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Exercise alters LPS-induced glial activation in the mouse brain. Neuronal Signal 2020; 4:NS20200003. [PMID: 33304620 PMCID: PMC7711064 DOI: 10.1042/ns20200003] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2020] [Revised: 10/23/2020] [Accepted: 11/05/2020] [Indexed: 12/11/2022] Open
Abstract
Experimental and epidemiological evidence suggest that modifiable lifestyle factors, including physical exercise, can build structural and cognitive reserve in the brain, increasing resilience to injury and insult. Accordingly, exercise can reduce the increased expression of proinflammatory cytokines in the brain associated with ageing or experimentally induced neuroinflammation. However, the cellular mechanisms by which exercise exerts this effect are unknown, including the effects of exercise on classic or alternative activation of astrocytes and microglia. In the present study, we assess the effects of nine consecutive days of treadmill running on the glial cell response to a single systemic injection of lipopolysaccharide (LPS) and, in parallel, the effects on spatial learning and memory. We show that prior exercise protects against LPS-induced impairment of performance in the object displacement task concomitant with attenuation of IL-1β, TNFα and IL-10 mRNA expression in the hippocampus. Assessment of isolated astrocytes and microglia revealed that LPS induced a proinflammatory response in these cells that was not observed in cells prepared from the brains of mice who had undergone prior exercise. The results suggest that exercise modulates neuroinflammation by reducing the proinflammatory microglial response, suggesting a mechanism by which exercise may be neuroprotective.
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2
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Hu X, Yuan Y, Wang D, Su Z. Heterogeneous astrocytes: Active players in CNS. Brain Res Bull 2016; 125:1-18. [PMID: 27021168 DOI: 10.1016/j.brainresbull.2016.03.017] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2016] [Revised: 03/22/2016] [Accepted: 03/24/2016] [Indexed: 12/12/2022]
Abstract
Astrocytes, the predominant cell type that are broadly distributed in the brain and spinal cord, play key roles in maintaining homeostasis of the central nerve system (CNS) in physiological and pathological conditions. Increasing evidence indicates that astrocytes are a complex colony with heterogeneity on morphology, gene expression, function and many other aspects depending on their spatio-temporal distribution and activation level. In pathological conditions, astrocytes differentially respond to all kinds of insults, including injury and disease, and participate in the neuropathological process. Based on current studies, we here give an overview of the roles of heterogeneous astrocytes in CNS, especially in neuropathologies, which focuses on biological and functional diversity of astrocytes. We propose that a precise understanding of the heterogeneous astrocytes is critical to unlocking the secrets about pathogenesis and treatment of the mazy CNS.
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Affiliation(s)
- Xin Hu
- Institute of Neuroscience and Key Laboratory of Molecular Neurobiology of Ministry of Education, Second Military Medical University, Shanghai, China
| | - Yimin Yuan
- Institute of Neuroscience and Key Laboratory of Molecular Neurobiology of Ministry of Education, Second Military Medical University, Shanghai, China
| | - Dan Wang
- Institute of Neuroscience and Key Laboratory of Molecular Neurobiology of Ministry of Education, Second Military Medical University, Shanghai, China
| | - Zhida Su
- Institute of Neuroscience and Key Laboratory of Molecular Neurobiology of Ministry of Education, Second Military Medical University, Shanghai, China.
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3
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Zhou Y, Zhou Y, Yu S, Wu J, Chen Y, Zhao Y. Sulfiredoxin-1 exerts anti-apoptotic and neuroprotective effects against oxidative stress-induced injury in rat cortical astrocytes following exposure to oxygen-glucose deprivation and hydrogen peroxide. Int J Mol Med 2015; 36:43-52. [PMID: 25955519 PMCID: PMC4494579 DOI: 10.3892/ijmm.2015.2205] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2014] [Accepted: 04/21/2015] [Indexed: 01/05/2023] Open
Abstract
Sulfiredoxin 1 (Srxn1), an endogenous antioxidant protein, plays an important neuroprotective role in cerebral ischemia. However, the exact mechanisms of action of Srxn1 in cerebral ischemia have not yet been fully elucidated. Therefore, in the present study, rat primary cortical astrocytes transfected with a lentiviral vector encoding short hairpin RNA (shRNA) were exposed to oxygen-glucose deprivation (OGD) for 4 h or to 100 μM hydrogen peroxide (H2O2) for 6 h, in order to construct an in vitro model of cerebral ischemia-induced damage. We found that following exposure to OGD or H2O2, the knockdown of Srxn1 resulted in a decrease in cell viability, as shown by MTS assay, an increase in cell damage, as shown by lactate dehydrogenase assay and an increase in cellular apoptosis, as shown by Hoechst 33342 staining and flow cytometry. Furthermore, we found that following exposure to OGD or H2O2, the knockdown of Srxn1 resulted in a decrease in mitochondrial transmembrane potential (Δψm) as indicated by JC-1 staining, an increase in the cytoplasmic expression of cytochrome c (Cyt.C), caspase-3, caspase-9, poly(ADP-ribose) polymerase (PARP) and Bax protein at the protein level, but a decrease in the expression of the anti-apoptotic Bcl-2 protein; these effects were tightly associated with the mitochondrial apoptotic pathway. However, we found that there was no obvious change in the intracellular calcium ([Ca2+]i) levels and caspase-12 expression following the knockdown of Srxn1. Taken together, the results from the present study demonstrate that Srxn1 protects primary rat cortical astrocytes from OGD- or H2O2-induced apoptosis and that involves the activation of the mitochondrial apoptotic pathway, which suggests that Srxn1 may be a potential target in the treatment of cerebral ischemia.
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Affiliation(s)
- Yunchuan Zhou
- Department of Pathology, Chongqing Medical University, Chongqing 400016, P.R. China
| | - Yang Zhou
- Department of Pathology, Chongqing Medical University, Chongqing 400016, P.R. China
| | - Shanshan Yu
- Department of Pathology, Chongqing Medical University, Chongqing 400016, P.R. China
| | - Jingxian Wu
- Department of Pathology, Chongqing Medical University, Chongqing 400016, P.R. China
| | - Yanlin Chen
- Department of Pathology, Chongqing Medical University, Chongqing 400016, P.R. China
| | - Yong Zhao
- Department of Pathology, Chongqing Medical University, Chongqing 400016, P.R. China
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4
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Pang Y, Chai CR, Gao K, Jia XH, Kong JG, Chen XQ, Vatcher G, Chen JG, Yu ACH. Ischemia preconditioning protects astrocytes from ischemic injury through 14-3-3γ. J Neurosci Res 2015; 93:1507-18. [PMID: 25711139 DOI: 10.1002/jnr.23574] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2014] [Revised: 01/11/2015] [Accepted: 01/25/2015] [Indexed: 12/28/2022]
Abstract
Stroke is a leading cause of death and disability, and new strategies are required to reduce neuronal injury and improve prognosis. Ischemia preconditioning (IPC) is an intrinsic phenomenon that protects cells from subsequent ischemic injury and might provide promising mechanisms for clinical treatment. In this study, primary astrocytes exhibited significantly less cell death than control when exposed to different durations of IPC (15, 30, 60, or 120 min). A 15-min duration was the most effective IPC to protect astrocytes from 8-hr-ischemia injury. The protective mechanisms of IPC involve the upregulation of protective proteins, including 14-3-3γ, and attenuation of malondialdehyde (MDA) content and ATP depletion. 14-3-3γ is an antiapoptotic intracellular protein that was significantly upregulated for up to 84 hr after IPC. In addition, IPC promoted activation of the c-Jun N-terminal kinase (JNK), extracellular signal-related kinase (ERK)-1/2, p38, and protein kinase B (Akt) signaling pathways. When JNK was specifically inhibited with SP600125, the upregulation of 14-3-3γ induced by IPC was almost completely abolished; however, there was no effect on ATP or MDA levels. This suggests that, even though both energy preservation and 14-3-3γ up-regulation were turned on by IPC, they were controlled by different pathways. The ERK1/2, p38, and Akt signaling pathways were not involved in the 14-3-3γ upregulation and energy preservation. These results indicate that IPC could protect astrocytes from ischemia injury by inducing 14-3-3γ and by alleviating energy depletion through different pathways, suggesting multiple protection of IPC and providing new insights into potential stroke therapies.
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Affiliation(s)
- Ying Pang
- Neuroscience Research Institute, Peking University, Beijing, China.,Department of Neurobiology, School of Basic Medical Sciences, Health Science Center, Peking University, Beijing, China.,Key Laboratory for Neuroscience, Ministry of Education/National Health and Family Planning Commission, Peking University, Beijing, China
| | - Chao Rui Chai
- Neuroscience Research Institute, Peking University, Beijing, China.,Department of Neurobiology, School of Basic Medical Sciences, Health Science Center, Peking University, Beijing, China.,Key Laboratory for Neuroscience, Ministry of Education/National Health and Family Planning Commission, Peking University, Beijing, China
| | - Kai Gao
- Neuroscience Research Institute, Peking University, Beijing, China.,Department of Neurobiology, School of Basic Medical Sciences, Health Science Center, Peking University, Beijing, China.,Key Laboratory for Neuroscience, Ministry of Education/National Health and Family Planning Commission, Peking University, Beijing, China
| | - Xi Hua Jia
- Neuroscience Research Institute, Peking University, Beijing, China.,Department of Neurobiology, School of Basic Medical Sciences, Health Science Center, Peking University, Beijing, China.,Key Laboratory for Neuroscience, Ministry of Education/National Health and Family Planning Commission, Peking University, Beijing, China
| | - Jin Ge Kong
- Neuroscience Research Institute, Peking University, Beijing, China.,Department of Neurobiology, School of Basic Medical Sciences, Health Science Center, Peking University, Beijing, China.,Key Laboratory for Neuroscience, Ministry of Education/National Health and Family Planning Commission, Peking University, Beijing, China
| | - Xiao Qian Chen
- Department of Pathophysiology, Ministry of Education and Department of Pharmacology, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Greg Vatcher
- Neuroscience Research Institute, Peking University, Beijing, China.,Department of Neurobiology, School of Basic Medical Sciences, Health Science Center, Peking University, Beijing, China.,Key Laboratory for Neuroscience, Ministry of Education/National Health and Family Planning Commission, Peking University, Beijing, China
| | - Jian Guo Chen
- Key Laboratory of Biomembrane and Membrane Bioengineering, Key Laboratory of Cell Proliferation and Differentiation, Ministry of Education, College of Life Sciences, Peking University, Beijing, China
| | - Albert Cheung Hoi Yu
- Neuroscience Research Institute, Peking University, Beijing, China.,Department of Neurobiology, School of Basic Medical Sciences, Health Science Center, Peking University, Beijing, China.,Key Laboratory for Neuroscience, Ministry of Education/National Health and Family Planning Commission, Peking University, Beijing, China.,Laboratory of Translational Medicine, Institute of Systems Biomedicine, Peking University, Beijing, China
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5
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Liang HJ, Chai RC, Li X, Kong JG, Jiang JH, Ma J, Vatcher G, Yu ACH. Astrocytic exportin-7 responds to ischemia through mediating LKB1 translocation from the nucleus to the cytoplasm. J Neurosci Res 2014; 93:253-67. [PMID: 25250856 DOI: 10.1002/jnr.23486] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2014] [Revised: 07/16/2014] [Accepted: 08/18/2014] [Indexed: 11/06/2022]
Abstract
The superfamily of importin-β-related proteins is the largest class of nuclear transport receptors and can be generally divided into importins and exportins according to their transport directions. Eleven importins and seven exportins have been identified, and the expression patterns of both classes are important for their functions in nucleocytoplasmic transport activities. This study demonstrates that all of the importins (importin-β; transportin-1, -2, and -3; and importin-4, -5, -7, -8, -9, -11, and -13) and all the exportins (exportin-1, -2, -4, -5, -6, -7, and -t) are differentially expressed in the cerebral cortex, cerebellum, hippocampus, and brainstem and in primary cultures of cerebral cortical astrocytes and neurons. For astrocytes, we observed that different importins and exportins displayed different expression changes during 0-6 hr of ischemia treatment, especially an increase of both the mRNA and the protein of exportin-7. Immunostaining showed that exportin-7 accumulated inside the nucleus and around the nuclear envelope. In addition, we noticed an increased cytoplasmic distribution of one of the cargo proteins of exportin-7, LKB1, an important element in maintaining energy homeostasis. This increased cytoplasmic distribution was accompanied by an increased expression of exportin-7 under ischemia in astrocytes. We demonstrate that exportin-7 responds to ischemia in astrocytes and that this response involves translocation of LKB1, a protein that plays important roles during metabolic stress, from the nucleus to the cytoplasm.
