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Shetty MS, Ris L, Schindler RFR, Mizuno K, Fedele L, Giese KP, Brand T, Abel T. Mice Lacking the cAMP Effector Protein POPDC1 Show Enhanced Hippocampal Synaptic Plasticity. Cereb Cortex 2022; 32:3457-3471. [PMID: 34937090 PMCID: PMC9376866 DOI: 10.1093/cercor/bhab426] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2021] [Revised: 10/28/2021] [Accepted: 10/29/2021] [Indexed: 11/13/2022] Open
Abstract
Extensive research has uncovered diverse forms of synaptic plasticity and an array of molecular signaling mechanisms that act as positive or negative regulators. Specifically, cyclic 3',5'-cyclic adenosine monophosphate (cAMP)-dependent signaling pathways are crucially implicated in long-lasting synaptic plasticity. In this study, we examine the role of Popeye domain-containing protein 1 (POPDC1) (or blood vessel epicardial substance (BVES)), a cAMP effector protein, in modulating hippocampal synaptic plasticity. Unlike other cAMP effectors, such as protein kinase A (PKA) and exchange factor directly activated by cAMP, POPDC1 is membrane-bound and the sequence of the cAMP-binding cassette differs from canonical cAMP-binding domains, suggesting that POPDC1 may have an unique role in cAMP-mediated signaling. Our results show that Popdc1 is widely expressed in various brain regions including the hippocampus. Acute hippocampal slices from Popdc1 knockout (KO) mice exhibit PKA-dependent enhancement in CA1 long-term potentiation (LTP) in response to weaker stimulation paradigms, which in slices from wild-type mice induce only transient LTP. Loss of POPDC1, while not affecting basal transmission or input-specificity of LTP, results in altered response during high-frequency stimulation. Popdc1 KO mice also show enhanced forskolin-induced potentiation. Overall, these findings reveal POPDC1 as a novel negative regulator of hippocampal synaptic plasticity and, together with recent evidence for its interaction with phosphodiesterases (PDEs), suggest that POPDC1 is involved in modulating activity-dependent local cAMP-PKA-PDE signaling.
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Affiliation(s)
- Mahesh Shivarama Shetty
- Department of Neuroscience and Pharmacology, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA
- Iowa Neuroscience Institute, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA
| | - Laurence Ris
- Department of Neuroscience, University of Mons, Research Institute for Health Sciences and Technology, 7000 Mons, Belgium
| | | | - Keiko Mizuno
- Department of Neuroscience, King’s College, London SE5 9NU, UK
| | - Laura Fedele
- National Heart and Lung Institute, Imperial College London, London W12 ONN, UK
| | | | - Thomas Brand
- National Heart and Lung Institute, Imperial College London, London W12 ONN, UK
| | - Ted Abel
- Department of Neuroscience and Pharmacology, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA
- Iowa Neuroscience Institute, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA
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Shi H, Tu Y, Li Y, Ma C, Gyabaah AT, Yu C, Li Z, Chen J, Li Z, Huang ZL, Cai X. Caffeine excites medial parabrachial nucleus neurons of mice by blocking adenosine A1 receptor. Brain Res 2022; 1790:147984. [PMID: 35709891 DOI: 10.1016/j.brainres.2022.147984] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2021] [Revised: 06/08/2022] [Accepted: 06/09/2022] [Indexed: 11/26/2022]
Abstract
Caffeine has been used as a first-line drug for treatment of apnea neonatorum for decades due to its high safety and effectiveness. Studies report that caffeine mainly acts as a blocker of Adenosine Receptors (ARs). However, the mechanism of caffeine in reducing apnea neonatorum in the central nervous system has not been fully explored. Medial parabrachial nucleus (MPB) is part of the respiratory center of the pons that may be related to the activity of caffeine. Previous studies have not explored the effect and mechanism of caffeine on MPB neurons. To elucidate this, the current study used antagonists of A1 and A2a receptors to mimic the effect of caffeine in MPB of mice in vitro using the patch-clamp technique. The firing rates and spontaneous post-synaptic currents were recorded. The findings of the study showed that caffeine excited MPB neurons. Notably, the adenosine A1R antagonist 8-cyclopentyl-1,3-dimethyl-xanthine (CPT) but not the adenosine A2aR antagonist Istradefylline (KW6002) mimicked the exciting effect of caffeine, implying that caffeine excited MPB neurons in mice by blocking A1Rs. Further, the results indicated that caffeine could increase efficiency of synaptic transmission to excite MPB neurons. These findings suggest that A1Rs in MPB may be potential targets for caffeine in reducing apnea neonatorum.
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Affiliation(s)
- Hua Shi
- Department of Pediatrics, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, 109 Xueyuan Western Road, Wenzhou, Zhejiang 325027, PR China; The Second School of Medicine, Wenzhou Medical University, Wenzhou, Zhejiang, PR China
| | - Yunjia Tu
- Department of Pediatrics, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, 109 Xueyuan Western Road, Wenzhou, Zhejiang 325027, PR China; The Second School of Medicine, Wenzhou Medical University, Wenzhou, Zhejiang, PR China
| | - Yuanai Li
- Department of Pediatrics, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, 109 Xueyuan Western Road, Wenzhou, Zhejiang 325027, PR China; The Second School of Medicine, Wenzhou Medical University, Wenzhou, Zhejiang, PR China
| | - Chunyan Ma
- Department of Pediatrics, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, 109 Xueyuan Western Road, Wenzhou, Zhejiang 325027, PR China; The Second School of Medicine, Wenzhou Medical University, Wenzhou, Zhejiang, PR China
| | - Adwoa Takyiwaa Gyabaah
- Department of Pediatrics, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, 109 Xueyuan Western Road, Wenzhou, Zhejiang 325027, PR China; The Second School of Medicine, Wenzhou Medical University, Wenzhou, Zhejiang, PR China
| | - Chenyi Yu
- Department of Pediatrics, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, 109 Xueyuan Western Road, Wenzhou, Zhejiang 325027, PR China; The Second School of Medicine, Wenzhou Medical University, Wenzhou, Zhejiang, PR China
| | - Zhijie Li
- Department of Pediatrics, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, 109 Xueyuan Western Road, Wenzhou, Zhejiang 325027, PR China
| | - Jiayi Chen
- Department of Pediatrics, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, 109 Xueyuan Western Road, Wenzhou, Zhejiang 325027, PR China; The Second School of Medicine, Wenzhou Medical University, Wenzhou, Zhejiang, PR China
| | - Zhilin Li
- Department of Pediatrics, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, 109 Xueyuan Western Road, Wenzhou, Zhejiang 325027, PR China; The Second School of Medicine, Wenzhou Medical University, Wenzhou, Zhejiang, PR China
| | - Zhi-Li Huang
- Department of Pharmacology, School of Basic Medical Sciences, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai 200032, PR China.
| | - Xiaohong Cai
- Department of Pediatrics, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, 109 Xueyuan Western Road, Wenzhou, Zhejiang 325027, PR China; The Second School of Medicine, Wenzhou Medical University, Wenzhou, Zhejiang, PR China.
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3
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Ale-Agha N, Goy C, Jakobs P, Spyridopoulos I, Gonnissen S, Dyballa-Rukes N, Aufenvenne K, von Ameln F, Zurek M, Spannbrucker T, Eckermann O, Jakob S, Gorressen S, Abrams M, Grandoch M, Fischer JW, Köhrer K, Deenen R, Unfried K, Altschmied J, Haendeler J. CDKN1B/p27 is localized in mitochondria and improves respiration-dependent processes in the cardiovascular system-New mode of action for caffeine. PLoS Biol 2018; 16:e2004408. [PMID: 29927970 PMCID: PMC6013014 DOI: 10.1371/journal.pbio.2004408] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2017] [Accepted: 05/18/2018] [Indexed: 12/16/2022] Open
Abstract
We show that the cyclin-dependent kinase inhibitor 1B (CDKN1B)/p27, previously known as a cell cycle inhibitor, is also localized within mitochondria. The migratory capacity of endothelial cells, which need intact mitochondria, is completely dependent on mitochondrial p27. Mitochondrial p27 improves mitochondrial membrane potential, increases adenosine triphosphate (ATP) content, and is required for the promigratory effect of caffeine. Domain mapping of p27 revealed that the N-terminus and C-terminus are required for those improvements. Further analysis of those regions revealed that the translocation of p27 into the mitochondria and its promigratory activity depend on serine 10 and threonine 187. In addition, mitochondrial p27 protects cardiomyocytes against apoptosis. Moreover, mitochondrial p27 is necessary and sufficient for cardiac myofibroblast differentiation. In addition, p27 deficiency and aging decrease respiration in heart mitochondria. Caffeine does not increase respiration in p27-deficient animals, whereas aged mice display improvement after 10 days of caffeine in drinking water. Moreover, caffeine induces transcriptome changes in a p27-dependent manner, affecting mostly genes relevant for mitochondrial processes. Caffeine also reduces infarct size after myocardial infarction in prediabetic mice and increases mitochondrial p27. Our data characterize mitochondrial p27 as a common denominator that improves mitochondria-dependent processes and define an increase in mitochondrial p27 as a new mode of action of caffeine.
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Affiliation(s)
- Niloofar Ale-Agha
- Heisenberg-group—Environmentally-induced Cardiovascular Degeneration, Medical Faculty, HHU Duesseldorf and IUF-Leibniz Research Institute for Environmental Medicine, Duesseldorf, Germany
| | - Christine Goy
- Heisenberg-group—Environmentally-induced Cardiovascular Degeneration, Medical Faculty, HHU Duesseldorf and IUF-Leibniz Research Institute for Environmental Medicine, Duesseldorf, Germany
| | - Philipp Jakobs
- Heisenberg-group—Environmentally-induced Cardiovascular Degeneration, Medical Faculty, HHU Duesseldorf and IUF-Leibniz Research Institute for Environmental Medicine, Duesseldorf, Germany
| | - Ioakim Spyridopoulos
- Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Stefanie Gonnissen
- Core Unit Biosafety Level 2 Laboratory, IUF-Leibniz Research Institute for Environmental Medicine, Duesseldorf, Germany
| | - Nadine Dyballa-Rukes
- Heisenberg-group—Environmentally-induced Cardiovascular Degeneration, Medical Faculty, HHU Duesseldorf and IUF-Leibniz Research Institute for Environmental Medicine, Duesseldorf, Germany
| | - Karin Aufenvenne
- Heisenberg-group—Environmentally-induced Cardiovascular Degeneration, Medical Faculty, HHU Duesseldorf and IUF-Leibniz Research Institute for Environmental Medicine, Duesseldorf, Germany
| | - Florian von Ameln
- Heisenberg-group—Environmentally-induced Cardiovascular Degeneration, Medical Faculty, HHU Duesseldorf and IUF-Leibniz Research Institute for Environmental Medicine, Duesseldorf, Germany
- Core Unit Biosafety Level 2 Laboratory, IUF-Leibniz Research Institute for Environmental Medicine, Duesseldorf, Germany
| | - Mark Zurek
- Heisenberg-group—Environmentally-induced Cardiovascular Degeneration, Medical Faculty, HHU Duesseldorf and IUF-Leibniz Research Institute for Environmental Medicine, Duesseldorf, Germany
| | - Tim Spannbrucker
- Environmentally-induced Skin and Lung Aging, IUF-Leibniz Research Institute for Environmental Medicine, Duesseldorf, Germany
| | - Olaf Eckermann
- Heisenberg-group—Environmentally-induced Cardiovascular Degeneration, Medical Faculty, HHU Duesseldorf and IUF-Leibniz Research Institute for Environmental Medicine, Duesseldorf, Germany
| | - Sascha Jakob
- Heisenberg-group—Environmentally-induced Cardiovascular Degeneration, Medical Faculty, HHU Duesseldorf and IUF-Leibniz Research Institute for Environmental Medicine, Duesseldorf, Germany
| | - Simone Gorressen
- Institute for Pharmacology and Clinical Pharmacology, Medical Faculty, HHU Duesseldorf, Duesseldorf, Germany
| | - Marcel Abrams
- Institute for Pharmacology and Clinical Pharmacology, Medical Faculty, HHU Duesseldorf, Duesseldorf, Germany
| | - Maria Grandoch
- Institute for Pharmacology and Clinical Pharmacology, Medical Faculty, HHU Duesseldorf, Duesseldorf, Germany
| | - Jens W. Fischer
- Institute for Pharmacology and Clinical Pharmacology, Medical Faculty, HHU Duesseldorf, Duesseldorf, Germany
| | - Karl Köhrer
- Biological and Medical Research Center (BMFZ), HHU, Duesseldorf, Germany
| | - René Deenen
- Biological and Medical Research Center (BMFZ), HHU, Duesseldorf, Germany
| | - Klaus Unfried
- Environmentally-induced Skin and Lung Aging, IUF-Leibniz Research Institute for Environmental Medicine, Duesseldorf, Germany
| | - Joachim Altschmied
- Core Unit Biosafety Level 2 Laboratory, IUF-Leibniz Research Institute for Environmental Medicine, Duesseldorf, Germany
| | - Judith Haendeler
- Heisenberg-group—Environmentally-induced Cardiovascular Degeneration, Medical Faculty, HHU Duesseldorf and IUF-Leibniz Research Institute for Environmental Medicine, Duesseldorf, Germany
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Lao-Peregrín C, Ballesteros JJ, Fernández M, Zamora-Moratalla A, Saavedra A, Gómez Lázaro M, Pérez-Navarro E, Burks D, Martín ED. Caffeine-mediated BDNF release regulates long-term synaptic plasticity through activation of IRS2 signaling. Addict Biol 2017; 22:1706-1718. [PMID: 27457910 PMCID: PMC5697621 DOI: 10.1111/adb.12433] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2016] [Revised: 06/23/2016] [Accepted: 06/27/2016] [Indexed: 11/27/2022]
Abstract
Caffeine has cognitive‐enhancing properties with effects on learning and memory, concentration, arousal and mood. These effects imply changes at circuital and synaptic level, but the mechanism by which caffeine modifies synaptic plasticity remains elusive. Here we report that caffeine, at concentrations representing moderate to high levels of consumption in humans, induces an NMDA receptor‐independent form of LTP (CAFLTP) in the CA1 region of the hippocampus by promoting calcium‐dependent secretion of BDNF, which subsequently activates TrkB‐mediated signaling required for the expression of CAFLTP. Our data include the novel observation that insulin receptor substrate 2 (IRS2) is phosphorylated during induction of CAFLTP, a process that requires cytosolic free Ca2+. Consistent with the involvement of IRS2 signals in caffeine‐mediated synaptic plasticity, phosphorylation of Akt (Ser473) in response to LTP induction is defective in Irs2−/− mice, demonstrating that these plasticity changes are associated with downstream targets of the phosphoinositide 3‐kinase (PI3K) pathway. These findings indicate that TrkB‐IRS2 signals are essential for activation of PI3K during the induction of LTP by caffeine.
