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Avila ME, Sepúlveda FJ, Burgos CF, Moraga-Cid G, Parodi J, Moon RT, Aguayo LG, Opazo C, De Ferrari GV. Correction: Canonical Wnt3a modulates intracellular calcium and enhances excitatory neurotransmission in hippocampal neurons. J Biol Chem 2020; 295:9265. [PMID: 32620693 DOI: 10.1074/jbc.aac120.014663] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
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2
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Palma-Chavez A, Konar-Nié M, Órdenes P, Maurelia F, Elizondo-Vega R, Oyarce K, López S, Rojas J, Steinberg X, García-Robles MA, Sepúlveda FJ. Glucose Increase DAGLα Levels in Tanycytes and Its Inhibition Alters Orexigenic and Anorexigenic Neuropeptides Expression in Response to Glucose. Front Endocrinol (Lausanne) 2019; 10:647. [PMID: 31620093 PMCID: PMC6763563 DOI: 10.3389/fendo.2019.00647] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/28/2019] [Accepted: 09/05/2019] [Indexed: 12/11/2022] Open
Abstract
The endocannabinoid system (ECS) is composed of a group of Gi-coupled protein receptors and enzymes, producing and degrading the endocannabinoids, 2-arachidonoylglycerol (2-AG) and N-arachidonoyl-ethanolamine (AEA). Endocannabinoid-mediated signaling modulates brain functions, such as pain, mood, memory, and feeding behavior. The activation of the ECS is associated with overeating and obesity; however, the expression of components of this system has been only partially studied in the hypothalamus, a critical region implicated in feeding behavior. Within this brain region, anorexigenic, and orexigenic neurons of the arcuate nucleus (ARC) are in close contact with tanycytes, glial radial-like cells that line the lateral walls and floor of the third ventricle (3V). The specific function of tanycytes and the effects of metabolic signals generated by them on adjacent neurons is starting to be elucidated. We have proposed that the ECS within tanycytes modulates ARC neurons, thus modifying food intake. Here, we evaluated the expression and the loss of function of the 2-AG-producing enzyme, diacylglycerol lipase-alpha (DAGLα). Using Western blot and immunohistochemistry analyses in basal hypothalamus sections of adult rats under several glycemic conditions, we confirm that DAGLα is strongly expressed at the basal hypothalamus in glial and neuronal cells, increasing further in response to greater extracellular glucose levels. Using a DAGLα-inhibiting adenovirus (shRNA), suppression of DAGLα expression in tanycytes altered the usual response to intracerebroventricular glucose in terms of neuropeptides produced by neurons of the ARC. Thus, these results strongly suggest that the tanycytes could generate 2-AG, which modulates the function of anorexigenic and orexigenic neurons.
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Affiliation(s)
- Alejandra Palma-Chavez
- Laboratorio de Biología Celular, Departamento de Biología Celular, Universidad de Concepcion, Concepción, Chile
- Laboratorio de Bioquímica y Biología Celular, Departamento de Bioquímica y Biología Molecular, Universidad de Concepción, Concepción, Chile
| | - Macarena Konar-Nié
- Laboratorio de Biología Celular, Departamento de Biología Celular, Universidad de Concepcion, Concepción, Chile
| | - Patricio Órdenes
- Laboratorio de Biología Celular, Departamento de Biología Celular, Universidad de Concepcion, Concepción, Chile
| | - Felipe Maurelia
- Laboratorio de Bioquímica y Biología Celular, Departamento de Bioquímica y Biología Molecular, Universidad de Concepción, Concepción, Chile
| | - Roberto Elizondo-Vega
- Laboratorio de Biología Celular, Departamento de Biología Celular, Universidad de Concepcion, Concepción, Chile
| | - Karina Oyarce
- Facultad de Medicina y Ciencia, Universidad San Sebastián, Concepción, Chile
| | - Sergio López
- Laboratorio de Biología Celular, Departamento de Biología Celular, Universidad de Concepcion, Concepción, Chile
| | - Joaquin Rojas
- Centro de Estudios Avanzados para la Vida (CREAV), Universidad de Concepción, Concepción, Chile
| | - Ximena Steinberg
- Laboratorio de Bioquímica y Biología Celular, Departamento de Bioquímica y Biología Molecular, Universidad de Concepción, Concepción, Chile
| | - María A. García-Robles
- Laboratorio de Biología Celular, Departamento de Biología Celular, Universidad de Concepcion, Concepción, Chile
- Centro de Estudios Avanzados para la Vida (CREAV), Universidad de Concepción, Concepción, Chile
- *Correspondence: María A. García-Robles
| | - Fernando J. Sepúlveda
- Laboratorio de Biología Celular, Departamento de Biología Celular, Universidad de Concepcion, Concepción, Chile
- Laboratorio de Bioquímica y Biología Celular, Departamento de Bioquímica y Biología Molecular, Universidad de Concepción, Concepción, Chile
- Fernando J. Sepúlveda
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Miranda MT, Sepúlveda FJ, Arranz JI, Montero I, Rojas CV. Analysis of pelletizing from corn cob waste. J Environ Manage 2018; 228:303-311. [PMID: 30236883 DOI: 10.1016/j.jenvman.2018.08.105] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/07/2017] [Revised: 02/09/2018] [Accepted: 08/29/2018] [Indexed: 06/08/2023]
Abstract
In recent years, biomass market has constantly increased. Pellet industry has started looking for new products with the potential to be used as biofuels. Among them are agricultural wastes, such as corn cob waste, which presents some characteristics that make its direct use in industrial facilities possible. However, these properties are not enough for its use in domestic stoves and boilers, where higher quality of fuel is needed. For this reason, densification is used. In the present research work a technical and energy analysis of corn cob waste pelletizing was carried out in a semi-industrial pelletizer. Some relationships between variables, such as moisture, bulk density and mechanical durability, were analyzed, as well as their influence on energy use and final productivity. The results were satisfactory, as the pellets manufactured fulfilled with most specifications that were consulted, with higher values than those recorded for similar kinds of pellets. Concerning the energy study, the increase in production justified a higher energy consumption of the process in order to get a higher productivity ratio.
