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Ding C, Yang D, Feldmeyer D. Adenosinergic Modulation of Layer 6 Microcircuitry in the Medial Prefrontal Cortex Is Specific to Presynaptic Cell Type. J Neurosci 2024; 44:e1606232023. [PMID: 38429106 PMCID: PMC11007316 DOI: 10.1523/jneurosci.1606-23.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2023] [Revised: 12/12/2023] [Accepted: 12/13/2023] [Indexed: 03/03/2024] Open
Abstract
Adenosinergic modulation in the PFC is recognized for its involvement in various behavioral aspects including sleep homoeostasis, decision-making, spatial working memory and anxiety. While the principal cells of layer 6 (L6) exhibit a significant morphological diversity, the detailed cell-specific regulatory mechanisms of adenosine in L6 remain unexplored. Here, we quantitatively analyzed the morphological and electrophysiological parameters of L6 neurons in the rat medial prefrontal cortex (mPFC) using whole-cell recordings combined with morphological reconstructions. We were able to identify two different morphological categories of excitatory neurons in the mPFC of both juvenile and young adult rats with both sexes. These categories were characterized by a leading dendrite that was oriented either upright (toward the pial surface) or inverted (toward the white matter). These two excitatory neuron subtypes exhibited different electrophysiological and synaptic properties. Adenosine at a concentration of 30 µM indiscriminately suppressed connections with either an upright or an inverted presynaptic excitatory neuron. However, using lower concentrations of adenosine (10 µM) revealed that synapses originating from L6 upright neurons have a higher sensitivity to adenosine-induced inhibition of synaptic release. Adenosine receptor activation causes a reduction in the probability of presynaptic neurotransmitter release that could be abolished by specifically blocking A1 adenosine receptors (A1ARs) using 8-cyclopentyltheophylline (CPT). Our results demonstrate a differential expression level of A1ARs at presynaptic sites of two functionally and morphologically distinct subpopulations of L6 principal neurons, suggesting the intricate functional role of adenosine in neuronal signaling in the brain.
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Affiliation(s)
- Chao Ding
- Research Center Juelich, Institute of Neuroscience and Medicine 10, Research Center Juelich, Juelich 52425, Germany
| | - Danqing Yang
- Research Center Juelich, Institute of Neuroscience and Medicine 10, Research Center Juelich, Juelich 52425, Germany
- Department of Psychiatry, Psychotherapy, and Psychosomatics, RWTH Aachen University Hospital, Aachen 52074, Germany
| | - Dirk Feldmeyer
- Research Center Juelich, Institute of Neuroscience and Medicine 10, Research Center Juelich, Juelich 52425, Germany
- Department of Psychiatry, Psychotherapy, and Psychosomatics, RWTH Aachen University Hospital, Aachen 52074, Germany
- Jülich-Aachen Research Alliance, Translational Brain Medicine (JARA Brain), Aachen 52074, Germany
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2
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Bhattacharya D, Górska-Andrzejak J, Abaquita TAL, Pyza E. Effects of adenosine receptor overexpression and silencing in neurons and glial cells on lifespan, fitness, and sleep of Drosophila melanogaster. Exp Brain Res 2023:10.1007/s00221-023-06649-y. [PMID: 37335362 DOI: 10.1007/s00221-023-06649-y] [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: 10/03/2022] [Accepted: 05/28/2023] [Indexed: 06/21/2023]
Abstract
A single adenosine receptor gene (dAdoR) has been detected in Drosophila melanogaster. However, its function in different cell types of the nervous system is mostly unknown. Therefore, we overexpressed or silenced the dAdoR gene in eye photoreceptors, all neurons, or glial cells and examined the fitness of flies, the amount and daily pattern of sleep, and the influence of dAdoR silencing on Bruchpilot (BRP) presynaptic protein. Furthermore, we examined the dAdoR and brp gene expression in young and old flies. We found that a higher level of dAdoR in the retina photoreceptors, all neurons, and glial cells negatively influenced the survival rate and lifespan of male and female Drosophila in a cell-dependent manner and to a different extent depending on the age of the flies. In old flies, expression of both dAdoR and brp was higher than in young ones. An excess of dAdoR in neurons improved climbing in older individuals. It also influenced sleep by lengthening nighttime sleep and siesta. In turn, silencing of dAdoR decreased the lifespan of flies, although it increased the survival rate of young flies. It hindered the climbing of older males and females, but did not change sleep. Silencing also affected the daily pattern of BRP abundance, especially when dAdoR expression was decreased in glial cells. The obtained results indicate the role of adenosine and dAdoR in the regulation of fitness in flies that is based on communication between neurons and glial cells, and the effect of glial cells on synapses.
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Affiliation(s)
| | | | | | - Elżbieta Pyza
- Department of Cell Biology and Imaging, Jagellonian University, Kraków, Poland.
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3
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Yang D, Ding C, Qi G, Feldmeyer D. Cholinergic and Adenosinergic Modulation of Synaptic Release. Neuroscience 2020; 456:114-130. [PMID: 32540364 DOI: 10.1016/j.neuroscience.2020.06.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2020] [Revised: 05/29/2020] [Accepted: 06/01/2020] [Indexed: 01/14/2023]
Abstract
In this review we will discuss the effect of two neuromodulatory transmitters, acetylcholine (ACh) and adenosine, on the synaptic release probability and short-term synaptic plasticity. ACh and adenosine differ fundamentally in the way they are released into the extracellular space. ACh is released mostly from synaptic terminals and axonal bouton of cholinergic neurons in the basal forebrain (BF). Its mode of action on synaptic release probability is complex because it activate both ligand-gated ion channels, so-called nicotinic ACh receptors and G-protein coupled muscarinic ACh receptors. In contrast, adenosine is released from both neurons and glia via nucleoside transporters or diffusion over the cell membrane in a non-vesicular, non-synaptic fashion; its receptors are exclusively G-protein coupled receptors. We show that ACh and adenosine effects are highly specific for an identified synaptic connection and depend mostly on the presynaptic but also on the postsynaptic receptor type and discuss the functional implications of these differences.
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Affiliation(s)
- Danqing Yang
- Research Centre Juelich, Institute of Neuroscience and Medicine 10, Leo-Brandt-Strasse, Juelich, Germany
| | - Chao Ding
- Research Centre Juelich, Institute of Neuroscience and Medicine 10, Leo-Brandt-Strasse, Juelich, Germany
| | - Guanxiao Qi
- Research Centre Juelich, Institute of Neuroscience and Medicine 10, Leo-Brandt-Strasse, Juelich, Germany
| | - Dirk Feldmeyer
- Research Centre Juelich, Institute of Neuroscience and Medicine 10, Leo-Brandt-Strasse, Juelich, Germany; RWTH Aachen University Hospital, Pauwelsstrasse 30, Aachen, Germany; Jülich-Aachen Research Alliance Brain - JARA Brain, Germany.
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4
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Garofalo S, Picard K, Limatola C, Nadjar A, Pascual O, Tremblay MÈ. Role of Glia in the Regulation of Sleep in Health and Disease. Compr Physiol 2020; 10:687-712. [PMID: 32163207 DOI: 10.1002/cphy.c190022] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Sleep is a naturally occurring physiological state that is required to sustain physical and mental health. Traditionally viewed as strictly regulated by top-down control mechanisms, sleep is now known to also originate locally. Glial cells are emerging as important contributors to the regulation of sleep-wake cycles, locally and among dedicated neural circuits. A few pioneering studies revealed that astrocytes and microglia may influence sleep pressure, duration as well as intensity, but the precise involvement of these two glial cells in the regulation of sleep remains to be fully addressed, across contexts of health and disease. In this overview article, we will first summarize the literature pertaining to the role of astrocytes and microglia in the regulation of sleep under normal physiological conditions. Afterward, we will discuss the beneficial and deleterious consequences of glia-mediated neuroinflammation, whether it is acute, or chronic and associated with brain diseases, on the regulation of sleep. Sleep disturbances are a main comorbidity in neurodegenerative diseases, and in several brain diseases that include pain, epilepsy, and cancer. Identifying the relationships between glia-mediated neuroinflammation, sleep-wake rhythm disruption and brain diseases may have important implications for the treatment of several disorders. © 2020 American Physiological Society. Compr Physiol 10:687-712, 2020.
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Affiliation(s)
- Stefano Garofalo
- Department of Physiology and Pharmacology, Sapienza University, Laboratory affiliated to Istituto Pasteur Italia - Fondazione Cenci Bolognetti, Rome, Italy
| | - Katherine Picard
- Nutrition et Neurobiologie Intégrée, UMR 1286, Institut National de la Recherche Agronomique, Bordeaux University, Bordeaux, France.,Axe Neurosciences, Centre de recherche du CHU de Québec-Université Laval, Québec, Quebec, Canada
| | - Cristina Limatola
- Department of Physiology and Pharmacology, Sapienza University, Laboratory affiliated to Istituto Pasteur Italia - Fondazione Cenci Bolognetti, Rome, Italy.,IRCCS Neuromed, Pozzilli, Italy
| | - Agnès Nadjar
- Nutrition et Neurobiologie Intégrée, UMR 1286, Institut National de la Recherche Agronomique, Bordeaux University, Bordeaux, France
| | - Olivier Pascual
- INSERM U1028, CNRS UMR5292, Lyon Neuroscience Research Center, Université Claude Bernard Lyon, Lyon, France
| | - Marie-Ève Tremblay
- Axe Neurosciences, Centre de recherche du CHU de Québec-Université Laval, Québec, Quebec, Canada.,Départment de médecine moleculaire, Faculté de médecine, Université Laval, Québec, Quebec, Canada
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5
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Czeisler CM, Silva TM, Fair SR, Liu J, Tupal S, Kaya B, Cowgill A, Mahajan S, Silva PE, Wang Y, Blissett AR, Göksel M, Borniger JC, Zhang N, Fernandes‐Junior SA, Catacutan F, Alves MJ, Nelson RJ, Sundaresean V, Rekling J, Takakura AC, Moreira TS, Otero JJ. The role of PHOX2B-derived astrocytes in chemosensory control of breathing and sleep homeostasis. J Physiol 2019; 597:2225-2251. [PMID: 30707772 PMCID: PMC6462490 DOI: 10.1113/jp277082] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2018] [Accepted: 01/28/2019] [Indexed: 01/07/2023] Open
Abstract
KEY POINTS The embryonic PHOX2B-progenitor domain generates neuronal and glial cells which together are involved in chemosensory control of breathing and sleep homeostasis. Ablating PHOX2B-derived astrocytes significantly contributes to secondary hypoxic respiratory depression as well as abnormalities in sleep homeostasis. PHOX2B-derived astrocyte ablation results in axonal pathologies in the retrotrapezoid nucleus. ABSTRACT We identify in mice a population of ∼800 retrotrapezoid nucleus (RTN) astrocytes derived from PHOX2B-positive, OLIG3-negative progenitor cells, that interact with PHOX2B-expressing RTN chemosensory neurons. PHOX2B-derived astrocyte ablation during early life results in adult-onset O2 chemoreflex deficiency. These animals also display changes in sleep homeostasis, including fragmented sleep and disturbances in delta power after sleep deprivation, all without observable changes in anxiety or social behaviours. Ultrastructural evaluation of the RTN demonstrates that PHOX2B-derived astrocyte ablation results in features characteristic of degenerative neuro-axonal dystrophy, including abnormally dilated axon terminals and increased amounts of synapses containing autophagic vacuoles/phagosomes. We conclude that PHOX2B-derived astrocytes are necessary for maintaining a functional O2 chemosensory reflex in the adult, modulate sleep homeostasis, and are key regulators of synaptic integrity in the RTN region, which is necessary for the chemosensory control of breathing. These data also highlight how defects in embryonic development may manifest as neurodegenerative pathology in an adult.
