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Stringer RN, Weiss N. Pathophysiology of ion channels in amyotrophic lateral sclerosis. Mol Brain 2023; 16:82. [PMID: 38102715 PMCID: PMC10722804 DOI: 10.1186/s13041-023-01070-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2023] [Accepted: 12/11/2023] [Indexed: 12/17/2023] Open
Abstract
Amyotrophic lateral sclerosis (ALS) stands as the most prevalent and severe form of motor neuron disease, affecting an estimated 2 in 100,000 individuals worldwide. It is characterized by the progressive loss of cortical, brainstem, and spinal motor neurons, ultimately resulting in muscle weakness and death. Although the etiology of ALS remains poorly understood in most cases, the remodelling of ion channels and alteration in neuronal excitability represent a hallmark of the disease, manifesting not only during the symptomatic period but also in the early pre-symptomatic stages. In this review, we delve into these alterations observed in ALS patients and preclinical disease models, and explore their consequences on neuronal activities. Furthermore, we discuss the potential of ion channels as therapeutic targets in the context of ALS.
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Affiliation(s)
- Robin N Stringer
- Department of Pathophysiology, Third Faculty of Medicine, Charles University, Prague, Czech Republic
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Prague, Czech Republic
| | - Norbert Weiss
- Department of Pathophysiology, Third Faculty of Medicine, Charles University, Prague, Czech Republic.
- Center of Biosciences, Institute of Molecular Physiology and Genetics, Slovak Academy of Sciences, Bratislava, Slovakia.
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2
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Gento-Caro Á, Vilches-Herrando E, García-Morales V, Portillo F, Rodríguez-Bey G, González-Forero D, Moreno-López B. Interfering with lysophosphatidic acid receptor edg2/lpa 1 signalling slows down disease progression in SOD1-G93A transgenic mice. Neuropathol Appl Neurobiol 2021; 47:1004-1018. [PMID: 33508894 DOI: 10.1111/nan.12699] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2020] [Revised: 01/19/2021] [Accepted: 01/21/2021] [Indexed: 01/18/2023]
Abstract
AIMS Alterations in excitability represent an early hallmark in Amyotrophic Lateral Sclerosis (ALS). Therefore, deciphering the factors that impact motor neuron (MN) excitability offers an opportunity to uncover further aetiopathogenic mechanisms, neuroprotective agents, therapeutic targets, and/or biomarkers in ALS. Here, we hypothesised that the lipokine lysophosphatidic acid (lpa) regulates MN excitability via the G-protein-coupled receptor lpa1 . Then, modulating lpa1 -mediated signalling might affect disease progression in the ALS SOD1-G93A mouse model. METHODS The influence of lpa-lpa1 signalling on the electrical properties, Ca2+ dynamic and survival of MNs was tested in vitro. Expression of lpa1 in cultured MNs and in the spinal cord of SOD1-G93A mice was analysed. ALS mice were chronically treated with a small-interfering RNA against lpa1 (siRNAlpa1 ) or with the lpa1 inhibitor AM095. Motor skills, MN loss, and lifespan were evaluated. RESULTS AM095 reduced MN excitability. Conversely, exogenous lpa increased MN excitability by modulating task1 'leak' potassium channels downstream of lpa1 . Lpa-lpa1 signalling evoked an excitotoxic response in MNs via voltage-sensitive calcium channels. Cultured SOD1-G93A MNs displayed lpa1 upregulation and heightened vulnerability to lpa. In transgenic mice, lpa1 was upregulated mostly in spinal cord MNs before cell loss. Chronic administration of either siRNAlpa1 or AM095 reduced lpa1 expression at least in MNs, delayed MN death, improved motor skills, and prolonged life expectancy of ALS mice. CONCLUSIONS These results suggest that stressed lpa-lpa1 signalling contributes to MN degeneration in SOD1-G93A mice. Consequently, disrupting lpa1 slows down disease progression. This highlights LPA1 signalling as a potential target and/or biomarker in ALS.
