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Ringuette D, EbrahimAmini A, Sangphosuk W, Aquilino MS, Carroll G, Ashley M, Bazzigaluppi P, Dufour S, Droguerre M, Stefanovic B, Levi O, Charveriat M, Monnier PP, Carlen PL. Spreading depolarization suppression from inter-astrocytic gap junction blockade assessed with multimodal imaging and a novel wavefront detection scheme. Neurotherapeutics 2024; 21:e00298. [PMID: 38241157 PMCID: PMC10903093 DOI: 10.1016/j.neurot.2023.10.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2023] [Accepted: 10/07/2023] [Indexed: 01/21/2024] Open
Abstract
Spreading depolarizations (SDs) are an enigmatic and ubiquitous co-morbidity of neural dysfunction. SDs are propagating waves of local field depolarization and increased extracellular potassium. They increase the metabolic demand on brain tissue, resulting in changes in tissue blood flow, and are associated with adverse neurological consequences including stroke, epilepsy, neurotrauma, and migraine. Their occurrence is associated with poor patient prognosis through mechanisms which are only partially understood. Here we show in vivo that two (structurally dissimilar) drugs, which suppress astroglial gap junctional communication, can acutely suppress SDs. We found that mefloquine hydrochloride (MQH), administered IP, slowed the propagation of the SD potassium waveform and intermittently led to its suppression. The hemodynamic response was similarly delayed and intermittently suppressed. Furthermore, in instances where SD led to transient tissue swelling, MQH reduced observable tissue displacement. Administration of meclofenamic acid (MFA) IP was found to reduce blood flow, both proximal and distal, to the site of SD induction, preceding a large reduction in the amplitude of the SD-associated potassium wave. We introduce a novel image processing scheme for SD wavefront localization under low-contrast imaging conditions permitting full-field wavefront velocity mapping and wavefront parametrization. We found that MQH administration delayed SD wavefront's optical correlates. These two clinically used drugs, both gap junctional blockers found to distinctly suppress SDs, may be of therapeutic benefit in the various brain disorders associated with recurrent SDs.
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Affiliation(s)
- Dene Ringuette
- Department of Physiology, Faculty of Medicine, University of Toronto, 1 King's College Circle, Toronto, Ontario M5S 1A8, Canada; Division of Genetics and Development, Krembil Research Institute, 60 Leonard Ave., Toronto, Ontario M5T 2S8, Canada; Krembil Neuroscience, Krembil Research Institute, 60 Leonard Ave., Toronto, Ontario M5T 2S8, Canada.
| | - Azin EbrahimAmini
- Krembil Neuroscience, Krembil Research Institute, 60 Leonard Ave., Toronto, Ontario M5T 2S8, Canada; The Institute Biomedical Engineering, University of Toronto, 164 College St., Toronto, Ontario M5S 3G9, Canada
| | - Weerawong Sangphosuk
- Krembil Neuroscience, Krembil Research Institute, 60 Leonard Ave., Toronto, Ontario M5T 2S8, Canada
| | - Mark S Aquilino
- The Institute Biomedical Engineering, University of Toronto, 164 College St., Toronto, Ontario M5S 3G9, Canada
| | - Gwennyth Carroll
- The Institute Biomedical Engineering, University of Toronto, 164 College St., Toronto, Ontario M5S 3G9, Canada
| | - Max Ashley
- Krembil Neuroscience, Krembil Research Institute, 60 Leonard Ave., Toronto, Ontario M5T 2S8, Canada
| | - Paolo Bazzigaluppi
- Sunnybrook Health Sciences Center, 2075 Bayview Ave., Toronto, Ontario M4N 3M5, Canada
| | - Suzie Dufour
- The Institute Biomedical Engineering, University of Toronto, 164 College St., Toronto, Ontario M5S 3G9, Canada
| | | | - Bojana Stefanovic
- Department of Medical Biophysics, University of Toronto, 610 University Ave., Toronto, Ontario M5G 2M9, Canada; Sunnybrook Health Sciences Center, 2075 Bayview Ave., Toronto, Ontario M4N 3M5, Canada
| | - Ofer Levi
- The Institute Biomedical Engineering, University of Toronto, 164 College St., Toronto, Ontario M5S 3G9, Canada; The Edward S. Rogers Sr. Department of Electrical and Computer Engineering, University of Toronto, 10 King's College Rd., Toronto, Ontario M5S 3G4, Canada
| | | | - Philippe P Monnier
- Department of Physiology, Faculty of Medicine, University of Toronto, 1 King's College Circle, Toronto, Ontario M5S 1A8, Canada; Division of Genetics and Development, Krembil Research Institute, 60 Leonard Ave., Toronto, Ontario M5T 2S8, Canada; Department of Ophthalmology & Vision Science, Faculty of Medicine, University of Toronto, 340 College St., Toronto, Ontario M5T 3A9, Canada
| | - Peter L Carlen
- Department of Physiology, Faculty of Medicine, University of Toronto, 1 King's College Circle, Toronto, Ontario M5S 1A8, Canada; Division of Genetics and Development, Krembil Research Institute, 60 Leonard Ave., Toronto, Ontario M5T 2S8, Canada; Krembil Neuroscience, Krembil Research Institute, 60 Leonard Ave., Toronto, Ontario M5T 2S8, Canada; The Institute Biomedical Engineering, University of Toronto, 164 College St., Toronto, Ontario M5S 3G9, Canada
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Hanalioglu S, Taskiran-Sag A, Karatas H, Donmez-Demir B, Yilmaz-Ozcan S, Eren-Kocak E, Gursoy-Ozdemir Y, Dalkara T. Cortical spreading depression can be triggered by sensory stimulation in primed wild type mouse brain: a mechanistic insight to migraine aura generation. J Headache Pain 2022; 23:107. [PMID: 35986251 PMCID: PMC9392331 DOI: 10.1186/s10194-022-01474-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2022] [Accepted: 08/09/2022] [Indexed: 11/10/2022] Open
Abstract
Abstract
Background
Unlike the spontaneously appearing aura in migraineurs, experimentally, cortical spreading depression (CSD), the neurophysiological correlate of aura is induced by non-physiological stimuli. Consequently, neural mechanisms involved in spontaneous CSD generation, which may provide insight into how migraine starts in an otherwise healthy brain, remain largely unclear. We hypothesized that CSD can be physiologically induced by sensory stimulation in primed mouse brain.