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Affiliation(s)
| | - Talita M. Silva
- Department of Physiology and BiophysicsInstitute of Biomedical ScienceUniversity of Sao PauloSao PauloBrazil
| | - Summer R. Fair
- Department of PathologyThe Ohio State University College of MedicineColumbusOHUSA
| | - Jillian Liu
- Department of PathologyThe Ohio State University College of MedicineColumbusOHUSA
| | - Srinivasan Tupal
- Department of PathologyThe Ohio State University College of MedicineColumbusOHUSA
| | - Behiye Kaya
- Department of PathologyThe Ohio State University College of MedicineColumbusOHUSA
| | - Aaron Cowgill
- Department of PathologyThe Ohio State University College of MedicineColumbusOHUSA
| | - Salil Mahajan
- Department of PathologyThe Ohio State University College of MedicineColumbusOHUSA
| | - Phelipe E. Silva
- Department of Physiology and BiophysicsInstitute of Biomedical ScienceUniversity of Sao PauloSao PauloBrazil
| | - Yangyang Wang
- Department of NeuroscienceThe Ohio State University College of MedicineColumbusOHUSA
- The Ohio State University Mathematical Biosciences InstituteColumbusOHUSA
| | - Angela R. Blissett
- Department of Mechanical and Aerospace EngineeringThe Ohio State University College of EngineeringColumbusOHUSA
| | - Mustafa Göksel
- Department of PathologyThe Ohio State University College of MedicineColumbusOHUSA
| | - Jeremy C. Borniger
- Department of NeuroscienceThe Ohio State University College of MedicineColumbusOHUSA
| | - Ning Zhang
- Department of NeuroscienceWest Virginia UniversityWVUSA
| | - Silvio A. Fernandes‐Junior
- The Ohio State University Campus Microscopy and Imaging FacilityColumbusOHUSA
- Department of PharmacologyInstitute of Biomedical ScienceUniversity of São PauloSao PauloBrazil
| | - Fay Catacutan
- Department of PathologyThe Ohio State University College of MedicineColumbusOHUSA
| | - Michele J. Alves
- Department of PathologyThe Ohio State University College of MedicineColumbusOHUSA
| | | | - Vishnu Sundaresean
- Department of PathologyThe Ohio State University College of MedicineColumbusOHUSA
| | - Jens Rekling
- Department of NeuroscienceUniversity of CopenhagenCopenhagenDenmark
| | - Ana C. Takakura
- Department of PharmacologyInstitute of Biomedical ScienceUniversity of São PauloSao PauloBrazil
| | - Thiago S. Moreira
- Department of Physiology and BiophysicsInstitute of Biomedical ScienceUniversity of Sao PauloSao PauloBrazil
| | - José J. Otero
- Department of PathologyThe Ohio State University College of MedicineColumbusOHUSA
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6
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Abstract
The functions of sleep remain a mystery. Yet they must be important since sleep is highly conserved, and its chronic disruption is associated with various metabolic, psychiatric, and neurodegenerative disorders. This review will cover our evolving understanding of the mechanisms by which sleep is controlled and the complex relationship between sleep and disease states.
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Affiliation(s)
- William J Joiner
- Department of Pharmacology, Biomedical Sciences Graduate Program, Neurosciences Graduate Program, and Center for Circadian Biology, University of California San Diego , La Jolla, California
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7
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Qi G, van Aerde K, Abel T, Feldmeyer D. Adenosine Differentially Modulates Synaptic Transmission of Excitatory and Inhibitory Microcircuits in Layer 4 of Rat Barrel Cortex. Cereb Cortex 2018; 27:4411-4422. [PMID: 27522071 DOI: 10.1093/cercor/bhw243] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2016] [Accepted: 07/15/2016] [Indexed: 12/27/2022] Open
Abstract
Adenosine is considered to be a key regulator of sleep homeostasis by promoting slow-wave sleep through inhibition of the brain's arousal centers. However, little is known about the effect of adenosine on neuronal network activity at the cellular level in the neocortex. Here, we show that adenosine differentially modulates synaptic transmission between different types of neurons in cortical layer 4 (L4) through activation of pre- and/or postsynaptically located adenosine A1 receptors. In recurrent excitatory connections between L4 spiny neurons, adenosine suppresses synaptic transmission through activation of both pre- and postsynaptic A1 receptors. In reciprocal excitatory and inhibitory connections between L4 spiny neurons and interneurons, adenosine strongly suppresses excitatory transmission via activating presynaptic A1 receptors but only slightly suppresses inhibitory transmission via activating postsynaptic A1 receptors. Adenosine has no effect on inhibitory transmission between L4 interneurons. The effect of adenosine is concentration dependent and first visible at a concentration of 1 μM. The effect of adenosine is blocked by the specific A1 receptor antagonist, 8-cyclopentyltheophylline or the nonspecific adenosine receptor antagonist, caffeine. By differentially affecting excitatory and inhibitory synaptic transmission, adenosine changes the excitation-inhibition balance and causes an overall shift to lower excitability in L4 primary somatosensory (barrel) cortical microcircuits.
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Affiliation(s)
- Guanxiao Qi
- Institute of Neuroscience and Medicine, INM-2, Research Centre Jülich, D-52425 Jülich, Germany
| | - Karlijn van Aerde
- Institute of Neuroscience and Medicine, INM-2, Research Centre Jülich, D-52425 Jülich, Germany.,Department of Translational Neuroscience, Brain Center Rudolf Magnus, University Medical Center Utrecht, 3508 AB Utrecht, The Netherlands
| | - Ted Abel
- Department of Biology, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Dirk Feldmeyer
- Institute of Neuroscience and Medicine, INM-2, Research Centre Jülich, D-52425 Jülich, Germany.,Department of Psychiatry, Psychotherapy and Psychosomatics, RWTH Aachen University, D-52074 Aachen, Germany.,Jülich-Aachen Research Alliance-Brain, Translational Brain Medicine, D-52074 Aachen, Germany
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8
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Oikonomou KD, Singh MB, Rich MT, Short SM, Antic SD. Contribution of extrasynaptic N-methyl-D-aspartate and adenosine A1 receptors in the generation of dendritic glutamate-mediated plateau potentials. Philos Trans R Soc Lond B Biol Sci 2016; 370:rstb.2014.0193. [PMID: 26009772 DOI: 10.1098/rstb.2014.0193] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Thin basal dendrites can strongly influence neuronal output via generation of dendritic spikes. It was recently postulated that glial processes actively support dendritic spikes by either ceasing glutamate uptake or by actively releasing glutamate and adenosine triphosphate (ATP). We used calcium imaging to study the role of NR2C/D-containing N-methyl-d-aspartate (NMDA) receptors and adenosine A1 receptors in the generation of dendritic NMDA spikes and plateau potentials in basal dendrites of layer 5 pyramidal neurons in the mouse prefrontal cortex. We found that NR2C/D glutamate receptor subunits contribute to the amplitude of synaptically evoked NMDA spikes. Dendritic calcium signals associated with glutamate-evoked dendritic plateau potentials were significantly shortened upon application of the NR2C/D receptor antagonist PPDA, suggesting that NR2C/D receptors prolong the duration of calcium influx during dendritic spiking. In contrast to NR2C/D receptors, adenosine A1 receptors act to abbreviate dendritic and somatic signals via the activation of dendritic K(+) current. This current is characterized as a slow-activating outward-rectifying voltage- and adenosine-gated current, insensitive to 4-aminopyridine but sensitive to TEA. Our data support the hypothesis that the release of glutamate and ATP from neurons or glia contribute to initiation, maintenance and termination of local dendritic glutamate-mediated regenerative potentials.
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Affiliation(s)
- Katerina D Oikonomou
- Department of Neuroscience, University of Connecticut Health Center, Farmington, CT 06030, USA
| | - Mandakini B Singh
- Department of Neuroscience, University of Connecticut Health Center, Farmington, CT 06030, USA
| | - Matthew T Rich
- Department of Neuroscience, University of Connecticut Health Center, Farmington, CT 06030, USA
| | - Shaina M Short
- Department of Neuroscience, University of Connecticut Health Center, Farmington, CT 06030, USA
| | - Srdjan D Antic
- Department of Neuroscience, University of Connecticut Health Center, Farmington, CT 06030, USA
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9
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Astrocytic Regulation of Sleep Processes. CURRENT SLEEP MEDICINE REPORTS 2015. [DOI: 10.1007/s40675-014-0005-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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10
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Role for neuronal nitric oxide synthase in sleep homeostasis and arousal. Proc Natl Acad Sci U S A 2013; 110:19982-3. [PMID: 24284175 DOI: 10.1073/pnas.1319863110] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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11
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Adenosine A(1) receptors in mouse pontine reticular formation depress breathing, increase anesthesia recovery time, and decrease acetylcholine release. Anesthesiology 2013; 118:327-36. [PMID: 23263018 DOI: 10.1097/aln.0b013e31827d413e] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
BACKGROUND Clinical and preclinical data demonstrate the analgesic actions of adenosine. Central administration of adenosine agonists, however, suppresses arousal and breathing by poorly understood mechanisms. This study tested the two-tailed hypothesis that adenosine A1 receptors in the pontine reticular formation (PRF) of C57BL/6J mice modulate breathing, behavioral arousal, and PRF acetylcholine release. METHODS Three sets of experiments used 51 mice. First, breathing was measured by plethysmography after PRF microinjection of the adenosine A1 receptor agonist N-sulfophenyl adenosine (SPA) or saline. Second, mice were anesthetized with isoflurane and the time to recovery of righting response (RoRR) was quantified after a PRF microinjection of SPA or saline. Third, acetylcholine release in the PRF was measured before and during microdialysis delivery of SPA, the adenosine A1 receptor antagonist 1, 3-dipropyl-8-cyclopentylxanthine, or SPA and 1, 3-dipropyl-8-cyclopentylxanthine. RESULTS First, SPA significantly decreased respiratory rate (-18%), tidal volume (-12%), and minute ventilation (-16%). Second, SPA concentration accounted for 76% of the variance in RoRR. Third, SPA concentration accounted for a significant amount of the variance in acetylcholine release (52%), RoRR (98%), and breathing rate (86%). 1, 3-dipropyl-8-cyclopentylxanthine alone caused a concentration-dependent increase in acetylcholine, a decrease in RoRR, and a decrease in breathing rate. Coadministration of SPA and 1, 3-dipropyl-8-cyclopentylxanthine blocked the SPA-induced decrease in acetylcholine and increase in RoRR. CONCLUSIONS Endogenous adenosine acting at adenosine A1 receptors in the PRF modulates breathing, behavioral arousal, and acetylcholine release. The results support the interpretation that an adenosinergic-cholinergic interaction within the PRF comprises one neurochemical mechanism underlying the wakefulness stimulus for breathing.
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12
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Porkka-Heiskanen T. Sleep homeostasis. Curr Opin Neurobiol 2013; 23:799-805. [PMID: 23510741 DOI: 10.1016/j.conb.2013.02.010] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2013] [Revised: 02/19/2013] [Accepted: 02/20/2013] [Indexed: 10/27/2022]
Abstract
Research on sleep homeostasis aims to answer the question: how does the brain measure the duration and intensity of previous wakefulness in order to increase the duration and intensity of subsequent sleep? The search of regulatory factors has identified a number of potential molecules that increase their concentration in waking and decrease it during sleep. These factors regulate many physiological functions, including energy metabolism, neural plasticity and immune functions and one molecule may participate in the regulation of all these functions. The method to study regulation of sleep homeostasis is experimental prolongation of waking, which is used also to address the question of physiological purpose of sleep: prolonging wakefulness provokes symptoms that tell us what goes wrong during lack of sleep. The interpretation of the role of each identified factor in the regulation of sleep/sleep homeostasis reflects the theoretical background concept of the research. Presently three main concepts are being actively studied: the energy (depletion) hypothesis, the neural plasticity hypothesis and the (immune) defense hypothesis.
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Affiliation(s)
- Tarja Porkka-Heiskanen
- University of Helsinki, Institute of Biomedicine, Department of Physiology, PO Box 63, 00014 University of Helsinki, Finland.
