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Sucha P, Hermanova Z, Chmelova M, Kirdajova D, Camacho Garcia S, Marchetti V, Vorisek I, Tureckova J, Shany E, Jirak D, Anderova M, Vargova L. The absence of AQP4/TRPV4 complex substantially reduces acute cytotoxic edema following ischemic injury. Front Cell Neurosci 2022; 16:1054919. [PMID: 36568889 PMCID: PMC9773096 DOI: 10.3389/fncel.2022.1054919] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2022] [Accepted: 11/22/2022] [Indexed: 12/13/2022] Open
Abstract
Introduction Astrocytic Aquaporin 4 (AQP4) and Transient receptor potential vanilloid 4 (TRPV4) channels form a functional complex that likely influences cell volume regulation, the development of brain edema, and the severity of the ischemic injury. However, it remains to be fully elucidated whether blocking these channels can serve as a therapeutic approach to alleviate the consequences of having a stroke. Methods and results In this study, we used in vivo magnetic resonance imaging (MRI) to quantify the extent of brain lesions one day (D1) and seven days (D7) after permanent middle cerebral artery occlusion (pMCAO) in AQP4 or TRPV4 knockouts and mice with simultaneous deletion of both channels. Our results showed that deletion of AQP4 or TRPV4 channels alone leads to a significant worsening of ischemic brain injury at both time points, whereas their simultaneous deletion results in a smaller brain lesion at D1 but equal tissue damage at D7 when compared with controls. Immunohistochemical analysis 7 days after pMCAO confirmed the MRI data, as the brain lesion was significantly greater in AQP4 or TRPV4 knockouts than in controls and double knockouts. For a closer inspection of the TRPV4 and AQP4 channel complex in the development of brain edema, we applied a real-time iontophoretic method in situ to determine ECS diffusion parameters, namely volume fraction (α) and tortuosity (λ). Changes in these parameters reflect alterations in cell volume, and tissue structure during exposure of acute brain slices to models of ischemic conditions in situ, such as oxygen-glucose deprivation (OGD), hypoosmotic stress, or hyperkalemia. The decrease in α was comparable in double knockouts and controls when exposed to hypoosmotic stress or hyperkalemia. However, during OGD, there was no decrease in α in the double knockouts as observed in the controls, which suggests less swelling of the cellular components of the brain. Conclusion Although simultaneous deletion of AQP4 and TRPV4 did not improve the overall outcome of ischemic brain injury, our data indicate that the interplay between AQP4 and TRPV4 channels plays a critical role during neuronal and non-neuronal swelling in the acute phase of ischemic injury.
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Affiliation(s)
- Petra Sucha
- Second Faculty of Medicine, Charles University, Prague, Czechia,Department of Cellular Neurophysiology, Institute of Experimental Medicine of the CAS, Prague, Czechia
| | - Zuzana Hermanova
- Second Faculty of Medicine, Charles University, Prague, Czechia,Department of Cellular Neurophysiology, Institute of Experimental Medicine of the CAS, Prague, Czechia
| | - Martina Chmelova
- Second Faculty of Medicine, Charles University, Prague, Czechia,Department of Cellular Neurophysiology, Institute of Experimental Medicine of the CAS, Prague, Czechia
| | - Denisa Kirdajova
- Department of Cellular Neurophysiology, Institute of Experimental Medicine of the CAS, Prague, Czechia
| | - Sara Camacho Garcia
- Department of Cellular Neurophysiology, Institute of Experimental Medicine of the CAS, Prague, Czechia
| | - Valeria Marchetti
- Second Faculty of Medicine, Charles University, Prague, Czechia,Department of Cellular Neurophysiology, Institute of Experimental Medicine of the CAS, Prague, Czechia
| | - Ivan Vorisek
- Department of Cellular Neurophysiology, Institute of Experimental Medicine of the CAS, Prague, Czechia
| | - Jana Tureckova
- Department of Cellular Neurophysiology, Institute of Experimental Medicine of the CAS, Prague, Czechia
| | - Eyar Shany
- Department of Diagnostic and Interventional Radiology, Institute of Clinical and Experimental Medicine, Prague, Czechia
| | - Daniel Jirak
- Department of Diagnostic and Interventional Radiology, Institute of Clinical and Experimental Medicine, Prague, Czechia,First Faculty of Medicine, Institute of Biophysics and Informatics, Charles University, Prague, Czechia
| | - Miroslava Anderova
- Second Faculty of Medicine, Charles University, Prague, Czechia,Department of Cellular Neurophysiology, Institute of Experimental Medicine of the CAS, Prague, Czechia,*Correspondence: Miroslava Anderova,
| | - Lydia Vargova
- Second Faculty of Medicine, Charles University, Prague, Czechia,Department of Cellular Neurophysiology, Institute of Experimental Medicine of the CAS, Prague, Czechia
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2
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Gooch HM, Bluett T, Perumal MB, Vo HD, Fletcher LN, Papacostas J, Jeffree RL, Wood M, Colditz MJ, McMillen J, Tsahtsarlis T, Amato D, Campbell R, Gillinder L, Williams SR. High-fidelity dendritic sodium spike generation in human layer 2/3 neocortical pyramidal neurons. Cell Rep 2022; 41:111500. [DOI: 10.1016/j.celrep.2022.111500] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2022] [Revised: 08/22/2022] [Accepted: 09/21/2022] [Indexed: 11/03/2022] Open
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Gorlewicz A, Barthet G, Zucca S, Vincent P, Griguoli M, Grosjean N, Wilczynski G, Mulle C. The Deletion of GluK2 Alters Cholinergic Control of Neuronal Excitability. Cereb Cortex 2022; 32:2907-2923. [PMID: 34730179 DOI: 10.1093/cercor/bhab390] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Revised: 09/28/2021] [Accepted: 09/29/2021] [Indexed: 11/14/2022] Open
Abstract
Kainate receptors (KARs) are key regulators of synaptic circuits by acting at pre- and postsynaptic sites through either ionotropic or metabotropic actions. KARs can be activated by kainate, a potent neurotoxin, which induces acute convulsions. Here, we report that the acute convulsive effect of kainate mostly depends on GluK2/GluK5 containing KARs. By contrast, the acute convulsive activity of pilocarpine and pentylenetetrazol is not alleviated in the absence of KARs. Unexpectedly, the genetic inactivation of GluK2 rather confers increased susceptibility to acute pilocarpine-induced seizures. The mechanism involves an enhanced excitability of GluK2-/- CA3 pyramidal cells compared with controls upon pilocarpine application. Finally, we uncover that the absence of GluK2 increases pilocarpine modulation of Kv7/M currents. Taken together, our findings reveal that GluK2-containing KARs can control the excitability of hippocampal circuits through interaction with the neuromodulatory cholinergic system.
