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Linne ML. Computational modeling of neuron-glia signaling interactions to unravel cellular and neural circuit functioning. Curr Opin Neurobiol 2024; 85:102838. [PMID: 38310660 DOI: 10.1016/j.conb.2023.102838] [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: 03/10/2023] [Revised: 12/22/2023] [Accepted: 12/29/2023] [Indexed: 02/06/2024]
Abstract
Glial cells have been shown to be vital for various brain functions, including homeostasis, information processing, and cognition. Over the past 30 years, various signaling interactions between neuronal and glial cells have been shown to underlie these functions. This review summarizes the interactions, particularly between neurons and astrocytes, which are types of glial cells. Some of the interactions remain controversial in part due to the nature of experimental methods and preparations used. Based on the accumulated data, computational models of the neuron-astrocyte interactions have been developed to explain the complex functions of astrocytes in neural circuits and to test conflicting hypotheses. This review presents the most significant recent models, modeling methods and simulation tools for neuron-astrocyte interactions. In the future, we will especially need more experimental research on awake animals in vivo and new computational models of neuron-glia interactions to advance our understanding of cellular dynamics and the functioning of neural circuits in different brain regions.
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Affiliation(s)
- Marja-Leena Linne
- Tampere University, Faculty of Medicine and Health Technology, Tampere, Finland.
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2
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Manninen T, Aćimović J, Linne ML. Analysis of Network Models with Neuron-Astrocyte Interactions. Neuroinformatics 2023; 21:375-406. [PMID: 36959372 PMCID: PMC10085960 DOI: 10.1007/s12021-023-09622-w] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/01/2023] [Indexed: 03/25/2023]
Abstract
Neural networks, composed of many neurons and governed by complex interactions between them, are a widely accepted formalism for modeling and exploring global dynamics and emergent properties in brain systems. In the past decades, experimental evidence of computationally relevant neuron-astrocyte interactions, as well as the astrocytic modulation of global neural dynamics, have accumulated. These findings motivated advances in computational glioscience and inspired several models integrating mechanisms of neuron-astrocyte interactions into the standard neural network formalism. These models were developed to study, for example, synchronization, information transfer, synaptic plasticity, and hyperexcitability, as well as classification tasks and hardware implementations. We here focus on network models of at least two neurons interacting bidirectionally with at least two astrocytes that include explicitly modeled astrocytic calcium dynamics. In this study, we analyze the evolution of these models and the biophysical, biochemical, cellular, and network mechanisms used to construct them. Based on our analysis, we propose how to systematically describe and categorize interaction schemes between cells in neuron-astrocyte networks. We additionally study the models in view of the existing experimental data and present future perspectives. Our analysis is an important first step towards understanding astrocytic contribution to brain functions. However, more advances are needed to collect comprehensive data about astrocyte morphology and physiology in vivo and to better integrate them in data-driven computational models. Broadening the discussion about theoretical approaches and expanding the computational tools is necessary to better understand astrocytes' roles in brain functions.
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Affiliation(s)
- Tiina Manninen
- Faculty of Medicine and Health Technology, Tampere University, Korkeakoulunkatu 3, FI-33720, Tampere, Finland.
| | - Jugoslava Aćimović
- Faculty of Medicine and Health Technology, Tampere University, Korkeakoulunkatu 3, FI-33720, Tampere, Finland
| | - Marja-Leena Linne
- Faculty of Medicine and Health Technology, Tampere University, Korkeakoulunkatu 3, FI-33720, Tampere, Finland.
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3
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Jiang YH, Li T, Liu Y, Liu X, Jia S, Hou C, Chen G, Wang H, Ling S, Gao Q, Wang XR, Wang YF. Contribution of inwardly rectifying K + channel 4.1 of supraoptic astrocytes to the regulation of vasopressin neuronal activity by hypotonicity. Glia 2023; 71:704-719. [PMID: 36408843 DOI: 10.1002/glia.24306] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2022] [Revised: 11/06/2022] [Accepted: 11/12/2022] [Indexed: 11/22/2022]
Abstract
Astrocytic morphological plasticity and its modulation of adjacent neuronal activity are largely determined by astrocytic volume regulation, in which glial fibrillary acidic protein (GFAP), aquaporin 4 (AQP4), and potassium channels including inwardly rectifying K+ channel 4.1 (Kir4.1) are essential. However, associations of astrocyte-dominant Kir4.1 with other molecules in astrocytic volume regulation and the subsequent influence on neuronal activity remain unclear. Here, we report our study on these issues using primary cultures of rat pups' hypothalamic astrocytes and male adult rat brain slices. In astrocyte culture, hyposmotic challenge (HOC) significantly decreased GFAP monomer expression and astrocytic volume at 1.5 min and increased Kir4.1 expression and inwardly rectifying currents (IRCs) at 10 min. BaCl2 (100 μmol/l) suppressed the HOC-increased IRCs, which was simulated by VU0134992 (2 μmol/l), a Kir4.1 blocker. Preincubation of the astrocyte culture with TGN-020 (10 μmol/l, a specific AQP4 blocker) made the HOC-increased Kir4.1 currents insignificant. In hypothalamic brain slices, HOC initially decreased and then increased the firing rate of vasopressin (VP) neurons in the supraoptic nucleus. In the presence of BaCl2 or VU0134992, HOC-elicited rebound increase in VP neuronal activity was blocked. GFAP was molecularly associated with Kir4.1, which was increased by HOC at 20 min; this increase was blocked by BaCl2 . These results suggest that HOC-evoked astrocytic retraction or decrease in the volume and length of its processes is associated with increased Kir4.1 activity. Kir4.1 involvement in HOC-elicited astrocytic retraction is associated with AQP4 activity and GFAP plasticity, which together determines the rebound excitation of VP neurons.