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13
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Dias RB, Rombo DM, Ribeiro JA, Henley JM, Sebastião AM. Adenosine: setting the stage for plasticity. Trends Neurosci 2013; 36:248-57. [PMID: 23332692 DOI: 10.1016/j.tins.2012.12.003] [Citation(s) in RCA: 99] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2012] [Revised: 10/09/2012] [Accepted: 12/14/2012] [Indexed: 12/19/2022]
Abstract
It is widely accepted that Hebbian forms of plasticity mediate selective modifications in synaptic strength underlying information encoding in response to experience and circuit formation or refinement throughout development. Several complementary forms of homeostatic plasticity coordinate to keep Hebbian plasticity in check, frequently through the actions of conserved regulatory molecules. Recent evidence suggests that this may be the case for adenosine, which is ubiquitous in the brain and is released by both neurons and glial cells via constitutive and activity-dependent mechanisms. Through A1 and A2A receptor activation, adenosine modulates neuronal homeostasis and tunes the ability of synapses to undergo and/or sustain plasticity. Here, we review how adenosine equilibrates neuronal activity and sets the stage for synaptic plasticity.
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Affiliation(s)
- Raquel B Dias
- Institute of Pharmacology and Neurosciences, Faculty of Medicine, University of Lisbon, Lisbon, Portugal
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14
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Lüthi A. The Adenosine Story Goes Ionic: CaV2.1-type Ca2+ Channels Identified as Effectors of Adenosine's Somnogenic Actions. Sleep 2013; 36:13-4. [DOI: 10.5665/sleep.2290] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
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15
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Abstract
This review summarizes the brain mechanisms controlling sleep and wakefulness. Wakefulness promoting systems cause low-voltage, fast activity in the electroencephalogram (EEG). Multiple interacting neurotransmitter systems in the brain stem, hypothalamus, and basal forebrain converge onto common effector systems in the thalamus and cortex. Sleep results from the inhibition of wake-promoting systems by homeostatic sleep factors such as adenosine and nitric oxide and GABAergic neurons in the preoptic area of the hypothalamus, resulting in large-amplitude, slow EEG oscillations. Local, activity-dependent factors modulate the amplitude and frequency of cortical slow oscillations. Non-rapid-eye-movement (NREM) sleep results in conservation of brain energy and facilitates memory consolidation through the modulation of synaptic weights. Rapid-eye-movement (REM) sleep results from the interaction of brain stem cholinergic, aminergic, and GABAergic neurons which control the activity of glutamatergic reticular formation neurons leading to REM sleep phenomena such as muscle atonia, REMs, dreaming, and cortical activation. Strong activation of limbic regions during REM sleep suggests a role in regulation of emotion. Genetic studies suggest that brain mechanisms controlling waking and NREM sleep are strongly conserved throughout evolution, underscoring their enormous importance for brain function. Sleep disruption interferes with the normal restorative functions of NREM and REM sleep, resulting in disruptions of breathing and cardiovascular function, changes in emotional reactivity, and cognitive impairments in attention, memory, and decision making.
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Affiliation(s)
- Ritchie E Brown
- Laboratory of Neuroscience, VA Boston Healthcare System and Harvard Medical School, Brockton, Massachusetts 02301, USA
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16
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Hawryluk JM, Ferrari LL, Keating SA, Arrigoni E. Adenosine inhibits glutamatergic input to basal forebrain cholinergic neurons. J Neurophysiol 2012; 107:2769-81. [PMID: 22357797 PMCID: PMC3362278 DOI: 10.1152/jn.00528.2011] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2011] [Accepted: 02/15/2012] [Indexed: 01/03/2023] Open
Abstract
Adenosine has been proposed as an endogenous homeostatic sleep factor that accumulates during waking and inhibits wake-active neurons to promote sleep. It has been specifically hypothesized that adenosine decreases wakefulness and promotes sleep recovery by directly inhibiting wake-active neurons of the basal forebrain (BF), particularly BF cholinergic neurons. We previously showed that adenosine directly inhibits BF cholinergic neurons. Here, we investigated 1) how adenosine modulates glutamatergic input to BF cholinergic neurons and 2) how adenosine uptake and adenosine metabolism are involved in regulating extracellular levels of adenosine. Our experiments were conducted using whole cell patch-clamp recordings in mouse brain slices. We found that in BF cholinergic neurons, adenosine reduced the amplitude of AMPA-mediated evoked glutamatergic excitatory postsynaptic currents (EPSCs) and decreased the frequency of spontaneous and miniature EPSCs through presynaptic A(1) receptors. Thus we have demonstrated that in addition to directly inhibiting BF cholinergic neurons, adenosine depresses excitatory inputs to these neurons. It is therefore possible that both direct and indirect inhibition may synergistically contribute to the sleep-promoting effects of adenosine in the BF. We also found that blocking the influx of adenosine through the equilibrative nucleoside transporters or inhibiting adenosine kinase and adenosine deaminase increased endogenous adenosine inhibitory tone, suggesting a possible mechanism through which adenosine extracellular levels in the basal forebrain are regulated.
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Affiliation(s)
- J M Hawryluk
- Department of Neurology, Beth Israel Deaconess Medical Center, Boston, MA 02215, USA
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17
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Xia JX, Xiong JX, Wang HK, Duan SM, Ye JN, Hu ZA. Presynaptic inhibition of GABAergic synaptic transmission by adenosine in mouse hypothalamic hypocretin neurons. Neuroscience 2011; 201:46-56. [PMID: 22119641 DOI: 10.1016/j.neuroscience.2011.11.019] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2011] [Revised: 11/08/2011] [Accepted: 11/08/2011] [Indexed: 10/15/2022]
Abstract
Hypocretin neurons in the lateral hypothalamus, a new wakefulness-promoting center, have been recently regarded as an important target involved in endogenous adenosine-regulating sleep homeostasis. The GABAergic synaptic transmissions are the main inhibitory afferents to hypocretin neurons, which play an important role in the regulation of excitability of these neurons. The inhibitory effect of adenosine, a homeostatic sleep-promoting factor, on the excitatory glutamatergic synaptic transmissions in hypocretin neurons has been well documented, whether adenosine also modulates these inhibitory GABAergic synaptic transmissions in these neurons has not been investigated. In this study, the effect of adenosine on inhibitory postsynaptic currents (IPSCs) in hypocretin neurons was examined by using perforated patch-clamp recordings in the acute hypothalamic slices. The findings demonstrated that adenosine suppressed the amplitude of evoked IPSCs in a dose-dependent manner, which was completely abolished by 8-cyclopentyltheophylline (CPT), a selective antagonist of adenosine A1 receptor but not adenosine A2 receptor antagonist 3,7-dimethyl-1-(2-propynyl) xanthine. A presynaptic origin was suggested as following: adenosine increased paired-pulse ratio as well as reduced GABAergic miniature IPSC frequency without affecting the miniature IPSC amplitude. Further findings demonstrated that when the frequency of electrical stimulation was raised to 10 Hz, but not 1 Hz, a time-dependent depression of evoked IPSC amplitude was detected in hypocretin neurons, which could be partially blocked by CPT. However, under a higher frequency at 100 Hz stimulation, CPT had no action on the depressed GABAergic synaptic transmission induced by such tetanic stimulation in these hypocretin neurons. These results suggest that endogenous adenosine generated under certain stronger activities of synaptic transmissions exerts an inhibitory effect on GABAergic synaptic transmission in hypocretin neurons by activation of presynaptic adenosine A1 receptors, which may finely regulate the excitability of these neurons as well as eventually modulate the sleep-wakefulness.
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Affiliation(s)
- J X Xia
- Department of Physiology, Third Military Medical University, 30 Gaotanyan Street, Chongqing, 400038, China
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18
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Greene RW. Adenosine: front and center in linking nutrition and metabolism to neuronal activity. J Clin Invest 2011; 121:2548-50. [PMID: 21701073 DOI: 10.1172/jci58391] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Many individuals with epilepsy benefit from consuming a ketogenic diet, which is similar to the more commonly known Atkins diet. The underlying molecular reason for this has not been determined. However, in this issue of the JCI, Masino et al. have elucidated the mechanism responsible for the antiepileptic effects of the ketogenic diet in mice. The diet is shown to decrease expression of the enzyme adenosine kinase (Adk), which is responsible for clearing the endogenous antiepileptic agent adenosine (Ado) from the extracellular CNS space. Decreased expression of Adk results in increased extracellular Ado, activation of inhibitory Ado A1 receptors, and decreased seizure generation, the desired therapeutic effect. The authors' work serves to emphasize the importance of controlling Adk expression, not only as the mechanism of action of the ketogenic diet, but also as a potential target of future therapies.
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Affiliation(s)
- Robert W Greene
- Department of Psychiatry, University of Texas Southwestern Medical Center and Dallas VA Medical Center, Dallas, Texas 75390, USA.
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19
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Greene RW, Frank MG. Slow wave activity during sleep: functional and therapeutic implications. Neuroscientist 2010; 16:618-33. [PMID: 20921564 DOI: 10.1177/1073858410377064] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Electroencephalographic slow-wave activity (EEG SWA) is an electrophysiological signature of slow (0.5 to 4.0 Hz), synchronized, oscillatory neocortical activity. In healthy individuals, EEG SWA is maximally expressed during non-rapid-eye-movement (non-REM) sleep, and intensifies as a function of prior wake duration. Many of the cellular and network mechanisms generating EEG SWA have been identified, but a number of questions remain unanswered. For example, although EEG SWA is a marker of sleep need, its precise relationship with sleep homeostasis and its roles in the brain are unknown. In this review, the authors discuss their current understanding of the neural mechanisms and possible functions of EEG SWA.
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Affiliation(s)
- Robert W Greene
- Department of Psychiatry, UTSW Medical Center, Dallas VA, Dallas, Texas 75390, USA.
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20
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Brambilla D, Barajon I, Bianchi S, Opp MR, Imeri L. Interleukin-1 inhibits putative cholinergic neurons in vitro and REM sleep when microinjected into the rat laterodorsal tegmental nucleus. Sleep 2010; 33:919-29. [PMID: 20614852 DOI: 10.1093/sleep/33.7.919] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
STUDY OBJECTIVES REM sleep is suppressed during infection, an effect mimicked by the administration of cytokines such as interleukin-1 (IL-1). In spite of this observation, brain sites and neurochemical systems mediating IL-1-induced suppression of REM sleep have not been identified. Cholinergic neurons in the brainstem laterodorsal tegmental nucleus (LDT) are part of the neuronal circuitry responsible for REM sleep generation. Since IL-1 inhibits acetylcholine synthesis and release, the aim of this study was to test the two different, but related hypotheses. We hypothesized that IL-1 inhibits LDT cholinergic neurons, and that, as a result of this inhibition, IL-1 suppresses REM sleep. DESIGN, MEASUREMENT, AND RESULTS To test these hypotheses, the electrophysiological activity of putative cholinergic LDT neurons was recorded in a rat brainstem slice preparation. Interleukin-1 significantly inhibited the firing rate of 76% of recorded putative cholinergic LDT neurons and reduced the amplitude of glutamatergic evoked potentials in 60% of recorded neurons. When IL-1 (1 ng) was microinjected into the LDT of freely behaving rats, REM sleep was reduced by about 50% (from 12.7% +/- 1.5% of recording time [after vehicle] to 6.1% +/- 1.4% following IL-1 administration) during post-injection hours 3-4. CONCLUSIONS Results of this study support the hypothesis that IL-1 can suppress REM sleep by acting at the level of the LDT nucleus. Furthermore this effect may result from the inhibition of evoked glutamatergic responses and of spontaneous firing of putative cholinergic LDT neurons.
