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Dalmaso B, Liber AMP, Ventura DF, Jancar S, Del Debbio CB. Platelet-activating factor receptor (PAFR) regulates neuronal maturation and synaptic transmission during postnatal retinal development. Front Cell Neurosci 2024; 18:1343745. [PMID: 38572071 PMCID: PMC10988781 DOI: 10.3389/fncel.2024.1343745] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2023] [Accepted: 02/19/2024] [Indexed: 04/05/2024] Open
Abstract
Introduction Platelet-activating factor (PAF), PAF receptor (PAFR), and PAF- synthesis/degradation systems are involved in essential CNS processes such as neuroblast proliferation, differentiation, migration, and synaptic modulation. The retina is an important central nervous system (CNS) tissue for visual information processing. During retinal development, the balance between Retinal Progenitor Cell (RPC) proliferation and differentiation is crucial for proper cell determination and retinogenesis. Despite its importance in retinal development, the effects of PAFR deletion on RPC dynamics are still unknown. Methods We compared PAFR knockout mice (PAFR-/-) retinal postnatal development proliferation and differentiation aspects with control animals. Electrophysiological responses were analyzed by electroretinography (ERG). Results and discussion In this study, we demonstrate that PAFR-/- mice increased proliferation during postnatal retinogenesis and altered the expression of specific differentiation markers. The retinas of postnatal PAFR-/- animals decreased neuronal differentiation and synaptic transmission markers, leading to differential responses to light stimuli measured by ERG. Our findings suggest that PAFR signaling plays a critical role in regulating postnatal RPC cell differentiation dynamics during retinal development, cell organization, and neuronal circuitry formation.
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Affiliation(s)
- Barbara Dalmaso
- Department of Cell and Developmental Biology, Biomedical Sciences Institute, University of São Paulo (ICB-USP), São Paulo, Brazil
| | - Andre Mauricio Passos Liber
- Université Paris-Saclay, CNRS, Institut des Neurosciences Paris-Saclay, Saclay, France
- Department of Experimental Psychology, Institute of Psychology, University of São Paulo (IP-USP), São Paulo, Brazil
| | - Dora Fix Ventura
- Department of Experimental Psychology, Institute of Psychology, University of São Paulo (IP-USP), São Paulo, Brazil
| | - Sonia Jancar
- Department of Immunology, Biomedical Sciences Institute, University of São Paulo (ICB-USP), São Paulo, Brazil
| | - Carolina Beltrame Del Debbio
- Department of Cell and Developmental Biology, Biomedical Sciences Institute, University of São Paulo (ICB-USP), São Paulo, Brazil
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Gene Expression Profile in Different Age Groups and Its Association with Cognitive Function in Healthy Malay Adults in Malaysia. Cells 2021; 10:cells10071611. [PMID: 34199148 PMCID: PMC8304476 DOI: 10.3390/cells10071611] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2021] [Revised: 06/13/2021] [Accepted: 06/21/2021] [Indexed: 11/16/2022] Open
Abstract
The mechanism of cognitive aging at the molecular level is complex and not well understood. Growing evidence suggests that cognitive differences might also be caused by ethnicity. Thus, this study aims to determine the gene expression changes associated with age-related cognitive decline among Malay adults in Malaysia. A cross-sectional study was conducted on 160 healthy Malay subjects, aged between 28 and 79, and recruited around Selangor and Klang Valley, Malaysia. Gene expression analysis was performed using a HumanHT-12v4.0 Expression BeadChip microarray kit. The top 20 differentially expressed genes at p < 0.05 and fold change (FC) = 1.2 showed that PAFAH1B3, HIST1H1E, KCNA3, TM7SF2, RGS1, and TGFBRAP1 were regulated with increased age. The gene set analysis suggests that the Malay adult's susceptibility to developing age-related cognitive decline might be due to the changes in gene expression patterns associated with inflammation, signal transduction, and metabolic pathway in the genetic network. It may, perhaps, have important implications for finding a biomarker for cognitive decline and offer molecular targets to achieve successful aging, mainly in the Malay population in Malaysia.
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Dalmaso B, da Silva-Junior IA, Fragel-Madeira L, Jancar S, Del Debbio CB. Platelet activating factor in the eye: Physiological roles, diseases and future perspectives. Prostaglandins Other Lipid Mediat 2020; 153:106522. [PMID: 33358892 DOI: 10.1016/j.prostaglandins.2020.106522] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Revised: 12/03/2020] [Accepted: 12/18/2020] [Indexed: 01/09/2023]
Abstract
Platelet Activating Factor (PAF) is a known phospholipid mediator of inflammation. Since its first description in 1972, it has emerged as a key regulator of vital cellular signaling functions, as proliferation, cell adhesion, and apoptosis. Evidence suggests that interactions between PAF and its receptor (PAFR) play a critical role in nervous system tissues, including the retina. The retina is a very important constituent of the visual system, along with the cornea, sclera, choroid, iris, and ciliary body, that acts synergistically to provide vision and to maintain optical homeostasis. There is evidence that PAF may regulate a wide range of physiological functions in the visual system tissues, such as eye development, inflammation, epithelial wound healing, and synapsis. Due to their multiple functions, PAF and PAFR also have important pathological and clinical implications in ocular disorders such as Choroidal Neovascularization (CNV), Age Macular Degeneration, (AMD), Diabetic Retinopathy (DR), transplant responses, and pharmacological interactions. Studies with PAFR antagonists have shown promising results such as inhibition of neovascularization and chloroquine-induced retinopathies, as well as reducing inflammation and retinal cell death. Due to the importance of PAFR signaling in the visual system and ophthalmology research, this review aims to provide a general overview of current and future perspectives about PAF in eye biology.
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Affiliation(s)
- Barbara Dalmaso
- Department of Cell and Developmental Biology, Biomedical Sciences Institute, University of Sao Paulo, São Paulo, Brazil
| | | | - Lucianne Fragel-Madeira
- Department of Neurobiology, Institute of Biology, Fluminense Federal University, Rio de Janeiro, Brazil
| | - Sonia Jancar
- Department of Immunology, Biomedical Sciences Institute, University of Sao Paulo, São Paulo, Brazil
| | - Carolina Beltrame Del Debbio
- Department of Cell and Developmental Biology, Biomedical Sciences Institute, University of Sao Paulo, São Paulo, Brazil.
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Di Miceli M, Bosch-Bouju C, Layé S. PUFA and their derivatives in neurotransmission and synapses: a new hallmark of synaptopathies. Proc Nutr Soc 2020; 79:1-16. [PMID: 32299516 DOI: 10.1017/s0029665120000129] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
PUFA of the n-3 and n-6 families are present in high concentration in the brain where they are major components of cell membranes. The main forms found in the brain are DHA (22 :6, n-3) and arachidonic acid (20:4, n-6). In the past century, several studies pinpointed that modifications of n-3 and n-6 PUFA levels in the brain through dietary supply or genetic means are linked to the alterations of synaptic function. Yet, synaptopathies emerge as a common characteristic of neurodevelopmental disorders, neuropsychiatric diseases and some neurodegenerative diseases. Understanding the mechanisms of action underlying the activity of PUFA at the level of synapses is thus of high interest. In this frame, dietary supplementation in PUFA aiming at restoring or promoting the optimal function of synapses appears as a promising strategy to treat synaptopathies. This paper reviews the link between dietary PUFA, synapse formation and the role of PUFA and their metabolites in synaptic functions.
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Affiliation(s)
- Mathieu Di Miceli
- INRAE, University of Bordeaux, Bordeaux INP, NutriNeuro, UMR 1286, F-33000, Bordeaux, France
| | - Clémentine Bosch-Bouju
- INRAE, University of Bordeaux, Bordeaux INP, NutriNeuro, UMR 1286, F-33000, Bordeaux, France
| | - Sophie Layé
- INRAE, University of Bordeaux, Bordeaux INP, NutriNeuro, UMR 1286, F-33000, Bordeaux, France
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Sanfeliu A, Hokamp K, Gill M, Tropea D. Transcriptomic Analysis of Mecp2 Mutant Mice Reveals Differentially Expressed Genes and Altered Mechanisms in Both Blood and Brain. Front Psychiatry 2019; 10:278. [PMID: 31110484 PMCID: PMC6501143 DOI: 10.3389/fpsyt.2019.00278] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/07/2019] [Accepted: 04/11/2019] [Indexed: 12/11/2022] Open
Abstract
Rett syndrome is a rare neuropsychiatric disorder with a wide symptomatology including impaired communication and movement, cardio-respiratory abnormalities, and seizures. The clinical presentation is typically associated to mutations in the gene coding for the methyl-CpG-binding protein 2 (MECP2), which is a transcription factor. The gene is ubiquitously present in all the cells of the organism with a peak of expression in neurons. For this reason, most of the studies in Rett models have been performed in brain. However, some of the symptoms of Rett are linked to the peripheral expression of MECP2, suggesting that the effects of the mutations affect gene expression levels in tissues other than the brain. We used RNA sequencing in Mecp2 mutant mice and matched controls, to identify common genes and pathways differentially regulated across different tissues. We performed our study in brain and peripheral blood, and we identified differentially expressed genes (DEGs) and pathways in each tissue. Then, we compared the genes and mechanisms identified in each preparation. We found that some genes and molecular pathways that are differentially expressed in brain are also differentially expressed in blood of Mecp2 mutant mice at a symptomatic-but not presymptomatic-stage. This is the case for the gene Ube2v1, linked to ubiquitination system, and Serpin1, involved in complement and coagulation cascades. Analysis of biological functions in the brain shows the enrichment of mechanisms correlated to circadian rhythms, while in the blood are enriched the mechanisms of response to stimulus-including immune response. Some mechanisms are enriched in both preparations, such as lipid metabolism and response to stress. These results suggest that analysis of peripheral blood can reveal ubiquitous altered molecular mechanisms of Rett and have applications in diagnosis and treatments' assessments.