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Affiliation(s)
- Hai Jie Liang
- Neuroscience Research Institute and Department of Neurobiology, School of Basic Medical Sciences, Peking University, Beijing, China; Key Laboratory for Neuroscience of the Ministry of Education and Key Laboratory for Neuroscience of the National Health and Family Planning Commission, Peking University, Beijing, China
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6
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He L, Zhang X, Wei X, Li Y. Progesterone attenuates aquaporin-4 expression in an astrocyte model of ischemia/reperfusion. Neurochem Res 2014; 39:2251-61. [PMID: 25200987 DOI: 10.1007/s11064-014-1427-7] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2014] [Revised: 07/23/2014] [Accepted: 08/30/2014] [Indexed: 01/01/2023]
Abstract
Previous studies have suggested that progesterone may be involved in neuroprotection by preventing brain edema. In this study, we assessed the effects of progesterone on aquaporin-4 (AQP4) expression in an ischemia/reperfusion model of cultured rat astrocytes, and further explored the possible role of the protein kinase C (PKC) pathway in this course. We evaluate primary culture astrocytes exposed to 4 h oxygen-glucose deprivation (OGD) followed by 24 h reperfusion (OGD4h/R24h) as a means of simulating cortex ischemia and reperfusion, and test the effect of progesterone on AQP4 expression in response to OGD4h/R24h. Besides, the cell viability was assessed by MTT reduction and lactate dehydrogenase release assay, accompanied by cell morphology survey. At a concentration of 1 and 2 μM, progesterone significantly attenuated AQP4 at the level of both protein and mRNA and ameliorated the cell viability of astrocytes from OGD/reperfusion injury. Moreover, this effect was blocked by the PKC inhibitor Ro31-8220, which was employed before the OGD. These results indicate that progesterone exerts the protective effects and attenuates AQP4 expression in an astrocyte model of ischemia/reperfusion depending on the PKC signal pathway.
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Affiliation(s)
- Lu He
- Department of Anatomy and Histology, School of Basic Medical Sciences, Tianjin Medical University, 22 Qixiangtai Road, Tianjin, 300070, China
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7
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Korenić A, Boltze J, Deten A, Peters M, Andjus P, Radenović L. Astrocytic mitochondrial membrane hyperpolarization following extended oxygen and glucose deprivation. PLoS One 2014; 9:e90697. [PMID: 24587410 PMCID: PMC3938803 DOI: 10.1371/journal.pone.0090697] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2013] [Accepted: 02/03/2014] [Indexed: 11/23/2022] Open
Abstract
Astrocytes can tolerate longer periods of oxygen and glucose deprivation (OGD) as compared to neurons. The reasons for this reduced vulnerability are not well understood. Particularly, changes in mitochondrial membrane potential (Δψm) in astrocytes, an indicator of the cellular redox state, have not been investigated during reperfusion after extended OGD exposure. Here, we subjected primary mouse astrocytes to glucose deprivation (GD), OGD and combinations of both conditions varying in duration and sequence. Changes in Δψm, visualized by change in the fluorescence of JC-1, were investigated within one hour after reconstitution of oxygen and glucose supply, intended to model in vivo reperfusion. In all experiments, astrocytes showed resilience to extended periods of OGD, which had little effect on Δψm during reperfusion, whereas GD caused a robust Δψm negativation. In case no Δψm negativation was observed after OGD, subsequent chemical oxygen deprivation (OD) induced by sodium azide caused depolarization, which, however, was significantly delayed as compared to normoxic group. When GD preceded OD for 12 h, Δψm hyperpolarization was induced by both GD and subsequent OD, but significant interaction between these conditions was not detected. However, when GD was extended to 48 h preceding OGD, hyperpolarization enhanced during reperfusion. This implicates synergistic effects of both conditions in that sequence. These findings provide novel information regarding the role of the two main substrates of electron transport chain (glucose and oxygen) and their hyperpolarizing effect on Δψm during substrate deprivation, thus shedding new light on mechanisms of astrocyte resilience to prolonged ischemic injury.
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Affiliation(s)
- Andrej Korenić
- Centre for Laser Microscopy, Department of Physiology and Biochemistry, Faculty of Biology, University of Belgrade, Belgrade, Serbia
| | - Johannes Boltze
- Fraunhofer Institute for Cell Therapy and Immunology, Leipzig, Germany ; Translational Centre for Regenerative Medicine, University of Leipzig, Leipzig, Germany ; Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts, United States of America
| | - Alexander Deten
- Fraunhofer Institute for Cell Therapy and Immunology, Leipzig, Germany
| | - Myriam Peters
- Fraunhofer Institute for Cell Therapy and Immunology, Leipzig, Germany
| | - Pavle Andjus
- Centre for Laser Microscopy, Department of Physiology and Biochemistry, Faculty of Biology, University of Belgrade, Belgrade, Serbia
| | - Lidija Radenović
- Centre for Laser Microscopy, Department of Physiology and Biochemistry, Faculty of Biology, University of Belgrade, Belgrade, Serbia
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8
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Jo WK, Law ACK, Chung SK. The neglected co-star in the dementia drama: the putative roles of astrocytes in the pathogeneses of major neurocognitive disorders. Mol Psychiatry 2014; 19:159-67. [PMID: 24393807 DOI: 10.1038/mp.2013.171] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/01/2013] [Revised: 09/26/2013] [Accepted: 10/29/2013] [Indexed: 01/03/2023]
Abstract
Alzheimer's disease (AD) and vascular dementia are the major causes of cognitive disorders worldwide. They are characterized by cognitive impairments along with neuropsychiatric symptoms, and that their pathogeneses show overlapping multifactorial mechanisms. Although AD has long been considered the most common cause of dementia, individuals afflicted with AD commonly exhibit cerebral vascular abnormalities. The concept of mixed dementia has emerged to more clearly identify patients with neurodegenerative phenomena exhibiting both AD and cerebral vascular pathologies-vascular damage along with β-amyloid (Aβ)-associated neurotoxicity and τ-hyperphosphorylation. Cognitive impairment has long been commonly explained through a 'neuro-centric' perspective, but emerging evidence has shed light over the important roles that neurovascular unit dysfunction could have in neuronal death. Moreover, accumulating data have been demonstrating astrocytes being the essential cell type in maintaining proper central nervous system functioning. In relation to dementia, the roles of astrocytes in Aβ deposition and clearance are unclear. This article emphasizes the multiple events triggered by ischemia and the cytotoxicity exerted by Aβ either alone or in association with endothelin-1 and receptor for advanced glycation end products, thereby leading to neurodegeneration in an 'astroglio-centric' perspective.
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Affiliation(s)
- W K Jo
- Neural Dysfunction Research Laboratory, Department of Psychiatry, LKS Faculty of Medicine, The University of Hong Kong, Pok Fu Lam, Hong Kong
| | - A C K Law
- 1] Neural Dysfunction Research Laboratory, Department of Psychiatry, LKS Faculty of Medicine, The University of Hong Kong, Pok Fu Lam, Hong Kong [2] Research Centre of Heart, Brain, Hormone and Healthy Aging, LKS Faculty of Medicine, The University of Hong Kong, Pok Fu Lam, Hong Kong [3] State Key Laboratory of Brain and Cognitive Sciences, The University of Hong Kong, Pok Fu Lam, Hong Kong
| | - S K Chung
- 1] State Key Laboratory of Brain and Cognitive Sciences, The University of Hong Kong, Pok Fu Lam, Hong Kong [2] Department of Anatomy, LKS Faculty of Medicine, The University of Hong Kong, Pok Fu Lam, Hong Kong
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9
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Chai RC, Jiang JH, Wong AYK, Jiang F, Gao K, Vatcher G, Hoi Yu AC. AQP5 is differentially regulated in astrocytes during metabolic and traumatic injuries. Glia 2013; 61:1748-65. [PMID: 23922257 DOI: 10.1002/glia.22555] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2013] [Revised: 05/30/2013] [Accepted: 06/17/2013] [Indexed: 01/14/2023]
Abstract
Water movement plays vital roles in both physiological and pathological conditions in the brain. Astrocytes are responsible for regulating this water movement and are the major contributors to brain edema in pathological conditions. Aquaporins (AQPs) in astrocytes play critical roles in the regulation of water movement in the brain. AQP1, 3, 4, 5, 8, and 9 have been reported in the brain. Compared with AQP1, 4, and 9, AQP3, 5, and 8 are less studied. Among the lesser known AQPs, AQP5, which has multiple functions identified outside the central nervous system, is also indicated to be involved in hypoxia injury in astrocytes. In our study, AQP5 expression could be detected both in primary cultures of astrocytes and neurons, and AQP5 expression in astrocytes was confirmed in 1- to 4-week old primary cultures of astrocytes. AQP5 was localized on the cytoplasmic membrane and in the cytoplasm of astrocytes. AQP5 expression was downregulated during ischemia treatment and upregulated after scratch-wound injury, which was also confirmed in a middle cerebral artery occlusion model and a stab-wound injury model in vivo. The AQP5 increased after scratch injury was polarized to the migrating processes and cytoplasmic membrane of astrocytes in the leading edge of the scratch-wound, and AQP5 over-expression facilitated astrocyte process elongation after scratch injury. Taken together, these results indicate that AQP5 might be an important water channel in astrocytes that is differentially expressed during various brain injuries.
