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Rajput P, Brookshier A, Kothari S, Eckstein L, Chang H, Liska S, Lamb J, Sances S, Lyden P. Differential Vulnerability and Response to Injury among Brain Cell Types Comprising the Neurovascular Unit. J Neurosci 2024; 44:e1093222024. [PMID: 38548341 PMCID: PMC11140689 DOI: 10.1523/jneurosci.1093-22.2024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2022] [Revised: 02/29/2024] [Accepted: 03/11/2024] [Indexed: 05/31/2024] Open
Abstract
The neurovascular unit (NVU) includes multiple different cell types, including neurons, astrocytes, endothelial cells, and pericytes, which respond to insults on very different time or dose scales. We defined differential vulnerability among these cell types, using response to two different insults: oxygen-glucose deprivation (OGD) and thrombin-mediated cytotoxicity. We found that neurons are most vulnerable, followed by endothelial cells and astrocytes. After temporary focal cerebral ischemia in male rats, we found significantly more injured neurons, compared with astrocytes in the ischemic area, consistent with differential vulnerability in vivo. We sought to illustrate different and shared mechanisms across all cell types during response to insult. We found that gene expression profiles in response to OGD differed among the cell types, with a paucity of gene responses shared by all types. All cell types activated genes relating to autophagy, apoptosis, and necroptosis, but the specific genes differed. Astrocytes and endothelial cells also activated pathways connected to DNA repair and antiapoptosis. Taken together, the data support the concept of differential vulnerability in the NVU and suggest that different elements of the unit will evolve from salvageable to irretrievable on different time scales while residing in the same brain region and receiving the same (ischemic) blood flow. Future work will focus on the mechanisms of these differences. These data suggest future stroke therapy development should target different elements of the NVU differently.
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Affiliation(s)
- Padmesh Rajput
- Department of Physiology and Neuroscience, Zilkha Neurogenetic Institute, Keck School of Medicine of USC, Los Angeles, California 90089-2821
| | - Allison Brookshier
- Department of Physiology and Neuroscience, Zilkha Neurogenetic Institute, Keck School of Medicine of USC, Los Angeles, California 90089-2821
| | - Shweta Kothari
- Chinook Therapeutics, Inc., Vancouver, British Columbia V5T 4T5, Canada
- Cedars-Sinai Medical Center, Los Angeles, California 90048
| | - Lillie Eckstein
- Department of Physiology and Neuroscience, Zilkha Neurogenetic Institute, Keck School of Medicine of USC, Los Angeles, California 90089-2821
| | - Heather Chang
- Department of Physiology and Neuroscience, Zilkha Neurogenetic Institute, Keck School of Medicine of USC, Los Angeles, California 90089-2821
| | - Sophie Liska
- Department of Physiology and Neuroscience, Zilkha Neurogenetic Institute, Keck School of Medicine of USC, Los Angeles, California 90089-2821
| | - Jessica Lamb
- Department of Physiology and Neuroscience, Zilkha Neurogenetic Institute, Keck School of Medicine of USC, Los Angeles, California 90089-2821
| | - Samuel Sances
- Cedars-Sinai Medical Center, Los Angeles, California 90048
| | - Patrick Lyden
- Department of Physiology and Neuroscience, Zilkha Neurogenetic Institute, Keck School of Medicine of USC, Los Angeles, California 90089-2821
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Brain Protection after Anoxic Brain Injury: Is Lactate Supplementation Helpful? Cells 2021; 10:cells10071714. [PMID: 34359883 PMCID: PMC8305209 DOI: 10.3390/cells10071714] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2021] [Revised: 07/02/2021] [Accepted: 07/05/2021] [Indexed: 11/17/2022] Open
Abstract
While sudden loss of perfusion is responsible for ischemia, failure to supply the required amount of oxygen to the tissues is defined as hypoxia. Among several pathological conditions that can impair brain perfusion and oxygenation, cardiocirculatory arrest is characterized by a complete loss of perfusion to the brain, determining a whole brain ischemic-anoxic injury. Differently from other threatening situations of reduced cerebral perfusion, i.e., caused by increased intracranial pressure or circulatory shock, resuscitated patients after a cardiac arrest experience a sudden restoration of cerebral blood flow and are exposed to a massive reperfusion injury, which could significantly alter cellular metabolism. Current evidence suggests that cell populations in the central nervous system might use alternative metabolic pathways to glucose and that neurons may rely on a lactate-centered metabolism. Indeed, lactate does not require adenosine triphosphate (ATP) to be oxidated and it could therefore serve as an alternative substrate in condition of depleted energy reserves, i.e., reperfusion injury, even in presence of adequate tissue oxygen delivery. Lactate enriched solutions were studied in recent years in healthy subjects, acute heart failure, and severe traumatic brain injured patients, showing possible benefits that extend beyond the role as alternative energetic substrates. In this manuscript, we addressed some key aspects of the cellular metabolic derangements occurring after cerebral ischemia-reperfusion injury and examined the possible rationale for the administration of lactate enriched solutions in resuscitated patients after cardiac arrest.
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Zimmerman B, Rypma B, Gratton G, Fabiani M. Age-related changes in cerebrovascular health and their effects on neural function and cognition: A comprehensive review. Psychophysiology 2021; 58:e13796. [PMID: 33728712 PMCID: PMC8244108 DOI: 10.1111/psyp.13796] [Citation(s) in RCA: 44] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2020] [Revised: 01/11/2021] [Accepted: 02/08/2021] [Indexed: 12/11/2022]
Abstract
The process of aging includes changes in cellular biology that affect local interactions between cells and their environments and eventually propagate to systemic levels. In the brain, where neurons critically depend on an efficient and dynamic supply of oxygen and glucose, age-related changes in the complex interaction between the brain parenchyma and the cerebrovasculature have effects on health and functioning that negatively impact cognition and play a role in pathology. Thus, cerebrovascular health is considered one of the main mechanisms by which a healthy lifestyle, such as habitual cardiorespiratory exercise and a healthful diet, could lead to improved cognitive outcomes with aging. This review aims at detailing how the physiology of the cerebral vascular system changes with age and how these changes lead to differential trajectories of cognitive maintenance or decline. This provides a framework for generating specific mechanistic hypotheses about the efficacy of proposed interventions and lifestyle covariates that contribute to enhanced cognitive well-being. Finally, we discuss the methodological implications of age-related changes in the cerebral vasculature for human cognitive neuroscience research and propose directions for future experiments aimed at investigating age-related changes in the relationship between physiology and cognitive mechanisms.
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Affiliation(s)
- Benjamin Zimmerman
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Bart Rypma
- School of Behavioral and Brain Sciences, University of Texas at Dallas, Richardson, TX, USA
- Department of Psychiatry, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Gabriele Gratton
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL, USA
- Department of Psychology, University of Illinois at Urbana-Champaign, Champaign, IL, USA
- Neuroscience Program, University of Illinois at Urbana-Champaign, Champaign, IL, USA
| | - Monica Fabiani
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL, USA
- Department of Psychology, University of Illinois at Urbana-Champaign, Champaign, IL, USA
- Neuroscience Program, University of Illinois at Urbana-Champaign, Champaign, IL, USA
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Reappraisal of anoxic spreading depolarization as a terminal event during oxygen-glucose deprivation in brain slices in vitro. Sci Rep 2020; 10:18970. [PMID: 33149164 PMCID: PMC7643106 DOI: 10.1038/s41598-020-75975-w] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2020] [Accepted: 10/22/2020] [Indexed: 12/20/2022] Open
Abstract
Anoxic spreading depolarization (aSD) has been hypothesized as a terminal event during oxygen–glucose deprivation (OGD) in submerged cortical slices in vitro. However, mechanical artifacts caused by aSD-triggered edema may introduce error in the assessment of neuronal viability. Here, using continuous patch-clamp recordings from submerged rat cortical slices, we first confirmed that vast majority of L4 neurons permanently lost their membrane potential during OGD-induced aSD. In some recordings, spontaneous transition from whole-cell to out-side out configuration occurred during or after aSD, and only a small fraction of neurons survived aSD with reperfusion started shortly after aSD. Secondly, to minimize artifacts caused by OGD-induced edema, cells were short-term patched following OGD episodes of various duration. Nearly half of L4 cells maintained membrane potential and showed the ability to spike-fire if reperfusion started less than 10 min after aSD. The probability of finding live neurons progressively decreased at longer reperfusion delays at a rate of about 2% per minute. We also found that neurons in L2/3 show nearly threefold higher resistance to OGD than neurons in L4. Our results suggest that in the OGD ischemia model, aSD is not a terminal event, and that the “commitment point” of irreversible damage occurs at variable delays, in the range of tens of minutes, after OGD-induced aSD in submerged cortical slices.
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Hwang S, Ham S, Lee SE, Lee Y, Lee GH. Hypoxia regulates the level of glutamic acid decarboxylase enzymes and interrupts inhibitory synapse stability in primary cultured neurons. Neurotoxicology 2018; 65:221-230. [DOI: 10.1016/j.neuro.2017.10.006] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2017] [Revised: 09/19/2017] [Accepted: 10/27/2017] [Indexed: 01/23/2023]
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Regional Differences in Cerebral Glucose Metabolism After Cardiac Arrest and Resuscitation in Rats Using [18F]FDG Positron Emission Tomography and Autoradiography. Neurocrit Care 2017; 28:370-378. [DOI: 10.1007/s12028-017-0445-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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Mushtaq G, Greig NH, Anwar F, Al-Abbasi FA, Zamzami MA, Al-Talhi HA, Kamal MA. Neuroprotective Mechanisms Mediated by CDK5 Inhibition. Curr Pharm Des 2016; 22:527-34. [PMID: 26601962 DOI: 10.2174/1381612822666151124235028] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2015] [Accepted: 11/24/2015] [Indexed: 12/30/2022]
Abstract
Cyclin-dependent kinase 5 (CDK5) is a proline-directed serine/threonine kinase belonging to the family of cyclin-dependent kinases. In addition to maintaining the neuronal architecture, CDK5 plays an important role in the regulation of synaptic plasticity, neurotransmitter release, neuron migration and neurite outgrowth. Although various reports have shown links between neurodegeneration and deregulation of cyclin-dependent kinases, the specific role of CDK5 inhibition in causing neuroprotection in cases of neuronal insult or in neurodegenerative diseases is not wellunderstood. This article discusses current evidence for the involvement of CDK5 deregulation in neurodegenerative disorders and neurodegeneration associated with stroke through various mechanisms. These include upregulation of cyclin D1 and overactivation of CDK5 mediated neuronal cell death pathways, aberrant hyperphosphorylation of human tau proteins and/or neurofilament proteins, formation of neurofibrillary lesions, excitotoxicity, cytoskeletal disruption, motor neuron death (due to abnormally high levels of CDK5/p25) and colchicine- induced apoptosis in cerebellar granule neurons. A better understanding of the role of CDK5 inhibition in neuroprotective mechanisms will help scientists and researchers to develop selective, safe and efficacious pharmacological inhibitors of CDK5 for therapeutic use against human neurodegenerative disorders, such as Alzheimer's disease, amyotrophic lateral sclerosis and neuronal loss associated with stroke.
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Affiliation(s)
- Gohar Mushtaq
- Department of Biochemistry, College of Science, King Abdulaziz University, Jeddah 21589, Saudi Arabia.
| | - Nigel H Greig
- Drug Design & Development Section, Translational Gerontology Branch, Intramural Research Program, National, Institute on Aging, National Institutes of Health, Biomedical Research Center, 251 Bayview Boulevard, Baltimore, MD 21224, USA.