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Affiliation(s)
- Yun-Hao Jiang
- Department of Physiology, School of Basic Medical Sciences, Harbin Medical University, Harbin, China
| | - Tong Li
- Department of Physiology, School of Basic Medical Sciences, Harbin Medical University, Harbin, China.,Neuroelectrophysiology Laboratory, School of Mental Health, Qiqihar Medical University, Qiqihar, China
| | - Yang Liu
- Department of Physiology, School of Basic Medical Sciences, Harbin Medical University, Harbin, China
| | - Xiaoyu Liu
- Department of Physiology, School of Basic Medical Sciences, Harbin Medical University, Harbin, China
| | - Shuwei Jia
- Department of Physiology, School of Basic Medical Sciences, Harbin Medical University, Harbin, China
| | - Chunmei Hou
- Department of Physiology, School of Basic Medical Sciences, Harbin Medical University, Harbin, China
| | - Guichuan Chen
- Department of Physiology, School of Basic Medical Sciences, Harbin Medical University, Harbin, China
| | - Hongyang Wang
- Department of Physiology, School of Basic Medical Sciences, Harbin Medical University, Harbin, China
| | - Shuo Ling
- Department of Physiology, School of Basic Medical Sciences, Harbin Medical University, Harbin, China
| | - Qiang Gao
- Department of Physiology, School of Basic Medical Sciences, Harbin Medical University, Harbin, China
| | - Xiao-Ran Wang
- Department of Physiology, School of Basic Medical Sciences, Harbin Medical University, Harbin, China
| | - Yu-Feng Wang
- Department of Physiology, School of Basic Medical Sciences, Harbin Medical University, Harbin, China
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4
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Zhao J, Sun J, Zheng Y, Zheng Y, Shao Y, Li Y, Fei F, Xu C, Liu X, Wang S, Ruan Y, Liu J, Duan S, Chen Z, Wang Y. Activated astrocytes attenuate neocortical seizures in rodent models through driving Na +-K +-ATPase. Nat Commun 2022; 13:7136. [PMID: 36414629 PMCID: PMC9681834 DOI: 10.1038/s41467-022-34662-2] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2022] [Accepted: 11/01/2022] [Indexed: 11/24/2022] Open
Abstract
Epileptic seizures are widely regarded to occur as a result of the excitation-inhibition imbalance from a neuro-centric view. Although astrocyte-neuron interactions are increasingly recognized in seizure, elementary questions about the causal role of astrocytes in seizure remain unanswered. Here we show that optogenetic activation of channelrhodopsin-2-expressing astrocytes effectively attenuates neocortical seizures in rodent models. This anti-seizure effect is independent from classical calcium signaling, and instead related to astrocytic Na+-K+-ATPase-mediated buffering K+, which activity-dependently inhibits firing in highly active pyramidal neurons during seizure. Compared with inhibition of pyramidal neurons, astrocyte stimulation exhibits anti-seizure effects with several advantages, including a wider therapeutic window, large-space efficacy, and minimal side effects. Finally, optogenetic-driven astrocytic Na+-K+-ATPase shows promising therapeutic effects in a chronic focal cortical dysplasia epilepsy model. Together, we uncover a promising anti-seizure strategy with optogenetic control of astrocytic Na+-K+-ATPase activity, providing alternative ideas and a potential target for the treatment of intractable epilepsy.
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Affiliation(s)
- Junli Zhao
- Key Laboratory of Neuropharmacology and Translational Medicine of Zhejiang Province, School of Pharmaceutical Sciences, Zhejiang Chinese Medical University, Hangzhou, China
- Institute of Pharmacology & Toxicology, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, China
| | - Jinyi Sun
- Institute of Pharmacology & Toxicology, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, China
| | - Yang Zheng
- Key Laboratory of Neuropharmacology and Translational Medicine of Zhejiang Province, School of Pharmaceutical Sciences, Zhejiang Chinese Medical University, Hangzhou, China
| | - Yanrong Zheng
- Key Laboratory of Neuropharmacology and Translational Medicine of Zhejiang Province, School of Pharmaceutical Sciences, Zhejiang Chinese Medical University, Hangzhou, China
| | - Yuying Shao
- Institute of Pharmacology & Toxicology, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, China
| | - Yulan Li
- Key Laboratory of Neuropharmacology and Translational Medicine of Zhejiang Province, School of Pharmaceutical Sciences, Zhejiang Chinese Medical University, Hangzhou, China
| | - Fan Fei
- Key Laboratory of Neuropharmacology and Translational Medicine of Zhejiang Province, School of Pharmaceutical Sciences, Zhejiang Chinese Medical University, Hangzhou, China
- Institute of Pharmacology & Toxicology, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, China
| | - Cenglin Xu
- Key Laboratory of Neuropharmacology and Translational Medicine of Zhejiang Province, School of Pharmaceutical Sciences, Zhejiang Chinese Medical University, Hangzhou, China
| | - Xiuxiu Liu
- Institute of Pharmacology & Toxicology, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, China
| | - Shuang Wang
- Epilepsy Center, Department of Neurology, Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China
| | - Yeping Ruan
- Key Laboratory of Neuropharmacology and Translational Medicine of Zhejiang Province, School of Pharmaceutical Sciences, Zhejiang Chinese Medical University, Hangzhou, China
| | - Jinggen Liu
- Key Laboratory of Neuropharmacology and Translational Medicine of Zhejiang Province, School of Pharmaceutical Sciences, Zhejiang Chinese Medical University, Hangzhou, China
| | - Shumin Duan
- Key Laboratory of Medical Neurobiology of the Ministry of Health of China, School of Brain Science and Brain Medicine, Zhejiang University, Hangzhou, China
| | - Zhong Chen
- Key Laboratory of Neuropharmacology and Translational Medicine of Zhejiang Province, School of Pharmaceutical Sciences, Zhejiang Chinese Medical University, Hangzhou, China.