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Affiliation(s)
- M T Miranda
- Industrial Engineering School, University of Extremadura, Av. Elvas s/n, Badajoz 06006, Spain
| | - F J Sepúlveda
- Industrial Engineering School, University of Extremadura, Av. Elvas s/n, Badajoz 06006, Spain
| | - J I Arranz
- Industrial Engineering School, University of Extremadura, Av. Elvas s/n, Badajoz 06006, Spain.
| | - I Montero
- Industrial Engineering School, University of Extremadura, Av. Elvas s/n, Badajoz 06006, Spain
| | - C V Rojas
- Industrial Engineering School, University of Extremadura, Av. Elvas s/n, Badajoz 06006, Spain
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Fernández-Pérez EJ, Sepúlveda FJ, Peters C, Bascuñán D, Riffo-Lepe NO, González-Sanmiguel J, Sánchez SA, Peoples RW, Vicente B, Aguayo LG. Effect of Cholesterol on Membrane Fluidity and Association of Aβ Oligomers and Subsequent Neuronal Damage: A Double-Edged Sword. Front Aging Neurosci 2018; 10:226. [PMID: 30123122 PMCID: PMC6085471 DOI: 10.3389/fnagi.2018.00226] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2018] [Accepted: 07/03/2018] [Indexed: 02/06/2023] Open
Abstract
Background: The beta-amyloid peptide (Aβ) involved in Alzheimer's disease (AD) has been described to associate/aggregate on the cell surface disrupting the membrane through pore formation and breakage. However, molecular determinants involved for this interaction (e.g., some physicochemical properties of the cell membrane) are largely unknown. Since cholesterol is an important molecule for membrane structure and fluidity, we examined the effect of varying cholesterol content with the association and membrane perforation by Aβ in cultured hippocampal neurons. Methods: To decrease or increase the levels of cholesterol in the membrane we used methyl-β-cyclodextrin (MβCD) and MβCD/cholesterol, respectively. We analyzed if membrane fluidity was affected using generalized polarization (GP) imaging and the fluorescent dye di-4-ANEPPDHQ. Additionally membrane association and perforation was assessed using immunocytochemistry and electrophysiological techniques, respectively. Results: The results showed that cholesterol removal decreased the macroscopic association of Aβ to neuronal membranes (fluorescent-puncta/20 μm: control = 18 ± 2 vs. MβCD = 10 ± 1, p < 0.05) and induced a facilitation of the membrane perforation by Aβ with respect to control cells (half-time for maximal charge transferred: control = 7.2 vs. MβCD = 4.4). Under this condition, we found an increase in membrane fluidity (46 ± 3.3% decrease in GP value, p < 0.001). On the contrary, increasing cholesterol levels incremented membrane rigidity (38 ± 2.7% increase in GP value, p < 0.001) and enhanced the association and clustering of Aβ (fluorescent-puncta/20 μm: control = 18 ± 2 vs. MβCD = 10 ± 1, p < 0.01), but inhibited membrane disruption. Conclusion: Our results strongly support the significance of plasma membrane organization in the toxic effects of Aβ in hippocampal neurons, since fluidity can regulate distribution and insertion of the Aβ peptide in the neuronal membrane.