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Affiliation(s)
- Albert Sanfeliu
- Neuropsychiatric Genetics, Department of Psychiatry, School of Medicine, Trinity Translational Medicine Institute, St James Hospital, Dublin, Ireland
| | - Karsten Hokamp
- Department of Genetics, School of Genetics and Microbiology, Smurfit Institute of Genetics, Trinity College Dublin, Dublin, Ireland
| | - Michael Gill
- Neuropsychiatric Genetics, Department of Psychiatry, School of Medicine, Trinity Translational Medicine Institute, St James Hospital, Dublin, Ireland
| | - Daniela Tropea
- Neuropsychiatric Genetics, Department of Psychiatry, School of Medicine, Trinity Translational Medicine Institute, St James Hospital, Dublin, Ireland
- Department of Psychiatry, School of Medicine, Trinity College Institute for Neuroscience, Trinity College Dublin, Dublin, Ireland
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Osborne C, West E, Bate C. The phospholipase A 2 pathway controls a synaptic cholesterol ester cycle and synapse damage. J Cell Sci 2018; 131:jcs.211789. [PMID: 29588394 DOI: 10.1242/jcs.211789] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2017] [Accepted: 03/19/2018] [Indexed: 11/20/2022] Open
Abstract
The cellular prion protein (PrPC) acts as a scaffold protein that organises signalling complexes. In synaptosomes, the aggregation of PrPC by amyloid-β (Aβ) oligomers attracts and activates cytoplasmic phospholipase A2 (cPLA2), leading to synapse degeneration. The signalling platform is dependent on cholesterol released from cholesterol esters by cholesterol ester hydrolases (CEHs). The activation of cPLA2 requires cholesterol released from cholesterol esters by cholesterol ester hydrolases (CEHs), enzymes dependent upon platelet activating factor (PAF) released by activated cPLA2 This demonstrates a positive feedback system in which activated cPLA2 increased cholesterol concentrations, which in turn facilitated cPLA2 activation. PAF was also required for the incorporation of the tyrosine kinase Fyn and cyclooxygenase (COX)-2 into Aβ-PrPC-cPLA2 complexes. As a failure to deactivate signalling complexes can lead to pathology, the mechanisms involved in their dispersal were studied. PAF facilitated the incorporation of acyl-coenzyme A:cholesterol acyltransferase (ACAT)-1 into Aβ-PrPC-cPLA2-COX-2-Fyn complexes. The esterification of cholesterol reduced cholesterol concentrations, causing dispersal of Aβ-PrPC-cPLA2-COX-2-Fyn complexes and the cessation of signalling. This study identifies PAF as a key mediator regulating the cholesterol ester cycle, activation of cPLA2 and COX-2 within synapses, and synapse damage.
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Affiliation(s)
- Craig Osborne
- Department of Pathology and Pathogen Biology, Royal Veterinary College, Hawkshead Lane, North Mymms, Hatfield, UK AL9 7TA
| | - Ewan West
- Department of Pathology and Pathogen Biology, Royal Veterinary College, Hawkshead Lane, North Mymms, Hatfield, UK AL9 7TA
| | - Clive Bate
- Department of Pathology and Pathogen Biology, Royal Veterinary College, Hawkshead Lane, North Mymms, Hatfield, UK AL9 7TA
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Dorninger F, Forss-Petter S, Berger J. From peroxisomal disorders to common neurodegenerative diseases - the role of ether phospholipids in the nervous system. FEBS Lett 2017; 591:2761-2788. [PMID: 28796901 DOI: 10.1002/1873-3468.12788] [Citation(s) in RCA: 79] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2017] [Revised: 07/26/2017] [Accepted: 08/07/2017] [Indexed: 01/01/2023]
Abstract
The emerging diverse roles of ether (phospho)lipids in nervous system development and function in health and disease are currently attracting growing interest. Plasmalogens, a subgroup of ether lipids, are important membrane components involved in vesicle fusion and membrane raft composition. They store polyunsaturated fatty acids and may serve as antioxidants. Ether lipid metabolites act as precursors for the formation of glycosyl-phosphatidyl-inositol anchors; others, like platelet-activating factor, are implicated in signaling functions. Consolidating the available information, we attempt to provide molecular explanations for the dramatic neurological phenotype in ether lipid-deficient human patients and mice by linking individual functional properties of ether lipids with pathological features. Furthermore, recent publications have identified altered ether lipid levels in the context of many acquired neurological disorders including Alzheimer's disease (AD) and autism. Finally, current efforts to restore ether lipids in peroxisomal disorders as well as AD are critically reviewed.
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Affiliation(s)
- Fabian Dorninger
- Department of Pathobiology of the Nervous System, Center for Brain Research, Medical University of Vienna, Austria
| | - Sonja Forss-Petter
- Department of Pathobiology of the Nervous System, Center for Brain Research, Medical University of Vienna, Austria
| | - Johannes Berger
- Department of Pathobiology of the Nervous System, Center for Brain Research, Medical University of Vienna, Austria
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Lee D, Kim E, Tanaka-Yamamoto K. Diacylglycerol Kinases in the Coordination of Synaptic Plasticity. Front Cell Dev Biol 2016; 4:92. [PMID: 27630986 PMCID: PMC5005321 DOI: 10.3389/fcell.2016.00092] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2016] [Accepted: 08/17/2016] [Indexed: 01/07/2023] Open
Abstract
Synaptic plasticity is activity-dependent modification of the efficacy of synaptic transmission. Although, detailed mechanisms underlying synaptic plasticity are diverse and vary at different types of synapses, diacylglycerol (DAG)-associated signaling has been considered as an important regulator of many forms of synaptic plasticity, including long-term potentiation (LTP) and long-term depression (LTD). Recent evidences indicate that DAG kinases (DGKs), which phosphorylate DAG to phosphatidic acid to terminate DAG signaling, are important regulators of LTP and LTD, as supported by the results from mice lacking specific DGK isoforms. This review will summarize these studies and discuss how specific DGK isoforms distinctly regulate different forms of synaptic plasticity at pre- and postsynaptic sites. In addition, we propose a general role of DGKs as coordinators of synaptic plasticity that make local synaptic environments more permissive for synaptic plasticity by regulating DAG concentration and interacting with other synaptic proteins.
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Affiliation(s)
- Dongwon Lee
- Center for Synaptic Brain Dysfunctions, Institute for Basic Science Daejeon, South Korea
| | - Eunjoon Kim
- Center for Synaptic Brain Dysfunctions, Institute for Basic ScienceDaejeon, South Korea; Department of Biological Sciences, Korea Advanced Institute of Science and TechnologyDaejeon, South Korea
| | - Keiko Tanaka-Yamamoto
- Center for Functional Connectomics, Korea Institute of Science and Technology Seoul, South Korea
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9
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Musto AE, Rosencrans RF, Walker CP, Bhattacharjee S, Raulji CM, Belayev L, Fang Z, Gordon WC, Bazan NG. Dysfunctional epileptic neuronal circuits and dysmorphic dendritic spines are mitigated by platelet-activating factor receptor antagonism. Sci Rep 2016; 6:30298. [PMID: 27444269 PMCID: PMC4957208 DOI: 10.1038/srep30298] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2015] [Accepted: 06/30/2016] [Indexed: 01/28/2023] Open
Abstract
Temporal lobe epilepsy or limbic epilepsy lacks effective therapies due to a void in understanding the cellular and molecular mechanisms that set in motion aberrant neuronal network formations during the course of limbic epileptogenesis (LE). Here we show in in vivo rodent models of LE that the phospholipid mediator platelet-activating factor (PAF) increases in LE and that PAF receptor (PAF-r) ablation mitigates its progression. Synthetic PAF-r antagonists, when administered intraperitoneally in LE, re-establish hippocampal dendritic spine density and prevent formation of dysmorphic dendritic spines. Concomitantly, hippocampal interictal spikes, aberrant oscillations, and neuronal hyper-excitability, evaluated 15–16 weeks after LE using multi-array silicon probe electrodes implanted in the dorsal hippocampus, are reduced in PAF-r antagonist-treated mice. We suggest that over-activation of PAF-r signaling induces aberrant neuronal plasticity in LE and leads to chronic dysfunctional neuronal circuitry that mediates epilepsy.
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Affiliation(s)
- Alberto E Musto
- Neuroscience Center of Excellence, Louisiana State University Health Sciences Center, 2020 Gravier Street, New Orleans, Louisiana 70112, USA
| | - Robert F Rosencrans
- Neuroscience Center of Excellence, Louisiana State University Health Sciences Center, 2020 Gravier Street, New Orleans, Louisiana 70112, USA
| | - Chelsey P Walker
- Neuroscience Center of Excellence, Louisiana State University Health Sciences Center, 2020 Gravier Street, New Orleans, Louisiana 70112, USA
| | - Surjyadipta Bhattacharjee
- Neuroscience Center of Excellence, Louisiana State University Health Sciences Center, 2020 Gravier Street, New Orleans, Louisiana 70112, USA
| | - Chittalsinh M Raulji
- Neuroscience Center of Excellence, Louisiana State University Health Sciences Center, 2020 Gravier Street, New Orleans, Louisiana 70112, USA.,Department of Pediatrics, Hematology-Oncology, Louisiana State University Health Sciences Center and Children's Hospital of New Orleans, New Orleans, Louisiana 70118, USA
| | - Ludmila Belayev
- Neuroscience Center of Excellence, Louisiana State University Health Sciences Center, 2020 Gravier Street, New Orleans, Louisiana 70112, USA
| | - Zhide Fang
- Biostatistics, School of Public Health, Louisiana State University Health Sciences Center, 2020 Gravier Street, New Orleans, Louisiana 70112, USA
| | - William C Gordon
- Neuroscience Center of Excellence, Louisiana State University Health Sciences Center, 2020 Gravier Street, New Orleans, Louisiana 70112, USA
| | - Nicolas G Bazan
- Neuroscience Center of Excellence, Louisiana State University Health Sciences Center, 2020 Gravier Street, New Orleans, Louisiana 70112, USA
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Reiner B, Wang W, Liu J, Xiong H. Platelet-activating factor attenuation of long-term potentiation in rat hippocampal slices via protein tyrosine kinase signaling. Neurosci Lett 2016; 615:83-7. [PMID: 26808643 DOI: 10.1016/j.neulet.2016.01.033] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2015] [Revised: 01/13/2016] [Accepted: 01/19/2016] [Indexed: 02/08/2023]
Abstract
It is well established that HIV-1-infected mononuclear phagocytes release platelet activating factor (PAF) and elevated levels of PAF have been detected in blood and in the cerebrospinal fluid (CSF) of acquired immunodeficiency syndrome (AIDS) patients with HIV-associated neurocognitive disorders (HAND). It is our hypothesis that the elevated levels of PAF alter long-term potentiation (LTP) in the hippocampus, leading to neurocognitive dysfunction. To test this hypothesis, we studied the effects of PAF on LTP in the CA1 region of rat hippocampal slices. Our results showed incubation of hippocampal slices with PAF attenuated LTP. The PAF-mediated attenuation was blocked by ginkgolide B, a PAF receptor antagonist, suggesting PAF attenuation of LTP via PAF receptors. Application of lyso-PAF, an inactive PAF analog, had no apparent effect on LTP. Further investigation revealed an involvement of tyrosine kinase in PAF attenuation of LTP, which was demonstrated by lavendustin A (a specific protein tyrosine kinase inhibitor) blockage of PAF attenuation of LTP. As LTP is widely considered as the cellular and synaptic basis for learning and memory, the attenuation of LTP by PAF may contribute at least in part to the HAND pathogenesis.
