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Sample records for adenosine receptor dampens

  1. Adenosine Receptors and Wound Healing

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    Bruce N. Cronstein

    2004-01-01

    Full Text Available Recent studies have demonstrated that application of topical adenosine A2A receptor agonists promotes more rapid wound closure and clinical studies are currently underway to determine the utility of topical A2A adenosine receptor agonists in the therapy of diabetic foot ulcers. The effects of adenosine A2A receptors on the cells and tissues of healing wounds have only recently been explored. We review here the known effects of adenosine A2A receptor occupancy on the cells involved in wound healing.

  2. Adenosine receptor desensitization and trafficking.

    Science.gov (United States)

    Mundell, Stuart; Kelly, Eamonn

    2011-05-01

    As with the majority of G-protein-coupled receptors, all four of the adenosine receptor subtypes are known to undergo agonist-induced regulation in the form of desensitization and trafficking. These processes can limit the ability of adenosine receptors to couple to intracellular signalling pathways and thus reduce the ability of adenosine receptor agonists as well as endogenous adenosine to produce cellular responses. In addition, since adenosine receptors couple to multiple signalling pathways, these pathways may desensitize differentially, while the desensitization of one pathway could even trigger signalling via another. Thus, the overall picture of adenosine receptor regulation can be complex. For all adenosine receptor subtypes, there is evidence to implicate arrestins in agonist-induced desensitization and trafficking, but there is also evidence for other possible forms of regulation, including second messenger-dependent kinase regulation, heterologous effects involving G proteins, and the involvement of non-clathrin trafficking pathways such as caveolae. In this review, the evidence implicating these mechanisms is summarized for each adenosine receptor subtype, and we also discuss those issues of adenosine receptor regulation that remain to be resolved as well as likely directions for future research in this field. Copyright © 2010 Elsevier B.V. All rights reserved.

  3. Role of adenosine receptors in caffeine tolerance

    Energy Technology Data Exchange (ETDEWEB)

    Holtzman, S.G.; Mante, S.; Minneman, K.P. (Emory Univ. School of Medicine, Atlanta, GA (USA))

    1991-01-01

    Caffeine is a competitive antagonist at adenosine receptors. Receptor up-regulation during chronic drug treatment has been proposed to be the mechanism of tolerance to the behavioral stimulant effects of caffeine. This study reassessed the role of adenosine receptors in caffeine tolerance. Separate groups of rats were given scheduled access to drinking bottles containing plain tap water or a 0.1% solution of caffeine. Daily drug intake averaged 60-75 mg/kg and resulted in complete tolerance to caffeine-induced stimulation of locomotor activity, which could not be surmounted by increasing the dose of caffeine. 5'-N-ethylcarboxamidoadenosine (0.001-1.0 mg/kg) dose dependently decreased the locomotor activity of caffeine-tolerant rats and their water-treated controls but was 8-fold more potent in the latter group. Caffeine (1.0-10 mg/kg) injected concurrently with 5-N-ethylcarboxamidoadenosine antagonized the decreases in locomotor activity comparably in both groups. Apparent pA2 values for tolerant and control rats also were comparable: 5.05 and 5.11. Thus, the adenosine-antagonist activity of caffeine was undiminished in tolerant rats. The effects of chronic caffeine administration on parameters of adenosine receptor binding and function were measured in cerebral cortex. There were no differences between brain tissue from control and caffeine-treated rats in number and affinity of adenosine binding sites or in receptor-mediated increases (A2 adenosine receptor) and decreases (A1 adenosine receptor) in cAMP accumulation. These results are consistent with theoretical arguments that changes in receptor density should not affect the potency of a competitive antagonist. Experimental evidence and theoretical considerations indicate that up-regulation of adenosine receptors is not the mechanism of tolerance to caffeine-induced stimulation of locomotor activity.

  4. Role of adenosine receptors in caffeine tolerance

    International Nuclear Information System (INIS)

    Holtzman, S.G.; Mante, S.; Minneman, K.P.

    1991-01-01

    Caffeine is a competitive antagonist at adenosine receptors. Receptor up-regulation during chronic drug treatment has been proposed to be the mechanism of tolerance to the behavioral stimulant effects of caffeine. This study reassessed the role of adenosine receptors in caffeine tolerance. Separate groups of rats were given scheduled access to drinking bottles containing plain tap water or a 0.1% solution of caffeine. Daily drug intake averaged 60-75 mg/kg and resulted in complete tolerance to caffeine-induced stimulation of locomotor activity, which could not be surmounted by increasing the dose of caffeine. 5'-N-ethylcarboxamidoadenosine (0.001-1.0 mg/kg) dose dependently decreased the locomotor activity of caffeine-tolerant rats and their water-treated controls but was 8-fold more potent in the latter group. Caffeine (1.0-10 mg/kg) injected concurrently with 5-N-ethylcarboxamidoadenosine antagonized the decreases in locomotor activity comparably in both groups. Apparent pA2 values for tolerant and control rats also were comparable: 5.05 and 5.11. Thus, the adenosine-antagonist activity of caffeine was undiminished in tolerant rats. The effects of chronic caffeine administration on parameters of adenosine receptor binding and function were measured in cerebral cortex. There were no differences between brain tissue from control and caffeine-treated rats in number and affinity of adenosine binding sites or in receptor-mediated increases (A2 adenosine receptor) and decreases (A1 adenosine receptor) in cAMP accumulation. These results are consistent with theoretical arguments that changes in receptor density should not affect the potency of a competitive antagonist. Experimental evidence and theoretical considerations indicate that up-regulation of adenosine receptors is not the mechanism of tolerance to caffeine-induced stimulation of locomotor activity

  5. Structural Mapping of Adenosine Receptor Mutations

    DEFF Research Database (Denmark)

    Jespers, Willem; Schiedel, Anke C; Heitman, Laura H

    2018-01-01

    The four adenosine receptors (ARs), A1, A2A, A2B, and A3, constitute a subfamily of G protein-coupled receptors (GPCRs) with exceptional foundations for structure-based ligand design. The vast amount of mutagenesis data, accumulated in the literature since the 1990s, has been recently supplemente...

  6. Partial separation of platelet and placental adenosine receptors from adenosine A2-like binding protein

    International Nuclear Information System (INIS)

    Zolnierowicz, S.; Work, C.; Hutchison, K.; Fox, I.H.

    1990-01-01

    The ubiquitous adenosine A2-like binding protein obscures the binding properties of adenosine receptors assayed with 5'-N-[ 3 H]ethylcarboxamidoadenosine [( 3 H]NECA). To solve this problem, we developed a rapid and simple method to separate adenosine receptors from the adenosine A2-like binding protein. Human platelet and placental membranes were solubilized with 1% 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate. The soluble platelet extract was precipitated with polyethylene glycol and the fraction enriched in adenosine receptors was isolated from the precipitate by differential centrifugation. The adenosine A2-like binding protein was removed from the soluble placental extract with hydroxylapatite and adenosine receptors were precipitated with polyethylene glycol. The specificity of the [ 3 H]NECA binding is typical of an adenosine A2 receptor for platelets and an adenosine A1 receptor for placenta. This method leads to enrichment of adenosine A2 receptors for platelets and adenosine A1 receptors for placenta. This provides a useful preparation technique for pharmacologic studies of adenosine receptors

  7. Involvement of A1 adenosine receptors and neural pathways in adenosine-induced bronchoconstriction in mice.

    Science.gov (United States)

    Hua, Xiaoyang; Erikson, Christopher J; Chason, Kelly D; Rosebrock, Craig N; Deshpande, Deepak A; Penn, Raymond B; Tilley, Stephen L

    2007-07-01

    High levels of adenosine can be measured from the lungs of asthmatics, and it is well recognized that aerosolized 5'AMP, the precursor of adenosine, elicits robust bronchoconstriction in patients with this disease. Characterization of mice with elevated adenosine levels secondary to the loss of adenosine deaminase (ADA) expression, the primary metabolic enzyme for adenosine, further support a role for this ubiquitous mediator in the pathogenesis of asthma. To begin to identify pathways by which adenosine can alter airway tone, we examined adenosine-induced bronchoconstriction in four mouse lines, each lacking one of the receptors for this nucleoside. We show, using direct measures of airway mechanics, that adenosine can increase airway resistance and that this increase in resistance is mediated by binding the A(1) receptor. Further examination of this response using pharmacologically, surgically, and genetically manipulated mice supports a model in which adenosine-induced bronchoconstriction occurs indirectly through the activation of sensory neurons.

  8. Amyotrophic Lateral Sclerosis (ALS and Adenosine Receptors

    Directory of Open Access Journals (Sweden)

    Ana M. Sebastião

    2018-04-01

    Full Text Available In the present review we discuss the potential involvement of adenosinergic signaling, in particular the role of adenosine receptors, in amyotrophic lateral sclerosis (ALS. Though the literature on this topic is not abundant, the information so far available on adenosine receptors in animal models of ALS highlights the interest to continue to explore the role of these receptors in this neurodegenerative disease. Indeed, all motor neurons affected in ALS are responsive to adenosine receptor ligands but interestingly, there are alterations in pre-symptomatic or early symptomatic stages that mirror those in advanced disease stages. Information starts to emerge pointing toward a beneficial role of A2A receptors (A2AR, most probably at early disease states, and a detrimental role of caffeine, in clear contrast with what occurs in other neurodegenerative diseases. However, some evidence also exists on a beneficial action of A2AR antagonists. It may happen that there are time windows where A2AR prove beneficial and others where their blockade is required. Furthermore, the same changes may not occur simultaneously at the different synapses. In line with this, it is not fully understood if ALS is a dying back disease or if it propagates in a centrifugal way. It thus seems crucial to understand how motor neuron dysfunction occurs, how adenosine receptors are involved in those dysfunctions and whether the early changes in purinergic signaling are compensatory or triggers for the disease. Getting this information is crucial before starting the design of purinergic based strategies to halt or delay disease progression.

  9. Characteristic molecular vibrations of adenosine receptor ligands.

    Science.gov (United States)

    Chee, Hyun Keun; Yang, Jin-San; Joung, Je-Gun; Zhang, Byoung-Tak; Oh, S June

    2015-02-13

    Although the regulation of membrane receptor activation is known to be crucial for molecular signal transduction, the molecular mechanism underlying receptor activation is not fully elucidated. Here we study the physicochemical nature of membrane receptor behavior by investigating the characteristic molecular vibrations of receptor ligands using computational chemistry and informatics methods. By using information gain, t-tests, and support vector machines, we have identified highly informative features of adenosine receptor (AdoR) ligand and corresponding functional amino acid residues such as Asn (6.55) of AdoR that has informative significance and is indispensable for ligand recognition of AdoRs. These findings may provide new perspectives and insights into the fundamental mechanism of class A G protein-coupled receptor activation. Copyright © 2015 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.

  10. AMP is an adenosine A1 receptor agonist.

    Science.gov (United States)

    Rittiner, Joseph E; Korboukh, Ilia; Hull-Ryde, Emily A; Jin, Jian; Janzen, William P; Frye, Stephen V; Zylka, Mark J

    2012-02-17

    Numerous receptors for ATP, ADP, and adenosine exist; however, it is currently unknown whether a receptor for the related nucleotide adenosine 5'-monophosphate (AMP) exists. Using a novel cell-based assay to visualize adenosine receptor activation in real time, we found that AMP and a non-hydrolyzable AMP analog (deoxyadenosine 5'-monophosphonate, ACP) directly activated the adenosine A(1) receptor (A(1)R). In contrast, AMP only activated the adenosine A(2B) receptor (A(2B)R) after hydrolysis to adenosine by ecto-5'-nucleotidase (NT5E, CD73) or prostatic acid phosphatase (PAP, ACPP). Adenosine and AMP were equipotent human A(1)R agonists in our real-time assay and in a cAMP accumulation assay. ACP also depressed cAMP levels in mouse cortical neurons through activation of endogenous A(1)R. Non-selective purinergic receptor antagonists (pyridoxalphosphate-6-azophenyl-2',4'-disulfonic acid and suramin) did not block adenosine- or AMP-evoked activation. Moreover, mutation of His-251 in the human A(1)R ligand binding pocket reduced AMP potency without affecting adenosine potency. In contrast, mutation of a different binding pocket residue (His-278) eliminated responses to AMP and to adenosine. Taken together, our study indicates that the physiologically relevant nucleotide AMP is a full agonist of A(1)R. In addition, our study suggests that some of the physiological effects of AMP may be direct, and not indirect through ectonucleotidases that hydrolyze this nucleotide to adenosine.

  11. AMP Is an Adenosine A1 Receptor Agonist*

    Science.gov (United States)

    Rittiner, Joseph E.; Korboukh, Ilia; Hull-Ryde, Emily A.; Jin, Jian; Janzen, William P.; Frye, Stephen V.; Zylka, Mark J.

    2012-01-01

    Numerous receptors for ATP, ADP, and adenosine exist; however, it is currently unknown whether a receptor for the related nucleotide adenosine 5′-monophosphate (AMP) exists. Using a novel cell-based assay to visualize adenosine receptor activation in real time, we found that AMP and a non-hydrolyzable AMP analog (deoxyadenosine 5′-monophosphonate, ACP) directly activated the adenosine A1 receptor (A1R). In contrast, AMP only activated the adenosine A2B receptor (A2BR) after hydrolysis to adenosine by ecto-5′-nucleotidase (NT5E, CD73) or prostatic acid phosphatase (PAP, ACPP). Adenosine and AMP were equipotent human A1R agonists in our real-time assay and in a cAMP accumulation assay. ACP also depressed cAMP levels in mouse cortical neurons through activation of endogenous A1R. Non-selective purinergic receptor antagonists (pyridoxalphosphate-6-azophenyl-2′,4′-disulfonic acid and suramin) did not block adenosine- or AMP-evoked activation. Moreover, mutation of His-251 in the human A1R ligand binding pocket reduced AMP potency without affecting adenosine potency. In contrast, mutation of a different binding pocket residue (His-278) eliminated responses to AMP and to adenosine. Taken together, our study indicates that the physiologically relevant nucleotide AMP is a full agonist of A1R. In addition, our study suggests that some of the physiological effects of AMP may be direct, and not indirect through ectonucleotidases that hydrolyze this nucleotide to adenosine. PMID:22215671

  12. A2A adenosine receptor ligand binding and signalling is allosterically modulated by adenosine deaminase.

    Science.gov (United States)

    Gracia, Eduard; Pérez-Capote, Kamil; Moreno, Estefanía; Barkešová, Jana; Mallol, Josefa; Lluís, Carme; Franco, Rafael; Cortés, Antoni; Casadó, Vicent; Canela, Enric I

    2011-05-01

    A2ARs (adenosine A2A receptors) are highly enriched in the striatum, which is the main motor control CNS (central nervous system) area. BRET (bioluminescence resonance energy transfer) assays showed that A2AR homomers may act as cell-surface ADA (adenosine deaminase; EC 3.5.4.4)-binding proteins. ADA binding affected the quaternary structure of A2ARs present on the cell surface. ADA binding to adenosine A2ARs increased both agonist and antagonist affinity on ligand binding to striatal membranes where these proteins are co-expressed. ADA also increased receptor-mediated ERK1/2 (extracellular-signal-regulated kinase 1/2) phosphorylation. Collectively, the results of the present study show that ADA, apart from regulating the concentration of extracellular adenosine, may behave as an allosteric modulator that markedly enhances ligand affinity and receptor function. This powerful regulation may have implications for the physiology and pharmacology of neuronal A2ARs.

  13. Adenosine receptors and caffeine in retinopathy of prematurity.

    Science.gov (United States)

    Chen, Jiang-Fan; Zhang, Shuya; Zhou, Rong; Lin, Zhenlang; Cai, Xiaohong; Lin, Jing; Huo, Yuqing; Liu, Xiaoling

    2017-06-01

    Retinopathy of prematurity (ROP) is a major cause of childhood blindness in the world and is caused by oxygen-induced damage to the developing retinal vasculature, resulting in hyperoxia-induced vaso-obliteration and subsequent delayed retinal vascularization and hypoxia-induced pathological neovascularization driven by vascular endothelial growth factor (VEGF) signaling pathway in retina. Current anti-VEGF therapy has shown some effective in a clinical trial, but is associated with the unintended effects on delayed eye growth and retinal vasculature development of preterm infants. Notably, cellular responses to hypoxia are characterized by robust increases in extracellular adenosine production and the markedly induced adenosine receptors, which provide a novel target for preferential control of pathological angiogenesis without affecting normal vascular development. Here, we review the experimental evidence in support of adenosine receptor-based therapeutic strategy for ROP, including the aberrant adenosine signaling in oxygen-induced retinopathy and the role of three adenosine receptor subtypes (A 1 R, A 2A R, A 2B R) in development and treatment of ROP using oxygen-induced retinopathy models. The clinical and initial animal evidence that implicate the therapeutic effect of caffeine (a non-selective adenosine receptor antagonist) in treatment of ROP are highlighted. Lastly, we discussed the translational potential as well therapeutic advantage of adenosine receptor- and caffeine-based therapy for ROR and possibly other proliferative retinopathy. Copyright © 2017 Elsevier Ltd. All rights reserved.

  14. Synthesis of carbon-11 labelled cyclopentyltheophylline: A radioligand for PET studies of adenosine receptors

    International Nuclear Information System (INIS)

    Yorke, J.C.; Prenant, C.; Crouzel, C.

    1990-01-01

    Adenosine is presently considered as a neuromodulator, and an adenosine system has been described including secretory neurons, with a diffused distribution, specific receptors and a re-uptake system distributed heterogeneously in different anatomic areas. In order to localize the adenosine receptors in vivo by PET, the authors have synthesized the carbon-11 labelled 8-cyclopentyltheophylline, a known adenosine antagonist of A 1 receptors

  15. Adenosine Receptor Heteromers and their Integrative Role in Striatal Function

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    Sergi Ferré

    2007-01-01

    Full Text Available By analyzing the functional role of adenosine receptor heteromers, we review a series of new concepts that should modify our classical views of neurotransmission in the central nervous system (CNS. Neurotransmitter receptors cannot be considered as single functional units anymore. Heteromerization of neurotransmitter receptors confers functional entities that possess different biochemical characteristics with respect to the individual components of the heteromer. Some of these characteristics can be used as a “biochemical fingerprint” to identify neurotransmitter receptor heteromers in the CNS. This is exemplified by changes in binding characteristics that are dependent on coactivation of the receptor units of different adenosine receptor heteromers. Neurotransmitter receptor heteromers can act as “processors” of computations that modulate cell signaling, sometimes critically involved in the control of pre- and postsynaptic neurotransmission. For instance, the adenosine A1-A2A receptor heteromer acts as a concentration-dependent switch that controls striatal glutamatergic neurotransmission. Neurotransmitter receptor heteromers play a particularly important integrative role in the “local module” (the minimal portion of one or more neurons and/or one or more glial cells that operates as an independent integrative unit, where they act as processors mediating computations that convey information from diverse volume-transmitted signals. For instance, the adenosine A2A-dopamine D2 receptor heteromers work as integrators of two different neurotransmitters in the striatal spine module.

  16. Activation of Adenylyl Cyclase Causes Stimulation of Adenosine Receptors

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    Thomas Pleli

    2018-03-01

    Full Text Available Background/Aims: Signaling of Gs protein-coupled receptors (GsPCRs is accomplished by stimulation of adenylyl cyclase, causing an increase of the intracellular cAMP concentration, activation of the intracellular cAMP effectors protein kinase A (PKA and Epac, and an efflux of cAMP, the function of which is still unclear. Methods: Activation of adenylyl cyclase by GsPCR agonists or cholera toxin was monitored by measurement of the intracellular cAMP concentration by ELISA, anti-phospho-PKA substrate motif phosphorylation by immunoblotting, and an Epac-FRET assay in the presence and absence of adenosine receptor antagonists or ecto-nucleotide phosphodiesterase/pyrophosphatase2 (eNPP2 inhibitors. The production of AMP from cAMP by recombinant eNPP2 was measured by HPLC. Extracellular adenosine was determined by LC-MS/MS, extracellular ATP by luciferase and LC-MS/MS. The expression of eNPP isoenzymes 1-3 was examined by RT-PCR. The expression of multidrug resistance protein 4 was suppressed by siRNA. Results: Here we show that the activation of GsPCRs and the GsPCRs-independent activation of Gs proteins and adenylyl cyclase by cholera toxin induce stimulation of cell surface adenosine receptors (A2A or A2B adenosine receptors. In PC12 cells stimulation of adenylyl cyclase by GsPCR or cholera toxin caused activation of A2A adenosine receptors by an autocrine signaling pathway involving cAMP efflux through multidrug resistance protein 4 and hydrolysis of released cAMP to AMP by eNPP2. In contrast, in PC3 cells cholera toxin- and GsPCR-induced stimulation of adenylyl cyclase resulted in the activation of A2B adenosine receptors. Conclusion: Our findings show that stimulation of adenylyl cyclase causes a remarkable activation of cell surface adenosine receptors.

  17. Mechanism of A2 adenosine receptor activation. I. Blockade of A2 adenosine receptors by photoaffinity labeling

    International Nuclear Information System (INIS)

    Lohse, M.J.; Klotz, K.N.; Schwabe, U.

    1991-01-01

    It has previously been shown that covalent incorporation of the photoreactive adenosine derivative (R)-2-azido-N6-p-hydroxy-phenylisopropyladenosine [(R)-AHPIA] into the A1 adenosine receptor of intact fat cells leads to a persistent activation of this receptor, resulting in a reduction of cellular cAMP levels. In contrast, covalent incorporation of (R)-AHPIA into human platelet membranes, which contain only stimulatory A2 adenosine receptors, reduces adenylate cyclase stimulation via these receptors. This effect of (R)-AHPIA is specific for the A2 receptor and can be prevented by the adenosine receptor antagonist theophylline. Binding studies indicate that up to 90% of A2 receptors can be blocked by photoincorporation of (R)-AHPIA. However, the remaining 10-20% of A2 receptors are sufficient to mediate an adenylate cyclase stimulation of up to 50% of the control value. Similarly, the activation via these 10-20% of receptors occurs with a half-life that is only 2 times longer than that in control membranes. This indicates the presence of a receptor reserve, with respect to both the extent and the rate of adenylate cyclase stimulation. These observations require a modification of the models of receptor-adenylate cyclase coupling

  18. N6-(2-Hydroxyethyl)-Adenosine Exhibits Insecticidal Activity against Plutella xylostella via Adenosine Receptors.

    Science.gov (United States)

    Fang, Ming; Chai, Yiqiu; Chen, Guanjv; Wang, Huidong; Huang, Bo

    The diamondback moth, Plutella xylostella, is one of the most important pests of cruciferous crops. We have earlier shown that N6-(2-hydroxyethyl)-adenosine (HEA) exhibits insecticidal activity against P. xylostella. In the present study we investigated the possible mechanism of insecticidal action of HEA on P. xylostella. HEA is a derivative of adenosine, therefore, we speculated whether it acts via P. xylostella adenosine receptor (PxAdoR). We used RNAi approach to silence PxAdoR gene and used antagonist of denosine receptor (AdoR) to study the insecticidal effect of HEA. We cloned the whole sequence of PxAdoR gene. A BLAST search using NCBI protein database showed a 61% identity with the Drosophila adenosine receptor (DmAdoR) and a 32-35% identity with human AdoR. Though the amino acids sequence of PxAdoR was different compared to other adenosine receptors, most of the amino acids that are known to be important for adenosine receptor ligand binding and signaling were present. However, only 30% binding sites key residues was similar between PxAdoR and A1R. HEA, at a dose of 1 mg/mL, was found to be lethal to the second-instar larvae of P. xylostella, and a significant reduction of mortality and growth inhibition ratio were obtained when HEA was administered to the larvae along with PxAdoR-dsRNA or antagonist of AdoR (SCH58261) for 36, 48, or 60 h. Especially at 48 h, the rate of growth inhibition of the PxAdoR knockdown group was 3.5-fold less than that of the HEA group, and the corrected mortality of SCH58261 group was reduced almost 2-fold compared with the HEA group. Our findings show that HEA may exert its insecticidal activity against P. xylostella larvae via acting on PxAdoR.

  19. N6-(2-Hydroxyethyl)-Adenosine Exhibits Insecticidal Activity against Plutella xylostella via Adenosine Receptors

    Science.gov (United States)

    Fang, Ming; Chai, Yiqiu; Chen, Guanjv; Wang, Huidong; Huang, Bo

    2016-01-01

    The diamondback moth, Plutella xylostella, is one of the most important pests of cruciferous crops. We have earlier shown that N6-(2-hydroxyethyl)-adenosine (HEA) exhibits insecticidal activity against P. xylostella. In the present study we investigated the possible mechanism of insecticidal action of HEA on P. xylostella. HEA is a derivative of adenosine, therefore, we speculated whether it acts via P. xylostella adenosine receptor (PxAdoR). We used RNAi approach to silence PxAdoR gene and used antagonist of denosine receptor (AdoR) to study the insecticidal effect of HEA. We cloned the whole sequence of PxAdoR gene. A BLAST search using NCBI protein database showed a 61% identity with the Drosophila adenosine receptor (DmAdoR) and a 32–35% identity with human AdoR. Though the amino acids sequence of PxAdoR was different compared to other adenosine receptors, most of the amino acids that are known to be important for adenosine receptor ligand binding and signaling were present. However, only 30% binding sites key residues was similar between PxAdoR and A1R. HEA, at a dose of 1 mg/mL, was found to be lethal to the second-instar larvae of P. xylostella, and a significant reduction of mortality and growth inhibition ratio were obtained when HEA was administered to the larvae along with PxAdoR-dsRNA or antagonist of AdoR (SCH58261) for 36, 48, or 60 h. Especially at 48 h, the rate of growth inhibition of the PxAdoR knockdown group was 3.5-fold less than that of the HEA group, and the corrected mortality of SCH58261 group was reduced almost 2-fold compared with the HEA group. Our findings show that HEA may exert its insecticidal activity against P. xylostella larvae via acting on PxAdoR. PMID:27668428

  20. AMP and adenosine are both ligands for adenosine 2B receptor signaling.

    Science.gov (United States)

    Holien, Jessica K; Seibt, Benjamin; Roberts, Veena; Salvaris, Evelyn; Parker, Michael W; Cowan, Peter J; Dwyer, Karen M

    2018-01-15

    Adenosine is considered the canonical ligand for the adenosine 2B receptor (A 2B R). A 2B R is upregulated following kidney ischemia augmenting post ischemic blood flow and limiting tubular injury. In this context the beneficial effect of A 2B R signaling has been attributed to an increase in the pericellular concentration of adenosine. However, following renal ischemia both kidney adenosine monophosphate (AMP) and adenosine levels are substantially increased. Using computational modeling and calcium mobilization assays, we investigated whether AMP could also be a ligand for A 2B R. The computational modeling suggested that AMP interacts with more favorable energy to A 2B R compared with adenosine. Furthermore, AMPαS, a non-hydrolyzable form of AMP, increased calcium uptake by Chinese hamster ovary (CHO) cells expressing the human A 2B R, indicating preferential signaling via the G q pathway. Therefore, a putative AMP-A 2B R interaction is supported by the computational modeling data and the biological results suggest this interaction involves preferential G q activation. These data provide further insights into the role of purinergic signaling in the pathophysiology of renal IRI. Copyright © 2017 Elsevier Ltd. All rights reserved.

  1. The role of glial adenosine receptors in neural resilience and the neurobiology of mood disorders

    NARCIS (Netherlands)

    Calker, D; Biber, K

    2005-01-01

    Adenosine receptors were classified into A(1)- and A(2)-receptors in the laboratory of Bernd Hamprecht more than 25 years ago. Adenosine receptors are instrumental to the neurotrophic effects of glia cells. Both microglia and astrocytes release after stimulation via adenosine receptors factors that

  2. Caffeine, Adenosine Receptors and Estrogen in Toxin Models of Parkinson's Disease

    National Research Council Canada - National Science Library

    Schwarzschild, Michael A; Xu, Kui

    2008-01-01

    ...) that are leading candidate modulators of PD risk. In Year 4 we have obtained and reported evidence that the adenosine receptor blocker caffeine as well as specific genetic depletion of the A2A subtype of adenosine receptor...

  3. DMPD: Shaping of monocyte and macrophage function by adenosine receptors. [Dynamic Macrophage Pathway CSML Database

    Lifescience Database Archive (English)

    Full Text Available 17056121 Shaping of monocyte and macrophage function by adenosine receptors. Hasko ...tml) (.csml) Show Shaping of monocyte and macrophage function by adenosine receptors. PubmedID 17056121 Titl...e Shaping of monocyte and macrophage function by adenosine receptors. Authors Has

  4. PET imaging of adenosine A2A receptors

    NARCIS (Netherlands)

    Zhou, Xiaoyun

    2017-01-01

    This thesis describes the development and evaluation of [11C]preladenant as a novel radioligand for in vivo imaging of adenosine A2A receptors in the brain with positron-emission tomography (PET). The 11C-labeled drug [11C]preladenant was produced with high radiochemical yield and specific activity.

  5. Cerebral adenosine A1 receptors are upregulated in rodent encephalitis

    NARCIS (Netherlands)

    Paul, Souman; Khanapur, Shivashankar; Boersma, Wytske; Sijbesma, Jurgen W.; Ishiwata, Kiichi; Elsinga, Philip H.; Meerlo, Peter; Doorduin, Janine; Dierckx, Rudi A.; van Waarde, Aren

    2014-01-01

    Adenosine A(1) receptors (A(1) Rs) are implied in the modulation of neuroinflammation. Activation of cerebral A(1) Rs acts as a brake on the microglial response after traumatic brain injury and has neuroprotective properties in animal models of Parkinson's disease and multiple sclerosis.

  6. The role of adenosine receptor agonists in regulation of hematopoiesis

    Czech Academy of Sciences Publication Activity Database

    Hofer, Michal; Pospíšil, Milan; Weiterová, Lenka; Hoferová, Zuzana

    2011-01-01

    Roč. 16, č. 1 (2011), s. 675-685 ISSN 1420-3049 R&D Projects: GA MO OVBIOFYZ20101; GA ČR(CZ) GA305/08/0158 Institutional research plan: CEZ:AV0Z50040507; CEZ:AV0Z50040702 Keywords : adenosine receptors * hematopoiesis * myelosuppression Subject RIV: BO - Biophysics Impact factor: 2.386, year: 2011

  7. The Role of Adenosine Receptors in Psychostimulant Addiction

    Directory of Open Access Journals (Sweden)

    Inmaculada Ballesteros-Yáñez

    2018-01-01

    Full Text Available Adenosine receptors (AR are a family of G-protein coupled receptors, comprised of four members, named A1, A2A, A2B, and A3 receptors, found widely distributed in almost all human body tissues and organs. To date, they are known to participate in a large variety of physiopathological responses, which include vasodilation, pain, and inflammation. In particular, in the central nervous system (CNS, adenosine acts as a neuromodulator, exerting different functions depending on the type of AR and consequent cellular signaling involved. In terms of molecular pathways and second messengers involved, A1 and A3 receptors inhibit adenylyl cyclase (AC, through Gi/o proteins, while A2A and A2B receptors stimulate it through Gs proteins. In the CNS, A1 receptors are widely distributed in the cortex, hippocampus, and cerebellum, A2A receptors are localized mainly in the striatum and olfactory bulb, while A2B and A3 receptors are found at low levels of expression. In addition, AR are able to form heteromers, both among themselves (e.g., A1/A2A, as well as with other subtypes (e.g., A2A/D2, opening a whole range of possibilities in the field of the pharmacology of AR. Nowadays, we know that adenosine, by acting on adenosine A1 and A2A receptors, is known to antagonistically modulate dopaminergic neurotransmission and therefore reward systems, being A1 receptors colocalized in heteromeric complexes with D1 receptors, and A2A receptors with D2 receptors. This review documents the present state of knowledge of the contribution of AR, particularly A1 and A2A, to psychostimulants-mediated effects, including locomotor activity, discrimination, seeking and reward, and discuss their therapeutic relevance to psychostimulant addiction. Studies presented in this review reinforce the potential of A1 agonists as an effective strategy to counteract psychostimulant-induced effects. Furthermore, different experimental data support the hypothesis that A2A/D2 heterodimers are

  8. Characterization of cardiac adenosine receptors using N6-phenyladenosines and a new radioligand, [125I]-(m-aminophenyl)adenosine

    International Nuclear Information System (INIS)

    Kwatra, M.M.; Hosey, M.M.; Green, R.

    1986-01-01

    The chick heart contains adenosine receptors with characteristics similar to the R adenosine receptors found in the CNS. They have synthesized several N 6 -phenyladenosines and tested their potencies for inhibiting the binding of [ 125 I](p-aminobenzyl)adenosine {[ 125 I]ABA) to chick heart membranes. Of the 12 compounds tested, N 6 -(p-aminobenzyl) adenosine (ABA) was the least potent (IC 50 ∼ 40 nM) while N 6 -(m-nitrophenyl)adenosine(MNPA) was the most potent (IC 50 ∼ 1 nM). The IC 50 of N 6 -(m-aminophenyl)adenosine(MAPA) was greater than that of N 6 -phenyladenosine(PA) while that of MNPA was less than that of PA. The effects of these electron-releasing (-NH 2 ) and electron-withdrawing (-NO 2 ) groups along with data obtained with other phenyl-substituted N 6 -phenyladenosines suggest that the electron density of the N 6 -nitrogen may affect the affinities of these compounds for the cardiac adenosine receptor. MAPA can be iodinated to produce a new ligand, [ 125 I]MAPA. This iodination, like that of ABA, increases the affinity of the compound and produces a ligand with good affinity and low nonspecific binding suitable for studies on tissues with low concentrations of adenosine receptors

  9. Adenosine receptor modulation of seizure susceptibility in rats

    International Nuclear Information System (INIS)

    Szot, P.

    1987-01-01

    Adenosine is considered to be a neuromodulator or cotransmitter in the periphery and CNS. This neuromodulatory action of adenosine may be observed as an anticonvulsant effect. Dose-response curves for R-phenylisopropyladenosine (PIA), cycohexyladenosine (CHA), 2-chloroadenosine (2-ClAdo), N-ethylcarboxamidoadenosine (NECA) and S-PIA were generated against PTZ seizure thresholds in the rat. The rank order of potency for adenosine agonists to elevate PTZ seizure threshold was R-PIA > 2-ClAdo > NECA > CHA > S-PIA. R-PIA was approximately 80-fold more potent than S-PIA. This 80-fold difference in potency between the diasteriomers of PIA was consistent with an A 1 adenoise receptor-mediated response. The anticonvulsant action of 2-ClAdo was reversed by pretreatment with theoplylline. Chronic administration of theophylline significantly increased the specific binding of 3 H-cyclohexyladenosine in membranes of the cerebral cortex and cerebellum of the rat. Chronic exposure to theophylline produced a significant increase in the densities of both the high- and low-affinity forms of A 1 adenosine receptors in the cerebral cortex

  10. Molecular Evidence of Adenosine Deaminase Linking Adenosine A2A Receptor and CD26 Proteins.

    Science.gov (United States)

    Moreno, Estefanía; Canet, Júlia; Gracia, Eduard; Lluís, Carme; Mallol, Josefa; Canela, Enric I; Cortés, Antoni; Casadó, Vicent

    2018-01-01

    Adenosine is an endogenous purine nucleoside that acts in all living systems as a homeostatic network regulator through many pathways, which are adenosine receptor (AR)-dependent and -independent. From a metabolic point of view, adenosine deaminase (ADA) is an essential protein in the regulation of the total intracellular and extracellular adenosine in a tissue. In addition to its cytosolic localization, ADA is also expressed as an ecto-enzyme on the surface of different cells. Dipeptidyl peptidase IV (CD26) and some ARs act as binding proteins for extracellular ADA in humans. Since CD26 and ARs interact with ADA at opposite sites, we have investigated if ADA can function as a cell-to-cell communication molecule by bridging the anchoring molecules CD26 and A 2A R present on the surfaces of the interacting cells. By combining site-directed mutagenesis of ADA amino acids involved in binding to A 2A R and a modification of the bioluminescence resonance energy transfer (BRET) technique that allows detection of interactions between two proteins expressed in different cell populations with low steric hindrance (NanoBRET), we show direct evidence of the specific formation of trimeric complexes CD26-ADA-A 2A R involving two cells. By dynamic mass redistribution assays and ligand binding experiments, we also demonstrate that A 2A R-NanoLuc fusion proteins are functional. The existence of this ternary complex is in good agreement with the hypothesis that ADA could bridge T-cells (expressing CD26) and dendritic cells (expressing A 2A R). This is a new metabolic function for ecto-ADA that, being a single chain protein, it has been considered as an example of moonlighting protein, because it performs more than one functional role (as a catalyst, a costimulator, an allosteric modulator and a cell-to-cell connector) without partitioning these functions in different subunits.

  11. Molecular Evidence of Adenosine Deaminase Linking Adenosine A2A Receptor and CD26 Proteins

    Directory of Open Access Journals (Sweden)

    Estefanía Moreno

    2018-02-01

    Full Text Available Adenosine is an endogenous purine nucleoside that acts in all living systems as a homeostatic network regulator through many pathways, which are adenosine receptor (AR-dependent and -independent. From a metabolic point of view, adenosine deaminase (ADA is an essential protein in the regulation of the total intracellular and extracellular adenosine in a tissue. In addition to its cytosolic localization, ADA is also expressed as an ecto-enzyme on the surface of different cells. Dipeptidyl peptidase IV (CD26 and some ARs act as binding proteins for extracellular ADA in humans. Since CD26 and ARs interact with ADA at opposite sites, we have investigated if ADA can function as a cell-to-cell communication molecule by bridging the anchoring molecules CD26 and A2AR present on the surfaces of the interacting cells. By combining site-directed mutagenesis of ADA amino acids involved in binding to A2AR and a modification of the bioluminescence resonance energy transfer (BRET technique that allows detection of interactions between two proteins expressed in different cell populations with low steric hindrance (NanoBRET, we show direct evidence of the specific formation of trimeric complexes CD26-ADA-A2AR involving two cells. By dynamic mass redistribution assays and ligand binding experiments, we also demonstrate that A2AR-NanoLuc fusion proteins are functional. The existence of this ternary complex is in good agreement with the hypothesis that ADA could bridge T-cells (expressing CD26 and dendritic cells (expressing A2AR. This is a new metabolic function for ecto-ADA that, being a single chain protein, it has been considered as an example of moonlighting protein, because it performs more than one functional role (as a catalyst, a costimulator, an allosteric modulator and a cell-to-cell connector without partitioning these functions in different subunits.

  12. Molecular vibration-activity relationship in the agonism of adenosine receptors.

    Science.gov (United States)

    Chee, Hyun Keun; Oh, S June

    2013-12-01

    The molecular vibration-activity relationship in the receptor-ligand interaction of adenosine receptors was investigated by structure similarity, molecular vibration, and hierarchical clustering in a dataset of 46 ligands of adenosine receptors. The resulting dendrogram was compared with those of another kind of fingerprint or descriptor. The dendrogram result produced by corralled intensity of molecular vibrational frequency outperformed four other analyses in the current study of adenosine receptor agonism and antagonism. The tree that was produced by clustering analysis of molecular vibration patterns showed its potential for the functional classification of adenosine receptor ligands.

  13. Molecular Vibration-Activity Relationship in the Agonism of Adenosine Receptors

    Directory of Open Access Journals (Sweden)

    Hyun Keun Chee

    2013-12-01

    Full Text Available The molecular vibration-activity relationship in the receptor-ligand interaction of adenosine receptors was investigated by structure similarity, molecular vibration, and hierarchical clustering in a dataset of 46 ligands of adenosine receptors. The resulting dendrogram was compared with those of another kind of fingerprint or descriptor. The dendrogram result produced by corralled intensity of molecular vibrational frequency outperformed four other analyses in the current study of adenosine receptor agonism and antagonism. The tree that was produced by clustering analysis of molecular vibration patterns showed its potential for the functional classification of adenosine receptor ligands.

  14. Effects of targeted deletion of A1 adenosine receptors on postischemic cardiac function and expression of adenosine receptor subtypes.

    Science.gov (United States)

    Morrison, R Ray; Teng, Bunyen; Oldenburg, Peter J; Katwa, Laxmansa C; Schnermann, Jurgen B; Mustafa, S Jamal

    2006-10-01

    To examine ischemic tolerance in the absence of A(1) adenosine receptors (A(1)ARs), isolated wild-type (WT) and A(1)AR knockout (A(1)KO) murine hearts underwent global ischemia-reperfusion, and injury was measured in terms of functional recovery and efflux of lactate dehydrogenase (LDH). Hearts were analyzed by real-time RT-PCR both at baseline and at intervals during ischemia-reperfusion to determine whether compensatory expression of other adenosine receptor subtypes occurs with either A(1)AR deletion and/or ischemia-reperfusion. A(1)KO hearts had higher baseline coronary flow (CF) and left ventricular developed pressure (LVDP) than WT hearts, whereas heart rate was unchanged by A(1)AR deletion. After 20 min of ischemia, CF was attenuated in A(1)KO compared with WT hearts, and this reduction persisted throughout reperfusion. Final recovery of LVDP was decreased in A(1)KO hearts (54.4 +/- 5.1 vs. WT 81.1 +/- 3.4% preischemic baseline) and correlated with higher diastolic pressure during reperfusion. Postischemic efflux of LDH was greater in A(1)KO compared with WT hearts. Real-time RT-PCR demonstrated the absence of A(1)AR transcript in A(1)KO hearts, and the message for A(2A), A(2B), and A(3) adenosine receptors was similar in uninstrumented A(1)KO and WT hearts. Ischemia-reperfusion increased A(2B) mRNA expression 2.5-fold in both WT and A(1)KO hearts without changing A(1) or A(3) expression. In WT hearts, ischemia transiently doubled A(2A) mRNA, which returned to preischemic level upon reperfusion, a pattern not observed in A(1)KO hearts. Together, these data affirm the cardioprotective role of A(1)ARs and suggest that induced expression of other adenosine receptor subtypes may participate in the response to ischemia-reperfusion in isolated murine hearts.

  15. Adenosine A(2A) receptor dynamics studied with the novel fluorescent agonist Alexa488-APEC.

    Science.gov (United States)

    Brand, Frank; Klutz, Athena M; Jacobson, Kenneth A; Fredholm, Bertil B; Schulte, Gunnar

    2008-08-20

    G protein-coupled receptors, such as the adenosine A(2A) receptor, are dynamic proteins, which undergo agonist-dependent redistribution from the cell surface to intracellular membranous compartments, such as endosomes. In order to study the kinetics of adenosine A(2A) receptor redistribution in living cells, we synthesized a novel fluorescent agonist, Alexa488-APEC. Alexa488-APEC binds to adenosine A(2A) (K(i)=149+/-27 nM) as well as A(3) receptors (K(i)=240+/-160 nM) but not to adenosine A(1) receptors. Further, we characterized the dose-dependent increase in Alexa488-APEC-induced cAMP production as well as cAMP response element binding (CREB) protein phosphorylation, verifying the ligand's functionality at adenosine A(2A) but not A(2B) receptors. In live-cell imaging studies, Alexa488-APEC-induced adenosine A(2A) receptor internalization, which was blocked by the competitive reversible antagonist ZM 241385 and hyperosmolaric sucrose. Further, internalized adenosine A(2A) receptors co-localized with clathrin and Rab5, indicating that agonist stimulation promotes adenosine A(2A) receptor uptake through a clathrin-dependent mechanism to Rab5-positive endosomes. The basic characterization of Alexa488-APEC described here showed that it provides a useful tool for tracing adenosine A(2A) receptors in vitro.

  16. Molecular Vibration-Activity Relationship in the Agonism of Adenosine Receptors

    OpenAIRE

    Chee, Hyun Keun; Oh, S. June

    2013-01-01

    The molecular vibration-activity relationship in the receptor-ligand interaction of adenosine receptors was investigated by structure similarity, molecular vibration, and hierarchical clustering in a dataset of 46 ligands of adenosine receptors. The resulting dendrogram was compared with those of another kind of fingerprint or descriptor. The dendrogram result produced by corralled intensity of molecular vibrational frequency outperformed four other analyses in the current study of adenosine ...

  17. Elevated Adenosine Induces Placental DNA Hypomethylation Independent of A2B Receptor Signaling in Preeclampsia.

    Science.gov (United States)

    Huang, Aji; Wu, Hongyu; Iriyama, Takayuki; Zhang, Yujin; Sun, Kaiqi; Song, Anren; Liu, Hong; Peng, Zhangzhe; Tang, Lili; Lee, Minjung; Huang, Yun; Ni, Xin; Kellems, Rodney E; Xia, Yang

    2017-07-01

    Preeclampsia is a prevalent pregnancy hypertensive disease with both maternal and fetal morbidity and mortality. Emerging evidence indicates that global placental DNA hypomethylation is observed in patients with preeclampsia and is linked to altered gene expression and disease development. However, the molecular basis underlying placental epigenetic changes in preeclampsia remains unclear. Using 2 independent experimental models of preeclampsia, adenosine deaminase-deficient mice and a pathogenic autoantibody-induced mouse model of preeclampsia, we demonstrate that elevated placental adenosine not only induces hallmark features of preeclampsia but also causes placental DNA hypomethylation. The use of genetic approaches to express an adenosine deaminase minigene specifically in placentas, or adenosine deaminase enzyme replacement therapy, restored placental adenosine to normal levels, attenuated preeclampsia features, and abolished placental DNA hypomethylation in adenosine deaminase-deficient mice. Genetic deletion of CD73 (an ectonucleotidase that converts AMP to adenosine) prevented the elevation of placental adenosine in the autoantibody-induced preeclampsia mouse model and ameliorated preeclampsia features and placental DNA hypomethylation. Immunohistochemical studies revealed that elevated placental adenosine-mediated DNA hypomethylation predominantly occurs in spongiotrophoblasts and labyrinthine trophoblasts and that this effect is independent of A2B adenosine receptor activation in both preeclampsia models. Extending our mouse findings to humans, we used cultured human trophoblasts to demonstrate that adenosine functions intracellularly and induces DNA hypomethylation without A2B adenosine receptor activation. Altogether, both mouse and human studies reveal novel mechanisms underlying placental DNA hypomethylation and potential therapeutic approaches for preeclampsia. © 2017 American Heart Association, Inc.

  18. Lack of adenosine A(3) receptors causes defects in mouse peripheral blood parameters

    Czech Academy of Sciences Publication Activity Database

    Hofer, Michal; Pospíšil, Milan; Dušek, L.; Hoferová, Zuzana; Komůrková, Denisa

    2014-01-01

    Roč. 10, č. 3 (2014), s. 509-514 ISSN 1573-9538 R&D Projects: GA ČR(CZ) GAP303/11/0128 Institutional support: RVO:68081707 Keywords : Adenosine A(3) receptor * Adenosine A(3) receptor knockout mice * Hematopoiesis Subject RIV: BO - Biophysics Impact factor: 3.886, year: 2014

  19. Adenosine A2A Receptor Modulates the Activity of Globus Pallidus Neurons in Rats

    Directory of Open Access Journals (Sweden)

    Hui-Ling Diao

    2017-11-01

    Full Text Available The globus pallidus is a central nucleus in the basal ganglia motor control circuit. Morphological studies have revealed the expression of adenosine A2A receptors in the globus pallidus. To determine the modulation of adenosine A2A receptors on the activity of pallidal neurons in both normal and parkinsonian rats, in vivo electrophysiological and behavioral tests were performed in the present study. The extracellular single unit recordings showed that micro-pressure administration of adenosine A2A receptor agonist, CGS21680, regulated the pallidal firing activity. GABAergic neurotransmission was involved in CGS21680-induced modulation of pallidal neurons via a PKA pathway. Furthermore, application of two adenosine A2A receptor antagonists, KW6002 or SCH442416, mainly increased the spontaneous firing of pallidal neurons, suggesting that endogenous adenosine system modulates the activity of pallidal neurons through adenosine A2A receptors. Finally, elevated body swing test (EBST showed that intrapallidal microinjection of adenosine A2A receptor agonist/antagonist induced ipsilateral/contralateral-biased swing, respectively. In addition, the electrophysiological and behavioral findings also revealed that activation of dopamine D2 receptors by quinpirole strengthened KW6002/SCH442416-induced excitation of pallidal activity. Co-application of quinpirole with KW6002 or SCH442416 alleviated biased swing in hemi-parkinsonian rats. Based on the present findings, we concluded that pallidal adenosine A2A receptors may be potentially useful in the treatment of Parkinson's disease.

  20. Ischaemic tolerance in aged mouse myocardium: the role of adenosine and effects of A1 adenosine receptor overexpression

    Science.gov (United States)

    Headrick, John P; Willems, Laura; Ashton, Kevin J; Holmgren, Kirsten; Peart, Jason; Matherne, G Paul

    2003-01-01

    The genesis of the ischaemia intolerant phenotype in aged myocardium is poorly understood. We tested the hypothesis that impaired adenosine-mediated protection contributes to ischaemic intolerance, and examined whether this is countered by A1 adenosine receptor (A1AR) overexpression. Responses to 20 min ischaemia and 45 min reperfusion were assessed in perfused hearts from young (2–4 months) and moderately aged (16–18 months) mice. Post-ischaemic contractility was impaired by ageing with elevated ventricular diastolic (32 ± 2 vs. 18 ± 2 mmHg in young) and reduced developed (37 ± 3 vs. 83 ± 6 mmHg in young) pressures. Lactate dehydrogenase (LDH) loss was exaggerated (27 ± 2 vs. 16 ± 2 IU g−1in young) whereas the incidence of tachyarrhythmias was similar in young (15 ± 1 %) and aged hearts (16 ± 1 %). Functional analysis confirmed equipotent effects of 50 μm adenosine at A1 and A2 receptors in young and aged hearts. Nonetheless, while 50 μm adenosine improved diastolic (5 ± 1 mmHg) and developed pressures (134 ± 7 mmHg) and LDH loss (6 ± 2 IU g−1) in young hearts, it did not alter these variables in the aged group. Adenosine did attenuate arrhythmogenesis for both ages (to ∼10 %). In contrast to adenosine, 50 μm diazoxide reduced ischaemic damage and arrhythmogenesis for both ages. Contractile and anti-necrotic effects of adenosine were limited by 100 μm 5-hydroxydecanoate (5-HD) and 3 μm chelerythrine. Anti-arrhythmic effects were limited by 5-HD but not chelerythrine. Non-selective (100 μm 8-sulfophenyltheophylline) and A1-selective (150 nm 8-cyclopentyl-1,3-dipropylxanthine) adenosine receptor antagonism impaired ischaemic tolerance in young but not aged hearts. Quantitative real-time PCR and radioligand analysis indicated that impaired protection is unrelated to changes in A1AR mRNA transcription, or receptor density (∼8 fmol mg−1 protein in both age groups). However, A1AR overexpression improved tolerance for both ages, restoring

  1. Novel approaches for targeting the adenosine A2A receptor.

    Science.gov (United States)

    Yuan, Gengyang; Gedeon, Nicholas G; Jankins, Tanner C; Jones, Graham B

    2015-01-01

    The adenosine A2A receptor (A2AR) represents a drug target for a wide spectrum of diseases. Approaches for targeting this membrane-bound protein have been greatly advanced by new stabilization techniques. The resulting X-ray crystal structures and subsequent analyses provide deep insight to the A2AR from both static and dynamic perspectives. Application of this, along with other biophysical methods combined with fragment-based drug design (FBDD), has become a standard approach in targeting A2AR. Complementarities of in silico screening based- and biophysical screening assisted- FBDD are likely to feature in future approaches in identifying novel ligands against this key receptor. This review describes evolution of the above approaches for targeting A2AR and highlights key modulators identified. It includes a review of: adenosine receptor structures, homology modeling, X-ray structural analysis, rational drug design, biophysical methods, FBDD and in silico screening. As a drug target, the A2AR is attractive as its function plays a role in a wide spectrum of diseases including oncologic, inflammatory, Parkinson's and cardiovascular diseases. Although traditional approaches such as high-throughput screening and homology model-based virtual screening (VS) have played a role in targeting A2AR, numerous shortcomings have generally restricted their applications to specific ligand families. Using stabilization methods for crystallization, X-ray structures of A2AR have greatly accelerated drug discovery and influenced development of biophysical-in silico hybrid screening methods. Application of these new methods to other ARs and G-protein-coupled receptors is anticipated in the future.

  2. Age-dependent changes of presynaptic neuromodulation via A1-adenosine receptors in rat hippocampal slices.

    Science.gov (United States)

    Sperlágh, B; Zsilla, G; Baranyi, M; Kékes-Szabó, A; Vizi, E S

    1997-10-01

    The presynaptic neuromodulation of stimulation-evoked release of [3H]-acetylcholine by endogenous adenosine, via A1-adenosine receptors, was studied in superfused hippocampal slices taken from 4-, 12- and 24-month-old rats. 8-Cyclopentyl-1,3-dimethylxanthine (0.25 microM), a selective A1-receptor antagonist, increased significantly the electrical field stimulation-induced release of [3H]-acetylcholine in slices prepared from 4- and 12-month-old rats, showing a tonic inhibitory action of endogenous adenosine via stimulation of presynaptic A1-adenosine receptors. In contrast, 8-cyclopentyl-1,3-dimethylxanthine had no effect in 24-month-old rats. 2-Chloroadenosine (10 microM), an adenosine receptor agonist decreased the release of [3H]-acetylcholine in slices taken from 4- and 12-month-old rats, and no significant change was observed in slices taken from 24-month-old rats. In order to show whether the number/or affinity of the A1-receptors was affected in aged rats, [3H]-8-cyclopentyl-1,3-dimethylxanthine binding was studied in hippocampal membranes prepared from rats of different ages. Whereas the Bmax value was significantly lower in 2-year-old rats than in younger counterparts, the dissociation constant (Kd) was not affected by aging, indicating that the density rather than the affinity of adenosine receptors was altered. Endogenous adenosine levels present in the extracellular space were also measured in the superfusate by high performance liquid chromatography (HPLC) coupled with ultraviolet detection, and an age-related increase in the adenosine level was found. In summary, our results indicate that during aging the level of adenosine in the extracellular fluid is increased in the hippocampus. There is a downregulation and reduced responsiveness of presynaptic adenosine A1-receptors, and it seems likely that these changes are due to the enhanced adenosine level in the extracellular space.

  3. Small-animal PET study of adenosine A(1) receptors in rat brain: blocking receptors and raising extracellular adenosine.

    Science.gov (United States)

    Paul, Soumen; Khanapur, Shivashankar; Rybczynska, Anna A; Kwizera, Chantal; Sijbesma, Jurgen W A; Ishiwata, Kiichi; Willemsen, Antoon T M; Elsinga, Philip H; Dierckx, Rudi A J O; van Waarde, Aren

    2011-08-01

    Activation of adenosine A(1) receptors (A(1)R) in the brain causes sedation, reduces anxiety, inhibits seizures, and promotes neuroprotection. Cerebral A(1)R can be visualized using 8-dicyclopropylmethyl-1-(11)C-methyl-3-propyl-xanthine ((11)C-MPDX) and PET. This study aims to test whether (11)C-MPDX can be used for quantitative studies of cerebral A(1)R in rodents. (11)C-MPDX was injected (intravenously) into isoflurane-anesthetized male Wistar rats (300 g). A dynamic scan of the central nervous system was obtained, using a small-animal PET camera. A cannula in a femoral artery was used for blood sampling. Three groups of animals were studied: group 1, controls (saline-treated); group 2, animals pretreated with the A(1)R antagonist 8-cyclopentyl-1,3-dipropylxanthine (DPCPX, 1 mg, intraperitoneally); and group 3, animals pretreated (intraperitoneally) with a 20% solution of ethanol in saline (2 mL) plus the adenosine kinase inhibitor 4-amino-5-(3-bromophenyl)-7-(6-morpholino-pyridin-3-yl)pyrido[2,3-d] pyrimidine dihydrochloride (ABT-702) (1 mg). DPCPX is known to occupy cerebral A(1)R, whereas ethanol and ABT-702 increase extracellular adenosine. In groups 1 and 3, the brain was clearly visualized. High uptake of (11)C-MPDX was noted in striatum, hippocampus, and cerebellum. In group 2, tracer uptake was strongly suppressed and regional differences were abolished. The treatment of group 3 resulted in an unexpected 40%-45% increase of the cerebral uptake of radioactivity as indicated by increases of PET standardized uptake value, distribution volume from Logan plot, nondisplaceable binding potential from 2-tissue-compartment model fit, and standardized uptake value from a biodistribution study performed after the PET scan. The partition coefficient of the tracer (K(1)/k(2) from the model fit) was not altered under the study conditions. (11)C-MPDX shows a regional distribution in rat brain consistent with binding to A(1)R. Tracer binding is blocked by the selective A

  4. Natural Killer Receptor 1 Dampens the Development of Allergic Eosinophilic Airway Inflammation.

    Directory of Open Access Journals (Sweden)

    Shirin Elhaik Goldman

    Full Text Available The function of NCR1 was studied in a model of experimental asthma, classified as a type 1 hypersensitivity reaction, in mice. IgE levels were significantly increased in the serum of OVA immunized NCR1 deficient (NCR1gfp/gfp mice in comparison to OVA immunized wild type (NCR1+/+ and adjuvant immunized mice. Histological analysis of OVA immunized NCR1gfp/gfp mice revealed no preservation of the lung structure and overwhelming peribronchial and perivascular granulocytes together with mononuclear cells infiltration. OVA immunized NCR+/+ mice demonstrated preserved lung structure and peribronchial and perivascular immune cell infiltration to a lower extent than that in NCR1gfp/gfp mice. Adjuvant immunized mice demonstrated lung structure preservation and no immune cell infiltration. OVA immunization caused an increase in PAS production independently of NCR1 presence. Bronchoalveolar lavage (BAL revealed NCR1 dependent decreased percentages of eosinophils and increased percentages of lymphocytes and macrophages following OVA immunization. In the OVA immunized NCR1gfp/gfp mice the protein levels of eosinophils' (CCL24 and Th2 CD4+ T-cells' chemoattractants (CCL17, and CCL24 in the BAL are increased in comparison with OVA immunized NCR+/+ mice. In the presence of NCR1, OVA immunization caused an increase in NK cells numbers and decreased NCR1 ligand expression on CD11c+GR1+ cells and decreased NCR1 mRNA expression in the BAL. OVA immunization resulted in significantly increased IL-13, IL-4 and CCL17 mRNA expression in NCR1+/+ and NCR1gfp/gfp mice. IL-17 and TNFα expression increased only in OVA-immunized NCR1+/+mice. IL-6 mRNA increased only in OVA immunized NCR1gfp/gfp mice. Collectively, it is demonstrated that NCR1 dampens allergic eosinophilic airway inflammation.

  5. Caffeine, Adenosine Receptors and Estrogen in Toxin Models of Parkinson's Disease

    National Research Council Canada - National Science Library

    Schwarzschild, Michael A; Xu, Kui

    2008-01-01

    Continued progress has been made toward each of the Specific Aims (SAs) 1 and 2 (SA 3 completed) of our research project, Caffeine, adenosine receptors and estrogen in toxin models of Parkinson's disease...

  6. Adenosine A1 receptors contribute to immune regulation after neonatal hypoxic ischemic brain injury

    OpenAIRE

    Winerdal, Max; Winerdal, Malin E.; Wang, Ying-Qing; Fredholm, Bertil B.; Winqvist, Ola; Ådén, Ulrika

    2015-01-01

    Neonatal brain hypoxic ischemia (HI) often results in long-term motor and cognitive impairments. Post-ischemic inflammation greatly effects outcome and adenosine receptor signaling modulates both HI and immune cell function. Here, we investigated the influence of adenosine A1 receptor deficiency (A1R−/−) on key immune cell populations in a neonatal brain HI model. Ten-day-old mice were subjected to HI. Functional outcome was assessed by open locomotion and beam walking test and infarction siz...

  7. No Effect of Nutritional Adenosine Receptor Antagonists on Exercise Performance in the Heat

    Science.gov (United States)

    2008-11-01

    358–363, 1996. 11. Cook NC, Samman S. Flavonoids —chemistry, metabolism, cardiopro- tective effects, and dietary sources. Nutr Biochem 7: 66–76, 1996...metabolism and health effects of dietary flavonoids in man. Biomed Pharmacother 51: 305–310, 1997. R400 ADENOSINE RECEPTOR ANTAGONISM AND EXERCISE IN THE HEAT...Interactions of flavonoids with adenosine receptors. J Med Chem 39: 781–788, 1996. 35. MacRae HS, Mefferd KM. Dietary antioxidant supplementation com

  8. Adenosine receptors in rat and human pancreatic ducts stimulate chloride transport

    DEFF Research Database (Denmark)

    Novak, Ivana; Hede, Susanne; Hansen, Mette

    2007-01-01

    , it was found that 58% of PANC-1 cells responded to adenosine, whereas only 9% of CFPAC-1 cells responded. Adenosine elicited Ca(2+) signals only in a few rat and human duct cells, which did not seem to correlate with Cl(-) signals. A(2A) receptors were localized in the luminal membranes of rat pancreatic ducts......, plasma membrane of many PANC-1 cells, but only a few CFPAC-1 cells. Taken together, our data indicate that A(2A) receptors open Cl(-) channels in pancreatic ducts cells with functional CFTR. We propose that adenosine can stimulate pancreatic secretion and, thereby, is an active player in the acini...

  9. Polymorphisms in adenosine receptor genes are associated with infarct size in patients with ischemic cardiomyopathy.

    Science.gov (United States)

    Tang, Z; Diamond, M A; Chen, J-M; Holly, T A; Bonow, R O; Dasgupta, A; Hyslop, T; Purzycki, A; Wagner, J; McNamara, D M; Kukulski, T; Wos, S; Velazquez, E J; Ardlie, K; Feldman, A M

    2007-10-01

    The goal of this experiment was to identify the presence of genetic variants in the adenosine receptor genes and assess their relationship to infarct size in a population of patients with ischemic cardiomyopathy. Adenosine receptors play an important role in protecting the heart during ischemia and in mediating the effects of ischemic preconditioning. We sequenced DNA samples from 273 individuals with ischemic cardiomyopathy and from 203 normal controls to identify the presence of genetic variants in the adenosine receptor genes. Subsequently, we analyzed the relationship between the identified genetic variants and infarct size, left ventricular size, and left ventricular function. Three variants in the 3'-untranslated region of the A(1)-adenosine gene (nt 1689 C/A, nt 2206 Tdel, nt 2683del36) and an informative polymorphism in the coding region of the A3-adenosine gene (nt 1509 A/C I248L) were associated with changes in infarct size. These results suggest that genetic variants in the adenosine receptor genes may predict the heart's response to ischemia or injury and might also influence an individual's response to adenosine therapy.

  10. Protection against methamphetamine-induced neurotoxicity to neostriatal dopaminergic neurons by adenosine receptor activation.

    Science.gov (United States)

    Delle Donne, K T; Sonsalla, P K

    1994-12-01

    Methamphetamine (METH)-induced neurotoxicity to nigrostriatal dopaminergic neurons in experimental animals appears to have a glutamatergic component because blockade of N-methyl-D-aspartate receptors prevents the neuropathologic consequences. Because adenosine affords neuroprotection against various forms of glutamate-mediated neuronal damage, the present studies were performed to investigate whether adenosine plays a protective role in METH-induced toxicity. METH-induced decrements in neostriatal dopamine content and tyrosine hydroxylase activity in mice were potentiated by concurrent treatment with caffeine, a nonselective adenosine antagonist that blocks both A1 and A2 adenosine receptors. In contrast, chronic treatment of mice with caffeine through their drinking water for 4 weeks, which increased the number of adenosine A1 receptors in the neostriatum and frontal cortex, followed by drug washout, prevented the neurochemical changes produced by the treatment of mice with METH treatment. In contrast, this treatment did not prevent 1-methyl-4-phenyl-1,2,3,6- tetrahydropyridine-induced dopaminergic neurotoxicity. Furthermore, concurrent administration of cyclopentyladenosine, an adenosine A1 receptor agonist, attenuated the METH-induced neurochemical changes. This protection by cyclopentyladenosine was blocked by cyclopentyltheophylline, an A1 receptor antagonist. These results indicate that activation of A1 receptors can protect against METH-induced neurotoxicity in mice.

  11. Caffeine acts through neuronal adenosine A2A receptors to prevent mood and memory dysfunction triggered by chronic stress.

    Science.gov (United States)

    Kaster, Manuella P; Machado, Nuno J; Silva, Henrique B; Nunes, Ana; Ardais, Ana Paula; Santana, Magda; Baqi, Younis; Müller, Christa E; Rodrigues, Ana Lúcia S; Porciúncula, Lisiane O; Chen, Jiang Fan; Tomé, Ângelo R; Agostinho, Paula; Canas, Paula M; Cunha, Rodrigo A

    2015-06-23

    The consumption of caffeine (an adenosine receptor antagonist) correlates inversely with depression and memory deterioration, and adenosine A2A receptor (A2AR) antagonists emerge as candidate therapeutic targets because they control aberrant synaptic plasticity and afford neuroprotection. Therefore we tested the ability of A2AR to control the behavioral, electrophysiological, and neurochemical modifications caused by chronic unpredictable stress (CUS), which alters hippocampal circuits, dampens mood and memory performance, and enhances susceptibility to depression. CUS for 3 wk in adult mice induced anxiogenic and helpless-like behavior and decreased memory performance. These behavioral changes were accompanied by synaptic alterations, typified by a decrease in synaptic plasticity and a reduced density of synaptic proteins (synaptosomal-associated protein 25, syntaxin, and vesicular glutamate transporter type 1), together with an increased density of A2AR in glutamatergic terminals in the hippocampus. Except for anxiety, for which results were mixed, CUS-induced behavioral and synaptic alterations were prevented by (i) caffeine (1 g/L in the drinking water, starting 3 wk before and continued throughout CUS); (ii) the selective A2AR antagonist KW6002 (3 mg/kg, p.o.); (iii) global A2AR deletion; and (iv) selective A2AR deletion in forebrain neurons. Notably, A2AR blockade was not only prophylactic but also therapeutically efficacious, because a 3-wk treatment with the A2AR antagonist SCH58261 (0.1 mg/kg, i.p.) reversed the mood and synaptic dysfunction caused by CUS. These results herald a key role for synaptic A2AR in the control of chronic stress-induced modifications and suggest A2AR as candidate targets to alleviate the consequences of chronic stress on brain function.

  12. Cerebral adenosine A₁ receptors are upregulated in rodent encephalitis.

    Science.gov (United States)

    Paul, Soumen; Khanapur, Shivashankar; Boersma, Wytske; Sijbesma, Jurgen W; Ishiwata, Kiichi; Elsinga, Philip H; Meerlo, Peter; Doorduin, Janine; Dierckx, Rudi A; van Waarde, Aren

    2014-05-15

    Adenosine A1 receptors (A1Rs) are implied in the modulation of neuroinflammation. Activation of cerebral A1Rs acts as a brake on the microglial response after traumatic brain injury and has neuroprotective properties in animal models of Parkinson's disease and multiple sclerosis. Neuroinflammatory processes in turn may affect the expression of A1Rs, but the available data is limited and inconsistent. Here, we applied an animal model of encephalitis to assess how neuroinflammation affects the expression of A1Rs. Two groups of animals were studied: Infected rats (n=7) were intranasally inoculated with herpes simplex virus-1 (HSV-1, 1 × 10(7) plaque forming units), sham-infected rats (n=6) received only phosphate-buffered saline. Six or seven days later, microPET scans (60 min with arterial blood sampling) were made using the tracer 8-dicyclopropyl-1-(11)C-methyl-3-propyl-xanthine ((11)C-MPDX). Tracer clearance from plasma and partition coefficient (K₁/k₂ estimated from a 2-tissue compartment model fit) were not significantly altered after virus infection. PET tracer distribution volume calculated from a Logan plot was significantly increased in the hippocampus (+37%) and medulla (+27%) of virus infected rats. Tracer binding potential (k₃/k₄ estimated from the model fit) was significantly increased in the cerebellum (+87%) and the medulla (+148%) which may indicate increased A1R expression. This was confirmed by immunohistochemical analysis showing a strong increase of A1R immunoreactivity in the cerebellum of HSV-1-infected rats. Both the quantitative PET data and immunohistochemical analysis indicate that A1Rs are upregulated in brain areas where active virus is present. Copyright © 2014 Elsevier Inc. All rights reserved.

  13. Adenosine enhances sweet taste through A2B receptors in the taste bud.

    Science.gov (United States)

    Dando, Robin; Dvoryanchikov, Gennady; Pereira, Elizabeth; Chaudhari, Nirupa; Roper, Stephen D

    2012-01-04

    Mammalian taste buds use ATP as a neurotransmitter. Taste Receptor (type II) cells secrete ATP via gap junction hemichannels into the narrow extracellular spaces within a taste bud. This ATP excites primary sensory afferent fibers and also stimulates neighboring taste bud cells. Here we show that extracellular ATP is enzymatically degraded to adenosine within mouse vallate taste buds and that this nucleoside acts as an autocrine neuromodulator to selectively enhance sweet taste. In Receptor cells in a lingual slice preparation, Ca(2+) mobilization evoked by focally applied artificial sweeteners was significantly enhanced by adenosine (50 μM). Adenosine had no effect on bitter or umami taste responses, and the nucleoside did not affect Presynaptic (type III) taste cells. We also used biosensor cells to measure transmitter release from isolated taste buds. Adenosine (5 μM) enhanced ATP release evoked by sweet but not bitter taste stimuli. Using single-cell reverse transcriptase (RT)-PCR on isolated vallate taste cells, we show that many Receptor cells express the adenosine receptor, Adora2b, while Presynaptic (type III) and Glial-like (type I) cells seldom do. Furthermore, Adora2b receptors are significantly associated with expression of the sweet taste receptor subunit, Tas1r2. Adenosine is generated during taste stimulation mainly by the action of the ecto-5'-nucleotidase, NT5E, and to a lesser extent, prostatic acid phosphatase. Both these ecto-nucleotidases are expressed by Presynaptic cells, as shown by single-cell RT-PCR, enzyme histochemistry, and immunofluorescence. Our findings suggest that ATP released during taste reception is degraded to adenosine to exert positive modulation particularly on sweet taste.

  14. Autoradiographic localization of adenosine receptors in rat brain using [3H]cyclohexyladenosine

    International Nuclear Information System (INIS)

    Goodman, R.R.; Synder, S.H.

    1982-01-01

    Adenosine (A1) receptor binding sites have been localized in rat brain by an in vitro light microscopic autoradiographic method. The binding of [ 3 H]N6-cyclohexyladenosine to slide-mounted rat brain tissue sections has the characteristics of A1 receptors. It is saturable with high affinity and has appropriate pharmacology and stereospecificity. The highest densities of adenosine receptors occur in the molecular layer of the cerebellum, the molecular and polymorphic layers of the hippocampus and dentate gyrus, the medial geniculate body, certain thalamic nuclei, and the lateral septum. High densities also are observed in certain layers of the cerebral cortex, the piriform cortex, the caudate-putamen, the nucleus accumbens, and the granule cell layer of the cerebellum. Most white matter areas, as well as certain gray matter areas, such as the hypothalamus, have negligible receptor concentrations. These localizations suggest possible central nervous system sites of action of adenosine

  15. The Neuroprotective Benefits of Central Adenosine Receptor Stimulation in a Soman Nerve Agent Rat Model

    Science.gov (United States)

    2014-04-01

    where treatment is delayed and nerve agent-induced status epilepticus develops. New therapeutic targets are required to improve survivability and...Exp Ther 304(3): 1307-1313. Compton, J. R. (2004). Adenosine Receptor Agonist Pd 81,723 Protects Against Seizure/ Status Epilepticus and...Dragunow (1994). " Status epilepticus may be caused by loss of adenosine anticonvulsant mechanisms." Neuroscience 58(2): 245-261. Youssef, A. F. and B. W

  16. REDUCTION OF ADENOSINE-A1-RECEPTORS IN THE PERFORANT PATHWAY TERMINAL ZONE IN ALZHEIMER HIPPOCAMPUS

    NARCIS (Netherlands)

    JAARSMA, D; SEBENS, JB; KORF, J

    1991-01-01

    The cells of origin of the perforant pathway are destroyed in Alzheimer's disease (AD). In rat the adenosine A1-receptors are specifically localized on the perforant path terminals in the molecular layer of the dentate gyrus. In the present study the density of A1-receptors in the hippocampus of

  17. Adenosine Receptor Stimulation Improves Glucocorticoid-Induced Osteoporosis in a Rat Model

    Directory of Open Access Journals (Sweden)

    Gabriele Pizzino

    2017-09-01

    Full Text Available Glucocorticoid-induced osteoporosis (GIO is a secondary cause of bone loss. Bisphosphonates approved for GIO, might induce jaw osteonecrosis; thus additional therapeutics are required. Adenosine receptor agonists are positive regulators of bone remodeling, thus the efficacy of adenosine receptor stimulation for treating GIO was tested. In a preventive study GIO was induced in Sprague-Dawley rats by methylprednisolone (MP for 60 days. Animals were randomly assigned to receive polydeoxyribonucleotide (PDRN, an adenosine A2 receptor agonist, or PDRN and DMPX (3,7-dimethyl-1-propargylxanthine, an A2 antagonist, or vehicle (0.9% NaCl. Another set of animals was used for a treatment study, following the 60 days of MP-induction rats were randomized to receive (for additional 60 days PDRN, or PDRN and DMPX (an adenosine A2 receptor antagonist, or zoledronate (as control for gold standard treatment, or vehicle. Control animals were administered with vehicle for either 60 or 120 days. Femurs were analyzed after treatments for histology, imaging, and breaking strength analysis. MP treatment induced severe bone loss, the concomitant use of PDRN prevented the developing of osteoporosis. In rats treated for 120 days, PDRN restored bone architecture and bone strength; increased b-ALP, osteocalcin, osteoprotegerin and stimulated the Wnt canonical and non-canonical pathway. Zoledronate reduced bone resorption and ameliorated the histological features, without significant effects on bone formation. Our results suggest that adenosine receptor stimulation might be useful for preventing and treating GIO.

