1
|
Pál B. On the functions of astrocyte-mediated neuronal slow inward currents. Neural Regen Res 2024; 19:2602-2612. [PMID: 38595279 DOI: 10.4103/nrr.nrr-d-23-01723] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2023] [Accepted: 01/24/2024] [Indexed: 04/11/2024] Open
Abstract
Slow inward currents are known as neuronal excitatory currents mediated by glutamate release and activation of neuronal extrasynaptic N-methyl-D-aspartate receptors with the contribution of astrocytes. These events are significantly slower than the excitatory postsynaptic currents. Parameters of slow inward currents are determined by several factors including the mechanisms of astrocytic activation and glutamate release, as well as the diffusion pathways from the release site towards the extrasynaptic receptors. Astrocytes are stimulated by neuronal network activity, which in turn excite neurons, forming an astrocyte-neuron feedback loop. Mostly as a consequence of brain edema, astrocytic swelling can also induce slow inward currents under pathological conditions. There is a growing body of evidence on the roles of slow inward currents on a single neuron or local network level. These events often occur in synchrony on neurons located in the same astrocytic domain. Besides synchronization of neuronal excitability, slow inward currents also set synaptic strength via eliciting timing-dependent synaptic plasticity. In addition, slow inward currents are also subject to non-synaptic plasticity triggered by long-lasting stimulation of the excitatory inputs. Of note, there might be important region-specific differences in the roles and actions triggering slow inward currents. In greater networks, the pathophysiological roles of slow inward currents can be better understood than physiological ones. Slow inward currents are identified in the pathophysiological background of autism, as slow inward currents drive early hypersynchrony of the neural networks. Slow inward currents are significant contributors to paroxysmal depolarizational shifts/interictal spikes. These events are related to epilepsy, but also found in Alzheimer's disease, Parkinson's disease, and stroke, leading to the decline of cognitive functions. Events with features overlapping with slow inward currents (excitatory, N-methyl-D-aspartate-receptor mediated currents with astrocytic contribution) as ischemic currents and spreading depolarization also have a well-known pathophysiological role in worsening consequences of stroke, traumatic brain injury, or epilepsy. One might assume that slow inward currents occurring with low frequency under physiological conditions might contribute to synaptic plasticity and memory formation. However, to state this, more experimental evidence from greater neuronal networks or the level of the individual is needed. In this review, I aimed to summarize findings on slow inward currents and to speculate on the potential functions of it.
Collapse
Affiliation(s)
- Balázs Pál
- Department of Physiology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| |
Collapse
|
2
|
Glutamate and GABA A receptor crosstalk mediates homeostatic regulation of neuronal excitation in the mammalian brain. Signal Transduct Target Ther 2022; 7:340. [PMID: 36184627 PMCID: PMC9527238 DOI: 10.1038/s41392-022-01148-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2022] [Revised: 05/29/2022] [Accepted: 07/27/2022] [Indexed: 11/17/2022] Open
Abstract
Maintaining a proper balance between the glutamate receptor-mediated neuronal excitation and the A type of GABA receptor (GABAAR) mediated inhibition is essential for brain functioning; and its imbalance contributes to the pathogenesis of many brain disorders including neurodegenerative diseases and mental illnesses. Here we identify a novel glutamate-GABAAR interaction mediated by a direct glutamate binding of the GABAAR. In HEK293 cells overexpressing recombinant GABAARs, glutamate and its analog ligands, while producing no current on their own, potentiate GABA-evoked currents. This potentiation is mediated by a direct binding at a novel glutamate binding pocket located at the α+/β− subunit interface of the GABAAR. Moreover, the potentiation does not require the presence of a γ subunit, and in fact, the presence of γ subunit significantly reduces the potency of the glutamate potentiation. In addition, the glutamate-mediated allosteric potentiation occurs on native GABAARs in rat neurons maintained in culture, as evidenced by the potentiation of GABAAR-mediated inhibitory postsynaptic currents and tonic currents. Most importantly, we found that genetic impairment of this glutamate potentiation in knock-in mice resulted in phenotypes of increased neuronal excitability, including decreased thresholds to noxious stimuli and increased seizure susceptibility. These results demonstrate a novel cross-talk between excitatory transmitter glutamate and inhibitory GABAAR. Such a rapid and short feedback loop between the two principal excitatory and inhibitory neurotransmission systems may play a critical homeostatic role in fine-tuning the excitation-inhibition balance (E/I balance), thereby maintaining neuronal excitability in the mammalian brain under both physiological and pathological conditions.
Collapse
|
3
|
Fernández-Serra R, Martínez-Alonso E, Alcázar A, Chioua M, Marco-Contelles J, Martínez-Murillo R, Ramos M, Guinea GV, González-Nieto D. Postischemic Neuroprotection of Aminoethoxydiphenyl Borate Associates Shortening of Peri-Infarct Depolarizations. Int J Mol Sci 2022; 23:ijms23137449. [PMID: 35806455 PMCID: PMC9266990 DOI: 10.3390/ijms23137449] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2022] [Revised: 06/29/2022] [Accepted: 07/03/2022] [Indexed: 11/28/2022] Open
Abstract
Brain stroke is a highly prevalent pathology and a main cause of disability among older adults. If not promptly treated with recanalization therapies, primary and secondary mechanisms of injury contribute to an increase in the lesion, enhancing neurological deficits. Targeting excitotoxicity and oxidative stress are very promising approaches, but only a few compounds have reached the clinic with relatively good positive outcomes. The exploration of novel targets might overcome the lack of clinical translation of previous efficient preclinical neuroprotective treatments. In this study, we examined the neuroprotective properties of 2-aminoethoxydiphenyl borate (2-APB), a molecule that interferes with intracellular calcium dynamics by the antagonization of several channels and receptors. In a permanent model of cerebral ischemia, we showed that 2-APB reduces the extent of the damage and preserves the functionality of the cortical territory, as evaluated by somatosensory evoked potentials (SSEPs). While in this permanent ischemia model, the neuroprotective effect exerted by the antioxidant scavenger cholesteronitrone F2 was associated with a reduction in reactive oxygen species (ROS) and better neuronal survival in the penumbra, 2-APB did not modify the inflammatory response or decrease the content of ROS and was mostly associated with a shortening of peri-infarct depolarizations, which translated into better cerebral blood perfusion in the penumbra. Our study highlights the potential of 2-APB to target spreading depolarization events and their associated inverse hemodynamic changes, which mainly contribute to extension of the area of lesion in cerebrovascular pathologies.
