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Trinh PNH, Baltos JA, Hellyer SD, May LT, Gregory KJ. Adenosine receptor signalling in Alzheimer’s disease. Purinergic Signal 2022; 18:359-381. [PMID: 35870032 PMCID: PMC9391555 DOI: 10.1007/s11302-022-09883-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Accepted: 07/02/2022] [Indexed: 12/11/2022] Open
Abstract
Alzheimer’s disease (AD) is the most common dementia in the elderly and its increasing prevalence presents treatment challenges. Despite a better understanding of the disease, the current mainstay of treatment cannot modify pathogenesis or effectively address the associated cognitive and memory deficits. Emerging evidence suggests adenosine G protein-coupled receptors (GPCRs) are promising therapeutic targets for Alzheimer’s disease. The adenosine A1 and A2A receptors are expressed in the human brain and have a proposed involvement in the pathogenesis of dementia. Targeting these receptors preclinically can mitigate pathogenic β-amyloid and tau neurotoxicity whilst improving cognition and memory. In this review, we provide an accessible summary of the literature on Alzheimer’s disease and the therapeutic potential of A1 and A2A receptors. Although there are no available medicines targeting these receptors approved for treating dementia, we provide insights into some novel strategies, including allosterism and the targeting of oligomers, which may increase drug discovery success and enhance the therapeutic response.
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Affiliation(s)
- Phuc N. H. Trinh
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC 3052 Australia
- Department of Pharmacology, Monash University, Parkville, VIC 3052 Australia
| | - Jo-Anne Baltos
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC 3052 Australia
- Department of Pharmacology, Monash University, Parkville, VIC 3052 Australia
| | - Shane D. Hellyer
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC 3052 Australia
| | - Lauren T. May
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC 3052 Australia
- Department of Pharmacology, Monash University, Parkville, VIC 3052 Australia
| | - Karen J. Gregory
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC 3052 Australia
- Department of Pharmacology, Monash University, Parkville, VIC 3052 Australia
- ARC Centre for Cryo-Electron Microscopy of Membrane Proteins, Monash Institute of Pharmaceutical Sciences, Parkville, 3052 Australia
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2
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Chen ZH, Han YY, Shang YJ, Zhuang SY, Huang JN, Wu BY, Li CH. Cordycepin Ameliorates Synaptic Dysfunction and Dendrite Morphology Damage of Hippocampal CA1 via A1R in Cerebral Ischemia. Front Cell Neurosci 2022; 15:783478. [PMID: 35002628 PMCID: PMC8740211 DOI: 10.3389/fncel.2021.783478] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2021] [Accepted: 12/01/2021] [Indexed: 01/18/2023] Open
Abstract
Cordycepin exerted significant neuroprotective effects and protected against cerebral ischemic damage. Learning and memory impairments after cerebral ischemia are common. Cordycepin has been proved to improve memory impairments induced by cerebral ischemia, but its underlying mechanism has not been revealed yet. The plasticity of synaptic structure and function is considered to be one of the neural mechanisms of learning and memory. Therefore, we investigated how cordycepin benefits dendritic morphology and synaptic transmission after cerebral ischemia and traced the related molecular mechanisms. The effects of cordycepin on the protection against ischemia were studied by using global cerebral ischemia (GCI) and oxygen-glucose deprivation (OGD) models. Behavioral long-term potentiation (LTP) and synaptic transmission were observed with electrophysiological recordings. The dendritic morphology and histological assessment were assessed by Golgi staining and hematoxylin-eosin (HE) staining, respectively. Adenosine A1 receptors (A1R) and adenosine A2A receptors (A2AR) were evaluated with western blotting. The results showed that cordycepin reduced the GCI-induced dendritic morphology scathing and behavioral LTP impairment in the hippocampal CA1 area, improved the learning and memory abilities, and up-regulated the level of A1R but not A2AR. In the in vitro experiments, cordycepin pre-perfusion could alleviate the hippocampal slices injury and synaptic transmission cripple induced by OGD, accompanied by increased adenosine content. In addition, the protective effect of cordycepin on OGD-induced synaptic transmission damage was eliminated by using an A1R antagonist instead of A2AR. These findings revealed that cordycepin alleviated synaptic dysfunction and dendritic injury in ischemic models by modulating A1R, which provides new insights into the pharmacological mechanisms of cordycepin for ameliorating cognitive impairment induced by cerebral ischemia.
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Affiliation(s)
- Zhao-Hui Chen
- School of Life Science, South China Normal University, Guangzhou, China
| | - Yuan-Yuan Han
- School of Life Science, South China Normal University, Guangzhou, China.,Panyu Central Hospital, Guangzhou, China
| | - Ying-Jie Shang
- School of Life Science, South China Normal University, Guangzhou, China
| | - Si-Yi Zhuang
- School of Life Science, South China Normal University, Guangzhou, China
| | - Jun-Ni Huang
- School of Life Science, South China Normal University, Guangzhou, China
| | - Bao-Yan Wu
- Ministry of Education (MOE) Key Laboratory of Laser Life Science, Institute of Laser Life Science, College of Biophotonics, South China Normal University, Guangzhou, China
| | - Chu-Hua Li
- School of Life Science, South China Normal University, Guangzhou, China
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3
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Adenosine Signaling and Clathrin-Mediated Endocytosis of Glutamate AMPA Receptors in Delayed Hypoxic Injury in Rat Hippocampus: Role of Casein Kinase 2. Mol Neurobiol 2021; 58:1932-1951. [PMID: 33415682 PMCID: PMC8018935 DOI: 10.1007/s12035-020-02246-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2019] [Accepted: 12/03/2020] [Indexed: 11/20/2022]
Abstract
Chronic adenosine A1R stimulation in hypoxia leads to persistent hippocampal synaptic depression, while unopposed adenosine A2AR receptor stimulation during hypoxia/reperfusion triggers adenosine-induced post-hypoxia synaptic potentiation (APSP) and increased neuronal death. Still, the mechanisms responsible for this adenosine-mediated neuronal damage following hypoxia need to be fully elucidated. We tested the hypothesis that A1R and A2AR regulation by protein kinase casein kinase 2 (CK2) and clathrin-dependent endocytosis of AMPARs both contribute to APSPs and neuronal damage. The APSPs following a 20-min hypoxia recorded from CA1 layer of rat hippocampal slices were abolished by A1R and A2AR antagonists and by broad-spectrum AMPAR antagonists. The inhibitor of GluA2 clathrin-mediated endocytosis Tat-GluA2-3Y peptide and the dynamin-dependent endocytosis inhibitor dynasore both significantly inhibited APSPs. The CK2 antagonist DRB also inhibited APSPs and, like hypoxic treatment, caused opposite regulation of A1R and A2AR surface expression. APSPs were abolished when calcium-permeable AMPAR (CP-AMPAR) antagonist (IEM or philanthotoxin) or non-competitive AMPAR antagonist perampanel was applied 5 min after hypoxia. In contrast, perampanel, but not CP-AMPAR antagonists, abolished APSPs when applied during hypoxia/reperfusion. To test for neuronal viability after hypoxia, propidium iodide staining revealed significant neuroprotection of hippocampal CA1 pyramidal neurons when pretreated with Tat-GluA2-3Y peptide, CK2 inhibitors, dynamin inhibitor, CP-AMPAR antagonists (applied 5 min after hypoxia), and perampanel (either at 5 min hypoxia onset or during APSP). These results suggest that the A1R-CK2-A2AR signaling pathway in hypoxia/reperfusion injury model mediates increased hippocampal synaptic transmission and neuronal damage via calcium-permeable AMPARs that can be targeted by perampanel for neuroprotective stroke therapy.
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4
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Spanoghe J, Larsen LE, Craey E, Manzella S, Van Dycke A, Boon P, Raedt R. The Signaling Pathways Involved in the Anticonvulsive Effects of the Adenosine A 1 Receptor. Int J Mol Sci 2020; 22:ijms22010320. [PMID: 33396826 PMCID: PMC7794785 DOI: 10.3390/ijms22010320] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2020] [Revised: 12/22/2020] [Accepted: 12/27/2020] [Indexed: 12/20/2022] Open
Abstract
Adenosine acts as an endogenous anticonvulsant and seizure terminator in the brain. Many of its anticonvulsive effects are mediated through the activation of the adenosine A1 receptor, a G protein-coupled receptor with a wide array of targets. Activating A1 receptors is an effective approach to suppress seizures. This review gives an overview of the neuronal targets of the adenosine A1 receptor focusing in particular on signaling pathways resulting in neuronal inhibition. These include direct interactions of G protein subunits, the adenyl cyclase pathway and the phospholipase C pathway, which all mediate neuronal hyperpolarization and suppression of synaptic transmission. Additionally, the contribution of the guanyl cyclase and mitogen-activated protein kinase cascades to the seizure-suppressing effects of A1 receptor activation are discussed. This review ends with the cautionary note that chronic activation of the A1 receptor might have detrimental effects, which will need to be avoided when pursuing A1 receptor-based epilepsy therapies.
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Affiliation(s)
- Jeroen Spanoghe
- 4Brain, Department of Head and Skin, Ghent University, 9000 Ghent, Belgium; (J.S.); (L.E.L.); (E.C.); (S.M.); (P.B.)
| | - Lars E. Larsen
- 4Brain, Department of Head and Skin, Ghent University, 9000 Ghent, Belgium; (J.S.); (L.E.L.); (E.C.); (S.M.); (P.B.)
| | - Erine Craey
- 4Brain, Department of Head and Skin, Ghent University, 9000 Ghent, Belgium; (J.S.); (L.E.L.); (E.C.); (S.M.); (P.B.)
| | - Simona Manzella
- 4Brain, Department of Head and Skin, Ghent University, 9000 Ghent, Belgium; (J.S.); (L.E.L.); (E.C.); (S.M.); (P.B.)
| | - Annelies Van Dycke
- Department of Neurology, General Hospital Sint-Jan Bruges, 8000 Bruges, Belgium;
| | - Paul Boon
- 4Brain, Department of Head and Skin, Ghent University, 9000 Ghent, Belgium; (J.S.); (L.E.L.); (E.C.); (S.M.); (P.B.)
| | - Robrecht Raedt
- 4Brain, Department of Head and Skin, Ghent University, 9000 Ghent, Belgium; (J.S.); (L.E.L.); (E.C.); (S.M.); (P.B.)