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Affiliation(s)
- Rui Chao Chai
- Neuroscience Research Institute & Department of Neurobiology, School of Basic Medical Sciences, Peking University, Beijing 100191, China
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10
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Istaphanous GK, Ward CG, Nan X, Hughes EA, McCann JC, McAuliffe JJ, Danzer SC, Loepke AW. Characterization and quantification of isoflurane-induced developmental apoptotic cell death in mouse cerebral cortex. Anesth Analg 2013; 116:845-54. [PMID: 23460572 DOI: 10.1213/ane.0b013e318281e988] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
BACKGROUND Accumulating evidence indicates that isoflurane and other, similarly acting anesthetics exert neurotoxic effects in neonatal animals. However, neither the identity of dying cortical cells nor the extent of cortical cell loss has been sufficiently characterized. We conducted the present study to immunohistochemically identify the dying cells and to quantify the fraction of cells undergoing apoptotic death in neonatal mouse cortex, a substantially affected brain region. METHODS Seven-day-old littermates (n = 36) were randomly assigned to a 6-hour exposure to either 1.5% isoflurane or fasting in room air. Animals were euthanized immediately after exposure and brain sections were double-stained for activated caspase 3 and one of the following cellular markers: Neuronal Nuclei (NeuN) for neurons, glutamic acid decarboxylase (GAD)65 and GAD67 for GABAergic cells, as well as GFAP (glial fibrillary acidic protein) and S100β for astrocytes. RESULTS In 7-day-old mice, isoflurane exposure led to widespread increases in apoptotic cell death relative to controls, as measured by activated caspase 3 immunolabeling. Confocal analyses of caspase 3-labeled cells in cortical layers II and III revealed that the overwhelming majority of cells were postmitotic neurons, but some were astrocytes. We then quantified isoflurane-induced neuronal apoptosis in visual cortex, an area of substantial injury. In unanesthetized control animals, 0.08% ± 0.001% of NeuN-positive layer II/III cortical neurons were immunoreactive for caspase 3. By contrast, the rate of apoptotic NeuN-positive neurons increased at least 11-fold (lower end of the 95% confidence interval [CI]) to 2.0% ± 0.004% of neurons immediately after isoflurane exposure (P = 0.0017 isoflurane versus control). In isoflurane-treated animals, 2.9% ± 0.02% of all caspase 3-positive neurons in superficial cortex also coexpressed GAD67, indicating that inhibitory neurons may also be affected. Analysis of GABAergic neurons, however, proved unexpectedly complex. In addition to inducing apoptosis among some GAD67-immunoreactive neurons, anesthesia also coincided with a dramatic decrease in both GAD67 (0.98 vs 1.84 ng/mg protein, P < 0.00001, anesthesia versus control) and GAD65 (2.25 ± 0.74 vs 23.03 ± 8.47 ng/mg protein, P = 0.0008, anesthesia versus control) protein levels. CONCLUSIONS Prolonged exposure to isoflurane increased neuronal apoptotic cell death in 7-day-old mice, eliminating approximately 2% of cortical neurons, of which some were identified as GABAergic interneurons. Moreover, isoflurane exposure interfered with the inhibitory nervous system by downregulating the central enzymes GAD65 and GAD67. Conversely, at this age, only a minority of degenerating cells were identified as astrocytes. The clinical relevance of these findings in animals remains to be determined.
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Affiliation(s)
- George K Istaphanous
- Department of Anesthesia, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA
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11
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Paquet M, Ribeiro FM, Guadagno J, Esseltine JL, Ferguson SSG, Cregan SP. Role of metabotropic glutamate receptor 5 signaling and homer in oxygen glucose deprivation-mediated astrocyte apoptosis. Mol Brain 2013; 6:9. [PMID: 23406666 PMCID: PMC3598502 DOI: 10.1186/1756-6606-6-9] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2013] [Accepted: 02/11/2013] [Indexed: 02/03/2023] Open
Abstract
BACKGROUND Group I metabotropic glutamate receptors (mGluR) are coupled via Gαq/11 to the activation of phospholipase Cβ, which hydrolyzes membrane phospholipids to form inositol 1,4,5 trisphosphate and diacylglycerol. In addition to functioning as neurotransmitter receptors to modulate synaptic activity, pathological mGluR5 signaling has been implicated in a number of disease processes including Fragile X, amyotrophic lateral sclerosis, multiple sclerosis, Alzheimer's disease, Parkinson's disease, Huntington's disease, epilepsy, and drug addiction. The expression of mGluR5 in astrocytes has been shown to be increased in several acute and chronic neurodegenerative conditions, but little is known about the functional relevance of mGluR5 up-regulation in astrocytes following injury. RESULTS In the current study, we investigated primary mouse cortical astrocyte cell death in response to oxygen glucose deprivation (OGD) and found that OGD induced both necrotic and apoptotic cell death of astrocytes. OGD resulted in an increase in astrocytic mGluR5 protein expression, inositol phosphate formation and extracellular regulated kinase (ERK1/2) phosphorylation, but only inositol phosphate formation was blocked with the mGluR5 selective antagonist MPEP. Cortical astrocytes derived from mGluR5 knockout mice exhibited resistance to OGD-stimulated apoptosis, but a lack of mGluR5 expression did not confer protection against necrotic cell death. The antagonism of the inositol 1,4,5 trisphosphate receptor also reduced apoptotic cell death in wild-type astrocytes, but did not provide any additional protection to astrocytes derived from mGluR5 null mice. Moreover, the disruption of Homer protein interactions with mGluR5 also reduced astrocyte apoptosis. CONCLUSION Taken together these observations indicated that mGluR5 up-regulation contributed selectively to the apoptosis of astrocytes via the activation of phospholipase C and the release of calcium from intracellular stores as well as via the association with Homer proteins.
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Affiliation(s)
- Maryse Paquet
- J, Allyn Taylor Centre for Cell Biology, Robarts Research Institute, Department of Physiology and Pharmacology, The University of Western Ontario, 100 Perth Drive, London, ON, N6A 5K8, Canada
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12
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HSIAO WW, LIAO HS, LIN HH, LEE YL, FAN CK, LIAO CW, LIN PY, HWU ET, CHANG CS. Biophysical Analysis of Astrocytes Apoptosis Triggered by Larval E/S Antigen from Cerebral Toxocarosis-Causing Pathogen Toxocara canis. ANAL SCI 2013; 29:885-92. [DOI: 10.2116/analsci.29.885] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Affiliation(s)
- Wesley W. HSIAO
- Institute of Physics, Academia Sinica
- Taiwan International Graduate Program–Chemical Biology and Molecular Biophysics, Institute of Biological Chemistry, Academia Sinica
- College of Life Sciences, National Tsing Hua University
| | | | - Hsing-Hung LIN
- Genomics Research Center, Academia Sinica
- Taiwan International Graduate Program–Chemical Biology and Molecular Biophysics, Institute of Biological Chemistry, Academia Sinica
| | - Yueh-Lun LEE
- Department of Microbiology and Immunology, Taipei Medical University
| | - Chia-Kwung FAN
- Department of Parasitology, Taipei Medical University
- Master Program in Global Health and Development, Taipei Medical University
| | - Chien-Wei LIAO
- Department of Parasitology, Taipei Medical University
- Master Program in Global Health and Development, Taipei Medical University
| | | | - En-Te HWU
- Institute of Physics, Academia Sinica
| | - Chia-Seng CHANG
- Institute of Physics, Academia Sinica
- Taiwan International Graduate Program–Chemical Biology and Molecular Biophysics, Institute of Biological Chemistry, Academia Sinica
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Zhou S, Wu H, Zeng C, Xiong X, Tang S, Tang Z, Sun X. Apolipoprotein E protects astrocytes from hypoxia and glutamate-induced apoptosis. FEBS Lett 2012; 587:254-8. [DOI: 10.1016/j.febslet.2012.12.003] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2012] [Revised: 11/29/2012] [Accepted: 12/02/2012] [Indexed: 10/27/2022]
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14
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Guo J, Duckles SP, Weiss JH, Li X, Krause DN. 17β-Estradiol prevents cell death and mitochondrial dysfunction by an estrogen receptor-dependent mechanism in astrocytes after oxygen-glucose deprivation/reperfusion. Free Radic Biol Med 2012; 52:2151-60. [PMID: 22554613 PMCID: PMC3377773 DOI: 10.1016/j.freeradbiomed.2012.03.005] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/26/2011] [Revised: 03/07/2012] [Accepted: 03/08/2012] [Indexed: 11/16/2022]
Abstract
17β-Estradiol (E2) has been shown to protect against ischemic brain injury, yet its targets and the mechanisms are unclear. E2 may exert multiple regulatory actions on astrocytes that may greatly contribute to its ability to protect the brain. Mitochondria are recognized as playing central roles in the development of injury during ischemia. Increasing evidence indicates that mitochondrial mechanisms are critically involved in E2-mediated protection. In this study, the effects of E2 and the role of mitochondria were evaluated in primary cultures of astrocytes subjected to an ischemia-like condition of oxygen-glucose deprivation (OGD)/reperfusion. We showed that E2 treatment significantly protects against OGD/reperfusion-induced cell death as determined by cell viability, apoptosis, and lactate dehydrogenase leakage. The protective effects of E2 on astrocytic survival were blocked by an estrogen receptor (ER) antagonist (ICI-182,780) and were mimicked by an ER agonist selective for ERα (PPT), but not by an ER agonist selective for ERβ (DPN). OGD/reperfusion provoked mitochondrial dysfunction as manifested by an increase in cellular reactive oxygen species production, loss of mitochondrial membrane potential, and depletion of ATP. E2 pretreatment significantly inhibited OGD/reperfusion-induced mitochondrial dysfunction, and this effect was also blocked by ICI-182,780. Therefore, we conclude that E2 provides direct protection to astrocytes from ischemic injury by an ER-dependent mechanism, highlighting an important role for ERα. Estrogen protects against mitochondrial dysfunction at the early phase of ischemic injury. However, overall implications for protection against brain ischemia and its complex sequelae await further exploration.
