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Regulation of GABA A Receptors Induced by the Activation of L-Type Voltage-Gated Calcium Channels. MEMBRANES 2021; 11:membranes11070486. [PMID: 34209589 PMCID: PMC8304739 DOI: 10.3390/membranes11070486] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/21/2021] [Revised: 06/23/2021] [Accepted: 06/25/2021] [Indexed: 12/30/2022]
Abstract
GABAA receptors are pentameric ion channels that mediate most synaptic and tonic extrasynaptic inhibitory transmissions in the central nervous system. There are multiple GABAA receptor subtypes constructed from 19 different subunits in mammals that exhibit different regional and subcellular distributions and distinct pharmacological properties. Dysfunctional alterations of GABAA receptors are associated with various neuropsychiatric disorders. Short- and long-term plastic changes in GABAA receptors can be induced by the activation of different intracellular signaling pathways that are triggered, under physiological and pathological conditions, by calcium entering through voltage-gated calcium channels. This review discusses several mechanisms of regulation of GABAA receptor function that result from the activation of L-type voltage gated calcium channels. Calcium influx via these channels activates different signaling cascades that lead to changes in GABAA receptor transcription, phosphorylation, trafficking, and synaptic clustering, thus regulating the inhibitory synaptic strength. These plastic mechanisms regulate the interplay of synaptic excitation and inhibition that is crucial for the normal function of neuronal circuits.
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Duzgun Ergun D, Dursun S, Pastaci Ozsobaci N, Hatırnaz Ng O, Naziroglu M, Ozcelik D. The potential protective roles of zinc, selenium and glutathione on hypoxia-induced TRPM2 channel activation in transfected HEK293 cells. J Recept Signal Transduct Res 2020; 40:521-530. [PMID: 32354246 DOI: 10.1080/10799893.2020.1759093] [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] [Indexed: 10/24/2022]
Abstract
Hypoxia induces cell death through excessive production of reactive oxygen species (ROS) and calcium (Ca2+) influx in cells and TRPM2 cation channel is activated by oxidative stress. Zinc (Zn), selenium (Se), and glutathione (GSH) have antioxidant properties in several cells and hypoxia-induced TRPM2 channel activity, ROS and cell death may be inhibited by the Zn, Se, and GSH treatments. We investigated effects of Zn, Se, and GSH on lipid peroxidation (LPO), cell cytotoxicity and death through inhibition of TRPM2 channel activity in transfected HEK293 cells exposed to hypoxia defined as oxygen deficiency.We induced four groups as normoxia 30 and 60 min evaluated as control groups, hypoxia 30 and 60 min in the HEK293 cells. The cells were separately pre-incubated with extracellular Zn (100 µM), Se (150 nM) and GSH (5 mM). Cytotoxicity was evaluated by lactate dehydrogenase (LDH) release and the LDH and LPO levels were significantly higher in the hypoxia-30 and 60 min-exposed cells according to normoxia 30 and 60 min groups. Furthermore, we found that the LPO and LDH were decreased in the hypoxia-exposed cells after being treated with Zn, Se, and GSH according to the hypoxia groups. Compared to the normoxia groups, the current densities of TRPM2 channel were increased in the hypoxia-exposed cells by the hypoxia applications, while the same values were decreased in the treatment of Zn, Se, and GSH according to hypoxia group. In conclusion, hypoxia-induced TRPM2 channel activity, ROS and cell death were recovered by the Se, Zn and GSH treatments.
