glutamine synthetase (GS). Experimental approach The role of baicalin was explored in primary astrocytes exposed to oxygen-glucose deprivation/reperfusion (OGD/R) and rats subjected to middle cerebral artery occlusion/reperfusion (MCAO/R). Key results Mitochondrial succinate dehydrogenase (SDH) activation led to an excessive production of reactive oxygen species (ROS) via reverse electron transport (RET) under conditions of OGD/R or I/R, which increased the carbonylation and proteasomal degradation of GS in astrocytes. Treatment of baicalin decreased the oxidative stress mediated by SDH and reduced the subsequent loss of GS. This effect increased the glutamate disposal by astrocytes and protected neurons from excitotoxicity in response to I/R insults. Conclusions and implications Baicalin inactivated SDH to suppress ROS production and protected GS protein stability against oxidative stress, contributing to the improvement of the glutamate disposal and decrease in excitotoxicity. These results suggest that protection of GS stability in astrocytes might be an effective strategy to prevent neuronal injury in acute ischemic stroke. SDH activation induced the excessive ROS production during early reperfusion. Activated SDH-induced GS degradation by 20S proteasome impaired glutamate disposal. Baicalin inactivated SDH, decreased GS loss and suppressed excitotoxicity.
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Affiliation(s)
- Xianrui Song
- Department of Pharmacology of Chinese Materia Medica, School of Traditional Chinese Pharmacy, China Pharmaceutical University, 639 Longmian Road, Nanjing, 211198, China
| | - Zixuan Gong
- Department of Pharmacology of Chinese Materia Medica, School of Traditional Chinese Pharmacy, China Pharmaceutical University, 639 Longmian Road, Nanjing, 211198, China
| | - Kaili Liu
- Department of Pharmacology of Chinese Materia Medica, School of Traditional Chinese Pharmacy, China Pharmaceutical University, 639 Longmian Road, Nanjing, 211198, China
| | - Junping Kou
- Department of Pharmacology of Chinese Materia Medica, School of Traditional Chinese Pharmacy, China Pharmaceutical University, 639 Longmian Road, Nanjing, 211198, China; Jiangsu Key Laboratory of TCM Evaluation and Translational Research, School of Traditional Chinese Pharmacy, China Pharmaceutical University, 639 Longmian Road, Nanjing, 211198, China
| | - Baolin Liu
- Department of Pharmacology of Chinese Materia Medica, School of Traditional Chinese Pharmacy, China Pharmaceutical University, 639 Longmian Road, Nanjing, 211198, China; Jiangsu Key Laboratory of TCM Evaluation and Translational Research, School of Traditional Chinese Pharmacy, China Pharmaceutical University, 639 Longmian Road, Nanjing, 211198, China
| | - Kang Liu
- Department of Pharmacology of Chinese Materia Medica, School of Traditional Chinese Pharmacy, China Pharmaceutical University, 639 Longmian Road, Nanjing, 211198, China; Jiangsu Key Laboratory of TCM Evaluation and Translational Research, School of Traditional Chinese Pharmacy, China Pharmaceutical University, 639 Longmian Road, Nanjing, 211198, China.
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Dong R, Chen M, Liu J, Kang J, Zhu S. Temporospatial effects of acyl-ghrelin on activation of astrocytes after ischaemic brain injury. J Neuroendocrinol 2019; 31:e12767. [PMID: 31276248 DOI: 10.1111/jne.12767] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/13/2018] [Revised: 06/04/2019] [Accepted: 06/30/2019] [Indexed: 12/13/2022]
Abstract
The protective mechanisms of astrocyte signalling are based on the release of neurotrophic factors and the clearing of toxic substances in the early stages of cerebral ischaemia. However, astrocytes are also responsible for the detrimental effects that occur during the later stages of ischaemia, in which glial scars are formed, thereby impeding neural recovery. Acyl-ghrelin has been found to be neuroprotective after stroke, although the influence of acyl-ghrelin on astrocytes after ischaemic injury is yet to be clarified. In the present study, we used permanent middle cerebral arterial occlusion to establish a brain ischaemia model in vivo, as well as oxygen and glucose deprivation (OGD) to mimic ischaemic insults in vitro. We found that acyl-ghrelin injection significantly increased the number of activated astrocytes in the peri-infarct area at day 3 after brain ischaemia and decreased the number of activated astrocytes after day 9. Moreover, the expression of fibroblast growth factor 2 (FGF2) in the ischaemic hemisphere increased markedly after day 3, and i.c.v. injection of SU5402, an inhibitor of FGF2 signalling, abolished the suppression effects of acyl-ghrelin on astrocyte activation in the peri-infarct region during the later stages of ischaemia. The results from in vitro studies also showed the dual effect of acyl-ghrelin on astrocyte viability. Acyl-ghrelin increased the viability of uninjured astrocytes in an indirect way by stimulating the secretion from OGD-injured astrocytes. It also inhibited the astrocyte viability in the presence of FGF2 in a dose-dependent manner. Furthermore, the expression of acyl-ghrelin receptors on astrocytes was increased after acyl-ghrelin and FGF2 co-treatment. In conclusion, acyl-ghrelin promoted astrocyte activation in the early stages of ischaemia but suppressed the activation in later stages of ischaemic injury. These later effects were likely to be triggered by the increased expression of endogenous FGF2 after brain ischaemia.
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Affiliation(s)
- Ruirui Dong
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Peking University Health Science Center, Beijing, China
| | - Man Chen
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Peking University Health Science Center, Beijing, China
| | - Jing Liu
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Peking University Health Science Center, Beijing, China
| | - Jihong Kang
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Peking University Health Science Center, Beijing, China
| | - Shigong Zhu
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Peking University Health Science Center, Beijing, China
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Li J, Liu B, Cai M, Lin X, Lou S. Glucose metabolic alterations in hippocampus of diabetes mellitus rats and the regulation of aerobic exercise. Behav Brain Res 2019; 364:447-456. [DOI: 10.1016/j.bbr.2017.11.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2017] [Revised: 11/02/2017] [Accepted: 11/02/2017] [Indexed: 12/17/2022]
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13
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Pregnolato S, Chakkarapani E, Isles AR, Luyt K. Glutamate Transport and Preterm Brain Injury. Front Physiol 2019; 10:417. [PMID: 31068830 PMCID: PMC6491644 DOI: 10.3389/fphys.2019.00417] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2018] [Accepted: 03/27/2019] [Indexed: 12/19/2022] Open
Abstract
Preterm birth complications are the leading cause of child death worldwide and a top global health priority. Among the survivors, the risk of life-long disabilities is high, including cerebral palsy and impairment of movement, cognition, and behavior. Understanding the molecular mechanisms of preterm brain injuries is at the core of future healthcare improvements. Glutamate excitotoxicity is a key mechanism in preterm brain injury, whereby the accumulation of extracellular glutamate damages the delicate immature oligodendrocytes and neurons, leading to the typical patterns of injury seen in the periventricular white matter. Glutamate excitotoxicity is thought to be induced by an interaction between environmental triggers of injury in the perinatal period, particularly cerebral hypoxia-ischemia and infection/inflammation, and developmental and genetic vulnerabilities. To avoid extracellular build-up of glutamate, the brain relies on rapid uptake by sodium-dependent glutamate transporters. Astrocytic excitatory amino acid transporter 2 (EAAT2) is responsible for up to 95% of glutamate clearance, and several lines of evidence suggest that it is essential for brain functioning. While in the adult EAAT2 is predominantly expressed by astrocytes, EAAT2 is transiently upregulated in the immature oligodendrocytes and selected neuronal populations during mid-late gestation, at the peak time for preterm brain injury. This developmental upregulation may interact with perinatal hypoxia-ischemia and infection/inflammation and contribute to the selective vulnerability of the immature oligodendrocytes and neurons in the preterm brain. Disruption of EAAT2 may involve not only altered expression but also impaired function with reversal of transport direction. Importantly, elevated EAAT2 levels have been found in the reactive astrocytes and macrophages of human infant post-mortem brains with severe white matter injury (cystic periventricular leukomalacia), potentially suggesting an adaptive mechanism against excitotoxicity. Interestingly, EAAT2 is suppressed in animal models of acute hypoxic-ischemic brain injury at term, pointing to an important and complex role in newborn brain injuries. Enhancement of EAAT2 expression and transport function is gathering attention as a potential therapeutic approach for a variety of adult disorders and awaits exploration in the context of the preterm brain injuries.
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Affiliation(s)
- Silvia Pregnolato
- Department of Neonatal Neurology, Translational Health Sciences, Bristol Medical School, University of Bristol, Bristol, United Kingdom
| | - Elavazhagan Chakkarapani
- Department of Neonatal Neurology, Translational Health Sciences, Bristol Medical School, University of Bristol, Bristol, United Kingdom
| | - Anthony R Isles
- Behavioural Genetics Group, MRC Centre for Neuropsychiatric Genetics and Genomics, School of Medicine, Cardiff University, Cardiff, United Kingdom
| | - Karen Luyt
- Department of Neonatal Neurology, Translational Health Sciences, Bristol Medical School, University of Bristol, Bristol, United Kingdom
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Abstract
Glucose is the long-established, obligatory fuel for brain that fulfills many critical functions, including ATP production, oxidative stress management, and synthesis of neurotransmitters, neuromodulators, and structural components. Neuronal glucose oxidation exceeds that in astrocytes, but both rates increase in direct proportion to excitatory neurotransmission; signaling and metabolism are closely coupled at the local level. Exact details of neuron-astrocyte glutamate-glutamine cycling remain to be established, and the specific roles of glucose and lactate in the cellular energetics of these processes are debated. Glycolysis is preferentially upregulated during brain activation even though oxygen availability is sufficient (aerobic glycolysis). Three major pathways, glycolysis, pentose phosphate shunt, and glycogen turnover, contribute to utilization of glucose in excess of oxygen, and adrenergic regulation of aerobic glycolysis draws attention to astrocytic metabolism, particularly glycogen turnover, which has a high impact on the oxygen-carbohydrate mismatch. Aerobic glycolysis is proposed to be predominant in young children and specific brain regions, but re-evaluation of data is necessary. Shuttling of glucose- and glycogen-derived lactate from astrocytes to neurons during activation, neurotransmission, and memory consolidation are controversial topics for which alternative mechanisms are proposed. Nutritional therapy and vagus nerve stimulation are translational bridges from metabolism to clinical treatment of diverse brain disorders.
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Affiliation(s)
- Gerald A Dienel
- Department of Neurology, University of Arkansas for Medical Sciences , Little Rock, Arkansas ; and Department of Cell Biology and Physiology, University of New Mexico , Albuquerque, New Mexico
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15
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Shih EK, Robinson MB. Role of Astrocytic Mitochondria in Limiting Ischemic Brain Injury? Physiology (Bethesda) 2019; 33:99-112. [PMID: 29412059 DOI: 10.1152/physiol.00038.2017] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Until recently, astrocyte processes were thought to be too small to contain mitochondria. However, it is now clear that mitochondria are found throughout fine astrocyte processes and are mobile with neuronal activity resulting in positioning near synapses. In this review, we discuss evidence that astrocytic mitochondria confer selective resiliency to astrocytes during ischemic insults and the functional significance of these mitochondria for normal brain function.