Methods
Cortex was made susceptible to CSD with partial inhibition of Na+/K+-ATPase by epidural application of a low concentration of Na+/K+-ATPase blocker ouabain, allowing longer than 30-min intervals between CSDs or by knocking-down α2 subunit of Na+/K+-ATPase, which is crucial for K+ and glutamate re-uptake, with shRNA. Stimulation-triggered CSDs and extracellular K+ changes were monitored in vivo electrophysiologically and a K+-sensitive fluoroprobe (IPG-4), respectively.
Results
After priming with ouabain, photic stimulation significantly increased the CSD incidence compared with non-stimulated animals (44.0 vs. 4.9%, p < 0.001). Whisker stimulation also significantly increased the CSD incidence, albeit less effectively (14.9 vs. 2.4%, p = 0.02). Knocking-down Na+/K+-ATPase (50% decrease in mRNA) lowered the CSD threshold in all mice tested with KCl but triggered CSDs in 14.3% and 16.7% of mice with photic and whisker stimulation, respectively. Confirming Na+/K+-ATPase hypofunction, extracellular K+ significantly rose during sensory stimulation after ouabain or shRNA treatment unlike controls. In line with the higher CSD susceptibility observed, K+ rise was more prominent after ouabain. To gain insight to preventive mechanisms reducing the probability of stimulus-evoked CSDs, we applied an A1-receptor antagonist (DPCPX) to the occipital cortex, because adenosine formed during stimulation from ATP can reduce CSD susceptibility. DPCPX induced spontaneous CSDs but only small-DC shifts along with suppression of EEG spikes during photic stimulation, suggesting that the inhibition co-activated with sensory stimulation could limit CSD ignition when K+ uptake was not sufficiently suppressed as with ouabain.
Conclusions
Normal brain is well protected against CSD generation. For CSD to be ignited under physiological conditions, priming and predisposing factors are required as seen in migraine patients. Intense sensory stimulation has potential to trigger CSD when co-existing conditions bring extracellular K+ and glutamate concentrations over CSD-ignition threshold and stimulation-evoked inhibitory mechanisms are overcome.
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Boyd MA, Davis AM, Chambers NR, Tran P, Prindle A, Kamat NP. Vesicle-Based Sensors for Extracellular Potassium Detection. Cell Mol Bioeng 2021; 14:459-469. [PMID: 34777604 DOI: 10.1007/s12195-021-00688-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2021] [Accepted: 07/07/2021] [Indexed: 10/20/2022] Open
Abstract
Introduction The design of sensors that can detect biological ions in situ remains challenging. While many fluorescent indicators exist that can provide a fast, easy readout, they are often nonspecific, particularly to ions with similar charge states. To address this issue, we developed a vesicle-based sensor that harnesses membrane channels to gate access of potassium (K+) ions to an encapsulated fluorescent indicator. Methods We assembled phospholipid vesicles that incorporated valinomycin, a K+ specific membrane transporter, and that encapsulated benzofuran isophthalate (PBFI), a K+ sensitive dye that nonspecifically fluoresces in the presence of other ions, like sodium (Na+). The specificity, kinetics, and reversibility of encapsulated PBFI fluorescence was determined in a plate reader and fluorimeter. The sensors were then added to E. coli bacterial cultures to evaluate K+ levels in media as a function of cell density. Results Vesicle sensors significantly improved specificity of K+ detection in the presence of a competing monovalent ion, sodium (Na+), and a divalent cation, calcium (Ca2+), relative to controls where the dye was free in solution. The sensor was able to report both increases and decreases in K+ concentration. Finally, we observed our vesicle sensors could detect changes in K+ concentration in bacterial cultures. Conclusion Our data present a new platform for extracellular ion detection that harnesses ion-specific membrane transporters to improve the specificity of ion detection. By changing the membrane transporter and encapsulated sensor, our approach should be broadly useful for designing biological sensors that detect an array of biological analytes in traditionally hard-to-monitor environments. Supplementary Information The online version contains supplementary material available at 10.1007/s12195-021-00688-7.