- Correspondence:
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5
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Zhang Y, Cao H, Qiu X, Xu D, Chen Y, Barnes GN, Tu Y, Gyabaah AT, Gharbal AHAA, Peng C, Cai J, Cai X. Neuroprotective Effects of Adenosine A1 Receptor Signaling on Cognitive Impairment Induced by Chronic Intermittent Hypoxia in Mice. Front Cell Neurosci 2020; 14:202. [PMID: 32733207 PMCID: PMC7363980 DOI: 10.3389/fncel.2020.00202] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2020] [Accepted: 06/09/2020] [Indexed: 12/18/2022] Open
Abstract
Obstructive sleep apnea-hypopnea syndrome (OSAHS) is a breathing disorder associated with cognitive impairment. However, the mechanisms leading to cognitive deficits in OSAHS remain uncertain. In this study, a mouse model of chronic intermittent hypoxia (CIH) exposures were applied for simulating the deoxygenation-reoxygenation events occurring in OSAHS. The conventional adenosine A1 receptor gene (A1R) knockout mice and the A1R agonist CCPA- or antagonist DPCPX-administrated mice were utilized to determine the precise function of A1R signaling in the process of OSAHS-relevant cognitive impairment. We demonstrated that CIH induced morphological changes and apoptosis in hippocampal neurons. Further, CIH blunted hippocampal long-term potentiation (LTP) and resulted in learning/memory impairment. Disruption of adenosine A1R exacerbated morphological, cellular, and functional damage induced by CIH. In contrast, activation of adenosine A1R signaling reduced morphological changes and apoptosis of hippocampal neurons, promoted LTP, and enhanced learning and memory. A1Rs may up-regulate protein kinase C (PKC) and its subtype PKC-ζ through the activation of Gα(i) improve spatial learning and memory disorder induced by CIH in mice. Taken together, A1R signaling plays a neuroprotective role in CIH-induced cognitive dysfunction and pathological changes in the hippocampus.
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Affiliation(s)
- Yichun Zhang
- Department of Pediatrics, The Second Affiliated Hospital and Yuying Children's Hospital, Wenzhou Medical University, Wenzhou, China
| | - Hongchao Cao
- Department of Pediatrics, The Second Affiliated Hospital and Yuying Children's Hospital, Wenzhou Medical University, Wenzhou, China.,Department of Internal Medicine, Hwa Mei Hospital, University of Chinese Academy of Sciences (Ningbo No. 2 Hospital), Ningbo, China
| | - Xuehao Qiu
- Department of Pediatrics, The Second Affiliated Hospital and Yuying Children's Hospital, Wenzhou Medical University, Wenzhou, China
| | - Danfen Xu
- Department of Pediatrics, The Second Affiliated Hospital and Yuying Children's Hospital, Wenzhou Medical University, Wenzhou, China
| | - Yifeng Chen
- Department of Pediatrics, The Second Affiliated Hospital and Yuying Children's Hospital, Wenzhou Medical University, Wenzhou, China
| | - Gregory N Barnes
- Department of Neurology, University of Louisville School of Medicine, Louisville, KY, United States.,Department of Pediatrics, Pediatric Research Institute, University of Louisville School of Medicine, Louisville, KY, United States
| | - Yunjia Tu
- Department of Pediatrics, The Second Affiliated Hospital and Yuying Children's Hospital, Wenzhou Medical University, Wenzhou, China
| | - Adwoa Takyiwaa Gyabaah
- Department of Pediatrics, The Second Affiliated Hospital and Yuying Children's Hospital, Wenzhou Medical University, Wenzhou, China
| | | | - Chenlei Peng
- Department of Pediatrics, The Second Affiliated Hospital and Yuying Children's Hospital, Wenzhou Medical University, Wenzhou, China.,Department of Internal Medicine, Hwa Mei Hospital, University of Chinese Academy of Sciences (Ningbo No. 2 Hospital), Ningbo, China
| | - Jun Cai
- Department of Pediatrics, Pediatric Research Institute, University of Louisville School of Medicine, Louisville, KY, United States
| | - Xiaohong Cai
- Department of Pediatrics, The Second Affiliated Hospital and Yuying Children's Hospital, Wenzhou Medical University, Wenzhou, China
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6
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Caruana DA, Dudek SM. Adenosine A 1 Receptor-Mediated Synaptic Depression in the Developing Hippocampal Area CA2. Front Synaptic Neurosci 2020; 12:21. [PMID: 32612520 PMCID: PMC7307308 DOI: 10.3389/fnsyn.2020.00021] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2020] [Accepted: 05/04/2020] [Indexed: 12/22/2022] Open
Abstract
Immunolabeling for adenosine A1 receptors (A1Rs) is high in hippocampal area CA2 in adult rats, and the potentiating effects of caffeine or other A1R-selective antagonists on synaptic responses are particularly robust at Schaffer collateral synapses in CA2. Interestingly, the pronounced staining for A1Rs in CA2 is not apparent until rats are 4 weeks old, suggesting that developmental changes other than receptor distribution underlie the sensitivity of CA2 synapses to A1R antagonists in young animals. To evaluate the role of A1R-mediated postsynaptic signals at these synapses, we tested whether A1R agonists regulate synaptic transmission at Schaffer collateral inputs to CA2 and CA1. We found that the selective A1R agonist CCPA caused a lasting depression of synaptic responses in both CA2 and CA1 neurons in slices obtained from juvenile rats (P14), but that the effect was observed only in CA2 in slices prepared from adult animals (~P70). Interestingly, blocking phosphodiesterase activity with rolipram inhibited the CCPA-induced depression in CA1, but not in CA2, indicative of robust phosphodiesterase activity in CA1 neurons. Likewise, synaptic responses in CA2 and CA1 differed in their sensitivity to the adenylyl cyclase activator, forskolin, in that it increased synaptic transmission in CA2, but had little effect in CA1. These findings suggest that the A1R-mediated synaptic depression tracks the postnatal development of immunolabeling for A1Rs and that the enhanced sensitivity to antagonists in CA2 at young ages is likely due to robust adenylyl cyclase activity and weak phosphodiesterase activity rather than to enrichment of A1Rs.
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Affiliation(s)
- Douglas A Caruana
- School of Life and Health Sciences, Aston University, Birmingham, United Kingdom.,Neurobiology Laboratory, National Institute of Environmental Health Sciences (NIEHS), National Institutes of Health, Research Triangle Park, NC, United States
| | - Serena M Dudek
- Neurobiology Laboratory, National Institute of Environmental Health Sciences (NIEHS), National Institutes of Health, Research Triangle Park, NC, United States
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7
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Lv YC, Gao AB, Yang J, Zhong LY, Jia B, Ouyang SH, Gui L, Peng TH, Sun S, Cayabyab FS. Long-term adenosine A1 receptor activation-induced sortilin expression promotes α-synuclein upregulation in dopaminergic neurons. Neural Regen Res 2020; 15:712-723. [PMID: 31638096 PMCID: PMC6975149 DOI: 10.4103/1673-5374.266916] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Prolonged activation of adenosine A1 receptor likely leads to damage of dopaminergic neurons and subsequent development of neurodegenerative diseases. However, the pathogenesis underlying long-term adenosine A1 receptor activation-induced neurodegeneration remains unclear. In this study, rats were intraperitoneally injected with 5 mg/kg of the adenosine A1 receptor agonist N6-cyclopentyladenosine (CPA) for five weeks. The mobility of rats was evaluated by forced swimming test, while their cognitive capabilities were evaluated by Y-maze test. Expression of sortilin, α-synuclein, p-JUN, and c-JUN proteins in the substantia nigra were detected by western blot analysis. In addition, immunofluorescence staining of sortilin and α-synuclein was performed to detect expression in the substantia nigra. The results showed that, compared with adenosine A1 receptor antagonist 8-cyclopentyl-1,3-dipropylxanthine (5 mg/kg) + CPA co-treated rats, motor and memory abilities were reduced, surface expression of sortin and α-synuclein in dopaminergic neurons was reduced, and total sortilin and total α-synuclein were increased in CPA-treated rats. MN9D cells were incubated with 500 nM CPA alone or in combination with 10 μM SP600125 (JNK inhibitor) for 48 hours. Quantitative real-time polymerase chain reaction analysis of sortilin and α-synuclein mRNA levels in MN9D cells revealed upregulated sortilin expression in MN9D cells cultured with CPA alone, but the combination of CPA and SP600125 could inhibit this expression. Predictions made using Jasper, PROMO, and Alibaba online databases identified a highly conserved sequence in the sortilin promoter that was predicted to bind JUN in both humans and rodents. A luciferase reporter assay of sortilin promoter plasmid-transfected HEK293T cells confirmed this prediction. After sortilin expression was inhibited by sh-SORT1, expression of p-JUN and c-JUN was detected by western blot analysis. Long-term adenosine A1 receptor activation levels upregulated α-synuclein expression at the post-transcriptional level by affecting sortilin expression. The online tool Raptor-X-Binding and Discovery Studio 4.5 prediction software predicted that sortilin can bind to α-synuclein. Co-immunoprecipitation revealed an interaction between sortilin and α-synuclein in MN9D cells. Our findings indicate that suppression of prolonged adenosine A1 receptor activation potently inhibited sortilin expression and α-synuclein accumulation, and dramatically improved host cognition and kineticism. This study was approved by the University Committee of Animal Care and Supply at the University of Saskatchewan (approval No. AUP#20070090) in March 2007 and the Animals Ethics Committee of University of South China (approval No. LL0387-USC) in June 2017.