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Affiliation(s)
- Evelyn K Shih
- Children's Hospital of Philadelphia Research Institute , Philadelphia, Pennsylvania.,Children's Hospital of Philadelphia, Division of Neurology , Philadelphia, Pennsylvania.,Department of Pediatrics, University of Pennsylvania , Philadelphia, Pennsylvania
| | - Michael B Robinson
- Children's Hospital of Philadelphia Research Institute , Philadelphia, Pennsylvania.,Department of Pediatrics, University of Pennsylvania , Philadelphia, Pennsylvania.,Department of Systems Pharmacology and Translational Therapeutics, University of Pennsylvania , Philadelphia, Pennsylvania
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16
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Miyamoto K, Ishikura KI, Kume K, Ohsawa M. Astrocyte-neuron lactate shuttle sensitizes nociceptive transmission in the spinal cord. Glia 2018; 67:27-36. [DOI: 10.1002/glia.23474] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2017] [Revised: 05/17/2018] [Accepted: 05/25/2018] [Indexed: 12/24/2022]
Affiliation(s)
- Keisuke Miyamoto
- Department of Neuropharmacology; Graduate School of Pharmaceutical Sciences, Nagoya City University; Nagoya Japan
| | - Kei-ichiro Ishikura
- Department of Neuropharmacology; Graduate School of Pharmaceutical Sciences, Nagoya City University; Nagoya Japan
| | - Kazuhiko Kume
- Department of Neuropharmacology; Graduate School of Pharmaceutical Sciences, Nagoya City University; Nagoya Japan
| | - Masahiro Ohsawa
- Department of Neuropharmacology; Graduate School of Pharmaceutical Sciences, Nagoya City University; Nagoya Japan
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17
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Schurr A. Glycolysis Paradigm Shift Dictates a Reevaluation of Glucose and Oxygen Metabolic Rates of Activated Neural Tissue. Front Neurosci 2018; 12:700. [PMID: 30364172 PMCID: PMC6192285 DOI: 10.3389/fnins.2018.00700] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2018] [Accepted: 09/18/2018] [Indexed: 01/31/2023] Open
Abstract
In 1988 two seminal studies were published, both instigating controversy. One concluded that “the energy needs of activated neural tissue are minimal, being fulfilled via the glycolytic pathway alone,” a conclusion based on the observation that neural activation increased glucose consumption, which was not accompanied by a corresponding increase in oxygen consumption (Fox et al., 1988). The second demonstrated that neural tissue function can be supported exclusively by lactate as the energy substrate (Schurr et al., 1988). While both studies continue to have their supporters and detractors, the present review attempts to clarify the issues responsible for the persistence of the controversies they have provoked and offer a possible rationalization. The concept that lactate rather than pyruvate, is the glycolytic end-product, both aerobically and anaerobically, and thus the real mitochondrial oxidative substrate, has gained a greater acceptance over the years. The idea of glycolysis as the sole ATP supplier for neural activation (glucose → lactate + 2ATP) continues to be controversial. Lactate oxidative utilization by activated neural tissue could explain the mismatch between glucose and oxygen consumption and resolve the existing disagreements among users of imaging methods to measure the metabolic rates of the two energy metabolic substrates. The postulate that the energy necessary for active neural tissue is supplied by glycolysis alone stems from the original aerobic glycolysis paradigm. Accordingly, glucose consumption is accompanied by oxygen consumption at 1–6 ratio. Since Fox et al. (1988) observed only a minimal if non-existent oxygen consumption compared to glucose consumption, their conclusion make sense. Nevertheless, considering (a) the shift in the paradigm of glycolysis (glucose → lactate; lactate + O2 + mitochondria → pyruvate → TCA cycle → CO2 + H2O + 17ATP); (b) that one mole of lactate oxidation requires only 50% of the amount of oxygen necessary for the oxidation of one mole of glucose; and (c) that lactate, as a mitochondrial substrate, is over eight times more efficient at ATP production than glucose as a glycolytic substrate, suggest that future studies of cerebral metabolic rates of activated neural tissue should include along with the measurements of CMRO2 and CMRglucose the measurement of CMRlactate.
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Affiliation(s)
- Avital Schurr
- Department of Anesthesiology and Perioperative Medicine, School of Medicine, University of Louisville, Louisville, KY, United States
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18
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Kahl A, Stepanova A, Konrad C, Anderson C, Manfredi G, Zhou P, Iadecola C, Galkin A. Critical Role of Flavin and Glutathione in Complex I-Mediated Bioenergetic Failure in Brain Ischemia/Reperfusion Injury. Stroke 2018; 49:1223-1231. [PMID: 29643256 PMCID: PMC5916474 DOI: 10.1161/strokeaha.117.019687] [Citation(s) in RCA: 51] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2017] [Revised: 02/01/2018] [Accepted: 02/16/2018] [Indexed: 01/08/2023]
Abstract
Supplemental Digital Content is available in the text. Background and Purpose— Ischemic brain injury is characterized by 2 temporally distinct but interrelated phases: ischemia (primary energy failure) and reperfusion (secondary energy failure). Loss of cerebral blood flow leads to decreased oxygen levels and energy crisis in the ischemic area, initiating a sequence of pathophysiological events that after reoxygenation lead to ischemia/reperfusion (I/R) brain damage. Mitochondrial impairment and oxidative stress are known to be early events in I/R injury. However, the biochemical mechanisms of mitochondria damage in I/R are not completely understood. Methods— We used a mouse model of transient focal cerebral ischemia to investigate acute I/R-induced changes of mitochondrial function, focusing on mechanisms of primary and secondary energy failure. Results— Ischemia induced a reversible loss of flavin mononucleotide from mitochondrial complex I leading to a transient decrease in its enzymatic activity, which is rapidly reversed on reoxygenation. Reestablishing blood flow led to a reversible oxidative modification of mitochondrial complex I thiol residues and inhibition of the enzyme. Administration of glutathione-ethyl ester at the onset of reperfusion prevented the decline of complex I activity and was associated with smaller infarct size and improved neurological outcome, suggesting that decreased oxidation of complex I thiols during I/R-induced oxidative stress may contribute to the neuroprotective effect of glutathione ester. Conclusions— Our results unveil a key role of mitochondrial complex I in the development of I/R brain injury and provide the mechanistic basis for the well-established mitochondrial dysfunction caused by I/R. Targeting the functional integrity of complex I in the early phase of reperfusion may provide a novel therapeutic strategy to prevent tissue injury after stroke.
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Affiliation(s)
- Anja Kahl
- From the Feil Family Brain and Mind Research Institute, Weill Cornell Medicine, New York, NY (A.K., A.S., C.K., C.A., G.M., P.Z., C.I., A.G.)
| | - Anna Stepanova
- From the Feil Family Brain and Mind Research Institute, Weill Cornell Medicine, New York, NY (A.K., A.S., C.K., C.A., G.M., P.Z., C.I., A.G.).,School of Biological Sciences, Queen's University Belfast, United Kingdom (A.S., A.G.)
| | - Csaba Konrad
- From the Feil Family Brain and Mind Research Institute, Weill Cornell Medicine, New York, NY (A.K., A.S., C.K., C.A., G.M., P.Z., C.I., A.G.)
| | - Corey Anderson
- From the Feil Family Brain and Mind Research Institute, Weill Cornell Medicine, New York, NY (A.K., A.S., C.K., C.A., G.M., P.Z., C.I., A.G.)
| | - Giovanni Manfredi
- From the Feil Family Brain and Mind Research Institute, Weill Cornell Medicine, New York, NY (A.K., A.S., C.K., C.A., G.M., P.Z., C.I., A.G.)
| | - Ping Zhou
- From the Feil Family Brain and Mind Research Institute, Weill Cornell Medicine, New York, NY (A.K., A.S., C.K., C.A., G.M., P.Z., C.I., A.G.)
| | - Costantino Iadecola
- From the Feil Family Brain and Mind Research Institute, Weill Cornell Medicine, New York, NY (A.K., A.S., C.K., C.A., G.M., P.Z., C.I., A.G.)
| | - Alexander Galkin
- From the Feil Family Brain and Mind Research Institute, Weill Cornell Medicine, New York, NY (A.K., A.S., C.K., C.A., G.M., P.Z., C.I., A.G.).,School of Biological Sciences, Queen's University Belfast, United Kingdom (A.S., A.G.)
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19
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Cell Type-Specific Mechanisms in the Pathogenesis of Ischemic Stroke: The Role of Apoptosis Signal-Regulating Kinase 1. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2018; 2018:2596043. [PMID: 29743976 PMCID: PMC5883936 DOI: 10.1155/2018/2596043] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/14/2017] [Revised: 02/10/2018] [Accepted: 02/22/2018] [Indexed: 12/19/2022]
Abstract
Stroke has become a more common disease worldwide. Despite great efforts to develop treatment, little is known about ischemic stroke. Cerebral ischemia activates multiple cascades of cell type-specific pathomechanisms. Ischemic brain injury consists of a complex series of cellular reactions in various cell types within the central nervous system (CNS) including platelets, endothelial cells, astrocytes, neutrophils, microglia/macrophages, and neurons. Diverse cellular changes after ischemic injury are likely to induce cell death and tissue damage in the brain. Since cells in the brain exhibit different functional roles at distinct time points after injury (acute/subacute/chronic phases), it is difficult to pinpoint genuine roles of cell types after brain injury. Many experimental studies have shown the association of apoptosis signal-regulating kinase 1 (ASK1) with cellular pathomechanisms after cerebral ischemia. Blockade of ASK1, by either pharmacological or genetic manipulation, leads to reduced ischemic brain injury and subsequent neuroprotective effects. In this review, we present the cell type-specific pathophysiology of the early phase of ischemic stroke, the role of ASK1 suggested by preclinical studies, and the potential use of ASK suppression, either by pharmacologic or genetic suppression, as a promising therapeutic option for ischemic stroke recovery.
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20
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Salman MM, Kitchen P, Woodroofe MN, Bill RM, Conner AC, Heath PR, Conner MT. Transcriptome Analysis of Gene Expression Provides New Insights into the Effect of Mild Therapeutic Hypothermia on Primary Human Cortical Astrocytes Cultured under Hypoxia. Front Cell Neurosci 2017; 11:386. [PMID: 29311824 PMCID: PMC5735114 DOI: 10.3389/fncel.2017.00386] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2017] [Accepted: 11/20/2017] [Indexed: 01/02/2023] Open
Abstract
Hypothermia is increasingly used as a therapeutic measure to treat brain injury. However, the cellular mechanisms underpinning its actions are complex and are not yet fully elucidated. Astrocytes are the most abundant cell type in the brain and are likely to play a critical role. In this study, transcriptional changes and the protein expression profile of human primary cortical astrocytes cultured under hypoxic conditions for 6 h were investigated. Cells were treated either with or without a mild hypothermic intervention 2 h post-insult to mimic the treatment of patients following traumatic brain injury (TBI) and/or stroke. Using human gene expression microarrays, 411 differentially expressed genes were identified following hypothermic treatment of astrocytes following a 2 h hypoxic insult. KEGG pathway analysis indicated that these genes were mainly enriched in the Wnt and p53 signaling pathways, which were inhibited following hypothermic intervention. The expression levels of 168 genes involved in Wnt signaling were validated by quantitative real-time-PCR (qPCR). Among these genes, 10 were up-regulated and 32 were down-regulated with the remainder unchanged. Two of the differentially expressed genes (DEGs), p38 and JNK, were selected for validation at the protein level using cell based ELISA. Hypothermic intervention significantly down-regulated total protein levels for the gene products of p38 and JNK. Moreover, hypothermia significantly up-regulated the phosphorylated (activated) forms of JNK protein, while downregulating phosphorylation of p38 protein. Within the p53 signaling pathway, 35 human apoptosis-related proteins closely associated with Wnt signaling were investigated using a Proteome Profiling Array. Hypothermic intervention significantly down-regulated 18 proteins, while upregulating one protein, survivin. Hypothermia is a complex intervention; this study provides the first detailed longitudinal investigation at the transcript and protein expression levels of the molecular effects of therapeutic hypothermic intervention on hypoxic human primary cortical astrocytes. The identified genes and proteins are targets for detailed functional studies, which may help to develop new treatments for brain injury based on an in-depth mechanistic understanding of the astrocytic response to hypoxia and/or hypothermia.
