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Lemale CL, Lückl J, Horst V, Reiffurth C, Major S, Hecht N, Woitzik J, Dreier JP. Migraine Aura, Transient Ischemic Attacks, Stroke, and Dying of the Brain Share the Same Key Pathophysiological Process in Neurons Driven by Gibbs–Donnan Forces, Namely Spreading Depolarization. Front Cell Neurosci 2022; 16:837650. [PMID: 35237133 PMCID: PMC8884062 DOI: 10.3389/fncel.2022.837650] [Citation(s) in RCA: 23] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Accepted: 01/19/2022] [Indexed: 12/15/2022] Open
Abstract
Neuronal cytotoxic edema is the morphological correlate of the near-complete neuronal battery breakdown called spreading depolarization, or conversely, spreading depolarization is the electrophysiological correlate of the initial, still reversible phase of neuronal cytotoxic edema. Cytotoxic edema and spreading depolarization are thus different modalities of the same process, which represents a metastable universal reference state in the gray matter of the brain close to Gibbs–Donnan equilibrium. Different but merging sections of the spreading-depolarization continuum from short duration waves to intermediate duration waves to terminal waves occur in a plethora of clinical conditions, including migraine aura, ischemic stroke, traumatic brain injury, aneurysmal subarachnoid hemorrhage (aSAH) and delayed cerebral ischemia (DCI), spontaneous intracerebral hemorrhage, subdural hematoma, development of brain death, and the dying process during cardio circulatory arrest. Thus, spreading depolarization represents a prime and simultaneously the most neglected pathophysiological process in acute neurology. Aristides Leão postulated as early as the 1940s that the pathophysiological process in neurons underlying migraine aura is of the same nature as the pathophysiological process in neurons that occurs in response to cerebral circulatory arrest, because he assumed that spreading depolarization occurs in both conditions. With this in mind, it is not surprising that patients with migraine with aura have about a twofold increased risk of stroke, as some spreading depolarizations leading to the patient percept of migraine aura could be caused by cerebral ischemia. However, it is in the nature of spreading depolarization that it can have different etiologies and not all spreading depolarizations arise because of ischemia. Spreading depolarization is observed as a negative direct current (DC) shift and associated with different changes in spontaneous brain activity in the alternating current (AC) band of the electrocorticogram. These are non-spreading depression and spreading activity depression and epileptiform activity. The same spreading depolarization wave may be associated with different activity changes in adjacent brain regions. Here, we review the basal mechanism underlying spreading depolarization and the associated activity changes. Using original recordings in animals and patients, we illustrate that the associated changes in spontaneous activity are by no means trivial, but pose unsolved mechanistic puzzles and require proper scientific analysis.
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Affiliation(s)
- Coline L. Lemale
- Center for Stroke Research Berlin, Berlin Institute of Health, Charité – Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin, Germany
- Department of Experimental Neurology, Berlin Institute of Health, Charité – Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Janos Lückl
- Center for Stroke Research Berlin, Berlin Institute of Health, Charité – Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin, Germany
- Department of Medical Physics and Informatics, University of Szeged, Szeged, Hungary
- Department of Neurology, University of Szeged, Szeged, Hungary
| | - Viktor Horst
- Center for Stroke Research Berlin, Berlin Institute of Health, Charité – Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Clemens Reiffurth
- Center for Stroke Research Berlin, Berlin Institute of Health, Charité – Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin, Germany
- Department of Experimental Neurology, Berlin Institute of Health, Charité – Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Sebastian Major
- Center for Stroke Research Berlin, Berlin Institute of Health, Charité – Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin, Germany
- Department of Experimental Neurology, Berlin Institute of Health, Charité – Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin, Germany
- Department of Neurology, Berlin Institute of Health, Charité – Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Nils Hecht
- Department of Neurosurgery, Berlin Institute of Health, Charité – Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Johannes Woitzik
- Department of Neurosurgery, Evangelisches Krankenhaus Oldenburg, University of Oldenburg, Oldenburg, Germany
| | - Jens P. Dreier
- Center for Stroke Research Berlin, Berlin Institute of Health, Charité – Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin, Germany
- Department of Experimental Neurology, Berlin Institute of Health, Charité – Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin, Germany
- Department of Neurology, Berlin Institute of Health, Charité – Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin, Germany