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Affiliation(s)
- Yun-Cheng Lv
- Clinical Anatomy & Reproductive Medicine Application Institute, Hengyang Medical College, University of South China, Hengyang, Hunan Province, China; Department of Surgery, College of Medicine, University of Saskatchewan, Saskatoon, Canada
| | - An-Bo Gao
- Clinical Anatomy & Reproductive Medicine Application Institute, Hengyang Medical College; Institute of Pharmacy and Pharmacology, School of Pharmaceutical Science, University of South China, Hengyang, Hunan Province, China
| | - Jing Yang
- Department of Metabolism & Endocrinology, the First Affiliated Hospital, Hengyang Medical College, University of South China, Hengyang, Hunan Province, China
| | - Li-Yuan Zhong
- Clinical Anatomy & Reproductive Medicine Application Institute, Hengyang Medical College, University of South China, Hengyang, Hunan Province, China
| | - Bo Jia
- Clinical Anatomy & Reproductive Medicine Application Institute, Hengyang Medical College, University of South China, Hengyang, Hunan Province, China
| | - Shu-Hui Ouyang
- Clinical Anatomy & Reproductive Medicine Application Institute, Hengyang Medical College, University of South China, Hengyang, Hunan Province, China
| | - Le Gui
- Department of Surgery, College of Medicine, University of Saskatchewan, Saskatoon, Canada
| | - Tian-Hong Peng
- Clinical Anatomy & Reproductive Medicine Application Institute, Hengyang Medical College, University of South China, Hengyang, Hunan Province, China
| | - Sha Sun
- Clinical Anatomy & Reproductive Medicine Application Institute, Hengyang Medical College, University of South China, Hengyang, Hunan Province, China
| | - Francisco S Cayabyab
- Department of Surgery, College of Medicine, University of Saskatchewan, Saskatoon, Canada
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8
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Alves ACDB, Bristot VJDO, Limana MD, Speck AE, Barros LSD, Solano AF, Aguiar AS. Role of Adenosine A 2A Receptors in the Central Fatigue of Neurodegenerative Diseases. J Caffeine Adenosine Res 2019. [DOI: 10.1089/caff.2019.0009] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Affiliation(s)
- Ana Cristina de Bem Alves
- Exercise Biology Lab, Department of Health Sciences, UFSC—Universidade Federal de Santa Catarina, Araranguá, Brazil
| | | | - Mirieli Denardi Limana
- Exercise Biology Lab, Department of Health Sciences, UFSC—Universidade Federal de Santa Catarina, Araranguá, Brazil
| | - Ana Elisa Speck
- Exercise Biology Lab, Department of Health Sciences, UFSC—Universidade Federal de Santa Catarina, Araranguá, Brazil
| | - Leonardo Soares de Barros
- LABOX—Laboratório de Bioenergética e Estresse Oxidativo, Departamento de Bioquímica, UFSC—Universidade Federal de Santa Catarina, Florianópolis, Brazil
| | - Alexandre Francisco Solano
- LABOX—Laboratório de Bioenergética e Estresse Oxidativo, Departamento de Bioquímica, UFSC—Universidade Federal de Santa Catarina, Florianópolis, Brazil
| | - Aderbal S. Aguiar
- Exercise Biology Lab, Department of Health Sciences, UFSC—Universidade Federal de Santa Catarina, Araranguá, Brazil
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9
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Temperoammonic Stimulation Depotentiates Schaffer Collateral LTP via p38 MAPK Downstream of Adenosine A1 Receptors. J Neurosci 2019; 39:1783-1792. [PMID: 30622168 DOI: 10.1523/jneurosci.1362-18.2018] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2018] [Revised: 12/17/2018] [Accepted: 12/31/2018] [Indexed: 01/12/2023] Open
Abstract
We previously found that low-frequency stimulation of direct temperoammonic (TA) inputs to hippocampal area CA1 depotentiates previously established long-term potentiation in the Schaffer collateral (SC) pathway through complex signaling involving dopamine, endocannabinoids, neuregulin-1, GABA, and adenosine, with adenosine being the most distal modulator identified to date. In the present studies, we examined mechanisms contributing to the effects of adenosine in hippocampal slices from male albino rats. We found that extracellular conversion of ATP to adenosine via an ectonucleotidase contributes significantly to TA-mediated SC depotentiation and the depotentiation resulting from block of adenosine transport. Adenosine-mediated SC depotentiation does not involve activation of c-Jun N-terminal protein kinase, serine phosphatases, or nitric oxide synthase, unlike homosynaptic SC depotentiation. Rather, adenosine-induced depotentiation is inhibited by specific antagonists of p38 MAPK, but not by a structural analog that does not inhibit p38. Additionally, using antagonists with relative selectivity for p38 subtypes, it appears that TA-induced SC depotentiation most likely involves p38 MAPK β. These findings have implications for understanding the role of adenosine and other extrahippocampal and intrahippocampal modulators in regulating SC synaptic function and the contributions of these modulators to the cognitive dysfunction associated with neuropsychiatric illnesses.SIGNIFICANCE STATEMENT Low-frequency stimulation of temperoammonic (TA) inputs to stratum lacunosum moleculare of hippocampal area CA1 heterosynaptically depotentiates long-term potentiation of Schaffer collateral (SC) synapses. TA-induced SC depotentiation involves complex signaling including dopamine, endocannabinoids, GABA, and adenosine, with adenosine serving as the most downstream messenger in the cascade identified to date. The present results indicate that TA-induced depotentiation requires intact inputs from entorhinal cortex and that adenosine ultimately drives depotentiation via activation of p38 MAPK. These studies have implications for understanding the cognitive dysfunction of psychiatric illnesses and certain abused drugs.
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10
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Lanigan SM, O'Connor JJ. Prolyl hydroxylase domain inhibitors: can multiple mechanisms be an opportunity for ischemic stroke? Neuropharmacology 2018; 148:117-130. [PMID: 30578795 DOI: 10.1016/j.neuropharm.2018.12.021] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2018] [Revised: 12/17/2018] [Accepted: 12/18/2018] [Indexed: 12/19/2022]
Abstract
Stroke and cerebrovascular disease are now the fifth most common cause of death behind other diseases such as heart, cancer and respiratory disease and accounts for approximately 40-50 fatalities per 100,000 people each year in the United States. Currently the only therapy for acute stroke, is intravenous administration of tissue plasminogen activator which was approved in 1996 by the FDA. Surprisingly no new treatments have come on the market since, although endovascular mechanical thrombectomy is showing promising results in trials. Recently focus has shifted towards a preventative therapy rather than trying to reverse or limit the amount of damage occurring following stroke onset. During one of the components of ischemia, hypoxia, a number of physiological changes occur within neurons which include the stabilization of hypoxia-inducible factors. The activity of these proteins is regulated by O2, Fe2+, 2-OG and ascorbate-dependant hydroxylases which contain prolyl-4-hydroxylase domains (PHDs). PHD inhibitors are capable of pharmacologically activating the body's own endogenous adaptive response to low levels of oxygen and have therefore become an attractive therapeutic target for treating ischemia. They have been widely used in the periphery and have been shown to have a preconditioning and protective effect against a later and more severe ischemic insult. Currently there are a number of these agents in phase 1, 2 and 3 clinical trials for the treatment of anemia. In this review we assess the neuroprotective effects of PHD inhibitors, including dimethyloxalylglycine and deferoxamine and suggest that not all of their effects in the CNS are HIF-dependent. Unravelling new roles and a better understanding of the function of PHD inhibitors in the CNS may be of great benefit especially when investigating their use in the treatment of stroke and other ischemic diseases.
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Affiliation(s)
- Sinead M Lanigan
- UCD School of Biomolecular & Biomedical Science, UCD Conway Institute of Biomolecular & Biomedical Research, University College Dublin, Belfield, Dublin 4, Ireland
| | - John J O'Connor
- UCD School of Biomolecular & Biomedical Science, UCD Conway Institute of Biomolecular & Biomedical Research, University College Dublin, Belfield, Dublin 4, Ireland.
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11
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Synaptic transmission and excitability during hypoxia with inflammation and reoxygenation in hippocampal CA1 neurons. Neuropharmacology 2018; 138:20-31. [PMID: 29775678 DOI: 10.1016/j.neuropharm.2018.05.011] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2018] [Revised: 04/19/2018] [Accepted: 05/08/2018] [Indexed: 12/30/2022]
Abstract
Although a number of experimental and clinical studies have shown that hypoxia typically accompanies acute inflammatory responses, the combinatorial effect of the two insults on basic neural function has not been thoroughly investigated. Previous studies have predominantly suggested that hypoxia reduces network activity; however, several studies suggest the opposite effect. Of note, inflammation is known to increase neural activity. In the current study, we examined the effects of limited oxygen in combination with an inflammatory stimulus, as well as the effects of reoxygenation, on synaptic transmission and excitability. We observed a significant reduction of both synaptic transmission and excitability when hypoxia and inflammation occurred in combination, whereas reoxygenation caused hyperexcitability of neurons. Further, we found that the observed reduction in synaptic transmission was due to compromised presynaptic release efficiency based on an adenosine-receptor-dependent increase in synaptic facilitation. Excitability changes in both directions were attributable to dynamic regulation of the hyperpolarization-activated cation current (Ih) and to changes in the input resistance and the voltage difference between resting membrane potential and action potential threshold. We found that zatebradine, an Ih current inhibitor, reduced the fluctuation in excitability, suggesting that it may have potential as a drug to ameliorate reperfusion brain injury.
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Bai HH, Liu JP, Yang L, Zhao JY, Suo ZW, Yang X, Hu XD. Adenosine A1 receptor potentiated glycinergic transmission in spinal cord dorsal horn of rats after peripheral inflammation. Neuropharmacology 2017; 126:158-167. [DOI: 10.1016/j.neuropharm.2017.09.001] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2017] [Revised: 08/30/2017] [Accepted: 09/02/2017] [Indexed: 12/12/2022]
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Neuregulin and Dopamine D4 Receptors Contribute Independently to Depotentiation of Schaffer Collateral LTP by Temperoammonic Path Stimulation. eNeuro 2017; 4:eN-NWR-0176-17. [PMID: 28828402 PMCID: PMC5563842 DOI: 10.1523/eneuro.0176-17.2017] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2017] [Revised: 07/14/2017] [Accepted: 08/07/2017] [Indexed: 11/21/2022] Open
Abstract
Prior studies have found that dopamine (DA), acting at D4 receptors, and neuregulin (NRG), likely acting at ErbB4 receptors, are involved in a form of depotentiation of long-term potentiation (LTP) at Schaffer collateral (SC) synapses in the hippocampus. Furthermore, DA and NRG actions are intertwined in that NRG induces DA release. We previously found that low-frequency stimulation (LFS) of temperoammonic (TA) inputs to area CA1 also depotentiates previously established SC LTP through a complex signaling pathway involving endocannabinoids, GABA, adenosine, and mitogen-activated protein kinases (MAPKs), but not glutamate. In the present studies, we found that TA-induced SC depotentiation in hippocampal slices from Sprague-Dawley albino rats also involves activation of both D4 receptors and NRG-activated ErbB receptors, but that the roles of these two modulator systems are independent with D4 receptor antagonism failing to alter chemical depotentiation by NRG1β. Furthermore, a selective D4 receptor agonist was unable to depotentiate SC LTP when administered alone, suggesting that D4 receptor activation is necessary but not sufficient for TA-induced SC depotentiation. Chemical depotentiation by NRG1β was inhibited by a Pan-ErbB antagonist and by picrotoxin (PTX), an antagonist of GABA-A receptors (GABAARs), indicating that NRG likely promotes SC depotentiation via effects on GABA and interneurons. These findings have implications for understanding the role of DA and NRG in cognitive dysfunction associated with neuropsychiatric illnesses.
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14
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Adenosine A1 and A2A Receptors in the Brain: Current Research and Their Role in Neurodegeneration. Molecules 2017; 22:molecules22040676. [PMID: 28441750 PMCID: PMC6154612 DOI: 10.3390/molecules22040676] [Citation(s) in RCA: 114] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2017] [Revised: 04/21/2017] [Accepted: 04/21/2017] [Indexed: 12/20/2022] Open
Abstract
The inhibitory adenosine A1 receptor (A1R) and excitatory A2A receptor (A2AR) are predominantly expressed in the brain. Whereas the A2AR has been implicated in normal aging and enhancing neurotoxicity in multiple neurodegenerative diseases, the inhibitory A1R has traditionally been ascribed to have a neuroprotective function in various brain insults. This review provides a summary of the emerging role of prolonged A1R signaling and its potential cross-talk with A2AR in the cellular basis for increased neurotoxicity in neurodegenerative disorders. This A1R signaling enhances A2AR-mediated neurodegeneration, and provides a platform for future development of neuroprotective agents in stroke, Parkinson’s disease and epilepsy.