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Affiliation(s)
- Eduardo J Fernández-Pérez
- Laboratory of Neurophysiology, Department of Physiology, Universidad de Concepción, Concepción, Chile
| | - Fernando J Sepúlveda
- Laboratory of Neurophysiology, Department of Physiology, Universidad de Concepción, Concepción, Chile
| | - Christian Peters
- Laboratory of Neurophysiology, Department of Physiology, Universidad de Concepción, Concepción, Chile
| | - Denisse Bascuñán
- Laboratory of Neurophysiology, Department of Physiology, Universidad de Concepción, Concepción, Chile
| | - Nicolás O Riffo-Lepe
- Laboratory of Neurophysiology, Department of Physiology, Universidad de Concepción, Concepción, Chile
| | | | - Susana A Sánchez
- Departamento de Polímeros, Facultad de Ciencias Químicas, Universidad de Concepción, Concepción, Chile
| | - Robert W Peoples
- Department of Biomedical Sciences, Marquette University, Milwaukee, WI, United States
| | - Benjamín Vicente
- Department of Psychiatry and Mental Health, Universidad de Concepción, Concepción, Chile
| | - Luis G Aguayo
- Laboratory of Neurophysiology, Department of Physiology, Universidad de Concepción, Concepción, Chile
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Peters C, Sepúlveda FJ, Fernández-Pérez EJ, Peoples RW, Aguayo LG. The Level of NMDA Receptor in the Membrane Modulates Amyloid-β Association and Perforation. J Alzheimers Dis 2018; 53:197-207. [PMID: 27163827 DOI: 10.3233/jad-160170] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Alzheimer's disease is a neurodegenerative disorder that affects mostly the elderly. The main histopathological markers are the senile plaques formed by amyloid-β peptide (Aβ) aggregates that can perforate the plasma membrane of cells, increasing the intracellular calcium levels and releasing synaptic vesicles that finally lead to a delayed synaptic failure. Several membrane proteins and lipids interact with Aβ affecting its toxicity in neurons. Here, we focus on NMDA receptors (NMDARs) as proteins that could be modulating the association and neurotoxic perforation induced by Aβ on the plasma membrane. In fact, our results showed that decreasing NMDARs, using enzymatic or siRNA approaches, increased the association of Aβ to the neurons. Furthermore, overexpression of NMDARs also resulted in an enhanced association between NMDA and Aβ. Functionally, the reduction in membrane NMDARs augmented the process of membrane perforation. On the other hand, overexpressing NMDARs had a protective effect because Aβ was now unable to cause membrane perforation, suggesting a complex relationship between Aβ and NMDARs. Because previous studies have recognized that Aβ oligomers are able to increase membrane permeability and produce amyloid pores, the present study supports the conclusion that NMDARs play a critical protective role on Aβ actions in hippocampal neurons. These results could explain the lack of correlation between brain Aβ burden and clinically observed dementia.
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Affiliation(s)
- Christian Peters
- Laboratory of Neurophysiology, Department of Physiology, Universidad de Concepción, Chile
| | - Fernando J Sepúlveda
- Laboratory of Neurophysiology, Department of Physiology, Universidad de Concepción, Chile
| | | | - Robert W Peoples
- Laboratory of Biomedical Sciences, Marquette University, Milwaukee, WI, USA
| | - Luis G Aguayo
- Laboratory of Neurophysiology, Department of Physiology, Universidad de Concepción, Chile
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6
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Fernández-Pérez EJ, Sepúlveda FJ, Peters C, Bascuñán D, Riffo-Lepe NO, González-Sanmiguel J, Sánchez SA, Peoples RW, Vicente B, Aguayo LG. Effect of Cholesterol on Membrane Fluidity and Association of Aβ Oligomers and Subsequent Neuronal Damage: A Double-Edged Sword. Front Aging Neurosci 2018. [PMID: 30123122 DOI: 10.3389/fnagi.2018.002.26] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/09/2023] Open
Abstract
Background: The beta-amyloid peptide (Aβ) involved in Alzheimer's disease (AD) has been described to associate/aggregate on the cell surface disrupting the membrane through pore formation and breakage. However, molecular determinants involved for this interaction (e.g., some physicochemical properties of the cell membrane) are largely unknown. Since cholesterol is an important molecule for membrane structure and fluidity, we examined the effect of varying cholesterol content with the association and membrane perforation by Aβ in cultured hippocampal neurons. Methods: To decrease or increase the levels of cholesterol in the membrane we used methyl-β-cyclodextrin (MβCD) and MβCD/cholesterol, respectively. We analyzed if membrane fluidity was affected using generalized polarization (GP) imaging and the fluorescent dye di-4-ANEPPDHQ. Additionally membrane association and perforation was assessed using immunocytochemistry and electrophysiological techniques, respectively. Results: The results showed that cholesterol removal decreased the macroscopic association of Aβ to neuronal membranes (fluorescent-puncta/20 μm: control = 18 ± 2 vs. MβCD = 10 ± 1, p < 0.05) and induced a facilitation of the membrane perforation by Aβ with respect to control cells (half-time for maximal charge transferred: control = 7.2 vs. MβCD = 4.4). Under this condition, we found an increase in membrane fluidity (46 ± 3.3% decrease in GP value, p < 0.001). On the contrary, increasing cholesterol levels incremented membrane rigidity (38 ± 2.7% increase in GP value, p < 0.001) and enhanced the association and clustering of Aβ (fluorescent-puncta/20 μm: control = 18 ± 2 vs. MβCD = 10 ± 1, p < 0.01), but inhibited membrane disruption. Conclusion: Our results strongly support the significance of plasma membrane organization in the toxic effects of Aβ in hippocampal neurons, since fluidity can regulate distribution and insertion of the Aβ peptide in the neuronal membrane.