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Affiliation(s)
- Cristina Lao-Peregrín
- Laboratory of Neurophysiology and Synaptic Plasticity, Castilla-La Mancha Science and Technology Park (PCYTCLM), Institute for Research in Neurological Disabilities (IDINE); University of Castilla-La Mancha; Spain
| | - Jesús Javier Ballesteros
- Laboratory of Neurophysiology and Synaptic Plasticity, Castilla-La Mancha Science and Technology Park (PCYTCLM), Institute for Research in Neurological Disabilities (IDINE); University of Castilla-La Mancha; Spain
| | - Miriam Fernández
- Laboratory of Neurophysiology and Synaptic Plasticity, Castilla-La Mancha Science and Technology Park (PCYTCLM), Institute for Research in Neurological Disabilities (IDINE); University of Castilla-La Mancha; Spain
| | - Alfonsa Zamora-Moratalla
- Laboratory of Neurophysiology and Synaptic Plasticity, Castilla-La Mancha Science and Technology Park (PCYTCLM), Institute for Research in Neurological Disabilities (IDINE); University of Castilla-La Mancha; Spain
| | - Ana Saavedra
- Departament de Biomedicina, Facultat de Medicina; Universitat de Barcelona; Spain
- Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS); Spain
- Centro de Investigación Biomédica en Red (CIBER) sobre Enfermedades Neurodegenerativas (CIBERNED); Spain
- Institut de Neurociències; Universitat de Barcelona; Spain
| | - María Gómez Lázaro
- Laboratory of Neurophysiology and Synaptic Plasticity, Castilla-La Mancha Science and Technology Park (PCYTCLM), Institute for Research in Neurological Disabilities (IDINE); University of Castilla-La Mancha; Spain
| | - Esther Pérez-Navarro
- Departament de Biomedicina, Facultat de Medicina; Universitat de Barcelona; Spain
- Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS); Spain
- Centro de Investigación Biomédica en Red (CIBER) sobre Enfermedades Neurodegenerativas (CIBERNED); Spain
- Institut de Neurociències; Universitat de Barcelona; Spain
| | - Deborah Burks
- Centro de Investigación Príncipe Felipe, CIBER de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM); Spain
| | - Eduardo D. Martín
- Laboratory of Neurophysiology and Synaptic Plasticity, Castilla-La Mancha Science and Technology Park (PCYTCLM), Institute for Research in Neurological Disabilities (IDINE); University of Castilla-La Mancha; Spain
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5
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Low, but not high, dose caffeine is a readily available probe for adenosine actions. Mol Aspects Med 2016; 55:20-25. [PMID: 27915051 DOI: 10.1016/j.mam.2016.11.011] [Citation(s) in RCA: 58] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2016] [Revised: 11/23/2016] [Accepted: 11/23/2016] [Indexed: 12/21/2022]
Abstract
Caffeine is very widely used and knowledge of its mode of action can be used to gain an understanding of basal physiological regulation. This review makes the point that caffeine is - in low doses - an antagonist of adenosine acting at A1, A2A and A2B receptors. We use published and unpublished data to make the point that high dose effects of caffeine are not only qualitatively different but have a different underlying mechanism. Therefore one must be careful in only using epidemiological or experimental data where rather low doses of caffeine are used to draw conclusions about the physiology and pathophysiology of adenosine.
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Quintanilla G, Usarralde Á, Pérez I, Gargiulo ML, Yakupoglu G, Martín A, Barba F. Anodic Oxidation of Caffeine and Theophylline in Glacial Acetic Acid. ChemistrySelect 2016. [DOI: 10.1002/slct.201500047] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Affiliation(s)
- Gloria Quintanilla
- Departamento de Química Orgánica y Química Inorgánica; Universidad de Alcalá; 28871 Alcalá de Henares Madrid Spain
| | - Ángela Usarralde
- Departamento de Química Orgánica y Química Inorgánica; Universidad de Alcalá; 28871 Alcalá de Henares Madrid Spain
| | - Iván Pérez
- Departamento de Química Orgánica y Química Inorgánica; Universidad de Alcalá; 28871 Alcalá de Henares Madrid Spain
| | - Maria L. Gargiulo
- Departamento de Química Orgánica y Química Inorgánica; Universidad de Alcalá; 28871 Alcalá de Henares Madrid Spain
| | - Gökce Yakupoglu
- Departamento de Química Orgánica y Química Inorgánica; Universidad de Alcalá; 28871 Alcalá de Henares Madrid Spain
| | - Avelino Martín
- Departamento de Química Orgánica y Química Inorgánica; Universidad de Alcalá; 28871 Alcalá de Henares Madrid Spain
| | - Fructuoso Barba
- Departamento de Química Orgánica y Química Inorgánica; Universidad de Alcalá; 28871 Alcalá de Henares Madrid Spain
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Jameel MN, Xiong Q, Mansoor A, Bache RJ, Zhang J. ATP sensitive K(+) channels are critical for maintaining myocardial perfusion and high energy phosphates in the failing heart. J Mol Cell Cardiol 2016; 92:116-21. [PMID: 26854629 DOI: 10.1016/j.yjmcc.2016.02.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/04/2015] [Revised: 01/21/2016] [Accepted: 02/04/2016] [Indexed: 01/08/2023]
Abstract
Congestive heart failure (CHF) is associated with intrinsic alterations of mitochondrial oxidative phosphorylation which lead to increased myocardial cytosolic free ADP. ATP sensitive K(+) channels (KATP) act as metabolic sensors that are important for maintaining coronary blood flow (MBF) and in mediating the response of the myocardium to stress. Coronary adenosine receptors (AdR) are not normally active but cause vasodilation during myocardial ischemia. This study examined the myocardial energetic response to inhibition of KATP and AdR in CHF. CHF (as evidenced by LVEDP>20mmHg) was produced in adult mongrel dogs (n=12) by rapid ventricular pacing for 4weeks. MBF was measured with radiolabeled microspheres during baseline (BL), AdR blockade with 8-phenyltheophylline (8-PT; 5mg/kg iv), and KATP blockade with glibenclamide (GLB; 20μg/kg/min ic). High energy phosphates were examined with (31)P magnetic resonance spectroscopy (MRS) while myocardial oxygenation was assessed from the deoxymyoglobin signal (Mb-δ) using (1)H MRS. During basal conditions the phosphocreatine (PCr)/ATP ratio (1.73±0.15) was significantly lower than in previously studied normal dogs (2.42±0.11) although Mb-δ was undetectable. 8-PT caused ≈21% increase in MBF with no change in PCr/ATP. GLB caused a 33±0.1% decrease in MBF with a decrease in PCr/ATP from 1.65±0.17 to 1.11±0.11 (p<0.0001). GLB did not change the pseudo-first-order rate constant of ATP production via CK (kf), but the ATP production rate via CK was reduced by 35±0.08%; this was accompanied by an increase in Pi/PCr and appearance of a Mb-δ signal indicating tissue hypoxia. Thus, in the failing heart the balance between myocardial ATP demands and oxygen delivery is critically dependent on functioning KATP channels.
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Affiliation(s)
- Mohammad N Jameel
- Department of Medicine, University of Minnesota Medical School, Minneapolis, MN 55455, USA
| | - Qiang Xiong
- Department of Medicine, University of Minnesota Medical School, Minneapolis, MN 55455, USA
| | - Abdul Mansoor
- Department of Medicine, University of Minnesota Medical School, Minneapolis, MN 55455, USA
| | - Robert J Bache
- Department of Medicine, University of Minnesota Medical School, Minneapolis, MN 55455, USA
| | - Jianyi Zhang
- Department of Medicine, University of Minnesota Medical School, Minneapolis, MN 55455, USA; Department of Biomedical Engineering, School of Medicine, School of Engineering, University of Alabama at Birmingham, Birmingham, AL 35294, USA.
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Syce DV. A Cup of Black Tea Does Not Modify Heart Rate Variability. JOURNAL OF CAFFEINE RESEARCH 2015. [DOI: 10.1089/jcr.2014.0016] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Affiliation(s)
- Dinesh Vedanathan Syce
- Department of Physiology, Pondicherry Institute of Medical Sciences (PIMS), Pondicherry, India
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Petzer A, Pienaar A, Petzer JP. The interactions of caffeine with monoamine oxidase. Life Sci 2013; 93:283-7. [PMID: 23850513 DOI: 10.1016/j.lfs.2013.06.020] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2013] [Revised: 06/19/2013] [Accepted: 06/27/2013] [Indexed: 11/25/2022]
Abstract
AIMS Caffeine has been used as a scaffold for the design of inhibitors of monoamine oxidase (MAO) A and B. Substitution at the C8 position with a variety of moieties yields structures with high MAO inhibition potencies. Although the MAO inhibitory properties of numerous caffeine derivatives have been characterized, the possibility that caffeine inhibits the MAOs has not been investigated in detail. Based on the therapeutic applications and potential adverse effects of MAO inhibition, this study examines the interactions of caffeine with the MAOs. MAIN METHODS Employing the recombinant human enzymes, the potencies by which caffeine inhibits the in vitro catalytic activities of the MAOs were recorded and expressed as the IC₅₀ and Ki values. The reversibility of inhibition was determined by measuring the recovery of enzyme activity after dialysis of enzyme-caffeine mixtures. KEY FINDINGS Caffeine acts as a MAO inhibitor with Ki values of 0.70 mM and 3.83 mM for the inhibition of MAO-A and MAO-B, respectively. The results show that caffeine binds reversibly and competitively to both MAO enzymes. SIGNIFICANCE Although structural modifications of caffeine lead to highly potent MAO inhibitors, caffeine is a weak inhibitor of MAO-A and MAO-B. At plasma concentrations (approximately 1-10 μM) achieved by normal human consumption, the MAO inhibitory potencies of caffeine are unlikely to be of pharmacological relevance in humans. The MAO inhibitory effects of caffeine should however be taken into consideration when using this drug in vitro and in tissue culture experiments where higher doses and concentrations of caffeine are often used.