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Affiliation(s)
- Mootaz M Salman
- Biomolecular Sciences Research Centre, Sheffield Hallam University, Sheffield, United Kingdom
| | - Philip Kitchen
- Institute of Clinical Sciences, University of Birmingham, Birmingham, United Kingdom
| | - M Nicola Woodroofe
- Biomolecular Sciences Research Centre, Sheffield Hallam University, Sheffield, United Kingdom
| | - Roslyn M Bill
- School of Life and Health Sciences, Aston University, Birmingham, United Kingdom
| | - Alex C Conner
- Institute of Clinical Sciences, University of Birmingham, Birmingham, United Kingdom
| | - Paul R Heath
- Sheffield Institute for Translational Neuroscience, University of Sheffield, Sheffield, United Kingdom
| | - Matthew T Conner
- Research Institute of Health Sciences, Wolverhampton School of Sciences, University of Wolverhampton, Wolverhampton, United Kingdom
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21
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Zheng Y, Wang XM. Measurement of Lactate Content and Amide Proton Transfer Values in the Basal Ganglia of a Neonatal Piglet Hypoxic-Ischemic Brain Injury Model Using MRI. AJNR Am J Neuroradiol 2017; 38:827-834. [PMID: 28154122 DOI: 10.3174/ajnr.a5066] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2016] [Accepted: 11/06/2016] [Indexed: 11/07/2022]
Abstract
BACKGROUND AND PURPOSE As amide proton transfer imaging is sensitive to protein content and intracellular pH, it has been widely used in the nervous system, including brain tumors and stroke. This work aimed to measure the lactate content and amide proton transfer values in the basal ganglia of a neonatal piglet hypoxic-ischemic brain injury model by using MR spectroscopy and amide proton transfer imaging. MATERIALS AND METHODS From 58 healthy neonatal piglets (3-5 days after birth; weight, 1-1.5 kg) selected initially, 9 piglets remained in the control group and 43 piglets, in the hypoxic-ischemic brain injury group. Single-section amide proton transfer imaging was performed at the coronal level of the basal ganglia. Amide proton transfer values of the bilateral basal ganglia were measured in all piglets. The ROI of MR spectroscopy imaging was the right basal ganglia, and the postprocessing was completed with LCModel software. RESULTS After hypoxic-ischemic insult, the amide proton transfer values immediately decreased, and at 0-2 hours, they remained at their lowest level. Thereafter, they gradually increased and finally exceeded those of the control group at 48-72 hours. After hypoxic-ischemic insult, the lactate content increased immediately, was maximal at 2-6 hours, and then gradually decreased to the level of the control group. The amide proton transfer values were negatively correlated with lactate content (r = -0.79, P < .05). CONCLUSIONS This observation suggests that after hypoxic-ischemic insult, the recovery of pH was faster than that of lactate homeostasis.
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Affiliation(s)
- Y Zheng
- From the Department of Radiology, Shengjing Hospital of China Medical University, Shenyang, PR China
| | - X-M Wang
- From the Department of Radiology, Shengjing Hospital of China Medical University, Shenyang, PR China.
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22
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Okoreeh AK, Bake S, Sohrabji F. Astrocyte-specific insulin-like growth factor-1 gene transfer in aging female rats improves stroke outcomes. Glia 2017; 65:1043-1058. [PMID: 28317235 DOI: 10.1002/glia.23142] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2016] [Revised: 02/26/2017] [Accepted: 02/27/2017] [Indexed: 12/25/2022]
Abstract
Middle aged female rats sustain larger stroke infarction and disability than younger female rats. This older group also shows age-related reduction of insulin like growth factor (IGF)-1 in serum and in astrocytes, a cell type necessary for poststroke recovery. To determine the impact of astrocytic IGF-1 for ischemic stroke, these studies tested the hypothesis that gene transfer of IGF-1 to astrocytes will improve stroke outcomes in middle aged female rats. Middle aged (10-12 month old), acyclic female rats were injected with recombinant adeno-associated virus serotype 5 (AAV5) packaged with the coding sequence of the human (h)IGF-1 gene downstream of an astrocyte-specific promoter glial fibrillary acidic protein (GFAP) (AAV5-GFP-hIGF-1) into the striatum and cortex. The AAV5-control consisted of an identical shuttle vector construct without the hIGF-1 gene (AAV5-GFAP-control). Six to eight weeks later, animals underwent transient (90 min) middle cerebral artery occlusion via intraluminal suture. While infarct volume was not altered, AAV5-GFAP-hIGF-1 treatment significantly improved blood pressure and neurological score in the early acute phase of stroke (2 days) and sensory-motor performance at both the early and late (5 days) acute phase of stroke. AAV5-GFAP-hIGF-1 treatment also reduced circulating serum levels of GFAP, a biomarker for blood brain barrier permeability. Flow cytometry analysis of immune cells in the brain at 24 hr poststroke showed that AAV5-GFAP-hIGF-1 altered the type of immune cells trafficked to the ischemic hemisphere, promoting an anti-inflammatory profile. Collectively, these studies show that targeted enhancement of IGF-1 in astrocytes of middle-aged females improves stroke-induced behavioral impairment and neuroinflammation.
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Affiliation(s)
- Andre K Okoreeh
- Women's Health in Neuroscience Program, Neuroscience and Experimental Therapeutics, Texas A&M College of Medicine, Bryan, Texas, 77807
| | - Shameena Bake
- Women's Health in Neuroscience Program, Neuroscience and Experimental Therapeutics, Texas A&M College of Medicine, Bryan, Texas, 77807
| | - Farida Sohrabji
- Women's Health in Neuroscience Program, Neuroscience and Experimental Therapeutics, Texas A&M College of Medicine, Bryan, Texas, 77807
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23
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Martín-Jiménez CA, Salazar-Barreto D, Barreto GE, González J. Genome-Scale Reconstruction of the Human Astrocyte Metabolic Network. Front Aging Neurosci 2017; 9:23. [PMID: 28243200 PMCID: PMC5303712 DOI: 10.3389/fnagi.2017.00023] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2016] [Accepted: 01/27/2017] [Indexed: 12/22/2022] Open
Abstract
Astrocytes are the most abundant cells of the central nervous system; they have a predominant role in maintaining brain metabolism. In this sense, abnormal metabolic states have been found in different neuropathological diseases. Determination of metabolic states of astrocytes is difficult to model using current experimental approaches given the high number of reactions and metabolites present. Thus, genome-scale metabolic networks derived from transcriptomic data can be used as a framework to elucidate how astrocytes modulate human brain metabolic states during normal conditions and in neurodegenerative diseases. We performed a Genome-Scale Reconstruction of the Human Astrocyte Metabolic Network with the purpose of elucidating a significant portion of the metabolic map of the astrocyte. This is the first global high-quality, manually curated metabolic reconstruction network of a human astrocyte. It includes 5,007 metabolites and 5,659 reactions distributed among 8 cell compartments, (extracellular, cytoplasm, mitochondria, endoplasmic reticle, Golgi apparatus, lysosome, peroxisome and nucleus). Using the reconstructed network, the metabolic capabilities of human astrocytes were calculated and compared both in normal and ischemic conditions. We identified reactions activated in these two states, which can be useful for understanding the astrocytic pathways that are affected during brain disease. Additionally, we also showed that the obtained flux distributions in the model, are in accordance with literature-based findings. Up to date, this is the most complete representation of the human astrocyte in terms of inclusion of genes, proteins, reactions and metabolic pathways, being a useful guide for in-silico analysis of several metabolic behaviors of the astrocyte during normal and pathologic states.
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Affiliation(s)
- Cynthia A Martín-Jiménez
- Departamento de Nutrición y Bioquímica, Facultad de Ciencias, Pontificia Universidad Javeriana Bogotá, Colombia
| | - Diego Salazar-Barreto
- Departamento de Nutrición y Bioquímica, Facultad de Ciencias, Pontificia Universidad Javeriana Bogotá, Colombia
| | - George E Barreto
- Departamento de Nutrición y Bioquímica, Facultad de Ciencias, Pontificia Universidad JaverianaBogotá, Colombia; Instituto de Ciencias Biomédicas, Universidad Autónoma de ChileSantiago, Chile
| | - Janneth González
- Departamento de Nutrición y Bioquímica, Facultad de Ciencias, Pontificia Universidad Javeriana Bogotá, Colombia
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24
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Dienel GA. Lack of appropriate stoichiometry: Strong evidence against an energetically important astrocyte-neuron lactate shuttle in brain. J Neurosci Res 2017; 95:2103-2125. [PMID: 28151548 DOI: 10.1002/jnr.24015] [Citation(s) in RCA: 115] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2016] [Revised: 11/28/2016] [Accepted: 12/16/2016] [Indexed: 12/22/2022]
Abstract
Glutamate-stimulated aerobic glycolysis in astrocytes coupled with lactate shuttling to neurons where it can be oxidized was proposed as a mechanism to couple excitatory neuronal activity with glucose utilization (CMRglc ) during brain activation. From the outset, this model was not viable because it did not fulfill critical stoichiometric requirements: (i) Calculated glycolytic rates and measured lactate release rates were discordant in cultured astrocytes. (ii) Lactate oxidation requires oxygen consumption, but the oxygen-glucose index (OGI, calculated as CMRO2 /CMRglc ) fell during activation in human brain, and the small rise in CMRO2 could not fully support oxidation of lactate produced by disproportionate increases in CMRglc . (iii) Labeled products of glucose metabolism are not retained in activated rat brain, indicating rapid release of a highly labeled, diffusible metabolite identified as lactate, thereby explaining the CMRglc -CMRO2 mismatch. Additional independent lines of evidence against lactate shuttling include the following: astrocytic oxidation of glutamate after its uptake can help "pay" for its uptake without stimulating glycolysis; blockade of glutamate receptors during activation in vivo prevents upregulation of metabolism and lactate release without impairing glutamate uptake; blockade of β-adrenergic receptors prevents the fall in OGI in activated human and rat brain while allowing glutamate uptake; and neurons upregulate glucose utilization in vivo and in vitro under many stimulatory conditions. Studies in immature cultured cells are not appropriate models for lactate shuttling in adult brain because of their incomplete development of metabolic capability and astrocyte-neuron interactions. Astrocyte-neuron lactate shuttling does not make large, metabolically significant contributions to energetics of brain activation. © 2017 Wiley Periodicals, Inc.