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Affiliation(s)
- Benjamin Reiner
- The Neurophysiology Laboratory, Department of Pharmacology and Experimental Neuroscience, University of Nebraska Medical Center, Omaha, NE 68198-5880, USA; Department of Biology, West Chester University of Pennsylvania, West Chester, PA 19383, USA
| | - Wenwei Wang
- The Neurophysiology Laboratory, Department of Pharmacology and Experimental Neuroscience, University of Nebraska Medical Center, Omaha, NE 68198-5880, USA; Department of Physiology, Fudan University School of Medicine, Shanghai, China
| | - Jianuo Liu
- The Neurophysiology Laboratory, Department of Pharmacology and Experimental Neuroscience, University of Nebraska Medical Center, Omaha, NE 68198-5880, USA
| | - Huangui Xiong
- The Neurophysiology Laboratory, Department of Pharmacology and Experimental Neuroscience, University of Nebraska Medical Center, Omaha, NE 68198-5880, USA.
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Prakash A, Kalra J, Mani V, Ramasamy K, Majeed ABA. Pharmacological approaches for Alzheimer’s disease: neurotransmitter as drug targets. Expert Rev Neurother 2014; 15:53-71. [DOI: 10.1586/14737175.2015.988709] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
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12
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Mazereeuw G, Herrmann N, Bennett SAL, Swardfager W, Xu H, Valenzuela N, Fai S, Lanctôt KL. Platelet activating factors in depression and coronary artery disease: a potential biomarker related to inflammatory mechanisms and neurodegeneration. Neurosci Biobehav Rev 2013; 37:1611-21. [PMID: 23800745 DOI: 10.1016/j.neubiorev.2013.06.010] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2013] [Revised: 05/07/2013] [Accepted: 06/13/2013] [Indexed: 02/02/2023]
Abstract
The persistence of a depressive episode in coronary artery disease (CAD) patients not only heightens the risk of acute ischemic events, but it is also associated with accelerated cognitive decline. Antidepressant interventions for depression in CAD have only modest effects and novel approaches are limited by a poor understanding of etiological mechanisms. This review proposes that the platelet activating factor (PAF) family of lipids might be associated with the persistence of a depressive episode and related neurodegenerative pathology in CAD due to their association with leading etiological mechanisms for depression in CAD such as inflammation, oxidative and nitrosative stress, vascular endothelial dysfunction, and platelet reactivity. The evidence implicating PAFs in CAD, vascular pathology, and neurodegenerative processes is also presented. We also propose future directions for the investigation of PAFs as mediators of persistent depression. In summary, PAFs are implicated in leading mechanisms associated with depression in CAD. PAFs may therefore be associated with the persistence of depression in CAD and related to neurodegenerative and cognitive sequelae.
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Affiliation(s)
- Graham Mazereeuw
- Sunnybrook Research Institute, Toronto, Ontario, Canada; Department of Pharmacology and Toxicology, University of Toronto, Toronto, Ontario, Canada; Neural Regeneration Laboratory, Ottawa Institute of Systems Biology, Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Ontario, Canada; CIHR Training Program in Neurodegenerative Lipidomics, Canada
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13
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Sirangelo I, Irace G, Balestrieri ML. Amyloid toxicity and platelet-activating factor signaling. J Cell Physiol 2013; 228:1143-8. [DOI: 10.1002/jcp.24284] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2012] [Accepted: 11/07/2012] [Indexed: 01/08/2023]
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Frisardi V, Panza F, Seripa D, Farooqui T, Farooqui AA. Glycerophospholipids and glycerophospholipid-derived lipid mediators: A complex meshwork in Alzheimer’s disease pathology. Prog Lipid Res 2011; 50:313-30. [DOI: 10.1016/j.plipres.2011.06.001] [Citation(s) in RCA: 112] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2011] [Revised: 06/09/2011] [Accepted: 06/09/2011] [Indexed: 10/18/2022]
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Suzuki E, Sato M, Takezawa R, Usuki T, Okada T. The facilitative effects of bilobalide, a unique constituent of Ginkgo biloba, on synaptic transmission and plasticity in hippocampal subfields. J Physiol Sci 2011; 61:421-7. [PMID: 21710296 PMCID: PMC10717362 DOI: 10.1007/s12576-011-0159-6] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2010] [Accepted: 06/13/2011] [Indexed: 10/18/2022]
Abstract
Bilobalide, a unique constituent of Ginkgo biloba, has been reported to potentiate population spikes in hippocampal CA1 pyramidal cells and to protect the brain against cell death. In this study, the effects of bilobalide on synaptic transmission and its plasticity in rat hippocampal subfields were electrophysiologically investigated. Bilobalide (50 μM) significantly potentiated the input-output relationship at Schaffer collateral (SC)-CA1 synapses but not at medial perforant path (MPP)-dentate gyrus (DG), lateral perforant path (LPP)-DG, or mossy fiber (MF)-CA3 synapses. Facilitative effects of bilobalide on synaptic plasticity were only observed at MPP-DG synapses, in which the induction of long-term depression was blocked in the presence of bilobalide. However, no effect on synaptic plasticity was observed at SC-CA1 synapses. These results suggest that bilobalide has differential effects on synaptic efficacy in each hippocampal subfield.
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Affiliation(s)
- Etsuko Suzuki
- Department of Psychology, Faculty of Human Sciences, Sophia University, 7-1 Kioi-cho, Chiyoda-ku, Tokyo, 102-8554 Japan
| | - Makiko Sato
- Department of Materials and Life Sciences, Faculty of Science and Technology, Sophia University, 7-1 Kioi-cho, Chiyoda-ku, Tokyo, 102-8554 Japan
| | - Ryota Takezawa
- Department of Materials and Life Sciences, Faculty of Science and Technology, Sophia University, 7-1 Kioi-cho, Chiyoda-ku, Tokyo, 102-8554 Japan
| | - Toyonobu Usuki
- Department of Materials and Life Sciences, Faculty of Science and Technology, Sophia University, 7-1 Kioi-cho, Chiyoda-ku, Tokyo, 102-8554 Japan
| | - Takashi Okada
- Department of Psychology, Faculty of Human Sciences, Sophia University, 7-1 Kioi-cho, Chiyoda-ku, Tokyo, 102-8554 Japan
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Musto AE, Samii M. Platelet-activating factor receptor antagonism targets neuroinflammation in experimental epilepsy. Epilepsia 2011; 52:551-61. [PMID: 21204830 DOI: 10.1111/j.1528-1167.2010.02920.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
PURPOSE Temporal lobe epilepsy is associated with the inflammatory process related to the basic mechanisms that lead to seizure susceptibility and brain damage. Platelet-activating factor (PAF), a potent, short-lived phospholipid mediator of inflammation, participates in physiologic signaling in the brain. However, after seizures, PAF accumulates in the brain and activates intracellular signaling related with inflammation-mediated excitotoxicity and hippocampal hyperexcitability. The objective of this study is to evaluate the effect of PAF antagonism on hippocampal hyperexcitability, seizure susceptibility, and neuroprotection using the kindling paradigm and pilocarpine-induced seizure damage models. METHODS The PAF antagonist, LAU-0901 (60 mg/kg, i.p.), or vehicle, was administrated each day of kindling or daily during the 4 weeks after status epilepticus (SE). We analyzed seizure severity, electrical activity, cellular damage, and inflammation in the hippocampi of both treated groups. KEY FINDINGS LAU-0901 limits the progression of kindling and attenuates seizure susceptibility 1 week after the kindling procedure. In addition, under the seizure-damage conditions studied here, we observed that LAU-0901 induces hippocampal neuroprotection and limits somatostatin interneuronal cell loss and inflammation. SIGNIFICANCE Our results indicate that modulation of PAF overactivity attenuates seizure susceptibility, hippocampal hyperexcitability, and neuroinflammation.
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Affiliation(s)
- Alberto E Musto
- Neuroscience Center of Excellence, Louisiana State University Health Sciences Center, School of Medicine, New Orleans, Louisiana 70112, USA.
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Moriguchi S, Shioda N, Yamamoto Y, Fukunaga K. Platelet-activating factor-induced synaptic facilitation is associated with increased calcium/calmodulin-dependent protein kinase II, protein kinase C and extracellular signal-regulated kinase activities in the rat hippocampal CA1 region. Neuroscience 2010; 166:1158-66. [PMID: 20074623 DOI: 10.1016/j.neuroscience.2010.01.008] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2009] [Revised: 01/05/2010] [Accepted: 01/05/2010] [Indexed: 12/01/2022]
Abstract
Platelet-activating factor (PAF) is an important inflammatory lipid mediator affecting neural plasticity. In the present study, we demonstrated how PAF affects synaptic efficacy through activation of protein kinases in the rat hippocampal CA1 region. In cultured hippocampal neurons, 10 to 1000 nM PAF stimulated autophosphorylation of calcium/calmodulin-dependent protein kinase II (CaMKII) and phosphorylation of synapsin I and myristoylated alanine-rich protein kinase C substrate (MARCKS). In hippocampal CA1 slices, field excitatory postsynaptic potentials (fEPSPs) induced by stimulation of the Schaffer collateral/commissural pathways were significantly increased 10-50 min after exposure to 100 to 1000 nM PAF. Immunoblotting analysis showed that 100 nM PAF treatment for 10 or 50 min significantly and persistently increased CaMKII autophosphorylation in the hippocampal CA1 region. Increased protein kinase Calpha (PKCalpha) autophosphorylation was also seen at the same time point after PAF exposure. By contrast, extracellular signal-regulated kinase (ERK) phosphorylation was slightly but significantly increased at 10 min after PAF exposure. Consistent with increased CaMKII autophosphorylation, AMPA-type glutamate receptor subunit 1 (GluR1) (Ser-831) phosphorylation as a CaMKII postsynaptic substrate significantly increased after 10 or 50 min of treatment, whereas synapsin I (Ser-603) phosphorylation as a presynaptic substrate increased at 10 min in the hippocampal CA1 region. Phosphorylation of MARCKS (Ser-152/156) and NMDA receptor subunit 1 (NR1) (Ser-896) as PKCalpha substrates also significantly increased after 10 min but had not further increased by 50 min in the CA1 region. Increased of fEPSPs induced by PAF treatment completely and/or partly inhibited by KN93 and/or U0126 treatment. These results suggest that PAF induces synaptic facilitation through activation of CaMKII, PKC and ERK in the hippocampal CA1 region.