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Affiliation(s)
- Anél Petzer
- Centre of Excellence for Pharmaceutical Sciences, School of Pharmacy, North-West University, Private Bag X6001, Potchefstroom, 2520, South Africa.
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Alzoubi K, Abdul-Razzak K, Khabour O, Al-Tuweiq G, Alzubi M, Alkadhi K. Caffeine prevents cognitive impairment induced by chronic psychosocial stress and/or high fat–high carbohydrate diet. Behav Brain Res 2013; 237:7-14. [DOI: 10.1016/j.bbr.2012.09.018] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2012] [Revised: 09/08/2012] [Accepted: 09/13/2012] [Indexed: 11/26/2022]
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Chronic Caffeine Treatment Prevents Stress-Induced LTP Impairment: the Critical Role of Phosphorylated CaMKII and BDNF. J Mol Neurosci 2012; 49:11-20. [DOI: 10.1007/s12031-012-9836-z] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2012] [Accepted: 06/06/2012] [Indexed: 10/28/2022]
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12
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Mustard JA, Dews L, Brugato A, Dey K, Wright GA. Consumption of an acute dose of caffeine reduces acquisition but not memory in the honey bee. Behav Brain Res 2012; 232:217-24. [PMID: 22521838 DOI: 10.1016/j.bbr.2012.04.014] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2011] [Revised: 03/28/2012] [Accepted: 04/08/2012] [Indexed: 11/30/2022]
Abstract
Caffeine affects several molecules that are also involved in the processes underlying learning and memory such as cAMP and calcium. However, studies of caffeine's influence on learning and memory in mammals are often contradictory. Invertebrate model systems have provided valuable insight into the actions of many neuroactive compounds including ethanol and cocaine. We use the honey bee (Apis mellifera) to investigate how the ingestion of acute doses of caffeine before, during, and after conditioning influences performance in an appetitive olfactory learning and memory task. Consumption of caffeine doses of 0.01 M or greater during or prior to conditioning causes a significant reduction in response levels during acquisition. Although bees find the taste of caffeine to be aversive at high concentrations, the bitter taste does not explain the reduction in acquisition observed for bees fed caffeine before conditioning. While high doses of caffeine reduced performance during acquisition, the response levels of bees given caffeine were the same as those of the sucrose only control group in a recall test 24h after conditioning. In addition, caffeine administered after conditioning had no affect on recall. These results suggest that caffeine specifically affects performance during acquisition and not the processes involved in the formation of early long term memory.
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Affiliation(s)
- Julie A Mustard
- School of Life Sciences, Arizona State University, PO Box 874501, Tempe, AZ 85281, USA.
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Alhaider IA, Aleisa AM, Tran TT, Alkadhi KA. Sleep deprivation prevents stimulation-induced increases of levels of P-CREB and BDNF: protection by caffeine. Mol Cell Neurosci 2011; 46:742-51. [PMID: 21338685 DOI: 10.1016/j.mcn.2011.02.006] [Citation(s) in RCA: 96] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2010] [Revised: 02/02/2011] [Accepted: 02/11/2011] [Indexed: 01/12/2023] Open
Abstract
It is well known that caffeine and sleep deprivation have opposing effects on learning and memory; therefore, this study was undertaken to determine the effects of chronic (4wks) caffeine treatment (0.3g/l in drinking water) on long-term memory deficit associated with 24h sleep deprivation. Animals were sleep deprived using the modified multiple platform method. The results showed that chronic caffeine treatment prevented the impairment of long-term memory as measured by performance in the radial arm water maze task and normalized L-LTP in area CA1 of the hippocampi of sleep-deprived anesthetized rats. Sleep deprivation prevents the high frequency stimulation-induced increases in the levels of phosphorylated-cAMP response element binding protein (P-CREB) and brain-derived neurotrophic factor (BDNF) seen during the expression of late phase long-term potentiation (L-LTP). However, chronic caffeine treatment prevented the effect of sleep-deprivation on the stimulated levels of P-CREB and BDNF. The results suggest that chronic caffeine treatment may protect the sleep-deprived brain probably by preserving the levels of P-CREB and BDNF.
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Affiliation(s)
- Ibrahim A Alhaider
- Department of Pharmacological and Pharmaceutical Sciences, College of Pharmacy, University of Houston, Houston, TX, USA
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Francis SH, Sekhar KR, Ke H, Corbin JD. Inhibition of cyclic nucleotide phosphodiesterases by methylxanthines and related compounds. Handb Exp Pharmacol 2011:93-133. [PMID: 20859794 DOI: 10.1007/978-3-642-13443-2_4] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Naturally occurring methylxanthines were the first inhibitors of cyclic nucleotide (cN) phosphodiesterases (PDEs) to be discovered. To improve potency and specificity for inhibition of various PDEs in research and for treatment of diseases, thousands of compounds with related structures have now been synthesized. All known PDE inhibitors contain one or more rings that mimic the purine in the cN substrate and directly compete with cN for access to the catalytic site; this review focuses on inhibitors that contain a nucleus that is closely related to the xanthine ring of theophylline and caffeine and the purine ring of cNs. The specificity and potency of these compounds for blocking PDE action have been improved by appending groups at positions on the rings as well as by modification of the number and distribution of nitrogens and carbons in those rings. Several of these inhibitors are highly selective for particular PDEs; potent and largely selective PDE5 inhibitors are used clinically for treatment of erectile dysfunction [sildenafil (Viagra™), tadalafil (Cialis™) and vardenafil (Levitra™)] and pulmonary hypertension [sildenafil (Revatio™) and tadalafil (Adenocirca)]. Related compounds target other PDEs and show therapeutic promise for a number of maladies.
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Affiliation(s)
- Sharron H Francis
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN 37232-0615, USA.
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15
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Sturgess JE, Ting-A-Kee RA, Podbielski D, Sellings LHL, Chen JF, van der Kooy D. Adenosine A1 and A2A receptors are not upstream of caffeine's dopamine D2 receptor-dependent aversive effects and dopamine-independent rewarding effects. Eur J Neurosci 2010; 32:143-54. [PMID: 20576036 DOI: 10.1111/j.1460-9568.2010.07247.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Caffeine is widely consumed throughout the world, but little is known about the mechanisms underlying its rewarding and aversive properties. We show that pharmacological antagonism of dopamine not only blocks conditioned place aversion to caffeine, but also reveals dopamine blockade-induced conditioned place preferences. These aversive effects are mediated by the dopamine D(2) receptor, as knockout mice showed conditioned place preferences in response to doses of caffeine that C57Bl/6 mice found aversive. Furthermore, these aversive responses appear to be centrally mediated, as a quaternary analog of caffeine failed to produce conditioned place aversion. Although the adenosine A(2A) receptor is important for caffeine's physiological effects, this receptor seems only to modulate the appetitive and aversive effects of caffeine. A(2A) receptor knockout mice showed stronger dopamine-dependent aversive responses to caffeine than did C57Bl/6 mice, which partially obscured the dopamine-independent and A(2A) receptor-independent preferences. Additionally, the A(1) receptor, alone or in combination with the A(2A) receptor, does not seem to be important for caffeine's rewarding or aversive effects. Finally, excitotoxic lesions of the tegmental pedunculopontine nucleus revealed that this brain region is not involved in dopamine blockade-induced caffeine reward. These data provide surprising new information on the mechanism of action of caffeine, indicating that adenosine receptors do not mediate caffeine's appetitive and aversive effects. We show that caffeine has an atypical reward mechanism, independent of the dopaminergic system and the tegmental pedunculopontine nucleus, and provide additional evidence in support of a role for the dopaminergic system in aversive learning.
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Affiliation(s)
- Jessica E Sturgess
- Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada.
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Alhaider IA, Aleisa AM, Tran TT, Alkadhi KA. Caffeine prevents sleep loss-induced deficits in long-term potentiation and related signaling molecules in the dentate gyrus. Eur J Neurosci 2010; 31:1368-76. [DOI: 10.1111/j.1460-9568.2010.07175.x] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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17
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Nantwi KD. Recovery of respiratory activity after C2 hemisection (C2HS): involvement of adenosinergic mechanisms. Respir Physiol Neurobiol 2009; 169:102-14. [PMID: 19651244 DOI: 10.1016/j.resp.2009.07.014] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2009] [Revised: 07/14/2009] [Accepted: 07/14/2009] [Indexed: 11/18/2022]
Abstract
Consequences of spinal cord injury (SCI) depend on the level and extent of injury. Cervical SCI often results in a compromised respiratory system. Primary treatment of SCI patients with respiratory insufficiency continues to be with mechanical ventilatory support. In an animal model of SCI, an upper cervical spinal cord hemisection paralyzes the hemidiaphragm ipsilateral to the side of injury. However, a latent respiratory motor pathway can be activated to restore respiratory function after injury. In this review, restoration of respiratory activity following systemic administration of theophylline, a respiratory stimulant will be discussed. Pharmacologically, theophylline is a non-specific adenosine receptor antagonist, a phosphodiesterase inhibitor and a bronchodilator. It has been used in the treatment of asthma and other respiratory-related diseases such as chronic obstructive pulmonary disease (COPD) and in treatment of apnea in premature infants. However, the clinical use of theophylline to improve respiration in SCI patients with respiratory deficits is a more recent approach. This review will focus on the use of theophylline to restore respiratory activity in an animal model of SCI. In this model, a C2 hemisection (C2HS) interrupts the major descending respiratory pathways and paralyzes the ipsilateral hemidiaphragm. The review also highlights involvement of central and peripheral adenosine receptors in functional restitution. Biochemical binding assays that highlight changes in adenosine receptors after chronic theophylline administration are discussed as they pertain to understanding adenosine receptor-mediation in functional recovery. Finally, the clinical application of theophylline in SCI patients with respiratory deficits in particular is discussed.
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Affiliation(s)
- Kwaku D Nantwi
- Department of Anatomy and Cell Biology, Wayne State University School of Medicine, Detroit, MI 48202, USA.
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Abstract
John Daly played an important role in defining adenosine receptors as an important target for drug discovery. His systematic work characterized the effects of adenosine analogues on cyclic AMP in the brain that were antagonized by methylxanthines. He also played a decisive role in establishing these receptors as bona fide biochemical entities and contributed to the discovery of receptor heterogeneity. This brief review will cover some of his important early discoveries in the pharmacology and medicinal chemistry of adenosine receptors.
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Affiliation(s)
- Bertil B Fredholm
- Department of Physiology and Pharmacology, Karolinska Institutet, S-171 77 Stockholm, Sweden
| | - Kenneth A Jacobson
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, USA 20892
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Calabrese EJ. Addiction and Dose Response: The Psychomotor Stimulant Theory of Addiction Reveals That Hormetic Dose Responses Are Dominant. Crit Rev Toxicol 2008; 38:599-617. [DOI: 10.1080/10408440802026315] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Rofecoxib, a selective cyclooxygenase-2 (COX-2) inhibitor increases pentylenetetrazol seizure threshold in mice: possible involvement of adenosinergic mechanism. Epilepsy Res 2007; 78:60-70. [PMID: 18054463 DOI: 10.1016/j.eplepsyres.2007.10.008] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2007] [Revised: 10/21/2007] [Accepted: 10/24/2007] [Indexed: 01/26/2023]
Abstract
Multiple lines of investigations have explored the role of cyclooxygenases (COX) in epilepsy and related neuropsychiatric disorders. Cyclooxygenase particularly, COX-2 expression was found to increase in brain during seizure paradigms. The present study was carried out to investigate the effect of rofecoxib, a selective COX-2 inhibitor against pentylenetetrazol (PTZ i.v.) seizure threshold in mice. The study was further extended to elucidate the possible involvement of adenosinergic mechanism in mediating its anticonvulsant action. Minimal dose of PTZ (i.v., mg/kg) needed to induce different phases (myoclonic jerks, generalized clonus and tonic extension) of PTZ convulsions were noted as an index of seizure threshold. Acute administration of rofecoxib (4mg/kg, i.p.) before PTZ infusion produced an elevation of seizure threshold for all the phases of convulsions. A lower dose of rofecoxib (2mg/kg, i.p.) showed an increase in PTZ seizure threshold for the onset of myoclonic jerks and tonic extension phases but not for generalized clonus. A still lower dose of rofecoxib (1mg/kg, i.p.) failed to increase the threshold in any of the convulsive phases induced by PTZ i.v. infusion. Pretreatment with sub-effective dose of rofecoxib (1mg/kg, i.p.) enhanced the action of sub-protective doses of either adenosine (25mg/kg, i.p.) or 2-chloroadenosine (1 or 2mg/kg, i.p.) in increasing the seizure threshold. On the contrary, treatment with caffeine (100 or 200mg/kg, i.p.) or theophylline (50 or 100mg/kg, i.p.), both non-selective A(1)/A(2) adenosine receptor antagonists reversed the anticonvulsant effect of rofecoxib (4mg/kg, i.p.). Further, dipyridamole (5mg/kg, i.p.), an adenosine uptake inhibitor displayed an anticonvulsant effect with rofecoxib (1mg/kg, i.p.). The study for the first time demonstrated the possible involvement of adenosinergic system in the anticonvulsant effects of rofecoxib against PTZ i.v. seizure threshold paradigm in mice.