Collapse
Affiliation(s)
- Rocío Fernández-Serra
- Center for Biomedical Technology, Universidad Politécnica de Madrid, 28223 Madrid, Spain; (R.F.-S.); (M.R.); (G.V.G.)
- Departamento de Tecnología Fotónica y Bioingeniería, ETSI Telecomunicaciones, Universidad Politécnica de Madrid, 28040 Madrid, Spain
- Departamento de Ciencia de Materiales, ETSI Caminos, Canales y Puertos, Universidad Politécnica de Madrid, 28040 Madrid, Spain
- Silk Biomed SL, 28260 Madrid, Spain
| | - Emma Martínez-Alonso
- Department of Research, Hospital Universitario Ramón y Cajal, IRYCIS, 28034 Madrid, Spain; (E.M.-A.); (A.A.)
| | - Alberto Alcázar
- Department of Research, Hospital Universitario Ramón y Cajal, IRYCIS, 28034 Madrid, Spain; (E.M.-A.); (A.A.)
| | - Mourad Chioua
- Laboratory of Medicinal Chemistry, Institute of General Organic Chemistry (CSIC), 28006 Madrid, Spain; (M.C.); (J.M.-C.)
| | - José Marco-Contelles
- Laboratory of Medicinal Chemistry, Institute of General Organic Chemistry (CSIC), 28006 Madrid, Spain; (M.C.); (J.M.-C.)
| | | | - Milagros Ramos
- Center for Biomedical Technology, Universidad Politécnica de Madrid, 28223 Madrid, Spain; (R.F.-S.); (M.R.); (G.V.G.)
- Departamento de Tecnología Fotónica y Bioingeniería, ETSI Telecomunicaciones, Universidad Politécnica de Madrid, 28040 Madrid, Spain
- Biomedical Research Networking Center in Bioengineering Biomaterials and Nanomedicine (CIBER-BBN), 28029 Madrid, Spain
| | - Gustavo V. Guinea
- Center for Biomedical Technology, Universidad Politécnica de Madrid, 28223 Madrid, Spain; (R.F.-S.); (M.R.); (G.V.G.)
- Departamento de Ciencia de Materiales, ETSI Caminos, Canales y Puertos, Universidad Politécnica de Madrid, 28040 Madrid, Spain
- Silk Biomed SL, 28260 Madrid, Spain
- Biomedical Research Networking Center in Bioengineering Biomaterials and Nanomedicine (CIBER-BBN), 28029 Madrid, Spain
- Biomaterials and Regenerative Medicine Group, Instituto de Investigación Sanitaria del Hospital Clínico San Carlos (IdISSC), 28040 Madrid, Spain
| | - Daniel González-Nieto
- Center for Biomedical Technology, Universidad Politécnica de Madrid, 28223 Madrid, Spain; (R.F.-S.); (M.R.); (G.V.G.)
- Departamento de Tecnología Fotónica y Bioingeniería, ETSI Telecomunicaciones, Universidad Politécnica de Madrid, 28040 Madrid, Spain
- Silk Biomed SL, 28260 Madrid, Spain
- Biomedical Research Networking Center in Bioengineering Biomaterials and Nanomedicine (CIBER-BBN), 28029 Madrid, Spain
- Correspondence: ; Tel.: +34-910679280
| |
Collapse
|
4
|
Astrocytes Modulate Somatostatin Interneuron Signaling in the Visual Cortex. Cells 2022; 11:cells11091400. [PMID: 35563706 PMCID: PMC9102536 DOI: 10.3390/cells11091400] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Revised: 04/14/2022] [Accepted: 04/18/2022] [Indexed: 02/05/2023] Open
Abstract
At glutamatergic synapses, astrocytes respond to the neurotransmitter glutamate with intracellular Ca2+ elevations and the release of gliotransmitters that modulate synaptic transmission. While the functional interactions between neurons and astrocytes have been intensively studied at glutamatergic synapses, the role of astrocytes at GABAergic synapses has been less investigated. In the present study, we combine optogenetics with 2-photon Ca2+ imaging experiments and patch-clamp recording techniques to investigate the signaling between Somatostatin (SST)-releasing GABAergic interneurons and astrocytes in brain slice preparations from the visual cortex (VCx). We found that an intense stimulation of SST interneurons evokes Ca2+ elevations in astrocytes that fundamentally depend on GABAB receptor (GABABR) activation, and that this astrocyte response is modulated by the neuropeptide somatostatin. After episodes of SST interneuron hyperactivity, we also observed a long-lasting reduction of the inhibitory postsynaptic current (IPSC) amplitude onto pyramidal neurons (PNs). This reduction of inhibitory tone (i.e., disinhibition) is counterbalanced by the activation of astrocytes that upregulate SST interneuron-evoked IPSC amplitude by releasing ATP that, after conversion to adenosine, activates A1Rs. Our results describe a hitherto unidentified modulatory mechanism of inhibitory transmission to VCx layer II/III PNs that involves the functional recruitment of astrocytes by SST interneuron signaling.