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Affiliation(s)
- Gerald A Dienel
- Department of Neurology, University of Arkansas for Medical Sciences, Little Rock, Arkansas, and Department of Cell Biology and Physiology, University of New Mexico, Albuquerque, New Mexico
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25
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Ali EHA, Ahmed-Farid OA, Osman AAE. Bone marrow-derived mesenchymal stem cells ameliorate sodium nitrite-induced hypoxic brain injury in a rat model. Neural Regen Res 2017; 12:1990-1999. [PMID: 29323037 PMCID: PMC5784346 DOI: 10.4103/1673-5374.221155] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Sodium nitrite (NaNO2) is an inorganic salt used broadly in chemical industry. NaNO2 is highly reactive with hemoglobin causing hypoxia. Mesenchymal stem cells (MSCs) are capable of differentiating into a variety of tissue specific cells and MSC therapy is a potential method for improving brain functions. This work aims to investigate the possible therapeutic role of bone marrow-derived MSCs against NaNO2 induced hypoxic brain injury. Rats were divided into control group (treated for 3 or 6 weeks), hypoxic (HP) group (subcutaneous injection of 35 mg/kg NaNO2 for 3 weeks to induce hypoxic brain injury), HP recovery groups N-2wR and N-3wR (treated with the same dose of NaNO2 for 2 and 3 weeks respectively, followed by 4-week or 3-week self-recovery respectively), and MSCs treated groups N-2wSC and N-3wSC (treated with the same dose of NaNO2 for 2 and 3 weeks respectively, followed by one injection of 2 × 106 MSCs via the tail vein in combination with 4 week self-recovery or intravenous injection of NaNO2 for 1 week in combination with 3 week self-recovery). The levels of neurotransmitters (norepinephrine, dopamine, serotonin), energy substances (adenosine monophosphate, adenosine diphosphate, adenosine triphosphate), and oxidative stress markers (malondialdehyde, nitric oxide, 8-hydroxy-2'-deoxyguanosine, glutathione reduced form, and oxidized glutathione) in the frontal cortex and midbrain were measured using high performance liquid chromatography. At the same time, hematoxylin-eosin staining was performed to observe the pathological change of the injured brain tissue. Compared with HP group, pathological change of brain tissue was milder, the levels of malondialdehyde, nitric oxide, oxidized glutathione, 8-hydroxy-2'-deoxyguanosine, norepinephrine, serotonin, glutathione reduced form, and adenosine triphosphate in the frontal cortex and midbrain were significantly decreased, and glutathione reduced form/oxidized glutathione and adenosine monophosphate/adenosine triphosphate ratio were significantly increased in the MSCs treated groups. These findings suggest that bone marrow-derived MSCs exhibit neuroprotective effects against NaNO2-induced hypoxic brain injury through exerting anti-oxidative effects and providing energy to the brain.
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Affiliation(s)
- Elham H A Ali
- Faculty of Women for Art, Sciences and Education, Ain Shams University, Cairo, Egypt
| | - Omar A Ahmed-Farid
- National Organization for Drug Control and Research (NODCAR), Giza, Egypt
| | - Amany A E Osman
- Faculty of Women for Art, Sciences and Education, Ain Shams University, Cairo, Egypt
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Nissen JD, Lykke K, Bryk J, Stridh MH, Zaganas I, Skytt DM, Schousboe A, Bak LK, Enard W, Pääbo S, Waagepetersen HS. Expression of the human isoform of glutamate dehydrogenase, hGDH2, augments TCA cycle capacity and oxidative metabolism of glutamate during glucose deprivation in astrocytes. Glia 2016; 65:474-488. [PMID: 28032919 DOI: 10.1002/glia.23105] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2016] [Revised: 11/23/2016] [Accepted: 11/30/2016] [Indexed: 01/06/2023]
Abstract
A key enzyme in brain glutamate homeostasis is glutamate dehydrogenase (GDH) which links carbohydrate and amino acid metabolism mediating glutamate degradation to CO2 and expanding tricarboxylic acid (TCA) cycle capacity with intermediates, i.e. anaplerosis. Humans express two GDH isoforms, GDH1 and 2, whereas most other mammals express only GDH1. hGDH1 is widely expressed in human brain while hGDH2 is confined to astrocytes. The two isoforms display different enzymatic properties and the nature of these supports that hGDH2 expression in astrocytes potentially increases glutamate oxidation and supports the TCA cycle during energy-demanding processes such as high intensity glutamatergic signaling. However, little is known about how expression of hGDH2 affects the handling of glutamate and TCA cycle metabolism in astrocytes. Therefore, we cultured astrocytes from cerebral cortical tissue of hGDH2-expressing transgenic mice. We measured glutamate uptake and metabolism using [3 H]glutamate, while the effect on metabolic pathways of glutamate and glucose was evaluated by use of 13 C and 14 C substrates and analysis by mass spectrometry and determination of radioactively labeled metabolites including CO2 , respectively. We conclude that hGDH2 expression increases capacity for uptake and oxidative metabolism of glutamate, particularly during increased workload and aglycemia. Additionally, hGDH2 expression increased utilization of branched-chain amino acids (BCAA) during aglycemia and caused a general decrease in oxidative glucose metabolism. We speculate, that expression of hGDH2 allows astrocytes to spare glucose and utilize BCAAs during substrate shortages. These findings support the proposed role of hGDH2 in astrocytes as an important fail-safe during situations of intense glutamatergic activity. GLIA 2017;65:474-488.
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Affiliation(s)
- Jakob D Nissen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Science, University of Copenhagen, Copenhagen, 2100, Denmark
| | - Kasper Lykke
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Science, University of Copenhagen, Copenhagen, 2100, Denmark
| | - Jaroslaw Bryk
- Department of Evolutionary Genetics, Max Planck Institute for Evolutionary Anthropology, Leipzig, 02109, Germany
| | - Malin H Stridh
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Science, University of Copenhagen, Copenhagen, 2100, Denmark
| | - Ioannis Zaganas
- Neurology Laboratory, School of Health Sciences, Faculty of Medicine, University of Crete, Heraklion, Crete, Greece
| | - Dorte M Skytt
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Science, University of Copenhagen, Copenhagen, 2100, Denmark
| | - Arne Schousboe
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Science, University of Copenhagen, Copenhagen, 2100, Denmark
| | - Lasse K Bak
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Science, University of Copenhagen, Copenhagen, 2100, Denmark
| | - Wolfgang Enard
- Department of Evolutionary Genetics, Max Planck Institute for Evolutionary Anthropology, Leipzig, 02109, Germany
| | - Svante Pääbo
- Department of Evolutionary Genetics, Max Planck Institute for Evolutionary Anthropology, Leipzig, 02109, Germany
| | - Helle S Waagepetersen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Science, University of Copenhagen, Copenhagen, 2100, Denmark
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Katnik C, Garcia A, Behensky AA, Yasny IE, Shuster AM, Seredenin SB, Petrov AV, Cuevas J. Activation of σ1 and σ2 receptors by afobazole increases glial cell survival and prevents glial cell activation and nitrosative stress after ischemic stroke. J Neurochem 2016; 139:497-509. [PMID: 27488244 DOI: 10.1111/jnc.13756] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2016] [Revised: 07/22/2016] [Accepted: 07/26/2016] [Indexed: 11/30/2022]
Abstract
Activation of sigma receptors at delayed time points has been shown to decrease injury following ischemic stroke. The mixed σ1/σ2 receptor agonist, 5-ethoxy-2-[2-(morpholino)-ethylthio]benzimidazole (afobazole), provides superior long-term outcomes compared to other σ ligands in the rat middle cerebral artery occlusion (MCAO) stroke model. Experiments using the MCAO model were carried out to determine the molecular mechanism involved in the beneficial effects of afobazole. Administration of afobazole (3 mg/kg) at delayed time points post-stroke significantly increased the number of microglia and astrocytes detected in the ipsilateral hemisphere at 96 h post-surgery. Morphological analysis of the microglia indicated that a greater number of these cells were found in the ramified resting state in MCAO animals treated with afobazole relative to MCAO vehicle controls. Similarly, fewer reactive astrocytes were detected in the injured hemisphere of afobazole-treated animals. Both the enhanced survival and reduced activation of glial cells were abolished by co-application of either a σ1 (BD-1063) or a σ2 (SM-21) receptor antagonist with afobazole. To gain further insight into the mechanisms by which afobazole lessens stroke injury, we probed the brain sections for markers of neuroinflammation (tumor necrosis factor α) and nitrosative stress (S-nitrosocysteine). Data show that afobazole significantly reduces S-nitrosocysteine levels, but does not alter tumor necrosis factor α expression 96 h after an ischemic stroke. Taken together our data indicate that afobazole acting via both σ1 and σ2 receptors decreases stroke injury by enhancing glial cell survival, blocking ischemia-induced glial cell activation, and decreasing nitrosative stress.
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Affiliation(s)
- Christopher Katnik
- Department of Molecular Pharmacology and Physiology, Morsani College of Medicine, University of South Florida, Tampa, Florida, USA
| | - Angela Garcia
- Department of Molecular Pharmacology and Physiology, Morsani College of Medicine, University of South Florida, Tampa, Florida, USA
| | - Adam A Behensky
- Department of Molecular Pharmacology and Physiology, Morsani College of Medicine, University of South Florida, Tampa, Florida, USA
| | | | | | | | | | - Javier Cuevas
- Department of Molecular Pharmacology and Physiology, Morsani College of Medicine, University of South Florida, Tampa, Florida, USA.
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Banerjee A, Ghatak S, Sikdar SK. l-Lactate mediates neuroprotection against ischaemia by increasing TREK1 channel expression in rat hippocampal astrocytes in vitro. J Neurochem 2016; 138:265-81. [PMID: 27062641 DOI: 10.1111/jnc.13638] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2015] [Revised: 04/04/2016] [Accepted: 04/04/2016] [Indexed: 12/20/2022]
Abstract
Brain ischaemia is a highly debilitating condition where shortage of oxygen and glucose leads to profuse cell death. Lactate is a neuroprotective metabolite whose concentrations increase up to 15-30 mmol/L during ischaemia and TREK1 is a neuroprotective potassium channel which is upregulated during ischaemia. The aim of this study was to investigate the effect of l-lactate on TREK1 expression and to evaluate the role of l-lactate-TREK1 interaction in conferring neuroprotection in ischaemia-prone hippocampus. We show that 15-30 mmol/L l-lactate increases functional TREK1 protein expression by 1.5-3-fold in hippocampal astrocytes using immunostaining and electrophysiology. Studies with transcription blocker actinomycin-D and quantitative PCR indicate that the increase in TREK1 expression is due to enhanced TREK1 mRNA transcription. We further report that l-lactate-mediated increase in TREK1 expression is via protein kinase A (PKA)-dependent pathway. This is the first report of an ischaemic metabolite affecting functional expression of an ion channel. Our studies in an in vitro model of ischaemia using oxygen glucose deprivation show that 30 mmol/L l-lactate fails to reduce cell death in rat hippocampal slices treated with TREK1 blockers, PKA inhibitors and gliotoxin. The above effects were specific to l-lactate as pyruvate failed to increase TREK1 expression and reduce cell death. l-Lactate-induced TREK1 upregulation is a novel finding of physiological significance as TREK1 channels contribute to neuroprotection by enhancing potassium buffering and glutamate clearance capacity of astrocytes. We propose that l-lactate promotes neuronal survival in hippocampus by increasing TREK1 channel expression via PKA pathway in astrocytes during ischaemia. Insufficient blood supply to the brain leads to cerebral ischaemia and increase in extracellular lactate concentrations. We incubated hippocampal astrocytes in lactate and observed increase in TREK1 channel expression via protein kinase A (PKA). Inhibition of TREK1, PKA and metabolic impairment of astrocytes prevented lactate from reducing cell death in ischaemic hippocampus. This pathway serves as an alternate mechanism of neuroprotection. Cover image for this issue: doi: 10.1111/jnc.13326.