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Affiliation(s)
- Adam Gorlewicz
- Interdisciplinary Institute for Neuroscience, UMR 5297, Centre National de la Recherche Scientifique, F-33000 Bordeaux, France
- Interdisciplinary Institute for Neuroscience, UMR 5297, University of Bordeaux, F-33000 Bordeaux, France
- Laboratory of Molecular and Systemic Neuromorphology, Nencki Institute of Experimental Biology, 02-093 Warsaw, Poland
| | - Gael Barthet
- Interdisciplinary Institute for Neuroscience, UMR 5297, Centre National de la Recherche Scientifique, F-33000 Bordeaux, France
- Interdisciplinary Institute for Neuroscience, UMR 5297, University of Bordeaux, F-33000 Bordeaux, France
| | - Stefano Zucca
- Interdisciplinary Institute for Neuroscience, UMR 5297, Centre National de la Recherche Scientifique, F-33000 Bordeaux, France
- Interdisciplinary Institute for Neuroscience, UMR 5297, University of Bordeaux, F-33000 Bordeaux, France
| | - Peggy Vincent
- Interdisciplinary Institute for Neuroscience, UMR 5297, Centre National de la Recherche Scientifique, F-33000 Bordeaux, France
- Interdisciplinary Institute for Neuroscience, UMR 5297, University of Bordeaux, F-33000 Bordeaux, France
| | - Marilena Griguoli
- Interdisciplinary Institute for Neuroscience, UMR 5297, Centre National de la Recherche Scientifique, F-33000 Bordeaux, France
- Interdisciplinary Institute for Neuroscience, UMR 5297, University of Bordeaux, F-33000 Bordeaux, France
| | - Noëlle Grosjean
- Interdisciplinary Institute for Neuroscience, UMR 5297, Centre National de la Recherche Scientifique, F-33000 Bordeaux, France
- Interdisciplinary Institute for Neuroscience, UMR 5297, University of Bordeaux, F-33000 Bordeaux, France
| | - Grzegorz Wilczynski
- Laboratory of Molecular and Systemic Neuromorphology, Nencki Institute of Experimental Biology, 02-093 Warsaw, Poland
| | - Christophe Mulle
- Interdisciplinary Institute for Neuroscience, UMR 5297, Centre National de la Recherche Scientifique, F-33000 Bordeaux, France
- Interdisciplinary Institute for Neuroscience, UMR 5297, University of Bordeaux, F-33000 Bordeaux, France
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4
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Chmelova M, Sucha P, Bochin M, Vorisek I, Pivonkova H, Hermanova Z, Anderova M, Vargova L. The role of aquaporin-4 and transient receptor potential vaniloid isoform 4 channels in the development of cytotoxic edema and associated extracellular diffusion parameter changes. Eur J Neurosci 2019; 50:1685-1699. [PMID: 30633415 DOI: 10.1111/ejn.14338] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2018] [Revised: 12/27/2018] [Accepted: 01/04/2019] [Indexed: 11/30/2022]
Abstract
The proper function of the nervous system is dependent on the balance of ions and water between the intracellular and extracellular space (ECS). It has been suggested that the interaction of aquaporin-4 (AQP4) and the transient receptor potential vaniloid isoform 4 (TRPV4) channels play a role in water balance and cell volume regulation, and indirectly, of the ECS volume. Using the real-time iontophoretic method, we studied the changes of the ECS diffusion parameters: ECS volume fraction α (α = ECS volume fraction/total tissue volume) and tortuosity λ (λ2 = free/apparent diffusion coefficient) in mice with a genetic deficiency of AQP4 or TRPV4 channels, and in control animals. The used models of cytotoxic edema included: mild and severe hypotonic stress or oxygen-glucose deprivation (OGD) in situ and terminal ischemia/anoxia in vivo. This study shows that an AQP4 or TRPV4 deficit slows down the ECS volume shrinkage during severe ischemia in vivo. We further demonstrate that a TRPV4 deficit slows down the velocity and attenuates an extent of the ECS volume decrease during OGD treatment in situ. However, in any of the cytotoxic edema models in situ (OGD, mild or severe hypotonic stress), we did not detect any alterations in the cell swelling or volume regulation caused by AQP4 deficiency. Overall, our results indicate that the AQP4 and TRPV4 channels may play a crucial role in severe pathological states associated with their overexpression and enhanced cell swelling. However, detailed interplay between AQP4 and TRPV4 channels requires further studies and additional research.