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Affiliation(s)
- Jiabin Guo
- Department of Pharmacology (J.G., S.P.D., D.N.K), Department of Neurology (J.H.W.), School of Medicine, University of California, Irvine, CA 92697, USA
- State Key Laboratory of Natural Biomimetic Drugs, Department of Pharmacology, School of Basic Medicine, Peking University, Beijing 100191, China
- Evaluation and Research Centre for Toxicology, Institute of Disease Control and Prevention, Academy of Military Medical Sciences, Beijing 100071, China
| | - Sue P. Duckles
- Department of Pharmacology (J.G., S.P.D., D.N.K), Department of Neurology (J.H.W.), School of Medicine, University of California, Irvine, CA 92697, USA
| | - John H. Weiss
- Department of Pharmacology (J.G., S.P.D., D.N.K), Department of Neurology (J.H.W.), School of Medicine, University of California, Irvine, CA 92697, USA
| | - Xuejun Li
- State Key Laboratory of Natural Biomimetic Drugs, Department of Pharmacology, School of Basic Medicine, Peking University, Beijing 100191, China
| | - Diana N. Krause
- Department of Pharmacology (J.G., S.P.D., D.N.K), Department of Neurology (J.H.W.), School of Medicine, University of California, Irvine, CA 92697, USA
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Abstract
Stroke is a major neurological disorder characterized by an increase in the Glu (glutamate) concentration resulting in excitotoxicity and eventually cellular damage and death in the brain. HIF-1 (hypoxia-inducible factor-1), a transcription factor, plays an important protective role in promoting cellular adaptation to hypoxic conditions. It is known that HIF-1α, the regulatable subunit of HIF-1, is expressed by astrocytes under severe ischaemia. However, the effect of HIF-1 on astrocytes following Glu toxicity during ischaemia has not been well studied. We investigated the role of HIF-1 in protecting ischaemic astrocytes against Glu toxicity. Immunostaining with GFAP (glial fibrillary acidic protein) confirmed the morphological modification of astrocytes in the presence of 1 mM Glu under normoxia. Interestingly, when the astrocytes were exposed to severe hypoxia (0.1% O2), the altered cell morphology was ameliorated with up-regulation of HIF-1α. To ascertain HIF-1's protective role, effects of two HIF-1α inhibitors, YC-1 [3-(50-hydroxymethyl-20-furyl)-1-benzylindazole] and 2Me2 (2-methoxyoestradiol), were tested. Both the inhibitors decreased the recovery in astrocyte morphology and increased cell death. Given that ischaemia increases ROS (reactive oxygen species), we examined the role of GSH (reduced glutathione) in the mechanism for this protection. GSH was increased under hypoxia, and this correlated with an increase in HIF-1α stabilization in the astrocytes. Furthermore, inhibition of GSH with BSO (l-butathione sulfoximine) decreased HIF-1α expression, suggesting its role in the stabilization of HIF-1α. Overall, our results indicate that the expression of HIF-1α under hypoxia has a protective effect on astrocytes in maintaining cell morphology and viability in response to Glu toxicity.
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Xu M, Yang L, Hong LZ, Zhao XY, Zhang HL. Direct protection of neurons and astrocytes by matrine via inhibition of the NF-κB signaling pathway contributes to neuroprotection against focal cerebral ischemia. Brain Res 2012; 1454:48-64. [PMID: 22503072 DOI: 10.1016/j.brainres.2012.03.020] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2011] [Revised: 03/05/2012] [Accepted: 03/08/2012] [Indexed: 02/02/2023]
Abstract
Matrine (Mat) and oxymatrine are two major alkaloids of the Chinese herb Sophora flavescens Ait. (Leguminosae). Previous study has demonstrated that Mat reduces brain edema induced by focal cerebral ischemia. More recently, oxymatrine has been reported to produce neuroprotective effects against focal cerebral ischemia via inhibiting the activation of NF-κB in the ischemic brain tissue. In the current study, we investigated whether direct protection on neurons and astrocytes via inhibition of NF-κB signaling pathway is associated with Mat's neuroprotective effects against cerebral ischemia. In a model of permanent middle cerebral artery occlusion (pMCAO), Mat (12.5, 25 and 50 mg/kg) reduced the infarction volume and improved the neurological deficits in a dose-dependent manner, administered 10 min, 3h and even 6h following pMCAO. Mat 50 mg/kg also decreased the hemispheric water content. The number of GFAP-positive cells was markedly decreased in the ischemic cortex at 12h after ischemia. In contrast, Mat increased the number of GFAP-positive cells. Mat 50mg/kg has no effect on the cerebral blood flow (CBF). Primary neuron or astrocyte cultures were exposed to a paradigm of ischemic insult by using an oxygen-glucose deprivation (OGD), Mat (50-200 μM) reduced LDH leakage and the number of neuronal and astrocytic apoptosis, and increased the number of MAP2-positive and GFAP-positive cells. Further observations revealed that Mat increased the protein levels of IκBα, and blocked the translocation of NF-κB p65 from the cytosol to the nucleus in the ischemic cortex and injured neurons and astrocytes induced by in vitro OGD. Moreover, Mat could down-regulate NF-κB p65 downstream pro-apoptotic gene p53 and/or c-Myc in the injured neurons and astrocytes induced by OGD. The present findings suggest that Mat, even when administrated 6h after ischemia, has neuroprotective effects against focal cerebral ischemia and directly protects neurons and astrocytes via inhibition of NF-κB signaling pathway, contributing to matrine's neuroprotection against focal cerebral ischemia.
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Affiliation(s)
- Min Xu
- Department of Pharmacology and Laboratory of Cerebrovascular Pharmacology, College of Pharmaceutical Science, Soochow University, Suzhou 215123, China
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17
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Progress of Neuroscience in China From 2000 to 2009. PROG BIOCHEM BIOPHYS 2011. [DOI: 10.3724/sp.j.1206.2011.00279] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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18
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Woodruff TM, Thundyil J, Tang SC, Sobey CG, Taylor SM, Arumugam TV. Pathophysiology, treatment, and animal and cellular models of human ischemic stroke. Mol Neurodegener 2011; 6:11. [PMID: 21266064 PMCID: PMC3037909 DOI: 10.1186/1750-1326-6-11] [Citation(s) in RCA: 363] [Impact Index Per Article: 27.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2010] [Accepted: 01/25/2011] [Indexed: 01/02/2023] Open
Abstract
Stroke is the world's second leading cause of mortality, with a high incidence of severe morbidity in surviving victims. There are currently relatively few treatment options available to minimize tissue death following a stroke. As such, there is a pressing need to explore, at a molecular, cellular, tissue, and whole body level, the mechanisms leading to damage and death of CNS tissue following an ischemic brain event. This review explores the etiology and pathogenesis of ischemic stroke, and provides a general model of such. The pathophysiology of cerebral ischemic injury is explained, and experimental animal models of global and focal ischemic stroke, and in vitro cellular stroke models, are described in detail along with experimental strategies to analyze the injuries. In particular, the technical aspects of these stroke models are assessed and critically evaluated, along with detailed descriptions of the current best-practice murine models of ischemic stroke. Finally, we review preclinical studies using different strategies in experimental models, followed by an evaluation of results of recent, and failed attempts of neuroprotection in human clinical trials. We also explore new and emerging approaches for the prevention and treatment of stroke. In this regard, we note that single-target drug therapies for stroke therapy, have thus far universally failed in clinical trials. The need to investigate new targets for stroke treatments, which have pleiotropic therapeutic effects in the brain, is explored as an alternate strategy, and some such possible targets are elaborated. Developing therapeutic treatments for ischemic stroke is an intrinsically difficult endeavour. The heterogeneity of the causes, the anatomical complexity of the brain, and the practicalities of the victim receiving both timely and effective treatment, conspire against developing effective drug therapies. This should in no way be a disincentive to research, but instead, a clarion call to intensify efforts to ameliorate suffering and death from this common health catastrophe. This review aims to summarize both the present experimental and clinical state-of-the art, and to guide future research directions.
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Affiliation(s)
- Trent M Woodruff
- School of Biomedical Sciences, University of Queensland, Brisbane, Queensland 4072, Australia.
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19
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Zhou Y, Li HL, Zhao R, Yang LT, Dong Y, Yue X, Ma YY, Wang Z, Chen J, Cui CL, Yu ACH. Astrocytes Express N-Methyl-D-Aspartate Receptor Subunits in Development, Ischemia and Post-Ischemia. Neurochem Res 2010; 35:2124-34. [DOI: 10.1007/s11064-010-0325-x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/11/2010] [Indexed: 11/30/2022]
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20
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Cao X, Xiao H, Zhang Y, Zou L, Chu Y, Chu X. 1, 5-Dicaffeoylquinic acid-mediated glutathione synthesis through activation of Nrf2 protects against OGD/reperfusion-induced oxidative stress in astrocytes. Brain Res 2010; 1347:142-8. [DOI: 10.1016/j.brainres.2010.05.072] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2010] [Revised: 05/18/2010] [Accepted: 05/24/2010] [Indexed: 12/30/2022]
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21
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Zhang A, Zhang J, Sun P, Yao C, Su C, Sui T, Huang H, Cao X, Ge Y. EIF2α and caspase-12 activation are involved in oxygen–glucose–serum deprivation/restoration-induced apoptosis of spinal cord astrocytes. Neurosci Lett 2010; 478:32-6. [DOI: 10.1016/j.neulet.2010.04.062] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2010] [Revised: 04/26/2010] [Accepted: 04/26/2010] [Indexed: 11/30/2022]
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22
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Dong Y, Zhao R, Chen XQ, Yu ACH. 14-3-3γ and Neuroglobin are New Intrinsic Protective Factors for Cerebral Ischemia. Mol Neurobiol 2010; 41:218-31. [DOI: 10.1007/s12035-010-8142-4] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2009] [Accepted: 04/20/2010] [Indexed: 12/15/2022]
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23
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Progress in glial cell studies in some laboratories in China. SCIENCE CHINA-LIFE SCIENCES 2010; 53:330-337. [DOI: 10.1007/s11427-010-0067-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2010] [Accepted: 02/26/2010] [Indexed: 01/12/2023]
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24
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Abstract
Brain plasticity describes the potential of the organ for adaptive changes involved in various phenomena in health and disease. A substantial amount of experimental evidence, received in animal and cell models, shows that a cascade of plastic changes at the molecular, cellular, and tissue levels, is initiated in different regions of the postischemic brain. Underlying mechanisms include neurochemical alterations, functional changes in excitatory and inhibitory synapses, axonal and dendritic sprouting, and reorganization of sensory and motor central maps. Multiple lines of evidence indicate numerous points in which the process of postischemic recovery may be influenced with the aim to restore the full capacity of the brain tissue injured by an ischemic episode.