Collapse
|
5
|
Frank R, Bari F, Menyhárt Á, Farkas E. Comparative analysis of spreading depolarizations in brain slices exposed to osmotic or metabolic stress. BMC Neurosci 2021; 22:33. [PMID: 33941084 PMCID: PMC8094470 DOI: 10.1186/s12868-021-00637-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2021] [Accepted: 04/20/2021] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND Recurrent spreading depolarizations (SDs) occur in stroke and traumatic brain injury and are considered as a hallmark of injury progression. The complexity of conditions associated with SD in the living brain encouraged researchers to study SD in live brain slice preparations, yet methodological differences among laboratories complicate integrative data interpretation. Here we provide a comparative evaluation of SD evolution in live brain slices, in response to selected SD triggers and in various media, under otherwise standardized experimental conditions. METHODS Rat live coronal brain slices (350 μm) were prepared (n = 51). Hypo-osmotic medium (Na+ content reduced from 130 to 60 mM, HM) or oxygen-glucose deprivation (OGD) were applied to cause osmotic or ischemic challenge. Brain slices superfused with artificial cerebrospinal fluid (aCSF) served as control. SDs were evoked in the control condition with pressure injection of KCl or electric stimulation. Local field potential (LFP) was recorded via an intracortical glass capillary electrode, or intrinsic optical signal imaging was conducted at white light illumination to characterize SDs. TTC and hematoxylin-eosin staining were used to assess tissue damage. RESULTS Severe osmotic stress or OGD provoked a spontaneous SD. In contrast with SDs triggered in aCSF, these spontaneous depolarizations were characterized by incomplete repolarization and prolonged duration. Further, cortical SDs under HM or OGD propagated over the entire cortex and occassionally invaded the striatum, while SDs in aCSF covered a significantly smaller cortical area before coming to a halt, and never spread to the striatum. SDs in HM displayed the greatest amplitude and the most rapid propagation velocity. Finally, spontaneous SD in HM and especially under OGD was followed by tissue injury. CONCLUSIONS While the failure of Na+/K+ ATP-ase is thought to impair tissue recovery from OGD-related SD, the tissue swelling-related hyper excitability and the exhaustion of astrocyte buffering capacity are suggested to promote SD evolution under osmotic stress. In contrast with OGD, SD propagating under hypo-osmotic condition is not terminal, yet it is associated with irreversible tissue injury. Further investigation is required to understand the mechanistic similarities or differences between the evolution of SDs spontaneously occurring in HM and under OGD.
Collapse
Affiliation(s)
- Rita Frank
- Department of Medical Physics and Informatics, Faculty of Medicine and Faculty of Science and Informatics, University of Szeged, Korányi fasor 9, 6720, Szeged, Hungary
| | - Ferenc Bari
- Department of Medical Physics and Informatics, Faculty of Medicine and Faculty of Science and Informatics, University of Szeged, Korányi fasor 9, 6720, Szeged, Hungary
| | - Ákos Menyhárt
- Department of Medical Physics and Informatics, Faculty of Medicine and Faculty of Science and Informatics, University of Szeged, Korányi fasor 9, 6720, Szeged, Hungary.
| | - Eszter Farkas
- Department of Medical Physics and Informatics, Faculty of Medicine and Faculty of Science and Informatics, University of Szeged, Korányi fasor 9, 6720, Szeged, Hungary.
| |
Collapse
|
6
|
Choi JIV, Tchernookova BK, Kumar W, Kiedrowski L, Goeke C, Guizzetti M, Larson J, Kreitzer MA, Malchow RP. Extracellular ATP-Induced Alterations in Extracellular H + Fluxes From Cultured Cortical and Hippocampal Astrocytes. Front Cell Neurosci 2021; 15:640217. [PMID: 33994945 PMCID: PMC8120152 DOI: 10.3389/fncel.2021.640217] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2020] [Accepted: 03/19/2021] [Indexed: 12/18/2022] Open
Abstract
Small alterations in the level of extracellular H+ can profoundly alter neuronal activity throughout the nervous system. In this study, self-referencing H+-selective microelectrodes were used to examine extracellular H+ fluxes from individual astrocytes. Activation of astrocytes cultured from mouse hippocampus and rat cortex with extracellular ATP produced a pronounced increase in extracellular H+ flux. The ATP-elicited increase in H+ flux appeared to be independent of bicarbonate transport, as ATP increased H+ flux regardless of whether the primary extracellular pH buffer was 26 mM bicarbonate or 1 mM HEPES, and persisted when atmospheric levels of CO2 were replaced by oxygen. Adenosine failed to elicit any change in extracellular H+ fluxes, and ATP-mediated increases in H+ flux were inhibited by the P2 inhibitors suramin and PPADS suggesting direct activation of ATP receptors. Extracellular ATP also induced an intracellular rise in calcium in cultured astrocytes, and ATP-induced rises in both calcium and H+ efflux were significantly attenuated when calcium re-loading into the endoplasmic reticulum was inhibited by thapsigargin. Replacement of extracellular sodium with choline did not significantly reduce the size of the ATP-induced increases in H+ flux, and the increases in H+ flux were not significantly affected by addition of EIPA, suggesting little involvement of Na+/H+ exchangers in ATP-elicited increases in H+ flux. Given the high sensitivity of voltage-sensitive calcium channels on neurons to small changes in levels of free H+, we hypothesize that the ATP-mediated extrusion of H+ from astrocytes may play a key role in regulating signaling at synapses within the nervous system.
