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The role of diurnal fluctuations in excitatory amino acid carrier 1 levels in post-ischemic hippocampal Zn 2+ accumulation. Exp Neurol 2020; 336:113538. [PMID: 33253705 DOI: 10.1016/j.expneurol.2020.113538] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2020] [Revised: 11/04/2020] [Accepted: 11/22/2020] [Indexed: 02/06/2023]
Abstract
Accumulating evidence indicates time-of-day variations in ischemic neuronal injury. Under ischemic conditions, Zn2+ is massively released from hippocampal glutamatergic neurons, and intracellular Zn2+ accumulation results in neuron death. Notably, excitatory amino acid carrier 1 (EAAC1), known as a cysteine transporter, is involved in Zn2+ homeostasis, and its expressions exhibit a diurnal fluctuation. This study aimed to investigate whether time of day of an ischemic insult affects Zn2+ accumulation and neuronal injury and determine whether altered Zn2+ accumulation is modulated by EAAC1 diurnal fluctuation in the hippocampus in a mouse model of ischemic stroke. Mice subjected to transient global ischemia for 40 min at Zeitgeber time 18 (ZT18) (23:00) exhibited reduced Zn2+ accumulation and neuronal death in the hilar region of the hippocampus compared to those at ZT4 (09:00). The EAAC1 protein expression in the hippocampus was increased at ZT18 relative to ZT4. Intracerebroventricular injection of a non-selective excitatory amino acid transporter inhibitor, DL-threo-β-benzyloxyaspartate, or a selective EAAC1 inhibitor, L-aspartic acid β-hydroxamate, increased ischemia-induced Zn2+ accumulation and neuronal death in the hilus at ZT18. These findings suggest that ischemia-induced Zn2+ accumulation displays circadian fluctuations through diurnal variations in EAAC1 expressions and affects susceptibility to ischemic neuronal injury in the hippocampal hilar region.
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2
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León-Moreno LC, Castañeda-Arellano R, Rivas-Carrillo JD, Dueñas-Jiménez SH. Challenges and Improvements of Developing an Ischemia Mouse Model Through Bilateral Common Carotid Artery Occlusion. J Stroke Cerebrovasc Dis 2020; 29:104773. [PMID: 32199775 DOI: 10.1016/j.jstrokecerebrovasdis.2020.104773] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2019] [Revised: 01/10/2020] [Accepted: 02/17/2020] [Indexed: 01/01/2023] Open
Abstract
Brain ischemia is one of the principal causes of death and disability worldwide in which prevention or an effective treatment does not exist. In order to develop successful treatments, an adequate and useful ischemia model is essential. Transient global cerebral ischemia is one of the most interesting pathological conditions in stroke studies because of the observed degeneration of forebrain and delayed neuronal cell death in selective vulnerable regions such as hippocampus. Transient occlusion of both common carotid arteries is the most convenient model to induce tGCI. Although there are effective rat and gerbil models using this method, the induction of a reproducible and reliable injury after global ischemia in mouse has presented higher variations, mainly because of its size and the necessary monitoring skills in order to accomplish homogeneous and reproducible results. Further, great variability among cerebral vasculature and susceptibility of the different strains and sub-strains is observed. In recent years, some modifications have been made to the model in order to normalize the heterogenic effects. Analysis of posterior communicating artery patency has been proposed as an exclusion parameter due to the direct relationship reported with the reduction of cerebral blood flow. Another method used to significantly reduce blood flow is the induction of hypotension with isoflurane. Each protocol produces distinct injury outcomes. Further improvements are needed to attain a general, simpler, reproducible and globally accepted model that allows comparisons between research groups, progress in understanding ischemia and the consequent development of therapeutic alternatives for ischemic injury.
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Affiliation(s)
| | - Rolando Castañeda-Arellano
- Department of Biomedical Sciences, University Center of Tonala, University de Guadalajara, Jalisco Mexico
| | - Jorge David Rivas-Carrillo
- Department of Physiology, Laboratory of Tissue Engineering and Transplant and cGMP Cell Processing Facility, Health Sciences Center, University de Guadalajara, Jalisco, Mexico
| | - Sergio Horacio Dueñas-Jiménez
- Department of Neuroscience, Laboratory of Neurophysiology, Health Sciences Center, University of Guadalajara, Guadalajara, C.P. 44340 Jalisco, México.
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3
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Lee YH, Lee SR. Neuroprotective effects of N-acetylcysteine via inhibition of matrix metalloproteinase in a mouse model of transient global cerebral ischemia. Brain Res Bull 2019; 154:142-150. [PMID: 31722253 DOI: 10.1016/j.brainresbull.2019.10.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2019] [Revised: 10/06/2019] [Accepted: 10/15/2019] [Indexed: 10/25/2022]
Abstract
N-acetylcysteine (NAC) is known to serve many biological functions including acting as an antioxidant, and electing antiinflammatory effects. Previous reports have revealed that NAC may have neuroprotective effects against the deleterious effects of brain ischemia. Despite of this, the mechanism by which NAC prevents neuronal damage after brain ischemia remains unclear. The current study aimed to investigate this mechanism in a mouse model of transient global brain ischemia. In the present study, mice were subjected to 20 min of transient global brain ischemia, proceeded by intraperitoneal administration of NAC (150 mg/kg) in one group. The mice were then euthanized 72 h after this ischemic insult for collection of experimental tissues. The effect of NAC on neuronal damage and matrix metalloproteinase (MMP)-9 activity were assessed and immunofluorescence, and hippocampal terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL) assay experiments were conducted and results compared between NAC- and vehicle-treated groups. Neuronal damage was primarily observed in the hippocampal CA1 and CA2 regions. In NAC-treated mice, neuronal damage was significantly reduced after ischemia when compared to vehicle-treated animals. NAC also inhibited increased MMP-9 activity after global brain ischemia. NAC increased laminin and NeuN expression and inhibited increases in TUNEL-positive cells, all in the hippocampus. These results suggest that NAC reduces hippocampal neuronal damage following transient global ischemia, potentially via reductions in MMP-9 activity.