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Affiliation(s)
- Margrethe A Boyd
- Department of Biomedical Engineering, McCormick School of Engineering, Northwestern University, Evanston, IL 60208 USA
| | - Anna M Davis
- Department of Biomedical Engineering, McCormick School of Engineering, Northwestern University, Evanston, IL 60208 USA
| | - Nora R Chambers
- Department of Biomedical Engineering, McCormick School of Engineering, Northwestern University, Evanston, IL 60208 USA
| | - Peter Tran
- Department of Chemical and Biological Engineering, McCormick School of Engineering, Northwestern University, Evanston, IL 60208 USA
| | - Arthur Prindle
- Center for Synthetic Biology, McCormick School of Engineering, Northwestern University, Evanston, IL 60208 USA.,Department of Chemical and Biological Engineering, McCormick School of Engineering, Northwestern University, Evanston, IL 60208 USA.,Department of Biochemistry and Molecular Genetics, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611 USA
| | - Neha P Kamat
- Department of Biomedical Engineering, McCormick School of Engineering, Northwestern University, Evanston, IL 60208 USA.,Center for Synthetic Biology, McCormick School of Engineering, Northwestern University, Evanston, IL 60208 USA
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Varga DP, Menyhárt Á, Pósfai B, Császár E, Lénárt N, Cserép C, Orsolits B, Martinecz B, Szlepák T, Bari F, Farkas E, Dénes Á. Microglia alter the threshold of spreading depolarization and related potassium uptake in the mouse brain. J Cereb Blood Flow Metab 2020; 40:S67-S80. [PMID: 31987008 PMCID: PMC7687034 DOI: 10.1177/0271678x19900097] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Selective elimination of microglia from the brain was shown to dysregulate neuronal Ca2+ signaling and to reduce the incidence of spreading depolarization (SD) during cerebral ischemia. However, the mechanisms through which microglia interfere with SD remained unexplored. Here, we identify microglia as essential modulators of the induction and evolution of SD in the physiologically intact brain in vivo. Confocal- and super-resolution microscopy revealed that a series of SDs induced rapid morphological changes in microglia, facilitated microglial process recruitment to neurons and increased the density of P2Y12 receptors (P2Y12R) on recruited microglial processes. In line with this, depolarization and hyperpolarization during SD were microglia- and P2Y12R-dependent. An absence of microglia was associated with altered potassium uptake after SD and increased the number of c-fos-positive neurons, independently of P2Y12R. Thus, the presence of microglia is likely to be essential to maintain the electrical elicitation threshold and to support the full evolution of SD, conceivably by interfering with the extracellular potassium homeostasis of the brain through sustaining [K+]e re-uptake mechanisms.
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Affiliation(s)
- Dániel P Varga
- Department of Medical Physics and Informatics, University of Szeged, Szeged, Hungary
| | - Ákos Menyhárt
- Department of Medical Physics and Informatics, University of Szeged, Szeged, Hungary
| | - Balázs Pósfai
- Laboratory of Neuroimmunology, Institute of Experimental Medicine, Budapest, Hungary.,Szentágothai János Doctoral School of Neuroscience, Semmelweis University, Budapest, Hungary
| | - Eszter Császár
- Laboratory of Neuroimmunology, Institute of Experimental Medicine, Budapest, Hungary.,Szentágothai János Doctoral School of Neuroscience, Semmelweis University, Budapest, Hungary
| | - Nikolett Lénárt
- Laboratory of Neuroimmunology, Institute of Experimental Medicine, Budapest, Hungary
| | - Csaba Cserép
- Laboratory of Neuroimmunology, Institute of Experimental Medicine, Budapest, Hungary
| | - Barbara Orsolits
- Laboratory of Neuroimmunology, Institute of Experimental Medicine, Budapest, Hungary
| | - Bernadett Martinecz
- Laboratory of Neuroimmunology, Institute of Experimental Medicine, Budapest, Hungary
| | - Tamás Szlepák
- Laboratory of Neuroimmunology, Institute of Experimental Medicine, Budapest, Hungary.,Szentágothai János Doctoral School of Neuroscience, Semmelweis University, Budapest, Hungary
| | - Ferenc Bari
- Department of Medical Physics and Informatics, University of Szeged, Szeged, Hungary
| | - Eszter Farkas
- Department of Medical Physics and Informatics, University of Szeged, Szeged, Hungary
| | - Ádám Dénes
- Laboratory of Neuroimmunology, Institute of Experimental Medicine, Budapest, Hungary
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Breithausen B, Kautzmann S, Boehlen A, Steinhäuser C, Henneberger C. Limited contribution of astroglial gap junction coupling to buffering of extracellular K + in CA1 stratum radiatum. Glia 2019; 68:918-931. [PMID: 31743499 DOI: 10.1002/glia.23751] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2019] [Revised: 10/25/2019] [Accepted: 10/29/2019] [Indexed: 12/21/2022]
Abstract
Astrocytes form large networks, in which individual cells are connected via gap junctions. It is thought that this astroglial gap junction coupling contributes to the buffering of extracellular K+ increases. However, it is largely unknown how the control of extracellular K+ by astroglial gap junction coupling depends on the underlying activity patterns and on the magnitude of extracellular K+ increases. We explored this dependency in acute hippocampal slices (CA1, stratum radiatum) by direct K+ -sensitive microelectrode recordings and acute pharmacological inhibition of gap junctions. K+ transients evoked by synaptic and axonal activity were largely unaffected by acute astroglial uncoupling in slices obtained from young and adult rats. Iontophoretic K+ -application enabled us to generate K+ gradients with defined spatial properties and magnitude. By varying the K+ -iontophoresis position and protocol, we found that acute pharmacological uncoupling increases the amplitude of K+ transients once their initial amplitude exceeded ~10 mM. Our experiments demonstrate that the contribution of gap junction coupling to buffering of extracellular K+ gradients is limited to large and localized K+ increases.
