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Dan Q, Ma Z, Tan Y, Visar B, Chen L. AQP4 knockout promotes neurite outgrowth via upregulating GAP43 expression in infant rats with hypoxic-ischemic brain injury. IBRAIN 2022; 8:324-337. [PMID: 37786741 PMCID: PMC10528973 DOI: 10.1002/ibra.12062] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/10/2022] [Revised: 08/04/2022] [Accepted: 08/08/2022] [Indexed: 10/04/2023]
Abstract
Neonatal hypoxic-ischemic encephalopathy (NHIE) induces severe cerebral damage and neurological dysfunction, with seldom effective therapy. Aquaporin-4 (AQP4) is involved in aggravating brain damage induced by NHIE. This study aimed to investigate the role of AQP4 underlying the pathogenesis of NHIE. Neonatal Sprague-Dawley rats were used to establish neonatal hypoxic-ischemic (HI) models, and the expression of AQP4 in the cortex, hippocampus, and lung tissues was detected by real-time quantitative polymerase chain reaction as well as Western blot. Primary cortical neurons were cultured for the oxygen-glucose deprivation (OGD) model, and siRNA was used to silence the expression of AQP4. Immunostaining of Tuj1 was performed to observe the axonal growth. CRISPER/Cas9 technology was used to knock out AQP4. The results demonstrated that AQP4 was upregulated in the cortex, hippocampus, and lung tissues in neonatal rats with HI and OGD neurons. Besides, silencing AQP4 promoted axonal growth of OGD neurons, and AQP4 knockout notably improved long-term neurobehavioral impairment. Furthermore, GAP43 was found closely correlated with AQP4 via GeneMANIA prediction. Significant downregulation of GAP43 was induced in OGD neurons, while AQP4 knockout markedly upregulated its expression in rats. This indicated that the depletion of AQP4 may enhance axonal regeneration and promote the long-term neurobehavioral recovery associated with the upregulation of GAP43 expression.
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Affiliation(s)
- Qi‐Qin Dan
- National‐Local Joint Engineering Research Center of Translational Medicine of Anesthesiology, West China HospitalSichuan UniversityChengduChina
| | - Zheng Ma
- National‐Local Joint Engineering Research Center of Translational Medicine of Anesthesiology, West China HospitalSichuan UniversityChengduChina
| | - Ya‐Xin Tan
- National‐Local Joint Engineering Research Center of Translational Medicine of Anesthesiology, West China HospitalSichuan UniversityChengduChina
| | - Belegu Visar
- Center for Epigenetics and Induced Pluripotent Stem Cells, Kennedy Krieger InstituteJohns Hopkins UniversityBaltimoreUSA
| | - Li Chen
- National‐Local Joint Engineering Research Center of Translational Medicine of Anesthesiology, West China HospitalSichuan UniversityChengduChina
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2
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P2X7 Receptors in Astrocytes: A Switch for Ischemic Tolerance. MOLECULES (BASEL, SWITZERLAND) 2022; 27:molecules27123655. [PMID: 35744780 PMCID: PMC9228417 DOI: 10.3390/molecules27123655] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/18/2022] [Revised: 06/02/2022] [Accepted: 06/03/2022] [Indexed: 11/17/2022]
Abstract
A sub-lethal ischemic episode (preconditioning [PC]) protects neurons against a subsequent lethal ischemic injury. This phenomenon is known as ischemic tolerance. PC itself does not cause brain damage, but affects glial responses, especially astrocytes, and transforms them into an ischemia-resistant phenotype. P2X7 receptors (P2X7Rs) in astrocytes play essential roles in PC. Although P2X7Rs trigger inflammatory and toxic responses, PC-induced P2X7Rs in astrocytes function as a switch to protect the brain against ischemia. In this review, we focus on P2X7Rs and summarize recent developments on how astrocytes control P2X7Rs and what molecular mechanisms they use to induce ischemic tolerance.
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Lee YC, Kao ST, Cheng CY. Acorus tatarinowii Schott extract reduces cerebral edema caused by ischemia-reperfusion injury in rats: involvement in regulation of astrocytic NKCC1/AQP4 and JNK/iNOS-mediated signaling. BMC Complement Med Ther 2020; 20:374. [PMID: 33298024 PMCID: PMC7726880 DOI: 10.1186/s12906-020-03168-z] [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: 03/31/2020] [Accepted: 11/26/2020] [Indexed: 12/13/2022] Open
Abstract
Background This study aimed to evaluate the effects of the Acorus tatarinowii Schott [Shi Chang Pu (SCP)] extract administered at the start of 2 h of middle cerebral artery occlusion (MCAo), followed by 3 d of reperfusion, and to determine mechanisms involved in anti-edema effects in the penumbra of the cerebral cortex. Method Rats were intraperitoneally administered the SCP extract at a dose of 0.25 g/kg (SCP-0.25 g), 0.5 g/kg (SCP-0.5 g), or 1 g/kg (SCP-1 g) at the start of MCAo. Result SCP-0.5 g and SCP-1 g treatments effectively reduced the cerebral infarct size, ameliorated cerebral edema, reduced blood–brain barrier permeability, and restored neurological function. SCP-0.5 g and SCP-1 g treatments markedly downregulated the levels of glial fibrillary acidic protein, Na+-K+-2Cl− cotransporter type 1 (NKCC1), aquaporin 4 (AQP4), phospho-c-Jun N-terminal kinase (p-JNK)/JNK, inducible nitric oxide synthase (iNOS), 3-nitrotyrosine, intercellular adhesion molecule-1 (ICAM-1), matrix metalloproteinase-9 (MMP-9), vascular endothelial growth factor-A (VEGF-A), and zonula occluden-1 (ZO-1) and upregulated ZO-3 expression in the penumbra of the cerebral cortex 3 d after reperfusion. Conclusions SCP-0.5 g and SCP-1 g treatments exert neuroprotective effects against cerebral infarction and cerebral edema partially by mitigating astrocytic swelling and blood–brain barrier disruption. Moreover, the anti-cerebral edema effects of SCP extract treatments are possibly associated with the downregulation of astrocytic NKCC1/AQP4 and JNK/iNOS-mediated ICAM-1/MMP-9 signaling in the penumbra of the cerebral cortex 3 d after reperfusion.