  18. Caffeine and Selective Adenosine Receptor Antagonists as New Therapeutic Tools for the Motivational Symptoms of Depression

    Directory of Open Access Journals (Sweden)

    Laura López-Cruz

    2018-06-01

    Full Text Available Major depressive disorder is one of the most common and debilitating psychiatric disorders. Some of the motivational symptoms of depression, such anergia (lack of self-reported energy and fatigue are relatively resistant to traditional treatments such as serotonin uptake inhibitors. Thus, new pharmacological targets are being investigated. Epidemiological data suggest that caffeine consumption can have an impact on aspects of depressive symptomatology. Caffeine is a non-selective adenosine antagonist for A1/A2A receptors, and has been demonstrated to modulate behavior in classical animal models of depression. Moreover, selective adenosine receptor antagonists are being assessed for their antidepressant effects in animal studies. This review focuses on how caffeine and selective adenosine antagonists can improve different aspects of depression in humans, as well as in animal models. The effects on motivational symptoms of depression such as anergia, fatigue, and psychomotor slowing receive particular attention. Thus, the ability of adenosine receptor antagonists to reverse the anergia induced by dopamine antagonism or depletion is of special interest. In conclusion, although further studies are needed, it appears that caffeine and selective adenosine receptor antagonists could be therapeutic agents for the treatment of motivational dysfunction in depression.

  19. Adenosine A2A Receptors Modulate Acute Injury and Neuroinflammation in Brain Ischemia

    Directory of Open Access Journals (Sweden)

    Felicita Pedata

    2014-01-01

    Full Text Available The extracellular concentration of adenosine in the brain increases dramatically during ischemia. Adenosine A2A receptor is expressed in neurons and glial cells and in inflammatory cells (lymphocytes and granulocytes. Recently, adenosine A2A receptor emerged as a potential therapeutic attractive target in ischemia. Ischemia is a multifactorial pathology characterized by different events evolving in the time. After ischemia the early massive increase of extracellular glutamate is followed by activation of resident immune cells, that is, microglia, and production or activation of inflammation mediators. Proinflammatory cytokines, which upregulate cell adhesion molecules, exert an important role in promoting recruitment of leukocytes that in turn promote expansion of the inflammatory response in ischemic tissue. Protracted neuroinflammation is now recognized as the predominant mechanism of secondary brain injury progression. A2A receptors present on central cells and on blood cells account for important effects depending on the time-related evolution of the pathological condition. Evidence suggests that A2A receptor antagonists provide early protection via centrally mediated control of excessive excitotoxicity, while A2A receptor agonists provide protracted protection by controlling massive blood cell infiltration in the hours and days after ischemia. Focus on inflammatory responses provides for adenosine A2A receptor agonists a wide therapeutic time-window of hours and even days after stroke.

  20. A2BR Adenosine Receptor Modulates Sweet Taste in Circumvallate Taste Buds

    Science.gov (United States)

    Yang, Dan; Shultz, Nicole; Vandenbeuch, Aurelie; Ravid, Katya; Kinnamon, Sue C.; Finger, Thomas E.

    2012-01-01

    In response to taste stimulation, taste buds release ATP, which activates ionotropic ATP receptors (P2X2/P2X3) on taste nerves as well as metabotropic (P2Y) purinergic receptors on taste bud cells. The action of the extracellular ATP is terminated by ectonucleotidases, ultimately generating adenosine, which itself can activate one or more G-protein coupled adenosine receptors: A1, A2A, A2B, and A3. Here we investigated the expression of adenosine receptors in mouse taste buds at both the nucleotide and protein expression levels. Of the adenosine receptors, only A2B receptor (A2BR) is expressed specifically in taste epithelia. Further, A2BR is expressed abundantly only in a subset of taste bud cells of posterior (circumvallate, foliate), but not anterior (fungiform, palate) taste fields in mice. Analysis of double-labeled tissue indicates that A2BR occurs on Type II taste bud cells that also express Gα14, which is present only in sweet-sensitive taste cells of the foliate and circumvallate papillae. Glossopharyngeal nerve recordings from A2BR knockout mice show significantly reduced responses to both sucrose and synthetic sweeteners, but normal responses to tastants representing other qualities. Thus, our study identified a novel regulator of sweet taste, the A2BR, which functions to potentiate sweet responses in posterior lingual taste fields. PMID:22253866

  1. A2BR adenosine receptor modulates sweet taste in circumvallate taste buds.

    Directory of Open Access Journals (Sweden)

    Shinji Kataoka

    Full Text Available In response to taste stimulation, taste buds release ATP, which activates ionotropic ATP receptors (P2X2/P2X3 on taste nerves as well as metabotropic (P2Y purinergic receptors on taste bud cells. The action of the extracellular ATP is terminated by ectonucleotidases, ultimately generating adenosine, which itself can activate one or more G-protein coupled adenosine receptors: A1, A2A, A2B, and A3. Here we investigated the expression of adenosine receptors in mouse taste buds at both the nucleotide and protein expression levels. Of the adenosine receptors, only A2B receptor (A2BR is expressed specifically in taste epithelia. Further, A2BR is expressed abundantly only in a subset of taste bud cells of posterior (circumvallate, foliate, but not anterior (fungiform, palate taste fields in mice. Analysis of double-labeled tissue indicates that A2BR occurs on Type II taste bud cells that also express Gα14, which is present only in sweet-sensitive taste cells of the foliate and circumvallate papillae. Glossopharyngeal nerve recordings from A2BR knockout mice show significantly reduced responses to both sucrose and synthetic sweeteners, but normal responses to tastants representing other qualities. Thus, our study identified a novel regulator of sweet taste, the A2BR, which functions to potentiate sweet responses in posterior lingual taste fields.

  2. A2BR adenosine receptor modulates sweet taste in circumvallate taste buds.

    Science.gov (United States)

    Kataoka, Shinji; Baquero, Arian; Yang, Dan; Shultz, Nicole; Vandenbeuch, Aurelie; Ravid, Katya; Kinnamon, Sue C; Finger, Thomas E

    2012-01-01

    In response to taste stimulation, taste buds release ATP, which activates ionotropic ATP receptors (P2X2/P2X3) on taste nerves as well as metabotropic (P2Y) purinergic receptors on taste bud cells. The action of the extracellular ATP is terminated by ectonucleotidases, ultimately generating adenosine, which itself can activate one or more G-protein coupled adenosine receptors: A1, A2A, A2B, and A3. Here we investigated the expression of adenosine receptors in mouse taste buds at both the nucleotide and protein expression levels. Of the adenosine receptors, only A2B receptor (A2BR) is expressed specifically in taste epithelia. Further, A2BR is expressed abundantly only in a subset of taste bud cells of posterior (circumvallate, foliate), but not anterior (fungiform, palate) taste fields in mice. Analysis of double-labeled tissue indicates that A2BR occurs on Type II taste bud cells that also express Gα14, which is present only in sweet-sensitive taste cells of the foliate and circumvallate papillae. Glossopharyngeal nerve recordings from A2BR knockout mice show significantly reduced responses to both sucrose and synthetic sweeteners, but normal responses to tastants representing other qualities. Thus, our study identified a novel regulator of sweet taste, the A2BR, which functions to potentiate sweet responses in posterior lingual taste fields.

  3. Adenosine receptors and muscarinic receptors cooperate in acetylcholine release modulation in the neuromuscular synapse.

    Science.gov (United States)

    Santafe, M M; Priego, M; Obis, T; Garcia, N; Tomàs, M; Lanuza, M A; Tomàs, J

    2015-07-01

    Adenosine receptors (ARs) are present in the motor terminals at the mouse neuromuscular junction. ARs and the presynaptic muscarinic acetylcholine receptors (mAChRs) share the functional control of the neuromuscular junction. We analysed their mutual interaction in transmitter release modulation. In electrophysiological experiments with unaltered synaptic transmission (muscles paralysed by blocking the voltage-dependent sodium channel of the muscle cells with μ-conotoxin GIIIB), we found that: (i) a collaborative action between different AR subtypes reduced synaptic depression at a moderate activity level (40 Hz); (ii) at high activity levels (100 Hz), endogenous adenosine production in the synaptic cleft was sufficient to reduce depression through A1 -type receptors (A1 Rs) and A2 A-type receptors (A2 A Rs); (iii) when the non-metabolizable 2-chloroadenosine (CADO) agonist was used, both the quantal content and depression were reduced; (iv) the protective effect of CADO on depression was mediated by A1 Rs, whereas A2 A Rs seemed to modulate A1 Rs; (v) ARs and mAChRs absolutely depended upon each other for the modulation of evoked and spontaneous acetylcholine release in basal conditions and in experimental conditions with CADO stimulation; (vi) the purinergic and muscarinic mechanisms cooperated in the control of depression by sharing a common pathway although the purinergic control was more powerful than the muscarinic control; and (vii) the imbalance of the ARs created by using subtype-selective and non-selective inhibitory and stimulatory agents uncoupled protein kinase C from evoked transmitter release. In summary, ARs (A1 Rs, A2 A Rs) and mAChRs (M1 , M2 ) cooperated in the control of activity-dependent synaptic depression and may share a common protein kinase C pathway. © 2015 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

  4. Identification of the A2 adenosine receptor binding subunit by photoaffinity crosslinking

    International Nuclear Information System (INIS)

    Barrington, W.W.; Jacobson, K.A.; Hutchison, A.J.; Williams, M.; Stiles, G.L.

    1989-01-01

    A high-affinity iodinated agonist radioligand for the A2 adenosine receptor has been synthesized to facilitate studies of the A2 adenosine receptor binding subunit. The radioligand 125I-labeled PAPA-APEC (125I-labeled 2-[4-(2-[2-[(4- aminophenyl)methylcarbonylamino]ethylaminocarbonyl]- ethyl)phenyl]ethylamino-5'-N-ethylcarboxamidoadenosine) was synthesized and found to bind to the A2 adenosine receptor in bovine striatal membranes with high affinity (Kd = 1.5 nM) and A2 receptor selectivity. Competitive binding studies reveal the appropriate A2 receptor pharmacologic potency order with 5'-N-ethylcarboxamidoadenosine (NECA) greater than (-)-N6-[(R)-1-methyl- 2-phenylethyl]adenosine (R-PIA) greater than (+)-N6-[(S)-1-methyl-2- phenylethyl]adenosine (S-PIA). Adenylate cyclase assays, in human platelet membranes, demonstrate a dose-dependent stimulation of cAMP production. PAPA-APEC (1 microM) produces a 43% increase in cAMP production, which is essentially the same degree of increase produced by 5'-N- ethylcarboxamidoadenosine (the prototypic A2 receptor agonist). These findings combined with the observed guanine nucleotide-mediated decrease in binding suggest that PAPA-APEC is a full A2 agonist. The A2 receptor binding subunit was identified by photoaffinity-crosslinking studies using 125I-labeled PAPA-APEC and the heterobifunctional crosslinking agent N-succinimidyl 6-(4'-azido-2'-nitrophenylamino)hexanoate (SANPAH). After covalent incorporation, a single specifically radiolabeled protein with an apparent molecular mass of 45 kDa was observed on NaDodSO4/PAGE/autoradiography. Incorporation of 125I-labeled PAPA-APEC into this polypeptide is blocked by agonists and antagonists with the expected potency for A2 receptors and is decreased in the presence of 10(-4) M guanosine 5'-[beta, gamma-imido]triphosphate

  5. Progress towards novel adenosine receptor therapeutics gleaned from the recent patent literature.

    Science.gov (United States)

    Press, Neil J; Fozard, John R

    2010-08-01

    The principle of treating disease with selective adenosine receptor ligands has been demonstrated with drugs on the market, while the lesser understood receptor subtypes are still being probed with new and drug-like pharmaceutical tools. The field of adenosine receptor research is, therefore, highly important as an emerging and proven point of intervention in disease. From 2008 to 2009, > 120 primary patent applications have claimed adenosine receptor ligands, which we analyze by applicant and target. Particularly significant disclosures are described in detail, paying particular attention to the biological data marshalled to support the case. The first published disclosure of new compounds, compound uses or drug targets is often in the patent literature, which can be difficult to trawl, interpret and verify as it is not subject to peer review. We have critically reviewed this area and share our conclusions regarding progress, trends and identification of early tool compounds or compounds of potential clinical significance ahead of peer-reviewed publication. Adenosine receptor research is a thriving field with continuing claims of exciting new compounds with high specificity and intriguing examples of new uses for such ligands.

  6. Adenosine inhibits neutrophil vascular endothelial growth factor release and transendothelial migration via A2B receptor activation.

    LENUS (Irish Health Repository)

    Wakai, A

    2012-02-03

    The effects of adenosine on neutrophil (polymorphonuclear neutrophils; PMN)-directed changes in vascular permeability are poorly characterized. This study investigated whether adenosine modulates activated PMN vascular endothelial growth factor (vascular permeability factor; VEGF) release and transendothelial migration. PMN activated with tumour necrosis factor-alpha (TNF-alpha, 10 ng\\/mL) were incubated with adenosine and its receptor-specific analogues. Culture supernatants were assayed for VEGF. PMN transendothelial migration across human umbilical vein endothelial cell (HUVEC) monolayers was assessed in vitro. Adhesion molecule receptor expression was assessed flow cytometrically. Adenosine and some of its receptor-specific analogues dose-dependently inhibited activated PMN VEGF release. The rank order of potency was consistent with the affinity profile of human A2B receptors. The inhibitory effect of adenosine was reversed by 3,7-dimethyl-1-propargylxanthine, an A2 receptor antagonist. Adenosine (100 microM) or the A2B receptor agonist 5\\'-N-ethylcarboxamidoadenosine (NECA, 100 microM) significantly reduced PMN transendothelial migration. However, expression of activated PMN beta2 integrins and HUVEC ICAM-1 were not significantly altered by adenosine or NECA. Adenosine attenuates human PMN VEGF release and transendothelial migration via the A2B receptor. This provides a novel target for the modulation of PMN-directed vascular hyperpermeability in conditions such as the capillary leak syndrome.

  7. Regulatory effects of adenosine A2A receptors on psychomotor ability and mood behavior of mice

    Directory of Open Access Journals (Sweden)

    Li JIANG

    2011-07-01

    Full Text Available Objective To explore the effects of gene knock-out,agonist or inhibitor of adenosine A2A receptor on the locomotor activity,and anxiety-or depression-like behavior of mice.Methods Male C57BL/6 mice,comprising those underwent gene knock-out of adenosine A2A receptor(A2AKO and their wild-type(WT littermates,were assigned into A2AKO group and WT group.Another batch of male C57BL/6,specific-pathogen-free(SPF mice,were assigned into SCH58261 group,CGS21680 group and control group.Mice of aforesaid 3 groups were transperitoneally administered with SCH58261,a specific inhibitor of adenosine A2A receptor at a dose of 2mg/kg,CGS21680,a specific agonist of adenosine A2A receptor at a dose of 0.5mg/kg,and vehicle(0.25ml,comprising DMSO and saline,respectively.Ten minutes after injection,mice of the 3 groups underwent open-field test,elevated plus-maze test and forced swimming test to detect their locomotor activity,anxiety-and depression-like behavior.Results a Compared with WT group,the total movement distance decreased(P 0.05.b Compared with control group,the total movement distance decreased and the stay time in the peripheral area increased significantly in the open field test(P 0.05.Conclusions The agonist of adenosine A2A receptor may depress the spontaneous motility and exploratory behavior,and exacerbate the anxiety and depression,and it simulates the effect induced by knock-out of A2A receptor gene,but it is opposite to the effect induced by A2A receptor inhibitor.

  8. Circadian rhythm in adenosine A1 receptor of mouse cerebral cortex

    Energy Technology Data Exchange (ETDEWEB)

    Florio, C.; Rosati, A.M.; Traversa, U.; Vertua, R. (Univ. of Trieste (Italy))

    1991-01-01

    In order to investigate diurnal variation in adenosine A1 receptors binding parameters, Bmax and Kd values of specifically bound N6-cyclohexyl-({sup 3}H)adenosine were determined in the cerebral cortex of mice that had been housed under controlled light-dark cycles for 4 weeks. Significant differences were found for Bmax values measured at 3-hr intervals across a 24-h period, with low Bmax values during the light period and high Bmax values during the dark period. The amplitude between 03.00 and 18.00 hr was 33%. No substantial rhythm was found in the Kd values. It is suggested that the changes in the density of A1 receptors could reflect a physiologically-relevant mechanism by which adenosine exerts its modulatory role in the central nervous system.

  9. Circadian rhythm in adenosine A1 receptor of mouse cerebral cortex

    International Nuclear Information System (INIS)

    Florio, C.; Rosati, A.M.; Traversa, U.; Vertua, R.

    1991-01-01

    In order to investigate diurnal variation in adenosine A1 receptors binding parameters, Bmax and Kd values of specifically bound N6-cyclohexyl-[ 3 H]adenosine were determined in the cerebral cortex of mice that had been housed under controlled light-dark cycles for 4 weeks. Significant differences were found for Bmax values measured at 3-hr intervals across a 24-h period, with low Bmax values during the light period and high Bmax values during the dark period. The amplitude between 03.00 and 18.00 hr was 33%. No substantial rhythm was found in the Kd values. It is suggested that the changes in the density of A1 receptors could reflect a physiologically-relevant mechanism by which adenosine exerts its modulatory role in the central nervous system

  10. NCS-1 associates with adenosine A2A receptors and modulates receptor function

    Directory of Open Access Journals (Sweden)

    Gemma eNavarro

    2012-04-01

    Full Text Available Modulation of G protein-coupled receptor (GPCR signalling by local changes in intracellular calcium concentration is an established function of Calmodulin which is known to interact with many GPCRs. Less is known about the functional role of the closely related neuronal EF-hand Ca2+-sensor proteins that frequently associate with calmodulin targets with different functional outcome. In the present study we aimed to investigate if a target of calmodulin – the A2A adenosine receptor, is able to associate with two other neuronal calcium binding proteins, namely NCS-1 and caldendrin. Using bioluminescence resonance energy transfer and co-immunoprecipitation experiments we show the existence of A2A - NCS-1 complexes in living cells whereas caldendrin did not associate with A2A receptors under the conditions tested. Interestingly, NCS-1 binding modulated downstream A2A receptor intracellular signalling in a Ca2+-dependent manner. Taken together this study provides further evidence that neuronal Ca2+-sensor proteins play an important role in modulation of GPCR signalling.

  11. Untangling dopamine-adenosine receptor-receptor assembly in experimental parkinsonism in rats

    Directory of Open Access Journals (Sweden)

    Víctor Fernández-Dueñas

    2015-01-01

    Full Text Available Parkinson’s disease (PD is a dopaminergic-related pathology in which functioning of the basal ganglia is altered. It has been postulated that a direct receptor-receptor interaction – i.e. of dopamine D2 receptor (D2R with adenosine A2A receptor (A2AR (forming D2R-A2AR oligomers – finely regulates this brain area. Accordingly, elucidating whether the pathology prompts changes to these complexes could provide valuable information for the design of new PD therapies. Here, we first resolved a long-standing question concerning whether D2R-A2AR assembly occurs in native tissue: by means of different complementary experimental approaches (i.e. immunoelectron microscopy, proximity ligation assay and TR-FRET, we unambiguously identified native D2R-A2AR oligomers in rat striatum. Subsequently, we determined that, under pathological conditions (i.e. in a rat PD model, D2R-A2AR interaction was impaired. Collectively, these results provide definitive evidence for alteration of native D2R-A2AR oligomers in experimental parkinsonism, thus conferring the rationale for appropriate oligomer-based PD treatments.

  12. Therapeutic efficacy of the adenosine A1 receptor agonist N6-cyclopentyladenosine (CPA) against organophosphate intoxication

    NARCIS (Netherlands)

    Bueters, T.J.H.; Groen, B.; Danhof, M.; IJzerman, A.P.; Helden, H.P.M. van

    2002-01-01

    The objective of the present study was to investigate whether reduction of central acetylcholine (ACh) accumulation by adenosine receptor agonists could serve as a generic treatment against organophosphate (OP) poisoning. The OPs studied were tabun (O-ethyl-N-dimethylphosphoramidocyanidate), sarin

  13. Hematopoiesis in 5-Fluorouracil-Treated Adenosine A(3) Receptor Knock-Out Mice

    Czech Academy of Sciences Publication Activity Database

    Hofer, Michal; Pospíšil, Milan; Dušek, L.; Hoferová, Zuzana; Komůrková, Denisa

    2015-01-01

    Roč. 64, č. 2 (2015), s. 255-262 ISSN 0862-8408 Institutional support: RVO:68081707 Keywords : Adenosine A(3) receptor knock-out mice * Hematopoiesis * 5-fluorouracil-induced hematotoxicity Subject RIV: BO - Biophysics Impact factor: 1.643, year: 2015

  14. Adenosine concentration in the porcine coronary artery wall and A2A receptor involvement in hypoxia-induced vasodilatation.

    Science.gov (United States)

    Frøbert, Ole; Haink, Gesine; Simonsen, Ulf; Gravholt, Claus H; Levin, Max; Deussen, Andreas

    2006-01-15

    We tested whether hypoxia-induced coronary artery dilatation could be mediated by an increase in adenosine concentration within the coronary artery wall or by an increase in adenosine sensitivity. Porcine left anterior descendent coronary arteries, precontracted with prostaglandin F(2alpha) (10(-5) M), were mounted in a pressure myograph and microdialysis catheters were inserted into the tunica media. Dialysate adenosine concentrations were analysed by HPLC. Glucose, lactate and pyruvate were measured by an automated spectrophotometric kinetic enzymatic analyser. The exchange fraction of [(14)C]adenosine over the microdialysis membrane increased from 0.32 +/- 0.02 to 0.46 +/- 0.02 (n = 4, P lactate/pyruvate ratio was significantly increased in hypoxic arteries but did not correlate with adenosine concentration. We conclude that hypoxia-induced coronary artery dilatation is not mediated by increased adenosine produced within the artery wall but might be facilitated by increased adenosine sensitivity at the A(2A) receptor level.

  15. Adenosine A2B receptor: from cell biology to human diseases

    Science.gov (United States)

    Sun, Ying; Huang, Pingbo

    2016-08-01

    Extracellular adenosine is a ubiquitous signaling molecule that modulates a wide array of biological processes. Recently, significant advances have been made in our understanding of A2B adenosine receptor (A2BAR). In this review, we first summarize some of the general characteristics of A2BAR, and then we describe the multiple binding partners of the receptor, such as newly identified α-actinin-1 and p105, and discuss how these associated proteins could modulate A2BAR’s functions, including certain seemingly paradoxical functions of the receptor. Growing evidence indicates a critical role of A2BAR in cancer, renal disease, and diabetes, in addition to its importance in the regulation of vascular diseases and lung disease. Here, we also discuss the role of A2BAR in cancer, renal disease, and diabetes and the potential of the receptor as a target for treating these three diseases.

  16. The adenosine A2B receptor is involved in anion secretion in human pancreatic duct Capan-1 epithelial cells

    DEFF Research Database (Denmark)

    Hayashi, M.; Inagaki, A.; Novak, Ivana

    2016-01-01

    Adenosine modulates a wide variety of biological processes via adenosine receptors. In the exocrine pancreas, adenosine regulates transepithelial anion secretion in duct cells and is considered to play a role in acini-to-duct signaling. To identify the functional adenosine receptors and Cl......− channels important for anion secretion, we herein performed experiments on Capan-1, a human pancreatic duct cell line, using open-circuit Ussing chamber and gramicidin-perforated patch-clamp techniques. The luminal addition of adenosine increased the negative transepithelial potential difference (Vte......) in Capan-1 monolayers with a half-maximal effective concentration value of approximately 10 μM, which corresponded to the value obtained on whole-cell Cl− currents in Capan-1 single cells. The effects of adenosine on Vte, an equivalent short-circuit current (Isc), and whole-cell Cl− currents were inhibited...

  17. Modulation of short-term social memory in rats by adenosine A1 and A(2A) receptors.

    Science.gov (United States)

    Prediger, Rui D S; Takahashi, Reinaldo N

    2005-03-16

    The recognition of an unfamiliar juvenile rat by an adult rat has been shown to imply short-term memory processes. The present study was designed to examine the role of adenosine receptors in the short-term social memory of rats using the social recognition paradigm. Adenosine (5.0-10.0 mg/kg), the selective adenosine A1 receptor agonist 2-chloro-N6-cyclopentyladenosine (CCPA, 0.025-0.05 mg/kg) and the selective adenosine A(2A) receptor agonist N6-[2-(3,5-dimethoxyphenyl)-2-(2-methylphenyl)ethyl]adenosine (DPMA, 1.0-5.0 mg/kg), given by i.p. route 30 min before the test, disrupted the juvenile recognition ability of adult rats. This negative effect of adenosine (5.0 mg/kg, i.p.) on social memory was prevented by pretreatment with the non-selective adenosine receptor antagonist caffeine (10.0 mg/kg, i.p.), the adenosine A1 antagonist 8-cyclopentyl-1,3-dipropylxanthine (DPCPX, 1.0 mg/kg, i.p.) and the adenosine A(2A) antagonist 4-(2-[7-amino-2-{2-furyl}{1,2,4}triazolo-{2,3-a}{1,3,5}triazin-5-yl-amino]ethyl)phenol (ZM241385, 1.0 mg/kg, i.p.). Furthermore, acute administration of caffeine (10.0-30.0 mg/kg, i.p.), DPCPX (1.0-3.0 mg/kg, i.p.) or ZM241385 (0.5-1.0 mg/kg, i.p.) improved the short-term social memory in a specific manner. These results indicate that adenosine modulates the short-term social memory in rats by acting on both A1 and A(2A) receptors, with adenosine receptor agonists and antagonists, respectively, disrupting and enhancing the social memory.

  18. Ethanol-induced increase in portal blood flow: Role of acetate and A1- and A2-adenosine receptors

    International Nuclear Information System (INIS)

    Carmichael, F.J.; Saldivia, V.; Varghese, G.A.; Israel, Y.; Orrego, H.

    1988-01-01

    The increase in portal blood flow induced by ethanol appears to be adenosine mediated. Acetate, which is released by the liver during ethanol metabolism, is known to increase adenosine levels in tissues and in blood. The effects of acetate on portal blood flow were investigated in rats using the microsphere technique. The intravenous infusion of acetate resulted in vasodilation of the preportal vasculature and in a dose-dependent increase in portal blood flow. This acetate-induced increase in portal blood flow was suppressed by the adenosine receptor blocker, 8-phenyltheophylline. Using the A 1 -adenosine receptor agonist N-6-cyclohexyl adenosine and the A 2 -agonist 5'-N-ethylcarboxamido adenosine, we demonstrate that the effect of adenosine on the preportal vasculature is mediated by the A 2 -subtype of adenosine receptors. In conclusion, these data support the hypothesis that the increase in portal blood flow after ethanol administration results from a preportal vasodilatory effect of adenosine formed from acetate metabolism in extrahepatic tissues

  19. Phrenic motor neuron adenosine 2A receptors elicit phrenic motor facilitation.

    Science.gov (United States)

    Seven, Yasin B; Perim, Raphael R; Hobson, Orinda R; Simon, Alec K; Tadjalli, Arash; Mitchell, Gordon S

    2018-04-15

    Although adenosine 2A (A 2A ) receptor activation triggers specific cell signalling cascades, the ensuing physiological outcomes depend on the specific cell type expressing these receptors. Cervical spinal adenosine 2A (A 2A ) receptor activation elicits a prolonged facilitation in phrenic nerve activity, which was nearly abolished following intrapleural A 2A receptor siRNA injections. A 2A receptor siRNA injections selectively knocked down A 2A receptors in cholera toxin B-subunit-identified phrenic motor neurons, sparing cervical non-phrenic motor neurons. Collectively, our results support the hypothesis that phrenic motor neurons express the A 2A receptors relevant to A 2A receptor-induced phrenic motor facilitation. Upregulation of A 2A receptor expression in the phrenic motor neurons per se may potentially be a useful approach to increase phrenic motor neuron excitability in conditions such as spinal cord injury. Cervical spinal adenosine 2A (A 2A ) receptor activation elicits a prolonged increase in phrenic nerve activity, an effect known as phrenic motor facilitation (pMF). The specific cervical spinal cells expressing the relevant A 2A receptors for pMF are unknown. This is an important question since the physiological outcome of A 2A receptor activation is highly cell type specific. Thus, we tested the hypothesis that the relevant A 2A receptors for pMF are expressed in phrenic motor neurons per se versus non-phrenic neurons of the cervical spinal cord. A 2A receptor immunostaining significantly colocalized with NeuN-positive neurons (89 ± 2%). Intrapleural siRNA injections were used to selectively knock down A 2A receptors in cholera toxin B-subunit-labelled phrenic motor neurons. A 2A receptor knock-down was verified by a ∼45% decrease in A 2A receptor immunoreactivity within phrenic motor neurons versus non-targeting siRNAs (siNT; P phrenic motor neurons. In rats that were anaesthetized, subjected to neuromuscular blockade and ventilated, p

  20. Adenosine A2B and A3 receptor location at the mouse neuromuscular junction.

    Science.gov (United States)

    Garcia, Neus; Priego, Mercedes; Hurtado, Erica; Obis, Teresa; Santafe, Manel M; Tomàs, Marta; Lanuza, Maria Angel; Tomàs, Josep

    2014-07-01

    To date, four subtypes of adenosine receptors have been cloned (A(1)R, A(2A)R, A(2B)R, and A(3)R). In a previous study we used confocal immunocytochemistry to identify A(1)R and A(2A)R receptors at mouse neuromuscular junctions (NMJs). The data shows that these receptors are localized differently in the three cells (muscle, nerve and glia) that configure the NMJs. A(1)R localizes in the terminal teloglial Schwann cell and nerve terminal, whereas A(2A)R localizes in the postsynaptic muscle and in the axon and nerve terminal. Here, we use Western blotting to investigate the presence of A(2B)R and A(3)R receptors in striated muscle and immunohistochemistry to localize them in the three cells of the adult neuromuscular synapse. The data show that A(2B)R and A(3)R receptors are present in the nerve terminal and muscle cells at the NMJs. Neither A(2B)R nor A(3)R receptors are localized in the Schwann cells. Thus, the four subtypes of adenosine receptors are present in the motor endings. The presence of these receptors in the neuromuscular synapse allows the receptors to be involved in the modulation of transmitter release. © 2014 Anatomical Society.

  1. Endogenous activation of adenosine A(1) receptors accelerates ischemic suppression of spontaneous electrocortical activity

    DEFF Research Database (Denmark)

    Ilie, Andrei; Ciocan, Dragos; Zagrean, Ana-Maria

    2006-01-01

    Cerebral ischemia induces a rapid suppression of spontaneous brain rhythms prior to major alterations in ionic homeostasis. It was found in vitro during ischemia that the rapidly formed adenosine, resulting from the intracellular breakdown of ATP, may inhibit synaptic transmission via the A(1......) receptor subtype. The link between endogenous A(1) receptor activation during ischemia and the suppression of spontaneous electrocortical activity has not yet been established in the intact brain. The aim of this study was to investigate in vivo the effects of A(1) receptor antagonism by 8-cyclopentyl-1...

  2. Activation of adenosine receptors and inhibition of cyclooxygenases: two recent pharmacological approaches to modulation of radiation suppressed hematopoiesis

    International Nuclear Information System (INIS)

    Hofer, M.; Pospisil, M.; Vacek, A.; Hola, J.; Weiterova, L.; Streitova, D.; Znojil, V.

    2008-01-01

    Searching for drugs conforming to requirements for protection and/or treatment of radiation-induced damage belongs to the most important tasks of current radiobiology. In the Laboratory of Experimental Hematology, Institute of Biophysics, v.v.i., Academy of Sciences of the Czech Republic, Brno, Czech Republic, two original approaches for stimulation of radiation-suppressed hematopoiesis have been tested in recent years, namely activation of adenosine receptors and inhibition of cyclooxygenases. Non-selective activation of adenosine receptors, induced by combined administration of dipyridamole, a drug preventing adenosine uptake and supporting thus its extracellular receptor-mediated action, and adenosine monophosphate, an adenosine prodrug, has been found to stimulate hematopoiesis when the drugs were given either pre- or post-irradiation. When synthetic adenosine receptor agonists selective for individual adenosine receptor subtypes were tested, stimulatory effects in myelosuppressed mice have been found after administration of IB-MECA, a selective adenosine A3 receptor agonist. Non-selective cyclooxygenase inhibitors, inhibiting both cyclooxygenase-1 (COX-1) and cyclooxygenase-2 (COX-2), indomethacin, diclofenac, or flurbiprofen, have been observed to act positively on radiation-perturbed hematopoiesis in sublethally irradiated mice. However, their undesirable gastrointestinal side effects have been found to negatively influence survival of lethally irradiated animals. Recently tested selective COX-2 inhibitor meloxicam, preserving protective action of COX-1-synthesized prostaglandins in the gastrointestinal tissues, has been observed to retain the hematopoiesis-stimulating effects of non-selective cyclooxygenase inhibitors and to improve the survival of animals exposed to lethal radiation doses. These findings bear evidence for the possibility to use selective adenosine A3 receptor agonists and selective COX-2 inhibitors in human practice for treatment of

  3. Antitumor effect of cordycepin (3'-deoxyadenosine) on mouse melanoma and lung carcinoma cells involves adenosine A3 receptor stimulation.

    Science.gov (United States)

    Nakamura, Kazuki; Yoshikawa, Noriko; Yamaguchi, Yu; Kagota, Satomi; Shinozuka, Kazumasa; Kunitomo, Masaru

    2006-01-01

    An attempt was made to elucidate the molecular targetfor the antitumor effects of cordycepin (3'-deoxyadenosine) using non-selective and selective adenosine A1, A2a, A2b and A3 receptor agonists and antagonists. Although adenosine and 2'-deoxyadenosine (up to 100 microM) had no effect, cordycepin showed remarkable inhibitory effects on the growth curves of B16-BL6 mouse melanoma (IC50= 39 microM) and mouse Lewis lung carcinoma (IC50 = 48 microM) cell lines in vitro. Among the adenosine receptor agonists and antagonists used (up to 100 microM), only 2-chloro-N6-(3-iodobenzyl)-adenosine-5'-N-methyluronamide (Cl-IB-MECA), a selective adenosine A3 receptor agonist, notably inhibited the growth of both mouse tumor cell lines (B16-BL6; IC50 = 5 microM, LLC; 14 microM). In addition, the tumor growth inhibitory effect of cordycepin was antagonized by 3-ethyl 5-benzyl 2-methyl-6-phenyl-4-phenylethynyl-1,4-(+/-)-dihydropyridine-3,5-dicarboxylate (MRS1191), a selective adenosine A3 receptor antagonist. These results suggest that cordycepin exerts inhibitory effects on the growth of mouse melanoma and lung carcinoma cells by stimulating adenosine A3 receptors on tumor cells.

  4. The adenosine A2A receptor agonist CGS 21680 exhibits antipsychotic-like activity in Cebus apella monkeys

    DEFF Research Database (Denmark)

    Andersen, M B; Fuxe, K; Werge, T

    2002-01-01

    The adenosine A2A receptor agonist CGS 21680 has shown effects similar to dopamine antagonists in behavioural assays in rats predictive for antipsychotic activity, without induction of extrapyramidal side-effects (EPS). In the present study, we examined whether this functional dopamine antagonism...... showed a functional anti-dopaminergic effect in Cebus apella monkeys without production of EPS. This further substantiates that adenosine A2A receptor agonists may have potential as antipsychotics with atypical profiles....

  5. A2A Adenosine Receptor Antagonists as Therapeutic Candidates: are they still an interesting challenge?

    Science.gov (United States)

    Cacciari, Barbara; Federico, Stephanie; Spalluto, Giampiero

    2018-04-22

    In the past decades, many efforts were done to develope ligands for the adenosine receptors, with the purpose to individuate agonists and antagonists affine and selective for each subtypes , named A1, A2A, A2B, and A3. These intense studies allowed a deeper and deeper knowledge of the nature and, moreover, of the pathophysiological roles of all the adenosine receptor subtypes. In particular, the involvment of the A2A adenosine receptor subtype in some physiological mechanisms in the brain, that could be related to important diseases such as the Parkinson's disease, encouraged the research in this field. Particular attention was given to the antagonists endowed with high affinity and selectivity since they could have a real employment in the treatment of Parkinson's disease, and some compounds, such as istradefylline, preladenant and tozadenant, are already studied in clinical trials. Actually, the role of A2A antagonists in Parkinson's disease is becoming contradictory due to contrasting results in the last studies, but, at the same time, new possible employments are emerging for this class of antagonists in cancer pathologies as much interesting to legitimate further efforts in the research of A2A ligands. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  6. Activation of adenosine A(1) receptors alters behavioral and biochemical parameters in hyperthyroid rats.

    Science.gov (United States)

    Bruno, Alessandra Nejar; Fontella, Fernanda Urruth; Bonan, Carla Denise; Barreto-Chaves, Maria Luiza M; Dalmaz, Carla; Sarkis, João José Freitas

    2006-02-28

    Adenosine acting on A(1) receptors has been related with neuroprotective and neuromodulatory actions, protection against oxidative stress and decrease of anxiety and nociceptive signaling. Previous studies demonstrated an inhibition of the enzymes that hydrolyze ATP to adenosine in the rat central nervous system after hyperthyroidism induction. Manifestations of hyperthyroidism include increased anxiety, nervousness, high O(2) consumption and physical hyperactivity. Here, we investigated the effects of administration of a specific agonist of adenosine A(1) receptor (N(6)-cyclopentyladenosine; CPA) on nociception, anxiety, exploratory response, locomotion and brain oxidative stress of hyperthyroid rats. Hyperthyroidism was induced by daily intraperitoneal injections of l-thyroxine (T4) for 14 days. Nociception was assessed with a tail-flick apparatus and exploratory behavior, locomotion and anxiety were analyzed by open-field and plus-maze tests. We verified the total antioxidant reactivity (TAR), lipid peroxide levels by the thiobarbituric acid reactive species (TBARS) reaction and the free radicals content by the DCF test. Our results demonstrated that CPA reverted the hyperalgesia induced by hyperthyroidism and decreased the exploratory behavior, locomotion and anxiety in hyperthyroid rats. Furthermore, CPA decreased lipid peroxidation in hippocampus and cerebral cortex of control rats and in cerebral cortex of hyperthyroid rats. CPA also increased the total antioxidant reactivity in hippocampus and cerebral cortex of control and hyperthyroid rats, but the production of free radicals verified by the DCF test was changed only in cerebral cortex. These results suggest that some of the hyperthyroidism effects are subjected to regulation by adenosine A(1) receptor, demonstrating the involvement of the adenosinergic system in this pathology.

  7. Adenosine A1 receptors (A1Rs) play a critical role in osteoclast formation and function

    Science.gov (United States)

    Kara, Firas M.; Chitu, Violeta; Sloane, Jennifer; Axelrod, Matthew; Fredholm, Bertil B.; Stanley, E. Richard; Cronstein, Bruce N.

    2010-01-01

    Adenosine regulates a wide variety of physiological processes via interaction with one or more G-protein-coupled receptors (A1R, A2AR, A2BR, and A3R). Because A1R occupancy promotes fusion of human monocytes to form giant cells in vitro, we determined whether A1R occupancy similarly promotes osteoclast function and formation. Bone marrow cells (BMCs) were harvested from C57Bl/6 female mice or A1R-knockout mice and their wild-type (WT) littermates and differentiated into osteoclasts in the presence of colony stimulating factor-1 and receptor activator of NF-κB ligand in the presence or absence of the A1R antagonist 1,3-dipropyl-8-cyclopentyl xanthine (DPCPX). Osteoclast morphology was analyzed in tartrate-resistant acid phosphatase or F-actin-stained samples, and bone resorption was evaluated by toluidine blue staining of dentin. BMCs from A1R-knockout mice form fewer osteoclasts than BMCs from WT mice, and the A1R antagonist DPCPX inhibits osteoclast formation (IC50=1 nM), with altered morphology and reduced ability to resorb bone. A1R blockade increased ubiquitination and degradation of TRAF6 in RAW264.7 cells induced to differentiate into osteoclasts. These studies suggest a critical role for adenosine in bone homeostasis via interaction with adenosine A1R and further suggest that A1R may be a novel pharmacologic target to prevent the bone loss associated with inflammatory diseases and menopause.—Kara, F. M., Chitu, V., Sloane, J., Axelrod, M., Fredholm, B. B., Stanley, R., Cronstein, B. N. Adenosine A1 receptors (A1Rs) play a critical role in osteoclast formation and function. PMID:20181934

  8. Adenosine A(2A) receptors are necessary and sufficient to trigger memory impairment in adult mice.

    Science.gov (United States)

    Pagnussat, N; Almeida, A S; Marques, D M; Nunes, F; Chenet, G C; Botton, P H S; Mioranzza, S; Loss, C M; Cunha, R A; Porciúncula, L O

    2015-08-01

    Caffeine (a non-selective adenosine receptor antagonist) prevents memory deficits in aging and Alzheimer's disease, an effect mimicked by adenosine A2 A receptor, but not A1 receptor, antagonists. Hence, we investigated the effects of adenosine receptor agonists and antagonists on memory performance and scopolamine-induced memory impairment in mice. We determined whether A2 A receptors are necessary for the emergence of memory impairments induced by scopolamine and whether A2 A receptor activation triggers memory deficits in naïve mice, using three tests to assess short-term memory, namely the object recognition task, inhibitory avoidance and modified Y-maze. Scopolamine (1.0 mg·kg(-1) , i.p.) impaired short-term memory performance in all three tests and this scopolamine-induced amnesia was prevented by the A2 A receptor antagonist (SCH 58261, 0.1-1.0 mg·kg(-1) , i.p.) and by the A1 receptor antagonist (DPCPX, 0.2-5.0 mg·kg(-1) , i.p.), except in the modified Y-maze where only SCH58261 was effective. Both antagonists were devoid of effects on memory or locomotion in naïve rats. Notably, the activation of A2 A receptors with CGS 21680 (0.1-0.5 mg·kg(-1) , i.p.) before the training session was sufficient to trigger memory impairment in the three tests in naïve mice, and this effect was prevented by SCH 58261 (1.0 mg·kg(-1) , i.p.). Furthermore, i.c.v. administration of CGS 21680 (50 nmol) also impaired recognition memory in the object recognition task. These results show that A2 A receptors are necessary and sufficient to trigger memory impairment and further suggest that A1 receptors might also be selectively engaged to control the cholinergic-driven memory impairment. © 2015 The British Pharmacological Society.

  9. Human Adenosine A2A Receptor: Molecular Mechanism of Ligand Binding and Activation

    Directory of Open Access Journals (Sweden)

    Byron Carpenter

    2017-12-01

    Full Text Available Adenosine receptors (ARs comprise the P1 class of purinergic receptors and belong to the largest family of integral membrane proteins in the human genome, the G protein-coupled receptors (GPCRs. ARs are classified into four subtypes, A1, A2A, A2B, and A3, which are all activated by extracellular adenosine, and play central roles in a broad range of physiological processes, including sleep regulation, angiogenesis and modulation of the immune system. ARs are potential therapeutic targets in a variety of pathophysiological conditions, including sleep disorders, cancer, and dementia, which has made them important targets for structural biology. Over a decade of research and innovation has culminated with the publication of more than 30 crystal structures of the human adenosine A2A receptor (A2AR, making it one of the best structurally characterized GPCRs at the atomic level. In this review we analyze the structural data reported for A2AR that described for the first time the binding of mode of antagonists, including newly developed drug candidates, synthetic and endogenous agonists, sodium ions and an engineered G protein. These structures have revealed the key conformational changes induced upon agonist and G protein binding that are central to signal transduction by A2AR, and have highlighted both similarities and differences in the activation mechanism of this receptor compared to other class A GPCRs. Finally, comparison of A2AR with the recently solved structures of A1R has provided the first structural insight into the molecular determinants of ligand binding specificity in different AR subtypes.

  10. Cerebral A1 adenosine receptors (A1AR) in liver cirrhosis

    International Nuclear Information System (INIS)

    Boy, Christian; Meyer, Philipp T.; Kircheis, Gerald; Haussinger, Dieter; Holschbach, Marcus H.; Coenen, Heinz H.; Herzog, Hans; Elmenhorst, David; Kaiser, Hans J.; Zilles, Karl; Bauer, Andreas

    2008-01-01

    The cerebral mechanisms underlying hepatic encephalopathy (HE) are poorly understood. Adenosine, a neuromodulator that pre- and postsynaptically modulates neuronal excitability and release of classical neurotransmitters via A 1 adenosine receptors (A 1 AR), is likely to be involved. The present study investigates changes of cerebral A 1 AR binding in cirrhotic patients by means of positron emission tomography (PET) and [ 18 F]CPFPX, a novel selective A 1 AR antagonist. PET was performed in cirrhotic patients (n = 10) and healthy volunteers (n = 10). Quantification of in vivo receptor density was done by Logan's non-invasive graphical analysis (pons as reference region). The outcome parameter was the apparent binding potential (aBP, proportional to B max /K D ). Cortical and subcortical regions showed lower A 1 AR binding in cirrhotic patients than in controls. The aBP changes reached statistical significance vs healthy controls (p 1 AR binding may further aggravate neurotransmitter imbalance at the synaptic cleft in cirrhosis and hepatic encephalopathy. Different pathomechanisms may account for these alterations including decrease of A 1 AR density or affinity, as well as blockade of the A 1 AR by endogenous adenosine or exogenous xanthines. (orig.)

  11. The A2b adenosine receptor antagonist PSB-603 promotes oxidative phosphorylation and ROS production in colorectal cancer cells via adenosine receptor-independent mechanism.

    Science.gov (United States)

    Mølck, Christina; Ryall, James; Failla, Laura M; Coates, Janine L; Pascussi, Jean-Marc; Heath, Joan K; Stewart, Gregory; Hollande, Frédéric

    2016-12-01

    Adenosine is a multifaceted regulator of tumor progression. It modulates immune cell activity as well as acting directly on tumor cells. The A 2b adenosine receptor (A 2b -AR) is thought to be an important mediator of these effects. In this study we sought to analyze the contribution of the A 2b -AR to the behavior of colorectal cancer cells. The A 2b -AR antagonist PSB-603 changed cellular redox state without affecting cellular viability. Quantification of cellular bioenergetics demonstrated that PSB-603 increased basal oxygen consumption rates, indicative of enhanced mitochondrial oxidative phosphorylation. Unexpectedly, pharmacological and genetic approaches to antagonize AR-related signalling of PSB-603 did not abolish the response, suggesting that it was AR-independent. PSB-603 also induced acute increases in reactive oxygen species, and PSB-603 synergized with chemotherapy treatment to increase colorectal cancer cell death, consistent with the known link between cellular metabolism and chemotherapy response. PSB-603 alters cellular metabolism in colorectal cancer cells and increases their sensitivity to chemotherapy. Although requiring more mechanistic insight into its A 2b -AR-independent activity, our results show that PSB-603 may have clinical value as an anti-colorectal cancer therapeutic. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  12. A3 Adenosine Receptors Modulate Hypoxia-inducible Factor-1a Expression in Human A375 Melanoma Cells

    Directory of Open Access Journals (Sweden)

    Stefania Merighi

    2005-10-01

    Full Text Available Hypoxia-inducible factor-1 (HIF-1 is a key regulator of genes crucial to many aspects of cancer biology. The purine nucleoside, adenosine, accumulates within many tissues under hypoxic conditions, including that of tumors. Because the levels of both HIF-1 and adenosine are elevated within the hypoxic environment of solid tumors, we investigated whether adenosine may regulate HIF-1. Here we show that, under hypoxic conditions (< 2% 02, adenosine upregulates HIF-1α protein expression in a dose-dependent and timedependent manner, exclusively through the A3 receptor subtype. The response to adenosine was generated at the cell surface because the inhibition of A3 receptor expression, by using small interfering RNA, abolished nucleoside effects. A3 receptor stimulation in hypoxia also increases angiopoietin-2 (Ang-2 protein accumulation through the induction of HIF-1α. In particular, we found that A3 receptor stimulation activates p44/p42 and p38 mitogen-activated protein kinases, which are required for A3-induced increase of HIF-1a and Ang-2. Collectively, these results suggest a cooperation between hypoxic and adenosine signals that ultimately may lead to the increase in HIF-1-mediated effects in cancer cells.

  13. Synergistic Action of Presynaptic Muscarinic Acetylcholine Receptors and Adenosine Receptors in Developmental Axonal Competition at the Neuromuscular Junction.

    Science.gov (United States)

    Nadal, Laura; Garcia, Neus; Hurtado, Erica; Simó, Anna; Tomàs, Marta; Lanuza, Maria Angel; Cilleros, Victor; Tomàs, Josep Maria

    2016-01-01

    The development of the nervous system involves the initial overproduction of synapses, which promotes connectivity. Hebbian competition between axons with different activities leads to the loss of roughly half of the overproduced elements and this refines connectivity. We used quantitative immunohistochemistry to investigate, in the postnatal day 7 (P7) to P9 neuromuscular junctions, the involvement of muscarinic receptors (muscarinic acetylcholine autoreceptors and the M1, M2, and M4 subtypes) and adenosine receptors (A1 and A2A subtypes) in the control of axonal elimination after the mouse levator auris longus muscle had been exposed to selective antagonists in vivo. In a previous study we analyzed the role of each of the individual receptors. Here we investigate the additive or occlusive effects of their inhibitors and thus the existence of synergistic activity between the receptors. The main results show that the A2A, M1, M4, and A1 receptors (in this order of ability) delayed axonal elimination at P7. M4 produces some occlusion of the M1 pathway and some addition to the A1 pathway, which suggests that they cooperate. M2 receptors may modulate (by allowing a permissive action) the other receptors, mainly M4 and A1. The continued action of these receptors (now including M2 but not M4) finally promotes axonal loss at P9. All 4 receptors (M2, M1, A1, and A2A, in this order of ability) are necessary. The M4 receptor (which in itself does not affect axon loss) seems to modulate the other receptors. We found a synergistic action between the M1, A1, and A2A receptors, which show an additive effect, whereas the potent M2 effect is largely independent of the other receptors (though can be modulated by M4). At P9, there is a full mutual dependence between the A1 and A2A receptors in regulating axon loss. In summary, postnatal axonal elimination is a regulated multireceptor mechanism that involves the cooperation of several muscarinic and adenosine receptor subtypes.

  14. Roles of the adenosine receptor and CD73 in the regulatory effect of γδ T cells.

    Directory of Open Access Journals (Sweden)

    Dongchun Liang

    Full Text Available The adenosine A2A receptor (A2AR, the main functional adenosine receptor on murine T cells, plays a unique role in the attenuation of inflammation and tissue damage in vivo. Here, we showed that, of the immune cell types tested, activated γδ T cells expressed the highest levels of A2AR mRNA and that A2AR ligation inhibited αβ T cell activation, but enhanced γδ T cell activation. We also showed that the inhibitory effect of an adenosine receptor agonist on autoreactive T cells was prevented by addition of a low percentage of activated γδ T cells. Furthermore, compared to resting cells, activated γδ T cells expressed significantly lower levels of CD73, an enzyme involved in the generation of extracellular adenosine. Exogenous AMP had a significant inhibitory effect on autoreactive T cell responses, but only in the presence of CD73+ γδ T cells, and this effect was abolished by a CD73 inhibitor. Our results show that expression of increased amounts of A2AR allows γδ T cells to bind adenosine and thereby attenuate its suppressive effect, while decreased expression of CD73 results in less generation of adenosine in the inflammatory site. Together, these events allow activated γδ T cells to acquire increased proinflammatory activity, leading to augmented autoimmune responses.

  15. Basal and adenosine receptor-stimulated levels of cAMP are reduced in lymphocytes from alcoholic patients

    International Nuclear Information System (INIS)

    Diamond, I.; Wrubel, B.; Estrin, W.; Gordon, A.

    1987-01-01

    Alcoholism causes serious neurologic disease that may be due, in part, to the ability of ethanol to interact with neural cell membranes and change neuronal function. Adenosine receptors are membrane-bound proteins that appear to mediate some of the effects of ethanol in the brain. Human lymphocytes also have adenosine receptors, and their activation causes increases in cAMP levels. To test the hypothesis that basal and adenosine receptor-stimulated cAMP levels in lymphocytes might be abnormal in alcoholism, the authors studied lymphocytes from 10 alcoholic subjects, 10 age- and sex-matched normal individuals, and 10 patients with nonalcoholic liver disease. Basal and adenosine receptor-stimulated cAMP levels were reduced 75% in lymphocytes from alcoholic subjects. Also, there was a 76% reduction in ethanol stimulation of cAMP accumulation in lymphocytes from alcoholics. Similar results were demonstrable in isolated T cells. Unlike other laboratory tests examined, these measurements appeared to distinguish alcoholics from normal subjects and from patients with nonalcoholic liver disease. Reduced basal and adenosine receptor-stimulated levels of cAMP in lymphocytes from alcoholics may reflect a change in cell membranes due either to chronic alcohol abuse or to a genetic predisposition unique to alcoholic subjects

  16. Cordycepin Increases Nonrapid Eye Movement Sleep via Adenosine Receptors in Rats.

    Science.gov (United States)

    Hu, Zhenzhen; Lee, Chung-Il; Shah, Vikash Kumar; Oh, Eun-Hye; Han, Jin-Yi; Bae, Jae-Ryong; Lee, Kinam; Chong, Myong-Soo; Hong, Jin Tae; Oh, Ki-Wan

    2013-01-01

    Cordycepin (3'-deoxyadenosine) is a naturally occurring adenosine analogue and one of the bioactive constituents isolated from Cordyceps militaris/Cordyceps sinensis, species of the fungal genus Cordyceps. It has traditionally been a prized Chinese folk medicine for the human well-being. Because of similarity of chemical structure of adenosine, cordycepin has been focused on the diverse effects of the central nervous systems (CNSs), like sleep regulation. Therefore, this study was undertaken to know whether cordycepin increases the natural sleep in rats, and its effect is mediated by adenosine receptors (ARs). Sleep was recorded using electroencephalogram (EEG) for 4 hours after oral administration of cordycepin in rats. Sleep architecture and EEG power spectra were analyzed. Cordycepin reduced sleep-wake cycles and increased nonrapid eye movement (NREM) sleep. Interestingly, cordycepin increased θ (theta) waves power density during NREM sleep. In addition, the protein levels of AR subtypes (A1, A2A, and A2B) were increased after the administration of cordycepin, especially in the rat hypothalamus which plays an important role in sleep regulation. Therefore, we suggest that cordycepin increases theta waves power density during NREM sleep via nonspecific AR in rats. In addition, this experiment can provide basic evidence that cordycepin may be helpful for sleep-disturbed subjects.

  17. Cordycepin Increases Nonrapid Eye Movement Sleep via Adenosine Receptors in Rats

    Directory of Open Access Journals (Sweden)

    Zhenzhen Hu

    2013-01-01

    Full Text Available Cordycepin (3′-deoxyadenosine is a naturally occurring adenosine analogue and one of the bioactive constituents isolated from Cordyceps militaris/Cordyceps sinensis, species of the fungal genus Cordyceps. It has traditionally been a prized Chinese folk medicine for the human well-being. Because of similarity of chemical structure of adenosine, cordycepin has been focused on the diverse effects of the central nervous systems (CNSs, like sleep regulation. Therefore, this study was undertaken to know whether cordycepin increases the natural sleep in rats, and its effect is mediated by adenosine receptors (ARs. Sleep was recorded using electroencephalogram (EEG for 4 hours after oral administration of cordycepin in rats. Sleep architecture and EEG power spectra were analyzed. Cordycepin reduced sleep-wake cycles and increased nonrapid eye movement (NREM sleep. Interestingly, cordycepin increased θ (theta waves power density during NREM sleep. In addition, the protein levels of AR subtypes (A1, A2A, and A2B were increased after the administration of cordycepin, especially in the rat hypothalamus which plays an important role in sleep regulation. Therefore, we suggest that cordycepin increases theta waves power density during NREM sleep via nonspecific AR in rats. In addition, this experiment can provide basic evidence that cordycepin may be helpful for sleep-disturbed subjects.

  18. Structural Probing and Molecular Modeling of the A₃ Adenosine Receptor: A Focus on Agonist Binding.

    Science.gov (United States)

    Ciancetta, Antonella; Jacobson, Kenneth A

    2017-03-11

    Adenosine is an endogenous modulator exerting its functions through the activation of four adenosine receptor (AR) subtypes, termed A₁, A 2A , A 2B and A₃, which belong to the G protein-coupled receptor (GPCR) superfamily. The human A₃AR (hA₃AR) subtype is implicated in several cytoprotective functions. Therefore, hA₃AR modulators, and in particular agonists, are sought for their potential application as anti-inflammatory, anticancer, and cardioprotective agents. Structure-based molecular modeling techniques have been applied over the years to rationalize the structure-activity relationships (SARs) of newly emerged A₃AR ligands, guide the subsequent lead optimization, and interpret site-directed mutagenesis (SDM) data from a molecular perspective. In this review, we showcase selected modeling-based and guided strategies that were applied to elucidate the binding of agonists to the A₃AR and discuss the challenges associated with an accurate prediction of the receptor extracellular vestibule through homology modeling from the available X-ray templates.

  19. Structural Probing and Molecular Modeling of the A3 Adenosine Receptor: A Focus on Agonist Binding

    Science.gov (United States)

    Ciancetta, Antonella; Jacobson, Kenneth A.

    2017-01-01

    Adenosine is an endogenous modulator exerting its functions through the activation of four adenosine receptor (AR) subtypes, termed A1, A2A, A2B and A3, which belong to the G protein-coupled receptor (GPCR) superfamily. The human A3AR (hA3AR) subtype is implicated in several cytoprotective functions. Therefore, hA3AR modulators, and in particular agonists, are sought for their potential application as anti-inflammatory, anticancer, and cardioprotective agents. Structure-based molecular modeling techniques have been applied over the years to rationalize the structure-activity relationships (SARs) of newly emerged A3AR ligands, guide the subsequent lead optimization, and interpret site-directed mutagenesis (SDM) data from a molecular perspective. In this review, we showcase selected modeling-based and guided strategies that were applied to elucidate the binding of agonists to the A3AR and discuss the challenges associated with an accurate prediction of the receptor extracellular vestibule through homology modeling from the available X-ray templates. PMID:28287473

  20. Structural Probing and Molecular Modeling of the A3 Adenosine Receptor: A Focus on Agonist Binding

    Directory of Open Access Journals (Sweden)

    Antonella Ciancetta

    2017-03-01

    Full Text Available Adenosine is an endogenous modulator exerting its functions through the activation of four adenosine receptor (AR subtypes, termed A1, A2A, A2B and A3, which belong to the G protein-coupled receptor (GPCR superfamily. The human A3AR (hA3AR subtype is implicated in several cytoprotective functions. Therefore, hA3AR modulators, and in particular agonists, are sought for their potential application as anti-inflammatory, anticancer, and cardioprotective agents. Structure-based molecular modeling techniques have been applied over the years to rationalize the structure–activity relationships (SARs of newly emerged A3AR ligands, guide the subsequent lead optimization, and interpret site-directed mutagenesis (SDM data from a molecular perspective. In this review, we showcase selected modeling-based and guided strategies that were applied to elucidate the binding of agonists to the A3AR and discuss the challenges associated with an accurate prediction of the receptor extracellular vestibule through homology modeling from the available X-ray templates.

  1. The second extracellular loop of the adenosine A1 receptor mediates activity of allosteric enhancers.

    Science.gov (United States)

    Kennedy, Dylan P; McRobb, Fiona M; Leonhardt, Susan A; Purdy, Michael; Figler, Heidi; Marshall, Melissa A; Chordia, Mahendra; Figler, Robert; Linden, Joel; Abagyan, Ruben; Yeager, Mark

    2014-02-01

    Allosteric enhancers of the adenosine A1 receptor amplify signaling by orthosteric agonists. Allosteric enhancers are appealing drug candidates because their activity requires that the orthosteric site be occupied by an agonist, thereby conferring specificity to stressed or injured tissues that produce adenosine. To explore the mechanism of allosteric enhancer activity, we examined their action on several A1 receptor constructs, including (1) species variants, (2) species chimeras, (3) alanine scanning mutants, and (4) site-specific mutants. These findings were combined with homology modeling of the A1 receptor and in silico screening of an allosteric enhancer library. The binding modes of known docked allosteric enhancers correlated with the known structure-activity relationship, suggesting that these allosteric enhancers bind to a pocket formed by the second extracellular loop, flanked by residues S150 and M162. We propose a model in which this vestibule controls the entry and efflux of agonists from the orthosteric site and agonist binding elicits a conformational change that enables allosteric enhancer binding. This model provides a mechanism for the observations that allosteric enhancers slow the dissociation of orthosteric agonists but not antagonists.

  2. Caffeine May Reduce Perceived Sweet Taste in Humans, Supporting Evidence That Adenosine Receptors Modulate Taste.

    Science.gov (United States)

    Choo, Ezen; Picket, Benjamin; Dando, Robin

    2017-09-01

    Multiple recent reports have detailed the presence of adenosine receptors in sweet sensitive taste cells of mice. These receptors are activated by endogenous adenosine in the plasma to enhance sweet signals within the taste bud, before reporting to the primary afferent. As we commonly consume caffeine, a powerful antagonist for such receptors, in our daily lives, an intriguing question we sought to answer was whether the caffeine we habitually consume in coffee can inhibit the perception of sweet taste in humans. 107 panelists were randomly assigned to 2 groups, sampling decaffeinated coffee supplemented with either 200 mg of caffeine, about the level found in a strong cup of coffee, or an equally bitter concentration of quinine. Participants subsequently performed sensory testing, with the session repeated in the alternative condition in a second session on a separate day. Panelists rated both the sweetened coffee itself and subsequent sucrose solutions as less sweet in the caffeine condition, despite the treatment having no effect on bitter, sour, salty, or umami perception. Panelists were also unable to discern whether they had consumed the caffeinated or noncaffeinated coffee, with ratings of alertness increased equally, but no significant improvement in reaction times, highlighting coffee's powerful placebo effect. This work validates earlier observations in rodents in a human population. © 2017 Institute of Food Technologists®.

  3. 125I-labeled 8-phenylxanthine derivatives: antagonist radioligands for adenosine A1 receptors

    International Nuclear Information System (INIS)

    Linden, J.; Patel, A.; Earl, C.Q.; Craig, R.H.; Daluge, S.M.

    1988-01-01

    A series of 8-phenylxanthine derivatives has been synthesized with oxyacetic acid on the para phenyl position to increase aqueous solubility and minimize nonspecific binding and iodinatable groups on the 1- or 3-position of the xanthine ring. The structure-activity relationship for binding of these compounds to A1 adenosine receptors of bovine and rat brain and A2 receptors of human platelets was examined. The addition of arylamine or photosensitive aryl azide groups to the 3-position of xanthine had little effect on A1 binding affinity with or without iodination, whereas substitutions at the 1-position caused greatly reduced A1 binding affinity. The addition of an aminobenzyl group to the 3-position of the xanthine had little effect on A2 binding affinity, but 3-aminophenethyl substitution decreased A2 binding affinity. Two acidic 3-(arylamino)-8-phenylxanthine derivatives were labeled with 125 I and evaluated as A1 receptor radioligands. The new radioligands bound to A1 receptors with KD values of 1-1.25 nM. Specific binding represented over 80% of total binding. High concentrations of NaCl or other salts increased the binding affinity of acidic but not neutral antagonists, suggesting that interactions between ionized xanthines and receptors may be affected significantly by changes in ionic strength. On the basis of binding studies with these antagonists and isotope dilution with the agonist [ 125 I]N6-(4-amino-3-iodobenzyl)adenosine, multiple agonist affinity states of A1 receptors have been identified

  4. Adenosine A1 receptors (A1Rs) play a critical role in osteoclast formation and function

    OpenAIRE

    Kara, Firas M.; Chitu, Violeta; Sloane, Jennifer; Axelrod, Matthew; Fredholm, Bertil B.; Stanley, E. Richard; Cronstein, Bruce N.

    2010-01-01

    Adenosine regulates a wide variety of physiological processes via interaction with one or more G-protein-coupled receptors (A1R, A2AR, A2BR, and A3R). Because A1R occupancy promotes fusion of human monocytes to form giant cells in vitro, we determined whether A1R occupancy similarly promotes osteoclast function and formation. Bone marrow cells (BMCs) were harvested from C57Bl/6 female mice or A1R-knockout mice and their wild-type (WT) littermates and differentiated into osteoclasts in the pre...

  5. Adenosine A2b receptor promotes progression of human oral cancer

    International Nuclear Information System (INIS)

    Kasama, Hiroki; Sakamoto, Yosuke; Kasamatsu, Atsushi; Okamoto, Atsushi; Koyama, Tomoyoshi; Minakawa, Yasuyuki; Ogawara, Katsunori; Yokoe, Hidetaka; Shiiba, Masashi; Tanzawa, Hideki; Uzawa, Katsuhiro

    2015-01-01

    Adenosine A2b receptor (ADORA2B) encodes an adenosine receptor that is a member of the G protein-coupled receptor superfamily. This integral membrane protein stimulates adenylate cyclase activity in the presence of adenosine. Little is known about the relevance of ADORA2B to human malignancy including oral squamous cell carcinoma (OSCC). We aimed to characterize the expression state and function of ADORA2B in OSCC. The ADORA2B expression levels in nine OSCC-derived cells were analyzed by quantitative reverse transcriptase-polymerase chain reaction and immunoblotting analyses. Using an ADORA2B knockdown model, we assessed cellular proliferation and expression of hypoxia-inducible factor1α (HIF-1α). We examined the adenosine receptor expression profile under both normoxic and hypoxic conditions in the OSCC-derived cells. In addition to in vitro data, the clinical correlation between the ADORA2B expression levels in primary OSCCs (n = 100 patients) and the clinicopathological status by immunohistochemistry (IHC) also was evaluated. ADORA2B mRNA and protein were up-regulated significantly (p < 0.05) in seven OSCC-derived cells compared with human normal oral keratinocytes. Suppression of ADORA2B expression with shRNA significantly (p < 0.05) inhibited cellular proliferation compared with the control cells. HIF-1α also was down-regulated in ADORA2B knockdown OSCC cells. During hypoxia, ADORA2B expression was induced significantly (p < 0.05) in the mRNA and protein after 24 hours of incubation in OSCC-derived cells. IHC showed that ADORA2B expression in primary OSCCs was significantly (p < 0.05) greater than in the normal oral counterparts and that ADORA2B-positive OSCCs were correlated closely (p < 0.05) with tumoral size. Our results suggested that ADORA2B controls cellular proliferation via HIF-1α activation, indicating that ADORA2B may be a key regulator of tumoral progression in OSCCs. The online version of this article (doi:10.1186/s12885-015-1577-2) contains

  6. The importance of the adenosine A(2A) receptor-dopamine D(2) receptor interaction in drug addiction.

    Science.gov (United States)

    Filip, M; Zaniewska, M; Frankowska, M; Wydra, K; Fuxe, K

    2012-01-01

    Drug addiction is a serious brain disorder with somatic, psychological, psychiatric, socio-economic and legal implications in the developed world. Illegal (e.g., psychostimulants, opioids, cannabinoids) and legal (alcohol, nicotine) drugs of abuse create a complex behavioral pattern composed of drug intake, withdrawal, seeking and relapse. One of the hallmarks of drugs that are abused by humans is that they have different mechanisms of action to increase dopamine (DA) neurotransmission within the mesolimbic circuitry of the brain and indirectly activate DA receptors. Among the DA receptors, D(2) receptors are linked to drug abuse and addiction because their function has been proven to be correlated with drug reinforcement and relapses. The recognition that D(2) receptors exist not only as homomers but also can form heteromers, such as with the adenosine (A)(2A) receptor, that are pharmacologically and functionally distinct from their constituent receptors, has significantly expanded the range of potential drug targets and provided new avenues for drug design in the search for novel drug addiction therapies. The aim of this review is to bring current focus on A(2A) receptors, their physiology and pharmacology in the central nervous system, and to discuss the therapeutic relevance of these receptors to drug addiction. We concentrate on the contribution of A(2A) receptors to the effects of different classes of drugs of abuse examined in preclinical behavioral experiments carried out with pharmacological and genetic tools. The consequences of chronic drug treatment on A(2A) receptor-assigned functions in preclinical studies are also presented. Finally, the neurochemical mechanism of the interaction between A(2A) receptors and drugs of abuse in the context of the heteromeric A(2A)-D(2) receptor complex is discussed. Taken together, a significant amount of experimental analyses provide evidence that targeting A(2A) receptors may offer innovative translational strategies

  7. Cerebral A{sub 1} adenosine receptors (A{sub 1}AR) in liver cirrhosis

    Energy Technology Data Exchange (ETDEWEB)

    Boy, Christian [Research Centre Juelich, Brain Imaging Centre West, Institute of Medicine, Juelich (Germany); University Hospital Essen, Department of Nuclear Medicine, Essen (Germany); Meyer, Philipp T. [Research Centre Juelich, Brain Imaging Centre West, Institute of Medicine, Juelich (Germany); University Hospital Aachen, Department of Nuclear Medicine, Aachen (Germany); Kircheis, Gerald; Haussinger, Dieter [University of Duesseldorf, Clinic for Gastroenterology, Hepatology and Infectiology, Duesseldorf (Germany); Holschbach, Marcus H.; Coenen, Heinz H. [Research Centre Juelich, Institute of Nuclear Chemistry, Juelich (Germany); Herzog, Hans; Elmenhorst, David [Research Centre Juelich, Brain Imaging Centre West, Institute of Medicine, Juelich (Germany); Kaiser, Hans J. [University Hospital Aachen, Department of Nuclear Medicine, Aachen (Germany); Zilles, Karl [Research Centre Juelich, Brain Imaging Centre West, Institute of Medicine, Juelich (Germany); C. and O. Vogt Institute of Brain Research, Duesseldorf (Germany); Bauer, Andreas [Research Centre Juelich, Brain Imaging Centre West, Institute of Medicine, Juelich (Germany); University of Duesseldorf, Department of Neurology, Duesseldorf (Germany)

    2008-03-15

    The cerebral mechanisms underlying hepatic encephalopathy (HE) are poorly understood. Adenosine, a neuromodulator that pre- and postsynaptically modulates neuronal excitability and release of classical neurotransmitters via A{sub 1} adenosine receptors (A{sub 1}AR), is likely to be involved. The present study investigates changes of cerebral A{sub 1}AR binding in cirrhotic patients by means of positron emission tomography (PET) and [{sup 18}F]CPFPX, a novel selective A{sub 1}AR antagonist. PET was performed in cirrhotic patients (n = 10) and healthy volunteers (n = 10). Quantification of in vivo receptor density was done by Logan's non-invasive graphical analysis (pons as reference region). The outcome parameter was the apparent binding potential (aBP, proportional to B{sub max}/K{sub D}). Cortical and subcortical regions showed lower A{sub 1}AR binding in cirrhotic patients than in controls. The aBP changes reached statistical significance vs healthy controls (p < 0.05, U test with Bonferroni-Holm adjustment for multiple comparisons) in cingulate cortex (-50.0%), precentral gyrus (-40.9%), postcentral gyrus (-38.6%), insular cortex (-38.6%), thalamus (-32.9%), parietal cortex (-31.7%), frontal cortex (-28.6), lateral temporal cortex (-28.2%), orbitofrontal cortex (-27.9%), occipital cortex (-24.6), putamen (-22.7%) and mesial temporal lobe (-22.4%). Regional cerebral adenosinergic neuromodulation is heterogeneously altered in cirrhotic patients. The decrease of cerebral A{sub 1}AR binding may further aggravate neurotransmitter imbalance at the synaptic cleft in cirrhosis and hepatic encephalopathy. Different pathomechanisms may account for these alterations including decrease of A{sub 1}AR density or affinity, as well as blockade of the A{sub 1}AR by endogenous adenosine or exogenous xanthines. (orig.)

  8. Adenosine Receptors in Developing and Adult Mouse Neuromuscular Junctions and Functional Links With Other Metabotropic Receptor Pathways.

    Science.gov (United States)

    Tomàs, Josep; Garcia, Neus; Lanuza, Maria A; Santafé, Manel M; Tomàs, Marta; Nadal, Laura; Hurtado, Erica; Simó-Ollé, Anna; Cilleros-Mañé, Víctor; Just-Borràs, Laia

    2018-01-01

    In the last few years, we have studied the presence and involvement in synaptogenesis and mature transmitter release of the adenosine autoreceptors (AR) in the mammalian neuromuscular junction (NMJ). Here, we review and bring together the previously published data to emphasize the relevance of these receptors for developmental axonal competition, synaptic loss and mature NMJ functional modulation. However, in addition to AR, activity-dependent mediators originating from any of the three cells that make the synapse (nerve, muscle, and glial cells) cross the extracellular cleft to generate signals in target metabotropic receptors. Thus, the integrated interpretation of the complementary function of all these receptors is needed. We previously studied, in the NMJ, the links of AR with mAChR and the neurotrophin receptor TrkB in the control of synapse elimination and transmitter release. We conclude that AR cooperate with these receptors through synergistic and antagonistic effects in the developmental synapse elimination process. In the adult NMJ, this cooperation is manifested so as that the functional integrity of a given receptor group depends on the other receptors operating normally (i.e., the functional integrity of mAChR depends on AR operating normally). These observations underlie the relevance of AR in the NMJ function.

  9. Adenosine Receptors in Developing and Adult Mouse Neuromuscular Junctions and Functional Links With Other Metabotropic Receptor Pathways

    Directory of Open Access Journals (Sweden)

    Josep Tomàs

    2018-04-01

    Full Text Available In the last few years, we have studied the presence and involvement in synaptogenesis and mature transmitter release of the adenosine autoreceptors (AR in the mammalian neuromuscular junction (NMJ. Here, we review and bring together the previously published data to emphasize the relevance of these receptors for developmental axonal competition, synaptic loss and mature NMJ functional modulation. However, in addition to AR, activity-dependent mediators originating from any of the three cells that make the synapse (nerve, muscle, and glial cells cross the extracellular cleft to generate signals in target metabotropic receptors. Thus, the integrated interpretation of the complementary function of all these receptors is needed. We previously studied, in the NMJ, the links of AR with mAChR and the neurotrophin receptor TrkB in the control of synapse elimination and transmitter release. We conclude that AR cooperate with these receptors through synergistic and antagonistic effects in the developmental synapse elimination process. In the adult NMJ, this cooperation is manifested so as that the functional integrity of a given receptor group depends on the other receptors operating normally (i.e., the functional integrity of mAChR depends on AR operating normally. These observations underlie the relevance of AR in the NMJ function.