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Affiliation(s)
- Björn Breithausen
- Institute of Cellular Neurosciences, University of Bonn Medical School, Bonn, Germany
| | - Steffen Kautzmann
- Institute of Cellular Neurosciences, University of Bonn Medical School, Bonn, Germany
| | - Anne Boehlen
- Institute of Cellular Neurosciences, University of Bonn Medical School, Bonn, Germany
| | - Christian Steinhäuser
- Institute of Cellular Neurosciences, University of Bonn Medical School, Bonn, Germany
| | - Christian Henneberger
- Institute of Cellular Neurosciences, University of Bonn Medical School, Bonn, Germany.,Institute of Neurology, University College London, London, UK.,German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany
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6
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Depaoli MR, Bischof H, Eroglu E, Burgstaller S, Ramadani-muja J, Rauter T, Schinagl M, Waldeck-weiermair M, Hay JC, Graier WF, Malli R. Live cell imaging of signaling and metabolic activities. Pharmacol Ther 2019; 202:98-119. [DOI: 10.1016/j.pharmthera.2019.06.003] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2019] [Accepted: 05/31/2019] [Indexed: 12/15/2022]
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Menyhárt Á, Farkas AE, Varga DP, Frank R, Tóth R, Bálint AR, Makra P, Dreier JP, Bari F, Krizbai IA, Farkas E. Large-conductance Ca 2+-activated potassium channels are potently involved in the inverse neurovascular response to spreading depolarization. Neurobiol Dis 2018; 119:41-52. [PMID: 30053571 DOI: 10.1016/j.nbd.2018.07.026] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2018] [Revised: 07/03/2018] [Accepted: 07/23/2018] [Indexed: 12/21/2022] Open
Abstract
Recurrent spreading depolarizations occur in the cerebral cortex from minutes up to weeks following acute brain injury. Clinical evidence suggests that the immediate reduction of cerebral blood flow in response to spreading depolarization importantly contributes to lesion progression as the wave propagates over vulnerable tissue zones, characterized by potassium concentration already elevated prior to the passage of spreading depolarization. Here we demonstrate with two-photon microscopy in anesthetized mice that initial vasoconstriction in response to SD triggered experimentally with 1 M KCl is coincident in space and time with the large extracellular accumulation of potassium, as shown with a potassium indicator fluorescent dye. Moreover, pharmacological manipulations in combination with the use of potassium-sensitive microelectrodes suggest that large-conductance Ca2+-activated potassium (BK) channels and L-type voltage-gated calcium channels play significant roles in the marked initial vasoconstriction under elevated baseline potassium. We propose that potassium efflux through BK channels is a central component in the devastating neurovascular effects of spreading depolarizations in tissue at risk.
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Bazzigaluppi P, Ebrahim Amini A, Weisspapir I, Stefanovic B, Carlen PL. Hungry Neurons: Metabolic Insights on Seizure Dynamics. Int J Mol Sci 2017; 18:ijms18112269. [PMID: 29143800 PMCID: PMC5713239 DOI: 10.3390/ijms18112269] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2017] [Revised: 10/24/2017] [Accepted: 10/26/2017] [Indexed: 12/18/2022] Open
Abstract
Epilepsy afflicts up to 1.6% of the population and the mechanisms underlying the appearance of seizures are still not understood. In past years, many efforts have been spent trying to understand the mechanisms underlying the excessive and synchronous firing of neurons. Traditionally, attention was pointed towards synaptic (dys)function and extracellular ionic species (dys)regulation. Recently, novel clinical and preclinical studies explored the role of brain metabolism (i.e., glucose utilization) of seizures pathophysiology revealing (in most cases) reduced metabolism in the inter-ictal period and increased metabolism in the seconds preceding and during the appearance of seizures. In the present review, we summarize the clinical and preclinical observations showing metabolic dysregulation during epileptogenesis, seizure initiation, and termination, and in the inter-ictal period. Recent preclinical studies have shown that 2-Deoxyglucose (2-DG, a glycolysis blocker) is a novel therapeutic approach to reduce seizures. Furthermore, we present initial evidence for the effectiveness of 2-DG in arresting 4-Aminopyridine induced neocortical seizures in vivo in the mouse.