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Wang X, Ma Z, Fu Z, Gao S, Yang L, Jin Y, Sun H, Wang C, Fan W, Chen L, Zheng QY, Bi G, Ma CL. Hydroxysafflor Yellow A Protects Neurons From Excitotoxic Death through Inhibition of NMDARs. ASN Neuro 2016; 8:8/2/1759091416642345. [PMID: 27067428 PMCID: PMC4828664 DOI: 10.1177/1759091416642345] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2015] [Accepted: 12/30/2015] [Indexed: 11/15/2022] Open
Abstract
Excessive glutamate release causes overactivation of N-methyl d-aspartate receptors (NMDARs), leading to excitatory neuronal damage in cerebral ischemia. Hydroxysafflor yellow A (HSYA), a compound extracted from Carthamus tinctorius L., has been reported to exert a neuroprotective effect in many pathological conditions, including brain ischemia. However, the underlying mechanism of HSYA's effect on neurons remains elusive. In the present study, we conducted experiments using patch-clamp recording of mouse hippocampal slices. In addition, we performed Ca2+ imaging, Western blots, as well as mitochondrial-targeted circularly permuted yellow fluorescent protein transfection into cultured hippocampal neurons in order to decipher the physiological mechanism underlying HSYA's neuroprotective effect. Through the electrophysiology experiments, we found that HSYA inhibited NMDAR-mediated excitatory postsynaptic currents without affecting α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor and γ-aminobutyric acid A-type receptor-mediated currents. This inhibitory effect of HSYA on NMDARs was concentration dependent. HSYA did not show any preferential inhibition of either N-methyl d-aspartate receptor subtype 2A- or N-methyl d-aspartate receptor subtype 2B- subunit-containing NMDARs. Additionally, HSYA exhibits a facilitatory effect on paired NMDAR-mediated excitatory postsynaptic currents. Furthermore, HSYA reduced the magnitude of NMDAR-mediated membrane depolarization currents evoked by oxygen-glucose deprivation, and suppressed oxygen-glucose deprivation–induced and NMDAR-dependent ischemic long-term potentiation, which is believed to cause severe reperfusion damage after ischemia. Through the molecular biology experiments, we found that HSYA inhibited the NMDA-induced and NMDAR-mediated intracellular Ca2+ concentration increase in hippocampal cultures, reduced apoptotic and necrotic cell deaths, and prevented mitochondrial damage. Together, our data demonstrate for the first time that HSYA protects hippocampal neurons from excitotoxic damage through the inhibition of NMDARs. This novel finding indicates that HSYA may be a promising pharmacological candidate for the treatment of brain ischemia.
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Affiliation(s)
- Xingtao Wang
- Department of Physiology, Binzhou Medical University, Yantai, Shandong, China "Brain stroke" Key Lab of Shandong Health Administration Institute, Binzhou Medical University, Yantai, Shandong, China Department of Internal Neurology, Affiliated Hospital of Binzhou Medical University, Binzhou, Shandong, China
| | - Zhiyuan Ma
- School of Public Economics and Administration, Shanghai University of Finance and Economics, Shanghai, China
| | - Zhongxiao Fu
- CAS Key Laboratory of Brain Function and Diseases, School of Life Science, University of Science and Technology of China, Hefei, Anhui, China
| | - Su Gao
- Department of Internal Neurology, Affiliated Hospital of Binzhou Medical University, Binzhou, Shandong, China
| | - Liu Yang
- Department of Physiology, Binzhou Medical University, Yantai, Shandong, China "Brain stroke" Key Lab of Shandong Health Administration Institute, Binzhou Medical University, Yantai, Shandong, China
| | - Yan Jin
- CAS Key Laboratory of Brain Function and Diseases, School of Life Science, University of Science and Technology of China, Hefei, Anhui, China
| | - Hui Sun
- Department of Physiology, Binzhou Medical University, Yantai, Shandong, China "Brain stroke" Key Lab of Shandong Health Administration Institute, Binzhou Medical University, Yantai, Shandong, China
| | - Chaoyun Wang
- Department of Pharmacology, Binzhou Medical University, Yantai, Shandong, China
| | - Weiming Fan
- Department of Internal Neurology, Affiliated Hospital of Binzhou Medical University, Binzhou, Shandong, China
| | - Lin Chen
- CAS Key Laboratory of Brain Function and Diseases, School of Life Science, University of Science and Technology of China, Hefei, Anhui, China
| | - Qing-Yin Zheng
- Department of Internal Neurology, Affiliated Hospital of Binzhou Medical University, Binzhou, Shandong, China
| | - Guoqiang Bi
- CAS Key Laboratory of Brain Function and Diseases, School of Life Science, University of Science and Technology of China, Hefei, Anhui, China
| | - Chun-Lei Ma
- Department of Physiology, Binzhou Medical University, Yantai, Shandong, China "Brain stroke" Key Lab of Shandong Health Administration Institute, Binzhou Medical University, Yantai, Shandong, China
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Hübel N, Andrew RD, Ullah G. Large extracellular space leads to neuronal susceptibility to ischemic injury in a Na+/K+ pumps-dependent manner. J Comput Neurosci 2016; 40:177-92. [PMID: 26852334 DOI: 10.1007/s10827-016-0591-y] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2015] [Revised: 01/17/2016] [Accepted: 01/21/2016] [Indexed: 11/29/2022]
Abstract
The extent of anoxic depolarization (AD), the initial electrophysiological event during ischemia, determines the degree of brain region-specific neuronal damage. Neurons in higher brain regions exhibiting nonreversible, strong AD are more susceptible to ischemic injury as compared to cells in lower brain regions that exhibit reversible, weak AD. While the contrasting ADs in different brain regions in response to oxygen-glucose deprivation (OGD) is well established, the mechanism leading to such differences is not clear. Here we use computational modeling to elucidate the mechanism behind the brain region-specific recovery from AD. Our extended Hodgkin-Huxley (HH) framework consisting of neural spiking dynamics, processes of ion accumulation, and ion homeostatic mechanisms unveils that glial-vascular K(+) clearance and Na(+)/K(+)-exchange pumps are key to the cell's recovery from AD. Our phase space analysis reveals that the large extracellular space in the upper brain regions leads to impaired Na(+)/K(+)-exchange pumps so that they function at lower than normal capacity and are unable to bring the cell out of AD after oxygen and glucose is restored.
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Affiliation(s)
- Niklas Hübel
- Department of Physics, University of South Florida, Tampa, FL, 33620, USA.
| | - R David Andrew
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, ON, Canada
| | - Ghanim Ullah
- Department of Physics, University of South Florida, Tampa, FL, 33620, USA
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Ma S, You S, Hao L, Zhang D, Quan L. Fatal mechanical asphyxia induces changes in energy utilization in the rat brain: An (18)F-FDG-PET study. Leg Med (Tokyo) 2015; 17:239-44. [PMID: 25725531 DOI: 10.1016/j.legalmed.2015.02.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2014] [Revised: 01/16/2015] [Accepted: 02/10/2015] [Indexed: 10/24/2022]
Abstract
PURPOSE This study was designed to evaluate changes in brain glucose metabolism in rats following ligature strangulation. MATERIALS AND METHODS Thirteen male Wistar rats were used in the present study, divided into control (n=7) and asphyxia groups (n=6, ligature strangulation). Positron emission tomography (PET) with 2-deoxy-2-[(18)F]fluoro-D-glucose ((18)F-FDG) was used to evaluate brain glucose metabolism. Rats were scanned for PET-CT, and image data co-registered with a T2WI MRI template using SPM8 software. Image J was employed to draw regions of interest (ROIs) from the MRI template and acquire ROI activity information from the PET images. RESULTS In the asphyxia group vs. controls, (18)F-FDG uptake (FU) was decreased in the substantia nigra (25.26%, p<0.001), rhombencephalon (pons/medulla oblongata, 13.92%, p<0.01), hypothalamus (22.06%, p<0.01), ventral tegmentum (10.12%, p<0.05) and amygdala (12.74%, p<0.05); however, FU was increased in motor (18.21%, p<0.05) and visual cortices (19.2%, p<0.05). CONCLUSIONS The glucose metabolism distribution map in the asphyxiated rat brains were substantially changed versus controls. PET with (18)F-FDG can demonstrate excitement and inhibition of different brain areas even in cases of ligature strangulation.
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Affiliation(s)
- Suhua Ma
- Department of Forensic Pathology, Zhongshan School of Medicine, Sun Yat-Sen University, 74 Zhongshan 2 Road, Guangzhou, Guangdong Province 510080, PR China
| | - Shengzhong You
- Department of Forensic Pathology, Zhongshan School of Medicine, Sun Yat-Sen University, 74 Zhongshan 2 Road, Guangzhou, Guangdong Province 510080, PR China
| | - Li Hao
- Department of Forensic Pathology, Zhongshan School of Medicine, Sun Yat-Sen University, 74 Zhongshan 2 Road, Guangzhou, Guangdong Province 510080, PR China
| | - Dongchuan Zhang
- Department of Forensic Pathology, Zhongshan School of Medicine, Sun Yat-Sen University, 74 Zhongshan 2 Road, Guangzhou, Guangdong Province 510080, PR China
| | - Li Quan
- Department of Forensic Pathology, Zhongshan School of Medicine, Sun Yat-Sen University, 74 Zhongshan 2 Road, Guangzhou, Guangdong Province 510080, PR China; Department of Legal Medicine, Osaka City University Medical School, Osaka 545-8585, Japan.
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Geiseler SJ, Ludvigsen S, Folkow LP. KATP-channels play a minor role in the protective hypoxic shut-down of cerebellar activity in eider ducks (Somateria mollissima). Neuroscience 2014; 284:751-758. [PMID: 25451290 DOI: 10.1016/j.neuroscience.2014.10.046] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2014] [Revised: 10/02/2014] [Accepted: 10/15/2014] [Indexed: 10/24/2022]
Abstract
Eider duck (Somateria mollissima) cerebellar neurons are highly tolerant toward hypoxia in vitro, which in part is due to a hypoxia-induced depression of their spontaneous activity. We have studied whether this response involves ATP-sensitive potassium (KATP) channels, which are known to be involved in the hypoxic/ischemic defense of mammalian neural and muscular tissues, by causing hyperpolarization and reduced ATP demand. Extracellular recordings in the Purkinje layer of isolated normoxic eider duck cerebellar slices showed that their spontaneous neuronal activity decreased significantly compared to in control slices when the KATP channel opener diazoxide (600 μM) was added (F1,70=92.781, p<0.001). Adding the KATP channel blocker tolbutamide (400 μM) 5 min prior to diazoxide completely abolished its effect (F1,55=39.639, p<0.001), strongly suggesting that these drugs have a similar mode of action in this avian species as in mammals. The spontaneous activity of slices treated with tolbutamide in combined hypoxia/chemical anoxia (95% N2-5% CO2 and 2 mM NaCN) was not significantly different from that of control slices (F1,203=0.071, p=0.791). Recovery from hypoxia/anoxia was, however, slightly but significantly weaker in tolbutamide-treated slices than in control slices (F1,137=15.539, p<0.001). We conclude that KATP channels are present in eider duck cerebellar neurons and are activated in hypoxia/anoxia, but that they do not play a key role in the protective shut-down response to hypoxia/anoxia.