- Institute of Pharmacology & Toxicology, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, China.
- Epilepsy Center, Department of Neurology, Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China.
| | - Yi Wang
- Key Laboratory of Neuropharmacology and Translational Medicine of Zhejiang Province, School of Pharmaceutical Sciences, Zhejiang Chinese Medical University, Hangzhou, China.
- Institute of Pharmacology & Toxicology, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, China.
- Epilepsy Center, Department of Neurology, Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China.
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5
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Yuan Z, Feng P, Fan Y, Yu Y, Wu Y. Astrocytic modulation on neuronal electric mode selection induced by magnetic field effect. Cogn Neurodyn 2022; 16:183-194. [PMID: 35126777 PMCID: PMC8807809 DOI: 10.1007/s11571-021-09709-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2021] [Revised: 06/11/2021] [Accepted: 07/20/2021] [Indexed: 02/03/2023] Open
Abstract
Astrocytes as well as electromagnetic induction have been primarily considered as main factors in regulating neuronal firing patterns in the recent decade. In this work, an improved neuron-astrocyte model in consideration of the modulation of astrocytes and the electromagnetic induction is employed to explore the extend to which both of the factors affect the firing modes of the neurons. The "alternation mode", defined as the alternative of neural normal spiking mode with the high-frequency bursting-like mode, clearly shows the functions of astrocytes on neurons. Moreover, the firing pattern of the neuron becomes more abnormal when astrocytes are hyper-excitable, the reason why the abnormal coupling of the astrocyte leads to the "alternation mode" of the neuron have been studied. In addition, the effect of electromagnetic induction manifests nonlinear characteristic towards neurons, complex firing modes of neurons are observed in the weaker field and a switching mode consists with quiescent and spiking mode appears when there is a higher stronger field. This approved model can reveal the normal or abnormal electric activities of neuron considered electromagnetic induction induced by the degree of excitability of the astrocyte. These results can provide potential understanding about the effects of astrocyte on neuronal activity when the coupling of electromagnetic field is considered.
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Affiliation(s)
- Zhixuan Yuan
- State Key Laboratory for Strength and Vibration of Mechanical Structures, Shaanxi Engineering Laboratory for Vibration Control of Aerospace Structures, School of Aerospace Engineering, Xian Jiaotong University, Xian, 710049 China
| | - Peihua Feng
- State Key Laboratory for Strength and Vibration of Mechanical Structures, Shaanxi Engineering Laboratory for Vibration Control of Aerospace Structures, School of Aerospace Engineering, Xian Jiaotong University, Xian, 710049 China
| | - Yongchen Fan
- State Key Laboratory for Strength and Vibration of Mechanical Structures, Shaanxi Engineering Laboratory for Vibration Control of Aerospace Structures, School of Aerospace Engineering, Xian Jiaotong University, Xian, 710049 China
| | - Yangyang Yu
- State Key Laboratory for Strength and Vibration of Mechanical Structures, Shaanxi Engineering Laboratory for Vibration Control of Aerospace Structures, School of Aerospace Engineering, Xian Jiaotong University, Xian, 710049 China
| | - Ying Wu
- State Key Laboratory for Strength and Vibration of Mechanical Structures, Shaanxi Engineering Laboratory for Vibration Control of Aerospace Structures, School of Aerospace Engineering, Xian Jiaotong University, Xian, 710049 China
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6
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Volnova A, Tsytsarev V, Ganina O, Vélez-Crespo GE, Alves JM, Ignashchenkova A, Inyushin M. The Anti-Epileptic Effects of Carbenoxolone In Vitro and In Vivo. Int J Mol Sci 2022; 23:ijms23020663. [PMID: 35054848 PMCID: PMC8775396 DOI: 10.3390/ijms23020663] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2021] [Revised: 01/04/2022] [Accepted: 01/06/2022] [Indexed: 12/14/2022] Open
Abstract
Gap junctions (GJs) are intercellular junctions that allow the direct transfer of ions and small molecules between neighboring cells, and GJs between astrocytes play an important role in the development of various pathologies of the brain, including regulation of the pathological neuronal synchronization underlying epileptic seizures. Recently, we found that a pathological change is observed in astrocytes during the ictal and interictal phases of 4-aminopyridin (4-AP)-elicited epileptic activity in vitro, which was correlated with neuronal synchronization and extracellular epileptic electrical activity. This finding raises the question: Does this signal depend on GJs between astrocytes? In this study we investigated the effect of the GJ blocker, carbenoxolone (CBX), on epileptic activity in vitro and in vivo. Based on the results obtained, we came to the conclusion that the astrocytic syncytium formed by GJ-associated astrocytes, which is responsible for the regulation of potassium, affects the formation of epileptic activity in astrocytes in vitro and epileptic seizure onset. This effect is probably an important, but not the only, mechanism by which CBX suppresses epileptic activity. It is likely that the mechanisms of selective inhibition of GJs between astrocytes will show important translational benefits in anti-epileptic therapies.