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Traverse JH, Chen Y, Hou M, Li Y, Bache RJ. Effect of K+ATP channel and adenosine receptor blockade during rest and exercise in congestive heart failure. Circ Res 2007; 100:1643-9. [PMID: 17478726 DOI: 10.1161/circresaha.107.150219] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
K(+)(ATP) channels are important metabolic regulators of coronary blood flow (CBF) that are activated in the setting of reduced levels of ATP or perfusion pressure. In the normal heart, blockade of K(+)(ATP) channels results in a approximately 20% reduction in resting CBF but does not impair the increase in CBF that occurs during exercise. In contrast, adenosine receptor blockade fails to alter CBF or myocardial oxygen consumption (MVO(2)) in the normal heart but contributes to the increase in CBF during exercise when vascular K(+)(ATP) channels are blocked. Congestive heart failure (CHF) is associated with a decrease in CBF that is matched to a decrease in MVO(2) suggesting downregulation of myocardial energy utilization. Because myocardial ATP levels and coronary perfusion pressure are reduced in CHF, this study was undertaken to examine the role of K(+)(ATP) channels and adenosine in dogs with pacing-induced CHF. Myocardial blood flow (MBF) and MVO(2) were measured during rest and treadmill exercise before and after K(+)(ATP) channel blockade with glibenclamide (50 microg/kg/min ic) or adenosine receptor blockade with 8-phenyltheophylline (8-PT; 5 mg/kg iv). Inhibition of K(+)(ATP) channels resulted in a decrease in CBF and MVO(2) at rest and during exercise without a change in the relationship between CBF and MVO(2). In contrast, adenosine receptor blockade caused a significant increase in CBF that occurred secondary to an increase of MVO(2). These findings demonstrate that coronary K(+)(ATP) channel activity contribute to the regulation of resting MBF in CHF, and that endogenous adenosine may act to inhibit MVO(2) in the failing heart.
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Affiliation(s)
- Jay H Traverse
- Department of Medicine, University of Minnesota Medical School, Minneapolis, MN 55455, USA.
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22
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Celenza KM, Shugert E, Vélez SJ. Depressing Effect of Caffeine at Crayfish Neuromuscular Synapses II. Initial Search for Possible Sites of Action. Cell Mol Neurobiol 2007; 27:381-93. [PMID: 17235692 DOI: 10.1007/s10571-006-9131-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2006] [Accepted: 11/02/2006] [Indexed: 11/26/2022]
Abstract
Caffeine's unexpected depression of synaptic transmission in the superficial flexor muscle system (SFM) of Procambarus clarkii was studied by looking at three known sites of action of this drug: via adenosine and ryanodine receptors and inhibition of phosphodiesterase.1. JPs did not change in size when exposed to physiological concentrations of adenosine, suggesting that the SFM system lacks presynaptic adenosine receptors.2. JPs slightly increased in size in the presence of a phosphodiesterase inhibitor, the opposite response to that obtained with caffeine, suggesting that caffeine is not acting via this pathway.3. A calcium ionophore immediately enhanced synaptic transmission in the SFM system but when given in combination with caffeine the enhancement is reduced and declines over time.4. Serotonin enhanced synaptic transmission in the SFM system, but when given in combination with caffeine this enhancement was not observed.5. These caffeine effects are interpreted in terms of alterations to the calcium homeostatic mechanisms of the terminals.
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Affiliation(s)
- Kathryn M Celenza
- Department of Biological Sciences, Dartmouth College, Hanover, NH 03755, USA
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Hashimoto S, Huang Y, Briggs J, Schnermann J. Reduced autoregulatory effectiveness in adenosine 1 receptor-deficient mice. Am J Physiol Renal Physiol 2005; 290:F888-91. [PMID: 16263804 DOI: 10.1152/ajprenal.00381.2005] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Adjustments of renal vascular resistance in response to changes in blood pressure are mediated by an interplay between the myocyte-inherent myogenic and the kidney-specific tubuloglomerular feedback (TGF) mechanisms. Using mice with deletion of the A(1) adenosine receptor (A1AR) gene, we tested the prediction that the absence of TGF, previously established to result from A1AR deficiency, is associated with a reduction in the efficiency of autoregulation. In anesthetized wild-type (A1AR+/+) and A1AR-deficient mice (A1AR-/-), glomerular filtration rate (GFR) and renal blood flow (RBF) were determined before and after reducing renal perfusion pressure through a suprarenal aortic clamp. In response to a blood pressure reduction by 15.9 +/- 1.34 mmHg in A1AR-/- (n = 9) and by 14.2 +/- 0.9 mmHg in A1AR+/+ mice (n = 8; P = 0.31), GFR fell by 187.9 +/- 37 mul/min and by 72.3 +/- 10 mul/min in A1AR-/- and A1AR+/+ mice, respectively (P = 0.013). Similarly, with pressure reductions of 14.8 +/- 1.1 and 13.3 +/- 1.5 mmHg in A1AR-/- (n = 9) and wild-type mice (n = 8), respectively (P = 0.43), RBF fell by 0.17 +/- 0.02 ml/min in A1AR-/- mice and by only 0.08 +/- 0.02 ml/min in wild-type animals (P = 0.0039). Autoregulatory indexes for both GFR and RBF were significantly higher in A1AR-/- compared with A1AR+/+ mice, indicating reduced regulatory responsiveness in the knockout animals. We conclude that autoregulation of renal vascular resistance is less complete in A1AR-deficient mice, an effect that is presumably related to absence of TGF regulation in these animals.
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Affiliation(s)
- S Hashimoto
- National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, USA
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Magkos F, Kavouras SA. Caffeine Use in Sports, Pharmacokinetics in Man, and Cellular Mechanisms of Action. Crit Rev Food Sci Nutr 2005; 45:535-62. [PMID: 16371327 DOI: 10.1080/1040-830491379245] [Citation(s) in RCA: 202] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Caffeine is the most widely consumed psychoactive 'drug' in the world and probably one of the most commonly used stimulants in sports. This is not surprising, since it is one of the few ergogenic aids with documented efficiency and minimal side effects. Caffeine is rapidly and completely absorbed by the gastrointestinal tract and is readily distributed throughout all tissues of the body. Peak plasma concentrations after normal consumption are usually around 50 microM, and half-lives for elimination range between 2.5-10 h. The parent compound is extensively metabolized in the liver microsomes to more than 25 derivatives, while considerably less than 5% of the ingested dose is excreted unchanged in the urine. There is, however, considerable inter-individual variability in the handling of caffeine by the body, due to both environmental and genetic factors. Evidence from in vitro studies provides a wealth of different cellular actions that could potentially contribute to the observed effects of caffeine in humans in vivo. These include potentiation of muscle contractility via induction of sarcoplasmic reticulum calcium release, inhibition of phosphodiesterase isoenzymes and concomitant cyclic monophosphate accumulation, inhibition of glycogen phosphorylase enzymes in liver and muscle, non-selective adenosine receptor antagonism, stimulation of the cellular membrane sodium/potassium pump, impairment of phosphoinositide metabolism, as well as other, less thoroughly characterized actions. Not all, however, seem to account for the observed effects in vivo, although a variable degree of contribution cannot be readily discounted on the basis of experimental data. The most physiologically relevant mechanism of action is probably the blockade of adenosine receptors, but evidence suggests that, at least under certain conditions, other biochemical mechanisms may also be operational.
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Affiliation(s)
- Faidon Magkos
- Laboratory of Nutrition and Clinical Dietetics, Department of Nutrition and Dietetics, Harokopio University, 176 71 Kallithea, Athens, Greece
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Hoexter MQ, Rosa PS, Tufik S, Mello LE. Consequences of Prolonged Caffeine Administration and Its Withdrawal on Pilocarpine- and Kainate-induced Seizures in Rats. Epilepsia 2005; 46:1401-6. [PMID: 16146434 DOI: 10.1111/j.1528-1167.2005.63904.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
PURPOSE To investigate the consequences of caffeine consumption on epileptic seizures, we used the pilocarpine and the kainate models of epilepsy. We hypothesized that prolonged caffeine consumption or its withdrawal would alter adenosine levels and hence alter seizure susceptibility. METHODS We administered a 0.1% caffeine solution in the drinking water of adult male Wistar rats over a 2-week period. We challenged another group of animals with the same doses of pilocarpine or kainate 12 h after the withdrawal of the same caffeine-administration protocol. RESULTS This did not alter the threshold for the induction of seizures by a subconvulsant dose of pilocarpine (200 mg/kg, i.p.) or kainic acid (8 mg/kg, i.p.). Similarly, challenging another group of animals with the same doses of pilocarpine or kainate 12 h after the withdrawal of the same caffeine-administration protocol did not lead to any significant changes in seizures. CONCLUSIONS With the pilocarpine model of epilepsy, we were not able to find any significant difference in seizure profile that could stem from either caffeine administration or its withdrawal. Despite the extensive laboratory evidence on the convulsant properties of xanthine derivatives in animal models of epilepsy, such strong evidence is lacking in clinical settings. Our current findings with the administration of caffeine at doses similar to those of daily life both support and confirm the clinical experience.
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Zhang J, From AHL, Ugurbil K, Bache RJ. Myocardial oxygenation and high-energy phosphate levels during KATP channel blockade. Am J Physiol Heart Circ Physiol 2003; 285:H1420-7. [PMID: 12805030 DOI: 10.1152/ajpheart.00167.2003] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Inhibition of ATP-sensitive K+ (KATP) channel activity has previously been demonstrated to result in coronary vasoconstriction with decreased myocardial blood flow and loss of phosphocreatine (PCr). This study was performed to determine whether the high-energy phosphate abnormality during KATP channel blockade can be ascribed to oxygen insufficiency. Myocardial blood flow and oxygen extraction were measured in open-chest dogs during KATP channel blockade with intracoronary glibenclamide, whereas high-energy phosphates were examined with 31P magnetic resonance spectroscopy (MRS), and myocardial deoxymyoglobin (Mb-delta) was determined with 1H MRS. Glibenclamide resulted in a 20 +/- 8% decrease of myocardial blood flow that was associated with a loss of phosphocreatine (PCr) and accumulation of inorganic phosphate. Mb-delta was undetectable during basal conditions but increased to 58 +/- 5% of total myoglobin during glibenclamide administration. This degree of myoglobin desaturation during glibenclamide was far greater than we previously observed during a similar reduction of blood flow produced by a coronary stenosis (22% of myoglobin deoxygenated during stenosis). The findings suggest that reduction of coronary blood flow with an arterial stenosis was associated with a decrease of myocardial energy demands and that this response to hypoperfusion was inhibited by KATP channel blockade.
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Affiliation(s)
- Jianyi Zhang
- Department of Medicine and Center for Megnetic Resonance Research, University of Minnesota Health Science Center, Mayo Mail Code 508, 420 Delaware St. SE, Minneapolis, MN 55455, USA.