  10. Cross sectional PET study of cerebral adenosine A1 receptors in premanifest and manifest Huntington's disease

    International Nuclear Information System (INIS)

    Matusch, Andreas; Elmenhorst, David; Saft, Carsten; Kraus, Peter H.; Gold, Ralf; Hartung, Hans-Peter; Bauer, Andreas

    2014-01-01

    To study cerebral adenosine receptors (AR) in premanifest and manifest stages of Huntington's disease (HD). We quantified the cerebral binding potential (BP ND ) of the A 1 AR in carriers of the HD CAG trinucleotide repeat expansion using the radioligand [ 18 F]CPFPX and PET. Four groups were investigated: (i) premanifest individuals far (preHD-A; n = 7) or (ii) near (preHD-B; n = 6) to the predicted symptom onset, (iii) manifest HD patients (n = 8), and (iv) controls (n = 36). Cerebral A 1 AR values of preHD-A subjects were generally higher than those of controls (by up to 31 %, p 1 AR BP ND was observed to the levels of controls in preHD-B and undercutting controls in manifest HD by down to 25 %, p 1 AR BP ND and years to onset. Before onset of HD, the assumed annual rates of change of A 1 AR density were -1.2 % in the caudatus, -1.7 % in the thalamus and -3.4 % in the amygdala, while the corresponding volume losses amounted to 0.6 %, 0.1 % and 0.2 %, respectively. Adenosine receptors switch from supra to subnormal levels during phenoconversion of HD. This differential regulation may play a role in the pathophysiology of altered energy metabolism. (orig.)

  11. Effect of adenosine1-receptor blockade on renin release from rabbit isolated perfused juxtaglomerular apparatus

    DEFF Research Database (Denmark)

    Weihprecht, H; Lorenz, J N; Schnermann, J

    1990-01-01

    Adenosine has been proposed to act within the juxtaglomerular apparatus (JGA) as a mediator of the inhibition of renin secretion produced by a high NaCl concentration at the macula densa. To test this hypothesis, we studied the effects of the adenosine1 (A1)-receptor blocker 8-cyclopentyl-1......,3-dipropylxanthine (CPX) on renin release from single isolated rabbit JGAs with macula densa perfused. The A1-receptor agonist, N6-cyclohexyladenosine (CHA), applied in the bathing solution at 10(-7) M, was found to inhibit renin secretion, an effect that was completely blocked by adding CPX (10(-5) M) to the bath....... Applied to the lumen, 10(-5) M CPX produced a modest stimulation of renin secretion rates suppressed by a high NaCl concentration at the macula densa (P less than 0.05). The effect of changing luminal NaCl concentration on renin secretion rate was examined in the presence of CPX (10(-7) and 10(-5) M...

  12. Adenosine activates brown adipose tissue and recruits beige adipocytes via A2A receptors

    DEFF Research Database (Denmark)

    Gnad, Thorsten; Scheibler, Saskia; von Kügelgen, Ivar

    2014-01-01

    hamster or rat. However, the role of adenosine in human BAT is unknown. Here we show that adenosine activates human and murine brown adipocytes at low nanomolar concentrations. Adenosine is released in BAT during stimulation of sympathetic nerves as well as from brown adipocytes. The adenosine A2A...

  13. Regulation of Hippocampal Cannabinoid CB1 Receptor Actions by Adenosine A1 Receptors and Chronic Caffeine Administration: Implications for the Effects of Δ9-Tetrahydrocannabinol on Spatial Memory

    OpenAIRE

    Sousa, Vasco C; Assaife-Lopes, Natália; Ribeiro, Joaquim A; Pratt, Judith A; Brett, Ros R; Sebastião, Ana M

    2010-01-01

    Abstract The cannabinoid CB1 receptor-mediated modulation of ?-aminobutyric acid (GABA) release from inhibitory interneurons is important for the integrity of hippocampal-dependent spatial memory. Although adenosine A1 receptors have a central role in fine-tuning excitatory transmission in the hippocampus, A1 receptors localized in GABAergic cells do not directly influence GABA release. CB1 and A1 receptors are the main targets for the effects of two of the most heavily consumed ps...

  14. The macrophage A2B adenosine receptor regulates tissue insulin sensitivity.

    Directory of Open Access Journals (Sweden)

    Hillary Johnston-Cox

    Full Text Available High fat diet (HFD-induced type 2 diabetes continues to be an epidemic with significant risk for various pathologies. Previously, we identified the A2b adenosine receptor (A2bAR, an established regulator of inflammation, as a regulator of HFD-induced insulin resistance. In particular, HFD was associated with vast upregulation of liver A2bAR in control mice, and while mice lacking this receptor showed augmented liver inflammation and tissue insulin resistance. As the A2bAR is expressed in different tissues, here, we provide the first lead to cellular mechanism by demonstrating that the receptor's influence on tissue insulin sensitivity is mediated via its expression in macrophages. This was shown using a newly generated transgenic mouse model expressing the A2bAR gene in the macrophage lineage on an otherwise A2bAR null background. Reinstatement of macrophage A2bAR expression in A2bAR null mice fed HFD restored insulin tolerance and tissue insulin signaling to the level of control mice. The molecular mechanism for this effect involves A2bAR-mediated changes in cyclic adenosine monophosphate in macrophages, reducing the expression and release of inflammatory cytokines, which downregulate insulin receptor-2. Thus, our results illustrate that macrophage A2bAR signaling is needed and sufficient for relaying the protective effect of the A2bAR against HFD-induced tissue inflammation and insulin resistance in mice.

  15. Adenosine A2A receptors in ventral striatum, hypothalamus and nociceptive circuitry. Implications for drug addiction, sleep and pain

    Science.gov (United States)

    Ferré, S.; Diamond, I.; Goldberg, S.R.; Yao, L.; Hourani, S.M.O.; Huang, Z.L.; Urade, Y.; Kitchen, I.

    2007-01-01

    Adenosine A2A receptors localized in the dorsal striatum are considered as a new target for the development of antiparkinsonian drugs. Co-administration of A2A receptor antagonists has shown a significant improvement of the effects of L-DOPA. The present review emphasizes the possible application of A2A receptor antagonists in pathological conditions other than parkinsonism, including drug addiction, sleep disorders and pain. In addition to the dorsal striatum, the ventral striatum (nucleus accumbens) contains a high density of A2A receptors, which presynaptically and postsynaptically regulate glutamatergic transmission in the cortical glutamatergic projections to the nucleus accumbens. It is currently believed that molecular adaptations of the cortico-accumbens glutamatergic synapses are involved in compulsive drug seeking and relapse. Here we review recent experimental evidence suggesting that A2A antagonists could become new therapeutic agents for drug addiction. Morphological and functional studies have identified lower levels of A2A receptors in brain areas other than the striatum, such as the ventrolateral preoptic area of the hypothalamus, where adenosine plays an important role in sleep regulation. Although initially believed to be mostly dependent on A1 receptors, here we review recent studies that demonstrate that the somnogenic effects of adenosine are largely mediated by hypothalamic A2A receptors. A2A receptor antagonists could therefore be considered as a possible treatment for narcolepsy and other sleep-related disorders. Finally, nociception is another adenosine-regulated neural function previously thought to mostly involve A1 receptors. Although there is some conflicting literature on the effects of agonists and antagonists, which may partly be due to the lack of selectivity of available drugs, the studies in A2A receptor knockout mice suggest that A2A receptor antagonists might have some therapeutic potential in pain states, in particular where

  16. Adenosine A2B Receptors: An Optional Target for the Management of Irritable Bowel Syndrome with Diarrhea?

    Directory of Open Access Journals (Sweden)

    Teita Asano

    2017-11-01

    Full Text Available Irritable bowel syndrome (IBS is a functional gastrointestinal disorder, with the characteristic symptoms of chronic abdominal pain and altered bowel habits (diarrhea, constipation, or both. IBS is a highly prevalent condition, which negatively affects quality of life and is a significant burden on global healthcare costs. Although many pharmacological medicines have been proposed to treat IBS, including those targeting receptors, channels, and chemical mediators related to visceral hypersensitivity, successful pharmacotherapy for the disease has not been established. Visceral hypersensitivity plays an important role in IBS pathogenesis. Immune activation is observed in diarrhea-predominant patients with IBS and contributes to the development of visceral hypersensitivity. Adenosine is a chemical mediator that regulates many physiological processes, including inflammation and nociception. Among its receptors, the adenosine A2B receptor regulates intestinal secretion, motor function, and the immune response. We recently demonstrated that the adenosine A2B receptor is involved in visceral hypersensitivity in animal models of IBS. In this review, we discuss the possibility of the adenosine A2B receptor as a novel therapeutic target for IBS.

  17. Activation of adenosine low-affinity A3 receptors inhibits the enteric short interplexus neural circuit triggered by histamine.

    Science.gov (United States)

    Bozarov, Andrey; Wang, Yu-Zhong; Yu, Jun Ge; Wunderlich, Jacqueline; Hassanain, Hamdy H; Alhaj, Mazin; Cooke, Helen J; Grants, Iveta; Ren, Tianhua; Christofi, Fievos L

    2009-12-01

    We tested the novel hypothesis that endogenous adenosine (eADO) activates low-affinity A3 receptors in a model of neurogenic diarrhea in the guinea pig colon. Dimaprit activation of H2 receptors was used to trigger a cyclic coordinated response of contraction and Cl(-) secretion. Contraction-relaxation was monitored by sonomicrometry (via intracrystal distance) simultaneously with short-circuit current (I(sc), Cl(-) secretion). The short interplexus reflex coordinated response was attenuated or abolished by antagonists at H2 (cimetidine), 5-hydroxytryptamine 4 receptor (RS39604), neurokinin-1 receptor (GR82334), or nicotinic (mecamylamine) receptors. The A1 agonist 2-chloro-N(6)-cyclopentyladenosine (CCPA) abolished coordinated responses, and A1 antagonists could restore normal responses. A1-selective antagonists alone [8-cyclopentyltheophylline (CPT), 1,3-dipropyl-8-(2-amino-4-chlorophenyl)xanthine (PACPX), or 8-cyclopentyl-N(3)-[3-(4-(fluorosulfonyl)benzoyloxy)propyl]-xanthine (FSCPX)] caused a concentration-dependent augmentation of crypt cell secretion or contraction and acted at nanomolar concentrations. The A3 agonist N(6)-(3-iodobenzyl)-adenosine-5'-N-methyluronamide (IB-MECA) abolished coordinated responses and the A3 antagonist 3-ethyl-5-benzyl-2-methyl-4-phenylethynyl-6-phenyl-1,4-(+/-)-dihydropyridine-3,5-dicarboxylate (MRS1191) could restore and further augment responses. The IB-MECA effect was resistant to knockdown of adenosine A1 receptor with the irreversible antagonist FSCPX; the IC(50) for IB-MECA was 0.8 microM. MRS1191 alone could augment or unmask coordinated responses to dimaprit, and IB-MECA suppressed them. MRS1191 augmented distension-evoked reflex I(sc) responses. Adenosine deaminase mimicked actions of adenosine receptor antagonists. A3 receptor immunoreactivity was differentially expressed in enteric neurons of different parts of colon. After tetrodotoxin, IB-MECA caused circular muscle relaxation. The data support the novel concept that

  18. Allosteric interactions between agonists and antagonists within the adenosine A2A receptor-dopamine D2 receptor heterotetramer.

    Science.gov (United States)

    Bonaventura, Jordi; Navarro, Gemma; Casadó-Anguera, Verònica; Azdad, Karima; Rea, William; Moreno, Estefanía; Brugarolas, Marc; Mallol, Josefa; Canela, Enric I; Lluís, Carme; Cortés, Antoni; Volkow, Nora D; Schiffmann, Serge N; Ferré, Sergi; Casadó, Vicent

    2015-07-07

    Adenosine A2A receptor (A2AR)-dopamine D2 receptor (D2R) heteromers are key modulators of striatal neuronal function. It has been suggested that the psychostimulant effects of caffeine depend on its ability to block an allosteric modulation within the A2AR-D2R heteromer, by which adenosine decreases the affinity and intrinsic efficacy of dopamine at the D2R. We describe novel unsuspected allosteric mechanisms within the heteromer by which not only A2AR agonists, but also A2AR antagonists, decrease the affinity and intrinsic efficacy of D2R agonists and the affinity of D2R antagonists. Strikingly, these allosteric modulations disappear on agonist and antagonist coadministration. This can be explained by a model that considers A2AR-D2R heteromers as heterotetramers, constituted by A2AR and D2R homodimers, as demonstrated by experiments with bioluminescence resonance energy transfer and bimolecular fluorescence and bioluminescence complementation. As predicted by the model, high concentrations of A2AR antagonists behaved as A2AR agonists and decreased D2R function in the brain.

  19. Antinociception by systemically-administered acetaminophen (paracetamol) involves spinal serotonin 5-HT7 and adenosine A1 receptors, as well as peripheral adenosine A1 receptors.

    Science.gov (United States)

    Liu, Jean; Reid, Allison R; Sawynok, Jana

    2013-03-01

    Acetaminophen (paracetamol) is a widely used analgesic, but its sites and mechanisms of action remain incompletely understood. Recent studies have separately implicated spinal adenosine A(1) receptors (A(1)Rs) and serotonin 5-HT(7) receptors (5-HT(7)Rs) in the antinociceptive effects of systemically administered acetaminophen. In the present study, we determined whether these two actions are linked by delivering a selective 5-HT(7)R antagonist to the spinal cord of mice and examining nociception using the formalin 2% model. In normal and A(1)R wild type mice, antinociception by systemic (i.p.) acetaminophen 300mg/kg was reduced by intrathecal (i.t.) delivery of the selective 5-HT(7)R antagonist SB269970 3μg. In mice lacking A(1)Rs, i.t. SB269970 did not reverse antinociception by systemic acetaminophen, indicating a link between spinal 5-HT(7)R and A(1)R mechanisms. We also explored potential roles of peripheral A(1)Rs in antinociception by acetaminophen administered both locally and systemically. In normal mice, intraplantar (i.pl.) acetaminophen 200μg produced antinociception in the formalin test, and this was blocked by co-administration of the selective A(1)R antagonist DPCPX 4.5μg. Acetaminophen administered into the contralateral hindpaw had no effect, indicating a local peripheral action. When acetaminophen was administered systemically, its antinociceptive effect was reversed by i.pl. DPCPX in normal mice; this was also observed in A(1)R wild type mice, but not in those lacking A(1)Rs. In summary, we demonstrate a link between spinal 5-HT(7)Rs and A(1)Rs in the spinal cord relevant to antinociception by systemic acetaminophen. Furthermore, we implicate peripheral A(1)Rs in the antinociceptive effects of locally- and systemically-administered acetaminophen. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

  20. Adenosine A2A receptors and A2A receptor heteromers as key players in striatal function

    Directory of Open Access Journals (Sweden)

    Sergi eFerre

    2011-06-01

    Full Text Available A very significant density of adenosine adenosine A2A receptors (A2ARs is present in the striatum, where they are preferentially localized postsynaptically in striatopallidal medium spiny neurons (MSNs. In this localization A2ARs establish reciprocal antagonistic interactions with dopamine D2 receptors (D2Rs. In one type of interaction, A2AR and D2R are forming heteromers and, by means of an allosteric interaction, A2AR counteracts D2R-mediated inhibitory modulation of the effects of NMDA receptor stimulation in the striato-pallidal neuron. This interaction is probably mostly responsible for the locomotor depressant and activating effects of A2AR agonist and antagonists, respectively. The second type of interaction involves A2AR and D2R that do not form heteromers and takes place at the level of adenylyl-cyclase (AC. Due to a strong tonic effect of endogenous dopamine on striatal D2R, this interaction keeps A2AR from signaling through AC. However, under conditions of dopamine depletion or with blockade of D2R, A2AR-mediated AC activation is unleashed with an increased gene expression and activity of the striato-pallidal neuron and with a consequent motor depression. This interaction is probably the main mechanism responsible for the locomotor depression induced by D2R antagonists. Finally, striatal A2ARs are also localized presynaptically, in cortico-striatal glutamatergic terminals that contact the striato-nigral MSN. These presynaptic A2ARs heteromerize with A1 receptors (A1Rs and their activation facilitates glutamate release. These three different types of A2ARs can be pharmacologically dissected by their ability to bind ligands with different affinity and can therefore provide selective targets for drug development in different basal ganglia disorders.

  1. Overexpression of adenosine A2A receptors in rats: effects on depression, locomotion and anxiety

    Directory of Open Access Journals (Sweden)

    Joana E Coelho

    2014-06-01

    Full Text Available Adenosine A2A receptors (A2AR are a sub-type of receptors enriched in basal ganglia, activated by the neuromodulator adenosine, which interact with dopamine D2 receptors. Although this reciprocal antagonistic interaction is well established in motor function, the outcome in dopamine-related behaviors remains uncertain, in particular in depression and anxiety. We have demonstrated an upsurge of A2AR associated to aging and chronic stress. Furthermore, Alzheimer’s disease patients present A2AR accumulation in cortical areas together with depressive signs. We now tested the impact of overexpressing A2AR in forebrain neurons on dopamine related behavior, namely depression. Adult male rats overexpressing human A2AR under the control of CaMKII promoter [Tg(CaMKII-hA2AR] and aged-matched wild-types (WT of the same strain (Sprague-Dawley were studied. The forced swimming test (FST, sucrose preference test (SPT and the open-field test (OFT were performed to evaluate behavioral despair, anhedonia, locomotion and anxiety. Tg(CaMKII-hA2AR animals spent more time floating and less time swimming in the FST and presented a decreased sucrose preference at 48h in the SPT. They also covered higher distances in the OFT and spent more time in the central zone than the WT. The results indicate that Tg(CaMKII-hA2AR rats exhibit depressive-like behavior, hyperlocomotion and altered exploratory behavior. This A2AR overexpression may explain the depressive signs found in aging, chronic stress and Alzheimer’s disease.

  2. Overexpression of Adenosine A2A Receptors in Rats: Effects on Depression, Locomotion, and Anxiety.

    Science.gov (United States)

    Coelho, Joana E; Alves, Pedro; Canas, Paula M; Valadas, Jorge S; Shmidt, Tatiana; Batalha, Vânia L; Ferreira, Diana G; Ribeiro, Joaquim A; Bader, Michael; Cunha, Rodrigo A; do Couto, Frederico Simões; Lopes, Luísa V

    2014-01-01

    Adenosine A2A receptors (A2AR) are a sub-type of receptors enriched in basal ganglia, activated by the neuromodulator adenosine, which interact with dopamine D2 receptors. Although this reciprocal antagonistic interaction is well-established in motor function, the outcome in dopamine-related behaviors remains uncertain, in particular in depression and anxiety. We have demonstrated an upsurge of A2AR associated to aging and chronic stress. Furthermore, Alzheimer's disease patients present A2AR accumulation in cortical areas together with depressive signs. We now tested the impact of overexpressing A2AR in forebrain neurons on dopamine-related behavior, namely depression. Adult male rats overexpressing human A2AR under the control of CaMKII promoter [Tg(CaMKII-hA2AR)] and aged-matched wild-types (WT) of the same strain (Sprague-Dawley) were studied. The forced swimming test (FST), sucrose preference test (SPT), and the open-field test (OFT) were performed to evaluate behavioral despair, anhedonia, locomotion, and anxiety. Tg(CaMKII-hA2AR) animals spent more time floating and less time swimming in the FST and presented a decreased sucrose preference at 48 h in the SPT. They also covered higher distances in the OFT and spent more time in the central zone than the WT. The results indicate that Tg(CaMKII-hA2AR) rats exhibit depressive-like behavior, hyperlocomotion, and altered exploratory behavior. This A2AR overexpression may explain the depressive signs found in aging, chronic stress, and Alzheimer's disease.

  3. Chronic sleep restriction induces long-lasting changes in adenosine and noradrenaline receptor density in the rat brain.

    Science.gov (United States)

    Kim, Youngsoo; Elmenhorst, David; Weisshaupt, Angela; Wedekind, Franziska; Kroll, Tina; McCarley, Robert W; Strecker, Robert E; Bauer, Andreas

    2015-10-01

    Although chronic sleep restriction frequently produces long-lasting behavioural and physiological impairments in humans, the underlying neural mechanisms are unknown. Here we used a rat model of chronic sleep restriction to investigate the role of brain adenosine and noradrenaline systems, known to regulate sleep and wakefulness, respectively. The density of adenosine A1 and A2a receptors and β-adrenergic receptors before, during and following 5 days of sleep restriction was assessed with autoradiography. Rats (n = 48) were sleep-deprived for 18 h day(-1) for 5 consecutive days (SR1-SR5), followed by 3 unrestricted recovery sleep days (R1-R3). Brains were collected at the beginning of the light period, which was immediately after the end of sleep deprivation on sleep restriction days. Chronic sleep restriction increased adenosine A1 receptor density significantly in nine of the 13 brain areas analysed with elevations also observed on R3 (+18 to +32%). In contrast, chronic sleep restriction reduced adenosine A2a receptor density significantly in one of the three brain areas analysed (olfactory tubercle which declined 26-31% from SR1 to R1). A decrease in β-adrenergic receptors density was seen in substantia innominata and ventral pallidum which remained reduced on R3, but no changes were found in the anterior cingulate cortex. These data suggest that chronic sleep restriction can induce long-term changes in the brain adenosine and noradrenaline receptors, which may underlie the long-lasting neurocognitive impairments observed in chronic sleep restriction. © 2015 European Sleep Research Society.

  4. Communication over the network of binary switches regulates the activation of A2A adenosine receptor.

    Directory of Open Access Journals (Sweden)

    Yoonji Lee

    2015-02-01

    Full Text Available Dynamics and functions of G-protein coupled receptors (GPCRs are accurately regulated by the type of ligands that bind to the orthosteric or allosteric binding sites. To glean the structural and dynamical origin of ligand-dependent modulation of GPCR activity, we performed total ~ 5 μsec molecular dynamics simulations of A2A adenosine receptor (A2AAR in its apo, antagonist-bound, and agonist-bound forms in an explicit water and membrane environment, and examined the corresponding dynamics and correlation between the 10 key structural motifs that serve as the allosteric hotspots in intramolecular signaling network. We dubbed these 10 structural motifs "binary switches" as they display molecular interactions that switch between two distinct states. By projecting the receptor dynamics on these binary switches that yield 2(10 microstates, we show that (i the receptors in apo, antagonist-bound, and agonist-bound states explore vastly different conformational space; (ii among the three receptor states the apo state explores the broadest range of microstates; (iii in the presence of the agonist, the active conformation is maintained through coherent couplings among the binary switches; and (iv to be most specific, our analysis shows that W246, located deep inside the binding cleft, can serve as both an agonist sensor and actuator of ensuing intramolecular signaling for the receptor activation. Finally, our analysis of multiple trajectories generated by inserting an agonist to the apo state underscores that the transition of the receptor from inactive to active form requires the disruption of ionic-lock in the DRY motif.

  5. AMP-guided tumour-specific nanoparticle delivery via adenosine A1 receptor.

    Science.gov (United States)

    Dai, Tongcheng; Li, Na; Han, Fajun; Zhang, Hua; Zhang, Yuanxing; Liu, Qin

    2016-03-01

    Active targeting-ligands have been increasingly used to functionalize nanoparticles for tumour-specific clinical applications. Here we utilize nucleotide adenosine 5'-monophosphate (AMP) as a novel ligand to functionalize polymer-based fluorescent nanoparticles (NPs) for tumour-targeted imaging. We demonstrate that AMP-conjugated NPs (NPs-AMP) efficiently bind to and are following internalized into colon cancer cell CW-2 and breast cancer cell MDA-MB-468 in vitro. RNA interference and inhibitor assays reveal that the targeting effects mainly rely on the specific binding of AMP to adenosine A1 receptor (A1R), which is greatly up-regulated in cancer cells than in matched normal cells. More importantly, NPs-AMP specifically accumulate in the tumour site of colon and breast tumour xenografts and are further internalized into the tumour cells in vivo via tail vein injection, confirming that the high in vitro specificity of AMP can be successfully translated into the in vivo efficacy. Furthermore, NPs-AMP exhibit an active tumour-targeting behaviour in various colon and breast cancer cells, which is positively related to the up-regulation level of A1R in cancer cells, suggesting that AMP potentially suits for more extensive A1R-overexpressing cancer models. This work establishes AMP to be a novel tumour-targeting ligand and provides a promising strategy for future diagnostic or therapeutic applications. Copyright © 2016 Elsevier Ltd. All rights reserved.

  6. Synthesis and properties of a new water-soluble prodrug of the adenosine A 2A receptor antagonist MSX-2.

    Science.gov (United States)

    Vollmann, Karl; Qurishi, Ramatullah; Hockemeyer, Jörg; Müller, Christa E

    2008-02-12

    The compound L-valine-3-{8-[(E)-2-[3-methoxyphenyl)ethenyl]-7-methyl-1-propargylxanthine-3-yl}propyl ester hydrochloride (MSX-4) was synthesized as an amino acid ester prodrug of the adenosine A2A receptor antagonist MSX-2. It was found to be stable in artificial gastric acid, but readily cleaved by pig liver esterase.

  7. A1 not A2A adenosine receptors play a role in cortical epileptic afterdischarges in immature rats

    Czech Academy of Sciences Publication Activity Database

    Mareš, Pavel

    2014-01-01

    Roč. 121, č. 11 (2014), s. 1329-1336 ISSN 0300-9564 R&D Projects: GA MŠk(CZ) LH11015 Institutional support: RVO:67985823 Keywords : adenosine receptors * epileptic afterdischarges * cerebral cortex * ontogeny * rat Subject RIV: FH - Neurology Impact factor: 2.402, year: 2014

  8. IB-MECA, an Adenosine A(3) Receptor Agonist, Does Not Influence Survival of Lethally gamma-Irradiated Mice

    Czech Academy of Sciences Publication Activity Database

    Hofer, Michal; Pospíšil, Milan; Dušek, L.; Hoferová, Zuzana; Komůrková, Denisa

    2012-01-01

    Roč. 61, č. 6 (2012), s. 649-654 ISSN 0862-8408 R&D Projects: GA ČR(CZ) GA305/08/0158; GA ČR(CZ) GAP303/11/0128 Institutional support: RVO:68081707 Keywords : Mouse * IB-MECA * Adenosine A(3) receptor agonist Subject RIV: BO - Biophysics Impact factor: 1.531, year: 2012

  9. Early Cessation of Adenosine Diphosphate Receptor Inhibitors Among Acute Myocardial Infarction Patients Treated With Percutaneous Coronary Intervention

    DEFF Research Database (Denmark)

    Fosbøl, Emil L; Ju, Christine; Anstrom, Kevin J

    2016-01-01

    BACKGROUND: Guidelines recommend the use of adenosine diphosphate receptor inhibitor (ADPri) therapy for 1 year postacute myocardial infarction; yet, early cessation of therapy occurs frequently in clinical practice. METHODS AND RESULTS: We examined 11 858 acute myocardial infarction patients tre...

  10. Synthesis and Properties of a New Water-Soluble Prodrug of the Adenosine A2A Receptor Antagonist MSX-2

    Directory of Open Access Journals (Sweden)

    Christa E. Müller

    2008-02-01

    Full Text Available The compound L-valine-3-{8-[(E-2-[3-methoxyphenylethenyl]-7-methyl-1-propargylxanthine-3-yl}propyl ester hydrochloride (MSX-4 was synthesized as an aminoacid ester prodrug of the adenosine A2A receptor antagonist MSX-2. It was found to bestable in artificial gastric acid, but readily cleaved by pig liver esterase.

  11. Synthesis and pharmacological characterization of novel xanthine carboxylate amides as A2A adenosine receptor ligands exhibiting bronchospasmolytic activity.

    Science.gov (United States)

    Yadav, Rakesh; Bansal, Ranju; Rohilla, Suman; Kachler, Sonja; Klotz, Karl-Norbert

    2016-04-01

    The carboxylate amides of 8-phenyl-1,3-dimethylxanthine described herein represent a new series of selective ligands of the adenosine A2A receptors exhibiting bronchospasmolytic activity. The effects of location of 8-phenyl substitutions on the adenosine receptor (AR) binding affinities of the newly synthesized xanthines have also been studied. The compounds displayed moderate to potent binding affinities toward various adenosine receptor subtypes when evaluated through radioligand binding studies. However, most of the compounds showed the maximum affinity for the A2A subtype, some with high selectivity versus all other subtypes. Xanthine carboxylate amide 13b with a diethylaminoethylamino moiety at the para-position of the 8-phenylxanthine scaffold was identified as the most potent A2A adenosine receptor ligand with Ki=0.06μM. Similarly potent and highly A2A-selective are the isovanillin derivatives 16a and 16d. In addition, the newly synthesized xanthine derivatives showed good in vivo bronchospasmolytic activity when tested in guinea pigs. Copyright © 2016 Elsevier Inc. All rights reserved.

  12. Combined pharmacological therapy of the acute radiation disease using a cyclooxygenase-2 inhibitor and an adenosine A(3) receptor agonist

    Czech Academy of Sciences Publication Activity Database

    Hofer, Michal; Pospíšil, Milan; Dušek, L.; Hoferová, Zuzana; Komůrková, Denisa

    2014-01-01

    Roč. 9, č. 6 (2014), s. 642-646 ISSN 1895-104X R&D Projects: GA ČR(CZ) GAP303/11/0128 Institutional support: RVO:68081707 Keywords : Hematopoiesis * Cyclooxygenase inhibition * Adenosine receptor agonist Subject RIV: BO - Biophysics Impact factor: 0.710, year: 2014

  13. Intracellular ATP influences synaptic plasticity in area CA1 of rat hippocampus via metabolism to adenosine and activity-dependent activation of adenosine A1 receptors.

    Science.gov (United States)

    zur Nedden, Stephanie; Hawley, Simon; Pentland, Naomi; Hardie, D Grahame; Doney, Alexander S; Frenguelli, Bruno G

    2011-04-20

    The extent to which brain slices reflect the energetic status of the in vivo brain has been a subject of debate. We addressed this issue to investigate the recovery of energetic parameters and adenine nucleotides in rat hippocampal slices and the influence this has on synaptic transmission and plasticity. We show that, although adenine nucleotide levels recover appreciably within 10 min of incubation, it takes 3 h for a full recovery of the energy charge (to ≥ 0.93) and that incubation of brain slices at 34°C results in a significantly higher ATP/AMP ratio and a threefold lower activity of AMP-activated protein kinase compared with slices incubated at room temperature. Supplementation of artificial CSF with d-ribose and adenine (Rib/Ade) increased the total adenine nucleotide pool of brain slices, which, when corrected for the influence of the dead cut edges, closely approached in vivo values. Rib/Ade did not affect basal synaptic transmission or paired-pulse facilitation but did inhibit long-term potentiation (LTP) induced by tetanic or weak theta-burst stimulation. This decrease in LTP was reversed by strong theta-burst stimulation or antagonizing the inhibitory adenosine A(1) receptor suggesting that the elevated tissue ATP levels had resulted in greater activity-dependent adenosine release during LTP induction. This was confirmed by direct measurement of adenosine release with adenosine biosensors. These observations provide new insight into the recovery of adenine nucleotides after slice preparation, the sources of loss of such compounds in brain slices, the means by which to restore them, and the functional consequences of doing so.

  14. Enhanced A3 adenosine receptor selectivity of multivalent nucleoside-dendrimer conjugates

    Directory of Open Access Journals (Sweden)

    Shainberg Asher

    2008-10-01

    Full Text Available Abstract Background An approach to use multivalent dendrimer carriers for delivery of nucleoside signaling molecules to their cell surface G protein-coupled receptors (GPCRs was recently introduced. Results A known adenosine receptor (AR agonist was conjugated to polyamidoamine (PAMAM dendrimer carriers for delivery of the intact covalent conjugate to on the cell surface. Depending on the linking moiety, multivalent conjugates of the N6-chain elongated functionalized congener ADAC (N6-[4-[[[4-[[[(2-aminoethylamino]carbonyl]methyl]anilino]carbonyl]methyl]phenyl]-adenosine achieved unanticipated high selectivity in binding to the cytoprotective human A3 AR, a class A GPCR. The key to this selectivity of > 100-fold in both radioreceptor binding (Ki app = 2.4 nM and functional assays (EC50 = 1.6 nM in inhibition of adenylate cyclase was maintaining a free amino group (secondary in an amide-linked chain. Attachment of neutral amide-linked chains or thiourea-containing chains preserved the moderate affinity and efficacy at the A1 AR subtype, but there was no selectivity for the A3 AR. Since residual amino groups on dendrimers are associated with cytotoxicity, the unreacted terminal positions of this A3 AR-selective G2.5 dendrimer were present as carboxylate groups, which had the further benefit of increasing water-solubility. The A3 AR selective G2.5 dendrimer was also visualized binding the membrane of cells expressing the A3 receptor but did not bind cells that did not express the receptor. Conclusion This is the first example showing that it is feasible to modulate and even enhance the pharmacological profile of a ligand of a GPCR based on conjugation to a nanocarrier and the precise structure of the linking group, which was designed to interact with distal extracellular regions of the 7 transmembrane-spanning receptor. This ligand tool can now be used in pharmacological models of tissue rescue from ischemia and to probe the existence of A3 AR

  15. Adenosine A1 receptors contribute to immune regulation after neonatal hypoxic ischemic brain injury.

    Science.gov (United States)

    Winerdal, Max; Winerdal, Malin E; Wang, Ying-Qing; Fredholm, Bertil B; Winqvist, Ola; Ådén, Ulrika

    2016-03-01

    Neonatal brain hypoxic ischemia (HI) often results in long-term motor and cognitive impairments. Post-ischemic inflammation greatly effects outcome and adenosine receptor signaling modulates both HI and immune cell function. Here, we investigated the influence of adenosine A1 receptor deficiency (A1R(-/-)) on key immune cell populations in a neonatal brain HI model. Ten-day-old mice were subjected to HI. Functional outcome was assessed by open locomotion and beam walking test and infarction size evaluated. Flow cytometry was performed on brain-infiltrating cells, and semi-automated analysis of flow cytometric data was applied. A1R(-/-) mice displayed larger infarctions (+33%, p beam walking tests (44% more mistakes, p < 0.05) than wild-type (WT) mice. Myeloid cell activation after injury was enhanced in A1R(-/-) versus WT brains. Activated B lymphocytes expressing IL-10 infiltrated the brain after HI in WT, but were less activated and did not increase in relative frequency in A1R(-/-). Also, A1R(-/-) B lymphocytes expressed less IL-10 than their WT counterparts, the A1R antagonist DPCPX decreased IL-10 expression whereas the A1R agonist CPA increased it. CD4(+) T lymphocytes including FoxP3(+) T regulatory cells, were unaffected by genotype, whereas CD8(+) T lymphocyte responses were smaller in A1R(-/-) mice. Using PCA to characterize the immune profile, we could discriminate the A1R(-/-) and WT genotypes as well as sham operated from HI-subjected animals. We conclude that A1R signaling modulates IL-10 expression by immune cells, influences the activation of these cells in vivo, and affects outcome after HI.

  16. Role of Adenosine Receptor A2A in Traumatic Optic Neuropathies (Addendum)

    Science.gov (United States)

    2016-03-01

    diabetic retinopathy . Life Sci. 2013 Jul 30;93(2-3):78-88. doi: 10.1016/j.lfs.2013.05.024. Epub 2013 Jun 12.PMID:23770229 7 AIMS: This study was...undertaken to determine the effect of an adenosine kinase inhibitor (AKI) in diabetic retinopathy (DR). We have shown previously that adenosine signaling...reported recently that adenosine kinase upregulated in retinal tissue of diabetic retinopathy (Elsherbiny et al., 2013). Adenosine kinase (ADK) converts

  17. Structural and energetic effects of A2A adenosine receptor mutations on agonist and antagonist binding.

    Directory of Open Access Journals (Sweden)

    Henrik Keränen

    Full Text Available To predict structural and energetic effects of point mutations on ligand binding is of considerable interest in biochemistry and pharmacology. This is not only useful in connection with site-directed mutagenesis experiments, but could also allow interpretation and prediction of individual responses to drug treatment. For G-protein coupled receptors systematic mutagenesis has provided the major part of functional data as structural information until recently has been very limited. For the pharmacologically important A(2A adenosine receptor, extensive site-directed mutagenesis data on agonist and antagonist binding is available and crystal structures of both types of complexes have been determined. Here, we employ a computational strategy, based on molecular dynamics free energy simulations, to rationalize and interpret available alanine-scanning experiments for both agonist and antagonist binding to this receptor. These computer simulations show excellent agreement with the experimental data and, most importantly, reveal the molecular details behind the observed effects which are often not immediately evident from the crystal structures. The work further provides a distinct validation of the computational strategy used to assess effects of point-mutations on ligand binding. It also highlights the importance of considering not only protein-ligand interactions but also those mediated by solvent water molecules, in ligand design projects.

  18. Mapping adenosine A1 receptors in the cat brain by positron emission tomography with [11C]MPDX

    International Nuclear Information System (INIS)

    Shimada, Yuhei; Ishiwata, Kiichi; Kiyosawa, Motohiro; Nariai, Tadashi; Oda, Keiichi; Toyama, Hinako; Suzuki, Fumio; Ono, Kenichirou; Senda, Michio

    2002-01-01

    We evaluated the potential of [ 11 C]MPDX as a radioligand for mapping adenosine A 1 receptors in comparison with previously proposed [ 11 C]KF15372 in cat brain by PET. Two tracers showed the same brain distribution. Brain uptake of [ 11 C]MPDX (Ki=4.2 nM) was much higher and washed out faster than that of [ 11 C]KF15372 (Ki=3.0 nM), and was blocked by carrier-loading or displaced with an A 1 antagonist. The regional A 1 receptor distribution evaluated with kinetic analysis is consistent with that previously measured in vitro. [ 11 C]MPDX PET has a potential for mapping adenosine A 1 receptors in brain

  19. Adenosine Receptors Differentially Regulate the Expression of Regulators of G-Protein Signalling (RGS 2, 3 and 4 in Astrocyte-Like Cells.

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    Till Nicolas Eusemann

    Full Text Available The "regulators of g-protein signalling" (RGS comprise a large family of proteins that limit by virtue of their GTPase accelerating protein domain the signal transduction of G-protein coupled receptors. RGS proteins have been implicated in various neuropsychiatric diseases such as schizophrenia, drug abuse, depression and anxiety and aggressive behaviour. Since conditions associated with a large increase of adenosine in the brain such as seizures or ischemia were reported to modify the expression of some RGS proteins we hypothesized that adenosine might regulate RGS expression in neural cells. We measured the expression of RGS-2,-3, and -4 in both transformed glia cells (human U373 MG astrocytoma cells and in primary rat astrocyte cultures stimulated with adenosine agonists. Expression of RGS-2 mRNA as well as RGS2 protein was increased up to 30-fold by adenosine agonists in astrocytes. The order of potency of agonists and the blockade by the adenosine A2B-antagonist MRS1706 indicated that this effect was largely mediated by adenosine A2B receptors. However, a smaller effect was observed due to activation of adenosine A2A receptors. In astrocytoma cells adenosine agonists elicited an increase in RGS-2 expression solely mediated by A2B receptors. Expression of RGS-3 was inhibited by adenosine agonists in both astrocytoma cells and astrocytes. However while this effect was mediated by A2B receptors in astrocytoma cells it was mediated by A2A receptors in astrocytes as assessed by the order of potency of agonists and selective blockade by the specific antagonists MRS1706 and ZM241385 respectively. RGS-4 expression was inhibited in astrocytoma cells but enhanced in astrocytes by adenosine agonists.

  20. Selective adenosine A2A receptor agonists and antagonists protect against spinal cord injury through peripheral and central effects

    Directory of Open Access Journals (Sweden)

    Esposito Emanuela

    2011-04-01

    Full Text Available Abstract Background Permanent functional deficits following spinal cord injury (SCI arise both from mechanical injury and from secondary tissue reactions involving inflammation. Enhanced release of adenosine and glutamate soon after SCI represents a component in the sequelae that may be responsible for resulting functional deficits. The role of adenosine A2A receptor in central ischemia/trauma is still to be elucidated. In our previous studies we have demonstrated that the adenosine A2A receptor-selective agonist CGS21680, systemically administered after SCI, protects from tissue damage, locomotor dysfunction and different inflammatory readouts. In this work we studied the effect of the adenosine A2A receptor antagonist SCH58261, systemically administered after SCI, on the same parameters. We investigated the hypothesis that the main action mechanism of agonists and antagonists is at peripheral or central sites. Methods Spinal trauma was induced by extradural compression of SC exposed via a four-level T5-T8 laminectomy in mouse. Three drug-dosing protocols were utilized: a short-term systemic administration by intraperitoneal injection, a chronic administration via osmotic minipump, and direct injection into the spinal cord. Results SCH58261, systemically administered (0.01 mg/kg intraperitoneal. 1, 6 and 10 hours after SCI, reduced demyelination and levels of TNF-α, Fas-L, PAR, Bax expression and activation of JNK mitogen-activated protein kinase (MAPK 24 hours after SCI. Chronic SCH58261 administration, by mini-osmotic pump delivery for 10 days, improved the neurological deficit up to 10 days after SCI. Adenosine A2A receptors are physiologically expressed in the spinal cord by astrocytes, microglia and oligodendrocytes. Soon after SCI (24 hours, these receptors showed enhanced expression in neurons. Both the A2A agonist and antagonist, administered intraperitoneally, reduced expression of the A2A receptor, ruling out the possibility that the

  1. Behavioral control by striatal adenosine A2A -dopamine D2 receptor heteromers.

    Science.gov (United States)

    Taura, J; Valle-León, M; Sahlholm, K; Watanabe, M; Van Craenenbroeck, K; Fernández-Dueñas, V; Ferré, S; Ciruela, F

    2018-04-01

    G protein-coupled receptors (GPCR) exhibit the ability to form receptor complexes that include molecularly different GPCR (ie, GPCR heteromers), which endow them with singular functional and pharmacological characteristics. The relative expression of GPCR heteromers remains a matter of intense debate. Recent studies support that adenosine A 2A receptors (A 2A R) and dopamine D 2 receptors (D 2 R) predominantly form A 2A R-D 2 R heteromers in the striatum. The aim of the present study was evaluating the behavioral effects of pharmacological manipulation and genetic blockade of A 2A R and D 2 R within the frame of such a predominant striatal heteromeric population. First, in order to avoid possible strain-related differences, a new D 2 R-deficient mouse with the same genetic background (CD-1) than the A 2A R knock-out mouse was generated. Locomotor activity, pre-pulse inhibition (PPI) and drug-induced catalepsy were then evaluated in wild-type, A 2A R and D 2 R knock-out mice, with and without the concomitant administration of either the D 2 R agonist sumanirole or the A 2A R antagonist SCH442416. SCH442416-mediated locomotor effects were demonstrated to be dependent on D 2 R signaling. Similarly, a significant dependence on A 2A R signaling was observed for PPI and for haloperidol-induced catalepsy. The results could be explained by the existence of one main population of striatal postsynaptic A 2A R-D 2 R heteromers, which may constitute a relevant target for the treatment of Parkinson's disease and other neuropsychiatric disorders. © 2017 John Wiley & Sons Ltd and International Behavioural and Neural Genetics Society.

  2. Emotional instability but intact spatial cognition in adenosine receptor 1 knock out mice.

    Science.gov (United States)

    Lang, Undine E; Lang, Florian; Richter, Kerstin; Vallon, Volker; Lipp, Hans-Peter; Schnermann, Jürgen; Wolfer, David P

    2003-10-17

    Several lines of evidence point to the involvement of adenosine in the regulation of important central mechanisms such as cognition, arousal, aggression and anxiety. In order to elucidate the involvement of the adenosine A1 receptor (A1AR) in spatial learning and the control of exploratory behaviour, we assessed A1AR knockout mice (A1AR-/-) and their wild-type littermates (A1AR+/+) in a place navigation task in the water maze and in a battery of forced and free exploration tests. In the water maze, A1AR-/- mice showed normal escape latencies and were indistinguishable from controls with respect to measures of spatial performance during both training and probe trial. But despite normal performance they showed increased wall hugging, most prominently after the relocation of the goal platform for reversal training. Quantitative analysis of strategy choices indicated that wall hugging was increased mainly at the expense of chaining and passive floating, whereas the frequency of trials characterised as direct swims or focal searching was normal in A1AR-/- mice. These results indicate intact spatial cognition, but mildly altered emotional reactions to the water maze environment. In line with this interpretation, A1AR-/- mice showed normal levels and patterns of activity, but a mild increase of some measures of anxiety in our battery of forced and free exploration paradigms. These results are in line with findings published using a genetically similar line, but demonstrate that the magnitude of the changes and the range of affected behavioural measures may vary considerably depending on the environmental conditions during testing.

  3. Striatal pre- and postsynaptic profile of adenosine A(2A receptor antagonists.

    Directory of Open Access Journals (Sweden)

    Marco Orru

    2011-01-01

    Full Text Available Striatal adenosine A(2A receptors (A(2ARs are highly expressed in medium spiny neurons (MSNs of the indirect efferent pathway, where they heteromerize with dopamine D(2 receptors (D(2Rs. A(2ARs are also localized presynaptically in cortico-striatal glutamatergic terminals contacting MSNs of the direct efferent pathway, where they heteromerize with adenosine A(1 receptors (A(1Rs. It has been hypothesized that postsynaptic A(2AR antagonists should be useful in Parkinson's disease, while presynaptic A(2AR antagonists could be beneficial in dyskinetic disorders, such as Huntington's disease, obsessive-compulsive disorders and drug addiction. The aim or this work was to determine whether selective A(2AR antagonists may be subdivided according to a preferential pre- versus postsynaptic mechanism of action. The potency at blocking the motor output and striatal glutamate release induced by cortical electrical stimulation and the potency at inducing locomotor activation were used as in vivo measures of pre- and postsynaptic activities, respectively. SCH-442416 and KW-6002 showed a significant preferential pre- and postsynaptic profile, respectively, while the other tested compounds (MSX-2, SCH-420814, ZM-241385 and SCH-58261 showed no clear preference. Radioligand-binding experiments were performed in cells expressing A(2AR-D(2R and A(1R-A(2AR heteromers to determine possible differences in the affinity of these compounds for different A(2AR heteromers. Heteromerization played a key role in the presynaptic profile of SCH-442416, since it bound with much less affinity to A(2AR when co-expressed with D(2R than with A(1R. KW-6002 showed the best relative affinity for A(2AR co-expressed with D(2R than co-expressed with A(1R, which can at least partially explain the postsynaptic profile of this compound. Also, the in vitro pharmacological profile of MSX-2, SCH-420814, ZM-241385 and SCH-58261 was is in accordance with their mixed pre- and postsynaptic profile

  4. A3 Adenosine Receptor Allosteric Modulator Induces an Anti-Inflammatory Effect: In Vivo Studies and Molecular Mechanism of Action

    Directory of Open Access Journals (Sweden)

    Shira Cohen

    2014-01-01

    Full Text Available The A3 adenosine receptor (A3AR is overexpressed in inflammatory cells and in the peripheral blood mononuclear cells of individuals with inflammatory conditions. Agonists to the A3AR are known to induce specific anti-inflammatory effects upon chronic treatment. LUF6000 is an allosteric compound known to modulate the A3AR and render the endogenous ligand adenosine to bind to the receptor with higher affinity. The advantage of allosteric modulators is their capability to target specifically areas where adenosine levels are increased such as inflammatory and tumor sites, whereas normal body cells and tissues are refractory to the allosteric modulators due to low adenosine levels. LUF6000 administration induced anti-inflammatory effect in 3 experimental animal models of rat adjuvant induced arthritis, monoiodoacetate induced osteoarthritis, and concanavalin A induced liver inflammation in mice. The molecular mechanism of action points to deregulation of signaling proteins including PI3K, IKK, IκB, Jak-2, and STAT-1, resulting in decreased levels of NF-κB, known to mediate inflammatory effects. Moreover, LUF6000 induced a slight stimulatory effect on the number of normal white blood cells and neutrophils. The anti-inflammatory effect of LUF6000, mechanism of action, and the differential effects on inflammatory and normal cells position this allosteric modulator as an attractive and unique drug candidate.

  5. Deletion of the distal COOH-terminus of the A2B adenosine receptor switches internalization to an arrestin- and clathrin-independent pathway and inhibits recycling.

    Science.gov (United States)

    Mundell, S J; Matharu, A-L; Nisar, S; Palmer, T M; Benovic, J L; Kelly, E

    2010-02-01

    We have investigated the effect of deletions of a postsynaptic density, disc large and zo-1 protein (PDZ) motif at the end of the COOH-terminus of the rat A(2B) adenosine receptor on intracellular trafficking following long-term exposure to the agonist 5'-(N-ethylcarboxamido)-adenosine. The trafficking of the wild type A(2B) adenosine receptor and deletion mutants expressed in Chinese hamster ovary cells was studied using an enzyme-linked immunosorbent assay in combination with immunofluorescence microscopy. The wild type A(2B) adenosine receptor and deletion mutants were all extensively internalized following prolonged treatment with NECA. The intracellular compartment through which the Gln(325)-stop receptor mutant, which lacks the Type II PDZ motif found in the wild type receptor initially trafficked was not the same as the wild type receptor. Expression of dominant negative mutants of arrestin-2, dynamin or Eps-15 inhibited internalization of wild type and Leu(330)-stop receptors, whereas only dominant negative mutant dynamin inhibited agonist-induced internalization of Gln(325)-stop, Ser(326)-stop and Phe(328)-stop receptors. Following internalization, the wild type A(2B) adenosine receptor recycled rapidly to the cell surface, whereas the Gln(325)-stop receptor did not recycle. Deletion of the COOH-terminus of the A(2B) adenosine receptor beyond Leu(330) switches internalization from an arrestin- and clathrin-dependent pathway to one that is dynamin dependent but arrestin and clathrin independent. The presence of a Type II PDZ motif appears to be essential for arrestin- and clathrin-dependent internalization, as well as recycling of the A(2B) adenosine receptor following prolonged agonist addition.

  6. Adenosine A2A Receptor in the Monkey Basal Ganglia: Ultrastructural Localization and Colocalization With the Metabotropic Glutamate Receptor 5 in the Striatum

    OpenAIRE

    Bogenpohl, James W.; Ritter, Stefanie L.; Hall, Randy A.; Smith, Yoland

    2012-01-01

    The adenosine A2A receptor (A2AR) is a potential drug target for the treatment of Parkinson’s disease and other neurological disorders. In rodents, the therapeutic efficacy of A2AR modulation is improved by concomitant modulation of the metabotropic glutamate receptor 5 (mGluR5). To elucidate the anatomical substrate(s) through which these therapeutic benefits could be mediated, pre-embedding electron microscopy immunohistochemistry was used to conduct a detailed, quantitative ultrastructural...

  7. ATP induced vasodilatation and purinergic receptors in the human leg: roles of nitric oxide, prostaglandins and adenosine

    DEFF Research Database (Denmark)

    Mortensen, Stefan P; Gonzalez-Alonso, Jose; Bune, Laurids

    2009-01-01

    .05) and was associated with a parallel lowering in leg vascular conductance and cardiac output and a compensatory increase in leg O2 extraction. Infusion of theophylline did not alter the ATP induced leg hyperemia or systemic variables. Real time PCR analysis of the mRNA content from the vastus lateralus muscle of 8...... subjects showed the highest expression of P2Y2 receptors of the 10 investigated P2 receptor subtypes. Immunohistochemistry showed that P2Y2 receptors were located in the endothelium of microvessels and smooth muscle cells, whereas P2X1 receptors were located in the endothelium and the sacrolemma....... Collectively, these results indicate that NO and prostaglandins, but not adenosine, play a role in ATP induced vasodilation in human skeletal muscle. The localization of the P2Y2 and P2X1 receptors suggest that these receptors may mediate ATP induced vasodilation in skeletal muscle. Key words: Skeletal Muscle...

  8. Allosteric mechanisms within the adenosine A2A-dopamine D2 receptor heterotetramer

    Science.gov (United States)

    Ferré, Sergi; Bonaventura, Jordi; Tomasi, Dardo; Navarro, Gemma; Moreno, Estefanía; Cortés, Antonio; Lluís, Carme; Casadó, Vicent; Volkow, Nora D.

    2017-01-01

    The structure constituted by a G protein coupled receptor (GPCR) homodimer and a G protein provides a main functional unit and oligomeric entities can be viewed as multiples of dimers. For GPCR heteromers, experimental evidence supports a tetrameric structure, comprised of two different homodimers, each able to signal with its preferred G protein. GPCR homomers and heteromers can act as the conduit of allosteric interactions between orthosteric ligands. The well-known agonist/agonist allosteric interaction in the adenosine A2A receptor (A2AR)-dopamine D2 receptor (D2R) heteromer, by which A2AR agonists decrease the affinity of D2R agonists, gave the first rationale for the use of A2AR antagonists in Parkinson’s disease. We review new pharmacological findings that can be explained in the frame of a tetrameric structure of the A2AR-D2R heteromer: first, ligand-independent allosteric modulations by the D2R that result in changes of the binding properties of A2AR ligands; second, differential modulation of the intrinsic efficacy of D2R ligands for G protein-dependent and independent signaling; third, the canonical antagonistic Gs-Gi interaction within the frame of the heteromer; and fourth, the ability of A2AR antagonists, including caffeine, to also exert the same allosteric modulations of D2R ligands than A2AR agonists, while A2AR agonists and antagonists counteract each other’s effects. These findings can have important clinical implications when evaluating the use of A2AR antagonists. They also call for the need of monitoring caffeine intake when evaluating the effect of D2R ligands, when used as therapeutic agents in neuropsychiatric disorders or as probes in imaging studies. PMID:26051403

  9. Hide and seek: a comparative autoradiographic in vitro investigation of the adenosine A3 receptor

    Energy Technology Data Exchange (ETDEWEB)

    Haeusler, D.; Fuchshuber, F.; Girschele, F.; Hacker, M.; Wadsak, W.; Mitterhauser, Markus [Medical University of Vienna, Department of Biomedical Imaging and Image-guided Therapy, Vienna (Austria); Grassinger, L. [University of Applied Sciences Wiener Neustadt, Department of Biomedical Analytics, Wiener Neustadt (Austria); Hoerleinsberger, W.J. [Medical University of Vienna, Department of Biomedical Imaging and Image-guided Therapy, Vienna (Austria); University of Vienna, Cognitive Science Research Platform, Vienna (Austria); Hoeftberger, R.; Leisser, I. [Medical University of Vienna, Institute of Neurology, Vienna (Austria); Shanab, K.; Spreitzer, H. [University of Vienna, Department of Drug and Natural Product Synthesis, Vienna (Austria); Gerdenitsch, W. [Medical University of Vienna, Institute of Biomedicinal Research, Vienna (Austria)

    2015-05-01

    Since the adenosine A3 receptor (A3R) is considered to be of high clinical importance in the diagnosis and treatment of ischaemic conditions (heart and brain), glaucoma, asthma, arthritis, cancer and inflammation, a suitable and selective A3R PET tracer such as [{sup 18}F]FE rate at SUPPY would be of high clinical value for clinicians as well as patients. A3R was discovered in the late 1990s, but there is still little known regarding its distribution in the CNS and periphery. Hence, in autoradiographic experiments the distribution of A3R in human brain and rat tissues was investigated and the specific binding of the A3R antagonist FE rate at SUPPY and MRS1523 compared. Immunohistochemical staining (IHC) experiments were also performed to validate the autoradiographic findings. For autoradiographic competition experiments human post-mortem brain and rat tissues were incubated with [{sup 125}I]AB-MECA and highly selective compounds to block the other adenosine receptor subtypes. Additionally, IHC was performed with an A3 antibody. Specific A3R binding of MRS1523 and FE rate at SUPPY was found in all rat peripheral tissues examined with the highest amounts in the spleen (44.0 % and 46.4 %), lung (44.5 % and 45.0 %), heart (39.9 % and 42.9 %) and testes (27.4 % and 29.5 %, respectively). Low amounts of A3R were found in rat brain tissues (5.9 % and 5.6 %, respectively) and human brain tissues (thalamus 8.0 % and 9.1 %, putamen 7.8 % and 8.2 %, cerebellum 6.0 % and 7.8 %, hippocampus 5.7 % and 5.6 %, caudate nucleus 4.9 % and 6.4 %, cortex 4.9 % and 6.3 %, respectively). The outcome of the A3 antibody staining experiments complemented the results of the autoradiographic experiments. The presence of A3R protein was verified in central and peripheral tissues by autoradiography and IHC. The specificity and selectivity of FE rate at SUPPY was confirmed by direct comparison with MRS1523, providing further evidence that [{sup 18}F]FE rate at SUPPY may be a suitable A3 PET

  10. Preclinical studies on [{sup 11}C]MPDX for mapping adenosine A{sub 1} receptors by positron emission tomography

    Energy Technology Data Exchange (ETDEWEB)

    Ishiwata, Kiichi; Kimura, Yuichi; Oda, Keiichi; Kawamura, Kazunori; Ishii, Kenji; Senda, Michio [Tokyo Metropolitan Inst. of Gerontology (Japan). Positron Medical Center; Nariai, Tadashi; Wakabayashi, Shinichi [Tokyo Medical and Dental Univ. (Japan). School of Medicine; Shimada, Junichi [Kyowa Hakko Kogyo Co. Ltd., Tokyo (Japan). Pharmaceutical Research Inst.

    2002-09-01

    In previous in vivo studies with mice, rats and cats, we have demonstrated that [{sup 11}C]MPDX ([1-methyl-{sup 11}C]8-dicyclopropylmethyl-1-methyl-3-propylxanthine) is a potential radioligand for mapping adenosine A{sub 1} receptors of the brain by positron emission tomography (PET). In the present study, we performed a preclinical study. The radiation absorbed-dose by [{sup 11}C]MPDX in humans estimated from the tissue distribution in mice was low enough for clinical use, and the acute toxicity and mutagenicity of MPDX were not found. The monkey brain was clearly visualized by PET with [{sup 11}C]MPDX. We have concluded that [{sup 11}C]MPDX is suitable for mapping adenosine A{sub 1} receptors in the human brain by PET. (author)

  11. Reinforcing and neurochemical effects of cannabinoid CB1 receptor agonists, but not cocaine, are altered by an adenosine A2A receptor antagonist.

    Science.gov (United States)

    Justinová, Zuzana; Ferré, Sergi; Redhi, Godfrey H; Mascia, Paola; Stroik, Jessica; Quarta, Davide; Yasar, Sevil; Müller, Christa E; Franco, Rafael; Goldberg, Steven R

    2011-07-01

    Several recent studies suggest functional and molecular interactions between striatal adenosine A(2A) and cannabinoid CB(1) receptors. Here, we demonstrate that A(2A) receptors selectively modulate reinforcing effects of cannabinoids. We studied effects of A(2A) receptor blockade on the reinforcing effects of delta-9-tetrahydrocannabinol (THC) and the endogenous CB(1) receptor ligand anandamide under a fixed-ratio schedule of intravenous drug injection in squirrel monkeys. A low dose of the selective adenosine A(2A) receptor antagonist MSX-3 (1 mg/kg) caused downward shifts of THC and anandamide dose-response curves. In contrast, a higher dose of MSX-3 (3 mg/kg) shifted THC and anandamide dose-response curves to the left. MSX-3 did not modify cocaine or food pellet self-administration. Also, MSX-3 neither promoted reinstatement of extinguished drug-seeking behavior nor altered reinstatement of drug-seeking behavior by non-contingent priming injections of THC. Finally, using in vivo microdialysis in freely-moving rats, a behaviorally active dose of MSX-3 significantly counteracted THC-induced, but not cocaine-induced, increases in extracellular dopamine levels in the nucleus accumbens shell. The significant and selective results obtained with the lower dose of MSX-3 suggest that adenosine A(2A) antagonists acting preferentially at presynaptic A(2A) receptors might selectively reduce reinforcing effects of cannabinoids that lead to their abuse. However, the appearance of potentiating rather than suppressing effects on cannabinoid reinforcement at the higher dose of MSX-3 would likely preclude the use of such a compound as a medication for cannabis abuse. Adenosine A(2A) antagonists with more selectivity for presynaptic versus postsynaptic receptors could be potential medications for treatment of cannabis abuse. Addiction Biology © 2010 Society for the Study of Addiction. No claim to original US government works.

  12. Adenosine A₂A receptors inhibit delayed rectifier potassium currents and cell differentiation in primary purified oligodendrocyte cultures.

    Science.gov (United States)

    Coppi, Elisabetta; Cellai, Lucrezia; Maraula, Giovanna; Pugliese, Anna Maria; Pedata, Felicita

    2013-10-01

    Oligodendrocyte progenitor cells (OPCs) are a population of cycling cells which persist in the adult central nervous system (CNS) where, under opportune stimuli, they differentiate into mature myelinating oligodendrocytes. Adenosine A(2A) receptors are Gs-coupled P1 purinergic receptors which are widely distributed throughout the CNS. It has been demonstrated that OPCs express A(2A) receptors, but their functional role in these cells remains elusive. Oligodendrocytes express distinct voltage-gated ion channels depending on their maturation. Here, by electrophysiological recordings coupled with immunocytochemical labeling, we studied the effects of adenosine A(2A) receptors on membrane currents and differentiation of purified primary OPCs isolated from the rat cortex. We found that the selective A(2A) agonist, CGS21680, inhibits sustained, delayed rectifier, K(+) currents (I(K)) without modifying transient (I(A)) conductances. The effect was observed in all cells tested, independently from time in culture. CGS21680 inhibition of I(K) current was concentration-dependent (10-200 nM) and blocked in the presence of the selective A(2A) antagonist SCH58261 (100 nM). It is known that I(K) currents play an important role during OPC development since their block decreases cell proliferation and differentiation. In light of these data, our further aim was to investigate whether A(2A) receptors modulate these processes. CGS21680, applied at 100 nM in the culture medium of oligodendrocyte cultures, inhibits OPC differentiation (an effect prevented by SCH58261) without affecting cell proliferation. Data demonstrate that cultured OPCs express functional A(2A) receptors whose activation negatively modulate I(K) currents. We propose that, by this mechanism, A(2A) adenosine receptors inhibit OPC differentiation. Copyright © 2013 Elsevier Ltd. All rights reserved.

  13. Pharmacological delayed preconditioning against ischaemia-induced ventricular arrhythmias: effect of an adenosine A1-receptor agonist

    OpenAIRE

    Tissier, Renaud; Souktani, Rachid; Parent de Curzon, Olivier; Lellouche, Nicolas; Henry, Patrick; Giudicelli, Jean-François; Berdeaux, Alain; Ghaleh, Bijan

    2001-01-01

    The goal of this study was to investigate the effects of the delayed pharmacological preconditioning produced by an adenosine A1-receptor agonist (A1-DPC) against ventricular arrhythmias induced by ischaemia and reperfusion, compared to those of ischaemia-induced delayed preconditioning (I-DPC).Eighty-nine instrumented conscious rabbits underwent a 2 consecutive days protocol. On day 1, rabbits were randomly divided into four groups: ‘Control' (saline, i.v.), ‘I-DPC' (six 4-min coronary arter...

  14. Promotion of Wound Healing by an Agonist of Adenosine A2A Receptor Is Dependent on Tissue Plasminogen Activator.

    Science.gov (United States)

    Montesinos, M Carmen; Desai-Merchant, Avani; Cronstein, Bruce N

    2015-12-01

    Impaired wound healing, as it occurs in diabetes mellitus or long-term corticoid treatment, is commonly associated with disability, diminished quality of life, and high economic costs. Selective agonists of the A2A receptor subtype of adenosine, an endogenous regulator of inflammation, promote tissue repair in animal models, both healthy and with impaired healing. Plasmin-mediated proteolysis of fibrin and other matrix proteins is essential for cell migration at sites of injury. Since adenosine A2A receptor activation increases plasminogen activator release from macrophages and mast cells, we studied the effect of a selective agonist, CGS-21680, on full-thickness excisional wound closure in wild-type, urokinase plasminogen activator (uPA)-deficient, and tissue plasminogen activator (tPA)-deficient mice. Wound closure was impaired in tPA- and uPA-deficient mice as compared with wild-type mice, and topical application of CGS-21680 significantly increased the rate at which wounds closed in wild-type mice and uPA-deficient mice, but not in tPA-deficient mice. Immunostaining of tissue sections showed that tPA was present in endothelial cells and histiocytes by day 3 post-wound and also by day 6. In contrast, uPA was more prominent in these cell types only by day 6 post-wound. Our results confirm that plasminogen activation contributes to wound repair and are consistent with the hypothesis that adenosine A2A receptor activation promotes wound closure by a mechanism that depends upon tPA, but not uPA. Moreover, our results suggest that topical adenosine A2A receptor agonists may be useful in promotion of wound closure in patients with impaired wound healing.

  15. Hypothermia in mouse is caused by adenosine A1 and A3 receptor agonists and AMP via three distinct mechanisms.

    Science.gov (United States)

    Carlin, Jesse Lea; Jain, Shalini; Gizewski, Elizabeth; Wan, Tina C; Tosh, Dilip K; Xiao, Cuiying; Auchampach, John A; Jacobson, Kenneth A; Gavrilova, Oksana; Reitman, Marc L

    2017-03-01

    Small mammals have the ability to enter torpor, a hypothermic, hypometabolic state, allowing impressive energy conservation. Administration of adenosine or adenosine 5'-monophosphate (AMP) can trigger a hypothermic, torpor-like state. We investigated the mechanisms for hypothermia using telemetric monitoring of body temperature in wild type and receptor knock out (Adora1 -/- , Adora3 -/- ) mice. Confirming prior data, stimulation of the A 3 adenosine receptor (AR) induced hypothermia via peripheral mast cell degranulation, histamine release, and activation of central histamine H 1 receptors. In contrast, A 1 AR agonists and AMP both acted centrally to cause hypothermia. Commonly used, selective A 1 AR agonists, including N 6 -cyclopentyladenosine (CPA), N 6 -cyclohexyladenosine (CHA), and MRS5474, caused hypothermia via both A 1 AR and A 3 AR when given intraperitoneally. Intracerebroventricular dosing, low peripheral doses of Cl-ENBA [(±)-5'-chloro-5'-deoxy-N 6 -endo-norbornyladenosine], or using Adora3 -/- mice allowed selective stimulation of A 1 AR. AMP-stimulated hypothermia can occur independently of A 1 AR, A 3 AR, and mast cells. A 1 AR and A 3 AR agonists and AMP cause regulated hypothermia that was characterized by a drop in total energy expenditure, physical inactivity, and preference for cooler environmental temperatures, indicating a reduced body temperature set point. Neither A 1 AR nor A 3 AR was required for fasting-induced torpor. A 1 AR and A 3 AR agonists and AMP trigger regulated hypothermia via three distinct mechanisms. Published by Elsevier Ltd.

  16. Regulation of hippocampal cannabinoid CB1 receptor actions by adenosine A1 receptors and chronic caffeine administration: implications for the effects of Δ9-tetrahydrocannabinol on spatial memory.

    Science.gov (United States)

    Sousa, Vasco C; Assaife-Lopes, Natália; Ribeiro, Joaquim A; Pratt, Judith A; Brett, Ros R; Sebastião, Ana M

    2011-01-01

    The cannabinoid CB(1) receptor-mediated modulation of γ-aminobutyric acid (GABA) release from inhibitory interneurons is important for the integrity of hippocampal-dependent spatial memory. Although adenosine A(1) receptors have a central role in fine-tuning excitatory transmission in the hippocampus, A(1) receptors localized in GABAergic cells do not directly influence GABA release. CB(1) and A(1) receptors are the main targets for the effects of two of the most heavily consumed psychoactive substances worldwide: Δ(9)-tetrahydrocannabinol (THC, a CB(1) receptor agonist) and caffeine (an adenosine receptor antagonist). We first tested the hypothesis that an A(1)-CB(1) interaction influences GABA and glutamate release in the hippocampus. We found that A(1) receptor activation attenuated the CB(1)-mediated inhibition of GABA and glutamate release and this interaction was manifested at the level of G-protein activation. Using in vivo and in vitro approaches, we then investigated the functional implications of the adenosine-cannabinoid interplay that may arise following chronic caffeine consumption. Chronic administration of caffeine in mice (intraperitoneally, 3 mg/kg/day, for 15 days, >12 h before trials) led to an A(1)-mediated enhancement of the CB(1)-dependent acute disruptive effects of THC on a short-term spatial memory task, despite inducing a reduction in cortical and hippocampal CB(1) receptor number and an attenuation of CB(1) coupling with G protein. A(1) receptor levels were increased following chronic caffeine administration. This study shows that A(1) receptors exert a negative modulatory effect on CB(1)-mediated inhibition of GABA and glutamate release, and provides the first evidence of chronic caffeine-induced alterations on the cannabinoid system in the cortex and hippocampus, with functional implications in spatial memory.

  17. Anticonvulsant effect of AMP by direct activation of adenosine A1 receptor.

    Science.gov (United States)

    Muzzi, Mirko; Coppi, Elisabetta; Pugliese, Anna Maria; Chiarugi, Alberto

    2013-12-01

    Purinergic neurotransmission mediated by adenosine (Ado) type 1 receptors (A1Rs) plays pivotal roles in negative modulation of epileptic seizures, and Ado is thought to be a key endogenous anticonvulsant. Recent evidence, however, indicates that AMP, the metabolic precursor of Ado, also activate A1Rs. Here, we evaluated the antiepileptic effects of AMP adopting in vitro and in vivo models of epilepsy. We report that AMP reversed the increase in population spike (PS) amplitude and the decrease in PS latency induced by a Mg(2+)-free extracellular solution in CA1 neurons of mouse hippocampal slices. The AMP effects were inhibited by the A1R antagonist DPCPX, but not prevented by inhibiting conversion of AMP into Ado, indicating that AMP inhibited per se sustained hippocampal excitatory neurotransmission by directly activating A1Rs. AMP also reduced seizure severity and mortality in a model of audiogenic convulsion. Of note, the anticonvulsant effects of AMP were potentiated by preventing its conversion into Ado and inhibited by DPCPX. When tested in a model of kainate-induced seizure, AMP prolonged latency of convulsions but had no effects on seizure severity and mortality. Data provide the first evidence that AMP is an endogenous anticonvulsant acting at A1Rs. © 2013.

  18. ADENOSINE RECEPTOR STIMULATION BY POLYDEOXYRIBONUCLEOTIDE IMPROVES TISSUE REPAIR AND SYMPTOMOLOGY IN EXPERIMENTAL COLITIS.

    Directory of Open Access Journals (Sweden)

    Giovanni Pallio

    2016-08-01

    Full Text Available Activation of the adenosine receptor pathway has been demonstrated to be effective in improving tissue remodelling and blunting the inflammatory response. Active colitis is characterized by an intense inflammatory reaction resulting in extensive tissue damage. Symptomatic improvement requires both control of the inflammatory process and repair and remodelling of damaged tissues. We investigated the ability of an A2A receptor agonist, polydeoxyribonucleotide (PDRN, to restore tissue structural integrity in two experimental colitis models using male Sprague-Dawley rats. In the first model, colitis was induced with a single intra-colonic instillation of dinitro-benzene-sulfonic acid (DNBS, 25mg diluted in 0.8ml 50% ethanol. After 6 hrs, animals were randomized to receive either PDRN (8mg/kg/i.p., or PDRN + the A2A antagonist (DMPX; 10mg/kg/i.p., or vehicle (0.8 ml saline solution daily. In the second model, dextran sodium sulphate (DSS was dissolved in drinking water at a concentration of 8%. Control animals received standard drinking water. After 24 hrs animals were randomized to receive PDRN or PDRN+DMPX as described above. Rats were sacrificed 7 days after receiving DNBS or 5 days after DSS. In both experimental models of colitis, PDRN ameliorated the clinical symptoms and weight loss associated with disease as well as promoted the histological repair of damaged tissues. Moreover, PDRN reduced expression of inflammatory cytokines, myeloperoxydase activity, and malondialdheyde. All these effects were abolished by the concomitant administration of the A2a antagonist DMPX. Our study suggests that PDRN may represent a promising treatment for improving tissue repair during inflammatory bowel diseases.

  19. Inosine Released from Dying or Dead Cells Stimulates Cell Proliferation via Adenosine Receptors

    Directory of Open Access Journals (Sweden)

    Yi Zhao

    2017-04-01

    Full Text Available IntroductionMany antitumor therapies induce apoptotic cell death in order to cause tumor regression. Paradoxically, apoptotic cells are also known to promote wound healing, cell proliferation, and tumor cell repopulation in multicellular organisms. We aimed to characterize the nature of the regenerative signals concentrated in the micromilieu of dead and dying cells.MethodsCultures of viable melanoma B16F10 cells, mouse fibroblasts, and primary human fibroblast-like synoviocytes (FLS in the presence of dead and dying cells, their supernatants (SNs, or purified agonists and antagonists were used to evaluate the stimulation of proliferation. Viable cell quantification was performed by either flow cytometry of harvested cells or by crystal violet staining of adherent cells. High-performance liquid chromatography and liquid chromatography coupled with mass spectrometry of cell SNs were deployed to identify the nature of growth-promoting factors. Coimplantation of living cells in the presence of SNs collected from dead and dying cells and specific agonists was used to evaluate tumor growth in vivo.ResultsThe stimulation of proliferation of few surviving cells by bystander dead cells was confirmed for melanoma cells, mouse fibroblasts, and primary FLS. We found that small soluble molecules present in the protein-free fraction of SNs of dead and dying cells were responsible for the promotion of proliferation. The nucleoside inosine released by dead and dying cells acting via adenosine receptors was identified as putative inducer of proliferation of surviving tumor cells after irradiation and heat treatment.ConclusionInosine released by dead and dying cells mediates tumor cell proliferation via purinergic receptors. Therapeutic strategies surmounting this pathway may help to reduce the rate of recurrence after radio- and chemotherapy.