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Affiliation(s)
- Ángela Gento-Caro
- Grupo de Neurodegeneración y Neurorreparación (GRUNEDERE), Área de Fisiología, Facultad de Medicina, Universidad de Cádiz, Cádiz, Spain.,Instituto de Investigación e Innovación Biomédica de Cádiz (INiBICA), Cádiz, Spain
| | - Esther Vilches-Herrando
- Grupo de Neurodegeneración y Neurorreparación (GRUNEDERE), Área de Fisiología, Facultad de Medicina, Universidad de Cádiz, Cádiz, Spain.,Instituto de Investigación e Innovación Biomédica de Cádiz (INiBICA), Cádiz, Spain
| | - Victoria García-Morales
- Grupo de Neurodegeneración y Neurorreparación (GRUNEDERE), Área de Fisiología, Facultad de Medicina, Universidad de Cádiz, Cádiz, Spain.,Instituto de Investigación e Innovación Biomédica de Cádiz (INiBICA), Cádiz, Spain
| | - Federico Portillo
- Grupo de Neurodegeneración y Neurorreparación (GRUNEDERE), Área de Fisiología, Facultad de Medicina, Universidad de Cádiz, Cádiz, Spain.,Instituto de Investigación e Innovación Biomédica de Cádiz (INiBICA), Cádiz, Spain
| | - Guillermo Rodríguez-Bey
- Grupo de Neurodegeneración y Neurorreparación (GRUNEDERE), Área de Fisiología, Facultad de Medicina, Universidad de Cádiz, Cádiz, Spain.,Department of Human Genetics. Graduate School of Public Health, University of Pittsburgh, Pittsburgh, PA, USA
| | - David González-Forero
- Grupo de Neurodegeneración y Neurorreparación (GRUNEDERE), Área de Fisiología, Facultad de Medicina, Universidad de Cádiz, Cádiz, Spain.,Instituto de Investigación e Innovación Biomédica de Cádiz (INiBICA), Cádiz, Spain
| | - Bernardo Moreno-López
- Grupo de Neurodegeneración y Neurorreparación (GRUNEDERE), Área de Fisiología, Facultad de Medicina, Universidad de Cádiz, Cádiz, Spain.,Instituto de Investigación e Innovación Biomédica de Cádiz (INiBICA), Cádiz, Spain
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3
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Chang Q, Martin LJ. Voltage-gated calcium channels are abnormal in cultured spinal motoneurons in the G93A-SOD1 transgenic mouse model of ALS. Neurobiol Dis 2016; 93:78-95. [PMID: 27151771 DOI: 10.1016/j.nbd.2016.04.009] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2014] [Revised: 04/01/2016] [Accepted: 04/29/2016] [Indexed: 12/12/2022] Open
Abstract
Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease characterized by progressive loss of motoneurons. Hyperexcitability and excitotoxicity have been implicated in the early pathogenesis of ALS. Studies addressing excitotoxic motoneuron death and intracellular Ca(2+) overload have mostly focused on Ca(2+) influx through AMPA glutamate receptors. However, intrinsic excitability of motoneurons through voltage-gated ion channels may also have a role in the neurodegeneration. In this study we examined the function and localization of voltage-gated Ca(2+) channels in cultured spinal cord motoneurons from mice expressing a mutant form of human superoxide dismutase-1 with a Gly93→Ala substitution (G93A-SOD1). Using whole-cell patch-clamp recordings, we showed that high voltage activated (HVA) Ca(2+) currents are increased in G93A-SOD1 motoneurons, but low voltage activated Ca(2+) currents are not affected. G93A-SOD1 motoneurons also have altered persistent Ca(2+) current mediated by L-type Ca(2+) channels. Quantitative single-cell RT-PCR revealed higher levels of Ca1a, Ca1b, Ca1c, and Ca1e subunit mRNA expression in G93A-SOD1 motoneurons, indicating that the increase of HVA Ca(2+) currents may result from upregulation of Ca(2+) channel mRNA expression in motoneurons. The localizations of the Ca1B N-type and Ca1D L-type Ca(2+) channels in motoneurons were examined by immunocytochemistry and confocal microscopy. G93A-SOD1 motoneurons had increased Ca1B channels on the plasma membrane of soma and dendrites. Ca1D channels are similar on the plasma membrane of soma and lower on the plasma membrane of dendrites of G93A-SOD1 motoneurons. Our study demonstrates that voltage-gated Ca(2+) channels have aberrant functions and localizations in ALS mouse motoneurons. The increased HVA Ca(2+) currents and PCCa current could contribute to early pathogenesis of ALS.