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Affiliation(s)
- Martina Chmelova
- Department of Neuroscience, 2nd Faculty of Medicine, Charles University, Prague, Czech Republic.,Department of Cellular Neurophysiology, Institute of Experimental Medicine of the CAS, Prague, Czech Republic
| | - Petra Sucha
- Department of Neuroscience, 2nd Faculty of Medicine, Charles University, Prague, Czech Republic.,Department of Cellular Neurophysiology, Institute of Experimental Medicine of the CAS, Prague, Czech Republic
| | - Marcel Bochin
- Department of Neuroscience, 2nd Faculty of Medicine, Charles University, Prague, Czech Republic.,Department of Cellular Neurophysiology, Institute of Experimental Medicine of the CAS, Prague, Czech Republic
| | - Ivan Vorisek
- Department of Cellular Neurophysiology, Institute of Experimental Medicine of the CAS, Prague, Czech Republic
| | - Helena Pivonkova
- Department of Cellular Neurophysiology, Institute of Experimental Medicine of the CAS, Prague, Czech Republic
| | - Zuzana Hermanova
- Department of Cellular Neurophysiology, Institute of Experimental Medicine of the CAS, Prague, Czech Republic
| | - Miroslava Anderova
- Department of Neuroscience, 2nd Faculty of Medicine, Charles University, Prague, Czech Republic.,Department of Cellular Neurophysiology, Institute of Experimental Medicine of the CAS, Prague, Czech Republic
| | - Lydia Vargova
- Department of Neuroscience, 2nd Faculty of Medicine, Charles University, Prague, Czech Republic.,Department of Cellular Neurophysiology, Institute of Experimental Medicine of the CAS, Prague, Czech Republic
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5
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So EC, Foo NP, Ko SY, Wu SN. Bisoprolol, Known to Be a Selective β₁-Receptor Antagonist, Differentially but Directly Suppresses I K(M) and I K(erg) in Pituitary Cells and Hippocampal Neurons. Int J Mol Sci 2019; 20:E657. [PMID: 30717422 PMCID: PMC6386942 DOI: 10.3390/ijms20030657] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2019] [Revised: 01/27/2019] [Accepted: 01/30/2019] [Indexed: 12/27/2022] Open
Abstract
Bisoprolol (BIS) is a selective antagonist of β₁ adrenergic receptors. We examined the effects of BIS on M-type K⁺ currents (IK(M)) or erg-mediated K⁺ currents (IK(erg)) in pituitary GH3, R1220 cells, and hippocampal mHippoE-14 cells. As GH₃ cells were exposed to BIS, amplitude of IK(M) was suppressed with an IC50 value of 1.21 μM. The BIS-induced suppression of IK(M) amplitude was not affected by addition of isoproterenol or ractopamine, but attenuated by flupirtine or ivabradine. In cell-attached current, BIS decreased the open probability of M-type K⁺ (KM) channels, along with decreased mean opening time of the channel. BIS decreased IK(erg) amplitude with an IC50 value of 6.42 μM. Further addition of PD-118057 attenuated BIS-mediated inhibition of IK(erg). Under current-clamp conditions, BIS depolarization increased the firing of spontaneous action potentials in GH₃ cells; addition of flupirtine, but not ractopamine, reversed BIS-induced firing rate. In R1220 cells, BIS suppressed IK(M); subsequent application of ML-213(Kv7.2 channel activator) reversed BIS-induced suppression of the current. In hippocampal mHippoE-14 neurons, BIS inhibited IK(M) to a greater extent compared to its depressant effect on IK(erg). This demonstrated that in pituitary cells and hippocampal neurons the presence of BIS is capable of directly and differentially suppressing IK(M) and IK(erg), despite its antagonism of β₁-adrenergic receptors.
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Affiliation(s)
- Edmund Cheung So
- Department of Anesthesia, An Nan Hospital, China Medical University, Tainan 70965, Taiwan.
- Department of Anesthesia, China Medical University, Taichung 40402, Taiwan.
- Graduate Institute of Medical Sciences, Chang Jung Christian University, Tainan 71101, Taiwan.
| | - Ning-Ping Foo
- Department of Anesthesia, An Nan Hospital, China Medical University, Tainan 70965, Taiwan.
- Graduate Institute of Medical Sciences, Chang Jung Christian University, Tainan 71101, Taiwan.
- Department of Emergency Medicine, An Nan Hospital, China Medical University, Tainan 70965, Taiwan.
| | - Shun Yao Ko
- Graduate Institute of Medical Sciences, Chang Jung Christian University, Tainan 71101, Taiwan.
| | - Sheng-Nan Wu
- Institute of Basic Medical Sciences, National Cheng Kung University Medical College, Tainan 70101, Taiwan.
- Department of Physiology, National Cheng Kung University Medical College, Tainan 70101, Taiwan.