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Affiliation(s)
- Yoon-Hyung Lee
- Department of Pharmacology and ODR center, Brain Research Institute, School of Medicine, Keimyung University, Daegu, 42601, South Korea; Department of Urology, Fatima Hospital, Daegu, 42601, South Korea
| | - Seong-Ryong Lee
- Department of Pharmacology and ODR center, Brain Research Institute, School of Medicine, Keimyung University, Daegu, 42601, South Korea.
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4
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Wang F, Han J, Higashimori H, Wang J, Liu J, Tong L, Yang Y, Dong H, Zhang X, Xiong L. Long-term depression induced by endogenous cannabinoids produces neuroprotection via astroglial CB 1R after stroke in rodents. J Cereb Blood Flow Metab 2019; 39:1122-1137. [PMID: 29432698 PMCID: PMC6547184 DOI: 10.1177/0271678x18755661] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Ischemia not only activates cell death pathways but also triggers endogenous protective mechanisms. However, it is largely unknown what is the essence of the endogenous neuroprotective mechanisms induced by preconditioning. In this study we demonstrated that systemic injection of JZL195, a selective inhibitor of eCB clearance enzymes, induces in vivo long-term depression at CA3-CA1 synapses and at PrL-NAc synapses produces neuroprotection. JZL195-elicited long-term depression is blocked by AM281, the antagonist of cannabinoid 1 receptor (CB1R) and is abolished in mice lacking cannabinoid CB1 receptor (CB1R) in astroglial cells, but is conserved in mice lacking CB1R in glutamatergic or GABAergic neurons. Blocking the glutamate NMDA receptor and the synaptic trafficking of glutamate AMPA receptor abolishes both long-term depression and neuroprotection induced by JZL195. Mice lacking CB1R in astroglia show decreased neuronal death following cerebral ischemia. Thus, an acute elevation of extracellular eCB following eCB clearance inhibition results in neuroprotection through long-term depression induction after sequential activation of astroglial CB1R and postsynaptic glutamate receptors.
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Affiliation(s)
- Feng Wang
- 1 Department of Anesthesiology and Perioperative Medicine, Xijing Hospital, Fourth Military Medical University, Xian, Shaanxi Province, China.,2 Department of Psychiatry, and Department of Cellular & Molecular Medicine, University of Ottawa Institute of Mental Health Research at the Royal, Ottawa, ON, Canada
| | - Jing Han
- 3 Key Laboratory of Modern Teaching Technology, Shaanxi Normal University, Xian, China
| | - Haruki Higashimori
- 4 Department of Neuroscience, Tufts University School of Medicine, Boston, MA, USA
| | - Jingyi Wang
- 1 Department of Anesthesiology and Perioperative Medicine, Xijing Hospital, Fourth Military Medical University, Xian, Shaanxi Province, China
| | - Jingjing Liu
- 1 Department of Anesthesiology and Perioperative Medicine, Xijing Hospital, Fourth Military Medical University, Xian, Shaanxi Province, China
| | - Li Tong
- 2 Department of Psychiatry, and Department of Cellular & Molecular Medicine, University of Ottawa Institute of Mental Health Research at the Royal, Ottawa, ON, Canada
| | - Yongjie Yang
- 4 Department of Neuroscience, Tufts University School of Medicine, Boston, MA, USA
| | - Hailong Dong
- 1 Department of Anesthesiology and Perioperative Medicine, Xijing Hospital, Fourth Military Medical University, Xian, Shaanxi Province, China
| | - Xia Zhang
- 2 Department of Psychiatry, and Department of Cellular & Molecular Medicine, University of Ottawa Institute of Mental Health Research at the Royal, Ottawa, ON, Canada
| | - Lize Xiong
- 1 Department of Anesthesiology and Perioperative Medicine, Xijing Hospital, Fourth Military Medical University, Xian, Shaanxi Province, China
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5
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Prophylactic Zinc and Therapeutic Selenium Administration Increases the Antioxidant Enzyme Activity in the Rat Temporoparietal Cortex and Improves Memory after a Transient Hypoxia-Ischemia. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2018; 2018:9416432. [PMID: 30258527 PMCID: PMC6146673 DOI: 10.1155/2018/9416432] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/16/2018] [Accepted: 07/31/2018] [Indexed: 11/17/2022]
Abstract
In the cerebral hypoxia-ischemia rat model, the prophylactic administration of zinc can cause either cytotoxicity or preconditioning effect, whereas the therapeutic administration of selenium decreases the ischemic damage. Herein, we aimed to explore whether supplementation of low doses of prophylactic zinc and therapeutic selenium could protect from a transient hypoxic-ischemic event. We administrated zinc (0.2 mg/kg of body weight; ip) daily for 14 days before a 10 min common carotid artery occlusion (CCAO). After CCAO, we administrated sodium selenite (6 μg/kg of body weight; ip) daily for 7 days. In the temporoparietal cerebral cortex, we determined nitrites by the Griess method and lipid peroxidation by the Gerard-Monnier assay. qPCR was used to measure mRNA of nitric oxide synthases, antioxidant enzymes, chemokines, and their receptors. We measured the enzymatic activity of SOD and GPx and protein levels of chemokines and their receptors by ELISA. We evaluated long-term memory using the Morris-Water maze test. Our results showed that prophylactic administration of zinc caused a preconditioning effect, decreasing nitrosative/oxidative stress and increasing GPx and SOD expression and activity, as well as eNOS expression. The therapeutic administration of selenium maintained this preconditioning effect up to the late phase of hypoxia-ischemia. Ccl2, Ccr2, Cxcl12, and Cxcr4 were upregulated, and long-term memory was improved. Pyknotic cells were decreased suggesting prevention of neuronal cell death. Our results show that the prophylactic zinc and therapeutic selenium administration induces effective neuroprotection in the early and late phases after CCAO.