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Affiliation(s)
- Qing Chang
- Department of Pathology, Division of Neuropathology, Johns Hopkins University School of Medicine, MD 21205, United States.
| | - Lee J Martin
- Department of Pathology, Division of Neuropathology, Johns Hopkins University School of Medicine, MD 21205, United States; Department of Neuroscience, Johns Hopkins University School of Medicine, MD 21205, United States
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4
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Gutierrez-Merino C, Marques-da-Silva D, Fortalezas S, K. Samhan-Arias A. The critical role of lipid rafts nanodomains in the cross-talk between calcium and reactive oxygen and nitrogen species in cerebellar granule neurons apoptosis by extracellular potassium deprivation. AIMS MOLECULAR SCIENCE 2016. [DOI: 10.3934/molsci.2016.1.12] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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5
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Gou-Fabregas M, Ramírez-Núñez O, Cacabelos D, Bahi N, Portero M, Garcera A, Soler RM. Calpain activation and CaMKIV reduction in spinal cords from hSOD1G93A mouse model. Mol Cell Neurosci 2014; 61:219-25. [PMID: 25063475 DOI: 10.1016/j.mcn.2014.07.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2013] [Revised: 07/17/2014] [Accepted: 07/21/2014] [Indexed: 01/21/2023] Open
Abstract
Amyotrophic Lateral Sclerosis (ALS), a severe neurodegenerative disease, affects the upper and lower motor neurons in the brain and spinal cord. In some studies, ALS disease progression has been associated with an increase in calcium-dependent degeneration processes. Motoneurons are specifically vulnerable to sustained membrane depolarization and excessive elevation of intracellular calcium concentration. The present study analyzed intracellular events in embryonic motoneurons and adult spinal cords of the hSOD1G93A ALS mouse model. We observed activation of calpain, a calcium-dependent cysteine protease that degrades a variety of substrates, and a reduction in calcium-calmodulin dependent protein kinase type IV (CaMKIV) levels in protein extracts from spinal cords obtained at several time-points of hSOD1G93A mice disease progression. However, in cultured embryonic motoneurons these differences between controls and hSOD1G93A mutants are not evident. Our results support the hypothesis that age-dependent changes in calcium homeostasis and resulting events, e.g., calpain activation and CaMKIV processing, are involved in ALS pathogenesis.
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Affiliation(s)
- Myriam Gou-Fabregas
- Unitat de Senyalització Neuronal, Dept Ciencies Mediques Basiques, Facultat de Medicina, Universitat de Lleida, IRBLLEIDA, Rovira Roure, 80, 25198 Lleida, Spain
| | - Omar Ramírez-Núñez
- Dept Medicina Experimental, Facultat de Medicina, Universitat de Lleida, IRBLLEIDA, Rovira Roure, 80, 25198 Lleida, Spain
| | - Daniel Cacabelos
- Dept Medicina Experimental, Facultat de Medicina, Universitat de Lleida, IRBLLEIDA, Rovira Roure, 80, 25198 Lleida, Spain
| | - Nuria Bahi
- Unitat de Senyalització Neuronal, Dept Ciencies Mediques Basiques, Facultat de Medicina, Universitat de Lleida, IRBLLEIDA, Rovira Roure, 80, 25198 Lleida, Spain
| | - Manuel Portero
- Dept Medicina Experimental, Facultat de Medicina, Universitat de Lleida, IRBLLEIDA, Rovira Roure, 80, 25198 Lleida, Spain
| | - Ana Garcera
- Unitat de Senyalització Neuronal, Dept Ciencies Mediques Basiques, Facultat de Medicina, Universitat de Lleida, IRBLLEIDA, Rovira Roure, 80, 25198 Lleida, Spain
| | - Rosa M Soler
- Unitat de Senyalització Neuronal, Dept Ciencies Mediques Basiques, Facultat de Medicina, Universitat de Lleida, IRBLLEIDA, Rovira Roure, 80, 25198 Lleida, Spain.