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Affiliation(s)
- Dilek Duzgun Ergun
- Department of Biophysics, Faculty of Medicine, Istanbul Aydin University, Istanbul, Turkey.,Department of Biophysics, Cerrahpasa Medical Faculty, Istanbul University-Cerrahpasa, Istanbul, Turkey
| | - Sefik Dursun
- Department of Biophysics, Faculty of Medicine, Uskudar University, Istanbul, Turkey
| | - Nural Pastaci Ozsobaci
- Department of Biophysics, Cerrahpasa Medical Faculty, Istanbul University-Cerrahpasa, Istanbul, Turkey
| | - Ozden Hatırnaz Ng
- Department of Medical Biology, Faculty of Medicine, Acibadem Mehmet Ali Aydinlar University, Istanbul, Turkey.,Department of Genetic, Aziz Sancar Institute of Experimental Medicine, Istanbul University, Istanbul, Turkey
| | - Mustafa Naziroglu
- Department of Biophysics, Faculty of Medicine, Suleyman Demirel University, Isparta, Turkey.,Drug Discovery Unit, BSN Health, Analyses, Innovation, Consultancy, Organization, Agriculture, Industry LTD. Inc, Göller Bölgesi Teknokenti, Isparta, Turkey
| | - Dervis Ozcelik
- Department of Biophysics, Cerrahpasa Medical Faculty, Istanbul University-Cerrahpasa, Istanbul, Turkey
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LaCorte S. How chronic administration of benzodiazepines leads to unexplained chronic illnesses: A hypothesis. Med Hypotheses 2018; 118:59-67. [PMID: 30037616 DOI: 10.1016/j.mehy.2018.06.019] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2018] [Revised: 05/28/2018] [Accepted: 06/19/2018] [Indexed: 11/15/2022]
Abstract
It is thought that an ill defined biochemical cascade may lead to protracted withdrawal symptoms subsequent to discontinuance of routine use of benzodiazepine class drugs and establish chronic illness in some patients. In this review, published findings are presented that support the novel concept that withdrawal from benzodiazepine class drugs can trigger elevated and sustained levels of a potent oxidant called peroxynitrite via potentiation of the L-type voltage-gated calcium channels, and in the later stages of withdrawal, via excessive N-methyl-D-aspartate receptor activity, as well. Potentiation of L-type voltage-gated calcium channels and excessive N-methyl-D-aspartate receptor activity both result in calcium influx into the cell that triggers nitric oxide synthesis. In pathophysiological conditions, such increased nitric oxide synthesis leads to peroxynitrite formation. The downstream effects of peroxynitrite formation that may occur during withdrawal ultimately lead to further peroxynitrite production in a system of overlapping vicious cycles collectively referred to as the NO/ONOO(-) cycle. Once triggered, the elements of the NO/ONOO(-) cycle perpetuate pathophysiology, perhaps including reduced GABAA receptor functioning, that may explain protracted withdrawal associated symptoms while the vicious cycle nature of the NO/ONOO(-) cycle may explain how withdrawal becomes a chronic state. Suboptimal levels of tetrahydrobiopterin may be one risk factor for the development of the protracted withdrawal syndrome as this will lead to partial nitric oxide uncoupling and resultant peroxynitrite formation. Nitric oxide uncoupling results in superoxide production as calcium-dependent nitric oxide synthases attempt to produce nitric oxide in response to L-type voltage-gated calcium channel-mediated calcium influx that is known to occur during withdrawal. The combination of nitric oxide and superoxide produced, as when partial uncoupling occurs, react together in a very rapid, diffusion limited reaction to form peroxynitrite and thereby trigger the NO/ONOO(-) cycle. The NO/ONOO(-) cycle may explain the nature of the protracted withdrawal syndrome and the related constellation of symptoms that are also common in other illnesses characterized as NO/ONOO(-) disorders such as myalgic encephalomyelitis/chronic fatigue syndrome and fibromyalgia.
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Affiliation(s)
- S LaCorte
- Benzodiazepine Information Coalition, 1042 Fort Union Blvd. Suite 1030, Midvale, UT 84047, United States.