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McHugh WM, Russell WW, Fleszar AJ, Rodenhouse PE, Rietberg SP, Sun L, Shanley TP, Cornell TT. Protein phosphatase 2A activation attenuates inflammation in murine models of acute lung injury. Am J Physiol Lung Cell Mol Physiol 2016; 311:L903-L912. [PMID: 27638902 DOI: 10.1152/ajplung.00007.2016] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2016] [Accepted: 09/11/2016] [Indexed: 12/27/2022] Open
Abstract
Acute respiratory distress syndrome (ARDS) remains a leading cause of morbidity and mortality in both adult and pediatric intensive care units. A key event in the development of ARDS is neutrophil recruitment into the lungs leading to tissue damage and destruction. Interleukin-8 (IL-8) is the major human chemokine responsible for neutrophil recruitment into the lungs. Protein phosphatase 2A (PP2A) has been shown to be a key regulator of the mitogen-activated protein kinase (MAPK) cascades, which control the production of IL-8. Previously, our laboratory employed an in vitro model to show that inhibition of PP2A results in an increase in IL-8 production in human alveolar epithelial cells. The objective of this study was to determine whether PP2A regulated this response in vivo by investigating the impact of pharmacologic activation of PP2A on chemokine production and activation of the MAPK cascade and lung injury using endotoxin- and bacterial-challenge models of ARDS in mice. N6-cyclopentyladenosine (N6-CPA) increased PP2A activity and inhibited endotoxin-induced cytokine production in a murine alveolar macrophage cell line. N6-CPA pretreatment in mice challenged with intratracheal endotoxin decreased chemokine production, reduced neutrophil infiltration, and attenuated lung injury. Following initiation of lung injury with live Pseudomonas aeruginosa, mice that received N6-CPA 4 h following bacterial challenge showed attenuated chemokine production and reduced neutrophil infiltration compared with control mice. Pharmacologic PP2A activation both limited and prevented inflammation and tissue injury in two direct injury models of ARDS. These results suggest modulation of PP2A activity as a therapeutic target in ARDS.
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Affiliation(s)
- Walker M McHugh
- Division of Pediatric Critical Care Medicine, Department of Pediatrics and Communicable Diseases, University of Michigan School of Medicine, and C. S. Mott Children's Hospital, University of Michigan, Ann Arbor, Michigan
| | - William W Russell
- Division of Pediatric Critical Care Medicine, Department of Pediatrics and Communicable Diseases, University of Michigan School of Medicine, and C. S. Mott Children's Hospital, University of Michigan, Ann Arbor, Michigan
| | - Andrew J Fleszar
- Division of Pediatric Critical Care Medicine, Department of Pediatrics and Communicable Diseases, University of Michigan School of Medicine, and C. S. Mott Children's Hospital, University of Michigan, Ann Arbor, Michigan
| | - Paul E Rodenhouse
- Division of Pediatric Critical Care Medicine, Department of Pediatrics and Communicable Diseases, University of Michigan School of Medicine, and C. S. Mott Children's Hospital, University of Michigan, Ann Arbor, Michigan
| | - Skyler P Rietberg
- Division of Pediatric Critical Care Medicine, Department of Pediatrics and Communicable Diseases, University of Michigan School of Medicine, and C. S. Mott Children's Hospital, University of Michigan, Ann Arbor, Michigan
| | - Lei Sun
- Division of Pediatric Critical Care Medicine, Department of Pediatrics and Communicable Diseases, University of Michigan School of Medicine, and C. S. Mott Children's Hospital, University of Michigan, Ann Arbor, Michigan
| | - Thomas P Shanley
- Division of Pediatric Critical Care Medicine, Department of Pediatrics and Communicable Diseases, University of Michigan School of Medicine, and C. S. Mott Children's Hospital, University of Michigan, Ann Arbor, Michigan
| | - Timothy T Cornell
- Division of Pediatric Critical Care Medicine, Department of Pediatrics and Communicable Diseases, University of Michigan School of Medicine, and C. S. Mott Children's Hospital, University of Michigan, Ann Arbor, Michigan
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Zhai W, Chen D, Shen H, Chen Z, Li H, Yu Z, Chen G. A1 adenosine receptor attenuates intracerebral hemorrhage-induced secondary brain injury in rats by activating the P38-MAPKAP2-Hsp27 pathway. Mol Brain 2016; 9:66. [PMID: 27301321 PMCID: PMC4908780 DOI: 10.1186/s13041-016-0247-x] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2016] [Accepted: 06/02/2016] [Indexed: 12/27/2022] Open
Abstract
Background This study was designed to determine the role of the A1 adenosine receptors in intracerebral hemorrhage (ICH)-induced secondary brain injury and the underlying mechanisms. Methods A collagenase-induced ICH model was established in Sprague–Dawley rats, and cultured primary rat cortical neurons were exposed to oxyhemoglobin at a concentration of 10 μM to mimic ICH in vitro. The A1 adenosine receptor agonist N(6)-cyclohexyladenosine and antagonist 8-phenyl-1,3-dipropylxanthine were used to study the role of A1 adenosine receptor in ICH-induced secondary brain injury, and antagonists of P38 and Hsp27 were used to study the underlying mechanisms of A1 adenosine receptor actions. Results The protein level of A1 adenosine receptor was significantly increased by ICH, while there was no significant change in protein levels of the other 3 adenosine receptors. In addition, the A1 adenosine receptor expression could be increased by N(6)-cyclohexyladenosine and decreased by 8-phenyl-1,3-dipropylxanthine under ICH conditions. Activation of the A1 adenosine receptor attenuated neuronal apoptosis in the subcortex, which was associated with increased phosphorylation of P38, MAPK, MAPKAP2, and Hsp27. Inhibition of the A1 adenosine receptor resulted in opposite effects. Finally, the neuroprotective effect of the A1 adenosine receptor agonist N(6)-cyclohexyladenosine was inhibited by antagonists of P38 and Hsp27. Conclusions This study demonstrates that activation of the A1 adenosine receptor by N(6)-cyclohexyladenosine could prevent ICH-induced secondary brain injury via the P38-MAPKAP2-Hsp27 pathway.
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Affiliation(s)
- Weiwei Zhai
- Department of Neurosurgery & Brain and Nerve Research Laboratory, The First Affiliated Hospital of Soochow University, 188 Shizi Street, Suzhou, 215006, China
| | - Dongdong Chen
- Department of Neurosurgery & Brain and Nerve Research Laboratory, The First Affiliated Hospital of Soochow University, 188 Shizi Street, Suzhou, 215006, China
| | - Haitao Shen
- Department of Neurosurgery & Brain and Nerve Research Laboratory, The First Affiliated Hospital of Soochow University, 188 Shizi Street, Suzhou, 215006, China
| | - Zhouqing Chen
- Department of Neurosurgery & Brain and Nerve Research Laboratory, The First Affiliated Hospital of Soochow University, 188 Shizi Street, Suzhou, 215006, China
| | - Haiying Li
- Department of Neurosurgery & Brain and Nerve Research Laboratory, The First Affiliated Hospital of Soochow University, 188 Shizi Street, Suzhou, 215006, China
| | - Zhengquan Yu
- Department of Neurosurgery & Brain and Nerve Research Laboratory, The First Affiliated Hospital of Soochow University, 188 Shizi Street, Suzhou, 215006, China.
| | - Gang Chen
- Department of Neurosurgery & Brain and Nerve Research Laboratory, The First Affiliated Hospital of Soochow University, 188 Shizi Street, Suzhou, 215006, China.
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Pinto I, Serpa A, Sebastião AM, Cascalheira JF. The Role of cGMP on Adenosine A 1 Receptor-mediated Inhibition of Synaptic Transmission at the Hippocampus. Front Pharmacol 2016; 7:103. [PMID: 27148059 PMCID: PMC4840265 DOI: 10.3389/fphar.2016.00103] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2016] [Accepted: 04/05/2016] [Indexed: 01/14/2023] Open
Abstract
Both adenosine A1 receptor and cGMP inhibit synaptic transmission at the hippocampus and recently it was found that A1 receptor increased cGMP levels in hippocampus, but the role of cGMP on A1 receptor-mediated inhibition of synaptic transmission remains to be established. In the present work we investigated if blocking the NOS/sGC/cGMP/PKG pathway using nitric oxide synthase (NOS), protein kinase G (PKG), and soluble guanylyl cyclase (sGC) inhibitors modify the A1 receptor effect on synaptic transmission. Neurotransmission was evaluated by measuring the slope of field excitatory postsynaptic potentials (fEPSPs) evoked by electrical stimulation at hippocampal slices. N6-cyclopentyladenosine (CPA, 15 nM), a selective A1 receptor agonist, reversibly decreased the fEPSPs by 54 ± 5%. Incubation of the slices with an inhibitor of NOS (L-NAME, 200 μM) decreased the CPA effect on fEPSPs by 57 ± 9% in female rats. In males, ODQ (10 μM), an sGC inhibitor, decreased the CPA inhibitory effect on fEPSPs by 23 ± 6%, but only when adenosine deaminase (ADA,1 U/ml) was present; similar results were found in females, where ODQ decreased CPA-induced inhibition of fEPSP slope by 23 ± 7%. In male rats, the presence of the PKG inhibitor (KT5823, 1 nM) decreased the CPA effect by 45.0 ± 9%; similar results were obtained in females, where KT5823 caused a 32 ± 9% decrease on the CPA effect. In conclusion, the results suggest that the inhibitory action of adenosine A1 receptors on synaptic transmission at hippocampus is, in part, mediated by the NOS/sGC/cGMP/PKG pathway.
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Affiliation(s)
- Isa Pinto
- CICS-UBI - Health Sciences Research Center, University of Beira Interior Covilhã, Portugal
| | - André Serpa
- CICS-UBI - Health Sciences Research Center, University of Beira Interior Covilhã, Portugal
| | - Ana M Sebastião
- Institute of Pharmacology and Neurosciences, Faculty of Medicine, University of LisbonLisboa, Portugal; Institute of Molecular Medicine, University of LisbonLisboa, Portugal
| | - José F Cascalheira
- CICS-UBI - Health Sciences Research Center, University of Beira InteriorCovilhã, Portugal; Department of Chemistry, University of Beira InteriorCovilhã, Portugal
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Status Epilepticus Enhances Depotentiation after Fully Established LTP in an NMDAR-Dependent but GluN2B-Independent Manner. Neural Plast 2016; 2016:6592038. [PMID: 26881126 PMCID: PMC4735914 DOI: 10.1155/2016/6592038] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2015] [Revised: 10/26/2015] [Accepted: 11/01/2015] [Indexed: 11/22/2022] Open
Abstract
N-Methyl-D-aspartate (NMDA) receptor-dependent long-term potentiation (LTP) can be reversed by low-frequency stimulation (LFS) referred to as depotentiation (DP). We previously found GluN2B upregulated in CA1 neurons from post-status epilepticus (post-SE) tissue associated with an enhanced LTP. Here, we tested whether LFS-induced DP is also altered in pathological GluN2B upregulation. Although LTP was enhanced in post-SE tissue, LTP was significantly reversed in this tissue, but not in controls. We next tested the effect of the GluN2B subunit-specific blocker Ro 25-6981 (1 μM) on LFS-DP. As expected, LFS had no effect on synaptic strength in the presence of the GluN2B blocker in control tissue. In marked contrast, LFS-DP was also attained in post-SE tissue indicating that GluN2B was obviously not involved in depotentiation. To test for NMDA receptor-dependence, we applied the NMDA receptor antagonist D-AP5 (50 μM) prior to LFS and observed that DP was abolished in both control and post-SE tissue confirming NMDA receptor involvement. These results indicate that control Schaffer collateral-CA1 synapses cannot be depotentiated after fully established LTP, but LFS was able to reverse LTP significantly in post-SE tissue. However, while LFS-DP clearly required NMDA receptor activation, GluN2B-containing NMDA receptors were not involved in this form of depotentiation.