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Affiliation(s)
- S Moriguchi
- Department of Pharmacology, Graduate School of Pharmaceutical Sciences, Tohoku University, Aoba-ku, Sendai, Miyagi, Japan.
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Ryan SD, Harris CS, Carswell CL, Baenziger JE, Bennett SA. Heterogeneity in the sn-1 carbon chain of platelet-activating factor glycerophospholipids determines pro- or anti-apoptotic signaling in primary neurons. J Lipid Res 2008; 49:2250-8. [DOI: 10.1194/jlr.m800263-jlr200] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
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Harayama T, Shindou H, Ogasawara R, Suwabe A, Shimizu T. Identification of a novel noninflammatory biosynthetic pathway of platelet-activating factor. J Biol Chem 2008; 283:11097-106. [PMID: 18285344 DOI: 10.1074/jbc.m708909200] [Citation(s) in RCA: 102] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Platelet-activating factor (PAF) is a potent lipid mediator playing various inflammatory and physiological roles. PAF is biosynthesized through two independent pathways called the de novo and remodeling pathways. Lyso-PAF acetyltransferase (lyso-PAF AT) was believed to biosynthesize PAF under inflammatory conditions, through the remodeling pathway. The first isolated lyso-PAF AT (LysoPAFAT/LPCAT2) had consistent properties. However, we show in this study the finding of a second lyso-PAF AT working under noninflammatory conditions. We partially purified a Ca(2+)-independent lyso-PAF AT from mouse lung. Immunoreactivity for lysophosphatidylcholine acyltransferase 1 (LPCAT1) was detected in the active fraction. Lpcat1-transfected Chinese hamster ovary cells exhibited both LPCAT and lyso-PAF AT activities. We confirmed that LPCAT1 transfers acetate from acetyl-CoA to lyso-PAF by the identification of an acetyl-CoA (and other acyl-CoAs) interacting site in LPCAT1. We further showed that LPCAT1 activity and expression are independent of inflammatory signals. Therefore, these results suggest the molecular diversity of lyso-PAF ATs is as follows: one (LysoPAFAT/LPCAT2) is inducible and activated by inflammatory stimulation, and the other (LPCAT1) is constitutively expressed. Each lyso-PAF AT biosynthesizes inflammatory and physiological amounts of PAF, depending on the cell type. These findings provide important knowledge for the understanding of the diverse pathological and physiological roles of PAF.
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Affiliation(s)
- Takeshi Harayama
- Department of Biochemistry and Molecular Biology, Faculty of Medicine, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033
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Ryan SD, Harris CS, Mo F, Lee H, Hou ST, Bazan NG, Haddad PS, Arnason JT, Bennett SAL. Platelet activating factor-induced neuronal apoptosis is initiated independently of its G-protein coupled PAF receptor and is inhibited by the benzoate orsellinic acid. J Neurochem 2007; 103:88-97. [PMID: 17877634 DOI: 10.1111/j.1471-4159.2007.04740.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The bioactive lipid mediator platelet activating factor (PAF) is recognized as a key effecter of neuronal apoptosis, yet it is not clear whether its G-protein coupled receptor (PAFR) initiates or prevents PAF neurotoxicity. Using PAFR-/- and congenic wild-type mice, we show that PAF triggers caspase-3/7 activity and neuronal death in PAFR-/- but not PAFR+/+ cerebellar granule neurons. Restoring receptor expression by recombinant adenoviral infection protected cells from PAF challenge. Neuronal death was not mediated by nitric oxide or N-methyl-d-aspartate receptor signaling given that N-nitro-l-arginine methyl ester and MK-801 did not inhibit PAF-induced neuronal loss in PAFR-/- neurons. To intervene in PAFR-independent neurotoxicity, the anti-apoptotic actions of three structurally distinct PAF antagonists were compared to a panel of plant and fungal benzoic acid derivatives. We found that the PAF antagonist BN 52021 but not FR 49175 or CV 3988 inhibited PAFR-independent neurotoxicity. Orsellinic acid, a fungal-derived benzoic acid, blocked PAF-mediated neuronal apoptosis without affecting PAFR-mediated neuroprotection. These findings demonstrate that PAF can transduce apoptotic death in primary neurons independently of its G-protein coupled receptor, that PAFR activation is neuroprotective, and that orsellinic acid effectively attenuates PAFR-independent neuronal apoptosis.
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Affiliation(s)
- Scott D Ryan
- Department of Biochemistry, Microbiology, and Immunology, Neural Regeneration Laboratory and Ottawa Institute of Systems Biology, University of Ottawa, Ottawa, Ontario, Canada
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Piccoli G, Verpelli C, Tonna N, Romorini S, Alessio M, Nairn AC, Bachi A, Sala C. Proteomic analysis of activity-dependent synaptic plasticity in hippocampal neurons. J Proteome Res 2007; 6:3203-15. [PMID: 17622166 DOI: 10.1021/pr0701308] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Following long-term treatment with bicuculline and tetrodotoxin (TTX) aimed at modifying synaptic activity in cultured neurons, we used a proteomic approach to identify the associated changes in protein expression. The neurons were left untreated, or treated with bicuculline or TTX, and fractionated by means of differential detergent extraction, after which the proteins in each fraction were separated by means of two-dimensional (2D) gel electrophoresis, and 57 proteins of interest were identified by mass spectrometry. The proteins that showed altered expression and/or post-translational modifications include proteins or enzymes involved in regulating cell and protein metabolism, the cytoskeleton, or mitochondrial activity. These results suggest that extensive alterations in neuronal protein expression take place as a result of increased or decreased synaptic activity.
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Affiliation(s)
- Giovanni Piccoli
- CNR Institute of Neuroscience and Department of Pharmacology, University of Milan, Italy
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Heusler P, Boehmer G. Platelet-activating factor contributes to the induction of long-term potentiation in the rat somatosensory cortex in vitro. Brain Res 2007; 1135:85-91. [PMID: 17196945 DOI: 10.1016/j.brainres.2006.12.016] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2006] [Revised: 12/04/2006] [Accepted: 12/07/2006] [Indexed: 11/25/2022]
Abstract
The contribution of platelet-activating factor (PAF) to the induction of neocortical LTP was examined in rat brain slices containing the primary somatosensory cortex (SI). Field potentials evoked by single pulse stimulation in cortical layer IV were recorded from layer II/III. In control experiments, tetanic high frequency stimulation (HFS) resulted in input-specific, NMDA receptor-dependent LTP (21.1+/-3.2%; mean+/-SEM; n=15; P<0.001). BN-52021 (5 microM), an antagonist at the extracellular PAF receptor, weakened the HFS-induced LTP to 12.4+/-2.7% (n=11; P<0.05). In contrast, HFS-induced LTP was significantly enhanced to 29.4+/-2.3% (n=11; P<0.05) when brain slices were superfused with ACSF containing the PAF receptor-agonist C-PAF (1.5 microM). The difference between LTP weakened by BN-52021 and LTP enhanced by C-PAF was highly significant (P<0.0005). These results suggest a physiological contribution of PAF to the induction of LTP in neocortical area SI. This contribution of PAF is mediated by an action at extracellular receptor sites.
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Affiliation(s)
- Peter Heusler
- Institute of Physiology and Pathophysiology, Johannes Gutenberg University, Duesbergweg 6, D-55099 Mainz, Germany
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Bate C, Kempster S, Williams A. Platelet-activating factor antagonists protect amyloid-β damaged neurons from microglia-mediated death. Neuropharmacology 2006; 51:173-81. [PMID: 16678220 DOI: 10.1016/j.neuropharm.2006.02.015] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2005] [Revised: 02/22/2006] [Accepted: 02/27/2006] [Indexed: 11/26/2022]
Abstract
Neurons treated with sub-lethal concentrations of amyloid-beta1-42 developed phenotypic changes and selectively bound a CD14-IgG chimera; in co-cultures, microglia recognised and killed these amyloid-beta1-42 -damaged neurons. Pre-treatment with the platelet-activating factor (PAF) antagonists (Hexa-PAF, CV6209 or ginkgolide B) reduced CD14-IgG binding to amyloid-beta1-42 -damaged neurons, and the presence of PAF antagonists in co-cultures increased neuronal survival in a dose-dependant manner. PAF antagonists also protected neurons treated with HuPrP82-146, a peptide found in prion diseases. Second messenger studies demonstrated that the addition of PAF mimicked some of the effects of amyloid-beta1-42 on neurons. PAF-damaged neurons bound CD14-IgG, and PAF-damaged neurons were killed by microglia in a CD14-dependent process. Neuronal death was inversely related to both the concentration of PAF, and the number of microglia added. The effects of PAF were reduced by an antagonist of the prostanoid D receptor (BWA868C) indicating that neuronal damage induced by PAF is partly mediated by prostaglandins. These observations are compatible with the hypothesis that sub-lethal concentrations of amyloid-beta1-42 stimulate a cascade of second messengers including PAF and the prostaglandins. At nanomolar concentrations PAF induces a change in neuronal phenotype that activates microglia via the CD14 molecule, these activated microglia then kill the amyloid-beta1-42 damaged neurons.
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Affiliation(s)
- Clive Bate
- Department of Pathology and Infectious Diseases, Royal Veterinary College, Hawkshead Lane, North Mymms, Hatfield, Hertfordshire AL9 7TA, UK.