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Affiliation(s)
- Yu-Chen Lee
- Graduate Institute of Acupuncture Science, China Medical University, Taichung, 40402, Taiwan.,Department of Chinese Medicine, China Medical University Hospital 40447, Taichung, Taiwan.,Research Center for Chinese Medicine & Acupuncture, China Medical University, Taichung, 40402, Taiwan
| | - Shung-Te Kao
- School of Chinese Medicine, College of Chinese Medicine, China Medical University, Taichung, 40402, Taiwan
| | - Chin-Yi Cheng
- School of Post-baccalaureate Chinese Medicine, College of Chinese Medicine, China Medical University, Taichung, 40402, Taiwan. .,Department of Chinese Medicine, Hui-Sheng Hospital 42056, Taichung, Taiwan.
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4
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Lana D, Ugolini F, Giovannini MG. An Overview on the Differential Interplay Among Neurons-Astrocytes-Microglia in CA1 and CA3 Hippocampus in Hypoxia/Ischemia. Front Cell Neurosci 2020; 14:585833. [PMID: 33262692 PMCID: PMC7686560 DOI: 10.3389/fncel.2020.585833] [Citation(s) in RCA: 43] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2020] [Accepted: 10/09/2020] [Indexed: 12/13/2022] Open
Abstract
Neurons have been long regarded as the basic functional cells of the brain, whereas astrocytes and microglia have been regarded only as elements of support. However, proper intercommunication among neurons-astrocytes-microglia is of fundamental importance for the functional organization of the brain. Perturbation in the regulation of brain energy metabolism not only in neurons but also in astrocytes and microglia may be one of the pathophysiological mechanisms of neurodegeneration, especially in hypoxia/ischemia. Glial activation has long been considered detrimental for survival of neurons, but recently it appears that glial responses to an insult are not equal but vary in different brain areas. In this review, we first take into consideration the modifications of the vascular unit of the glymphatic system and glial metabolism in hypoxic conditions. Using the method of triple-labeling fluorescent immunohistochemistry coupled with confocal microscopy (TIC), we recently studied the interplay among neurons, astrocytes, and microglia in chronic brain hypoperfusion. We evaluated the quantitative and morpho-functional alterations of the neuron-astrocyte-microglia triads comparing the hippocampal CA1 area, more vulnerable to ischemia, to the CA3 area, less vulnerable. In these contiguous and interconnected areas, in the same experimental hypoxic conditions, astrocytes and microglia show differential, finely regulated, region-specific reactivities. In both areas, astrocytes and microglia form triad clusters with apoptotic, degenerating neurons. In the neuron-astrocyte-microglia triads, the cell body of a damaged neuron is infiltrated and bisected by branches of astrocyte that create a microscar around it while a microglial cell phagocytoses the damaged neuron. These coordinated actions are consistent with the scavenging and protective activities of microglia. In hypoxia, the neuron-astrocyte-microglia triads are more numerous in CA3 than in CA1, further indicating their protective effects. These data, taken from contiguous and interconnected hippocampal areas, demonstrate that glial response to the same hypoxic insult is not equal but varies significantly. Understanding the differences of glial reactivity is of great interest to explain the differential susceptibility of hippocampal areas to hypoxia/ischemia. Further studies may evidence the differential reactivity of glia in different brain areas, explaining the higher or lower sensitivity of these areas to different insults and whether glia may represent a target for future therapeutic interventions.
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Affiliation(s)
- Daniele Lana
- Department of Health Sciences, Section of Clinical Pharmacology and Oncology, University of Florence, Florence, Italy
| | - Filippo Ugolini
- Department of Health Sciences, Section of Anatomopathology, University of Florence, Florence, Italy
| | - Maria G Giovannini
- Department of Health Sciences, Section of Clinical Pharmacology and Oncology, University of Florence, Florence, Italy
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5
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Skowrońska K, Obara-Michlewska M, Czarnecka A, Dąbrowska K, Zielińska M, Albrecht J. Persistent Overexposure to N-Methyl-D-Aspartate (NMDA) Calcium-Dependently Downregulates Glutamine Synthetase, Aquaporin 4, and Kir4.1 Channel in Mouse Cortical Astrocytes. Neurotox Res 2018; 35:271-280. [PMID: 30220059 PMCID: PMC6313349 DOI: 10.1007/s12640-018-9958-3] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2017] [Revised: 08/31/2018] [Accepted: 09/07/2018] [Indexed: 11/25/2022]
Abstract
Astrocytes express N-methyl-d-aspartate (NMDA) receptor (NMDAR) but its functions in these cells are not well defined. This study shows that the sustained exposure (8–72 h) of mouse astrocytes to NMDA decreases the expression of the functional astroglia-specific proteins, glutamine synthetase (GS), and the water channel protein aquaporin-4 (AQP4) and also reduces GS activity. Similar to rat astrocytes (Obara-Michlewska et al. Neurochem Int 88:20–25, 2015), the exposure of mouse astrocytes to NMDA also decreased the expression of the inward rectifying potassium channel Kir4.1. NMDA failed to elicit the effects in those cells incubated in the absence of Ca2+ and in those in which the GluN1 subunit of the NMDAR was silenced with GluN1 siRNA. The downregulation of GS, AQP4, and Kir4.1 observed in vitro may reflect NMDAR-mediated alterations of astrocytic functions noted in central nervous system pathologies associated with increased glutamate (Glu) release and excitotoxic tissue damage.
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Affiliation(s)
- Katarzyna Skowrońska
- Department of Neurotoxicology, Mossakowski Medical Research Centre, Polish Academy of Sciences, Pawińskiego St. 5, 02-106, Warsaw, Poland
| | - Marta Obara-Michlewska
- Department of Neurotoxicology, Mossakowski Medical Research Centre, Polish Academy of Sciences, Pawińskiego St. 5, 02-106, Warsaw, Poland
| | - Anna Czarnecka
- Department of Neurotoxicology, Mossakowski Medical Research Centre, Polish Academy of Sciences, Pawińskiego St. 5, 02-106, Warsaw, Poland
| | - Katarzyna Dąbrowska
- Department of Neurotoxicology, Mossakowski Medical Research Centre, Polish Academy of Sciences, Pawińskiego St. 5, 02-106, Warsaw, Poland
| | - Magdalena Zielińska
- Department of Neurotoxicology, Mossakowski Medical Research Centre, Polish Academy of Sciences, Pawińskiego St. 5, 02-106, Warsaw, Poland
| | - Jan Albrecht
- Department of Neurotoxicology, Mossakowski Medical Research Centre, Polish Academy of Sciences, Pawińskiego St. 5, 02-106, Warsaw, Poland.