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Affiliation(s)
- Dario Brambilla
- Department of Human Physiology, University of Milan Medical School, Milan, Italy
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21
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Etherington LAV, Patterson GE, Meechan L, Boison D, Irving AJ, Dale N, Frenguelli BG. Astrocytic adenosine kinase regulates basal synaptic adenosine levels and seizure activity but not activity-dependent adenosine release in the hippocampus. Neuropharmacology 2009; 56:429-37. [PMID: 18957298 PMCID: PMC9972962 DOI: 10.1016/j.neuropharm.2008.09.016] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2008] [Revised: 09/16/2008] [Accepted: 09/22/2008] [Indexed: 12/20/2022]
Abstract
Adenosine is an endogenous inhibitor of excitatory synaptic transmission with potent anticonvulsant properties in the mammalian brain. Given adenosine's important role in modulating synaptic transmission, several mechanisms exist to regulate its extracellular availability. One of these is the intracellular enzyme adenosine kinase (ADK), which phosphorylates adenosine to AMP. We have investigated the role that ADK plays in regulating the presence and effects of extracellular adenosine in area CA1 of rat hippocampal slices. Inhibition of ADK activity with 5'-iodotubercidin (IODO; 5 muM) raised extracellular adenosine, as measured with adenosine biosensors, and potently inhibited field excitatory post-synaptic potentials (fEPSPs) in an adenosine A(1)R-dependent manner. In nominally Mg(2+)-free aCSF, which facilitated the induction of electrically-evoked epileptiform activity, adenosine biosensor recordings revealed that seizures were accompanied by the transient release of adenosine. Under these conditions, IODO also inhibited the fEPSP and greatly suppressed epileptiform activity evoked by brief, high-frequency stimulation. During spontaneous seizures evoked by the A(1)R antagonist CPT, adenosine release was unaffected by IODO. This suggests that ADK activity does not limit activity-dependent adenosine release. On the basis of strong ADK immunoreactivity in GFAP-positive cells, astrocytes are likely to play a key role in regulating basal adenosine levels. It is this action of ADK on the basal adenosine tone that is permissive to seizure activity, and, by extension, other forms of activity-dependent neuronal activity such as synaptic plasticity.
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Affiliation(s)
- Lori-An V. Etherington
- Neurosciences Institute, Division of Pathology and Neuroscience, University of Dundee, Ninewells Hospital & Medical School, Dundee DD1 9SY, UK
| | - Graham E. Patterson
- Neurosciences Institute, Division of Pathology and Neuroscience, University of Dundee, Ninewells Hospital & Medical School, Dundee DD1 9SY, UK
| | - Louise Meechan
- Neurosciences Institute, Division of Pathology and Neuroscience, University of Dundee, Ninewells Hospital & Medical School, Dundee DD1 9SY, UK
| | - Detlev Boison
- RS Dow Neurobiology Laboratories, Legacy Research, 1225 NE 2nd Avenue, Portland, OR 97232-2003, USA
| | - Andrew J. Irving
- Neurosciences Institute, Division of Pathology and Neuroscience, University of Dundee, Ninewells Hospital & Medical School, Dundee DD1 9SY, UK
| | - Nicholas Dale
- Department of Biological Sciences, University of Warwick, Coventry CV4 7AL, UK
| | - Bruno G. Frenguelli
- Neurosciences Institute, Division of Pathology and Neuroscience, University of Dundee, Ninewells Hospital & Medical School, Dundee DD1 9SY, UK,Department of Biological Sciences, University of Warwick, Coventry CV4 7AL, UK,Correspondence to: Bruno G. Frenguelli, Department of Biological Sciences, University of Warwick, Coventry CV4 7AL, UK. Tel.: +44 02476 150591; fax: +44 02476 523701. (B.G. Frenguelli)
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22
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Scharf MT, Naidoo N, Zimmerman JE, Pack AI. The energy hypothesis of sleep revisited. Prog Neurobiol 2008; 86:264-80. [PMID: 18809461 DOI: 10.1016/j.pneurobio.2008.08.003] [Citation(s) in RCA: 135] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2007] [Revised: 06/08/2008] [Accepted: 08/27/2008] [Indexed: 01/09/2023]
Abstract
One of the proposed functions of sleep is to replenish energy stores in the brain that have been depleted during wakefulness. Benington and Heller formulated a version of the energy hypothesis of sleep in terms of the metabolites adenosine and glycogen. They postulated that during wakefulness, adenosine increases and astrocytic glycogen decreases reflecting the increased energetic demand of wakefulness. We review recent studies on adenosine and glycogen stimulated by this hypothesis. We also discuss other evidence that wakefulness is an energetic challenge to the brain including the unfolded protein response, the electron transport chain, NPAS2, AMP-activated protein kinase, the astrocyte-neuron lactate shuttle, production of reactive oxygen species and uncoupling proteins. We believe the available evidence supports the notion that wakefulness is an energetic challenge to the brain, and that sleep restores energy balance in the brain, although the mechanisms by which this is accomplished are considerably more complex than envisaged by Benington and Heller.
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Affiliation(s)
- Matthew T Scharf
- Center for Sleep and Respiratory Neurobiology, University of Pennsylvania School of Medicine, Translational Research Building, Suite 2100, 125 S. 31st Street, Philadelphia, PA 19104-3403, USA.
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23
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Perez-Buira S, Barrachina M, Rodriguez A, Albasanz JL, Martín M, Ferrer I. Expression levels of adenosine receptors in hippocampus and frontal cortex in argyrophilic grain disease. Neurosci Lett 2007; 423:194-9. [PMID: 17707587 DOI: 10.1016/j.neulet.2007.06.049] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2007] [Revised: 06/24/2007] [Accepted: 06/25/2007] [Indexed: 12/24/2022]
Abstract
Expression of adenosine receptors of the A1, A2A and A2B type has been examined in the post-mortem frontal cortex and hippocampus in argyrophilic grain disease (AGD), a tauopathy affecting the hippocampus but usually not the frontal cortex, in an attempt to learn about the modulation of the adenosine pathway in this disorder. Significant increased levels of A1, but not of A2A and A2B, have been observed in AGD in the hippocampus but not in the frontal cortex, when compared with age-matched controls. This is accompanied by increased levels of adenylyl cyclase (AC), an effector of A1, and by increased (although not significant) percentage of inhibition of forskolin-stimulated AC by the A1 agonist cyclohexyladenosine in the hippocampus in AGD. These findings indicate sensitization of A1/AC in the hippocampus in AGD, and support a putative activation of the A1/AC pathway that may facilitate protection of this preferentially involved region in AGD.
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Affiliation(s)
- S Perez-Buira
- Institut de Neuropatologia, Servei Anatomia Patològica, IDIBELL-Hospital Universitari de Bellvitge, Facultad de Medicina, Universitat de Barcelona, carrer Feixa Llarga sn, 08907 Hospitalet de Llobregat, Spain
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24
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Abstract
This review is focused on purinergic neurotransmission, i.e., ATP released from nerves as a transmitter or cotransmitter to act as an extracellular signaling molecule on both pre- and postjunctional membranes at neuroeffector junctions and synapses, as well as acting as a trophic factor during development and regeneration. Emphasis is placed on the physiology and pathophysiology of ATP, but extracellular roles of its breakdown product, adenosine, are also considered because of their intimate interactions. The early history of the involvement of ATP in autonomic and skeletal neuromuscular transmission and in activities in the central nervous system and ganglia is reviewed. Brief background information is given about the identification of receptor subtypes for purines and pyrimidines and about ATP storage, release, and ectoenzymatic breakdown. Evidence that ATP is a cotransmitter in most, if not all, peripheral and central neurons is presented, as well as full accounts of neurotransmission and neuromodulation in autonomic and sensory ganglia and in the brain and spinal cord. There is coverage of neuron-glia interactions and of purinergic neuroeffector transmission to nonmuscular cells. To establish the primitive and widespread nature of purinergic neurotransmission, both the ontogeny and phylogeny of purinergic signaling are considered. Finally, the pathophysiology of purinergic neurotransmission in both peripheral and central nervous systems is reviewed, and speculations are made about future developments.
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Affiliation(s)
- Geoffrey Burnstock
- Autonomic Neurscience Centre, Royal Free and University College Medical School, London, UK.
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25
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Arrigoni E, Rosenberg PA. Nitric oxide-induced adenosine inhibition of hippocampal synaptic transmission depends on adenosine kinase inhibition and is cyclic GMP independent. Eur J Neurosci 2007; 24:2471-80. [PMID: 17100836 DOI: 10.1111/j.1460-9568.2006.05124.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Adenosine is an important inhibitory neuromodulator that regulates neuronal excitability. Several studies have shown that nitric oxide induces release of adenosine. Here we investigated the mechanism of this release. We studied the effects of nitric oxide on evoked field excitatory postsynaptic potentials (fEPSPs) recorded in the CA1 area of rat hippocampal slices. The nitric oxide donor 1,1-diethyl-2-hydroxy-2-nitroso-hydrazine sodium (DEA/NO; 100 microm) depressed the fEPSP by 77.6 +/- 4.1%. This effect was abolished by the adenosine A1 antagonist 8-cyclopentyl-1,3-dipropylxanthine (DPCPX; 400 nm), indicating that the nitric oxide effect was mediated by adenosine accumulation. The DEA/NO effect was unaltered by the 5'-ectonucleotidase inhibitor alpha,beta-methylene-adenosine 5'-diphosphate (AMP-CP; 100 microm), indicating that extracellular adenosine did not derive from ATP or cAMP release. The guanylyl cyclase inhibitor 1H-[1,2,4]oxadiazole[4,3-a]quinoxaline-1-one (ODQ; 5 microm) did not affect nitric oxide depression of the fEPSPs, indicating that nitric oxide-mediated adenosine release was not mediated through a cGMP signaling cascade. This conclusion was confirmed by the observation that 8-(4-chlorophenylthio)-guanosine-3',5'-cyclic monophosphate (8-pCPT-cGMP; 1 mm) reversibly depressed the fEPSP by 24.9 +/- 4.5%, but this effect was not blocked by adenosine antagonists. Adenosine kinase inhibitor 5-iodotubercidin (ITU; 7 microm) occluded the nitric oxide effects by 74%, suggesting that inhibition of adenosine kinase activity contributes to adenosine release. In conclusion, exogenous nitric oxide evokes adenosine release by a cGMP-independent pathway. Intracellular cGMP elevation partially inhibits the fEPSP but not through adenosine release. Although a direct block of adenosine kinase by nitric oxide can not be excluded, the depression of adenosine kinase activity may be due to inhibition by its own substrate adenosine.
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Affiliation(s)
- Elda Arrigoni
- Department of Neurology, Beth Israel Deaconess Medical Center, Boston, MA 02215, USA
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26
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Liu ZW, Gao XB. Adenosine inhibits activity of hypocretin/orexin neurons by the A1 receptor in the lateral hypothalamus: a possible sleep-promoting effect. J Neurophysiol 2006; 97:837-48. [PMID: 17093123 PMCID: PMC1783688 DOI: 10.1152/jn.00873.2006] [Citation(s) in RCA: 154] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Neurons in the lateral hypothalamus (LH) that contain hypocretin/orexin have been established as important promoters of arousal. Deficiencies in the hypocretin/orexin system lead to narcolepsy. The inhibition of hypocretin/orexin neurons by sleep-promoting neurotransmitters has been suggested as one part of the sleep regulation machinery. Adenosine has been identified as a sleep promoter and its role in sleep regulation in the basal forebrain has been well documented. However, the effect of adenosine on arousal-promoting hypocretin/orexin neurons has not been addressed, despite recent evidence that immunocytochemical visualization of adenosine receptors was detected in these neurons. In this study, we examined the hypothesis that adenosine inhibits the activity of hypocretin/orexin neurons by using electrophysiological methods in brain slices from mice expressing green fluorescent protein in hypocretin/orexin neurons. We found that adenosine significantly attenuated the frequency of action potentials without a change in membrane potential in hypocretin/orexin neurons. The adenosine-mediated inhibition arises from depression of excitatory synaptic transmission to hypocretin/orexin neurons because adenosine depresses the amplitude of evoked excitatory postsynaptic potential and the frequency of spontaneous and miniature excitatory postsynaptic currents in these neurons. At the cell body of the hypocretin/orexin neurons, adenosine inhibits voltage-dependent calcium currents without the induction of GIRK current. The inhibitory effect of adenosine is dose dependent, pertussis toxin sensitive, and mediated by A1 receptors. In summary, our data suggest that in addition to its effect in the basal forebrain, adenosine exerts its sleep-promoting effect in the LH by inhibition of hypocretin/orexin neurons.