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Adenosine A1 Receptor-Mediated Endocytosis of AMPA Receptors Contributes to Impairments in Long-Term Potentiation (LTP) in the Middle-Aged Rat Hippocampus. Neurochem Res 2015; 41:1085-97. [PMID: 26700433 DOI: 10.1007/s11064-015-1799-3] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2015] [Revised: 12/09/2015] [Accepted: 12/09/2015] [Indexed: 12/20/2022]
Abstract
Aging causes multiple changes in the mammalian brain, including changes in synaptic signaling. Previous reports have shown increased extracellular adenosine in the aging brain, and we recently reported that activation of adenosine A1 receptors (A1Rs) induces AMPA receptor (AMPAR) internalization in rat hippocampus. This study investigated whether aging-related changes in the rat hippocampus include altered surface expression of adenosine A1 and A2A receptors, and whether these changes correspond to changes in AMPAR surface expression and altered synaptic plasticity. We found reduced A1R surface expression in middle-aged rat hippocampus, and also reduced GluA1 and GluA2 AMPAR subunit surface expression. Using a chemically-induced LTP (cLTP) experimental protocol, we recorded fEPSPs in young (1 month old) and middle-aged (7-12 month old) rat hippocampal slices. There were significant impairments in cLTP in middle-aged slices, suggesting impaired synaptic plasticity. Since we previously showed that the A1R agonist N(6)-cyclopentyladenosine (CPA) reduced both A1Rs and GluA2/GluA1 AMPARs, we hypothesized that the observed impaired synaptic plasticity in middle-aged brains is regulated by A1R-mediated AMPAR internalization by clathrin-mediated endocytosis. Following cLTP, we found a significant increase in GluA1 and GluA2 surface expression in young rats, which was blunted in middle-aged brains or in young brains pretreated with CPA. Blocking A1Rs with 8-cyclopentyl-1,3-dipropylxanthine or AMPAR endocytosis with either Tat-GluA2-3Y peptide or dynasore (dynamin inhibitor) similarly enhanced AMPAR surface expression following cLTP. These data suggest that age-dependent alteration in adenosine receptor expression contributes to increased AMPAR endocytosis and impaired synaptic plasticity in aged brains.
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Stockwell J, Chen Z, Niazi M, Nosib S, Cayabyab FS. Protein phosphatase role in adenosine A1 receptor-induced AMPA receptor trafficking and rat hippocampal neuronal damage in hypoxia/reperfusion injury. Neuropharmacology 2015; 102:254-65. [PMID: 26626486 DOI: 10.1016/j.neuropharm.2015.11.018] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2015] [Revised: 11/19/2015] [Accepted: 11/21/2015] [Indexed: 12/19/2022]
Abstract
Adenosine signaling via A1 receptor (A1R) and A2A receptor (A2AR) has shown promise in revealing potential targets for neuroprotection in cerebral ischemia. We recently showed a novel mechanism by which A1R activation with N(6)-cyclopentyl adenosine (CPA) induced GluA1 and GluA2 AMPA receptor (AMPAR) endocytosis and adenosine-induced persistent synaptic depression (APSD) in rat hippocampus. This study further investigates the mechanism of A1R-mediated AMPAR internalization and hippocampal slice neuronal damage through activation of protein phosphatase 1 (PP1), 2A (PP2A), and 2B (PP2B) using electrophysiological, biochemical and imaging techniques. Following prolonged A1R activation, GluA2 internalization was selectively blocked by PP2A inhibitors (okadaic acid and fostriecin), whereas inhibitors of PP2A, PP1 (tautomycetin), and PP2B (FK506) all prevented GluA1 internalization. Additionally, GluA1 phosphorylation at Ser831 and Ser845 was reduced after prolonged A1R activation in hippocampal slices. PP2A inhibitors nullified A1R-mediated downregulation of pSer845-GluA1, while PP1 and PP2B inhibitors prevented pSer831-GluA1 downregulation. Each protein phosphatase inhibitor also blunted CPA-induced synaptic depression and APSD. We then tested whether A1R-mediated changes in AMPAR trafficking and APSD contribute to hypoxia-induced neuronal injury. Hypoxia (20 min) induced A1R-mediated internalization of both AMPAR subunits, and subsequent normoxic reperfusion (45 min) increased GluA1 but persistently reduced GluA2 surface expression. Neuronal damage after hypoxia-reperfusion injury was significantly blunted by pre-incubation with the above protein phosphatase inhibitors. Together, these data suggest that A1R-mediated protein phosphatase activation causes persistent synaptic depression by downregulating GluA2-containing AMPARs; this previously undefined role of A1R stimulation in hippocampal neuronal damage represents a novel therapeutic target in cerebral ischemic damage.
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Affiliation(s)
- Jocelyn Stockwell
- Department of Surgery, Neuroscience Research Group, University of Saskatchewan, Saskatoon, Saskatchewan, Canada.
| | - Zhicheng Chen
- Department of Surgery, Neuroscience Research Group, University of Saskatchewan, Saskatoon, Saskatchewan, Canada.
| | - Mina Niazi
- Department of Surgery, Neuroscience Research Group, University of Saskatchewan, Saskatoon, Saskatchewan, Canada.
| | - Siddarth Nosib
- Department of Surgery, Neuroscience Research Group, University of Saskatchewan, Saskatoon, Saskatchewan, Canada.
| | - Francisco S Cayabyab
- Department of Surgery, Neuroscience Research Group, University of Saskatchewan, Saskatoon, Saskatchewan, Canada.
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Prolonged adenosine A1 receptor activation in hypoxia and pial vessel disruption focal cortical ischemia facilitates clathrin-mediated AMPA receptor endocytosis and long-lasting synaptic inhibition in rat hippocampal CA3-CA1 synapses: differential regulation of GluA2 and GluA1 subunits by p38 MAPK and JNK. J Neurosci 2014; 34:9621-43. [PMID: 25031403 DOI: 10.1523/jneurosci.3991-13.2014] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Activation of presynaptic adenosine A1 receptors (A1Rs) causes substantial synaptic depression during hypoxia/cerebral ischemia, but postsynaptic actions of A1Rs are less clear. We found that A1Rs and GluA2-containing AMPA receptors (AMPARs) form stable protein complexes from hippocampal brain homogenates and cultured hippocampal neurons from Sprague Dawley rats. In contrast, adenosine A2A receptors (A2ARs) did not coprecipitate or colocalize with GluA2-containing AMPARs. Prolonged stimulation of A1Rs with the agonist N(6)-cyclopentyladenosine (CPA) caused adenosine-induced persistent synaptic depression (APSD) in hippocampal brain slices, and APSD levels were blunted by inhibiting clathrin-mediated endocytosis of GluA2 subunits with the Tat-GluA2-3Y peptide. Using biotinylation and membrane fractionation assays, prolonged CPA incubation showed significant depletion of GluA2/GluA1 surface expression from hippocampal brain slices and cultured neurons. Tat-GluA2-3Y peptide or dynamin inhibitor Dynasore prevented CPA-induced GluA2/GluA1 internalization. Confocal imaging analysis confirmed that functional A1Rs, but not A2ARs, are required for clathrin-mediated AMPAR endocytosis in hippocampal neurons. Pharmacological inhibitors or shRNA knockdown of p38 MAPK and JNK prevented A1R-mediated internalization of GluA2 but not GluA1 subunits. Tat-GluA2-3Y peptide or A1R antagonist 8-cyclopentyl-1,3-dipropylxanthine also prevented hypoxia-mediated GluA2/GluA1 internalization. Finally, in a pial vessel disruption cortical stroke model, a unilateral cortical lesion compared with sham surgery reduced hippocampal GluA2, GluA1, and A1R surface expression and also caused synaptic depression in hippocampal slices that was consistent with AMPAR downregulation and decreased probability of transmitter release. Together, these results indicate a previously unknown mechanism for A1R-induced persistent synaptic depression involving clathrin-mediated GluA2 and GluA1 internalization that leads to hippocampal neurodegeneration after hypoxia/cerebral ischemia.
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Ferrante A, Martire A, Pepponi R, Varani K, Vincenzi F, Ferraro L, Beggiato S, Tebano MT, Popoli P. Expression, pharmacology and functional activity of adenosine A1 receptors in genetic models of Huntington's disease. Neurobiol Dis 2014; 71:193-204. [PMID: 25132555 DOI: 10.1016/j.nbd.2014.08.013] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2014] [Revised: 07/15/2014] [Accepted: 08/06/2014] [Indexed: 12/20/2022] Open
Abstract
Adenosine A1 receptor (A1R) stimulation exerts beneficial effects in response to various insults to the brain and, although it was found neuroprotective in a lesional model of Huntington's disease (HD), the features of this receptor in genetic models of HD have never been explored. In the present study we characterized the expression, affinity and functional effects of A1Rs in R6/2 mice (the most widely used transgenic model of HD) and in a cellular model of HD. Binding studies revealed that the density of A1Rs was significantly reduced in the cortex and the striatum of R6/2 mice compared to age-matched wild-type (WT), while receptor affinity was unchanged. The selective A1R agonist cyclopentyladenosine (CPA, 300nM) was significantly more effective in reducing synaptic transmission in corticostriatal slices from symptomatic R6/2 than in age-matched WT mice. Such an effect was due to a stronger inhibition of glutamate release from the pre-synaptic terminal. The different functional activities of A1Rs in HD mice were associated also to a different intracellular signaling pathway involved in the synaptic effect of CPA. In fact, while the PKA pathway was involved in both genotypes, p38 MAPK inhibitor SB203580 partially prevented synaptic effects of CPA in R6/2, but not in WT, mice; moreover, CPA differently modulated the phosphorylation status of p38 in the two genotypes. In vitro studies confirmed a different behavior of A1Rs in HD: CPA (100 nM for 5h) modulated cell viability in STHdh(Q111/Q111) (mhttHD cells), without affecting the viability of STHdh(Q7/Q7) (wthtt cells). This effect was prevented by the application of SB203580. Our results demonstrate that in the presence of the HD mutation A1Rs undergo profound changes in terms of expression, pharmacology and functional activity. These changes have to be taken in due account when considering A1Rs as a potential therapeutic target for this disease.