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Affiliation(s)
- S J Geiseler
- Department of Arctic and Marine Biology, University of Tromsø - the Arctic University of Norway, Breivika, NO-9037 Tromsø, Norway.
| | - S Ludvigsen
- Department of Arctic and Marine Biology, University of Tromsø - the Arctic University of Norway, Breivika, NO-9037 Tromsø, Norway
| | - L P Folkow
- Department of Arctic and Marine Biology, University of Tromsø - the Arctic University of Norway, Breivika, NO-9037 Tromsø, Norway
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Bista P, Cerina M, Ehling P, Leist M, Pape HC, Meuth SG, Budde T. The role of two-pore-domain background K⁺ (K₂p) channels in the thalamus. Pflugers Arch 2014; 467:895-905. [PMID: 25346156 DOI: 10.1007/s00424-014-1632-x] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2014] [Revised: 10/09/2014] [Accepted: 10/12/2014] [Indexed: 12/15/2022]
Abstract
The thalamocortical system is characterized by two fundamentally different activity states, namely synchronized burst firing and tonic action potential generation, which mainly occur during the behavioral states of sleep and wakefulness, respectively. The switch between the two firing modes is crucially governed by the bidirectional modulation of members of the K2P channel family, namely tandem of P domains in a weakly inward rectifying K(+) (TWIK)-related acid-sensitive K(+) (TASK) and TWIK-related K(+) (TREK) channels, in thalamocortical relay (TC) neurons. Several physicochemical stimuli including neurotransmitters, protons, di- and multivalent cations as well as clinically used drugs have been shown to modulate K2P channels in these cells. With respect to modulation of these channels by G-protein-coupled receptors, PLCβ plays a unique role with both substrate breakdown and product synthesis exerting important functions. While the degradation of PIP2 leads to the closure of TREK channels, the production of DAG induces the inhibition of TASK channels. Therefore, TASK and TREK channels were found to be central elements in the control of thalamic activity modes. Since research has yet focused on identifying the muscarinic pathway underling the modulation of TASK and TREK channels in TC neurons, future studies should address other thalamic cell types and members of the K2P channel family.
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Affiliation(s)
- Pawan Bista
- Institut für Physiologie I, Westfälische Wilhelms-Universität, Robert-Koch-Str. 27a, 48149, Münster, Germany
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Abstract
Ischemic stroke is one of the leading causes of morbidity and mortality. Treatment options are limited and only a minority of patients receive acute interventions. Understanding the mechanisms that mediate neuronal injury and death may identify targets for neuroprotective treatments. Here we show that the aberrant activity of the protein kinase Cdk5 is a principal cause of neuronal death in rodents during stroke. Ischemia induced either by embolic middle cerebral artery occlusion (MCAO) in vivo or by oxygen and glucose deprivation in brain slices caused calpain-dependent conversion of the Cdk5-activating cofactor p35 to p25. Inhibition of aberrant Cdk5 during ischemia protected dopamine neurotransmission, maintained field potentials, and blocked excitotoxicity. Furthermore, pharmacological inhibition or conditional knock-out (CKO) of Cdk5 prevented neuronal death in response to ischemia. Moreover, Cdk5 CKO dramatically reduced infarctions following MCAO. Thus, targeting aberrant Cdk5 activity may serve as an effective treatment for stroke.
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Brisson CD, Hsieh YT, Kim D, Jin AY, Andrew RD. Brainstem neurons survive the identical ischemic stress that kills higher neurons: insight to the persistent vegetative state. PLoS One 2014; 9:e96585. [PMID: 24802253 PMCID: PMC4011844 DOI: 10.1371/journal.pone.0096585] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2014] [Accepted: 04/08/2014] [Indexed: 11/19/2022] Open
Abstract
Global ischemia caused by heart attack, pulmonary failure, near-drowning or traumatic brain injury often damages the higher brain but not the brainstem, leading to a ‘persistent vegetative state’ where the patient is awake but not aware. Approximately 30,000 U.S. patients are held captive in this condition but not a single research study has addressed how the lower brain is preferentially protected in these people. In the higher brain, ischemia elicits a profound anoxic depolarization (AD) causing neuronal dysfunction and vasoconstriction within minutes. Might brainstem nuclei generate less damaging AD and so be more resilient? Here we compared resistance to acute injury induced from simulated ischemia by ‘higher’ hippocampal and striatal neurons versus brainstem neurons in live slices from rat and mouse. Light transmittance (LT) imaging in response to 10 minutes of oxygen/glucose deprivation (OGD) revealed immediate and acutely damaging AD propagating through gray matter of neocortex, hippocampus, striatum, thalamus and cerebellar cortex. In adjacent brainstem nuclei, OGD-evoked AD caused little tissue injury. Whole-cell patch recordings from hippocampal and striatal neurons under OGD revealed sudden membrane potential loss that did not recover. In contrast brainstem neurons from locus ceruleus and mesencephalic nucleus as well as from sensory and motor nuclei only slowly depolarized and then repolarized post-OGD. Two-photon microscopy confirmed non-recoverable swelling and dendritic beading of hippocampal neurons during OGD, while mesencephalic neurons in midbrain appeared uninjured. All of the above responses were mimicked by bath exposure to 100 µM ouabain which inhibits the Na+/K+ pump or to 1–10 nM palytoxin which converts the pump into an open cationic channel. Therefore during ischemia the Na+/K+ pump of higher neurons fails quickly and extensively compared to naturally resilient hypothalamic and brainstem neurons. The selective survival of lower brain regions that maintain vital functions will support the persistent vegetative state.
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Affiliation(s)
- C. Devin Brisson
- Department of Biomedical & Molecular Sciences, Queen's University, Kingston, Ontario, Canada
| | - Yi-Ting Hsieh
- Department of Biomedical & Molecular Sciences, Queen's University, Kingston, Ontario, Canada
| | - Danielle Kim
- Department of Biomedical & Molecular Sciences, Queen's University, Kingston, Ontario, Canada
| | - Albert Y. Jin
- Department of Biomedical & Molecular Sciences, Queen's University, Kingston, Ontario, Canada
| | - R. David Andrew
- Department of Biomedical & Molecular Sciences, Queen's University, Kingston, Ontario, Canada
- * E-mail:
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Brisson CD, Lukewich MK, Andrew RD. A distinct boundary between the higher brain's susceptibility to ischemia and the lower brain's resistance. PLoS One 2013; 8:e79589. [PMID: 24223181 PMCID: PMC3819273 DOI: 10.1371/journal.pone.0079589] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2013] [Accepted: 10/03/2013] [Indexed: 11/19/2022] Open
Abstract
Higher brain regions are more susceptible to global ischemia than the brainstem, but is there a gradual increase in vulnerability in the caudal-rostral direction or is there a discrete boundary? We examined the interface between `higher` thalamus and the hypothalamus the using live brain slices where variation in blood flow is not a factor. Whole-cell current clamp recording of 18 thalamic neurons in response to 10 min O2/glucose deprivation (OGD) revealed a rapid anoxic depolarization (AD) from which thalamic neurons do not recover. Newly acquired neurons could not be patched following AD, confirming significant regional thalamic injury. Coinciding with AD, light transmittance (LT) imaging during whole-cell recording showed an elevated LT front that initiated in midline thalamus and that propagated into adjacent hypothalamus. However, hypothalamic neurons patched in paraventricular nucleus (PVN, n= 8 magnocellular and 12 parvocellular neurons) and suprachiasmatic nucleus (SCN, n= 18) only slowly depolarized as AD passed through these regions. And with return to control aCSF, hypothalamic neurons repolarized and recovered their input resistance and action potential amplitude. Moreover, newly acquired hypothalamic neurons could be readily patched following exposure to OGD, with resting parameters similar to neurons not previously exposed to OGD. Thalamic susceptibility and hypothalamic resilience were also observed following ouabain exposure which blocks the Na+/K+ pump, evoking depolarization similar to OGD in all neuronal types tested. Finally, brief exposure to elevated [K+]o caused spreading depression (SD, a milder, AD-like event) only in thalamic neurons so SD generation is regionally correlated with strong AD. Therefore the thalamus-hypothalamus interface represents a discrete boundary where neuronal vulnerability to ischemia is high in thalamus (like more rostral neocortex, striatum, hippocampus). In contrast hypothalamic neurons are comparatively resistant, generating weaker and recoverable anoxic depolarization similar to brainstem neurons, possibly the result of a Na/K pump that better functions during ischemia.
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Affiliation(s)
- C. Devin Brisson
- Department of Biomedical and Molecular Sciences, Queen’s University, Kingston, Ontario, Canada
| | - Mark K. Lukewich
- Department of Biomedical and Molecular Sciences, Queen’s University, Kingston, Ontario, Canada
| | - R. David Andrew
- Department of Biomedical and Molecular Sciences, Queen’s University, Kingston, Ontario, Canada
- * E-mail:
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Brisson CD, Andrew RD. A neuronal population in hypothalamus that dramatically resists acute ischemic injury compared to neocortex. J Neurophysiol 2012; 108:419-30. [PMID: 22514289 DOI: 10.1152/jn.00090.2012] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Pyramidal neurons (PyNs) of the cortex are highly susceptible to acute stroke damage, yet "lower" brain regions like hypothalamus and brain stem better survive global ischemia. Here we show for the first time that a "lower" neuron population intrinsically resists acute strokelike injury. In rat brain slices deprived of oxygen and glucose (OGD), we imaged anoxic depolarization (AD) as it propagated through neocortex or hypothalamus. AD, the initial electrophysiological event of stroke, is a front of depolarization that drains residual energy in compromised gray matter. The extent of AD reliably determines ensuing cortical damage, but do all CNS neurons generate a robust AD? During 10 min of OGD, PyNs depolarize without functional recovery. In contrast, magnocellular neuroendocrine cells (MNCs) in hypothalamus under identical stress generate a weak and delayed AD, resist complete depolarization, and rapidly repolarize when oxygen and glucose are restored. They recover their membrane potential, input resistance, and spike amplitude and can survive multiple OGD exposures. Two-photon microscopy in slices derived from a fluorescent mouse line confirms this protection, revealing PyN swelling and dendritic beading after OGD, whereas MNCs are not injured. Exposure to the Na(+)-K(+)-ATPase inhibitor ouabain (100 μM) induces AD similar to OGD in both cell types. Moreover, elevated extracellular K(+) concentration ([K(+)](o)) evokes spreading depression (SD), a milder version of AD, in PyNs but not MNCs. Therefore overriding the pump by OGD, ouabain, or elevated [K(+)](o) evokes a propagating depolarization in higher gray matter but not in MNCs. We suggest that variation in Na(+)-K(+)-ATPase pump efficiency during ischemia injury determines whether a neuronal type succumbs to or resists stroke.
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Affiliation(s)
- C Devin Brisson
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada
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Christian Machado Ximenes J, Crisóstomo Lima Verde E, da Graça Naffah-Mazzacoratti M, Socorro de Barros Viana G. Valproic Acid, a Drug with Multiple Molecular Targets Related to Its Potential Neuroprotective Action. ACTA ACUST UNITED AC 2012. [DOI: 10.4236/nm.2012.31016] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Abstract
Excitotoxicity is the major cause of many neurologic disorders including stroke. Potassium currents modulate neuronal excitability and therefore influence the pathological process. A-type potassium current (I(A)) is one of the major voltage-dependent potassium currents, yet its roles in excitotoxic cell death are not well understood. We report that, following ischemic insults, the I(A) increases significantly in large aspiny (LA) neurons but not medium spiny (MS) neurons in the striatum, which correlates with the higher resistance of LA neurons to ischemia. Activation of protein kinase Cα increases I(A) in LA neurons after ischemia. Cultured neurons from transgenic mice lacking both Kv1.4 and Kv4.2 subunits exhibit an increased vulnerability to ischemic insults. Increase of I(A) by recombinant expression of Kv1.4 or Kv4.2 is sufficient in improving the survival of MS neurons against ischemic insults both in vitro and in vivo. These results, taken together, provide compelling evidence for a protective role of I(A) against ischemia.