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6
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Glykys J, Duquette E, Rahmati N, Duquette K, Staley KJ. Mannitol decreases neocortical epileptiform activity during early brain development via cotransport of chloride and water. Neurobiol Dis 2019; 125:163-175. [PMID: 30711483 DOI: 10.1016/j.nbd.2019.01.024] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2018] [Revised: 01/28/2019] [Accepted: 01/30/2019] [Indexed: 12/31/2022] Open
Abstract
Seizures and brain injury lead to water and Cl- accumulation in neurons. The increase in intraneuronal Cl- concentration ([Cl-]i) depolarizes the GABAA reversal potential (EGABA) and worsens seizure activity. Neocortical neuronal membranes have a low water permeability due to the lack of aquaporins necessary to move free water. Instead, neurons use cotransport of ions including Cl- to move water. Thus, increasing the extracellular osmolarity during seizures should result in an outward movement of water and salt, reducing [Cl-]i and improving GABAA receptor-mediated inhibition. We tested the effects of hyperosmotic therapy with a clinically relevant dose of mannitol (20 mM) on epileptiform activity, spontaneous multiunit activity, spontaneous inhibitory post-synaptic currents (sIPSCs), [Cl-]i, and neuronal volume in layer IV/V of the developing neocortex of C57BL/6 and Clomeleon mice. Using electrophysiological techniques and multiphoton imaging in acute brain slices (post-natal day 7-12) and organotypic neocortical slice cultures (post-natal day 14), we observed that mannitol: 1) decreased epileptiform activity, 2) decreased neuronal volume and [Cl-]i through CCCs, 3) decreased spontaneous multi-unit activity frequency but not amplitude, and 4) restored the anticonvulsant efficacy of the GABAA receptor modulator diazepam. Increasing extracellular osmolarity by 20 mOsm with hypertonic saline did not decrease epileptiform activity. We conclude that an increase in extracellular osmolarity by mannitol mediates the efflux of [Cl-]i and water through CCCs, which results in a decrease in epileptiform activity and enhances benzodiazepine actions in the developing neocortex in vitro. Novel treatments aimed to decrease neuronal volume may concomitantly decrease [Cl-]i and improve seizure control.
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Affiliation(s)
- J Glykys
- Department of Neurology, Massachusetts General Hospital, Boston 02114, United States; Harvard Medical School, Boston, MA 02115, United States.
| | - E Duquette
- Department of Neurology, Massachusetts General Hospital, Boston 02114, United States
| | - N Rahmati
- Department of Neurology, Massachusetts General Hospital, Boston 02114, United States; Harvard Medical School, Boston, MA 02115, United States
| | - K Duquette
- Department of Neurology, Massachusetts General Hospital, Boston 02114, United States; Northeastern University, Boston 02115, United States
| | - K J Staley
- Department of Neurology, Massachusetts General Hospital, Boston 02114, United States; Harvard Medical School, Boston, MA 02115, United States
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7
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Wilson CS, Mongin AA. Cell Volume Control in Healthy Brain and Neuropathologies. CURRENT TOPICS IN MEMBRANES 2018; 81:385-455. [PMID: 30243438 DOI: 10.1016/bs.ctm.2018.07.006] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Regulation of cellular volume is a critical homeostatic process that is intimately linked to ionic and osmotic balance in the brain tissue. Because the brain is encased in the rigid skull and has a very complex cellular architecture, even minute changes in the volume of extracellular and intracellular compartments have a very strong impact on tissue excitability and function. The failure of cell volume control is a major feature of several neuropathologies, such as hyponatremia, stroke, epilepsy, hyperammonemia, and others. There is strong evidence that such dysregulation, especially uncontrolled cell swelling, plays a major role in adverse pathological outcomes. To protect themselves, brain cells utilize a variety of mechanisms to maintain their optimal volume, primarily by releasing or taking in ions and small organic molecules through diverse volume-sensitive ion channels and transporters. In principle, the mechanisms of cell volume regulation are not unique to the brain and share many commonalities with other tissues. However, because ions and some organic osmolytes (e.g., major amino acid neurotransmitters) have a strong impact on neuronal excitability, cell volume regulation in the brain is a surprisingly treacherous process, which may cause more harm than good. This topical review covers the established and emerging information in this rapidly developing area of physiology.
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Affiliation(s)
- Corinne S Wilson
- Department of Neuroscience and Experimental Therapeutics, Albany Medical College, Albany, NY, United States
| | - Alexander A Mongin
- Department of Neuroscience and Experimental Therapeutics, Albany Medical College, Albany, NY, United States; Department of Biophysics and Functional Diagnostics, Siberian State Medical University, Tomsk, Russian Federation
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8
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Wei X, Zhang Y, Yin B, Wen J, Cheng J, Fu X. The expression and function of KCNQ potassium channels in human chorionic plate arteries from women with normal pregnancies and pre-eclampsia. PLoS One 2018; 13:e0192122. [PMID: 29579054 PMCID: PMC5868761 DOI: 10.1371/journal.pone.0192122] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2017] [Accepted: 01/18/2018] [Indexed: 11/25/2022] Open
Abstract
Pre-eclampsia is associated with altered maternal and placental vascular reactivity. Kv7 channels (encoded by KCNQ 1–5 genes) are a potential contributor to the regulation of vascular tone in CPAs (chorionic plate arteries) during normal pregnancy. The aim of this study is to establish the expression profile of KCNQ subunits in CPAs taken from women with preeclampsia or normotensive women and to examine the functional relevance of the Kv7 channels on an altered expression profile of KCNQ subunits. The effects of Kv7 channel modulators on CPAs were investigated by tension measurement. Quantitative PCR experiments were used to analyze the expression of KCNQ genes. Western blotting and immunofluorescence were both used to analyze the protein expression of Kv7 channels. Finally, in CPAs from normotensive women, the Kv7 channel blocker XE991 increased arterial basal tone and U46619-induced contraction, and pre-contracted CPAs (10−7 M U46619) exhibited significant relaxation following treatment with Retigabine(Kv7.2–7.5 activator) and BMS-204352(Kv7.2–7.5 activator). However, ICA-27243(selective KCNQ2 and KCNQ3 activator) and ML277(selective KV7.1 activator) had no significant effect on tension in the pre-contracted CPAs. Conversely, compared with CPAs from normotensive women, the effects of XE991 on basal tone and agonist (U46619)-induced contractions in CPAs from women with preeclampsia were markedly attenuated. Moreover, the relaxation effects of Retigabine and BMS-204352 on pre-contracted CPA vessels from women with pre-eclampsia were also markedly down-regulated. Interestingly, the relaxation ability of ICA-27243 in pre-contracted CPA vessels in women with pre-eclampsia was enhanced. The mRNA of KCNQ3 was specifically up-regulated, whereas those for KCNQ4 and KCNQ5 were down-regulated in CPAs from women with pre-eclampsia compared with those in normotensive women. Similar observations were found in a subsequent analysis of protein expression of KCNQ genes 3–5. Thus, down-regulated Kv7 channel function in tension regulation of CPAs in women with pre-eclampsia could be associated with considerably altered expression profiles of Kv7 subunits.