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Affiliation(s)
- Eduardo J Fernández-Pérez
- Laboratory of Neurophysiology, Department of Physiology, Universidad de Concepción, Concepción, Chile
| | - Fernando J Sepúlveda
- Laboratory of Neurophysiology, Department of Physiology, Universidad de Concepción, Concepción, Chile
| | - Christian Peters
- Laboratory of Neurophysiology, Department of Physiology, Universidad de Concepción, Concepción, Chile
| | - Denisse Bascuñán
- Laboratory of Neurophysiology, Department of Physiology, Universidad de Concepción, Concepción, Chile
| | - Nicolás O Riffo-Lepe
- Laboratory of Neurophysiology, Department of Physiology, Universidad de Concepción, Concepción, Chile
| | | | - Susana A Sánchez
- Departamento de Polímeros, Facultad de Ciencias Químicas, Universidad de Concepción, Concepción, Chile
| | - Robert W Peoples
- Department of Biomedical Sciences, Marquette University, Milwaukee, WI, United States
| | - Benjamín Vicente
- Department of Psychiatry and Mental Health, Universidad de Concepción, Concepción, Chile
| | - Luis G Aguayo
- Laboratory of Neurophysiology, Department of Physiology, Universidad de Concepción, Concepción, Chile
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7
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Barahona MJ, Llanos P, Recabal A, Escobar-Acuña K, Elizondo-Vega R, Salgado M, Ordenes P, Uribe E, Sepúlveda FJ, Araneda RC, García-Robles MA. Glial hypothalamic inhibition of GLUT2 expression alters satiety, impacting eating behavior. Glia 2017; 66:592-605. [PMID: 29178321 PMCID: PMC5814884 DOI: 10.1002/glia.23267] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2017] [Revised: 10/31/2017] [Accepted: 11/07/2017] [Indexed: 12/22/2022]
Abstract
Glucose is a key modulator of feeding behavior. By acting in peripheral tissues and in the central nervous system, it directly controls the secretion of hormones and neuropeptides and modulates the activity of the autonomic nervous system. GLUT2 is required for several glucoregulatory responses in the brain, including feeding behavior, and is localized in the hypothalamus and brainstem, which are the main centers that control this behavior. In the hypothalamus, GLUT2 has been detected in glial cells, known as tanycytes, which line the basal walls of the third ventricle (3V). This study aimed to clarify the role of GLUT2 expression in tanycytes in feeding behavior using 3V injections of an adenovirus encoding a shRNA against GLUT2 and the reporter EGFP (Ad‐shGLUT2). Efficient in vivo GLUT2 knockdown in rat hypothalamic tissue was demonstrated by qPCR and Western blot analyses. Specificity of cell transduction in the hypothalamus and brainstem was evaluated by EGFP‐fluorescence and immunohistochemistry, which showed EGFP expression specifically in ependymal cells, including tanycytes. The altered mRNA levels of both orexigenic and anorexigenic neuropeptides suggested a loss of response to increased glucose in the 3V. Feeding behavior analysis in the fasting‐feeding transition revealed that GLUT2‐knockdown rats had increased food intake and body weight, suggesting an inhibitory effect on satiety. Taken together, suppression of GLUT2 expression in tanycytes disrupted the hypothalamic glucosensing mechanism, which altered the feeding behavior.