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Affiliation(s)
- Anna Volnova
- Biological Faculty, Saint Petersburg State University, 199034 St. Petersburg, Russia
- Institute of Translational Biomedicine, Saint Petersburg State University, 199034 St. Petersburg, Russia;
- Correspondence: (A.V.); (M.I.)
| | | | - Olga Ganina
- Nevsky Center of Scientific Collaboration, 192119 St. Petersburg, Russia;
| | - Grace E. Vélez-Crespo
- School of Medicine, Universidad Central del Caribe, Bayamon, PR 00956, USA; (G.E.V.-C.); (J.M.A.)
| | - Janaina M. Alves
- School of Medicine, Universidad Central del Caribe, Bayamon, PR 00956, USA; (G.E.V.-C.); (J.M.A.)
| | - Alla Ignashchenkova
- Institute of Translational Biomedicine, Saint Petersburg State University, 199034 St. Petersburg, Russia;
- Nevsky Center of Scientific Collaboration, 192119 St. Petersburg, Russia;
| | - Mikhail Inyushin
- School of Medicine, Universidad Central del Caribe, Bayamon, PR 00956, USA; (G.E.V.-C.); (J.M.A.)
- Correspondence: (A.V.); (M.I.)
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7
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Akyuz E, Koklu B, Uner A, Angelopoulou E, Paudel YN. Envisioning the role of inwardly rectifying potassium (Kir) channel in epilepsy. J Neurosci Res 2021; 100:413-443. [PMID: 34713909 DOI: 10.1002/jnr.24985] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2021] [Revised: 09/23/2021] [Accepted: 10/01/2021] [Indexed: 01/29/2023]
Abstract
Epilepsy is a devastating neurological disorder characterized by recurrent seizures attributed to the disruption of the dynamic excitatory and inhibitory balance in the brain. Epilepsy has emerged as a global health concern affecting about 70 million people worldwide. Despite recent advances in pre-clinical and clinical research, its etiopathogenesis remains obscure, and there are still no treatment strategies modifying disease progression. Although the precise molecular mechanisms underlying epileptogenesis have not been clarified yet, the role of ion channels as regulators of cellular excitability has increasingly gained attention. In this regard, emerging evidence highlights the potential implication of inwardly rectifying potassium (Kir) channels in epileptogenesis. Kir channels consist of seven different subfamilies (Kir1-Kir7), and they are highly expressed in both neuronal and glial cells in the central nervous system. These channels control the cell volume and excitability. In this review, we discuss preclinical and clinical evidence on the role of the several subfamilies of Kir channels in epileptogenesis, aiming to shed more light on the pathogenesis of this disorder and pave the way for future novel therapeutic approaches.
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Affiliation(s)
- Enes Akyuz
- Faculty of International Medicine, Department of Biophysics, University of Health Sciences, Istanbul, Turkey
| | - Betul Koklu
- Faculty of Medicine, Namık Kemal University, Tekirdağ, Turkey
| | - Arda Uner
- Faculty of Medicine, Yozgat Bozok University, Yozgat, Turkey
| | - Efthalia Angelopoulou
- Department of Biological Chemistry, Medical School, National and Kapodistrian University of Athens, Athens, Greece
| | - Yam Nath Paudel
- Neuropharmacology Research Strength, Jeffrey Cheah School of Medicine and Health Sciences, Monash University Malaysia, Bandar Sunway, Malaysia
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8
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Ohno Y, Kunisawa N, Shimizu S. Emerging Roles of Astrocyte Kir4.1 Channels in the Pathogenesis and Treatment of Brain Diseases. Int J Mol Sci 2021; 22:ijms221910236. [PMID: 34638578 PMCID: PMC8508600 DOI: 10.3390/ijms221910236] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2021] [Revised: 09/14/2021] [Accepted: 09/16/2021] [Indexed: 12/15/2022] Open
Abstract
Inwardly rectifying Kir4.1 channels in astrocytes mediate spatial potassium (K+) buffering, a clearance mechanism for excessive extracellular K+, in tripartite synapses. In addition to K+ homeostasis, astrocytic Kir4.1 channels also play an essential role in regulating extracellular glutamate levels via coupling with glutamate transporters. Moreover, Kir4.1 channels act as novel modulators of the expression of brain-derived neurotrophic factor (BDNF) in astrocytes. Specifically, inhibition of astrocytic Kir4.1 channels elevates extracellular K+ and glutamate levels at synapses and facilitates BDNF expression in astrocytes. These changes elevate neural excitability, which may facilitate synaptic plasticity and connectivity. In this article, we summarize the functions and pharmacological features of Kir4.1 channels in astrocytes and highlight the importance of these channels in the treatment of brain diseases. Although further validation in animal models and human patients is required, astrocytic Kir4.1 channel could potentially serve as a novel therapeutic target for the treatment of depressive disorders and epilepsy.