- Bernstein Center for Computational Neuroscience Berlin, Berlin, Germany
- Einstein Center for Neurosciences Berlin, Berlin, Germany
- *Correspondence: Jens P. Dreier,
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Khadrawy YA, AboulEzz HS, Ahmed NA, Mohammed HS. The Anticonvulant Effect of Cooling in Comparison to α-Lipoic Acid: A Neurochemical Study. Neurochem Res 2013; 38:906-15. [DOI: 10.1007/s11064-013-0995-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2012] [Revised: 01/28/2013] [Accepted: 01/31/2013] [Indexed: 11/29/2022]
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Park S, Jung Y. Combined actions of Na/K-ATPase, NCX1 and glutamate dependent NMDA receptors in ischemic rat brain penumbra. Anat Cell Biol 2010; 43:201-10. [PMID: 21212860 PMCID: PMC3015038 DOI: 10.5115/acb.2010.43.3.201] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2010] [Revised: 08/26/2010] [Accepted: 09/10/2010] [Indexed: 11/27/2022] Open
Abstract
Instrumental role of Na+ and Ca2+ influx via Na+/K+ adenosine triphosphatase (Na+/K+-ATPase) and Na+/Ca2+ exchanger 1 (NCX1) is examined in the N-Methyl-D-aspartate (NMDA) receptor-mediated pathogenesis of penumbra after focal cerebral ischemia. An experimental model of 3, 6, and 24 h focal cerebral ischemia by permanent occlusion of middle cerebral artery was developed in rats. The changes in protein expression of Na+/K+-ATPase and NCX1 as well as functional subunits of NMDA receptor 2A and 2B (NR2A and NR2B) in the penumbra were assessed using by quantitative immunoblottings. The most prominent changes of Na+/K+-ATPase (78±6%, n=4, *P<0.05) and NCX1 (144±2%, n=4, *P<0.05) in the penumbra were developed 24 h after focal cerebral ischemia. The expression of NR2A in the penumbra was significantly increased (153±9%, n=4, *P<0.05) whereas the expression of NR2B was significantly decreased (37±2%, n=4, *P<0.05) as compared with sham-operated controls 3 h after focal cerebral ischemia. However, the expression of NR2A and NR2B in the penumbra was reversed 24 h after focal cerebral ischemia (NR2A: 40±7%; NR2B: 120±16%, n=4, *P<0.05). Moreover, the decreased expression of neuronal nuclei (NeuN) in the penumbra was most prominent than that of glial fibrillary acidic protein (GFAP) 24 h after focal cerebral ischemia. These findings imply that intracellular Na+ accumulation via decreased Na+/K+-ATPase exacerbate the Ca2+ overload cooperated by the increased NCX1 and NR2B-containing NMDA receptor which may play an important role in the pathogenesis of the penumbra.
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Affiliation(s)
- Sungjin Park
- Department of Anatomy, College of Medicine, Dongguk University, Gyeongju, Korea
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Intracerebroventricular Administration of Ouabain to Rats Changes the Expression of NMDA Receptor Subunits in Cerebral Cortex and Hippocampus. Neurochem Res 2009; 34:1650-7. [DOI: 10.1007/s11064-009-9956-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2008] [Accepted: 03/11/2009] [Indexed: 01/29/2023]
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Golden WC, Martin LJ. Low-dose ouabain protects against excitotoxic apoptosis and up-regulates nuclear Bcl-2 in vivo. Neuroscience 2005; 137:133-44. [PMID: 16297565 DOI: 10.1016/j.neuroscience.2005.10.004] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2005] [Revised: 09/15/2005] [Accepted: 10/05/2005] [Indexed: 10/25/2022]
Abstract
Sodium-potassium ATPase (Na+,K+-ATPase) regulates the electrochemical gradient in cells, thereby providing fluid and ionic homeostasis. Additionally, interaction of the Na+,K+ pump with cardiac glycosides can activate intracellular signaling cascades (resulting in cell growth) and up-regulate transcription factors that promote cell survival. We used an in vivo excitotoxicity model to assess if Na+,K+-ATPase plays a role in neuronal apoptosis. After unilateral, intrastriatal injection of the glutamate receptor agonist kainic acid into postnatal day 7 rats, Na+,K+ pump function was increased at 12 h after excitotoxic challenge, and levels of neuron-specific enzyme subunits were preserved (up to 24 h after injection) in membrane-enriched striatal fractions. In addition, co-injection of kainic acid with a low-dose (0.01 nmol) of the cardiac glycoside ouabain significantly (P<0.05) reduced striatal apoptosis (at 24 h post-injection) without diminishing Na+,K+-ATPase activity. To evaluate the possible mechanisms for this neuroprotection, we examined the levels of nuclear factor kappa B and Bcl-2 after cardiac glycoside exposure. Low-dose ouabain increased nuclear Bcl-2 (but not nuclear factor kappa B) protein levels at 6 h post injection. Our results suggest that Na+,K+-ATPase allows for progression of apoptosis in excitotoxically-injured neurons, and that sublethal concentrations of ouabain provide neuroprotection against excitotoxicity. The mechanism for this ouabain neuroprotection could be intracellular cascades linked to the Na+,K+-ATPase-ouabain interaction that modulate subcellular Bcl-2 levels. Targeted, therapeutic inhibition of apoptosis through cardiac glycosides may represent an effective strategy against excitotoxicity-mediated neuronal injury.