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Gonçalves LV, Herlinger AL, Ferreira TAA, Coitinho JB, Pires RGW, Martins-Silva C. Environmental enrichment cognitive neuroprotection in an experimental model of cerebral ischemia: biochemical and molecular aspects. Behav Brain Res 2018; 348:171-183. [DOI: 10.1016/j.bbr.2018.04.023] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2017] [Revised: 03/07/2018] [Accepted: 04/16/2018] [Indexed: 01/25/2023]
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7
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Justin A, Divakar S, Ramanathan M. Cerebral ischemia induced inflammatory response and altered glutaminergic function mediated through brain AT 1 and not AT 2 receptor. Biomed Pharmacother 2018; 102:947-958. [PMID: 29710550 DOI: 10.1016/j.biopha.2018.03.164] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2017] [Revised: 03/27/2018] [Accepted: 03/28/2018] [Indexed: 11/28/2022] Open
Abstract
In the present study, we investigated the effects of angiotensin (Ang II) receptor blockers in cerebral ischemia by administration of telmisartan (AT1 blocker) and/or PD123319 (AT2 blocker) in global ischemic mice model. The neuroprotective effect of AT antagonists was evaluated through monitoring muscle co-ordination and cerebral blood perfusion in ischemic mice. Gene expression studies (NF-κB, GSK-3β, EAAT-2, AT1 & AT2 receptors) and staining of brain regions with cresyl violet, GFAP, synaptophysin and NSE methods were carried out in to understand the molecular mechanisms. Further, the brain glutamate, cytokines, and Ang II peptide levels were evaluated and their correlation with EAAT-2 mRNA expression was performed. Our results indicate that the induction of ischemia elevates brain Ang II, cytokines, and glutamate levels and reduced muscle co-ordination and cerebral blood perfusion. The expressions of NF-κB, GSK-3β and AT1 were significantly increased, whereas, EAAT-2 expression was decreased. Blocking of AT1 receptors by telmisartan (TM) reversed the detrimental responses of cerebral ischemia and restored the cerebral blood flow denoting blockade of Ang II/AT1 pathway is beneficial in ischemia, whereas, blockade of AT2 receptors by PD123319 (PD) increased the ischemic injury in mice. This vulnerable effect of PD may be attributed through augmenting the Ang II/AT1 dependent cytokines mediated glutamate transporter (EAAT-2) dysfunction. Interestingly, the beneficial effects of AT1 blocker was remarkably antagonized by AT2 blocker in most of the parameters studied in ischemic conditions. Also, the expression of AT2 receptors was significantly increased compared to that of AT1 receptors upon ischemic induction. It denotes that the endogenous Ang II predominantly acts on AT2 receptor, thereby promoting its own mRNA transcription. Hence, the increased expression of AT2 receptors in ischemic condition could be used as target protein for therapeutic benefit.
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Affiliation(s)
- A Justin
- PSG College of Pharmacy, Peelamedu, Coimbatore, TN, 641004, India
| | - S Divakar
- PSG College of Pharmacy, Peelamedu, Coimbatore, TN, 641004, India
| | - M Ramanathan
- PSG College of Pharmacy, Peelamedu, Coimbatore, TN, 641004, India.
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8
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Nyanzu M, Siaw-Debrah F, Ni H, Xu Z, Wang H, Lin X, Zhuge Q, Huang L. Improving on Laboratory Traumatic Brain Injury Models to Achieve Better Results. Int J Med Sci 2017; 14:494-505. [PMID: 28539826 PMCID: PMC5441042 DOI: 10.7150/ijms.18075] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/25/2016] [Accepted: 01/31/2017] [Indexed: 11/30/2022] Open
Abstract
Experimental modeling of traumatic brain injury (TBI) in animals has identified several potential means and interventions that might have beneficial applications for treating traumatic brain injury clinically. Several of these interventions have been applied and tried with humans that are at different phases of testing (completed, prematurely terminated and others in progress). The promising results achieved in the laboratory with animal models have not been replicated with human trails as expected. This review will highlight some insights and significance attained via laboratory animal modeling of TBI as well as factors that require incorporation into the experimental studies that could help in translating results from laboratory to the bedside. Major progress has been made due to laboratory studies; in explaining the mechanisms as well as pathophysiological features of brain damage after TBI. Attempts to intervene in the cascade of events occurring after TBI all rely heavily on the knowledge from basic laboratory investigations. In looking to discover treatment, this review will endeavor to sight and state some central discrepancies between laboratory models and clinical scenarios.