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Wang SJ, Sihra TS. Opposing facilitatory and inhibitory modulation of glutamate release elicited by cAMP production in cerebrocortical nerve terminals (synaptosomes). Neuropharmacology 2003; 44:686-97. [PMID: 12668054 DOI: 10.1016/s0028-3908(03)00045-5] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Activation of cAMP-protein kinase A (PKA) is widely reported to facilitate synaptic transmission. Here, we examined the presynaptic loci of PKA action using isolated nerve terminals (synaptosoms). The adenylyl cyclase (AC) activator, forskolin, failed to have any effect on 4-aminopyridine (4-AP)-evoked glutamate release, when added alone. However, in the presence of the alkylxanthine, IBMX, forskolin strongly facilitated glutamate release. This potentiation of release was blocked by the PKA inhibitors Rp-cAMPS and H7. Given that IBMX has dual activity, antagonizing adenosine receptors as well as inhibiting cAMP phosphodiesterase, we examined the effect of a selective adenosine A(1) receptor antagonist, 8-cyclopentyl-1,3-dipropylxanthine (DPCPX) and RO20-1724, a specific phosphodiesterase inhibitor. Both unmasked the forskolin-mediated modulation of glutamate release. Conversely, the adenosine analogue, N(6)-cyclohexyladenosine (CHA), reversed the facilitation induced by forskolin+RO20-1724. Adenosine A(1) receptor activation, therefore, appears to curtail cAMP/PKA-induced potentiation of glutamate release. Looking at the targets for cAMP/PKA-mediated potentiation of glutamate release, while synaptosomal excitability was only marginally increased, basal and 4-AP-evoked-increases in [Ca(2+)](c) were substantially enhanced by forskolin+IBMX. Moreover, glutamate release elicited by Ca(2+)-ionophore (ionomycin)-induced Ca(2+)-entry was facilitated by forskolin+IBMX. cAMP/PKA-mediated facilitation of glutamate release may therefore involve modulation of Ca(2+)-entry, as well as downstream events controlling synaptic vesicle recruitment and exocytosis.
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Affiliation(s)
- S J Wang
- Department of Pharmacology, University College London, Medawar Building, Gower Street, UK
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Fujii S, Kuroda Y, Li J, Ito K, Kaneko K, Sasaki H, Kato H. The temperature-dependent modulation of an inhibitory circuit in hippocampal slices as revealed by a population spike recording is mediated by extracellular adenosine. THE JAPANESE JOURNAL OF PHYSIOLOGY 2001; 51:545-54. [PMID: 11734074 DOI: 10.2170/jjphysiol.51.545] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
We examined the effects of temperature on excitatory synaptic transmission and the recurrent inhibitory loop in CA1 neurons in guinea pig hippocampal slices. Increasing the temperature of the perfusing medium from 30 to 49 degrees C resulted in attenuation of both the amplitude of the synaptically evoked CA1 population spikes and the paired-pulse inhibition (PPI) of the spikes. A bath application of 2 microM picrotoxin, a gamma-aminobutyric acid receptor antagonist, did not affect the amplitude of the CA1 population spikes, but it significantly reduced PPI during the early heating phase (30-32 degrees C). In contrast, the application of 1 mM theophylline or 50 microM 8-phenyltheophylline, a selective adenosine A1 receptor antagonist, resulted in significant augmentation of the PPI during the early phase of hyperthermia (30-34 degrees C) and a significant increase in the amplitude of the CA1 population spikes at higher temperatures (34-43 degrees C). These results suggest that increased activation of adenosine A1 receptors in response to a temperature increase depresses not only excitatory synaptic responses, but also the strength of the inhibitory circuit in CA1 neurons. Furthermore, hyperexcitability of CA1 pyramidal neurons was seen in the middle of the heating range (34-38 degrees C), excitatory responses still being present, but the strength of the inhibitory circuit significantly reduced.
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Affiliation(s)
- S Fujii
- Department of Physiology, Yamagata University School of Medicine, Yamagata, 990-9585 Japan.
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Nantwi KD, Goshgarian HG. Alkylxanthine-induced recovery of respiratory function following cervical spinal cord injury in adult rats. Exp Neurol 2001; 168:123-34. [PMID: 11170727 DOI: 10.1006/exnr.2000.7581] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Previous investigations from our laboratory have demonstrated qualitatively that a latent respiratory pathway can be activated by systemic theophylline administration to restore function to a hemidiaphragm paralyzed by an upper (C2) cervical spinal cord hemisection in adult rats. The present study seeks to extend the previous investigations by contrasting and quantitating the actions of theophylline, 8-phenyltheophylline, enprofylline, and 8(p-Sulfophenyl)theophylline in restoring function 24 h after hemidiaphragm paralysis. The alkylxanthines were selected based on their diverse pharmacologic profiles to elucidate the mechanisms that underlie functional recovery after spinal cord injury. To quantitatively assess the magnitude of recovery, electrophysiological experiments were conducted on pancuronium-paralyzed, hemisected animals under standardized recording conditions. The total absence of respiratory-related activity in the phrenic nerve ipsilateral to the hemisection and paralyzed hemidiaphragm was used as the index of a functionally complete hemisection. Thereafter, drug-induced recovered activity in the phrenic nerve ipsilateral to hemisection was quantified and expressed either as a percentage of contralateral phrenic nerve activity in the same animal prior to drug administration or as a percentage of predrug activity in the homolateral nerve in noninjured animals. With either approach, theophylline (5-15 mg/kg) and 8-phenyltheophylline (5-10 mg/kg) dose-dependently induced respiratory-related recovered activity. Enprofylline, a potent bronchodilator, and 8(p-Sulfophenyl)theophylline, an adenosine receptor antagonist with limited access to the central nervous system, were ineffective. Maximal recovery was attained with theophylline (15 mg/kg) and 8-phenyltheophylline (10 mg/kg). At these doses, theophylline and 8-phenyltheophylline induced recovery that was 70.0 +/- 2.5 and 69.3 +/- 4.1% of predrug contralateral nerve activity respectively. When expressed as a percentage of activity in the homolateral nerve in noninjured animals, the magnitude changed to 32.9 +/- 4.9 and 35.7 +/- 6.9%, respectively. Involvement of adenosine receptors in the alkylxanthine-induced actions was confirmed in experiments with the adenosine analog, N6 (l-2-phenylisopropyl) adenosine (L-PIA). It is concluded that central adenosine receptor-mediated mechanisms are implicated in the recovery of respiratory-related activity after spinal cord injury. Furthermore, our results suggest a potential for a new therapeutic approach in the rehabilitation of spinal cord patients with respiratory deficits.
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Affiliation(s)
- K D Nantwi
- Department of Anatomy and Cell Biology, Wayne State University, School of Medicine, 540 East Canfield Avenue, Detroit, Michigan 48201, USA
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30
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Montiel M, Pavía J, Marsigliante S, Jiménez E. Activation of muscarinic acetylcholine receptors induces Ca(2+) mobilization in FRT cells. Cell Signal 2001; 13:207-12. [PMID: 11282459 DOI: 10.1016/s0898-6568(01)00133-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The effect of the muscarinic receptors agonist carbachol (Cch) on intracellular calcium concentration ([Ca(2+)](i)) and cAMP level was studied in polarized Fischer rat thyroid (FRT) epithelial cells. Cch provoked a transient increase in [Ca(2+)](i), followed by a lower sustained phase. Thapsigargin, a specific microsomal Ca(2+)-ATPase inhibitor, caused a rapid rise in [Ca(2+)](i) and subsequent addition of Cch was without effect. Removal of extracellular Ca(2+) reduced the initial transient response and completely abolished the plateau phase. Ryanodine, an agent that depletes intracellular Ca(2+) stores through stimulation of ryanodine receptors (RyRs), had no effect on [Ca(2+)](i). However, the transitory activation of [Ca(2+)](i) was dose-dependently attenuated in cells pretreated with U73122, a specific inhibitor of phospholipase C (PLC). These data suggest that the Cch-stimulated increment of [Ca(2+)](i) required IP(3) formation and binding to its specific receptors in Ca(2+) stores. Further studies were performed to investigate whether the effect of Cch on Ca(2+) entry into FRT cells was via L-type voltage-dependent Ca(2+) channels (L-VDCCs). Nicardipine, a nonspecific L-type Ca(2+) channel blocker, decreased Cch-induced increase on [Ca(2+)](i), while Bay K-8644, an L-type Ca(2+) channel agonist, slightly increased [Ca(2+)](i) in FRT cells. These data indicate that Ca(2+) entry into these nondifferentiated thyroid cells occurs through an L-VDCC, and probably through another mechanism such as a capacitative pathway. Cch did not affect the intracellular cAMP levels, but its effects on [Ca(2+)](i) were significantly reduced when cells were pretreated with forskolin, suggesting the existence of an intracellular cross-talk between PLC and cAMP mechanisms in the regulation of intracellular Ca(2+) mobilization in neoplastic FRT cells.
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Affiliation(s)
- M Montiel
- Departamento de Bioquímica y Biología Molecular, Facultad de Medicina, Universidad de Málaga, Spain
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31
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Duffy SN, Craddock KJ, Abel T, Nguyen PV. Environmental enrichment modifies the PKA-dependence of hippocampal LTP and improves hippocampus-dependent memory. Learn Mem 2001; 8:26-34. [PMID: 11160761 PMCID: PMC311356 DOI: 10.1101/lm.36301] [Citation(s) in RCA: 253] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
cAMP-dependent protein kinase (PKA) is critical for the expression of some forms of long-term potentiation (LTP) in area CA1 of the mouse hippocampus and for hippocampus-dependent memory. Exposure to spatially enriched environments can modify LTP and improve behavioral memory in rodents, but the molecular bases for the enhanced memory performance seen in enriched animals are undefined. We tested the hypothesis that exposure to a spatially enriched environment may alter the PKA dependence of hippocampal LTP. Hippocampal slices from enriched mice showed enhanced LTP following a single burst of 100-Hz stimulation in the Schaffer collateral pathway of area CA1. In slices from nonenriched mice, this single-burst form of LTP was less robust and was unaffected by Rp-cAMPS, an inhibitor of PKA. In contrast, the enhanced LTP in enriched mice was attenuated by Rp-cAMPS. Enriched slices expressed greater forskolin-induced, cAMP-dependent synaptic facilitation than did slices from nonenriched mice. Enriched mice showed improved memory for contextual fear conditioning, whereas memory for cued fear conditioning was unaffected following enrichment. Our data indicate that exposure of mice to spatial enrichment alters the PKA dependence of LTP and enhances one type of hippocampus-dependent memory. Environmental enrichment can transform the pharmacological profile of hippocampal LTP, possibly by altering the threshold for activity-dependent recruitment of the cAMP-PKA signaling pathway following electrical and chemical stimulation. We suggest that experience-dependent plasticity of the PKA dependence of hippocampal LTP may be important for regulating the efficacy of hippocampus-based memory.
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Affiliation(s)
- S N Duffy
- Department of Physiology, University of Alberta School of Medicine, Edmonton, Alberta T6G 2H7, Canada
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32
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Greer F, Friars D, Graham TE. Comparison of caffeine and theophylline ingestion: exercise metabolism and endurance. J Appl Physiol (1985) 2000; 89:1837-44. [PMID: 11053334 DOI: 10.1152/jappl.2000.89.5.1837] [Citation(s) in RCA: 97] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
This two-part investigation compared the ergogenic and metabolic effects of theophylline and caffeine. Initially (part A), the ergogenic potential of theophylline on endurance exercise was investigated. Eight men cycled at 80% maximum O(2) consumption to exhaustion 90 min after ingesting either placebo (dextrose), caffeine (6 mg/kg; Caff), or theophylline (4.5 mg/kg Theolair; Theo). There was a significant increase in time to exhaustion in both the Caff (41.2+/-4.8 min) and Theo (37.4+/-5.0 min) trials compared with placebo (32.6+/-3.4 min) (P<0.05). In part B, the effects of Theo on muscle metabolism were investigated and compared with Caff. Seven men cycled for 45 min at 70% maximum O(2) consumption (identical treatment protocol as in part A). Neither methylxanthines (MX) affected muscle glycogen utilization (P>0.05). Only Caff increased plasma epinephrine (P<0.05), but both MX increased blood glycerol levels (P<0.05). Muscle cAMP was increased (P<0.05) by both MX at 15 min and remained elevated at 45 min with Theo. This demonstrates that both MX are ergogenic and that this can be independent of muscle glycogen.