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Affiliation(s)
- María J Barahona
- Laboratorio de Biología Celular, Departamento de Biología Celular, Facultad de Ciencias Biológicas, Universidad de Concepción, Concepción, Chile
| | - Paula Llanos
- Laboratorio de Biología Celular, Departamento de Biología Celular, Facultad de Ciencias Biológicas, Universidad de Concepción, Concepción, Chile
| | - Antonia Recabal
- Laboratorio de Biología Celular, Departamento de Biología Celular, Facultad de Ciencias Biológicas, Universidad de Concepción, Concepción, Chile
| | - Kathleen Escobar-Acuña
- Laboratorio de Biología Celular, Departamento de Biología Celular, Facultad de Ciencias Biológicas, Universidad de Concepción, Concepción, Chile
| | - Roberto Elizondo-Vega
- Laboratorio de Biología Celular, Departamento de Biología Celular, Facultad de Ciencias Biológicas, Universidad de Concepción, Concepción, Chile.,Laboratorio de Inmunología Celular y Molecular, Centro de Investigación Biomédica, Facultad de Medicina, Universidad de los Andes, Santiago, Chile
| | - Magdiel Salgado
- Laboratorio de Biología Celular, Departamento de Biología Celular, Facultad de Ciencias Biológicas, Universidad de Concepción, Concepción, Chile
| | - Patricio Ordenes
- Laboratorio de Biología Celular, Departamento de Biología Celular, Facultad de Ciencias Biológicas, Universidad de Concepción, Concepción, Chile
| | - Elena Uribe
- Departamento de Bioquímica y Biología Molecular, Universidad de Concepción, Chile
| | - Fernando J Sepúlveda
- Departamento de Bioquímica y Biología Molecular, Universidad de Concepción, Chile.,Departamento de Ciencias Biológica Universidad Andrés Bello, Concepción, Chile
| | - Ricardo C Araneda
- Department of Biology, University of Maryland, College Park, Maryland
| | - María A García-Robles
- Laboratorio de Biología Celular, Departamento de Biología Celular, Facultad de Ciencias Biológicas, Universidad de Concepción, Concepción, Chile
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8
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Castro PA, Ramirez A, Sepúlveda FJ, Peters C, Fierro H, Waldron J, Luza S, Fuentealba J, Muñoz FJ, De Ferrari GV, Bush AI, Aguayo LG, Opazo CM. Copper-uptake is critical for the down regulation of synapsin and dynamin induced by neocuproine: modulation of synaptic activity in hippocampal neurons. Front Aging Neurosci 2014; 6:319. [PMID: 25520655 PMCID: PMC4253966 DOI: 10.3389/fnagi.2014.00319] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2014] [Accepted: 10/30/2014] [Indexed: 01/08/2023] Open
Abstract
Extracellular and intracellular copper and zinc regulate synaptic activity and plasticity, which may impact brain functionality and human behavior. We have found that a metal coordinating molecule, Neocuproine, transiently increases free intracellular copper and zinc levels (i.e., min) in hippocampal neurons as monitored by Phen Green and FluoZin-3 fluorescence, respectively. The changes in free intracellular zinc induced by Neocuproine were abolished by the presence of a non-permeant copper chelator, Bathocuproine (BC), indicating that copper influx is needed for the action of Neocuproine on intracellular Zn levels. Moreover, Neocuproine decreased the mRNA levels of Synapsin and Dynamin, and did not affect the expression of Bassoon, tubulin or superoxide dismutase (SOD). Western blot analysis showed that protein levels of synapsin and dynamin were also down regulated in the presence of Neocuproine and that these changes were accompanied by a decrease in calcium transients and neuronal activity. Furthermore, Neocuproine decreased the number of active neurons, effect that was blocked by the presence of BC, indicating that copper influx is needed for the action of Neocuproine. We finally show that Neocuproine blocks the epileptiform-like activity induced by bicuculline in hippocampal neurons. Collectively, our data indicates that presynaptic protein configuration and function of primary hippocampal neurons is sensitive to transient changes in transition metal homeostasis. Therefore, small molecules able to coordinate transition metals and penetrate the blood-brain barrier might modify neurotransmission at the Central Nervous System (CNS). This might be useful to establish therapeutic approaches to control the neuronal hyperexcitabiltity observed in brain conditions that are associated to copper dyshomeotasis such as Alzheimer’s and Menkes diseases. Our work also opens a new avenue to find novel and effective antiepilepsy drugs based in metal coordinating molecules.
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Affiliation(s)
- Patricio A Castro
- Department of Physiology and Membrane Biology, Shriners Hospital for Children Northern California, University of California at Davis School of Medicine California, USA
| | - Alejandra Ramirez
- Laboratorio de Neurofisiología, Departamento de Fisiología, Facultad de Ciencias Biológicas, Universidad de Concepción Concepción, Chile ; Oxidation Biology Laboratory, The Florey Institute of Neuroscience and Mental Health, The University of Melbourne Parkville, Melbourne, Victoria, Australia
| | - Fernando J Sepúlveda
- Laboratorio de Neurofisiología, Departamento de Fisiología, Facultad de Ciencias Biológicas, Universidad de Concepción Concepción, Chile
| | - Christian Peters
- Laboratorio de Neurofisiología, Departamento de Fisiología, Facultad de Ciencias Biológicas, Universidad de Concepción Concepción, Chile