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Affiliation(s)
- Aditi Banerjee
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore, Karnataka, India
| | - Swagata Ghatak
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore, Karnataka, India
| | - Sujit Kumar Sikdar
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore, Karnataka, India
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Chen W, Wei S, Yu Y, Xue H, Yao F, Zhang M, Xiao J, Hatch GM, Chen L. Pretreatment of rats with increased bioavailable berberine attenuates cerebral ischemia-reperfusion injury via down regulation of adenosine-5'monophosphate kinase activity. Eur J Pharmacol 2016; 779:80-90. [PMID: 26957053 DOI: 10.1016/j.ejphar.2016.03.015] [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: 10/23/2015] [Revised: 02/26/2016] [Accepted: 03/04/2016] [Indexed: 01/09/2023]
Abstract
Berberine (BBR) exhibits multiple beneficial biological effects. However, poor bioavailability of BBR has limited its clinical application. We previously demonstrated that solid dispersion of BBR with sodium caprate (HGSD) remarkably improves its bioavailability. We examined whether this increased bioavailability of BBR could protect the brain from ischemia-reperfusion (IR) induced injury. Rats treated with HGSD, SC and saline for 7 days then subjected to cerebral ischemia reperfusion by middle cerebral artery occlusion for 2h followed 12h reperfusion. Neurological deficit scores, infarct size, SOD, MDA and NO levels were examined. P-AMPK, Bax, cleaved-Caspase-3 in brain was determined. To further probe for the mechanism of beneficial effect of HGSD, PC12 cells were incubated with serum from control or HGSD pretreated animals, incubated with 300μM H2O2 to induce apoptosis. Caspase-3 activity and cell apoptosis was evaluated. HGSD pretreatment significantly attenuated neurological deficit scores, reduced infarct size, increased SOD and decreased MDA and NO after cerebral IR injury compared to controls. Meanwhile, HGSD pretreatment significantly reduced expression of p-AMPK, Bax, cleaved-Caspase-3 after cerebral IR injury. Sodium caprate (100mg/kg/d) pretreatment alone did not exhibit any of these beneficial effects. PC12 cell apoptosis was attenuated when cells were cultured with HGSD serum compared to control. The presence of AMPK activator (AICAR) attenuated whereas AMPK inhibitor (Compound C) augmented the protective effect of HGSD serum on PC12 cell apoptosis.The results indicate that HGSD-pretreatment of rats protects the brain from ischemia-reperfusion injury and the mechanism is due to its anti-apoptotic effect mediated by decreased activation of AMPK.
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Affiliation(s)
- Weijia Chen
- Department of Pharmacology, College of Basic Medical Sciences, School of Nursing, Jilin University, Changchun Jilin, China; Department of Pharmacology, College of Pharmacy, Jilin University, Changchun, Jilin, China
| | - Shengnan Wei
- Department of Pharmacology, College of Basic Medical Sciences, School of Nursing, Jilin University, Changchun Jilin, China
| | - Yang Yu
- Department of Pharmacology, College of Basic Medical Sciences, School of Nursing, Jilin University, Changchun Jilin, China
| | - Huan Xue
- Department of Pharmacology, College of Basic Medical Sciences, School of Nursing, Jilin University, Changchun Jilin, China
| | - Fan Yao
- Department of Pharmacology, College of Basic Medical Sciences, School of Nursing, Jilin University, Changchun Jilin, China
| | - Ming Zhang
- Department of Pharmacology, College of Basic Medical Sciences, School of Nursing, Jilin University, Changchun Jilin, China.
| | - Jun Xiao
- Department of Ophthalmology, the Second Hospital of Jilin University, Changchun, Jilin, China.
| | - Grant M Hatch
- Department of Pharmacology & Therapeutics, University of Manitoba, Manitoba Institute of Child Health, Winnipeg, Manitoba, Canada
| | - Li Chen
- Department of Pharmacology, College of Basic Medical Sciences, School of Nursing, Jilin University, Changchun Jilin, China
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Ghatak S, Banerjee A, Sikdar SK. Ischaemic concentrations of lactate increase TREK1 channel activity by interacting with a single histidine residue in the carboxy terminal domain. J Physiol 2015; 594:59-81. [PMID: 26445100 DOI: 10.1113/jp270706] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2015] [Accepted: 09/21/2015] [Indexed: 02/01/2023] Open
Abstract
KEY POINTS The physiological metabolite, lactate and the two-pore domain leak potassium channel, TREK1 are known neuroprotectants against cerebral ischaemia. However, it is not known whether lactate interacts with TREK1 channel to provide neuroprotection. In this study we show that lactate increases TREK1 channel activity and hyperpolarizes CA1 stratum radiatum astrocytes in hippocampal slices. Lactate increases open probability and decreases longer close time of the human (h)TREK1 channel in a concentration dependent manner. Lactate interacts with histidine 328 (H328) in the carboxy terminal domain of hTREK1 channel to decrease its dwell time in the longer closed state. This interaction was dependent on the charge on H328. Lactate-insensitive mutant H328A hTREK1 showed pH sensitivity similar to wild-type hTREK1, indicating that the effect of lactate on hTREK1 is independent of pH change. A rise in lactate concentration and the leak potassium channel TREK1 have been independently associated with cerebral ischaemia. Recent literature suggests lactate to be neuroprotective and TREK1 knockout mice show an increased sensitivity to brain and spinal cord ischaemia; however, the connecting link between the two is missing. Therefore we hypothesized that lactate might interact with TREK1 channels. In the present study, we show that lactate at ischaemic concentrations (15-30 mm) at pH 7.4 increases TREK1 current in CA1 stratum radiatum astrocytes and causes membrane hyperpolarization. We confirm the intracellular action of lactate on TREK1 in hippocampal slices using monocarboxylate transporter blockers and at single channel level in cell-free inside-out membrane patches. The intracellular effect of lactate on TREK1 is specific since other monocarboxylates such as pyruvate and acetate at pH 7.4 failed to increase TREK1 current. Deletion and point mutation experiments suggest that lactate decreases the longer close dwell time incrementally with increase in lactate concentration by interacting with the histidine residue at position 328 (H328) in the carboxy terminal domain of the TREK1 channel. The interaction of lactate with H328 is dependent on the charge on the histidine residue since isosteric mutation of H328 to glutamine did not show an increase in TREK1 channel activity with lactate. This is the first demonstration of a direct effect of lactate on ion channel activity. The action of lactate on the TREK1 channel signifies a separate neuroprotective mechanism in ischaemia since it was found to be independent of the effect of acidic pH on channel activity.
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Affiliation(s)
- Swagata Ghatak
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore, Karnataka, 560012, India
| | - Aditi Banerjee
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore, Karnataka, 560012, India
| | - Sujit Kumar Sikdar
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore, Karnataka, 560012, India
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31
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Carbone F, Burger F, Roversi G, Tamborino C, Casetta I, Seraceni S, Trentini A, Padroni M, Bertolotto M, Dallegri F, Mach F, Fainardi E, Montecucco F. Leptin/adiponectin ratio predicts poststroke neurological outcome. Eur J Clin Invest 2015; 45:1184-91. [PMID: 26381386 DOI: 10.1111/eci.12538] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/01/2015] [Accepted: 09/13/2015] [Indexed: 12/12/2022]
Abstract
BACKGROUND AND AIMS Different adipokines have been associated with atherosclerotic plaque rupture and cardiovascular events, such as acute ischaemic stroke (AIS). However, the potential role of these molecules in postischaemic brain injury remains largely unknown. METHODS AND METHODS We performed a substudy analysis on nonobese patients with first atherothrombotic stroke (n = 35) from a recently published prospective cohort. Primary endpoint was to investigate the predictive value of serum leptin/adiponectin ratio on neurological recovery at 90 days after AIS. The secondary endpoint was the predictive value of serum adipokine levels of clinical and radiological outcomes at a shorter follow-up (at days 1 and 7 after AIS). The radiological evaluation included ischaemic lesion volume and haemorrhagic transformation (HT). The clinical examination was based on National Institutes of Health Stroke Scale (NIHSS) and modified Rankin Scale (mRS). RESULTS At day 1 after AIS, serum leptin and leptin/adiponectin ratio were increased and inversely correlated with both radiological and clinical parameters at all follow-up time points. Once identified the best cut-off points by receiver operating characteristic (ROC) analysis, risk analysis showed that higher circulating leptin improved neurological recovery at day 90. In addition, leptin/adiponectin ratio maintained statistical significance after adjustment for age, gender and thrombolysis, also predicting the occurrence of HT in the first 7 days after AIS (adjusted OR 0·15 [95% CI 0·03-0·83); P = 0·030]). CONCLUSIONS Higher leptin/adiponectin ratio at day 1 predicted better neurological outcomes in patients with atherothrombotic AIS and might be potentially useful as a prognostic biomarker of the disease.