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Cheng ZJ, Dai TM, Shen YY, He JL, Li J, Tu JL. Atorvastatin Pretreatment Attenuates Ischemic Brain Edema by Suppressing Aquaporin 4. J Stroke Cerebrovasc Dis 2018; 27:3247-3255. [PMID: 30093197 DOI: 10.1016/j.jstrokecerebrovasdis.2018.07.011] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2018] [Revised: 07/01/2018] [Accepted: 07/05/2018] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND Cerebral edema, a serious complication of acute cerebral infarction, has a crucial impact on morbidity and mortality in the early stage of cerebral infarction. And aquaporin 4 (AQP4), a bidirectional water transporting protein, plays a pivotal role in edema formation. At experimental model, it has proven that atorvastatin could exert pleiotropic neuroprotection on acute cerebral infarction independent of its cholesterol-lowering action. It was a common protective manifestation that atorvastatin can reduce the infarct volume and cerebral edema. However, little is known about atorvastatin improving ischemic brain edema by regulating AQP4 expression. This study intended to investigate the neuroprotection effects of atorvastatin pretreatment in rats with cerebral ischemia and further explore the potential relationship between atorvastatin and AQP4 expression. METHODS Fifty-one adult male Sprague Dawley rats were randomly divided into 3 groups: sham, middle cerebral artery occlusion (MCAO), and atorvastatin pretreatment (Ator) group. For Ator group, 20 mg/kg of atorvastatin injectable suspension was administered once for 7days by gavage before operation, whereas the others were administered the same volume of saline matching. Except for sham group, MCAO and Ator groups were subjected to permanent MCAO by modified intraluminal suture method. Infarct volume, neurological deficit, brain water content (BWC), immunohistochemistry, western blot, and polymerase chain reaction (PCR) were measured at 24 hours after MCAO. RESULTS Compared with sham group, the mNSS, infarct volume, and BWC of ischemic hemisphere were significantly increased (P < 0.001) in MCAO group. Positive cells and protein levels of p-p38MAPK and AQP4 in peri-infarction were significantly increased (P < 0.01). The mRNA levels of p38MAPK and AQP4 were also prominently upregulated (P < 0.01). Interestingly, preadministration of atorvastatin dramatically decreased infarct volume and the BWC of ischemic hemisphere compared with MCAO group (P < 0.05). The overexpressions of p-p38MAPK and AQP4 in peri-infarction were significantly decreased (P < 0.05) and their mRNA levels were downregulated by atorvastatin pretreatment (P < 0.05). Neurological deficits were also dramatically improved (P < 0.001). CONCLUSION To the best of our knowledge, this is the first study that demonstrates an effect of atorvastatin on expression of AQP4, and we propose that decreased AQP4 expression through a p38MAPK-suppression pathway may be the mechanism of atorvastatin alleviating ischemic cerebral edema.
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Affiliation(s)
- Zhi-Juan Cheng
- Department of Neurology, The Second Affiliated Hospital of Nanchang University, China.
| | - Ting-Min Dai
- Department of Neurology, Affiliated Hospital of Jiujiang University, China.
| | - Yao-Yao Shen
- Department of Neurology, Affiliated Hospital of Jiujiang University, China.
| | - Jian-Le He
- Department of Neurology, The Second Affiliated Hospital of Nanchang University, China.
| | - Juan Li
- Department of Neurology, The Second Affiliated Hospital of Nanchang University, China.
| | - Jiang-Long Tu
- Department of Neurology, The Second Affiliated Hospital of Nanchang University, China.
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7
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Koizumi S, Hirayama Y, Morizawa YM. New roles of reactive astrocytes in the brain; an organizer of cerebral ischemia. Neurochem Int 2018; 119:107-114. [PMID: 29360494 DOI: 10.1016/j.neuint.2018.01.007] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2017] [Revised: 12/18/2017] [Accepted: 01/16/2018] [Indexed: 01/16/2023]
Abstract
The brain consists of neurons and much higher number of glial cells. They communicate each other, by which they control brain functions. The brain is highly vulnerable to several insults such as ischemia, but has a self-protective and self-repairing mechanisms against these. Ischemic tolerance or preconditioning is an endogenous neuroprotective phenomenon, where a mild non-lethal ischemic episode can induce resistance to a subsequent severe ischemic injury in the brain. Because of its neuroprotective effects against cerebral ischemia or stroke, ischemic tolerance has been widely studied. However, almost all studies have been performed from the viewpoint of neurons. Glial cells are structurally in close association with synapses. Recent studies have uncovered the active roles of astrocytes in modulating synaptic connectivity, such as synapse formation, elimination and maturation, during development or pathology. However, glia-mediated ischemic tolerance and/or neuronal repairing have received only limited attention. We and others have demonstrated that glial cells, especially astrocytes, play a pivotal role in regulation of induction of ischemic tolerance as well as repairing/remodeling of neuronal networks by phagocytosis. Here, we review our current understanding of (1) glial-mediated ischemic tolerance and (2) glia-mediated repairing/remodeling of the penumbra neuronal networks, and highlight their mechanisms as well as their potential benefits, problems, and therapeutic application.
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Affiliation(s)
- Schuichi Koizumi
- Department of Neuropharmacology, Interdisciplinary Graduate School of Medicine, University of Yamanashi, 1110 Shimokato, Chuo, Yamanashi 409-3898, Japan.