Collapse
Affiliation(s)
- Ji-In Vivien Choi
- Department of Biological Sciences, University of Illinois at Chicago, Chicago, IL, United States.,Stritch School of Medicine, Loyola University, Maywood, IL, United States
| | - Boriana K Tchernookova
- Department of Biological Sciences, University of Illinois at Chicago, Chicago, IL, United States
| | - Wasan Kumar
- Department of Biological Sciences, University of Illinois at Chicago, Chicago, IL, United States
| | - Lech Kiedrowski
- Department of Biological Sciences, University of Illinois at Chicago, Chicago, IL, United States.,Spot Cells LLC, Chicago, IL, United States
| | - Calla Goeke
- VA Portland Health Care System, Portland, OR, United States.,Department of Behavioral Neuroscience, Oregon Health & Science University, Portland, OR, United States
| | - Marina Guizzetti
- VA Portland Health Care System, Portland, OR, United States.,Department of Behavioral Neuroscience, Oregon Health & Science University, Portland, OR, United States
| | - John Larson
- Department of Psychiatry, University of Illinois at Chicago, Chicago, IL, United States
| | - Matthew A Kreitzer
- Department of Biology, Indiana Wesleyan University, Marion, IN, United States
| | - Robert Paul Malchow
- Department of Biological Sciences, University of Illinois at Chicago, Chicago, IL, United States.,Department Ophthalmology and Visual Sciences, University of Illinois at Chicago, Chicago, IL, United States
| |
Collapse
|
7
|
Adrenergic inhibition facilitates normalization of extracellular potassium after cortical spreading depolarization. Sci Rep 2021; 11:8150. [PMID: 33854148 PMCID: PMC8047013 DOI: 10.1038/s41598-021-87609-w] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Accepted: 03/31/2021] [Indexed: 01/31/2023] Open
Abstract
Cortical spreading depolarization (CSD) is a propagating wave of tissue depolarization characterized by a large increase of extracellular potassium concentration and prolonged subsequent electrical silencing of neurons. Waves of CSD arise spontaneously in various acute neurological settings, including migraine aura and ischemic stroke. Recently, we have reported that pan-inhibition of adrenergic receptors (AdRs) facilitates the normalization of extracellular potassium after acute photothrombotic stroke in mice. Here, we have extended that mechanistic study to ask whether AdR antagonists also modify the dynamics of KCl-induced CSD and post-CSD recovery in vivo. Spontaneous neural activity and KCl-induced CSD were visualized by cortex-wide transcranial Ca2+ imaging in G-CaMP7 transgenic mice. AdR antagonism decreased the recurrence of CSD waves and accelerated the post-CSD recovery of neural activity. Two-photon imaging revealed that astrocytes exhibited aberrant Ca2+ signaling after passage of the CSD wave. This astrocytic Ca2+ activity was diminished by the AdR antagonists. Furthermore, AdR pan-antagonism facilitated the normalization of the extracellular potassium level after CSD, which paralleled the recovery of neural activity. These observations add support to the proposal that neuroprotective effects of AdR pan-antagonism arise from accelerated normalization of extracellular K+ levels in the setting of acute brain injury.
Collapse
|
8
|
Tóth R, Farkas AE, Krizbai IA, Makra P, Bari F, Farkas E, Menyhárt Á. Astrocyte Ca 2+ Waves and Subsequent Non-Synchronized Ca 2+ Oscillations Coincide with Arteriole Diameter Changes in Response to Spreading Depolarization. Int J Mol Sci 2021; 22:ijms22073442. [PMID: 33810538 PMCID: PMC8037646 DOI: 10.3390/ijms22073442] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2021] [Revised: 03/11/2021] [Accepted: 03/23/2021] [Indexed: 11/16/2022] Open
Abstract
Spreading depolarization (SD) is a wave of mass depolarization that causes profound perfusion changes in acute cerebrovascular diseases. Although the astrocyte response is secondary to the neuronal depolarization with SD, it remains to be explored how glial activity is altered after the passage of SD. Here, we describe post-SD high frequency astrocyte Ca2+ oscillations in the mouse somatosensory cortex. The intracellular Ca2+ changes of SR101 labeled astrocytes and the SD-related arteriole diameter variations were simultaneously visualized by multiphoton microscopy in anesthetized mice. Post-SD astrocyte Ca2+ oscillations were identified as Ca2+ events non-synchronized among astrocytes in the field of view. Ca2+ oscillations occurred minutes after the Ca2+ wave of SD. Furthermore, fewer astrocytes were involved in Ca2+ oscillations at a given time, compared to Ca2+ waves, engaging all astrocytes in the field of view simultaneously. Finally, our data confirm that astrocyte Ca2+ waves coincide with arteriolar constriction, while post-SD Ca2+ oscillations occur with the peak of the SD-related vasodilation. This is the first in vivo study to present the post-SD astrocyte Ca2+ oscillations. Our results provide novel insight into the spatio-temporal correlation between glial reactivity and cerebral arteriole diameter changes behind the SD wavefront.
Collapse
Affiliation(s)
- Réka Tóth
- Department of Medical Physics and Informatics, Faculty of Medicine and Faculty of Science and Informatics, University of Szeged, Korányi fasor 9, 6720 Szeged, Hungary; (R.T.); (P.M.); (F.B.)
| | - Attila E. Farkas
- Neurovascular Unit Research Group, Molecular Neurobiology Research Unit, Institute of Biophysics, Biological Research Centre, Eötvös Loránd Research Network (ELKH), Temesvári krt 62, 6726 Szeged, Hungary; (A.E.F.); (I.A.K.)
| | - István A. Krizbai
- Neurovascular Unit Research Group, Molecular Neurobiology Research Unit, Institute of Biophysics, Biological Research Centre, Eötvös Loránd Research Network (ELKH), Temesvári krt 62, 6726 Szeged, Hungary; (A.E.F.); (I.A.K.)