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Affiliation(s)
- Zhong-Wu Liu
- Department of OB/GYN and Reproductive Science, Yale University School of Medicine, New Haven, CT 06520
- Department of Neurobiology, Yunyang Medical College, Shiyan, Hubei 442000, P. R. China
| | - Xiao-Bing Gao
- Department of OB/GYN and Reproductive Science, Yale University School of Medicine, New Haven, CT 06520
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27
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Rodríguez A, Martín M, Albasanz JL, Barrachina M, Espinosa JC, Torres JM, Ferrer I. Adenosine A1 Receptor Protein Levels and Activity Is Increased in the Cerebral Cortex in Creutzfeldt-Jakob Disease and in Bovine Spongiform Encephalopathy-Infected Bovine-PrP Mice. J Neuropathol Exp Neurol 2006; 65:964-75. [PMID: 17021401 DOI: 10.1097/01.jnen.0000235120.59935.f5] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Prion diseases are characterized by neuronal loss, astrocytic gliosis, spongiform change, and abnormal protease-resistant prion protein (PrP) deposition. Creutzfeldt-Jakob disease (CJD) is the most prevalent human prion disease, whereas scrapie and bovine spongiform encephalopathy (BSE) are the most common animal prion diseases. Several candidates have been proposed as mediators of degeneration in prion diseases, one of them glutamate. Recent studies have shown reduced metabotropic glutamate receptor/phospholipase C signaling in the cerebral cortex in CJD, suggesting that this important neuromodulator and neuroprotector pathway is attenuated in CJD. Adenosine is involved in the regulation of different metabolic processes under physiological and pathologic conditions. Adenosine function is mediated by adenosine receptors, which are categorized into 4 types: A1, A2A, A2B, and A3. A1Rs are G-protein-coupled receptors that induce the inhibition of adenylyl cyclase activity. The most dramatic inhibitory actions of adenosine receptors are on the glutamatergic system. For these reasons, we examined the levels of A1Rs in the frontal cortex of 12 patients with CJD and 6 age-matched controls and in BSE-infected bovine-PrP transgenic mice (BoPrP-Tg110 mice) at different postincubation times to address modifications in A1Rs with disease progression. A significant increase in the protein levels of A1Rs was found in the cerebral cortex in CJD and in the murine BSE model at advanced stages of the disease and coincidental with the appearance of PrP expression. In addition, the activity of A1Rs was analyzed by in vitro assays with isolated membranes of the frontal cortex in CJD. Increased activity of the receptor, as revealed by the decreased forskolin-stimulated cAMP production in response to the A1R agonists cyclohexyl adenosine and cyclopentyl adenosine, was observed in CJD cases when compared with controls. Finally, mRNA A1R levels were similar in CJD and control cases, thus suggesting abnormal A1R turnover or dysregulation of raft-associated signaling pathways in CJD. These results show, for the first time, sensitization of A1Rs in prion diseases.
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Affiliation(s)
- Agustín Rodríguez
- Institut de Neuropatologia, Servei Anatomia Patològica, IDIBELL-Hospital Universitari de Bellvitge, Universitat de Barcelona, 08907 Hospitalet de Llobregat, Spain
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28
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Sergeeva OA, Klyuch BP, Fleischer W, Eriksson KS, Korotkova TM, Siebler M, Haas HL. P2Y receptor-mediated excitation in the posterior hypothalamus. Eur J Neurosci 2006; 24:1413-26. [PMID: 16965543 DOI: 10.1111/j.1460-9568.2006.05027.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Histaminergic neurons located in the posterior hypothalamus (tuberomamillary nucleus, TMN) project widely through the whole brain controlling arousal and attention. They are tonically active during wakefulness but cease firing during sleep. As a homeostatic theory of sleep involves ATP depletion and adenosine accumulation in the brain, we investigated the role of ATP and its analogues as well as adenosine on neuronal activity in the TMN. We show increased firing of rat TMN neurons by ATP, ADP, UTP and 2meSATP, indicating activation of receptors belonging to the P2Y family. Adenosine affected neither membrane potential nor firing of these cells. Single-cell reverse transcriptase-polymerase chain reaction revealed that P2Y1 and P2Y4 are prevailing receptors in TMN neurons. P2Y1 receptor mRNA was detected with a higher frequency in 2-week-old than in 4-week-old rats; in accordance, 2meSATP was more potent than ATP. Semi-quantitative real-time polymerase chain reaction revealed a developmental downregulation of mRNA levels for P2Y1 and P2Y4 receptors. Immunocytochemistry demonstrated neuronal and glial localization of the P2Y1 receptor protein. Network activity measured with multielectrode arrays in primary cultures made from the posterior hypothalamus was enhanced by UTP and 2meSATP (P2Y4 and P2Y1 agonists, respectively). ATP caused an inhibition of firing, which was reversed in the presence of suramin or gabazine [gamma-aminobutyric acid (GABA)A receptor antagonist], indicating that GABAergic neurons are preferentially activated by ATP in this network. Excitation of the wake-active TMN neurons by nucleotides and the lack of adenosine action may be important factors in sleep-wake regulation.
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MESH Headings
- Action Potentials/drug effects
- Action Potentials/physiology
- Adenine Nucleotides/pharmacology
- Adenosine Diphosphate/analogs & derivatives
- Adenosine Diphosphate/pharmacology
- Animals
- Animals, Newborn
- Dose-Response Relationship, Drug
- Drug Interactions
- Gene Expression/drug effects
- Histamine/metabolism
- Hypothalamus, Posterior/cytology
- Hypothalamus, Posterior/drug effects
- Hypothalamus, Posterior/physiology
- Imidazoles/pharmacology
- Immunohistochemistry/methods
- In Vitro Techniques
- Male
- Methylhistamines/pharmacology
- Microtubule-Associated Proteins/metabolism
- Purinergic P2 Receptor Antagonists
- Pyridoxal Phosphate/analogs & derivatives
- Pyridoxal Phosphate/pharmacology
- RNA, Messenger/metabolism
- Rats
- Receptors, Metabotropic Glutamate/metabolism
- Receptors, Purinergic P2/classification
- Receptors, Purinergic P2/genetics
- Receptors, Purinergic P2/physiology
- Reverse Transcriptase Polymerase Chain Reaction/methods
- Temperature
- Thiorphan/analogs & derivatives
- Thiorphan/pharmacology
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Affiliation(s)
- Olga A Sergeeva
- Department of Neurophysiology, Heinrich-Heine-Universität, POB 101007, D-40001 Düsseldorf, Germany.
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29
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Coleman CG, Baghdoyan HA, Lydic R. Dialysis delivery of an adenosine A2Aagonist into the pontine reticular formation of C57BL/6J mouse increases pontine acetylcholine release and sleep. J Neurochem 2006; 96:1750-9. [PMID: 16539690 DOI: 10.1111/j.1471-4159.2006.03700.x] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
In vivo microdialysis in C57BL/6J (B6) mouse was used to test the hypothesis that activating adenosine A(2A) receptors in the pontine reticular formation (PRF) increases acetylcholine (ACh) release and rapid eye movement (REM) sleep. Eight concentrations of the adenosine A(2A) receptor agonist 2-p-(2-carboxyethyl)phenethylamino-5'-N-ethylcarboxamidoadenosine hydrochloride (CGS 21680; CGS) were delivered to the PRF and ACh in the PRF was quantified. ACh release was significantly increased by dialysis with 3 mum CGS and significantly decreased by dialysis with 10 and 100 microm CGS. Co-administration of the adenosine A(2A) receptor antagonist 4-(2-[7-amino-2-(2-furyl)[1,2,4]triazolo[2,3-a][1,3,5]triazin-5-ylamino]ethyl)phenol (ZM 241385; 30 nM) blocked the CGS-induced increase in ACh release. In a second series of experiments, CGS (3 microm) was delivered by dialysis to the PRF for 2 h while recording sleep and wakefulness. CGS significantly decreased time in wakefulness (-51% in h 1; -54% in h 2), increased time in non-rapid eye movement (NREM) sleep (90% in h 1; 151% in h 2), and increased both time in REM sleep (331% in h 2) and the number of REM sleep episodes (488% in h 2). The enhancement of REM sleep is consistent with the interpretation that adenosine A(2A) receptors in the PRF of the B6 mouse contribute to REM sleep regulation, in part, by increasing ACh release in the PRF. A(2A) receptor activation may promote NREM sleep via GABAergic inhibition of arousal promoting neurons in the PRF.
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Affiliation(s)
- Christal G Coleman
- Department of Anesthesiology, University of Michigan, Ann Arbor, Michigan 48109-0615, USA
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30
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Wong AYC, Billups B, Johnston J, Evans RJ, Forsythe ID. Endogenous activation of adenosine A1 receptors, but not P2X receptors, during high-frequency synaptic transmission at the calyx of Held. J Neurophysiol 2006; 95:3336-42. [PMID: 16481462 DOI: 10.1152/jn.00694.2005] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Activation of presynaptic receptors plays an important role in modulation of transmission at many synapses, particularly during high-frequency trains of stimulation. Adenosine-triphosphate (ATP) is coreleased with several neurotransmitters and acts at presynaptic sites to reduce transmitter release; such presynaptic P2X receptors occur at inhibitory and excitatory terminals in the medial nucleus of the trapezoid body (MNTB). We have investigated the mechanism of purinergic modulation during high-frequency repetitive stimulation at the calyx of Held synapse. Suppression of calyceal excitatory postsynaptic currents (EPSCs) by ATP and ATPgammaS (100 microM) was mimicked by adenosine application and was blocked by DPCPX (10 microM), indicating mediation by adenosine A1 receptors. DPCPX enhanced EPSC amplitudes during high-frequency synaptic stimulation, suggesting that adenosine has a physiological role in modulating transmission at the calyx. The Luciferin-Luciferase method was used to probe for endogenous ATP release (at 37 degrees C), but no release was detected. Blockers of ectonucleotidases also had no effect on endogenous synaptic depression, suggesting that it is adenosine acting on A1 receptors, rather than degradation of released ATP, which accounts for presynaptic purinergic suppression of synaptic transmission during physiological stimulus trains at this glutamatergic synapse.
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Affiliation(s)
- Adrian Y C Wong
- Department of Cell Physiology and Pharmacology, University of Leicester, United Kingdom
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31
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Deurveilher S, Lo H, Murphy JA, Burns J, Semba K. Differential c-Fos immunoreactivity in arousal-promoting cell groups following systemic administration of caffeine in rats. J Comp Neurol 2006; 498:667-89. [PMID: 16917819 DOI: 10.1002/cne.21084] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Despite the widespread use of caffeine, the neuronal mechanisms underlying its stimulatory effects are not completely understood. By using c-Fos immunohistochemistry as a marker of neuronal activation, we recently showed that stimulant doses of caffeine activate arousal-promoting hypothalamic orexin (hypocretin) neurons. In the present study, we investigated whether other key neurons of the arousal system are also activated by caffeine, via dual immunostaining for c-Fos and transmitter markers. Rats were administered three doses of caffeine or saline vehicle during the light phase. Caffeine at 10 and 30 mg/kg, i.p., increased motor activities, including locomotion, compared with after saline or a higher dose, 75 mg/kg. The three doses of caffeine induced distinct dose-related patterns of c-Fos immunoreactivity in several arousal-promoting areas, including orexin neurons and adjacent neurons containing neither orexin nor melanin-concentrating hormone; tuberomammillary histaminergic neurons; locus coeruleus noradrenergic neurons; noncholinergic basal forebrain neurons that do not contain parvalbumin; and nondopaminergic neurons in the ventral tegmental area. At any dose used, caffeine induced little or no c-Fos expression in cholinergic neurons of the basal forebrain and mesopontine tegmentum; dopaminergic neurons of the ventral tegmental area, central gray, and substantia nigra pars compacta; and serotonergic neurons in the dorsal raphe nucleus. Saline controls exhibited only few c-Fos-positive cells in most of the cell groups examined. These results indicate that motor-stimulatory doses of caffeine induce a remarkably restricted pattern of c-Fos expression in the arousal-promoting system and suggest that this specific neuronal activation may be involved in the behavioral arousal by caffeine.