| | - Yuri Hirayama
- Department of Neuropharmacology, Interdisciplinary Graduate School of Medicine, University of Yamanashi, 1110 Shimokato, Chuo, Yamanashi 409-3898, Japan
| | - Yosuke M Morizawa
- Department of Neuropharmacology, Interdisciplinary Graduate School of Medicine, University of Yamanashi, 1110 Shimokato, Chuo, Yamanashi 409-3898, Japan
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8
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Mann AP, Scodeller P, Hussain S, Braun GB, Mölder T, Toome K, Ambasudhan R, Teesalu T, Lipton SA, Ruoslahti E. Identification of a peptide recognizing cerebrovascular changes in mouse models of Alzheimer's disease. Nat Commun 2017; 8:1403. [PMID: 29123083 PMCID: PMC5680235 DOI: 10.1038/s41467-017-01096-0] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2016] [Accepted: 08/17/2017] [Indexed: 01/02/2023] Open
Abstract
Cerebrovascular changes occur in Alzheimer’s disease (AD). Using in vivo phage display, we searched for molecular markers of the neurovascular unit, including endothelial cells and astrocytes, in mouse models of AD. We identified a cyclic peptide, CDAGRKQKC (DAG), that accumulates in the hippocampus of hAPP-J20 mice at different ages. Intravenously injected DAG peptide homes to neurovascular unit endothelial cells and to reactive astrocytes in mouse models of AD. We identified connective tissue growth factor (CTGF), a matricellular protein that is highly expressed in the brain of individuals with AD and in mouse models, as the target of the DAG peptide. We also showed that exogenously delivered DAG homes to the brain in mouse models of glioblastoma, traumatic brain injury, and Parkinson’s disease. DAG may potentially be used as a tool to enhance delivery of therapeutics and imaging agents to sites of vascular changes and astrogliosis in diseases associated with neuroinflammation. Cerebrovascular changes and astrogliosis occur in Alzheimer’s disease (AD). Using an in vivo phage display technique, the authors identified a peptide that upon systematic administration, can home to brain endothelial cells and astrocytes in mouse models of AD at the early stages of the disease.
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Affiliation(s)
- Aman P Mann
- Cancer Research Center, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA, 92037, USA
| | - Pablo Scodeller
- Cancer Research Center, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA, 92037, USA.,Laboratory of Cancer Biology, Institute of Biomedicine and Translational Medicine, University of Tartu, Tartu, 50411, Estonia
| | - Sazid Hussain
- Cancer Research Center, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA, 92037, USA.,AivoCode Inc., La Jolla, CA, 92037, USA
| | - Gary B Braun
- Cancer Research Center, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA, 92037, USA
| | - Tarmo Mölder
- Laboratory of Cancer Biology, Institute of Biomedicine and Translational Medicine, University of Tartu, Tartu, 50411, Estonia
| | - Kadri Toome
- Laboratory of Cancer Biology, Institute of Biomedicine and Translational Medicine, University of Tartu, Tartu, 50411, Estonia
| | - Rajesh Ambasudhan
- Neurodegenerative Disease Center, Scintillon Institute, San Diego, CA, 92121, USA
| | - Tambet Teesalu
- Laboratory of Cancer Biology, Institute of Biomedicine and Translational Medicine, University of Tartu, Tartu, 50411, Estonia
| | - Stuart A Lipton
- Neurodegenerative Disease Center, Scintillon Institute, San Diego, CA, 92121, USA.,Department of Neurosciences, University of California, San Diego, School of Medicine, La Jolla, CA, 92093, USA
| | - Erkki Ruoslahti
- Cancer Research Center, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA, 92037, USA. .,Center for Nanomedicine and Department of Cell, Molecular and Developmental Biology, University of California, Santa Barbara, Santa Barbara, CA, 93106, USA.
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9
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Hirt L, Price M, Mastour N, Brunet JF, Barrière G, Friscourt F, Badaut J. Increase of aquaporin 9 expression in astrocytes participates in astrogliosis. J Neurosci Res 2017; 96:194-206. [PMID: 28419510 DOI: 10.1002/jnr.24061] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2016] [Revised: 03/10/2017] [Accepted: 03/10/2017] [Indexed: 01/01/2023]
Abstract
Here we assess the potential functional role of increased aquaporin 9 (APQ9) in astrocytes. Increased AQP9 expression was achieved in primary astrocyte cultures by transfection of a plasmid-containing green fluorescent protein fused to either wild-type or mutated human AQP9. Increased AQP9 expression and phosphorylation at Ser222 were associated with a significant change in astrocyte morphology, mainly with a higher number of processes. Similar phenotypic changes are observed in astrogliosis processes after injury. In parallel, we observed that in vivo, thrombin preconditioning before ischemic stroke induced an early increase in AQP9 expression in the male mouse brain. This increased AQP9 expression was also associated with astrocyte morphological changes, especially in the white matter tract. Astrocyte reactivity is debated as being either beneficial or deleterious. As thrombin preconditioning leads to a decrease in lesion size after stroke, our data suggest that the early increase in AQP9 concomitant with astrocyte reactivity leads to a beneficial effect. © 2017 Wiley Periodicals, Inc.
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Affiliation(s)
- Lorenz Hirt
- Neurology Department, Centre Hospitalier Universitaire Vaudois and University of Lausanne, Lausanne, Switzerland
| | - Melanie Price
- Neurology Department, Centre Hospitalier Universitaire Vaudois and University of Lausanne, Lausanne, Switzerland
| | - Nabil Mastour
- Neurosurgery Research Group, Centre Hospitalier Universitaire Vaudois and University of Lausanne, Lausanne, Switzerland
| | - Jean-François Brunet
- Neurosurgery Research Group, Centre Hospitalier Universitaire Vaudois and University of Lausanne, Lausanne, Switzerland
| | | | | | - Jerome Badaut
- CNRS UMR 5287, INCIA, University of Bordeaux, Bordeaux, France
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10
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Ma L, Guan L, Ding JN, Geng X. Current AQP research: therapeutic approaches to ischemic and hemorrhagic stroke. Neural Regen Res 2017; 11:1918-1919. [PMID: 28197182 PMCID: PMC5270424 DOI: 10.4103/1673-5374.197128] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Affiliation(s)
- Linlin Ma
- China-America Institute of Neuroscience, Beijing Luhe Hospital, Capital Medical University, Beijing, China; Department of Neurology, Beijing Luhe Hospital, Capital Medical University, Beijing, China
| | - Longfei Guan
- China-America Institute of Neuroscience, Beijing Luhe Hospital, Capital Medical University, Beijing, China
| | - Jessie N Ding
- Department of Neurosurgery, Wayne State University School of Medicine, Detroit, MI, USA
| | - Xiaokun Geng
- China-America Institute of Neuroscience, Beijing Luhe Hospital, Capital Medical University, Beijing, China; Department of Neurology, Beijing Luhe Hospital, Capital Medical University, Beijing, China; Department of Neurosurgery, Wayne State University School of Medicine, Detroit, MI, USA
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11
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Progress in AQP Research and New Developments in Therapeutic Approaches to Ischemic and Hemorrhagic Stroke. Int J Mol Sci 2016; 17:ijms17071146. [PMID: 27438832 PMCID: PMC4964519 DOI: 10.3390/ijms17071146] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2016] [Revised: 07/06/2016] [Accepted: 07/07/2016] [Indexed: 11/17/2022] Open
Abstract
Cerebral edema often manifests after the development of cerebrovascular disease, particularly in the case of stroke, both ischemic and hemorrhagic. Without clinical intervention, the influx of water into brain tissues leads to increased intracranial pressure, cerebral herniation, and ultimately death. Strategies to manage the development of edema constitute a major unmet therapeutic need. However, despite its major clinical significance, the mechanisms underlying cerebral water transport and edema formation remain elusive. Aquaporins (AQPs) are a class of water channel proteins which have been implicated in the regulation of water homeostasis and cerebral edema formation, and thus represent a promising target for alleviating stroke-induced cerebral edema. This review examines the significance of relevant AQPs in stroke injury and subsequently explores neuroprotective strategies aimed at modulating AQP expression, with a particular focus on AQP4, the most abundant AQP in the central nervous system.