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9
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A dynamics model of neuron-astrocyte network accounting for febrile seizures. Cogn Neurodyn 2021; 16:411-423. [PMID: 35401866 PMCID: PMC8934847 DOI: 10.1007/s11571-021-09706-w] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Revised: 06/03/2021] [Accepted: 07/17/2021] [Indexed: 10/20/2022] Open
Abstract
Febrile seizure (FS) is a full-body convulsion caused by a high body temperature that affect young kids, however, how these most common of human seizures are generated by fever has not been known. One common observation is that cortical neurons become overexcited with abnormal running of sodium and potassium ions cross membrane in raised body temperature condition, Considering that astrocyte Kir4.1 channel play a critical role in maintaining extracellular homeostasis of ionic concentrations and electrochemical potentials of neurons by fast depletion of extracellular potassium ions, we examined here the potential role of temperature-dependent Kir4.1 channel in astrocytes in causing FS. We first built up a temperature-dependent computational model of the Kir4.1 channel in astrocytes and validated with experiments. We have then built up a neuron-astrocyte network and examine the role of the Kir4.1 channel in modulating neuronal firing dynamics as temperature increase. The numerical experiment demonstrated that the Kir4.1 channel function optimally in the body temperature around 37 °C in cleaning 'excessive' extracellular potassium ions during neuronal firing process, however, higher temperature deteriorates its cleaning function, while lower temperature slows down its cleaning efficiency. With the increase of temperature, neurons go through different stages of spiking dynamics from spontaneous slow oscillations, to tonic spiking, fast bursting oscillations, and eventually epileptic bursting. Thus, our study may provide a potential new mechanism that febrile seizures may be happened due to temperature-dependent functional disorders of Kir4.1 channel in astrocytes. Supplementary Information The online version contains supplementary material available at 10.1007/s11571-021-09706-w.
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10
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Exacerbation of Epilepsy by Astrocyte Alkalization and Gap Junction Uncoupling. J Neurosci 2021; 41:2106-2118. [PMID: 33478985 DOI: 10.1523/jneurosci.2365-20.2020] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2020] [Revised: 11/02/2020] [Accepted: 11/25/2020] [Indexed: 12/12/2022] Open
Abstract
Seizures invite seizures. At the initial stage of epilepsy, seizures intensify with each episode; however, the mechanisms underlying this exacerbation remain to be solved. Astrocytes have a strong control over neuronal excitability and the mode of information processing. This control is accomplished by adjusting the levels of various ions in the extracellular space. The network of astrocytes connected via gap junctions allows a wider or more confined distribution of these ions depending on the open probability of the gap junctions. K+ clearance relies on the K+ uptake by astrocytes and the subsequent diffusion of K+ through the astrocyte network. When astrocytes become uncoupled, K+ clearance becomes hindered. Accumulation of extracellular K+ leads to hyperexcitability of neurons. Here, using acute hippocampal slices from mice, we uncovered that brief periods of epileptiform activity result in gap junction uncoupling. In slices that experienced short-term epileptiform activity, extracellular K+ transients in response to glutamate became prolonged. Na+ imaging with a fluorescent indicator indicated that intercellular diffusion of small cations in the astrocytic syncytium via gap junctions became rapidly restricted after epileptiform activity. Using a transgenic mouse with astrocyte-specific expression of a pH sensor (Lck-E2GFP), we confirmed that astrocytes react to epileptiform activity with intracellular alkalization. Application of Na+/HCO3 - cotransporter blocker led to the suppression of intracellular alkalization of astrocytes and to the prevention of astrocyte uncoupling and hyperactivity intensification both in vitro and in vivo Therefore, the inhibition of astrocyte alkalization could become a promising therapeutic strategy for countering epilepsy development.SIGNIFICANCE STATEMENT We aimed to understand the mechanisms underlying the plastic change of forebrain circuits associated with the intensification of epilepsy. Here, we demonstrate that first-time exposure to only brief periods of epileptiform activity results in acute disturbance of the intercellular astrocyte network formed by gap junctions in hippocampal tissue slices from mice. Moreover, rapid clearance of K+ from the extracellular space was impaired. Epileptiform activity activated inward Na+/HCO3 - cotransport in astrocytes by cell depolarization, resulting in their alkalization. Our data suggest that alkaline pH shifts in astrocytes lead to gap junction uncoupling, hampering K+ clearance, and thereby to exacerbation of epilepsy. Pharmacological intervention could become a promising new strategy to dampen neuronal hyperexcitability and epileptogenesis.