- Institute of Life Sciences, Vasile Goldis Western University, Revolutiei Blvd no. 94, 310025 Arad, Romania
| | - Péter Makra
- Department of Medical Physics and Informatics, Faculty of Medicine and Faculty of Science and Informatics, University of Szeged, Korányi fasor 9, 6720 Szeged, Hungary; (R.T.); (P.M.); (F.B.)
| | - Ferenc Bari
- Department of Medical Physics and Informatics, Faculty of Medicine and Faculty of Science and Informatics, University of Szeged, Korányi fasor 9, 6720 Szeged, Hungary; (R.T.); (P.M.); (F.B.)
| | - Eszter Farkas
- Department of Medical Physics and Informatics, Faculty of Medicine and Faculty of Science and Informatics, University of Szeged, Korányi fasor 9, 6720 Szeged, Hungary; (R.T.); (P.M.); (F.B.)
- Correspondence: (E.F.); (Á.M.); Tel.: +36-62-545-971 (E.F.); +36-62-545-364 (Á.M.)
| | - Ákos Menyhárt
- Department of Medical Physics and Informatics, Faculty of Medicine and Faculty of Science and Informatics, University of Szeged, Korányi fasor 9, 6720 Szeged, Hungary; (R.T.); (P.M.); (F.B.)
- Correspondence: (E.F.); (Á.M.); Tel.: +36-62-545-971 (E.F.); +36-62-545-364 (Á.M.)
| |
Collapse
|
9
|
Parker PD, Suryavanshi P, Melone M, Sawant-Pokam PA, Reinhart KM, Kaufmann D, Theriot JJ, Pugliese A, Conti F, Shuttleworth CW, Pietrobon D, Brennan KC. Non-canonical glutamate signaling in a genetic model of migraine with aura. Neuron 2021; 109:611-628.e8. [PMID: 33321071 PMCID: PMC7889497 DOI: 10.1016/j.neuron.2020.11.018] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2019] [Revised: 10/09/2020] [Accepted: 11/17/2020] [Indexed: 12/13/2022]
Abstract
Migraine with aura is a common but poorly understood sensory circuit disorder. Monogenic models allow an opportunity to investigate its mechanisms, including spreading depolarization (SD), the phenomenon underlying migraine aura. Using fluorescent glutamate imaging, we show that awake mice carrying a familial hemiplegic migraine type 2 (FHM2) mutation have slower clearance during sensory processing, as well as previously undescribed spontaneous "plumes" of glutamate. Glutamatergic plumes overlapped anatomically with a reduced density of GLT-1a-positive astrocyte processes and were mimicked in wild-type animals by inhibiting glutamate clearance. Plume pharmacology and plume-like neural Ca2+ events were consistent with action-potential-independent spontaneous glutamate release, suggesting plumes are a consequence of inefficient clearance following synaptic release. Importantly, a rise in basal glutamate and plume frequency predicted the onset of SD in both FHM2 and wild-type mice, providing a novel mechanism in migraine with aura and, by extension, the other neurological disorders where SD occurs.
Collapse
Affiliation(s)
- Patrick D Parker
- Department of Neurology, University of Utah School of Medicine, Salt Lake City, UT 84108, USA; Interdepartmental Program in Neuroscience, University of Utah School of Medicine, Salt Lake City, UT 84108, USA
| | - Pratyush Suryavanshi
- Department of Neurology, University of Utah School of Medicine, Salt Lake City, UT 84108, USA; Interdepartmental Program in Neuroscience, University of Utah School of Medicine, Salt Lake City, UT 84108, USA
| | - Marcello Melone
- Section of Neuroscience and Cell Biology, Department of Experimental and Clinical Medicine, Università Politecnica delle Marche, Ancona 60020, Italy; Center for Neurobiology of Aging, IRCCS INRCA, Ancona 60020, Italy
| | - Punam A Sawant-Pokam
- Department of Neurology, University of Utah School of Medicine, Salt Lake City, UT 84108, USA
| | - Katelyn M Reinhart
- Department of Neurology, University of Utah School of Medicine, Salt Lake City, UT 84108, USA; Department of Neurosciences, University of New Mexico School of Medicine, Albuquerque, NM 87106, USA
| | - Dan Kaufmann
- Department of Neurology, University of Utah School of Medicine, Salt Lake City, UT 84108, USA
| | - Jeremy J Theriot
- Department of Neurology, University of Utah School of Medicine, Salt Lake City, UT 84108, USA
| | - Arianna Pugliese
- Section of Neuroscience and Cell Biology, Department of Experimental and Clinical Medicine, Università Politecnica delle Marche, Ancona 60020, Italy
| | - Fiorenzo Conti
- Section of Neuroscience and Cell Biology, Department of Experimental and Clinical Medicine, Università Politecnica delle Marche, Ancona 60020, Italy; Center for Neurobiology of Aging, IRCCS INRCA, Ancona 60020, Italy; Foundation for Molecular Medicine, Università Politecnica delle Marche, Ancona 60020, Italy
| | - C William Shuttleworth
- Department of Neurosciences, University of New Mexico School of Medicine, Albuquerque, NM 87106, USA
| | - Daniela Pietrobon
- Department of Biomedical Sciences and Padova Neuroscience Center (PNC), University of Padova, 35131 Padova, Italy; CNR Institute of Neuroscience, 35131 Padova, Italy.
| | - K C Brennan
- Department of Neurology, University of Utah School of Medicine, Salt Lake City, UT 84108, USA.