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Affiliation(s)
- Xiaohong Wei
- Department of Gynecology and Obstetrics, the Affiliated Hospital of Southwest Medical University, Luzhou, Sichuan, China
| | - Yujiao Zhang
- Department of Gynecology and Obstetrics, the Affiliated Hospital of Southwest Medical University, Luzhou, Sichuan, China
| | - Benlan Yin
- Department of Gynecology and Obstetrics, the Affiliated Hospital of Southwest Medical University, Luzhou, Sichuan, China
| | - Jing Wen
- Key Laboratory of Medical Electrophysiology of Ministry of Education, Collaborative Innovation Center for Prevention and Treatment of Cardiovascular Research, Southwest Medical University, Luzhou, Sichuan, China
| | - Jun Cheng
- Key Laboratory of Medical Electrophysiology of Ministry of Education, Collaborative Innovation Center for Prevention and Treatment of Cardiovascular Research, Southwest Medical University, Luzhou, Sichuan, China
| | - Xiaodong Fu
- Department of Gynecology and Obstetrics, the Affiliated Hospital of Southwest Medical University, Luzhou, Sichuan, China
- * E-mail:
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Murphy TR, Davila D, Cuvelier N, Young LR, Lauderdale K, Binder DK, Fiacco TA. Hippocampal and Cortical Pyramidal Neurons Swell in Parallel with Astrocytes during Acute Hypoosmolar Stress. Front Cell Neurosci 2017; 11:275. [PMID: 28979186 PMCID: PMC5611379 DOI: 10.3389/fncel.2017.00275] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2017] [Accepted: 08/28/2017] [Indexed: 01/08/2023] Open
Abstract
Normal nervous system function is critically dependent on the balance of water and ions in the extracellular space (ECS). Pathological reduction in brain interstitial osmolarity results in osmotically-driven flux of water into cells, causing cellular edema which reduces the ECS and increases neuronal excitability and risk of seizures. Astrocytes are widely considered to be particularly susceptible to cellular edema due to selective expression of the water channel aquaporin-4 (AQP4). The apparent resistance of pyramidal neurons to osmotic swelling has been attributed to lack of functional water channels. In this study we report rapid volume changes in CA1 pyramidal cells in hypoosmolar ACSF (hACSF) that are equivalent to volume changes in astrocytes across a variety of conditions. Astrocyte and neuronal swelling was significant within 1 min of exposure to 17 or 40% hACSF, was rapidly reversible upon return to normosmolar ACSF, and repeatable upon re-exposure to hACSF. Neuronal swelling was not an artifact of patch clamp, occurred deep in tissue, was similar at physiological vs. room temperature, and occurred in both juvenile and adult hippocampal slices. Neuronal swelling was neither inhibited by TTX, nor by antagonists of NMDA or AMPA receptors, suggesting that it was not occurring as a result of excitotoxicity. Surprisingly, genetic deletion of AQP4 did not inhibit, but rather augmented, astrocyte swelling in severe hypoosmolar conditions. Taken together, our results indicate that neurons are not osmoresistant as previously reported, and that osmotic swelling is driven by an AQP4-independent mechanism.