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11
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Yang TT, Qian F, Liu L, Peng XC, Huang JR, Ren BX, Tang FR. Astroglial connexins in epileptogenesis. Seizure 2020; 84:122-128. [PMID: 33348235 DOI: 10.1016/j.seizure.2020.11.022] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2020] [Revised: 11/27/2020] [Accepted: 11/29/2020] [Indexed: 12/27/2022] Open
Abstract
The astroglial network connected through gap junctions assembling from connexins physiologically balances the concentrations of ions and neurotransmitters around neurons. Astrocytic dysfunction has been associated with many neurological disorders including epilepsy. Dissociated gap junctions result in the increased activity of connexin hemichannels which triggers brain pathophysiological changes. Previous studies in patients and animal models of epilepsy indicate that the reduced gap junction coupling from assembled connexin hemichannels in the astrocytes may play an important role in epileptogenesis. This abnormal cell-to-cell communication is now emerging as an important feature of brain pathologies and being considered as a novel therapeutic target for controlling epileptogenesis. In particular, candidate drugs with ability of inhibition of connexin hemichannel activity and enhancement of gap junction formation in astrocytes should be explored to prevent epileptogenesis and control epilepsy.
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Affiliation(s)
- Ting-Ting Yang
- School of Basic Medicine, Health Science Center, Yangtze University, Jingzhou, Hubei Province, 434023, China
| | - Feng Qian
- School of Basic Medicine, Health Science Center, Yangtze University, Jingzhou, Hubei Province, 434023, China.
| | - Lian Liu
- School of Basic Medicine, Health Science Center, Yangtze University, Jingzhou, Hubei Province, 434023, China
| | - Xiao-Chun Peng
- School of Basic Medicine, Health Science Center, Yangtze University, Jingzhou, Hubei Province, 434023, China
| | - Jiang-Rong Huang
- School of Basic Medicine, Health Science Center, Yangtze University, Jingzhou, Hubei Province, 434023, China
| | - Bo-Xu Ren
- School of Basic Medicine, Health Science Center, Yangtze University, Jingzhou, Hubei Province, 434023, China
| | - Feng-Ru Tang
- Radiobiology Research Laboratory, Singapore Nuclear Research and Safety Initiative, National University of Singapore, Singapore.
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12
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Méndez-González MP, Rivera-Aponte DE, Benedikt J, Maldonado-Martínez G, Tejeda-Bayron F, Skatchkov SN, Eaton MJ. Downregulation of Astrocytic Kir4.1 Potassium Channels Is Associated with Hippocampal Neuronal Hyperexcitability in Type 2 Diabetic Mice. Brain Sci 2020; 10:brainsci10020072. [PMID: 32019062 PMCID: PMC7071513 DOI: 10.3390/brainsci10020072] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2020] [Accepted: 01/22/2020] [Indexed: 11/16/2022] Open
Abstract
Epilepsy, characterized by recurrent seizures, affects 1% of the general population. Interestingly, 25% of diabetics develop seizures with a yet unknown mechanism. Hyperglycemia downregulates inwardly rectifying potassium channel 4.1 (Kir4.1) in cultured astrocytes. Therefore, the present study aims to determine if downregulation of functional astrocytic Kir4.1 channels occurs in brains of type 2 diabetic mice and could influence hippocampal neuronal hyperexcitability. Using whole-cell patch clamp recording in hippocampal brain slices from male mice, we determined the electrophysiological properties of stratum radiatum astrocytes and CA1 pyramidal neurons. In diabetic mice, astrocytic Kir4.1 channels were functionally downregulated as evidenced by multiple characteristics including depolarized membrane potential, reduced barium-sensitive Kir currents and impaired potassium uptake capabilities of hippocampal astrocytes. Furthermore, CA1 pyramidal neurons from diabetic mice displayed increased spontaneous activity: action potential frequency was ≈9 times higher in diabetic compared with non-diabetic mice and small EPSC event frequency was significantly higher in CA1 pyramidal cells of diabetics compared to non-diabetics. These differences were apparent in control conditions and largely pronounced in response to the pro-convulsant 4-aminopyridine. Our data suggest that astrocytic dysfunction due to downregulation of Kir4.1 channels may increase seizure susceptibility by impairing astrocytic ability to maintain proper extracellular homeostasis.
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Affiliation(s)
- Miguel P. Méndez-González
- Department of Biochemistry, Universidad Central del Caribe, Bayamón, PR 00960-6032, USA; (M.P.M.-G.); (F.T.-B.)
- Department of Sciences and Technology, Antilles Adventist University, Mayaguez, PR 00680, USA
- Department of Natural Sciences, University of Puerto Rico, Aguadilla, PR 00604-6150, USA
| | - David E. Rivera-Aponte
- Department of Biochemistry, Universidad Central del Caribe, Bayamón, PR 00960-6032, USA; (M.P.M.-G.); (F.T.-B.)
| | - Jan Benedikt
- Departments of Physiology and Biochemistry Universidad Central del Caribe, Bayamón, PR 00960-6032, USA;
| | | | - Flavia Tejeda-Bayron
- Department of Biochemistry, Universidad Central del Caribe, Bayamón, PR 00960-6032, USA; (M.P.M.-G.); (F.T.-B.)
| | - Serguei N. Skatchkov
- Department of Biochemistry, Universidad Central del Caribe, Bayamón, PR 00960-6032, USA; (M.P.M.-G.); (F.T.-B.)