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Affiliation(s)
- Galyna G Skibo
- Department of Cytology, Bogomoletz Institute of Physiology, Kiev, Ukraine
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25
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Nikonenko AG, Radenovic L, Andjus PR, Skibo GG. Structural Features of Ischemic Damage in the Hippocampus. Anat Rec (Hoboken) 2009; 292:1914-21. [DOI: 10.1002/ar.20969] [Citation(s) in RCA: 91] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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26
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Dong Y, Liu HD, Zhao R, Yang CZ, Chen XQ, Wang XH, Lau LT, Chen J, Yu ACH. Ischemia activates JNK/c-Jun/AP-1 pathway to up-regulate 14-3-3γ in astrocyte. J Neurochem 2009; 109 Suppl 1:182-8. [DOI: 10.1111/j.1471-4159.2009.05974.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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27
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Elevated pressure induced astrocyte damage in the optic nerve. Brain Res 2008; 1244:142-54. [DOI: 10.1016/j.brainres.2008.09.044] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2008] [Revised: 09/08/2008] [Accepted: 09/10/2008] [Indexed: 11/22/2022]
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28
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Björklund O, Shang M, Tonazzini I, Daré E, Fredholm BB. Adenosine A1 and A3 receptors protect astrocytes from hypoxic damage. Eur J Pharmacol 2008; 596:6-13. [PMID: 18727925 DOI: 10.1016/j.ejphar.2008.08.002] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2008] [Revised: 08/01/2008] [Accepted: 08/04/2008] [Indexed: 12/15/2022]
Abstract
Brain levels of adenosine are elevated during hypoxia. Through effects on adenosine receptors (A(1), A(2A), A(2B) and A(3)) on astrocytes, adenosine can influence functions such as glutamate uptake, reactive gliosis, swelling, as well as release of neurotrophic and neurotoxic factors having an impact on the outcome of metabolic stress. We have studied the roles of these receptors in astrocytes by evaluating their susceptibility to damage induced by oxygen deprivation or exposure to the hypoxia mimic cobalt chloride (CoCl(2)). Hypoxia caused ATP breakdown and purine release, whereas CoCl(2) (0.8 mM) mainly reduced ATP by causing cell death in human D384 astrocytoma cells. Further experiments were conducted in primary astrocytes prepared from specific adenosine receptor knock-out (KO) and wild type (WT) mice. In WT cells purine release following CoCl(2) exposure was mainly due to nucleotide release, whereas hypoxia-induced intracellular ATP breakdown followed by nucleoside efflux. N-ethylcarboxamidoadenosine (NECA), an unselective adenosine receptor agonist, protected from cell death following hypoxia. Cytotoxicity was more pronounced in A(1)R KO astrocytes and tended to be higher in WT cells in the presence of the A(1) receptor antagonist 8-cyclopentyl-1,3-dipropylxanthine (DPCPX). Genetic deletion of A(2A) receptor resulted in less prominent effects. A(3)R KO glial cells were more affected by hypoxia than WT cells. Accordingly, the A(3) receptor agonist 2-chloro-N(6)-(3-iodobenzyl)-N-methyl-5'-carbamoyladenosine (CL-IB-MECA) reduced ATP depletion caused by hypoxic conditions. It also reduced apoptosis in human astroglioma D384 cells after oxygen deprivation. In conclusion, the data point to a cytoprotective role of adenosine mediated by both A(1) and A(3) receptors in primary mouse astrocytes.
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Affiliation(s)
- Olga Björklund
- Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden.
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29
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Yu ACH, Liu RY, Zhang Y, Sun HR, Qin LY, Lau LT, Wu BY, Hui HK, Heung MY, Han JS. Glial cell line-derived neurotrophic factor protects astrocytes from staurosporine- and ischemia- induced apoptosis. J Neurosci Res 2007; 85:3457-64. [PMID: 17497674 DOI: 10.1002/jnr.21345] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Glial cell line-derived neurotrophic factor (GDNF) promotes the survival and functions of neurons. It has been shown to be a promising candidate in the treatment of ischemia and other neurodegenerative diseases. We transfected mouse astrocytes in primary cultures with a human GDNF gene and found that their conditioned medium could not only support the growth and survival of cultured dopaminergic neurons but also protect astrocytes from staurosporine- and ischemia-induced apoptosis. This indicated that these transfected astrocytes could release GDNF. A similar protective effect on astrocytes against apoptosis was evident when recombinant human GDNF was used. Moreover, GDNF reduced caspase-3 activity but not that of caspase-1 in cultured astrocytes after ischemia treatment. Thus, GDNF protects astrocytes from apoptosis by inhibiting the activation of caspase-3.
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30
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Falcão AS, Silva RFM, Fernandes A, Brito MA, Brites D. Influence of hypoxia and ischemia preconditioning on bilirubin damage to astrocytes. Brain Res 2007; 1149:191-9. [PMID: 17376407 DOI: 10.1016/j.brainres.2007.02.039] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2006] [Revised: 02/16/2007] [Accepted: 02/18/2007] [Indexed: 10/23/2022]
Abstract
Hypoxia-ischemia in the perinatal period is a common cause of neurologic disability in children and is often associated with neonatal morbidity and mortality. Another frequent condition of the newborn is hyperbilirubinemia and it is well known that deposition of unconjugated bilirubin (UCB) in the central nervous system can damage nerve cells and cause encephalopathy. Interestingly, some studies report the onset of cerebral hypoxia-ischemia as a risk factor for UCB encephalopathy, since that condition often precedes neonatal hyperbilirubinemia. However, the cellular mechanisms triggered by hypoxia-ischemia that may enforce UCB deleterious effects are not well elucidated. Therefore, we designed this study to investigate whether hypoxia (HP) or combined oxygen-glucose deprivation (OGD) followed by reoxygenation, modifies glial cell susceptibility to UCB injury. Thus, cultured astrocytes were exposed to HP or OGD for 4 h and returned to normoxic conditions for another 12 h prior to incubation with UCB for 4 h. HP and OGD effects in UCB toxicity were compared to normoxic conditions. Our results demonstrate that HP and OGD preconditioning increase the vulnerability of glial cells to UCB damage by enhancing some of the deleterious effects of UCB, namely cell death by both apoptosis and necrosis. This preconditioning also augments the UCB-induced stimulation of an inflammatory response by an effect that involves the activation of the nuclear factor kappaB activation. These findings provide a novel basis for the increased risk of brain damage in jaundiced newborns that were previously exposed to hypoxia or ischemia during the perinatal period, namely during delivery.
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Affiliation(s)
- Ana S Falcão
- Centro de Patogénese Molecular-UBMBE, Faculdade de Farmácia, University of Lisbon, Av. Forças Armadas, 1600-083 Lisboa, Portugal
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31
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Chu X, Fu X, Zou L, Qi C, Li Z, Rao Y, Ma K. Oncosis, the possible cell death pathway in astrocytes after focal cerebral ischemia. Brain Res 2007; 1149:157-64. [PMID: 17433269 DOI: 10.1016/j.brainres.2007.02.061] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2006] [Revised: 02/14/2007] [Accepted: 02/14/2007] [Indexed: 11/27/2022]
Abstract
Swelling of astrocytes at early stage of cerebral ischemia has been reported, however, the fate and the cell death pathway of astrocytes are still unclear. Focal cerebral ischemia was induced in Sprague-Dawley rats by permanent occlusion of middle cerebral artery for 3 to 48 h. Haematoxylin and eosin (HE) staining, terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL), glial fibrillary acidic protein (GFAP), caspase-3 immunostaining, and double-staining with TUNEL and GFAP were carried out on consecutive sections. The ultrastructure was revealed by electron microscopy. Using electron microscope, apoptotic neurons were confirmed with condensed chromatin and apoptotic bodies. In the core of the infarct, clumps of heterochromatin around the edge of nucleus, vacuolar degeneration of the nucleus and leakage of chromatin were demonstrated at 3, 6, and 12 h respectively in the swelling astrocytes, which accorded with the process of oncosis; in the peripheral zone of the infarct, reactive astrocytes with nuclear membranes preserved demonstrated increased cell size and number and coexisted with oncotic astrocytes. Scattered GFAP-positive cells and ubiquitous caspase-3-positive cells were found in the core after 12 h following cerebral ischemia, and no cells positive for double-staining with TUNEL and GFAP were found in the ischemic regions, indicating that most GFAP-positive astrocytes did not die by apoptosis. Findings from present study demonstrate that after cerebral ischemia, oncosis may be the possible cell death pathway of astrocytes in the ischemic region, and oncotic astrocytes coexist with reactive astrocytes in the peripheral zone.
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Affiliation(s)
- Xiaofan Chu
- Department of Neurology, Second Clinical College, Jinan University, Shenzhen, 518020, China.
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32
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Karovic O, Tonazzini I, Rebola N, Edström E, Lövdahl C, Fredholm BB, Daré E. Toxic effects of cobalt in primary cultures of mouse astrocytes. Biochem Pharmacol 2007; 73:694-708. [PMID: 17169330 DOI: 10.1016/j.bcp.2006.11.008] [Citation(s) in RCA: 109] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2006] [Revised: 11/03/2006] [Accepted: 11/10/2006] [Indexed: 01/27/2023]
Abstract
Cobalt is suspected to cause memory deficit in humans and was reported to induce neurotoxicity in animal models. We have studied the effects of cobalt in primary cultures of mouse astrocytes. CoCl(2) (0.2-0.8mM) caused dose-dependent ATP depletion, apoptosis (cell shrinkage, phosphatidylserine externalization and chromatin rearrangements) and secondary necrosis. The mitochondria appeared to be a main target of cobalt toxicity, as shown by the loss of mitochondrial membrane potential (DeltaPsi(m)) and release from the mitochondria of apoptogenic factors, e.g. apoptosis inducing factor (AIF). Pre-treatment with bongkrekic acid reduced ATP depletion, implicating the involvement of the mitochondrial permeability transition (MPT) pore. Cobalt increased the generation of oxygen radicals, but antioxidants did not prevent toxicity. There was also an impaired response to ATP stimulation, evaluated as a lower raise in intracellular calcium. Similarly to hypoxia and dymethyloxallyl glycine (DMOG), cobalt triggered stabilization of the alpha-subunit of hypoxia-inducible factor HIF-1 (HIF-1alpha). This early event was followed by an increased expression of HIF-1 regulated genes, e.g. stress protein HO-1, pro-apoptotic factor Nip3 and iNOS. Although all of the three stimuli activated the HIF-1alpha pathway and decreased ATP levels, the downstream effects were different. DMOG only inhibited cell proliferation, whereas the other two conditions caused cell death by apoptosis and necrosis. This points to cobalt and hypoxia not only inducing HIF-1alpha regulated genes but also affecting similarly other cellular functions, including metabolism.