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Affiliation(s)
- Thomas R. Murphy
- Division of Biomedical Sciences, School of Medicine, University of California, RiversideRiverside, CA, United States
- Center for Glial-Neuronal Interactions, University of California, RiversideRiverside, CA, United States
| | - David Davila
- Center for Glial-Neuronal Interactions, University of California, RiversideRiverside, CA, United States
- Department of Cell Biology and Neuroscience, University of California, RiversideRiverside, CA, United States
| | - Nicholas Cuvelier
- Center for Glial-Neuronal Interactions, University of California, RiversideRiverside, CA, United States
- Department of Cell Biology and Neuroscience, University of California, RiversideRiverside, CA, United States
| | - Leslie R. Young
- Center for Glial-Neuronal Interactions, University of California, RiversideRiverside, CA, United States
- Department of Cell Biology and Neuroscience, University of California, RiversideRiverside, CA, United States
| | - Kelli Lauderdale
- Division of Biomedical Sciences, School of Medicine, University of California, RiversideRiverside, CA, United States
- Center for Glial-Neuronal Interactions, University of California, RiversideRiverside, CA, United States
| | - Devin K. Binder
- Division of Biomedical Sciences, School of Medicine, University of California, RiversideRiverside, CA, United States
- Center for Glial-Neuronal Interactions, University of California, RiversideRiverside, CA, United States
| | - Todd A. Fiacco
- Center for Glial-Neuronal Interactions, University of California, RiversideRiverside, CA, United States
- Department of Cell Biology and Neuroscience, University of California, RiversideRiverside, CA, United States
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10
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Barkai O, Goldstein RH, Caspi Y, Katz B, Lev S, Binshtok AM. The Role of Kv7/M Potassium Channels in Controlling Ectopic Firing in Nociceptors. Front Mol Neurosci 2017; 10:181. [PMID: 28659757 PMCID: PMC5468463 DOI: 10.3389/fnmol.2017.00181] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2017] [Accepted: 05/24/2017] [Indexed: 11/13/2022] Open
Abstract
Peripheral nociceptive neurons encode and convey injury-inducing stimuli toward the central nervous system. In normal conditions, tight control of nociceptive resting potential prevents their spontaneous activation. However, in many pathological conditions the control of membrane potential is disrupted, leading to ectopic, stimulus-unrelated firing of nociceptive neurons, which is correlated to spontaneous pain. We have investigated the role of KV7/M channels in stabilizing membrane potential and impeding spontaneous firing of nociceptive neurons. These channels generate low voltage-activating, noninactivating M-type K+ currents (M-current, IM ), which control neuronal excitability. Using perforated-patch recordings from cultured, rat nociceptor-like dorsal root ganglion neurons, we show that inhibition of M-current leads to depolarization of nociceptive neurons and generation of repetitive firing. To assess to what extent the M-current, acting at the nociceptive terminals, is able to stabilize terminals' membrane potential, thus preventing their ectopic activation, in normal and pathological conditions, we built a multi-compartment computational model of a pseudo-unipolar unmyelinated nociceptive neuron with a realistic terminal tree. The modeled terminal tree was based on the in vivo structure of nociceptive peripheral terminal, which we assessed by in vivo multiphoton imaging of GFP-expressing nociceptive neuronal terminals innervating mice hind paw. By modifying the conductance of the KV7/M channels at the modeled terminal tree (terminal gKV7/M) we have found that 40% of the terminal gKV7/M conductance is sufficient to prevent spontaneous firing, while ~75% of terminal gKV7/M is sufficient to inhibit stimulus induced activation of nociceptive neurons. Moreover, we showed that terminal M-current reduces susceptibility of nociceptive neurons to a small fluctuations of membrane potentials. Furthermore, we simulated how the interaction between terminal persistent sodium current and M-current affects the excitability of the neurons. We demonstrated that terminal M-current in nociceptive neurons impeded spontaneous firing even when terminal Na(V)1.9 channels conductance was substantially increased. On the other hand, when terminal gKV7/M was decreased, nociceptive neurons fire spontaneously after slight increase in terminal Na(V)1.9 conductance. Our results emphasize the pivotal role of M-current in stabilizing membrane potential and hereby in controlling nociceptive spontaneous firing, in normal and pathological conditions.
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Affiliation(s)
- Omer Barkai
- Department of Medical Neurobiology, Institute for Medical Research Israel-Canada, Hadassah School of Medicine, The Hebrew University-Hadassah School of MedicineJerusalem, Israel.,The Edmond and Lily Safra Center for Brain Sciences, The Hebrew University of JerusalemJerusalem, Israel
| | - Robert H Goldstein
- Department of Medical Neurobiology, Institute for Medical Research Israel-Canada, Hadassah School of Medicine, The Hebrew University-Hadassah School of MedicineJerusalem, Israel.,The Edmond and Lily Safra Center for Brain Sciences, The Hebrew University of JerusalemJerusalem, Israel
| | - Yaki Caspi
- Department of Medical Neurobiology, Institute for Medical Research Israel-Canada, Hadassah School of Medicine, The Hebrew University-Hadassah School of MedicineJerusalem, Israel.,The Edmond and Lily Safra Center for Brain Sciences, The Hebrew University of JerusalemJerusalem, Israel
| | - Ben Katz
- Department of Medical Neurobiology, Institute for Medical Research Israel-Canada, Hadassah School of Medicine, The Hebrew University-Hadassah School of MedicineJerusalem, Israel.,The Edmond and Lily Safra Center for Brain Sciences, The Hebrew University of JerusalemJerusalem, Israel
| | - Shaya Lev
- Department of Medical Neurobiology, Institute for Medical Research Israel-Canada, Hadassah School of Medicine, The Hebrew University-Hadassah School of MedicineJerusalem, Israel.,The Edmond and Lily Safra Center for Brain Sciences, The Hebrew University of JerusalemJerusalem, Israel
| | - Alexander M Binshtok
- Department of Medical Neurobiology, Institute for Medical Research Israel-Canada, Hadassah School of Medicine, The Hebrew University-Hadassah School of MedicineJerusalem, Israel.,The Edmond and Lily Safra Center for Brain Sciences, The Hebrew University of JerusalemJerusalem, Israel
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11
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Turning down the volume: Astrocyte volume change in the generation and termination of epileptic seizures. Neurobiol Dis 2017; 104:24-32. [PMID: 28438505 DOI: 10.1016/j.nbd.2017.04.016] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2017] [Revised: 04/18/2017] [Accepted: 04/20/2017] [Indexed: 12/20/2022] Open
Abstract
Approximately 1% of the global population suffers from epilepsy, a class of disorders characterized by recurrent and unpredictable seizures. Of these cases roughly one-third are refractory to current antiepileptic drugs, which typically target neuronal excitability directly. The events leading to seizure generation and epileptogenesis remain largely unknown, hindering development of new treatments. Some recent experimental models of epilepsy have provided compelling evidence that glial cells, especially astrocytes, could be central to seizure development. One of the proposed mechanisms for astrocyte involvement in seizures is astrocyte swelling, which may promote pathological neuronal firing and synchrony through reduction of the extracellular space and elevated glutamate concentrations. In this review, we discuss the common conditions under which astrocytes swell, the resultant effects on neural excitability, and how seizure development may ultimately be influenced by these effects.