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12
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Hoshi A, Tsunoda A, Yamamoto T, Tada M, Kakita A, Ugawa Y. Increased neuronal and astroglial aquaporin-1 immunoreactivity in rat striatum by chemical preconditioning with 3-nitropropionic acid. Neurosci Lett 2016; 626:48-53. [PMID: 27181510 DOI: 10.1016/j.neulet.2016.05.021] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2016] [Revised: 05/11/2016] [Accepted: 05/11/2016] [Indexed: 02/06/2023]
Abstract
Aquaporin-1 (AQP1) is a water channel expressed in the choroid plexus and participates in forming cerebrospinal fluid. Interestingly, reactive astrocytes also express AQP1 in the central nervous system under some pathological conditions. On the other hand, 3-nitropropionic acid (3NP) is a mitochondrial toxin that causes selective degeneration of striatum; however, its chemical preconditioning is neuroprotective against cerebral ischemia. We previously reported that mild 3NP application is accompanied with numerous reactive astrocytes in rat striatum devoid of typical necrotic lesions. Therefore, we studied whether AQP1 in the rat striatum could be upregulated with reactive astrocytosis using the 3NP model. Immunohistochemical or immunofluorescence analysis showed that reactive astrocytosis in the striatum, which upregulates glial fibrillary acidic protein and glutamine synthetase, was induced by mild doses of 3NP administration. Intriguingly, after 3NP treatment, AQP1 was intensely expressed not only by the subpopulation of astroglia but also by neurons. The AQP1 immunoreactivity became more intensified at the early-subtoxic stage (ES: 24-48h), but not as much in the delayed-subtoxic stage (DS: 96-120h). In contrast, AQP4 expression in the striatum was downregulated after 3NP treatment, in particular during the ES stage. AQP1 upregulation/AQP4 downregulation induced under subtoxic 3NP treatment may play a pivotal role in water homeostasis and cell viability in the striatum.
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Affiliation(s)
- Akihiko Hoshi
- Department of Neurology, Fukushima Medical University, Fukushima, Japan.
| | - Ayako Tsunoda
- Department of Neurology, Fukushima Medical University, Fukushima, Japan
| | - Teiji Yamamoto
- Department of Neurology, Fukushima Medical University, Fukushima, Japan
| | - Mari Tada
- Department of Pathology, Brain Research Institute, University of Niigata, Niigata, Japan
| | - Akiyoshi Kakita
- Department of Pathology, Brain Research Institute, University of Niigata, Niigata, Japan
| | - Yoshikazu Ugawa
- Department of Neurology, Fukushima Medical University, Fukushima, Japan
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Pathogenesis of brain edema and investigation into anti-edema drugs. Int J Mol Sci 2015; 16:9949-75. [PMID: 25941935 PMCID: PMC4463627 DOI: 10.3390/ijms16059949] [Citation(s) in RCA: 196] [Impact Index Per Article: 21.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2015] [Revised: 04/15/2015] [Accepted: 04/27/2015] [Indexed: 12/18/2022] Open
Abstract
Brain edema is a potentially fatal pathological state that occurs after brain injuries such as stroke and head trauma. In the edematous brain, excess accumulation of extracellular fluid results in elevation of intracranial pressure, leading to impaired nerve function. Despite the seriousness of brain edema, only symptomatic treatments to remove edema fluid are currently available. Thus, the development of novel anti-edema drugs is required. The pathogenesis of brain edema is classified as vasogenic or cytotoxic edema. Vasogenic edema is defined as extracellular accumulation of fluid resulting from disruption of the blood-brain barrier (BBB) and extravasations of serum proteins, while cytotoxic edema is characterized by cell swelling caused by intracellular accumulation of fluid. Various experimental animal models are often used to investigate mechanisms underlying brain edema. Many soluble factors and functional molecules have been confirmed to induce BBB disruption or cell swelling and drugs targeted to these factors are expected to have anti-edema effects. In this review, we discuss the mechanisms and involvement of factors that induce brain edema formation, and the possibility of anti-edema drugs targeting them.
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Vella J, Zammit C, Di Giovanni G, Muscat R, Valentino M. The central role of aquaporins in the pathophysiology of ischemic stroke. Front Cell Neurosci 2015; 9:108. [PMID: 25904843 PMCID: PMC4389728 DOI: 10.3389/fncel.2015.00108] [Citation(s) in RCA: 84] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2015] [Accepted: 04/10/2015] [Indexed: 11/16/2022] Open
Abstract
Stroke is a complex and devastating neurological condition with limited treatment options. Brain edema is a serious complication of stroke. Early edema formation can significantly contribute to infarct formation and thus represents a promising target. Aquaporin (AQP) water channels contribute to water homeostasis by regulating water transport and are implicated in several disease pathways. At least 7 AQP subtypes have been identified in the rodent brain and the use of transgenic mice has greatly aided our understanding of their functions. AQP4, the most abundant channel in the brain, is up-regulated around the peri-infarct border in transient cerebral ischemia and AQP4 knockout mice demonstrate significantly reduced cerebral edema and improved neurological outcome. In models of vasogenic edema, brain swelling is more pronounced in AQP4-null mice than wild-type providing strong evidence of the dual role of AQP4 in the formation and resolution of both vasogenic and cytotoxic edema. AQP4 is co-localized with inwardly rectifying K(+)-channels (Kir4.1) and glial K(+) uptake is attenuated in AQP4 knockout mice compared to wild-type, indicating some form of functional interaction. AQP4-null mice also exhibit a reduction in calcium signaling, suggesting that this channel may also be involved in triggering pathological downstream signaling events. Associations with the gap junction protein Cx43 possibly recapitulate its role in edema dissipation within the astroglial syncytium. Other roles ascribed to AQP4 include facilitation of astrocyte migration, glial scar formation, modulation of inflammation and signaling functions. Treatment of ischemic cerebral edema is based on the various mechanisms in which fluid content in different brain compartments can be modified. The identification of modulators and inhibitors of AQP4 offer new therapeutic avenues in the hope of reducing the extent of morbidity and mortality in stroke.