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Affiliation(s)
- Mark Nyanzu
- Zhejiang Provincial Key Laboratory of Aging and Neurological Disorder Research, First Affiliated Hospital, Wenzhou Medical University, Wenzhou 325000, China.,Department of Neurosurgery, the First Affiliated Hospital of Wenzhou Medical University, Wenzhou 325000, China
| | - Felix Siaw-Debrah
- Zhejiang Provincial Key Laboratory of Aging and Neurological Disorder Research, First Affiliated Hospital, Wenzhou Medical University, Wenzhou 325000, China.,Department of Neurosurgery, the First Affiliated Hospital of Wenzhou Medical University, Wenzhou 325000, China
| | - Haoqi Ni
- Zhejiang Provincial Key Laboratory of Aging and Neurological Disorder Research, First Affiliated Hospital, Wenzhou Medical University, Wenzhou 325000, China.,Department of Neurosurgery, the First Affiliated Hospital of Wenzhou Medical University, Wenzhou 325000, China
| | - Zhu Xu
- Zhejiang Provincial Key Laboratory of Aging and Neurological Disorder Research, First Affiliated Hospital, Wenzhou Medical University, Wenzhou 325000, China.,Department of Neurosurgery, the First Affiliated Hospital of Wenzhou Medical University, Wenzhou 325000, China
| | - Hua Wang
- Zhejiang Provincial Key Laboratory of Aging and Neurological Disorder Research, First Affiliated Hospital, Wenzhou Medical University, Wenzhou 325000, China.,Department of Neurosurgery, the First Affiliated Hospital of Wenzhou Medical University, Wenzhou 325000, China
| | - Xiao Lin
- Zhejiang Provincial Key Laboratory of Aging and Neurological Disorder Research, First Affiliated Hospital, Wenzhou Medical University, Wenzhou 325000, China.,Department of Neurosurgery, the First Affiliated Hospital of Wenzhou Medical University, Wenzhou 325000, China
| | - Qichuan Zhuge
- Zhejiang Provincial Key Laboratory of Aging and Neurological Disorder Research, First Affiliated Hospital, Wenzhou Medical University, Wenzhou 325000, China.,Department of Neurosurgery, the First Affiliated Hospital of Wenzhou Medical University, Wenzhou 325000, China
| | - Lijie Huang
- Zhejiang Provincial Key Laboratory of Aging and Neurological Disorder Research, First Affiliated Hospital, Wenzhou Medical University, Wenzhou 325000, China.,Department of Neurosurgery, the First Affiliated Hospital of Wenzhou Medical University, Wenzhou 325000, China
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9
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Low dose of l-glutamic acid attenuated the neurological dysfunctions and excitotoxicity in bilateral common carotid artery occluded mice. Behav Pharmacol 2016; 27:615-22. [DOI: 10.1097/fbp.0000000000000256] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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10
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Spray S, Edvinsson L. Improved assessment of outcomes following transient global cerebral ischemia in mice. Exp Brain Res 2016; 234:1925-1934. [DOI: 10.1007/s00221-016-4597-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2015] [Accepted: 02/11/2016] [Indexed: 11/28/2022]
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11
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Hong JH, Lee H, Lee SR. Protective effect of resveratrol against neuronal damage following transient global cerebral ischemia in mice. J Nutr Biochem 2016; 27:146-52. [DOI: 10.1016/j.jnutbio.2015.08.029] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2015] [Revised: 08/12/2015] [Accepted: 08/25/2015] [Indexed: 02/04/2023]
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12
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Wang HC, Sun CF, Chen H, Chen MS, Shen G, Ma YB, Wang BD. Where are we in the modelling of traumatic brain injury? Models complicated by secondary brain insults. Brain Inj 2014; 28:1491-503. [PMID: 25111457 DOI: 10.3109/02699052.2014.943288] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Affiliation(s)
- Hong-Cai Wang
- Department of Neurosurgery, Li Hui Li Hospital of Medical Centre of Ningbo
NingboPR China
| | - Cheng-Feng Sun
- Department of Neurosurgery, Li Hui Li Hospital of Medical Centre of Ningbo
NingboPR China
| | - Hai Chen
- Department of Neurosurgery, Li Hui Li Hospital of Medical Centre of Ningbo
NingboPR China
| | - Mao-Song Chen
- Department of Neurosurgery, Li Hui Li Hospital of Medical Centre of Ningbo
NingboPR China
| | - Gang Shen
- Department of Neurosurgery, Li Hui Li Hospital of Medical Centre of Ningbo
NingboPR China
| | - Yan-Bin Ma
- Department of Neurosurgery, NO.3 People’s Hospital Affiliated to Shanghai Jiao Tong University School of Medicine
ShanghaiPR China
| | - Bo-Ding Wang
- Department of Neurosurgery, Li Hui Li Hospital of Medical Centre of Ningbo
NingboPR China
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13
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Lee JH, Wei L, Gu X, Wei Z, Dix TA, Yu SP. Therapeutic effects of pharmacologically induced hypothermia against traumatic brain injury in mice. J Neurotrauma 2014; 31:1417-30. [PMID: 24731132 DOI: 10.1089/neu.2013.3251] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Preclinical and clinical studies have shown therapeutic potential of mild-to-moderate hypothermia for treatments of stroke and traumatic brain injury (TBI). Physical cooling in humans, however, is usually slow, cumbersome, and necessitates sedation that prevents early application in clinical settings and causes several side effects. Our recent study showed that pharmacologically induced hypothermia (PIH) using a novel neurotensin receptor 1 (NTR1) agonist, HPI-201 (also known as ABS-201), is efficient and effective in inducing therapeutic hypothermia and protecting the brain from ischemic and hemorrhagic stroke in mice. The present investigation tested another second-generation NTR1 agonist, HPI-363, for its hypothermic and protective effect against TBI. Adult male mice were subjected to controlled cortical impact (CCI) (velocity=3 m/sec, depth=1.0 mm, contact time=150 msec) to the exposed cortex. Intraperitoneal administration of HPI-363 (0.3 mg/kg) reduced body temperature by 3-5°C within 30-60 min without triggering a shivering defensive reaction. An additional two injections sustained the hypothermic effect in conscious mice for up to 6 h. This PIH treatment was initiated 15, 60, or 120 min after the onset of TBI, and significantly reduced the contusion volume measured 3 days after TBI. HPI-363 attenuated caspase-3 activation, Bax expression, and TUNEL-positive cells in the pericontusion region. In blood-brain barrier assessments, HPI-363 ameliorated extravasation of Evans blue dye and immunoglobulin G, attenuated the MMP-9 expression, and decreased the number of microglia cells in the post-TBI brain. HPI-363 decreased the mRNA expression of tumor necrosis factor-α and interleukin-1β (IL-1β), but increased IL-6 and IL-10 levels. Compared with TBI control mice, HPI-363 treatments improved sensorimotor functional recovery after TBI. These findings suggest that the second generation NTR-1 agonists, such as HPI-363, are efficient hypothermic-inducing compounds that have a strong potential in the management of TBI.