  20. Structural Probing of Off-Target G Protein-Coupled Receptor Activities within a Series of Adenosine/Adenine Congeners

    Science.gov (United States)

    Paoletta, Silvia; Tosh, Dilip K.; Salvemini, Daniela; Jacobson, Kenneth A.

    2014-01-01

    We studied patterns of off-target receptor interactions, mostly at G protein-coupled receptors (GPCRs) in the µM range, of nucleoside derivatives that are highly engineered for nM interaction with adenosine receptors (ARs). Because of the considerable interest of using AR ligands for treating diseases of the CNS, we used the Psychoactive Drug Screening Program (PDSP) for probing promiscuity of these adenosine/adenine congeners at 41 diverse receptors, channels and a transporter. The step-wise truncation of rigidified, trisubstituted (at N6, C2, and 5′ positions) nucleosides revealed unanticipated interactions mainly with biogenic amine receptors, such as adrenergic receptors and serotonergic receptors, with affinities as high as 61 nM. The unmasking of consistent sets of structure activity relationship (SAR) at novel sites suggested similarities between receptor families in molecular recognition. Extensive molecular modeling of the GPCRs affected suggested binding modes of the ligands that supported the patterns of SAR at individual receptors. In some cases, the ligand docking mode closely resembled AR binding and in other cases the ligand assumed different orientations. The recognition patterns for different GPCRs were clustered according to which substituent groups were tolerated and explained in light of the complementarity with the receptor binding site. Thus, some likely off-target interactions, a concern for secondary drug effects, can be predicted for analogues of this set of substructures, aiding the design of additional structural analogues that either eliminate or accentuate certain off-target activities. Moreover, similar analyses could be performed for unrelated structural families for other GPCRs. PMID:24859150

  1. Epac is required for exogenous and endogenous stimulation of adenosine A2B receptor for inhibition of angiotensin II-induced collagen synthesis and myofibroblast differentiation.

    Science.gov (United States)

    Phosri, Sarawuth; Bunrukchai, Kwanchai; Parichatikanond, Warisara; Sato, Vilasinee H; Mangmool, Supachoke

    2018-01-10

    Angiotensin II (Ang II) plays an important role on the pathogenesis of cardiac fibrosis. Prolong and overstimulation of angiotensin II type 1 receptor with Ang II-induced collagen synthesis and myofibroblast differentiation in cardiac fibroblasts, leading to cardiac fibrosis. Although adenosine and its analogues are known to have cardioprotective effects, the mechanistic by which adenosine A 2 receptors (A 2 Rs) inhibit Ang II-induced cardiac fibrosis is not clearly understood. In the present study, we examined the effects of exogenous adenosine and endogenous adenosine on Ang II-induced collagen and myofibroblast differentiation determined by α-smooth muscle action (α-SMA) overexpression and their underlying signal transduction. Elevation of endogenous adenosine levels resulted in the inhibition of Ang II-induced collagen type I and III and α-SMA synthesis in cardiac fibroblasts. Moreover, treatment with exogenous adenosine which selectively stimulated A 2 Rs also suppressed Ang II-induced collagen synthesis and α-SMA production. These antifibrotic effects of both endogenous and exogenous adenosines are mediated through the A 2B receptor (A 2B R) subtype. Stimulation of A 2B R exhibited antifibrotic effects via the cAMP-dependent and Epac-dependent pathways. Our results provide new mechanistic insights regarding the role for cAMP and Epac on A 2B R-mediated antifibrotic effects. Thus, A 2B R is one of the potential therapeutic targets against cardiac fibrosis.

  2. Prediction of consensus binding mode geometries for related chemical series of positive allosteric modulators of adenosine and muscarinic acetylcholine receptors.

    Science.gov (United States)

    Sakkal, Leon A; Rajkowski, Kyle Z; Armen, Roger S

    2017-06-05

    Following insights from recent crystal structures of the muscarinic acetylcholine receptor, binding modes of Positive Allosteric Modulators (PAMs) were predicted under the assumption that PAMs should bind to the extracellular surface of the active state. A series of well-characterized PAMs for adenosine (A 1 R, A 2A R, A 3 R) and muscarinic acetylcholine (M 1 R, M 5 R) receptors were modeled using both rigid and flexible receptor CHARMM-based molecular docking. Studies of adenosine receptors investigated the molecular basis of the probe-dependence of PAM activity by modeling in complex with specific agonist radioligands. Consensus binding modes map common pharmacophore features of several chemical series to specific binding interactions. These models provide a rationalization of how PAM binding slows agonist radioligand dissociation kinetics. M 1 R PAMs were predicted to bind in the analogous M 2 R PAM LY2119620 binding site. The M 5 R NAM (ML-375) was predicted to bind in the PAM (ML-380) binding site with a unique induced-fit receptor conformation. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

  3. Methodical Challenges and a Possible Resolution in the Assessment of Receptor Reserve for Adenosine, an Agonist with Short Half-Life

    Directory of Open Access Journals (Sweden)

    Judit Zsuga

    2017-05-01

    Full Text Available The term receptor reserve, first introduced and used in the traditional receptor theory, is an integrative measure of response-inducing ability of the interaction between an agonist and a receptor system (consisting of a receptor and its downstream signaling. The underlying phenomenon, i.e., stimulation of a submaximal fraction of receptors can apparently elicit the maximal effect (in certain cases, provides an opportunity to assess the receptor reserve. However, determining receptor reserve is challenging for agonists with short half-lives, such as adenosine. Although adenosine metabolism can be inhibited several ways (in order to prevent the rapid elimination of adenosine administered to construct concentration–effect (E/c curves for the determination, the consequent accumulation of endogenous adenosine biases the results. To address this problem, we previously proposed a method, by means of which this bias can be mathematically corrected (utilizing a traditional receptor theory-independent approach. In the present investigation, we have offered in silico validation of this method by simulating E/c curves with the use of the operational model of agonism and then by evaluating them using our method. We have found that our method is suitable to reliably assess the receptor reserve for adenosine in our recently published experimental setting, suggesting that it may be capable for a qualitative determination of receptor reserve for rapidly eliminating agonists in general. In addition, we have disclosed a possible interference between FSCPX (8-cyclopentyl-N3-[3-(4-(fluorosulfonylbenzoyloxypropyl]-N1-propylxanthine, an irreversible A1 adenosine receptor antagonist, and NBTI (S-(2-hydroxy-5-nitrobenzyl-6-thioinosine, a nucleoside transport inhibitor, i.e., FSCPX may blunt the effect of NBTI.

  4. On the role of subtype selective adenosine receptor agonists during proliferation and osteogenic differentiation of human primary bone marrow stromal cells.

    Science.gov (United States)

    Costa, M Adelina; Barbosa, A; Neto, E; Sá-e-Sousa, A; Freitas, R; Neves, J M; Magalhães-Cardoso, T; Ferreirinha, F; Correia-de-Sá, P

    2011-05-01

    Purines are important modulators of bone cell biology. ATP is metabolized into adenosine by human primary osteoblast cells (HPOC); due to very low activity of adenosine deaminase, the nucleoside is the end product of the ecto-nucleotidase cascade. We, therefore, investigated the expression and function of adenosine receptor subtypes (A(1) , A(2A) , A(2B) , and A(3) ) during proliferation and osteogenic differentiation of HPOC. Adenosine A(1) (CPA), A(2A) (CGS21680C), A(2B) (NECA), and A(3) (2-Cl-IB-MECA) receptor agonists concentration-dependently increased HPOC proliferation. Agonist-induced HPOC proliferation was prevented by their selective antagonists, DPCPX, SCH442416, PSB603, and MRS1191. CPA and NECA facilitated osteogenic differentiation measured by increases in alkaline phosphatase (ALP) activity. This contrasts with the effect of CGS21680C which delayed HPOC differentiation; 2-Cl-IB-MECA was devoid of effect. Blockade of the A(2B) receptor with PSB603 prevented osteogenic differentiation by NECA. In the presence of the A(1) antagonist, DPCPX, CPA reduced ALP activity at 21 and 28 days in culture. At the same time points, blockade of A(2A) receptors with SCH442416 transformed the inhibitory effect of CGS21680C into facilitation. Inhibition of adenosine uptake with dipyridamole caused a net increase in osteogenic differentiation. The presence of all subtypes of adenosine receptors on HPOC was confirmed by immunocytochemistry. Data show that adenosine is an important regulator of osteogenic cell differentiation through the activation of subtype-specific receptors. The most abundant A(2B) receptor seems to have a consistent role in cell differentiation, which may be balanced through the relative strengths of A(1) or A(2A) receptors determining whether osteoblasts are driven into proliferation or differentiation. Copyright © 2010 Wiley-Liss, Inc.

  5. Adenosine and preeclampsia.

    Science.gov (United States)

    Salsoso, Rocío; Farías, Marcelo; Gutiérrez, Jaime; Pardo, Fabián; Chiarello, Delia I; Toledo, Fernando; Leiva, Andrea; Mate, Alfonso; Vázquez, Carmen M; Sobrevia, Luis

    2017-06-01

    Adenosine is an endogenous nucleoside with pleiotropic effects in different physiological processes including circulation, renal blood flow, immune function, or glucose homeostasis. Changes in adenosine membrane transporters, adenosine receptors, and corresponding intracellular signalling network associate with development of pathologies of pregnancy, including preeclampsia. Preeclampsia is a cause of maternal and perinatal morbidity and mortality affecting 3-5% of pregnancies. Since the proposed mechanisms of preeclampsia development include adenosine-dependent biological effects, adenosine membrane transporters and receptors, and the associated signalling mechanisms might play a role in the pathophysiology of preeclampsia. Preeclampsia associates with increased adenosine concentration in the maternal blood and placental tissue, likely due to local hypoxia and ischemia (although not directly demonstrated), microthrombosis, increased catecholamine release, and platelet activation. In addition, abnormal expression and function of equilibrative nucleoside transporters is described in foetoplacental tissues from preeclampsia; however, the role of adenosine receptors in the aetiology of this disease is not well understood. Adenosine receptors activation may be related to abnormal trophoblast invasion, angiogenesis, and ischemia/reperfusion mechanisms in the placenta from preeclampsia. These mechanisms may explain only a low fraction of the associated abnormal transformation of spiral arteries in preeclampsia, triggering cellular stress and inflammatory mediators release from the placenta to the maternal circulation. Although increased adenosine concentration in preeclampsia may be a compensatory or adaptive mechanism favouring placental angiogenesis, a poor angiogenic state is found in preeclampsia. Thus, preeclampsia-associated complications might affect the cell response to adenosine due to altered expression and activity of adenosine receptors, membrane transporters

  6. Singular Location and Signaling Profile of Adenosine A2A-Cannabinoid CB1 Receptor Heteromers in the Dorsal Striatum.

    Science.gov (United States)

    Moreno, Estefanía; Chiarlone, Anna; Medrano, Mireia; Puigdellívol, Mar; Bibic, Lucka; Howell, Lesley A; Resel, Eva; Puente, Nagore; Casarejos, María J; Perucho, Juan; Botta, Joaquín; Suelves, Nuria; Ciruela, Francisco; Ginés, Silvia; Galve-Roperh, Ismael; Casadó, Vicent; Grandes, Pedro; Lutz, Beat; Monory, Krisztina; Canela, Enric I; Lluís, Carmen; McCormick, Peter J; Guzmán, Manuel

    2018-04-01

    The dorsal striatum is a key node for many neurobiological processes such as motor activity, cognitive functions, and affective processes. The proper functioning of striatal neurons relies critically on metabotropic receptors. Specifically, the main adenosine and endocannabinoid receptors present in the striatum, ie, adenosine A 2A receptor (A 2A R) and cannabinoid CB 1 receptor (CB 1 R), are of pivotal importance in the control of neuronal excitability. Facilitatory and inhibitory functional interactions between striatal A 2A R and CB 1 R have been reported, and evidence supports that this cross-talk may rely, at least in part, on the formation of A 2A R-CB 1 R heteromeric complexes. However, the specific location and properties of these heteromers have remained largely unknown. Here, by using techniques that allowed a precise visualization of the heteromers in situ in combination with sophisticated genetically modified animal models, together with biochemical and pharmacological approaches, we provide a high-resolution expression map and a detailed functional characterization of A 2A R-CB 1 R heteromers in the dorsal striatum. Specifically, our data unveil that the A 2A R-CB 1 R heteromer (i) is essentially absent from corticostriatal projections and striatonigral neurons, and, instead, is largely present in striatopallidal neurons, (ii) displays a striking G protein-coupled signaling profile, where co-stimulation of both receptors leads to strongly reduced downstream signaling, and (iii) undergoes an unprecedented dysfunction in Huntington's disease, an archetypal disease that affects striatal neurons. Altogether, our findings may open a new conceptual framework to understand the role of coordinated adenosine-endocannabinoid signaling in the indirect striatal pathway, which may be relevant in motor function and neurodegenerative diseases.

  7. The adenosine A2A receptor — Myocardial protectant and coronary target in endotoxemia

    Science.gov (United States)

    Reichelt, Melissa E.; Ashton, Kevin J.; Tan, Xing Lin; Mustafa, S. Jamal; Ledent, Catherine; Delbridge, Lea M.D.; Hofmann, Polly A.; Headrick, John P.; Morrison, R. Ray

    2013-01-01

    Background Cardiac injury and dysfunction are contributors to disease progression and mortality in sepsis. This study evaluated the cardiovascular role of intrinsic A2A adenosine receptor (A2AAR) activity during lipopolysaccharide (LPS)-induced inflammation. Methods We assessed the impact of 24 h of LPS challenge (20 mg/kg, IP) on cardiac injury, coronary function and inflammatory mediator levels in Wild-Type (WT) mice and mice lacking functional A2AARs (A2AAR KO). Results Cardiac injury was evident in LPS-treated WTs, with ∼7-fold elevation in serum cardiac troponin I (cTnI), and significant ventricular and coronary dysfunction. Absence of A2AARs increased LPS-provoked cTnI release at 24 h by 3-fold without additional demise of contraction function. Importantly, A2AAR deletion per se emulated detrimental effects of LPS on coronary function, and LPS was without effect in coronary vessels lacking A2AARs. Effects of A2AAR KO were independent of major shifts in circulating C-reactive protein (CRP) and haptoglobin. Cytokine responses were largely insensitive to A2AAR deletion; substantial LPS-induced elevations (up to 100-fold) in IFN-γ and IL-10 were unaltered in A2AAR KO mice, as were levels of IL-4 and TNF-α. However, late elevations in IL-2 and IL-5 were differentially modulated by A2AAR KO (IL-2 reduced, IL-5 increased). Data demonstrate that in the context of LPS-triggered cardiac and coronary injury, A2AAR activity protects myocardial viability without modifying contractile dysfunction, and selectively modulates cytokine (IL-2, IL-5) release. A2AARs also appear to be targeted by LPS in the coronary vasculature. Conclusions These experimental data suggest that preservation of A2AAR functionality might provide therapeutic benefit in human sepsis. PMID:22192288

  8. Genetic polymorphism of the adenosine A2A receptor is associated with habitual caffeine consumption.

    Science.gov (United States)

    Cornelis, Marilyn C; El-Sohemy, Ahmed; Campos, Hannia

    2007-07-01

    Caffeine is the most widely consumed stimulant in the world, and individual differences in response to its stimulating effects may explain some of the variability in caffeine consumption within a population. We examined whether genetic variability in caffeine metabolism [cytochrome P450 1A2 (CYP1A2) -163A-->C] or the main target of caffeine action in the nervous system [adenosine A(2A) receptor (ADORA2A) 1083C-->T] is associated with habitual caffeine consumption. Subjects (n=2735) were participants from a study of gene-diet interactions and risk of myocardial infarction who did not have a history of hypertension. Genotype frequencies were examined among persons who were categorized according to their self-reported daily caffeine intake, as assessed with a validated food-frequency questionnaire. The ADORA2A, but not the CYP1A2, genotype was associated with different amounts of caffeine intake. Compared with persons consuming caffeine/d, the odds ratios for having the ADORA2A TT genotype were 0.74 (95% CI: 0.53, 1.03), 0.63 (95% CI: 0.48, 0.83), and 0.57 (95% CI: 0.42, 0.77) for those consuming 100-200, >200-400, and >400 mg caffeine/d, respectively. The association was more pronounced among current smokers than among nonsmokers (P for interaction = 0.07). Persons with the ADORA2A TT genotype also were significantly more likely to consume less caffeine (ie, caffeine consumption increases. This observation provides a biologic basis for caffeine consumption behavior and suggests that persons with this genotype may be less vulnerable to caffeine dependence.

  9. Extracellular adenosine generation in the regulation of pro-inflammatory responses and pathogen colonization.

    Science.gov (United States)

    Alam, M Samiul; Costales, Matthew G; Cavanaugh, Christopher; Williams, Kristina

    2015-05-05

    Adenosine, an immunomodulatory biomolecule, is produced by the ecto-enzymes CD39 (nucleoside triphosphate dephosphorylase) and CD73 (ecto-5'-nucleotidase) by dephosphorylation of extracellular ATP. CD73 is expressed by many cell types during injury, infection and during steady-state conditions. Besides host cells, many bacteria also have CD39-CD73-like machinery, which helps the pathogen subvert the host inflammatory response. The major function for adenosine is anti-inflammatory, and most recent research has focused on adenosine's control of inflammatory mechanisms underlying various autoimmune diseases (e.g., colitis, arthritis). Although adenosine generated through CD73 provides a feedback to control tissue damage mediated by a host immune response, it can also contribute to immunosuppression. Thus, inflammation can be a double-edged sword: it may harm the host but eventually helps by killing the invading pathogen. The role of adenosine in dampening inflammation has been an area of active research, but the relevance of the CD39/CD73-axis and adenosine receptor signaling in host defense against infection has received less attention. Here, we review our recent knowledge regarding CD73 expression during murine Salmonellosis and Helicobacter-induced gastric infection and its role in disease pathogenesis and bacterial persistence. We also explored a possible role for the CD73/adenosine pathway in regulating innate host defense function during infection.

  10. Medicinal chemistry of adenosine, P2Y and P2X receptors.

    Science.gov (United States)

    Jacobson, Kenneth A; Müller, Christa E

    2016-05-01

    Pharmacological tool compounds are now available to define action at the adenosine (ARs), P2Y and P2X receptors. We present a selection of the most commonly used agents to study purines in the nervous system. Some of these compounds, including A1 and A3 AR agonists, P2Y1R and P2Y12R antagonists, and P2X3, P2X4 and P2X7 antagonists, are potentially of clinical use in treatment of disorders of the nervous system, such as chronic pain, neurodegeneration and brain injury. Agonists of the A2AAR and P2Y2R are already used clinically, P2Y12R antagonists are widely used antithrombotics and an antagonist of the A2AAR is approved in Japan for treating Parkinson's disease. The selectivity defined for some of the previously introduced compounds has been revised with updated pharmacological characterization, for example, various AR agonists and antagonists were deemed A1AR or A3AR selective based on human data, but species differences indicated a reduction in selectivity ratios in other species. Also, many of the P2R ligands still lack bioavailability due to charged groups or hydrolytic (either enzymatic or chemical) instability. X-ray crystallographic structures of AR and P2YRs have shifted the mode of ligand discovery to structure-based approaches rather than previous empirical approaches. The X-ray structures can be utilized either for in silico screening of chemically diverse libraries for the discovery of novel ligands or for enhancement of the properties of known ligands by chemical modification. Although X-ray structures of the zebrafish P2X4R have been reported, there is scant structural information about ligand recognition in these trimeric ion channels. In summary, there are definitive, selective agonists and antagonists for all of the ARs and some of the P2YRs; while the pharmacochemistry of P2XRs is still in nascent stages. The therapeutic potential of selectively modulating these receptors is continuing to gain interest in such fields as cancer, inflammation, pain

  11. Adenosine A2A receptors in the nucleus accumbens bi-directionally alter cocaine seeking in rats.

    Science.gov (United States)

    O'Neill, Casey E; LeTendre, McKenzie L; Bachtell, Ryan K

    2012-04-01

    Repeated cocaine administration enhances dopamine D(2) receptor sensitivity in the mesolimbic dopamine system, which contributes to drug relapse. Adenosine A(2A) receptors are colocalized with D(2) receptors on nucleus accumbens (NAc) medium spiny neurons where they antagonize D(2) receptor activity. Thus, A(2A) receptors represent a target for reducing enhanced D(2) receptor sensitivity that contributes to cocaine relapse. The aim of these studies were to determine the effects of adenosine A(2A) receptor modulation in the NAc on cocaine seeking in rats that were trained to lever press for cocaine. Following at least 15 daily self-administration sessions and 1 week of abstinence, lever pressing was extinguished in daily extinction sessions. We subsequently assessed the effects of intra-NAc core microinjections of the A(2A) receptor agonist, CGS 21680 (4-[2-[[6-amino-9-(N-ethyl-b-D-ribofuranuronamidosyl)-9H-purin-2-yl]amino]ethyl]benzenepropanoic acid hydrochloride), and the A(2A) receptor antagonist, MSX-3 (3,7-dihydro-8-[(1E)-2-(3-methoxyphenyl)ethenyl]-7-methyl-3-[3-(phosphonooxy)propyl-1-(2-propynyl)-1H-purine-2,6-dione disodium salt hydrate), in modulating cocaine- and quinpirole-induced reinstatement to cocaine seeking. Intra-NAc pretreatment of CGS 21680 reduced both cocaine- and quinpirole-induced reinstatement. These effects were specific to cocaine reinstatement as intra-NAc CGS 21680 had no effect on sucrose seeking in rats trained to self-administer sucrose pellets. Intra-NAc treatment with MSX-3 modestly reinstated cocaine seeking when given alone, and exacerbated both cocaine- and quinpirole-induced reinstatement. Interestingly, the exacerbation of cocaine seeking produced by MSX-3 was only observed at sub-threshold doses of cocaine and quinpirole, suggesting that removing tonic A(2A) receptor activity enables behaviors mediated by dopamine receptors. Taken together, these findings suggest that A(2A) receptor stimulation reduces, while A(2A) blockade

  12. Adenosine A2A Receptors in the Nucleus Accumbens Bi-Directionally Alter Cocaine Seeking in Rats

    Science.gov (United States)

    O'Neill, Casey E; LeTendre, Mckenzie L; Bachtell, Ryan K

    2012-01-01

    Repeated cocaine administration enhances dopamine D2 receptor sensitivity in the mesolimbic dopamine system, which contributes to drug relapse. Adenosine A2A receptors are colocalized with D2 receptors on nucleus accumbens (NAc) medium spiny neurons where they antagonize D2 receptor activity. Thus, A2A receptors represent a target for reducing enhanced D2 receptor sensitivity that contributes to cocaine relapse. The aim of these studies were to determine the effects of adenosine A2A receptor modulation in the NAc on cocaine seeking in rats that were trained to lever press for cocaine. Following at least 15 daily self-administration sessions and 1 week of abstinence, lever pressing was extinguished in daily extinction sessions. We subsequently assessed the effects of intra-NAc core microinjections of the A2A receptor agonist, CGS 21680 (4-[2-[[6-amino-9-(N-ethyl-b--ribofuranuronamidosyl)-9H-purin-2-yl]amino]ethyl]benzenepropanoic acid hydrochloride), and the A2A receptor antagonist, MSX-3 (3,7-dihydro-8-[(1E)-2-(3-methoxyphenyl)ethenyl]-7-methyl-3-[3-(phosphonooxy)propyl-1-(2-propynyl)-1H-purine-2,6-dione disodium salt hydrate), in modulating cocaine- and quinpirole-induced reinstatement to cocaine seeking. Intra-NAc pretreatment of CGS 21680 reduced both cocaine- and quinpirole-induced reinstatement. These effects were specific to cocaine reinstatement as intra-NAc CGS 21680 had no effect on sucrose seeking in rats trained to self-administer sucrose pellets. Intra-NAc treatment with MSX-3 modestly reinstated cocaine seeking when given alone, and exacerbated both cocaine- and quinpirole-induced reinstatement. Interestingly, the exacerbation of cocaine seeking produced by MSX-3 was only observed at sub-threshold doses of cocaine and quinpirole, suggesting that removing tonic A2A receptor activity enables behaviors mediated by dopamine receptors. Taken together, these findings suggest that A2A receptor stimulation reduces, while A2A blockade amplifies, D2 receptor

  13. Adenosine A₁ and A₂A receptor-mediated modulation of acetylcholine release in the mice neuromuscular junction.

    Science.gov (United States)

    Garcia, Neus; Priego, Mercedes; Obis, Teresa; Santafe, Manel M; Tomàs, Marta; Besalduch, Nuria; Lanuza, M Angel; Tomàs, Josep

    2013-07-01

    Immunocytochemistry shows that purinergic receptors (P1Rs) type A1 and A2A (A1 R and A2 A R, respectively) are present in the nerve endings at the P6 and P30 Levator auris longus (LAL) mouse neuromuscular junctions (NMJs). As described elsewhere, 25 μm adenosine reduces (50%) acetylcholine release in high Mg(2+) or d-tubocurarine paralysed muscle. We hypothesize that in more preserved neurotransmission machinery conditions (blocking the voltage-dependent sodium channel of the muscle cells with μ-conotoxin GIIIB) the physiological role of the P1Rs in the NMJ must be better observed. We found that the presence of a non-selective P1R agonist (adenosine) or antagonist (8-SPT) or selective modulators of A1 R or A2 A R subtypes (CCPA and DPCPX, or CGS-21680 and SCH-58261, respectively) does not result in any changes in the evoked release. However, P1Rs seem to be involved in spontaneous release (miniature endplate potentials MEPPs) because MEPP frequency is increased by non-selective block but decreased by non-selective stimulation, with A1 Rs playing the main role. We assayed the role of P1Rs in presynaptic short-term plasticity during imposed synaptic activity (40 Hz for 2 min of supramaximal stimuli). Depression is reduced by micromolar adenosine but increased by blocking P1Rs with 8-SPT. Synaptic depression is not affected by the presence of selective A1 R and A2 A R modulators, which suggests that both receptors need to collaborate. Thus, A1 R and A2 A R might have no real effect on neuromuscular transmission in resting conditions. However, these receptors can conserve resources by limiting spontaneous quantal leak of acetylcholine and may protect synaptic function by reducing the magnitude of depression during repetitive activity. © 2013 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

  14. Structure-Activity Relationships of Truncated C2- or C8-Substituted Adenosine Derivatives as Dual Acting A2A and A3 Adenosine Receptor Ligands

    Science.gov (United States)

    Hou, Xiyan; Majik, Mahesh S.; Kim, Kyunglim; Pyee, Yuna; Lee, Yoonji; Alexander, Varughese; Chung, Hwa-Jin; Lee, Hyuk Woo; Chandra, Girish; Lee, Jin Hee; Park, Seul-gi; Choi, Won Jun; Kim, Hea Ok; Phan, Khai; Gao, Zhan-Guo; Jacobson, Kenneth A.; Choi, Sun; Lee, Sang Kook; Jeong, Lak Shin

    2011-01-01

    Truncated N6-substituted-4′-oxo- and 4′-thioadenosine derivatives with C2 or C8 substitution were studied as dual acting A2A and A3 adenosine receptor (AR) ligands. The lithiation-mediated stannyl transfer and palladium-catalyzed cross coupling reactions were utilized for functionalization of the C2 position of 6-chloropurine nucleosides. An unsubstituted 6-amino group and a hydrophobic C2 substituent were required for high affinity at the hA2AAR, but hydrophobic C8 substitution abolished binding at the hA2AAR. However, most of synthesized compounds displayed medium to high binding affinity at the hA3AR, regardless of C2 or C8 substitution, and low efficacy in a functional cAMP assay. Several compounds tended to be full hA2AAR agonists. C2 substitution probed geometrically through hA2AAR-docking, was important for binding in order of hexynyl > hexenyl > hexanyl. Compound 4g was the most potent ligand acting dually as hA2AAR agonist and hA3AR antagonist, which might be useful for treatment of asthma or other inflammatory diseases. PMID:22142423

  15. Insulin-increased L-arginine transport requires A(2A adenosine receptors activation in human umbilical vein endothelium.

    Directory of Open Access Journals (Sweden)

    Enrique Guzmán-Gutiérrez

    Full Text Available Adenosine causes vasodilation of human placenta vasculature by increasing the transport of arginine via cationic amino acid transporters 1 (hCAT-1. This process involves the activation of A(2A adenosine receptors (A(2AAR in human umbilical vein endothelial cells (HUVECs. Insulin increases hCAT-1 activity and expression in HUVECs, and A(2AAR stimulation increases insulin sensitivity in subjects with insulin resistance. However, whether A(2AAR plays a role in insulin-mediated increase in L-arginine transport in HUVECs is unknown. To determine this, we first assayed the kinetics of saturable L-arginine transport (1 minute, 37°C in the absence or presence of nitrobenzylthioinosine (NBTI, 10 µmol/L, adenosine transport inhibitor and/or adenosine receptors agonist/antagonists. We also determined hCAT-1 protein and mRNA expression levels (Western blots and quantitative PCR, and SLC7A1 (for hCAT-1 reporter promoter activity. Insulin and NBTI increased the extracellular adenosine concentration, the maximal velocity for L-arginine transport without altering the apparent K(m for L-arginine transport, hCAT-1 protein and mRNA expression levels, and SLC7A1 transcriptional activity. An A2AAR antagonist ZM-241385 blocked these effects. ZM241385 inhibited SLC7A1 reporter transcriptional activity to the same extent in cells transfected with pGL3-hCAT-1(-1606 or pGL3-hCAT-1(-650 constructs in the presence of NBTI + insulin. However, SLC7A1 reporter activity was increased by NBTI only in cells transfected with pGL3-hCAT-1(-1606, and the ZM-241385 sensitive fraction of the NBTI response was similar in the absence or in the presence of insulin. Thus, insulin modulation of hCAT-1 expression and activity requires functional A(2AAR in HUVECs, a mechanism that may be applicable to diseases associated with fetal insulin resistance, such as gestational diabetes.

  16. Adenosine A1 receptor antagonist mitigates deleterious effects of sleep deprivation on adult neurogenesis and spatial reference memory in rats.

    Science.gov (United States)

    Chauhan, G; Ray, K; Sahu, S; Roy, K; Jain, V; Wadhwa, M; Panjwani, U; Kishore, K; Singh, S B

    2016-11-19

    Sleep deprivation (SD) upsurges intracellular levels of adenosine, impairs adult neuronal cell proliferation (NCP) and cognition while caffeine, a non-selective adenosine A1 receptor (A1R) antagonist improves cognition and adult NCP during SD. We examined the selective antagonistic effects of adenosine A1R using 8-cyclopentyl-1,3-dimethylxanthine (8-CPT) on impairment of spatial reference memory and adult NCP during 48h SD. Adult male Sprague Dawley rats were sleep deprived for 48h, using an automatic cage vibrating stimulus based on animal activity. Spatial reference memory was tested as a measure of cognitive performance employing Morris Water Maze. Rats were given 8-CPT dissolved in 50% dimethyl sulfoxide (DMSO), twice daily (10mg/kg, i.p.) along with 5-bromo-2-deoxyuridine (BrdU) (50mg/kg/day, i.p.). The rats treated with 8-CPT showed significantly short mean latency and path-length to reach the platform compared to the SD rats. Consistent with these findings, 8-CPT-treated group was found to have significantly increased the number of BrdU, Ki-67 and doublecortin (DCX) positive cells. However, no significant difference was seen in NeuN expression in the Dentate Gyrus (DG). Brain-derived neurotropic factor (BDNF) expression in the DG and CA1 region was observed to decrease significantly after SD and be rescued by 8-CPT treatment. Furthermore, latency to reach platform showed a negative correlation with number of BrdU, DCX type-1 cells and BDNF expression in DG. Thus, it may be concluded that treatment with 8-CPT, an adenosine A1R antagonist during SD mitigates SD induced decline in spatial reference memory and adult NCP possibly via up regulation of BDNF levels in DG and CA1 regions. Copyright © 2016 IBRO. Published by Elsevier Ltd. All rights reserved.

  17. β-Nicotinamide adenine dinucleotide acts at prejunctional adenosine A1 receptors to suppress inhibitory musculomotor neurotransmission in guinea pig colon and human jejunum

    Science.gov (United States)

    Wang, Guo-Du; Wang, Xi-Yu; Liu, Sumei; Xia, Yun; Zou, Fei; Qu, Meihua; Needleman, Bradley J.; Mikami, Dean J.

    2015-01-01

    Intracellular microelectrodes were used to record neurogenic inhibitory junction potentials in the intestinal circular muscle coat. Electrical field stimulation was used to stimulate intramural neurons and evoke contraction of the smooth musculature. Exposure to β-nicotinamide adenine dinucleotide (β-NAD) did not alter smooth muscle membrane potential in guinea pig colon or human jejunum. ATP, ADP, β-NAD, and adenosine, as well as the purinergic P2Y1 receptor antagonists MRS 2179 and MRS 2500 and the adenosine A1 receptor agonist 2-chloro-N6-cyclopentyladenosine, each suppressed inhibitory junction potentials in guinea pig and human preparations. β-NAD suppressed contractile force of twitch-like contractions evoked by electrical field stimulation in guinea pig and human preparations. P2Y1 receptor antagonists did not reverse this action. Stimulation of adenosine A1 receptors with 2-chloro-N6-cyclopentyladenosine suppressed the force of twitch contractions evoked by electrical field stimulation in like manner to the action of β-NAD. Blockade of adenosine A1 receptors with 8-cyclopentyl-1,3-dipropylxanthine suppressed the inhibitory action of β-NAD on the force of electrically evoked contractions. The results do not support an inhibitory neurotransmitter role for β-NAD at intestinal neuromuscular junctions. The data suggest that β-NAD is a ligand for the adenosine A1 receptor subtype expressed by neurons in the enteric nervous system. The influence of β-NAD on intestinal motility emerges from adenosine A1 receptor-mediated suppression of neurotransmitter release at inhibitory neuromuscular junctions. PMID:25813057

  18. Adenosine A1 receptors in human sleep regulation studied by electroencephalography (EEG) and positron emission tomography (PET)

    International Nuclear Information System (INIS)

    Geissler, E.

    2007-01-01

    Sleep is an essential physiological process. However, the functions of sleep and the endogenous mechanisms involved in sleep regulation are only partially understood. Convergent lines of evidence support the hypothesis that the build-up of sleep propensity during wakefulness and its decline during sleep are associated with alterations in brain adenosine levels and adenosine receptor concentrations. The non-selective A 1 and A 2A adenosine receptor antagonist caffeine stimulates alertness and is known to attenuate changes in the waking and sleep electroencephalogram (EEG) typically observed after prolonged waking. Several findings point to an important function of the adenosine A 1 receptor (A 1 AR) in the modulation of vigilance states. The A 1 AR is densely expressed in brain regions involved in sleep regulation, and pharmacological manipulations affecting the A 1 AR were shown to influence sleep propensity and sleep depth. However, an involvement of the A 2A adenosine receptor (A 2A AR) is also assumed. The distinct functions of the A 1 and A 2A receptor subtypes in sleep-wake regulation and in mediating the effects of caffeine have not been identified so far. The selective adenosine A 1 receptor antagonist, 8-cyclopentyl-3-(3- 18 Ffluoropropyl)- 1-propylxanthine ( 18 F-CPFPX), offers the opportunity to get further insights into adenosinergic mechanisms by in vivo imaging of the A 1 AR subtype with positron emission tomography (PET). The aim of this thesis was to elucidate the role of adenosine A 1 receptors in human sleep regulation, combining 18 F-CPFPX PET brain imaging and EEG recordings, the gold standard in sleep research. It was hypothesized that sleep deprivation would induce adenosine accumulation and/or changes in A 1 AR density. Thus, the question was addressed whether these effects of prolonged wakefulness can be visualized by altered 18 F-CPFPX binding. Moreover, it was investigated whether radioligand uptake might be influenced by caffeine, since

  19. Autoradiographic visualization of A 1-adenosine receptors in brain and peripheral tissues of rat and guinea pig using 125I-HPIA

    International Nuclear Information System (INIS)

    Weber, R.G.; Lohse, M.J.; Jones, C.R.; Palacios, J.M.

    1988-01-01

    A 1 -adenosine receptors were identified in sections of rat brain and guinea pig kidney with the radioiodinated agonist 1 25I-N 6 -p-hydroxyphenylisopropyladenosine ( 1 25I-HPIA) using in vitro autoradiography. The affinities of adenosine receptor ligands in competing with 1 25I-HPIA binding to tissue sections were in good agreement with those found in membranes and indicate that the binding site represents an A 1 pattern of [ 3 H]N 6 -cyclohexyladenosine ([ 3 H]CHA) binding sites determined previously, with highest densities in the hippocampus and dentate gyrus, the cerebellar cortex, some thalamic nuclei and certain layers of the cerebral cortex. In the guinea pig kidney 1 25I-HPIA labelled longitudinal structures in the medulla. This study demonstrates that 1 25I-HPIA allows the autoradiographic detection of A-1 adenosine receptors in the brain and peripheral organs and has the advantage of short exposure times (author)

  20. Role of adenosine A2A receptor signaling in the nicotine-evoked attenuation of reflex cardiac sympathetic control

    International Nuclear Information System (INIS)

    El-Mas, Mahmoud M.; El-gowilly, Sahar M.; Fouda, Mohamed A.; Saad, Evan I.

    2011-01-01

    Baroreflex dysfunction contributes to increased cardiovascular risk in cigarette smokers. Given the importance of adenosinergic pathways in baroreflex control, the hypothesis was tested that defective central adenosinergic modulation of cardiac autonomic activity mediates the nicotine-baroreflex interaction. Baroreflex curves relating changes in heart rate (HR) to increases or decreases in blood pressure (BP) evoked by i.v. doses (1-16 μg/kg) of phenylephrine (PE) and sodium nitroprusside (SNP), respectively, were constructed in conscious rats; slopes of the curves were taken as measures of baroreflex sensitivity (BRS). Nicotine (25 and 100 μg/kg i.v.) dose-dependently reduced BRS SNP in contrast to no effect on BRS PE . BRS SNP was also attenuated after intracisternal (i.c.) administration of nicotine. Similar reductions in BRS SNP were observed in rats pretreated with atropine or propranolol. The combined treatment with nicotine and atropine produced additive inhibitory effects on BRS, an effect that was not demonstrated upon concurrent exposure to nicotine and propranolol. BRS SNP was reduced in preparations treated with i.c. 8-phenyltheophylline (8-PT, nonselective adenosine receptor antagonist), 8-(3-Chlorostyryl) caffeine (CSC, A 2A antagonist), or VUF5574 (A 3 antagonist). In contrast, BRS SNP was preserved after blockade of A 1 (DPCPX) or A 2B (alloxazine) receptors or inhibition of adenosine uptake by dipyridamole. CSC or 8-PT abrogated the BRS SNP depressant effect of nicotine whereas other adenosinergic antagonists were without effect. Together, nicotine preferentially impairs reflex tachycardia via disruption of adenosine A 2A receptor-mediated facilitation of reflex cardiac sympathoexcitation. Clinically, the attenuation by nicotine of compensatory sympathoexcitation may be detrimental in conditions such as hypothalamic defense response, posture changes, and ventricular rhythms. - Research highlights: → The role of central adenosinergic sites in

  1. A1 adenosine receptor-induced phosphorylation and modulation of transglutaminase 2 activity in H9c2 cells: A role in cell survival.

    Science.gov (United States)

    Vyas, Falguni S; Hargreaves, Alan J; Bonner, Philip L R; Boocock, David J; Coveney, Clare; Dickenson, John M

    2016-05-01

    The regulation of tissue transglutaminase (TG2) activity by the GPCR family is poorly understood. In this study, we investigated the modulation of TG2 activity by the A1 adenosine receptor in cardiomyocyte-like H9c2 cells. H9c2 cells were lysed following stimulation with the A1 adenosine receptor agonist N(6)-cyclopentyladenosine (CPA). Transglutaminase activity was determined using an amine incorporating and a protein cross linking assay. TG2 phosphorylation was assessed via immunoprecipitation and Western blotting. The role of TG2 in A1 adenosine receptor-induced cytoprotection was investigated by monitoring hypoxia-induced cell death. CPA induced time and concentration-dependent increases in amine incorporating and protein crosslinking activity of TG2. CPA-induced increases in TG2 activity were attenuated by the TG2 inhibitors Z-DON and R283. Responses to CPA were blocked by PKC (Ro 31-8220), MEK1/2 (PD 98059), p38 MAPK (SB 203580) and JNK1/2 (SP 600125) inhibitors and by removal of extracellular Ca(2+). CPA triggered robust increases in the levels of TG2-associated phosphoserine and phosphothreonine, which were attenuated by PKC, MEK1/2 and JNK1/2 inhibitors. Fluorescence microscopy revealed TG2-mediated biotin-X-cadaverine incorporation into proteins and proteomic analysis identified known (Histone H4) and novel (Hexokinase 1) protein substrates for TG2. CPA pre-treatment reversed hypoxia-induced LDH release and decreases in MTT reduction. TG2 inhibitors R283 and Z-DON attenuated A1 adenosine receptor-induced cytoprotection. TG2 activity was stimulated by the A1 adenosine receptor in H9c2 cells via a multi protein kinase dependent pathway. These results suggest a role for TG2 in A1 adenosine receptor-induced cytoprotection. Copyright © 2016 Elsevier Inc. All rights reserved.

  2. Erythropoiesis- and Thrombopoiesis-Characterizing Parameters in Adenosine A(3) Receptor Knock-Out Mice

    Czech Academy of Sciences Publication Activity Database

    Hofer, Michal; Pospíšil, Milan; Dušek, L.; Hoferová, Zuzana; Weiterová, Lenka

    2013-01-01

    Roč. 62, č. 3 (2013), s. 305-311 ISSN 0862-8408 R&D Projects: GA ČR(CZ) GAP303/11/0128 Institutional support: RVO:68081707 Keywords : ELEVATING EXTRACELLULAR ADENOSINE * COLONY-STIMULATING FACTOR * HEMATOPOIETIC PROGENITOR CELLS Subject RIV: BO - Biophysics Impact factor: 1.487, year: 2013

  3. Synthetic adenosine receptor agonists modulate murine haematopoiesis: a study employing the cytotoxic action of 5-fluorouracil

    Czech Academy of Sciences Publication Activity Database

    Hofer, Michal; Pospíšil, Milan; Vacek, Antonín; Znojil, V.; Pipalová, I.

    2004-01-01

    Roč. 5, Suppl. 2 (2004), s. S65 ISSN 1466-4860. [Congress of the European Hematology Association /9./. 10.06.2004-13.06.2004, Geneva] R&D Projects: GA ČR GA305/02/0423 Keywords : 5-fluorouracil * haematopoiesis * adenosine Subject RIV: BO - Biophysics

  4. Adenosine A(2A) receptor gene (ADORA2A) variants may increase autistic symptoms and anxiety in autism spectrum disorder.

    Science.gov (United States)

    Freitag, Christine M; Agelopoulos, Konstantin; Huy, Ellen; Rothermundt, Matthias; Krakowitzky, Petra; Meyer, Jobst; Deckert, Jürgen; von Gontard, Alexander; Hohoff, Christa

    2010-01-01

    Autism spectrum disorders (ASDs) are heterogeneous disorders presenting with increased rates of anxiety. The adenosine A(2A) receptor gene (ADORA2A) is associated with panic disorder and is located on chromosome 22q11.23. Its gene product, the adenosine A(2A) receptor, is strongly expressed in the caudate nucleus, which also is involved in ASD. As autistic symptoms are increased in individuals with 22q11.2 deletion syndrome, and large 22q11.2 deletions and duplications have been observed in ASD individuals, in this study, 98 individuals with ASD and 234 control individuals were genotyped for eight single-nucleotide polymorphisms in ADORA2A. Nominal association with the disorder was observed for rs2236624-CC, and phenotypic variability in ASD symptoms was influenced by rs3761422, rs5751876 and rs35320474. In addition, association of ADORA2A variants with anxiety was replicated for individuals with ASD. Findings point toward a possible mediating role of ADORA2A variants on phenotypic expression in ASD that need to be replicated in a larger sample.

  5. Neuroprotection by caffeine in the MPTP model of parkinson's disease and its dependence on adenosine A2A receptors.

    Science.gov (United States)

    Xu, K; Di Luca, D G; Orrú, M; Xu, Y; Chen, J-F; Schwarzschild, M A

    2016-05-13

    Considerable epidemiological and laboratory data have suggested that caffeine, a nonselective adenosine receptor antagonist, may protect against the underlying neurodegeneration of parkinson's disease (PD). Although both caffeine and more specific antagonists of the A2A subtype of adenosine receptor (A2AR) have been found to confer protection in animal models of PD, the dependence of caffeine's neuroprotective effects on the A2AR is not known. To definitively determine its A2AR dependence, the effect of caffeine on 1-methyl-4-phenyl-1,2,3,6 tetra-hydropyridine (MPTP) neurotoxicity was compared in wild-type (WT) and A2AR gene global knockout (A2A KO) mice, as well as in central nervous system (CNS) cell type-specific (conditional) A2AR knockout (cKO) mice that lack the receptor either in postnatal forebrain neurons or in astrocytes. In WT and in heterozygous A2AR KO mice caffeine pretreatment (25mg/kgip) significantly attenuated MPTP-induced depletion of striatal dopamine. By contrast in homozygous A2AR global KO mice caffeine had no effect on MPTP toxicity. In forebrain neuron A2AR cKO mice, caffeine lost its locomotor stimulant effect, whereas its neuroprotective effect was mostly preserved. In astrocytic A2AR cKO mice, both caffeine's locomotor stimulant and protective properties were undiminished. Taken together, these results indicate that neuroprotection by caffeine in the MPTP model of PD relies on the A2AR, although the specific cellular localization of these receptors remains to be determined. Copyright © 2016 IBRO. All rights reserved.

  6. Protein kinase A mediates adenosine A2a receptor modulation of neurotransmitter release via synapsin I phosphorylation in cultured cells from medulla oblongata.

    Science.gov (United States)

    Matsumoto, Joao Paulo Pontes; Almeida, Marina Gomes; Castilho-Martins, Emerson Augusto; Costa, Maisa Aparecida; Fior-Chadi, Debora Rejane

    2014-08-01

    Synaptic transmission is an essential process for neuron physiology. Such process is enabled in part due to modulation of neurotransmitter release. Adenosine is a synaptic modulator of neurotransmitter release in the Central Nervous System, including neurons of medulla oblongata, where several nuclei are involved with neurovegetative reflexes. Adenosine modulates different neurotransmitter systems in medulla oblongata, specially glutamate and noradrenaline in the nucleus tractussolitarii, which are involved in hypotensive responses. However, the intracellular mechanisms involved in this modulation remain unknown. The adenosine A2a receptor modulates neurotransmitter release by activating two cAMP protein effectors, the protein kinase A and the exchange protein activated by cAMP. Therefore, an in vitro approach (cultured cells) was carried out to evaluate modulation of neurotransmission by adenosine A2a receptor and the signaling intracellular pathway involved. Results show that the adenosine A2a receptor agonist, CGS 21680, increases neurotransmitter release, in particular, glutamate and noradrenaline and such response is mediated by protein kinase A activation, which in turn increased synapsin I phosphorylation. This suggests a mechanism of A2aR modulation of neurotransmitter release in cultured cells from medulla oblongata of Wistar rats and suggest that protein kinase A mediates this modulation of neurotransmitter release via synapsin I phosphorylation. Copyright © 2014 Elsevier Ireland Ltd and the Japan Neuroscience Society. All rights reserved.

  7. Prevention of adenosine A2A receptor activation diminishes beat-to-beat alternation in human atrial myocytes.

    Science.gov (United States)

    Molina, Cristina E; Llach, Anna; Herraiz-Martínez, Adela; Tarifa, Carmen; Barriga, Montserrat; Wiegerinck, Rob F; Fernandes, Jacqueline; Cabello, Nuria; Vallmitjana, Alex; Benitéz, Raúl; Montiel, José; Cinca, Juan; Hove-Madsen, Leif

    2016-01-01

    Atrial fibrillation (AF) has been associated with increased spontaneous calcium release from the sarcoplasmic reticulum and linked to increased adenosine A2A receptor (A2AR) expression and activation. Here we tested whether this may favor atrial arrhythmogenesis by promoting beat-to-beat alternation and irregularity. Patch-clamp and confocal calcium imaging was used to measure the beat-to-beat response of the calcium current and transient in human atrial myocytes. Responses were classified as uniform, alternating or irregular and stimulation of Gs-protein coupled receptors decreased the frequency where a uniform response could be maintained from 1.0 ± 0.1 to 0.6 ± 0.1 Hz; p < 0.01 for beta-adrenergic receptors and from 1.4 ± 0.1 to 0.5 ± 0.1 Hz; p < 0.05 for A2ARs. The latter was linked to increased spontaneous calcium release and after-depolarizations. Moreover, A2AR activation increased the fraction of non-uniformly responding cells in HL-1 myocyte cultures from 19 ± 3 to 51 ± 9 %; p < 0.02, and electrical mapping in perfused porcine atria revealed that adenosine induced electrical alternans at longer cycle lengths, doubled the fraction of electrodes showing alternation, and increased the amplitude of alternations. Importantly, protein kinase A inhibition increased the highest frequency where uniform responses could be maintained from 0.84 ± 0.12 to 1.86 ± 0.11 Hz; p < 0.001 and prevention of A2AR-activation with exogenous adenosine deaminase selectively increased the threshold from 0.8 ± 0.1 to 1.2 ± 0.1 Hz; p = 0.001 in myocytes from patients with AF. In conclusion, A2AR-activation promotes beat-to-beat irregularities in the calcium transient in human atrial myocytes, and prevention of A2AR activation may be a novel means to maintain uniform beat-to-beat responses at higher beating frequencies in patients with atrial fibrillation.

  8. The role of adenosine receptor agonist and antagonist on Hippocampal MDMA detrimental effects; a structural and behavioral study.

    Science.gov (United States)

    Kermanian, Fatemeh; Mehdizadeh, Mehdi; Soleimani, Mansureh; Ebrahimzadeh Bideskan, Ali Reza; Asadi-Shekaari, Majid; Kheradmand, Hamed; Haghir, Hossein

    2012-12-01

    There is abundant evidence showing that repeated use of MDMA (3, 4-Methylenedioxymethamphetamine, ecstasy) has been associated with depression, anxiety and deficits in learning and memory, suggesting detrimental effects on hippocampus. Adenosine is an endogenous purine nucleoside that has a neuromodulatory role in the central nervous system. In the present study, we investigated the role of A2a adenosine receptors agonist (CGS) and antagonist (SCH) on the body temperature, learning deficits, and hippocampal cell death induced by MDMA administration. In this study, 63 adult, male, Sprague - Dawley rats were subjected to MDMA (10 and 20 mg/kg) followed by intraperitoneal CGS (0.03 mg/kg) or SCH (0.03 mg/kg) injection. The animals were tested for spatial learning in the Morris water maze (MWM) task performance, accompanied by a recording of body temperature, electron microscopy and stereological study. Our results showed that MDMA treatment increased body temperature significantly, and impaired the ability of rats to locate the hidden platform(P learning deficits observed in MDMA users. However, the exact mechanism of these interactions requires further studies.

  9. Greater adenosine A2A receptor densities in cardiac and skeletal muscle in endurance-trained men: a [11C]TMSX PET study

    International Nuclear Information System (INIS)

    Mizuno, Masaki; Kimura, Yuichi; Tokizawa, Ken; Ishii, Kenji; Oda, Keiichi; Sasaki, Toru; Nakamura, Yoshio; Muraoka, Isao; Ishiwata, Kiichi

    2005-01-01

    We examined the densities of adenosine A 2A receptors in cardiac and skeletal muscles between untrained and endurance-trained subjects using positron emission tomography (PET) and [7-methyl- 11 C]-(E)-8-(3,4,5-trimethoxystyryl)-1,3,7-trimethylxanthine ([ 11 C]TMSX), a newly developed radioligand for mapping adenosine A 2A receptors. Five untrained and five endurance-trained subjects participated in this study. The density of adenosine A 2A receptors was evaluated as the distribution volume of [ 11 C]TMSX in cardiac and triceps brachii muscles in the resting state using PET. The distribution volume of [ 11 C]TMSX in the myocardium was significantly greater than in the triceps brachii muscle in both groups. Further, distribution volumes [ 11 C]TMSX in the trained subjects were significantly grater than those in untrained subjects (myocardium, 3.6±0.3 vs. 3.1±0.4 ml g -1 ; triceps brachii muscle, 1.7±0.3 vs. 1.2±0.2 ml g -1 , respectively). These results indicate that the densities of adenosine A 2A receptors in the cardiac and skeletal muscles are greater in the endurance-trained men than in the untrained men

  10. Caffeine consumption prevents memory impairment, neuronal damage, and adenosine A2A receptors upregulation in the hippocampus of a rat model of sporadic dementia.

    Science.gov (United States)

    Espinosa, Janaína; Rocha, Andreia; Nunes, Fernanda; Costa, Marcelo S; Schein, Vanessa; Kazlauckas, Vanessa; Kalinine, Eduardo; Souza, Diogo O; Cunha, Rodrigo A; Porciúncula, Lisiane O

    2013-01-01

    Intracerebroventricular (icv) streptozotocin (STZ) administration induces pathological and behavioral alterations similar to those observed in Alzheimer's disease (AD) and is thus considered an experimental model of sporadic AD. Since caffeine (an adenosine receptor antagonist) and selective antagonists of adenosine A2A receptors modify the course of memory impairment in different amyloid-β-based experimental models of AD, we now tested the impact of caffeine on STZ-induced dementia and associated neurodegeneration in the hippocampus as well as on the expression and density of adenosine receptors. Adult male rats received a bilateral infusion of saline or STZ (3 mg/kg, icv), which triggered memory deficits after four weeks, as gauged by impaired object recognition memory. This was accompanied by a reduced NeuN immunoreactivity in the hippocampal CA1 region and an increased expression and density of adenosine A2A receptors (A2AR), but not A1R, in the hippocampus. Caffeine consumption (1 g/L in the drinking water starting 2 weeks before the STZ challenge) prevented the STZ-induced memory impairment and neurodegeneration as well as the upregulation of A2AR. These findings provide the first demonstration that caffeine prevents sporadic dementia and implicate the control of central A2AR as its likely mechanism of action.

  11. New 2-alkynyl derivatives of the acyclic nucleoside 9-(2,3-dihydroxypropyl)adenine and their 6-guanidinopurine counterparts as potential effectors of adenosine receptors

    Czech Academy of Sciences Publication Activity Database

    Česnek, Michal; Holý, Antonín; Masojídková, Milena

    2003-01-01

    Roč. 68, č. 11 (2003), s. 2201-2218 ISSN 0010-0765 R&D Projects: GA AV ČR IBS4055109; GA MŠk OC D13.20 Institutional research plan: CEZ:AV0Z4055905 Keywords : adenosine receptors * alkynes * purines Subject RIV: CC - Organic Chemistry Impact factor: 1.041, year: 2003

  12. Activation of adenosine A3 receptors supports hematopoiesis-stimulating effects of granulocyte colony-stimulating factor in sublethally irradiated mice

    Czech Academy of Sciences Publication Activity Database

    Hofer, Michal; Pospíšil, Milan; Šefc, L.; Dušek, L.; Vacek, Antonín; Holá, Jiřina; Hoferová, Zuzana; Štreitová, Denisa

    2010-01-01

    Roč. 86, č. 8 (2010), s. 649-656 ISSN 0955-3002 R&D Projects: GA ČR(CZ) GA305/08/0158 Institutional research plan: CEZ:AV0Z50040507; CEZ:AV0Z50040702 Keywords : ionising radiation * hematopoiesis * adenosine A3 receptors Subject RIV: BO - Biophysics Impact factor: 1.861, year: 2010

  13. Radiation Dosimetry of a Novel Adenosine A(2A) Receptor Radioligand [C-11]Preladenant Based on PET/CT Imaging and Ex Vivo Biodistribution in Rats

    NARCIS (Netherlands)

    Zhou, Xiaoyun; Elsinga, Philip H.; Khanapur, Shivashankar; Dierckx, Rudi A. J. O.; de Vries, Erik F. J.; de Jong, Johan R.

    [C-11]Preladenant was developed as a novel adenosine A(2A) receptor PET radioligand. The aim of this study was to determine the radiation dosimetry of [C-11]preladenant and to investigate whether dosimetry estimation based on organ harvesting can be replaced by positron emission tomography

  14. Adenosine A1 receptor mRNA expression and the effects of systemic theophylline administration on respiratory function 4 months after C2 hemisection.

    Science.gov (United States)

    Nantwi, Kwaku D; Basura, Gregory J; Goshgarian, Harry G

    2003-01-01

    Previous studies from our laboratory have demonstrated that in an animal model of acute cervical spinal cord injury (SCI), respiratory function can be restored by theophylline. We also have shown that respiratory recovery occurs spontaneously after prolonged postinjury survival periods when a hemidiaphragm is paralyzed by an ipsilateral upper cervical (C2) spinal cord hemisection. Theophylline mediates functional recovery by central nervous system adenosine A1 receptor antagonism; however, it is unclear whether adenosine receptors are altered after prolonged postinjury periods and whether theophylline can further enhance restored respiratory function that occurs spontaneously. To assess putative effects of systemic theophylline administration on further enhancing spontaneous respiratory muscle recovery 4 months after C2 hemisection in rats and to determine whether adenosine A1 receptor mRNA expression is altered in these animals. Electrophysiologic assessment of respiratory activity in the phrenic nerves was conducted in C2 hemisected rats 4 months after hemisection under standardized conditions. Immediately thereafter, rats were killed and the cervical spinal cords were prepared for adenosine A1 receptor mRNA expression by in situ hybridization. Spontaneous recovery of respiratory activity in the ipsilateral phrenic nerve was detected in a majority (15/20) of C2 hemisected animals and amounted to 44.06% +/- 2.38% when expressed as a percentage of activity in the homolateral phrenic nerve in noninjured animals. At the optimal dosage used in the acute studies, theophylline (15 mg/kg) did not enhance, but rather unexpectedly blocked, recovered respiratory activity in 4 out of 5 animals tested. At dosages of 5 mg/kg and 2.5 mg/kg, the drug blocked recovered respiratory activity in 3 out of 4 and 3 out of 5 animals tested, respectively. Quantitative analysis of adenosine A1 receptor mRNA expression did not reveal a significant difference between experimental animals

  15. [3H]CGS 21680, a selective A2 adenosine receptor agonist directly labels A2 receptors in rat brain

    International Nuclear Information System (INIS)

    Jarvis, M.F.; Schulz, R.; Hutchison, A.J.; Do, U.H.; Sills, M.A.; Williams, M.

    1989-01-01

    In the present study, the binding of a highly A2-selective agonist radioligand, [3H]CGS 21680 (2-[p-(2-carboxyethyl)-phenethylamino]-5'-N-ethylcarboxamido adenosine) is described. [3H]CGS 21680 specific binding to rat striatal membranes was saturable, reversible and dependent upon protein concentration. Saturation studies revealed that [3H]CGS 21680 bound with high affinity (Kd = 15.5 nM) and limited capacity (apparent Bmax = 375 fmol/mg of protein) to a single class of recognition sites. Estimates of ligand affinity (16 nM) determined from association and dissociation kinetic experiments were in close agreement with the results from the saturation studies. [3H]CGS 21680 binding was greatest in striatal membranes with negligible specific binding obtained in rat cortical membranes. Adenosine agonists ligands competed for the binding of 5 nM [3H]CGS 21680 to striatal membranes with the following order of activity; CGS 21680 = 5'-N-ethylcarboxamidoadenosine greater than 2-phenylaminoadenosine (CV-1808) = 5'-N-methylcarboxamidoadenosine = 2-chloroadenosine greater than R-phenylisopropyladenosine greater than N6-cyclohexyladenosine greater than N6cyclopentyltheophylline greater than S-phenylisopropyladenosine. The nonxanthine adenosine antagonist, CGS 15943A, was the most active compound in inhibiting the binding of [3H]CGS 21680. Other adenosine antagonists inhibited binding in the following order; xanthine amine congener = 1,3-dipropyl-8-(2-amino-4-chloro)phenylxanthine greater than 1,3-dipropyl-8-cyclopentylxanthine greater than 1,3-diethyl-8-phenylxanthine greater than 8-phenyltheophylline greater than 8-cyclopentyltheophylline = xanthine carboxylic acid congener greater than 8-parasulfophenyltheophylline greater than theophylline greater than caffeine

  16. Frog secretions and hunting magic in the upper Amazon: identification of a peptide that interacts with an adenosine receptor.

    Science.gov (United States)

    Daly, J W; Caceres, J; Moni, R W; Gusovsky, F; Moos, M; Seamon, K B; Milton, K; Myers, C W

    1992-11-15

    A frog used for "hunting magic" by several groups of Panoan-speaking Indians in the borderline between Brazil and Peru is identified as Phyllomedusa bicolor. This frog's skin secretion, which the Indians introduce into the body through fresh burns, is rich in peptides. These include vasoactive peptides, opioid peptides, and a peptide that we have named adenoregulin, with the sequence GLWSKIKEVGKEAAKAAAKAAGKAALGAVSEAV as determined from mass spectrometry and Edman degradation. The natural peptide may contain a D amino acid residue, since it is not identical in chromatographic properties to the synthetic peptide. Adenoregulin enhances binding of agonists to A1 adenosine receptors; it is accompanied in the skin secretion by peptides that inhibit binding. The vasoactive peptide sauvagine, the opioid peptides, and adenoregulin and related peptides affect behavior in mice and presumably contribute to the behavioral sequelae observed in humans.

  17. The adenosine A2A receptor agonist CGS 21680 exhibits antipsychotic-like activity in Cebus apella monkeys

    DEFF Research Database (Denmark)

    Andersen, M B; Fuxe, K; Werge, T

    2002-01-01

    and lack of EPS in rodents could also be observed in non-human primates. We investigated the effects of CGS 21680 on behaviours induced by D-amphetamine and (-)-apomorphine in EPS-sensitized Cebus apella monkeys. CGS 21680 was administered s.c. in doses of 0.01, 0.025 and 0.05 mg/kg, alone...... and in combination with D-amphetamine and (-)-apomorphine. The monkeys were videotaped after drug administration and the tapes were rated for EPS and psychosis-like symptoms. CGS 21680 decreased apomorphine-induced behavioural unrest, arousal (0.01-0.05 mg/kg) and stereotypies (0.05 mg/kg) while amphetamine...... showed a functional anti-dopaminergic effect in Cebus apella monkeys without production of EPS. This further substantiates that adenosine A2A receptor agonists may have potential as antipsychotics with atypical profiles....

  18. QSAR of adenosine receptor antagonists. Part 3: Exploring physicochemical requirements for selective binding of 1,2,4-triazolo[5,1-i]purine derivatives with human adenosine A3 receptor subtype.

    Science.gov (United States)

    Roy, Kunal; Leonard, J Thomas; Sengupta, Chandana

    2004-07-16

    Considering potential of selective adenosine A3 receptor antagonists in the development of prospective therapeutic agents, an attempt has been made to explore selectivity requirements of 1,2,4-triazolo[5,1-i]purine derivatives for binding with cloned human adenosine A3 receptor subtype. In this study, partition coefficient (logP) values of the molecules (calculated by Crippen's fragmentation method) and Wang-Ford charges of the common atoms of the triazolopurine nucleus (calculated from molecular electrostatic potential surface of energy minimized geometry using AM1 technique) were used as independent variables along with suitable dummy parameters. The best equation describing A3 binding affinity [n=29, Q2=0.796, Ra2=0.853, R2=0.874, R=0.935, s=0.342, F=41.5 (df 4,24), SDEP=0.396] showed parabolic relation with logP (optimum value being 4.134). Further, it was found that an aromatic substituent conjugated with the triazole nucleus should be present at R2 position for A3 binding affinity. Again, high negative charges on N2 and N4 are conducive to the binding affinity. While exploring selectivity requirements of the compounds for binding with A3 receptor over that with A2A receptor, the selectivity relation [n=23, Q2=0.909, Ra2=0.918, R2=0.933, R=0.966, s=0.401, F=62.4 (df 4,18), SDEP=0.412] showed that an aromatic R2 substituent conjugated with the triazole nucleus contributes significantly to the selectivity. Again, presence of a 4-substituted-phenyl ring (except 4-OH-phenyl and 4-CH3-phenyl) at R2 position also increases selectivity. Further, charge difference between N2 and N11 (negative charge on the former should be higher and that on the latter should be less) contributes significantly to the selectivity. In addition, negative charge on N7 is conducive while presence of substituents like propyl, butyl, pentyl or phenyl at R1 position is detrimental for the A3 selectivity.

  19. Essential Control of the Function of the Striatopallidal Neuron by Pre-coupled Complexes of Adenosine A2A-Dopamine D2 Receptor Heterotetramers and Adenylyl Cyclase

    Directory of Open Access Journals (Sweden)

    Sergi Ferré

    2018-04-01

    Full Text Available The central adenosine system and adenosine receptors play a fundamental role in the modulation of dopaminergic neurotransmission. This is mostly achieved by the strategic co-localization of different adenosine and dopamine receptor subtypes in the two populations of striatal efferent neurons, striatonigral and striatopallidal, that give rise to the direct and indirect striatal efferent pathways, respectively. With optogenetic techniques it has been possible to dissect a differential role of the direct and indirect pathways in mediating “Go” responses upon exposure to reward-related stimuli and “NoGo” responses upon exposure to non-rewarded or aversive-related stimuli, respectively, which depends on their different connecting output structures and their differential expression of dopamine and adenosine receptor subtypes. The striatopallidal neuron selectively expresses dopamine D2 receptors (D2R and adenosine A2A receptors (A2AR, and numerous experiments using multiple genetic and pharmacological in vitro, in situ and in vivo approaches, demonstrate they can form A2AR-D2R heteromers. It was initially assumed that different pharmacological interactions between dopamine and adenosine receptor ligands indicated the existence of different subpopulations of A2AR and D2R in the striatopallidal neuron. However, as elaborated in the present essay, most evidence now indicates that all interactions can be explained with a predominant population of striatal A2AR-D2R heteromers forming complexes with adenylyl cyclase subtype 5 (AC5. The A2AR-D2R heteromer has a tetrameric structure, with two homodimers, which allows not only multiple allosteric interactions between different orthosteric ligands, agonists, and antagonists, but also the canonical Gs-Gi antagonistic interaction at the level of AC5. We present a model of the function of the A2AR-D2R heterotetramer-AC5 complex, which acts as an integrative device of adenosine and dopamine signals that

  20. Exploring an interaction of adenosine A2A receptor variability with coffee and tea intake in Parkinson's disease.

    Science.gov (United States)

    Tan, E K; Lu, Z Y; Fook-Chong, S M C; Tan, E; Shen, H; Chua, E; Yih, Y; Teo, Y Y; Zhao, Y

    2006-09-05

    Caffeine is an adenosine receptor A1 and A2A receptor antagonist and a putative functional genetic variant of the A2A receptor (2592C > Tins) mediates caffeine-induced anxiety. Here we investigated the potential interaction of this A2A genetic variant with the quantity of coffee and tea intake and their relationship with the risk of PD. A total of 441 subjects consisting of 222 PD and 219 race, gender and age matched controls were included. A multivariate analysis of the variables including the 2592C > Tins A2A genotypes, age of onset, gender, and the quantity of tea and coffee intake, interaction of the A2A genotypes with coffee intake, interaction of A2A genotypes with tea intake demonstrated the quantity of coffee intake to be significantly associated with PD (P coffee and tea intake in modulating the risk of PD. The dose dependent protective effect of coffee intake in PD was independent of the 2592C > Tins A2A genotype suggesting that the pharmacogenetic action of caffeine in PD may be mediated differently from other caffeine-induced neurologic syndromes.

  1. Chronic and acute adenosine A2A receptor blockade prevents long-term episodic memory disruption caused by acute cannabinoid CB1 receptor activation.

    Science.gov (United States)

    Mouro, Francisco M; Batalha, Vânia L; Ferreira, Diana G; Coelho, Joana E; Baqi, Younis; Müller, Christa E; Lopes, Luísa V; Ribeiro, Joaquim A; Sebastião, Ana M

    2017-05-01

    Cannabinoid-mediated memory impairment is a concern in cannabinoid-based therapies. Caffeine exacerbates cannabinoid CB 1 receptor (CB 1 R)-induced memory deficits through an adenosine A 1 receptor-mediated mechanism. We now evaluated how chronic or acute blockade of adenosine A 2A receptors (A 2A Rs) affects long-term episodic memory deficits induced by a single injection of a selective CB 1 R agonist. Long-term episodic memory was assessed by the novel object recognition (NOR) test. Mice received an intraperitoneal (i.p.) injection of the CB 1 /CB 2 receptor agonist WIN 55,212-2 (1 mg/kg) immediately after the NOR training, being tested for novelty recognition 24 h later. Anxiety levels were assessed by the Elevated Plus Maze test, immediately after the NOR. Mice were also tested for exploratory behaviour at the Open Field. For chronic A 2A R blockade, KW-6002 (istradefylline) (3 mg/kg/day) was administered orally for 30 days; acute blockade of A 2A Rs was assessed by i.p. injection of SCH 58261 (1 mg/kg) administered either together with WIN 55,212-2 or only 30 min before the NOR test phase. The involvement of CB 1 Rs was assessed by using the CB 1 R antagonist, AM251 (3 mg/kg, i.p.). WIN 55,212-2 caused a disruption in NOR, an action absent in mice also receiving AM251, KW-6002 or SCH 58261 during the encoding/consolidation phase; SCH 58251 was ineffective if present during retrieval only. No effects were detected in the Elevated Plus maze or Open Field Test. The finding that CB 1 R-mediated memory disruption is prevented by antagonism of adenosine A 2A Rs, highlights a possibility to prevent cognitive side effects when therapeutic application of CB 1 R drugs is desired. Copyright © 2017 Elsevier Ltd. All rights reserved.

  2. Activation of Adenosine Receptor A2A Increases HSC Proliferation and Inhibits Death and Senescence by Down-regulation of p53 and Rb

    Directory of Open Access Journals (Sweden)

    Md. Kaimul eAhsan

    2014-04-01

    Full Text Available Background & Aims: During fibrosis hepatic stellate cells (HSC undergo activation, proliferation and senescence but the regulation of these important processes is poorly understood. The adenosine A2A receptor (A2A is known to be present on HSC, and its activation results in liver fibrosis. In this study, we tested if A2A has a role in the regulation of HSC proliferation, apoptosis, senescence, and the relevant molecular mechanism.Methods: The ability of adenosine to regulate p53 and Rb protein levels, proliferation, apoptosis and senescence was tested in the human HSC cell line LX-2 and rat primary HSC.Results: Adenosine receptor activation down-regulates p53 and Rb protein levels, increases BrdU incorporation and increases cell survival in LX-2 cells and in primary rat HSC. These effects of NECA were reproduced by an adenosine A2A receptor specific agonist (CGS21680 and blocked by a specific antagonist (ZM241385. By day twenty-one of culture primary rat HSC entered senescence and expressed -gal which was significantly inhibited by NECA. Furthermore, NECA induced down regulation of p53 and Rb and Rac1, and decreased phosphorylation of p44-42 MAP Kinase in LX-2 cells and primary rat HSC. These effects were reproduced by the cAMP analog 8-Bromo-cAMP, and the adenylyl cyclase activator forskolin, and were blocked by PKA inhibitors.Conclusions: These results demonstrate that A2A receptor regulates a number of HSC fate decisions and induces greater HSC proliferation, reduces apoptosis and senescence by decreasing p53 and Rb through cAMP-PKA/Rac1/p38 MAPK pathway. This provides a mechanism for adenosine induced HSC regulation and liver fibrosis.

  3. Autoradiographic localization of adenosine A1 receptors in rat brain using [3H]XCC, a functionalized congener of 1,3-dipropylxanthine

    International Nuclear Information System (INIS)

    Jarvis, M.J.; Williams, M.; Jacobson, K.A.

    1987-01-01

    Quantitative autoradiography was used to visualize the anatomical distribution of adenosine receptors labeled by the carboxylic acid congener of 1,3-dipropylxanthine, [ 3 Hi](8-(p-carbonxymethyloxy) phenyl-1,3 dipropylxanthine)([ 3 H]XCC) in rat brain. [ 3 H]XCC was observed to specifically bind to rat brain sagittal sections in a heterogenous pattern. Saturation experiments revealed that [ 3 H]XCC binds with nanomolar affinity to 20μm frozen tissue sections with the highest binding densities occurring in the hippocampus and cerebellum. Both the binding characteristics and regional receptor distribution obtained with [ 3 H]XCC demonstrate the potential usefulness of this new ligand in the study of adenosine A 1 receptors. 13 refs. (Author)

  4. Calcium modulates calmodulin/α-actinin 1 interaction with and agonist-dependent internalization of the adenosine A2A receptor.

    Science.gov (United States)

    Piirainen, Henni; Taura, Jaume; Kursula, Petri; Ciruela, Francisco; Jaakola, Veli-Pekka

    2017-04-01

    Adenosine receptors are G protein-coupled receptors that sense extracellular adenosine to transmit intracellular signals. One of the four adenosine receptor subtypes, the adenosine A 2A receptor (A 2A R), has an exceptionally long intracellular C terminus (A 2A R-ct) that mediates interactions with a large array of proteins, including calmodulin and α-actinin. Here, we aimed to ascertain the α-actinin 1/calmodulin interplay whilst binding to A 2A R and the role of Ca 2+ in this process. First, we studied the A 2A R-α-actinin 1 interaction by means of native polyacrylamide gel electrophoresis, isothermal titration calorimetry, and surface plasmon resonance, using purified recombinant proteins. α-Actinin 1 binds the A 2A R-ct through its distal calmodulin-like domain in a Ca 2+ -independent manner with a dissociation constant of 5-12μM, thus showing an ~100 times lower affinity compared to the A 2A R-calmodulin/Ca 2+ complex. Importantly, calmodulin displaced α-actinin 1 from the A 2A R-ct in a Ca 2+ -dependent fashion, disrupting the A 2A R-α-actinin 1 complex. Finally, we assessed the impact of Ca 2+ on A 2A R internalization in living cells, a function operated by the A 2A R-α-actinin 1 complex. Interestingly, while Ca 2+ influx did not affect constitutive A 2A R endocytosis, it abolished agonist-dependent internalization. In addition, we demonstrated that the A 2A R/α-actinin interaction plays a pivotal role in receptor internalization and function. Overall, our results suggest that the interplay of A 2A R with calmodulin and α-actinin 1 is fine-tuned by Ca 2+ , a fact that might power agonist-mediated receptor internalization and function. Copyright © 2017 Elsevier B.V. All rights reserved.