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12
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Tzour A, Leibovich H, Barkai O, Biala Y, Lev S, Yaari Y, Binshtok AM. K V 7/M channels as targets for lipopolysaccharide-induced inflammatory neuronal hyperexcitability. J Physiol 2016; 595:713-738. [PMID: 27506492 DOI: 10.1113/jp272547] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2016] [Accepted: 07/27/2016] [Indexed: 12/11/2022] Open
Abstract
KEY POINTS Neuroinflammation associated with CNS insults leads to neuronal hyperexcitability, which may culminate in epileptiform discharges. Application of the endotoxin lipopolysaccharide (LPS) to brain tissue initiates a neuroinflammatory cascade, providing an experimental model to study the mechanisms of neuroinflammatory neuronal hyperexcitability. Here we show that LPS application to hippocampal slices markedly enhances the excitability of CA1 pyramidal cells by inhibiting a specific potassium current, the M-current, generated by KV 7/M channels, which controls the excitability of almost every neuron in the CNS. The LPS-induced M-current inhibition is triggered by sequential activation of microglia, astrocytes and pyramidal cells, mediated by metabotropic purinergic and glutamatergic transmission, leading to blockade of KV 7/M channels by calcium released from intracellular stores. The identification of the downstream molecular target of neuroinflammation, namely the KV 7/M channel, potentially has far reaching implications for the understanding and treatment of many acute and chronic brain disorders. ABSTRACT Acute brain insults and many chronic brain diseases manifest an innate inflammatory response. The hallmark of this response is glia activation, which promotes repair of damaged tissue, but also induces structural and functional changes that may lead to an increase in neuronal excitability. We have investigated the mechanisms involved in the modulation of neuronal activity by acute inflammation. Initiating inflammatory responses in hippocampal tissue rapidly led to neuronal depolarization and repetitive firing even in the absence of active synaptic transmission. This action was mediated by a complex metabotropic purinergic and glutamatergic glia-to-neuron signalling cascade, leading to the blockade of neuronal KV 7/M channels by Ca2+ released from internal stores. These channels generate the low voltage-activating, non-inactivating M-type K+ current (M-current) that controls intrinsic neuronal excitability, and its inhibition was the predominant cause of the inflammation-induced hyperexcitability. Our discovery that the ubiquitous KV 7/M channels are the downstream target of the inflammation-induced cascade, has far reaching implications for the understanding and treatment of many acute and chronic brain disorders.
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Affiliation(s)
- Arik Tzour
- Department of Medical Neurobiology, Institute for Medical Research Israel-Canada, Hebrew University-Hadassah School of Medicine, Jerusalem, 91120, Israel.,The Edmond and Lily Safra Center for Brain Sciences, Hebrew University of Jerusalem, Israel
| | - Hodaya Leibovich
- Department of Medical Neurobiology, Institute for Medical Research Israel-Canada, Hebrew University-Hadassah School of Medicine, Jerusalem, 91120, Israel.,The Edmond and Lily Safra Center for Brain Sciences, Hebrew University of Jerusalem, Israel
| | - Omer Barkai
- Department of Medical Neurobiology, Institute for Medical Research Israel-Canada, Hebrew University-Hadassah School of Medicine, Jerusalem, 91120, Israel.,The Edmond and Lily Safra Center for Brain Sciences, Hebrew University of Jerusalem, Israel
| | - Yoav Biala
- Department of Medical Neurobiology, Institute for Medical Research Israel-Canada, Hebrew University-Hadassah School of Medicine, Jerusalem, 91120, Israel
| | - Shaya Lev
- Department of Medical Neurobiology, Institute for Medical Research Israel-Canada, Hebrew University-Hadassah School of Medicine, Jerusalem, 91120, Israel.,The Edmond and Lily Safra Center for Brain Sciences, Hebrew University of Jerusalem, Israel
| | - Yoel Yaari
- Department of Medical Neurobiology, Institute for Medical Research Israel-Canada, Hebrew University-Hadassah School of Medicine, Jerusalem, 91120, Israel
| | - Alexander M Binshtok
- Department of Medical Neurobiology, Institute for Medical Research Israel-Canada, Hebrew University-Hadassah School of Medicine, Jerusalem, 91120, Israel.,The Edmond and Lily Safra Center for Brain Sciences, Hebrew University of Jerusalem, Israel
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13
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Role of small conductance Ca²⁺-activated K⁺ channels in controlling CA1 pyramidal cell excitability. J Neurosci 2014; 34:8219-30. [PMID: 24920626 DOI: 10.1523/jneurosci.0936-14.2014] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Small-conductance Ca(2+)-activated K(+) (SK or K(Ca)2) channels are widely expressed in the CNS. In several types of neurons, these channels were shown to become activated during repetitive firing, causing early spike frequency adaptation. In CA1 pyramidal cells, SK channels in dendritic spines were shown to regulate synaptic transmission. However, the presence of functional SK channels in the somata and their role in controlling the intrinsic firing of these neurons has been controversial. Using whole-cell voltage-clamp and current-clamp recordings in acute hippocampal slices and focal applications of irreversible and reversible SK channel blockers, we provide evidence that functional SK channels are expressed in the somata and proximal dendrites of adult rat CA1 pyramidal cells. Although these channels can generate a medium duration afterhyperpolarizing current, they play only an auxiliary role in controlling the intrinsic excitability of these neurons, secondary to the low voltage-activating, noninactivating K(V)7/M channels. As long as K(V)7/M channels are operative, activation of SK channels during repetitive firing does not notably affect the spike output of CA1 pyramidal cells. However, when K(V)7/M channel activity is compromised, SK channel activation significantly and uniquely reduces spike output of these neurons. Therefore, proximal SK channels provide a "second line of defense" against intrinsic hyperexcitability, which may play a role in multiple conditions in which K(V)7/M channels activity is compromised, such as hyposmolarity.