| |
Collapse
|
10
|
Herreras O, Makarova J. Mechanisms of the negative potential associated with Leão's spreading depolarization: A history of brain electrogenesis. J Cereb Blood Flow Metab 2020; 40:1934-1952. [PMID: 32580670 PMCID: PMC7786845 DOI: 10.1177/0271678x20935998] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/06/2020] [Revised: 05/04/2020] [Accepted: 05/18/2020] [Indexed: 12/16/2022]
Abstract
Spreading depolarization (SD) is a self-propagated wave that provokes transient disorder of numerous cell and tissue functions, and that may kill neurons in metabolically compromised tissue. We examined the mechanisms underlying the main hallmark of SD, a giant extracellular potential (ΔVo) for which multiple electromotive forces have been proposed. The end-point is that neurons and not glia, dendritic channels and not spatial currents, and increased sodium conductance rather than potassium gradients, appear to be the main actors in the generation of the negative ΔVo. Neuronal currents are established by two mechanisms, a voltage independent dendritic current, and the differential polarization along the neuron membranes. Notably, despite of a marked drop of ion gradients, these evolve significantly during SD, and yet the membrane potential remains clamped at zero no matter how much inward current is present. There may be substantial inward current or none in function of the evolving portion of the neuron dendrites with SD-activated channels. We propose that the ΔVo promotes swelling-induced dendritic damage. Understanding SD electrogenesis requires all elements relevant for membrane potential, action currents, field potentials and volume conduction to be jointly considered, and it has already encouraged the search for new targets to limit SD-related pathology.
Collapse
Affiliation(s)
- Oscar Herreras
- Department of Translational Neuroscience, Cajal Institute – CSIC, Madrid, Spain
| | - Julia Makarova
- Department of Translational Neuroscience, Cajal Institute – CSIC, Madrid, Spain
- Lobachevsky State University of Nizhny Novgorod, Nizhny Novgorod, Russia
| |
Collapse
|
11
|
Mei YY, Lee MH, Cheng TC, Hsiao IH, Wu DC, Zhou N. NMDA receptors sustain but do not initiate neuronal depolarization in spreading depolarization. Neurobiol Dis 2020; 145:105071. [PMID: 32890774 DOI: 10.1016/j.nbd.2020.105071] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Revised: 08/26/2020] [Accepted: 08/30/2020] [Indexed: 12/18/2022] Open
Abstract
Spreading depolarization (SD) represents a neurological process characterized by a massive, self-sustaining wave of brain cell depolarization. Understanding its mechanism is important for treating ischemic or hemorrhagic stroke and migraine with aura. Many believed that ion fluxes through NMDA receptors (NMDARs) are responsible for neuronal transmembrane currents of SD. However, the explicit role of NMDARs remains ambiguous. This is in part due to the limitation of traditional pharmacological approaches in resolving the contribution of NMDARs in different intercellular and intracellular processes of SD. Here, we applied single-cell blockade and genetic deletion methods to remove functional NMDARs from individual hippocampal CA1 neurons in order to examine the role of NMDARs in the depolarization mechanism without affecting the propagation of SD. We analyzed neuronal membrane potential changes to demonstrate that NMDARs are not required for initiating the depolarization. Consistently, neuronal input resistance (RN) revealed a sharp decline at the start of SD, which was unaffected by blocking NMDARs. Instead, the recovery of both membrane potential and RN during the late phase of SD was facilitated by inhibition of NMDARs, indicating that NMDARs are responsible for sustaining the depolarization. Our results strongly indicate that NMDAR activation is not a determinant of the initiation of depolarization but is important for sustaining transmembrane ion fluxes during SD.
Collapse
Affiliation(s)
- Yu-Ying Mei
- Graduate Institute of Biomedical Sciences, China Medical University, Taichung 40402, Taiwan; Translational Medicine Research Center, China Medical University Hospital, Taichung 40402, Taiwan
| | - Ming-Hsueh Lee
- Department of Neurosurgery, Chang Gung Memorial Hospital, Chiayi 61363, Taiwan
| | - Ting-Chun Cheng
- Graduate Institute of Biomedical Sciences, China Medical University, Taichung 40402, Taiwan; Translational Medicine Research Center, China Medical University Hospital, Taichung 40402, Taiwan
| | - I-Han Hsiao
- Department of Neurosurgery, China Medical University Hospital, Taichung 40402, Taiwan
| | - Dong Chuan Wu
- Graduate Institute of Biomedical Sciences, China Medical University, Taichung 40402, Taiwan; Translational Medicine Research Center, China Medical University Hospital, Taichung 40402, Taiwan.
| | - Ning Zhou
- iHuman Institute, ShanghaiTech University, Shanghai 201210, China.
| |
Collapse
|
12
|
Wang YF, Gao YJ. 2019 Academic Annual Meeting and the Frontier Seminar on "Glial Cell Function and Disease" (Nantong, China). ASN Neuro 2019; 11:1759091419863576. [PMID: 31342775 PMCID: PMC6659189 DOI: 10.1177/1759091419863576] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
The contribution of glial activities to the functions, diseases, and repair of
the central nervous system has received increasing attention in neuroscience
studies. To promote the research of glial cells and increase cooperation with
peers, the 2019 Academic Annual Meeting and the Frontier Seminar on “Glial Cell
Function and Disease” was held in Nantong City, Jiangsu Province, China from May
24 to 26. The meeting was organized by Drs. Yong-Jing Gao and Jia-Wei Zhou of
the Chinese Society of Neuroscience Glia Branch. The conference focused on the
physiological and pathological functions of astrocytes, microglia, and
oligodendrocytes with 25 speakers in two plenary speeches and five sections of
more than 180 participants engaged in glial cell research. In the two plenary
lectures, Yutian Wang from the University of British Columbia and Xia Zhang from
the University of Ottawa presented “Development of NMDAR (N-methyl-D-aspartic
acid receptor)-positive allosteric modulators as novel therapeutics for brain
disorders” and “Mechanisms underlying cannabinoid regulation of brain function
and disease,” respectively. The five sections included microglia and disease,
astrocytes and disease, glioma treatment and glial imaging, oligodendrocytes and
disease, and glial–neuronal interactions and disease. This meeting allowed
extensive and in-depth academic exchanges on the latest research and
experimental techniques, represented the highest achievements of Chinese
scholars on glial cells, and promoted the cooperation between peers in the
fields of glia studies.