  5. The neuronal Ca(2+) -binding protein 2 (NECAB2) interacts with the adenosine A(2A) receptor and modulates the cell surface expression and function of the receptor.

    Science.gov (United States)

    Canela, Laia; Luján, Rafael; Lluís, Carme; Burgueño, Javier; Mallol, Josefa; Canela, Enric I; Franco, Rafael; Ciruela, Francisco

    2007-09-01

    Heptaspanning membrane also known as G protein-coupled receptors (GPCR) do interact with a variety of intracellular proteins whose function is regulate receptor traffic and/or signaling. Using a yeast two-hybrid screen, NECAB2, a neuronal calcium binding protein, was identified as a binding partner for the adenosine A(2A) receptor (A(2A)R) interacting with its C-terminal domain. Co-localization, co-immunoprecipitation and pull-down experiments showed a close and specific interaction between A(2A)R and NECAB2 in both transfected HEK-293 cells and also in rat striatum. Immunoelectron microscopy detection of NECAB2 and A(2A)R in the rat striatopallidal structures indicated that both proteins are co-distributed in the same glutamatergic nerve terminals. The interaction of NECAB2 with A(2A)R modulated the cell surface expression, the ligand-dependent internalization and the receptor-mediated activation of the MAPK pathway. Overall, these results show that A(2A)R interacts with NECAB2 in striatal neurones co-expressing the two proteins and that the interaction is relevant for A(2A)R function.

  6. Antidepressant activity of the adenosine A2A receptor antagonist, istradefylline (KW-6002) on learned helplessness in rats.

    Science.gov (United States)

    Yamada, Koji; Kobayashi, Minoru; Shiozaki, Shizuo; Ohta, Teruko; Mori, Akihisa; Jenner, Peter; Kanda, Tomoyuki

    2014-07-01

    Istradefylline, an adenosine A2A receptor antagonist, improves motor function in animal models of Parkinson's disease (PD) and in patients with PD. In addition, some A2A antagonists exert antidepressant-like activity in rodent models of depression, such as the forced swim and the tail suspension tests. We have investigated the effect of istradefylline on depression-like behaviors using the rat learned helplessness (LH) model. Acute, as well as chronic, oral administration of istradefylline significantly improved the inescapable shock (IES)-induced escape deficit with a degree of efficacy comparable to chronic treatment with the tricyclic antidepressant desipramine and the selective serotonin (5-HT) reuptake inhibitor, fluoxetine. Both the A1/A2A receptor nonspecific antagonist theophylline and the moderately selective antagonist CGS15943, but not the A1 selective antagonist DPCPX, ameliorated the IES-induced escape deficit. The enhancement of escape response by istradefylline was reversed by a local injection of the A2A specific agonist CGS21680 either into the nucleus accumbens, the caudate-putamen, or the paraventricular nucleus of the hypothalamus, but not by the A1 specific agonist R-PIA into the nucleus accumbens. Moreover, neither the 5-HT2A/2C receptor antagonist methysergide or the adrenergic α 2 antagonist yohimbine, nor the β-adrenergic antagonist propranolol, affected the improvement of escape response induced by istradefylline. Istradefylline exerts antidepressant-like effects via modulation of A2A receptor activity which is independent of monoaminergic transmission in the brain. Istradefylline may represent a novel treatment option for depression in PD as well as for the motor symptoms.

  7. Recombinant mouse PAP has pH-dependent ectonucleotidase activity and acts through A(1-adenosine receptors to mediate antinociception.

    Directory of Open Access Journals (Sweden)

    Nathaniel A Sowa

    Full Text Available Prostatic acid phosphatase (PAP is expressed in nociceptive neurons and functions as an ectonucleotidase. When injected intraspinally, the secretory isoforms of human and bovine PAP protein have potent and long-lasting antinociceptive effects that are dependent on A(1-adenosine receptor (A(1R activation. In this study, we purified the secretory isoform of mouse (mPAP using the baculovirus expression system to determine if recombinant mPAP also had antinociceptive properties. We found that mPAP dephosphorylated AMP, and to a much lesser extent, ADP at neutral pH (pH 7.0. In contrast, mPAP dephosphorylated all purine nucleotides (AMP, ADP, ATP at an acidic pH (pH 5.6. The transmembrane isoform of mPAP had similar pH-dependent ectonucleotidase activity. A single intraspinal injection of mPAP protein had long-lasting (three day antinociceptive properties, including antihyperalgesic and antiallodynic effects in the Complete Freund's Adjuvant (CFA inflammatory pain model. These antinociceptive effects were transiently blocked by the A(1R antagonist 8-cyclopentyl-1, 3-dipropylxanthine (CPX, suggesting mPAP dephosphorylates nucleotides to adenosine to mediate antinociception just like human and bovine PAP. Our studies indicate that PAP has species-conserved antinociceptive effects and has pH-dependent ectonucleotidase activity. The ability to metabolize nucleotides in a pH-dependent manner could be relevant to conditions like inflammation where tissue acidosis and nucleotide release occur. Lastly, our studies demonstrate that recombinant PAP protein can be used to treat chronic pain in animal models.

  8. Inhibition of A2A Adenosine Receptor Signaling in Cancer Cells Proliferation by the Novel Antagonist TP455

    Directory of Open Access Journals (Sweden)

    Stefania Gessi

    2017-12-01

    Full Text Available Several evidences indicate that the ubiquitous nucleoside adenosine, acting through A1, A2A, A2B, and A3 receptor (AR subtypes, plays crucial roles in tumor development. Adenosine has contrasting effects on cell proliferation depending on the engagement of different receptor subtypes in various tumors. The involvement of A2AARs in human A375 melanoma, as well as in human A549 lung and rat MRMT1 breast carcinoma proliferation has been evaluated in view of the availability of a novel A2AAR antagonist, with high affinity and selectivity, named as 2-(2-furanyl-N5-(2-methoxybenzyl[1,3]thiazolo[5,4-d]pyrimidine-5,7-diammine (TP455. Specifically, the signaling pathways triggered in the cancer cells of different origin and the antagonist effect of TP455 were investigated. The A2AAR protein expression was evaluated through receptor binding assays. Furthermore, the effect of A2AAR activation on cell proliferation at 24, 48 and 72 hours was studied. The selective A2AAR agonist 2-p-(2-carboxyethylphenethylamino-5′-N-ethylcarboxamidoadenosine hydrochloride (CGS21680, concentration-dependently induced cell proliferation in A375, A549, and MRMT1 cancer cells and the effect was potently antagonized by the A2AAR antagonist TP455, as well as by the reference A2AAR blocker 4-(2-[7-amino-2-(2-furyl[1,2,4]triazolo[2,3-a][1,3,5]triazin-5-ylamino]ethylphenol (ZM241385. As for the signaling pathway recruited in this response we demonstrated that, by using the specific inhibitors of signal transduction pathways, the effect of A2AAR stimulation was induced through phospholipase C (PLC and protein kinase C-delta (PKC-δ. In addition, we evaluated, through the AlphaScreen SureFire phospho(p protein assay, the kinases enrolled by A2AAR to stimulate cell proliferation and we found the involvement of protein kinase B (AKT, extracellular regulated kinases (ERK1/2, and c-Jun N-terminal kinases (JNKs. Indeed, we demonstrated that the CGS21680 stimulatory effect on kinases was

  9. Guanosine may increase absence epileptic activity by means of A2A adenosine receptors in Wistar Albino Glaxo Rijswijk rats.

    Science.gov (United States)

    Lakatos, Renáta Krisztina; Dobolyi, Árpád; Todorov, Mihail Ivilinov; Kékesi, Katalin A; Juhász, Gábor; Aleksza, Magdolna; Kovács, Zsolt

    2016-06-01

    The non-adenosine nucleoside guanosine (Guo) was demonstrated to decrease quinolinic acid(QA)-induced seizures, spontaneously emerged absence epileptic seizures and lipopolysaccharide(LPS)-evoked induction of absence epileptic seizures suggesting its antiepileptic potential. It was also described previously that intraperitoneal (i.p.) injection of 20 and 50mg/kg Guo decreased the number of spike-wave discharges (SWDs) in a well investigated model of human absence epilepsy, the Wistar Albino Glaxo Rijswijk (WAG/Rij) rats during 4th (20mg/kg Guo) and 3rd as well as 4th (50mg/kg Guo) measuring hours. Guanosine can potentially decrease SWD number by means of its putative receptors but absence epileptic activity changing effects of Guo by means of increased extracellular adenosine (Ado) cannot be excluded. An increase in the dose of i.p. injected Guo is limited by its low solubility in saline, therefore, we addressed in the present study whether higher doses of Guo, diluted in sodium hydroxide (NaOH) solution, have more potent antiepileptic effect in WAG/Rij rats. We confirmed that i.p. 50mg/kg Guo decreased but, surprisingly, i.p. 100mg/kg Guo enhanced the number of SWDs in WAG/Rij rats. Combined i.p. injection of a non-selective Ado receptor antagonist theophylline (5mg/kg) or a selective Ado A2A receptor (A2AR) antagonist SCH 58261 (7-(2-phenylethyl)-5-amino-2-(2-furyl)-pyrazolo-[4,3-e]-1,2,4-triazolo[1,5-c]pyrimidine) (1mg/kg) and a cyclooxygenase 1 and 2/COX-1 and COX-2 inhibitor indomethacin (10mg/kg) with 100mg/kg Guo decreased the SWD number compared to i.p. 100mg/kg Guo alone. The results suggest that i.p. 100mg/kg Guo can increase SWD number by means of the adenosinergic system. Copyright © 2016 Elsevier Inc. All rights reserved.

  10. Ethanol and Caffeine Effects on Social Interaction and Recognition in Mice: Involvement of Adenosine A2A and A1 Receptors.

    Science.gov (United States)

    López-Cruz, Laura; San-Miguel, Noemí; Bayarri, Pilar; Baqi, Younis; Müller, Christa E; Salamone, John D; Correa, Mercé

    2016-01-01

    Ethanol and caffeine are frequently consumed in combination and have opposite effects on the adenosine system: ethanol metabolism leads to an increase in adenosine levels, while caffeine is a non-selective adenosine A 1 /A 2A receptor antagonist. These receptors are highly expressed in striatum and olfactory tubercle, brain areas involved in exploration and social interaction in rodents. Ethanol modulates social interaction processes, but the role of adenosine in social behavior is still poorly understood. The present work was undertaken to study the impact of ethanol, caffeine and their combination on social behavior, and to explore the involvement of A 1 and A 2A receptors on those actions. Male CD1 mice were evaluated in a social interaction three-chamber paradigm, for preference of conspecific vs. object, and also for long-term recognition memory of familiar vs. novel conspecific. Ethanol showed a biphasic effect, with low doses (0.25 g/kg) increasing social contact and higher doses (1.0-1.5 g/kg) reducing social interaction. However, no dose changed social preference; mice always spent more time sniffing the conspecific than the object, independently of the ethanol dose. Ethanol, even at doses that did not change social exploration, produced amnestic effects on social recognition the following day. Caffeine reduced social contact (15.0-60.0 mg/kg), and even blocked social preference at higher doses (30.0-60.0 mg/kg). The A 1 antagonist Cyclopentyltheophylline (CPT; 3-9 mg/kg) did not modify social contact or preference on its own, and the A 2A antagonist MSX-3 (1.5-6 mg/kg) increased social interaction at all doses. Ethanol at intermediate doses (0.5-1.0 g/kg) was able to reverse the reduction in social exploration induced by caffeine (15.0-30.0 mg/kg). Although there was no interaction between ethanol and CPT or MSX-3 on social exploration in the first day, MSX-3 blocked the amnestic effects of ethanol observed on the following day. Thus, ethanol impairs the

  11. Adenosine A2A receptor-dependent proliferation of pulmonary endothelial cells is mediated through calcium mobilization, PI3-kinase and ERK1/2 pathways

    International Nuclear Information System (INIS)

    Ahmad, Aftab; Schaack, Jerome B.; White, Carl W.; Ahmad, Shama

    2013-01-01

    Highlights: •A 2A receptor-induced pulmonary endothelial growth is mediated by PI3K and ERK1/2. •Cytosolic calcium mobilization is also critical for pulmonary endothelial growth. •Effectors of A 2A receptor, like tyrosine kinases and cAMP increase PI3K/Akt signaling. •Activation of A 2A receptor can contribute to vascular remodeling. -- Abstract: Hypoxia and HIF-2α-dependent A 2A receptor expression and activation increase proliferation of human lung microvascular endothelial cells (HLMVECs). This study was undertaken to investigate the signaling mechanisms that mediate the proliferative effects of A 2A receptor. A 2A receptor-mediated proliferation of HLMVECs was inhibited by intracellular calcium chelation, and by specific inhibitors of ERK1/2 and PI3-kinase (PI3K). The adenosine A 2A receptor agonist CGS21680 caused intracellular calcium mobilization in controls and, to a greater extent, in A 2A receptor-overexpressing HLMVECs. Adenoviral-mediated A 2A receptor overexpression as well as receptor activation by CGS21680 caused increased PI3K activity and Akt phosphorylation. Cells overexpressing A 2A receptor also manifested enhanced ERK1/2 phosphorylation upon CGS21680 treatment. A 2A receptor activation also caused enhanced cAMP production. Likewise, treatment with 8Br-cAMP increased PI3K activity. Hence A 2A receptor-mediated cAMP production and PI3K and Akt phosphorylation are potential mediators of the A 2A -mediated proliferative response of HLMVECs. Cytosolic calcium mobilization and ERK1/2 phosphorylation are other critical effectors of HLMVEC proliferation and growth. These studies underscore the importance of adenosine A 2A receptor in activation of survival and proliferative pathways in pulmonary endothelial cells that are mediated through PI3K/Akt and ERK1/2 pathways

  12. Selecting an optimal number of binding site waters to improve virtual screening enrichments against the adenosine A2A receptor.

    Science.gov (United States)

    Lenselink, Eelke B; Beuming, Thijs; Sherman, Woody; van Vlijmen, Herman W T; IJzerman, Adriaan P

    2014-06-23

    A major challenge in structure-based virtual screening (VS) involves the treatment of explicit water molecules during docking in order to improve the enrichment of active compounds over decoys. Here we have investigated this in the context of the adenosine A2A receptor, where water molecules have previously been shown to be important for achieving high enrichment rates with docking, and where the positions of some binding site waters are known from a high-resolution crystal structure. The effect of these waters (both their presence and orientations) on VS enrichment was assessed using a carefully curated set of 299 high affinity A2A antagonists and 17,337 decoys. We show that including certain crystal waters greatly improves VS enrichment and that optimization of water hydrogen positions is needed in order to achieve the best results. We also show that waters derived from a molecular dynamics simulation - without any knowledge of crystallographic waters - can improve enrichments to a similar degree as the crystallographic waters, which makes this strategy applicable to structures without experimental knowledge of water positions. Finally, we used decision trees to select an ensemble of structures with different water molecule positions and orientations that outperforms any single structure with water molecules. The approach presented here is validated against independent test sets of A2A receptor antagonists and decoys from the literature. In general, this water optimization strategy could be applied to any target with waters-mediated protein-ligand interactions.

  13. Cognitive impairments associated with alterations in synaptic proteins induced by the genetic loss of adenosine A2A receptors in mice.

    Science.gov (United States)

    Moscoso-Castro, Maria; López-Cano, Marc; Gracia-Rubio, Irene; Ciruela, Francisco; Valverde, Olga

    2017-11-01

    The study of psychiatric disorders usually focuses on emotional symptoms assessment. However, cognitive deficiencies frequently constitute the core symptoms, are often poorly controlled and handicap individual's quality of life. Adenosine receptors, through the control of both dopamine and glutamate systems, have been implicated in the pathophysiology of several psychiatric disorders such as schizophrenia and attention deficit/hyperactivity disorder. Indeed, clinical data indicate that poorly responsive schizophrenia patients treated with adenosine adjuvants show improved treatment outcomes. The A 2A adenosine receptor subtype (A 2A R) is highly expressed in brain areas controlling cognition and motivational responses including the striatum, hippocampus and cerebral cortex. Accordingly, we study the role of A 2A R in the regulation of cognitive processes based on a complete cognitive behavioural analysis coupled with the assessment of neurogenesis and sub-synaptic protein expression in adult and middle-aged A 2A R constitutional knockout mice and wild-type littermates. Our results show overall cognitive impairments in A 2A R knockout mice associated with a decrease in new-born hippocampal neuron proliferation and concomitant changes in synaptic protein expression, in both the prefrontal cortex and the hippocampus. These results suggest a deficient adenosine signalling in cognitive processes, thus providing new opportunities for the therapeutic management of cognitive deficits associated with psychiatric disorders. Copyright © 2017 Elsevier Ltd. All rights reserved.

  14. Modulation of gene expression of adenosine and metabotropic glutamate receptors in rat's neuronal cells exposed to L-glutamate and [60]fullerene.

    Science.gov (United States)

    Giust, Davide; Da Ros, Tatiana; Martín, Mairena; Albasanz, José Luis

    2014-08-01

    L-Glutamate (L-Glu) has been often associated not only to fundamental physiological roles, as learning and memory, but also to neuronal cell death and the genesis and development of important neurodegenerative diseases. Herein we studied the variation in the adenosine and metabotropic glutamate receptors expression induced by L-Glu treatment in rat's cortical neurons. The possibility to have structural alteration of the cells induced by L-Glu (100 nM, 1 and 10 microM) has been addressed, studying the modulation of microtubule associated protein-2 (MAP-2) and neurofilament heavy polypeptide (NEFH), natively associated proteins to the dendritic shape maintenance. Results showed that the proposed treatments were not destabilizing the cells, so the L-Glu concentrations were acceptable to investigate fluctuation in receptors expression, which were studied by RT-PCR. Interestingly, C60 fullerene derivative t3ss elicited a protective effect against glutamate toxicity, as demonstrated by MTT assay. In addition, t3ss compound exerted a different effect on the adenosine and metabotropic glutamate receptors analyzed. Interestingly, A(2A) and mGlu1 mRNAs were significantly decreased in conditions were t3ss neuroprotected cortical neurons from L-Glu toxicity. In summary, t3ss protects neurons from glutamate toxicity in a process that appears to be associated with the modulation of the gene expression of adenosine and metabotropic glutamate receptors.

  15. Effect of the adenosine A2A receptor antagonist MSX-3 on motivational disruptions of maternal behavior induced by dopamine antagonism in the early postpartum rat.

    Science.gov (United States)

    Pereira, Mariana; Farrar, Andrew M; Hockemeyer, Jörg; Müller, Christa E; Salamone, John D; Morrell, Joan I

    2011-01-01

    Mesolimbic dopamine (DA), particularly in the nucleus accumbens, importantly regulates activational aspects of maternal responsiveness. DA antagonism and accumbens DA depletions interfere with early postpartum maternal motivation by selectively affecting most forms of active maternal behaviors, while leaving nursing behavior relatively intact. Considerable evidence indicates that there is a functional interaction between DA D2 and adenosine A(2A) receptors in striatal areas, including the nucleus accumbens. This study was conducted to determine if adenosine A(2A) receptor antagonism could reverse the effects of DA receptor antagonism on early postpartum maternal behavior. The adenosine A(2A) receptor antagonist MSX-3 (0.25-2.0 mg/kg, IP) was investigated for its ability to reverse the effects of the DA D2 receptor antagonist haloperidol (0.1 mg/kg, IP) on the maternal behavior of early postpartum female rats. Haloperidol severely impaired the expression of active maternal components, including retrieval and grouping the pups at the nest site, pup licking, and nest building. Co-administration of MSX-3 (0.25-2.0 mg/kg, IP) with haloperidol produced a dose-related attenuation of the haloperidol-induced behavioral deficits in early postpartum females. Doses of MSX-3 that effectively reversed the effects of haloperidol (0.5, 1.0 mg/kg), when administered in the absence of haloperidol, did not affect maternal responding or locomotor activity. Adenosine and DA systems interact to regulate early postpartum maternal responsiveness. This research may potentially contribute to the development of strategies for treatments of psychiatric disorders during the postpartum period, with particular emphasis in maintaining or restoring the mother-infant relationship.

  16. Muscarinic, adenosine and tropomyosin-related kinase B receptors modulate the neuromuscular developmental synapse elimination process

    OpenAIRE

    Nadal Magriñà, Laura

    2017-01-01

    El desarrollo del sistema nervioso periférico implica una inicial exuberante producción de neuronas y, una posterior reducción dependiente de actividad del número de sinapsis en las uniones neuromusculares (NMJ). Este proceso se denomina eliminación sináptica. Al final de la segunda semana postnatal, cada fibra muscular esta inervadas por una solo motoneurona. Los receptores muscarínicos de acetilcolina (mAChR), los receptores de adenosina (AR) y el receptor quinasa de tropomiosina B (TrkB) p...

  17. Cordycepin (3'-deoxyadenosine) inhibits the growth of B16-BL6 mouse melanoma cells through the stimulation of adenosine A3 receptor followed by glycogen synthase kinase-3beta activation and cyclin D1 suppression.

    Science.gov (United States)

    Yoshikawa, Noriko; Yamada, Shizuo; Takeuchi, Chihiro; Kagota, Satomi; Shinozuka, Kazumasa; Kunitomo, Masaru; Nakamura, Kazuki

    2008-06-01

    Cordyceps sinensis, a parasitic fungus on the larvae of Lepidoptera, has been used as a traditional Chinese medicine. We previously reported that the growth of B16-BL6 mouse melanoma (B16-BL6) cells was inhibited by cordycepin (3'-deoxyadenosine), an active ingredient of C. sinensis, and its effect was antagonized by MRS1191, a selective adenosine A3 receptor antagonist. In this study, the radioligand binding assay using [125I]-AB-MECA (a selective adenosine A3 receptor agonist) has shown that B16-BL6 cells express adenosine A3 receptors and that cordycepin binds to these receptors. We also confirmed the involvement of adenosine A3 receptors in the action of cordycepin using MRS1523 and MRS1220, specific adenosine A3 receptor antagonists. Next, indirubin, a glycogen synthase kinase-3beta (GSK-3beta) inhibitor, antagonized the growth suppression induced by cordycepin. Furthermore, the level of cyclin D1 protein in B16-BL6 cells was decreased by cordycepin using Western blot analysis. In conclusion, this study demonstrated that cordycepin inhibits the proliferation of B16-BL6 cells by stimulating adenosine A3 receptors followed by the Wnt signaling pathway, including GSK-3beta activation and cyclin D1 inhibition.

  18. Characterization of the adenosine receptor in cultured embryonic chick atrial myocytes: Coupling to modulation of contractility and adenylate cyclase activity and identification by direct radioligand binding

    International Nuclear Information System (INIS)

    Liang, B.T.

    1989-01-01

    Adenosine receptors in a spontaneously contracting atrial myocyte culture from 14-day chick embryos were characterized by radioligand binding studies and by examining the involvement of G-protein in coupling these receptors to a high-affinity state and to the adenylate cyclase and the myocyte contractility. Binding of the antagonist radioligand [3H]-8-cyclopentyl-1,3-diproylxanthine ([3H]CPX) was rapid, reversible and saturable and was to a homogeneous population of sites with a Kd value of 2.1 +/- 0.2 nM and an apparent maximum binding of 26.2 +/- 3 fmol/mg of protein (n = 10, +/- S.E.). Guanyl-5-yl-(beta, gamma-imido)diphosphate had no effect on either the Kd or the maximum binding and CPX reversed the N6-R-phenyl-2-propyladenosine-induced inhibition of adenylate cyclase activity and contractility, indicating that [3H] CPX is an antagonist radioligand. Competition curves for [3H] CPX binding by a series of reference adenosine agonists were consistent with labeling of an A1 adenosine receptor and were better fit by a two-site model than by a one-site model. ADP-ribosylation of the G-protein by the endogenous NAD+ in the presence of pertussis toxin shifted the competition curves from bi to monophasic with Ki values similar to those of the KL observed in the absence of prior pertussis intoxication. The adenosine agonists were capable of inhibiting both the adenylate cyclase activity and myocyte contractility in either the absence or the presence of isoproterenol. The A1 adenosine receptor-selective antagonist CPX reversed these agonist effects. The order of ability of the reference adenosine receptor agonists in causing these inhibitory effects was similar to the order of potency of the same agonists in inhibiting the specific [3H]CPX binding (N6-R-phenyl-2-propyladenosine greater than N6-S-phenyl-2-propyladenosine or N-ethyladenosine-5'-uronic acid)

  19. The amphiphilic peptide adenoregulin enhances agonist binding to A1-adenosine receptors and [35S]GTP gamma S to brain membranes.

    Science.gov (United States)

    Moni, R W; Romero, F S; Daly, J W

    1995-08-01

    1. Adenoregulin is an amphilic peptide isolated from skin mucus of the tree frog, Phyllomedusa bicolor. Synthetic adenoregulin enhanced the binding of agonists to several G-protein-coupled receptors in rat brain membranes. 2. The maximal enhancement of agonist binding, and in parentheses, the concentration of adenoregulin affording maximal enhancement were as follows: 60% (20 microM) for A1-adenosine receptors, 30% (100 microM) for A2a-adenosine receptors, 20% (2 microM) for alpha 2-adrenergic receptors, and 30% (10 microM) for 5HT1A receptors. High affinity agonist binding for A1-, alpha 2-, and 5HT1A-receptors was virtually abolished by GTP gamma S in the presence of adenoregulin, but was only partially abolished in its absence. Magnesium ions increased the binding of agonists to receptors and reduced the enhancement elicited by adenoregulin. 3. The effect of adenoregulin on binding of N6-cyclohexyladenosine ([3H]CHA) to A1-receptors was relatively slow and was irreversible. Adenoregulin increased the Bmax value for [3H]CHA binding sites, and the proportion of high affinity states, and slowed the rate of [3H]CHA dissociation. Binding of the A1-selective antagonist, [3H]DPCPX, was maximally enhanced by only 13% at 2 microM adenoregulin. Basal and A1-adenosine receptor-stimulated binding of [35S]GTP gamma S were maximally enhanced 45% and 23%, respectively, by 50 microM adenoregulin. In CHAPS-solubilized membranes from rat cortex, the binding of both [3H]CHA and [3H]DPCPX were enhanced by adenoregulin. Binding of [3H]CHA to membranes from DDT1 MF-2 cells was maximally enhanced 17% at 20 microM adenoregulin. In intact DDT1 MF-2 cells, 20 microM adenoregulin did not potentiate the inhibition of cyclic AMP accumulation mediated via the adenosine A1 receptor. 4. It is proposed that adenoregulin enhances agonist binding through a mechanism involving enhancement of guanyl nucleotide exchange at G-proteins, resulting in a conversion of receptors into a high affinity state

  20. Adenosine A2A receptor blockade Prevents Rotenone-Induced Motor Impairment in a Rat Model of Parkinsonism

    Directory of Open Access Journals (Sweden)

    Ahmed M Fathalla

    2016-02-01

    Full Text Available Pharmacological studies implicate the blockade of adenosine receptorsas an effective strategy for reducing Parkinson's disease (PD symptoms. The objective of this study is to elucidate the possible protective effects of ZM241385 and 8-cyclopentyl-1,3-dipropylxanthine, two selective A2Aand A1 receptor antagonists, on a rotenone rat model of PD. Rats were split into four groups: vehicle control (1 ml/kg/48 h, rotenone(1.5 mg/kg/48 h, s.c., ZM241385 (3.3 mg/kg/day, i.p and 8-cyclopentyl-1,3-dipropylxanthine (5 mg/kg/day, i.p. After that, animals were subjected to behavioral (stride length and grid walking and biochemical (measuring concentration of dopamine levels using high performance liquid chromatography. In the rotenone group, rats displayed a reduced motor activity and disturbed movement coordination in the behavioral tests and a decreased dopamine concentration as foundby high performance liquid chromatography. The effect of rotenone was partially preventedin the ZM241385 group, but not with 8-cyclopentyl-1,3-dipropylxanthine administration. The administration of ZM241385 has led toan improvement improved of motor function and movement coordination (a partial increase of stride length and partial decrease in the number of foot slips and an increase in dopamine concentration in the rotenone-injected rats. However, the 8-cyclopentyl-1,3-dipropylxanthine and rotenone groups were not significantly different. These results indicate that selective A2Areceptor blockade by ZM241385, but not A1receptor blockadeby 8-cyclopentyl-1,3-dipropylxanthine, may treat PD motor symptoms. This reinforces the potential use of A2A receptor antagonists as a treatment strategy for PD patients.. This may provide a more selective treatment strategy for PD patients.

  1. Adenosine A1 Receptor Protects Against Cisplatin Ototoxicity by Suppressing the NOX3/STAT1 Inflammatory Pathway in the Cochlea.

    Science.gov (United States)

    Kaur, Tejbeer; Borse, Vikrant; Sheth, Sandeep; Sheehan, Kelly; Ghosh, Sumana; Tupal, Srinivasan; Jajoo, Sarvesh; Mukherjea, Debashree; Rybak, Leonard P; Ramkumar, Vickram

    2016-04-06

    Cisplatin is a commonly used antineoplastic agent that produces ototoxicity that is mediated in part by increasing levels of reactive oxygen species (ROS) via the NOX3 NADPH oxidase pathway in the cochlea. Recent studies implicate ROS generation in mediating inflammatory and apoptotic processes and hearing loss by activating signal transducer and activator of transcription (STAT1). In this study, we show that the adenosine A1 receptor (A1AR) protects against cisplatin ototoxicity by suppressing an inflammatory response initiated by ROS generation via NOX3 NADPH oxidase, leading to inhibition of STAT1. Trans-tympanic administration of the A1AR agonist R-phenylisopropyladenosine (R-PIA) inhibited cisplatin-induced ototoxicity, as measured by auditory brainstem responses and scanning electron microscopy in male Wistar rats. This was associated with reduced NOX3 expression, STAT1 activation, tumor necrosis factor-α (TNF-α) levels, and apoptosis in the cochlea. In vitro studies in UB/OC-1 cells, an organ of Corti immortalized cell line, showed that R-PIA reduced cisplatin-induced phosphorylation of STAT1 Ser(727) (but not Tyr(701)) and STAT1 luciferase activity by suppressing the ERK1/2, p38, and JNK mitogen-activated protein kinase (MAPK) pathways.R-PIA also decreased the expression of STAT1 target genes, such as TNF-α, inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) and reduced cisplatin-mediated apoptosis. These data suggest that the A1AR provides otoprotection by suppressing NOX3 and inflammation in the cochlea and could serve as an ideal target for otoprotective drug therapy. Cisplatin is a widely used chemotherapeutic agent for the treatment of solid tumors. Its use results in significant and permanent hearing loss, for which no US Food and Drug Administration-approved treatment is currently available. In this study, we targeted the cochlear adenosine A1 receptor (A1AR) by trans-tympanic injections of the agonist R

  2. Adenosine A1 Receptor Protects Against Cisplatin Ototoxicity by Suppressing the NOX3/STAT1 Inflammatory Pathway in the Cochlea

    Science.gov (United States)

    Kaur, Tejbeer; Borse, Vikrant; Sheth, Sandeep; Sheehan, Kelly; Ghosh, Sumana; Tupal, Srinivasan; Jajoo, Sarvesh; Mukherjea, Debashree; Rybak, Leonard P.

    2016-01-01

    Cisplatin is a commonly used antineoplastic agent that produces ototoxicity that is mediated in part by increasing levels of reactive oxygen species (ROS) via the NOX3 NADPH oxidase pathway in the cochlea. Recent studies implicate ROS generation in mediating inflammatory and apoptotic processes and hearing loss by activating signal transducer and activator of transcription (STAT1). In this study, we show that the adenosine A1 receptor (A1AR) protects against cisplatin ototoxicity by suppressing an inflammatory response initiated by ROS generation via NOX3 NADPH oxidase, leading to inhibition of STAT1. Trans-tympanic administration of the A1AR agonist R-phenylisopropyladenosine (R-PIA) inhibited cisplatin-induced ototoxicity, as measured by auditory brainstem responses and scanning electron microscopy in male Wistar rats. This was associated with reduced NOX3 expression, STAT1 activation, tumor necrosis factor-α (TNF-α) levels, and apoptosis in the cochlea. In vitro studies in UB/OC-1 cells, an organ of Corti immortalized cell line, showed that R-PIA reduced cisplatin-induced phosphorylation of STAT1 Ser727 (but not Tyr701) and STAT1 luciferase activity by suppressing the ERK1/2, p38, and JNK mitogen-activated protein kinase (MAPK) pathways. R-PIA also decreased the expression of STAT1 target genes, such as TNF-α, inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) and reduced cisplatin-mediated apoptosis. These data suggest that the A1AR provides otoprotection by suppressing NOX3 and inflammation in the cochlea and could serve as an ideal target for otoprotective drug therapy. SIGNIFICANCE STATEMENT Cisplatin is a widely used chemotherapeutic agent for the treatment of solid tumors. Its use results in significant and permanent hearing loss, for which no US Food and Drug Administration-approved treatment is currently available. In this study, we targeted the cochlear adenosine A1 receptor (A1AR) by trans-tympanic injections of the agonist R

  3. Polyamidoamine (PAMAM) Dendrimer Conjugates of Clickable Agonists of the A3 Adenosine Receptor and Coactivation of the P2Y14 Receptor by a Tethered Nucleotide

    Energy Technology Data Exchange (ETDEWEB)

    Tosh, Dilip, K. [National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health; Yoo, Lena S. [National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health; Chinn, Moshe [National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health; Hong, Kunlun [ORNL; Kilbey, II, S Michael [ORNL; Barrett, Matthew O. [University of North Carolina School of Medicine; Fricks, Ingrid P. [University of North Carolina School of Medicine; Harden, T. Kendall [University of North Carolina School of Medicine; Jacobson, Kenneth A. [National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health

    2010-01-01

    We previously synthesized a series of potent and selective A{sub 3} adenosine receptor (AR) agonists (North-methanocarba nucleoside 5{prime}-uronamides) containing dialkyne groups on extended adenine C2 substituents. We coupled the distal alkyne of a 2-octadiynyl nucleoside by Cu(I)-catalyzed 'click' chemistry to azide-derivatized G4 (fourth-generation) PAMAM dendrimers to form triazoles. A{sub 3}AR activation was preserved in these multivalent conjugates, which bound with apparent Ki of 0.1-0.3 nM. They were substituted with nucleoside moieties, solely or in combination with water-solubilizing carboxylic acid groups derived from hexynoic acid. A comparison with various amide-linked dendrimers showed that triazole-linked conjugates displayed selectivity and enhanced A{sub 3}AR affinity. We prepared a PAMAM dendrimer containing equiproportioned peripheral azido and amino groups for conjugation of multiple ligands. A bifunctional conjugate activated both A{sub 3} and P2Y{sub 14} receptors (via amide-linked uridine-5{prime}-diphosphoglucuronic acid), with selectivity in comparison to other ARs and P2Y receptors. This is the first example of targeting two different GPCRs with the same dendrimer conjugate, which is intended for activation of heteromeric GPCR aggregates. Synergistic effects of activating multiple GPCRs with a single dendrimer conjugate might be useful in disease treatment.

  4. Nucleus accumbens neurotransmission and effort-related choice behavior in food motivation: effects of drugs acting on dopamine, adenosine, and muscarinic acetylcholine receptors.

    Science.gov (United States)

    Nunes, Eric J; Randall, Patrick A; Podurgiel, Samantha; Correa, Mercè; Salamone, John D

    2013-11-01

    Mesolimbic dopamine (DA) is a critical component of the brain circuitry regulating behavioral activation and effort-related processes. Although nucleus accumbens (NAc) DA depletions or antagonism leave aspects of appetite and primary food motivation intact, rats with impaired DA transmission reallocate their instrumental behavior away from food-reinforced tasks with high response requirements, and instead select less effortful food-seeking behaviors. Previous work showed that adenosine A2A antagonists can reverse the effects of DA D2 antagonists on effort-related choice, and that stimulation of adenosine A2A receptors produces behavioral effects that are similar to those induced by DA antagonism. The present review summarizes the literature on the role of NAc DA and adenosine in effort-related processes, and also presents original data on the effects of local stimulation of muscarinic acetylcholine receptors in NAc core. Local injections of the muscarinic agonist pilocarpine directly into NAc core produces shifts in effort-related choice behavior similar to those induced by DA antagonism or A2A receptor stimulation, decreasing lever pressing but increasing chow intake in rats responding on a concurrent fixed ratio/chow feeding choice task. In contrast, injections into a neostriatal control site dorsal to the NAc were ineffective. The actions of pilocarpine on this task were attenuated by co-administration of the muscarinic antagonist scopolamine. Thus, drugs that act on DA, adenosine A2A, and muscarinic receptors regulate effort-related choice behavior, which may have implications for the treatment of psychiatric symptoms such as psychomotor slowing, fatigue or anergia that can be observed in depression and other disorders. Copyright © 2013 Elsevier Ltd. All rights reserved.

  5. The role of adenosine A1 and A2A receptors in the caffeine effect on MDMA-induced DA and 5-HT release in the mouse striatum.

    Science.gov (United States)

    Górska, A M; Gołembiowska, K

    2015-04-01

    3,4-Methylenedioxymethamphetamine (MDMA, "ecstasy") popular as a designer drug is often used with caffeine to gain a stronger stimulant effect. MDMA induces 5-HT and DA release by interaction with monoamine transporters. Co-administration of caffeine and MDMA may aggravate MDMA-induced toxic effects on DA and 5-HT terminals. In the present study, we determined whether caffeine influences DA and 5-HT release induced by MDMA. We also tried to find out if adenosine A1 and A2A receptors play a role in the effect of caffeine by investigating the effect of the selective adenosine A1 and A2A receptor antagonists, DPCPX and KW 6002 on DA and 5-HT release induced by MDMA. Mice were treated with caffeine (10 mg/kg) and MDMA (20 or 40 mg/kg) alone or in combination. DA and 5-HT release in the mouse striatum was measured using in vivo microdialysis. Caffeine exacerbated the effect of MDMA on DA and 5-HT release. DPCPX or KW 6002 co-administered with MDMA had similar influence as caffeine, but KW 6002 was more potent than caffeine or DPCPX. To exclude the contribution of MAO inhibition by caffeine in the caffeine effect on MDMA-induced increase in DA and 5-HT, we also tested the effect of the nonxanthine adenosine receptor antagonist CGS 15943A lacking properties of MAO activity modification. Our findings indicate that adenosine A1 and A2A receptor blockade may account for the caffeine-induced exacerbation of the MDMA effect on DA and 5-HT release and may aggravate MDMA toxicity.

  6. Activation of adenosine A3 receptors potentiates stimulatory effects of IL-3, SCF, and GM-CSF on mouse granulocyte-macrophage hematopoietic progenitor cells

    Czech Academy of Sciences Publication Activity Database

    Hofer, Michal; Vacek, Antonín; Pospíšil, Milan; Holá, Jiřina; Štreitová, Denisa; Znojil, V.

    2009-01-01

    Roč. 58, č. 2 (2009), s. 247-252 ISSN 0862-8408 R&D Projects: GA ČR(CZ) GA305/06/0015; GA ČR(CZ) GA305/08/0158 Institutional research plan: CEZ:AV0Z50040507; CEZ:AV0Z50040702 Keywords : hematopoiesis * adenosine A3 receptor agonist * hematopoietic growth factors Subject RIV: BO - Biophysics Impact factor: 1.430, year: 2009

  7. Ethanol and Caffeine effects on social interaction and recognition in mice: Involvement of adenosine A2A and A1 receptors

    Directory of Open Access Journals (Sweden)

    Laura López-Cruz

    2016-11-01

    Full Text Available Ethanol and caffeine are frequently consumed in combination and have opposite effects on the adenosine system: ethanol metabolism leads to an increase in adenosine levels, while caffeine is a non-selective adenosine A1/A2A receptor antagonist. These receptors are highly expressed in striatum and olfactory tubercle, brain areas involved in exploration and social interaction in rodents. Ethanol modulates social interaction processes, but the role of adenosine in social behavior is still poorly understood. The present work was undertaken to study the impact of ethanol, caffeine and their combination on social behavior, and to explore the involvement of A1 and A2A receptors on those actions. Male CD1 mice were evaluated in a social interaction three-chamber paradigm, for preference of conspecific vs. object, and also for long-term recognition memory of familiar vs. novel conspecific. Ethanol showed a biphasic effect, with low doses (0.25 g/kg increasing social contact and higher doses (1.0-1.5 g/kg reducing social interaction. However, no dose changed social preference; mice always spent more time sniffing the conspecific than the object, independently of the ethanol dose. Ethanol, even at doses that did not change social exploration, produced amnestic effects on social recognition the following day. Caffeine reduced social contact (15.0-60.0 mg/kg, and even blocked social preference at higher doses (30.0-60.0 mg/kg. The A1 antagonist CPT (3-9 mg/kg did not modify social contact or preference on its own, and the A2A antagonist MSX-3 (1.5-6 mg/kg increased social interaction at all doses. Ethanol at intermediate doses (0.5-1.0 g/kg was able to reverse the reduction in social exploration induced by caffeine (15.0-30.0 mg/kg. Although there was no interaction between ethanol and CPT or MSX-3 on social exploration in the first day, MSX-3 blocked the amnestic effects of ethanol observed on the following day. Thus, ethanol impairs the formation of social

  8. Administration of caffeine inhibited adenosine receptor agonist-induced decreases in motor performance, thermoregulation, and brain neurotransmitter release in exercising rats.

    Science.gov (United States)

    Zheng, Xinyan; Hasegawa, Hiroshi

    2016-01-01

    We examined the effects of an adenosine receptor agonist on caffeine-induced changes in thermoregulation, neurotransmitter release in the preoptic area and anterior hypothalamus, and endurance exercise performance in rats. One hour before the start of exercise, rats were intraperitoneally injected with either saline alone (SAL), 10 mg kg(-1) caffeine and saline (CAF), a non-selective adenosine receptor agonist (5'-N-ethylcarboxamidoadenosine [NECA]: 0.5 mg kg(-1)) and saline (NECA), or the combination of caffeine and NECA (CAF+NECA). Rats ran until fatigue on the treadmill with a 5% grade at a speed of 18 m min(-1) at 23 °C. Compared to the SAL group, the run time to fatigue (RTTF) was significantly increased by 52% following caffeine administration and significantly decreased by 65% following NECA injection (SAL: 91 ± 14.1 min; CAF: 137 ± 25.8 min; NECA: 31 ± 13.7 min; CAF+NECA: 85 ± 11.8 min; pcaffeine injection inhibited the NECA-induced decreases in the RTTF, Tcore, heat production, heat loss, and extracellular DA release. Neither caffeine nor NECA affected extracellular noradrenaline or serotonin release. These results support the findings of previous studies showing improved endurance performance and overrides in body limitations after caffeine administration, and imply that the ergogenic effects of caffeine may be associated with the adenosine receptor blockade-induced increases in brain DA release. Copyright © 2015 Elsevier Inc. All rights reserved.

  9. Binding of the Antagonist Caffeine to the Human Adenosine Receptor hA2AR in Nearly Physiological Conditions.

    Directory of Open Access Journals (Sweden)

    Ruyin Cao

    Full Text Available Lipid composition may significantly affect membrane proteins function, yet its impact on the protein structural determinants is not well understood. Here we present a comparative molecular dynamics (MD study of the human adenosine receptor type 2A (hA(2AR in complex with caffeine--a system of high neuro-pharmacological relevance--within different membrane types. These are POPC, mixed POPC/POPE and cholesterol-rich membranes. 0.8-μs MD simulations unambiguously show that the helical folding of the amphipathic helix 8 depends on membrane contents. Most importantly, the distinct cholesterol binding into the cleft between helix 1 and 2 stabilizes a specific caffeine-binding pose against others visited during the simulation. Hence, cholesterol presence (~33%-50% in synaptic membrane in central nervous system, often neglected in X-ray determination of membrane proteins, affects the population of the ligand binding poses. We conclude that including a correct description of neuronal membranes may be very important for computer-aided design of ligands targeting hA(2AR and possibly other GPCRs.

  10. Preparation and first evaluation of [18F]FE-SUPPY: a new PET tracer for the adenosine A3 receptor

    International Nuclear Information System (INIS)

    Wadsak, Wolfgang; Mien, Leonhard-Key; Shanab, Karem; Ettlinger, Dagmar E.; Haeusler, Daniela; Sindelar, Karoline; Lanzenberger, Rupert R.; Spreitzer, Helmut; Viernstein, Helmut; Keppler, Bernhard K.; Dudczak, Robert; Kletter, Kurt; Mitterhauser, Markus

    2008-01-01

    Introduction: Changes of the adenosine A 3 receptor subtype (A3AR) expression have been shown in a variety of pathologies, especially neurological and affective disorders, cardiac diseases and oncological and inflammation processes. Recently, 5-(2-fluoroethyl) 2,4-diethyl-3-(ethylsulfanylcarbonyl)-6-phenylpyridine-5-carboxylate (FE-SUPPY) was presented as a high-affinity ligand for the A3AR with good selectivity. Our aims were the development of a suitable labeling precursor, the establishment of a reliable radiosynthesis for the fluorine-18-labeled analogue [ 18 F]FE-SUPPY and a first evaluation of [ 18 F]FE-SUPPY in rats. Methods: [ 18 F]FE-SUPPY was prepared in a feasible and reliable manner by radiofluorination of the corresponding tosylated precursor. Biodistribution was carried out in rats, and organs were removed and counted. Autoradiography was performed on rat brain slices in the presence or absence of 2-Cl-IB-MECA. Results: Overall yields and radiochemical purity were sufficient for further preclinical and clinical applications. The uptake pattern of [ 18 F]FE-SUPPY found in rats mainly followed the described mRNA distribution pattern of the A3AR. Specific uptake in brain was demonstrated by blocking with a selective A3AR agonist. Conclusion: We conclude that [ 18 F]FE-SUPPY has the potential to serve as the first positron emission tomography tracer for the A3AR

  11. Adenosine A2A Receptors Control Glutamatergic Synaptic Plasticity in Fast Spiking Interneurons of the Prefrontal Cortex

    Directory of Open Access Journals (Sweden)

    Amber Kerkhofs

    2018-03-01

    Full Text Available Adenosine A2A receptors (A2AR are activated upon increased synaptic activity to assist in the implementation of long-term plastic changes at synapses. While it is reported that A2AR are involved in the control of prefrontal cortex (PFC-dependent behavior such as working memory, reversal learning and effort-based decision making, it is not known whether A2AR control glutamatergic synapse plasticity within the medial PFC (mPFC. To elucidate that, we tested whether A2AR blockade affects long-term plasticity (LTP of excitatory post-synaptic potentials in pyramidal neurons and fast spiking (FS interneurons in layer 5 of the mPFC and of population spikes. Our results show that A2AR are enriched at mPFC synapses, where their blockade reversed the direction of plasticity at excitatory synapses onto layer 5 FS interneurons from LTP to long-term depression, while their blockade had no effect on the induction of LTP at excitatory synapses onto layer 5 pyramidal neurons. At the network level, extracellularly induced LTP of population spikes was reduced by A2AR blockade. The interneuron-specificity of A2AR in controlling glutamatergic synapse LTP may ensure that during periods of high synaptic activity, a proper excitation/inhibition balance is maintained within the mPFC.

  12. Adenosine A2A Receptor and IL-10 in Peripheral Blood Mononuclear Cells of Patients with Mild Cognitive Impairment

    Directory of Open Access Journals (Sweden)

    Beatrice Arosio

    2011-01-01

    Full Text Available Adenosine suppresses immune responses through the A2A receptor (A2AR. This study investigated the interleukin 10 (IL-10 genetic profile and the expression of A2AR in peripheral blood mononuclear cells (PBMCs of patients with mild cognitive impairment (MCI, Alzheimer disease (AD, and age-matched controls to verify, if they may help distinguish different forms of cognitive decline. We analyzed the IL-10 genotype and the expression of A2AR in 41 subjects with AD, 10 with amnestic MCI (a-MCI, 49 with multiple cognitive domain MCI (mcd-MCI, and 46 controls. There was a significant linear increase in A2AR mRNA levels and A2AR density from mcd-MCI to a-MCI, with intermediate levels being found in AD. The IL-10 AA genotype frequency was 67% in a-MCI, 46% in AD, 35% in mcd-MCI, and 20% in controls. These data suggest that the assessment of the IL-10 genotype and the expression of A2AR in PBMCs may be a valuable means of differentiating between a-MCI and mcd-MCI.

  13. Theobromine suppresses adipogenesis through enhancement of CCAAT-enhancer-binding protein β degradation by adenosine receptor A1.

    Science.gov (United States)

    Mitani, Takakazu; Watanabe, Shun; Yoshioka, Yasukiyo; Katayama, Shigeru; Nakamura, Soichiro; Ashida, Hitoshi

    2017-12-01

    Theobromine, a methylxanthine derived from cacao beans, reportedly has various health-promoting properties but molecular mechanism by which effects of theobromine on adipocyte differentiation and adipogenesis remains unclear. In this study, we aimed to clarify the molecular mechanisms of the anti-adipogenic effect of theobromine in vitro and in vivo. ICR mice (4week-old) were administered with theobromine (0.1g/kg) for 7days. Theobromine administration attenuated gains in body and epididymal adipose tissue weights in mice and suppressed expression of adipogenic-associated genes in mouse adipose tissue. In 3T3-L1 preadipocytes, theobromine caused degradation of C/EBPβ protein by the ubiquitin-proteasome pathway. Pull down assay showed that theobromine selectively interacts with adenosine receptor A1 (AR1), and AR1 knockdown inhibited theobromine-induced C/EBPβ degradation. Theobromine increased sumoylation of C/EBPβ at Lys133. Expression of the small ubiquitin-like modifier (SUMO)-specific protease 2 (SENP2) gene, coding for a desumoylation enzyme, was suppressed by theobromine. In vivo knockdown studies showed that AR1 knockdown in mice attenuated the anti-adipogenic effects of theobromine in younger mice. Theobromine suppresses adipocyte differentiation and induced C/EBPβ degradation by increasing its sumoylation. Furthermore, the inhibition of AR1 signaling is important for theobromine-induced C/EBPβ degradation. Copyright © 2017 Elsevier B.V. All rights reserved.

  14. Discovery of indolylpiperazinylpyrimidines with dual-target profiles at adenosine A2A and dopamine D2 receptors for Parkinson's disease treatment.

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    Yi-Ming Shao

    Full Text Available Parkinson's disease (PD is a neurodegenerative disorder characterized by progressive loss of dopaminergic neurons in the substantia nigra of the human brain, leading to depletion of dopamine production. Dopamine replacement therapy remains the mainstay for attenuation of PD symptoms. Nonetheless, the potential benefit of current pharmacotherapies is mostly limited by adverse side effects, such as drug-induced dyskinesia, motor fluctuations and psychosis. Non-dopaminergic receptors, such as human A2A adenosine receptors, have emerged as important therapeutic targets in potentiating therapeutic effects and reducing the unwanted side effects. In this study, new chemical entities targeting both human A2A adenosine receptor and dopamine D2 receptor were designed and evaluated. Two computational methods, namely support vector machine (SVM models and Tanimoto similarity-based clustering analysis, were integrated for the identification of compounds containing indole-piperazine-pyrimidine (IPP scaffold. Subsequent synthesis and testing resulted in compounds 5 and 6, which acted as human A2A adenosine receptor binders in the radioligand competition assay (Ki = 8.7-11.2 μM as well as human dopamine D2 receptor binders in the artificial cell membrane assay (EC50 = 22.5-40.2 μM. Moreover, compound 5 showed improvement in movement and mitigation of the loss of dopaminergic neurons in Drosophila models of PD. Furthermore, in vitro toxicity studies on compounds 5 and 6 did not reveal any mutagenicity (up to 100 μM, hepatotoxicity (up to 30 μM or cardiotoxicity (up to 30 μM.

  15. Nucleoside conjugates of quantum dots for characterization of G protein-coupled receptors: strategies for immobilizing A2A adenosine receptor agonists

    Directory of Open Access Journals (Sweden)

    Gao Zhan-Guo

    2010-05-01

    Full Text Available Abstract Background Quantum dots (QDs are crystalline nanoparticles that are compatible with biological systems to provide a chemically and photochemically stable fluorescent label. New ligand probes with fluorescent reporter groups are needed for detection and characterization of G protein-coupled receptors (GPCRs. Results Synthetic strategies for coupling the A2A adenosine receptor (AR agonist CGS21680 (2-[4-(2-carboxyethylphenylethylamino]-5'-N-ethylcarboxamidoadenosine to functionalized QDs were explored. Conjugates tethered through amide-linked chains and poly(ethyleneglycol (PEG displayed low solubility and lacked receptor affinity. The anchor to the dendron was either through two thiol groups of (R-thioctic acid or through amide formation to a commercial carboxy-derivatized QD. The most effective approach was to use polyamidoamine (PAMAM D5 dendrons as multivalent spacer groups, grafted on the QD surface through a thioctic acid moiety. In radioligand binding assays, dendron nucleoside conjugate 11 displayed a moderate affinity at the human A2AAR (Kiapp 1.02 ± 0.15 μM. The QD conjugate of increased water solubility 13, resulting from the anchoring of this dendron derivative, interacted with the receptor with Kiapp of 118 ± 54 nM. The fluorescence emission of 13 occurred at 565 nm, and the presence of the pendant nucleoside did not appreciably quench the fluorescence. Conclusions This is a feasibility study to demonstrate a means of conjugating to a QD a small molecular pharmacophore of a GPCR that is relatively hydrophobic. Further enhancement of affinity by altering the pharmacophore or the linking structures will be needed to make useful affinity probes.

  16. Adenosine A(2A receptors measured with [C]TMSX PET in the striata of Parkinson's disease patients.

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    Masahiro Mishina

    Full Text Available Adenosine A(2A receptors (A2ARs are thought to interact negatively with the dopamine D(2 receptor (D2R, so selective A2AR antagonists have attracted attention as novel treatments for Parkinson's disease (PD. However, no information about the receptor in living patients with PD is available. The purpose of this study was to investigate the relationship between A2ARs and the dopaminergic system in the striata of drug-naïve PD patients and PD patients with dyskinesia, and alteration of these receptors after antiparkinsonian therapy. We measured binding ability of striatal A2ARs using positron emission tomography (PET with [7-methyl-(11C]-(E-8-(3,4,5-trimethoxystyryl-1,3,7-trimethylxanthine ([(11C]TMSX in nine drug-naïve patients with PD, seven PD patients with mild dyskinesia and six elderly control subjects using PET. The patients and eight normal control subjects were also examined for binding ability of dopamine transporters and D2Rs. Seven of the drug-naïve patients underwent a second series of PET scans following therapy. We found that the distribution volume ratio of A2ARs in the putamen were larger in the dyskinesic patients than in the control subjects (p<0.05, Tukey-Kramer post hoc test. In the drug-naïve patients, the binding ability of the A2ARs in the putamen, but not in the head of caudate nucleus, was significantly lower on the more affected side than on the less affected side (p<0.05, paired t-test. In addition, the A2ARs were significantly increased after antiparkinsonian therapy in the bilateral putamen of the drug-naïve patients (p<0.05, paired t-test but not in the bilateral head of caudate nucleus. Our study demonstrated that the A2ARs in the putamen were increased in the PD patients with dyskinesia, and also suggest that the A2ARs in the putamen compensate for the asymmetrical decrease of dopamine in drug-naïve PD patients and that antiparkinsonian therapy increases the A2ARs in the putamen. The A2ARs may play an

  17. Preclinical tools in PET-tracer development : automatisation and biopharmaceutical evaluation with special emphasis on the adenosine A3 receptor

    International Nuclear Information System (INIS)

    Haeusler, D. I. B.

    2010-01-01

    Positron Emission Tomography (PET) is the first choice technology for the visualization and quantification of receptors and transporters, enabling examination of e.g. neurological, psychiatric and oncological diseases on a molecular level. Therefore, new and innovative PET-radiopharmaceuticals need to be developed to get further insights into the biochemical mechanisms involved in pathological changes. PET-tracer development starts with the idea or modelling of the chemical structure of a (new) molecule with (hopefully) good binding characteristics to the desired target site. As next steps, the compound needs to be synthesized and radiolabelled with a suitable PET-nuclide. Then it has to be evaluated regarding its parameters in various preclinical experimental settings. Hence, two major tools are crucial in the development-process of new PET-tracers: 1) a fast and reliable production method, most desirable and optimal in an automated set-up, and 2) proof of tracer suitability (high affinity, high selectivity and specificity, beside low unspecific binding) through preclinical evaluation in an animal model, prior to human application. Both aspects, the radiochemical preparation and automatisation, as well as the biopharmaceutical evaluation are presented in the thesis in 5 different manuscripts. In detail, the development and preclinical evaluation of 4 different PET-tracers ([11C]DASB, [18F]FE SUPPY, [18F]FE SUPPY:2, and [18F]FE CIT) for 3 targets, the serotonin transporter (SERT), the adenosine A3 receptor (A3R) and the dopamine transporter (DAT), respectively, are covered in the present thesis. The first manuscript presents a method for a fast, reliable and fully-automated radiosynthesis of [11C]DASB (a tracer for the imaging of the SERT in human brain in e.g. depression patients) will facilitate further clinical investigations (e.g. for the department of psychiatry and psychotherapy of the medical university of Vienna) with this tracer. [18F]FE SUPPY was

  18. Adenosine A1 receptor-mediated inhibition of in vitro prolactin secretion from the rat anterior pituitary

    Directory of Open Access Journals (Sweden)

    D.L.W. Picanço-Diniz

    2006-11-01

    Full Text Available In previous studies, we demonstrated biphasic purinergic effects on prolactin (PRL secretion stimulated by an adenosine A2 agonist. In the present study, we investigated the role of the activation of adenosine A1 receptors by (R-N6-(2-phenylisopropyladenosine (R-PIA at the pituitary level in in vitro PRL secretion. Hemipituitaries (one per cuvette in five replicates from adult male rats were incubated. Administration of R-PIA (0.001, 0.01, 0.1, 1, and 10 µM induced a reduction of PRL secretion into the medium in a U-shaped dose-response curve. The maximal reduction was obtained with 0.1 µM R-PIA (mean ± SEM, 36.01 ± 5.53 ng/mg tissue weight (t.w. treatment compared to control (264.56 ± 15.46 ng/mg t.w.. R-PIA inhibition (0.01 µM = 141.97 ± 15.79 vs control = 244.77 ± 13.79 ng/mg t.w. of PRL release was blocked by 1 µM cyclopentyltheophylline, a specific A1 receptor antagonist (1 µM = 212.360 ± 26.560 ng/mg t.w., whereas cyclopentyltheophylline alone (0.01, 0.1, 1 µM had no effect. R-PIA (0.001, 0.01, 0.1, 1 µM produced inhibition of PRL secretion stimulated by both phospholipase C (0.5 IU/mL; 977.44 ± 76.17 ng/mg t.w. and dibutyryl cAMP (1 mM; 415.93 ± 37.66 ng/mg t.w. with nadir established at the dose of 0.1 µM (225.55 ± 71.42 and 201.9 ± 19.08 ng/mg t.w., respectively. Similarly, R-PIA (0.01 µM decreased (242.00 ± 24.00 ng/mg t.w. the PRL secretion stimulated by cholera toxin (0.5 mg/mL; 1050.00 ± 70.00 ng/mg t.w.. In contrast, R-PIA had no effect (468.00 ± 34.00 ng/mg t.w. on PRL secretion stimulation by pertussis toxin (0.5 mg/mL; 430.00 ± 26.00 ng/mg t.w.. These results suggest that inhibition of PRL secretion after A1 receptor activation by R-PIA is mediated by a Gi protein-dependent mechanism.

  19. The stimulatory adenosine receptor ADORA2B regulates serotonin (5-HT synthesis and release in oxygen-depleted EC cells in inflammatory bowel disease.

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    Rikard Dammen

    Full Text Available We recently demonstrated that hypoxia, a key feature of IBD, increases enterochromaffin (EC cell 5-HT secretion, which is also physiologically regulated by the ADORA2B mechanoreceptor. Since hypoxia is associated with increased extracellular adenosine, we wanted to examine whether this nucleotide amplifies HIF-1α-mediated 5-HT secretion.The effects of hypoxia were studied on IBD mucosa, isolated IBD-EC cells, isolated normal EC cells and the EC cell tumor derived cell line KRJ-1. Hypoxia (0.5% O2 was compared to NECA (adenosine agonist, MRS1754 (ADORA2B receptor antagonist and SCH442146 (ADORA2A antagonist on HIF signaling and 5-HT secretion. Antisense approaches were used to mechanistically evaluate EC cells in vitro. PCR and western blot were used to analyze transcript and protein levels of HIF-1α signaling and neuroendocrine cell function. An animal model of colitis was evaluated to confirm hypoxia:adenosine signaling in vivo.HIF-1α is upregulated in IBD mucosa and IBD-EC cells, the majority (~90% of which express an activated phenotype in situ. Hypoxia stimulated 5-HT release maximally at 30 mins, an effect amplified by NECA and selectively inhibited by MRS1754, through phosphorylation of TPH-1 and activation of VMAT-1. Transient transfection with Renilla luciferase under hypoxia transcriptional response element (HRE control identified that ADORA2B activated HIF-1α signaling under hypoxic conditions. Additional signaling pathways associated with hypoxia:adenosine included MAP kinase and CREB. Antisense approaches mechanistically confirmed that ADORA2B signaling was linked to these pathways and 5-HT release under hypoxic conditions. Hypoxia:adenosine activation which could be reversed by 5'-ASA treatment was confirmed in a TNBS-model.Hypoxia induced 5-HT synthesis and secretion is amplified by ADORA2B signaling via MAPK/CREB and TPH-1 activation. Targeting ADORA2s may decrease EC cell 5-HT production and secretion in IBD.

  20. Adenosine A{sub 2A} receptor imaging with [{sup 11}C]KF18446 PET in the rat brain after quinolinic acid lesion. Comparison with the dopamine receptor imaging

    Energy Technology Data Exchange (ETDEWEB)

    Ishiwata, Kiichi; Ogi, Nobuo; Hayakawa, Nobutaka [Tokyo Metropolitan Inst. of Gerontology, Tokyo (Japan). Positron Medical Center] [and others

    2002-11-01

    We proposed [{sup 11}C]KF18446 as a selective radioligand for mapping the adenosine A{sub 2A} receptors being highly enriched in the striatum by positron emission tomography (PET). In the present study, we investigated whether [{sup 11}C]KF18446 PET can detect the change in the striatal adenosine A{sub 2A} receptors in the rat after unilateral injection of an excitotoxin quinolinic acid into the striatum, a Huntington's disease model, to demonstrate the usefulness of [{sup 11}C]KF18446. The extent of the striatal lesion was identified based on MRI, to which the PET was co-registered. The binding potential of [{sup 11}C]KF18446 significantly decreased in the quinolinic acid-lesioned striatum. The decrease was comparable to the decrease in the potential of [{sup 11}C] raclopride binding to dopamine D{sub 2} receptors in the lesioned striatum, but seemed to be larger than the decrease in the potential of [{sup 11}C]SCH23390 binding to dopamine D{sub 1} receptors. Ex vivo and in vitro autoradiography validated the PET signals. We concluded that [{sup 11}C]KF18446 PET can detect change in the adenosine A{sub 2A} receptors in the rat model, and will provide a new diagnostic tool for characterizing post-synaptic striatopallidal neurons in the stratum. (author)

  1. Carbamazepine and oxcarbazepine, but not eslicarbazepine, enhance excitatory synaptic transmission onto hippocampal CA1 pyramidal cells through an antagonist action at adenosine A1 receptors.

    Science.gov (United States)

    Booker, Sam A; Pires, Nuno; Cobb, Stuart; Soares-da-Silva, Patrício; Vida, Imre

    2015-06-01

    This study assessed the anticonvulsant and seizure generation effects of carbamazepine (CBZ), oxcarbazepine (OXC) and eslicarbazepine (S-Lic) in wild-type mice. Electrophysiological recordings were made to discriminate potential cellular and synaptic mechanisms underlying anti- and pro-epileptic actions. The anticonvulsant and pro-convulsant effects were evaluated in the MES, the 6-Hz and the Irwin tests. Whole-cell patch-clamp recordings were used to investigate the effects on fast excitatory and inhibitory synaptic transmission in hippocampal area CA1. The safety window for CBZ, OXC and eslicarbazepine (ED50 value against the MES test and the dose that produces grade 5 convulsions in all mice), was 6.3, 6.0 and 12.5, respectively. At high concentrations the three drugs reduced synaptic transmission. CBZ and OXC enhanced excitatory postsynaptic currents (EPSCs) at low, therapeutically-relevant concentrations. These effects were associated with no change in inhibitory postsynaptic currents (IPSCs) resulting in altered balance between excitation and inhibition. S-Lic had no effect on EPSC or IPSC amplitudes over the same concentration range. The CBZ mediated enhancement of EPSCs was blocked by DPCPX, a selective antagonist, and occluded by CCPA, a selective agonist of the adenosine A1 receptor. Furthermore, reduction of endogenous adenosine by application of the enzyme adenosine deaminase also abolished the CBZ- and OXC-induced increase of EPSCs, indicating that the two drugs act as antagonists at native adenosine receptors. In conclusion, CBZ and OXC possess pro-epileptic actions at clinically-relevant concentrations through the enhancement of excitatory synaptic transmission. S-Lic by comparison has no such effect on synaptic transmission, explaining its lack of seizure exacerbation. Copyright © 2015 Elsevier Ltd. All rights reserved.

  2. Quantification of adenosine A2A receptors in the human brain using [11C]TMSX and positron emission tomography

    International Nuclear Information System (INIS)

    Naganawa, Mika; Kimura, Yuichi; Oda, Keiichi; Ishii, Kenji; Ishiwata, Kiichi; Mishina, Masahiro; Manabe, Yoshitsugu; Chihara, Kunihiro

    2007-01-01

    [7-methyl- 11 C]-(E)-8-(3,4,5-trimethoxystyryl)-1,3,7-trimethylxanthine ([ 11 C]TMSX) is a positron-emitting adenosine A 2A receptor (A2AR) antagonist for visualisation of A2AR distribution by positron emission tomography (PET). The aims of this paper were to use a kinetic model to analyse the behaviour of [ 11 C]TMSX in the brain and to examine the applicability of the Logan plot. We also studied the applicability of a simplified Logan plot by omitting metabolite correction and arterial blood sampling. The centrum semiovale was used as a reference region on the basis of a post-mortem study showing that it has a negligibly low density of A2ARs. Compartmental analysis was performed in five normal subjects. Parametric images of A2AR binding potential (BP) were also generated using a Logan plot with or without metabolite correction and with or without arterial blood sampling. To omit arterial blood sampling, we applied a method to extract the plasma-related information using independent component analysis (EPICA). The estimated K 1 /k 2 was confirmed to be common in the centrum semiovale and main cortices. The three-compartment model was well fitted to the other regions using the fixed value of K 1 /k 2 estimated from the centrum semiovale. The estimated BPs using the Logan plot matched those derived from compartment analysis. Without the metabolite correction, the estimate of BP underestimated the true value by 5%. The estimated BPs agreed regardless of arterial blood sampling. A three-compartment model with a reference region, the centrum semiovale, describes the kinetic behaviour of [ 11 C]TMSX PET images. A2ARs in the human brain can be visualised as a BP image using [ 11 C]TMSX PET without arterial blood sampling. (orig.)

  3. Transporter Protein-Coupled DPCPX Nanoconjugates Induce Diaphragmatic Recovery after SCI by Blocking Adenosine A1 Receptors.

    Science.gov (United States)

    Minic, Zeljka; Zhang, Yanhua; Mao, Guangzhao; Goshgarian, Harry G

    2016-03-23

    Respiratory complications in patients with spinal cord injury (SCI) are common and have a negative impact on the quality of patients' lives. Systemic administration of drugs that improve respiratory function often cause deleterious side effects. The present study examines the applicability of a novel nanotechnology-based drug delivery system, which induces recovery of diaphragm function after SCI in the adult rat model. We developed a protein-coupled nanoconjugate to selectively deliver by transsynaptic transport small therapeutic amounts of an A1 adenosine receptor antagonist to the respiratory centers. A single administration of the nanoconjugate restored 75% of the respiratory drive at 0.1% of the systemic therapeutic drug dose. The reduction of the systemic dose may obviate the side effects. The recovery lasted for 4 weeks (the longest period studied). These findings have translational implications for patients with respiratory dysfunction after SCI. The leading causes of death in humans following SCI are respiratory complications secondary to paralysis of respiratory muscles. Systemic administration of methylxantines improves respiratory function but also leads to the development of deleterious side effects due to actions of the drug on nonrespiratory sites. The importance of the present study lies in the novel drug delivery approach that uses nanotechnology to selectively deliver recovery-inducing drugs to the respiratory centers exclusively. This strategy allows for a reduction in the therapeutic drug dose, which may reduce harmful side effects and markedly improve the quality of life for SCI patients. Copyright © 2016 the authors 0270-6474/16/363441-12$15.00/0.

  4. Predicting Subtype Selectivity for Adenosine Receptor Ligands with Three-Dimensional Biologically Relevant Spectrum (BRS-3D)

    Science.gov (United States)

    He, Song-Bing; Ben Hu; Kuang, Zheng-Kun; Wang, Dong; Kong, De-Xin

    2016-11-01

    Adenosine receptors (ARs) are potential therapeutic targets for Parkinson’s disease, diabetes, pain, stroke and cancers. Prediction of subtype selectivity is therefore important from both therapeutic and mechanistic perspectives. In this paper, we introduced a shape similarity profile as molecular descriptor, namely three-dimensional biologically relevant spectrum (BRS-3D), for AR selectivity prediction. Pairwise regression and discrimination models were built with the support vector machine methods. The average determination coefficient (r2) of the regression models was 0.664 (for test sets). The 2B-3 (A2B vs A3) model performed best with q2 = 0.769 for training sets (10-fold cross-validation), and r2 = 0.766, RMSE = 0.828 for test sets. The models’ robustness and stability were validated with 100 times resampling and 500 times Y-randomization. We compared the performance of BRS-3D with 3D descriptors calculated by MOE. BRS-3D performed as good as, or better than, MOE 3D descriptors. The performances of the discrimination models were also encouraging, with average accuracy (ACC) 0.912 and MCC 0.792 (test set). The 2A-3 (A2A vs A3) selectivity discrimination model (ACC = 0.882 and MCC = 0.715 for test set) outperformed an earlier reported one (ACC = 0.784). These results demonstrated that, through multiple conformation encoding, BRS-3D can be used as an effective molecular descriptor for AR subtype selectivity prediction.

  5. Caffeine reverses age-related deficits in olfactory discrimination and social recognition memory in rats. Involvement of adenosine A1 and A2A receptors.

    Science.gov (United States)

    Prediger, Rui D S; Batista, Luciano C; Takahashi, Reinaldo N

    2005-06-01

    Caffeine, a non-selective adenosine receptor antagonist, has been suggested as a potential drug to counteract age-related cognitive decline since critical changes in adenosinergic neurotransmission occur with aging. In the present study, olfactory discrimination and short-term social memory of 3, 6, 12 and 18 month-old rats were assessed with the olfactory discrimination and social recognition tasks, respectively. The actions of caffeine (3.0, 10.0 and 30.0 mg/kg, i.p.), the A1 receptor antagonist DPCPX (1.0 and 3.0 mg/kg, i.p.) and the A2A receptor antagonist ZM241385 (0.5 and 1.0 mg/kg, i.p.) in relation to age-related effects on olfactory functions were also studied. The 12 and 18 month-old rats exhibited significantly impaired performance in both models, demonstrating deficits in their odor discrimination and in their ability to recognize a juvenile rat after a short period of time. Acute treatment with caffeine or ZM241385, but not with DPCPX, reversed these age-related olfactory deficits. The present results suggest the participation of adenosine receptors in the control of olfactory functions and confirm the potential of caffeine for the treatment of aged-related cognitive decline.

  6. 2',3'-cAMP, 3'-AMP, 2'-AMP and adenosine inhibit TNF-α and CXCL10 production from activated primary murine microglia via A2A receptors.

    Science.gov (United States)

    Newell, Elizabeth A; Exo, Jennifer L; Verrier, Jonathan D; Jackson, Travis C; Gillespie, Delbert G; Janesko-Feldman, Keri; Kochanek, Patrick M; Jackson, Edwin K

    2015-01-12

    Some cells, tissues and organs release 2',3'-cAMP (a positional isomer of 3',5'-cAMP) and convert extracellular 2',3'-cAMP to 2'-AMP plus 3'-AMP and convert these AMPs to adenosine (called the extracellular 2',3'-cAMP-adenosine pathway). Recent studies show that microglia have an extracellular 2',3'-cAMP-adenosine pathway. The goal of the present study was to investigate whether the extracellular 2',3'-cAMP-adenosine pathway could have functional consequences on the production of cytokines/chemokines by activated microglia. Experiments were conducted in cultures of primary murine microglia. In the first experiment, the effect of 2',3'-cAMP, 3'-AMP, 2'-AMP and adenosine on LPS-induced TNF-α and CXCL10 production was determined. In the next experiment, the first protocol was replicated but with the addition of 1,3-dipropyl-8-p-sulfophenylxanthine (DPSPX) (0.1 μM; antagonist of adenosine receptors). The last experiment compared the ability of 2-chloro-N(6)-cyclopentyladenosine (CCPA) (10 μM; selective A1 agonist), 5'-N-ethylcarboxamide adenosine (NECA) (10 μM; agonist for all adenosine receptor subtypes) and CGS21680 (10 μM; selective A2A agonist) to inhibit LPS-induced TNF-α and CXCL10 production. (1) 2',3'-cAMP, 3'-AMP, 2'-AMP and adenosine similarly inhibited LPS-induced TNF-α and CXCL10 production; (2) DPSPX nearly eliminated the inhibitory effects of 2',3'-cAMP, 3'-AMP, 2'-AMP and adenosine on LPS-induced TNF-α and CXCL10 production; (3) CCPA did not affect LPS-induced TNF-α and CXCL10; (4) NECA and CGS21680 similarly inhibited LPS-induced TNF-α and CXCL10 production. 2',3'-cAMP and its metabolites (3'-AMP, 2'-AMP and adenosine) inhibit LPS-induced TNF-α and CXCL10 production via A2A-receptor activation. Adenosine and its precursors, via A2A receptors, likely suppress TNF-α and CXCL10 production by activated microglia in brain diseases. Copyright © 2014 Elsevier B.V. All rights reserved.