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Affiliation(s)
- W C Golden
- Department of Pediatrics, Eudowood Neonatal Pulmonary Division, Johns Hopkins University School of Medicine, 600 North Wolfe Street, Nelson-Harvey 2-133, Baltimore, MD 21287, USA.
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Abstract
Mutations affecting ion channels and neuronal membrane excitability have been identified in Drosophila as well as in other organisms and characterized for their acute effects on behavior and neuronal function. However, the long-term effect of these perturbations on the maintenance of neuronal viability has not been studied in detail. Here we perform an initial survey of mutations affecting Na+ channels and K+ channels in Drosophila to investigate their effects on life span and neuronal viability as a function of age. We find that mutations that decrease membrane excitability as well as those that increase excitability can trigger neurodegeneration to varying degrees. Results of double-mutant interactions with dominant Na+/K+ ATPase mutations, which themselves cause severe neurodegeneration, suggest that excitotoxicity owing to hyperexcitability is insufficient to explain the resultant phenotype. Although the exact mechanisms remain unclear, our results suggest that there is an important link between maintenance of proper neuronal signaling and maintenance of long-term neuronal viability. Disruption of these signaling mechanisms in any of a variety of ways increases the incidence of neurodegeneration.
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Affiliation(s)
- Tim Fergestad
- Laboratory of Genetics, University of Wisconsin, Madison 53706, USA
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Omar AI, Hu B. Detection of early tissue injury in vivo using fluorescent cell death markers in rat dentate gyrus. Neurosci Lett 2003; 348:143-6. [PMID: 12932814 DOI: 10.1016/s0304-3940(03)00715-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Fluorescent markers of cell death offer superior selectivity and sensitivity, although their applicability in detecting tissue injury under in vivo conditions remains uncertain. Here we examined whether ethidium bromide and Hoechst 33342, two widely used markers for cell necrosis and apoptosis, can be used in vivo to detect different types of cell death induced by Na,K-ATPase inhibition. Microinfusion of fluorescent markers and ouabain was made unilaterally into adult rat dentate gyrus. It was found that, at different time points post-injury, dentate cells that were exposed to ouabain but not to vehicle control showed marked loss of membrane integrity and exhibited nuclear condensation, as revealed by ethidium bromide and Hoechst 33342 staining, respectively. However, this pattern of cell death was not associated with DNA fragmentation and formation of apoptotic bodies, suggesting involvement of atypical cell apoptosis.
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Affiliation(s)
- A I Omar
- Neuroscience, Ottawa Health Research Institute, Ottawa Hospital and University of Ottawa, Ontario, K1Y 4K9, Ottawa, Canada
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Kimura T, Griffin DE. Extensive immune-mediated hippocampal damage in mice surviving infection with neuroadapted Sindbis virus. Virology 2003; 311:28-39. [PMID: 12832200 DOI: 10.1016/s0042-6822(03)00110-7] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Viral infections of the central nervous system and immune responses to these infections cause a variety of neurological diseases. Infection of weanling mice with Sindbis virus causes acute nonfatal encephalomyelitis followed by clearance of infectious virus, but persistence of viral RNA. Infection with a neuroadapted strain of Sindbis virus (NSV) causes fatal encephalomyelitis, but passive transfer of immune serum after infection protects from fatal disease and infectious virus is cleared. To determine whether persistent NSV RNA is associated with neurological damage, we examined the brains of recovered mice and found progressive loss of the hippocampal gyrus, adjacent white matter, and deep cerebral cortex associated with mononuclear cell infiltration. Mice deficient in CD4(+) T cells showed less tissue loss, while mice lacking CD8(+) T cells showed lesions comparable to those in immunocompetent mice. Mice deficient in both CD4(+) and CD8(+) T cells developed severe tissue loss similar to immunocompetent mice and this was associated with extensive infiltration of macrophages. The number of CD4(+) cells and macrophage/microglial cells, but not CD8(+) cells, infiltrating the hippocampal gyrus was correlated with the number of terminal deoxynucleotidyltransferase-mediated dUTP nick end-labeling positive pyramidal neurons. These results suggest that CD4(+) T cells can promote progressive neuronal death and tissue injury, despite clearance of infectious virus.