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Affiliation(s)
| | | | | | | | - Mario Valentino
- Department of Physiology and Biochemistry, University of MaltaMsida, Malta
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Zhang YB, Wang X, Meister EA, Gong KR, Yan SC, Lu GW, Ji XM, Shao G. The effects of CoCl2 on HIF-1α protein under experimental conditions of autoprogressive hypoxia using mouse models. Int J Mol Sci 2014; 15:10999-1012. [PMID: 24945310 PMCID: PMC4100194 DOI: 10.3390/ijms150610999] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2014] [Revised: 06/10/2014] [Accepted: 06/11/2014] [Indexed: 12/22/2022] Open
Abstract
It is well known that cobalt chloride (CoCl2) can enhance the stability of hypoxia-inducible factor (HIF)-1α. The aim of this study is to detect the effect of CoCl2 on the hypoxia tolerance of mice which were repeatedly exposed to autoprogressive hypoxia. Balb/c mice were randomly divided into groups of chemical pretreatment and normal saline (NS), respectively injected with CoCl2 and NS 3 h before exposure to hypoxia for 0 run (H0), 1 run (H1), and 4 runs (H4). Western Blot, electrophoretic mobility shift assay (EMSA), extracellular recordings population spikes in area cornus ammonis I (CA 1) of mouse hippocampal slices and real-time were used in this study. Our results demonstrated that the tolerance of mice to hypoxia, the changes of HIF-1α protein level and HIF-1 DNA binding activity in mice hippocampus, the mRNA level of erythropoietin (EPO) and vascular endothelial growth factor (VEGF), and the disappearance time of population spikes of hippocampal slices were substantially different between the control group and the CoCl2 group. Over-induction of HIF-1α by pretreatment with CoCl2 before hypoxia did not increase the hypoxia tolerance.
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Affiliation(s)
- Yan-Bo Zhang
- Department of Neurology, Affiliated Hospital of Tai Shan Medical University, Taishan 271000, China.
| | - Xiulian Wang
- Department of Intensive Care Unit , 2nd Affiliated Hospital of Baotou Medical College, Baotou 014030, China.
| | - Edward A Meister
- Department of Medicine, University of Arizona, Tucson, AZ 85721, USA.
| | - Ke-Rui Gong
- Biomedicine Research Center and Basic Medical College, Baotou Medical College, Baotou 014060, China.
| | - Shao-Chun Yan
- Biomedicine Research Center and Basic Medical College, Baotou Medical College, Baotou 014060, China.
| | - Guo-Wei Lu
- Institute for Hypoxia Medicine, Xuanwu Hospital of Capital Medical University, Beijing 10054, China.
| | - Xun-Ming Ji
- Institute for Hypoxia Medicine, Xuanwu Hospital of Capital Medical University, Beijing 10054, China.
| | - Guo Shao
- Biomedicine Research Center and Basic Medical College, Baotou Medical College, Baotou 014060, China.
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He Z, Wang X, Wu Y, Jia J, Hu Y, Yang X, Li J, Fan M, Zhang L, Guo J, Leung MCP. Treadmill pre-training ameliorates brain edema in ischemic stroke via down-regulation of aquaporin-4: an MRI study in rats. PLoS One 2014; 9:e84602. [PMID: 24416250 PMCID: PMC3886991 DOI: 10.1371/journal.pone.0084602] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2013] [Accepted: 11/15/2013] [Indexed: 01/23/2023] Open
Abstract
Objective Treadmill pre-training can ameliorate blood brain barrier (BBB) dysfunction in ischemia-reperfusion injury, however, its role in ischemic brain edema remains unclear. This study assessed the neuroprotective effects induced by treadmill pre-training, particularly on brain edema in transient middle cerebral artery occluded model. Methods Transient middle cerebral artery occlusion to induce stroke was performed on rats after 2 weeks of treadmill pre-training. Magnetic resonance imaging (MRI) was used to evaluate the dynamic impairment of cerebral edema after ischemia-reperfusion injury. In addition, measurements of wet and dry brain weight, Evans Blue assay and Garcia scores were performed to investigate the cerebral water content, BBB permeability and neurologic deficit, respectively. Moreover, during ischemia-reperfusion injury, the expression of Aquaporin 4 (AQP4) was detected using immunofluorescence and Western bloting analyses. Results Treadmill pre-training improved the relative apparent diffusion coefficient (rADC) loss in the ipsilateral cortex and striatum at 1 hour and 2.5 hours after cerebral ischemia. In the treadmill pre-training group, T2W1 values of the ipsilateral cortex and striatum increased less at 7.5 hours, 1 day, and 2 days after stroke while the brain water content decreased at 2 days after ischemia. Regarding the BBB permeability, the semi-quantitative amount of contrast agent leakage of treadmill pre-training group significantly decreased. Less Evans Blue exudation was also observed in treadmill pre-training group at 2 days after stroke. In addition, treadmill pre-training mitigated the Garcia score deficits at 2 days after stroke. Immunofluorescence staining and Western blotting results showed a significant decrease in the expression of AQP4 after treadmill ischemia following pre-training. Conclusions Treadmill pre-training may reduce cerebral edema and BBB dysfunction during cerebral ischemia/reperfusion injury via the down-regulation of AQP4.