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Komaki S, Ishikawa K, Arakawa Y. Trk and cAMP-dependent survival activity of adenosine A(2A) agonist CGS21680 on rat motoneurons in culture. Neurosci Lett 2012; 522:21-4. [PMID: 22691937 DOI: 10.1016/j.neulet.2012.06.003] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2012] [Revised: 05/27/2012] [Accepted: 06/01/2012] [Indexed: 01/01/2023]
Abstract
The survival activity of adenosine A(2A) agonist CGS21680 on motoneurons in culture through the transactivation of neurotrophin receptor TrkB has been reported previously; however, since adenosine A(2A) receptor belongs to a Gs-protein-coupled receptor, we investigated the involvement of the cAMP pathway in the survival activity of CGS21680 using purified motoneurons in culture. CGS21680 alone showed only small survival activity, but the activity was significantly enhanced by the addition of a phosphodiesterase inhibitor, IBMX. This survival activity was partially inhibited by a protein kinase A inhibitor H89 or a neurotrophin receptor tyrosine kinase inhibitor K252a, and was completely inhibited by their combination. These results indicate that the survival activity of CGS21680 on motoneurons is exerted by the mixed effect of the adenylate cyclase-cAMP-PKA pathway and transactivation of Trk neurotrophin receptor. Under conditions in which the maximum survival of motoneurons was supported by sufficient concentrations of brain-derived neurotrophic factor (BDNF), a TrkB ligand, the addition of 100μM AMPA for 3 days led to significant cell death. Treatment with CGS21680 and IBMX protected motoneurons from the toxicity of AMPA, further supporting the presence of a TrkB-independent pathway of CGS21680 activity and suggesting a novel therapeutic approach to motoneuron diseases such as amyotrophic lateral sclerosis.
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Affiliation(s)
- Satoshi Komaki
- Clinical Research Support Center, The University of Tokyo Hospital, Faculty of Medicine, The University of Tokyo, 7-3-1 Hongo, Tokyo 113-8655, Japan.
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Joshi DC, Singh M, Krishnamurthy K, Joshi PG, Joshi NB. AMPA induced Ca2+ influx in motor neurons occurs through voltage gated Ca2+ channel and Ca2+ permeable AMPA receptor. Neurochem Int 2011; 59:913-21. [PMID: 21777635 DOI: 10.1016/j.neuint.2011.06.023] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2011] [Revised: 06/27/2011] [Accepted: 06/29/2011] [Indexed: 11/19/2022]
Abstract
The rise in intracellular Ca(2+) mediated by AMPA subtype of glutamate receptors has been implicated in the pathogenesis of motor neuron disease, but the exact route of Ca(2+) entry into motor neurons is not clearly known. In the present study, we examined the role of voltage gated calcium channels (VGCCs) in AMPA induced Ca(2+) influx and subsequent intracellular signaling events responsible for motor neuron degeneration. AMPA stimulation caused sodium influx in spinal neurons that would depolarize the plasma membrane. The AMPA induced [Ca(2+)](i) rise in motor neurons as well as other spinal neurons was drastically reduced when extracellular sodium was replaced with NMDG, suggesting the involvement of voltage gated calcium channels. AMPA mediated rise in [Ca(2+)](i) was significantly inhibited by L-type VGCC blocker nifedipine, whereas ω-agatoxin-IVA and ω-conotoxin-GVIA, specific blockers of P/Q type and N-type VGCC were not effective. 1-Napthyl-acetyl spermine (NAS), an antagonist of Ca(2+) permeable AMPA receptors partially inhibited the AMPA induced [Ca(2+)](i) rise but selectively in motor neurons. Measurement of AMPA induced currents in whole cell voltage clamp mode suggests that a moderate amount of Ca(2+) influx occurs through Ca(2+) permeable AMPA receptors in a subpopulation of motor neurons. The AMPA induced mitochondrial calcium loading [Ca(2+)](m), mitochondrial depolarization and neurotoxicity were also significantly reduced in presence of nifedipine. Activation of VGCCs by depolarizing concentration of KCl (30mM) in extracellular medium increased the [Ca(2+)](i) but no change was observed in mitochondrial Ca(2+) and membrane potential. Our results demonstrate that a subpopulation of motor neurons express Ca(2+) permeable AMPA receptors, however the larger part of Ca(2+) influx occurs through L-type VGCCs subsequent to AMPA receptor activation and consequent mitochondrial dysfunction is the trigger for motor neuron degeneration. Nifedipine is an effective protective agent against AMPA induced mitochondrial stress and degeneration of motor neurons.