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Affiliation(s)
- Paolo Bazzigaluppi
- Krembil Research Institute, Fundamental Neurobiology, Toronto, ON M5T 2S8, Canada.
- Sunnybrook Research Institute, Medical Biophysics, Toronto, ON M4N 3M5, Canada.
| | - Azin Ebrahim Amini
- Krembil Research Institute, Fundamental Neurobiology, Toronto, ON M5T 2S8, Canada.
- Institute of Biomaterials & Biomedical Engineering (IBBME), University of Toronto, Toronto, ON M5S 3G9, Canada.
| | - Iliya Weisspapir
- Krembil Research Institute, Fundamental Neurobiology, Toronto, ON M5T 2S8, Canada.
| | - Bojana Stefanovic
- Sunnybrook Research Institute, Medical Biophysics, Toronto, ON M4N 3M5, Canada.
| | - Peter L Carlen
- Krembil Research Institute, Fundamental Neurobiology, Toronto, ON M5T 2S8, Canada.
- Department of Medicine & Physiology, and Institute of Biomaterials & Biomedical Engineering (IBBME), University of Toronto, Toronto, ON M5S 1A8, Canada.
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Ringuette D, Jeffrey MA, Dufour S, Carlen PL, Levi O. Continuous multi-modality brain imaging reveals modified neurovascular seizure response after intervention. Biomed Opt Express 2017; 8:873-889. [PMID: 28270990 PMCID: PMC5330586 DOI: 10.1364/boe.8.000873] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2016] [Revised: 12/05/2016] [Accepted: 12/19/2016] [Indexed: 05/28/2023]
Abstract
We developed a multi-modal brain imaging system to investigate the relationship between blood flow, blood oxygenation/volume, intracellular calcium and electrographic activity during acute seizure-like events (SLEs), both before and after pharmacological intervention. Rising blood volume was highly specific to SLE-onset whereas blood flow was more correlated with all eletrographic activity. Intracellular calcium spiked between SLEs and at SLE-onset with oscillation during SLEs. Modified neurovascular and ionic SLE responses were observed after intervention and the interval between SLEs became shorter and more inconsistent. Comparison of artery and vein pulsatile flow suggest proximal interference and greater vascular leakage prior to intervention.
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Affiliation(s)
- Dene Ringuette
- The Institute of Biomaterials and Biomedical Engineering, University of Toronto, 164 College Street, Toronto, Ontario, M5S 3G9,
Canada
| | - Melanie A. Jeffrey
- Division of Fundamental Neurobiology, Toronto Western Research Institute, 60 Leonard Ave, Toronto, Ontario M5T 2R1,
Canada
| | - Suzie Dufour
- The Institute of Biomaterials and Biomedical Engineering, University of Toronto, 164 College Street, Toronto, Ontario, M5S 3G9,
Canada
- Division of Fundamental Neurobiology, Toronto Western Research Institute, 60 Leonard Ave, Toronto, Ontario M5T 2R1,
Canada
| | - Peter L. Carlen
- The Institute of Biomaterials and Biomedical Engineering, University of Toronto, 164 College Street, Toronto, Ontario, M5S 3G9,
Canada
- Division of Fundamental Neurobiology, Toronto Western Research Institute, 60 Leonard Ave, Toronto, Ontario M5T 2R1,
Canada
| | - Ofer Levi
- The Institute of Biomaterials and Biomedical Engineering, University of Toronto, 164 College Street, Toronto, Ontario, M5S 3G9,
Canada
- The Edward S. Rogers Sr. Department of Electrical and Computer Engineering, University of Toronto, 10 King’s College Road, Toronto, Ontario, M5S 3G4,
Canada
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10
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Wellbourne-Wood J, Rimmele TS, Chatton JY. Imaging extracellular potassium dynamics in brain tissue using a potassium-sensitive nanosensor. Neurophotonics 2017; 4:015002. [PMID: 28217712 PMCID: PMC5299859 DOI: 10.1117/1.nph.4.1.015002] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/09/2016] [Accepted: 01/19/2017] [Indexed: 05/25/2023]
Abstract
Neuronal activity results in the release of [Formula: see text] into the extracellular space (ECS). Classically, measurements of extracellular [Formula: see text] ([Formula: see text]) are carried out using [Formula: see text]-sensitive microelectrodes, which provide a single point measurement with undefined spatial resolution. An imaging approach would enable the spatiotemporal mapping of [Formula: see text]. Here, we report on the design and characterization of a fluorescence imaging-based [Formula: see text]-sensitive nanosensor for the ECS based on dendrimer nanotechnology. Spectral characterization, sensitivity, and selectivity of the nanosensor were assessed by spectrofluorimetry, as well as in both wide-field and two-photon microscopy settings, demonstrating the nanosensor efficacy over the physiologically relevant ion concentration range. Spatial and temporal kinetics of the nanosensor responses were assessed using a localized iontophoretic [Formula: see text] application on a two-photon imaging setup. Using acute mouse brain slices, we demonstrate that the nanosensor is retained in the ECS for extended periods of time. In addition, we present a ratiometric version of the nanosensor, validate its sensitivity in brain tissue in response to elicited neuronal activity and correlate the responses to the extracellular field potential. Together, this study demonstrates the efficacy of the [Formula: see text]-sensitive nanosensor approach and validates the possibility of creating multimodal nanosensors.