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Affiliation(s)
- Antonella Ferrante
- Istituto Superiore di Sanità, Department of Therapeutic Research and Medicines Evaluation, Viale Regina Elena 299, 00161 Rome, Italy.
| | - Alberto Martire
- Istituto Superiore di Sanità, Department of Therapeutic Research and Medicines Evaluation, Viale Regina Elena 299, 00161 Rome, Italy
| | - Rita Pepponi
- Istituto Superiore di Sanità, Department of Therapeutic Research and Medicines Evaluation, Viale Regina Elena 299, 00161 Rome, Italy
| | - Katia Varani
- Department of Medical Sciences, Pharmacology Section, University of Ferrara, via Fossato di Mortara 17/19, 44121 Ferrara, Italy
| | - Fabrizio Vincenzi
- Department of Medical Sciences, Pharmacology Section, University of Ferrara, via Fossato di Mortara 17/19, 44121 Ferrara, Italy
| | - Luca Ferraro
- Department of Life Sciences and Biotechnology, University of Ferrara, Via Fossato di Mortara 17, 44121 Ferrara, Italy
| | - Sarah Beggiato
- Department of Medical Sciences, Pharmacology Section, University of Ferrara, via Fossato di Mortara 17/19, 44121 Ferrara, Italy
| | - Maria Teresa Tebano
- Istituto Superiore di Sanità, Department of Therapeutic Research and Medicines Evaluation, Viale Regina Elena 299, 00161 Rome, Italy
| | - Patrizia Popoli
- Istituto Superiore di Sanità, Department of Therapeutic Research and Medicines Evaluation, Viale Regina Elena 299, 00161 Rome, Italy
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Yang YC, Hu CC, Huang CS, Chou PY. Thalamic synaptic transmission of sensory information modulated by synergistic interaction of adenosine and serotonin. J Neurochem 2013; 128:852-63. [DOI: 10.1111/jnc.12499] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2013] [Revised: 10/10/2013] [Accepted: 10/14/2013] [Indexed: 01/01/2023]
Affiliation(s)
- Ya-Chin Yang
- Department of Biomedical Sciences; College of Medicine, Chang Gung University; Tao-Yuan Taiwan
- Graduate Institute of Biomedical Sciences, College of Medicine; Chang Gung University; Tao-Yuan Taiwan
| | - Chun-Chang Hu
- Graduate Institute of Biomedical Sciences, College of Medicine; Chang Gung University; Tao-Yuan Taiwan
| | - Chen-Syuan Huang
- Department of Biomedical Sciences; College of Medicine, Chang Gung University; Tao-Yuan Taiwan
- Graduate Institute of Biomedical Sciences, College of Medicine; Chang Gung University; Tao-Yuan Taiwan
| | - Pei-Yu Chou
- Graduate Institute of Biomedical Sciences, College of Medicine; Chang Gung University; Tao-Yuan Taiwan
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Cayabyab FS, Gowribai K, Walz W. Involvement of matrix metalloproteinases-2 and -9 in the formation of a lacuna-like cerebral cavity. J Neurosci Res 2013; 91:920-33. [PMID: 23606560 DOI: 10.1002/jnr.23223] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2012] [Revised: 02/22/2013] [Accepted: 03/01/2013] [Indexed: 12/20/2022]
Abstract
We used a modified pial vessel disruption (PVD) protocol with adult male Wistar rats to mimic small-vessel stroke in the cerebral cortex. Within 3 weeks, this lesion develops into a single lacuna-like cavity, which is fluid-filled and encapsulated by reactive astrocytes. Minocycline treatment that commences 1 hr after lesion and continues for 6 days prevents the cavitation and causes a filling of the lesion with reactive astrocytes and no barrier. Here, we determined whether inhibition of matrix metalloproteinases-2 and -9 (MMPs) mediates this minocycline action. Confocal microscopy revealed increased punctate staining of MMPs inside the lesion sites after 2 days of PVD. Astrocytes lined the lesion border but showed sparse localization inside the lesion. In contrast, increased MMP levels inside the lesion coincided with increased ED1 or OX-42 immunostaining, suggesting that MMP elevation reflected increased secretions from microglia/macrophages. Imaging analyses also revealed that minocycline administered for 2 days before animal euthanasia, significantly decreased MMP levels within the lesion. Moreover, Western blot analysis of cortical tissue extracts showed a significant 30-40% upregulation of MMPs 2 days after lesion. Minocycline administered 2 hr before the lesion significantly inhibited both MMP-9 and MMP-2 levels by ∼40%. In contrast, minocycline administered 1 hr after the lesion only decreased MMP-9 levels by ∼30%. Because MMP inhibition with batimastat injection also prevented cavity formation at 21 days, we conclude that minocycline prevented the creation of a lacuna-like cyst in the cerebral cortex by inhibiting the MMP secretion from microglia in the affected tissue.
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Affiliation(s)
- Francisco S Cayabyab
- Department of Physiology, University of Saskatchewan, Saskatoon, Saskatchewan, Canada.
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Zhang D, Xiong W, Chu S, Sun C, Albensi BC, Parkinson FE. Inhibition of hippocampal synaptic activity by ATP, hypoxia or oxygen-glucose deprivation does not require CD73. PLoS One 2012; 7:e39772. [PMID: 22761898 PMCID: PMC3382561 DOI: 10.1371/journal.pone.0039772] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2012] [Accepted: 05/30/2012] [Indexed: 11/24/2022] Open
Abstract
Adenosine, through activation of its A1 receptors, has neuroprotective effects during hypoxia and ischemia. Recently, using transgenic mice with neuronal expression of human equilibrative nucleoside transporter 1 (hENT1), we reported that nucleoside transporter-mediated release of adenosine from neurons was not a key mechanism facilitating the actions of adenosine at A1 receptors during hypoxia/ischemia. The present study was performed to test the importance of CD73 (ecto-5′-nucleotidase) for basal and hypoxic/ischemic adenosine production. Hippocampal slice electrophysiology was performed with CD73+/+ and CD73−/− mice. Adenosine and ATP had similar inhibitory effects in both genotypes, with IC50 values of approximately 25 µM. In contrast, ATP was a less potent inhibitor (IC50 = 100 µM) in slices from mice expressing hENT1 in neurons. The inhibitory effects of ATP in CD73+/+ and CD73−/− slices were blocked by the adenosine A1 receptor antagonist 8-cyclopentyl-1,3-dipropylxanthine (DPCPX) and were enhanced by the nucleoside transport inhibitor S-(4-nitrobenzyl)-6-thioinosine (NBTI), consistent with effects that are mediated by adenosine after metabolism of ATP. AMP showed a similar inhibitory effect to ATP and adenosine, indicating that the response to ATP was not mediated by P2 receptors. In comparing CD73−/− and CD73+/+ slices, hypoxia and oxygen-glucose deprivation produced similar depression of synaptic transmission in both genotypes. An inhibitor of tissue non-specific alkaline phosphatase (TNAP) was found to attenuate the inhibitory effects of AMP and ATP, increase basal synaptic activity and reduce responses to oxygen-glucose deprivation selectively in slices from CD73−/− mice. These results do not support an important role for CD73 in the formation of adenosine in the CA1 area of the hippocampus during basal, hypoxic or ischemic conditions, but instead point to TNAP as a potential source of extracellular adenosine when CD73 is absent.
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Affiliation(s)
- Dali Zhang
- Department of Pharmacology and Therapeutics, University of Manitoba, Winnipeg, Manitoba, Canada
- Division of Neurodegenerative Disorders, St Boniface Hospital Research Centre, Winnipeg, Manitoba, Canada
| | - Wei Xiong
- Department of Pharmacology and Therapeutics, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Stephanie Chu
- Department of Pharmacology and Therapeutics, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Chao Sun
- Department of Pharmacology and Therapeutics, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Benedict C. Albensi
- Department of Pharmacology and Therapeutics, University of Manitoba, Winnipeg, Manitoba, Canada
- Division of Neurodegenerative Disorders, St Boniface Hospital Research Centre, Winnipeg, Manitoba, Canada
| | - Fiona E. Parkinson
- Department of Pharmacology and Therapeutics, University of Manitoba, Winnipeg, Manitoba, Canada
- * E-mail:
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Sanderson TM. Molecular mechanisms involved in depotentiation and their relevance to schizophrenia. Chonnam Med J 2012; 48:1-6. [PMID: 22570808 PMCID: PMC3341431 DOI: 10.4068/cmj.2012.48.1.1] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2012] [Accepted: 04/10/2012] [Indexed: 12/27/2022] Open
Abstract
Long-term potentiation (LTP) and long-term depression (LTD) of synaptic transmission are forms of synaptic plasticity that have been studied extensively and are thought to contribute to learning and memory. The reversal of LTP, known as depotentiation (DP) has received far less attention however, and its role in behavior is also far from clear. Recently, deficits in depotentiation have been observed in models of schizophrenia, suggesting that a greater understanding of this form of synaptic plasticity may help reveal the physiological alterations that underlie symptoms experienced by patients. This review therefore seeks to summarize the current state of knowledge on DP, and then put the deficits in DP in models of disease into this context.
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Affiliation(s)
- Thomas M Sanderson
- Department of Brain & Cognitive Sciences, College of Natural Sciences, Seoul National University, Seoul, Korea
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Intracellular Signaling MAPK Pathway After Cerebral Ischemia–Reperfusion Injury. Neurochem Res 2012; 37:1568-77. [DOI: 10.1007/s11064-012-0752-y] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2012] [Revised: 02/29/2012] [Accepted: 03/07/2012] [Indexed: 12/22/2022]
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Nayak GH, Prentice HM, Milton SL. Neuroprotective signaling pathways are modulated by adenosine in the anoxia tolerant turtle. J Cereb Blood Flow Metab 2011; 31:467-75. [PMID: 20648037 PMCID: PMC3049502 DOI: 10.1038/jcbfm.2010.109] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Cumulative evidence shows a protective role for adenosine A1 receptors (A1R) in hypoxia/ischemia; A1R stimulation reduces neuronal damage, whereas blockade exacerbates damage. The signal transduction pathways may involve the mitogen-activated protein kinase (MAPK) pathways and serine/threonine kinase (AKT), with cell survival depending on the timing and degree of upregulation of these cascades as well as the balance between pro-survival and pro-death pathways. Here, we show in vitro that extracellular signal-regulated kinase (ERK1/2) and phosphatidylinositol 3-kinase (PI3-K/AKT) activation is dependent on A1R stimulation, with further downstream effects that promote neuronal survival. Phosphorylated ERK1/2 (p-ERK) and AKT (p-AKT) as well as Bcl-2 are upregulated in anoxic neuronally enriched primary cultures from turtle brain. This native upregulation is further increased by the selective A1R agonist 2-chloro-N-cyclopentyladenosine (CCPA), whereas the selective antagonist 8-cyclopentyl-1,3-dihydropylxanthine (DPCPX) decreases p-ERK and p-AKT expression. Conversely, A1R antagonism resulted in increases in phosphorylated JNK (p-JNK), p38 (p-p38), and Bax. As pathological and adaptive changes occur simultaneously during anoxia/ischemia in mammalian neurons, the turtle provides an alternative model to analyze protective mechanisms in the absence of evident pathologies.