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Affiliation(s)
- F Greer
- Department of Human Biology and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada N1G 2W1
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Nguyen PV, Duffy SN, Young JZ. Differential maintenance and frequency-dependent tuning of LTP at hippocampal synapses of specific strains of inbred mice. J Neurophysiol 2000; 84:2484-93. [PMID: 11067991 DOI: 10.1152/jn.2000.84.5.2484] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Transgenic and knockout mice are used extensively to elucidate the molecular mechanisms of hippocampal synaptic plasticity. However, genetic and phenotypic variations between inbred mouse strains that are used to construct genetic models may confound the interpretation of cellular neurophysiological data derived from these models. Using in vitro slice stimulation and recording methods, we compared the membrane biophysical, cellular electrophysiological, and synaptoplastic properties of hippocampal CA1 neurons in four specific strains of inbred mice: C57BL/6J, CBA/J, DBA/2J, and 129/SvEms/J. Hippocampal long-term potentiation (LTP) induced by theta-pattern stimulation, and by repeated multi-burst 100-Hz stimulation at various interburst intervals, was better maintained in area CA1 of slices from BL/6J mice than in slices from CBA and DBA mice. At an interburst interval of 20 s, maintenance of LTP was impaired in CBA and DBA slices, as compared with BL/6J slices. When the interburst interval was reduced to 3 s, induction of LTP was significantly enhanced in129/SvEms slices, but not in DBA and CBA slices. Long-term depression (LTD) was not significantly different between slices from these four strains. For the four strains examined, CA1 pyramidal neurons showed no significant differences in spike-frequency accommodation, membrane input resistance, and number of spikes elicited by current injection. Synaptically-evoked glutamatergic postsynaptic currents did not significantly differ among CA1 pyramidal neurons in these four strains. Since the observed LTP deficits resembled those previously seen in transgenic mice with reduced hippocampal cAMP-dependent protein kinase (PKA) activity, we searched for possible strain-dependent differences in cAMP-dependent synaptic facilitation induced by forskolin (an activator of adenylate cyclase) and IBMX (a phosphodiesterase inhibitor). We found that forskolin/IBMX-induced synaptic facilitation was deficient in area CA1 of DBA/2J and CBA/J slices, but not in BL/6J and 129/SvEms/J slices. These defects in cAMP-induced synaptic facilitation may underlie the deficits in memory, observed in CBA/J and DBA/2J mice, that have been previously reported. We conclude that hippocampal LTP is influenced by genetic background and by the temporal characteristics of the stimulation protocol. The plasticity of hippocampal synapses in some inbred mouse strains may be "tuned" to particular temporal patterns of synaptic activity. From a broader perspective, our data support the notion that strain-dependent variation in genetic background is an important factor that can influence the synaptoplastic phenotypes observed in studies that use genetically modified mice to explore the molecular bases of synaptic plasticity.
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Affiliation(s)
- P V Nguyen
- Department of Physiology, University of Alberta School of Medicine, Edmonton, Alberta T6G 2H7, Canada
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Yasui K, Agematsu K, Shinozaki K, Hokibara S, Nagumo H, Yamada S, Kobayashi N, Komiyama A. Effects of theophylline on human eosinophil functions: comparative study with neutrophil functions. J Leukoc Biol 2000. [DOI: 10.1189/jlb.68.2.194] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Affiliation(s)
- Kozo Yasui
- Department of Pediatrics, Shinshu University School of Medicine, Matsumoto, Japan
| | - Kazunaga Agematsu
- Department of Pediatrics, Shinshu University School of Medicine, Matsumoto, Japan
| | - Koji Shinozaki
- Department of Pediatrics, Shinshu University School of Medicine, Matsumoto, Japan
| | - Sho Hokibara
- Department of Pediatrics, Shinshu University School of Medicine, Matsumoto, Japan
| | - Haruo Nagumo
- Department of Pediatrics, Shinshu University School of Medicine, Matsumoto, Japan
| | - Shinji Yamada
- Department of Pediatrics, Shinshu University School of Medicine, Matsumoto, Japan
| | - Norimoto Kobayashi
- Department of Pediatrics, Shinshu University School of Medicine, Matsumoto, Japan
| | - Atsushi Komiyama
- Department of Pediatrics, Shinshu University School of Medicine, Matsumoto, Japan
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Abstract
(1) The methylxanthine caffeine has many pharmacological effects, most of which can be linked to blockade of adenosine receptors, inhibition of phosphodiesterases, and augmentation of calcium-dependent release of calcium from intracellular stores. (2) A variety of xanthines have been developed as potent and/or selective antagonists for adenosine receptors. (3) Several xanthines have been developed that are more potent and more selective inhibitors of cyclic nucleotide phosphodiesterase than caffeine or theophylline. (4) Caffeine remains the xanthine of choice for activation of intracellular calcium-sensitive calcium release channels although millimolar concentrations are required, which can have effects on other aspects of calcium regulation.
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Affiliation(s)
- J W Daly
- Section on Pharmacodynamics, Laboratory of Bioorganic Chemistry, National Institute of Diabetes, Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA
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36
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Sahraei H, Motamedi F, Khoshbaten A, Zarrindast MR. Adenosine A(2) receptors inhibit morphine self-administration in rats. Eur J Pharmacol 1999; 383:107-13. [PMID: 10585523 DOI: 10.1016/s0014-2999(99)00613-5] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
In the present study, the effect of adenosine receptor agonists and antagonists on morphine self-administration was investigated. Intravenous administration of morphine (0.3-3 mg/kg/injection) induced dose-dependent self-administration. The adenosine receptor antagonists, theophylline (2.5, 5, 10 mg/kg) and 3, 7-Dimethyl-1-propargylxanthine (DMPX; 0.25, 0.5, 1 mg/kg), when injected 1 h before the start of the test, reduced the number of self-administered morphine infusions. The adenosine receptor antagonists when administered in the training period (11 days) greatly increased the number of morphine infusions, however, they did not induce any response by themselves. 5'-N-ethylcarboxamido-adenosine (NECA; 0.5, 1 mg/kg) and 4-[2-[[6-Amino-9-(N-ethyl-beta-D-ribofuranuronamidosyl)-9H-purin-2 -yl ]amino] ethyl]benzenepropanoic acid (CGS21680; 0.001, 0.01, 0.025, 0. 05 mg/kg), given 1 h before the start of the test, increased morphine self-administration. Although the adenosine agonists, when injected during training period (11 days), reduced morphine self-administration. Furthermore, NECA, but not CGS21680, induced significant self-administration. The adenosine A(1) receptor agonist, N(6)-cyclohexyladenosine (CHA; 0.01, 0.1, 0.25, 0.5 and 1 mg/kg), and the adenosine A(1) receptor antagonist, 8-phenyletheophylline (2, 4, 6, 8 mg/kg), themselves neither altered morphine infusion nor induced any response. These results indicate a role for adenosine A(2) receptors in the expression and/or development of morphine self-administration.
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Affiliation(s)
- H Sahraei
- Department of Physiology and Biophysics, Baghyatollah (AS) University of Medical Sciences, Iran
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37
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Kobayashi S, Millhorn DE. Stimulation of expression for the adenosine A2A receptor gene by hypoxia in PC12 cells. A potential role in cell protection. J Biol Chem 1999; 274:20358-65. [PMID: 10400659 DOI: 10.1074/jbc.274.29.20358] [Citation(s) in RCA: 85] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The purpose of this study was to examine the regulation of adenosine A2A receptor (A2AR) gene expression during hypoxia in pheochromocytoma (PC12) cells. Northern blot analysis revealed that the A2AR mRNA level was substantially increased after a 3-h exposure to hypoxia (5% O2), which reached a peak at 12 h. Immunoblot analysis showed that the A2AR protein level was also increased during hypoxia. Inhibition of de novo protein synthesis blocked A2AR induction by hypoxia. In addition, removal of extracellular free Ca2+, chelation of intracellular free Ca2+, and pretreatment with protein kinase C inhibitors prevented A2AR induction by hypoxia. Moreover, depletion of protein kinase C activity by prolonged treatment with phorbol 12-myristate 13-acetate significantly inhibited the hypoxic induction of A2AR. A2AR antagonists led to a significant enhancement of A2AR mRNA levels during hypoxia, whereas A2AR agonists caused down-regulation of A2AR expression during hypoxia. This suggests that A2AR regulates its own expression during hypoxia by feedback mechanisms. We further found that activation of A2AR enhances cell viability during hypoxia and also inhibits vascular endothelial growth factor expression in PC12 cells. Thus, increased expression of A2AR during hypoxia might protect cells against hypoxia and may act to inhibit hypoxia-induced angiogenic activity mediated by vascular endothelial growth factor.
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Affiliation(s)
- S Kobayashi
- Department of Molecular and Cellular Physiology, University of Cincinnati, Cincinnati, Ohio 45267-576, USA
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38
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Yada T, Richmond KN, Van Bibber R, Kroll K, Feigl EO. Role of adenosine in local metabolic coronary vasodilation. THE AMERICAN JOURNAL OF PHYSIOLOGY 1999; 276:H1425-33. [PMID: 10330224 DOI: 10.1152/ajpheart.1999.276.5.h1425] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Adenosine has been postulated to mediate the increase in coronary blood flow when myocardial oxygen consumption is increased. The aim of this study was to evaluate the role of adenosine when myocardial oxygen consumption was augmented by cardiac paired-pulse stimulation without the use of catecholamines. In 10 anesthetized closed-chest dogs, coronary blood flow was measured in the left circumflex coronary artery, and myocardial oxygen consumption was calculated using the arteriovenous oxygen difference. Cardiac interstitial adenosine concentration was estimated from coronary venous and arterial plasma adenosine measurements using a previously described multicompartmental, axially distributed mathematical model. Paired stimulation increased heart rate from 55 to 120 beats/min, increased myocardial oxygen consumption 104%, and increased coronary blood flow 92%, but the estimated interstitial adenosine concentration remained below the threshold for coronary vasodilation. After adenosine-receptor blockade with 8-phenyltheophylline (8-PT), coronary blood flow and myocardial oxygen consumption were not significantly different from control values. Paired-pulse pacing during adenosine-receptor blockade resulted in increases in myocardial oxygen consumption and coronary blood flow similar to the response before 8-PT. Coronary venous and estimated interstitial adenosine concentration did not increase to overcome the adenosine blockade by 8-PT. These results demonstrate that adenosine is not required for the local metabolic control of coronary blood flow during pacing-induced increases in myocardial oxygen consumption.
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Affiliation(s)
- T Yada
- Department of Physiology and Biophysics and Center for Bioengineering, University of Washington, Seattle, Washington 98195-7290, USA
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39
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Lu KT, Gean PW. Masking of forskolin-induced long-term potentiation by adenosine accumulation in area CA1 of the rat hippocampus. Neuroscience 1999; 88:69-78. [PMID: 10051190 DOI: 10.1016/s0306-4522(98)00200-0] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
At hippocampal Schaffer collateral-CA1 synapses, activation of beta-adrenergic receptors and adenylyl cyclase increases transmitter release. However, this effect is transient, which is in contrast to that seen at mossy fiber-CA3 synapses, where activation of cyclic-AMP-dependent protein kinase results in long-lasting facilitation of transmitter release, a phenomenon known as a presynaptic form of long-term potentiation. The present study was aimed at investigating whether forskolin, an adenylyl cyclase activator, could produce long-term effects at the Schaffer collateral-CA1 synapses using extracellular recording techniques. As has been reported previously, forskolin persistently increased the amplitude of evoked population spikes without having a long-term effect on the field excitatory postsynaptic potentials. However, under the conditions where adenosine A1 receptors are inhibited, cyclic-AMP metabolism is disrupted or the transport of cyclic-AMP is blocked, forskolin induces long-term potentiation. Forskolin-induced potentiation is associated with a decrease in paired-pulse facilitation and is blocked by the cyclic-AMP-dependent protein kinase inhibitor Rp-adenosine-3',5'-cyclic monophosphorothioate. Activation of N-methyl-D-aspartate receptors is not required for forskolin-induced long-term potentiation, because pretreatment of slices with the N-methyl-D-aspartate receptor antagonist D-2-amino-5-phosphonovalerate did not prevent forskolin-induced potentiation. These results suggest that blockade of adenosine A1 receptors unmasks forskolin-induced long-term potentiation, and activation of cyclic-AMP-dependent protein kinase induces a form of long-term potentiation which is different from that induced by tetanic stimulation.