  7. 2’,3’-cAMP, 3’-AMP, 2’-AMP and Adenosine Inhibit TNF-α and CXCL10 Production From Activated Primary Murine Microglia via A2A Receptors

    Science.gov (United States)

    Newell, Elizabeth A.; Exo, Jennifer L.; Verrier, Jonathan D.; Jackson, Travis C.; Gillespie, Delbert G.; Janesko-Feldman, Keri; Kochanek, Patrick M.

    2014-01-01

    Background Some cells, tissues and organs release 2’,3’-cAMP (a positional isomer of 3’,5’-cAMP) and convert extracellular 2’,3’-cAMP to 2’-AMP plus 3’-AMP and convert these AMPs to adenosine (called the extracellular 2’,3’-cAMP-adenosine pathway). Recent studies show that microglia have an extracellular 2’,3’-cAMP-adenosine pathway. The goal of the present study was to investigate whether the extracellular 2’,3’-cAMP-adenosine pathway could have functional consequences on the production of cytokines/chemokines by activated microglia. Methods Experiments were conducted in cultures of primary murine microglia. In the first experiment, the effect of 2’,3’-cAMP, 3’-AMP, 2’-AMP and adenosine on LPS-induced TNF-α and CXCL10 production was determined. In the next experiment, the first protocol was replicated but with the addition of 1,3-dipropyl-8-p-sulfophenylxanthine (DPSPX) (0.1 µM; antagonist of adenosine receptors). The last experiment compared the ability of 2-chloro-N6-cyclopentyladenosine (CCPA) (10 µM; selective A1 agonist), 5’-N-ethylcarboxamide adenosine (NECA) (10 µM; agonist for all adenosine receptor subtypes) and CGS21680 (10 µM; selective A2A agonist) to inhibit LPS-induced TNF-α and CXCL10 production. Results 1) 2’,3’-cAMP, 3’-AMP, 2’-AMP and adenosine similarly inhibited LPS-induced TNF-α and CXCL10 production; 2) DPSPX nearly eliminated the inhibitory effects of 2’,3’-cAMP, 3’-AMP, 2’-AMP and adenosine on LPS-induced TNF-α and CXCL10 production; 3) CCPA did not affect LPS-induced TNF-α and CXCL10; 4) NECA and CGS21680 similarly inhibited LPS-induced TNF-α and CXCL10 production. Conclusions 2’,3’-cAMP and its metabolites (3’-AMP, 2’-AMP and adenosine) inhibit LPS-induced TNF-α and CXCL10 production via A2A-receptor activation. Adenosine and its precursors, via A2A receptors, likely suppress TNF-α and CXCL10 production by activated microglia in brain diseases. PMID:25451117

  8. Adenosine A2A receptors modulate the dopamine D2 receptor-mediated inhibition of synaptic transmission in the mouse prefrontal cortex.

    Science.gov (United States)

    Real, Joana I; Simões, Ana Patrícia; Cunha, Rodrigo A; Ferreira, Samira G; Rial, Daniel

    2018-05-01

    Prefrontal cortex (PFC) circuits are modulated by dopamine acting on D 1 - and D 2 -like receptors, which are pharmacologically exploited to manage neuropsychiatric conditions. Adenosine A 2A receptors (A 2 A R) also control PFC-related responses and A 2 A R antagonists are potential anti-psychotic drugs. As tight antagonistic A 2 A R-D 2 R and synergistic A 2 A R-D 1 R interactions occur in other brain regions, we now investigated the crosstalk between A 2 A R and D 1 /D 2 R controlling synaptic transmission between layers II/III and V in mouse PFC coronal slices. Dopamine decreased synaptic transmission, a presynaptic effect based on the parallel increase in paired-pulse responses. Dopamine inhibition was prevented by the D 2 R-like antagonist sulpiride but not by the D 1 R antagonist SCH23390 and was mimicked by the D 2 R agonist sumanirole, but not by the agonists of either D 4 R (A-412997) or D 3 R (PD128907). Dopamine inhibition was prevented by the A 2 A R antagonist, SCH58261, and attenuated in A 2 A R knockout mice. Accordingly, triple-labelling immunocytochemistry experiments revealed the co-localization of A 2 A R and D 2 R immunoreactivity in glutamatergic (vGluT1-positive) nerve terminals of the PFC. This reported positive A 2 A R-D 2 R interaction controlling PFC synaptic transmission provides a mechanistic justification for the anti-psychotic potential of A 2 A R antagonists. © 2018 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

  9. Quantitative analysis of adenosine A1 receptors in human brain using positron emission tomography and [1 -methyl-11C]8-dicyclopropylmethyl-1-methyl-3-propylxanthine

    International Nuclear Information System (INIS)

    Kimura, Yuichi; Ishii, Kenji; Fukumitsu, Nobuyoshi; Oda, Keiichi; Sasaki, Toru; Kawamura, Kazunori; Ishiwata, Kiichi

    2004-01-01

    Fully quantitative analysis of the adenosine A 1 receptor (A1R) in the brain with 11 C-MPDX and positron emission tomography is reported. The kinetics is described using a two-tissue three-compartment model, and estimated binding potentials correspond well with the estimates made by Logan plot. The image of the binding potential of the MPDX is physiologically reasonable. We conclude that MPDX is applicable to the visualization of the A1Rs in the brain with Logan plot

  10. Adenosine A1, A2a, A2B, and A3 receptors in hematopoiesis. 2. Expression of receptor mRNA in resting and lipopolysaccharide-activated mouse RAW 264.7 macrophages

    Czech Academy of Sciences Publication Activity Database

    Štreitová, Denisa; Hofer, Michal; Holá, Jiřina; Vacek, Antonín; Pospíšil, Milan

    2010-01-01

    Roč. 59, č. 1 (2010), s. 139-144 ISSN 0862-8408 R&D Projects: GA ČR(CZ) GA305/06/0015; GA ČR(CZ) GA305/08/0158 Institutional research plan: CEZ:AV0Z50040507; CEZ:AV0Z50040702 Keywords : adenosine receptors * macrophage * mRNA expression Subject RIV: BO - Biophysics Impact factor: 1.646, year: 2010

  11. Adenosine and sleep

    International Nuclear Information System (INIS)

    Yanik, G.M. Jr.

    1987-01-01

    Behavioral and biochemical approaches have been used to determine the relative contribution of endogenous adenosine and adenosine receptors to the sleep-wake cycle in the rat. Adenosine concentrations in specific areas of the rat brain were not affected by 24 hours of total sleep deprivation, or by 24 or 48 hours of REM sleep deprivation. In order to assess the effect of REM sleep deprivation on adenosine A 1 receptors, 3 H-L-PIA binding was measured. The Bmax values for 3 H-L-PIA binding to membrane preparations of the cortices and corpus striata from 48 hour REM sleep-deprived animals were increased 14.8% and 23%, respectively. These increases were not maintained following the cessation of sleep deprivation and recovered within 2 hours. The results of a 96 hour REM deprivation experiment were similar to those of the 48 hour REM sleep deprivation experiment. However, these increases were not evident in similar structures taken from stress control animals, and conclusively demonstrated that the changes in 3 H-L-PIA binding resulted from REM sleep deprivation and not from stress

  12. Crystal structure of the adenosine A 2A receptor bound to an antagonist reveals a potential allosteric pocket

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Bingfa; Bachhawat, Priti; Chu, Matthew Ling-Hon; Wood, Martyn; Ceska, Tom; Sands, Zara A.; Mercier, Joel; Lebon, Florence; Kobilka, Tong Sun; Kobilka, Brian K. (Stanford-MED); (ConfometRx); (UCB Pharma)

    2017-02-06

    The adenosine A2A receptor (A2AR) has long been implicated in cardiovascular disorders. As more selective A2AR ligands are being identified, its roles in other disorders, such as Parkinson’s disease, are starting to emerge, and A2AR antagonists are important drug candidates for nondopaminergic anti-Parkinson treatment. Here we report the crystal structure of A2A receptor bound to compound 1 (Cmpd-1), a novel A2AR/N-methyl D-aspartate receptor subtype 2B (NR2B) dual antagonist and potential anti-Parkinson candidate compound, at 3.5 Å resolution. The A2A receptor with a cytochrome b562-RIL (BRIL) fusion (A2AR–BRIL) in the intracellular loop 3 (ICL3) was crystallized in detergent micelles using vapor-phase diffusion. Whereas A2AR–BRIL bound to the antagonist ZM241385 has previously been crystallized in lipidic cubic phase (LCP), structural differences in the Cmpd-1–bound A2AR–BRIL prevented formation of the lattice observed with the ZM241385–bound receptor. The crystals grew with a type II crystal lattice in contrast to the typical type I packing seen from membrane protein structures crystallized in LCP. Cmpd-1 binds in a position that overlaps with the native ligand adenosine, but its methoxyphenyl group extends to an exosite not previously observed in other A2AR structures. Structural analysis revealed that Cmpd-1 binding results in the unique conformations of two tyrosine residues, Tyr91.35 and Tyr2717.36, which are critical for the formation of the exosite. The structure reveals insights into antagonist binding that are not observed in other A2AR structures, highlighting flexibility in the binding pocket that may facilitate the development of A2AR-selective compounds for the treatment of Parkinson’s disease.

  13. The Combined Inhibitory Effect of the Adenosine A1 and Cannabinoid CB1 Receptors on cAMP Accumulation in the Hippocampus Is Additive and Independent of A1 Receptor Desensitization

    OpenAIRE

    Serpa, Andr?; Correia, Sara; Ribeiro, Joaquim A.; Sebasti?o, Ana M.; Cascalheira, Jos? F.

    2015-01-01

    Adenosine A1 and cannabinoid CB1 receptors are highly expressed in hippocampus where they trigger similar transduction pathways. We investigated how the combined acute activation of A1 and CB1 receptors modulates cAMP accumulation in rat hippocampal slices. The CB1 agonist WIN55212-2 (0.3?30??M) decreased forskolin-stimulated cAMP accumulation with an EC50 of 6.6 ? 2.7??M and an E max? of 31% ? 2%, whereas for the A1 agonist, N6-cyclopentyladenosine (CPA, 10?150?nM), an EC50 of 35 ? 19?nM, an...

  14. Adenosine Receptors as a Biological Pathway for the Anti-Inflammatory and Beneficial Effects of Low Frequency Low Energy Pulsed Electromagnetic Fields

    Directory of Open Access Journals (Sweden)

    Katia Varani

    2017-01-01

    Full Text Available Several studies explored the biological effects of low frequency low energy pulsed electromagnetic fields (PEMFs on human body reporting different functional changes. Much research activity has focused on the mechanisms of interaction between PEMFs and membrane receptors such as the involvement of adenosine receptors (ARs. In particular, PEMF exposure mediates a significant upregulation of A2A and A3ARs expressed in various cells or tissues involving a reduction in most of the proinflammatory cytokines. Of particular interest is the observation that PEMFs, acting as modulators of adenosine, are able to increase the functionality of the endogenous agonist. By reviewing the scientific literature on joint cells, a double role for PEMFs could be hypothesized in vitro by stimulating cell proliferation, colonization of the scaffold, and production of tissue matrix. Another effect could be obtained in vivo after surgical implantation of the construct by favoring the anabolic activities of the implanted cells and surrounding tissues and protecting the construct from the catabolic effects of the inflammatory status. Moreover, a protective involvement of PEMFs on hypoxia damage in neuron-like cells and an anti-inflammatory effect in microglial cells have suggested the hypothesis of a positive impact of this noninvasive biophysical stimulus.

  15. Andrographolide protects liver cells from H2O2 induced cell death by upregulation of Nrf-2/HO-1 mediated via adenosine A2a receptor signalling.

    Science.gov (United States)

    Mittal, Smriti P K; Khole, Swati; Jagadish, Nidhi; Ghosh, Debjani; Gadgil, Vijay; Sinkar, Vilas; Ghaskadbi, Saroj S

    2016-11-01

    Andrographolide, principle constituent of Andrographis paniculata Nees is used in traditional medicine in Southeast Asia and is known to exhibit various biological activities. Its antioxidant activity is due to its ability to activate one of the antioxidant enzymes, heme oxygenase-1 (HO-1) which is regulated transcriptionally through Nrf-2. However, molecular mechanism underlying activation of Nrf-2/HO-1 has not yet been clearly understood. Protective effect of andrographolide against H2O2 induced cell death, reactive oxygen species and lipid peroxidation was observed in HepG2 cells. Ability of andrographolide to modulate G-protein coupled receptor (GPCR) mediated signalling was determined using in silico docking and gene expression was analyzed by qRT-PCR, confocal microscopy and western blot analysis. We clearly show that andrographolide via adenosine A2A receptor signalling leads to activation of p38 MAP kinase, resulting in upregulation of Nrf-2, its translocation to nucleus and activation of HO-1. Additionally, it activates adenylate cyclase resulting in cAMP formation which in turn activates protein kinase A leading to inhibition of GSK-3β by phosphorylation. Inactivated GSK-3β leads to retention of Nrf-2 in the nucleus leading to sustained expression of HO-1 by binding to its antioxidant response element (ARE). Thus, andrographolide probably by binding to adenosine A2a receptor activates Nrf-2 transcription and also inhibits its exclusion from the nucleus by inactivating GSK-3β, together resulting in activation of HO-1. We speculate that andrographolide can be used as a therapeutic drug to combat oxidative stress implicated in pathogenesis of various diseases such as diabetes, osteoporosis, neurodegenerative diseases etc. Copyright © 2016 Elsevier B.V. All rights reserved.

  16. Caffeine and an adenosine A(2A) receptor antagonist prevent memory impairment and synaptotoxicity in adult rats triggered by a convulsive episode in early life.

    Science.gov (United States)

    Cognato, Giana P; Agostinho, Paula M; Hockemeyer, Jörg; Müller, Christa E; Souza, Diogo O; Cunha, Rodrigo A

    2010-01-01

    Seizures early in life cause long-term behavioral modifications, namely long-term memory deficits in experimental animals. Since caffeine and adenosine A(2A) receptor (A(2A)R) antagonists prevent memory deficits in adult animals, we now investigated if they also prevented the long-term memory deficits caused by a convulsive period early in life. Administration of kainate (KA, 2 mg/kg) to 7-days-old (P7) rats caused a single period of self-extinguishable convulsions which lead to a poorer memory performance in the Y-maze only when rats were older than 90 days, without modification of locomotion or anxiety-like behavior in the elevated-plus maze. In accordance with the relationship between synaptotoxicity and memory dysfunction, the hippocampus of these adult rats treated with kainate at P7 displayed a lower density of synaptic proteins such as SNAP-25 and syntaxin (but not synaptophysin), as well as vesicular glutamate transporters type 1 (but not vesicular GABA transporters), with no changes in PSD-95, NMDA receptor subunits (NR1, NR2A, NR2B) or alpha-amino-3-hydroxy-5-methylisoxazole-4-propionate receptor subunits (GluR1, GluR2) compared with controls. Caffeine (1 g/L) or the A(2A)R antagonist, KW6002 (3 mg/kg) applied in the drinking water from P21 onwards, prevented these memory deficits in P90 rats treated with KA at P7, as well as the accompanying synaptotoxicity. These results show that a single convulsive episode in early life causes a delayed memory deficit in adulthood accompanied by a glutamatergic synaptotoxicity that was prevented by caffeine or adenosine A(2A)R antagonists.

  17. Ex vivo lung perfusion with adenosine A2A receptor agonist allows prolonged cold preservation of lungs donated after cardiac death.

    Science.gov (United States)

    Wagner, Cynthia E; Pope, Nicolas H; Charles, Eric J; Huerter, Mary E; Sharma, Ashish K; Salmon, Morgan D; Carter, Benjamin T; Stoler, Mark H; Lau, Christine L; Laubach, Victor E; Kron, Irving L

    2016-02-01

    Ex vivo lung perfusion has been successful in the assessment of marginal donor lungs, including donation after cardiac death (DCD) donor lungs. Ex vivo lung perfusion also represents a unique platform for targeted drug delivery. We sought to determine whether ischemia-reperfusion injury would be decreased after transplantation of DCD donor lungs subjected to prolonged cold preservation and treated with an adenosine A2A receptor agonist during ex vivo lung perfusion. Porcine DCD donor lungs were preserved at 4°C for 12 hours and underwent ex vivo lung perfusion for 4 hours. Left lungs were then transplanted and reperfused for 4 hours. Three groups (n = 4/group) were randomized according to treatment with the adenosine A2A receptor agonist ATL-1223 or the dimethyl sulfoxide vehicle: Infusion of dimethyl sulfoxide during ex vivo lung perfusion and reperfusion (DMSO), infusion of ATL-1223 during ex vivo lung perfusion and dimethyl sulfoxide during reperfusion (ATL-E), and infusion of ATL-1223 during ex vivo lung perfusion and reperfusion (ATL-E/R). Final Pao2/Fio2 ratios (arterial oxygen partial pressure/fraction of inspired oxygen) were determined from samples obtained from the left superior and inferior pulmonary veins. Final Pao2/Fio2 ratios in the ATL-E/R group (430.1 ± 26.4 mm Hg) were similar to final Pao2/Fio2 ratios in the ATL-E group (413.6 ± 18.8 mm Hg), but both treated groups had significantly higher final Pao2/Fio2 ratios compared with the dimethyl sulfoxide group (84.8 ± 17.7 mm Hg). Low oxygenation gradients during ex vivo lung perfusion did not preclude superior oxygenation capacity during reperfusion. After prolonged cold preservation, treatment of DCD donor lungs with an adenosine A2A receptor agonist during ex vivo lung perfusion enabled Pao2/Fio2 ratios greater than 400 mm Hg after transplantation in a preclinical porcine model. Pulmonary function during ex vivo lung perfusion was not predictive of outcomes after transplantation. Copyright

  18. Changes of Cerebral and/or Peripheral Adenosine A₁ Receptor and IGF-I Concentrations under Extended Sleep Duration in Rats.

    Science.gov (United States)

    Chennaoui, Mounir; Arnal, Pierrick J; Dorey, Rodolphe; Sauvet, Fabien; Ciret, Sylvain; Gallopin, Thierry; Leger, Damien; Drogou, Catherine; Gomez-Merino, Danielle

    2017-11-17

    Extended sleep improves sustained attention and reduces sleep pressure in humans. Downregulation of adenosine A₁ receptor (A₁R) and modulation of the neurotrophic factor insulin growth factor-1 (IGF-I) in brain structures controlling attentional capacities could be involved. In the frontal cortex and hippocampus of rats, we measured adenosine A₁R and IGF-I protein concentrations after photoperiod-induced sleep extension. Two groups of twelve rats were adapted over 14 days to a habitual (CON) 12:12 light-dark (LD) schedule and an extended (EXT) 16:8 LD schedule. IGF-I content was also measured in plasma, liver, and skeletal muscle. In EXT, compared to CON rats, A₁R content in the frontal cortex was significantly lower ( p IGF-I content was higher ( p IGF-I content in plasma and muscle was higher ( p IGF-I levels. This photoperiod induced an anabolic profile with increased weight gain and circulating and muscular IGF-I levels. An extension of sleep duration might favor cerebral and peripheral anabolism, which may help attentional and physical capacities.

  19. Functional coupling between adenosine A1 receptors and G-proteins in rat and postmortem human brain membranes determined with conventional guanosine-5'-O-(3-[35S]thio)triphosphate ([35S]GTPγS) binding or [35S]GTPγS/immunoprecipitation assay.

    Science.gov (United States)

    Odagaki, Yuji; Kinoshita, Masakazu; Ota, Toshio; Meana, J Javier; Callado, Luis F; Matsuoka, Isao; García-Sevilla, Jesús A

    2018-06-01

    Adenosine signaling plays a complex role in multiple physiological processes in the brain, and its dysfunction has been implicated in pathophysiology of neuropsychiatric diseases such as schizophrenia and affective disorders. In the present study, the coupling between adenosine A 1 receptor and G-protein was assessed by means of two [ 35 S]GTPγS binding assays, i.e., conventional filtration method and [ 35 S]GTPγS binding/immunoprecipitation in rat and human brain membranes. The latter method provides information about adenosine A 1 receptor-mediated Gα i-3 activation in rat as well as human brain membranes. On the other hand, adenosine-stimulated [ 35 S]GTPγS binding determined with conventional assay derives from functional activation of Gα i/o proteins (not restricted only to Gα i-3 ) coupled to adenosine A 1 receptors. The determination of adenosine concentrations in the samples used in the present study indicates the possibility that the assay mixture under our experimental conditions contains residual endogenous adenosine at nanomolar concentrations, which was also suggested by the results on the effects of adenosine receptor antagonists on basal [ 35 S]GTPγS binding level. The effects of adenosine deaminase (ADA) on basal binding also support the presence of adenosine. Nevertheless, the varied patterns of ADA discouraged us from adding ADA into assay medium routinely. The concentration-dependent increases elicited by adenosine were determined in 40 subjects without any neuropsychiatric disorders. The increases in %E max values determined by conventional assay according to aging and postmortem delay should be taken into account in future studies focusing on the effects of psychiatric disorders on adenosine A 1 receptor/G-protein interaction in postmortem human brain tissue.

  20. Adenosine A{sub 1} receptors in human sleep regulation studied by electroencephalography (EEG) and positron emission tomography (PET)[Dissertation 17227

    Energy Technology Data Exchange (ETDEWEB)

    Geissler, E

    2007-07-01

    Sleep is an essential physiological process. However, the functions of sleep and the endogenous mechanisms involved in sleep regulation are only partially understood. Convergent lines of evidence support the hypothesis that the build-up of sleep propensity during wakefulness and its decline during sleep are associated with alterations in brain adenosine levels and adenosine receptor concentrations. The non-selective A{sub 1} and A{sub 2A} adenosine receptor antagonist caffeine stimulates alertness and is known to attenuate changes in the waking and sleep electroencephalogram (EEG) typically observed after prolonged waking. Several findings point to an important function of the adenosine A{sub 1} receptor (A{sub 1}AR) in the modulation of vigilance states. The A{sub 1}AR is densely expressed in brain regions involved in sleep regulation, and pharmacological manipulations affecting the A{sub 1}AR were shown to influence sleep propensity and sleep depth. However, an involvement of the A{sub 2A} adenosine receptor (A{sub 2A}AR) is also assumed. The distinct functions of the A{sub 1} and A{sub 2A} receptor subtypes in sleep-wake regulation and in mediating the effects of caffeine have not been identified so far. The selective adenosine A{sub 1} receptor antagonist, 8-cyclopentyl-3-(3-{sup 18}Ffluoropropyl)- 1-propylxanthine ({sup 18}F-CPFPX), offers the opportunity to get further insights into adenosinergic mechanisms by in vivo imaging of the A{sub 1}AR subtype with positron emission tomography (PET). The aim of this thesis was to elucidate the role of adenosine A{sub 1} receptors in human sleep regulation, combining {sup 18}F-CPFPX PET brain imaging and EEG recordings, the gold standard in sleep research. It was hypothesized that sleep deprivation would induce adenosine accumulation and/or changes in A{sub 1}AR density. Thus, the question was addressed whether these effects of prolonged wakefulness can be visualized by altered {sup 18}F-CPFPX binding. Moreover, it was

  1. Wheel running alters patterns of uncontrollable stress-induced cfos mRNA expression in rat dorsal striatum direct and indirect pathways: a possible role for plasticity in adenosine receptors

    Science.gov (United States)

    Clark, Peter J.; Ghasem, Parsa R.; Mika, Agnieszka; Day, Heidi E.; Herrera, Jonathan J.; Greenwood, Benjamin N.; Fleshner, Monika

    2014-01-01

    Emerging evidence indicates that adenosine is a major regulator of striatum activity, in part, through the antagonistic modulation of dopaminergic function. Exercise can influence adenosine and dopamine activity, which may subsequently promote plasticity in striatum adenosine and dopamine systems. Such changes could alter activity of medium spiny neurons and impact striatum function. The purpose of this study was two-fold. The first was to characterize the effect of long-term wheel running on adenosine 1 (A1R), adenosine 2A (A2AR), dopamine 1 (D1R), and dopamine 2 (D2R) receptor mRNA expression in adult rat dorsal and ventral striatum structures using in situ hybridization. The second was to determine if changes to adenosine and dopamine receptor mRNA from running are associated with altered cfos mRNA induction in dynorphin- (direct pathway) and enkephalin- (indirect pathway) expressing neurons of the dorsal striatum following stress exposure. We report that chronic running, as well as acute uncontrollable stress, reduced A1R and A2AR mRNA levels in the dorsal and ventral striatum. Running also modestly elevated D2R mRNA levels in striatum regions. Finally, stress-induced cfos was potentiated in dynorphin and attenuated in enkephalin expressing neurons of running rats. These data suggest striatum adenosine and dopamine systems are targets for neuroplasticity from exercise, which may contribute to changes in direct and indirect pathway activity. These findings may have implications for striatum mediated motor and cognitive processes, as well as exercise facilitated stress-resistance. PMID:25017571

  2. Tandem mass spectrometry, but not T-cell receptor excision circle analysis, identifies newborns with late-onset adenosine deaminase deficiency.

    Science.gov (United States)

    la Marca, Giancarlo; Canessa, Clementina; Giocaliere, Elisa; Romano, Francesca; Duse, Marzia; Malvagia, Sabrina; Lippi, Francesca; Funghini, Silvia; Bianchi, Leila; Della Bona, Maria Luisa; Valleriani, Claudia; Ombrone, Daniela; Moriondo, Maria; Villanelli, Fabio; Speckmann, Carsten; Adams, Stuart; Gaspar, Bobby H; Hershfield, Michael; Santisteban, Ines; Fairbanks, Lynette; Ragusa, Giovanni; Resti, Massimo; de Martino, Maurizio; Guerrini, Renzo; Azzari, Chiara

    2013-06-01

    Adenosine deaminase (ADA)-severe combined immunodeficiency (SCID) is caused by genetic variants that disrupt the function of ADA. In its early-onset form, it is rapidly fatal to infants. Delayed or late-onset ADA-SCID is characterized by insidious progressive immunodeficiency that leads to permanent organ damage or death. Quantification of T-cell receptor excision circles (TRECs) or tandem mass spectrometry (tandem-MS) analysis of dried blood spots (DBSs) collected at birth can identify newborns with early-onset ADA-SCID and are used in screening programs. However, it is not clear whether these analyses can identify newborns who will have delayed or late-onset ADA-SCID before symptoms appear. We performed a retrospective study to evaluate whether tandem-MS and quantitative TREC analyses of DBSs could identify newborns who had delayed-onset ADA-SCID later in life. We tested stored DBSs collected at birth from 3 patients with delayed-onset ADA-SCID using tandem-MS (PCT EP2010/070517) to evaluate levels of adenosine and 2'-deoxyadenosine and real-time PCR to quantify TREC levels. We also analyzed DBSs from 3 newborns with early-onset ADA-SCID and 2 healthy newborn carriers of ADA deficiency. The DBSs taken at birth from the 3 patients with delayed-onset ADA-SCID had adenosine levels of 10, 25, and 19 μmol/L (normal value, <1.5 μmol/L) and 2'-deoxyadenosine levels of 0.7, 2.7, and 2.4 μmol/L (normal value, <0.07 μmol/L); the mean levels of adenosine and 2'-deoxyadenosine were respectively 12.0- and 27.6-fold higher than normal values. DBSs taken at birth from all 3 patients with delayed-onset ADA deficiency had normal TREC levels, but TRECs were undetectable in blood samples taken from the same patients at the time of diagnosis. Tandem-MS but not TREC quantification identifies newborns with delayed- or late-onset ADA deficiency. Copyright © 2013 American Academy of Allergy, Asthma & Immunology. Published by Mosby, Inc. All rights reserved.

  3. Cross sectional PET study of cerebral adenosine A{sub 1} receptors in premanifest and manifest Huntington's disease

    Energy Technology Data Exchange (ETDEWEB)

    Matusch, Andreas; Elmenhorst, David [Institute of Neuroscience and Medicine (INM-2), Juelich (Germany); Saft, Carsten; Kraus, Peter H.; Gold, Ralf [St. Josef Hospital, Ruhr University Bochum, Department of Neurology, Huntington Centre NRW, Bochum (Germany); Hartung, Hans-Peter [Heinrich Heine University Duesseldorf, Department of Neurology, Medical Faculty, Duesseldorf (Germany); Bauer, Andreas [Institute of Neuroscience and Medicine (INM-2), Juelich (Germany); Heinrich Heine University Duesseldorf, Department of Neurology, Medical Faculty, Duesseldorf (Germany)

    2014-06-15

    To study cerebral adenosine receptors (AR) in premanifest and manifest stages of Huntington's disease (HD). We quantified the cerebral binding potential (BP{sub ND}) of the A{sub 1}AR in carriers of the HD CAG trinucleotide repeat expansion using the radioligand [{sup 18} F]CPFPX and PET. Four groups were investigated: (i) premanifest individuals far (preHD-A; n = 7) or (ii) near (preHD-B; n = 6) to the predicted symptom onset, (iii) manifest HD patients (n = 8), and (iv) controls (n = 36). Cerebral A{sub 1}AR values of preHD-A subjects were generally higher than those of controls (by up to 31 %, p <.01, in the thalamus on average). Across stages a successive reduction of A{sub 1}AR BP{sub ND} was observed to the levels of controls in preHD-B and undercutting controls in manifest HD by down to 25 %, p <.01, in the caudatus and amygdala. There was a strong correlation between A{sub 1}AR BP{sub ND} and years to onset. Before onset of HD, the assumed annual rates of change of A{sub 1}AR density were -1.2 % in the caudatus, -1.7 % in the thalamus and -3.4 % in the amygdala, while the corresponding volume losses amounted to 0.6 %, 0.1 % and 0.2 %, respectively. Adenosine receptors switch from supra to subnormal levels during phenoconversion of HD. This differential regulation may play a role in the pathophysiology of altered energy metabolism. (orig.)

  4. Adenosine AA Receptor Antagonists Do Not Disrupt Rodent Prepulse Inhibition: An Improved Side Effect Profile in the Treatment of Parkinson's Disease

    Directory of Open Access Journals (Sweden)

    Carina J. Bleickardt

    2012-01-01

    Full Text Available Parkinson's disease (PD is characterized by loss of dopaminergic neurons in the substantia nigra. Current treatments for PD focus on dopaminergic therapies, including L-dopa and dopamine receptor agonists. However, these treatments induce neuropsychiatric side effects. Psychosis, characterized by delusions and hallucinations, is one of the most serious such side effects. Adenosine A2A receptor antagonism is a nondopaminergic treatment for PD with clinical and preclinical efficacy. The present studies assessed A2A antagonists SCH 412348 and istradefylline in rodent prepulse inhibition (PPI, a model of psychosis. Dopamine receptor agonists pramipexole (0.3–3 mg/kg, pergolide (0.3–3 mg/kg, and apomorphine (0.3–3 mg/kg significantly disrupted PPI; ropinirole (1–30 mg/kg had no effect; L-dopa (100–300 mg/kg disrupted rat but not mouse PPI. SCH 412348 (0.3–3 mg/kg did not disrupt rodent PPI; istradefylline (0.1–1 mg/kg marginally disrupted mouse but not rat PPI. These results suggest that A2A antagonists, unlike dopamine agonists, have an improved neuropsychiatric side effect profile.

  5. A Non-imaging High Throughput Approach to Chemical Library Screening at the Unmodified Adenosine-A3 Receptor in Living Cells

    Directory of Open Access Journals (Sweden)

    Maria Augusta Arruda

    2017-12-01

    Full Text Available Recent advances in fluorescent ligand technology have enabled the study of G protein-coupled receptors in their native environment without the need for genetic modification such as addition of N-terminal fluorescent or bioluminescent tags. Here, we have used a non-imaging plate reader (PHERAstar FS to monitor the binding of fluorescent ligands to the human adenosine-A3 receptor (A3AR; CA200645 and AV039, stably expressed in CHO-K1 cells. To verify that this method was suitable for the study of other GPCRs, assays at the human adenosine-A1 receptor, and β1 and β2 adrenoceptors (β1AR and β2AR; BODIPY-TMR-CGP-12177 were also carried out. Affinity values determined for the binding of the fluorescent ligands CA200645 and AV039 to A3AR for a range of classical adenosine receptor antagonists were consistent with A3AR pharmacology and correlated well (R2 = 0.94 with equivalent data obtained using a confocal imaging plate reader (ImageXpress Ultra. The binding of BODIPY-TMR-CGP-12177 to the β1AR was potently inhibited by low concentrations of the β1-selective antagonist CGP 20712A (pKi 9.68 but not by the β2-selective antagonist ICI 118551(pKi 7.40. Furthermore, in experiments conducted in CHO K1 cells expressing the β2AR this affinity order was reversed with ICI 118551 showing the highest affinity (pKi 8.73 and CGP20712A (pKi 5.68 the lowest affinity. To determine whether the faster data acquisition of the non-imaging plate reader (~3 min per 96-well plate was suitable for high throughput screening (HTS, we screened the LOPAC library for inhibitors of the binding of CA200645 to the A3AR. From the initial 1,263 compounds evaluated, 67 hits (defined as those that inhibited the total binding of 25 nM CA200645 by ≥40% were identified. All compounds within the library that had medium to high affinity for the A3AR (pKi ≥6 were successfully identified. We found three novel compounds in the library that displayed unexpected sub-micromolar affinity

  6. Differential effects of presynaptic versus postsynaptic adenosine A2A receptor blockade on Δ9-tetrahydrocannabinol (THC) self-administration in squirrel monkeys.

    Science.gov (United States)

    Justinová, Zuzana; Redhi, Godfrey H; Goldberg, Steven R; Ferré, Sergi

    2014-05-07

    Different doses of an adenosine A2A receptor antagonist MSX-3 [3,7-dihydro-8-[(1E)-2-(3-ethoxyphenyl)ethenyl]-7 methyl-3-[3-(phosphooxy)propyl-1-(2 propynil)-1H-purine-2,6-dione] were found previously to either decrease or increase self-administration of cannabinoids delta-9-tetrahydrocannabinol (THC) or anandamide in squirrel monkeys. It was hypothesized that the decrease observed with a relatively low dose of MSX-3 was related to blockade of striatal presynaptic A2A receptors that modulate glutamatergic neurotransmission, whereas the increase observed with a higher dose was related to blockade of postsynaptic A2A receptors localized in striatopallidal neurons. This hypothesis was confirmed in the present study by testing the effects of the preferential presynaptic and postsynaptic A2A receptor antagonists SCH-442416 [2-(2-furanyl)-7-[3-(4-methoxyphenyl)propyl]-7H-pyrazolo[4,3-e][1,2,4]triazolo[1,5-c]pyrimidin-5-amine] and KW-6002 [(E)-1, 3-diethyl-8-(3,4-dimethoxystyryl)-7-methyl-3,7-dihydro-1H-purine-2,6-dione], respectively, in squirrel monkeys trained to intravenously self-administer THC. SCH-442416 produced a significant shift to the right of the THC self-administration dose-response curves, consistent with antagonism of the reinforcing effects of THC. Conversely, KW-6002 produced a significant shift to the left, consistent with potentiation of the reinforcing effects of THC. These results show that selectively blocking presynaptic A2A receptors could provide a new pharmacological approach to the treatment of marijuana dependence and underscore corticostriatal glutamatergic neurotransmission as a possible main mechanism involved in the rewarding effects of THC.

  7. Analgesic effect of paeoniflorin in rats with neonatal maternal separation-induced visceral hyperalgesia is mediated through adenosine A(1) receptor by inhibiting the extracellular signal-regulated protein kinase (ERK) pathway.

    Science.gov (United States)

    Zhang, Xiao-Jun; Chen, Hong-Li; Li, Zhi; Zhang, Hong-Qi; Xu, Hong-Xi; Sung, Joseph J Y; Bian, Zhao-Xiang

    2009-11-01

    Paeoniflorin (PF), a chief active ingredient in the root of Paeonia lactiflora Pall (family Ranunculaceae), is effective in relieving colorectal distention (CRD)-induced visceral pain in rats with visceral hyperalgesia induced by neonatal maternal separation (NMS). This study aimed at exploring the underlying mechanisms of PF's analgesic effect on CRD-evoked nociceptive signaling in the central nervous system (CNS) and investigating whether the adenosine A(1) receptor is involved in PF's anti-nociception. CRD-induced visceral pain as well as phosphorylated-extracellular signal-regulated protein kinase (p-ERK) and phospho-cAMP response element-binding protein (p-CREB) expression in the CNS structures of NMS rats were suppressed by NMDA receptor antagonist dizocilpine (MK-801) and ERK phosphorylation inhibitor U0126. PF could similarly inhibit CRD-evoked p-ERK and c-Fos expression in laminae I-II of the lumbosacral dorsal horn and anterior cingulate cortex (ACC). PF could also reverse the CRD-evoked increased glutamate concentration by CRD as shown by dynamic microdialysis monitoring in ACC, whereas, DPCPX, an antagonist of adenosine A(1) receptor, significantly blocked the analgesic effect of PF and PF's inhibition on CRD-induced p-ERK and p-CREB expression. These results suggest that PF's analgesic effect is possibly mediated by adenosine A(1) receptor by inhibiting CRD-evoked glutamate release and the NMDA receptor dependent ERK signaling.

  8. A Novel Antagonist of the Immune Checkpoint Protein Adenosine A2a Receptor Restores Tumor-Infiltrating Lymphocyte Activity in the Context of the Tumor Microenvironment

    Directory of Open Access Journals (Sweden)

    Melanie Mediavilla-Varela

    2017-07-01

    Full Text Available BACKGROUND: Therapeutic strategies targeting immune checkpoint proteins have led to significant responses in patients with various tumor types. The success of these studies has led to the development of various antibodies/inhibitors for the different checkpoint proteins involved in immune evasion of the tumor. Adenosine present in high concentrations in the tumor microenvironment activates the immune checkpoint adenosine A2a receptor (A2aR, leading to the suppression of antitumor responses. Inhibition of this checkpoint has the potential to enhance antitumor T-cell responsiveness. METHODS: We developed a novel A2aR antagonist (PBF-509 and tested its antitumor response in vitro, in a mouse model, and in non-small cell lung cancer patient samples. RESULTS: Our studies showed that PBF-509 is highly specific to the A2aR as well as inhibitory of A2aR function in an in vitro model. In a mouse model, we found that lung metastasis was decreased after treatment with PBF-509 compared with its control. Furthermore, freshly resected tumor-infiltrating lymphocytes from lung cancer patients showed increased A2aR expression in CD4+ cells and variable expression in CD8+ cells. Ex vivo studies showed an increased responsiveness of human tumor-infiltrating lymphocytes when PBF-509 was combined with anti-PD-1 or anti-PD-L1. CONCLUSIONS: Our studies demonstrate that inhibition of the A2aR using the novel inhibitor PBF-509 could lead to novel immunotherapeutic strategies in non-small cell lung cancer.

  9. Adenosine A1 receptor activation increases myocardial protein S-nitrosothiols and elicits protection from ischemia-reperfusion injury in male and female hearts.

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    Qin Shao

    Full Text Available Nitric oxide (NO plays an important role in cardioprotection, and recent work from our group and others has implicated protein S-nitrosylation (SNO as a critical component of NO-mediated protection in different models, including ischemic pre- and post-conditioning and sex-dependent cardioprotection. However, studies have yet to examine whether protein SNO levels are similarly increased with pharmacologic preconditioning in male and female hearts, and whether an increase in protein SNO levels, which is protective in male hearts, is sufficient to increase baseline protection in female hearts. Therefore, we pharmacologically preconditioned male and female hearts with the adenosine A1 receptor agonist N6-cyclohexyl adenosine (CHA. CHA administration prior to ischemia significantly improved functional recovery in both male and female hearts compared to baseline in a Langendorff-perfused heart model of ischemia-reperfusion injury (% of preischemic function ± SE: male baseline: 37.5±3.4% vs. male CHA: 55.3±3.2%; female baseline: 61.4±5.7% vs. female CHA: 76.0±6.2%. In a separate set of hearts, we found that CHA increased p-Akt and p-eNOS levels. We also used SNO-resin-assisted capture with LC-MS/MS to identify SNO proteins in male and female hearts, and determined that CHA perfusion induced a modest increase in protein SNO levels in both male (11.4% and female (12.3% hearts compared to baseline. These findings support a potential role for protein SNO in a model of pharmacologic preconditioning, and provide evidence to suggest that a modest increase in protein SNO levels is sufficient to protect both male and female hearts from ischemic injury. In addition, a number of the SNO proteins identified with CHA treatment were also observed with other forms of cardioprotective stimuli in prior studies, further supporting a role for protein SNO in cardioprotection.

  10. Effects of adenosine A2a receptor agonist and antagonist on cerebellar nuclear factor-kB expression preceded by MDMA toxicity.

    Science.gov (United States)

    Kermanian, Fatemeh; Soleimani, Mansoureh; Pourheydar, Bagher; Samzadeh-Kermani, Alireza; Mohammadzadeh, Farzaneh; Mehdizadeh, Mehdi

    2014-01-01

    Adenosine is an endogenous purine nucleoside that has a neuromodulatory role in the central nervous system. The amphetamine derivative (±)-3,4-methylenedioxymethamphetamine (MDMA or ecstasy) is a synthetic amphetamine analogue used recreationally to obtain an enhanced affiliated emotional response. MDMA is a potent monoaminergic neurotoxin with the potential of damage to brain neurons. The NF-kB family of proteins are ubiquitously expressed and are inducible transcription factors that regulate the expression of genes involved in disparate processes such as immunity and ingrowth, development and cell-death regulation. In this study we investigated the effects of the A2a adenosine receptor (A2a-R) agonist (CGS) and antagonist (SCH) on NF-kB expression after MDMA administration. Sixty three male Sprague-Dawley rats were injected to MDMA (10 and 20mg/kg) followed by intraperitoneal CGS (0.03 mg/kg) or SCH (0.03mg/kg) injection. The cerebellum were then removed forcresylviolet staining, western blot and RT- PCR analyses. MDMA significantly elevated NF-kB expression. Our results showed that MDMA increased the number of cerebellar dark neurons. We observed that administration of CGS following MDMA, significantly elevated the NF-kB expression both at mRNA and protein levels. By contrast, administration of the A2a-R antagonist SCH resulted in a decrease in the NF-kB levels. These results indicated that, co-administration of A2a agonist (CGS) can protect against MDMA neurotoxic effects by increasing NF-kB expression levels; suggesting a potential application for protection against the neurotoxic effects observed in MDMA users.

  11. Changes of Cerebral and/or Peripheral Adenosine A1 Receptor and IGF-I Concentrations under Extended Sleep Duration in Rats

    Directory of Open Access Journals (Sweden)

    Mounir Chennaoui

    2017-11-01

    Full Text Available Extended sleep improves sustained attention and reduces sleep pressure in humans. Downregulation of adenosine A1 receptor (A1R and modulation of the neurotrophic factor insulin growth factor-1 (IGF-I in brain structures controlling attentional capacities could be involved. In the frontal cortex and hippocampus of rats, we measured adenosine A1R and IGF-I protein concentrations after photoperiod-induced sleep extension. Two groups of twelve rats were adapted over 14 days to a habitual (CON 12:12 light–dark (LD schedule and an extended (EXT 16:8 LD schedule. IGF-I content was also measured in plasma, liver, and skeletal muscle. In EXT, compared to CON rats, A1R content in the frontal cortex was significantly lower (p < 0.05, while IGF-I content was higher (p < 0.001, and no significant change was observed in the hippocampus. IGF-I content in plasma and muscle was higher (p < 0.001 and p < 0.01, while it was lower in liver (p < 0.001. The absolute weight and weight gain were higher in EXT rats (p < 0.01. These data suggest that 14 days under a 16:8 LD photoperiod respectively down- and upregulated cortical A1R and IGF-I levels. This photoperiod induced an anabolic profile with increased weight gain and circulating and muscular IGF-I levels. An extension of sleep duration might favor cerebral and peripheral anabolism, which may help attentional and physical capacities.

  12. The effect of adenosine A(2A) receptor antagonists on hydroxyl radical, dopamine, and glutamate in the striatum of rats with altered function of VMAT2.

    Science.gov (United States)

    Gołembiowska, Krystyna; Dziubina, Anna

    2012-08-01

    It has been shown that a decreased vesicular monoamine transporter (VMAT2) function and the disruption of dopamine (DA) storage is an early contributor to oxidative damage of dopamine neurons in Parkinson's disease (PD). In our previous study, we demonstrated that adenosine A(2A) receptor antagonists suppressed oxidative stress in 6-hydroxydopamine-treated rats suggesting that this effect may account for neuroprotective properties of drugs. In the present study, rats were injected with reserpine (10 mg/kg sc) and 18 h later the effect of the adenosine A(2A) receptor antagonists 8-(3-chlorostyryl)caffeine (CSC) and 4-(2-[7-amino-2-(2-furyl)[1,2,4]triazolo[2,3-a][1,3,5]triazin-5-ylamino]ethyl)phenol (ZM 241385) on extracellular DA, glutamate and hydroxyl radical formation was studied in the rat striatum using in vivo microdialysis. By disrupting VMAT2 function, reserpine depleted DA stores, and increased glutamate and hydroxyl radical levels in the rat striatum. CSC (1 mg/kg) but not ZM 241385 (3 mg/kg) increased extracellular DA level and production of hydroxyl radical in reserpinised rats. Both antagonists decreased the reserpine-induced increase in extracellular glutamate. L-3,4-Dihydroxyphenylalanine (L-DOPA) (25 mg/kg) significantly enhanced extracellular DA, had no effect on reserpine-induced hydroxyl radical production and decreased extracellular glutamate concentration. CSC but not ZM 241385 given jointly with L-DOPA increased the effect of L-DOPA on extracellular DA and augmented the reserpine-induced hydroxyl radical production. CSC and ZM 241385 did not influence extracellular glutamate level, which was decreased by L-DOPA. It seems that by decreasing the MAO-dependent DA metabolism rate, CSC raised cytosolic DA and by DA autoxidation, it induced hydroxyl radical overproduction. Thus, the methylxanthine A(2A) receptor antagonists bearing properties of MAO-B inhibitor, like CSC, may cause a risk of oxidative stress resulting from dysfunctional DA storage

  13. Role of transglutaminase 2 in A1 adenosine receptor- and β2-adrenoceptor-mediated pharmacological pre- and post-conditioning against hypoxia-reoxygenation-induced cell death in H9c2 cells.

    Science.gov (United States)

    Vyas, Falguni S; Nelson, Carl P; Dickenson, John M

    2018-01-15

    Pharmacologically-induced pre- and post-conditioning represent attractive therapeutic strategies to reduce ischaemia/reperfusion injury during cardiac surgery and following myocardial infarction. We have previously reported that transglutaminase 2 (TG2) activity is modulated by the A 1 adenosine receptor and β 2 -adrenoceptor in H9c2 cardiomyoblasts. The primary aim of this study was to determine the role of TG2 in A 1 adenosine receptor and β 2 -adrenoceptor-induced pharmacological pre- and post-conditioning in the H9c2 cells. H9c2 cells were exposed to 8h hypoxia (1% O 2 ) followed by 18h reoxygenation, after which cell viability was assessed by monitoring mitochondrial reduction of MTT, lactate dehydrogenase release and caspase-3 activation. N 6 -cyclopentyladenosine (CPA; A 1 adenosine receptor agonist), formoterol (β 2 -adrenoceptor agonist) or isoprenaline (non-selective β-adrenoceptor agonist) were added before hypoxia/reoxygenation (pre-conditioning) or at the start of reoxygenation following hypoxia (post-conditioning). Pharmacological pre- and post-conditioning with CPA and isoprenaline significantly reduced hypoxia/reoxygenation-induced cell death. In contrast, formoterol did not elicit protection. Pre-treatment with pertussis toxin (G i/o -protein inhibitor), DPCPX (A 1 adenosine receptor antagonist) or TG2 inhibitors (Z-DON and R283) attenuated the A 1 adenosine receptor-induced pharmacological pre- and post-conditioning. Similarly, pertussis toxin, ICI 118,551 (β 2 -adrenoceptor antagonist) or TG2 inhibition attenuated the isoprenaline-induced cell survival. Knockdown of TG2 using small interfering RNA (siRNA) attenuated CPA and isoprenaline-induced pharmacological pre- and post-conditioning. Finally, proteomic analysis following isoprenaline treatment identified known (e.g. protein S100-A6) and novel (e.g. adenine phosphoribosyltransferase) protein substrates for TG2. These results have shown that A 1 adenosine receptor and β 2 -adrenoceptor

  14. New generic approach to the treatment of organophosphate poisoning : Adenosine receptor mediated inhibition of ACh-release

    NARCIS (Netherlands)

    van Helden, HPM; Moor, E; Westerink, BHC; Bruijnzeel, PLB

    1998-01-01

    Current treatment of acute organophosphate (OP) poisoning includes a combined administration of a cholinesterase reactivator (oxime), a muscarinic receptor antagonist (atropine) and an anticonvulsant (diazepam). This treatment is not adequate since it does not prevent neuronal brain damage and

  15. New generic approach to the treatment of organophosphate poisoning: Adenosine receptor mediated inhibition of ACh-release

    NARCIS (Netherlands)

    Helden, H.P.M. van; Groen, B.; Moor, E.; Westerink, B.H.C.; Bruijnzeel, P.L.B.

    1998-01-01

    Current treatment of acute organophosphate (OP) poisoning includes a combined administration of a cholinesterase reactivator (oxime), a muscarinic receptor antagonist (atropine) and an anticonvulsant (diazepam). This treatment is not adequate since it does not prevent neuronal brain damage and

  16. Effects of Long-Term Caffeine Consumption on the Adenosine A1 Receptor in the Rat Brain: an In Vivo PET Study with [18F]CPFPX.

    Science.gov (United States)

    Nabbi-Schroeter, Danje; Elmenhorst, David; Oskamp, Angela; Laskowski, Stefanie; Bauer, Andreas; Kroll, Tina

    2018-04-01

    Caffeine, a nonselective antagonist of adenosine receptors, is the most popular psychostimulant worldwide. Recently, a protective role of moderate chronic caffeine consumption against neurodegenerative diseases such as Alzheimer's and Parkinson's disease has been discussed. Thus, aim of the present study was an in vivo investigation of effects of long-term caffeine consumption on the adenosine A 1 receptor (A 1 AR) in the rat brain. Sixteen adult, male rats underwent five positron emission tomography (PET) scans with the highly selective A 1 AR radioligand [ 18 F]CPFPX in order to determine A 1 AR availability. After the first baseline PET scan, the animals were assigned to two groups: Caffeine treatment and control group. The caffeine-treated animals received caffeinated tap water (30 mg/kg bodyweight/day, corresponding to 4-5 cups of coffee per day in humans) for 12 weeks. Subsequently, caffeine was withdrawn and repeated PET measurements were performed on day 1, 2, 4, and 7 of caffeine withdrawal. The control animals were measured according to the same time schedule. At day 1, after 4.4 h of caffeine withdrawal, a significant decrease (- 34.5%, p < 0.001) of whole brain A 1 AR availability was observed. Unlike all other investigated brain regions in caffeine-treated rats, the hypothalamus and nucleus accumbens showed no significant intraindividual differences between baseline and first withdrawal PET scan. After approximately 27 h of caffeine withdrawal, the region- and group-specific effects disappeared and A 1 AR availability settled around baseline. The present study provides evidence that chronic caffeine consumption does not lead to persistent changes in functional availability of cerebral A 1 ARs which have previously been associated with neuroprotective effects of caffeine. The acute and region-specific decrease in cerebral A 1 AR availability directly after caffeine withdrawal is most likely caused by residual amounts of caffeine metabolites

  17. Characterization of the pharmacokinetics, brain distribution, and therapeutic efficacy of the adenosine A1 receptor partial agonist 2'-deoxy-N6-cyclopentyladenosine in sarin-poisoned rats

    International Nuclear Information System (INIS)

    Bueters, Tjerk J.H.; IJzerman, Ad P.; Helden, Herman P.M. van; Danhof, Meindert

    2003-01-01

    Characterization of the pharmacokinetics, brain distribution, and therapeutic efficacy of the adenosine A 1 receptor partial agonist 2'-deoxy-N 6 -cyclopentyladenosine in sarin-poisoned rats. Bueters, T.J.H., IJzerman, A.P., Van Helden, H.P.M., and Danhof, M. (2003). The objective of the present study was to determine (1) the influence of sarin poisoning (144 μg/kg sc) on the pharmacokinetics and brain distribution of the adenosine A 1 receptor partial agonist 2'-deoxy-N 6 -cyclopentyladenosine (2'dCPA), and (2) the effect of 2'dCPA (20 mg/kg iv) on the central acetylcholine (ACh) release and protection against sarin toxicity. A five-compartment model successfully described the pharmacokinetic profile of 2'dCPA in blood and brain microdialysate. A covariate analysis revealed that the volume of distribution of 2'dCPA in blood was different in sarin-poisoned rats, 177 ± 7 versus 148 ± 8 ml in control rats. However, the transport of 2'dCPA from blood to the brain was unaffected as reflected by the values of the intercompartmental transport clearances, 0.21 ± 0.02 and 0.21 ± 0.04 μl/min in control and sarin-poisoned rats, respectively. Also the area-under-curve (AUC) ratios of brain microdialysate and blood were identical with values of 0.02 ± 0.001 and 0.02 ± 0.002, respectively, demonstrating the restricted transport of 2'dCPA into the brain in both treatment groups. Treatment of sarin-poisoned rats by 2'dCPA did not adequately prevent the accumulation of ACh in the central nervous system. 2'dCPA delayed the emergence of concomitant symptoms compared to untreated rats, but eventually only 29% of the animals survived 24 h. In conclusion, the pharmacokinetic profile of 2'dCPA in blood was slightly changed by sarin, but not the distribution of 2'dCPA into the brain. The therapeutic efficacy of 2'dCPA against sarin was limited, presumably due to insufficient quantities of 2'dCPA reaching the brain

  18. Effects of ethanolic extract and naphthoquinones obtained from the bulbs of Cipura paludosa on short-term and long-term memory: involvement of adenosine A₁ and A₂A receptors.

    Science.gov (United States)

    Lucena, Greice M R S; Matheus, Filipe C; Ferreira, Vania M; Tessele, Priscila B; Azevedo, Mariangela S; Cechinel-Filho, Valdir; Prediger, Rui D

    2013-04-01

    Previous studies from our group have indicated important biological properties of the ethanolic extract and isolated compounds from the bulbs of Cipura paludosa (Iridaceae), a native plant widely distributed in northern Brazil, including antioxidant, neuroprotective and anti-nociceptive activities. In the present study, the effects of the ethanolic extract and its two naphthoquinones (eleutherine and isoeleutherine) on the short- and long-term memory of adult rodents were assessed in social recognition and inhibitory avoidance tasks. Acute pre-training oral administration of the ethanolic extract improved the short-term social memory in rats as well as facilitated the step-down inhibitory avoidance short- and long-term memory in mice. Moreover, the co-administration of 'non-effective' doses of the extract of Cipura paludosa and the adenosine receptor antagonists caffeine (non-selective), DPCPX (adenosine A1 receptor antagonist) and ZM241385 (adenosine A2A receptor antagonist) improved the social recognition memory of rats. In the inhibitory avoidance task, the co-administration of sub-effective doses of the extract with caffeine or ZM241385, but not with DPCPX, improved the short- and long-term memory of mice. Finally, the acute oral administration of eleutherine and isoeleutherine facilitated the inhibitory avoidance short- and long-term memory in mice. These results demonstrate for the first time the cognitive-enhancing properties of the extract and isolated compounds from the bulbs of Cipura paludosa in rodents and suggest a possible involvement of adenosine A1 and A2A receptors in these effects. © 2012 The Authors Basic & Clinical Pharmacology & Toxicology © 2012 Nordic Pharmacological Society.

  19. Effect of fluoxetine and adenosine receptor NECA agonist on G alpha q/11 protein of C6 glioma cells

    Czech Academy of Sciences Publication Activity Database

    Kovářů, H.; Kovářů, F.; Lisá, Věra

    2012-01-01

    Roč. 33, č. 6 (2012), s. 614-618 ISSN 0172-780X Institutional support: RVO:67985823 Keywords : C6 glioma cells * SSRI antidepressant * G alpha q/11 signalling * G protein coupled receptor Subject RIV: ED - Physiology Impact factor: 0.932, year: 2012

  20. Pharmacological Blockade of Adenosine A2A but Not A1 Receptors Enhances Goal-Directed Valuation in Satiety-Based Instrumental Behavior

    Directory of Open Access Journals (Sweden)

    Yan Li

    2018-04-01

    Full Text Available The balance and smooth shift between flexible, goal-directed behaviors and repetitive, habitual actions are critical to optimal performance of behavioral tasks. The striatum plays an essential role in control of goal-directed versus habitual behaviors through a rich interplay of the numerous neurotransmitters and neuromodulators to modify the input, processing and output functions of the striatum. The adenosine receptors (namely A2AR and A1R, with their high expression pattern in the striatum and abilities to interact and integrate dopamine, glutamate and cannabinoid signals in the striatum, may represent novel therapeutic targets for modulating instrumental behavior. In this study, we examined the effects of pharmacological blockade of the A2ARs and A1Rs on goal-directed versus habitual behaviors in different information processing phases of instrumental learning using a satiety-based instrumental behavior procedure. We found that A2AR antagonist acts at the coding, consolidation and expression phases of instrumental learning to modulate animals’ sensitivity to goal-directed valuation without modifying action-outcome contingency. However, pharmacological blockade and genetic knockout of A1Rs did not affect acquisition or sensitivity to goal-valuation of instrumental behavior. These findings provide pharmacological evidence for a potential therapeutic strategy to control abnormal instrumental behaviors associated with drug addiction and obsessive-compulsive disorder by targeting the A2AR.

  1. When cytokinin, a plant hormone, meets the adenosine A2A receptor: a novel neuroprotectant and lead for treating neurodegenerative disorders?

    Directory of Open Access Journals (Sweden)

    Yi-Chao Lee

    Full Text Available It is well known that cytokinins are a class of phytohormones that promote cell division in plant roots and shoots. However, their targets, biological functions, and implications in mammalian systems have rarely been examined. In this study, we show that one cytokinin, zeatin riboside, can prevent pheochromocytoma (PC12 cells from serum deprivation-induced apoptosis by acting on the adenosine A(2A receptor (A(2A-R, which was blocked by an A(2A-R antagonist and a protein kinase A (PKA inhibitor, demonstrating the functional ability of zeatin riboside by mediating through A(2A-R signaling event. Since the A(2A-R was implicated as a therapeutic target in treating Huntington's disease (HD, a cellular model of HD was applied by transfecting mutant huntingtin in PC12 cells. By using filter retardation assay and confocal microscopy we found that zeatin riboside reversed mutant huntingtin (Htt-induced protein aggregations and proteasome deactivation through A(2A-R signaling. PKA inhibitor blocked zeatin riboside-induced suppression of mutant Htt aggregations. In addition, PKA activated proteasome activity and reduced mutant Htt protein aggregations. However, a proteasome inhibitor blocked both zeatin riboside-and PKA activator-mediated suppression of mutant Htt aggregations, confirming mediation of the A(2A-R/PKA/proteasome pathway. Taken together, zeatin riboside might have therapeutic potential as a novel neuroprotectant and a lead for treating neurodegenerative disorders.

  2. Synergistic interaction between a PDE5 inhibitor (sildenafil) and a new adenosine A2A receptor agonist (LASSBio-1359) improves pulmonary hypertension in rats.

    Science.gov (United States)

    Alencar, Allan K; Carvalho, Fábio I; Silva, Ananssa M; Martinez, Sabrina T; Calasans-Maia, Jorge A; Fraga, Carlos M; Barreiro, Eliezer J; Zapata-Sudo, Gisele; Sudo, Roberto T

    2018-01-01

    Pulmonary hypertension (PH) is characterized by enhanced pulmonary vascular resistance, which causes right ventricle (RV) pressure overload and results in right sided heart failure and death. This work investigated the effectiveness of a combined therapy with PDE5 inhibitor (PDE5i) and a new adenosine A2A receptor (A2AR) agonist in mitigating monocrotaline (MCT) induced PH in rats. An in vitro isobolographic analysis was performed to identify possible synergistic relaxation effect between sildenafil and LASSBio 1359 in rat pulmonary arteries (PAs). In the in vivo experiments, PH was induced in male Wistar rats by a single intraperitoneal injection of 60 mg/kg MCT. Rats were divided into the following groups: control (saline injection only), MCT + vehicle, MCT + sildenafil, MCT + LASSBio 1359 and MCT + combination of sildenafil and LASSBio 1359. Fourteen days after the MCT injection, rats were treated daily with oral administration of the regimen therapies or vehicle for 14 days. Cardiopulmonary system function and structure were evaluated by echocardiography. RV systolic pressure and PA endothelial function were measured. Isobolographic analysis showed a synergistic interaction between sildenafil and LASSBio 1359 in rat PAs. Combined therapy with sildenafil and LASSBio 1359 but not monotreatment with low dosages of either sildenafil or LASSBio 1359 ameliorated all of PH related abnormalities in cardiopulmonary function and structure in MCT challenged rats. The combination of sildenafil and LASSBio 1359 has a synergistic interaction, suggesting that combined use of these pharmacological targets may be an alternative to improve quality of life and outcomes for PH patients.

  3. Preparation and first evaluation of [{sup 18}F]FE-SUPPY: a new PET tracer for the adenosine A{sub 3} receptor

    Energy Technology Data Exchange (ETDEWEB)

    Wadsak, Wolfgang [Dept. of Nuclear Medicine, Medical Univ. of Vienna, A-1090 Vienna (Austria)]|[Dept. of Inorganic Chemistry, Univ. of Vienna, A-1090 Vienna (Austria); Mien, Leonhard-Key [Dept. of Nuclear Medicine, Medical Univ. of Vienna, A-1090 Vienna (Austria)]|[Dept. of Pharmaceutical Technology and Biopharmaceutics, Univ. of Vienna, A-1090 Vienna (Austria)]|[Dept. of Psychiatry and Psychotherapy, Medical Univ. of Vienna, A-1090 Vienna (Austria); Shanab, Karem [Dept. of Drug and Natural Product Synthesis, Faculty of Life Sciences, Univ. of Vienna, A-1090 Vienna (Austria); Ettlinger, Dagmar E. [Dept. of Nuclear Medicine, Medical Univ. of Vienna, A-1090 Vienna (Austria); Haeusler, Daniela [Dept. of Nuclear Medicine, Medical Univ. of Vienna, A-1090 Vienna (Austria)]|[Dept. of Pharmaceutical Technology and Biopharmaceutics, Univ. of Vienna, A-1090 Vienna (Austria); Sindelar, Karoline [Dept. of Nuclear Medicine, Medical Univ. of Vienna, A-1090 Vienna (Austria); Lanzenberger, Rupert R. [Dept. of Psychiatry and Psychotherapy, Medical Univ. of Vienna, A-1090 Vienna (Austria); Spreitzer, Helmut [Dept. of Drug and Natural Product Synthesis, Faculty of Life Sciences, Univ. of Vienna, A-1090 Vienna (Austria); Viernstein, Helmut [Dept. of Pharmaceutical Technology and Biopharmaceutics, Univ. of Vienna, A-1090 Vienna (Austria); Keppler, Bernhard K. [Dept. of Inorganic Chemistry, Univ. of Vienna, A-1090 Vienna (Austria); Dudczak, Robert; Kletter, Kurt [Dept. of Nuclear Medicine, Medical Univ. of Vienna, A-1090 Vienna (Austria); Mitterhauser, Markus [Dept. of Nuclear Medicine, Medical Univ. of Vienna, A-1090 Vienna (Austria)]|[Dept. of Pharmaceutical Technology and Biopharmaceutics, Univ. of Vienna, A-1090 Vienna (Austria)]|[Hospital Pharmacy of the General Hospital of Vienna, A-1090 Vienna (Austria)], E-mail: markus.mitterhouser@meduniwien.ac.at

    2008-01-15

    Introduction: Changes of the adenosine A{sub 3} receptor subtype (A3AR) expression have been shown in a variety of pathologies, especially neurological and affective disorders, cardiac diseases and oncological and inflammation processes. Recently, 5-(2-fluoroethyl) 2,4-diethyl-3-(ethylsulfanylcarbonyl)-6-phenylpyridine-5-carboxylate (FE-SUPPY) was presented as a high-affinity ligand for the A3AR with good selectivity. Our aims were the development of a suitable labeling precursor, the establishment of a reliable radiosynthesis for the fluorine-18-labeled analogue [{sup 18}F]FE-SUPPY and a first evaluation of [{sup 18}F]FE-SUPPY in rats. Methods: [{sup 18}F]FE-SUPPY was prepared in a feasible and reliable manner by radiofluorination of the corresponding tosylated precursor. Biodistribution was carried out in rats, and organs were removed and counted. Autoradiography was performed on rat brain slices in the presence or absence of 2-Cl-IB-MECA. Results: Overall yields and radiochemical purity were sufficient for further preclinical and clinical applications. The uptake pattern of [{sup 18}F]FE-SUPPY found in rats mainly followed the described mRNA distribution pattern of the A3AR. Specific uptake in brain was demonstrated by blocking with a selective A3AR agonist. Conclusion: We conclude that [{sup 18}F]FE-SUPPY has the potential to serve as the first positron emission tomography tracer for the A3AR.

  4. Adenosine A2A Receptors Mediate Anti-Inflammatory Effects of Electroacupuncture on Synovitis in Mice with Collagen-Induced Arthritis

    Directory of Open Access Journals (Sweden)

    Qi-hui Li

    2015-01-01

    Full Text Available To study the role of adenosine A2A receptor (A2AR in mediating the anti-inflammatory effect of electroacupuncture (EA on synovitis in collagen-induced arthritis (CIA, C57BL/6 mice were divided into five treatment groups: Sham-control, CIA-control, CIA-EA, CIA-SCH58261 (A2AR antagonist, and CIA-EA-SCH58261. All mice except those in the Sham-control group were immunized with collagen II for arthritis induction. EA treatment was administered using the stomach 36 and spleen 6 points, and stimulated with a continuous rectangular wave for 30 min daily. EA treatment and SCH58261 were administered daily from days 35 to 49 (n=10. After treatment, X-ray radiography of joint bone morphology was established at day 60 and mouse blood was collected for ELISA determination of tumor necrosis factor alpha (TNF-α levels. Mice were sacrificed and processed for histological examination of pathological changes of joint tissue, including hematoxylin-eosin staining and immunohistochemistry of A2AR expression. EA treatment resulted in significantly reduced pathological scores, TNF-α concentrations, and bone damage X-ray scores. Importantly, the anti-inflammatory and tissue-protective effect of EA treatment was reversed by coadministration of SCH58261. Thus, EA treatment exerts an anti-inflammatory effect resulting in significant protection of cartilage by activation of A2AR in the synovial tissue of CIA.

  5. Insulin and adenosine regulate the phosphatidylcholine concentration in isolated rat adipocyte plasma membranes.

    Science.gov (United States)

    Kiechle, F L; Sykes, E; Artiss, J D

    1995-01-01

    Blockade of adenosine receptors by 3-isobutyl-1-methylxanthine or degradation of endogenous adenosine with adenosine deaminase increased the phosphatidylcholine concentration in isolated rat adipocyte plasma membranes, an effect which was suppressed by the phosphatidylethanolamine methyltransferase inhibitor, S-adenosyl-L-homocysteine, and reversed by the adenosine analogue, N6-(L-phenylisopropyl)-adenosine. For example, the addition of N6-(L-phenylisopropyl)-adenosine to adenosine deaminase pretreated plasma membranes rapidly lowered the concentration of phosphatidylcholine by 171 nmol/mg at 30 seconds compared to control. Insulin-induced stimulation of phospholipid methylation in membranes treated with 3-isobutyl-1-methylxanthine or adenosine deaminase was achieved only after the addition of N6-(L-phenylisopropyl)-adenosine. These results suggest that adenosine receptor occupancy inhibits phospholipid methylation, is required for insulin stimulation of phospholipid methylation, and may perhaps activate a phosphatidylcholine-specific phospholipase C or phospholipase D.

  6. Colonic motor dysfunctions in a mouse model of high-fat diet-induced obesity: an involvement of A2B adenosine receptors.

    Science.gov (United States)

    Antonioli, Luca; Pellegrini, Carolina; Fornai, Matteo; Tirotta, Erika; Gentile, Daniela; Benvenuti, Laura; Giron, Maria Cecilia; Caputi, Valentina; Marsilio, Ilaria; Orso, Genny; Bernardini, Nunzia; Segnani, Cristina; Ippolito, Chiara; Csóka, Balázs; Németh, Zoltán H; Haskó, György; Scarpignato, Carmelo; Blandizzi, Corrado; Colucci, Rocchina

    2017-12-01

    Adenosine A 2B receptors (A 2B R) regulate several enteric functions. However, their implication in the pathophysiology of intestinal dysmotility associated with high-fat diet (HFD)-induced obesity has not been elucidated. We investigated the expression of A 2B R in mouse colon and their role in the mechanisms underlying the development of enteric dysmotility associated with obesity. Wild-type C57BL/6J mice were fed with HFD (60% kcal from fat) or normocaloric diet (NCD; 18% kcal from fat) for 8 weeks. Colonic A 2B R localization was examined by immunofluorescence. The role of A 2B R in the control of colonic motility was examined in functional experiments on longitudinal muscle preparations (LMPs). In NCD mice, A 2B R were predominantly located in myenteric neurons; in HFD animals, their expression increased throughout the neuromuscular layer. Functionally, the A 2B R antagonist MRS1754 enhanced electrically induced NK 1 -mediated tachykininergic contractions in LMPs from HFD mice, while it was less effective in tissues from NCD mice. The A 2B receptor agonist BAY 60-6583 decreased colonic tachykininergic contractions in LMPs, with higher efficacy in preparations from obese mice. Both A 2B R ligands did not affect contractions elicited by exogenous substance P. Obesity is related with a condition of colonic inflammation, leading to an increase of A 2B R expression. A 2B R, modulating the activity of excitatory tachykininergic nerves, participate to the enteric dysmotility associated with obesity.

  7. Blockade of A2b Adenosine Receptor Reduces Tumor Growth and Immune Suppression Mediated by Myeloid-Derived Suppressor Cells in a Mouse Model of Melanoma

    Directory of Open Access Journals (Sweden)

    Raffaella Iannone

    2013-12-01

    Full Text Available The A2b receptor (A2bR belongs to the adenosine receptor family. Emerging evidence suggest that A2bR is implicated in tumor progression in some murine tumor models, but the therapeutic potential of targeting A2bR in melanoma has not been examined. This study first shows that melanoma-bearing mice treated with Bay 60-6583, a selective A2bR agonist, had increased melanoma growth. This effect was associated with higher levels of immune regulatory mediators interleukin-10 (IL-10 and monocyte chemoattractant protein 1 (MCP-1 and accumulation of tumor-associated CD11b positive Gr1 positive cells (CD11b+Gr1+ myeloid-derived suppressor cells (MDSCs. Depletion of CD11b+Gr1+ cells completely reversed the protumor activity of Bay 60-6583. Conversely, pharmacological blockade of A2bR with PSB1115 reversed immune suppression in the tumor microenvironment, leading to a significant melanoma growth delay. PSB1115 treatment reduced both levels of IL-10 and MCP-1 and CD11b+Gr1+ cell number in melanoma lesions. These effects were associated with higher frequency of tumor-infiltrating CD8 positive (CD8+ T cells and natural killer T (NKT cells and increased levels of T helper 1 (Th1-like cytokines. Adoptive transfer of CD11b+Gr1+ cells abrogated the antitumor activity of PSB1115. These data suggest that the antitumor activity of PSB1115 relies on its ability to lower accumulation of tumor-infiltrating MDSCs and restore an efficient antitumor T cell response. The antitumor effect of PSB1115 was not observed in melanoma-bearing nude mice. Furthermore, PSB1115 enhanced the antitumor efficacy of dacarbazine. These data indicate that A2bR antagonists such as PSB1115 should be investigated as adjuvants in the treatment of melanoma.

  8. Detection of Heteromers Formed by Cannabinoid CB1, Dopamine D2, and Adenosine A2A G-Protein-Coupled Receptors by Combining Bimolecular Fluorescence Complementation and Bioluminescence Energy Transfer

    Science.gov (United States)

    Navarro, Gemma; Carriba, Paulina; Gandí, Jorge; Ciruela, Francisco; Casadó, Vicent; Cortés, Antoni; Mallol, Josefa; Canela, Enric I.; Lluis, Carmen; Franco, Rafael

    2008-01-01

    Functional interactions in signaling occur between dopamine D2 (D2R) and cannabinoid CB1 (CB1R) receptors, between CB1R and adenosine A2A (A2AR) receptors, and between D2R and A2AR. Furthermore, direct molecular interactions have been reported for the pairs CB1R-D2R, A2AR-D2R, and CB1R-A2AR. Here a combination of bimolecular fluorescence complementation and bioluminescence energy transfer techniques was used to identify the occurrence of D2R-CB1R-A2AR hetero-oligomers in living cells. PMID:18956124

  9. Detection of Heteromers Formed by Cannabinoid CB1, Dopamine D2, and Adenosine A2A G-Protein-Coupled Receptors by Combining Bimolecular Fluorescence Complementation and Bioluminescence Energy Transfer

    Directory of Open Access Journals (Sweden)

    Gemma Navarro

    2008-01-01

    Full Text Available Functional interactions in signaling occur between dopamine D2 (D2R and cannabinoid CB1 (CB1R receptors, between CB1R and adenosine A2A (A2AR receptors, and between D2R and A2AR. Furthermore, direct molecular interactions have been reported for the pairs CB1R-D2R, A2AR-D2R, and CB1R-A2AR. Here a combination of bimolecular fluorescence complementation and bioluminescence energy transfer techniques was used to identify the occurrence of D2R-CB1R-A2AR hetero-oligomers in living cells.