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Affiliation(s)
- Gauri H Nayak
- Department of Biology, Boston University, Boston, Massachusetts 02215, USA.
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29
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Behavioral and cerebellar transmission deficits in mice lacking the autism-linked gene islet brain-2. J Neurosci 2010; 30:14805-16. [PMID: 21048139 DOI: 10.1523/jneurosci.1161-10.2010] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Deletion of the human SHANK3 gene near the terminus of chromosome 22q is associated with Phelan-McDermid syndrome and autism spectrum disorders. Nearly all such deletions also span the tightly linked IB2 gene. We show here that IB2 protein is broadly expressed in the brain and is highly enriched within postsynaptic densities. Experimental disruption of the IB2 gene in mice reduces AMPA and enhances NMDA receptor-mediated glutamatergic transmission in cerebellum, changes the morphology of Purkinje cell dendritic arbors, and induces motor and cognitive deficits suggesting an autism phenotype. These findings support a role for human IB2 mutation as a contributing genetic factor in Chr22qter-associated cognitive disorders.
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Dale N, Frenguelli BG. Release of adenosine and ATP during ischemia and epilepsy. Curr Neuropharmacol 2010; 7:160-79. [PMID: 20190959 PMCID: PMC2769001 DOI: 10.2174/157015909789152146] [Citation(s) in RCA: 173] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2009] [Revised: 04/15/2009] [Accepted: 05/01/2009] [Indexed: 12/17/2022] Open
Abstract
Eighty years ago Drury & Szent-Györgyi described the actions of adenosine, AMP (adenylic acid) and ATP (pyrophosphoric or diphosphoric ester of adenylic acid) on the mammalian cardiovascular system, skeletal muscle, intestinal and urinary systems. Since then considerable insight has been gleaned on the means by which these compounds act, not least of which in the distinction between the two broad classes of their respective receptors, with their many subtypes, and the ensuing diversity in cellular consequences their activation invokes. These myriad actions are of course predicated on the release of the purines into the extracellular milieu, but, surprisingly, there is still considerable ambiguity as to how this occurs in various physiological and pathophysiological conditions. In this review we summarise the release of ATP and adenosine during seizures and cerebral ischemia and discuss mechanisms by which the purines adenosine and ATP may be released from cells in the CNS under these conditions.
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Affiliation(s)
- Nicholas Dale
- Department of Biological Sciences, University of Warwick, Coventry, CV4 7AL, UK
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Tumor necrosis factor-alpha impairs the recovery of synaptic transmission from hypoxia in rat hippocampal slices. J Neuroimmunol 2009; 218:21-7. [PMID: 19942300 DOI: 10.1016/j.jneuroim.2009.11.002] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2009] [Revised: 10/15/2009] [Accepted: 11/05/2009] [Indexed: 01/20/2023]
Abstract
Cerebral ischaemia is a common occurrence in a range of pathological conditions, including stroke and traumatic brain injury. Two of the components in ischaemia are tissue hypoxia and the release of pro-inflammatory agents such as TNF-alpha. The role of TNF-alpha in an ischaemic/hypoxic episode is still controversial, although deleterious effects of pro-inflammatory cytokines in the area of injury are well documented. One of the prime adaptive mechanisms in response to hypoxia is the cellular activation of adenosine 1 receptors (A1Rs), which inhibits excitatory synaptic transmission. In the present study we have examined the effect of TNF-alpha application on synaptic transmission during hypoxic exposure and re-oxygenation using extracellular recordings in the CA1 region of the rat hippocampal slice. Hypoxia caused a reversible depression of the field EPSP (29.6+/-9.7% of control, n=5), which was adenosine A(1) receptor-dependent (85.7+/-4.3%, in the presence of DPCPX (200 nM), the adenosine A(1) receptor antagonist). DPCPX inhibited the maintenance of long-term potentiation obtained 30 min post hypoxia (143.8+/-8.2% versus 96.4+/-10.6% respectively, 1h post tetanus; n=5; p<0.005). In TNF-alpha (150 pM) treated slices hypoxic depression was similar to controls but a reduction in fEPSP slope was observed during re-oxygenation (66.8+/-1.4%, n=5). This effect was reversed by pre-treatment with SB 203580 (1 microM), a p38 MAP kinase inhibitor (91.8+/-6.9%, n=5). These results demonstrate a novel p38 MAPK dependent role for TNF-alpha in attenuating synaptic transmission after a hypoxic episode.
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Katoh-Semba R, Kaneko R, Kitajima S, Tsuzuki M, Ichisaka S, Hata Y, Yamada H, Miyazaki N, Takahashi Y, Kato K. Activation of p38 mitogen-activated protein kinase is required for in vivo brain-derived neurotrophic factor production in the rat hippocampus. Neuroscience 2009; 163:352-61. [PMID: 19524026 DOI: 10.1016/j.neuroscience.2009.06.011] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2009] [Revised: 04/26/2009] [Accepted: 06/04/2009] [Indexed: 10/20/2022]
Abstract
Several lines of evidence strongly suggest that brain-derived neurotrophic factor (BDNF) is associated with the formation, storage and recall of memory in the hippocampus and that it is important to maintain a considerable level of hippocampal BDNF in order to keep normal functions. BDNF can be synthesized in an activity-dependent manner. In fact, kainic acid or AMPA enhances BDNF levels in hippocampal granule neurons. However, the mechanisms of BDNF production are largely unclear. Recently, we have found that riluzole, which blocks voltage-gated sodium channels and thereby reduces glutamate release, actually strengthens immunoreactivity of BDNF in hippocampal granule neurons of rats. Therefore, we examined the riluzole-activated signaling pathways for BDNF production. Riluzole increased levels of phospho-p38 mitogen-activated protein kinase (p38 MAPK), as well as BDNF levels. Inhibition of p38 MAPK by SB203580 reduced riluzole effects, while activation of p38 MAPK by anisomycin increased levels of BDNF, suggesting that p38 MAPK can mediate BDNF production. Riluzole-induced elevation of phospho-activating transcription factor-2, a transcription factor downstream of p38 MAPK, was also observed. A blocker of N-type voltage-gated calcium channels reduced the effects of riluzole on BDNF production and p38 MAPK activation. We also examined a possible involvement of the adenosine A1 receptor in BDNF production because riluzole can influence ecto-nucleotide levels. An A1 receptor agonist inhibited riluzole-induced elevation of BDNF levels, whereas an antagonist not only increased levels of BDNF and active p38 MAPK but also augmented riluzole effects. These results indicate that, in the rat hippocampus, there is an in vivo signaling pathway for BDNF synthesis mediated by p38 MAPK, and that N-type voltage-gated calcium channels and/or adenosine A1 receptors contribute to p38 MAPK activation.
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Affiliation(s)
- R Katoh-Semba
- Institute for Developmental Research, Aichi Human Service Center, Kasugai, Aichi, 480-0392, Japan.
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Marshall M, Anilkumar N, Layland J, Walker SJ, Kentish JC, Shah AM, Cave AC. Protein phosphatase 2A contributes to the cardiac dysfunction induced by endotoxemia. Cardiovasc Res 2009; 82:67-76. [PMID: 19201758 PMCID: PMC2652740 DOI: 10.1093/cvr/cvp037] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Aims Sepsis-associated cardiac dysfunction represents an intrinsic impairment of cardiomyocyte function due in part to a decrease in myofilament Ca2+ sensitivity associated with a sustained increase in cardiac troponin I (cTnI) phosphorylation at Ser23/24. Dephosphorylation of cTnI is under regulatory control. Thus, muscarinic and adenosine A1-receptor agonists antagonize β-adrenergic stimulation via activation of protein phosphatase 2A (PP2A). The aim of this study was to determine whether modulation of PP2A and thus cTnI phosphorylation could improve sepsis-induced contractile dysfunction. Methods and results Cardiomyocytes were isolated from control or septic mice 16–18 h after an injection of vehicle or lipopolysaccharide (LPS; 9 mg/kg ip) respectively. Protein expression and phosphatase activity were determined in homogenates of control and septic hearts. Our data showed that LPS significantly increased cTnI phosphorylation at Ser23/24 in cardiomyocytes and reduced contraction amplitude without affecting Ca2+-transients. Treatment of cardiomyocytes with the A1 agonist cyclopentyladenosine (CPA) or the protein kinase A inhibitor H89 significantly attenuated the LPS-induced contractile dysfunction without effect on Ca2+-transients. Co-treatment with CPA and H89 completely reversed the contractile dysfunction. Increased cTnI phosphorylation in septic hearts was associated with a significant reduction in the protein expression of both the catalytic and regulatory subunits (B56α) of PP2A and a decrease in PP2A activity. CPA treatment of septic hearts increased PP2A activity. An increase in the protein expression of demethylated PP2A and a decrease in the PP2A-methyltransferase (PPMT; the methyltransferase that catalyses this reaction) were also observed. Conclusion These data support the hypothesis that sustained cTnI phosphorylation underlies the contractile dysfunction seen in sepsis.
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Affiliation(s)
- Melanie Marshall
- Cardiovascular Division, Department of Cardiology, King's College London, James Black Centre, London SE5 9NU, UK.
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Brain metabolism dictates the polarity of astrocyte control over arterioles. Nature 2008; 456:745-9. [PMID: 18971930 DOI: 10.1038/nature07525] [Citation(s) in RCA: 541] [Impact Index Per Article: 33.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2008] [Accepted: 10/10/2008] [Indexed: 12/12/2022]
Abstract
Calcium signalling in astrocytes couples changes in neural activity to alterations in cerebral blood flow by eliciting vasoconstriction or vasodilation of arterioles. However, the mechanism for how these opposite astrocyte influences provide appropriate changes in vessel tone within an environment that has dynamic metabolic requirements remains unclear. Here we show that the ability of astrocytes to induce vasodilations over vasoconstrictions relies on the metabolic state of the rat brain tissue. When oxygen availability is lowered and astrocyte calcium concentration is elevated, astrocyte glycolysis and lactate release are maximized. External lactate attenuates transporter-mediated uptake from the extracellular space of prostaglandin E(2), leading to accumulation and subsequent vasodilation. In conditions of low oxygen concentration extracellular adenosine also increases, which blocks astrocyte-mediated constriction, facilitating dilation. These data reveal the role of metabolic substrates in regulating brain blood flow and provide a mechanism for differential astrocyte control over cerebrovascular diameter during different states of brain activation.