| | - Humberto Fierro
- Laboratorio de Neurofisiología, Departamento de Fisiología, Facultad de Ciencias Biológicas, Universidad de Concepción Concepción, Chile
| | - Javier Waldron
- Laboratorio de Neurofisiología, Departamento de Fisiología, Facultad de Ciencias Biológicas, Universidad de Concepción Concepción, Chile
| | - Sandra Luza
- Oxidation Biology Laboratory, The Florey Institute of Neuroscience and Mental Health, The University of Melbourne Parkville, Melbourne, Victoria, Australia
| | - Jorge Fuentealba
- Laboratorio de Neurofisiología, Departamento de Fisiología, Facultad de Ciencias Biológicas, Universidad de Concepción Concepción, Chile
| | - Francisco J Muñoz
- Laboratory of Molecular Physiology and Channelopathies, Departament de Ciències Experimentals i de la Salut, Universitat Pompeu Fabra Barcelona, Spain
| | - Giancarlo V De Ferrari
- Center for Biomedical Research and FONDAP Center for Genome Regulation, Universidad Andrés Bello Santiago, Chile
| | - Ashley I Bush
- Oxidation Biology Laboratory, The Florey Institute of Neuroscience and Mental Health, The University of Melbourne Parkville, Melbourne, Victoria, Australia
| | - Luis G Aguayo
- Laboratorio de Neurofisiología, Departamento de Fisiología, Facultad de Ciencias Biológicas, Universidad de Concepción Concepción, Chile
| | - Carlos M Opazo
- Oxidation Biology Laboratory, The Florey Institute of Neuroscience and Mental Health, The University of Melbourne Parkville, Melbourne, Victoria, Australia
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Zurita MP, Muñoz G, Sepúlveda FJ, Gómez P, Castillo C, Burgos CF, Fuentealba J, Opazo C, Aguayo LG. Ibuprofen inhibits the synaptic failure induced by the amyloid-β peptide in hippocampal neurons. J Alzheimers Dis 2013; 35:463-73. [PMID: 23455989 DOI: 10.3233/jad-122314] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Epidemiological studies have reported a decrease in the prevalence of Alzheimer's disease in individuals who chronically use non-steroidal anti-inflammatory drugs (NSAIDs). Clinical trials, on the other hand, have been less positive. Nevertheless, it has been proposed that NSAIDs exert part of their effects by reducing long-term cerebral neuroinflammation, although this mechanism has not been proven. In this study, we report that ibuprofen, one of the more widely used non-steroidal anti-inflammatory drugs, was able to alter the ultrastructure of amyloid-β peptide (Aβ) and significantly decrease its association to neuronal membranes, and consequently, its synaptotoxic effect in rat primary hippocampal and cortical cultures at 24 h incubation. In agreement with these results, we found that the decrease in the frequency of calcium transients with Aβ was partly recovered by addition of ibuprofen (8.0 × 10-2 Hz in control; 3.4 × 10-2 Hz in 5 μM Aβ, and 5.9 × 10-2 Hz in the presence of Aβ and 200 μM ibuprofen). Additionally, this effect correlated well with the increment and recovery of miniature spontaneous currents (47 ± 5% of control in 1 μM Aβ alone and 104 ± 14% in the presence of Aβ and ibuprofen). Our results suggest that ibuprofen could be exerting its neuroprotective effect by directly interacting with Aβ and altering its toxic aggregated forms. We postulate that other ibuprofen analogs with better pharmacological properties might have a higher efficacy in AD.
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Affiliation(s)
- Maria Paz Zurita
- Laboratory of Neurophysiology, Department of Physiology, Faculty of Biological Sciences, University of Concepción, Concepción, Chile
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Sepúlveda FJ, Fierro H, Fernandez E, Castillo C, Peoples RW, Opazo C, Aguayo LG. Nature of the neurotoxic membrane actions of amyloid-β on hippocampal neurons in Alzheimer's disease. Neurobiol Aging 2013; 35:472-81. [PMID: 24112789 DOI: 10.1016/j.neurobiolaging.2013.08.035] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2013] [Revised: 08/26/2013] [Accepted: 08/30/2013] [Indexed: 10/26/2022]
Abstract
The mechanism by which amyloid-β (Aβ) produces brain dysfunction in patients with Alzheimer's disease is largely unknown. According to previous studies, Aβ might share perforating properties with gramicidin, a well-accepted membrane-disrupting peptide. Therefore, we hypothesize that the key steps leading to synaptotoxicity by Aβ and gramicidin involve peptide aggregation, pore formation, and calcium dysregulation. Here, we show that Aβ and gramicidin form aggregates enriched in β-sheet structures using electron microscopy, and Thioflavin and Congo Red staining techniques. Also, we found that Aβ and gramicidin display fairly similar actions in hippocampal cell membranes, i.e. inducing Ca(2+) entry and synaptoxicity characterized by the loss of synaptic proteins and a decrease in neuronal viability. These effects were not observed in a Ca(2+) free solution, indicating that both Aβ and gramicidin induce neurotoxicity by a Ca(2+)-dependent mechanism. Using combined perforated patch clamp and imaging recordings, we found that only Aβ produced a perforation that progressed from a small (Cl(-)-selective pore) to a larger perforation that allowed the entry of fluorescent molecules. Therefore, based on these results, we propose that the perforation at the plasma membrane by Aβ is a dynamic process that is critical in producing neurotoxicity similar to that found in the brains of AD patients.