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Sang N, Zhang J, Marcheselli V, Bazan NG, Chen C. Postsynaptically synthesized prostaglandin E2 (PGE2) modulates hippocampal synaptic transmission via a presynaptic PGE2 EP2 receptor. J Neurosci 2006; 25:9858-70. [PMID: 16251433 PMCID: PMC6725559 DOI: 10.1523/jneurosci.2392-05.2005] [Citation(s) in RCA: 149] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Increasing evidence suggests that cyclooxygenase-2 (COX-2) is involved in synaptic transmission and plasticity, and prostaglandin E2 (PGE2) is a key molecule in COX-2-meduated synaptic modification. However, the precise mechanisms, in particular, which subtypes of PGE2 receptors (EPs) mediate the PGE2-induced synaptic response, are not clear. Recently, we demonstrated that EPs are expressed heterogeneously in the hippocampus, and EP2/4 are mainly expressed in presynaptic terminals. Here, we report that PGE2 increased synaptic stimulus-evoked amplitudes of EPSPs in hippocampal slices and frequency of miniature EPSCs (mEPSCs) in hippocampal neurons in culture. These actions were mimicked by an EP2 agonist and attenuated by protein kinase A inhibitors. Decrease of EP2 expression through silencing the EP2 gene eliminated PGE2-induced increase of the frequency of mEPSCs. COX-2 and microsomal PGE synthase-1 (mPGES-1) and mPGES-2 are present in postsynaptic dendritic spines, because they are colocalized with PSD-95 (postsynaptic density-95), a postsynaptic marker. In addition, the frequency of mEPSCs was enhanced in neurons pretreated with interleukin-1beta or lipopolysaccharide, which elevated expression of COX-2 and mPGES-1 and produced PGE2, and this enhancement was inhibited by a COX-2 inhibitor that inhibited production of PGE2. Our results suggest that PGE2 synthesized by postsynaptically localized COX-2 functions as a retrograde messenger in hippocampal synaptic signaling via a presynaptic EP2 receptor.
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Affiliation(s)
- Nan Sang
- Neuroscience Center of Excellence, School of Medicine, Louisiana State University Health Sciences Center, New Orleans, Louisiana 70112, USA
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Chen C, Bazan NG. Lipid signaling: sleep, synaptic plasticity, and neuroprotection. Prostaglandins Other Lipid Mediat 2005; 77:65-76. [PMID: 16099392 DOI: 10.1016/j.prostaglandins.2005.07.001] [Citation(s) in RCA: 122] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2004] [Accepted: 07/02/2005] [Indexed: 01/25/2023]
Abstract
Increasing evidence indicates that bioactive lipids participate in the regulation of synaptic function and dysfunction. We have demonstrated that signaling mediated by platelet-activating factor (PAF) and cyclooxygenase (COX)-2-synthesized PGE2 is involved in synaptic plasticity, memory, and neuronal protection [Clark GD, Happel LT, Zorumski CF, Bazan NG. Enhancement of hippocampal excitatory synaptic transmission by platelet-activating factor. Neuron 1992; 9:1211; Kato K, Clark GD, Bazan NG, Zorumski CF. Platelet-activating factor as a potential retrograde messenger in CA1 hippocampal long-term potentiation. Nature 1994; 367:175; Izquierdo I, Fin C, Schmitz PK, et al. Memory enhancement by intrahippocampal, intraamygdala or intraentorhinal infusion of platelet-activating factor measured in an inhibitory avoidance. Proc Natl Acad Sci USA 1995; 92:5047; Chen C, Magee CJ, Bazan NG. Cyclooxygenase-2 regulates prostaglandin E2 signaling in hippocampal long-term synaptic plasticity. J Neurophysiol 2002; 87:2851]. Recently, we found that prolonged continuous wakefulness (primarily rapid eye movement (REM)-sleep deprivation, SD) causes impairments in hippocampal long-term synaptic plasticity and hippocampus-dependent memory formation [McDermott CM, LaHoste GJ, Chen C, Musto A, Bazan NG, Magee JC. Sleep deprivation causes behavioral, synaptic, and membrane excitability alterations in hippocampal neurons. J Neurosci 2003; 23:9687]. To explore the mechanisms underlying SD-induced impairments, we have studied several bioactive lipids in the hippocampus following SD. It appears that SD causes increases in prostaglandin D2 (PGD2) and 2-arachidonylglycerol (2-AG), and a decrease in PGE2, suggesting that these lipid messengers participate in memory consolidation during REM sleep. We have also explored the formation of endogenous neuroprotective lipids. Toward this aim, we have used ischemia-reperfusion damage and LC-PDA-ESI-MS-MS-based lipidomic analysis and identified docosanoids derived from synaptic phospholipid-enriched docosahexaenoic acid. Some of the docosanoids exert potent neuroprotective bioactivity [Marcheselli VL, Hong S, Lukiw WJ, et al. Novel docosanoids inhibit brain ischemia-reperfusion-mediated leukocyte infiltration and pro-inflammatory gene expression. J Biol Chem 2003; 278:43807; Mukherjee PK, Marcheselli VL, Serhan CN, Bazan, NG. Neuroprotectin D1: A docosahexaenoic acid-derived docosatriene protects human retinal pigment epithelial cells from oxidative stress. Proc Nat Acad Sci USA 2004; 101:8491). Taken together, these observations that signaling lipids participate in synaptic plasticity, cognition, and survival indicate that lipid signaling is closely associated with several functions (e.g; learning and memory, sleep, and experimental stroke) and pathologic events. Alterations in endogenous signaling lipids or their receptors resulting from drug abuse lead to changes in synaptic circuitry and induce profound effects on these important functions. In the present article, we will briefly review bioactive lipids involved in sleep, synaptic transmission and plasticity, and neuroprotection, focusing mainly on our experimental studies and how these signaling molecules are related to functions and implicated in some neurologic disorders.
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Affiliation(s)
- Chu Chen
- Neuroscience Center of Excellence and Department of Ophthamology, Louisiana State University Health Sciences Center, School of Medicine in New Orleans, 2020 Gravier Street, Suite D, New Orleans, LA 70112, USA
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Chen C, Hardy M, Zhang J, LaHoste GJ, Bazan NG. Altered NMDA receptor trafficking contributes to sleep deprivation-induced hippocampal synaptic and cognitive impairments. Biochem Biophys Res Commun 2005; 340:435-40. [PMID: 16376302 DOI: 10.1016/j.bbrc.2005.12.021] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2005] [Accepted: 12/05/2005] [Indexed: 11/29/2022]
Abstract
Recent evidence indicates that continuous wakefulness (sleep deprivation, SD) causes impairments in behavioral performance and hippocampal long-term potentiation (LTP) in animals. However, the mechanisms by which SD impairs long-term synaptic plasticity and cognitive function are not clear. Here, we report that 24-h SD in mice results in impaired hippocampus-dependent contextual memory and LTP and, unexpectedly, in reductions of the surface expression of NMDA receptor (NMDAR) subunit NR1 and NMDAR-mediated excitatory post-synaptic currents at hippocampal perforant path-dentate granule cell synapses. The results suggest that the reduction of functional NMDAR in hippocampal neurons may underlie the SD-induced deficits in hippocampus-dependent contextual memory and long-term synaptic plasticity.
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Affiliation(s)
- Chu Chen
- Neuroscience Center, School of Medicine, Louisiana State University Health Sciences Center, New Orleans, LA 70112, USA.
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Chen C. β-Amyloid increases dendritic Ca2+ influx by inhibiting the A-type K+ current in hippocampal CA1 pyramidal neurons. Biochem Biophys Res Commun 2005; 338:1913-9. [PMID: 16289381 DOI: 10.1016/j.bbrc.2005.10.169] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2005] [Accepted: 10/25/2005] [Indexed: 10/25/2022]
Abstract
Accumulation of the beta-amyloid peptide (Abeta) is a primary event in the pathogenesis of Alzheimer's disease (AD). However, the mechanisms by which Abeta mediates neurotoxicity and initiates the degenerative processes of AD are still not clear. Recent evidence shows that voltage-gated K+ channels may be involved in Abeta-induced neurodegenerative processes. In particular, a transient A-type K+ current, with a linear increase in its density with distance from soma to distal dendrites in hippocampal CA1 pyramidal neurons, has been shown to contribute to dendritic membrane excitability. Here, I report that Abeta (1-42) inhibits the dendritic A-type K+ current in hippocampal CA1 pyramidal neurons, and this inhibition causes increases in back-propagating dendritic action potential amplitude and associated Ca2+ influx. These results suggest that the persistent inhibition of the A-type K+ current resulting from deposition of Abeta in dendritic arborization will induce a sustained increase in dendritic Ca2+ influx and lead to loss of Ca2+ homeostasis. This may be a component of the events that cause synaptic failure and initiate neuronal degenerative processes in the hippocampus.
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Affiliation(s)
- Chu Chen
- Neuroscience Center, School of Medicine, Louisiana State University Health Sciences Center, New Orleans, LA 70112, USA
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Nakanishi K. Terpene trilactones from Gingko biloba: from ancient times to the 21st century. Bioorg Med Chem 2005; 13:4987-5000. [PMID: 15990319 DOI: 10.1016/j.bmc.2005.06.014] [Citation(s) in RCA: 104] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2005] [Accepted: 06/01/2005] [Indexed: 11/19/2022]
Abstract
Ginkgolides were always close to my heart. I continue to be strongly attracted to Ginkgo biloba, the ginkgolides and bilobalide. Starting in 1963, I became fascinated by these molecules while working on their isolation and structure elucidation in Sendai. Presumably, due to the ginkgolide studies, I received an invitation to join the faculty at Columbia University. After almost three decades of not touching the ginkgolide project, we have unexpectedly resumed the studies, at this time because of their enigmatic biological effects. This account is a reflection on earlier studies, as well as an outline of our current work.
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Affiliation(s)
- Koji Nakanishi
- Department of Chemistry, Columbia University, New York, NY 10027, USA.
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Abstract
The extensive networking of the cells of the nervous system results in large cell membrane surface areas. We now know that neuronal membranes contain phospholipid pools that are the reservoirs for the synthesis of specific lipid messengers on neuronal stimulation or injury. These messengers in turn participate in signaling cascades that can either promote neuronal injury or neuroprotection. Prostaglandins are synthesized as a result of cyclooxygenase activity. In the first step of the arachidonic acid cascade, the short-lived precursor, prostaglandin H2, is synthesized. Additional steps in the cascade result in the synthesis of an array of prostaglandins, which participate in numerous physiological and neurological processes. Our laboratory recently reported that the membrane polyunsaturated fatty acid, docosahexaenoic acid, is the precursor of oxygenation products now known as the docosanoids, some of which are powerful counter-proinflammatory mediators. The mediator 10,17S-docosatriene (neuroprotectin D1, NPD1) counteracts leukocyte infiltration, NF-kappa activation, and proinflammatory gene expression in brain ischemia-reperfusion and is an apoptostatic mediator, potently counteracting oxidative stress-triggered apoptotic DNA damage in retinal pigment epithelial cells. NPD1 also upregulates the anti-apoptotic proteins Bcl-2 and Bcl-xL and decreases pro-apoptotic Bax and Bad expression. Another biologically active messenger derived from membrane phospholipids in response to synaptic activity is platelet-activating factor (PAF). The tight regulation of the balance between synthesis (via phospholipases) and degradation (via acetylhydrolases) of PAF modulates the functions of this lipid messenger. Under pathological conditions, this balance is tipped, and PAF becomes a proinflammatory mediator and neurotoxic agent. The newly discovered docosahexaenoic acid signaling pathways, as well as other lipid messengers related to synaptic activation, may lead to the clarification of clinical issues relevant to stroke, age-related macular degeneration, spinal cord injury, Alzheimer's disease, and other diseases that include neuroinflammatory components.