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Ingwersen J, De Santi L, Wingerath B, Graf J, Koop B, Schneider R, Hecker C, Schröter F, Bayer M, Engelke AD, Dietrich M, Albrecht P, Hartung HP, Annunziata P, Aktas O, Prozorovski T. Nimodipine confers clinical improvement in two models of experimental autoimmune encephalomyelitis. J Neurochem 2018; 146:86-98. [PMID: 29473171 DOI: 10.1111/jnc.14324] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2017] [Revised: 02/07/2018] [Accepted: 02/08/2018] [Indexed: 12/31/2022]
Abstract
Multiple sclerosis is characterised by inflammatory neurodegeneration, with axonal injury and neuronal cell death occurring in parallel to demyelination. Regarding the molecular mechanisms responsible for demyelination and axonopathy, energy failure, aberrant expression of ion channels and excitotoxicity have been suggested to lead to Ca2+ overload and subsequent activation of calcium-dependent damage pathways. Thus, the inhibition of Ca2+ influx by pharmacological modulation of Ca2+ channels may represent a novel neuroprotective strategy in the treatment of secondary axonopathy. We therefore investigated the effects of the L-type voltage-gated calcium channel blocker nimodipine in two different models of mouse experimental autoimmune encephalomyelitis (EAE), an established experimental paradigm for multiple sclerosis. We show that preventive application of nimodipine (10 mg/kg per day) starting on the day of induction had ameliorating effects on EAE in SJL/J mice immunised with encephalitic myelin peptide PLP139-151 , specifically in late-stage disease. Furthermore, supporting these data, administration of nimodipine to MOG35-55 -immunised C57BL/6 mice starting at the peak of pre-established disease, also led to a significant decrease in disease score, indicating a protective effect on secondary CNS damage. Histological analysis confirmed that nimodipine attenuated demyelination, axonal loss and pathological axonal β-amyloid precursor protein accumulation in the cerebellum and spinal cord in the chronic phase of disease. Of note, we observed no effects of nimodipine on the peripheral immune response in EAE mice with regard to distribution, antigen-specific proliferation or activation patterns of lymphocytes. Taken together, our data suggest a CNS-specific effect of L-type voltage-gated calcium channel blockade to inflammation-induced neurodegeneration.
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Affiliation(s)
- Jens Ingwersen
- Department of Neurology, Medical Faculty, Heinrich-Heine-University, Düsseldorf, Germany
| | - Lorenzo De Santi
- Department of Neurology, Medical Faculty, Heinrich-Heine-University, Düsseldorf, Germany
- Department of Medicine, Surgery and Neuroscience, University of Siena, Siena, Italy
| | - Britta Wingerath
- Department of Neurology, Medical Faculty, Heinrich-Heine-University, Düsseldorf, Germany
| | - Jonas Graf
- Department of Neurology, Medical Faculty, Heinrich-Heine-University, Düsseldorf, Germany
| | - Barbara Koop
- Department of Neurology, Medical Faculty, Heinrich-Heine-University, Düsseldorf, Germany
| | - Reiner Schneider
- Department of Neurology, Medical Faculty, Heinrich-Heine-University, Düsseldorf, Germany
| | - Christina Hecker
- Department of Neurology, Medical Faculty, Heinrich-Heine-University, Düsseldorf, Germany
| | - Friederike Schröter
- Department of Neurology, Medical Faculty, Heinrich-Heine-University, Düsseldorf, Germany
| | - Mary Bayer
- Department of Neurology, Medical Faculty, Heinrich-Heine-University, Düsseldorf, Germany
| | - Anna Dorothee Engelke
- Department of Neurology, Medical Faculty, Heinrich-Heine-University, Düsseldorf, Germany
| | - Michael Dietrich
- Department of Neurology, Medical Faculty, Heinrich-Heine-University, Düsseldorf, Germany
| | - Philipp Albrecht
- Department of Neurology, Medical Faculty, Heinrich-Heine-University, Düsseldorf, Germany
| | - Hans-Peter Hartung
- Department of Neurology, Medical Faculty, Heinrich-Heine-University, Düsseldorf, Germany
| | - Pasquale Annunziata
- Department of Medicine, Surgery and Neuroscience, University of Siena, Siena, Italy
| | - Orhan Aktas
- Department of Neurology, Medical Faculty, Heinrich-Heine-University, Düsseldorf, Germany
| | - Tim Prozorovski
- Department of Neurology, Medical Faculty, Heinrich-Heine-University, Düsseldorf, Germany
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Liu J, Li X, Chen L, Xue P, Yang Q, Wang A. Increased calcineurin expression after pilocarpine-induced status epilepticus is associated with brain focal edema and astrogliosis. Int J Neurosci 2015; 126:560-567. [PMID: 26000933 DOI: 10.3109/00207454.2015.1045975] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Calcineurin plays an important role in the development of neuronal excitability, modulation of receptor's function and induction of apoptosis in neurons. It has been established in kindling models that status epilepticus induces brain focal edema and astrocyte activation. However, the role of calcineurin in brain focal edema and astrocyte activation in status epilepticus has not been fully understood. In this study, we employed a model of lithium-pilocarpine-induced status epilepticus and detected calcineurin expression in hippocampus by immunoblotting, brain focal edema by non-invasive magnetic resonance imaging (MRI-7T) and astrocyte expression by immunohistochemistry. We found that the brain focal edema was seen at 24 h after status epilepticus, and astrocyte expression was obviously seen at 7 d after status epilepticus. Meanwhile, calcineurin expression was seen at24 h and retained to 7 d after status epilepticus. A FK506, a calcineurin inhibitor, remarkably suppressed the status epilepticus-induced brain focal edema and astrocyte expression. Our data suggested that calcineurin overexpression plays a very important role in brain focal edema and astrocyte expression. Therefore, calcineurin may be a novel candidate for brain focal edema occurring and intracellular trigger of astrogliosis in status epilepticus.