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Affiliation(s)
- Dinesh C Joshi
- Department of Biophysics, National Institute of Mental Health and Neuro Sciences, Bangalore 560 029, India
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8
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Mitochondrial Na+/Ca2+ exchanger, a new target for neuroprotection in rat hippocampal slices. Biochem Biophys Res Commun 2010; 400:140-4. [DOI: 10.1016/j.bbrc.2010.08.028] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2010] [Accepted: 08/07/2010] [Indexed: 12/17/2022]
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9
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Gou-Fabregas M, Garcera A, Mincheva S, Perez-Garcia MJ, Comella JX, Soler RM. Specific vulnerability of mouse spinal cord motoneurons to membrane depolarization. J Neurochem 2009; 110:1842-54. [PMID: 19627436 DOI: 10.1111/j.1471-4159.2009.06278.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Intracellular calcium (Ca(2+)) concentration determines neuronal dependence on neurotrophic factors (NTFs) and susceptibility to cell death. Ca(2+) overload induces neuronal death and the consequences are thought to be a probable cause of motoneuron (MN) degeneration in neurodegenerative diseases. In the present study, we show that membrane depolarization with elevated extracellular potassium (K(+)) was toxic to cultured embryonic mouse spinal cord MNs even in the presence of NTFs. Membrane depolarization induced an intracellular Ca(2+) increase. Depolarization-induced toxicity and increased intracellular Ca(2+) were blocked by treatment with antagonists to some of the voltage-gated Ca(2+) channels (VGCCs), indicating that Ca(2+) influx through these channels contributed to the toxic effect of depolarization. Ca(2+) activates the calpains, cysteine proteases that degrade a variety of substrates, causing cell death. We investigated the functional involvement of calpain using a calpain inhibitor and calpain gene silencing. Pre-treatment of MNs with calpeptin (a cell-permeable calpain inhibitor) rescued MNs survival; calpain RNA interference had the same protective effect, indicating that endogenous calpain contributes to the cell death caused by membrane depolarization. These findings suggest that MNs are especially vulnerable to extracellular K(+) concentration, which induces cell death by causing both intracellular Ca(2+) increase and calpain activation.
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Affiliation(s)
- Myriam Gou-Fabregas
- Neuronal Signaling Unit, Department Ciències Médiques Bàsiques, Facultat de Medicina, Universitat de Lleida-IRBLLEIDA, Montserrat Roig, Lleida, Spain
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10
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Tomimatsu N, Arakawa Y. Survival-promoting activity of pituitary adenylate cyclase-activating polypeptide in the presence of phosphodiesterase inhibitors on rat motoneurons in culture: cAMP-protein kinase A-mediated survival. J Neurochem 2008; 107:628-35. [PMID: 18717811 DOI: 10.1111/j.1471-4159.2008.05638.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Pituitary adenylate cyclase-activating polypeptide (PACAP) has been shown to be neurotrophic or neuroprotective in various neurons in culture. It is expressed in spinal motoneurons in vivo and its expression is increased markedly after axotomy, suggesting a neuroprotective role via an autocrine mechanism. However, neurotrophic activity of PACAP has not been reported for motoneurons. In the present study, we investigated the effects of PACAP on rat motoneurons in culture. In the presence of a phosphodiesterase inhibitor, PACAP showed significant neurotrophic activity at concentrations as low as 0.01 nM. Previously, we found that glutamate was excitotoxic to motoneurons even in the presence of brain-derived neurotrophic factor, which is neurotrophic for motoneurons. PACAP with a phosphodiesterase inhibitor protected motoneurons against this excitotoxicity. The activity of PACAP was inhibited by the protein kinase A inhibitor N-[2-(p-bromocinnamylamino) ethyl]-5-isoquinolinesulfonamide dihydrochloride, as was the case with the activity of forskolin, suggesting downstream involvement of a cAMP-protein kinase A signaling pathway. The present results may suggest a physiological role of PACAP in vivo, and implicate the PACAP-cAMP signaling pathway for the possible therapeutic target of amyotrophic lateral sclerosis as glutamate excitotoxicity was suggested in sporadic amyotrophic lateral sclerosis.