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Patel JC, Witkovsky P, Coetzee WA, Rice ME. Subsecond regulation of striatal dopamine release by pre-synaptic KATP channels. J Neurochem 2011; 118:721-36. [PMID: 21689107 DOI: 10.1111/j.1471-4159.2011.07358.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
ATP-sensitive K(+) (K(ATP)) channels are composed of pore-forming subunits, typically Kir6.2 in neurons, and regulatory sulfonylurea receptor subunits. In dorsal striatum, activity-dependent H(2)O(2) produced from glutamate receptor activation inhibits dopamine release via K(ATP) channels. Sources of modulatory H(2)O(2) include striatal medium spiny neurons, but not dopaminergic axons. Using fast-scan cyclic voltammetry in guinea-pig striatal slices and immunohistochemistry, we determined the time window for H(2)O(2)/K(ATP)-channel-mediated inhibition and assessed whether modulatory K(ATP) channels are on dopaminergic axons. Comparison of paired-pulse suppression of dopamine release in the absence and presence of glibenclamide, a K(ATP)-channel blocker, or mercaptosuccinate, a glutathione peroxidase inhibitor that enhances endogenous H(2)O(2) levels, revealed a time window for inhibition of 500-1000 ms after stimulation. Immunohistochemistry demonstrated localization of Kir6.2 K(ATP)-channel subunits on dopaminergic axons. Consistent with the presence of functional K(ATP) channels on dopaminergic axons, K(ATP)-channel openers, diazoxide and cromakalim, suppressed single-pulse evoked dopamine release. Although cholinergic interneurons that tonically regulate dopamine release also express K(ATP) channels, diazoxide did not induce the enhanced frequency responsiveness of dopamine release seen with nicotinic-receptor blockade. Together, these studies reveal subsecond regulation of striatal dopamine release by endogenous H(2)O(2) acting at K(ATP) channels on dopaminergic axons, including a role in paired-pulse suppression.
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Affiliation(s)
- Jyoti C Patel
- Department of Neurosurgery, New York University School of Medicine, New York, New York 10016, USA.
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Monnerie H, Hsu FC, Coulter DA, Le Roux PD. Role of the NR2A/2B subunits of the N-methyl-D-aspartate receptor in glutamate-induced glutamic acid decarboxylase alteration in cortical GABAergic neurons in vitro. Neuroscience 2010; 171:1075-90. [PMID: 20923697 DOI: 10.1016/j.neuroscience.2010.09.050] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2010] [Revised: 09/22/2010] [Accepted: 09/23/2010] [Indexed: 12/21/2022]
Abstract
The vulnerability of brain neuronal cell subpopulations to neurologic insults varies greatly. Among cells that survive a pathological insult, for example ischemia or brain trauma, some may undergo morphological and/or biochemical changes that may compromise brain function. The present study is a follow-up of our previous studies that investigated the effect of glutamate-induced excitotoxicity on the GABA synthesizing enzyme glutamic acid decarboxylase (GAD65/67)'s expression in surviving DIV 11 cortical GABAergic neurons in vitro [Monnerie and Le Roux, (2007) Exp Neurol 205:367-382, (2008) Exp Neurol 213:145-153]. An N-methyl-D-aspartate receptor (NMDAR)-mediated decrease in GAD expression was found following glutamate exposure. Here we examined which NMDAR subtype(s) mediated the glutamate-induced change in GAD protein levels. Western blotting techniques on cortical neuron cultures showed that glutamate's effect on GAD proteins was not altered by NR2B-containing diheteromeric (NR1/NR2B) receptor blockade. By contrast, blockade of triheteromeric (NR1/NR2A/NR2B) receptors fully protected against a decrease in GAD protein levels following glutamate exposure. When receptor location on the postsynaptic membrane was examined, extrasynaptic NMDAR stimulation was observed to be sufficient to decrease GAD protein levels similar to that observed after glutamate bath application. Blocking diheteromeric receptors prevented glutamate's effect on GAD proteins after extrasynaptic NMDAR stimulation. Finally, NR2B subunit examination with site-specific antibodies demonstrated a glutamate-induced, calpain-mediated alteration in NR2B expression. These results suggest that glutamate-induced excitotoxic NMDAR stimulation in cultured GABAergic cortical neurons depends upon subunit composition and receptor location (synaptic vs. extrasynaptic) on the neuronal membrane. Biochemical alterations in surviving cortical GABAergic neurons in various disease states may contribute to the altered balance between excitation and inhibition that is often observed after injury.
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Affiliation(s)
- H Monnerie
- Department of Neurosurgery, University of Pennsylvania, Philadelphia, PA 19104, USA
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Wang H, Imamura Y, Ishibashi R, Chandana EPS, Yamamoto M, Noda M. The Reck tumor suppressor protein alleviates tissue damage and promotes functional recovery after transient cerebral ischemia in mice. J Neurochem 2010; 115:385-98. [PMID: 20796170 DOI: 10.1111/j.1471-4159.2010.06933.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
The extracellular matrix (ECM) is important for both structural integrity and functions of the brain. Matrix metalloproteinases (MMPs) play major roles in ECM-remodeling under both physiological and pathological conditions. Reversion-inducing cysteine-rich protein with Kazal motifs (Reck) is a membrane-anchored MMP-regulator implicated in coordinated regulation of pericellular proteolysis. Although patho-physiological importance of MMPs and another group of MMP-regulators, tissue inhibitor of metalloproteinases, in brain ischemia has been demonstrated, little is known about the role of Reck in this process. In this study, we found that Reck is up-regulated in hippocampus and penumbra of subventricular zone after transient cerebral ischemia in mice. Most of the Reck-positive cells found at day 2 after ischemia are positive for Nestin as well as Ki67 and localized to the CA2 region of the hippocampus. At day 7 after ischemia, the Reck-positive cells increased in number, extended processes, expressed the reactive astrocyte marker GFAP and the neuronal marker NF200, and were widely distributed in the hippocampus. In the mutant mice carrying single functional Reck allele (Reck+/-), tissue damage and cell death after cerebral ischemia were augmented, the recovery of long-term potentiation in the hippocampus was compromised, NR2C subunit of NMDA receptor was up-regulated, gelatinolytic activity of MMPs were up-regulated and laminin-immunoreactivity was reduced. Our data implicate Reck in protection of ECM/tissue integrity and promotion of functional recovery in the brain after transient cerebral ischemia.
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Affiliation(s)
- Huan Wang
- Department of Molecular Oncology, Kyoto University Graduate School of Medicine, Sakyo-ku, Kyoto, Japan
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Irreversible striatal neuroimaging abnormalities secondary to prolonged, uncontrolled diabetes mellitus in the setting of progressive focal neurological symptoms. Neurol Sci 2009; 31:57-60. [PMID: 19768377 DOI: 10.1007/s10072-009-0127-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2009] [Accepted: 08/21/2009] [Indexed: 10/20/2022]
Abstract
Hemichorea-hemiballisum in patients with hyperglycemia and striatal hyperintensity on T1-weighted magnetic resonance imaging is now an accepted clinical entity. Usually, both the clinical syndrome and neuroimaging abnormalities are reversible. A transient, reversible metabolic impairment within the basal ganglion has been considered a possible cause of this disorder. However, the pathophysiology remains to be unclear. We report a 56-year-old man with a prolonged, uncontrolled hyperglycemia (HbA1C: 13.8%) and striatal hyperintensity on T1-weighted MR imaging presenting as reversible focal neurological deficit and irreversible neuroimaging abnormalities on the fourth month when blood sugar was under control (HbA1C 6.0 mg/dl). We hypothesize that neuroimaging abnormalities in our case may be a sequence of an "ischemic insult" caused by prolonged, uncontrolled hyperglycemia. Whether the signal abnormalities on neuroimaging studies or the clinical syndrome are reversible (patients with HCHB) or irreversible (such as in our case) are based on the degree of ischemic damage.
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Diwakarla S, Mercer LD, Kardashsyan L, Chu PWY, Shin YS, Lau CL, Hughes MLR, Nagley P, Beart PM. GABAergic striatal neurons exhibit caspase-independent, mitochondrially mediated programmed cell death. J Neurochem 2009; 109 Suppl 1:198-206. [PMID: 19393028 DOI: 10.1111/j.1471-4159.2009.05937.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
GABAergic striatal neurons are compromised in basal ganglia pathologies and we analysed how insult nature determined their patterns of injury and recruitment of the intrinsic mitochondrial pathway during programmed cell death (PCD). Stressors affecting targets implicated in striatal neurodegeneration [3-morpholinylsydnoneimine (SIN-1), 3-nitropropionic acid (3-NP), NMDA, 3,5-dihydroxyphenylglycine (DHPG), and staurosporine (STS)] were compared in cultured GABAergic neurons from murine striatum by analyzing the progression of injury and its correlation with mitochondrial involvement, the redistribution of intermembrane space (IMS) proteins, and patterns of protease activation. Stressors produced PCD exhibiting slow-onset kinetics with time-dependent annexin-V labeling and eventual DNA fragmentation. IMS proteins including cytochrome c were differentially distributed, although stressors except STS produced early redistribution of apoptosis-inducing factor and Omi, suggestive of early recruitment of both caspase-dependent and caspase-independent signaling. In general, Bax mobilization to mitochondria appeared to promote IMS protein redistribution. Caspase 3 activation was prominent after STS, whereas NMDA and SIN-1 produced mainly calpain activation, and 3-NP and DHPG elicited a mixed profile of protease activation. PCD and redistribution of IMS proteins in striatal GABAergic neurons were canonical and insult-dependent, reflecting differential interplay between the caspase cascade and alternate cell death pathways.
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Affiliation(s)
- Shanti Diwakarla
- Brain Injury and Repair Program, Florey Neuroscience Institutes, The University of Melbourne, Parkville, Victoria, Australia
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Li Y, Lei Z, Xu ZC. Enhancement of inhibitory synaptic transmission in large aspiny neurons after transient cerebral ischemia. Neuroscience 2009; 159:670-81. [PMID: 19167464 DOI: 10.1016/j.neuroscience.2008.12.046] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2008] [Revised: 12/23/2008] [Accepted: 12/24/2008] [Indexed: 01/15/2023]
Abstract
Large aspiny neurons and most of the GABAergic interneurons survive transient cerebral ischemia while medium spiny neurons degenerate in 24 h. Expression of a long-term enhancement of excitatory transmission in medium spiny neurons but not in large aspiny neurons has been indicated to contribute to this selective vulnerability. Because neuronal excitability is determined by the counterbalance of excitation and inhibition, the present study examined inhibitory synaptic transmission in large aspiny neurons after ischemia in rats. Transient cerebral ischemia was induced for 22 min using the four-vessel occlusion method and whole-cell voltage-clamp recording was performed on striatal slices. The amplitudes of evoked inhibitory postsynaptic currents in large aspiny neurons were significantly increased at 3 and 24 h after ischemia, which was mediated by the increase of presynaptic release. Postsynaptic responses were depressed at 24 h after ischemia. Inhibitory postsynaptic currents could be evoked in large aspiny neurons at 24 h after ischemia, suggesting that they receive GABAergic inputs from the survived GABAergic interneurons. Muscimol, a GABA(A) receptor agonist, presynaptically facilitated inhibitory synaptic transmission at 24 h after ischemia. Such facilitation was dependent on the extracellular calcium and voltage-gated sodium channels. The present study demonstrates an enhancement of inhibitory synaptic transmission in large aspiny neurons after ischemia, which might reduce excitotoxicity and contribute, at least in part, to the survival of large aspiny neurons. Our data also suggest that large aspiny neurons might receive inhibitory inputs from GABAergic interneurons.