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Affiliation(s)
- Jin Hwan Lee
- 1 Department of Anesthesiology, Emory University School of Medicine , Atlanta, Georgia
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Kim SJ, Lee SR. Protective effect of melatonin against transient global cerebral ischemia-induced neuronal cell damage via inhibition of matrix metalloproteinase-9. Life Sci 2013; 94:8-16. [PMID: 24269215 DOI: 10.1016/j.lfs.2013.11.013] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2013] [Revised: 11/09/2013] [Accepted: 11/09/2013] [Indexed: 11/26/2022]
Abstract
AIMS Melatonin possesses various pharmacological effects including neuroprotective effects against brain ischemia. Post-ischemic increases in matrix metalloproteinase-9 (MMP-9) expression and activity mainly contribute to neuronal damage by degradation of the extracellular matrix. This study was designed to examine whether melatonin has a neuroprotective effect and an influence on MMP-9 in transient global brain ischemia. MAIN METHODS Mice were subjected to 20 min of global brain ischemia and sacrificed 72h later. Melatonin (30 mg/kg) was administered 30 min before and 2h after ischemia as well as once daily until sacrifice. KEY FINDINGS Hippocampal pyramidal cell damage after ischemia was significantly decreased by melatonin. As observed by zymography, melatonin inhibited the increase of MMP-9 activity after ischemia. In the brain sections, the increased gelatinase activity was mainly observed in the hippocampus after ischemia and melatonin also reduced gelatinase activity. The laminin and NeuN expression levels were reduced in the hippocampal CA1 and CA2 regions after ischemia, and melatonin reduced laminin degradation and neuronal loss. A TUNEL assay demonstrated that there were TUNEL-positive cells in the hippocampus and the number of TUNEL-positive cells was significantly decreased by melatonin. There was no difference in the ischemia-induced hippocampal neuronal damage between the vehicle- and melatonin-treated groups of MMP-9 knock-out mice. SIGNIFICANCE These data demonstrate that melatonin suppressed the occurrence of neuronal injury, which might be partly due to its inhibitory effects on MMP-9 in addition to its anti-oxidative effects. MMP-9 may be an important key target of melatonin in neuroprotection against global ischemia.
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Affiliation(s)
- Su-Jin Kim
- Department of Anesthesiology, College of Medicine, Dongguk University, Gyeongju, South Korea; Department of Pharmacology, School of Medicine and Brain Research Institute, Keimyung University, Daegu 704-701, South Korea
| | - Seong-Ryong Lee
- Department of Pharmacology, School of Medicine and Brain Research Institute, Keimyung University, Daegu 704-701, South Korea.
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15
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1H nuclear magnetic resonance brain metabolomics in neonatal mice after hypoxia-ischemia distinguished normothermic recovery from mild hypothermia recoveries. Pediatr Res 2013; 74:170-9. [PMID: 23708689 PMCID: PMC3734529 DOI: 10.1038/pr.2013.88] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/17/2012] [Accepted: 04/01/2013] [Indexed: 12/20/2022]
Abstract
BACKGROUND Mild brain hypothermia (31-34 °C) after neonatal hypoxia-ischemia (HI) improves neurodevelopmental outcomes in human and animal neonates. Using an asphyxia model with neonatal mice treated with mild hypothermia after HI, we investigated whether (1)H nuclear magnetic resonance (NMR) metabolomics of brain extracts could suggest biomarkers and distinguish different treatments and outcome groups. METHODS At postnatal day 7 (P7), CD1 mice underwent right carotid artery occlusion, 30 min of HI (8% oxygen), and 3.5 h of either hypothermia (31 °C) or normothermia (37 °C). Whole brains were frozen immediately after HI, immediately after 3.5 h of hypothermia or normothermia treatments, and 24 h later. Perchloric acid extractions of 36 metabolites were quantified by 900 MHz (1)H NMR spectroscopy. Multivariate analyses included principal component analyses (PCA) and a novel regression algorithm. Histological injury was quantified after HI at 5 d. RESULTS PCA scores plots separated normothermia/HI animals from hypothermia/HI and control animals, but more data are required for multivariate models to be predictive. Loadings plots identified 11 significant metabolites, whereas the regression algorithm identified 6. Histological injury scores were significantly reduced by hypothermia. CONCLUSION Different treatment and outcome groups are identifiable by (1)H NMR metabolomics in a neonatal mouse model of mild hypothermia treatment of HI.
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16
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Meeusen JW, Tomasiewicz H, Nowakowski A, Petering DH. TSQ (6-methoxy-8-p-toluenesulfonamido-quinoline), a common fluorescent sensor for cellular zinc, images zinc proteins. Inorg Chem 2011; 50:7563-73. [PMID: 21774459 DOI: 10.1021/ic200478q] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Zn(2+) is a necessary cofactor for thousands of mammalian proteins. Research has suggested that transient fluxes of cellular Zn(2+) are also involved in processes such as apoptosis. Observations of Zn(2+) trafficking have been collected using Zn(2+) responsive fluorescent dyes. A commonly used Zn(2+) fluorophore is 6-methoxy-8-p-toluenesulfonamido-quinoline (TSQ). The chemical species responsible for TSQ's observed fluorescence in resting or activated cells have not been characterized. Parallel fluorescence microscopy and spectrofluorometry of LLC-PK(1) cells incubated with TSQ demonstrated punctate staining that concentrated around the nucleus and was characterized by an emission maximum near 470 nm. Addition of cell permeable Zn-pyrithione resulted in greatly increased, diffuse fluorescence that shifted the emission peak to 490 nm, indicative of the formation of Zn(TSQ)(2). TPEN (N,N,N'N'-tetrakis(-)[2-pyridylmethyl]-ethylenediamine), a cell permeant Zn(2+) chelator, largely quenched TSQ fluorescence returning the residual fluorescence to the 470 nm emission maximum. Gel filtration chromatography of cell supernatant from LLC-PK(1) cells treated with TSQ revealed that TSQ fluorescence (470 nm emission) eluted with the proteome fractions. Similarly, addition of TSQ to proteome prior to chromatography resulted in 470 nm fluorescence emission that was not observed in smaller molecular weight fractions. It is hypothesized that Zn-TSQ fluorescence, blue-shifted from the 490 nm emission maximum of Zn(TSQ)(2), results from ternary complex, TSQ-Zn-protein formation. As an example, Zn-carbonic anhydrase formed a ternary adduct with TSQ characterized by a fluorescence emission maximum of 470 nm and a dissociation constant of 1.55 × 10(-7) M. Quantification of TSQ-Zn-proteome fluorescence indicated that approximately 8% of cellular Zn(2+) was imaged by TSQ. These results were generalized to other cell types and model Zn-proteins.