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Affiliation(s)
- Naoko Tomimatsu
- Clinical Research Center, The University of Tokyo Hospital, Faculty of Medicine, University of Tokyo, Tokyo, Japan
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11
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Tomimatsu N, Arakawa Y. Protein kinase C-mediated protection of motoneurons from excitotoxicity. Neurosci Lett 2008; 439:143-6. [DOI: 10.1016/j.neulet.2008.05.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2008] [Revised: 04/29/2008] [Accepted: 05/03/2008] [Indexed: 01/26/2023]
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12
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Uchida K, Nakajima H, Inukai T, Takamura T, Kobayashi S, Furukawa S, Baba H. Adenovirus-mediated retrograde transfer of neurotrophin-3 gene enhances survival of anterior horn neurons oftwy/twy mice with chronic mechanical compression of the spinal cord. J Neurosci Res 2008; 86:1789-800. [DOI: 10.1002/jnr.21627] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
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13
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Turner CP, Miller R, Smith C, Brown L, Blackstone K, Dunham SR, Strehlow R, Manfredi M, Slocum P, Iverson K, West M, Ringler SL, Berry ZC. Widespread Neonatal Brain Damage following Calcium Channel Blockade. Dev Neurosci 2006; 29:213-31. [PMID: 16921238 DOI: 10.1159/000095221] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2006] [Accepted: 04/04/2006] [Indexed: 01/05/2023] Open
Abstract
An abundance of evidence exists that shows calcium channel blockade promotes injury in cultured neurons. However, few studies have addressed the in vivo toxicity of such agents. We now show that the L-type calcium channel antagonist nimodipine promotes widespread and robust injury throughout the neonatal rat brain, in an age-dependent manner. Using both isolated neuronal as well as brain slice approaches, we address mechanisms behind such injury. These expanded studies show a consistent pattern of injury using a variety of agents that lower intracellular calcium. Collectively, these observations indicate that postnatal brain development represents a transitional period for still developing neurons, from being highly sensitive to reductions in intracellular calcium to being less vulnerable to such changes. These observations directly relate to current therapeutic strategies targeting neonatal brain injury.
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Affiliation(s)
- C P Turner
- Department of Neurobiology and Anatomy, Wake Forest University Medical School, Medical Center Boulevard, Winston-Salem, NC 27157-1010, USA.
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Gutiérrez-Martín Y, Martín-Romero FJ, Henao F, Gutiérrez-Merino C. Alteration of cytosolic free calcium homeostasis by SIN-1: high sensitivity of L-type Ca2+ channels to extracellular oxidative/nitrosative stress in cerebellar granule cells. J Neurochem 2005; 92:973-89. [PMID: 15686499 DOI: 10.1111/j.1471-4159.2004.02964.x] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Exposure of cerebellar granule neurones in 25 mm KCl HEPES-containing Locke's buffer (pH 7.4) to 50-100 microm SIN-1 during 2 h decreased the steady-state free cytosolic Ca2+ concentration ([Ca2+]i) from 168 +/- 33 nm to 60 +/- 10 nm, whereas exposure to > or = 0.3 mm SIN-1 produced biphasic kinetics: (i) decrease of [Ca2+]i during the first 30 min, reaching a limiting value of 75 +/- 10 nm (due to inactivation of L-type Ca2+ channels) and (ii) a delayed increase of [Ca2+]i at longer exposures, which correlated with SIN-1-induced necrotic cell death. Both effects of SIN-1 on [Ca2+]i are blocked by superoxide dismutase plus catalase and by Mn(III)tetrakis(4-benzoic acid)porphyrin chloride. Supplementation of Locke's buffer with catalase before addition of 0.5-1 mm SIN-1 had no effect on the decrease of [Ca2+]i but further delayed and attenuated the increase of [Ca2+]i observed after 60-120 min exposure to SIN-1 and also protected against SIN-1-induced necrotic cell death. alpha-Tocopherol, the potent NMDA receptor antagonist (+)-MK-801 and the N- and P-type Ca2+ channels blocker omega-conotoxin MVIIC had no effect on the alterations of [Ca2+]i upon exposure to SIN-1. However, inhibition of the plasma membrane Ca2+ ATPase can account for the increase of [Ca2+]i observed after 60-120 min exposure to 0.5-1 mm SIN-1. It is concluded that L-type Ca2+ channels are a primary target of SIN-1-induced extracellular nitrosative/oxidative stress, being inactivated by chronic exposure to fluxes of peroxynitrite of 0.5-1 microm/min, while higher concentrations of peroxynitrite and hydrogen peroxide are required for the inhibition of the plasma membrane Ca2+ ATPase and induction of necrotic cell death, respectively.