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Affiliation(s)
- K T Lu
- Department of Pharmacology, College of Medicine, National Cheng-Kung University, Tainan City, Taiwan
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40
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Gillman TA, Pennefather JN. Evidence for the presence of both P1 and P2 purinoceptors in the rat myometrium. Clin Exp Pharmacol Physiol 1998; 25:592-9. [PMID: 9673434 DOI: 10.1111/j.1440-1681.1998.tb02257.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
1. Adenosine, adenosine triphosphate (ATP) and some stable analogues of adenosine inhibited field stimulation-induced contractions of the uterus from rats treated with oestradiol cypionate (20 micrograms/kg, s.c.) 1 day previously. Adenosine was twice as potent as ATP; both were potentiated by dipyridamole (10 mumol/L). 2. The order of agonist potency of adenosine and its analogues was: 5'-N-ethylcarboxamidoadenosine (NECA) > N6-cyclohexyladenosine > or = R-phenylisopropyladenosine = S-phenylisopropyladenosine = 2-chloroadenosine > or = adenosine > or = ATP > > 2-p-(2-carboxyethyl) phenethylamino-5'-N-ethylcarboxamidoadenosine. This order suggests the presence of P1 purinoceptors of the A2B subtype. 3. Responses to agonists were antagonized to differing extents by the P1 purinoceptor antagonist 8-phenyltheophylline (10 mumol/L). 4. In uterine preparations from rats pretreated for 2 days with oestrogen (20 micrograms/kg, s.c.) and for 1 day with progesterone (3 mg/animal, s.c.), the inhibitory potencies of adenosine and NECA were reduced, indicating hormonal regulation of uterine responsiveness to P1 purinoceptor agonists. 5. Stable analogues of ATP caused contractions of unstimulated myometrial preparations from oestrogen-treated animals, indicating activation of a P2 purinoceptor, possibly of the P2X subtype, because of the relative order of potency was alpha, beta-methylene ATP > beta, gamma-methylene ATP = ATP = 2-methylthio ATP.
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Affiliation(s)
- T A Gillman
- Department of Pharmacology, Monash University, Clayton, Victoria, Australia
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41
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Kuriyama H, Kitamura K, Itoh T, Inoue R. Physiological features of visceral smooth muscle cells, with special reference to receptors and ion channels. Physiol Rev 1998; 78:811-920. [PMID: 9674696 DOI: 10.1152/physrev.1998.78.3.811] [Citation(s) in RCA: 176] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Visceral smooth muscle cells (VSMC) play an essential role, through changes in their contraction-relaxation cycle, in the maintenance of homeostasis in biological systems. The features of these cells differ markedly by tissue and by species; moreover, there are often regional differences within a given tissue. The biophysical features used to investigate ion channels in VSMC have progressed from the original extracellular recording methods (large electrode, single or double sucrose gap methods), to the intracellular (microelectrode) recording method, and then to methods for recording from membrane fractions (patch-clamp, including cell-attached patch-clamp, methods). Remarkable advances are now being made thanks to the application of these more modern biophysical procedures and to the development of techniques in molecular biology. Even so, we still have much to learn about the physiological features of these channels and about their contribution to the activity of both cell and tissue. In this review, we take a detailed look at ion channels in VSMC and at receptor-operated ion channels in particular; we look at their interaction with the contraction-relaxation cycle in individual VSMC and especially at the way in which their activity is related to Ca2+ movements and Ca2+ homeostasis in the cell. In sections II and III, we discuss research findings mainly derived from the use of the microelectrode, although we also introduce work done using the patch-clamp procedure. These sections cover work on the electrical activity of VSMC membranes (sect. II) and on neuromuscular transmission (sect. III). In sections IV and V, we discuss work done, using the patch-clamp procedure, on individual ion channels (Na+, Ca2+, K+, and Cl-; sect. IV) and on various types of receptor-operated ion channels (with or without coupled GTP-binding proteins and voltage dependent and independent; sect. V). In sect. VI, we look at work done on the role of Ca2+ in VSMC using the patch-clamp procedure, biochemical procedures, measurements of Ca2+ transients, and Ca2+ sensitivity of contractile proteins of VSMC. We discuss the way in which Ca2+ mobilization occurs after membrane activation (Ca2+ influx and efflux through the surface membrane, Ca2+ release from and uptake into the sarcoplasmic reticulum, and dynamic changes in Ca2+ within the cytosol). In this article, we make only limited reference to vascular smooth muscle research, since we reviewed the features of ion channels in vascular tissues only recently.
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Affiliation(s)
- H Kuriyama
- Seinan Jogakuin University, Kokura-Kita, Fukuoka, Japan
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42
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Coney AM, Marshall JM. Role of adenosine and its receptors in the vasodilatation induced in the cerebral cortex of the rat by systemic hypoxia. J Physiol 1998; 509 ( Pt 2):507-18. [PMID: 9575299 PMCID: PMC2230973 DOI: 10.1111/j.1469-7793.1998.507bn.x] [Citation(s) in RCA: 71] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/1997] [Accepted: 02/16/1998] [Indexed: 11/26/2022] Open
Abstract
1. In anaesthetized rats, we have examined the role of adenosine in vasodilatation evoked in the cerebral cortex by systemic hypoxia (breathing 8 % O2). Red cell flux was recorded from the surface of the exposed parietal cortex (CoRCF) by a laser Doppler probe, cortical vascular conductance (CoVC) being computed as CoRCF divided by mean arterial blood pressure. All agonists and antagonists were applied topically to the cortex. 2. Systemic hypoxia or adenosine application for 5 or 10 min, respectively, induced an increase in CoRCF and CoVC. These responses were substantially reduced by 8-phenyltheophylline (8-PT), an adenosine receptor antagonist which is non-selective between the adenosine A1 and A2A receptor subtypes. By contrast, the adenosine receptor antagonist 8-sulphophenyltheophylline (8-SPT) which is similarly non-selective, but unlike 8-PT, does not cross the blood-brain barrier, reduced the increases in CoRCF and CoVC induced by adenosine, but had no effect on those induced by hypoxia. 3. The A2A receptor agonist CGS21680 produced a substantial increase in CoRCF and CoVC, but the A1 receptor agonist 2-chloro-N6-cyclopentyladenosine had minimal effects. 4. The A2A receptor antagonist ZM241385 reduced the increase in CoRCF and CoVC induced by adenosine and reduced the increase in CoRCF induced by hypoxia. 5. We propose that exogenous adenosine that is topically applied to the cerebral cortex produces vasodilatation by acting on A2A receptors on the vascular smooth muscle. However, during systemic hypoxia, we propose that adenosine is released from endothelial cells and acts on endothelial A2A receptors to produce the major part of the hypoxia-induced dilatation in the cerebral cortex.
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Affiliation(s)
- A M Coney
- Department of Physiology, The Medical School, Birmingham B15 2TT, UK
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43
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Fenu S, Morelli M. Motor stimulant effects of caffeine in 6-hydroxydopamine-lesioned rats are dependent on previous stimulation of dopamine receptors: a different role of D1 and D2 receptors. Eur J Neurosci 1998; 10:1878-84. [PMID: 9751157 DOI: 10.1046/j.1460-9568.1998.00198.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Caffeine has been reported to induce contralateral rotational behaviour in rats bearing a unilateral 6-hydroxydopamine lesion of the dopaminergic nigrostriatal pathway. In order to define the role of dopamine receptors in the mediation of this behaviour, we have evaluated the influence of previous exposure to a dopamine receptor agonist and the importance of the time elapsed from the 6-hydroxydopamine lesion on the rotational behaviour induced by caffeine. Separate groups of rats lesioned with 6-hydroxydopamine 2 weeks previously were exposed to four administrations of the D1/D2 receptor agonist apomorphine (0.3 mg/kg s.c.) (primed) or vehicle (drug-naive). Three days later, all rats received caffeine (30 mg/kg s.c.). Drug-naive 6-hydroxydopamine-lesioned rats did not rotate in response to caffeine, while rats primed with apomorphine rotate contralaterally in response to caffeine. When apomorphine priming was paired to the same environment (hemispherical bowls) where rats received caffeine, rotational behaviour was significantly higher than that obtained in rats primed in an unpaired environment (cylinders). Repeated priming with the D2/D3 receptor agonist quinpirole (0.2 mg/kg s.c.) induced a totally context-dependent contralateral rotation in response to caffeine, while caffeine contralateral rotation was not dependent from the context after repeated priming with the D1 agonist SKF 38393 [1-phenyl-2,3,4,5-tetrahydro-(1 H)-3-benzazepine-7,8-diol hydrochloride, 3 mg/kg s.c.]. Caffeine-mediated contralateral rotation was also evaluated in rats lesioned with 6-hydroxydopamine 12 weeks previously and exposed to four administrations of apomorphine or vehicle. As for rats repeatedly exposed to vehicle or apomorphine 2 weeks after 6-hydroxydopamine lesioning, caffeine failed to induce contralateral rotation in drug-naive rats, while it did induce a partially context-dependent contralateral rotation in apomorphine-primed rats. Different from rats receiving apomorphine priming 2 weeks after 6-hydroxydopamine lesioning, in 12 week-lesioned rats, caffeine also induced contralateral rotation after one priming with apomorphine (0.3 mg/kg s.c.), a condition which fails to induce context-dependent rotation. Administration of selective antagonists of A1 (8-cyclopentyl-1,3-dipropylxanthine), (DPCPX) or A2A (5-amino-2-(2-furyl)-7-(3-phenylpropyl)-pyrazolo[4,3-e]-1 ,2,4-triazolo[5c]pirimidine), (SCH 58261) adenosine receptors failed to induce contralateral rotation either alone or in combination in 12 week-6-hydroxydopamine-lesioned rats repeatedly primed with apomorphine. All together, the results indicate that: (i) caffeine does not induce any contralateral rotation in drug-naive 6-hydroxydopamine-lesioned rats; (ii) priming with a dopamine agonist enables caffeine to induce contralateral rotation, this rotation is, however, context independent only after priming with a selective D1 agonist; (iii) contralateral rotation in response to caffeine is dependent on the time from the 6-hydroxydopamine lesion; (iv) blockade of A1 and A2A adenosine receptors with selective antagonists does not induce contralateral rotational behaviour in 6-hydroxydopamine-lesioned rats.
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Affiliation(s)
- S Fenu
- Department of Toxicology, University of Cagliari, Italy
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Kobayashi S, Conforti L, Pun RY, Millhorn DE. Adenosine modulates hypoxia-induced responses in rat PC12 cells via the A2A receptor. J Physiol 1998; 508 ( Pt 1):95-107. [PMID: 9490823 PMCID: PMC2230860 DOI: 10.1111/j.1469-7793.1998.095br.x] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
1. The present study was undertaken to determine the role of adenosine in mediating the cellular responses to hypoxia in rat phaeochromocytoma (PC12) cells, an oxygen-sensitive clonal cell line. 2. Reverse transcriptase polymerase chain reaction studies revealed that PC12 cells express adenosine deaminase (the first catalysing enzyme of adenosine degradation) and the A2A and A2B adenosine receptors, but not the A1 or A3 adenosine receptors. 3. Whole-cell current- and voltage-clamp experiments showed that adenosine attenuated the hypoxia-induced membrane depolarization. The hypoxia-induced suppression of the voltage-sensitive potassium current (IK(V)) was markedly reduced by adenosine. Furthermore, extracellularly applied adenosine increased the peak amplitudes of IK(V) in a concentration-dependent manner. This increase was blocked by pretreatment not only with a non-specific adenosine receptor antagonist, 8-phenyltheophylline (8-PT), but also with a selective A2A receptor antagonist, ZM241385. 4. Ca2+ imaging studies using fura-2 acetoxymethyl ester (fura-2 AM) revealed that the increase in intracellular free Ca2+ during hypoxic exposure was attenuated significantly by adenosine. Voltage-clamp studies showed that adenosine inhibited the voltage-dependent Ca2+ currents (ICa) in a concentration-dependent fashion. This inhibition was also abolished by both 8-PT and ZM241385. 5. The modulation of both IK(V) and ICa by adenosine was prevented by intracellular application of an inhibitor of protein kinase A (PKA), PKA inhibitor fragment (6-22) amide. In addition, the effect of adenosine on either IK(V) or ICa was absent in PKA-deficient PC12 cells. 6. These results indicate that the modulatory effects of adenosine on the hypoxia-induced membrane responses of PC12 cells are likely to be mediated via activation of the A2A receptor, and that the PKA pathway is required for these modulatory actions. We propose that this modulation serves to regulate membrane excitability in PC12 cells and possibly other oxygen-sensitive cells during hypoxia.