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Affiliation(s)
- Nicolas G Bazan
- LSU Neuroscience Center of Excellence and Department of Ophthalmology, Louisiana State University Health Sciences Center, New Orleans, LA, USA.
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Chen C, Bazan NG. Endogenous PGE2Regulates Membrane Excitability and Synaptic Transmission in Hippocampal CA1 Pyramidal Neurons. J Neurophysiol 2005; 93:929-41. [PMID: 15653788 DOI: 10.1152/jn.00696.2004] [Citation(s) in RCA: 117] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The significance of cyclooxygenases (COXs), the rate-limiting enzymes that convert arachidonic acid (AA) to prostaglandins (PGs) in the brain, is unclear, although they have been implicated in inflammatory responses and in some neurological disorders such as epilepsy and Alzheimer's disease. Recent evidence that COX-2, which is expressed in postsynaptic dendritic spines, regulates PGE2signaling in activity-dependent long-term synaptic plasticity at hippocampal perforant path-dentate granule cell synapses, suggests an important role of the COX-2–generated PGE2in synaptic signaling. However, little is known of how endogenous PGE2regulates neuronal signaling. Here we showed that endogenous PGE2selectively regulates fundamental membrane and synaptic properties in the hippocampus. Somatic and dendritic membrane excitability was significantly reduced when endogenous PGE2was eliminated with a selective COX-2 inhibitor in hippocampal CA1 pyramidal neurons in slices. Exogenous application of PGE2produced significant increases in frequency of firing, excitatory postsynaptic potentials (EPSP) amplitude, and temporal summation in slices treated with the COX-2 inhibitor. The PGE2-induced increase in membrane excitability seemed to result from its inhibition of the potassium currents, which in turn, boosted dendritic Ca2+influx during dendritic-depolarizing current injections. In addition, the PGE2-induced enhancement of EPSPs was blocked by eliminating both PKA and PKC activities. These findings indicate that endogenous PGE2dynamically regulates membrane excitability, synaptic transmission, and plasticity and that the PGE2-induced synaptic modulation is mediated via cAMP-PKA and PKC pathways in rat hippocampal CA1 pyramidal neurons.
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Affiliation(s)
- Chu Chen
- Neuroscience Center of Excellence, Louisiana State University Health Sciences Center, New Orleans, LA 70112, USA.
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Zhu P, Genc A, Zhang X, Zhang J, Bazan NG, Chen C. Heterogeneous expression and regulation of hippocampal prostaglandin E2 receptors. J Neurosci Res 2005; 81:817-26. [PMID: 16041798 DOI: 10.1002/jnr.20597] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Although prostaglandin E2 (PGE2) has been shown to be critical to hippocampal synaptic signaling and neuronal survival, it is still not clear which subtypes of PGE2 receptors (EPs) are expressed and how these EPs are regulated in the hippocampus. To address these questions, the expression of the EPs was profiled in the hippocampus. Messenger RNAs and proteins of the four receptors, EP 1-4, were detected both in the hippocampus and in the neocortex. EP 2 and EP 3 appeared in greater abundance, whereas EP 1 and EP 4 were barely detectable. EP 1, EP 2 and EP 4 were mainly colocalized with synaptophysin, suggesting the presence of EP 1, EP 2, and EP 4 in presynaptic terminals. It appeared that interleukin-1 beta increased the expression of EP 2 and EP 4 mRNAs. A blockade of synaptic transmission with either tetrodotoxin or MK-801 plus 6,7-dinitroquinoxaline-2,3-dione (DNQX) for 6 hr increased EP 3 and EP 4 mRNA, whereas high K(+) (90 mM) or 4-aminopyridine enhanced EP 2 and EP 4. The EP 1 level did not change significantly under these conditions. The expressions of EP 2, EP 4, and EP 3 were further elevated or reduced in neurons treated with high K(+) for 24 hr. However, mRNA of EP 3 was down-regulated in neurons treated with tetrodotoxin or MK-801 plus DNQX for 24 hr. In addition, both EP 2 and EP 4 mRNAs were up-regulated within 4 hr after high-frequency stimulation associated with long-term potentiation induction in hippocampal slices. Our results indicate that the four EPs are heterogeneously expressed in the hippocampus, and their expression is differentially regulated by neuronal activities, suggesting that EPs may actively participate in hippocampal synaptic transmission and plasticity.
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Affiliation(s)
- Peimin Zhu
- Neuroscience Center, School of Medicine, LSU Health Sciences Center, New Orleans, Louisiana
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Strømgaard K, Suehiro M, Nakanishi K. Preparation of a tritiated ginkgolide. Bioorg Med Chem Lett 2004; 14:5673-5. [PMID: 15482945 DOI: 10.1016/j.bmcl.2004.08.042] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2004] [Revised: 08/17/2004] [Accepted: 08/18/2004] [Indexed: 11/20/2022]
Abstract
Ginkgolide B, a constituent of the tree Ginkgo biloba, was radiolabeled with the beta-emitter tritium ([(3)H]) in two steps from ginkgolide C. First, a triflate precursor was prepared utilizing the selective reactivity of 7-OH in ginkgolide C; the triflate was then reduced with sodium borotritide to yield tritiated ginkgolide B ([(3)H]GB) in good yield and high specific activity. The tritiated ginkgolide will be an important tool for studying neuromodulatory properties of ginkgolides.
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Row BW, Kheirandish L, Li RC, Guo SZ, Brittian KR, Hardy M, Bazan NG, Gozal D. Platelet-activating factor receptor-deficient mice are protected from experimental sleep apnea-induced learning deficits. J Neurochem 2004; 89:189-96. [PMID: 15030403 DOI: 10.1111/j.1471-4159.2004.02352.x] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Intermittent hypoxia (IH) during sleep, a hallmark of sleep apnea, is associated with neurobehavioral impairments, regional neurodegeneration and increased oxidative stress and inflammation in rodents. Platelet-activating factor (PAF) is an important mediator of both normal neural plasticity and brain injury. We report that mice deficient in the cell surface receptor for PAF (PAFR-/-), a bioactive mediator of oxidative stress and inflammation, are protected from the spatial reference learning deficits associated with IH. Furthermore, PAFR-/- exhibit attenuated elevations in inflammatory signaling (cyclo-oxygenase-2 and inducible nitric oxide synthase activities), degradation of the ubiquitin-proteasome pathway and apoptosis observed in wild-type littermates (PAFR+/+) exposed to IH. Collectively, these findings indicate that inflammatory signaling and neurobehavioral impairments induced by IH are mediated through PAF receptors.
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Affiliation(s)
- Barry W Row
- Kosair Children's Hospital Research Institute, Department of Pediatrics, University of Louisville, Louisville, Kentucky 40202, USA
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Reeves SR, Gozal D. Platelet-activating factor receptor modulates respiratory adaptation to long-term intermittent hypoxia in mice. Am J Physiol Regul Integr Comp Physiol 2004; 287:R369-74. [PMID: 15087283 DOI: 10.1152/ajpregu.00128.2004] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
During hypoxia, release of platelet-activating factor (PAF) and activation of its cognate receptor (PAFR) regulate neural transmission and are required for full expression of peak hypoxic ventilatory response (pHVR) but not hypercapnic ventilatory response. However, it is unclear whether PAFR underlie components of long-term ventilatory adaptations to hypoxia. To examine this issue, adult male PAFR(+/+) and PAFR(-/-) mice were exposed to intermittent hypoxia (IH) consisting of 90 s 21% O(2) and 90 s 10% O(2) for 30 days, and normoxic and hypoxic ventilatory patterns were assessed using whole body plethysmography. Starting at day 14 of IH, normoxic ventilation in PAFR(-/-) was reduced significantly compared with PAFR(+/+) mice (P < 0.001), the latter exhibiting a prominent long-term ventilatory facilitation (LTVF). However, IH-exposed PAFR(-/-) mice had markedly enhanced pHVR and hypoxic ventilatory decline that became similar to those of IH-exposed PAFR(+/+) mice. Thus we postulate that PAFR expression and/or function underlies critical components of IH-induced LTVF but does not play a role in the potentiation of the hypoxic ventilatory response after IH exposures.
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Affiliation(s)
- Stephen R Reeves
- Department of Pediatrics, Kosair Children's Hospital Research Institute, University of Louisville School of Medicine, Louisville, Kentucky 40202, USA
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Chen C. ZD7288 inhibits postsynaptic glutamate receptor-mediated responses at hippocampal perforant path-granule cell synapses. Eur J Neurosci 2004; 19:643-9. [PMID: 14984414 DOI: 10.1111/j.0953-816x.2003.03174.x] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Hyperpolarization-activated channels (Ih) are widely expressed in the nervous system and believed to play an important role in the regulation of membrane excitability and rhythmic activity. Recent evidence suggests that Ih may be involved in long-term potentiation (LTP) in the hippocampus; however, the results are controversial. To explore the possible causes of these differing results, the effects of Ih blockers on synaptic activity were evaluated in mouse hippocampal slices. ZD7288 (20 micro m), a selective Ih blocker, apparently prevented the induction of LTP, while Cs+ (1 mm), a commonly used Ih blocker, had no effect on LTP at hippocampal perforant path-dentate granule cell synapses. In addition, ZD7288 but not Cs+ abolished basal synaptic transmission. Results from voltage-clamp experiments showed that ZD7288 produced a very little inhibition on hyperpolarization-activated currents, indicating a weak expression of the Ih in granule neurons. Outside-out patch recordings revealed that ZD7288 inhibited glutamate receptor-mediated responses, while Cs+ had no effect on them. Meanwhile, ZD7288 reduced both alpha-amino-3-hydroxy-5-methylisoxazole-4-propionate and N-methyl-d-aspartate receptor-mediated excitatory postsynaptic currents. The results suggest that ZD7288-induced reduction of synaptic transmission may result from its inhibition of the postsynaptic glutamate receptors on dentate granule neurons.
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Affiliation(s)
- Chu Chen
- Neuroscience Center, School of Medicine, Louisiana State University Health Sciences Center, 2020 Gravier Street, Suite D, New Orleans, LA 70112, USA.