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Affiliation(s)
- Takashi Kimura
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD 21205, USA
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Global loss of Na,K-ATPase and its nitric oxide-mediated regulation in a transgenic mouse model of amyotrophic lateral sclerosis. J Neurosci 2003. [PMID: 12514200 DOI: 10.1523/jneurosci.23-01-00043.2003] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Na,K-ATPase plays a critical role in energy metabolism and ion fluxes. Its loss was investigated in the G93A mouse model of amyotrophic lateral sclerosis (ALS) in which the mutation of Cu/Zn superoxide dismutase (SOD1) is thought to lead to aberrant oxidative damage. Observed losses in spinal cord Na,K-ATPase activity exceeded all expectations. All three catalytic subunit isoforms (alpha1, alpha2, alpha3) were reduced, and the global alpha subunit loss affected not just neurons, glia, and myelinated axon tracts but even ependymal and pial membranes. Decreases in Na,K-ATPase activity were greater than losses of protein, and there were losses of Na,K-ATPase alpha, but not beta, subunits. Together, these observations are consistent with selective degradation of the alpha subunit after damage. Overexpression of normal SOD1 does not cause ALS-like symptoms, but it has other known pathological effects. In transgenic mice overexpressed normal human SOD1 had a smaller but still considerable effect on Na,K-ATPase. Furthermore, the nitric oxide-mediated regulatory pathway for Na,K-ATPase inhibition was undetectable in spinal cord tissue slices from mice overexpressing either mutant or normal human SOD1. Na,K-ATPase activity did not respond to nitric oxide donors, and the free radical-dependent step of the pathway could not be bypassed by the addition of the downstream protein kinase G activator, 8-Br-cGMP. The data demonstrate that Na,K-ATPase is vulnerable to aberrant SOD1 activity, making it a potential contributing factor in disease pathology. Moreover, the global cellular distribution of Na,K-ATPase loss indicates that SOD1 overexpression is far-reaching in its pathological effects.
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Isaev NK, Stelmashook EV, Halle A, Harms C, Lautenschlager M, Weih M, Dirnagl U, Victorov IV, Zorov DB. Inhibition of Na(+),K(+)-ATPase activity in cultured rat cerebellar granule cells prevents the onset of apoptosis induced by low potassium. Neurosci Lett 2000; 283:41-4. [PMID: 10729629 DOI: 10.1016/s0304-3940(00)00903-4] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
In cerebellar granule cells in culture, lowering of extracellular [K(+)] results in apoptotic death (D'Mello, S.R., Galli, C., Ciotti, T. and Calissano, P., Induction of apoptosis in cerebellar granule neurons by low potassium: inhibition of death by insulin-like growth factor I and cAMP, Proc. Natl. Acad. Sci. USA, 90 (1993) 10989-10993). In this model, we studied the influence of Na(+), K(+)-ATPase inhibition on apoptosis. We demonstrate that cell death (93+/-2 vs. 46+/-1.6%) as well as fragmentation of nuclear DNA induced by low extracellular potassium were prevented by addition of ouabain (0.1 mM), a specific inhibitor of the Na(+),K(+)-ATPase. Blockade of glutamatergic N-methyl-D-aspartate and alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid receptors by 5-methyl-10,11-dihydro-5H-dibenzo(a,d)cyclohepten-5,10-imine hydrogen maleate (MK-801; 20 microM) and 6-Cyano-7-nitroquinoxaline-2,3-dione (CNQX; 50 microM) did not inhibit the protective effect of ouabain. 24 h treatment with ouabain also decreased cell death induced by Fe(2+)/ascorbic acid (74+/-2% to 49+/-3%). We speculate that ouabain pretreatment enhances the resistance against low [K(+)]-induced apoptosis independent of glutamate-receptor activation. Since this effect can be mimicked by a free-radical generating system, we suggest an antioxidative effect underlying ouabain-induced neuroprotection.