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Affiliation(s)
- Samüel Deurveilher
- Department of Anatomy and Neurobiology, Faculty of Medicine, Dalhousie University, Halifax, Nova Scotia B3H 1X5, Canada
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32
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Fontanez DE, Porter JT. Adenosine A1 receptors decrease thalamic excitation of inhibitory and excitatory neurons in the barrel cortex. Neuroscience 2005; 137:1177-84. [PMID: 16343787 PMCID: PMC3698575 DOI: 10.1016/j.neuroscience.2005.10.022] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2005] [Revised: 10/17/2005] [Accepted: 10/17/2005] [Indexed: 11/29/2022]
Abstract
Caffeine is consumed worldwide to enhance wakefulness, but the cellular mechanisms are poorly understood. Caffeine blocks adenosine receptors suggesting that adenosine decreases cortical arousal. Given the widespread innervation of the cerebral cortex by thalamic fibers, adenosine receptors on thalamocortical terminals could provide an efficient method of limiting thalamic activation of the cortex. Using a mouse thalamocortical slice preparation and whole-cell patch clamp recordings, we examined whether thalamocortical terminals are modulated by adenosine receptors. Bath application of adenosine decreased excitatory postsynaptic currents elicited by stimulation of the ventrobasal thalamus. Thalamocortical synapses onto inhibitory and excitatory neurons were equally affected by adenosine. Adenosine also increased the paired pulse ratio and the coefficient of variation of the excitatory postsynaptic currents, suggesting that adenosine decreased glutamate release. The inhibition produced by adenosine was reversed by a selective antagonist of adenosine A1 receptors (8-cyclopentyltheophylline) and mimicked by a selective A1 receptor agonist (N6-cyclopentyladenosine). Our results indicate that thalamocortical excitation is regulated by presynaptic adenosine A1 receptors and provide a mechanism by which increased adenosine levels can directly reduce cortical excitability.
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Affiliation(s)
- D E Fontanez
- Department of Physiology and Pharmacology, Ponce School of Medicine, PO Box 7004, Ponce, Puerto Rico 00732
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33
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Ramos-Zepeda G, Herrero JF. Enhancement of wind-up by the combined administration of adenosine A1 receptor ligands on spinalized rats with carrageenan-induced inflammation. Neurosci Lett 2005; 384:177-82. [PMID: 15893424 DOI: 10.1016/j.neulet.2005.04.073] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2005] [Revised: 04/06/2005] [Accepted: 04/25/2005] [Indexed: 10/25/2022]
Abstract
The adenosine A1 receptor agonist N6-cyclopentyladenosine (CPA) is very effective in reducing wind-up in intact but not in spinalized adult rats with carrageenan-induced inflammation, suggesting an adenosine-mediated supraspinal modulation. Since wind-up is a spinal cord mediated phenomenon but highly influenced by descending modulatory systems, especially in situations of sensitization, we assessed the possible involvement of adenosine in the modulation of wind-up. We studied the effect of the adenosine A(1) receptor antagonist 8-cyclopentyl-1,3-dimethylxanthine (CPT) in the presence and in the absence of the adenosine A(1) receptor agonist CPA. The experiments were carried out in spinalized male Wistar rats under alpha-chloralose anaesthesia. Withdrawal reflexes, studied as single motor units, were activated by noxious mechanical and high-intensity repetitive electrical stimulation (wind-up). While CPA and CPT were not able to induce any change on wind-up when injected alone, the combination of the two drugs, in any order, lead to an important enhancement of wind-up. This enhancement not always paralleled an increase of responses to noxious mechanical stimulation, indicating that the effect is mainly located in the spinal cord. In addition, the enhancement of wind-up was not further increased by the administration of the opioid receptor antagonist naloxone. We conclude that the depression of the wind-up phenomenon observed in spinalized animals is, at least in part, dependent of adenosine systems and can be relieved by the combined administration of CPA and CPT.
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Affiliation(s)
- Guillermo Ramos-Zepeda
- Departamento de Fisiología, Campus Universitario, Universidad de Alcalá, Alcalá de Henares, 28871 Madrid, Spain
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Brambilla D, Chapman D, Greene R. Adenosine mediation of presynaptic feedback inhibition of glutamate release. Neuron 2005; 46:275-83. [PMID: 15848805 DOI: 10.1016/j.neuron.2005.03.016] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2004] [Revised: 01/11/2005] [Accepted: 03/12/2005] [Indexed: 11/23/2022]
Abstract
Conditions of increased metabolic demand relative to metabolite availability are associated with increased extracellular adenosine in CNS tissue. Synaptic activation of postsynaptic NMDA receptors on neurons of the cholinergic brainstem arousal center can increase sufficient extracellular adenosine to act on presynaptic A1 adenosine receptors (A1ADRs) of glutamate terminals, reducing release from the readily releasable pool. The time course of the adenosine response to an increase in glutamate release is slow (tau > 10 min), consistent with the role of adenosine as a fatigue factor that inhibits the activity of cholinergic arousal centers to reduce arousal.
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Affiliation(s)
- Dario Brambilla
- Department of Psychiatry, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
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Gu JW, Hasuo H, Takeya M, Akasu T. Effects of emodin on synaptic transmission in rat hippocampal CA1 pyramidal neurons in vitro. Neuropharmacology 2005; 49:103-11. [PMID: 15992585 DOI: 10.1016/j.neuropharm.2005.02.003] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2004] [Revised: 02/02/2005] [Accepted: 02/03/2005] [Indexed: 10/25/2022]
Abstract
Rhubarb extracts provide neuroprotection after brain injury, but the mechanism of this protective effect is not known. The present study tests the hypothesis that rhubarb extracts interfere with the release of glutamate by brain neurons and, therefore, reduce glutamate excitotoxicity. To this end, the effects of emodin, an anthraquinone derivative extracted from Rheum tanguticum Maxim. Ex. Balf, on the synaptic transmission of CA1 pyramidal neurons in rat hippocampus were studied in vitro. The excitatory postsynaptic potential (EPSP) was depressed by bath-application of emodin (0.3-30 microM). Paired-pulse facilitation (PPF) of the EPSP was significantly increased by emodin. The monosynaptic inhibitory postsynaptic potential (IPSP) recorded in the presence of glutamate receptor antagonists (DNQX and AP5) was not altered by emodin. Emodin decreased the frequency, but not the amplitude, of the miniature EPSP (mEPSP). The inhibition of the EPSP induced by emodin was blocked by either 8-CPT, an adenosine A1 receptor antagonist, or by adenosine deaminase. These results suggest that emodin inhibits the EPSP by decreasing the release of glutamate from Schaffer collateral/commissural terminals via the activation of adenosine A1 receptors in rat hippocampal CA1 area and that the neuroprotective effects of rhubarb extracts may result from decreased glutamate excitotoxicity.
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Affiliation(s)
- Jian-Wen Gu
- Department of Physiology, Kurume University School of Medicine, 67 Asahi-machi, Kurume 830-0011, Japan
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36
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Abstract
In a recent review, Frank and Heller (2003) provided support for their 'presleep theory' of sleep development. According to this theory, rapid eye movement (REM) and non-rapid eye movement (Non-REM) sleep in rats emerge from a common 'dissociated' state only when the neocortical EEG differentiates at 12 days of age (P12). Among the assumptions and inferences associated with this theory is that sleep before EEG differentiation is only 'sleep-like' and can only be characterized using behavioral measures; that the neural mechanisms governing presleep are distinct from those governing REM and Non-REM sleep; and that the presleep theory is the only theory that can account for developmental periods when REM and Non-REM sleep components appear to overlap. Evidence from our laboratory and others, however, refutes or casts doubt on these and other assertions. For example, infant sleep in rats is not 'sleep-like' in that it satisfies nearly every criterion used to characterize sleep across species. In addition, beginning as early as P2 in rats, myoclonic twitching occurs only against a background of muscle atonia, indicating that infant sleep is not dissociated and that electrographic measures are available for sleep characterization. Finally, improved techniques are leading to new insights concerning the neural substrates of sleep during early infancy. Thus, while many important developmental questions remain, the presleep theory, at least in its present form, does not accurately reflect the phenomenology of infant sleep.
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Affiliation(s)
- Mark S Blumberg
- Program in Behavioral and Cognitive Neuroscience, Department of Psychology, The University of Iowa, Iowa City, IA 5242, USA.
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37
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Radek RJ, Decker MW, Jarvis MF. The adenosine kinase inhibitor ABT-702 augments EEG slow waves in rats. Brain Res 2005; 1026:74-83. [PMID: 15476699 DOI: 10.1016/j.brainres.2004.08.011] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/10/2004] [Indexed: 11/25/2022]
Abstract
ABT-702 is a novel and selective non-nucleoside adenosine kinase (AK) inhibitor that produces increases in endogenous extracellular adenosine. Adenosine (ADO) is thought to be an important neuromodulator of sleep, therefore, the effects of ABT-702 and AK inhibition were examined on rat EEG and sleep, and compared to ADO receptor agonists to further evaluate the role of ADO receptor activation on sleep related EEG patterns. ABT-702 (10.0-30.0 micromol/kg, i.p.) increased the amplitude of the 1-4 Hz band (Fast Fourier Transform (FFT) analysis, p<0.05), which is indicative of augmented sleep-related slow waves. Theophylline (5.0 micromol/kg, i.p.), a centrally active, non-selective adenosine receptor antagonist, attenuated the effects of ABT-702 (20.0 micromol/kg, i.p.) on EEG, whereas 8-(p-sulfophenyl)-theophylline (8-PST, 150.0 micromol/kg, i.p.), a peripherally active antagonist, did not, indicating that the EEG effects of ABT-702 are mediated by a central ADO receptor mechanism. The selective A(1) agonist N6-cyclopentyladenosine (CPA, 30.0 micromol/kg, i.p.) also increased the amplitude of 1-4 Hz band, but was not as efficacious as ABT-702. In contrast, the A(2A) agonist CGS-21680 (1.0-10.0 micromol/kg, i.p.) and the non-selective agonist, N(6)-ethylcarboximidoadenosine (NECA, 0.03-0.1 micromol/kg, ip.), lowered 1-4 Hz amplitude for 2 h after injection. Finally, ABT-702 (10.0 micromol/kg, i.p.) was found to significantly increase slow wave sleep and decrease REM sleep in rats implanted with both EEG and EMG electrodes for evaluation of sleep. These studies demonstrate that increased extracellular adenosine through AK inhibition can elicit modulatory effects on EEG slow waves via an interaction with central ADO receptor subtypes.
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Affiliation(s)
- Richard J Radek
- Neurological Diseases Research, Global Pharmaceutical Research and Development, Abbott Laboratories, 100 Abbott Park Road, Abbott Park, IL 60064-3500, USA.
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Ramos-Zepeda G, Schröder W, Rosenow S, Herrero JF. Spinal vs. supraspinal antinociceptive activity of the adenosine A1 receptor agonist cyclopentyl-adenosine in rats with inflammation. Eur J Pharmacol 2004; 499:247-56. [PMID: 15381046 DOI: 10.1016/j.ejphar.2004.07.083] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2004] [Revised: 07/12/2004] [Accepted: 07/15/2004] [Indexed: 11/20/2022]
Abstract
The adenosine A(1) receptor is involved in spinal cord antinociception. As its role at supraspinal sites is not well known, we studied the systemic effects of its agonist N-cyclopentyl-adenosine (CPA) in single motor units from adult-spinalized, intact and sham-spinalized rats. CPA was not effective after spinalization, but it was very effective in intact animals (ID50: 92+/-1.3 microg/kg, noxious pinch) and over 10-fold more potent in sham-spinalized animals (ID50 of 8.3+/-1 microg/kg). Wind-up was also inhibited by CPA. We also studied the effect of CPA in the immature spinal cord preparation, where CPA dose-dependently inhibited responses to low (IC50s: 9+/-0.7 and 7.7+/-1.3 nM) and high intensity stimulation (IC50s: 4.9+/-0.5 and 12.1+/-2 nM). We conclude that the integrity of the spinal cord is crucial for the antinociceptive activity of systemic CPA in adult rats but not in immature rats, not yet influenced by a completely developed supraspinal control.