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Abstract
One of the most significant challenges in neuroscience is to identify the cellular and molecular processes that underlie learning and memory formation. The past decade has seen remarkable progress in understanding changes that accompany certain forms of acquisition and recall, particularly those forms which require activation of afferent pathways in the hippocampus. This progress can be attributed to a number of factors including well-characterized animal models, well-defined probes for analysis of cell signaling events and changes in gene transcription, and technology which has allowed gene knockout and overexpression in cells and animals. Of the several animal models used in identifying the changes which accompany plasticity in synaptic connections, long-term potentiation (LTP) has received most attention, and although it is not yet clear whether the changes that underlie maintenance of LTP also underlie memory consolidation, significant advances have been made in understanding cell signaling events that contribute to this form of synaptic plasticity. In this review, emphasis is focused on analysis of changes that occur after learning, especially spatial learning, and LTP and the value of assessing these changes in parallel is discussed. The effect of different stressors on spatial learning/memory and LTP is emphasized, and the review concludes with a brief analysis of the contribution of studies, in which transgenic animals were used, to the literature on memory/learning and LTP.
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Affiliation(s)
- M A Lynch
- Trinity College Institute of Neuroscience, Department of Physiology, Trinity College, Dublin, Ireland.
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Bazan NG. Synaptic lipid signaling: significance of polyunsaturated fatty acids and platelet-activating factor. J Lipid Res 2003; 44:2221-33. [PMID: 13130128 DOI: 10.1194/jlr.r300013-jlr200] [Citation(s) in RCA: 205] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Neuronal cellular and intracellular membranes are rich in specialized phospholipids that are reservoirs of lipid messengers released by specific phospholipases and stimulated by neurotransmitters, neurotrophic factors, cytokines, membrane depolarization, ion channel activation, etc. Secretory phospholipases A2 may be both intercellular messengers and generators of lipid messengers. The highly networked nervous system includes cells (e.g., astrocytes, oligodendrocytes, microglial cells, endothelial microvascular cells) that extensively interact with neurons; several lipid messengers participate in these interactions. This review highlights modulation of postsynaptic membrane excitability and long-term synaptic plasticity by cyclooxygenase-2-generated prostaglandin E2, arachidonoyldiacylcylglycerol, and arachidonic acid-containing endocannabinoids. The peroxidation of docosahexaenoic acid (DHA), a critical component of excitable membranes in brain and retina, is promoted by oxidative stress. DHA is also the precursor of enzyme-derived, neuroprotective docosanoids. The phospholipid platelet-activating factor is a retrograde messenger of long-term potentiation, a modulator of glutamate release, and an upregulator of memory formation. Lipid messengers modulate signaling cascades and contribute to cellular differentiation, function, protection, and repair in the nervous system. Lipidomic neurobiology will advance our knowledge of the brain, spinal cord, retina, and peripheral nerve function and diseases that affect them, and new discoveries on networks of signaling in health and disease will likely lead to novel therapeutic interventions.
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Affiliation(s)
- Nicolas G Bazan
- Louisiana State University Neuroscience Center of Excellence and Department of Ophthalmology, Louisiana State University Health Sciences Center, New Orleans, LA, USA.
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Andrásfalvy BK, Smith MA, Borchardt T, Sprengel R, Magee JC. Impaired regulation of synaptic strength in hippocampal neurons from GluR1-deficient mice. J Physiol 2003; 552:35-45. [PMID: 12878757 PMCID: PMC2343312 DOI: 10.1113/jphysiol.2003.045575] [Citation(s) in RCA: 91] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Neurons of the central nervous system (CNS) exhibit a variety of forms of synaptic plasticity, including associative long-term potentiation and depression (LTP/D), homeostatic activity-dependent scaling and distance-dependent scaling. Regulation of synaptic neurotransmitter receptors is currently thought to be a common mechanism amongst many of these forms of plasticity. In fact, glutamate receptor 1 (GluR1 or GluRA) subunits containing L-alpha-amino-3-hydroxy-5-methylisoxazole-4-propionate (AMPA) receptors have been shown to be required for several forms of hippocampal LTP and a particular hippocampal-dependent learning task. Because of this importance in associative plasticity, we sought to examine the role of these receptors in other forms of synaptic plasticity in the hippocampus. To do so, we recorded from the apical dendrites of hippocampal CA1 pyramidal neurons in mice lacking the GluR1 subunit (GluR1 -/-). Here we report data from outside-out patches that indicate GluR1-containing receptors are essential to the extrasynaptic population of AMPA receptors, as this pool was nearly empty in the GluR1 -/- mice. Additionally, these receptors appear to be a significant component of the synaptic glutamate receptor pool because the amplitude of spontaneous synaptic currents recorded at the site of input and synaptic AMPA receptor currents evoked by focal glutamate uncaging were both substantially reduced in these mice. Interestingly, the impact on synaptic weight was greatest at distant synapses such that the normal distance-dependent synaptic scaling used by these cells to counter dendritic attenuation was lacking in GluR1 -/- mice. Together the data suggest that the highly regulated movement of GluR1-containing AMPA receptors between extrasynaptic and synaptic receptor pools is critically involved in establishing two functionally diverse forms of synaptic plasticity: LTP and distance-dependent scaling.
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Affiliation(s)
- Bertalan K Andrásfalvy
- Neuroscience Center, Louisiana State University Health Science Center, 2020 Gravier Street, New Orleans, LA 70112, USA.
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Tokuoka SM, Ishii S, Kawamura N, Satoh M, Shimada A, Sasaki S, Hirotsune S, Wynshaw-Boris A, Shimizu T. Involvement of platelet-activating factor and LIS1 in neuronal migration. Eur J Neurosci 2003; 18:563-70. [PMID: 12911752 DOI: 10.1046/j.1460-9568.2003.02778.x] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Platelet-activating factor (PAF, 1-O-alkyl-2-acetyl-sn-glycero-3-phosphocholine) is a biologically active lipid mediator. We have previously shown the expression of PAF receptor in neurons and microglia. PAF is produced in the brain from its precursor, and degraded by the enzyme PAF acetylhydrolase. LIS1 is a regulatory subunit of PAF acetylhydrolase, and is identical to a gene whose deletion causes the human neuronal migration disorder, type I lissencephaly. Indeed, Lis1 mutant mice display defects in neuronal migration and layering in vivo, and also in cerebellar granule cell migration in vitro. However, the roles of PAF and the PAF receptor in the neuronal migration remain to be determined. Here, we show that PAF receptor-deficient mice exhibited histological abnormalities in the embryonic cerebellum. PAF receptor-deficient cerebellar granule neurons migrated more slowly in vitro than wild-type neurons, consistent with the observation that a PAF receptor antagonist reduced the migration of wild-type neurons in vitro. Synergistic reduction of neuronal migration was observed in a double mutant of PAF receptor and LIS1. Unexpectedly, PAF affected the migration of PAF receptor-deficient neurons, suggesting a receptor-independent pathway for PAF action. The PAF receptor-independent response to PAF was abolished in granule neurons derived from the double mutant mice. Thus, our results suggest that the migration of cerebellar granule cells is regulated by PAF through receptor-dependent and receptor-independent pathways, and that LIS1 is a pivotal molecule that links PAF action and neuronal cell migration both in vivo and in vitro.
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Affiliation(s)
- Suzumi M Tokuoka
- Department of Biochemistry and Molecular Biology, Faculty of Medicine, The University of Tokyo, CREST of JST, Tokyo 113-0033, Japan
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Abstract
Acetaminophen (APAP) has recently been found to target COX-3, a newly identified COX isozyme. We discovered previously that selective COX-2 inhibitors reduce membrane excitability and long-term potentiation (LTP) in the hippocampus. The purpose of this study was to investigate whether APAP had effects on hippocampal LTP. We found that APAP reduced LTP induction and increased the paired-pulse facilitation (PPF). APAP-induced changes in LTP and PPF were blocked by a 5-hydroxytryptamine (serotonin, 5-HT(2/1)) receptor antagonist. The results suggest that APAP-induced modification of synaptic plasticity at hippocampal lateral perforant path-dentate granule cell synapses may be mediated by a presynaptic 5-HT(2) receptor.
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Affiliation(s)
- Chu Chen
- Neuroscience Center of Excellence, School of Medicine, LSU Health Sciences Center, 2020 Gravier Street, Suite D, New Orleans, LA 70112, USA.
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41
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Brewer C, Bonin F, Bullock P, Nault MC, Morin J, Imbeault S, Shen TY, Franks DJ, Bennett SAL. Platelet activating factor-induced apoptosis is inhibited by ectopic expression of the platelet activating factor G-protein coupled receptor. J Neurochem 2002; 82:1502-11. [PMID: 12354298 DOI: 10.1046/j.1471-4159.2002.01094.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The pro-inflammatory lipid mediator platelet activating factor (PAF: 1-O-alkyl-2-acetyl-sn-glycero-3-phosphocholine) accumulates in ischemia, epilepsy, and human immunodeficiency virus-1-associated dementia and is implicated in neuronal loss. The present study was undertaken to establish a role for its G-protein coupled receptor in regulating neurotoxicity. PC12 cells do not express PAF receptor mRNA as demonstrated by northern analysis and RT-PCR. In the absence of the G-protein coupled receptor, PAF (0.1-1 micro m) triggered chromatin condensation, DNA strand breaks, oligonucleosomal fragmentation, and nuclear disintegration characteristic of apoptosis. Lyso-PAF (0.001-1 micro m), the immediate metabolite of PAF, did not elicit apoptotic death. Concentrations of PAF or lyso-PAF that exceeded critical micelle concentration had physicochemical effects on plasma membrane resulting in necrosis. Apoptosis but not necrosis was inhibited by the PAF antagonist BN52021 (1-100 micro m) but not CV3988 (0.2-20 micro m). Ectopic PAF receptor expression protected PC12 transfectants from ligand-induced apoptosis. PAF receptor-mediated protection was inhibited by CV3988 (1 micro m). These data provide empirical evidence that: (i) PAF can initiate apoptosis independently of its G-protein coupled receptor; (ii) PAF signaling initiated by its G-protein coupled receptor is cytoprotective to PC12 cells; (iii) the pro- and anti-apoptotic effects of PAF on PC12 cells can be pharmacologically distinguished using two different PAF antagonists.