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Affiliation(s)
- N K Isaev
- A.N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, Moscow, Russia.
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Abstract
The Na+/Ca2+ exchanger, an ion transport protein, is expressed in the plasma membrane (PM) of virtually all animal cells. It extrudes Ca2+ in parallel with the PM ATP-driven Ca2+ pump. As a reversible transporter, it also mediates Ca2+ entry in parallel with various ion channels. The energy for net Ca2+ transport by the Na+/Ca2+ exchanger and its direction depend on the Na+, Ca2+, and K+ gradients across the PM, the membrane potential, and the transport stoichiometry. In most cells, three Na+ are exchanged for one Ca2+. In vertebrate photoreceptors, some neurons, and certain other cells, K+ is transported in the same direction as Ca2+, with a coupling ratio of four Na+ to one Ca2+ plus one K+. The exchanger kinetics are affected by nontransported Ca2+, Na+, protons, ATP, and diverse other modulators. Five genes that code for the exchangers have been identified in mammals: three in the Na+/Ca2+ exchanger family (NCX1, NCX2, and NCX3) and two in the Na+/Ca2+ plus K+ family (NCKX1 and NCKX2). Genes homologous to NCX1 have been identified in frog, squid, lobster, and Drosophila. In mammals, alternatively spliced variants of NCX1 have been identified; dominant expression of these variants is cell type specific, which suggests that the variations are involved in targeting and/or functional differences. In cardiac myocytes, and probably other cell types, the exchanger serves a housekeeping role by maintaining a low intracellular Ca2+ concentration; its possible role in cardiac excitation-contraction coupling is controversial. Cellular increases in Na+ concentration lead to increases in Ca2+ concentration mediated by the Na+/Ca2+ exchanger; this is important in the therapeutic action of cardiotonic steroids like digitalis. Similarly, alterations of Na+ and Ca2+ apparently modulate basolateral K+ conductance in some epithelia, signaling in some special sense organs (e.g., photoreceptors and olfactory receptors) and Ca2+-dependent secretion in neurons and in many secretory cells. The juxtaposition of PM and sarco(endo)plasmic reticulum membranes may permit the PM Na+/Ca2+ exchanger to regulate sarco(endo)plasmic reticulum Ca2+ stores and influence cellular Ca2+ signaling.
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Affiliation(s)
- M P Blaustein
- Departments of Physiology, University of Maryland School of Medicine, Baltimore, USA
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Obrenovitch TP, Urenjak J. Altered glutamatergic transmission in neurological disorders: from high extracellular glutamate to excessive synaptic efficacy. Prog Neurobiol 1997; 51:39-87. [PMID: 9044428 DOI: 10.1016/s0301-0082(96)00049-4] [Citation(s) in RCA: 238] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
This review is a critical appraisal of the widespread assumption that high extracellular glutamate, resulting from enhanced pre-synaptic release superimposed on deficient uptake and/or cytosolic efflux, is the key to excessive glutamate-mediated excitation in neurological disorders. Indeed, high extracellular glutamate levels do not consistently correlate with, nor necessarily produce, neuronal dysfunction and death in vivo. Furthermore, we exemplify with spreading depression that the sensitivity of an experimental or pathological event to glutamate receptor antagonists does not imply involvement of high extracellular glutamate levels in the genesis of this event. We propose an extension to the current, oversimplified concept of excitotoxicity associated with neurological disorders, to include alternative abnormalities of glutamatergic transmission which may contribute to the pathology, and lead to excitotoxic injury. These may include the following: (i) increased density of glutamate receptors; (ii) altered ionic selectivity of ionotropic glutamate receptors; (iii) abnormalities in their sensitivity and modulation; (iv) enhancement of glutamate-mediated synaptic efficacy (i.e. a pathological form of long-term potentiation); (v) phenomena such as spreading depression which require activation of glutamate receptors and can be detrimental to the survival of neurons. Such an extension would take into account the diversity of glutamate-receptor-mediated processes, match the complexity of neurological disorders pathogenesis and pathophysiology, and ultimately provide a more elaborate scientific basis for the development of innovative treatments.
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Affiliation(s)
- T P Obrenovitch
- Department of Neurochemistry, Institute of Neurology, London.
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