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Affiliation(s)
- Y Li
- Department of Anatomy and Cell Biology, Indiana University School of Medicine, 635 Barnhill Drive, MS 507, Indianapolis, IN 46202, USA
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25
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Electrophysiology and pharmacology of striatal neuronal dysfunction induced by mitochondrial complex I inhibition. J Neurosci 2008; 28:8040-52. [PMID: 18685029 DOI: 10.1523/jneurosci.1947-08.2008] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Reduced activity of the mitochondrial respiratory chain and in particular of complex I is implicated not only in the etiology of Parkinson's disease but also in other forms of parkinsonism in which striatal neurodegeneration occurs, such as progressive supranuclear palsy. The pesticide rotenone inhibits mitochondrial complex I and reproduces features of these basal ganglia neurological disorders in animal models. We have characterized the electrophysiological effects of rotenone in the striatum as well as potential neuroprotective strategies to counteract the detrimental effects of this neurotoxin. We found that rotenone causes a dose-dependent and irreversible loss of the corticostriatal field potential amplitude, which was related to the development of a membrane depolarization/inward current in striatal spiny neurons, coupled to an increased release of both excitatory amino acids and dopamine (DA). In particular, we have investigated whether glutamate, DA, and GABA systems might represent possible targets for neuroprotection against rotenone-induced striatal neuronal dysfunction. Interestingly, whereas modulation of glutamatergic transmission was not neuroprotective, blockade of D(2)-like but not D(1)-like DA receptors significantly reduced the rotenone-induced effects via a GABA-mediated mechanism. In addition, because antiepileptic drugs (AEDs) modulate multiple transmitter systems, we have analyzed the possible neuroprotective effects of some AEDs against rotenone. We found that carbamazepine, unlike other tested AEDs, exerts a potent neuroprotective action against rotenone-induced striatal neuronal dysfunction. This neuroprotection was observed at therapeutically relevant concentrations requiring endogenous GABA. Differential targeting of GABAergic transmission may represent a possible therapeutic strategy against basal ganglia neurodegenerative disorders involving mitochondrial complex I dysfunction.
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Glutamate alteration of glutamic acid decarboxylase (GAD) in GABAergic neurons: The role of cysteine proteases. Exp Neurol 2008; 213:145-53. [DOI: 10.1016/j.expneurol.2008.05.013] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2007] [Revised: 05/02/2008] [Accepted: 05/17/2008] [Indexed: 11/19/2022]
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Acetyl-l-Carnitine selectively prevents post-ischemic LTP via a possible action on mitochondrial energy metabolism. Neuropharmacology 2008; 55:223-9. [DOI: 10.1016/j.neuropharm.2008.05.015] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2008] [Revised: 05/16/2008] [Accepted: 05/16/2008] [Indexed: 11/30/2022]
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Deng P, Zhang Y, Xu ZC. Inhibition of Ih in striatal cholinergic interneurons early after transient forebrain ischemia. J Cereb Blood Flow Metab 2008; 28:939-47. [PMID: 18000510 DOI: 10.1038/sj.jcbfm.9600583] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Striatal cholinergic interneurons are relatively resistant to ischemic insults. These neurons express hyperpolarization-activated cation current (I(h)) that profoundly regulates neuronal excitability. Changes in neuronal excitability early after ischemia may be crucial for determining neuronal injury. Here we report that I(h) in cholinergic interneurons was decreased 3 h after transient forebrain ischemia, which was accompanied by a negative shift of the voltage dependence of activation. The inhibition of I(h) might be due to the tonic activation of adenosine A1 receptors, as blockade of A1 receptors significantly increased I(h) in postischemic neurons, but had no effect on control neurons. Consistent with the inhibition of I(h), postischemic neurons showed a reduction in both spontaneous firing and hyperpolarization-induced rebound depolarization. These findings indicate that I(h) may play excitatory roles in striatal cholinergic interneurons. Postischemic inhibition of I(h) might be a novel mechanism by which adenosine confers neuronal resistance to cerebral ischemia.
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Affiliation(s)
- Ping Deng
- Department of Anatomy and Cell Biology, Indiana University School of Medicine, Indianapolis, Indiana 46202, USA
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29
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Sakuma M, Hyakawa N, Kato H, Araki T. Time dependent changes of striatal interneurons after focal cerebral ischemia in rats. J Neural Transm (Vienna) 2008; 115:413-22. [PMID: 18301954 DOI: 10.1007/s00702-007-0860-z] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2007] [Accepted: 11/04/2007] [Indexed: 11/29/2022]
Abstract
The cellular damage over time and the alterations of neuronal subtypes was characterized in the striatum after 90-min middle cerebral artery occlusion and reperfusion in rats. We investigated the immunohistochemical alterations of choline acetyltransferase (ChAT)-positive (cholinergic-positive), gamma-aminobutyric acid (GABA)ergic parvalbumin (PV)-positive, GABAergic nNOS (neuronal nitric oxide synthase)-positive interneurons, neuronal nuclei (NeuN)-positive spiny projection neurons, glial fibrillary acidic protein (GFAP)-positive strocytes and microglial response factor-1 (MRF-1)-positive microglia in the striatum after focal cerebral ischemia in rats. In the present study, transient focal cerebral ischemia in rats caused severe damage against interneurons as well as spiny projection neurons in the striatum. In contrast, a significant increase in the number of GFAP-immunopositive astrocytes was observed in the ipsilateral striatum 15 days after focal cerebral ischemia. Furthermore, a significant increase of MRF-1 immunoreactivity was observed in microglia of the ipsilateral striatum 7 days and 15 days after focal cerebral ischemia. Among three types of cholinergic interneurons, GABAergic PV-positive interneurons and GABAergic nNOS-positive interneurons, the severe damage of cholinergic and GABAergic PV-positive interneurons was more pronounced than that of GABAergic nNOS-positive interneurons after transient focal cerebral ischemia in rats. Furthermore, the present results suggest that GABAergic nNOS-positive interneurons in the striatum after focal cerebral ischemia undergo cellular death in a delayed manner.
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Affiliation(s)
- M Sakuma
- Department of Neurobiology and Therapeutics, Graduate School and Faculty of Pharmaceutical Sciences, The University of Tokushima, Tokushima, Japan
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Centonze D, Rossi S, Tortiglione A, Picconi B, Prosperetti C, De Chiara V, Bernardi G, Calabresi P. Synaptic plasticity during recovery from permanent occlusion of the middle cerebral artery. Neurobiol Dis 2007; 27:44-53. [PMID: 17490888 DOI: 10.1016/j.nbd.2007.03.012] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2006] [Revised: 03/15/2007] [Accepted: 03/31/2007] [Indexed: 11/23/2022] Open
Abstract
Synaptic rearrangements in the peri-infarct regions are believed to contribute to the partial recovery of function that takes place after stroke. Here, we performed neurophysiological recordings from single neurons of rats with permanent occlusion of the middle cerebral artery (pMCAO) during the resolution of their neurological deficits. Our results show that complex and dynamic changes of glutamate transmission in the peri-infarct area parallel the recovery from brain infarct. We have observed that frequency and duration of spontaneous glutamate-mediated synaptic events were markedly increased in striatal neurons during the early phase of the recovery (3 days after pMCAO), due to potentiation of both NMDA (N-methyl-d-aspartate) and non-NMDA receptor-mediated transmission. In the late phase of recovery (7 days after pMCAO), glutamate transmission was still enhanced because of a selective facilitation of non-NMDA receptor-mediated transmission. Spiny projection neurons but not aspiny interneurons underwent detectable changes of synaptic excitability in the striatum following pMCAO, indicating that the process of neuronal adaptation after focal brain ischemia is cell-type-specific. Our results provide a synaptic correlate of the long-lasting brain hyperexcitability mediating recovery described with noninvasive neurophysiological approaches.
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Affiliation(s)
- Diego Centonze
- Clinica Neurologica, Dipartimento di Neuroscienze, Università Tor Vergata, Rome, Italy.
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Tortiglione A, Picconi B, Barone I, Centonze D, Rossi S, Costa C, Di Filippo M, Tozzi A, Tantucci M, Bernardi G, Annunziato L, Calabresi P. Na+/Ca2+ exchanger maintains ionic homeostasis in the peri-infarct area. Stroke 2007; 38:1614-20. [PMID: 17395860 DOI: 10.1161/strokeaha.106.478644] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
BACKGROUND AND PURPOSE A prominent feature of cerebral ischemia is the excessive intracellular accumulation of both Na(+) and Ca(2+) ions, which results in subsequent cell death. The plasma membrane Na(+)/Ca(2+) exchanger (NCX), regulates the distribution of these ions acting either in the forward mode or in its reverse mode and it can play a critical role in brain ischemia. However, it is unclear whether the activity of NCX leads to detrimental or beneficial effects. METHODS Extracellular field potentials and whole-cell patch clamp recordings were obtained from rat corticostriatal brain-slice preparations in the peri-infarct area 24 hours after the permanent middle cerebral artery occlusion. Ischemia was induced in rats by permanent middle cerebral artery occlusion. RESULTS Bepridil, an inhibitor of NCX, reduced in a concentration-dependent manner (IC(50)=68 micromol/L) the field potential amplitude recorded from the peri-infarct area of corticostriatal slices. Conversely, no change was observed in sham-operated animals. The effect of bepridil was mimicked by 5-(N-4-chlorobenzyl)-2',4'-dimethylbenzamil (CB-DMB) (IC(50)=6 micromol/L), a more selective inhibitor of NCX. In whole-cell patch clamp experiments, bepridil and CB-DMB caused an inward current in spiny neurons recorded from the peri-infarct area but not in the same cells recorded from controls. Interestingly, cholinergic interneurons recorded from the striatal peri-infarct area did not develop an inward current after the application of NCX inhibitors, suggesting that the electrophysiological alterations induced by NCX inhibition are cell-type specific. Bepridil and CB-DMB also induced a suppression of excitatory synaptic currents in most of spiny neurons recorded from the peri-infarct area. This effect was not coupled to a significant change of paired-pulse facilitation suggesting a postsynaptic site of action. CONCLUSIONS Our data indicate that NCX plays a critical role in the maintenance of ionic homeostasis in the peri-infarct area.