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Liang YC, Huang CC, Hsu KS. A role of p38 mitogen-activated protein kinase in adenosine A₁ receptor-mediated synaptic depotentiation in area CA1 of the rat hippocampus. Mol Brain 2008; 1:13. [PMID: 18947392 PMCID: PMC2579284 DOI: 10.1186/1756-6606-1-13] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2008] [Accepted: 10/23/2008] [Indexed: 12/01/2022] Open
Abstract
Background Although long-term potentiation (LTP) of synaptic strength is very persistent, current studies have provided evidence that various manipulations or pharmacological treatment when applied shortly after LTP induction can reverse it. This kind of reversal of synaptic strength is termed as depotentiation and may have a function to increase the flexibility and storage capacity of neuronal networks. Our previous studies have demonstrated that an increase in extracellular levels of adenosine and subsequent activation of adenosine A1 receptors are important for the induction of depotentiation; however, the signaling downstream of adenosine A1 receptors to mediate depotentiation induction remains elusive. Results We confirm that depotentiation induced by low-frequency stimulation (LFS) (2 Hz, 10 min, 1200 pulses) was dependent on adenosine A1 receptor activation, because it was mimicked by bath-applied adenosine A1 receptor agonist N6-cyclopentyladenosine (CPA) and was inhibited by the selective adenosine A1 receptor antagonist 8-cyclopentyl-1,3-dipropylxanthine (DPCPX). Pretreatment of the hippocampal slices with the selective p38 mitogen-activated protein kinase (MAPK) inhibitors, 4-(4-fluorophenyl)-2-(4-methylsulfinylphenyl]-5-(4-pyrudyl)-1H-imidazole (SB203580) or trans-1-(4-hydroxycyclohexyl)-4-(fluorophenyl)-5-(2-methoxypyrimidin-4-yl)imidazole (SB239063), prevented the induction of depotentiation by LFS and CPA. In agreement with electrophysiological observation, both LFS- and CPA-induced depotentiation are associated with an increase in p38 MAPK activation, which are blocked by DPCPX or SB203580 application. Conclusion These results suggest that activation of adenosine A1 receptor and in turn triggering p38 MAPK signaling may contribute to the LFS-induced depotentiation at hippocampal CA1 synapses.
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Affiliation(s)
- Ying-Ching Liang
- Department of Pharmacology, National Cheng Kung University, Tainan City, Taiwan.
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Abstract
Long-term potentiation (LTP), a synaptic mechanism thought to underlie memory formation, has been studied extensively at hippocampal Schaffer collateral (SC) synapses. The SC pathway transmits information to area CA1 that originates in entorhinal cortex and is processed by the dentate gyrus and area CA3. CA1 also receives direct excitatory input from entorhinal cortex via the perforant path (PP), but the role of this cortical input is less certain. Here, we report that low-frequency stimulation of PP inputs to CA1 has no lasting effect on basal SC transmission, but effectively depotentiates SC synapses that have undergone LTP in a manner that can be reversed by subsequent high-frequency stimulation of SC inputs. This depotentiation does not require NMDA receptors, group I metabotropic glutamate receptors, or L-type calcium channels, but involves adenosine acting at A(1) receptors. Given the limited storage capacity of the hippocampus, these observations provide a mechanism by which input from cortex can help to reset synaptic transmission in the hippocampus and facilitate additional information processing.
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Cho J, Gruol DL. The chemokine CCL2 activates p38 mitogen-activated protein kinase pathway in cultured rat hippocampal cells. J Neuroimmunol 2008; 199:94-103. [PMID: 18584881 DOI: 10.1016/j.jneuroim.2008.05.011] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2007] [Revised: 04/25/2008] [Accepted: 05/19/2008] [Indexed: 11/24/2022]
Abstract
Emerging evidence indicates that chemokines can regulate both the physiology and biochemistry of CNS neurons and glia. In the current study, Western blot analysis showed that in rat hippocampal neuronal/glial cultures the signal transduction pathway activated by CCL2, a chemokine expressed in the normal brain and at elevated levels during neuroinflammation, involves a G-protein coupled receptor, p38 MAPK as well as its immediate upstream kinase MKK3/6, and the downstream transcription factor CREB. ERK 1/2 and the transcription factors STAT1 and STAT3 do not play a prominent role. CCL2 also altered Ca(2+) influx and synaptic network activity in the hippocampal neurons. These results suggest an important role for p38 MAPK and CREB in hippocampal actions of CCL2.
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Affiliation(s)
- Jungsook Cho
- Molecular and Integrative Neuroscience Department, The Scripps Research Institute, 10550 N. Torrey Pines Road, La Jolla, CA 92037, United States.
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Fragoso G, Haines JD, Roberston J, Pedraza L, Mushynski WE, Almazan G. p38 mitogen-activated protein kinase is required for central nervous system myelination. Glia 2007; 55:1531-41. [PMID: 17729284 DOI: 10.1002/glia.20567] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The p38 MAPKs are a family of kinases that regulate a number of cellular functions including cell migration, proliferation, and differentiation. Here, we report that p38 regulates oligodendrocyte differentiation. Inhibition of p38 with PD169316 and SB203580 prevented accumulation of protein and mRNA of cell-stage specific markers characteristic of differentiated oligodendrocytes, including myelin basic protein, myelin-associated glycoprotein, and the glycosphingolipids, galactosylceramide and sulfatide. In addition, the cell cycle regulator p27(kip1) and the transcription factor Sox10 were also significantly reduced. Most significantly, p38 inhibitors completely and irreversibly blocked myelination of dorsal root ganglion neurons by oligodendrocytes and prevented the axolemmal organization of the axo-glial adhesion molecule Caspr. Our results suggest a role(s) for this kinase in key regulatory steps in the maturation of OLGs and initiation of myelination.
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Affiliation(s)
- Gabriela Fragoso
- Department of Pharmacology and Therapeutics, McGill University, Montreal, Quebec, Canada
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p38 Mitogen-activated protein kinase regulates myelination. J Mol Neurosci 2007; 35:23-33. [PMID: 17994198 DOI: 10.1007/s12031-007-9011-0] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2007] [Accepted: 09/15/2007] [Indexed: 12/16/2022]
Abstract
The p38 mitogen-activated protein kinase family is emerging as a crucial signaling molecule for a vast number of cellular functions including cell migration, proliferation, and differentiation. The function of p38 in myelination has only been recently addressed. Using pyridinyl imidazole-based p38 alpha/beta selective inhibitors, we have reported a critical role for this kinase in the regulation of myelination, specifically, in controlling the differentiation of Schwann cells, and oligodendrocytes, the myelinating glia of the peripheral and central nervous systems, respectively. These compounds inhibited the accumulation of myelin-cell-specific markers, including myelin-specific glycosphingolipids, myelin-associated glycoprotein, and myelin basic protein. More significantly, myelination of dorsal root ganglia neurons by oligodendrocytes was irreversibly blocked by p38 inhibitors. Our current studies are focusing on the molecular mechanisms by which p38 regulates oligodendrocyte and Schwann cell differentiation and its role in models of myelination and remyelination.
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C-Jun N-terminal kinase regulates adenosine A1 receptor-mediated synaptic depression in the rat hippocampus. Neuropharmacology 2007; 53:906-17. [PMID: 17967469 DOI: 10.1016/j.neuropharm.2007.09.001] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2006] [Revised: 08/31/2007] [Accepted: 09/03/2007] [Indexed: 12/19/2022]
Abstract
Adenosine A1 receptors are ubiquitous mediators of presynaptic inhibition of neurotransmission in the central nervous system, yet the signalling pathway linking A1 receptor activation and decreased neurotransmitter release remains poorly resolved. We tested the contribution of c-Jun N-terminal kinase (JNK) to adenosine A1 receptor-mediated depression of field excitatory postsynaptic potentials (fEPSPs) in area CA1 of the rat hippocampus. We found that inhibition of JNK with SP600125 or JNK inhibitor V, but not an inactive analogue, attenuated the depression of fEPSPs induced by adenosine, hypoxia, and the A1 receptor agonist N(6)-cyclopentyladenosine (CPA). In contrast, the JNK inhibitor SP600125 did not inhibit GABA(B)-mediated synaptic depression. In support of our electrophysiological findings, Western blot analysis showed that A1 receptor stimulation resulted in a transient increase in JNK phosphorylation in the membrane fraction of hippocampal lysates. The total amount of JNK in the membrane fraction was unchanged by CPA treatment. The increase in phosphorylated JNK induced by A1 receptor stimulation was blocked by the A1 receptor antagonist 8-cyclopentyl-1,3-dipropylxanthine (DPCPX), indicating that A1 receptors specifically activate JNK in the hippocampus. Together with functional data indicating that JNK inhibition decreased CPA-induced paired pulse facilitation, these results suggest that JNK activation is necessary for adenosine A1 receptor-mediated synaptic depression occurring at a presynaptic locus The adenosine A1 receptor-JNK signalling pathway may represent a novel mechanism underlying inhibition of neurotransmitter release in the CNS.
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Papp L, Vizi ES, Sperlágh B. P2X7 receptor mediated phosphorylation of p38MAP kinase in the hippocampus. Biochem Biophys Res Commun 2007; 355:568-74. [PMID: 17306762 DOI: 10.1016/j.bbrc.2007.02.014] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2007] [Accepted: 02/02/2007] [Indexed: 10/23/2022]
Abstract
This study was designed to explore the effect of P2X7 receptor (P2X7R) activation on the expression of p38 MAP kinase (p38 MAPK) enzyme in hippocampal slices of wild-type (WT) and P2X7R(-/-) mice using the Western blot technique and to clarify its role in P2X7 receptor mediated [(3)H]glutamate release. ATP (1 mM) and the P2X7R agonist BzATP (100 microM) significantly increased p38 MAPK phosphorylation in WT mice, and these effects were absent in the hippocampal slices of P2X7R(-/-) mice. Both ATP- and BzATP-induced p38 MAPK phosphorylations were sensitive to the p38 MAP kinase inhibitor, SB203580 (1 microM). ATP elicited [(3)H]glutamate release from hippocampal slices, which was significantly attenuated by SB203580 (1 microM) but not by the extracellular signal-regulated kinase (ERK1/2) inhibitor, PD098095 (10 microM). Consequently, we suggest that P2X7Rs and p38 MAPK are involved in the stimulatory effect of ATP on glutamate release in the hippocampal slices of WT mice.
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Affiliation(s)
- Lilla Papp
- Department of Pharmacology, Institute of Experimental Medicine, Hungarian Academy of Sciences, H-1450 Budapest, Hungary.
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