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Affiliation(s)
- Federico Carbone
- Division of Cardiology, Foundation for Medical Researches, Department of Medical Specialties, Geneva University, Geneva, Switzerland
| | - Fabienne Burger
- Division of Cardiology, Foundation for Medical Researches, Department of Medical Specialties, Geneva University, Geneva, Switzerland
| | - Gloria Roversi
- Department of Biological, Psychiatric and Psychological Science, Azienda Ospedaliera-Universitaria, Arcispedale S. Anna, Ferrara, Italy
| | - Carmine Tamborino
- Department of Biological, Psychiatric and Psychological Science, Azienda Ospedaliera-Universitaria, Arcispedale S. Anna, Ferrara, Italy
| | - Ilaria Casetta
- Department of Biological, Psychiatric and Psychological Science, Azienda Ospedaliera-Universitaria, Arcispedale S. Anna, Ferrara, Italy
| | - Silva Seraceni
- Istitute for Maternal and Child Health "IRCCS Burlo Garofolo", Trieste, Italy
| | - Alessandro Trentini
- Section of Medical Biochemistry, Molecular Biology and Genetics, Department of Biomedical and Specialist Surgical Sciences, University of Ferrara, Ferrara, Italy
| | - Marina Padroni
- Department of Biological, Psychiatric and Psychological Science, Azienda Ospedaliera-Universitaria, Arcispedale S. Anna, Ferrara, Italy
| | - Maria Bertolotto
- First Clinic of Internal Medicine, Department of Internal Medicine, University of Genoa - IRCCS Azienda Ospedaliera Universitaria San Martino -IST Istituto Nazionale per la Ricerca sul Cancro, Genoa, Italy
| | - Franco Dallegri
- First Clinic of Internal Medicine, Department of Internal Medicine, University of Genoa - IRCCS Azienda Ospedaliera Universitaria San Martino -IST Istituto Nazionale per la Ricerca sul Cancro, Genoa, Italy
| | - François Mach
- Division of Cardiology, Foundation for Medical Researches, Department of Medical Specialties, Geneva University, Geneva, Switzerland
| | - Enrico Fainardi
- Neuroradiology Unit, Department of Neurosciences and Rehabilitation, Azienda Ospedaliera-Universitaria, Arcispedale S. Anna, Ferrara, Italy
| | - Fabrizio Montecucco
- Division of Cardiology, Foundation for Medical Researches, Department of Medical Specialties, Geneva University, Geneva, Switzerland.,Neuroradiology Unit, Department of Neurosciences and Rehabilitation, Azienda Ospedaliera-Universitaria, Arcispedale S. Anna, Ferrara, Italy
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32
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Nissen JD, Pajęcka K, Stridh MH, Skytt DM, Waagepetersen HS. Dysfunctional TCA-Cycle Metabolism in Glutamate Dehydrogenase Deficient Astrocytes. Glia 2015. [DOI: 10.1002/glia.22895] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Affiliation(s)
- Jakob D. Nissen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences; University of Copenhagen; Copenhagen Denmark
| | - Kamilla Pajęcka
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences; University of Copenhagen; Copenhagen Denmark
| | - Malin H. Stridh
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences; University of Copenhagen; Copenhagen Denmark
| | - Dorte M. Skytt
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences; University of Copenhagen; Copenhagen Denmark
| | - Helle S. Waagepetersen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences; University of Copenhagen; Copenhagen Denmark
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Nuñez-Figueredo Y, Pardo Andreu GL, Oliveira Loureiro S, Ganzella M, Ramírez-Sánchez J, Ochoa-Rodríguez E, Verdecia-Reyes Y, Delgado-Hernández R, Souza DO. The effects of JM-20 on the glutamatergic system in synaptic vesicles, synaptosomes and neural cells cultured from rat brain. Neurochem Int 2015; 81:41-7. [DOI: 10.1016/j.neuint.2015.01.006] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2014] [Revised: 12/24/2014] [Accepted: 01/15/2015] [Indexed: 01/07/2023]
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Schurr A. Cerebral glycolysis: a century of persistent misunderstanding and misconception. Front Neurosci 2014; 8:360. [PMID: 25477776 PMCID: PMC4237041 DOI: 10.3389/fnins.2014.00360] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2014] [Accepted: 10/21/2014] [Indexed: 11/18/2022] Open
Abstract
Since its discovery in 1780, lactate (lactic acid) has been blamed for almost any illness outcome in which its levels are elevated. Beginning in the mid-1980s, studies on both muscle and brain tissues, have suggested that lactate plays a role in bioenergetics. However, great skepticism and, at times, outright antagonism has been exhibited by many to any perceived role for this monocarboxylate in energy metabolism. The present review attempts to trace the negative attitudes about lactate to the first four or five decades of research on carbohydrate metabolism and its dogma according to which lactate is a useless anaerobic end-product of glycolysis. The main thrust here is the review of dozens of scientific publications, many by the leading scientists of their times, through the first half of the twentieth century. Consequently, it is concluded that there exists a barrier, described by Howard Margolis as “habit of mind,” that many scientists find impossible to cross. The term suggests “entrenched responses that ordinarily occur without conscious attention and that, even if noticed, are hard to change.” Habit of mind has undoubtedly played a major role in the above mentioned negative attitudes toward lactate. As early as the 1920s, scientists investigating brain carbohydrate metabolism had discovered that lactate can be oxidized by brain tissue preparations, yet their own habit of mind redirected them to believe that such an oxidation is simply a disposal mechanism of this “poisonous” compound. The last section of the review invites the reader to consider a postulated alternative glycolytic pathway in cerebral and, possibly, in most other tissues, where no distinction is being made between aerobic and anaerobic glycolysis; lactate is always the glycolytic end product. Aerobically, lactate is readily shuttled and transported into the mitochondrion, where it is converted to pyruvate via a mitochondrial lactate dehydrogenase (mLDH) and then is entered the tricarboxylic acid (TCA) cycle.
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Affiliation(s)
- Avital Schurr
- Department of Anesthesiology and Perioperative Medicine, University of Louisville School of Medicine Louisville, KY, USA
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Lactate shuttling and lactate use as fuel after traumatic brain injury: metabolic considerations. J Cereb Blood Flow Metab 2014; 34:1736-48. [PMID: 25204393 PMCID: PMC4269761 DOI: 10.1038/jcbfm.2014.153] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/17/2014] [Accepted: 07/31/2014] [Indexed: 11/08/2022]
Abstract
Lactate is proposed to be generated by astrocytes during glutamatergic neurotransmission and shuttled to neurons as 'preferred' oxidative fuel. However, a large body of evidence demonstrates that metabolic changes during activation of living brain disprove essential components of the astrocyte-neuron lactate shuttle model. For example, some glutamate is oxidized to generate ATP after its uptake into astrocytes and neuronal glucose phosphorylation rises during activation and provides pyruvate for oxidation. Extension of the notion that lactate is a preferential fuel into the traumatic brain injury (TBI) field has important clinical implications, and the concept must, therefore, be carefully evaluated before implementation into patient care. Microdialysis studies in TBI patients demonstrate that lactate and pyruvate levels and lactate/pyruvate ratios, along with other data, have important diagnostic value to distinguish between ischemia and mitochondrial dysfunction. Results show that lactate release from human brain to blood predominates over its uptake after TBI, and strong evidence for lactate metabolism is lacking; mitochondrial dysfunction may inhibit lactate oxidation. Claims that exogenous lactate infusion is energetically beneficial for TBI patients are not based on metabolic assays and data are incorrectly interpreted.
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Sayre NL, Chen Y, Sifuentes M, Stoveken B, Lechleiter JD. Purinergic receptor stimulation decreases ischemic brain damage by energizing astrocyte mitochondria. ADVANCES IN NEUROBIOLOGY 2014; 11:121-50. [PMID: 25236727 DOI: 10.1007/978-3-319-08894-5_7] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
As a leading cause of death in the world, cerebral ischemic stroke has limited treatment options. The lack of glucose and oxygen after stroke is particularly harmful in the brain because neuronal metabolism accounts for significantly more energy consumption per gram of body weight compared to other organs. Our laboratory has identified mitochondrial metabolism of astrocytes to be a key target for pharmacologic intervention, not only because astrocytes play a central role in regulating brain metabolism, but also because they are essential for neuronal health and support. Here we review current literature pertaining to the pathobiology of stroke, along with the role of astrocytes and metabolism in stroke. We also discuss our research, which has revealed that pharmacologic stimulation of metabotropic P2Y1 receptor signaling in astrocytes can increase mitochondrial energy production and also reduce damage after stroke.
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Affiliation(s)
- Naomi L Sayre
- Department of Cellular and Structural Biology, University of Texas Health Science Center San Antonio, 7703 Floyd Curl Drive, San Antonio, TX, 78229, USA
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Xiao Y, Wu X, Deng X, Huang L, Zhou Y, Yang X. Optimal electroacupuncture frequency for maintaining astrocyte structural integrity in cerebral ischemia. Neural Regen Res 2014; 8:1122-31. [PMID: 25206406 PMCID: PMC4145895 DOI: 10.3969/j.issn.1673-5374.2013.12.007] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2012] [Accepted: 03/19/2013] [Indexed: 11/18/2022] Open
Abstract
The astrocyte is a critical regulator of neuronal survival after ischemic brain injury. Electroacupuncture may be an effective therapy for cerebral ischemia, as electroacupuncture frequency can affect the structural integrity of astrocytes. In this study, a rat model of middle cerebral artery occlusion established using the modified thread embolism method was treated with electroacupuncture of the bilateral Quchi (LI11) and Zusanli (ST36) at 15, 30, and 100 Hz frequencies. Behavioral testing, immunohistochemistry and electron microscopy were used to explore the effect of these electroacupuncture frequencies used on maintaining the structural integrity of ischemic brain tissue. Compared with the model and 100 Hz electroacupuncture groups, the 15 and 30 Hz electroacupuncture groups displayed decreased neurological deficit scores, as evaluated by the "Longa" method, significantly increased glial fibrillary acidic protein expression, and alleviated ultrastructural damage of astrocytes at the edge of the infarct. Our experimental findings indicate that 15 and 30 Hz electroacupuncture intervention can favorably maintain the structural integrity of astrocytes and play a protective role in cerebral ischemic injury. Astrocyte structural integrity may be the mechanism underlying acupuncture production of ischemic tolerance.
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Affiliation(s)
- Yicai Xiao
- Department of Traditional Chinese Medicine, First Affiliated Hospital of Guangxi Medical University, Nanning 530021, Guangxi Zhuang Autonomous Region, China
| | - Xingui Wu
- Department of Traditional Chinese Medicine, First Affiliated Hospital of Guangxi Medical University, Nanning 530021, Guangxi Zhuang Autonomous Region, China
| | - Xiangfa Deng
- Department of Anatomy, Faculty of Preclinical Medicine, Guangxi Medical University, Nanning 530021, Guangxi Zhuang Autonomous Region, China
| | - Liping Huang
- Department of Traditional Chinese Medicine, First Affiliated Hospital of Guangxi Medical University, Nanning 530021, Guangxi Zhuang Autonomous Region, China
| | - Yuancheng Zhou
- Department of Traditional Chinese Medicine, First Affiliated Hospital of Guangxi Medical University, Nanning 530021, Guangxi Zhuang Autonomous Region, China
| | - Xuejie Yang
- Department of Traditional Chinese Medicine, First Affiliated Hospital of Guangxi Medical University, Nanning 530021, Guangxi Zhuang Autonomous Region, China
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Shen Y, Tian Y, Yang J, Shi X, Ouyang L, Gao J, Lu J. Dual effects of carnosine on energy metabolism of cultured cortical astrocytes under normal and ischemic conditions. ACTA ACUST UNITED AC 2014; 192-193:45-52. [PMID: 25195162 DOI: 10.1016/j.regpep.2014.08.005] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2014] [Revised: 07/09/2014] [Accepted: 08/11/2014] [Indexed: 12/18/2022]
Abstract
OBJECTIVE The aim of this study was to investigate the effects of carnosine on the bioenergetic profile of cultured cortical astrocytes under normal and ischemic conditions. METHODS The Seahorse Bioscience XF96 Extracellular Flux Analyzer was used to measure the oxygen consumption rates (OCRs) and extracellular acidification rates (ECARs) of cultured cortical astrocytes treated with and without carnosine under normal and ischemic conditions. RESULTS Under the normal growth condition, the basal OCRs and ECARs of astrocytes were 21.72±1.59 pmol/min/μg protein and 3.95±0.28 mpH/min/μg protein respectively. Mitochondrial respiration accounted for ~80% of the total cellular respiration and 85% of this coupled to ATP synthesis. Carnosine significantly reduced basal OCRs and ECARs and ATP-linked respiration, but it strikingly increased the spare respiratory capacity of astrocytes. The cellular ATP level in carnosine-treated astrocytes was reduced to ~42% of the control. However, under the ischemic condition, carnosine upregulated the mitochondrial respiratory and cellular ATP content of astrocytes exposed to 8h of oxygen-glucose deprivation (OGD) followed by 24 h of recovery under the normal growth condition. CONCLUSIONS Carnosine may be an endogenous regulator of astrocyte energy metabolism and a clinically safe therapeutic agent for promoting brain energy metabolism recovery after ischemia/reperfusion injury.