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Monnerie H, Le Roux PD. Reduced dendrite growth and altered glutamic acid decarboxylase (GAD) 65- and 67-kDa isoform protein expression from mouse cortical GABAergic neurons following excitotoxic injury in vitro. Exp Neurol 2007; 205:367-82. [PMID: 17433299 DOI: 10.1016/j.expneurol.2007.02.007] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2006] [Revised: 01/25/2007] [Accepted: 02/15/2007] [Indexed: 02/02/2023]
Abstract
The vulnerability of brain cells to neurologic insults varies greatly, depending on their neuronal subpopulation. However, cells surviving pathological insults such as ischemia or brain trauma may undergo structural changes, e.g., altered process growth, that could compromise brain function. In this study, we examined the effect of glutamate excitotoxicity on dendrite growth from surviving cortical GABAergic neurons in vitro. Glutamate exposure did not affect GABAergic neuron viability, however, it significantly reduced dendrite growth from GABAergic neurons. This effect was blocked by the AMPA receptor antagonists NBQX and CFM-2, and mimicked by AMPA, but not NMDA. Glutamate excitotoxicity also caused an NMDA receptor-mediated decrease in the GABA synthesizing enzyme glutamic acid decarboxylase (GAD65/67) immunoreactivity from GABAergic neurons, measured using immunocytochemical and Western blot techniques. GAD is necessary for GABA synthesis; however, reduction of GABA by 3-mercaptopropionic acid (3-MPA), which inhibits GABA synthesis, did not alter dendrite growth. These results suggest that GABAergic cortical neurons are relatively resistant to excitotoxic-induced cell death, but they can display morphological and biochemical alterations which may impair their function.
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Affiliation(s)
- Hubert Monnerie
- Department of Neurosurgery, University of Pennsylvania, 330 S 9th Street, 4th Floor, Philadelphia, PA 19107, USA
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Nisticò R, Piccirilli S, Sebastianelli L, Nisticò G, Bernardi G, Mercuri NB. The Blockade of K+‐ATP Channels has Neuroprotective Effects in an In Vitro Model of Brain Ischemia. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2007; 82:383-95. [PMID: 17678973 DOI: 10.1016/s0074-7742(07)82021-6] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
There is a common belief that the opening of K(+)-ATP channels during an ischemic episode has protective effects on neuronal functions by inducing a reduction in energy consumption. However, recent studies have also proposed that activation of these channels might have deleterious effects on cell's survival possibly after a stroke or during long-lasting neurodegenerative processes. Considering these contrasting results, we have used a hippocampal in vitro slice preparation in order to investigate the possible effects of K(+)-ATP channel blockers on the electrophysiological and morphological changes induced by a transient episode of ischemia (oxygen and glucose deprivation) on CA1 pyramidal neurons. Therefore, we found that tolbutamide and glibenclamide, both nonselective K(+)-ATP channel blockers, produce neuroprotective effects against in vitro ischemia. Interestingly, the mitochondrial K(+)-ATP channel blocker 5-hydroxydecanoate and various K(+) channel blockers did not exert neuroprotection. Our results are consistent with the concept that a decreased activity of the plasmalemmal K(+)-ATP conductances may have a protective effect during episodes of transient cerebral ischemia.
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Affiliation(s)
- Robert Nisticò
- Department of Experimental Neurology, S. Lucia Foundation IRCCS, Rome, Italy
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Pinheiro ACN, Gomez RS, Massensini AR, Cordeiro MN, Richardson M, Romano-Silva MA, Prado MAM, De Marco L, Gomez MV. Neuroprotective effect on brain injury by neurotoxins from the spider Phoneutria nigriventer. Neurochem Int 2006; 49:543-7. [PMID: 16759753 DOI: 10.1016/j.neuint.2006.04.009] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2006] [Accepted: 04/07/2006] [Indexed: 12/13/2022]
Abstract
The role of calcium channels blockers in ischemic condition has been well documented. The PhTx3 neurotoxic fraction of the spider Phoneutria nigriventer venom is a broad-spectrum calcium channel blocker that inhibits glutamate release, calcium uptake and also glutamate uptake in synaptosomes. In the present study we describe the effect of PhTx3 (1.0 microg/mL), omega-conotoxin GVIA (1.0 micromol/L) and omega-conotoxin MVIIC (100 nmol/L) on neuroprotection of hippocampal slices and SN56 cells subjected to ischemia by oxygen deprivation and low glucose insult (ODLG). After the insult, cell viability in the slices and SN56 cells was assessed by confocal microscopy and epifluorescence, using live/dead kit containing calcein-AM and ethidium homodimer. Confocal images of CA1 region of the rat hippocampal slices subjected to ischemia insult and treated with omega-conotoxin GVIA, omega-conotoxin MVIIC and PhTx3 showed a percentage of dead cells of 68%, 54% and 18%, respectively. The SN56 cells subjected to ischemia were almost completely protected from damage by PhTx3 while with omega-conotoxin GVIA or omega-conotoxin MVIIC the cell protection was only partial. Thus, PhTx3 provided robust ischemic neuroprotection showing potential as a novel class of agents that targets multiple components and exerts neuroprotection in in vitro model of brain ischemia.
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Affiliation(s)
- Ana C N Pinheiro
- Department of Pharmacology, ICB-UFMG, Av. Antonio Carlos 6627, Belo Horizonte 21270-901, Minas Gerais, Brazil
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Meuth SG, Kanyshkova T, Meuth P, Landgraf P, Munsch T, Ludwig A, Hofmann F, Pape HC, Budde T. Membrane Resting Potential of Thalamocortical Relay Neurons Is Shaped by the Interaction Among TASK3 and HCN2 Channels. J Neurophysiol 2006; 96:1517-29. [PMID: 16760342 DOI: 10.1152/jn.01212.2005] [Citation(s) in RCA: 89] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
By combining molecular biological, electrophysiological, immunological, and computer modeling techniques, we here demonstrate a counterbalancing contribution of TASK channels, underlying hyperpolarizing K+ leak currents, and HCN channels, underlying depolarizing Ih, to the resting membrane potential of thalamocortical relay (TC) neurons. RT-PCR experiments revealed the expression of TASK1, TASK3, and HCN1–4. Quantitative determination of mRNA expression levels and immunocytochemical staining demonstrated that TASK3 and HCN2 channels represent the dominant thalamic isoforms and are coexpressed in TC neurons. Extracellular acidification, a standard procedure to inhibit TASK channels, blocked a TASK current masked by additional action on HCN channels. Only in the presence of the HCN blocker ZD7288 was the pH-sensitive component typical for a TASK current, i.e., outward rectification and current reversal at the K+ equilibrium potential. In a similar way extracellular acidification was able to shift the activity pattern of TC neurons from burst to tonic firing only during block of Ih or genetic knock out of HCN channels. A single compartmental computer model of TC neurons simulated the counterbalancing influence of TASK and HCN on the resting membrane potential. It is concluded that TASK3 and HCN2 channels stabilize the membrane potential by a mutual functional interaction, that the most efficient way to regulate the membrane potential of TC neurons is the converse modulation of TASK and HCN channels, and that TC neurons are potentially more resistant to insults accompanied by extracellular pH shifts in comparison to other CNS regions.
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Affiliation(s)
- Sven G Meuth
- Neurologische Klinik, Bayerische Julius-Maximilians-Universität, Würzburg, Germany
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Costa C, Martella G, Picconi B, Prosperetti C, Pisani A, Di Filippo M, Pisani F, Bernardi G, Calabresi P. Multiple mechanisms underlying the neuroprotective effects of antiepileptic drugs against in vitro ischemia. Stroke 2006; 37:1319-26. [PMID: 16574927 DOI: 10.1161/01.str.0000217303.22856.38] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
BACKGROUND AND PURPOSE The possible neuroprotective effects of classic and new antiepileptic drugs on the electrophysiological changes induced by in vitro ischemia on striatal neurons were investigated. In particular, the aim of the study was to correlate the putative neuroprotective effects with the action of these drugs on fast sodium (Na+) and high-voltage-activated (HVA) calcium (Ca2+) currents. METHODS Extracellular field potentials were recorded from rat corticostriatal brain-slice preparations. In vitro ischemia was delivered by switching to an artificial cerebrospinal fluid solution in which glucose and oxygen were omitted. Na+ and HVA Ca2+ currents were analyzed by whole-cell patch-clamp recordings from acutely isolated rat striatal neurons. Excitatory postsynaptic potential was measured following synaptic stimulation in corticostriatal slices by sharp intracellular microelectrodes. RESULTS Neuroprotection against in vitro ischemia was observed in slices treated with carbamazepine (CBZ), valproic acid (VPA), and topiramate (TPM), whereas it was not achieved by using levetiracetam (LEV). Fast Na+ conductances were inhibited by CBZ and TPM, whereas VPA and LEV showed no effect. HVA Ca2+ conductances were reduced by CBZ, TPM, and LEV. VPA had no effect on this current. All antiepileptic drugs induced a small reduction of excitatory postsynaptic potential amplitude at concentrations higher than 100 microm without changes of paired-pulse facilitation. CONCLUSIONS The concomitant inhibition of fast Na+ and HVA Ca2+ conductances is critically important for the neuroprotection, whereas the presynaptic inhibition on glutamate transmission does not seem to play a major role.
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Affiliation(s)
- Cinzia Costa
- Clinica Neurologica, Università di Perugia, Ospedale Silvestrini, S. Andrea delle Fratte, Perugia, Italy
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Bao L, Avshalumov MV, Rice ME. Partial mitochondrial inhibition causes striatal dopamine release suppression and medium spiny neuron depolarization via H2O2 elevation, not ATP depletion. J Neurosci 2006; 25:10029-40. [PMID: 16251452 PMCID: PMC6725568 DOI: 10.1523/jneurosci.2652-05.2005] [Citation(s) in RCA: 89] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Mitochondrial dysfunction is a potential causal factor in Parkinson's disease. We show here that acute exposure to the mitochondrial complex I inhibitor rotenone (30-100 nM; 30 min) causes concentration-dependent suppression of single-pulse evoked dopamine (DA) release monitored in real time with carbon-fiber microelectrodes in guinea pig striatal slices, with no effect on DA content. Suppression of DA release was prevented by the sulfonylurea glibenclamide, implicating ATP-sensitive K+ (KATP) channels; however, tissue ATP was unaltered. Because KATP channels can be activated by hydrogen peroxide (H2O2), as well as by low ATP, we examined the involvement of rotenone-enhanced H2O2 generation. Confirming an essential role for H2O2, the inhibition of DA release by rotenone was prevented by catalase, a peroxide-scavenging enzyme. Striatal H2O2 generation during rotenone exposure was examined in individual medium spiny neurons using fluorescence imaging with dichlorofluorescein (DCF). An increase in intracellular H2O2 levels followed a similar time course to that of DA release suppression and was accompanied by cell membrane depolarization, decreased input resistance, and increased excitability. Extracellular catalase markedly attenuated the increase in DCF fluorescence and prevented rotenone-induced effects on membrane properties; membrane changes were also largely prevented by flufenamic acid, a blocker of transient receptor potential (TRP) channels. Thus, partial mitochondrial inhibition can cause functional DA denervation via H2O2 and KATP channels, without DA or ATP depletion. Furthermore, amplified H2O2 levels and TRP channel activation in striatal spiny neurons indicate potential sources of damage in these cells. Overall, these novel factors could contribute to parkinsonian motor deficits and neuronal degeneration caused by mitochondrial dysfunction.