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Affiliation(s)
- Joel Wellbourne-Wood
- University of Lausanne, Department of Fundamental Neurosciences, Lausanne, Switzerland
| | - Theresa S. Rimmele
- University of Lausanne, Department of Fundamental Neurosciences, Lausanne, Switzerland
| | - Jean-Yves Chatton
- University of Lausanne, Department of Fundamental Neurosciences, Lausanne, Switzerland
- University of Lausanne, Cellular Imaging Facility, Lausanne, Switzerland
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11
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Bazzigaluppi P, Weisspapir I, Stefanovic B, Leybaert L, Carlen PL. Astrocytic gap junction blockade markedly increases extracellular potassium without causing seizures in the mouse neocortex. Neurobiol Dis 2016; 101:1-7. [PMID: 28007587 DOI: 10.1016/j.nbd.2016.12.017] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2016] [Revised: 11/24/2016] [Accepted: 12/18/2016] [Indexed: 10/20/2022] Open
Abstract
Extracellular potassium concentration, [K+]o, is a major determinant of neuronal excitability. In the healthy brain, [K+]o levels are tightly controlled. During seizures, [K+]o increases up to 15mM and is thought to cause seizures due to its depolarizing effect. Although astrocytes have been suggested to play a key role in the redistribution (or spatial buffering) of excess K+ through Connexin-43 (Cx43)-based Gap Junctions (GJs), the relation between this dynamic regulatory process and seizure generation remains unknown. Here we contrasted the role of astrocytic GJs and hemichannels by studying the effect of GJ and hemichannel blockers on [K+]o regulation in vivo. [K+]o was measured by K+-sensitive microelectrodes. Neuronal excitability was estimated by local field potential (LFP) responses to forepaw stimulation and changes in the power of resting state activity. Starting at the baseline [K+]o level of 1.61±0.3mM, cortical microinjection of CBX, a broad spectrum connexin channel blocker, increased [K+]o to 11±3mM, Cx43 GJ/hemichannel blocker Gap27 increased it from 1.9±0.7 to 9±1mM. At these [K+]o levels, no seizures were observed. Cx43 hemichannel blockade with TAT-Gap19 increased [K+]o by only ~1mM. Microinjection of 4-aminopyridine, a known convulsant, increased [K+]o to ~10mM and induced spontaneously recurring seizures, whereas direct application of K+ did not trigger seizure activity. These findings are the first in vivo demonstration that astrocytic GJs are major determinants for the spatial buffering of [K+]o and that an increase in [K+]o alone does not trigger seizures in the neocortex.
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Affiliation(s)
- Paolo Bazzigaluppi
- Fundamental Neurobiology, Krembil Research Institute, University Health Network, M5T 2S8 Toronto, Ontario, Canada; Physical Sciences, Sunnybrook Research Institute, M4N 3M5 Toronto, Ontario, Canada.
| | - Iliya Weisspapir
- Fundamental Neurobiology, Krembil Research Institute, University Health Network, M5T 2S8 Toronto, Ontario, Canada
| | - Bojana Stefanovic
- Physical Sciences, Sunnybrook Research Institute, M4N 3M5 Toronto, Ontario, Canada; Department of Medical Biophysics, University of Toronto, Ontario, Canada
| | - Luc Leybaert
- Department of Basic Medical Sciences, University of Ghent, 9000 Ghent, Belgium
| | - Peter L Carlen
- Fundamental Neurobiology, Krembil Research Institute, University Health Network, M5T 2S8 Toronto, Ontario, Canada
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Machado R, Soltani N, Dufour S, Salam MT, Carlen PL, Genov R, Thompson M. Biofouling-Resistant Impedimetric Sensor for Array High-Resolution Extracellular Potassium Monitoring in the Brain. Biosensors (Basel) 2016; 6:E53. [PMID: 27754393 PMCID: PMC5192373 DOI: 10.3390/bios6040053] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/16/2016] [Revised: 09/28/2016] [Accepted: 09/30/2016] [Indexed: 02/02/2023]
Abstract
Extracellular potassium concentration, [K⁺]o, plays a fundamental role in the physiological functions of the brain. Studies investigating changes in [K⁺]o have predominantly relied upon glass capillary electrodes with K⁺-sensitive solution gradients for their measurements. However, such electrodes are unsuitable for taking spatio-temporal measurements and are limited by the surface area of their tips. We illustrate seizures invoked chemically and in optogenetically modified mice using blue light exposure while impedimetrically measuring the response. A sharp decrease of 1-2 mM in [K⁺]o before each spike has shown new physiological events not witnessed previously when measuring extracellular potassium concentrations during seizures in mice. We propose a novel approach that uses multichannel monolayer coated gold microelectrodes for in vivo spatio-temporal measurements of [K⁺]o in a mouse brain as an improvement to the conventional glass capillary electrode.