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Affiliation(s)
- Jinzhi Liu
- a Department of Neurology, Shandong Provincial Qianfoshan Hospital , Shandong University , Jinan , P.R. China
| | - Xiaolin Li
- a Department of Neurology, Shandong Provincial Qianfoshan Hospital , Shandong University , Jinan , P.R. China
| | - Liguang Chen
- b Department of MRI Diagnosis , Shandong Medical Imaging Research Institute , Jinan , P.R. China
| | - Ping Xue
- a Department of Neurology, Shandong Provincial Qianfoshan Hospital , Shandong University , Jinan , P.R. China
| | - Qianqian Yang
- a Department of Neurology, Shandong Provincial Qianfoshan Hospital , Shandong University , Jinan , P.R. China
| | - Aihua Wang
- a Department of Neurology, Shandong Provincial Qianfoshan Hospital , Shandong University , Jinan , P.R. China
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Force spectroscopy measurements show that cortical neurons exposed to excitotoxic agonists stiffen before showing evidence of bleb damage. PLoS One 2013; 8:e73499. [PMID: 24023686 PMCID: PMC3758302 DOI: 10.1371/journal.pone.0073499] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2013] [Accepted: 07/22/2013] [Indexed: 12/12/2022] Open
Abstract
In ischemic and traumatic brain injury, hyperactivated glutamate (N-methyl-D-aspartic acid, NMDA) and sodium (Nav) channels trigger excitotoxic neuron death. Na+, Ca++ and H2O influx into affected neurons elicits swelling (increased cell volume) and pathological blebbing (disassociation of the plasma membrane’s bilayer from its spectrin-actomyosin matrix). Though usually conflated in injured tissue, cell swelling and blebbing are distinct processes. Around an injury core, salvageable neurons could be mildly swollen without yet having suffered the bleb-type membrane damage that, by rendering channels leaky and pumps dysfunctional, exacerbates the excitotoxic positive feedback spiral. Recognizing when neuronal inflation signifies non-lethal osmotic swelling versus blebbing should further efforts to salvage injury-penumbra neurons. To assess whether the mechanical properties of osmotically-swollen versus excitotoxically-blebbing neurons might be cytomechanically distinguishable, we measured cortical neuron elasticity (gauged via atomic force microscopy (AFM)-based force spectroscopy) upon brief exposure to hypotonicity or to excitotoxic agonists (glutamate and Nav channel activators, NMDA and veratridine). Though unperturbed by solution exchange per se, elasticity increased abruptly with hypotonicity, with NMDA and with veratridine. Neurons then invariably softened towards or below the pre-treatment level, sometimes starting before the washout. The initial channel-mediated stiffening bespeaks an abrupt elevation of hydrostatic pressure linked to NMDA or Nav channel-mediated ion/H2O fluxes, together with increased [Ca++]int-mediated submembrane actomyosin contractility. The subsequent softening to below-control levels is consistent with the onset of a lethal level of bleb damage. These findings indicate that dissection/identification of molecular events during the excitotoxic transition from stiff/swollen to soft/blebbing is warranted and should be feasible.
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