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Affiliation(s)
- S Kobayashi
- Department of Molecular and Cellular Physiology, University of Cincinnati, 231 Bethesda Avenue, PO Box 576, Cincinnati, OH 45267-576, USA.
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Brown CJ, Caswell AM, Rahman S, Russell RG, Buttle DJ. Proteoglycan breakdown from bovine nasal cartilage is increased, and from articular cartilage is decreased, by extracellular ATP. BIOCHIMICA ET BIOPHYSICA ACTA 1997; 1362:208-20. [PMID: 9540852 DOI: 10.1016/s0925-4439(97)00080-x] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The addition of ATP, but not ADP or AMP, to the culture media of bovine nasal cartilage explants caused an acceleration in the rate of proteoglycan loss from the tissue. The ATP-stimulated loss of proteoglycan was not inhibited by the IL1-receptor antagonist protein, but was partially inhibited by the presence of ADP or AMP. The proteolytic events resulting from the presence of ATP were found to be similar to those following treatment with IL1, in that inhibitors of the cysteine-peptidase cathepsin B, serine-proteinases with trypsin-like specificity, and of some of the matrixins, could all prevent proteoglycan loss, which was mediated, at least in part, by the action of 'aggrecanase'. In contrast to its effects on nasal cartilage, ATP inhibited basal and stimulated proteoglycan release from articular cartilage. Both ADP and AMP had no effect on proteoglycan release in articular cartilage but enhanced the response to ATP when added concurrently. We conclude that extracellular ATP, probably acting via P2-purinoceptors, stimulates proteoglycan breakdown from bovine nasal cartilage and thus, may have a role in diseases which primarily involve destruction of non-articular cartilage. Extracellular ATP has, in contrast, a chondroprotective effect on bovine articular cartilage.
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Affiliation(s)
- C J Brown
- Department of Human Metabolism and Clinical Biochemistry, University of Sheffield Medical School, UK
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Zarrindast MR, Iraie F, Heidari MR, Mohagheghi-Badi M. Effect of adenosine receptor agonists and antagonists on morphine-induced catalepsy in mice. Eur J Pharmacol 1997; 338:11-6. [PMID: 9407998 DOI: 10.1016/s0014-2999(97)01221-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Effects of adenosine receptor agonists and antagonists on morphine-induced catalepsy in mice were investigated. The adenosine agonists, NECA (5'-N-ethylcarboxamidoadenosine) and S-PIA (S(+)-N6-(2-phenylisopropyl)adenosine) in doses which did not induce any response, increased the cataleptogenic effect produced by morphine. However, the morphine response was decreased and increased by the lower and higher doses of the adenosine receptor agonist, CHA (N6-cyclohexyladenosine), respectively. The adenosine receptor antagonist, theophylline, decreased, but 8-phenyltheophylline increased, the response induced by morphine. Naloxone inhibited the catalepsy induced by morphine or morphine + NECA but not that induced by NECA alone. It is concluded that adenosine A2 receptor activation increases, while adenosine A1 receptor stimulation decreases, the morphine cataleptogenic response. The response to morphine may be mediated through opioid and adenosine receptor mechanisms.
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Affiliation(s)
- M R Zarrindast
- Department of Pharmacology, School of Medicine, Tehran University of Medical Sciences, Iran
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Apland JP, Helekar SA, Lebeda FJ. Suppression of drug-induced epileptiform discharges by cyclic AMP in rat hippocampus. MOLECULAR AND CHEMICAL NEUROPATHOLOGY 1997; 31:265-78. [PMID: 9336768 DOI: 10.1007/bf02815129] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The effect of cyclic adenosine 3',5'-monophosphate (cAMP) on epileptiform activity in rat hippocampal slices was investigated. Bath-applied cAMP reversibly decreased the frequency of extracellularly recorded discharges in the CA3 subfield induced by bethanechol- or theophylline-containing solutions. Because cAMP was presumed to be relatively membrane impermeant, we developed and tested the hypothesis that this cAMP-mediated effect occurred extracellularly through the catabolic conversion of cAMP to 5'-AMP and, in turn, to adenosine, a known inhibitory neuromodulator. Three predictions derived from this catabolic hypothesis were tested. First, blockers of the enzymes involved were predicted to antagonize this effect of cAMP. In contrast, the coapplication of a cAMP-phosphodiesterase inhibitor, 3-isobutyl-1-methylxanthine (IBMX), or a 5'-nucleotidase inhibitor, adenosine 5'-[alpha, beta-methylene] diphosphate (AMP-CP), enhanced the cAMP-induced suppressive effect. Second, the nonhydrolyzable cAMP analogs, dibutyryl- and 8-bromo-cAMP, were predicted to be ineffective. Low concentrations (5-40 microM) of these two derivatives, however, also suppressed bethanechol-induced discharges, while, at a higher concentration (100 microM), both analogs increased discharge frequencies. Third, enzymatic catabolism of adenosine was predicted to antagonize cAMP's effect, but coapplying adenosine deaminase (10 U/mL) did not diminish this action. Because these data did not support the catabolic hypothesis, other, as yet undefined, mechanisms must be responsible for the discharge-suppressant effect of cAMP.
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Affiliation(s)
- J P Apland
- Neurotoxicology Branch, US Army Medical Research Institute of Chemical Defense, Aberdeen Proving Ground, MD 21010-5425, USA.
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Zarrindast MR, Moghadamnia AA. Adenosine receptor agents and conditioned place preference. GENERAL PHARMACOLOGY 1997; 29:285-9. [PMID: 9251915 DOI: 10.1016/s0306-3623(96)00236-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
1. The effects of different doses of the adenosine agonists N5-ethylcarboxamido-adenosine (NECA), R-isomer of N6-phenylisopropyladenosine (R-PIA), and N6-cyclohexyladenosine (CHA) or of the antagonists theophylline and 8-phenyltheophylline (8-PT) on conditioned place preference (CPP) have been studied. 2. The results show that R-PIA and CHA induced conditioned place aversion (CPA) whereas NECA induced conditioned place preference (CPP). 3. Low doses of theophylline elicit CPP, but high doses of the drug induced CPA. 8-PT also produced the CPP. 4. The responses of R-PIA and CHA but not NECA was decreased by theophylline and 8-PT administration. 5. It is concluded that the induction of CPP an CPA by adenosine antagonsists may be mediated by different adenosine receptors.
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Affiliation(s)
- M R Zarrindast
- Department of Pharmacology, School of Medicine, Tehran University of Medical Sciences, Iran
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Izzo AA, Mascolo N, Costa M, Capasso F. Effect of papaverine on synaptic transmission in the guinea-pig ileum. Br J Pharmacol 1997; 121:768-72. [PMID: 9208146 PMCID: PMC1564724 DOI: 10.1038/sj.bjp.0701142] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
1. The effect of papaverine, a well known smooth muscle relaxant, was investigated on neural transmission within the enteric nervous system. Segments of guinea-pig ileum were placed in a partitioned bath to enable drugs, including papaverine, to be applied to enteric nerve pathways without interfering with the recording of the smooth muscle contraction. Ascending excitatory enteric nerve pathways were activated by electrical field stimulation in the anal compartment (10 Hz for 2 s, 45 mA, 0.5 ms pulse duration) and the resulting contraction of the intestinal circular muscle in the oral compartment was recorded isotonically. 2. Tetrodotoxin (0.6 microM) and hexamethonium (100 microM) both abolished, or greatly reduced, the contractions when applied to either compartment indicating that nicotinic synapses are involved in this pathway. 3. Papaverine (0.3-30 microM) applied independently to each compartment depressed in a concentration-dependent manner, the nerve-mediated contractions. The IC50 of this inhibitory effect was 3.53 microM for the oral and 4.76 microM for the anal compartments, respectively. Two other phosphodiesterase (PDE) inhibitors, 3-isobutyl-1-methylxanthine (IBMX 10-300 microM) and theophylline (30-1000 microM) added to the anal compartment also inhibited the nerve mediated contractions. Papaverine applied to the anal bath, after IBMX 100 microM (or theophylline 300 microM) further inhibited the nerve-mediated contractions, but was less effective than when applied alone. 4. Phentolamine (1 microM), an alpha-adrenoceptor antagonist, reduced the inhibitory effect of papaverine, but not that of IBMX (100 microM) or theophylline (300 microM). A combination of phentolamine and IBMX (or theophylline) prevented the inhibitory effect of papaverine. 5. Tetrodotoxin, but not papaverine or hexamethonium, inhibited the contraction elicited by electrical stimulation just anal to the partition indicating that papaverine did not affect the generation or conduction of nerve action potentials. 6. Verapamil (1 microM) and nifedipine (1 microM), two smooth muscle relaxants which act by blocking L-type calcium channels, only inhibited the contractions when applied directly to the recording (oral) compartment. This indicates that L-type Ca2+ channels are probably not involved in synaptic transmission in these ascending pathways and thus that the PDE inhibitors do not inhibit synaptic transmission by acting on these channels. omega-Conotoxin GVIA (10 nM), a potent inhibitor of the N-type Ca2+ channels, blocked the nerve-mediated contractions applied to either compartment. Whether the PDE inhibitors exert their inhibitory actions via these channels remains to be established. 7. The results indicate that the PDE inhibitors, papaverine, IBMX and theophylline inhibit excitatory enteric neural pathways by depressing synaptic transmission. The inhibitory effect of papaverine (but not IMBX or theophylline) involves, at least in part, the release of noradrenaline from sympathetic nerves acting on alpha-adrenoceptors on enteric neurones.
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Affiliation(s)
- A A Izzo
- Department of Experimental Pharmacology, University of Naples, Federico II, Italy
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Senok SS, Baumann KI. Functional evidence for calcium-induced calcium release in isolated rat vibrissal Merkel cell mechanoreceptors. J Physiol 1997; 500 ( Pt 1):29-37. [PMID: 9097930 PMCID: PMC1159356 DOI: 10.1113/jphysiol.1997.sp021996] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
1. Single unit recordings were made from Merkel cell (sinus hair type I; St I) and sinus hair type II (St II) mechanoreceptors in isolated rat vibrissae. Responses were determined as the number of spikes evoked by controlled mechanical displacement of the hair shaft for 5 s every 30 s. 2. Superfusion of caffeine (10 mM) increased the responses of Merkel cell receptors by 50-180% of control (mean +/- S.E.M., 64 +/- 12.6%, n = 6, P < 0.001). Similar concentrations of caffeine inhibited St II receptor responses by 20-60% (mean +/- S.E.M., 35 +/- 8%, n = 5, P < 0.01). In both receptor types, caffeine induced a low-frequency increase in spontaneous firing. 3. When Merkel cell receptor responses were completely blocked by superfusion of high Mg2+-containing solution (to competitively block Ca2+ influx) caffeine had no effect when added after complete inhibition, but when added during partial inhibition of responses, the Mg2+-induced inhibition was transiently reversed or halted. This suggests that Ca2+ influx was a prerequisite for the action of caffeine. 4. Ryanodine (1 microM) increased the responses of Merkel cell receptors to mechanical stimulation by 7-60% (mean +/- S.E.M., 32 +/- 10.9 %, n = 5, P < 0.05) but had no effect on St II receptor responses. 5. The Ca2+-induced Ca2+ release (CICR) inhibitor procaine inhibited St I receptor responses in a concentration-dependent manner. Near-maximal inhibition was attained with 100 microM procaine. In four St I units, mean responses were depressed to 25% of control values. When both procaine (100 microM) and caffeine (10 mM) were introduced together, no net effect was seen. The responses of St II receptors were little affected by up to 100 microM procaine superfusion. 6. It is concluded that the mechano-electrical transduction process in St I receptors (but not St II) includes a CICR pathway. Taken with previous findings on the role of Merkel cells, it is likely that CICR is occurring in the Merkel cells.
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Affiliation(s)
- S S Senok
- Department of Physiology, Faculty of Medicine, The Chinese University of Hong Kong, Shatin.
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