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Affiliation(s)
- Jeffrey W Meeusen
- Department of Chemistry and Biochemistry, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin 53201, USA
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Li J, Benashski S, McCullough LD. Post-stroke hypothermia provides neuroprotection through inhibition of AMP-activated protein kinase. J Neurotrauma 2011; 28:1281-8. [PMID: 21446786 DOI: 10.1089/neu.2011.1751] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Hypothermia is robustly protective in pre-clinical models of both global and focal ischemia, as well as in patients after cardiac arrest. Although the mechanism for hypothermic neuroprotection remains unknown, reducing metabolic drive may play a role. Capitalizing on the beneficial effects of hypothermia while avoiding detrimental effects such as infection will be the key to moving this therapy forward as a treatment for stroke. AMPK is a master energy sensor that monitors levels of key energy metabolites. AMPK is activated via phosphorylation (pAMPK) when cellular energy levels are low, such as that seen during ischemia. AMPK activation appears to be detrimental in experimental stroke, likely via exacerbating ischemia-induced metabolic failure. We tested the hypothesis that hypothermia reduces AMPK activation. First, it was found that hypothermia reduced infarct after middle cerebral artery occlusion. Second, induced hypothermia reduced brain pAMPK in both sham control and stroke mice. Third, hypothermic neuroprotection was ameliorated after administration of compound C, an AMPK inhibitor. Finally, deletion of one of the catalytic isoforms of AMPK completely reversed the effect of hypothermia on stroke outcome after both acute and chronic survival. These effects were mediated by a reduction in AMPK activation rather than a reduction in LKB1, an upstream AMPK kinase. In summary, these studies provide evidence that hypothermia exerts its protective effect in part by inhibiting AMPK activation in experimental focal stroke. This suggests that AMPK represents a potentially important biological target for stroke treatment.
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Affiliation(s)
- Jun Li
- Department of Neuroscience, University of Connecticut Health Center, Farmington, CT 06030, USA
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Park JW, Jang YH, Kim JM, Lee H, Park WK, Lim MB, Chu YK, Lo EH, Lee SR. Green tea polyphenol (-)-epigallocatechin gallate reduces neuronal cell damage and up-regulation of MMP-9 activity in hippocampal CA1 and CA2 areas following transient global cerebral ischemia. J Neurosci Res 2009; 87:567-75. [PMID: 18752302 DOI: 10.1002/jnr.21847] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Previous studies have demonstrated that (-)-epigallocatechin gallate (EGCG), a green tea polyphenol, protects against ischemia and reperfusion-induced injury in many organ systems. Here, we test the hypothesis that part of EGCG's neuroprotective effects may involve a modulation of matrix metalloproteinases (MMPs) after cerebral ischemia. C57BL/6 mice were subjected to 20 min of transient global cerebral ischemia. EGCG (50 mg/kg) or vehicle (saline) was administered i.p. immediately after ischemia. Brains were examined 3 days after ischemia. The effects of EGCG on MMP (gelatinase) activity and neuronal damage in the hippocampus were assessed. Gelatin gel zymography showed induction of active forms of MMP-9 protein after transient global cerebral ischemia. In situ zymography showed that ischemic gelatinase activity occurred primarily in pyramidal neuronal areas after brain ischemia. Mice treated with EGCG showed significantly reduced gelatinase levels. Neuronal damage was evident in CA1 and CA2 pyramidal sectors, corresponding to TUNEL-positive signals. In EGCG-treated mice, delayed neuronal damage was significantly reduced compared with vehicle-treated mice. These results demonstrate that the green tea polyphenol EGCG suppresses MMP-9 activation and reduces the development of delayed neuronal death after transient global cerebral ischemia in mouse brain.
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Affiliation(s)
- Jong-Wan Park
- Department of Pharmacology, School of Medicine, Keimyung University, Taegu, South Korea
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Nagel S, Papadakis M, Hoyte L, Buchan AM. Therapeutic hypothermia in experimental models of focal and global cerebral ischemia and intracerebral hemorrhage. Expert Rev Neurother 2008; 8:1255-68. [PMID: 18671669 DOI: 10.1586/14737175.8.8.1255] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Experimental evidence shows that therapeutic hypothermia (TH) protects the brain from cerebral injury in multiple ways. In different models of focal and global cerebral ischemia, mild-to-moderate hypothermia reduces mortality and neuronal injury and improves neurological outcome. In models of experimental intracerebral hemorrhage (ICH), TH reduces edema formation but does not show consistent benefi cial effects on functional outcome parameters. However, the number of studies of hypothermia on ICH is still limited. TH is most effective when applied before or during the ischemic event, and its neuroprotective properties vary according to species, strains and the model of ischemia used. Intrinsic changes in body and brain temperature frequently occur in experimental models of focal and global cerebral ischemia, and may have infl uenced studies on other neuroprotectants. This might be one explanation for the failure of a large amount of translational clinical neuroprotective trials. Hypothermia is the only neuroprotective therapeutic agent for cerebral ischemia that has successfully managed the transfer from bench to bedside, and it is an approved therapy for patients after cardiac arrest and children with hypoxic-ischemic encephalopathy. However, the implementation of hypothermia in the treatment of stroke patients is still far from routine clinical practice. In this article, the authors describe the development of TH in different models of focal and global cerebral ischemia, point out why hypothermia is so efficient in experimental cerebral ischemia, explain why temperature regulation is essential for further neuroprotective studies and discuss why TH for acute ischemic stroke still remains a promising but controversial therapeutic option.