- Departments of Physiology and Biochemistry Universidad Central del Caribe, Bayamón, PR 00960-6032, USA;
- Correspondence: (S.N.S.); (M.J.E.); Tel.: +787-798-3001 (ext. 2057) (S.N.S.); +787-798-3001 (ext. 2034) (M.J.E.); Fax: +787-786-6285 (M.J.E.)
| | - Misty J. Eaton
- Department of Biochemistry, Universidad Central del Caribe, Bayamón, PR 00960-6032, USA; (M.P.M.-G.); (F.T.-B.)
- Correspondence: (S.N.S.); (M.J.E.); Tel.: +787-798-3001 (ext. 2057) (S.N.S.); +787-798-3001 (ext. 2034) (M.J.E.); Fax: +787-786-6285 (M.J.E.)
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Shu Y, Zhu C, Zeng M, Zhan Q, Hu Z, Wu X. The protective effect of carbenoxolone on gap junction damage in the hippocampal CA1 area of a temporal lobe epilepsy rat model. ANNALS OF TRANSLATIONAL MEDICINE 2019; 7:624. [PMID: 31930025 DOI: 10.21037/atm.2019.11.04] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Background Astrocytes are one of the most important types of neural cells in the central nervous system (CNS). Dysfunctional gap junction (GJ) communication could play an underlying role in epileptogenesis. Carbenoxolone (CBX) is a conventional chemical GJ blocker, and its target is connexin 43 (Cx43). Previous studies have shown that CBX can inhibit status epilepticus (SE) and spontaneous epileptic seizures (SESs). However, there is little information about the direct interaction between CBX and Cxs in temporal lobe epilepsy (TLE). Methods The behavior of epileptic rats was observed. Moreover, micromorphological changes in the hippocampal cornu ammonis 1 (CA1) area of epileptic rats following CBX injection were determined through transmission electron microscopy (TEM). To illustrate the possible mechanism of these changes, the Western blot method was used. Results After the injection of CBX, the seizure frequency, seizure duration, latency period to the first instance of SES, SESs behavioral score according to a scoring system developed by Velíšková and microstructures in the CA1 area were shown to be improved 60 days after SE by TEM. Furthermore, the dynamic expression patterns of Cx43 and Cx43 phosphorylated at Ser368 continuously declined after the injection of CBX until 60 days after SE. Conclusions CBX may contribute to the improvement of GJ dysfunction during epileptogenesis in the hippocampal CA1 area in a TLE rat model.
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Affiliation(s)
- Yi Shu
- Department of Neurology, The Second Xiangya Hospital, Central South University, Changsha 410011, China
| | - Can Zhu
- Department of Neurology, The Second Xiangya Hospital, Central South University, Changsha 410011, China
| | - Min Zeng
- Department of Neurology, The Second Xiangya Hospital, Central South University, Changsha 410011, China
| | - Qiong Zhan
- Department of Neurology, The Second Xiangya Hospital, Central South University, Changsha 410011, China
| | - Zhiping Hu
- Department of Neurology, The Second Xiangya Hospital, Central South University, Changsha 410011, China
| | - Xiaomei Wu
- Department of Neurology, The Second Xiangya Hospital, Central South University, Changsha 410011, China
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Xie Z, Yang Q, Song D, Quan Z, Qing H. Optogenetic manipulation of astrocytes from synapses to neuronal networks: A potential therapeutic strategy for neurodegenerative diseases. Glia 2019; 68:215-226. [PMID: 31400164 DOI: 10.1002/glia.23693] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2019] [Revised: 07/18/2019] [Accepted: 07/22/2019] [Indexed: 02/06/2023]
Abstract
Astrocytes are the most widespread and heterogeneous glial cells in the central nervous system and key regulators for brain development. They are capable of receiving neurotransmitters produced by synaptic activities and regulating synaptic functions by releasing gliotransmitters as part of the tripartite synapse. In addition to communicating with neurons at synaptic levels, astrocytes can integrate into inhibitory neural networks to interact with neurons in neuronal circuits. Astrocytes are closely related to the pathogenesis and pathological processes of neurodegenerative diseases (NDs). Recently, optogenetics has now been applied to reveal the function of astrocytes in physiology and pathology. Herein, we discuss the possibility whether optogenetics could be used to control the release of gliotransmitters and regulate astrocytic membrane channels. Thus, the capability of modulating the bidirectional interactions between astrocytes and neurons in both synaptic and neuronal networks via optogenetics is evaluated. Furthermore, we discuss that manipulating astrocytes via optogenetics might be an effective way to investigate the potential therapeutic strategy for NDs.