  10. Regulation of cessation of respiration and killing by cyclic 3',5'-adenosine monophosphate and its receptor protein after far-ultraviolet irradiation of Escherichia coli

    International Nuclear Information System (INIS)

    Swenson, P.A.; Schenley, R.L.; Joshi, J.G.

    1978-01-01

    When Escherichia coli B/r cultures are irradiated with ultraviolet light (UV) (254 nm), those cells that are killed stop respiring by 60 min after irradiation. Post-UV treatment with cyclic adenosine 3',5'-adenosine monophosphate (cAMP) causes more cells to stop respiring and to die. We have studied these effects at a UV fluence of 52 I/m 2 in a a wild-type E. coli K 12 strain and in mutants defective in cAMP metabolism. Strain CA 8,000 has crp + and cya + genes for the cAMP receptor protein (CRP) (required for transcription of operons regulated by cAMP) and for adenylate cyclase, respectively; CA 7901 is crp - ; and CA 8306 is a cya deletion (Δ). The wild-type culture showed a small transient cessation of respiration, and addition of cAMP caused cessation to be nearly complete. The crp - culture showed no evidence of cessation of respiration, and cAMP had no effect. The Δ cya mutant also showed no cessation of respiration, but cAMP (5 mM) caused as complete inhibition as in the wild type. cAMP caused a 10-fold loss in viability of UV-irradiated wild-type and Δ cya liquid cultures but had no effect on the cpr - culture. Respiration and viability changes were also studied in a double mutant, CA8404 Δ cya crp*, which has an altered CRP that is, with respect to the lac operon, independent of cAMP. The respiration response to UV was similar to that of the wild-type culture, and both respiration and viability of cells in liquid culture were sensitive to cAMP. The survival data, obtained by plating immediately after irradiation, show the wild type, Δ cya strains, and Δ cya crp* to be equally sensitive and the crp - strain to be more resistant. We conclude that cessation of respiration and cell killing after UV irradiation are regulated by cAMP and the CRP. (orig.) [de

  11. The effect of caffeine to increase reaction time in the rat during a test of attention is mediated through antagonism of adenosine A2A receptors.

    Science.gov (United States)

    Higgins, Guy A; Grzelak, Michael E; Pond, Annamarie J; Cohen-Williams, Mary E; Hodgson, Robert A; Varty, Geoffrey B

    2007-12-11

    Caffeine produces effects on cognitive function particularly relating to aspects of attention such as reaction time. Considering the plasma exposure levels following regular caffeine intake, and the affinity of caffeine for known protein targets, these effects are likely mediated by either the adenosine A(1) or A(2A) receptor. In the present studies, two rat strains [Long-Evans (LE) and CD] were trained to asymptote performance in a test of selective attention, the 5-choice serial reaction time task (5-CSRTT). Next, the effects of caffeine were compared to the selective A(2A) antagonists, SCH 412348 and KW-6002 (Istradefylline), and the A(1) antagonist, DPCPX. Further studies compared the psychostimulant effects of each drug. Finally, we tested the A(2A) agonist, CGS-21680, on 5-CSRTT performance and given the antipsychotic potential of this drug class, studied the interaction between CGS-21680 and amphetamine in this task. Caffeine (3-10mg/kg IP) increased reaction time in both LE and CD rats, with no effect on accuracy, an effect replicated by SCH 412348 (0.1-1mg/kg PO) and KW-6002 (1-3mg/kg PO), but not DPCPX (3-30 mg/kg PO). At least with SCH 412348, these effects were at doses that were not overtly psychostimulant. In contrast, CGS-21680 (0.03-0. 3mg/kg IP) slowed reaction speed and increased omissions. Interestingly, at a comparatively low dose of 0.03 mg/kg, CGS-21680 attenuated the increased premature responding produced by amphetamine (1mg/kg IP). The present results suggest that the attention-enhancing effects of caffeine are mediated through A(2A) receptor blockade, and selective A(2A) receptor antagonists may have potential as therapies for attention-related disorders. Furthermore, the improvement in response control in amphetamine-treated rats following CGS-21680 pretreatment supports the view that A(2A) agonists have potential as novel antipsychotics.

  12. Excitatory effect of the A2A adenosine receptor agonist CGS-21680 on spontaneous and K+-evoked acetylcholine release at the mouse neuromuscular junction.

    Science.gov (United States)

    Palma, A G; Muchnik, S; Losavio, A S

    2011-01-13

    The mechanism of action of the A2A adenosine receptor agonist 2-p-(2-carboxyethyl) phenethylamino-5'-N-ethylcarboxamidoadenosine hydrochloride (CGS-21680) in the facilitation of spontaneous (isotonic and hypertonic condition) and K+-evoked acetylcholine (ACh) release was investigated in the mouse diaphragm muscles. At isotonic condition, the CGS-21680-induced excitatory effect on miniature end-plate potential (MEPP) frequency was not modified in the presence of CdCl2 and in a medium free of Ca2+ (0Ca2+-EGTA), but it was abolished after buffering the rise of intracellular Ca2+ with 1,2-bis-(2-aminophenoxy)-ethane-N,N,N',N'-tetraacetic acid tetra(acetoxy-methyl) (BAPTA-AM) and when the Ca2+-ATPase inhibitor thapsigargin was used to deplete intracellular Ca2+ stores. CGS-21680 did not have a direct effect on the Ca2+-independent neurotransmitter-releasing machinery, since the modulatory effect on the hypertonic response was also occluded by BAPTA-AM and thapsigargin. CGS-21680 facilitation on K+-evoked ACh release was not altered by the P/Q-type voltage-dependent calcium channel (VDCC) blocker ω-Agatoxin IVA, but it was completely prevented by both, the L-type VDCC blocker nitrendipine (which is known to immobilize their gating charges), or thapsigargin, suggesting that the effects of CGS-21680 on L-type VDCC and thapsigargin-sensitive internal stores are associated. We found that the VDCC pore blocker Cd2+ (2 mM Ca2+ or 0Ca2+-EGTA) failed to affect the CGS-21680 effect in high K+ whereas nitrendipine in 0Ca2+-EGTA+Cd2+ occluded its action. The blockade of Ca2+ release from endoplasmic reticulum with ryanodine antagonized the facilitating effect of CGS-21680 in control and high K+ concentration. It is concluded that, at the mouse neuromuscular junction, activation of A2A receptors facilitates spontaneous and K+-evoked ACh release by an external Ca2+-independent mechanism but that involves mobilization of Ca2+ from internal stores: during spontaneous ACh release

  13. Activation of microglial cells triggers a release of brain-derived neurotrophic factor (BDNF) inducing their proliferation in an adenosine A2A receptor-dependent manner: A2A receptor blockade prevents BDNF release and proliferation of microglia

    Science.gov (United States)

    2013-01-01

    Background Brain-derived neurotrophic factor (BDNF) has been shown to control microglial responses in neuropathic pain. Since adenosine A2A receptors (A2ARs) control neuroinflammation, as well as the production and function of BDNF, we tested to see if A2AR controls the microglia-dependent secretion of BDNF and the proliferation of microglial cells, a crucial event in neuroinflammation. Methods Murine N9 microglial cells were challenged with lipopolysaccharide (LPS, 100 ng/mL) in the absence or in the presence of the A2AR antagonist, SCH58261 (50 nM), as well as other modulators of A2AR signaling. The BDNF cellular content and secretion were quantified by Western blotting and ELISA, A2AR density was probed by Western blotting and immunocytochemistry and cell proliferation was assessed by BrdU incorporation. Additionally, the A2AR modulation of LPS-driven cell proliferation was also tested in primary cultures of mouse microglia. Results LPS induced time-dependent changes of the intra- and extracellular levels of BDNF and increased microglial proliferation. The maximal LPS-induced BDNF release was time-coincident with an LPS-induced increase of the A2AR density. Notably, removing endogenous extracellular adenosine or blocking A2AR prevented the LPS-mediated increase of both BDNF secretion and proliferation, as well as exogenous BDNF-induced proliferation. Conclusions We conclude that A2AR activation plays a mandatory role controlling the release of BDNF from activated microglia, as well as the autocrine/paracrine proliferative role of BDNF. PMID:23363775

  14. Quantification of adenosine A{sub 2A} receptors in the human brain using [{sup 11}C]TMSX and positron emission tomography

    Energy Technology Data Exchange (ETDEWEB)

    Naganawa, Mika [Tokyo Metropolitan Institute of Gerontology, Positron Medical Center, Tokyo (Japan); Japan Society for the Promotion of Science, Tokyo (Japan); Kimura, Yuichi; Oda, Keiichi; Ishii, Kenji; Ishiwata, Kiichi [Tokyo Metropolitan Institute of Gerontology, Positron Medical Center, Tokyo (Japan); Mishina, Masahiro [Nippon Medical School Chiba-Hokusoh Hospital, Neurological Institute, Chiba (Japan); Manabe, Yoshitsugu; Chihara, Kunihiro [Nara Institute of Science and Technology, Graduate School of Information Science, Nara (Japan)

    2007-05-15

    [7-methyl-{sup 11}C]-(E)-8-(3,4,5-trimethoxystyryl)-1,3,7-trimethylxanthine ([{sup 11}C]TMSX) is a positron-emitting adenosine A{sub 2A} receptor (A2AR) antagonist for visualisation of A2AR distribution by positron emission tomography (PET). The aims of this paper were to use a kinetic model to analyse the behaviour of [{sup 11}C]TMSX in the brain and to examine the applicability of the Logan plot. We also studied the applicability of a simplified Logan plot by omitting metabolite correction and arterial blood sampling. The centrum semiovale was used as a reference region on the basis of a post-mortem study showing that it has a negligibly low density of A2ARs. Compartmental analysis was performed in five normal subjects. Parametric images of A2AR binding potential (BP) were also generated using a Logan plot with or without metabolite correction and with or without arterial blood sampling. To omit arterial blood sampling, we applied a method to extract the plasma-related information using independent component analysis (EPICA). The estimated K{sub 1}/k{sub 2} was confirmed to be common in the centrum semiovale and main cortices. The three-compartment model was well fitted to the other regions using the fixed value of K{sub 1}/k{sub 2} estimated from the centrum semiovale. The estimated BPs using the Logan plot matched those derived from compartment analysis. Without the metabolite correction, the estimate of BP underestimated the true value by 5%. The estimated BPs agreed regardless of arterial blood sampling. A three-compartment model with a reference region, the centrum semiovale, describes the kinetic behaviour of [{sup 11}C]TMSX PET images. A2ARs in the human brain can be visualised as a BP image using [{sup 11}C]TMSX PET without arterial blood sampling. (orig.)

  15. Caffeine Reverts Memory But Not Mood Impairment in a Depression-Prone Mouse Strain with Up-Regulated Adenosine A2A Receptor in Hippocampal Glutamate Synapses.

    Science.gov (United States)

    Machado, Nuno J; Simões, Ana Patrícia; Silva, Henrique B; Ardais, Ana Paula; Kaster, Manuella P; Garção, Pedro; Rodrigues, Diana I; Pochmann, Daniela; Santos, Ana Isabel; Araújo, Inês M; Porciúncula, Lisiane O; Tomé, Ângelo R; Köfalvi, Attila; Vaugeois, Jean-Marie; Agostinho, Paula; El Yacoubi, Malika; Cunha, Rodrigo A; Gomes, Catarina A

    2017-03-01

    Caffeine prophylactically prevents mood and memory impairments through adenosine A 2A receptor (A 2A R) antagonism. A 2A R antagonists also therapeutically revert mood and memory impairments, but it is not known if caffeine is also therapeutically or only prophylactically effective. Since depression is accompanied by mood and memory alterations, we now explored if chronic (4 weeks) caffeine consumption (0.3 g/L) reverts mood and memory impairment in helpless mice (HM, 12 weeks old), a bred-based model of depression. HM displayed higher immobility in the tail suspension and forced swimming tests, greater anxiety in the elevated plus maze, and poorer memory performance (modified Y-maze and object recognition). HM also had reduced density of synaptic (synaptophysin, SNAP-25), namely, glutamatergic (vGluT1; -22 ± 7 %) and GABAergic (vGAT; -23 ± 8 %) markers in the hippocampus. HM displayed higher A 2A R density (72 ± 6 %) in hippocampal synapses, an enhanced facilitation of hippocampal glutamate release by the A 2A R agonist, CGS21680 (30 nM), and a larger LTP amplitude (54 ± 8 % vs. 21 ± 5 % in controls) that was restored to control levels (30 ± 10 %) by the A 2A R antagonist, SCH58261 (50 nM). Notably, caffeine intake reverted memory deficits and reverted the loss of hippocampal synaptic markers but did not affect helpless or anxiety behavior. These results reinforce the validity of HM as an animal model of depression by showing that they also display reference memory deficits. Furthermore, caffeine intake selectively reverted memory but not mood deficits displayed by HM, which are associated with an increased density and functional impact of hippocampal A 2A R controlling synaptic glutamatergic function.

  16. A3 adenosine receptor agonist prevents the development of paclitaxel-induced neuropathic pain by modulating spinal glial-restricted redox-dependent signaling pathways.

    Science.gov (United States)

    Janes, Kali; Esposito, Emanuela; Doyle, Timothy; Cuzzocrea, Salvatore; Tosh, Dillip K; Jacobson, Kenneth A; Salvemini, Daniela

    2014-12-01

    Chemotherapy-induced peripheral neuropathy accompanied by chronic neuropathic pain is the major dose-limiting toxicity of several anticancer agents including the taxane paclitaxel (Taxol). A critical mechanism underlying paclitaxel-induced neuropathic pain is the increased production of peroxynitrite in spinal cord generated in response to activation of the superoxide-generating enzyme, NADPH oxidase. Peroxynitrite in turn contributes to the development of neuropathic pain by modulating several redox-dependent events in spinal cord. We recently reported that activation of the Gi/Gq-coupled A3 adenosine receptor (A3AR) with selective A3AR agonists (ie, IB-MECA) blocked the development of chemotherapy induced-neuropathic pain evoked by distinct agents, including paclitaxel, without interfering with anticancer effects. The mechanism or mechanisms of action underlying these beneficial effects has yet to be explored. We now demonstrate that IB-MECA attenuates the development of paclitaxel-induced neuropathic pain by inhibiting the activation of spinal NADPH oxidase and two downstream redox-dependent systems. The first relies on inhibition of the redox-sensitive transcription factor (NFκB) and mitogen activated protein kinases (ERK and p38) resulting in decreased production of neuroexcitatory/proinflammatory cytokines (TNF-α, IL-1β) and increased formation of the neuroprotective/anti-inflammatory IL-10. The second involves inhibition of redox-mediated posttranslational tyrosine nitration and modification (inactivation) of glia-restricted proteins known to play key roles in regulating synaptic glutamate homeostasis: the glutamate transporter GLT-1 and glutamine synthetase. Our results unravel a mechanistic link into biomolecular signaling pathways employed by A3AR activation in neuropathic pain while providing the foundation to consider use of A3AR agonists as therapeutic agents in patients with chemotherapy-induced peripheral neuropathy. Copyright © 2014

  17. Adenosine A1 Receptor Antagonism Abolished the Anti-seizure Effects of Exogenous Ketone Supplementation in Wistar Albino Glaxo Rijswijk Rats

    Directory of Open Access Journals (Sweden)

    Zsolt Kovács

    2017-07-01

    Full Text Available The state of therapeutic ketosis can be achieved by using the ketogenic diet (KD or exogenous ketone supplementation. It was suggested previously that the adenosinergic system may be involved in the mediating effect of KD on suppressing seizure activity in different types of epilepsies, likely by means of adenosine A1 receptors (A1Rs. Thus, we tested in the present study whether exogenous ketone supplements (ketone ester: KE, 2.5 g/kg/day; ketone salt/KS + medium chain triglyceride/MCT: KSMCT, 2.5 g/kg/day applied sub-chronically (for 7 days by intragastric gavage can modulate absence epileptic activity in genetically absence epileptic Wistar Albino Glaxo/Rijswijk (WAG/Rij rats. The number of spike-wave discharges (SWDs significantly and similarly decreased after both KE and KSMCT treatment between 3rd and 7th days of gavage. Moreover, blood beta-hydroxybutyrate (βHB levels were significantly increased alike after KE and KSMCT gavage, compared to control levels. The SWD number and βHB levels returned to the baseline levels on the first day without ketone supplementation. To determine whether A1Rs can modify ketone supplement-evoked changes in absence epileptic activity, we applied a non-pro-epileptic dose of a specific A1R antagonist DPCPX (1,3-dipropyl-8-cyclopentylxanthine (intraperitoneal/i.p. 0.2 mg/kg in combination with KSMCT (2.5 g/kg/day, gavage. As expected, DPCPX abolished the KSMCT-evoked decrease in SWD number. Thus, we concluded that application of exogenous ketone supplements may decrease absence epileptic activity in WAG/Rij rats. Moreover, our results suggest that among others the adenosinergic system, likely via A1Rs, may modulate the exogenous ketone supplements-evoked anti-seizure effects.

  18. The activation mechanisms of G protein-coupled receptors : the case of the adenosine A2B and HCA2/3 receptors

    NARCIS (Netherlands)

    Liu, R.

    2016-01-01

    Identifying and elucidating the functions and activation of GPCRs will provide opportunities for novel drug discovery. We confirmed that a yeast system with an extended library of G proteins is very well suited for the study of GPCR activation, G protein coupling profiles, receptor-G protein binding

  19. Involvement of adenosine in the antiinflammatory action of ketamine.

    Science.gov (United States)

    Mazar, Julia; Rogachev, Boris; Shaked, Gad; Ziv, Nadav Y; Czeiger, David; Chaimovitz, Cidio; Zlotnik, Moshe; Mukmenev, Igor; Byk, Gerardo; Douvdevani, Amos

    2005-06-01

    Ketamine is an anesthetic drug. Subanesthetic doses of ketamine have been shown to reduce interleukin-6 concentrations after surgery and to reduce mortality and the production of tumor necrosis factor alpha and interleukin 6 in septic animals. Similarly, adenosine was shown to reduce tumor necrosis factor alpha and mortality of septic animals. The aim of this study was to determine whether adenosine mediates the antiinflammatory effects of ketamine. Sepsis was induced in mice by lipopolysaccharide or Escherichia coli inoculation. Leukocyte recruitment and cytokine concentrations were used as inflammation markers. Adenosine concentrations were assayed by high-performance liquid chromatography, and the involvement of adenosine in the effects of ketamine was demonstrated by adenosine receptor agonists and antagonists. Ketamine markedly reduced mortality from sepsis, leukocyte recruitment, and tumor necrosis factor-alpha and interleukin-6 concentrations. Ketamine administration in mice and rats was associated with a surge at 20-35 min of adenosine in serum (up to 5 microm) and peritoneal fluid. The adenosine A2A receptor agonist CGS-21680 mimicked the effect of ketamine in peritonitis, whereas the A2A receptor antagonists DMPX and ZM 241385 blocked its antiinflammatory effects. In contrast, A1 and A3 receptor antagonists had no effect. ZM 241385 reversed the beneficial effect of ketamine on survival from bacterial sepsis. The current data suggest that the sepsis-protective antiinflammatory effects of ketamine are mediated by the release of adenosine acting through the A2A receptor.

  20. Effects of adenosine infusion into renal interstitium on renal hemodynamics

    International Nuclear Information System (INIS)

    Pawlowska, D.; Granger, J.P.; Knox, F.G.

    1987-01-01

    This study was designed to investigate the hemodynamic effects of exogenous adenosine in the interstitium of the rat kidney. Adenosine or its analogues were infused into the renal interstitium by means of chronically implanted capsules. In fusion of adenosine decreased glomerular filtration rate (GFR) from 0.81 +/- 0.06 to 0.37 +/- 0.06 ml/min while having no effect on renal blood flow (RBF). The metabolically stable analogue, 2-chloradenosine (2-ClAdo), decreased GFR from 0.73 +/- 0.07 to 021 +/- 0.06 ml/min. Interstitial infusion of theophylline, an adenosine receptor antagonist, completely abolished the effects of adenosine and 2-ClAdo on GFR. The distribution of adenosine, when infused into the renal interstitium, was determined using radiolabeled 5'-(N-ethyl)-carboxamidoadenosine (NECA), a metabolically stable adenosine agonist. After continuous infusion, [ 3 H]NECA was distributed throughout the kidney. The effects of NECA to reduce GFR were similar to those of adenosine and 2-ClAdo. They conclude that increased levels of adenosine in the renal interstitium markedly decrease GFR without affecting RBF in steady-state conditions. The marked effects of adenosine agonists during their infusion into the renal interstitium and the complete blockade of these effects by theophylline suggest an extracellular action of adenosine

  1. Caffeine Inhibits the Activation of Hepatic Stellate Cells Induced by Acetaldehyde via Adenosine A2A Receptor Mediated by the cAMP/PKA/SRC/ERK1/2/P38 MAPK Signal Pathway

    Science.gov (United States)

    Yang, Wanzhi; Wang, Qi; Zhao, Han; Yang, Feng; Lv, Xiongwen; Li, Jun

    2014-01-01

    Hepatic stellate cell (HSC) activation is an essential event during alcoholic liver fibrosis. Evidence suggests that adenosine aggravates liver fibrosis via the adenosine A2A receptor (A2AR). Caffeine, which is being widely consumed during daily life, inhibits the action of adenosine. In this study, we attempted to validate the hypothesis that caffeine influences acetaldehyde-induced HSC activation by acting on A2AR. Acetaldehyde at 50, 100, 200, and 400 μM significantly increased HSC-T6 cells proliferation, and cell proliferation reached a maximum at 48 h after exposure to 200 μM acetaldehyde. Caffeine and the A2AR antagonist ZM241385 decreased the cell viability and inhibited the expression of procollagen type I and type III in acetaldehyde-induced HSC-T6 cells. In addition, the inhibitory effect of caffeine on the expression of procollagen type I was regulated by A2AR-mediated signal pathway involving cAMP, PKA, SRC, and ERK1/2. Interestingly, caffeine’s inhibitory effect on the expression of procollagen type III may depend upon the A2AR-mediated P38 MAPK-dependent pathway. Conclusions: Caffeine significantly inhibited acetaldehyde-induced HSC-T6 cells activation by distinct A2AR mediated signal pathway via inhibition of cAMP-PKA-SRC-ERK1/2 for procollagen type I and via P38 MAPK for procollagen type III. PMID:24682220

  2. Quantitative analysis of adenosine A{sub 1} receptors in human brain using positron emission tomography and [1 -methyl-{sup 11}C]8-dicyclopropylmethyl-1-methyl-3-propylxanthine

    Energy Technology Data Exchange (ETDEWEB)

    Kimura, Yuichi [Positron Medical Center, Tokyo Metropolitan Institute of Gerontology, 1-1, Naka, Itabashi, Tokyo, 173-0022 (Japan)]. E-mail: ukimura@ieee.org; Ishii, Kenji [Positron Medical Center, Tokyo Metropolitan Institute of Gerontology, 1-1, Naka, Itabashi, Tokyo, 173-0022 (Japan); Fukumitsu, Nobuyoshi [Positron Medical Center, Tokyo Metropolitan Institute of Gerontology, 1-1, Naka, Itabashi, Tokyo, 173-0022 (Japan); Department of Radiation Oncology, University of Tsukuba Hospital, Amakubo, 2-1-1, Tsukuba, 305-8576 (Japan); Oda, Keiichi [Positron Medical Center, Tokyo Metropolitan Institute of Gerontology, 1-1, Naka, Itabashi, Tokyo, 173-0022 (Japan); Sasaki, Toru [Positron Medical Center, Tokyo Metropolitan Institute of Gerontology, 1-1, Naka, Itabashi, Tokyo, 173-0022 (Japan); Kawamura, Kazunori [Positron Medical Center, Tokyo Metropolitan Institute of Gerontology, 1-1, Naka, Itabashi, Tokyo, 173-0022 (Japan); SHI Accelerator Service Ltd., 1-17-6, Ohsaki, Shinagawa, Tokyo, 141-0032 (Japan); Ishiwata, Kiichi [Positron Medical Center, Tokyo Metropolitan Institute of Gerontology, 1-1, Naka, Itabashi, Tokyo, 173-0022 (Japan)

    2004-11-01

    Fully quantitative analysis of the adenosine A{sub 1} receptor (A1R) in the brain with {sup 11}C-MPDX and positron emission tomography is reported. The kinetics is described using a two-tissue three-compartment model, and estimated binding potentials correspond well with the estimates made by Logan plot. The image of the binding potential of the MPDX is physiologically reasonable. We conclude that MPDX is applicable to the visualization of the A1Rs in the brain with Logan plot.

  3. Anxiolytic Effect of Exogenous Ketone Supplementation Is Abolished by Adenosine A1 Receptor Inhibition in Wistar Albino Glaxo/Rijswijk Rats.

    Science.gov (United States)

    Kovács, Zsolt; D'Agostino, Dominic P; Ari, Csilla

    2018-01-01

    Anxiety disorders are one of the most common mental health problems worldwide, but the exact pathophysiology remains largely unknown. It has been demonstrated previously that administration of exogenous ketone supplement KSMCT (ketone salt/KS + medium chain triglyceride/MCT oil) by intragastric gavage for 7 days decreased the anxiety level in genetically absence epileptic Wistar Albino Glaxo/Rijswijk (WAG/Rij) rats. To investigate the potential role of the adenosinergic system in the pathomechanism of anxiety we tested whether the inhibition of adenosine A 1 receptors (A 1 Rs) influence the anxiolytic effect of the exogenous ketone supplement. As A 1 Rs may mediate such an effect, in the present study we used a specific A 1 R antagonist, DPCPX (1,3-dipropyl-8-cyclopentylxanthine) to test whether it modulates the anxiolytic effect of sub-chronically (7 days) applied KSMCT in the previously tested animal model by using elevated plus maze (EPM) test. We administered KSMCT (2.5 g/kg/day) alone by intragastric gavage and in combination with intraperitoneally (i.p.) injected of DPCPX in two doses (lower: 0.15 mg/kg, higher: 0.25 mg/kg). Control groups represented i.p saline and water gavage with or without i.p. DPCPX administration (2.5 g/kg/day). After treatments, the level of blood glucose and beta-hydroxybutyrate (βHB), as well as body weight were recorded. KSMCT alone significantly increased the time spent in the open arms and decreased the time spent in the closed arms, supporting our previous results. Injection of lower dose of DPCPX decreased, while higher dose of DPCPX abolished the effect of KSMCT administration on EPM. Blood βHB levels were significantly increased after administration of KSMCT, while DPCPX did not change the KSMCT induced increase in blood βHB levels. These results demonstrate that A 1 R inhibition modified (decreased) the anti-anxiety effect of KSMCT administration implying that the adenosinergic system, likely via A 1 Rs, may modulate the

  4. Anxiolytic Effect of Exogenous Ketone Supplementation Is Abolished by Adenosine A1 Receptor Inhibition in Wistar Albino Glaxo/Rijswijk Rats

    Directory of Open Access Journals (Sweden)

    Zsolt Kovács

    2018-02-01

    Full Text Available Anxiety disorders are one of the most common mental health problems worldwide, but the exact pathophysiology remains largely unknown. It has been demonstrated previously that administration of exogenous ketone supplement KSMCT (ketone salt/KS + medium chain triglyceride/MCT oil by intragastric gavage for 7 days decreased the anxiety level in genetically absence epileptic Wistar Albino Glaxo/Rijswijk (WAG/Rij rats. To investigate the potential role of the adenosinergic system in the pathomechanism of anxiety we tested whether the inhibition of adenosine A1 receptors (A1Rs influence the anxiolytic effect of the exogenous ketone supplement. As A1Rs may mediate such an effect, in the present study we used a specific A1R antagonist, DPCPX (1,3-dipropyl-8-cyclopentylxanthine to test whether it modulates the anxiolytic effect of sub-chronically (7 days applied KSMCT in the previously tested animal model by using elevated plus maze (EPM test. We administered KSMCT (2.5 g/kg/day alone by intragastric gavage and in combination with intraperitoneally (i.p. injected of DPCPX in two doses (lower: 0.15 mg/kg, higher: 0.25 mg/kg. Control groups represented i.p saline and water gavage with or without i.p. DPCPX administration (2.5 g/kg/day. After treatments, the level of blood glucose and beta-hydroxybutyrate (βHB, as well as body weight were recorded. KSMCT alone significantly increased the time spent in the open arms and decreased the time spent in the closed arms, supporting our previous results. Injection of lower dose of DPCPX decreased, while higher dose of DPCPX abolished the effect of KSMCT administration on EPM. Blood βHB levels were significantly increased after administration of KSMCT, while DPCPX did not change the KSMCT induced increase in blood βHB levels. These results demonstrate that A1R inhibition modified (decreased the anti-anxiety effect of KSMCT administration implying that the adenosinergic system, likely via A1Rs, may modulate the

  5. Renal ischemia-reperfusion injury and adenosine 2A receptor-mediated tissue protection: the role of CD4+ T cells and IFN-gamma.

    Science.gov (United States)

    Day, Yuan-Ji; Huang, Liping; Ye, Hong; Li, Li; Linden, Joel; Okusa, Mark D

    2006-03-01

    A(2A) adenosine receptor (A(2A)R)-expressing bone marrow (BM)-derived cells contribute to the renal protective effect of A(2A) agonists in renal ischemia-reperfusion injury (IRI). We performed IRI in mice lacking T and B cells to determine whether A(2A)R expressed in CD4+ cells mediate protection from IRI. Rag-1 knockout (KO) mice were protected in comparison to wild-type (WT) mice when subjected to IRI. ATL146e, a selective A(2A) agonist, did not confer additional protection. IFN-gamma is an important early signal in IRI and is thought to contribute to reperfusion injury. Because IFN-gamma is produced by kidney cells and T cells we performed IRI in BM chimeras in which the BM of WT mice was reconstituted with BM from IFN-gamma KO mice (IFN-gamma KO-->WT chimera). We observed marked reduction in IRI in comparison to WT-->WT chimeras providing additional indirect support for the role of T cells. To confirm the role of CD4+ A(2A)R in mediating protection from IRI, Rag-1 KO mice were subjected to ischemia-reperfusion. The protection observed in Rag-1 KO mice was reversed in Rag-1 KO mice that were adoptively transferred WT CD4+ cells (WT CD4+-->Rag-1 KO) or A(2A) KO CD4+ cells (A(2A) KO CD4+-->Rag-1 KO). ATL146e reduced injury in WT CD4+-->Rag-1 KO mice but not in A(2A) KO CD4+-->Rag-1 KO mice. Rag-1 KO mice reconstituted with CD4+ cells derived from IFN-gamma KO mice (IFN-gamma CD4+-->Rag-1 KO) were protected from IRI; ATL146e conferred no additional protection. These studies demonstrate that CD4+ IFN-gamma contributes to IRI and that A(2A) agonists mediate protection from IRI through action on CD4+ cells.

  6. Synthesis and characterization of [{sup 76}Br]-labeled high-affinity A{sub 3} adenosine receptor ligands for positron emission tomography

    Energy Technology Data Exchange (ETDEWEB)

    Kiesewetter, Dale O. [Positron Emission Tomography Radiochemistry Group, NIBIB, Clinical Center, National Institutes of Health, Bethesda, MD 20892 (United States)], E-mail: dk7k@nih.gov; Lang Lixin; Ma Ying; Bhattacharjee, Abesh Kumar [Positron Emission Tomography Radiochemistry Group, NIBIB, Clinical Center, National Institutes of Health, Bethesda, MD 20892 (United States); Gao, Zhan-Guo; Joshi, Bhalchandra V.; Melman, Artem; Castro, Sonia de; Jacobson, Kenneth A. [Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892 (United States)

    2009-01-15

    Introduction: Bromine-76-radiolabeled analogues of previously reported high-affinity A{sub 3} adenosine receptor (A{sub 3}AR) nucleoside ligands have been prepared as potential radiotracers for positron emission tomography. Methods: The radiosyntheses were accomplished by oxidative radiobromination on the N{sup 6}-benzyl moiety of trimethyltin precursors. Biodistribution studies of the kinetics of uptake were conducted in awake rats. Results: We prepared an agonist ligand {l_brace}[{sup 76}Br](1'S,2'R,3'S,4'R,5'S)-4'-{l_brace}2-chloro-6-[(3-bromophenylmethyl)amino] purin-9-yl{r_brace}-1'-(methylaminocarbonyl)bicyclo[3.1.0]hexane-2',3'-diol (MRS3581){r_brace} in 59% radiochemical yield with a specific activity of 19.5 GBq/{mu}mol and an antagonist ligand {l_brace}[{sup 76}Br](1'R,2'R,3'S,4'R,5'S)-4'-(6-(3-bromobenzylamino) -2-chloro-9H-purin-9-yl)bicyclo[3.1.0]hexane-2',3'-diol (MRS5147){r_brace} in 65% radiochemical yield with a specific activity of 22 GBq/{mu}mol. The resultant products exhibited the expected high affinity (K{sub i}{approx}0.6 nM) and specific binding at the human A{sub 3}AR in vitro. Biodistribution studies in the rat showed uptake in the organs of excretion and metabolism. The antagonist MRS5147 exhibited increasing uptake in testes, an organ that contains significant quantities of A{sub 3}AR, over a 2-h time course, which suggests the presence of a specific A{sub 3}AR retention mechanism. Conclusion: We were able to compare uptake of the [{sup 76}Br]-labeled antagonist MRS5147 to [{sup 76}Br]agonist MRS3581. The antagonist MRS5147 shows increasing uptake in the testes, an A{sub 3}AR-rich tissue, suggesting that this ligand may have promise as a molecular imaging agent.

  7. Metabolic changes of cultured DRG neurons induced by adenosine using confocal microscopy imaging

    Science.gov (United States)

    Zheng, Liqin; Huang, Yimei; Chen, Jiangxu; Wang, Yuhua; Yang, Hongqin; Zhang, Yanding; Xie, Shusen

    2012-12-01

    Adenosine exerts multiple effects on pain transmission in the peripheral nervous system. This study was performed to use confocal microscopy to evaluate whether adenosine could affect dorsal root ganglia (DRG) neurons in vitro and test which adenosine receptor mediates the effect of adenosine on DRG neurons. After adding adenosine with different concentration, we compared the metabolic changes by the real time imaging of calcium and mitochondria membrane potential using confocal microscopy. The results showed that the effect of 500 μM adenosine on the metabolic changes of DRG neurons was more significant than others. Furthermore, four different adenosine receptor antagonists were used to study which receptor mediated the influences of adenosine on the cultured DRG neurons. All adenosine receptor antagonists especially A1 receptor antagonist (DPCPX) had effect on the Ca2+ and mitochondria membrane potential dynamics of DRG neurons. The above studies demonstrated that the effect of adenosine which may be involved in the signal transmission on the sensory neurons was dose-dependent, and all the four adenosine receptors especially the A1R may mediate the transmission.

  8. Total and partial sleep deprivation: Effects on plasma TNF-αRI, TNF-αRII, and IL-6, and reversal by caffeine operating through adenosine A2 receptor

    Science.gov (United States)

    Shearer, William T.; Reuben, James M.; Lee, Bang-Ning; Mullington, Janet; Price, Nicholas; Dinges, David F.

    2000-01-01

    Plasma levels of IL-6 and TNF-α are elevated in individuals who are deprived of sleep. TNF-α regulates expression of its soluble receptors, sTNF-αRI and sTNF-αRII. Sleep deprivation (SD) also increases extracellular adenosine that induces sedation and sleep. An antagonist of adenosine, caffeine, raises exogenous adenosine levels, stimulates the expression of IL-6 and inhibits the release of TNF-α. Our objective was to determine the effect of total SD (TSD) or partial SD (PSD) on the levels of these sleep regulatory molecules in volunteers who experienced SD with or without the consumption of caffeine. Plasma levels of IL-6, sTNF-αRI and sTNF-αRII were assayed by ELISA in samples collected at 90-min intervals from each subject over an 88-hour period. The results were analyzed by the repeated measures ANOVA. Whereas only TSD significantly increased sTNF-αRI over time, caffeine suppressed both sTNF-α receptors in TSD and PSD subjects. The selective increase in the expression of sTNF-αRI and not sTNF-αRII in subjects experiencing TSD with caffeine compared with others experiencing PSD with caffeine has not been previously reported. Moreover, caffeine significantly increased IL-6 in TSD subjects compared with those who did not receive caffeine. However, subjects who were permitted intermittent naps (PSD) ablated the effects of caffeine and reduced their level of IL-6 to that of the TSD group. These data further lend support to the hypothesis that the sTNF-αRI and not the sTNF-αRII plays a significant role in sleep regulation by TNF-α. .

  9. Presynaptic muscarinic acetylcholine autoreceptors (M1, M2 and M4 subtypes), adenosine receptors (A1 and A2A) and tropomyosin-related kinase B receptor (TrkB) modulate the developmental synapse elimination process at the neuromuscular junction.

    Science.gov (United States)

    Nadal, Laura; Garcia, Neus; Hurtado, Erica; Simó, Anna; Tomàs, Marta; Lanuza, Maria A; Santafé, Manel; Tomàs, Josep

    2016-06-23

    The development of the nervous system involves an initially exuberant production of neurons that make an excessive number of synaptic contacts. The initial overproduction of synapses promotes connectivity. Hebbian competition between axons with different activities (the least active are punished) leads to the loss of roughly half of the overproduced elements and this refines connectivity and increases specificity. The neuromuscular junction is innervated by a single axon at the end of the synapse elimination process and, because of its relative simplicity, has long been used as a model for studying the general principles of synapse development. The involvement of the presynaptic muscarinic ACh autoreceptors may allow for the direct competitive interaction between nerve endings through differential activity-dependent acetylcholine release in the synaptic cleft. Then, the most active ending may directly punish the less active ones. Our previous results indicate the existence in the weakest axons on the polyinnervated neonatal NMJ of an ACh release inhibition mechanism based on mAChR coupled to protein kinase C and voltage-dependent calcium channels. We suggest that this mechanism plays a role in the elimination of redundant neonatal synapses. Here we used confocal microscopy and quantitative morphological analysis to count the number of brightly fluorescent axons per endplate in P7, P9 and P15 transgenic B6.Cg-Tg (Thy1-YFP)16 Jrs/J mice. We investigate the involvement of individual mAChR M1-, M2- and M4-subtypes in the control of axonal elimination after the Levator auris longus muscle had been exposed to agonist and antagonist in vivo. We also analysed the role of adenosine receptor subtypes (A1 and A2A) and the tropomyosin-related kinase B receptor. The data show that postnatal axonal elimination is a regulated multireceptor mechanism that guaranteed the monoinnervation of the neuromuscular synapses. The three receptor sets considered (mAChR, AR and TrkB receptors

  10. Adenosine contribution to normal renal physiology and chronic kidney disease.

    Science.gov (United States)

    Oyarzún, Carlos; Garrido, Wallys; Alarcón, Sebastián; Yáñez, Alejandro; Sobrevia, Luis; Quezada, Claudia; San Martín, Rody

    2017-06-01

    Adenosine is a nucleoside that is particularly interesting to many scientific and clinical communities as it has important physiological and pathophysiological roles in the kidney. The distribution of adenosine receptors has only recently been elucidated; therefore it is likely that more biological roles of this nucleoside will be unveiled in the near future. Since the discovery of the involvement of adenosine in renal vasoconstriction and regulation of local renin production, further evidence has shown that adenosine signaling is also involved in the tubuloglomerular feedback mechanism, sodium reabsorption and the adaptive response to acute insults, such as ischemia. However, the most interesting finding was the increased adenosine levels in chronic kidney diseases such as diabetic nephropathy and also in non-diabetic animal models of renal fibrosis. When adenosine is chronically increased its signaling via the adenosine receptors may change, switching to a state that induces renal damage and produces phenotypic changes in resident cells. This review discusses the physiological and pathophysiological roles of adenosine and pays special attention to the mechanisms associated with switching homeostatic nucleoside levels to increased adenosine production in kidneys affected by CKD. Copyright © 2017 Elsevier Ltd. All rights reserved.

  11. Regulation of adenosine deaminase (ADA) on induced mouse experimental autoimmune uveitis (EAU) ?

    OpenAIRE

    Liang, Dongchun; Zuo, Aijun; Zhao, Ronglan; Shao, Hui; Kaplan, Henry J.; Sun, Deming

    2016-01-01

    Adenosine is an important regulator of the immune response and adenosine deaminase (ADA) inhibits this regulatory effect by converting adenosine into functionally inactive molecules. Studies have shown that adenosine receptor (AR) agonists can be either anti- or pro-inflammatory. Clarification of the mechanisms that cause these opposing effects should provide a better guide for therapeutic intervention. In this study, we investigated the effect of ADA on the development of experimental autoim...

  12. Circadian variations of adenosine and of its metabolism. Could adenosine be a molecular oscillator for circadian rhythms?

    Science.gov (United States)

    Chagoya de Sánchez, V

    1995-03-01

    The present review describes the biological implications of the periodic changes of adenosine concentrations in different tissues of the rat. Adenosine is a purine molecule that could have been formed in the prebiotic chemical evolution and has been preserved. The rhythmicity of this molecule, as well as its metabolism and even the presence of specific receptors, suggests a regulatory role in eukaryotic cells and in multicellular organisms. Adenosine may be considered a chemical messenger and its action could take place at the level of the same cell (autocrine), the same tissue (paracrine), or on separate organs (endocrine). Exploration of the circadian variations of adenosine was planned considering the liver as an important tissue for purine formation, the blood as a vehicle among tissues, and the brain as the possible acceptor for hepatic adenosine or its metabolites. The rats used in these studies were adapted to a dark-light cycle of 12 h with an unrestrained feeding and drinking schedule. The metabolic control of adenosine concentration in the different tissues studied through the 24-h cycle is related to the activity of adenosine-metabolizing enzyme: 5'-nucleotidase adenosine deaminase, adenosine kinase, and S-adenosylhomocysteine hydrolase. Some possibilities of the factors modulating the activity of these enzymes are commented upon. The multiphysiological action of adenosine could be mediated by several actions: (i) by interaction with extracellular and intracellular receptors and (ii) through its metabolism modulating the methylation pathway, possibly inducing physiological lipoperoxidation, or participating in the energetic homeostasis of the cell. The physiological meaning of the circadian variations of adenosine and its metabolism was focused on: maintenance of the energetic homeostasis of the tissues, modulation of membrane structure and function, regulation of fasting and feeding metabolic pattern, and its participation in the sleep-wake cycle. From

  13. Transcriptional profiling of striatal neurons in response to single or concurrent activation of dopamine D2, adenosine A(2A) and metabotropic glutamate type 5 receptors: focus on beta-synuclein expression.

    Science.gov (United States)

    Canela, Laia; Selga, Elisabet; García-Martínez, Juan Manuel; Amaral, Olavo B; Fernández-Dueñas, Víctor; Alberch, Jordi; Canela, Enric I; Franco, Rafael; Noé, Véronique; Lluís, Carme; Ciudad, Carlos J; Ciruela, Francisco

    2012-10-25

    G protein-coupled receptor oligomerization is a concept which is changing the understanding of classical pharmacology. Both, oligomerization and functional interaction between adenosine A(2A,) dopamine D(2) and metabotropic glutamate type 5 receptors have been demonstrated in the striatum. However, the transcriptional consequences of receptors co-activation are still unexplored. We aim here to determine the changes in gene expression of striatal primary cultured neurons upon isolated or simultaneous receptor activation. Interestingly, we found that 95 genes of the total analyzed (15,866 transcripts and variants) changed their expression in response to simultaneous stimulation of all three receptors. Among these genes, we focused on the β-synuclein (β-Syn) gene (SCNB). Quantitative PCR verified the magnitude and direction of change in expression of SCNB. Since β-Syn belongs to the homologous synuclein family and may be considered a natural regulator of α-synuclein (α-Syn), it has been proposed that β-Syn might act protectively against α-Syn neuropathology. Copyright © 2012 Elsevier B.V. All rights reserved.

  14. [{sup 18}F]FE rate at SUPPY: a suitable PET tracer for the adenosine A3 receptor? An in vivo study in rodents

    Energy Technology Data Exchange (ETDEWEB)

    Haeusler, Daniela; Zeilinger, Markus; Wadsak, Wolfgang; Hacker, Marcus; Mitterhauser, Markus [Medical University of Vienna, Department of Nuclear Medicine, Vienna (Austria); Kuntner, Claudia; Wanek, Thomas; Langer, Oliver [AIT Austrian Institute of Technology GmbH, Biomedical Systems, Health and Environment Department, Seibersdorf (Austria); Nics, Lukas [Medical University of Vienna, Department of Nuclear Medicine, Vienna (Austria); University of Vienna, Department of Nutritional Sciences, Vienna (Austria); Savli, Markus; Lanzenberger, Rupert R. [Medical University of Vienna, Department of Psychiatry and Psychotherapy, Vienna (Austria); Karagiannis, Panagiotis [King' s College London, Cutaneous Medicine and Immunotherapy, St. John' s Institute of Dermatology, Division of Genetics and Molecular Medicine King' s College London School of Medicine, Guy' s Hospital, London (United Kingdom); Shanab, Karem; Spreitzer, Helmut [University of Vienna, Department of Drug and Natural Product Synthesis, Vienna (Austria)

    2015-04-01

    The adenosine A{sub 3} receptor (A3R) is involved in cardiovascular, neurological and tumour-related pathologies and serves as an exceptional pharmaceutical target in the clinical setting. A3R antagonists are considered antiinflammatory, antiallergic and anticancer agents, and to have potential for the treatment of asthma, COPD, glaucoma and stroke. Hence, an appropriate A3R PET tracer would be highly beneficial for the diagnosis and therapy monitoring of these diseases. Therefore, in this preclinical in vivo study we evaluated the potential as a PET tracer of the A3R antagonist [{sup 18}F]FE rate at SUPPY. Rats were injected with [{sup 18}F]FE rate at SUPPY for baseline scans and blocking scans (A3R with MRS1523 or FE rate at SUPPY, P-gp with tariquidar; three animals each). Additionally, metabolism was studied in plasma and brain. In a preliminary experiment in a mouse xenograft model (mice injected with cells expressing the human A3R; three animals), the animals received [{sup 18}F]FE rate at SUPPY and [{sup 18}F]FDG. Dynamic PET imaging was performed (60 min in rats, 90 min in xenografted mice). In vitro stability of [{sup 18}F]FE rate at SUPPY in human and rat plasma was also evaluated. [{sup 18}F]FE rate at SUPPY showed high uptake in fat-rich regions and low uptake in the brain. Pretreatment with MRS1523 led to a decrease in [{sup 18}F]FE rate at SUPPY uptake (p = 0.03), and pretreatment with the P-gp inhibitor tariquidar led to a 1.24-fold increase in [{sup 18}F]FE rate at SUPPY uptake (p = 0.09) in rat brain. There was no significant difference in metabolites in plasma and brain in the treatment groups. However, plasma concentrations of [{sup 18}F]FE rate at SUPPY were reduced to levels similar to those in rat brain after blocking. In contrast to [{sup 18}F]FDG uptake (p = 0.12), the xenograft model showed significantly increased uptake of [{sup 18}F]FE rate at SUPPY in the tissue masses from CHO cells expressing the human A3R (p = 0.03). [{sup 18}F

  15. [18F]FE rate at SUPPY: a suitable PET tracer for the adenosine A3 receptor? An in vivo study in rodents

    International Nuclear Information System (INIS)

    Haeusler, Daniela; Zeilinger, Markus; Wadsak, Wolfgang; Hacker, Marcus; Mitterhauser, Markus; Kuntner, Claudia; Wanek, Thomas; Langer, Oliver; Nics, Lukas; Savli, Markus; Lanzenberger, Rupert R.; Karagiannis, Panagiotis; Shanab, Karem; Spreitzer, Helmut

    2015-01-01

    The adenosine A 3 receptor (A3R) is involved in cardiovascular, neurological and tumour-related pathologies and serves as an exceptional pharmaceutical target in the clinical setting. A3R antagonists are considered antiinflammatory, antiallergic and anticancer agents, and to have potential for the treatment of asthma, COPD, glaucoma and stroke. Hence, an appropriate A3R PET tracer would be highly beneficial for the diagnosis and therapy monitoring of these diseases. Therefore, in this preclinical in vivo study we evaluated the potential as a PET tracer of the A3R antagonist [ 18 F]FE rate at SUPPY. Rats were injected with [ 18 F]FE rate at SUPPY for baseline scans and blocking scans (A3R with MRS1523 or FE rate at SUPPY, P-gp with tariquidar; three animals each). Additionally, metabolism was studied in plasma and brain. In a preliminary experiment in a mouse xenograft model (mice injected with cells expressing the human A3R; three animals), the animals received [ 18 F]FE rate at SUPPY and [ 18 F]FDG. Dynamic PET imaging was performed (60 min in rats, 90 min in xenografted mice). In vitro stability of [ 18 F]FE rate at SUPPY in human and rat plasma was also evaluated. [ 18 F]FE rate at SUPPY showed high uptake in fat-rich regions and low uptake in the brain. Pretreatment with MRS1523 led to a decrease in [ 18 F]FE rate at SUPPY uptake (p = 0.03), and pretreatment with the P-gp inhibitor tariquidar led to a 1.24-fold increase in [ 18 F]FE rate at SUPPY uptake (p = 0.09) in rat brain. There was no significant difference in metabolites in plasma and brain in the treatment groups. However, plasma concentrations of [ 18 F]FE rate at SUPPY were reduced to levels similar to those in rat brain after blocking. In contrast to [ 18 F]FDG uptake (p = 0.12), the xenograft model showed significantly increased uptake of [ 18 F]FE rate at SUPPY in the tissue masses from CHO cells expressing the human A3R (p = 0.03). [ 18 F]FE rate at SUPPY was stable in human plasma. Selective and

  16. Uridine adenosine tetraphosphate (Up4A) is a strong inductor of smooth muscle cell migration via activation of the P2Y2 receptor and cross-communication to the PDGF receptor

    International Nuclear Information System (INIS)

    Wiedon, Annette; Tölle, Markus; Bastine, Joschika; Schuchardt, Mirjam; Huang, Tao; Jankowski, Vera; Jankowski, Joachim; Zidek, Walter; Giet, Markus van der

    2012-01-01

    Highlights: ► Up 4 A induces VSMC migration. ► VSMC migration towards Up 4 A involves P2Y 2 activation. ► Up 4 A-induced VSMC migration is OPN-dependent. ► Activation of ERK1/2 pathway is necessary for VSMC migration towards Up 4 A. ► Up 4 A-directed VSMC migration cross-communicates with the PDGFR. -- Abstract: The recently discovered dinucleotide uridine adenosine tetraphosphate (Up 4 A) was found in human plasma and characterized as endothelium-derived vasoconstrictive factor (EDCF). A further study revealed a positive correlation between Up 4 A and vascular smooth muscle cell (VSMC) proliferation. Due to the dominant role of migration in the formation of atherosclerotic lesions our aim was to investigate the migration stimulating potential of Up 4 A. Indeed, we found a strong chemoattractant effect of Up 4 A on VSMC by using a modified Boyden chamber. This migration dramatically depends on osteopontin secretion (OPN) revealed by the reduction of the migration signal down to 23% during simultaneous incubation with an OPN-blocking antibody. Due to inhibitory patterns using specific and unspecific purinoreceptor inhibitors, Up 4 A mediates it’s migratory signal mainly via the P2Y 2 . The signaling behind the receptor was investigated with luminex technique and revealed an activation of the extracellular signal-regulated kinases 1 and 2 (ERK1/2) pathway. By use of the specific PDGF receptor (PDGFR) inhibitor AG1296 and siRNA technique against PDGFR-β we found a strongly reduced migration signal after Up 4 A stimulation in the PDGFR-β knockdown cells compared to control cells. In this study, we present substantiate data that Up 4 A exhibits migration stimulating potential probably involving the signaling cascade of MEK1 and ERK1/2 as well as the matrix protein OPN. We further suggest that the initiation of the migration process occurs predominant through direct activation of the P2Y 2 by Up 4 A and via transactivation of the PDGFR.

  17. Genetic deletion of GPR52 enhances the locomotor-stimulating effect of an adenosine A2A receptor antagonist in mice: A potential role of GPR52 in the function of striatopallidal neurons.

    Science.gov (United States)

    Nishiyama, Keiji; Suzuki, Hirobumi; Maruyama, Minoru; Yoshihara, Tomoki; Ohta, Hiroyuki

    2017-09-01

    G protein-coupled receptor 52 (GPR52) is largely co-expressed with dopamine D 2 receptor (DRD2) in the striatum and nucleus accumbens, and this expression pattern is similar to that of adenosine A 2A receptor (ADORA2A). GPR52 has been proposed as a therapeutic target for positive symptoms of schizophrenia, based on observations from pharmacological and transgenic mouse studies. However, the physiological role of GPR52 in dopaminergic functions in the basal ganglia remains unclear. Here, we used GPR52 knockout (KO) mice to examine the role of GPR52 in dopamine receptor-mediated and ADORA2A-mediated locomotor activity and dopamine receptor signaling. High expression of GPR52 protein in the striatum, nucleus accumbens, and lateral globus pallidus of wild type (WT) littermates was confirmed by immunohistochemical analysis. GPR52 KO and WT mice exhibited almost identical locomotor responses to the dopamine releaser methamphetamine and the N-methyl-d-aspartate antagonist MK-801. In contrast, the locomotor response to the ADORA2A antagonist istradefylline was significantly augmented in GPR52 KO mice compared to WT mice. Gene expression analysis revealed that striatal expression of DRD2, but not of dopamine D 1 receptor and ADORA2A, was significantly decreased in GPR52 KO mice. Moreover, a significant reduction in the mRNA expression of enkephalin, a marker of the activity of striatopallidal neurons, was observed in the striatum of GPR52 KO mice, suggesting that GPR52 deletion could enhance DRD2 signaling. Taken together, these results imply the physiological relevance of GPR52 in modulating the function of striatopallidal neurons, possibly by interaction of GPR52 with ADORA2A and DRD2. Copyright © 2017 Elsevier B.V. All rights reserved.

  18. The A2B Adenosine Receptor Modulates the Epithelial– Mesenchymal Transition through the Balance of cAMP/PKA and MAPK/ERK Pathway Activation in Human Epithelial Lung Cells

    Science.gov (United States)

    Giacomelli, Chiara; Daniele, Simona; Romei, Chiara; Tavanti, Laura; Neri, Tommaso; Piano, Ilaria; Celi, Alessandro; Martini, Claudia; Trincavelli, Maria L.

    2018-01-01

    The epithelial-mesenchymal transition (EMT) is a complex process in which cell phenotype switches from the epithelial to mesenchymal one. The deregulations of this process have been related with the occurrence of different diseases such as lung cancer and fibrosis. In the last decade, several efforts have been devoted in understanding the mechanisms that trigger and sustain this transition process. Adenosine is a purinergic signaling molecule that has been involved in the onset and progression of chronic lung diseases and cancer through the A2B adenosine receptor subtype activation, too. However, the relationship between A2BAR and EMT has not been investigated, yet. Herein, the A2BAR characterization was carried out in human epithelial lung cells. Moreover, the effects of receptor activation on EMT were investigated in the absence and presence of transforming growth factor-beta (TGF-β1), which has been known to promote the transition. The A2BAR activation alone decreased and increased the expression of epithelial markers (E-cadherin) and the mesenchymal one (Vimentin, N-cadherin), respectively, nevertheless a complete EMT was not observed. Surprisingly, the receptor activation counteracted the EMT induced by TGF-β1. Several intracellular pathways regulate the EMT: high levels of cAMP and ERK1/2 phosphorylation has been demonstrated to counteract and promote the transition, respectively. The A2BAR stimulation was able to modulated these two pathways, cAMP/PKA and MAPK/ERK, shifting the fine balance toward activation or inhibition of EMT. In fact, using a selective PKA inhibitor, which blocks the cAMP pathway, the A2BAR-mediated EMT promotion were exacerbated, and conversely the selective inhibition of MAPK/ERK counteracted the receptor-induced transition. These results highlighted the A2BAR as one of the receptors involved in the modulation of EMT process. Nevertheless, its activation is not enough to trigger a complete transition, its ability to affect different

  19. The A2B Adenosine Receptor Modulates the Epithelial– Mesenchymal Transition through the Balance of cAMP/PKA and MAPK/ERK Pathway Activation in Human Epithelial Lung Cells

    Directory of Open Access Journals (Sweden)

    Chiara Giacomelli

    2018-01-01

    Full Text Available The epithelial-mesenchymal transition (EMT is a complex process in which cell phenotype switches from the epithelial to mesenchymal one. The deregulations of this process have been related with the occurrence of different diseases such as lung cancer and fibrosis. In the last decade, several efforts have been devoted in understanding the mechanisms that trigger and sustain this transition process. Adenosine is a purinergic signaling molecule that has been involved in the onset and progression of chronic lung diseases and cancer through the A2B adenosine receptor subtype activation, too. However, the relationship between A2BAR and EMT has not been investigated, yet. Herein, the A2BAR characterization was carried out in human epithelial lung cells. Moreover, the effects of receptor activation on EMT were investigated in the absence and presence of transforming growth factor-beta (TGF-β1, which has been known to promote the transition. The A2BAR activation alone decreased and increased the expression of epithelial markers (E-cadherin and the mesenchymal one (Vimentin, N-cadherin, respectively, nevertheless a complete EMT was not observed. Surprisingly, the receptor activation counteracted the EMT induced by TGF-β1. Several intracellular pathways regulate the EMT: high levels of cAMP and ERK1/2 phosphorylation has been demonstrated to counteract and promote the transition, respectively. The A2BAR stimulation was able to modulated these two pathways, cAMP/PKA and MAPK/ERK, shifting the fine balance toward activation or inhibition of EMT. In fact, using a selective PKA inhibitor, which blocks the cAMP pathway, the A2BAR-mediated EMT promotion were exacerbated, and conversely the selective inhibition of MAPK/ERK counteracted the receptor-induced transition. These results highlighted the A2BAR as one of the receptors involved in the modulation of EMT process. Nevertheless, its activation is not enough to trigger a complete transition, its ability to

  20. Adenosine: an activity-dependent axonal signal regulating MAP kinase and proliferation in developing Schwann cells.

    Science.gov (United States)

    Stevens, Beth; Ishibashi, Tomoko; Chen, Jiang-Fan; Fields, R Douglas

    2004-02-01

    Nonsynaptic release of ATP from electrically stimulated dorsal root gangion (DRG) axons inhibits Schwann cell (SC) proliferation and arrests SC development at the premyelinating stage, but the specific types of purinergic receptor(s) and intracellular signaling pathways involved in this form of neuron-glia communication are not known. Recent research shows that adenosine is a neuron-glial transmitter between axons and myelinating glia of the CNS. The present study investigates the possibility that adenosine might have a similar function in communicating between axons and premyelinating SCs. Using a combination of pharmacological and molecular approaches, we found that mouse SCs in culture express functional adenosine receptors and ATP receptors, a far more complex array of purinergic receptors than thought previously. Adenosine, but not ATP, activates ERK/MAPK through stimulation of cAMP-linked A2(A) adenosine receptors. Both ATP and adenosine inhibit proliferation of SCs induced by platelet-derived growth factor (PDGF), via mechanisms that are partly independent. In contrast to ATP, adenosine failed to inhibit the differentiation of SCs to the O4+ stage. This indicates that, in addition to ATP, adenosine is an activity-dependent signaling molecule between axons and premyelinating Schwann cells, but that electrical activity, acting through adenosine, has opposite effects on the differentiation of myelinating glia in the PNS and CNS.

  1. Binding of β4γ5 by adenosine A1 and A2A receptors determined by stable isotope labeling with amino acids in cell culture and mass spectrometry.

    Science.gov (United States)

    Bigler Wang, Dora; Sherman, Nicholas E; Shannon, John D; Leonhardt, Susan A; Mayeenuddin, Linnia H; Yeager, Mark; McIntire, William E

    2011-01-18

    Characterization of G protein βγ dimer isoform expression in different cellular contexts has been impeded by low levels of protein expression, broad isoform heterogeneity, and antibodies of limited specificity, sensitivity, or availability. As a new approach, we used quantitative mass spectrometry to characterize native βγ dimers associated with adenosine A(1):α(i1) and adenosine A(2A):α(S) receptor fusion proteins expressed in HEK-293 cells. Cells expressing A(1):α(i1) were cultured in media containing [(13)C(6)]Arg and [(13)C(6)]Lys and βγ labeled with heavy isotopes purified. Heavy βγ was combined with either recombinant βγ purified from Sf9 cells, βγ purified from the A(2A):α(S) expressed in HEK-293 cells cultured in standard media, or an enriched βγ fraction from HEK-293 cells. Samples were separated by SDS-PAGE, protein bands containing β and γ were excised, digested with trypsin, and separated by HPLC, and isotope ratios were analyzed by mass spectrometry. Three β isoforms, β(1), β(2), and β(4), and seven γ isoforms, γ(2), γ(4), γ(5), γ(7), γ(10), γ(11), and γ(12), were identified in the analysis. β(1) and γ(5) were most abundant in the enriched βγ fraction, and this βγ profile was generally mirrored in the fusion proteins. However, both A(2A):α(S) and A(1):α(i1) bound more β(4) and γ(5) compared to the enriched βγ fraction; also, more β(4) was associated with A(2A):α(S) than A(1):α(i1). Both fusion proteins also contained less γ(2), γ(10), and γ(12) than the enriched βγ fraction. These results suggest that preferences for particular βγ isoforms may be driven in part by structural motifs common to adenosine receptor family members.

  2. Elevated placental adenosine signaling contributes to the pathogenesis of preeclampsia.

    Science.gov (United States)

    Iriyama, Takayuki; Sun, Kaiqi; Parchim, Nicholas F; Li, Jessica; Zhao, Cheng; Song, Anren; Hart, Laura A; Blackwell, Sean C; Sibai, Baha M; Chan, Lee-Nien L; Chan, Teh-Sheng; Hicks, M John; Blackburn, Michael R; Kellems, Rodney E; Xia, Yang

    2015-02-24

    Preeclampsia is a prevalent hypertensive disorder of pregnancy and a leading cause of maternal and neonatal morbidity and mortality worldwide. This pathogenic condition is speculated to be caused by placental abnormalities that contribute to the maternal syndrome. However, the specific factors and signaling pathways that lead to impaired placentas and maternal disease development remain elusive. Using 2 independent animal models of preeclampsia (genetically engineered pregnant mice with elevated adenosine exclusively in placentas and a pathogenic autoantibody-induced preeclampsia mouse model), we demonstrated that chronically elevated placental adenosine was sufficient to induce hallmark features of preeclampsia, including hypertension, proteinuria, small fetuses, and impaired placental vasculature. Genetic and pharmacological approaches revealed that elevated placental adenosine coupled with excessive A₂B adenosine receptor (ADORA2B) signaling contributed to the development of these features of preeclampsia. Mechanistically, we provided both human and mouse evidence that elevated placental CD73 is a key enzyme causing increased placental adenosine, thereby contributing to preeclampsia. We determined that elevated placental adenosine signaling is a previously unrecognized pathogenic factor for preeclampsia. Moreover, our findings revealed the molecular basis underlying the elevation of placental adenosine and the detrimental role of excess placental adenosine in the pathophysiology of preeclampsia, and thereby, we highlight novel therapeutic targets. © 2014 American Heart Association, Inc.

  3. Infection-induced coronary dysfunction and systemic inflammation in piglets are dampened in hypercholesterolemic milieu

    DEFF Research Database (Denmark)

    Birck, Malene M.; Pesonen, Erkki; Odermarsky, Michal

    2011-01-01

    The synergism of infection with conventional cardiovascular risk factors in atherosclerosis is much debated. We hypothesized that coronary arterial injury correlates with infection recurrence and pathogen burden and is further aggravated by hypercholesterolemia. Forty-two Göttingen minipigs were ...... = 0.08). Coinfection of piglets appears to be associated with more pronounced coronary muscarinic vasomotor dysfunction. In monoinfected animals, use of chol-diet seems to dampen both coronary dysfunction and systemic inflammation induced by infection....... assigned to repeated intratracheal inoculation of PBS, Chlamydia pneumoniae (Cpn), or both Cpn and influenza virus at 8, 11, and 14 wk of age. Animals were fed either standard or 2% cholesterol diet (chol-diet). At 19 wk of age coronary vasomotor responses to acetylcholine (ACh) and adenosine were assessed...... in vivo and blood and tissue samples were collected. Nonparametric tests were used to compare the groups. In cholesterol-fed animals, total cholesterol/HDL was significantly increased in infected animals compared with noninfected animals [3.13 (2.17–3.38) vs. 2.03 (1.53–2.41), respectively; P = 0.01]. C...

  4. Sustained Elevated Adenosine via ADORA2B Promotes Chronic Pain through Neuro-immune Interaction

    Directory of Open Access Journals (Sweden)

    Xia Hu

    2016-06-01

    Full Text Available The molecular mechanisms of chronic pain are poorly understood and effective mechanism-based treatments are lacking. Here, we report that mice lacking adenosine deaminase (ADA, an enzyme necessary for the breakdown of adenosine, displayed unexpected chronic mechanical and thermal hypersensitivity due to sustained elevated circulating adenosine. Extending from Ada−/− mice, we further discovered that prolonged elevated adenosine contributed to chronic pain behaviors in two additional independent animal models: sickle cell disease mice, a model of severe pain with limited treatment, and complete Freund’s adjuvant paw-injected mice, a well-accepted inflammatory model of chronic pain. Mechanistically, we revealed that activation of adenosine A2B receptors on myeloid cells caused nociceptor hyperexcitability and promoted chronic pain via soluble IL-6 receptor trans-signaling, and our findings determined that prolonged accumulated circulating adenosine contributes to chronic pain by promoting immune-neuronal interaction and revealed multiple therapeutic targets.

  5. [(3)H]8-Ethyl-4-methyl-2-phenyl-(8R)-4,5,7,8-tetrahydro-1H-imidazo[2,1-i]-purin-5-one ([(3)H]PSB-11), a novel high-affinity antagonist radioligand for human A(3) adenosine receptors.

    Science.gov (United States)

    Müller, Christa E; Diekmann, Martina; Thorand, Mark; Ozola, Vita

    2002-02-11

    This study describes the preparation and binding properties of [(3)H]PSB-11, a novel, potent, and selective antagonist radioligand for human A(3) adenosine receptors (ARs). [(3)H]PSB-11 binding to membranes of Chinese hamster ovary (CHO) cells expressing the human A(3) AR was saturable and reversible. Saturation experiments showed that [(3)H]PSB-11 labeled a single class of binding sites with high affinity (K(D)=4.9 nM) and limited capacity (B(max)=3500 fmol/mg of protein). PSB-11 is highly selective versus the other adenosine receptor subtypes. The new radioligand shows an extraordinarily low degree of non-specific binding rendering it a very useful tool for studying the (patho)physiological roles of A(3 )ARs.

  6. Traditional Acupuncture Triggers a Local Increase in Adenosine in Human Subjects

    OpenAIRE

    Takano, Takahiro; Chen, Xiaolin; Luo, Fang; Fujita, Takumi; Ren, Zeguang; Goldman, Nanna; Zhao, Yuanli; Markman, John D.; Nedergaard, Maiken

    2012-01-01

    Acupuncture is a form of Eastern medicine that has been practiced for centuries. Despite its long history and worldwide application, the biological mechanisms of acupuncture in relieving pain have been poorly defined. Recent studies in mice, however, demonstrate that acupuncture triggers increases in interstitial adenosine, which reduces the severity of chronic pain through adenosine A1 receptors, suggesting that adenosine-mediated antinociception contributes to the clinical benefits of acupu...

  7. Adenosine: a putative mediator of bronchoconstriction in asthma

    Energy Technology Data Exchange (ETDEWEB)

    Mann, J.S.

    1987-01-01

    The protective effect of a muscarinic cholinergic antagonists, ipratropium bromide (IB) from inhaled adenosine- and methacholine-induced bronchoconstriction in asthma was studied. Inhaled IB protected from methacholine- but not adenosine-induced bronchoconstriction. Parasympathetically mediated bronchoconstriction is therefore unlikely to account for adenosine's airway effect in asthma. The capacity of theophylline, a bronchodilator and a competitive antagonist of adenosine at its cell surface receptors, to protect asthmatic subjects from adenosine- and histamine-induced bronchoconstriction was determined. Asthmatic airways are infiltrated with inflammatory cells. Human leucocytes prelabeled with (/sup 3/H)-adenine when activated with the calcium ionophore A23187 released labelled hypoxanthine, inosine and adenosine which was associated with a dose-related release of histamine. The chemotactic peptide f-MLP while inducing histamine release had an inconstant effect on release of label. In four of five experiments f-MLP produced a transient early increase in label release but in the remaining experiment no significant release was observed. Anti-human IgE failed to induce significant label release despite releasing histamine. Activated leucocytes are therefore a potential source of adenosine in asthma.

  8. Endogenous adenosine produced during hypoxia attenuates neutrophil accumulation: coordination by extracellular nucleotide metabolism.

    Science.gov (United States)

    Eltzschig, Holger K; Thompson, Linda F; Karhausen, Jorn; Cotta, Richard J; Ibla, Juan C; Robson, Simon C; Colgan, Sean P

    2004-12-15

    Hypoxia is a well-documented inflammatory stimulus and results in tissue polymorphonuclear leukocyte (PMN) accumulation. Likewise, increased tissue adenosine levels are commonly associated with hypoxia, and given the anti-inflammatory properties of adenosine, we hypothesized that adenosine production via adenine nucleotide metabolism at the vascular surface triggers an endogenous anti-inflammatory response during hypoxia. Initial in vitro studies indicated that endogenously generated adenosine, through activation of PMN adenosine A(2A) and A(2B) receptors, functions as an antiadhesive signal for PMN binding to microvascular endothelia. Intravascular nucleotides released by inflammatory cells undergo phosphohydrolysis via hypoxia-induced CD39 ectoapyrase (CD39 converts adenosine triphosphate/adenosine diphosphate [ATP/ADP] to adenosine monophosphate [AMP]) and CD73 ecto-5'-nucleotidase (CD73 converts AMP to adenosine). Extensions of our in vitro findings using cd39- and cd73-null animals revealed that extracellular adenosine produced through adenine nucleotide metabolism during hypoxia is a potent anti-inflammatory signal for PMNs in vivo. These findings identify CD39 and CD73 as critical control points for endogenous adenosine generation and implicate this pathway as an innate mechanism to attenuate excessive tissue PMN accumulation.

  9. 3-(Fur-2-yl)-10-(2-phenylethyl)-[1,2,4]triazino[4,3-a]benzimidazol-4(10H)-one, a novel adenosine receptor antagonist with A(2A)-mediated neuroprotective effects.

    Science.gov (United States)

    Scatena, Alessia; Fornai, Francesco; Trincavelli, Maria Letizia; Taliani, Sabrina; Daniele, Simona; Pugliesi, Isabella; Cosconati, Sandro; Martini, Claudia; Da Settimo, Federico

    2011-09-21

    In this study, compound FTBI (3-(2-furyl)-10-(2-phenylethyl)[1,2,4]triazino[4,3-a]benzimidazol-4(10H)-one) was selected from a small library of triazinobenzimidazole derivatives as a potent A(2A) adenosine receptor (AR) antagonist and tested for its neuroprotective effects against two different kinds of dopaminergic neurotoxins, 1-methyl-4-phenylpyridinium (MPP+) and methamphetamine (METH), in rat PC12 and in human neuroblastoma SH-SY5Y cell lines. FTBI, in a concentration range corresponding to its affinity for A(2A) AR subtype, significantly increased the number of viable PC12 cells after their exposure to METH and, to a similar extent, to MPP+, as demonstrated in both trypan blue exclusion assay and in cytological staining. These neuroprotective effects were also observed with a classical A(2A) AR antagonist, ZM241385, and appeared to be completely counteracted by the AR agonist, NECA, supporting A(2A) ARs are directly involved in FTBI-mediated effects. Similarly, in human SH-SY5Y cells, FTBI was able to prevent cell toxicity induced by MPP+ and METH, showing that this A(2A) AR antagonist has a neuroprotective effect independently by the specific cell model. Altogether these results demonstrate that the A(2A) AR blockade mediates cell protection against neurotoxicity induced by dopaminergic neurotoxins in dopamine containing cells, supporting the potential use of A(2A) AR antagonists in dopaminergic degenerative diseases including Parkinson's disease.