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Affiliation(s)
- Olga Karovic
- Department of Physiology and Pharmacology, Karolinska Institutet, S-171 77 Stockholm, Sweden
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33
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Floyd CL, Lyeth BG. Astroglia: important mediators of traumatic brain injury. PROGRESS IN BRAIN RESEARCH 2007; 161:61-79. [PMID: 17618970 DOI: 10.1016/s0079-6123(06)61005-4] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Traumatic brain injury (TBI) research to date has focused almost exclusively on the pathophysiology of injured neurons with very little attention paid to non-neuronal cells. However in the past decade, exciting discoveries have challenged this century-old view of passive glial cells and have led to a reinterpretation of the role of glial cells in central nervous system (CNS) biology and pathology. In this chapter we review several lines of evidence, indicating that glial cells, particularly astrocytes, are active partners to neurons in the brain, and summarize recent findings that detail the significance of astrocyte pathology in traumatic brain injury.
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Affiliation(s)
- Candace L Floyd
- Department of Physical Medicine and Rehabilitation, Center for Glial Biology in Medicine, 547 Spain Rehabilitation Center, University of Alabama at Birmingham, Birmingham, AL 35249, USA.
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34
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Zelenkov P, Baumgartner R, Bise K, Heide M, Meier R, Stocker S, Sroka R, Goldbrunner R, Stummer W. Acute morphological sequelae of photodynamic therapy with 5-aminolevulinic acid in the C6 spheroid model. J Neurooncol 2006; 82:49-60. [PMID: 17004102 DOI: 10.1007/s11060-006-9252-8] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2006] [Accepted: 08/17/2006] [Indexed: 10/24/2022]
Abstract
OBJECTIVE Aminolevulinic acid (ALA)-mediated photodynamic therapy (PDT) may represent a treatment option for malignant brain tumors. We used a three-dimensional cell culture system, the C6 glioma spheroid model, to study acute effects of PDT and how they might be influenced by treatment conditions. METHODS Spheroids were incubated for 4 h in 100 microg/ml ALA in 5% CO(2) in room air or 95% O(2) with subsequent irradiation using a diode laser (lambda = 635 nm, 40 mW/cm(2), total fluence 25 J/cm(2)). Control groups were "laser only", "ALA only", and "no drug no light". Annexin V-FITC, a marker used for detection of apoptosis, propidium iodide (PI), a marker for necrotic cells and H 33342, a chromatin stain, were used for morphological characterization of PDT effects by confocal laser scanning and fluorescence microscopy. Hematoxylin-eosin staining and TdT-FragEL (TUNEL) assay were used on cryosections. Growth kinetics were followed for 8 days after PDT. RESULTS PDT after incubation in 5% CO(2) provided incomplete cell death and growth delay in spheroids of >350 microm diameter. However, complete cell death and growth arrest occurred in smaller spheroids (<350 microm). Incubation in 95% O(2) with subsequent PDT resulted in complete cell death and growth arrest regardless of spheroid size. In incompletely damaged spheroids viable cells were restricted to spheroid centers. The rate of cell death in all control groups was negligible. Cell death was accompanied by annexin/PI costaining, but there was also evidence for annexin V-FITC staining without PI uptake. CONCLUSIONS PDT of experimental glioma results in rapid and significant cell death that could be verified as acute necrosis immediately after irradiation. This effect depended on O(2) concentration and spheroid size.
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Affiliation(s)
- Pitr Zelenkov
- Department of Neurosurgery, Ludwig-Maximilians University, Munich, Germany
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35
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Yu ACH, Sun CX, Li Q, Liu HD, Wang CR, Zhao GP, Jin M, Lau LT, Fung YWW, Liu S. Identification of a mouse synaptic glycoprotein gene in cultured neurons. Neurochem Res 2006; 30:1289-94. [PMID: 16341590 DOI: 10.1007/s11064-005-8800-5] [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] [Accepted: 04/13/2005] [Indexed: 12/19/2022]
Abstract
Neuronal differentiation and aging are known to involve many genes, which may also be differentially expressed during these developmental processes. From primary cultured cerebral cortical neurons, we have previously identified various differentially expressed gene transcripts from cultured cortical neurons using the technique of arbitrarily primed PCR (RAP-PCR). Among these transcripts, clone 0-2 was found to have high homology to rat and human synaptic glycoprotein. By in silico analysis using an EST database and the FACTURA software, the full-length sequence of 0-2 was assembled and the clone was named as mouse synaptic glycoprotein homolog 2 (mSC2). DNA sequencing revealed transcript size of mSC2 being smaller than the human and rat homologs. RT-PCR indicated that mSC2 was expressed differentially at various culture days. The mSC2 gene was located in various tissues with higher expression in brain, lung, and liver. Functions of mSC2 in neurons and other tissues remain elusive and will require more investigation.
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Benavides A, Pastor D, Santos P, Tranque P, Calvo S. CHOP plays a pivotal role in the astrocyte death induced by oxygen and glucose deprivation. Glia 2006; 52:261-75. [PMID: 16001425 DOI: 10.1002/glia.20242] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Ischemia has different consequences on the survival of astrocytes and neurons. Thus, astrocytes show a remarkable resistance to short periods of ischemia that are well known to cause neuronal death. We have used a cell culture model of stroke, oxygen, and glucose deprivation (OGD), to clarify the mechanisms responsible for the exclusive resistance of astrocytes to ischemia. The expression of genes implicated in both ischemia-induced astrocyte death and post-ischemic survival was analysed by the RNA differential display technique. Our study revealed that the expression of the CEBP homologous protein (CHOP)-coding gene is promptly an intensely upregulated following astrocyte oxygen and glucose deprivation. CHOP mRNA induction was accompanied by the activation of other genes (grp78, grp95) that, alike CHOP, are involved in the endoplasmic reticulum (ER) stress response. In addition, drugs that cause ER calcium depletion or protein N-glycosylation inhibition mimicked the effects of OGD on astrocyte survival, further supporting the involvement of ER in the astrocyte responses to OGD. Our experiments also demonstrated that upregulation of CHOP during the ER stress response is required for ischemia to cause astrocyte death. Not only the levels of CHOP mRNA and protein correlate perfectly with the degree of OGD-triggered cell injury, but also astrocyte death induced by OGD is significantly overcome by CHOP antisense oligonucleotide treatment. Nevertheless, we observed that astrocytes undergo apoptosis only when CHOP is permanently upregulated, and not when CHOP increases are transient. Finally, we found that the extent of CHOP induction is determined by the length of the ischemic stimulus. Taken together, our results indicate that permanent upregulation of CHOP is decisive for the induction of astrocyte death by OGD.
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Affiliation(s)
- Amparo Benavides
- Pharmacology Unit, Facultad de Medicina, Departamento de Ciencias Médicas and Centro Regional de Investigaciones Biomédicas, Universidad de Castilla-La Mancha, Albacete, Spain
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Nodin C, Nilsson M, Blomstrand F. Gap junction blockage limits intercellular spreading of astrocytic apoptosis induced by metabolic depression. J Neurochem 2005; 94:1111-23. [PMID: 16092948 DOI: 10.1111/j.1471-4159.2005.03241.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Astrocytes are highly coupled by gap junction channels, which allow transfer of intracellular signalling molecules and metabolites between connected cells. Astrocytic gap junctions remain open during ischemic conditions as previously demonstrated in vitro and in situ. In this study, we investigated the effect of gap junction blockage on iodoacetate-induced ATP depression and cell death progression in astrocytes in primary rat hippocampal cultures. We demonstrated that blockage of gap junctions during iodoacetate-induced inhibition of the glycolysis induced an earlier onset of the ATP depression. Moreover, initiation of apoptotic processes, demonstrated by binding of Annexin V, was critically dependent on the ATP levels. The apoptotic event was also shown to spread and involve neighbouring cells, a process that was inhibited by blockage of gap junction communication. Chelating intracellular calcium using BAPTA-AM decelerated the iodoacetate-induced ATP depression. The chelation also decelerated the spreading of apoptotic processes. Inhibition of caspases did not alter the expansion of cell groups being Annexin V positive. However, the proportion of Annexin V positive cells also being propidium iodide positive was increased after caspase inhibition. The results show that inhibition of gap junctions during cellular metabolic depression interferes with the metabolic status and cell death progression in astrocytes.
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Affiliation(s)
- Christina Nodin
- Arvid Carlsson Institute for Neuroscience at the Institute of Clinical Neuroscience, Göteborg University, Sweden
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38
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Abstract
Astrocytes are essential for neuronal survival and function, neurogenesis, and neural repair. Although astrocytes are more resistant than neurons to most stress conditions in vitro, certain astrocyte subtypes, such as the glial fibrillary acidic protein (GFAP)-negative protoplasmic astrocytes that predominate in gray matter structures, may be equally or more sensitive than neurons to ischemia in vivo. Programmed cell death differs from passive, necrotic death in that cell constituents actively participate in cell demise. Like neurons, astrocytes undergo programmed cell death during normal development. Cell culture studies have shown that astrocytes can be induced to undergo apoptosis and other forms of programmed cell death by many factors relevant to ischemia, including acidosis, oxidative stress, substrate deprivation, and cytokines. Animal models of cerebral ischemia have confirmed nuclear condensation and upregulation of Bax and caspases in a subset of astrocytes exposed to ischemia, especially in immature brain. A causal role for these events in astrocyte death is supported by improved astrocyte survival after inhibition of caspase-dependent cell death pathways. Astrocyte survival is also improved by blocking the poly(ADP-ribose)-1 cell death pathway. Markers of programmed cell death are generally less evident and less widespread in astrocytes than in neighboring neurons. However, most studies to date have relied only on markers of classical apoptosis. In addition, these studies have relied almost exclusively on GFAP to identify astrocytes. Since most protoplasmic astrocytes are poorly immunoreactive for GFAP, the extent of ischemia-induced programmed cell death in this cell type remains uncertain.