Collapse
Affiliation(s)
- Yu-Feng Wang
- 1 Department of Physiology, Harbin Medical University, China
| | - Yong-Jing Gao
- 2 Institute of Pain Medicine, Institute of Special Environmental Medicine, Nantong University, China
| |
Collapse
|
13
|
Diverse Actions of Astrocytes in GABAergic Signaling. Int J Mol Sci 2019; 20:ijms20122964. [PMID: 31216630 PMCID: PMC6628243 DOI: 10.3390/ijms20122964] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2019] [Revised: 06/10/2019] [Accepted: 06/14/2019] [Indexed: 01/06/2023] Open
Abstract
An imbalance of excitatory and inhibitory neurotransmission leading to over excitation plays a crucial role in generating seizures, while enhancing GABAergic mechanisms are critical in terminating seizures. In recent years, it has been reported in many studies that astrocytes are deeply involved in synaptic transmission. Astrocytes form a critical component of the “tripartite” synapses by wrapping around the pre- and post-synaptic elements. From this location, astrocytes are known to greatly influence the dynamics of ions and transmitters in the synaptic cleft. Despite recent extensive research on excitatory tripartite synapses, inhibitory tripartite synapses have received less attention, even though they influence inhibitory synaptic transmission by affecting chloride and GABA concentration dynamics. In this review, we will discuss the diverse actions of astrocytic chloride and GABA homeostasis at GABAergic tripartite synapses. We will then consider the pathophysiological impacts of disturbed GABA homeostasis at the tripartite synapse.
Collapse
|
14
|
Unekawa M, Tomita Y, Toriumi H, Osada T, Masamoto K, Kawaguchi H, Izawa Y, Itoh Y, Kanno I, Suzuki N, Nakahara J. Spatiotemporal dynamics of red blood cells in capillaries in layer I of the cerebral cortex and changes in arterial diameter during cortical spreading depression and response to hypercapnia in anesthetized mice. Microcirculation 2019; 26:e12552. [PMID: 31050358 DOI: 10.1111/micc.12552] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2018] [Revised: 04/21/2019] [Accepted: 04/29/2019] [Indexed: 12/26/2022]
Abstract
OBJECTIVE Control of red blood cell velocity in capillaries is essential to meet local neuronal metabolic requirements, although changes of capillary diameter are limited. To further understand the microcirculatory response during cortical spreading depression, we analyzed the spatiotemporal changes of red blood cell velocity in intraparenchymal capillaries. METHODS In urethane-anesthetized Tie2-green fluorescent protein transgenic mice, the velocity of fluorescence-labeled red blood cells flowing in capillaries in layer I of the cerebral cortex was automatically measured with our Matlab domain software (KEIO-IS2) in sequential images obtained with a high-speed camera laser-scanning confocal fluorescence microscope system. RESULTS Cortical spreading depression repeatedly increased the red blood cell velocity prior to arterial constriction/dilation. During the first cortical spreading depression, red blood cell velocity significantly decreased, and sluggishly moving or retrograde-moving red blood cells were observed, concomitantly with marked arterial constriction. The velocity subsequently returned to around the basal level, while oligemia after cortical spreading depression with slight vasoconstriction remained. After several passages of cortical spreading depression, hypercapnia-induced increase of red blood cell velocity, regional cerebral blood flow and arterial diameter were all significantly reduced, and the correlations among them became extremely weak. CONCLUSIONS Taken together with our previous findings, these simultaneous measurements of red blood cell velocity in multiple capillaries, arterial diameter and regional cerebral blood flow support the idea that red blood cell flow might be altered independently, at least in part, from arterial regulation, that neuro-capillary coupling plays a role in rapidly meeting local neural demand.
Collapse
Affiliation(s)
- Miyuki Unekawa
- Department of Neurology, Keio University School of Medicine, Tokyo, Japan.,Tomita Hospital, Okazaki, Japan
| | - Yutaka Tomita
- Department of Neurology, Keio University School of Medicine, Tokyo, Japan.,Tomita Hospital, Okazaki, Japan
| | - Haruki Toriumi
- Department of Neurology, Keio University School of Medicine, Tokyo, Japan
| | - Takashi Osada
- Department of Neurology, Keio University School of Medicine, Tokyo, Japan
| | - Kazuto Masamoto
- Brain Science Inspired Life Support Research Center, University of Electro-Communications, Chofu, Japan.,Department of Functional Brain Imaging Research, National Institute of Radiological Sciences, Chiba, Japan
| | - Hiroshi Kawaguchi
- Department of Functional Brain Imaging Research, National Institute of Radiological Sciences, Chiba, Japan.,Human Informatics Research Institute, National Institute of Advanced Industrial Science and Technology, Tsukuba, Japan
| | - Yoshikane Izawa
- Department of Neurology, Keio University School of Medicine, Tokyo, Japan
| | - Yoshiaki Itoh
- Department of Neurology, Osaka City University Graduate School of Medicine, Osaka, Japan
| | - Iwao Kanno
- Department of Functional Brain Imaging Research, National Institute of Radiological Sciences, Chiba, Japan
| | - Norihiro Suzuki
- Department of Neurology, Keio University School of Medicine, Tokyo, Japan.,Department of Neurology, Shonan Keiiku Hospital, Fujisawa, Japan
| | - Jin Nakahara
- Department of Neurology, Keio University School of Medicine, Tokyo, Japan
| |
Collapse
|
15
|
Aberrant Calcium Signals in Reactive Astrocytes: A Key Process in Neurological Disorders. Int J Mol Sci 2019; 20:ijms20040996. [PMID: 30823575 PMCID: PMC6413203 DOI: 10.3390/ijms20040996] [Citation(s) in RCA: 85] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2019] [Revised: 02/20/2019] [Accepted: 02/21/2019] [Indexed: 02/06/2023] Open
Abstract
Astrocytes are abundant cells in the brain that regulate multiple aspects of neural tissue homeostasis by providing structural and metabolic support to neurons, maintaining synaptic environments and regulating blood flow. Recent evidence indicates that astrocytes also actively participate in brain functions and play a key role in brain disease by responding to neuronal activities and brain insults. Astrocytes become reactive in response to injury and inflammation, which is typically described as hypertrophy with increased expression of glial fibrillary acidic protein (GFAP). Reactive astrocytes are frequently found in many neurological disorders and are a hallmark of brain disease. Furthermore, reactive astrocytes may drive the initiation and progression of disease processes. Recent improvements in the methods to visualize the activity of reactive astrocytes in situ and in vivo have helped elucidate their functions. Ca2+ signals in reactive astrocytes are closely related to multiple aspects of disease and can be a good indicator of disease severity/state. In this review, we summarize recent findings concerning reactive astrocyte Ca2+ signals. We discuss the molecular mechanisms underlying aberrant Ca2+ signals in reactive astrocytes and the functional significance of aberrant Ca2+ signals in neurological disorders.