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Affiliation(s)
- Zhen Xie
- Key Laboratory of Molecular Medicine and Biotherapy in the Ministry of Industry and Information Technology, Department of Biology, School of Life Sciences, Beijing Institute of Technology, Beijing, China
| | - Qinghu Yang
- Key Laboratory of Molecular Medicine and Biotherapy in the Ministry of Industry and Information Technology, Department of Biology, School of Life Sciences, Beijing Institute of Technology, Beijing, China.,College of Life Sciences & Research Center for Resource Peptide Drugs, Shaanxi Engineering & Technological Research Center for Conversation & Utilization of Regional Biological Resources, Yanan University, Yanan, China
| | - Da Song
- Key Laboratory of Molecular Medicine and Biotherapy in the Ministry of Industry and Information Technology, Department of Biology, School of Life Sciences, Beijing Institute of Technology, Beijing, China
| | - Zhenzhen Quan
- Key Laboratory of Molecular Medicine and Biotherapy in the Ministry of Industry and Information Technology, Department of Biology, School of Life Sciences, Beijing Institute of Technology, Beijing, China
| | - Hong Qing
- Key Laboratory of Molecular Medicine and Biotherapy in the Ministry of Industry and Information Technology, Department of Biology, School of Life Sciences, Beijing Institute of Technology, Beijing, China
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Li Q, Li QQ, Jia JN, Liu ZQ, Zhou HH, Mao XY. Targeting gap junction in epilepsy: Perspectives and challenges. Biomed Pharmacother 2018; 109:57-65. [PMID: 30396092 DOI: 10.1016/j.biopha.2018.10.068] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2018] [Revised: 10/08/2018] [Accepted: 10/12/2018] [Indexed: 12/21/2022] Open
Abstract
Gap junctions (GJs) are multiple cellular intercellular connections that allow ions to pass directly into the cytoplasm of neighboring cells. Electrical coupling mediated by GJs plays a role in the generation of highly synchronous electrical activity. Accumulative investigations show that GJs in the brain are involved in the generation, synchronization and maintenance of seizure events. At the same time, GJ blockers exert potent curative potential on epilepsy in vivo or in vitro. This review aims to shed light on the role of GJs in epileptogenesis. Targeting GJs is likely to be served as a novel therapeutic approach on epileptic patients.
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Affiliation(s)
- Qin Li
- Department of Clinical Pharmacology, Xiangya Hospital, Central South University, Changsha 410008, China; Institute of Clinical Pharmacology, Hunan Key Laboratory of Pharmacogenetics, Central South University, Changsha 410078, Hunan, China
| | - Qiu-Qi Li
- Department of Clinical Pharmacology, Xiangya Hospital, Central South University, Changsha 410008, China; Institute of Clinical Pharmacology, Hunan Key Laboratory of Pharmacogenetics, Central South University, Changsha 410078, Hunan, China
| | - Ji-Ning Jia
- Department of Clinical Pharmacology, Xiangya Hospital, Central South University, Changsha 410008, China; Institute of Clinical Pharmacology, Hunan Key Laboratory of Pharmacogenetics, Central South University, Changsha 410078, Hunan, China
| | - Zhao-Qian Liu
- Department of Clinical Pharmacology, Xiangya Hospital, Central South University, Changsha 410008, China; Institute of Clinical Pharmacology, Hunan Key Laboratory of Pharmacogenetics, Central South University, Changsha 410078, Hunan, China
| | - Hong-Hao Zhou
- Department of Clinical Pharmacology, Xiangya Hospital, Central South University, Changsha 410008, China; Institute of Clinical Pharmacology, Hunan Key Laboratory of Pharmacogenetics, Central South University, Changsha 410078, Hunan, China
| | - Xiao-Yuan Mao
- Department of Clinical Pharmacology, Xiangya Hospital, Central South University, Changsha 410008, China; Institute of Clinical Pharmacology, Hunan Key Laboratory of Pharmacogenetics, Central South University, Changsha 410078, Hunan, China.
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Palygin O, Pochynyuk O, Staruschenko A. Distal tubule basolateral potassium channels: cellular and molecular mechanisms of regulation. Curr Opin Nephrol Hypertens 2018; 27:373-378. [PMID: 29894319 PMCID: PMC6217967 DOI: 10.1097/mnh.0000000000000437] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
PURPOSE OF REVIEW Multiple clinical and translational evidence support benefits of high potassium diet; however, there many uncertainties underlying the molecular and cellular mechanisms determining effects of dietary potassium. Kir4.1 and Kir5.1 proteins form a functional heteromer (Kir4.1/Kir5.1), which is the primary inwardly rectifying potassium channel on the basolateral membrane of both distal convoluted tubule (DCT) and the collecting duct principal cells. The purpose of this mini-review is to summarize latest advances in our understanding of the evolution, physiological relevance and mechanisms controlling these channels. RECENT FINDINGS Kir4.1 and Kir5.1 channels play a critical role in determining electrolyte homeostasis in the kidney and blood pressure, respectively. It was reported that Kir4.1/Kir5.1 serves as potassium sensors in the distal nephron responding to variations in dietary intake and hormonal stimuli. Global and kidney specific knockouts of either channel resulted in hypokalemia and severe cardiorenal phenotypes. Furthermore, knock out of Kir5.1 in Dahl salt-sensitive rat background revealed the crucial role of the Kir4.1/Kir5.1 channel in salt-induced hypertension. SUMMARY Here, we focus on reviewing novel experimental evidence of the physiological function, expression and hormonal regulation of renal basolateral inwardly rectifying potassium channels. Further investigation of molecular and cellular mechanisms controlling Kir4.1 and Kir4.1/Kir5.1-mediating pathways and development of specific compounds targeting these channels function is essential for proper control of electrolyte homeostasis and blood pressure.
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Affiliation(s)
- Oleg Palygin
- Department of Physiology, Medical College of Wisconsin, Milwaukee, WI 53226
| | - Oleh Pochynyuk
- Department of Integrative Biology, University of Texas Health Science Center, Houston, TX 77030
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