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Affiliation(s)
- Rona G Giffard
- Department of Anesthesia, Stanford University School of Medicine, Stanford, California
| | - Raymond A Swanson
- Department of Neurology, University of California and Veterans Affairs Medical Center, San Francisco, California
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Chen XQ, Fung YWW, Yu ACH. Association of 14-3-3gamma and phosphorylated bad attenuates injury in ischemic astrocytes. J Cereb Blood Flow Metab 2005; 25:338-47. [PMID: 15660102 DOI: 10.1038/sj.jcbfm.9600032] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Our recent findings indicate an induced upregulation of 14-3-3gamma mRNA and protein in ischemic cortical astrocytes. Despite being brain-specific, the functional role of 14-3-3gamma in the brain still remains largely unknown. In this study, we show that among all the 14-3-3 isoforms, only the gamma isoform is inducible under ischemia in astrocytes. Furthermore, this upregulation of 14-3-3gamma may play a specific protective role in astrocytes under ischemia. Overexpression experiments and antisense treatment show that an elevation of 14-3-3gamma protein in astrocytes promotes survival, while a decrease in 14-3-3gamma enhances apoptosis in astrocytes under ischemia. Under ischemia, endogenous 14-3-3gamma binds p-Bad, thus preventing Bad from entering mitochondria to initiate apoptosis. Therefore, 14-3-3gamma is selectively induced during ischemia to protect astrocytes from apoptosis through p-Bad-related signaling.
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Affiliation(s)
- Xiao Qian Chen
- Neuroscience Research Institute, Peking University, Beijing, China
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40
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Choi SJ, Kim MH, Lim SW, Gwak MS. Effect of ketamine on apoptosis by energy deprivation in astroglioma cells using flow cytometry system. J Korean Med Sci 2005; 20:113-20. [PMID: 15716615 PMCID: PMC2808556 DOI: 10.3346/jkms.2005.20.1.113] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Apoptosis is a programmed, physiologic mode of cell death that plays an important role in tissue homeostasis. As for the central nervous system, ischemic insults can induce pathophysiologic cascade of apoptosis in neurophils. Impairment of astrocyte functions during brain ischemia can critically influence neuron survival by neuronglia interactions. We aimed to elucidate the protective effect of ketamine on apoptosis by energy deprivation in astrocytes. Ischemic insults was induced with iodoacetate/ carbonylcyanide m-chlorophenylhydrazone (IAA/CCCP) 1.5 mM/20 microm or 150 microm/2 microm for 1 hr in the HTB-15 and CRL-1690 astrocytoma cells. Then these cells were reperfused with normal media or ketamine (0.1 mM) containing media for 1 hr or 24 hr. FITC-annexin-V staining and propidium iodide binding were determined by using flow cytometry. Cell size and granularity were measured by forward and side light scattering properties of flow cytometry system, respectively. An addition of ketamine during reperfusion increased the proportion of viable cells. Ketamine alleviated cell shrinkage and increased granularity during the early period, and ameliorated cell swelling during the late reperfusion period. Ketamine may have a valuable effect on amelioration of early and late apoptosis in the astrocytoma cells, even though the exact mechanism remains to be verified.
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Affiliation(s)
- Soo Joo Choi
- Department of Anesthesiology and Pain Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Myung Hee Kim
- Department of Anesthesiology and Pain Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Seung Woon Lim
- Department of Anesthesiology and Pain Medicine, Chungbuk National University, Cheongju, Korea
| | - Mi Sook Gwak
- Department of Anesthesiology and Pain Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
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41
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Xu L, Chock VY, Yang EY, Giffard RG. Susceptibility to apoptosis varies with time in culture for murine neurons and astrocytes: changes in gene expression and activity. Neurol Res 2005; 26:632-43. [PMID: 15327753 DOI: 10.1179/016164104225017587] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Apoptotic pathways in the brain may differ depending on cell type and developmental stage. To understand these differences, we studied several apoptotic proteins in the murine cortex and primary cultures of neurons and astrocytes of various ages in culture. We then induced apoptosis in our cultures using serum deprivation (SD) and observed changes in these apoptotic proteins. When analyzed by nuclear morphology and TUNEL staining, early cultures showed greater apoptotic injury compared with late cultures, and neuronal cultures showed greater apoptosis than astrocyte cultures. The decrease in apoptosis with development correlated best with a down-regulation of procaspase-3 and bax and decreasing caspase activation. Early culture astrocytes had higher caspase-11 levels compared with neurons. Mitogen-activated protein (MAP) kinases were also differentially expressed with activation of extracellular signal-regulated kinase (ERK) and p38 higher in early culture astrocytes and stress-activated protein kinase/C-jun N-terminal kinase (SAPK/JNK) greater in early culture neurons. However, caspase inhibitors, but not MAP kinase inhibitors reduced cell death. Our findings demonstrate that apoptosis regulatory proteins display cell type and developmentally specific expression and activation.
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Affiliation(s)
- Lijun Xu
- Department of Anesthesia, Stanford University School of Medicine, Stanford CA 94305-5123, USA
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42
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Chen XQ, Lau LT, Fung YWW, Yu ACH. Inactivation of bad by site-specific phosphorylation: The checkpoint for ischemic astrocytes to initiate or resist apoptosis. J Neurosci Res 2005; 79:798-808. [PMID: 15672442 DOI: 10.1002/jnr.20396] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Bcl-2-associated death protein (Bad), a member of the Bcl family, directs astrocytes in primary cultures to enter or resist apoptosis during ischemia in vitro. Under ischemia, Bad was the only Bcl family member whose expression was upregulated significantly during the early stages of an ischemic insult. Increased endogenous Bad was translocated from the cytoplasm to mitochondria to induce apoptosis in astrocytes. Concurrently, ischemia also induced Bad phosphorylation specifically on Ser112 to promote survival. This site-specific phosphorylation of Bad was mediated by an early activation of the mitogen-activated protein kinase/extracellular signal-regulated protein kinase (MAPK/ERK) intracellular signaling pathway. This study demonstrates that ischemia-induced Bad plays a dual role in determining whether astrocytes enter or resist apoptosis after an ischemic insult.
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Affiliation(s)
- Xiao Qian Chen
- Neuroscience Research Institute, Peking University, Beijing, China
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43
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Daniel B, DeCoster MA. Quantification of sPLA2-induced early and late apoptosis changes in neuronal cell cultures using combined TUNEL and DAPI staining. ACTA ACUST UNITED AC 2004; 13:144-50. [PMID: 15296851 DOI: 10.1016/j.brainresprot.2004.04.001] [Citation(s) in RCA: 78] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/08/2004] [Indexed: 10/26/2022]
Abstract
The terminal deoxynucleotidyl transferase (TdT) dUTP nick end labeling (TUNEL) stain is in wide use for measuring apoptosis in neurons, as well as in other cell types. TUNEL may give false positive results due to variations in labeling technique as well as staining of cells that have undergone non-apoptotic DNA strand breaks. Therefore, in isolation, TUNEL is not a certain indicator of apoptosis. Recently, we have demonstrated the potent apoptotic effect of secreted phospholipase A2 from group III (sPLA2-III) on primary cortical neurons from rat. Here we describe a computer-assisted method for quantifying TUNEL-positive neurons after sPLA2-III induced apoptosis. Extent of TUNEL is normalized to total nuclear content using 4',6-diamidino-2-phenylindole (DAPI) staining. Furthermore, DAPI counterstaining allows for determination of a nuclear morphology indicator, based on nuclear size and roundness, which we call the nuclear area factor. We found that the nuclear area factor is an early indicator of cell death (significant after 4 h post treatment), while TUNEL staining is significant at later times (26 h). Thus, the independent staining techniques using TUNEL and DAPI complement each other, and with commercially available image analysis software, may be used to indicate early as well as delayed cell injury processes.
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Affiliation(s)
- Bron Daniel
- Neuroscience Center, Louisiana State University Health Sciences Center, 2020 Gravier Street, Suite D, New Orleans, LA 70112, USA
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44
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Franke H, Günther A, Grosche J, Schmidt R, Rossner S, Reinhardt R, Faber-Zuschratter H, Schneider D, Illes P. P2X7 receptor expression after ischemia in the cerebral cortex of rats. J Neuropathol Exp Neurol 2004; 63:686-99. [PMID: 15290894 DOI: 10.1093/jnen/63.7.686] [Citation(s) in RCA: 191] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Large amounts of adenosine 5'-triphosphate (ATP) released from cellular sources under pathological conditions such as ischemia may activate purinoceptors of the P2X and P2Y types. In the present study, the expression of the P2X7 receptor-subtype in the brain cortex of spontaneously hypertensive rats was investigated using a permanent focal cerebral ischemia model. Immunocytochemistry with antibodies raised against the intracellular C-terminus of the P2X7 receptor showed a time-dependent upregulation of labeled cells in the peri-infarct region after right middle cerebral artery occlusion (MCAO) in comparison to controls. Double immunofluorescence visualized with confooal laser scanning microscopy indicated the localization of the P2X7 receptor after ischemia on microglial cells (after 1 and 4 days), on tubulin betaIII-labeled neurons (after 4 and 7 days), and on glial fibrillary acidic protein (GFAP)-positive astrocytes (after 4 days). In the following experiments, changes occurring 4 days after MCAO were investigated in detail. Western blot analysis of the cortical tissue around the area of necrosis indicated an increase in the P2X7 receptor protein. Immunoelectron microscopy revealed the receptor localization on synapses (presynaptically), on dendrites, as well as on the nuclear membrane of neurons (postsynaptically) and glial cells. Terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate-biotin nick end labeling in combination with P2X7 receptor immunocytochemistry indicated a co-expression on the apoptotic cells. Active caspase 3 was especially observed on GFAP-positive astrocytes. In conclusion, the present data demonstrate a postischemic, time-dependent upregulation of the P2X7 receptor-subtype on neurons and glial cells and suggest a role for this receptor in the pathophysiology of cerebral ischemia in vivo.
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Affiliation(s)
- Heike Franke
- Rudolf-Boehm-Institute of Pharmacology and Toxicology, University of Leipzig, Leipzig, Germany.