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14
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Albus K, Heinemann U, Kovács R. Network activity in hippocampal slice cultures revealed by long-term in vitro recordings. J Neurosci Methods 2013; 217:1-8. [PMID: 23639918 DOI: 10.1016/j.jneumeth.2013.04.014] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2013] [Revised: 03/21/2013] [Accepted: 04/16/2013] [Indexed: 01/19/2023]
Abstract
Organotypic hippocampal slice cultures (OHSCs) are widely used for anatomical, molecular and electrophysiological studies of the development of neuronal networks. Electrophysiological recordings are usually limited to a single time point during development, and recording conditions differ greatly based on culture conditions. Consequently, little is known about the maturation of neuronal network activity in vitro. Here, we describe a simple method that allows long-term electrophysiological recordings during culture maintenance in a CO2 incubator. We compared the occurrence of spontaneous network activity, including epileptiform activity, in OHSCs (maintained in Neurobasal/B27 serum-free medium) prepared at different postnatal days and investigated the effects of changes in osmolality and pH. Recordings over 48 h revealed spontaneous network activity culminating in seizure-like events (SLEs) in 65.4% of the OHSCs (n=78). SLE incidence peaked during the first 6h following implantation of the microelectrodes and a secondary increase in SLE-incidence began after 9h of recording and averaged 2.65SLEs/h. The initial peak was likely initiated by transient alkalosis induced by the low pCO2 during the positioning of the electrodes, whereas successive changes in the composition of the culture medium might explain the secondary increase in SLE incidence. Notably, changes in osmolality had no effect on SLE induction. In conclusion, long-term recordings in OHSCs will help to reveal changes in spontaneous network activity during maturation. The extent to which the axonal reorganization known to occur in OHSCs contributes to the susceptibility to epileptogenesis remains to be determined.
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Affiliation(s)
- Klaus Albus
- Institute of Neurophysiology, Universitätsmedizin Berlin, Charitéplatz 1, D-10117 Berlin, Germany.
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15
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Talnov AN, Isaeva E, Savotchenko AV, Dovgalets GV, Ochoa JG, Holmes GL, Isaev D. Electrolyte therapy reduces spike-and-wave discharges in the WAG/Rij rat model of absence epilepsy. Epilepsy Behav 2012; 24:399-402. [PMID: 22749239 PMCID: PMC3408819 DOI: 10.1016/j.yebeh.2012.05.018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/16/2012] [Revised: 05/21/2012] [Accepted: 05/24/2012] [Indexed: 10/28/2022]
Abstract
Although antiepileptic drugs are often effective in the control of seizures, some patients show little or no improvement. As alternative treatments, different dietary modifications were shown to be beneficial for patients with poor tolerance for AEDS. Previous reports have shown that rice-based oral electrolyte hydration therapy is effective in seizure control in patients with refractory absence seizures. In the present study, using an animal model of absence epilepsy, we showed that the occurrence of spike-and-wave discharges significantly decreases upon switching to electrolyte therapy. We also showed that consumption of solution with the same osmolarity as rice-based oral electrolyte solution leads to a decrease in the number of spike-and-wave discharges per hour. We suggest that the antiepileptic effect of rice-based oral electrolyte hydration therapy can be at least in part due to hyperosmolarity of the ingested solution.
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Affiliation(s)
- Arkadij N. Talnov
- Department of Physiology of Movements, Bogomoletz Institute of Physiology, Kiev, Ukraine,Department of Cellular Membranology, Bogomoletz Institute of Physiology, Kiev, Ukraine
| | - Elena Isaeva
- Department of Cellular Membranology, Bogomoletz Institute of Physiology, Kiev, Ukraine,Department of Neurology, Neuroscience Center at Dartmouth, Dartmouth Medical School, Lebanon, New Hampshire, USA
| | - Alina V. Savotchenko
- Department of Cellular Membranology, Bogomoletz Institute of Physiology, Kiev, Ukraine
| | - Galina V. Dovgalets
- Department of Physiology of Movements, Bogomoletz Institute of Physiology, Kiev, Ukraine
| | - Juan G. Ochoa
- Department of Neurology, University of South Alabama College of Medicine, Mobile, Alabama, USA
| | - Gregory L. Holmes
- Department of Neurology, Neuroscience Center at Dartmouth, Dartmouth Medical School, Lebanon, New Hampshire, USA
| | - Dmytro Isaev
- Department of Neurology, Neuroscience Center at Dartmouth, Dartmouth Medical School, Lebanon, New Hampshire, USA,State Key Laboratory for Molecular and Cellular Biology, Kiev, Ukraine
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16
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Affiliation(s)
- Nikita Gamper
- Institute ofMembrane and Systems Biology, Faculty of Biological Science, University of Leeds, Leeds LS2 9JT, UK.
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17
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Brain volume regulation: osmolytes and aquaporin perspectives. Neuroscience 2010; 168:871-84. [DOI: 10.1016/j.neuroscience.2009.11.074] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2009] [Revised: 11/13/2009] [Accepted: 11/25/2009] [Indexed: 02/08/2023]
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