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Affiliation(s)
- Guillermo Ramos-Zepeda
- Departamento de Fisiología, Facultad de Medicina, Universidad de Alcalá, Alcalá de Henares, 28871 Madrid, Spain
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Basheer R, Strecker RE, Thakkar MM, McCarley RW. Adenosine and sleep–wake regulation. Prog Neurobiol 2004; 73:379-96. [PMID: 15313333 DOI: 10.1016/j.pneurobio.2004.06.004] [Citation(s) in RCA: 358] [Impact Index Per Article: 17.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2003] [Accepted: 06/28/2004] [Indexed: 10/26/2022]
Abstract
This review addresses three principal questions about adenosine and sleep-wake regulation: (1) Is adenosine an endogenous sleep factor? (2) Are there specific brain regions/neuroanatomical targets and receptor subtypes through which adenosine mediates sleepiness? (3) What are the molecular mechanisms by which adenosine may mediate the long-term effects of sleep loss? Data suggest that adenosine is indeed an important endogenous, homeostatic sleep factor, likely mediating the sleepiness that follows prolonged wakefulness. The cholinergic basal forebrain is reviewed in detail as an essential area for mediating the sleep-inducing effects of adenosine by inhibition of wake-promoting neurons via the A1 receptor. The A2A receptor in the subarachnoid space below the rostral forebrain may play a role in the prostaglandin D2-mediated somnogenic effects of adenosine. Recent evidence indicates that a cascade of signal transduction induced by basal forebrain adenosine A1 receptor activation in cholinergic neurons leads to increased transcription of the A1 receptor; this may play a role in mediating the longer-term effects of sleep deprivation, often called sleep debt.
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Affiliation(s)
- Radhika Basheer
- Neuroscience Laboratory, Department of Psychiatry, Harvard Medical School and Boston VA Healthcare System, Brockton, MA 02301, USA
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40
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Kohlmeier KA, Inoue T, Leonard CS. Hypocretin/orexin peptide signaling in the ascending arousal system: elevation of intracellular calcium in the mouse dorsal raphe and laterodorsal tegmentum. J Neurophysiol 2004; 92:221-35. [PMID: 14999052 DOI: 10.1152/jn.00076.2004] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Dysfunction of the hypocretin/orexin (Hcrt/Orx) peptide system is closely linked to the sleep disorder narcolepsy, suggesting that it is also central to the normal regulation of sleep and wakefulness. Indeed, Hcrt/Orx peptides produce long-lasting excitation of arousal-related neurons, including those in the laterodorsal tegmentum (LDT) and the dorsal raphe (DR), although the mechanisms underlying these actions are not understood. Since Hcrt/Orx mobilizes intracellular calcium ([Ca(2+)](i)) in cells transfected with orexin receptors and since receptor-mediated Ca(2+) transients are ubiquitous signaling mechanisms, we investigated whether Hcrt/Orx regulates [Ca(2+)](i) in the LDT and DR. Changes in [Ca(2+)](i) were monitored by fluorescence changes of fura-2 AM loaded cells in young mouse brain slices. We found Hcrt/Orx (Orexin-A, 30-1,000 nM) evoked long-lasting increases in [Ca(2+)](i) with differing temporal profiles ranging from spiking to smooth plateaus. A fragment of Hcrt/Orx (16-33) failed to evoke changes in [Ca(2+)](i) and changes were not blocked by TTX or ionotropic glutamate receptor antagonists, suggesting they resulted from specific activation of postsynaptic orexin receptors. Unlike orexin receptor-transfected cells, Hcrt/Orx-responses were not attenuated by depletion of Ca(2+) stores with cyclopiazonic acid (CPA; 3-30 microM), thapsigargin (3 microM), or ryanodine (20 microM), although store-depletion by either CPA or ryanodine blocked Ca(2+) mobilization by the metabotropic glutamate receptor agonist (+/-)-1-aminocyclopentane-trans-1,3-dicarboxylic acid (trans-ACPD; 30 microM). In contrast, Hcrt/Orx responses were strongly attenuated by lowering extracellular Ca(2+) ( approximately 20 microM) but were not inhibited by concentrations of KB-R7943 (10 microM) selective for blockade of sodium/calcium exchange. Nifedipine (10 microM), inhibited Hcrt/Orx responses but was more effective at abolishing spiking than plateau responses. Bay K 8644 (5-10 microM), an L-type calcium channel agonist, potentiated responses. Finally, responses were attenuated by inhibitors of protein kinase C (PKC) but not by inhibitors of adenylyl cyclase. Collectively, our findings indicate that Hcrt/Orx signaling in the reticular activating system involves elevation of [Ca(2+)](i) by a PKC-involved influx of Ca(2+) across the plasma membrane, in part, via L-type calcium channels. Thus the physiological release of Hcrt/Orx may help regulate Ca(2+)-dependent processes such as gene expression and NO production in the LDT and DR in relation with behavioral state. Accordingly, the loss of Hcrt/Orx signaling in narcolepsy would be expected to disrupt calcium-dependent processes in these and other target structures.
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Affiliation(s)
- Kristi A Kohlmeier
- Department of Physiology, New York Medical College, Valhalla, New York 10595, USA
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Kiguchi S, Imamura T, Ichikawa K, Kojima M. Oxcarbazepine antinociception in animals with inflammatory pain or painful diabetic neuropathy. Clin Exp Pharmacol Physiol 2004; 31:57-64. [PMID: 14756685 DOI: 10.1111/j.1440-1681.2004.03950.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
1. Diabetic neuropathy is one of the most frequent complications of diabetes mellitus. However, the mechanisms underlying these disorders are not yet well defined and it has been reported that currently available analgesics have hardly any ameliorating effect on painful diabetic neuropathy. 2. The purpose of the present study was to evaluate the antinociceptive effect of oxcarbazepine (OCBZ), a keto derivative of carbamazepine (CBZ), in animal models generally used in pain research and in rats and mice with streptozotocin (STZ)-induced diabetes. In addition, we compared the effect of OCBZ with those of CBZ, mexiletine and morphine. 3. Diabetes was induced by injection of STZ at a dose of 300 mg/kg (i.p.) in mice and 50 mg/kg (i.v.) in rats. Experiments were conducted 2 weeks after STZ injection and those animals with a serum glucose level above 400 mg/dL were used for data analysis. Antinociceptive effects of the drugs were evaluated by the paw withdrawal test (normal, STZ-induced diabetic and carrageenin-injected rats), tail-flick test (normal and STZ-induced diabetic mice) and nociceptive behaviour (formalin-injected mice). 4. In the present study, diabetic mice showed thermal hyperalgesia and diabetic rats exhibited mechanical hyperalgesia. From these results, the STZ-induced diabetic animals used in the present study were found to be suitable for research on painful diabetic neuropathy. In STZ-induced diabetic animals, the antinociceptive effects of OCBZ, CBZ and mexiletine were facilitated, whereas the effect of morphine was attenuated, compared with effects in normal animals. 5. Oxcarbazepine inhibited the formalin-induced biphasic pain responses and increased the nociceptive threshold in the case of carrageenin-induced hyperalgesia. In view of these results, inhibition of substance P-mediated pain transmission may be involved in the antinociceptive action of OCBZ. 6. These results indicate that OCBZ has an analgesic action and is a possible therapeutic agent for the treatment of neuropathic pain, such as occurs in painful diabetic neuropathy.
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Affiliation(s)
- Sumiyoshi Kiguchi
- Pharmacology Research, R&D, Kissei Pharmaceutical Co. Ltd., 4365-1 Kashiwabara, Hotaka, Minamiazumi, Nagano 399-8304, Japan.
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Morairty S, Rainnie D, McCarley R, Greene R. Disinhibition of ventrolateral preoptic area sleep-active neurons by adenosine: a new mechanism for sleep promotion. Neuroscience 2004; 123:451-7. [PMID: 14698752 DOI: 10.1016/j.neuroscience.2003.08.066] [Citation(s) in RCA: 111] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The ventrolateral preoptic area of the hypothalamus (VLPO) contains a population of sleep-active neurons and is hypothesized to be an important part of the somnogenic process. Adenosine (AD) is an endogenous sleep-promoting factor and may play an important role in promoting natural sleep. We hypothesize that AD may promote sleep, in part, by activating the VLPO sleep-active neurons. Although, in the CNS, AD is generally regarded as an inhibitory neuromodulator, it is possible for AD to be directly excitatory via A2 receptors or indirectly via disinhibition. In order to test the hypotheses that AD can excite VLPO neurons we made intracellular recordings from the VLPO in vitro and examined the effects of AD on VLPO neural activity. Whole cell patch-clamp recordings were obtained from rat brain slices and drugs were bath applied. VLPO neurons were electrophysiologically heterogeneous. Depolarizing current steps elicited rhythmic firing (25 of 57), spike frequency adaptation or accommodation (24 of 57), or an unusual burst firing response (eight of 57). Spontaneous synaptic activity was pronounced in most recorded neurons and consisted of either fast excitatory post-synaptic potentials/currents (EPSP/C's) and/or fast inhibitory post-synaptic potentials/currents (IPSP/C's). The IPSC's were fully blocked by 30 microM bicuculline suggesting they are GABA(A)-mediated events, and the EPSC's were blocked by 40 microM DNQX suggesting they are mediated by the AMPA subtype of glutamate receptor (five of five). AD (20-100 microM) reduced the frequency of spontaneous IPSC's in 11 of 17 VLPO neurons (28-100%; mean reduction=63%) without significant effects on resting membrane potential. IPSC was unaffected in five neurons and one neuron displayed increases in spontaneous IPSC's. In contrast, AD decreased EPSC frequency in seven cells (36-73%; mean=59%), increased frequency in five cells (30-236%; mean 83%) and had no effect in six cells. AD application increased the firing rate in two of four cells tested. These data are consistent with the hypothesis that one mechanism which AD may promote sleep is by blocking inhibitory inputs on VLPO sleep-active neurons.
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Kimura M, Saitoh N, Takahashi T. Adenosine A(1) receptor-mediated presynaptic inhibition at the calyx of Held of immature rats. J Physiol 2003; 553:415-26. [PMID: 12963795 PMCID: PMC2343556 DOI: 10.1113/jphysiol.2003.048371] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2003] [Accepted: 09/02/2003] [Indexed: 01/02/2023] Open
Abstract
At the calyx of Held synapse in brainstem slices of 5- to 7-day-old (P5-7) rats, adenosine, or the type 1 adenosine (A1) receptor agonist N6-cyclopentyladenosine (CPA), inhibited excitatory postsynaptic currents (EPSCs) without affecting the amplitude of miniature EPSCs. The A1 receptor antagonist 8-cyclopentyltheophylline (CPT) had no effect on the amplitude of EPSCs evoked at a low frequency, but significantly reduced the magnitude of synaptic depression caused by repetitive stimulation at 10 Hz, suggesting that endogenous adenosine is involved in the regulation of transmitter release. Adenosine inhibited presynaptic Ca(2+) currents (IpCa) recorded directly from calyceal terminals, but had no effect on presynaptic K+ currents. When EPSCs were evoked by IpCa during simultaneous pre- and postsynaptic recordings, the magnitude of the adenosine-induced inhibition of IpCa fully explained that of EPSCs, suggesting that the presynaptic Ca(2+) channel is the main target of A1 receptors. Whereas the N-type Ca(2+) channel blocker omega-conotoxin attenuated EPSCs, it had no effect on the magnitude of adenosine-induced inhibition of EPSCs. During postnatal development, in parallel with a decrease in the A1 receptor immunoreactivity at the calyceal terminal, the inhibitory effect of adenosine became weaker. We conclude that presynaptic A1 receptors at the immature calyx of Held synapse play a regulatory role in transmitter release during high frequency transmission, by inhibiting multiple types of presynaptic Ca(2+) channels.