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Affiliation(s)
- Yao Shen
- Key Laboratory of Laboratory Medicine, Ministry of Education, Zhejiang Provincial Key Laboratory of Medical Genetics, College of Laboratory Medicine and Life Sciences, Wenzhou Medical University, Wenzhou 325035, China.
| | - Yueyang Tian
- Key Laboratory of Laboratory Medicine, Ministry of Education, Zhejiang Provincial Key Laboratory of Medical Genetics, College of Laboratory Medicine and Life Sciences, Wenzhou Medical University, Wenzhou 325035, China
| | - Jianbo Yang
- Key Laboratory of Laboratory Medicine, Ministry of Education, Zhejiang Provincial Key Laboratory of Medical Genetics, College of Laboratory Medicine and Life Sciences, Wenzhou Medical University, Wenzhou 325035, China
| | - Xiaojie Shi
- Key Laboratory of Laboratory Medicine, Ministry of Education, Zhejiang Provincial Key Laboratory of Medical Genetics, College of Laboratory Medicine and Life Sciences, Wenzhou Medical University, Wenzhou 325035, China
| | - Li Ouyang
- Key Laboratory of Laboratory Medicine, Ministry of Education, Zhejiang Provincial Key Laboratory of Medical Genetics, College of Laboratory Medicine and Life Sciences, Wenzhou Medical University, Wenzhou 325035, China
| | - Jieqiong Gao
- Key Laboratory of Laboratory Medicine, Ministry of Education, Zhejiang Provincial Key Laboratory of Medical Genetics, College of Laboratory Medicine and Life Sciences, Wenzhou Medical University, Wenzhou 325035, China
| | - Jianxin Lu
- Key Laboratory of Laboratory Medicine, Ministry of Education, Zhejiang Provincial Key Laboratory of Medical Genetics, College of Laboratory Medicine and Life Sciences, Wenzhou Medical University, Wenzhou 325035, China.
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Van Elzen R, Moens L, Dewilde S. Expression profiling of the cerebral ischemic and hypoxic response. Expert Rev Proteomics 2014; 5:263-82. [DOI: 10.1586/14789450.5.2.263] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Rodrigues TB, Valette J, Bouzier-Sore AK. (13)C NMR spectroscopy applications to brain energy metabolism. FRONTIERS IN NEUROENERGETICS 2013; 5:9. [PMID: 24367329 PMCID: PMC3856424 DOI: 10.3389/fnene.2013.00009] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/31/2013] [Accepted: 11/15/2013] [Indexed: 12/31/2022]
Abstract
(13)C nuclear magnetic resonance (NMR) spectroscopy is the method of choice for studying brain metabolism. Indeed, the most convincing data obtained to decipher metabolic exchanges between neurons and astrocytes have been obtained using this technique, thus illustrating its power. It may be difficult for non-specialists, however, to grasp thefull implication of data presented in articles written by spectroscopists. The aim of the review is, therefore, to provide a fundamental understanding of this topic to facilitate the non-specialists in their reading of this literature. In the first part of this review, we present the metabolic fate of (13)C-labeled substrates in the brain in a detailed way, including an overview of some general neurochemical principles. We also address and compare the various spectroscopic strategies that can be used to study brain metabolism. Then, we provide an overview of the (13)C NMR experiments performed to analyze both intracellular and intercellular metabolic fluxes. More particularly, the role of lactate as a potential energy substrate for neurons is discussed in the light of (13)C NMR data. Finally, new perspectives and applications offered by (13)C hyperpolarization are described.
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Affiliation(s)
- Tiago B. Rodrigues
- Cancer Research UK Cambridge Institute and Department of Biochemistry, University of CambridgeCambridge, UK
| | - Julien Valette
- Commissariat à l’Energie Atomique, Institut d’Imagerie Biomédicale, Molecular Imaging Research CenterFontenay-Aux-Roses, France
| | - Anne-Karine Bouzier-Sore
- Centre de Résonance Magnétique des Systèmes Biologiques, UMR 5536, Université Bordeaux Segalen - Centre National de la Recherche ScientifiqueBordeaux, France
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Lapp DW, Zhang SS, Barnstable CJ. Stat3 mediates LIF-induced protection of astrocytes against toxic ROS by upregulating the UPC2 mRNA pool. Glia 2013; 62:159-70. [DOI: 10.1002/glia.22594] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2013] [Revised: 10/12/2013] [Accepted: 10/16/2013] [Indexed: 11/08/2022]
Affiliation(s)
- Daniel W. Lapp
- Department of Neural and Behavioral Sciences; Penn State College of Medicine; Hershey Pennsylvania
| | - Samuel S. Zhang
- Department of Neural and Behavioral Sciences; Penn State College of Medicine; Hershey Pennsylvania
- Penn State Hershey Eye Center; Penn State College of Medicine; Hershey Pennsylvania
| | - Colin J. Barnstable
- Department of Neural and Behavioral Sciences; Penn State College of Medicine; Hershey Pennsylvania
- Penn State Hershey Eye Center; Penn State College of Medicine; Hershey Pennsylvania
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Stančić A, Otašević V, Janković A, Vučetić M, Ivanović-Burmazović I, Filipović MR, Korać A, Markelić M, Veličković K, Golić I, Buzadžić B, Korać B. Molecular basis of hippocampal energy metabolism in diabetic rats: the effects of SOD mimic. Brain Res Bull 2013; 99:27-33. [PMID: 24084255 DOI: 10.1016/j.brainresbull.2013.09.009] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2013] [Accepted: 09/23/2013] [Indexed: 01/22/2023]
Abstract
Hippocampal structural changes associated with diabetes-related cognitive impairments are well described, but their molecular background remained vague. We examined whether/how diabetes alters molecular basis of energy metabolism in hippocampus readily after diabetes onset, with special emphasis on its redox-sensitivity. To induce diabetes, adult Mill Hill hybrid hooded rats received a single alloxan dose (120 mg/kg). Both non-diabetic and diabetic groups were further divided in two subgroups receiving (i) or not (ii) superoxide dismutase (SOD) mimic, [Mn(II)(pyane)Cl2] for 7 days, i.p. Treatment of the diabetic animals started after blood glucose level ≥12 mM. Diabetes decreased protein levels of oxidative phosphorylation components: complex III and ATP synthase. In contrast, protein amounts of glyceraldehyde-3-phosphate dehydrogenase, pyruvate dehydrogenase, and hypoxia-inducible factor-1α - the key regulator of energy metabolism in stress conditions, were higher in diabetic animals. Treatment with SOD mimic restored/increased the levels of oxidative phosphorylation components and returned hypoxia-inducible factor-1α to control level, while diabetes-induced up-regulation of glycolytic enzyme, glyceraldehyde-3-phosphate dehydrogenase, was additionally stimulated. To conclude, our results provide insight into the earliest molecular changes of energy-producing pathways in diabetes that may account for structural/functional disturbance of hippocampus, seen during disease progression. Also, data suggest [Mn(II)(pyane)Cl2] as potential therapeutic agent in cutting-edge approaches to threat this widespread metabolic disorder.
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Affiliation(s)
- Ana Stančić
- University of Belgrade, Institute for Biological Research "Siniša Stanković", Department of Physiology, Belgrade, Serbia
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Lizarbe B, Benitez A, Peláez Brioso GA, Sánchez-Montañés M, López-Larrubia P, Ballesteros P, Cerdán S. Hypothalamic metabolic compartmentation during appetite regulation as revealed by magnetic resonance imaging and spectroscopy methods. FRONTIERS IN NEUROENERGETICS 2013; 5:6. [PMID: 23781199 PMCID: PMC3680712 DOI: 10.3389/fnene.2013.00006] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/12/2013] [Accepted: 05/28/2013] [Indexed: 12/14/2022]
Abstract
We review the role of neuroglial compartmentation and transcellular neurotransmitter cycling during hypothalamic appetite regulation as detected by Magnetic Resonance Imaging (MRI) and Spectroscopy (MRS) methods. We address first the neurochemical basis of neuroendocrine regulation in the hypothalamus and the orexigenic and anorexigenic feed-back loops that control appetite. Then we examine the main MRI and MRS strategies that have been used to investigate appetite regulation. Manganese-enhanced magnetic resonance imaging (MEMRI), Blood oxygenation level-dependent contrast (BOLD), and Diffusion-weighted magnetic resonance imaging (DWI) have revealed Mn2+ accumulations, augmented oxygen consumptions, and astrocytic swelling in the hypothalamus under fasting conditions, respectively. High field 1H magnetic resonance in vivo, showed increased hypothalamic myo-inositol concentrations as compared to other cerebral structures. 1H and 13C high resolution magic angle spinning (HRMAS) revealed increased neuroglial oxidative and glycolytic metabolism, as well as increased hypothalamic glutamatergic and GABAergic neurotransmissions under orexigenic stimulation. We propose here an integrative interpretation of all these findings suggesting that the neuroendocrine regulation of appetite is supported by important ionic and metabolic transcellular fluxes which begin at the tripartite orexigenic clefts and become extended spatially in the hypothalamus through astrocytic networks becoming eventually MRI and MRS detectable.
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Affiliation(s)
- Blanca Lizarbe
- Department of Experimental Models of Human diseases, Laboratory of Imaging and Spectroscopy by Magnetic Resonance, Instituto de Investigaciones Biomédicas "Alberto Sols" CSIC/UAM Madrid, Spain
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Sword J, Masuda T, Croom D, Kirov SA. Evolution of neuronal and astroglial disruption in the peri-contusional cortex of mice revealed by in vivo two-photon imaging. Brain 2013; 136:1446-61. [PMID: 23466395 PMCID: PMC3634194 DOI: 10.1093/brain/awt026] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2012] [Revised: 12/08/2012] [Accepted: 12/27/2012] [Indexed: 12/14/2022] Open
Abstract
In traumatic brain injury mechanical forces applied to the cranium and brain cause irreversible primary neuronal and astroglial damage associated with terminal dendritic beading and spine loss representing acute damage to synaptic circuitry. Oedema develops quickly after trauma, raising intracranial pressure that results in a decrease of blood flow and consequently in cerebral ischaemia, which can cause secondary injury in the peri-contusional cortex. Spreading depolarizations have also been shown to occur after traumatic brain injury in humans and in animal models and are thought to accelerate and exacerbate secondary tissue injury in at-risk cortical territory. Yet, the mechanisms of acute secondary injury to fine synaptic circuitry within the peri-contusional cortex after mild traumatic brain injury remain unknown. A mild focal cortical contusion model in adult mouse sensory-motor cortex was implemented by the controlled cortical impact injury device. In vivo two-photon microscopy in the peri-contusional cortex was used to monitor via optical window yellow fluorescent protein expressing neurons, enhanced green fluorescent protein expressing astrocytes and capillary blood flow. Dendritic beading in the peri-contusional cortex developed slowly and the loss of capillary blood flow preceded terminal dendritic injury. Astrocytes were swollen indicating oedema and remained swollen during the next 24 h throughout the imaging session. There were no recurrent spontaneous spreading depolarizations in this mild traumatic brain injury model; however, when spreading depolarizations were repeatedly induced outside the peri-contusional cortex by pressure-injecting KCl, dendrites undergo rapid beading and recovery coinciding with passage of spreading depolarizations, as was confirmed with electrophysiological recordings in the vicinity of imaged dendrites. Yet, accumulating metabolic stress resulting from as few as four rounds of spreading depolarization significantly added to the fraction of beaded dendrites that were incapable to recover during repolarization, thus facilitating terminal injury. In contrast, similarly induced four rounds of spreading depolarization in another set of control healthy mice caused no accumulating dendritic injury as dendrites fully recovered from beading during repolarization. Taken together, our data suggest that in the mild traumatic brain injury the acute dendritic injury in the peri-contusional cortex is gated by the decline in the local blood flow, most probably as a result of developing oedema. Furthermore, spreading depolarization is a specific mechanism that could accelerate injury to synaptic circuitry in the metabolically compromised peri-contusional cortex, worsening secondary damage following traumatic brain injury.