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Affiliation(s)
- Ruben Machado
- Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, ON M5S 3H6, Canada.
- Toronto Western Research Institute, Fundamental Neurobiology Division, 60 Leonard Avenue, Toronto, ON M5T 2S8, Canada.
| | - Nima Soltani
- Department of Electrical and Computer Engineering, University of Toronto, 10 King's College Road, Toronto, ON M5S 3G4, Canada.
| | - Suzie Dufour
- Toronto Western Research Institute, Fundamental Neurobiology Division, 60 Leonard Avenue, Toronto, ON M5T 2S8, Canada.
| | - Muhammad Tariqus Salam
- Department of Electrical and Computer Engineering, University of Toronto, 10 King's College Road, Toronto, ON M5S 3G4, Canada.
| | - Peter L Carlen
- Toronto Western Research Institute, Fundamental Neurobiology Division, 60 Leonard Avenue, Toronto, ON M5T 2S8, Canada.
- Institute of Biomaterials & Biomedical Engineering, University of Toronto, 164 College Street, Toronto, ON M5S 3G9, Canada.
| | - Roman Genov
- Department of Electrical and Computer Engineering, University of Toronto, 10 King's College Road, Toronto, ON M5S 3G4, Canada.
| | - Michael Thompson
- Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, ON M5S 3H6, Canada.
- Institute of Biomaterials & Biomedical Engineering, University of Toronto, 164 College Street, Toronto, ON M5S 3G9, Canada.
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Chen X, He WT, Hu L, Li J, Fang Y, Wang X, Xu X, Wang Z, Huang K, Han J. Pyroptosis is driven by non-selective gasdermin-D pore and its morphology is different from MLKL channel-mediated necroptosis. Cell Res. 2016;26:1007-1020. [PMID: 27573174 PMCID: PMC5034106 DOI: 10.1038/cr.2016.100] [Citation(s) in RCA: 498] [Impact Index Per Article: 62.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2016] [Revised: 08/02/2016] [Accepted: 08/03/2016] [Indexed: 12/17/2022] Open
Abstract
Necroptosis and pyroptosis are two forms of programmed cell death with a common feature of plasma membrane rupture. Here we studied the morphology and mechanism of pyroptosis in comparison with necroptosis. Different from necroptosis, pyroptosis undergoes membrane blebbing and produces apoptotic body-like cell protrusions (termed pyroptotic bodies) prior to plasma membrane rupture. The rupture in necroptosis is explosion-like, whereas in pyroptosis it leads to flattening of cells. It is known that the execution of necroptosis is mediated by mixed lineage kinase domain-like (MLKL) oligomers in the plasma membrane, whereas gasdermin-D (GSDMD) mediates pyroptosis after its cleavage by caspase-1 or caspase-11. We show that N-terminal fragment of GSDMD (GSDMD-N) generated by caspase cleavage also forms oligomer and migrates to the plasma membrane to kill cells. Both MLKL and GSDMD-N are lipophilic and the N-terminal sequences of both proteins are important for their oligomerization and plasma membrane translocation. Unlike MLKL which forms channels on the plasma membrane that induces influx of selected ions which osmotically swell the cells to burst, GSDMD-N forms non-selective pores and does not rely on increased osmolarity to disrupt cells. Our study reveals the pore-forming activity of GSDMD and channel-forming activity of MLKL determine different ways of plasma membrane rupture in pyroptosis and necroptosis.
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Depauw A, Dossi E, Kumar N, Fiorini-Debuisschert C, Huberfeld G, Ha-Thi MH, Rouach N, Leray I. A Highly Selective Potassium Sensor for the Detection of Potassium in Living Tissues. Chemistry 2016; 22:14902-14911. [PMID: 27558921 DOI: 10.1002/chem.201602209] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2016] [Indexed: 01/19/2023]
Abstract
The development of highly selective sensors for potassium is of great interest in biology. Two new hydrosoluble potassium sensors (Calix-COU-Alkyne and Calix-COU-Am) based on a calix[4]arene bis(crown-6) and an extended coumarin were synthesized and characterized. The photophysical properties and complexation studies of these compounds have been investigated and show high molar extinction coefficients and high fluorescence quantum yields. Upon complexation with potassium in the millimolar concentration range, an increase of one- and two-photon fluorescence emission is detected. A twofold fluorescence enhancement is observed upon excitation at λ=405 nm. The ligands present excellent selectivity for potassium in the presence of various competitive cations in water and in a physiological medium. The photophysical properties are not affected by the presence of a large amount of competing cations (Na+ , Ca2+ , Mg2+ , etc.). Ex vivo measurements on mouse hippocampal slices show that Calix-COU-Alkyne accumulates extracellularly and does not alter the neuronal activity. Furthermore, the sensor can be utilized to monitor slow extracellular K+ increase induced by inhibition of K+ entry into the cells.