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MESH Headings
- Adenosine/analogs & derivatives
- Adenosine/pharmacology
- Animals
- Auditory Pathways/chemistry
- Auditory Pathways/growth & development
- Auditory Pathways/physiology
- Baclofen/pharmacology
- Blotting, Western
- Brain Stem/chemistry
- Brain Stem/growth & development
- Brain Stem/physiology
- Calcium/metabolism
- Calcium Channels/drug effects
- Calcium Channels/physiology
- Dose-Response Relationship, Drug
- Excitatory Postsynaptic Potentials/drug effects
- GABA-B Receptor Agonists
- Gene Expression Regulation, Developmental
- Immunohistochemistry
- Neural Inhibition/physiology
- Patch-Clamp Techniques
- Potassium/metabolism
- Potassium Channels/drug effects
- Presynaptic Terminals/drug effects
- Presynaptic Terminals/physiology
- Rats
- Rats, Wistar
- Receptor, Adenosine A1/analysis
- Receptor, Adenosine A1/genetics
- Receptor, Adenosine A1/physiology
- Receptors, Presynaptic/analysis
- Receptors, Presynaptic/genetics
- Receptors, Presynaptic/physiology
- Synaptophysin/analysis
- Tetrodotoxin/pharmacology
- Theophylline/analogs & derivatives
- Theophylline/pharmacology
- omega-Conotoxin GVIA/pharmacology
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Affiliation(s)
- Masahiro Kimura
- Department of Neurophysiology, University of Tokyo Graduate School of Medicine, Tokyo 113-0033, Japan
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44
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Hack SP, Vaughan CW, Christie MJ. Modulation of GABA release during morphine withdrawal in midbrain neurons in vitro. Neuropharmacology 2003; 45:575-84. [PMID: 12941371 DOI: 10.1016/s0028-3908(03)00205-3] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Chronic treatment with opioids induces adaptations in neurons leading to tolerance and dependence. Studies have implicated the midbrain periaqueductal gray (PAG) in the expression of many signs of withdrawal. Patch-clamp recording techniques were used to examine whether augmentation of adenylyl cyclase signalling produces hyperexcitation in GABAergic nerve terminals within the mouse PAG. Both the rate of mIPSCs and the amplitude of evoked IPSCs during naloxone-precipitated withdrawal was profoundly enhanced in chronically morphine treated mice, compared to vehicle treated controls, in the presence but not the absence an adenosine A(1) receptor antagonist DPCPX. Enhanced GABAergic transmission in the presence of DPCPX was abolished by blocking protein kinase A. Inhibitors of cAMP transport, phosphodiesterase and nucleotide transport mimicked the effect of DPCPX. Coupling efficacy of micro-receptors to presynaptic inhibition of GABA release was increased in dependent mice in the presence of DPCPX. The increased coupling efficacy was abolished by blocking protein kinase A, which unmasked an underlying micro-receptor tolerance. These findings indicate that enhanced adenylyl cyclase signalling following chronic morphine treatment produces (1) GABAergic terminal hyperexcitability during withdrawal that is retarded by a concomitant increase in endogenous adenosine, and (2) enhanced micro-receptor coupling to presynaptic inhibition that overcomes an underlying tolerance.
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Affiliation(s)
- Stephen P Hack
- Department of Pharmacology and Pain Management Research Institute, University of Sydney and Royal North Shore Hospital, St Leonards, NSW 2006, Australia.
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45
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Chamberlin NL, Arrigoni E, Chou TC, Scammell TE, Greene RW, Saper CB. Effects of adenosine on gabaergic synaptic inputs to identified ventrolateral preoptic neurons. Neuroscience 2003; 119:913-8. [PMID: 12831851 DOI: 10.1016/s0306-4522(03)00246-x] [Citation(s) in RCA: 97] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The ventrolateral preoptic nucleus (VLPO) is a key regulator of behavioral state that promotes sleep by directly inhibiting brain regions that maintain wakefulness. Subarachnoid administration of adenosine (AD) or AD agonists promotes sleep and induces expression of Fos protein in VLPO neurons. Therefore, activation of VLPO neurons may contribute to the somnogenic actions of AD. To define the mechanism through which AD activates VLPO neurons, we prepared hypothalamic slices from 9 to 12-day-old rat pups and recorded from 43 neurons in the galaninergic VLPO cluster; nine neurons contained galanin mRNA by post hoc in situ hybridization. Bath application of AD (20 microM) to seven of these neurons had no direct effect but caused a significant decrease in the frequency of spontaneous miniature inhibitory postsynaptic currents in the presence of tetrodotoxin, indicating a presynaptic site of action. We conclude that AD-mediated disinhibition increases the excitability of VLPO neurons thus contributing to the somnogenic properties of AD.
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Affiliation(s)
- N L Chamberlin
- Department of Neurology, Beth Israel Deaconess Medical Center, Harvard Institute of Medicine, Room 820, 77 Avenue Louis Pasteur, Boston, MA 02115, USA.
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46
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Vorobjev VS, Sharonova IN, Haas HL, Sergeeva OA. Expression and function of P2X purinoceptors in rat histaminergic neurons. Br J Pharmacol 2003; 138:1013-9. [PMID: 12642404 PMCID: PMC1573743 DOI: 10.1038/sj.bjp.0705144] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
(1) The pharmacology of ATP responses and the expression pattern of seven known subunits of the P2X receptor were investigated in individual histaminergic neurons of the tuberomamillary nucleus (TM). (2) ATP (3-1000 micro M) evoked fast non-desensitizing inward currents in TM neurons. 2-methylthioATP (2MeSATP) displayed the same efficacy but a lower potency, EC(50)s 84 micro M versus 48 micro M, when compared with ATP. Adenosine-diphosphate (ADP), uridine-triphosphate (UTP) and alpha beta methylene-ATP (alphabeta-meATP) were inactive. (3) ATP-mediated whole cell currents were potentiated by acidification of the recording solution (pH 7.5 and 6.6 were compared). (4) Single-cell RT-PCR (scRT-PCR) analysis revealed that the P2X(2) receptor is expressed in all PCR-positive neurons. Each of the P2X(1), P2X(3), P2X(4), P2X(5) and P2X(6) mRNAs were detected in less than 35% of the cells. (5) Suramin antagonized ATP responses with an IC(50) of 4.2 micro M and pyridoxalphosphate-6-azophenyl-2',4'-disulphonic acid (PPADS, 1 micro M) reduced ATP responses to 43% of control, when antagonists were pre-applied 90s before the agonist. Cibacron blue (3 micro M) given together with ATP potentiated control responses by 67%, but inhibited it to 10% after pre-application. (6) 2',3'-O-(2,4,6-Trinitrophenyl) adenosine 5'-triphosphate (TNP-ATP) antagonized ATP responses with an IC(50) of 7 micro M. (7) Pharmacological properties of ATP responses together with scRT-PCR data suggest that P2X(2) is the major purinoceptor on the soma of TM neurons, however the presence of heteromeric P2X(2/5) receptors in some neurons cannot be excluded.
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Affiliation(s)
- Vladimir S Vorobjev
- Department of Neurophysiology, Heinrich-Heine-Universität, POB 101007, D-40001 Düsseldorf, Germany
| | - Irina N Sharonova
- Department of Neurophysiology, Heinrich-Heine-Universität, POB 101007, D-40001 Düsseldorf, Germany
| | - Helmut L Haas
- Department of Neurophysiology, Heinrich-Heine-Universität, POB 101007, D-40001 Düsseldorf, Germany
| | - Olga A Sergeeva
- Department of Neurophysiology, Heinrich-Heine-Universität, POB 101007, D-40001 Düsseldorf, Germany
- Author for correspondence:
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47
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Lu Y, Chung HJ, Li Y, Rosenberg PA. NMDA receptor-mediated extracellular adenosine accumulation in rat forebrain neurons in culture is associated with inhibition of adenosine kinase. Eur J Neurosci 2003; 17:1213-22. [PMID: 12670309 DOI: 10.1046/j.1460-9568.2003.02554.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The effect of N-methyl-d-aspartate (NMDA) on regulation of extracellular adenosine was investigated in rat forebrain neurons in culture. NMDA evoked accumulation of extracellular adenosine with an EC50 value of 4.8 +/- 1.2 microM. The effect of NMDA was blocked by (+)-5-methyl-10,11-dihydro-5H-dibenzo [a, d] cyclohepten-5,10-imine hydrogen maleate indicating that NMDA receptor activation was involved. The NMDA effect was also blocked by chelation of extracellular Ca2+ indicating that influx of calcium was required. The nitric oxide-cyclic GMP signalling pathway was not involved, as nitric oxide synthase inhibitors were unable to block, and cGMP analogs were unable to mimic, the effect of NMDA. The source for extracellular adenosine was likely to be intracellular adenosine as the ecto-5'-nucleotidase inhibitor alpha beta-methylene-ADP was unable to block the effect of NMDA. One possible cause of intracellular adenosine accumulation might be NMDA receptor-mediated inhibition of mitochondrial function and ATP hydrolysis. We found that NMDA caused a concentration dependent depletion of intracellular ATP with an EC50 value of 21 +/- 8 microM. NMDA also caused a significant decrease in adenosine kinase activity, assayed by two different methods. Consistent with the hypothesis that inhibition of adenosine kinase is sufficient to cause an increase in extracellular adenosine, inhibition of adenosine kinase by 5'-iodotubercidin resulted in elevation of extracellular adenosine. However, in the presence of a concentration of 5'-iodotubercidin that inhibited over 90% of adenosine kinase activity, exposure to NMDA still caused adenosine accumulation. These studies suggest that several possible mechanisms are likely to be involved in NMDA-evoked extracellular adenosine accumulation.
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Affiliation(s)
- Yin Lu
- Department of Neurology and Program in Neuroscience, Children's Hospital and Harvard Medical School, Boston, MA 02115, USA
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48
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Kyung Park Y, Jun Jung S, Kwak J, Kim J. Effect of hypoxia on excitatory transmission in the rat substantia gelatinosa neurons. Biochem Biophys Res Commun 2002; 295:929-36. [PMID: 12127984 DOI: 10.1016/s0006-291x(02)00790-8] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
We have investigated the effect of hypoxia on the excitatory synaptic transmission in the substantia gelatinosa neurons using perforated-patch-clamp configuration. Brief periods of hypoxia induced a depression in the evoked excitatory postsynaptic current (eEPSC) amplitude. The hypoxia-induced depression of eEPSC was not observed in the presence of theophylline, a nonselective adenosine receptor antagonist, and DPCPX, a selective adenosine receptor A1 antagonist. Application of adenosine (100 microM) also depressed eEPSC in a similar way as with hypoxia. This adenosine-induced depression of eEPSC was inhibited by DPCPX. Hypoxia and exogenous adenosine decreased the frequency of the spontaneous excitatory postsynaptic current (sEPSC) but not the amplitude of sEPSC and increased the paired-pulse ratio. From these results, it is suggested that acute hypoxia depresses the excitatory synaptic transmission by activating the presynaptic adenosine A1 receptor.
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Affiliation(s)
- Yun Kyung Park
- Department of Physiology and Biophysics, Seoul National University College of Medicine, 28 Yongon-dong, Chongno-gu, Seoul, Republic of Korea
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49
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Abstract
Adenosine is a putative sleep factor with effects mainly mediated by the A1 receptor. Recent studies have implicated the hypothalamic orexin/hypocretin-containing neurons in the control of sleep-wakefulness. To help determine if adenosine might play a role in the control of orexin neurons, immunohistochemistry was used to characterize the distribution of adenosine A1 receptor protein on the orexinergic neurons. About 30% of orexin-containing neurons were labeled. The data supports the presence of adenosine A1 receptors on orexinergic neurons and suggests a possible substrate for a functional role of adenosine in the regulation of orexinergic activity.
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Affiliation(s)
- Mahesh M Thakkar
- Department of Psychiatry, Harvard Medical School, VA Boston Healthcare System, Brockton VA Medical Center, Brockton, MA, USA.
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