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Affiliation(s)
- Fernando J Sepúlveda
- Laboratory of Neurophysiology, Department of Physiology, University of Concepción, Concepción, Chile
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Peters C, Muñoz B, Sepúlveda FJ, Urrutia J, Quiroz M, Luza S, De Ferrari GV, Aguayo LG, Opazo C. Biphasic effects of copper on neurotransmission in rat hippocampal neurons. J Neurochem 2011; 119:78-88. [PMID: 21824141 DOI: 10.1111/j.1471-4159.2011.07417.x] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The importance of copper in the CNS is well documented, but the mechanisms related to its brain functions are poorly understood. Copper is released at the synaptic cleft, where it may modulate neurotransmission. To understand the functional impact of copper on the neuronal network, we have analyzed the synaptic activity of primary rat hippocampal neurons by using different approaches including whole cell patch clamp, recording of calcium transients, immunofluorescence and western blot. Here, we show that copper produces biphasic changes in neurotransmission. When copper is acutely applied to the plate it blocks neurotransmission. Interestingly, when it is applied for 3 h to hippocampal neurons it mainly increases the frequency and amplitude of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)ergic currents (control: 0.21 ± 0.05 Hz/22.9 ± 1.3 pA; copper: 0.68 ± 0.16 Hz/30.5 ± 2.5 pA), intracellular calcium transients (control: 0.05 ± 0.013 Hz; copper: 0.11 ± 0.02 Hz) and evoked AMPA currents (control: EC50 8.3 ± 0.5 μM; copper: EC50 2.9 ± 0.2 μM). Moreover, our results suggest that copper increases GluA1 subunit levels of the AMPA receptor through the anchorage of AMPA receptors to the plasma membrane as a result of PSD-95 accumulation. We also found that copper-treated neurons displayed an undistinguishable neurotransmission to control neurons after 24 h of treatment, indicating that changes in neurotransmission induced by copper at 3 h of incubation are homeostatically regulated after long-term exposure to the metal. Together, our data reveal an unexpected biphasic effect of copper on neurotransmission, which may be relevant to understand the effects of this ion in brain diseases that display copper dyshomeostasis such as that observed in Alzheimer's disease (AD).
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Affiliation(s)
- Christian Peters
- Laboratorio de Neurobiometales Departamento de Fisiología, Facultad de Ciencias Biológicas, Universidad de Concepción, Chile
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Cuevas ME, Haensgen H, Sepúlveda FJ, Zegers G, Roa J, Opazo C, Aguayo LG. Soluble Aβ1-40 Peptide Increases Excitatory Neurotransmission and Induces Epileptiform Activity in Hippocampal Neurons. ACTA ACUST UNITED AC 2011; 23:673-87. [DOI: 10.3233/jad-2011-091717] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Affiliation(s)
- Magdalena E. Cuevas
- Laboratory of Neurophysiology, Department of Physiology, University of Concepción, Concepción, Chile
| | - Henny Haensgen
- Laboratory of Neurophysiology, Department of Physiology, University of Concepción, Concepción, Chile
| | - Fernando J. Sepúlveda
- Laboratory of Neurophysiology, Department of Physiology, University of Concepción, Concepción, Chile
- Centro de Investigación Avanzada en Educación, University of Concepción, Concepción, Chile
| | - Gabriela Zegers
- Laboratory of Neurophysiology, Department of Physiology, University of Concepción, Concepción, Chile
| | - Jorge Roa
- Laboratory of Neurobiometals, Department of Physiology, University of Concepción, Concepción, Chile
| | - Carlos Opazo
- Laboratory of Neurobiometals, Department of Physiology, University of Concepción, Concepción, Chile
| | - Luis G. Aguayo
- Laboratory of Neurophysiology, Department of Physiology, University of Concepción, Concepción, Chile
- Centro de Investigación Avanzada en Educación, University of Concepción, Concepción, Chile
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Avila ME, Sepúlveda FJ, Burgos CF, Moraga-Cid G, Parodi J, Moon RT, Aguayo LG, Opazo C, De Ferrari GV. Canonical Wnt3a modulates intracellular calcium and enhances excitatory neurotransmission in hippocampal neurons. J Biol Chem 2010; 285:18939-47. [PMID: 20404321 PMCID: PMC2881816 DOI: 10.1074/jbc.m110.103028] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2010] [Revised: 04/16/2010] [Indexed: 11/06/2022] Open
Abstract
A role for Wnt signal transduction in the development and maintenance of brain structures is widely acknowledged. Recent studies have suggested that Wnt signaling may be essential for synaptic plasticity and neurotransmission. However, the direct effect of a Wnt protein on synaptic transmission had not been demonstrated. Here we show that nanomolar concentrations of purified Wnt3a protein rapidly increase the frequency of miniature excitatory synaptic currents in embryonic rat hippocampal neurons through a mechanism involving a fast influx of calcium from the extracellular space, induction of post-translational modifications on the machinery involved in vesicle exocytosis in the presynaptic terminal leading to spontaneous Ca(2+) transients. Our results identify the Wnt3a protein and a member of its complex receptor at the membrane, the low density lipoprotein receptor-related protein 6 (LRP6) coreceptor, as key molecules in neurotransmission modulation and suggest cross-talk between canonical and Wnt/Ca(2+) signaling in central neurons.