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Affiliation(s)
- Simon Nagel
- Acute Stroke Programme, Nuffield Department of Clinical Medicine, John Radcliffe Hospital, Oxford, OX3 9DU, UK.
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Lee KJ, Jang YH, Lee H, Yoo HS, Lee SR. PPARgamma agonist pioglitazone reduces [corrected] neuronal cell damage after transient global cerebral ischemia through matrix metalloproteinase inhibition. Eur J Neurosci 2008; 27:334-42. [PMID: 18215232 DOI: 10.1111/j.1460-9568.2007.06007.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Previous studies have demonstrated that pioglitazone, a peroxisome proliferator-activated receptor gamma (PPARgamma) agonist, inhibits ischemia-induced injury in various tissues including neural tissue. Pioglitazone has also been shown to reduce matrix metalloproteinase (MMP) activity. Because MMP is known to play a major role in the pathophysiology of brain ischemia, the present study was undertaken to test whether pioglitazone attenuates ischemic neuronal damage through MMP inhibition. C57BL/6 mice were subjected to global brain ischemia for 20 min. Animals were killed 72 h after ischemia. Oral pioglitazone (40 mg/kg/day, as a suspension in 0.5% carboxymethylcellulose) was administered to mice twice daily for 3 days before ischemia and twice daily after ischemia until the animals were killed. We investigated gelatinase activity by zymography and laminin immunohistochemistry. Histological analysis was also performed to test the protective effect of pioglitazone on neuronal damage. Mice treated with pioglitazone had attenuated gelatinase activity. Gelatin gel and in situ zymography showed up-regulation of gelatinase activity after ischemia. Pioglitazone significantly inhibited ischemia-induced elevation of the active form of MMP-9. Pioglitazone also reduced up-regulation of in situ gelatinase activity and laminin breakdown induced by ischemia in the hippocampus. There was marked neuronal damage in the CA1 and CA2 areas after ischemia. Neuronal damage in mice was significantly decreased by pioglitazone treatment, compared with vehicle-treated mice. Pioglitazone also inhibited TdT-mediated dUTP nick end labeling staining in CA1 and CA2 areas. Pioglitazone, a PPARgamma agonist, reduces delayed neuronal damage induced by global ischemia through inhibition of MMP-9 activity.
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Affiliation(s)
- Kyung-Jae Lee
- Department of Pharmacology, School of Medicine, Keimyung University, Taegu 700-712, South Korea
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Zhao H, Steinberg GK, Sapolsky RM. General versus specific actions of mild-moderate hypothermia in attenuating cerebral ischemic damage. J Cereb Blood Flow Metab 2007; 27:1879-94. [PMID: 17684517 DOI: 10.1038/sj.jcbfm.9600540] [Citation(s) in RCA: 137] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Mild or moderate hypothermia is generally thought to block all changes in signaling events that are detrimental to ischemic brain, including ATP depletion, glutamate release, Ca(2+) mobilization, anoxic depolarization, free radical generation, inflammation, blood-brain barrier permeability, necrotic, and apoptotic pathways. However, the effects and mechanisms of hypothermia are, in fact, variable. We emphasize that, even in the laboratory, hypothermic protection is limited. In certain models of permanent focal ischemia, hypothermia may not protect at all. In cases where hypothermia reduces infarct, some studies have overemphasized its ability to maintain cerebral blood flow and ATP levels, and to prevent anoxic depolarization, glutamate release during ischemia. Instead, hypothermia may protect against ischemia by regulating cascades that occur after reperfusion, including blood-brain barrier permeability and the changes in gene and protein expressions associated with necrotic and apoptotic pathways. Hypothermia not only blocks multiple damaging cascades after stroke, but also selectively upregulates some protective genes. However, most of these mechanisms are addressed in models with intraischemic hypothermia; much less information is available in models with postischemic hypothermia. Moreover, although it has been confirmed that mild hypothermia is clinically feasible for acute focal stroke treatment, no definite beneficial effect has been reported yet. This lack of clinical protection may result from suboptimal criteria for patient entrance into clinical trials. To facilitate clinical translation, future efforts in the laboratory should focus more on the protective mechanisms of postischemic hypothermia, as well as on the effects of sex, age and rewarming during reperfusion on hypothermic protection.
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Affiliation(s)
- Heng Zhao
- Department of Neurosurgery, Stanford University, Stanford, California 94305-5327, USA.
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Galasso SL, Dyck RH. The role of zinc in cerebral ischemia. MOLECULAR MEDICINE (CAMBRIDGE, MASS.) 2007; 13:380-7. [PMID: 17622314 PMCID: PMC1952671 DOI: 10.2119/2007–00044.galasso] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Received: 04/23/2007] [Accepted: 04/25/2007] [Indexed: 11/06/2022]
Abstract
Ischemic stroke is one of the most pervasive life-threatening neurological conditions for which there currently exists limited therapeutic intervention beyond prevention. As calcium-focused neuroprotective strategies have met with limited clinical success, it is imperative that alternative therapeutic targets be considered in the attempt to antagonize ischemic-mediated injury. As such, zinc, which is able to function both as a signaling mediator and neurotoxin, has been implicated in cerebral ischemia. While zinc was first purported to have a role in cerebral ischemia nearly twenty years ago, our understanding of how zinc mediates ischemic injury is still in its relative infancy. Within this review, we examine some of the studies by which zinc has exerted either neuroprotective or neurotoxic effects during global and focal cerebral ischemia.