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Affiliation(s)
- Zhijie He
- Department of Rehabilitation, Huashan Hospital, Fudan University, Shanghai, China
| | - Xiaolou Wang
- Department of Rehabilitation, Huashan Hospital, Fudan University, Shanghai, China
| | - Yi Wu
- Department of Rehabilitation, Huashan Hospital, Fudan University, Shanghai, China
| | - Jie Jia
- Department of Rehabilitation, Huashan Hospital, Fudan University, Shanghai, China
- * E-mail: (JJ); (JG)
| | - Yongshan Hu
- Department of Rehabilitation, Huashan Hospital, Fudan University, Shanghai, China
- State Key Laboratory of Medical Neurobiology, Shanghai Medical College, Fudan University, Shanghai, China
| | - Xiaojiao Yang
- Department of Rehabilitation, Huashan Hospital, Fudan University, Shanghai, China
| | - Jianqi Li
- Shanghai Key Laboratory of Magnetic Resonance, Department of Physics, East China Normal University, Shanghai, China
| | - Mingxia Fan
- Shanghai Key Laboratory of Magnetic Resonance, Department of Physics, East China Normal University, Shanghai, China
| | - Li Zhang
- Department of Rehabilitation, Huashan Hospital, Fudan University, Shanghai, China
| | - Jinchun Guo
- State Key Laboratory of Medical Neurobiology, Shanghai Medical College, Fudan University, Shanghai, China
- * E-mail: (JJ); (JG)
| | - Mason C. P. Leung
- Department of Rehabilitation Sciences, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, SAR, China
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Abstract
Aquaporins are a group of proteins with high-selective permeability for water. A subgroup called aquaglyceroporins is also permeable to glycerol, urea and a few other solutes. Aquaporin function has mainly been studied in the brain, kidney, glands and skeletal muscle, while the information about aquaporins in the heart is still scarce. The current review explores the recent advances in this field, bringing aquaporins into focus in the context of myocardial ischemia, reperfusion, and blood osmolarity disturbances. Since the amount of data on aquaporins in the heart is still limited, examples and comparisons from better-studied areas of aquaporin biology have been used. The human heart expresses aquaporin-1, -3, -4 and -7 at the protein level. The potential roles of aquaporins in the heart are discussed, and some general phenomena that the myocardial aquaporins share with aquaporins in other organs are elaborated. Cardiac aquaporin-1 is mostly distributed in the microvasculature. Its main role is transcellular water flux across the endothelial membranes. Aquaporin-4 is expressed in myocytes, both in cardiac and in skeletal muscle. In addition to water flux, its function is connected to the calcium signaling machinery. It may play a role in ischemia-reperfusion injury. Aquaglyceroporins, especially aquaporin-7, may serve as a novel pathway for nutrient delivery into the heart. They also mediate toxicity of various poisons. Aquaporins cannot influence permeability by gating, therefore, their function is regulated by changes of expression-on the levels of transcription, translation (by microRNAs), post-translational modification, membrane trafficking, ubiquitination and subsequent degradation. Studies using mice genetically deficient for aquaporins have shown rather modest changes in the heart. However, they might still prove to be attractive targets for therapy directed to reduce myocardial edema and injury caused by ischemia and reperfusion.
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Characteristics of aquaporin expression surrounding senile plaques and cerebral amyloid angiopathy in Alzheimer disease. J Neuropathol Exp Neurol 2012; 71:750-9. [PMID: 22805778 DOI: 10.1097/nen.0b013e3182632566] [Citation(s) in RCA: 96] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Senile plaques (SPs) containing amyloid β peptide (Aβ) 1-42 are the major species present in Alzheimer disease (AD), whereas Aβ1-40 is the major constituent of arteriolar walls affected by cerebral amyloid angiopathy. The water channel proteins astrocytic aquaporin 1 (AQP1) and aquaporin 4 (AQP4) are known to be abnormally expressed in AD brains, but the expression of AQPs surrounding SPs and cerebral amyloid angiopathy has not been described in detail. Here, we investigated whether AQP expression is associated with each species of Aβ deposited in human brains affected by either sporadic or familial AD. Immunohistochemical analysis demonstrated more numerous AQP1-positive reactive astrocytes in the AD cerebral cortex than in controls, located close to Aβ42- or Aβ40-positive SPs. In AD cases, however, AQP1-positive astrocytes were not often observed in Aβ-rich areas, and there was a significant negative correlation between the levels of AQP1 and Aβ42 assessed semiquantitatively. We also found that Aβ plaque-like AQP4 was distributed in association with Aβ42- or Aβ40-positive SPs and that the degree of AQP4 expression around Aβ40-positive vessels was variable. These findings suggest that a defined population of AQP1-positive reactive astrocytes may modify Aβ deposition in the AD brain, whereas the Aβ deposition process might alter astrocytic expression of AQP4.
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Reactive gliosis and neuroinflammation in rats with communicating hydrocephalus. Neuroscience 2012; 218:317-25. [DOI: 10.1016/j.neuroscience.2012.05.004] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2012] [Revised: 04/05/2012] [Accepted: 05/03/2012] [Indexed: 02/07/2023]
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6-Hydroxydopamine leads to T2 hyperintensity, decreased claudin-3 immunoreactivity and altered aquaporin 4 expression in the striatum. Behav Brain Res 2012; 232:148-58. [DOI: 10.1016/j.bbr.2012.04.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2012] [Revised: 03/30/2012] [Accepted: 04/03/2012] [Indexed: 11/23/2022]
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Eskandari R, Harris CA, McAllister JP. Reactive astrocytosis in feline neonatal hydrocephalus: acute, chronic, and shunt-induced changes. Childs Nerv Syst 2011; 27:2067-76. [PMID: 21847645 DOI: 10.1007/s00381-011-1552-4] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/14/2011] [Accepted: 07/29/2011] [Indexed: 10/17/2022]
Abstract
PURPOSE Reactive astrocytosis has been implicated in injury and recovery patterns associated with hydrocephalus. To investigate temporal changes in astrogliosis during the early progression of hydrocephalus, after shunting, and after long-term ventriculomegaly, glial fibrillary protein (GFAP) levels were analyzed in a feline model. METHODS Obstructive hydrocephalus was induced in 10-day-old kittens by intracisternal injections of 25% kaolin. Acute non-shunted animals were killed 15 days post-kaolin injection to represent the pre-shunt condition. Shunt-treated animals received ventriculoperitoneal shunts 15 days post-injection and were killed 10 or 60 days later to represent short- and long-term recovery periods. Chronic untreated animals had Ommaya reservoirs implanted 15 days post-kaolin, which were tapped intermittently until they were killed 60 days later. Ventriculomegaly was monitored by neuroimaging before and after shunting and at death. RNA and total protein from primary visual cortex were analyzed by Northern and Western blotting. RESULTS GFAP RNA and protein levels for acute and chronic non-shunted hydrocephalic animals were 77% and 247% (p < 0.01) and 659% (p < 0.05) and 871% (p < 0.05) higher than controls, respectively. Shunted animals with short-term recovery demonstrated a mismatch in GFAP levels, with RNA expression decreasing 26% and protein increasing 335% (p < 0.01). Shunted animals with a long-term recovery exhibited GFAP RNA and protein levels 201% and 357% above normal, respectively. CONCLUSIONS These results indicate that a reactive astrocytic response continues to rise dramatically in chronic hydrocephalus, suggesting ongoing gliosis and potential damage. Shunting partially ameliorates the continuation of astrogliosis, but does not completely reverse this inflammatory reaction even after a long recovery.