Collapse
|
16
|
Pál B. Involvement of extrasynaptic glutamate in physiological and pathophysiological changes of neuronal excitability. Cell Mol Life Sci 2018; 75:2917-2949. [PMID: 29766217 PMCID: PMC11105518 DOI: 10.1007/s00018-018-2837-5] [Citation(s) in RCA: 72] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2018] [Revised: 04/27/2018] [Accepted: 05/07/2018] [Indexed: 12/14/2022]
Abstract
Glutamate is the most abundant neurotransmitter of the central nervous system, as the majority of neurons use glutamate as neurotransmitter. It is also well known that this neurotransmitter is not restricted to synaptic clefts, but found in the extrasynaptic regions as ambient glutamate. Extrasynaptic glutamate originates from spillover of synaptic release, as well as from astrocytes and microglia. Its concentration is magnitudes lower than in the synaptic cleft, but receptors responding to it have higher affinity for it. Extrasynaptic glutamate receptors can be found in neuronal somatodendritic location, on astroglia, oligodendrocytes or microglia. Activation of them leads to changes of neuronal excitability with different amplitude and kinetics. Extrasynaptic glutamate is taken up by neurons and astrocytes mostly via EAAT transporters, and astrocytes, in turn metabolize it to glutamine. Extrasynaptic glutamate is involved in several physiological phenomena of the central nervous system. It regulates neuronal excitability and synaptic strength by involving astroglia; contributing to learning and memory formation, neurosecretory and neuromodulatory mechanisms, as well as sleep homeostasis.The extrasynaptic glutamatergic system is affected in several brain pathologies related to excitotoxicity, neurodegeneration or neuroinflammation. Being present in dementias, neurodegenerative and neuropsychiatric diseases or tumor invasion in a seemingly uniform way, the system possibly provides a common component of their pathogenesis. Although parts of the system are extensively discussed by several recent reviews, in this review I attempt to summarize physiological actions of the extrasynaptic glutamate on neuronal excitability and provide a brief insight to its pathology for basic understanding of the topic.
Collapse
Affiliation(s)
- Balázs Pál
- Department of Physiology, Faculty of Medicine, University of Debrecen, Nagyerdei krt 98, Debrecen, 4012, Hungary.
| |
Collapse
|
17
|
Sompol P, Norris CM. Ca 2+, Astrocyte Activation and Calcineurin/NFAT Signaling in Age-Related Neurodegenerative Diseases. Front Aging Neurosci 2018; 10:199. [PMID: 30038565 PMCID: PMC6046440 DOI: 10.3389/fnagi.2018.00199] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2018] [Accepted: 06/12/2018] [Indexed: 12/12/2022] Open
Abstract
Mounting evidence supports a fundamental role for Ca2+ dysregulation in astrocyte activation. Though the activated astrocyte phenotype is complex, cell-type targeting approaches have revealed a number of detrimental roles of activated astrocytes involving neuroinflammation, release of synaptotoxic factors and loss of glutamate regulation. Work from our lab and others has suggested that the Ca2+/calmodulin dependent protein phosphatase, calcineurin (CN), provides a critical link between Ca2+ dysregulation and the activated astrocyte phenotype. A proteolyzed, hyperactivated form of CN appears at high levels in activated astrocytes in both human tissue and rodent tissue around regions of amyloid and vascular pathology. Similar upregulation of the CN-dependent transcription factor nuclear factor of activated T cells (NFAT4) also appears in activated astrocytes in mouse models of Alzheimer's disease (ADs) and traumatic brain injury (TBI). Major consequences of hyperactivated CN/NFAT4 signaling in astrocytes are neuroinflammation, synapse dysfunction and glutamate dysregulation/excitotoxicity, which will be covered in this review article.
Collapse
Affiliation(s)
- Pradoldej Sompol
- Sanders-Brown Center on Aging, University of Kentucky College of Medicine, Lexington, KY, United States
| | - Christopher M Norris
- Sanders-Brown Center on Aging, University of Kentucky College of Medicine, Lexington, KY, United States.,Department of Pharmacology and Nutritional Sciences, University of Kentucky College of Medicine, Lexington, KY, United States
| |
Collapse
|