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Affiliation(s)
- Cynthia Brewer
- Neural Regeneration Laboratory, Department of Biochemistry, Microbiology, and Immunology, University of Ottawa, Ottawa, Ontario, Canada
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Bazan NG, Tu B, Rodriguez de Turco EB. What synaptic lipid signaling tells us about seizure-induced damage and epileptogenesis. PROGRESS IN BRAIN RESEARCH 2002; 135:175-85. [PMID: 12143339 DOI: 10.1016/s0079-6123(02)35017-9] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
Abstract
Glutamate, the most abundant excitatory neurotransmitter in the mammalian CNS, plays a central role in many neuronal functions, such as long-term potentiation, which is necessary for learning and memory formation. The fast excitatory glutamate neurotransmission is mediated by ionotropic receptors that include AMPA/kainate and N-methyl-D-aspartate (NMDA) receptors, while the slow glutamate responses are mediated through its interaction with metabotropic receptors (mGluRs) coupled to G-proteins. During seizures, massive release of glutamate underlies excitotoxic neuronal damage as it triggers an overflow of calcium in postsynaptic neurons mediated by NMDA-gated channels. The early upstream postsynaptic events involve the activation of phospholipases, with the release of membrane-derived signaling molecules, such as free arachidonic acid (AA), eicosanoids, and platelet-activating factor (PAF). These bioactive lipids modulate the early neuronal responses to stimulation as they affect the activities of ion channels, receptors, and enzymes; and when released into the extracellular space, they can contribute to the modulation of presynaptic neurotransmitter release/re-uptake, and/or affect other neighboring neuronal/glial cells. The downstream postsynaptic events target the nucleus, leading to activation of gene-expression cascades. Syntheses of new proteins are the basis for seizure-induced sustained physiological and/or pathological changes that occur hours, days, or months later, such as synaptic reorganization and repair, and apoptotic/necrotic neuronal death. The intricate mesh of signaling pathways converging to the nucleus, and connecting upstream to downstream synaptic events, are at present the focus of many research efforts. We describe in this chapter how seizure-induced glutamate release activates the hydrolysis of membrane AA-phospholipids via phospholipase A2 (PLA2), PLC, and PLD, thus releasing bioactive lipids that, in turn, modulate neurotransmission. We discuss mechanisms through which lipid messengers, such as AA and PAF, may turn into injury mediators participating in seizure-induced brain damage.
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Affiliation(s)
- Nicolas G Bazan
- Neuroscience Center of Excellence, Department of Ophthalmology, Louisiana State University Health Sciences Center, 2020 Gravier Street, Suite D, New Orleans, LA 70112, USA.
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43
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Abstract
Platelet-activating factor (PAF, 1-O-alkyl-2-acetyl-sn-glycero-3-phosphocholine) is a biologically active phospholipid mediator. Although PAF was named for its potential to induce platelet aggregation, intense investigations have elucidated potent biological actions of PAF in a broad range of cell types and tissues. PAF acts by binding to a unique G-protein-coupled seven transmembrane receptor, and activates multiple intracellular signaling pathways. In the last decade, we have identified the PAF receptor structures, intracellular signaling mechanisms, and genomic organizations. Recently, we found a single nucleotide polymorphism of the human PAF receptor (A224D) with an allele frequency of 7.8% in Japanese. Cells expressing this receptor exhibited the reduced cellular signaling, although the binding parameters remain unchanged. We have established two different types of genetically altered mice, i.e. PAF receptor-overexpressing mouse and PAF receptor-deficient mouse. These mutant mice provide a novel and specific approach for identifying the pathophysiological and physiological functions of PAF in vivo. This review focuses on phenotypes of these mutant mice and summarizes the previous reports regarding PAF and PAF receptor.
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Affiliation(s)
- Satoshi Ishii
- Department of Biochemistry and Molecular Biology, Faculty of Medicine, The University of Tokyo, Japan.
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44
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Parker MA, Bazan HEP, Marcheselli V, Rodriguez de Turco EB, Bazan NG. Platelet-activating factor induces permeability transition and cytochrome c release in isolated brain mitochondria. J Neurosci Res 2002; 69:39-50. [PMID: 12111814 DOI: 10.1002/jnr.10235] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Platelet-activating factor (PAF), a potent bioactive phospholipid implicated in neuronal excitotoxic death, was assessed as a mediator of brain mitochondrial dysfunction. Carbamyl PAF, a non-hydrolyzable PAF analog, added to neurons in culture resulted in decreased mitochondrial membrane potential (DeltaPsi(M)) as measured by the DeltaPsi(M)-sensitive fluorophore 5,5', 6,6'-tetrachloro-1, 1', 3,3'-tetraethylethylbenzimidazolo-carbocyanide iodide (JC-1). To investigate whether PAF has a direct effect on the mitochondria, the mediator was added to rat brain mitochondria preparations and an increase in the permeability of the mitochondrial membrane, termed permeability transition (PT), and cytochrome c release were measured. We report that PAF causes both dose-dependent PT and cytochrome c release from isolated mitochondria. Furthermore, the selective PAF antagonist tetrahydro-4,7,8,10 methyl-1 (chloro-2 phenyl)-6 (methoxy-4 phenyl-carbamoyl)-9 pyrido [4',3'-4,5] thieno [3,2-f] triazolo-1,2,4 [4,3-a] diazepine-1,4 (BN50730), which has affinity for intracellular binding sites, and the peripheral benzodiazepine receptor ligands 7-chloro-5- [4'-chlorophenyl]-1,3-dihydro-1-methyl-2H-1,4-benzodiazepin-2-one (Ro5-4864) and 1-(-2-chlorophenyl)-N-methyl-N-(1-methylpropyl)-3-isoquinolinecarboxamide (PK11195), inhibit PAF induction of PT and cytochrome c release. These results suggest that PAF excitotoxicity involves, at least in part, alterations of the mitochondrial membrane.
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Affiliation(s)
- Mark A Parker
- Neuroscience Center of Excellence, Louisiana State University Health Sciences Center, New Orleans, Louisiana 70112, USA
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Chen C, Magee JC, Bazan NG. Cyclooxygenase-2 regulates prostaglandin E2 signaling in hippocampal long-term synaptic plasticity. J Neurophysiol 2002; 87:2851-7. [PMID: 12037188 DOI: 10.1152/jn.2002.87.6.2851] [Citation(s) in RCA: 238] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The functional significance of cyclooxygenases (COX-1 and -2), the key enzymes that convert arachidonic acid (AA) to prostaglandins (PGs) in brain, is unclear, although they have been implicated in cellular functions and in some neurologic disorders, including stroke, epilepsy, and Alzheimer's disease. Recent evidence that COX-2 is expressed in postsynaptic dendritic spines (which are specialized structures involved in synaptic signaling) and is regulated by synaptic activity implies participation of COX-2 in neuronal plasticity. However, direct evidence is lacking. Here we demonstrate that selective COX-2 inhibitors significantly reduced postsynaptic membrane excitability, back-propagating dendritic action potential-associated Ca2+ influx, and long-term potentiation (LTP) induction in hippocampal dentate granule neurons, while a COX-1 inhibitor is ineffective. All of these actions were effectively reversed by exogenous application of PGE2 but not of PGD2 or PGF(2alpha). Our results indicate that COX-2-generated PGE2 regulates membrane excitability and long-term synaptic plasticity in hippocampal perforant path-dentate gyrus synapses.
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Affiliation(s)
- Chu Chen
- Neuroscience Center, School of Medicine, Louisiana State University Health Sciences Center, New Orleans, Louisiana 70112, USA.
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46
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Calcerrada MC, Catalan RE, Martinez AM. PAF-stimulated protein tyrosine phosphorylation in hippocampus: involvement of NO synthase. Neurochem Res 2002; 27:313-8. [PMID: 11958533 DOI: 10.1023/a:1014911329489] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The effect of platelet-activating factor (PAF) on protein tyrosine phosphorylation was studied in rat hippocampal slices. PAF caused an increase in the tyrosine phosphorylation of two phosphoproteins, which we identified by immunoprecipitation assays as the focal adhesion kinase p125FAK and crk-associated substrate p130Ca. The PAF effect was time- and dose-dependent. In addition, the involvement of PAF receptor was demonstrated by using PCA-4248, a specific receptor antagonist. When NO synthase was inhibited by NG-monomethyl-L-arginine (L-NMA), PAF-stimulated protein tyrosine phosphorylation was inhibited. In conclusion, our results indicate that PAF increased the tyrosine phosphorylation of both p125FAK and p130Cas proteins by the production of NO in hippocampus, suggesting that PAF may play a role in the functioning of this cerebral area.
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Affiliation(s)
- M C Calcerrada
- Departamento de Bioquímica y Biologia Molecular I, Facultad de Química, Universidad Complutense de Madrid, Spain
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47
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Rodriguez de Turco EB, Tang W, Topham MK, Sakane F, Marcheselli VL, Chen C, Taketomi A, Prescott SM, Bazan NG. Diacylglycerol kinase epsilon regulates seizure susceptibility and long-term potentiation through arachidonoyl- inositol lipid signaling. Proc Natl Acad Sci U S A 2001; 98:4740-5. [PMID: 11287665 PMCID: PMC31904 DOI: 10.1073/pnas.081536298] [Citation(s) in RCA: 144] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2000] [Indexed: 11/18/2022] Open
Abstract
Arachidonoyldiacylglycerol (20:4-DAG) is a second messenger derived from phosphatidylinositol 4,5-bisphosphate and generated by stimulation of glutamate metabotropic receptors linked to G proteins and activation of phospholipase C. 20:4-DAG signaling is terminated by its phosphorylation to phosphatidic acid, catalyzed by diacylglycerol kinase (DGK). We have cloned the murine DGKepsilon gene that showed, when expressed in COS-7 cells, selectivity for 20:4-DAG. The significance of DGKepsilon in synaptic function was investigated in mice with targeted disruption of the DGKepsilon. DGKepsilon(-/-) mice showed a higher resistance to electroconvulsive shock with shorter tonic seizures and faster recovery than DGKepsilon(+/+) mice. The phosphatidylinositol 4,5-bisphosphate-signaling pathway in cerebral cortex was greatly affected, leading to lower accumulation of 20:4-DAG and free 20:4. Also, long-term potentiation was attenuated in perforant path-dentate granular cell synapses. We propose that DGKepsilon contributes to modulate neuronal signaling pathways linked to synaptic activity, neuronal plasticity, and epileptogenesis.
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Affiliation(s)
- E B Rodriguez de Turco
- Neuroscience Center of Excellence and Department of Ophthalmology, Louisiana State University Health Sciences Center, New Orleans, LA 70112, USA
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