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Affiliation(s)
- Ramin Eskandari
- Division of Pediatric Neurosurgery, Department of Neurosurgery, University of Utah, 175 North Medical Drive, Salt Lake City, UT 84132, USA
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22
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Panickar KS, Anderson RA. Effect of polyphenols on oxidative stress and mitochondrial dysfunction in neuronal death and brain edema in cerebral ischemia. Int J Mol Sci 2011; 12:8181-207. [PMID: 22174658 PMCID: PMC3233464 DOI: 10.3390/ijms12118181] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2011] [Revised: 10/18/2011] [Accepted: 11/14/2011] [Indexed: 01/15/2023] Open
Abstract
Polyphenols are natural substances with variable phenolic structures and are elevated in vegetables, fruits, grains, bark, roots, tea, and wine. There are over 8000 polyphenolic structures identified in plants, but edible plants contain only several hundred polyphenolic structures. In addition to their well-known antioxidant effects, select polyphenols also have insulin-potentiating, anti-inflammatory, anti-carcinogenic, anti-viral, anti-ulcer, and anti-apoptotic properties. One important consequence of ischemia is neuronal death and oxidative stress plays a key role in neuronal viability. In addition, neuronal death may be initiated by the activation of mitochondria-associated cell death pathways. Another consequence of ischemia that is possibly mediated by oxidative stress and mitochondrial dysfunction is glial swelling, a component of cytotoxic brain edema. The purpose of this article is to review the current literature on the contribution of oxidative stress and mitochondrial dysfunction to neuronal death, cell swelling, and brain edema in ischemia. A review of currently known mechanisms underlying neuronal death and edema/cell swelling will be undertaken and the potential of dietary polyphenols to reduce such neural damage will be critically reviewed.
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Affiliation(s)
- Kiran S Panickar
- Diet, Genomics, & Immunology Laboratory, Beltsville Human Nutrition Research Center, Agricultural Research Service, United States Department of Agriculture, Beltsville, MD 20705, USA; E-Mail:
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Zlokovic BV. Neurovascular pathways to neurodegeneration in Alzheimer's disease and other disorders. Nat Rev Neurosci 2011; 12:723-38. [PMID: 22048062 DOI: 10.1038/nrn3114] [Citation(s) in RCA: 2008] [Impact Index Per Article: 154.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The neurovascular unit (NVU) comprises brain endothelial cells, pericytes or vascular smooth muscle cells, glia and neurons. The NVU controls blood-brain barrier (BBB) permeability and cerebral blood flow, and maintains the chemical composition of the neuronal 'milieu', which is required for proper functioning of neuronal circuits. Recent evidence indicates that BBB dysfunction is associated with the accumulation of several vasculotoxic and neurotoxic molecules within brain parenchyma, a reduction in cerebral blood flow, and hypoxia. Together, these vascular-derived insults might initiate and/or contribute to neuronal degeneration. This article examines mechanisms of BBB dysfunction in neurodegenerative disorders, notably Alzheimer's disease, and highlights therapeutic opportunities relating to these neurovascular deficits.
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Affiliation(s)
- Berislav V Zlokovic
- Department of Physiology and Biophysics, and Center for Neurodegeneration and Regeneration at the Zilkha Neurogenetic Institute, University of Southern California, Keck School of Medicine, 1501 San Pablo Street, Los Angeles, California 90089, USA.
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Pre-conditioning induces the precocious differentiation of neonatal astrocytes to enhance their neuroprotective properties. ASN Neuro 2011; 3:e00062. [PMID: 21722095 PMCID: PMC3153963 DOI: 10.1042/an20100029] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Hypoxic preconditioning reprogrammes the brain's response to subsequent H/I (hypoxia–ischaemia) injury by enhancing neuroprotective mechanisms. Given that astrocytes normally support neuronal survival and function, the purpose of the present study was to test the hypothesis that a hypoxic preconditioning stimulus would activate an adaptive astrocytic response. We analysed several functional parameters 24 h after exposing rat pups to 3 h of systemic hypoxia (8% O2). Hypoxia increased neocortical astrocyte maturation as evidenced by the loss of GFAP (glial fibrillary acidic protein)-positive cells with radial morphologies and the acquisition of multipolar GFAP-positive cells. Interestingly, many of these astrocytes had nuclear S100B. Accompanying their differentiation, there was increased expression of GFAP, GS (glutamine synthetase), EAAT-1 (excitatory amino acid transporter-1; also known as GLAST), MCT-1 (monocarboxylate transporter-1) and ceruloplasmin. A subsequent H/I insult did not result in any further astrocyte activation. Some responses were cell autonomous, as levels of GS and MCT-1 increased subsequent to hypoxia in cultured forebrain astrocytes. In contrast, the expression of GFAP, GLAST and ceruloplasmin remained unaltered. Additional experiments utilized astrocytes exposed to exogenous dbcAMP (dibutyryl-cAMP), which mimicked several aspects of the preconditioning response, to determine whether activated astrocytes could protect neurons from subsequent excitotoxic injury. dbcAMP treatment increased GS and glutamate transporter expression and function, and as hypothesized, protected neurons from glutamate excitotoxicity. Taken altogether, these results indicate that a preconditioning stimulus causes the precocious differentiation of astrocytes and increases the acquisition of multiple astrocytic functions that will contribute to the neuroprotection conferred by a sublethal preconditioning stress.
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