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Affiliation(s)
- Li Bao
- Department of Physiology and Neuroscience, New York University School of Medicine, New York, New York 10016, USA
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Tsitolovsky LE. Protection from neuronal damage evoked by a motivational excitation is a driving force of intentional actions. ACTA ACUST UNITED AC 2005; 49:566-94. [PMID: 16269320 DOI: 10.1016/j.brainresrev.2005.02.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2004] [Revised: 12/16/2004] [Accepted: 02/25/2005] [Indexed: 01/13/2023]
Abstract
Motivation may be understood as an organism's subjective attitude to its current physiological state, which somehow modulates generation of actions until the organism attains an optimal state. How does this subjective attitude arise and how does it modulate generation of actions? Diverse lines of evidence suggest that elemental motivational states (hunger, thirst, fear, drug-dependence, etc.) arise as the result of metabolic disturbances and are related to transient injury, while rewards (food, water, avoidance, drugs, etc.) are associated with the recovery of specific neurons. Just as motivation and the very life of an organism depend on homeostasis, i.e., maintenance of optimum performance, so a neuron's behavior depends on neuronal (i.e., ion) homeostasis. During motivational excitation, the conventional properties of a neuron, such as maintenance of membrane potential and spike generation, are disturbed. Instrumental actions may originate as a consequence of the compensational recovery of neuronal excitability after the excitotoxic damage induced by a motivation. When the extent of neuronal actions is proportional to a metabolic disturbance, the neuron theoretically may choose a beneficial behavior even, if at each instant, it acts by chance. Homeostasis supposedly may be directed to anticipating compensation of the factors that lead to a disturbance of the homeostasis and, as a result, participates in the plasticity of motivational behavior. Following this line of thought, I suggest that voluntary actions arise from the interaction between endogenous compensational mechanisms and excitotoxic damage of specific neurons, and thus anticipate the exogenous compensation evoked by a reward.
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Affiliation(s)
- Lev E Tsitolovsky
- Department of Life Science, Bar-Ilan University, Ramat-Gan 52900, Israel.
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Zou B, Li Y, Deng P, Xu ZC. Alterations of potassium currents in ischemia-vulnerable and ischemia-resistant neurons in the hippocampus after ischemia. Brain Res 2005; 1033:78-89. [PMID: 15680342 DOI: 10.1016/j.brainres.2004.11.023] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/16/2004] [Indexed: 12/19/2022]
Abstract
CA1 pyramidal neurons in the hippocampus die 2-3 days following transient forebrain ischemia, whereas CA3 pyramidal neurons and granule cells in the dentate gyrus remain viable. Excitotoxicity is the major cause of ischemic cell death, and potassium currents play important roles in regulating the neuronal excitability. The present study compared the changes of potassium currents in acutely dissociated hippocampal neurons at different intervals after ischemia. In CA1 neurons, the amplitude of rapid inactivating potassium currents (I(A)) was significantly increased at 14 h and returned to control levels at 38 h after ischemia; the rising slope and decay time constant of I(A) were accordingly increased after ischemia. The activation curve of I(A) in CA1 neurons shifted to the depolarizing direction at 38 h after ischemia. In granule cells, the amplitude and rising slope of I(A) were significantly increased at 38 h after ischemia; the inactivation curves of I(A) shifted toward the depolarizing direction accordingly at 38 h after ischemia. The I(A) remained unchanged in CA3 neurons after ischemia. The amplitudes of delayed rectifier potassium currents (I(Kd)) in CA1 neurons were progressively increased after ischemia. No significant difference in I(Kd) was detected in CA3 and granule cells at any time points after reperfusion. These results indicated that the voltage dependent potassium currents in hippocampal neurons were differentially altered after cerebral ischemia. The up-regulation of I(A) in dentate granule cells might have protective effects. The increase of I(Kd) in CA1 neurons might be associated with the neuronal damage after ischemia.
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Affiliation(s)
- Bende Zou
- Department of Anatomy and Cell Biology, Indiana University School of Medicine, 635 Barnhill Drive, MS 507, Indianapolis, IN 46202, USA
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Deng P, Pang ZP, Zhang Y, Xu ZC. Increase of delayed rectifier potassium currents in large aspiny neurons in the neostriatum following transient forebrain ischemia. Neuroscience 2005; 131:135-46. [PMID: 15680698 DOI: 10.1016/j.neuroscience.2004.11.004] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/04/2004] [Indexed: 11/19/2022]
Abstract
Large aspiny (LA) neurons in the neostriatum are resistant to cerebral ischemia whereas spiny neurons are highly vulnerable to the same insult. Excitotoxicity has been implicated as the major cause of neuronal damage after ischemia. Voltage-dependent potassium currents play important roles in controlling neuronal excitability and therefore influence the ischemic outcome. To reveal the ionic mechanisms underlying the ischemia-resistance, the delayed rectifier potassium currents (Ik) in LA neurons were studied before and at different intervals after transient forebrain ischemia using brain slices and acute dissociation preparations. The current density of Ik increased significantly 24 h after ischemia and returned to control levels 72 h following reperfusion. Among currents contributing to Ik, the margatoxin-sensitive currents increased 24 h after ischemia while the KCNQ/M current remained unchanged after ischemia. Activation of protein kinase A (PKA) down-regulated Ik in both control and ischemic LA neurons, whereas inhibition of PKA only up-regulated Ik and margatoxin-sensitive currents 72 h after ischemia, indicating an active PKA regulation on Ik at this time. Protein tyrosine kinases had a tonic inhibition on Ik to a similar extent before and after ischemia. Compared with that of control neurons, the spike width was significantly shortened 24 h after ischemia due to facilitated repolarization, which could be reversed by blocking margatoxin-sensitive currents. The increase of Ik in LA neurons might be one of the protective mechanisms against ischemic insult.
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Affiliation(s)
- P Deng
- Department of Anatomy and Cell Biology, Indiana University School of Medicine, 635 Barnhill Drive, MS 507, Indianapolis, IN 46202, USA
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Mabuchi T, Lucero J, Feng A, Koziol JA, del Zoppo GJ. Focal cerebral ischemia preferentially affects neurons distant from their neighboring microvessels. J Cereb Blood Flow Metab 2005; 25:257-66. [PMID: 15678127 DOI: 10.1038/sj.jcbfm.9600027] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Developing cerebral infarction obscures the relationship of neurons to their local supply microvessels. We tested the notion that in the basal ganglia (i) an ordered relationship between neurons and their nearest neighboring microvessel exists, and (ii) focal ischemia predictably affects neuron integrity based on microvessel-neuron proximity. Distances between individual microvessels and their nearest neurons ([m-n distance]s) were measured in normal primates and ischemic subjects undergoing middle cerebral artery occlusion for 2 hours. An ordered microvessel-neuron relationship exists in the normal nonischemic basal ganglia within the early hours of focal ischemia. During ischemia normal (n) and sensitive (n*) neurons are interspersed. On average, neurons more distant from their nearest microvessel are most sensitive ([m-n distance]=16.2+/-11.2 microm versus [m-n* distance]=22.2+/-13.0 microm, 2P<0.00000001). Neurons not expressing glutamic acid decarboxylase were more likely to be sensitive than those with a normal microvessel-neuron relationship. In contrast, the [m-n distance] distribution of injured tyrosine hydroxylase-containing neurons was similar to those without tyrosine hydroxylase. Hence, the [m-n distance] relationship in the normal and ischemic basal ganglia is highly ordered, and distant neurons are consistently perturbed by ischemia, although this is not uniformly dependent on neurotransmitter type.
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Affiliation(s)
- Takuma Mabuchi
- Department of Molecular and Experimental Medicine, The Scripps Research Institute, La Jolla, California 92037, USA
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Pisani A, Bonsi P, Calabresi P. Calcium signaling and neuronal vulnerability to ischemia in the striatum. Cell Calcium 2005; 36:277-84. [PMID: 15261483 DOI: 10.1016/j.ceca.2004.02.010] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2004] [Accepted: 02/18/2004] [Indexed: 02/01/2023]
Abstract
Neurons express extremely different sensitivity to ischemic insults. The neuronal vulnerability is region-specific and the striatum is among the most susceptible areas to ischemic damage. Projecting GABAergic medium-sized neurons are very sensitive to energy metabolism impairment, whereas interneurons are selectively spared. However, the reasons for this differential vulnerability are largely unknown. Calcium ions (Ca2+) are important intracellular messengers enabling several physiological processes. However, excessive Ca2+ influx from the extracellular space or release from internal stores can elevate Ca2+ to levels that exceed the capacity of single neurons to appropriately buffer such overload. This capacity also appears to be a peculiar feature of single neuronal subtypes. This review will provide a brief survey of the ionic basis underlying the differential responses to in vitro ischemia of distinct striatal neuronal subtypes, mainly focusing on the role of Ca2+. The potential relevance of these findings in the development of therapeutic strategies for acute stroke will be discussed.
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Affiliation(s)
- Antonio Pisani
- Dipartimento di Neuroscienze, Clinica Neurologica, Università di Roma Tor Vergata, Fondazione Santa Lucia, IRCCS, Rome, Italy
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Klapstein GJ, Levine MS. Age-dependent biphasic changes in ischemic sensitivity in the striatum of Huntington's disease R6/2 transgenic mice. J Neurophysiol 2004; 93:758-65. [PMID: 15371492 DOI: 10.1152/jn.00483.2004] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We used the oxygen/glucose deprivation (OGD) model of ischemia in corticostriatal brain slices to test the hypothesis that metabolic deficiencies in R6/2 transgenic Huntington's disease (HD) mice will impair their recovery from an ischemic challenge. Corticostriatal extracellular field excitatory postsynaptic potentials (fEPSPs) were evoked in transgenic and wild-type (WT) mice in three age groups: 3-4 wk, before the overt behavioral phenotype develops; 5-9 wk, as overt behavioral symptoms begin; and 10-15 wk when symptoms were most severe. OGD for 8 min completely and reversibly inhibited fEPSPs. Although responses of 3-4 wk WTs showed a tolerance to ischemia and recovered rapidly, ischemic sensitivity developed progressively; at 5-9 and 10-15 wk, responses recovered more slowly from OGD. In contrast, although 3-4 wk R6/2 transgenic fEPSPs showed significantly more ischemic sensitivity than their WT counterparts, the R6/2 fEPSPs maintained a relative tolerance to ischemia at 5-9 and 10-15 wk. As a result, a "crossover" point occurred, roughly coinciding with the development of the overt behavioral phenotype (5-9 wk), after which time R6/2 fEPSPs were significantly more resistant to ischemia than WT responses. The increased ischemic sensitivity in 3-4 wk R6/2 responses was not due to excessive glutamate release during OGD as it persisted in the presence of the glutamate receptor antagonist kynurenic acid (1 mM). Although the mechanism for development of ischemic resistance in R6/2 transgenics remains unknown, it correlates with metabolic and biochemical changes described in this model and in HD patients.