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45
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Yung HW, Wyttenbach A, Tolkovsky AM. Aggravation of necrotic death of glucose-deprived cells by the MEK1 inhibitors U0126 and PD184161 through depletion of ATP. Biochem Pharmacol 2004; 68:351-60. [PMID: 15194007 DOI: 10.1016/j.bcp.2004.03.030] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2004] [Accepted: 03/31/2004] [Indexed: 11/15/2022]
Abstract
The extracellular-regulated kinases (ERK) modulate cell proliferation and survival in response to several different stimuli and are therefore important drug targets. ERKs are activated by the dual phosphorylation kinase MEK1 and MEK1 inhibitors PD98059, U0126 and CI-1040 are now widely used to inhibit ERKs in cell and animal studies. In an analysis of ERK functions in astrocytes we found that PD98059 (100microM) failed to inhibit ERK phosphorylation but U0126 (50microM) inhibited ERK phosphorylation to approximately 80%. Surprisingly, U0126 also caused profound depletion of ATP in glucose-deprived cells, leading to death by necrosis. Since glucose-deprived cells depend mainly on mitochondrial ATP-synthase for ATP production, we tested whether U0126 or PD184161, a derivative of CI-1040, might inhibit ATP synthase activity, using 143B(Rho0) cells (which lack a functional F0 subunit) to further parse this effect. We found that the F1F0ATPase activity extracted from U0126- or PD184161-treated parental 143B cells or astrocytes was indeed inhibited by >or=80% suggesting a covalent change in the enzyme. However, F1F0ATPase activity extracted from similarly treated 143B(Rho0) cells was spared. Because F1F0ATPase activity in isolated mitochondria was not inhibited directly, we propose that U0126 and PD184161 inhibit ATP-synthase via an indirect action on F0. The MEK1 inhibitors also induced necrosis of other glucose-deprived cell types including primary neurons at the same concentrations required for inhibition of ERK phosphorylation. Thus, the MEK1/ERK signalling pathway may modulate ATP synthase function, and its inhibition may cause cells unable to perform glycolysis to die by necrosis.
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Affiliation(s)
- Hong Wa Yung
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB2 1QW, UK
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46
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Takuma K, Baba A, Matsuda T. Astrocyte apoptosis: implications for neuroprotection. Prog Neurobiol 2004; 72:111-27. [PMID: 15063528 DOI: 10.1016/j.pneurobio.2004.02.001] [Citation(s) in RCA: 350] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2003] [Accepted: 02/04/2004] [Indexed: 12/21/2022]
Abstract
Astrocytes, the most abundant glial cell types in the brain, provide metabolic and trophic support to neurons and modulate synaptic activity. Accordingly, impairment in these astrocyte functions can critically influence neuronal survival. Recent studies show that astrocyte apoptosis may contribute to pathogenesis of many acute and chronic neurodegenerative disorders, such as cerebral ischemia, Alzheimer's disease and Parkinson's disease. We found that incubation of cultured rat astrocytes in a Ca(2+)-containing medium after exposure to a Ca(2+)-free medium causes an increase in intracellular Ca(2+) concentration followed by apoptosis, and that NF-kappa B, reactive oxygen species, and enzymes such as calpain, xanthine oxidase, calcineurin and caspase-3 are involved in reperfusion-induced apoptosis. Furthermore, we demonstrated that heat shock protein, mitogen-activated protein/extracellular signal-regulated kinase, phosphatidylinositol-3 kinase and cyclic GMP phosphodiesterase are target molecules for anti-apoptotic drugs. This review summarizes (1) astrocytic functions in neuroprotection, (2) current evidence of astrocyte apoptosis in both in vitro and in vivo studies including its molecular pathways such as Ca(2+) overload, oxidative stress, NF-kappa B activation, mitochondrial dysfunction, endoplasmic reticulum stress, and protease activation, and (3) several drugs preventing astrocyte apoptosis. As a whole, this article provides new insights into the potential role of astrocytes as targets for neuroprotection. In addition, the advance in the knowledge of molecular mechanisms of astrocyte apoptosis may lead to the development of novel therapeutic strategies for neurodegenerative disorders.
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Affiliation(s)
- Kazuhiro Takuma
- Department of Analytical Chemistry, Faculty of Pharmaceutical Sciences and High Technology Research Center, Kobe Gakuin University, Kobe 651-2180, Japan
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47
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Sharma P, Karian J, Sharma S, Liu S, Mongan PD. Pyruvate ameliorates post ischemic injury of rat astrocytes and protects them against PARP mediated cell death. Brain Res 2004; 992:104-13. [PMID: 14604778 DOI: 10.1016/j.brainres.2003.08.043] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
This in vitro study was designed to examine the efficacy of exogenous pyruvate and glucose as a fuel substrate to protect rat astrocytes from post-ischemic injury. Astrocytes were incubated in Kreb's buffer deprived of oxygen and glucose for 6 h (ischemia) followed by incubation with added pyruvate or glucose and normoxia for the next 6 h (reperfusion). The transformation of reactive astrocytes in response to various treatments was examined by immunostaining with glial fibrillary acidic protein. The extent of cell damage was evaluated in terms of lactate dehydrogenase leakage from the cells and altered intracellular redox status. The mechanism of cell death was determined by immunoblotting with cytochrome C, caspase-3 and PARP antibodies. The mechanism of the action of pyruvate was determined by measuring the activity of pyruvate dehydrogenase complex, and cellular metabolic status by measuring ATP levels. In comparison to glucose, supply of exogenous pyruvate restored the morphological integrity of post-ischemic astrocytes and prevented gliosis. Pyruvate prevented the cell death of post-ischemic astrocytes by inhibiting the leakage of lactate dehydrogenase, decreasing the redox ratio and restraining the activation of apoptotic events such as release of mitochondrial cytochrome c and fragmentation of caspase-3 and PARP. This study also suggests that pyruvate may accelerate its own metabolism by increasing the activity of pyruvate dehydrogenase and thus restores the cellular ATP levels in post-ischemic astrocytes. Use of pyruvate as an alternate fuel substrate may provide a possibility for the novel therapeutic approach to the treatment of cerebral ischemia.
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Affiliation(s)
- Pushpa Sharma
- Department of Anesthesiology, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814, USA.
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48
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Chen XQ, Liu S, Qin LY, Wang CR, Fung YWW, Yu ACH. Selective regulation of 14-3-3? in primary culture of cerebral cortical neurons and astrocytes during development. J Neurosci Res 2004; 79:114-8. [PMID: 15558750 DOI: 10.1002/jnr.20323] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The 14-3-3 proteins exist predominantly in the brain and may play regulatory roles in cellular processes of growth, differentiation, survival, and apoptosis. The biological functions, however, of the various 14-3-3 isoforms (beta, epsilon, eta, gamma, and zeta) in the brain remain unclear. We have reported previously upregulation of 14-3-3gamma in ischemic astrocytes. In the present study, we report selective regulation of 14-3-3eta in cultured cerebral cortical neurons and astrocytes during in vitro development. In cultured neurons, gene expression levels of 14-3-3eta increase with culture age (0-10 days). Brain-derived neurotrophic factor and neurotrophin-3 upregulate 14-3-3eta gene expression. In cultured astrocytes, 14-3-3eta is downregulated with culture age (1-5 weeks). The gene expression level of 14-3-3eta is not affected by scratch injury in astrocytes or by ischemia in neurons. These data suggest a possible role of 14-3-3eta in growth and differentiation of neurons and astrocytes, indicating an intricate mechanism governing coordinated and well-controlled developmental events in the brain to ensure normal neural functions.
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Affiliation(s)
- Xiao Qian Chen
- Neuroscience Research Institute, Peking University, 38 Xue Yuan Road, Beijing 100083, China
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49
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Yu ACH, Yung HW, Hui MHK, Lau LT, Chen XQ, Collins RA. Cycloheximide and actinomycin D delay death and affect bcl-2, bax, and Ice gene expression in astrocytes under in vitro ischemia. J Neurosci Res 2003; 74:318-25. [PMID: 14515361 DOI: 10.1002/jnr.10742] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
An in vitro ischemia model was established and the effect of the metabolic inhibitors cycloheximide (CHX) and actinomycin D (ActD) on apoptosis in astrocytes under ischemia studied. CHX decreased by 75% the number of cells dying after 6 hr of ischemia compared with control cultures. TdT-mediated dUTP nick end labelling (TUNEL) staining of comparable cultures was reduced by 40%. ActD decreased cell death by 60% compared with controls. The number of TUNEL-positive cells was reduced by 38%. The nuclear shrinkage in TUNEL-positive astrocytes in control cultures did not occur in ActD-treated astrocytes, indicating that nuclear shrinkage and DNA fragmentation during apoptosis are two unrelated processes. Expression of bcl-2 (alpha and beta), bax, and Ice in astrocytes under similar ischemic conditions, as measured by quantitative reverse transcription-polymerase chain reaction, indicated that ischemia down-regulated bcl-2 (alpha and beta) and bax. Ice was initially down-regulated from 0 to 4 hr, before returning to control levels after 8 hr of ischemia. ActD decreased the expression of these genes. CHX reduced the expression of bcl-2 (alpha and beta) but increased bax and Ice expression. It is hypothesized that the balance of proapoptotic (Bad, Bax) and antiapoptotic (Bcl-2, Bcl-Xl) proteins determines apoptosis. The data suggest that the ratio of Bcl-2/Bad in astrocytes following ActD and CHX treatment does not decrease as much in untreated cells during ischemia. Our data indicate that it is the ratio of Bcl-2 family members that plays a critical role in determining ischemia-induced apoptosis. It is also important to note that ischemia-induced apoptosis involves the regulation of RNA and protein synthesis.
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Affiliation(s)
- Albert Cheung Hoi Yu
- Neuroscience Research Institute, Peking University and Department of Neurobiology, Peking University Health Science Center, Beijing, People's Republic of China.
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50
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Ientile R, Campisi A, Raciti G, Caccamo D, Currò M, Cannavò G, Li Volti G, Macaione S, Vanella A. Cystamine inhibits transglutaminase and caspase-3 cleavage in glutamate-exposed astroglial cells. J Neurosci Res 2003; 74:52-9. [PMID: 13130505 DOI: 10.1002/jnr.10702] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Although the precise role of transglutaminase in cell death is unknown, several findings demonstrate that tissue transglutaminase selectively accumulates in cells undergoing apoptosis both in vivo and in vitro. Calcium-dependent transglutaminase reactions are also implicated in several neurodegenerative diseases, including alterations in the release of excitatory amino acids. One prevalent theme in cell damage induced by excitotoxic stimuli in different regions of the CNS is that apoptosis may be executed by intracellular caspase proteases. Furthermore, the presence of functional ion channel-gated receptors in glial cells suggests that also astrocytes can be susceptible to glutamate's toxic effects. In this study, we demonstrated that prolonged exposure to glutamate (100 microM) of cultured astrocytes caused an increase in the expression of tissue transglutaminase (tTG). This effect was prevented by preincubation with GYKI 52466, an antagonist of AMPA/KA receptors. Glutamate exposure also promoted an increase in caspase-3 compared with control cultures. Confocal laser microscopy analysis demonstrated the presence of activated caspase-3 in the cytoplasm as well as in the nucleus. The inhibition of TG-catalyzed reactions by cystamine (1 mM) blocked the activation pathway of caspase-3, with an evident reduction of enzyme cleavage. These results suggest that glutamate increased both TG and caspase-3 in astroglial cells early in the excitotoxin-induced events.
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Affiliation(s)
- R Ientile
- Department of Biochemical, Physiological, and Nutritional Sciences, University of Messina, Messina, Italy
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