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Affiliation(s)
- Yolanda Gutiérrez-Martín
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias and Escuela de Ingenierías Agrarias, Universidad de Extremadura, Badajoz, Spain
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Abstract
We have conducted a long-term study of spinal cord morphology and motor function recovery in rats that have undergone lumbar spinal demyelination induced by the B-fragment of cholera toxin (CTB)-saporin. We found that, after the initial demyelination and paraplegia, motor function recovered and was stable for up to 9 months, after which there occurred a slow deterioration of motor function accompanied by loss of motoneurons and loss of spinal white matter. A striking morphological feature was the appearance of large spheroids of calcium in the ventral and dorsal horns and occasionally in the white matter. Motor performance deterioration occurred earlier and was more severe in rats that had been exercised on a treadmill, but the same morphological changes occurred in both exercise- and nonexercise-treated animals. Rats given treadmill exercise starting 3 weeks after toxin injection had a mean motor deficit score of 3.0 (i.e., paraplegia) at perfusion, whereas the nontreadmill-treated rats had a mean score of 1.8 (SD 0.38; n = 6; P <.05). These findings suggest that, in addition to the acute effects of the toxin-induced demyelination from which there is recovery of motor function, there are chronic irreversible effects of the toxin, or the initial demyelination, that cause a slow progressive degeneration of the spinal cord. This model might therefore be useful in studying the long-term effects of spinal insult of the type associated with conditions such as postpolio syndrome.
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Affiliation(s)
- Luc Jasmin
- Department of Neurological Surgery, University of California San Francisco, San Francisco, California 94143-0452, USA
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Pierrot N, Ghisdal P, Caumont AS, Octave JN. Intraneuronal amyloid-β1-42 production triggered by sustained increase of cytosolic calcium concentration induces neuronal death. J Neurochem 2004; 88:1140-50. [PMID: 15009669 DOI: 10.1046/j.1471-4159.2003.02227.x] [Citation(s) in RCA: 105] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Alzheimer's disease (AD) is a neurodegenerative disorder characterized by the presence in the brain of senile plaques which contain an amyloid core made of beta-amyloid peptide (Abeta). Abeta is produced by the cleavage of the amyloid precursor protein (APP). Since impairment of neuronal calcium signalling has been causally implicated in ageing and AD, we have investigated the influence of an influx of extracellular calcium on the metabolism of human APP in rat cortical neurones. We report that a high cytosolic calcium concentration, induced by neuronal depolarization, inhibits the alpha-secretase cleavage of APP and triggers the accumulation of intraneuronal C-terminal fragments produced by the beta-cleavage of the protein (CTFbeta). Increase in cytosolic calcium concentration specifically induces the production of large amounts of intraneuronal Abeta1-42, which is inhibited by nimodipine, a specific antagonist of l-type calcium channels. Moreover, calcium release from endoplasmic reticulum is not sufficient to induce the production of intraneuronal Abeta, which requires influx of extracellular calcium mediated by the capacitative calcium entry mechanism. Therefore, a sustained high concentration of cytosolic calcium is needed to induce the production of intraneuronal Abeta1-42 from human APP. Our results show that this accumulation of intraneuronal Abeta1-42 induces neuronal death, which is prevented by a functional gamma-secretase inhibitor.
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Affiliation(s)
- Nathalie Pierrot
- Université catholique de Louvain, FARL/UCL 54 10, Brussels, Belgium
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