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Affiliation(s)
- Jeremy Sword
- 1 Graduate Program in Neuroscience, Georgia Health Sciences University, Augusta, Georgia 30912, USA
| | - Tadashi Masuda
- 2 Brain and Behaviour Discovery Institute, Georgia Health Sciences University, Augusta, Georgia 30912, USA
| | - Deborah Croom
- 3 Department of Neurosurgery, Georgia Health Sciences University, Augusta, Georgia 30912, USA
| | - Sergei A. Kirov
- 2 Brain and Behaviour Discovery Institute, Georgia Health Sciences University, Augusta, Georgia 30912, USA
- 3 Department of Neurosurgery, Georgia Health Sciences University, Augusta, Georgia 30912, USA
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Stroke neuroprotection: targeting mitochondria. Brain Sci 2013; 3:540-60. [PMID: 24961414 PMCID: PMC4061853 DOI: 10.3390/brainsci3020540] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2013] [Revised: 04/08/2013] [Accepted: 04/09/2013] [Indexed: 11/17/2022] Open
Abstract
Stroke is the fourth leading cause of death and the leading cause of long-term disability in the United States. Blood flow deficit results in an expanding infarct core with a time-sensitive peri-infarct penumbra that is considered salvageable and is the primary target for treatment strategies. The only current FDA-approved drug for treating ischemic stroke is recombinant tissue plasminogen activator (rt-PA). However, this treatment is limited to within 4.5 h of stroke onset in a small subset of patients. The goal of this review is to focus on mitochondrial-dependent therapeutic agents that could provide neuroprotection following stroke. Dysfunctional mitochondria are linked to neurodegeneration in many disease processes including stroke. The mechanisms reviewed include: (1) increasing ATP production by purinergic receptor stimulation, (2) decreasing the production of ROS by superoxide dismutase, or (3) increasing antioxidant defenses by methylene blue, and their benefits in providing neuroprotection following a stroke.
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Leptin attenuates cerebral ischemia injury through the promotion of energy metabolism via the PI3K/Akt pathway. J Cereb Blood Flow Metab 2013; 33:567-74. [PMID: 23299243 PMCID: PMC3618393 DOI: 10.1038/jcbfm.2012.202] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
The purpose of this study was to investigate the protective mechanism of leptin-mediated metabolic recovery against cerebral injury after ischemia and reperfusion. We determined the neurologic deficit score, extent of brain edema, and infarct volume after reperfusion. The histopathologic alterations and changes in glucose uptake in the brain were also observed. Moreover, the levels of lactate dehydrogenase (LDH), lactic acid, pyruvate, and ATP in brain tissue were detected. Leptin levels in serum were also detected. To further define leptin-induced neuroprotective signaling pathways, we examined the levels of phosphorylated Akt (p-Akt) in the brain and in cultured cells. After transient ischemia, leptin treatment markedly reduced the neurologic deficits, cerebral infarct volume, and brain edema. After leptin injection, ATP, leptin, and p-Akt levels were significantly increased, LDH levels and lactic acid/pyruvate ratio were noticeably reduced, and histopathologic injuries were alleviated, which were all reversed by the PI(3)K inhibitor LY294002. These data show that leptin ameliorates cerebral ischemia/reperfusion injury by enhancing p-Akt, which in turn improves the supply of energy. The PI(3)K/Akt pathway was found to be the critical pathway for the mediation of leptin-induced neuroprotection, a finding that may prove to be useful in the treatment of ischemic stroke.
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Barcelos GK, Tholance Y, Grousson S, Renaud B, Perret-Liaudet A, Dailler F, Zimmer L. Outcome of Poor-Grade Subarachnoid Hemorrhage as Determined by Biomarkers of Glucose Cerebral Metabolism. Neurocrit Care 2013; 18:234-44. [DOI: 10.1007/s12028-012-9810-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Wu X, Tang R, Liu Y, Song J, Yu Z, Wang W, Xie M. Small RNA interference-mediated gene silencing of TREK-1 potassium channel in cultured astrocytes. ACTA ACUST UNITED AC 2012; 32:849-855. [PMID: 23271285 DOI: 10.1007/s11596-012-1046-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2012] [Indexed: 11/27/2022]
Abstract
This study was aimed to examine the effect of TREK-1 silencing on the function of astrocytes. Three 21-nucleotide small interfering RNA (siRNA) duplexes (siT1, siT2, siT3) targeting TREK-1 were constructed. Cy3-labeled dsRNA oligmers were used to determine the transfection efficiency in cultured astrocytes. TREK-1-specific siRNA duplexes (siT1, siT2, siT3) at the optimal concentration were transfected into cultured astrocytes, and the most efficient siRNA was identified by the method of immunocytochemical staining and Western blotting. The proliferation of astrocytes tranfected with TREK-1-targeting siRNA under hypoxia condition was measured by fluorescence-activated cell sorting (FACS). The results showed that TREK-1 was expressed in cultured astrocytes. The dsRNA oligmers targeting TREK-1 could be transfected efficiently in cultured astrocytes and down-regulate the expression of TREK-1 in astrocytes. Moreover, the down-regulation of TREK-1 in astrocytes contributed to the proliferation of astrocytes under hypoxia condition as determined by cell cycle analysis. It was concluded that siRNA is a powerful technique that can be used to knockdown the expression of TREK-1 in astrocytes, which helps further investigate the function of TREK-1 channel in astrocytes under physicological and pathological condition.
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Affiliation(s)
- Xiao Wu
- Department of Neurology, Huazhong University of Science and Technology, Wuhan, 430030, China
| | - Ronghua Tang
- Department of Neurology, Huazhong University of Science and Technology, Wuhan, 430030, China
| | - Yang Liu
- Department of Neurology, Huazhong University of Science and Technology, Wuhan, 430030, China
| | - Jingjiao Song
- Division of Clinical Immunology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China
| | - Zhiyuan Yu
- Department of Neurology, Huazhong University of Science and Technology, Wuhan, 430030, China
| | - Wei Wang
- Department of Neurology, Huazhong University of Science and Technology, Wuhan, 430030, China
| | - Minjie Xie
- Department of Neurology, Huazhong University of Science and Technology, Wuhan, 430030, China.
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Risher WC, Croom D, Kirov SA. Persistent astroglial swelling accompanies rapid reversible dendritic injury during stroke-induced spreading depolarizations. Glia 2012; 60:1709-20. [PMID: 22821441 PMCID: PMC3435464 DOI: 10.1002/glia.22390] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2011] [Accepted: 06/20/2012] [Indexed: 11/10/2022]
Abstract
Spreading depolarizations are a key event in the pathophysiology of stroke, resulting in rapid dendritic beading, which represents acute damage to synaptic circuitry. The impact of spreading depolarizations on the real-time injury of astrocytes during ischemia is less clear. We used simultaneous in vivo 2-photon imaging and electrophysiological recordings in adult mouse somatosensory cortex to examine spreading depolarization-induced astroglial structural changes concurrently with signs of neuronal injury in the early periods of focal and global ischemia. Astrocytes in the metabolically compromised ischemic penumbra-like area showed a long lasting swelling response to spontaneous spreading depolarizations despite rapid dendritic recovery in a photothrombotic occlusion model of focal stroke. Astroglial swelling was often facilitated by recurrent depolarizations and the magnitude of swelling strongly correlated with the total duration of depolarization. In contrast, spreading depolarization-induced astroglial swelling was transient in normoxic healthy tissue. In a model of transient global ischemia, the occurrence of a single spreading depolarization elicited by a bilateral common carotid artery occlusion coincided with astroglial swelling alongside dendritic beading. With immediate reperfusion, dendritic beading subsides. Astroglial swelling was either transient during short ischemic periods distinguished by a short-lasting spreading depolarization, or persistent during severe ischemia characterized by a long-lasting depolarization with the ultraslow negative voltage component. We propose that persistent astroglial swelling is initiated and exacerbated during spreading depolarization in brain tissue with moderate to severe energy deficits, disrupting astroglial maintenance of normal homeostatic function thus contributing to the negative outcome of ischemic stroke as astrocytes fail to provide neuronal support.
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Affiliation(s)
- W. Christopher Risher
- Graduate Program in Neuroscience, Georgia Health Sciences University, Augusta, Georgia 30912
- Brain and Behavior Discovery Institute, Georgia Health Sciences University, Augusta, Georgia 30912
| | - Deborah Croom
- Department of Neurosurgery, Georgia Health Sciences University, Augusta, Georgia 30912
- Brain and Behavior Discovery Institute, Georgia Health Sciences University, Augusta, Georgia 30912
| | - Sergei A. Kirov
- Department of Neurosurgery, Georgia Health Sciences University, Augusta, Georgia 30912
- Brain and Behavior Discovery Institute, Georgia Health Sciences University, Augusta, Georgia 30912
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Barreto GE, White RE, Xu L, Palm CJ, Giffard RG. Effects of heat shock protein 72 (Hsp72) on evolution of astrocyte activation following stroke in the mouse. Exp Neurol 2012; 238:284-96. [PMID: 22940431 DOI: 10.1016/j.expneurol.2012.08.015] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2012] [Revised: 08/01/2012] [Accepted: 08/11/2012] [Indexed: 01/08/2023]
Abstract
Astrocyte activation is a hallmark of the response to brain ischemia consisting of changes in gene expression and morphology. Heat shock protein 72 (Hsp72) protects from cerebral ischemia, and although several protective mechanisms have been investigated, effects on astrocyte activation have not been studied. To identify potential mechanisms of protection, microarray analysis was used to assess gene expression in the ischemic hemispheres of wild-type (WT) and Hsp72-overexpressing (Hsp72Tg) mice 24 h after middle cerebral artery occlusion or sham surgery. After stroke both genotypes exhibited changes in genes related to apoptosis, inflammation, and stress, with more downregulated genes in Hsp72Tg and more inflammation-related genes increased in WT mice. Genes indicative of astrocyte activation were also upregulated in both genotypes. To measure the extent and time course of astrocyte activation after stroke, detailed histological and morphological analyses were performed in the cortical penumbra. We observed a marked and persistent increase in glial fibrillary acidic protein (GFAP) and a transient increase in vimentin. No change in overall astrocyte number was observed based on glutamine synthetase immunoreactivity. Hsp72Tg and WT mice were compared for density of astrocytes expressing activation markers and astrocytic morphology. In animals with comparable infarct size, overexpression of Hsp72 reduced the density of GFAP- and vimentin-expressing cells, and decreased astrocyte morphological complexity 72 h following stroke. However, by 30 days astrocyte activation was similar between genotypes. These data indicate that early modulation of astrocyte activation provides an additional novel mechanism associated with Hsp72 overexpression in the setting of ischemia.
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Affiliation(s)
- George E Barreto
- Department of Anesthesia, Stanford University School of Medicine, 300 Pasteur Drive, Stanford, CA 94305, USA
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