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Affiliation(s)
- Alexis Depauw
- PPSM, ENS Cachan, CNRS, Université Paris Saclay, 61 avenue du Président Wilson, 94235, Cachan Cedex, France
| | - Elena Dossi
- Center for Interdisciplinary Research in Biology, Collège de France, Centre National de la, Recherche Scientifique UMR 7241, Institut National de la Santé et de la Recherche Médicale U1050, Labex Memolife, PSL Research University, Paris, France
| | - Naresh Kumar
- PPSM, ENS Cachan, CNRS, Université Paris Saclay, 61 avenue du Président Wilson, 94235, Cachan Cedex, France
| | | | - Gilles Huberfeld
- Neurophysiology Department, Sorbonne University, UPMC University Paris 06, Centre Hospitalo-Universitaire Pitié-Salpêtrière, APHP, 75013, Paris, France.,INSERM U1129 "Infantile Epilepsies and Brain Plasticity", Paris Descartes University, PRES Sorbonne Paris Cité, CEA, Gif sur Yvette, France
| | - Minh-Huong Ha-Thi
- PPSM, ENS Cachan, CNRS, Université Paris Saclay, 61 avenue du Président Wilson, 94235, Cachan Cedex, France.,Institut des Sciences Moléculaire d'Orsay (ISMO), CNRS, Université Paris-Sud, Université Paris Saclay, 91405, Orsay, France
| | - Nathalie Rouach
- Center for Interdisciplinary Research in Biology, Collège de France, Centre National de la, Recherche Scientifique UMR 7241, Institut National de la Santé et de la Recherche Médicale U1050, Labex Memolife, PSL Research University, Paris, France
| | - Isabelle Leray
- PPSM, ENS Cachan, CNRS, Université Paris Saclay, 61 avenue du Président Wilson, 94235, Cachan Cedex, France.
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Medina-Ceja L, Pardo-Peña K, Morales-Villagrán A, Ortega-Ibarra J, López-Pérez S. Increase in the extracellular glutamate level during seizures and electrical stimulation determined using a high temporal resolution technique. BMC Neurosci 2015; 16:11. [PMID: 25887152 PMCID: PMC4363345 DOI: 10.1186/s12868-015-0147-5] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2014] [Accepted: 02/20/2015] [Indexed: 12/21/2022] Open
Abstract
Background Glutamate has been measured using different methods to determine its role under normal and pathological conditions. Although microdialysis coupled with HPLC is the preferred method to study glutamate, this technique exhibits poor temporal resolution and is time consuming. The concentration of glutamate in dialysis samples can be measured via glutamate oxidase using the Amplex Red method. Methods A new device has been designed and constructed to rapidly deposit dialysis samples onto a polycarbonate plate at Cartesian coordinates (every five seconds). The samples were added to an enzymatic reaction that generates hydrogen peroxide from glutamate, which was quantified using fluorescence detection. Fluorescence emission was induced by laser excitation, stimulating each spot automatically, in addition to controlling the humidity, temperature and incubation time of the enzymatic reaction. Results The measurement of standard glutamate concentrations was linear and could be performed in dialysis samples. This approach was used to determine the effect of the convulsant drugs bicuculline and 4-aminopyridine on the extracellular glutamate concentration. Seizure activity was associated with a considerable increase in glutamate that correlated with altered EEG patterns for both drugs. Conclusions These results indicate that this method is able to read samples with high temporal resolution, and it is easy to use compared with classical methods such as high-performance liquid chromatography, with the advantage that a large number of samples can be measured in a single experimental series. This method provides an alternative approach to determine the concentrations of neurotransmitters or other compounds that generate hydrogen peroxide as a reaction product.
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Affiliation(s)
- Laura Medina-Ceja
- Laboratory of Neurophysiology and Neurochemistry, Department of Cellular and Molecular Biology, CUCBA, University of Guadalajara, Jalisco, Mexico.
| | - Kenia Pardo-Peña
- Laboratory of Neurophysiology and Neurochemistry, Department of Cellular and Molecular Biology, CUCBA, University of Guadalajara, Jalisco, Mexico.
| | - Alberto Morales-Villagrán
- Laboratory of Neurophysiology and Neurochemistry, Department of Cellular and Molecular Biology, CUCBA, University of Guadalajara, Jalisco, Mexico. .,Laboratorio de Neurofisiología y Neuroquímica, Departamento de Biología Celular y Molecular, Centro Universitario de Ciencias Biológicas y Agropecuarias, Universidad de Guadalajara, Camino Ing. R. Padilla Sánchez 2100, Las Agujas, Nextipac, CP 45110, Zapopan, Jalisco, Mexico.
| | - Jorge Ortega-Ibarra
- Laboratory of Neurophysiology and Neurochemistry, Department of Cellular and Molecular Biology, CUCBA, University of Guadalajara, Jalisco, Mexico.
| | - Silvia López-Pérez
- Laboratory of Neurophysiology and Neurochemistry, Department of Cellular and Molecular Biology, CUCBA, University of Guadalajara, Jalisco, Mexico.
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