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Affiliation(s)
- Sherri L Galasso
- Department of Psychology, University of Calgary, Calgary, Alberta, Canada
- Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada
| | - Richard H Dyck
- Department of Psychology, University of Calgary, Calgary, Alberta, Canada
- Department of Cell Biology and Anatomy, University of Calgary, Calgary, Alberta, Canada
- Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada
- Address correspondence and reprint requests to Richard H Dyck, Department of Psychology, University of Calgary, 2500 University Drive N.W. Calgary, Alberta T2N 1N4. Phone: 403-220-4206; Fax: 403-282-8249;
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Abstract
Ischemic stroke is one of the most pervasive life-threatening neurological conditions for which there currently exists limited therapeutic intervention beyond prevention. As calcium-focused neuroprotective strategies have met with limited clinical success, it is imperative that alternative therapeutic targets be considered in the attempt to antagonize ischemic-mediated injury. As such, zinc, which is able to function both as a signaling mediator and neurotoxin, has been implicated in cerebral ischemia. While zinc was first purported to have a role in cerebral ischemia nearly twenty years ago, our understanding of how zinc mediates ischemic injury is still in its relative infancy. Within this review, we examine some of the studies by which zinc has exerted either neuroprotective or neurotoxic effects during global and focal cerebral ischemia.
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Affiliation(s)
- Sherri L Galasso
- Department of Psychology, University of Calgary, Calgary, Alberta, Canada
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Suh SW, Frederickson CJ, Danscher G. Neurotoxic zinc translocation into hippocampal neurons is inhibited by hypothermia and is aggravated by hyperthermia after traumatic brain injury in rats. J Cereb Blood Flow Metab 2006; 26:161-9. [PMID: 15988476 DOI: 10.1038/sj.jcbfm.9600176] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Hypothermia reduces excitotoxic neuronal damage after seizures, cerebral ischemia and traumatic brain injury (TBI), while hyperthermia exacerbates damage from these insults. Presynaptic release of ionic zinc (Zn2+), translocation and accumulation of Zn2+ ions in postsynaptic neurons are important mechanisms of excitotoxic neuronal injury. We hypothesized that temperature-dependent modulation of excitotoxicity is mediated in part by temperature-dependent changes in the synaptic release and translocation of Zn2+. In the present studies, we used autometallographic (AMG) and fluorescent imaging of N-(6-methoxy-8-quinolyl)-para-toluenesulfonamide (TSQ) staining to quantify the influence of temperature on translocation of Zn2+ into hippocampal neurons in adult rats after weight drop-induced TBI. The central finding was that TBI-induced Zn2+ translocation is strongly influenced by brain temperature. Vesicular Zn2+ release was detected by AMG staining 1 h after TBI. At 30 degrees C, hippocampus showed almost no evidence of vesicular Zn2+ release from presynaptic terminals; at 36.5 degrees C, the hippocampus showed around 20% to 30% presynaptic vesicular Zn2+ release; and at 39 degrees C vesicular Zn2+ release was significantly greater (40% to 60%) than at 36.5 degrees C. At 6 h after TBI, intracellular Zn2+ accumulation was detected by the TSQ staining method, which showed that Zn2+ translocation also paralleled the vesicular Zn2+ release. Neuronal injury, assessed by counting eosinophilic neurons, also paralleled the translocation of Zn2+, being minimal at 30 degrees C and maximal at 39 degrees C. We conclude that pathological Zn2+ translocation in brain after TBI is temperature-dependent and that hypothermic neuronal protection might be mediated in part by reduced Zn2+ translocation.
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Affiliation(s)
- Sang Won Suh
- Department of Neurology, University of California, San Francisco, California 94121, USA.
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Abstract
Synaptically released zinc is thought to play an important role in neuronal signaling by modulating excitatory and inhibitory receptors and intracellular signaling proteins. Consequently, neurons that release zinc have been implicated in synaptic plasticity underlying learning and memory as well as neuropathological processes such as epilepsy, stroke, and Alzheimer's disease. To characterize the distribution of these neurons, investigators have relied on a technique that involves the retrograde transport of zinc-selenium crystals from axonal boutons to the cell bodies of origin. However, one major problem with this method is that labeling of cell bodies is obscured by high levels of staining in synaptic boutons, particularly within forebrain structures where this staining is most intense. Here, we used a modification of the retrograde labeling method that eliminates terminal staining for zinc, thereby enabling a clear and comprehensive description of these neurons. Zincergic neurons were found in all cerebral cortical regions and were arranged in a distinct laminar pattern, restricted to layers 2/3, 5, and 6 with no labeling in layer 4. In the hippocampus, labeling was present in CA1, CA3, and the dentate gyrus but not in CA2. Labeled cell bodies were also observed in most amygdaloid nuclei, anterior olfactory nuclei, claustrum, tenia tecta, endopiriform region, lateral ventricle, lateral septum, zona incerta, superior colliculus, and periaqueductal gray. Moreover, retrograde labeling was also noted in the dorsomedial and lateral hypothalamus, regions that previously were thought to be devoid of neurons with a zincergic phenotype. Collectively these data show that zincergic neurons comprise a large population of neurons in the murine forebrain and will provide an anatomical framework for understanding the functional importance of these neurons in the mammalian brain.
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Affiliation(s)
- Craig E Brown
- Department of Psychology, University of Calgary, Calgary, Alberta T2N 1N4, Canada
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