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Affiliation(s)
- Gloria J Klapstein
- Mental Retardation Research Center, The David Geffen School of Medicine, University of California, Los Angeles, CA 90095, USA
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Wartenberg KE, Patsalides A, Yepes MS. Is Magnetic Resonance Spectroscopy Superior to Conventional Diagnostic Tools in Hypoxic-Ischemic Encephalopathy? J Neuroimaging 2004. [DOI: 10.1111/j.1552-6569.2004.tb00237.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
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Katchanov J, Waeber C, Gertz K, Gietz A, Winter B, Brück W, Dirnagl U, Veh RW, Endres M. Selective neuronal vulnerability following mild focal brain ischemia in the mouse. Brain Pathol 2004; 13:452-64. [PMID: 14655751 PMCID: PMC8095859 DOI: 10.1111/j.1750-3639.2003.tb00476.x] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
The evolution of cellular damage over time and the selective vulnerability of different neuronal subtypes was characterized in the striatum following 30-minute middle cerebral artery occlusion and reperfusion in the mouse. Using autoradiography we found an increase in the density of [3H]PK11195 binding sites--likely reflecting microglial activation--in the lesion border at 3 days and in the whole striatum from 10 days to 6 weeks. This was accompanied by a distinct loss of [3H]flumazenil and [3H]CGP39653 binding sites from 10 days up to 6 weeks reflecting neuronal loss. Brain ischemia resulted in a substantial loss of medium spiny projection neurons as seen at three days by Nissl staining, TUNEL and immunocytochemistry using antibodies against microtubule-associated protein (MAP2), NeuN, mu-opioid receptors, substance P, L-enkephalin, neurokinin B, choline acetyltransferase, parvalbumin, calretinin and somatostatin. Both patch and matrix compartments were involved in ischemic damage. In contrast, the numbers of cholinergic, GABAergic, and somatostatin-containing interneurons in the ischemic striatum were not different from those in the contralateral hemisphere at 3 and 14 days. A low density of glutamate receptors, the ability to sequester calcium by calcium-binding proteins and other hitherto unidentified factors may explain this relative resistance of interneurons to acute ischemia.
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Affiliation(s)
- Juri Katchanov
- Klinik und Poliklinik für Neurologie, Charité Campus Mitte, Humboldt‐Universität zu Berlin, Germany
| | - Christian Waeber
- Stroke and Neurovascular Regulation Laboratory, Massachusetts General Hospital, Harvard Medical School, Charlestown, Mass
| | - Karen Gertz
- Klinik und Poliklinik für Neurologie, Charité Campus Mitte, Humboldt‐Universität zu Berlin, Germany
| | - Andrea Gietz
- Klinik und Poliklinik für Neurologie, Charité Campus Mitte, Humboldt‐Universität zu Berlin, Germany
| | - Benjamin Winter
- Klinik und Poliklinik für Neurologie, Charité Campus Mitte, Humboldt‐Universität zu Berlin, Germany
| | - Wolfgang Brück
- Institut für Neuropathologie, Charité Campus Virchow, Humboldt‐Universität zu Berlin, Germany
| | - Ulrich Dirnagl
- Klinik und Poliklinik für Neurologie, Charité Campus Mitte, Humboldt‐Universität zu Berlin, Germany
| | - Rüdiger W. Veh
- Institut für Anatomie, Charité Campus Mitte, Humboldt‐Universität zu Berlin, Germany
| | - Matthias Endres
- Klinik und Poliklinik für Neurologie, Charité Campus Mitte, Humboldt‐Universität zu Berlin, Germany
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Takano H, Sugimura M, Kanazawa Y, Uchida T, Morishima Y, Shirasaki Y. Protective Effect of DY-9760e, a Calmodulin Antagonist, against Neuronal Cell Death. Biol Pharm Bull 2004; 27:1788-91. [PMID: 15516724 DOI: 10.1248/bpb.27.1788] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
An excessive elevation of intracellular Ca(2+) levels is known to play a key role in the pathological events following cerebral ischemia. DY-9760e, 3-[2-[4-(3-chloro-2-methylphenylmethyl)-1-piperazinyl]ethyl]-5,6-dimethoxy-1-(4-imidazolylmethyl)-1H-indazole dihydrochloride 3.5 hydrate, is a potent calmodulin antagonist that attenuates brain damage in focal ischemia models. In the present study, we investigated the effect of DY-9760e on neuronal cell death induced by a variety of cell-toxic stimuli that increase intracellular Ca(2+). Cell death was induced by the exposure of primary cultured neurons to excitotoxic agents such as glutamate and N-methyl-D-aspartate, membrane-depolarizing agents such as veratridine and high KCl, or thapsigargin an endoplasmic reticulum Ca(2+)-ATPase inhibitor. Treatment with DY-9760e resulted in a dose-dependent prevention of neuronal cell death elicited by excitotoxicity, voltage-gated channel opening, and inhibition of endoplasmic reticulum Ca(2+)-ATPase. These results indicate that DY-9760e can rescue neurons from various types of cell-toxic stimuli, which may contribute to attenuation of brain injury after cerebral ischemia.
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Affiliation(s)
- Hiromichi Takano
- New Product Research Laboratories II, Daiichi Pharmaceutical Co., Ltd., Tokyo, Japan
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Bonsi P, Calabresi P, De Persis C, Papa M, Centonze D, Bernardi G, Pisani A. Early ionic and membrane potential changes caused by the pesticide rotenone in striatal cholinergic interneurons. Exp Neurol 2004; 185:169-81. [PMID: 14697328 DOI: 10.1016/j.expneurol.2003.09.016] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Mitochondrial metabolism impairment has been implicated in the pathogenesis of several neurodegenerative disorders. In the present work, we combined electrophysiological recordings and microfluorometric measurements from cholinergic interneurons obtained from a rat neostriatal slice preparation. Acute application of the mitochondrial complex I inhibitor rotenone produced an early membrane hyperpolarization coupled to a fall in input resistance, followed by a late depolarizing response. Current-voltage relationship showed a reversal potential of -80 +/- 3 mV, suggesting the involvement of a potassium (K+) current. Simultaneous measurement of intracellular sodium [Na+]i or calcium [Ca2+]i concentrations revealed a striking correlation between [Na+]i elevation and the early membrane hyperpolarization, whereas a significant [Ca2+]i rise matched the depolarizing phase. Interestingly, ion and membrane potential changes were mimicked by ouabain, inhibitor of the Na+-K+ATPase, and were insensitive to tetrodotoxin (TTX) or to a combination of glutamate receptor antagonists. The rotenone effects were partially reduced by blockers of ATP-sensitive K+ channels, glibenclamide and tolbutamide, and largely attenuated by a low Na+-containing solution. Morphological analysis of the rotenone effects on striatal slices showed a significant decrease in the number of choline acetyltransferase (ChAT) immunoreactive cells. These results suggest that rotenone rapidly disrupts the ATP content, leading to a decreased Na+-K+ATPase function and, therefore, to [Na+]i overload. In turn, the hyperpolarizing response might be generated both by the opening of ATP-sensitive K+ channels and by Na+-activated K+ conductances. The increase in [Ca2+]i occurs lately and does not seem to influence the early events.
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Affiliation(s)
- P Bonsi
- Clinica Neurologica, Dipartimento di Neuroscienze, Università di Roma Tor Vergata, Fondazione Santa Lucia, IRCCS, 00133 Rome, Italy
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Abstract
Activity-dependent long-term potentiation (LTP) of excitatory neurotransmission underlies specific forms of associative learning and memory. A brief period of energy deprivation induces LTP in specific subsets of neurons; this synaptic plasticity might contribute to the delayed effects of brain ischaemia. In this review, we discuss the similarities and differences between LTP induced by energy deprivation and "physiological" LTP. On the basis of recent studies, we propose that pathological plasticity induced by energy deprivation can play a part in delayed neuronal death in the hippocampus and the striatum after global ischaemia and in the conversion of ischaemic penumbra to infarct core after focal ischaemia. We discuss evidence that ischaemia could also induce protective and reparative forms of neuronal plasticity that may play a part in ischaemic tolerance and poststroke recovery.
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Affiliation(s)
- Paolo Calabresi
- Clinica Neurologica, Dipartimento di Neuroscienze, Università Tor Vergata and the IRCCS Fondazione Santa Lucia, Rome, Italy.
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Marti M, Mela F, Ulazzi L, Hanau S, Stocchi S, Paganini F, Beani L, Bianchi C, Morari M. Differential responsiveness of rat striatal nerve endings to the mitochondrial toxin 3-nitropropionic acid: implications for Huntington's disease. Eur J Neurosci 2003; 18:759-67. [PMID: 12925002 DOI: 10.1046/j.1460-9568.2003.02806.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Rat striatal synaptosomes and slices were used to investigate the responsiveness of different populations of nerve terminals to 3-nitropropionic acid (3-NP), a suicide inhibitor of the mitochondrial enzyme succinate dehydrogenase, and to elucidate the ionic mechanisms involved. 3-NP (0.3-3 mm) stimulated spontaneous gamma-aminobutyric acid (GABA), glutamate and [3H]-dopamine efflux but left unchanged acetylcholine efflux from synaptosomes. This effect was associated with a >70% inhibition of succinate dehydrogenase, as measured in the whole synaptosomal population. The facilitation was not dependent on extracellular Ca2+ but relied on voltage-dependent Na+ channel opening, because it was prevented by tetrodotoxin and riluzole. 3-NP also elevated spontaneous glutamate efflux from slices but in a tetrodotoxin-insensitive way. To investigate whether energy depletion could change the responsiveness of nerve endings to a depolarizing stimulus, synaptosomes were pretreated with 3-NP and challenged with pulses of KCl evoking 'quasi-physiological' neurotransmitter release. 3-NP potentiated the K+-evoked GABA, glutamate and [3H]-dopamine release but inhibited the K+-evoked acetylcholine release. The 3-NP induced potentiation of GABA release was Ca2+-dependent and prevented by tetrodotoxin and riluzole whereas the 3-NP-induced inhibition of acetylcholine release was tetrodotoxin- and riluzole-insensitive but reversed by glipizide, an ATP-dependent K+ channel inhibitor. We conclude that the responsiveness of striatal nerve endings to 3-NP relies on activation of different ionic conductances, and suggest that the selective survival of striatal cholinergic interneurons following chronic 3-NP treatment (as in models of Huntington's disease) may rely on the opening of ATP-dependent K+ channels, which counteracts the fall in membrane potential as a result of mitochondrial impairment.
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Affiliation(s)
- Matteo Marti
- Department of Experimental and Clinical Medicine, Section of Pharmacology, via Fossato di Mortara 17-19, 44100 Ferrara, Italy
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Calabresi P, Cupini LM, Centonze D, Pisani F, Bernardi G. Antiepileptic drugs as a possible neuroprotective strategy in brain ischemia. Ann Neurol 2003; 53:693-702. [PMID: 12783414 DOI: 10.1002/ana.10603] [Citation(s) in RCA: 112] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Several new antiepileptic drugs (AEDs) have been introduced for clinical use recently. These new AEDs, as did the classic AEDs, target multiple cellular sites both pre- and postsynaptically. The major common goal of the pharmacological treatment using AEDs is to counteract abnormal brain excitability by either decreasing excitatory transmission or enhancing neuronal inhibition. Interestingly, an excessive release of excitatory amino acids and a reduced neuronal inhibition also occur in brain ischemia. Thus, recently, the use of AEDs as a possible neuroprotective strategy in brain ischemia is receiving increasing attention, and many AEDs have been tested in animal models of stroke, providing encouraging results. Experimental studies utilizing global or focal ischemia in rodents have provided insights into the possible neuroprotective action of the various AEDs. However, the implication of these studies in the treatment of acute stroke in humans is not always direct. In fact, various clinical studies with drugs targeting the same voltage- and ligand-gated channels modulated by most of the AEDs failed to show neuroprotection. The differential mechanisms that underlie the development of focal ischemic injury in experimental animal models versus human stroke require further investigation to open a new therapeutic perspective for neuroprotection that might be applicable in the future.
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Affiliation(s)
- Paolo Calabresi
- Clinica Neurologica, Dipartimento di Neuroscienze, Università di Roma Tor Vergata, Italy.
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