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Affiliation(s)
- Miguel E. Avila
- From the Departments of Biochemistry and Molecular Biology and
| | - Fernando J. Sepúlveda
- Physiology, Faculty of Biological Sciences, Universidad de Concepción, Concepción P.O. Box 4070386, Chile
| | | | - Gustavo Moraga-Cid
- Physiology, Faculty of Biological Sciences, Universidad de Concepción, Concepción P.O. Box 4070386, Chile
| | - Jorge Parodi
- Physiology, Faculty of Biological Sciences, Universidad de Concepción, Concepción P.O. Box 4070386, Chile
| | - Randall T. Moon
- Howard Hughes Medical Institute, Department of Pharmacology and Institute for Stem Cell and Regenerative Medicine, University of Washington School of Medicine, Seattle, Washington 98195, and
| | - Luis G. Aguayo
- Physiology, Faculty of Biological Sciences, Universidad de Concepción, Concepción P.O. Box 4070386, Chile
| | - Carlos Opazo
- Physiology, Faculty of Biological Sciences, Universidad de Concepción, Concepción P.O. Box 4070386, Chile
| | - Giancarlo V. De Ferrari
- From the Departments of Biochemistry and Molecular Biology and
- the Center for Biomedical Research, Faculty of Biological Sciences and Faculty of Medicine, Universidad Andrés Bello, Santiago P.O. Box 8370134, Chile
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Parodi J, Sepúlveda FJ, Roa J, Opazo C, Inestrosa NC, Aguayo LG. Beta-amyloid causes depletion of synaptic vesicles leading to neurotransmission failure. J Biol Chem 2009; 285:2506-14. [PMID: 19915004 DOI: 10.1074/jbc.m109.030023] [Citation(s) in RCA: 131] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Alzheimer disease is a progressive neurodegenerative brain disorder that leads to major debilitating cognitive deficits. It is believed that the alterations capable of causing brain circuitry dysfunctions have a slow onset and that the full blown disease may take several years to develop. Therefore, it is important to understand the early, asymptomatic, and possible reversible states of the disease with the aim of proposing preventive and disease-modifying therapeutic strategies. It is largely unknown how amyloid beta-peptide (A beta), a principal agent in Alzheimer disease, affects synapses in brain neurons. In this study, we found that similar to other pore-forming neurotoxins, A beta induced a rapid increase in intracellular calcium and miniature currents, indicating an enhancement in vesicular transmitter release. Significantly, blockade of these effects by low extracellular calcium and a peptide known to act as an inhibitor of the A beta-induced pore prevented the delayed failure, indicating that A beta blocks neurotransmission by causing vesicular depletion. This new mechanism for A beta synaptic toxicity should provide an alternative pathway to search for small molecules that can antagonize these effects of A beta.
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Affiliation(s)
- Jorge Parodi
- Laboratory of Neurophysiology, Department of Physiology, University of Concepción, Edmundo Larenas S/N, P.O. Box 160-C, Concepción, Chile
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Sepúlveda FJ, Opazo C, Aguayo LG. Alzheimer beta-amyloid blocks epileptiform activity in hippocampal neurons. Mol Cell Neurosci 2009; 41:420-8. [PMID: 19427381 DOI: 10.1016/j.mcn.2009.04.012] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2008] [Revised: 04/21/2009] [Accepted: 04/22/2009] [Indexed: 10/20/2022] Open
Abstract
Several studies showed that hippocampal neurons respond with an increase in synaptic transmission after chronic blockade of GABA(A) receptors with bicuculline, a neuroplastic phenomenon likely associated to epileptiform states. Here, we tested the effect of Abeta(1-40) oligomers/aggregates, believed to be involved in Alzheimer's Disease (AD) genesis, on this type of synaptic plasticity. In the presence of bicuculline, the frequency of miniature currents increased from 1.2+/-0.4 Hz to 3.1+/-0.6 Hz (n=6, p<0.05). Similarly, current amplitude increased from 45+/-3 pA to 81+/-11 pA (n=5, p<0.05). These effects were completely inhibited in the presence of Abeta(1-40) aggregates. Data suggest that Abeta aggregates exert their influence principally by blocking synaptic transmission and altering the transcriptional pathway associated with CREB-p. In conclusion, neurons exposed to aggregated Abeta(1-40) showed a reduced level of neuronal plasticity and this suggests that they might be acting as anti-epileptiform modulators.
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Affiliation(s)
- Fernando J Sepúlveda
- Laboratory of Neurophysiology, Department of Physiology, University of Concepción, Chile
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