  10. Radiosynthesis of a novel potential adenosine A{sub 3} receptor ligand, 5-ethyl 2,4-diethyl-3-((2-[{sup 18}F]fluoroethyl)sulfanylcarbonyl)-6-phenylpyridine-5-carboxylate ([{sup 18}F]FE rate at SUPPY:2)

    Energy Technology Data Exchange (ETDEWEB)

    Haeusler, D. [Dept. of Nuclear Medicine, Medical Univ. of Vienna (Austria); Dept. of Pharmaceutical Tech. and Biopharmaceutics, Univ. of Vienna (Austria); Mitterhauser, M. [Dept. of Nuclear Medicine, Medical Univ. of Vienna (Austria); Dept. of Pharmaceutical Tech. and Biopharmaceutics, Univ. of Vienna (Austria); Hospital Pharmacy of the General Hospital of Vienna (Austria); Mien, L.K. [Dept. of Nuclear Medicine, Medical Univ. of Vienna (Austria); Dept. of Pharmaceutical Tech. and Biopharmaceutics, Univ. of Vienna (Austria); Dept. of Psychiatry and Psychotherapy, Medical Univ. of Vienna (Austria); Shanab, K.; Spreitzer, H. [Dept. of Drug and Natural Product Synthesis, Univ. of Vienna (Austria); Lanzenberger, R.R [Dept. of Psychiatry and Psychotherapy, Medical Univ. of Vienna (Austria); Schirmer, E. [Dept. of Nuclear Medicine, Medical Univ. of Vienna (Austria); Dept. of Drug and Natural Product Synthesis, Univ. of Vienna (Austria); Ungersboeck, J.; Wadsak, W. [Dept. of Nuclear Medicine, Medical Univ. of Vienna (Austria); Dept. of Inorganic Chemistry, Univ. of Vienna (Austria); Nics, L. [Dept. of Nuclear Medicine, Medical Univ. of Vienna (Austria); Dept. of Nutritional Sciences, Univ. of Vienna (Austria); Viernstein, H. [Dept. of Pharmaceutical Tech. and Biopharmaceutics, Univ. of Vienna (Austria); Dudezak, R.; Kletter, K. [Dept. of Nuclear Medicine, Medical Univ. of Vienna (Austria)

    2009-07-01

    Since, to date very limited information on the distribution and function of the adenosine A{sub 3} receptor is available, the development of suitable radioligands is needed. Recently, we introduced [{sup 18}F]FE rate at SUPPY (5-(2-[{sup 18}F]fluoroethyl) 2,4-diethyl-3-(ethylsulfanylcarbonyl)-6-phenylpyridine-5-carboxylate) as the first PET-ligand for the A3R. Regarding the metabolic profile - this class of dialkylpyridines comprises two ester functions within one molecule, one carboxylic and one thiocarboxylic - one could expect carboxylesterases significantly contributing to cleavage and degradation. Therefore, our aim was the development of [{sup 18}F]FE rate at SUPPY:2 (5-ethyl 2,4-diethyl-3-((2-[{sup 18}F]fluoroethyl)sulfanylcarbonyl)-6-phenylpyridine-5-carboxylate), the functional isomer containing the label at the thiocarboxylic moiety. For satisfactory yields in high scale radiosyntheses, a reaction temperature of 75 C has to be applied for at least 20 min using 20 mg/mL of precursor. So far, 6 complete high-scale radiosyntheses were performed. Starting from an average of 51.2 {+-} 21.8 GBq (mean{+-}SD) [{sup 18}F]fluoride, 5.8 {+-} 4.1 GBq of formulated [{sup 18}F]FE rate at SUPPY:2 (12.0{+-}5.4%, based on [{sup 18}F]fluoride, not corrected for decay) were prepared in 75 {+-} 8 min. (orig.)

  11. Radiosynthesis of the adenosine A3 receptor ligand 5-(2-[18F]fluoroethyl) 2,4-diethyl-3-(ethylsulfanylcarbonyl)-6-phenylpyridine-5-carboxylate ([18F]FE rate at SUPPY)

    International Nuclear Information System (INIS)

    Wadsak, W.; Mien, L.K.; Shanab, K.; Spreitzer, H.; Weber, K.; Schmidt, B.; Haeusler, D.; Sindelar, K.M.; Ettlinger, D.E.; Dudczak, R.; Kletter, K.; Keppler, B.K.; Viernstein, H.; Mitterhauser, M.

    2008-01-01

    Since to date very limited information on the distribution and function of the adenosine A 3 receptor is available, the development of a suitable radioligand is needed. Such a selective radioligand can then be used for quantitative autoradiography, preclinical studies in animals and subsequent human PET applications. Recently, a promising candidate compound, 5-(2-fluoroethyl) 2,4-diethyl-3-(ethylsulfanylcarbonyl)-6-phenylpyridine-5-carboxylate (FE rate at SUPPY), has been presented. The successful preparation of a suitable labelling precursor and the evaluation and optimization of the radiosynthesis of [ 18 F]FE rate at SUPPY is presented herewith. For satisfactory yields, a reaction temperature of 75 C has to be applied for at least 20 min using 8-10 mg of precursor. Until now, 15 complete high-scale radiosyntheses were performed. Starting from an average of 51 ± 12 GBq (average ±SD; range: 30-67 GBq) [ 18 F]fluoride, 9.4 ± 3.6 GBq of formulated [ 18 F]FE rate at SUPPY (32.3 ± 12.4%, based on [ 18 F]fluoride, corrected for decay) were prepared in < 105 min. (orig.)

  12. Radiosynthesis of a novel potential adenosine A3 receptor ligand, 5-ethyl 2,4-diethyl-3-((2-[18F]fluoroethyl)sulfanylcarbonyl) -6-phenylpyridine-5-carbox ylate ([18F]FE rate at SUPPY:2)

    International Nuclear Information System (INIS)

    Haeusler, D.; Mitterhauser, M.; Mien, L.K.; Shanab, K.; Spreitzer, H.; Lanzenberger, R.R; Schirmer, E.; Ungersboeck, J.; Wadsak, W.; Nics, L.; Viernstein, H.; Dudezak, R.; Kletter, K.

    2009-01-01

    Since, to date very limited information on the distribution and function of the adenosine A 3 receptor is available, the development of suitable radioligands is needed. Recently, we introduced [ 18 F]FE rate at SUPPY (5-(2-[ 18 F]fluoroethyl) 2,4-diethyl-3-(ethylsulfanylcarbonyl)-6-phenylpyridine-5-carboxylate) as the first PET-ligand for the A3R. Regarding the metabolic profile - this class of dialkylpyridines comprises two ester functions within one molecule, one carboxylic and one thiocarboxylic - one could expect carboxylesterases significantly contributing to cleavage and degradation. Therefore, our aim was the development of [ 18 F]FE rate at SUPPY:2 (5-ethyl 2,4-diethyl-3-((2-[ 18 F]fluoroethyl)sulfanylcarbonyl)-6-phenylpyridine -5-carbox ylate), the functional isomer containing the label at the thiocarboxylic moiety. For satisfactory yields in high scale radiosyntheses, a reaction temperature of 75 C has to be applied for at least 20 min using 20 mg/mL of precursor. So far, 6 complete high-scale radiosyntheses were performed. Starting from an average of 51.2 ± 21.8 GBq (mean±SD) [ 18 F]fluoride, 5.8 ± 4.1 GBq of formulated [ 18 F]FE rate at SUPPY:2 (12.0±5.4%, based on [ 18 F]fluoride, not corrected for decay) were prepared in 75 ± 8 min. (orig.)

  13. Radiosynthesis of the adenosine A{sub 3} receptor ligand 5-(2-[{sup 18}F]fluoroethyl) 2,4-diethyl-3-(ethylsulfanylcarbonyl)-6-phenylpyridine-5-carboxylate ([{sup 18}F]FE rate at SUPPY)

    Energy Technology Data Exchange (ETDEWEB)

    Wadsak, W. [Dept. of Nuclear Medicine, Medical Univ. of Vienna (Austria); Dept. of Inorganic Chemistry, Univ. of Vienna (Austria); Mien, L.K. [Dept. of Nuclear Medicine, Medical Univ. of Vienna (Austria); Dept. of Pharmaceutical Technology and Biopharmaceutics, Univ. of Vienna (Austria); Dept. of Psychiatry and Psychotherapy, Medical Univ. of Vienna (Austria); Shanab, K.; Spreitzer, H. [Dept. of Psychiatry and Psychotherapy, Medical Univ. of Vienna (Austria); Weber, K.; Schmidt, B.; Haeusler, D. [Dept. of Nuclear Medicine, Medical Univ. of Vienna (Austria); Dept. of Pharmaceutical Technology and Biopharmaceutics, Univ. of Vienna (Austria); Sindelar, K.M.; Ettlinger, D.E.; Dudczak, R.; Kletter, K. [Dept. of Nuclear Medicine, Medical Univ. of Vienna (Austria); Keppler, B.K.; Viernstein, H. [Dept. of Inorganic Chemistry, Univ. of Vienna (Austria); Mitterhauser, M. [Dept. of Nuclear Medicine, Medical Univ. of Vienna (Austria); Dept. of Pharmaceutical Technology and Biopharmaceutics, Univ. of Vienna (Austria); Hospital Pharmacy of the General Hospital of Vienna (Austria)

    2008-07-01

    Since to date very limited information on the distribution and function of the adenosine A{sub 3} receptor is available, the development of a suitable radioligand is needed. Such a selective radioligand can then be used for quantitative autoradiography, preclinical studies in animals and subsequent human PET applications. Recently, a promising candidate compound, 5-(2-fluoroethyl) 2,4-diethyl-3-(ethylsulfanylcarbonyl)-6-phenylpyridine-5-carboxylate (FE rate at SUPPY), has been presented. The successful preparation of a suitable labelling precursor and the evaluation and optimization of the radiosynthesis of [{sup 18}F]FE rate at SUPPY is presented herewith. For satisfactory yields, a reaction temperature of 75 C has to be applied for at least 20 min using 8-10 mg of precursor. Until now, 15 complete high-scale radiosyntheses were performed. Starting from an average of 51 {+-} 12 GBq (average {+-}SD; range: 30-67 GBq) [{sup 18}F]fluoride, 9.4 {+-} 3.6 GBq of formulated [{sup 18}F]FE rate at SUPPY (32.3 {+-} 12.4%, based on [{sup 18}F]fluoride, corrected for decay) were prepared in < 105 min. (orig.)

  14. Striatal adenosine A2A receptor-mediated positron emission tomographic imaging in 6-hydroxydopamine-lesioned rats using [18F]-MRS5425

    International Nuclear Information System (INIS)

    Bhattacharjee, Abesh Kumar; Lang Lixin; Jacobson, Orit; Shinkre, Bidhan; Ma Ying; Niu Gang; Trenkle, William C.; Jacobson, Kenneth A.; Chen Xiaoyuan; Kiesewetter, Dale O.

    2011-01-01

    Introduction: A 2A receptors are expressed in the basal ganglia, specifically in striatopallidal GABAergic neurons in the striatum (caudate-putamen). This brain region undergoes degeneration of presynaptic dopamine projections and depletion of dopamine in Parkinson's disease. We developed an 18 F-labeled A 2A analog radiotracer ([ 18 F]-MRS5425) for A 2A receptor imaging using positron emission tomography (PET). We hypothesized that this tracer could image A 2A receptor changes in the rat model for Parkinson's disease, which is created following unilateral injection of the monoaminergic toxin 6-hydroxydopamine (6-OHDA) into the substantia nigra. Methods: [ 18 F]-MRS5425 was injected intravenously in anesthetized rats, and PET imaging data were collected. Image-derived percentage injected doses per gram (%ID/g) in regions of interest was measured in the striatum of normal rats and in rats unilaterally lesioned with 6-OHDA after intravenous administration of saline (baseline), D 2 agonist quinpirole (1.0 mg/kg) or D 2 antagonist raclopride (6.0 mg/kg). Results: Baseline %ID/g reached a maximum at 90 s and maintained plateau for 3.5 min, and then declined slowly thereafter. In 6-OHDA-lesioned rats, %ID/g was significantly higher in the lesioned side compared to the intact side, and the baseline total %ID/g (data from both hemispheres were combined) was significantly higher compared to quinpirole stimulation starting from 4.5 min until the end of acquisition at 30 min. Raclopride did not produce any change in uptake compared to baseline or between the hemispheres. Conclusion: Thus, increase of A 2A receptor-mediated uptake of radioactive MRS5425 could be a superior molecular target for Parkinson's imaging.

  15. Striatal adenosine A{sub 2A} receptor-mediated positron emission tomographic imaging in 6-hydroxydopamine-lesioned rats using [{sup 18}F]-MRS5425

    Energy Technology Data Exchange (ETDEWEB)

    Bhattacharjee, Abesh Kumar; Lang Lixin; Jacobson, Orit [Laboratory of Molecular Imaging and Nanomedicine, National Institute of Biomedical Imaging and Bioengineering, National Institutes of Health, Bethesda, MD 20892 (United States); Shinkre, Bidhan [Chemical Biology Unit, Laboratory of Cell Biochemistry and Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892 (United States); Ma Ying [Laboratory of Molecular Imaging and Nanomedicine, National Institute of Biomedical Imaging and Bioengineering, National Institutes of Health, Bethesda, MD 20892 (United States); Niu Gang [Laboratory of Molecular Imaging and Nanomedicine, National Institute of Biomedical Imaging and Bioengineering, National Institutes of Health, Bethesda, MD 20892 (United States); Department of Radiology and Imaging Sciences, Warren Grant Magnuson Clinical Center, National Institutes of Health, Bethesda, MD 20892 (United States); Trenkle, William C. [Chemical Biology Unit, Laboratory of Cell Biochemistry and Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892 (United States); Jacobson, Kenneth A. [Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892 (United States); Chen Xiaoyuan [Laboratory of Molecular Imaging and Nanomedicine, National Institute of Biomedical Imaging and Bioengineering, National Institutes of Health, Bethesda, MD 20892 (United States); Kiesewetter, Dale O., E-mail: dk7k@nih.gov [Laboratory of Molecular Imaging and Nanomedicine, National Institute of Biomedical Imaging and Bioengineering, National Institutes of Health, Bethesda, MD 20892 (United States)

    2011-08-15

    Introduction: A{sub 2A} receptors are expressed in the basal ganglia, specifically in striatopallidal GABAergic neurons in the striatum (caudate-putamen). This brain region undergoes degeneration of presynaptic dopamine projections and depletion of dopamine in Parkinson's disease. We developed an {sup 18}F-labeled A{sub 2A} analog radiotracer ([{sup 18}F]-MRS5425) for A{sub 2A} receptor imaging using positron emission tomography (PET). We hypothesized that this tracer could image A{sub 2A} receptor changes in the rat model for Parkinson's disease, which is created following unilateral injection of the monoaminergic toxin 6-hydroxydopamine (6-OHDA) into the substantia nigra. Methods: [{sup 18}F]-MRS5425 was injected intravenously in anesthetized rats, and PET imaging data were collected. Image-derived percentage injected doses per gram (%ID/g) in regions of interest was measured in the striatum of normal rats and in rats unilaterally lesioned with 6-OHDA after intravenous administration of saline (baseline), D{sub 2} agonist quinpirole (1.0 mg/kg) or D{sub 2} antagonist raclopride (6.0 mg/kg). Results: Baseline %ID/g reached a maximum at 90 s and maintained plateau for 3.5 min, and then declined slowly thereafter. In 6-OHDA-lesioned rats, %ID/g was significantly higher in the lesioned side compared to the intact side, and the baseline total %ID/g (data from both hemispheres were combined) was significantly higher compared to quinpirole stimulation starting from 4.5 min until the end of acquisition at 30 min. Raclopride did not produce any change in uptake compared to baseline or between the hemispheres. Conclusion: Thus, increase of A{sub 2A} receptor-mediated uptake of radioactive MRS5425 could be a superior molecular target for Parkinson's imaging.

  16. Adenosine Inhibits the Excitatory Synaptic Inputs to Basal Forebrain Cholinergic, GABAergic and Parvalbumin Neurons in mice

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    Chun eYang

    2013-06-01

    Full Text Available Coffee and tea contain the stimulants caffeine and theophylline. These compounds act as antagonists of adenosine receptors. Adenosine promotes sleep and its extracellular concentration rises in association with prolonged wakefulness, particularly in the basal forebrain (BF region involved in activating the cerebral cortex. However, the effect of adenosine on identified BF neurons, especially non-cholinergic neurons, is incompletely understood. Here we used whole-cell patch-clamp recordings in mouse brain slices prepared from two validated transgenic mouse lines with fluorescent proteins expressed in GABAergic or parvalbumin (PV neurons to determine the effect of adenosine. Whole-cell recordings were made BF cholinergic neurons and from BF GABAergic & PV neurons with the size (>20 µm and intrinsic membrane properties (prominent H-currents corresponding to cortically projecting neurons. A brief (2 min bath application of adenosine (100 μM decreased the frequency but not the amplitude of spontaneous excitatory postsynaptic currents in all groups of BF cholinergic, GABAergic and PV neurons we recorded. In addition, adenosine decreased the frequency of miniature EPSCs in BF cholinergic neurons. Adenosine had no effect on the frequency of spontaneous inhibitory postsynaptic currents in cholinergic neurons or GABAergic neurons with large H-currents but reduced them in a group of GABAergic neurons with smaller H-currents. All effects of adenosine were blocked by a selective, adenosine A1 receptor antagonist, cyclopentyltheophylline (CPT, 1 μM. Adenosine had no postsynaptic effects. Taken together, our work suggests that adenosine promotes sleep by an A1-receptor mediated inhibition of glutamatergic inputs to cortically-projecting cholinergic and GABA/PV neurons. Conversely, caffeine and theophylline promote attentive wakefulness by inhibiting these A1 receptors in BF thereby promoting the high-frequency oscillations in the cortex required for

  17. Feed-Forward Inhibition of CD73 and Upregulation of Adenosine Deaminase Contribute to the Loss of Adenosine Neuromodulation in Postinflammatory Ileitis

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    Cátia Vieira

    2014-01-01

    Full Text Available Purinergic signalling is remarkably plastic during gastrointestinal inflammation. Thus, selective drugs targeting the “purinome” may be helpful for inflammatory gastrointestinal diseases. The myenteric neuromuscular transmission of healthy individuals is fine-tuned and controlled by adenosine acting on A2A excitatory receptors. Here, we investigated the neuromodulatory role of adenosine in TNBS-inflamed longitudinal muscle-myenteric plexus of the rat ileum. Seven-day postinflammation ileitis lacks adenosine neuromodulation, which may contribute to acceleration of gastrointestinal transit. The loss of adenosine neuromodulation results from deficient accumulation of the nucleoside at the myenteric synapse despite the fact that the increases in ATP release were observed. Disparity between ATP outflow and adenosine deficit in postinflammatory ileitis is ascribed to feed-forward inhibition of ecto-5′-nucleotidase/CD73 by high extracellular ATP and/or ADP. Redistribution of NTPDase2, but not of NTPDase3, from ganglion cell bodies to myenteric nerve terminals leads to preferential ADP accumulation from released ATP, thus contributing to the prolonged inhibition of muscle-bound ecto-5′-nucleotidase/CD73 and to the delay of adenosine formation at the inflamed neuromuscular synapse. On the other hand, depression of endogenous adenosine accumulation may also occur due to enhancement of adenosine deaminase activity. Both membrane-bound and soluble forms of ecto-5′-nucleotidase/CD73 and adenosine deaminase were detected in the inflamed myenteric plexus. These findings provide novel therapeutic targets for inflammatory gut motility disorders.

  18. Acute hyperammonemia and systemic inflammation is associated with increased extracellular brain adenosine in rats

    DEFF Research Database (Denmark)

    Bjerring, Peter Nissen; Dale, Nicholas; Larsen, Fin Stolze

    2015-01-01

    ) and cerebral blood flow (CBF). We measured the adenosine concentration with biosensors in rat brain slices exposed to ammonia and in a rat model with hyperammonemia and systemic inflammation. Exposure to ammonia in concentrations from 0.15-10 mM led to increases in the cortical adenosine concentration up to 18......Acute liver failure (ALF) can lead to brain edema, cerebral hyperperfusion and intracranial hypertension. These complications are thought to be mediated by hyperammonemia and inflammation leading to altered brain metabolism. As increased levels of adenosine degradation products have been found...... in brain tissue of patients with ALF we investigated whether hyperammonemia could induce adenosine release in brain tissue. Since adenosine is a potent vasodilator and modulator of cerebral metabolism we furthermore studied the effect of adenosine receptor ligands on intracranial pressure (ICP...

  19. Contraction induced secretion of VEGF from skeletal muscle cells is mediated by adenosine

    DEFF Research Database (Denmark)

    Høier, Birgitte; Olsen, Karina; Nyberg, Michael Permin

    2010-01-01

    and that the contraction induced secretion of VEGF is partially mediated via adenosine acting on A(2B) adenosine receptors. Moreover, the contraction induced secretion of VEGF protein from muscle is dependent on both PKA and MAPK activation, but only the MAPK pathway appears to be adenosine dependent.......The role of adenosine and contraction for secretion of VEGF in skeletal muscle was investigated in human subjects and rat primary skeletal muscle cells. Microdialysis probes were inserted into the thigh muscle of seven male subjects and dialysate was collected at rest, during infusion of adenosine...... and contraction caused secretion of VEGF (pcontraction induced secretion of VEGF protein was abolished by the A(2B) antagonist enprofyllin and markedly reduced by inhibition of PKA or MAPK. The results demonstrate that adenosine causes secretion of VEGF from human skeletal muscle cells...

  20. Detrimental effects of adenosine signaling in sickle cell disease

    Science.gov (United States)

    Zhang, Yujin; Dai, Yingbo; Wen, Jiaming; Zhang, Weiru; Grenz, Almut; Sun, Hong; Tao, Lijian; Lu, Guangxiu; Alexander, Danny C; Milburn, Michael V; Carter-Dawson, Louvenia; Lewis, Dorothy E; Zhang, Wenzheng; Eltzschig, Holger K; Kellems, Rodney E; Blackburn, Michael R; Juneja, Harinder S; Xia, Yang

    2016-01-01

    Hypoxia can act as an initial trigger to induce erythrocyte sickling and eventual end organ damage in sickle cell disease (SCD). Many factors and metabolites are altered in response to hypoxia and may contribute to the pathogenesis of the disease. Using metabolomic profiling, we found that the steady-state concentration of adenosine in the blood was elevated in a transgenic mouse model of SCD. Adenosine concentrations were similarly elevated in the blood of humans with SCD. Increased adenosine levels promoted sickling, hemolysis and damage to multiple tissues in SCD transgenic mice and promoted sickling of human erythrocytes. Using biochemical, genetic and pharmacological approaches, we showed that adenosine A2B receptor (A2BR)-mediated induction of 2,3-diphosphoglycerate, an erythrocyte-specific metabolite that decreases the oxygen binding affinity of hemoglobin, underlies the induction of erythrocyte sickling by excess adenosine both in cultured human red blood cells and in SCD transgenic mice. Thus, excessive adenosine signaling through the A2BR has a pathological role in SCD. These findings may provide new therapeutic possibilities for this disease. PMID:21170046

  1. An Adenosine-Mediated Glial-Neuronal Circuit for Homeostatic Sleep.

    Science.gov (United States)

    Bjorness, Theresa E; Dale, Nicholas; Mettlach, Gabriel; Sonneborn, Alex; Sahin, Bogachan; Fienberg, Allen A; Yanagisawa, Masashi; Bibb, James A; Greene, Robert W

    2016-03-30

    Sleep homeostasis reflects a centrally mediated drive for sleep, which increases during waking and resolves during subsequent sleep. Here we demonstrate that mice deficient for glial adenosine kinase (AdK), the primary metabolizing enzyme for adenosine (Ado), exhibit enhanced expression of this homeostatic drive by three independent measures: (1) increased rebound of slow-wave activity; (2) increased consolidation of slow-wave sleep; and (3) increased time constant of slow-wave activity decay during an average slow-wave sleep episode, proposed and validated here as a new index for homeostatic sleep drive. Conversely, mice deficient for the neuronal adenosine A1 receptor exhibit significantly decreased sleep drive as judged by these same indices. Neuronal knock-out of AdK did not influence homeostatic sleep need. Together, these findings implicate a glial-neuronal circuit mediated by intercellular Ado, controlling expression of homeostatic sleep drive. Because AdK is tightly regulated by glial metabolic state, our findings suggest a functional link between cellular metabolism and sleep homeostasis. The work presented here provides evidence for an adenosine-mediated regulation of sleep in response to waking (i.e., homeostatic sleep need), requiring activation of neuronal adenosine A1 receptors and controlled by glial adenosine kinase. Adenosine kinase acts as a highly sensitive and important metabolic sensor of the glial ATP/ADP and AMP ratio directly controlling intracellular adenosine concentration. Glial equilibrative adenosine transporters reflect the intracellular concentration to the extracellular milieu to activate neuronal adenosine receptors. Thus, adenosine mediates a glial-neuronal circuit linking glial metabolic state to neural-expressed sleep homeostasis. This indicates a metabolically related function(s) for this glial-neuronal circuit in the buildup and resolution of our need to sleep and suggests potential therapeutic targets more directly related to

  2. Skeletal muscle expresses the extracellular cyclic AMP–adenosine pathway

    Science.gov (United States)

    Chiavegatti, T; Costa, V L; Araújo, M S; Godinho, R O

    2007-01-01

    Background and purpose: cAMP is a key intracellular signalling molecule that regulates multiple processes of the vertebrate skeletal muscle. We have shown that cAMP can be actively pumped out from the skeletal muscle cell. Since in other tissues, cAMP efflux had been associated with extracellular generation of adenosine, in the present study we have assessed the fate of interstitial cAMP and the existence of an extracellular cAMP-adenosine signalling pathway in skeletal muscle. Experimental approach: cAMP efflux and/or its extracellular degradation were analysed by incubating rat cultured skeletal muscle with exogenous cAMP, forskolin or isoprenaline. cAMP and its metabolites were quantified by radioassay or HPLC, respectively. Key results: Incubation of cells with exogenous cAMP was followed by interstitial accumulation of 5′-AMP and adenosine, a phenomenon inhibited by selective inhibitors of ecto-phosphodiesterase (DPSPX) and ecto-nucleotidase (AMPCP). Activation of adenylyl cyclase (AC) in cultured cells with forskolin or isoprenaline increased cAMP efflux and extracellular generation of 5′-AMP and adenosine. Extracellular cAMP-adenosine pathway was also observed after direct and receptor-dependent stimulation of AC in rat extensor muscle ex vivo. These events were attenuated by probenecid, an inhibitor of ATP binding cassette family transporters. Conclusions and implications: Our results show the existence of an extracellular biochemical cascade that converts cAMP into adenosine. The functional relevance of this extracellular signalling system may involve a feedback modulation of cellular response initiated by several G protein-coupled receptor ligands, amplifying cAMP influence to a paracrine mode, through its metabolite, adenosine. PMID:18157164

  3. Binding of [3H]MSX-2 (3-(3-hydroxypropyl)-7-methyl-8-(m-methoxystyryl)-1-propargylxanthine) to rat striatal membranes--a new, selective antagonist radioligand for A(2A) adenosine receptors.

    Science.gov (United States)

    Müller, C E; Maurinsh, J; Sauer, R

    2000-01-01

    The present study describes the preparation and binding properties of a new, potent, and selective A(2A) adenosine receptor (AR) antagonist radioligand, [3H]3-(3-hydroxypropyl)-7-methyl-8-(m-methoxystyryl)-1-propargy lxanth ine ([3H]MSX-2). [3H]MSX-2 binding to rat striatal membranes was saturable and reversible. Saturation experiments showed that [3H]MSX-2 labeled a single class of binding sites with high affinity (K(d)=8.0 nM) and limited capacity (B(max)=1.16 fmol.mg(-1) of protein). The presence of 100 microM GTP, or 10 mM magnesium chloride, respectively, had no effect on [3H]MSX-2 binding. AR agonists competed with the binding of 1 nM [3H]MSX-2 with the following order of potency: 5'-N-ethylcarboxamidoadenosine (NECA)>2-[4-(carboxyethyl)phenylethylamino]-5'-N-ethylcarboxami doaden osine (CGS-21680)>2-chloroadenosine (2-CADO)>N(6)-cyclopentyladenosine (CPA). AR antagonists showed the following order of potency: 8-(m-bromostyryl)-3, 7-dimethyl-1-propargylxanthine (BS-DMPX)>1, 3-dipropyl-8-cyclopentylxanthine (DPCPX)>(R)-5, 6-dimethyl-7-(1-phenylethyl)-2-(4-pyridyl)-7H-pyrrolo[2, 3-d]pyrimidine-4-amine (SH-128)>3,7-dimethyl-1-propargylxanthine (DMPX)>caffeine. The K(i) values for antagonists were in accordance with data from binding studies with the agonist radioligand [3H]CGS21680, while agonist affinities were 3-7-fold lower. [3H]MSX-2 is a highly selective A(2A) AR antagonist radioligand exhibiting a selectivity of at least two orders of magnitude versus all other AR subtypes. The new radioligand shows high specific radioactivity (85 Ci/mmol, 3150 GBq/mmol) and acceptable nonspecific binding at rat striatal membranes of 20-30%, at 1 nM.

  4. Hepatic oxidative stress in ovariectomized transgenic mice expressing the hepatitis C virus polyprotein is augmented through suppression of adenosine monophosphate-activated protein kinase/proliferator-activated receptor gamma co-activator 1 alpha signaling.

    Science.gov (United States)

    Tomiyama, Yasuyuki; Nishina, Sohji; Hara, Yuichi; Kawase, Tomoya; Hino, Keisuke

    2014-10-01

    Oxidative stress plays an important role in hepatocarcinogenesis of hepatitis C virus (HCV)-related chronic liver diseases. Despite the evidence of an increased proportion of females among elderly patients with HCV-related hepatocellular carcinoma (HCC), it remains unknown whether HCV augments hepatic oxidative stress in postmenopausal women. The aim of this study was to determine whether oxidative stress was augmented in ovariectomized (OVX) transgenic mice expressing the HCV polyprotein and to investigate its underlying mechanisms. OVX and sham-operated female transgenic mice expressing the HCV polyprotein and non-transgenic littermates were assessed for the production of reactive oxygen species (ROS), expression of inflammatory cytokines and antioxidant potential in the liver. Compared with OVX non-transgenic mice, OVX transgenic mice showed marked hepatic steatosis and ROS production without increased induction of inflammatory cytokines, but there was no increase in ROS-detoxifying enzymes such as superoxide dismutase 2 and glutathione peroxidase 1. In accordance with these results, OVX transgenic mice showed less activation of peroxisome proliferator-activated receptor-γ co-activator-1α (PGC-1α), which is required for the induction of ROS-detoxifying enzymes, and no activation of adenosine monophosphate-activated protein kinase-α (AMPKα), which regulates the activity of PGC-1α. Our study demonstrated that hepatic oxidative stress was augmented in OVX transgenic mice expressing the HCV polyprotein by attenuation of antioxidant potential through inhibition of AMPK/PGC-1α signaling. These results may account in part for the mechanisms by which HCV-infected women are at high risk for HCC development when some period has passed after menopause. © 2013 The Japan Society of Hepatology.

  5. Presynaptic inhibition of GABAergic synaptic transmission by adenosine in mouse hypothalamic hypocretin neurons.

    Science.gov (United States)

    Xia, J X; Xiong, J X; Wang, H K; Duan, S M; Ye, J N; Hu, Z A

    2012-01-10

    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

  6. Ability of γδ T cells to modulate the Foxp3 T cell response is dependent on adenosine.

    Directory of Open Access Journals (Sweden)

    Dongchun Liang

    Full Text Available Whether γδ T cells inhibit or enhance the Foxp3 T cell response depends upon their activation status. The critical enhancing effector in the supernatant is adenosine. Activated γδ T cells express adenosine receptors at high levels, which enables them to deprive Foxp3+ T cells of adenosine, and to inhibit their expansion. Meanwhile, cell-free supernatants of γδ T cell cultures enhance Foxp3 T cell expansion. Thus, inhibition and enhancement by γδ T cells of Foxp3 T cell response are a reflection of the balance between adenosine production and absorption by γδ T cells. Non-activated γδ T cells produce adenosine but bind little, and thus enhance the Foxp3 T cell response. Activated γδ T cells express high density of adenosine receptors and have a greatly increased ability to bind adenosine. Extracellular adenosine metabolism and expression of adenosine receptor A2ARs by γδ T cells played a major role in the outcome of γδ and Foxp3 T cell interactions. A better understanding of the functional conversion of γδ T cells could lead to γδ T cell-targeted immunotherapies for related diseases.

  7. Extracellular adenosine controls NKT-cell-dependent hepatitis induction.

    Science.gov (United States)

    Subramanian, Meenakshi; Kini, Radhika; Madasu, Manasa; Ohta, Akiko; Nowak, Michael; Exley, Mark; Sitkovsky, Michail; Ohta, Akio

    2014-04-01

    Extracellular adenosine regulates inflammatory responses via the A2A adenosine receptor (A2AR). A2AR deficiency results in much exaggerated acute hepatitis, indicating nonredundancy of adenosine-A2AR pathway in inhibiting immune activation. To identify a critical target of immunoregulatory effect of extracellular adenosine, we focused on NKT cells, which play an indispensable role in hepatitis. An A2AR agonist abolished NKT-cell-dependent induction of acute hepatitis by concanavalin A (Con A) or α-galactosylceramide in mice, corresponding to downregulation of activation markers and cytokines in NKT cells and of NK-cell co-activation. These results show that A2AR signaling can downregulate NKT-cell activation and suppress NKT-cell-triggered inflammatory responses. Next, we hypothesized that NKT cells might be under physiological control of the adenosine-A2AR pathway. Indeed, both Con A and α-galactosylceramide induced more severe hepatitis in A2AR-deficient mice than in WT controls. Transfer of A2AR-deficient NKT cells into A2AR-expressing recipients resulted in exaggeration of Con A-induced liver damage, suggesting that NKT-cell activation is controlled by endogenous adenosine via A2AR, and this physiological regulatory mechanism of NKT cells is critical in the control of tissue-damaging inflammation. The current study suggests the possibility to manipulate NKT-cell activity in inflammatory disorders through intervention to the adenosine-A2AR pathway. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Selective attenuation of norepinephrine release and stress-induced heart rate increase by partial adenosine A1 agonism.

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    Lorenz Bott-Flügel

    Full Text Available The release of the neurotransmitter norepinephrine (NE is modulated by presynaptic adenosine receptors. In the present study we investigated the effect of a partial activation of this feedback mechanism. We hypothesized that partial agonism would have differential effects on NE release in isolated hearts as well as on heart rate in vivo depending on the genetic background and baseline sympathetic activity. In isolated perfused hearts of Wistar and Spontaneously Hypertensive Rats (SHR, NE release was induced by electrical stimulation under control conditions (S1, and with capadenoson 6 · 10(-8 M (30 µg/l, 6 · 10(-7 M (300 µg/l or 2-chloro-N(6-cyclopentyladenosine (CCPA 10(-6 M (S2. Under control conditions (S1, NE release was significantly higher in SHR hearts compared to Wistar (766+/-87 pmol/g vs. 173+/-18 pmol/g, p<0.01. Capadenoson led to a concentration-dependent decrease of the stimulation-induced NE release in SHR (S2/S1  =  0.90 ± 0.08 with capadenoson 6 · 10(-8 M, 0.54 ± 0.02 with 6 · 10(-7 M, but not in Wistar hearts (S2/S1  =  1.05 ± 0.12 with 6 · 10(-8 M, 1.03 ± 0.09 with 6 · 10(-7 M. CCPA reduced NE release to a similar degree in hearts from both strains. In vivo capadenoson did not alter resting heart rate in Wistar rats or SHR. Restraint stress induced a significantly greater increase of heart rate in SHR than in Wistar rats. Capadenoson blunted this stress-induced tachycardia by 45% in SHR, but not in Wistar rats. Using a [(35S]GTPγS assay we demonstrated that capadenoson is a partial agonist compared to the full agonist CCPA (74+/-2% A(1-receptor stimulation. These results suggest that partial adenosine A(1-agonism dampens stress-induced tachycardia selectively in rats susceptible to strong increases in sympathetic activity, most likely due to a presynaptic attenuation of NE release.

  9. Hydrogen sulfide inhibits A2A adenosine receptor agonist induced β-amyloid production in SH-SY5Y neuroblastoma cells via a cAMP dependent pathway.

    Directory of Open Access Journals (Sweden)

    Bhushan Vijay Nagpure

    Full Text Available Alzheimer's disease (AD is the leading cause of senile dementia in today's society. Its debilitating symptoms are manifested by disturbances in many important brain functions, which are influenced by adenosine. Hence, adenosinergic system is considered as a potential therapeutic target in AD treatment. In the present study, we found that sodium hydrosulfide (NaHS, an H2S donor, 100 µM attenuated HENECA (a selective A2A receptor agonist, 10-200 nM induced β-amyloid (1-42 (Aβ42 production in SH-SY5Y cells. NaHS also interfered with HENECA-stimulated production and post-translational modification of amyloid precursor protein (APP by inhibiting its maturation. Measurement of the C-terminal APP fragments generated from its enzymatic cleavage by β-site amyloid precursor protein cleaving enzyme 1 (BACE1 showed that NaHS did not have any significant effect on β-secretase activity. However, the direct measurements of HENECA-elevated γ-secretase activity and mRNA expressions of presenilins suggested that the suppression of Aβ42 production in NaHS pretreated cells was mediated by inhibiting γ-secretase. NaHS induced reductions were accompanied by similar decreases in intracellular cAMP levels and phosphorylation of cAMP responsive element binding protein (CREB. NaHS significantly reduced the elevated cAMP and Aβ42 production caused by forskolin (an adenylyl cyclase, AC agonist alone or forskolin in combination with IBMX (a phosphodiesterase inhibitor, but had no effect on those caused by IBMX alone. Moreover, pretreatment with NaHS significantly attenuated HENECA-elevated AC activity and mRNA expressions of various AC isoforms. These data suggest that NaHS may preferentially suppress AC activity when it was stimulated. In conclusion, H2S attenuated HENECA induced Aβ42 production in SH-SY5Y neuroblastoma cells through inhibiting γ-secretase via a cAMP dependent pathway.

  10. Pulsed electromagnetic fields increased the anti-inflammatory effect of A₂A and A₃ adenosine receptors in human T/C-28a2 chondrocytes and hFOB 1.19 osteoblasts.

    Directory of Open Access Journals (Sweden)

    Fabrizio Vincenzi

    Full Text Available Adenosine receptors (ARs have an important role in the regulation of inflammation and their activation is involved in the inhibition of pro-inflammatory cytokine release. The effects of pulsed electromagnetic fields (PEMFs on inflammation have been reported and we have demonstrated that PEMFs increased A2A and A3AR density and functionality in different cell lines. Chondrocytes and osteoblasts are two key cell types in the skeletal system that play important role in cartilage and bone metabolism representing an interesting target to study the effect of PEMFs. The primary aim of the present study was to evaluate if PEMF exposure potentiated the anti-inflammatory effect of A2A and/or A3ARs in T/C-28a2 chondrocytes and hFOB 1.19 osteoblasts. Immunofluorescence, mRNA analysis and saturation binding assays revealed that PEMF exposure up-regulated A2A and A3AR expression. A2A and A3ARs were able to modulate cAMP production and cell proliferation. The activation of A2A and A3ARs resulted in the decrease of some of the most relevant pro-inflammatory cytokine release such as interleukin (IL-6 and IL-8, following the treatment with IL-1β as an inflammatory stimuli. In human chondrocyte and osteoblast cell lines, the inhibitory effect of A2A and A3AR stimulation on the release of prostaglandin E2 (PGE2, an important lipid inflammatory mediator, was observed. In addition, in T/C-28a2 cells, the activation of A2A or A3ARs elicited an inhibition of vascular endothelial growth factor (VEGF secretion. In hFOB 1.19 osteoblasts, PEMF exposure determined an increase of osteoprotegerin (OPG production. The effect of the A2A or A3AR agonists in the examined cells was enhanced in the presence of PEMFs and completely blocked by using well-known selective antagonists. These results demonstrated that PEMF exposure significantly increase the anti-inflammatory effect of A2A or A3ARs suggesting their potential therapeutic use in the therapy of inflammatory bone and joint

  11. Dampened STING-Dependent Interferon Activation in Bats.

    Science.gov (United States)

    Xie, Jiazheng; Li, Yang; Shen, Xurui; Goh, Geraldine; Zhu, Yan; Cui, Jie; Wang, Lin-Fa; Shi, Zheng-Li; Zhou, Peng

    2018-03-14

    Compared with terrestrial mammals, bats have a longer lifespan and greater capacity to co-exist with a variety of viruses. In addition to cytosolic DNA generated by these viral infections, the metabolic demands of flight cause DNA damage and the release of self-DNA into the cytoplasm. However, whether bats have an altered DNA sensing/defense system to balance high cytosolic DNA levels remains an open question. We demonstrate that bats have a dampened interferon response due to the replacement of the highly conserved serine residue (S358) in STING, an essential adaptor protein in multiple DNA sensing pathways. Reversing this mutation by introducing S358 restored STING functionality, resulting in interferon activation and virus inhibition. Combined with previous reports on bat-specific changes of other DNA sensors such as TLR9, IFI16, and AIM2, our findings shed light on bat adaptation to flight, their long lifespan, and their unique capacity to serve as a virus reservoir. Copyright © 2018 Elsevier Inc. All rights reserved.

  12. Adenosine and ATP Receptors in the Brain

    Czech Academy of Sciences Publication Activity Database

    Burnstock, G.; Fredholm, B. B.; Verkhratsky, Alexei

    2011-01-01

    Roč. 11, č. 8 (2011), s. 973-1011 ISSN 1568-0266 R&D Projects: GA ČR GA309/08/1381; GA ČR GA305/08/1384 Institutional research plan: CEZ:AV0Z50390703 Keywords : Ischaemia * CNS * glia Subject RIV: FH - Neurology Impact factor: 4.174, year: 2011

  13. Inhibition of synaptically evoked cortical acetylcholine release by adenosine: an in vivo microdialysis study in the rat.

    Science.gov (United States)

    Materi, L M; Rasmusson, D D; Semba, K

    2000-01-01

    The release of cortical acetylcholine from the intracortical axonal terminals of cholinergic basal forebrain neurons is closely associated with electroencephalographic activity. One factor which may act to reduce cortical acetylcholine release and promote sleep is adenosine. Using in vivo microdialysis, we examined the effect of adenosine and selective adenosine receptor agonists and antagonists on cortical acetylcholine release evoked by electrical stimulation of the pedunculopontine tegmental nucleus in urethane anesthetized rats. All drugs were administered locally within the cortex by reverse dialysis. None of the drugs tested altered basal release of acetylcholine in the cortex. Adenosine significantly reduced evoked cortical acetylcholine efflux in a concentration-dependent manner. This was mimicked by the adenosine A(1) receptor selective agonist N(6)-cyclopentyladenosine and blocked by the selective A(1) receptor antagonist 8-cyclopentyl-1,3-dipropylxanthine (DPCPX). The A(2A) receptor agonist 2-[p-(2-carboxyethyl)-phenethylamino]-5'-N-ethylcarboxamidoadenosi ne hydrochloride (CGS 21680) did not alter evoked cortical acetylcholine release even in the presence of DPCPX. Administered alone, neither DPCPX nor the non-selective adenosine receptor antagonist caffeine affected evoked cortical acetylcholine efflux. Simultaneous delivery of the adenosine uptake inhibitors dipyridamole and S-(4-nitrobenzyl)-6-thioinosine significantly reduced evoked cortical acetylcholine release, and this effect was blocked by the simultaneous administration of caffeine. These data indicate that activation of the A(1) adenosine receptor inhibits acetylcholine release in the cortex in vivo while the A(2A) receptor does not influence acetylcholine efflux. Such inhibition of cortical acetylcholine release by adenosine may contribute to an increased propensity to sleep during prolonged wakefulness.

  14. Characteristics of high affinity and low affinity adenosine binding sites in human cerebral cortex

    International Nuclear Information System (INIS)

    John, D.; Fox, I.V.

    1986-01-01

    The binding characteristics of human brain cortical membrane fractions were evaluated to test the hypothesis that there are A 1 and A 2 adenosine binding sites. The ligands used were 2-chloro(8- 3 H) adenosine and N 6 -(adenine-2, 8- 3 H) cyclohexayladenosine. Binding of chloroadenosine to human brain cortical membranes was time dependent, reversible and concentration dependent. The kinetic constant determinations from binding studies of the adenosine receptor are presented. Utilizing tritium-cyclohexyladenosine as ligand the authors observed evidence for a high affinity binding site in human brain cortical membranes with a kd of 5 nM

  15. The Use of Adenosine Agonists to Treat Nerve Agent-Induced Seizure and Neuropathology

    Science.gov (United States)

    2016-09-01

    not be cited for purposes of advertisement . REPORT DOCUMENTATION PAGE Form Approved OMB No. 0704-0188 Public reporting burden for this...survivability. That was an important step to clinical relevancy as it was feared that ADO’s depression of cardiovascular output would exacerbate...kainate, adenosine and neuropeptide Y receptors. Neurochemical Research. 28: 1501-1515. 23. Bjorness, T. E. & R. W. Greene . 2009. Adenosine and sleep

  16. Epitope Dampening Monotypic Measles Virus Hemagglutinin Glycoprotein Results in Resistance to Cocktail of Monoclonal Antibodies

    Science.gov (United States)

    Lech, Patrycja J.; Tobin, Gregory J.; Bushnell, Ruth; Gutschenritter, Emily; Pham, Linh D.; Nace, Rebecca; Verhoeyen, Els; Cosset, François-Loïc; Muller, Claude P.; Russell, Stephen J.; Nara, Peter L.

    2013-01-01

    The measles virus (MV) is serologically monotypic. Life-long immunity is conferred by a single attack of measles or following vaccination with the MV vaccine. This is contrary to viruses such as influenza, which readily develop resistance to the immune system and recur. A better understanding of factors that restrain MV to one serotype may allow us to predict if MV will remain monotypic in the future and influence the design of novel MV vaccines and therapeutics. MV hemagglutinin (H) glycoprotein, binds to cellular receptors and subsequently triggers the fusion (F) glycoprotein to fuse the virus into the cell. H is also the major target for neutralizing antibodies. To explore if MV remains monotypic due to a lack of plasticity of the H glycoprotein, we used the technology of Immune Dampening to generate viruses with rationally designed N-linked glycosylation sites and mutations in different epitopes and screened for viruses that escaped monoclonal antibodies (mAbs). We then combined rationally designed mutations with naturally selected mutations to generate a virus resistant to a cocktail of neutralizing mAbs targeting four different epitopes simultaneously. Two epitopes were protected by engineered N-linked glycosylations and two epitopes acquired escape mutations via two consecutive rounds of artificial selection in the presence of mAbs. Three of these epitopes were targeted by mAbs known to interfere with receptor binding. Results demonstrate that, within the epitopes analyzed, H can tolerate mutations in different residues and additional N-linked glycosylations to escape mAbs. Understanding the degree of change that H can tolerate is important as we follow its evolution in a host whose immunity is vaccine induced by genotype A strains instead of multiple genetically distinct wild-type MVs. PMID:23300970

  17. Role of adenosine as adjunctive therapy in acute myocardial infarction.

    Science.gov (United States)

    Forman, Mervyn B; Stone, Gregg W; Jackson, Edwin K

    2006-01-01

    Although early reperfusion and maintained patency is the mainstay therapy for ST elevation myocardial infarction, experimental studies demonstrate that reperfusion per se induces deleterious effects on viable ischemic cells. Thus "myocardial reperfusion injury" may compromise the full potential of reperfusion therapy and may account for unfavorable outcomes in high-risk patients. Although the mechanisms of reperfusion injury are complex and multifactorial, neutrophil-mediated microvascular injury resulting in a progressive decrease in blood flow ("no-reflow" phenomenon) likely plays an important role. Adenosine is an endogenous nucleoside found in large quantities in myocardial and endothelial cells. It activates four well-characterized receptors producing various physiological effects that attenuate many of the proposed mechanisms of reperfusion injury. The cardio-protective effects of adenosine are supported by its role as a mediator of pre- and post-conditioning. In experimental models, administration of adenosine in the peri-reperfusion period results in a marked reduction in infarct size and improvement in ventricular function. The cardioprotective effects in the canine model have a narrow time window with the drug losing its effect following three hours of ischemia. Several small clinical studies have demonstrated that administration of adenosine with reperfusion therapy reduces infarct size and improves ventricular function. In the larger AMISTAD and AMISTAD II trials a 3-h infusion of adenosine as an adjunct to reperfusion resulted in a striking reduction in infarct size (55-65%). Post hoc analysis of AMISTAD II showed that this was associated with significantly improved early and late mortality in patients treated within 3.17 h of symptoms. An intravenous infusion of adenosine for 3 h should be considered as adjunctive therapy in high risk-patients undergoing reperfusion therapy.

  18. Adenosine derived from Staphylococcus aureus-engulfed macrophages functions as a potent stimulant for the induction of inflammatory cytokines in mast cells

    DEFF Research Database (Denmark)

    Ma, Ying Jie; Kim, Chan-Hee; Ryu, Kyoung-Hwa

    2011-01-01

    In this study, we attempted to isolate novel mast cell-stimulating molecules from Staphylococcus aureus. Water-soluble extract of S. aureus cell lysate strongly induced human interleukin- 8 in human mast cell line-1 and mouse interleukin-6 in mouse bone marrow-derived mast cells. The active...... adenosine receptor blocker, verified that purified adenosine can induce interleukin-8 production via adenosine receptors on mast cells. Moreover, adenosine was purified from S. aureusengulfed RAW264.7 cells, a murine macrophage cell line, used to induce phagocytosis of S. aureus. These results show a novel...

  19. The Role of Adenosine A2BR in Metastatic Melanoma

    Science.gov (United States)

    2017-07-01

    burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden to Department of Defense...would like to interrogate the role of adenosine receptor (A2BR) in regulating primary tumor growth and metastasis in experimental models of melanoma...The positive control was a triple negative breast cancer cell line, E0771. To interrogate the role of A2BR in aiding tumor metastasis, we used VeCad

  20. The pharmacological activation of adenosine A(1) and A(3) receptors does not modulate the long- or short-term repopulating ability of hematopoietic stem and multipotent progenitor cells in mice

    Czech Academy of Sciences Publication Activity Database

    Hofer, Michal; Pospíšil, Milan; Hoferová, Zuzana; Komůrková, Denisa; Páral, P.; Savvulidi, F.; Šefc, L.

    2013-01-01

    Roč. 9, č. 2 (2013), s. 207-214 ISSN 1573-9538 R&D Projects: GA ČR(CZ) GA305/08/0158; GA ČR(CZ) GAP303/11/0128; GA MO(CZ) OVBIOFYZ20101 Grant - others:GA MŠk(CZ) LC06044 Institutional support: RVO:68081707 Keywords : ELEVATING EXTRACELLULAR ADENOSINE * COLONY-STIMULATING FACTOR * BONE -MARROW Subject RIV: BO - Biophysics Impact factor: 3.510, year: 2013

  1. Oral tremor induced by the muscarinic agonist pilocarpine is suppressed by the adenosine A2A antagonists MSX-3 and SCH58261, but not the adenosine A1 antagonist DPCPX.

    Science.gov (United States)

    Collins, Lyndsey E; Galtieri, Daniel J; Brennum, Lise T; Sager, Thomas N; Hockemeyer, Jörg; Müller, Christa E; Hinman, James R; Chrobak, James J; Salamone, John D

    2010-02-01

    Tremulous jaw movements in rats, which can be induced by dopamine (DA) antagonists, DA depletion, and cholinomimetics, have served as a useful model for studies of tremor. Although adenosine A(2A) antagonists can reduce the tremulous jaw movements induced by DA antagonists and DA depletion, there are conflicting reports about the interaction between adenosine antagonists and cholinomimetic drugs. The present studies investigated the ability of adenosine antagonists to reverse the tremorogenic effect of the muscarinic agonist pilocarpine. While the adenosine A(2A) antagonist MSX-3 was incapable of reversing the tremulous jaw movements induced by the 4.0mg/kg dose of pilocarpine, both MSX-3 and the adenosine A(2A) antagonist SCH58261 reversed the tremulous jaw movements elicited by 0.5mg/kg pilocarpine. Systemic administration of the adenosine A(1) antagonist DPCPX failed to reverse the tremulous jaw movements induced by either an acute 0.5mg/kg dose of the cholinomimetic pilocarpine or the DA D2 antagonist pimozide, indicating that the tremorolytic effects of adenosine antagonists may be receptor subtype specific. Behaviorally active doses of MSX-3 and SCH 58261 showed substantial in vivo occupancy of A(2A) receptors, but DPCPX did not. The results of these studies support the use of adenosine A(2A) antagonists for the treatment of tremor. Copyright 2009 Elsevier Inc. All rights reserved.

  2. The effect of nucleotides and adenosine on stimulus-evoked glutamate release from rat brain cortical slices.

    Science.gov (United States)

    Bennett, G C; Boarder, M R

    2000-10-01

    Evidence has previously been presented that P1 receptors for adenosine, and P2 receptors for nucleotides such as ATP, regulate stimulus-evoked release of biogenic amines from nerve terminals in the brain. Here we investigated whether adenosine and nucleotides exert presynaptic control over depolarisation-elicited glutamate release. Slices of rat brain cortex were perfused and stimulated with pulses of 46 mM K(+) in the presence of the glutamate uptake inhibitor L-trans-pyrrolidine-2,4-dicarboxylic acid (0.2 mM). High K(+) substantially increased efflux of glutamate from the slices. Basal glutamate release was unchanged by the presence of nucleotides or adenosine at concentrations of 300 microM. Adenosine, ATP, ADP and adenosine 5'-O-(3-thiotriphoshate) at 300 microM attenuated depolarisation-evoked release of glutamate. However UTP, 2-methylthio ATP, 2-methylthio ADP, and alpha,beta-methylene ATP at 300 microM had no effect on stimulated glutamate efflux. Adenosine deaminase blocked the effect of adenosine, but left the response to ATP unchanged. The A(1) antagonist 8-cyclopentyl-1, 3-dipropylxanthine antagonised the inhibitory effect of both adenosine and ATP. Cibacron blue 3GA inhibited stimulus-evoked glutamate release when applied alone. When cibacron blue 3GA was present with ATP, stimulus-evoked glutamate release was almost eliminated. However, this P2 antagonist had no effect on the inhibition by adenosine. These results show that the release of glutamate from depolarised nerve terminals of the rat cerebral cortex is inhibited by adenosine and ATP. ATP appears to act directly and not through conversion to adenosine.

  3. Role of adenosine signalling and metabolism in β-cell regeneration

    Energy Technology Data Exchange (ETDEWEB)

    Andersson, Olov, E-mail: olov.andersson@ki.se

    2014-02-01

    Glucose homeostasis, which is controlled by the endocrine cells of the pancreas, is disrupted in both type I and type II diabetes. Deficiency in the number of insulin-producing β cells – a primary cause of type I diabetes and a secondary contributor of type II diabetes – leads to hyperglycemia and hence an increase in the need for insulin. Although diabetes can be controlled with insulin injections, a curative approach is needed. A potential approach to curing diabetes involves regenerating the β-cell mass, e.g. by increasing β-cell proliferation, survival, neogenesis or transdifferentiation. The nucleoside adenosine and its cognate nucleotide ATP have long been known to affect insulin secretion, but have more recently been shown to increase β-cell proliferation during homeostatic control and regeneration of the β-cell mass. Adenosine is also known to have anti-inflammatory properties, and agonism of adenosine receptors can promote the survival of β-cells in an inflammatory microenvironment. In this review, both intracellular and extracellular mechanisms of adenosine and ATP are discussed in terms of their established and putative effects on β-cell regeneration. - Highlights: • A potential way to cure diabetes is to regenerate the β-cell mass by promoting cell survival, proliferation or neogenesis. • Adenosine may promote β-cell regeneration through several cellular mechanisms. • Adenosine and its cognate nucleotide ATP can each promote β-cell proliferation. • Do adenosine and ATP interact in promoting β-cell proliferation?.

  4. Role of adenosine signalling and metabolism in β-cell regeneration

    International Nuclear Information System (INIS)

    Andersson, Olov

    2014-01-01

    Glucose homeostasis, which is controlled by the endocrine cells of the pancreas, is disrupted in both type I and type II diabetes. Deficiency in the number of insulin-producing β cells – a primary cause of type I diabetes and a secondary contributor of type II diabetes – leads to hyperglycemia and hence an increase in the need for insulin. Although diabetes can be controlled with insulin injections, a curative approach is needed. A potential approach to curing diabetes involves regenerating the β-cell mass, e.g. by increasing β-cell proliferation, survival, neogenesis or transdifferentiation. The nucleoside adenosine and its cognate nucleotide ATP have long been known to affect insulin secretion, but have more recently been shown to increase β-cell proliferation during homeostatic control and regeneration of the β-cell mass. Adenosine is also known to have anti-inflammatory properties, and agonism of adenosine receptors can promote the survival of β-cells in an inflammatory microenvironment. In this review, both intracellular and extracellular mechanisms of adenosine and ATP are discussed in terms of their established and putative effects on β-cell regeneration. - Highlights: • A potential way to cure diabetes is to regenerate the β-cell mass by promoting cell survival, proliferation or neogenesis. • Adenosine may promote β-cell regeneration through several cellular mechanisms. • Adenosine and its cognate nucleotide ATP can each promote β-cell proliferation. • Do adenosine and ATP interact in promoting β-cell proliferation?

  5. Ecto-ATPase inhibition: ATP and adenosine release under physiological and ischemic in vivo conditions in the rat striatum.

    Science.gov (United States)

    Melani, Alessia; Corti, Francesca; Stephan, Holger; Müller, Christa E; Donati, Chiara; Bruni, Paola; Vannucchi, Maria Giuliana; Pedata, Felicita

    2012-01-01

    In the central nervous system (CNS) ATP and adenosine act as transmitters and neuromodulators on their own receptors but it is still unknown which part of extracellular adenosine derives per se from cells and which part is formed from the hydrolysis of released ATP. In this study extracellular concentrations of adenosine and ATP from the rat striatum were estimated by the microdialysis technique under in vivo physiological conditions and after focal ischemia induced by medial cerebral artery occlusion. Under physiological conditions, adenosine and ATP concentrations were in the range of 130 nmol/L and 40 nmol/L, respectively. In the presence of the novel ecto-ATPase inhibitor, PV4 (100 nmol/L), the extracellular concentration of ATP increased 12-fold to ~360 nmol/L but the adenosine concentration was not altered. This demonstrates that, under physiological conditions, adenosine is not a product of extracellular ATP. In the first 4h after ischemia, adenosine increased to ~690 nmol/L and ATP to ~50 nmol/L. In the presence of PV4 the extracellular concentration of ATP was in the range of 450 nmol/L and a significant decrease in extracellular adenosine (to ~270 nmol/L) was measured. The contribution of extracellular ATP to extracellular adenosine was maximal in the first 20 min after ischemia onset. Furthermore we demonstrated, by immunoelectron microscopy, the presence of the concentrative nucleoside transporter CNT2 on plasma and vesicle membranes isolated from the rat striatum. These results are in favor that adenosine is transported in vesicles and is released in an excitation-secretion manner under in vivo physiological conditions. Early after ischemia, extracellular ATP is hydrolyzed by ecto-nucleotidases which significantly contribute to the increase in extracellular adenosine. To establish the contribution of extracellular ATP to adenosine might constitute the basis for devising a correct putative purinergic strategy aimed at protection from ischemic damage

  6. Sleep-wake sensitive mechanisms of adenosine release in the basal forebrain of rodents: an in vitro study.

    Directory of Open Access Journals (Sweden)

    Robert Edward Sims

    Full Text Available Adenosine acting in the basal forebrain is a key mediator of sleep homeostasis. Extracellular adenosine concentrations increase during wakefulness, especially during prolonged wakefulness and lead to increased sleep pressure and subsequent rebound sleep. The release of endogenous adenosine during the sleep-wake cycle has mainly been studied in vivo with microdialysis techniques. The biochemical changes that accompany sleep-wake status may be preserved in vitro. We have therefore used adenosine-sensitive biosensors in slices of the basal forebrain (BFB to study both depolarization-evoked adenosine release and the steady state adenosine tone in rats, mice and hamsters. Adenosine release was evoked by high K(+, AMPA, NMDA and mGlu receptor agonists, but not by other transmitters associated with wakefulness such as orexin, histamine or neurotensin. Evoked and basal adenosine release in the BFB in vitro exhibited three key features: the magnitude of each varied systematically with the diurnal time at which the animal was sacrificed; sleep deprivation prior to sacrifice greatly increased both evoked adenosine release and the basal tone; and the enhancement of evoked adenosine release and basal tone resulting from sleep deprivation was reversed by the inducible nitric oxide synthase (iNOS inhibitor, 1400 W. These data indicate that characteristics of adenosine release recorded in the BFB in vitro reflect those that have been linked in vivo to the homeostatic control of sleep. Our results provide methodologically independent support for a key role for induction of iNOS as a trigger for enhanced adenosine release following sleep deprivation and suggest that this induction may constitute a biochemical memory of this state.

  7. Suppression of adenosine-activated chloride transport by ethanol in airway epithelia.

    Directory of Open Access Journals (Sweden)

    Sammeta V Raju

    Full Text Available Alcohol abuse is associated with increased lung infections. Molecular understanding of the underlying mechanisms is not complete. Airway epithelial ion transport regulates the homeostasis of airway surface liquid, essential for airway mucosal immunity and lung host defense. Here, air-liquid interface cultures of Calu-3 epithelial cells were basolaterally exposed to physiologically relevant concentrations of ethanol (0, 25, 50 and 100 mM for 24 hours and adenosine-stimulated ion transport was measured by Ussing chamber. The ethanol exposure reduced the epithelial short-circuit currents (I(SC in a dose-dependent manner. The ion currents activated by adenosine were chloride conductance mediated by cystic fibrosis transmembrane conductance regulator (CFTR, a cAMP-activated chloride channel. Alloxazine, a specific inhibitor for A(2B adenosine receptor (A(2BAR, largely abolished the adenosine-stimulated chloride transport, suggesting that A(2BAR is a major receptor responsible for regulating the chloride transport of the cells. Ethanol significantly reduced intracellular cAMP production upon adenosine stimulation. Moreover, ethanol-suppression of the chloride secretion was able to be restored by cAMP analogs or by inhibitors to block cAMP degradation. These results imply that ethanol exposure dysregulates CFTR-mediated chloride transport in airways by suppression of adenosine-A(2BAR-cAMP signaling pathway, which might contribute to alcohol-associated lung infections.

  8. Moonlighting adenosine deaminase: a target protein for drug development.

    Science.gov (United States)

    Cortés, Antoni; Gracia, Eduard; Moreno, Estefania; Mallol, Josefa; Lluís, Carme; Canela, Enric I; Casadó, Vicent

    2015-01-01

    Interest in adenosine deaminase (ADA) in the context of medicine has mainly focused on its enzymatic activity. This is justified by the importance of the reaction catalyzed by ADA not only for the intracellular purine metabolism, but also for the extracellular purine metabolism as well, because of its capacity as a regulator of the concentration of extracellular adenosine that is able to activate adenosine receptors (ARs). In recent years, other important roles have been described for ADA. One of these, with special relevance in immunology, is the capacity of ADA to act as a costimulator, promoting T-cell proliferation and differentiation mainly by interacting with the differentiation cluster CD26. Another role is the ability of ADA to act as an allosteric modulator of ARs. These receptors have very general physiological implications, particularly in the neurological system where they play an important role. Thus, ADA, being a single chain protein, performs more than one function, consistent with the definition of a moonlighting protein. Although ADA has never been associated with moonlighting proteins, here we consider ADA as an example of this family of multifunctional proteins. In this review, we discuss the different roles of ADA and their pathological implications. We propose a mechanism by which some of their moonlighting functions can be coordinated. We also suggest that drugs modulating ADA properties may act as modulators of the moonlighting functions of ADA, giving them additional potential medical interest. © 2014 Wiley Periodicals, Inc.

  9. Control model for dampening hand vibrations using information of internal and external coordinates.

    Directory of Open Access Journals (Sweden)

    Shunta Togo

    Full Text Available In the present study, we investigate a control mechanism that dampens hand vibrations. Here, we propose a control method with two components to suppress hand vibrations. The first is a passive suppression method that lowers the joint stiffness to passively dampen the hand vibrations. The second is an active suppression method that adjusts an equilibrium point based on skyhook control to actively dampen the hand vibrations. In a simulation experiment, we applied these two methods to dampen hand vibrations during the shoulder's horizontal oscillation. We also conducted a measurement experiment wherein a subject's shoulder was sinusoidally oscillated by a platform that generated horizontal oscillations. The results of the measurement experiments showed that the jerk of each part of the arm in a task using a cup filled with water was smaller than the shoulder jerk and that in a task with a cup filled with stones was larger than the shoulder jerk. Moreover, the amplitude of the hand trajectory in both horizontal and vertical directions was smaller in a task using a cup filled with water than in a task using a cup filled with stones. The results of the measurement experiments were accurately reproduced by the active suppression method based on skyhook control. These results suggest that humans dampen hand vibrations by controlling the equilibrium point through the information of the external workspace and the internal body state rather than by lowering joint stiffness only by using internal information.

  10. Extracellular adenosine-induced Rac1 activation in pulmonary endothelium: Molecular mechanisms and barrier-protective role.

    Science.gov (United States)

    Kovacs-Kasa, Anita; Kim, Kyung Mi; Cherian-Shaw, Mary; Black, Stephen M; Fulton, David J; Verin, Alexander D

    2018-08-01

    We have previously shown that Gs-coupled adenosine receptors (A2a) are primarily involved in adenosine-induced human pulmonary artery endothelial cell (HPAEC) barrier enhancement. However, the downstream events that mediate the strengthening of the endothelial cell (EC) barrier via adenosine signaling are largely unknown. In the current study, we tested the overall hypothesis that adenosine-induced Rac1 activation and EC barrier enhancement is mediated by Gs-dependent stimulation of cAMP-dependent Epac1-mediated signaling cascades. Adenoviral transduction of HPAEC with constitutively-active (C/A) Rac1 (V12Rac1) significantly increases transendothelial electrical resistance (TER) reflecting an enhancement of the EC barrier. Conversely, expression of an inactive Rac1 mutant (N17Rac1) decreases TER reflecting a compromised EC barrier. The adenosine-induced increase in TER was accompanied by activation of Rac1, decrease in contractility (MLC dephosphorylation), but not Rho inhibition. Conversely, inhibition of Rac1 activity attenuates adenosine-induced increase in TER. We next examined the role of cAMP-activated Epac1 and its putative downstream targets Rac1, Vav2, Rap1, and Tiam1. Depletion of Epac1 attenuated the adenosine-induced Rac1 activation and the increase in TER. Furthermore, silencing of Rac1 specific guanine nucleotide exchange factors (GEFs), Vav2 and Rap1a expression significantly attenuated adenosine-induced increases in TER and activation of Rac1. Depletion of Rap1b only modestly impacted adenosine-induced increases in TER and Tiam1 depletion had no effect on adenosine-induced Rac1 activation and TER. Together these data strongly suggest that Rac1 activity is required for adenosine-induced EC barrier enhancement and that the activation of Rac1 and ability to strengthen the EC barrier depends, at least in part, on cAMP-dependent Epac1/Vav2/Rap1-mediated signaling. © 2017 Wiley Periodicals, Inc.

  11. Adenosine as a signaling molecule in the retina: biochemical and developmental aspects

    Directory of Open Access Journals (Sweden)

    ROBERTO PAES-DE-CARVALHO

    2002-09-01

    Full Text Available The nucleoside adenosine plays an important role as a neurotransmitter or neuromodulator in the central nervous system, including the retina. In the present paper we review compelling evidence showing that adenosine is a signaling molecule in the developing retina. In the chick retina, adenosine transporters are present since early stages of development before the appearance of adenosine A1 receptors modulating dopamine-dependent adenylate cyclase activity or A2 receptors that directly activate the enzyme. Experiments using retinal cell cultures revealed that adenosine is taken up by specific cell populations that when stimulated by depolarization or neurotransmitters such as dopamine or glutamate, release the nucleoside through calcium-dependent transporter-mediated mechanisms. The presence of adenosine in the extracellular medium and the long-term activation of adenosine receptors is able to regulate the survival of retinal neurons and blocks glutamate excitoxicity. Thus, adenosine besides working as a neurotransmitter or neuromodulator in the mature retina, is considered as an important signaling molecule during retinal development having important functions such as regulation of neuronal survival and differentiation.O nucleosídeo adenosina apresenta um importante papel como neurotransmissor ou neuromodulador no sistema nervoso central, inclusive na retina. Neste artigo apresentamos uma revisão das evidências que mostram que a adenosina é uma molécula sinalizadora na retina em desenvolvimento. Na retina de pinto, transportadores de adenosina estão presentes desde estágios precoces do desenvolvimento, antes do aparecimento dos receptores A1 que modulam a atividade adenilato ciclase dependente de dopamina ou dos receptores A2 que ativam diretamente a enzima. Experimentos usando culturas de células de retina revelaram que a adenosina é captada por populações celulares específicas que, quando estimuladas por despolarização ou por

  12. Ethanol-induced increase in portal blood glow: Role of adenosine

    International Nuclear Information System (INIS)

    Orrego, H.; Carmichael, F.J.; Saldivia, V.; Giles, H.G.; Sandrin, S.; Israel, Y.

    1988-01-01

    The mechanism by which ethanol induces an increase in portal vein blood flow was studied in rats using radiolabeled microspheres. Ethanol by gavage resulted in an increase of 50-70% in portal vein blood flow. The ethanol-induced increase in portal blood flow was suppressed by the adenosine receptor blocker 8-phenyltheophylline. By itself, 8-phenyltheophylline was without effect on cardiac output or portal blood flow. Adenosine infusion resulted in a dose-dependent increase in portal blood flow. This adenosine-induced increase in portal blood flow was inhibited by 8-phenyltheophylline in a dose-dependent manner. Both alcohol and adenosine significantly reduced preportal vascular resistance by 40% and 60%, respectively. These effects were fully suppressed by 8-phenyltheophylline. It is concluded that adenosine is a likely candidate to mediate the ethanol-induced increase in portal vein blood flow. It is suggested that an increase in circulating acetate and liver hypoxia may mediate the effects of alcohol by increasing tissue and interstitial adenosine levels

  13. Adenosine signaling promotes regeneration of pancreatic β-cells in vivo

    Science.gov (United States)

    Andersson, Olov; Adams, Bruce A.; Yoo, Daniel; Ellis, Gregory C.; Gut, Philipp; Anderson, Ryan M.; German, Michael S.; Stainier, Didier Y. R.

    2012-01-01

    Diabetes can be controlled with insulin injections, but a curative approach that restores the number of insulin-producing β-cells is still needed. Using a zebrafish model of diabetes, we screened ~7000 small molecules to identify enhancers of β-cell regeneration. The compounds we identified converge on the adenosine signaling pathway and include exogenous agonists and compounds that inhibit degradation of endogenously produced adenosine. The most potent enhancer of β-cell regeneration was the adenosine agonist 5′-N-Ethylcarboxamidoadenosine (NECA), which acting through the adenosine receptor A2aa increased β-cell proliferation and accelerated restoration of normoglycemia in zebrafish. Despite markedly stimulating β-cell proliferation during regeneration, NECA had only a modest effect during development. The proliferative and glucose-lowering effect of NECA was confirmed in diabetic mice, suggesting an evolutionarily conserved role for adenosine in β-cell regeneration. With this whole-organism screen, we identified components of the adenosine pathway that could be therapeutically targeted for the treatment of diabetes. PMID:22608007

  14. Dampening Effects Of Food Importation On Climate Change-Induced Conflict In Africa

    Science.gov (United States)

    2017-12-01

    The validity of those claims, however, remains in question.47 Abundance theory, on the other hand, relies on a similar cost - benefit calculation but...FDRs). These resource fluctuations have the potential to reach levels extreme enough, as indicated in Table 9 results, to alter the cost - benefit ...NAVAL POSTGRADUATE SCHOOL MONTEREY, CALIFORNIA THESIS Approved for public release. Distribution is unlimited. DAMPENING EFFECTS

  15. Ebi3 Prevents Trypanosoma cruzi-Induced Myocarditis by Dampening IFN-γ-Driven Inflammation

    Directory of Open Access Journals (Sweden)

    Tiago Silva Medina

    2017-09-01

    Full Text Available The identification of anti-inflammatory mediators can reveal important targetable molecules capable of counterbalancing Trypanosoma cruzi-induced myocarditis. Composed of Ebi3 and IL-27p28 subunits, IL-27 is produced by myeloid cells and is able to suppress inflammation by inducing IL-10-producing Tr1 cells, thus emerging as a potential candidate to ameliorate cardiac inflammation induced by T. cruzi. Although IL-27 has been extensively characterized as a suppressive cytokine that prevents liver immunopathogenesis after T. cruzi infection, the mechanisms underlying its effects on T. cruzi-induced myocarditis remain largely unknown. Here, wild-type (WT and Ebi3-deficient animals were intraperitoneally infected with trypomastigotes of T. cruzi Y strain and used to evaluate the potential anti-inflammatory properties of Ebi3 during T. cruzi infection. The survival rates of mice were daily recorded, the frequency of inflammatory cells was analyzed by flow cytometry and inflammatory mediators were measured by ELISA, real-time PCR and PCR array. We reported that T. cruzi-induced myocarditis was prevented by Ebi3. Stressors mainly recognized by TLR2 and TLR4 receptors on myeloid cells were essential to trigger IL-27p28 production. In addition, Ebi3 regulated IFN-γ-mediated myocarditis by promoting an anti-inflammatory environment through IL-10, which was most likely produced by Tr1 cells rather than classical regulatory T cells (Tregs, in the heart tissue of T. cruzi-infected animals. Furthermore, in vivo IFN-γ blockade ameliorated the host survival without compromising the parasite control in the bloodstream. In humans, IL-27p28 was correlated with cardiac protection during Chagas disease. Patients with mild clinical forms of the disease produced high levels of IL-27p28, whereas lower levels were found in those with severe forms. In addition, polymorphic sites at Ebi3 gene were associated with severe cardiomyopathy in patients with Chagas disease

  16. Ebi3 Prevents Trypanosoma cruzi-Induced Myocarditis by Dampening IFN-γ-Driven Inflammation

    Science.gov (United States)

    Medina, Tiago Silva; Oliveira, Gabriela Gonçalves; Silva, Maria Cláudia; David, Bruna Araújo; Silva, Grace Kelly; Fonseca, Denise Morais; Sesti-Costa, Renata; Frade, Amanda Farage; Baron, Monique Andrade; Ianni, Barbara; Pereira, Alexandre Costa; Chevillard, Christophe; Cunha-Neto, Edécio; Marin-Neto, José Antonio; Silva, João Santana

    2017-01-01

    The identification of anti-inflammatory mediators can reveal important targetable molecules capable of counterbalancing Trypanosoma cruzi-induced myocarditis. Composed of Ebi3 and IL-27p28 subunits, IL-27 is produced by myeloid cells and is able to suppress inflammation by inducing IL-10-producing Tr1 cells, thus emerging as a potential candidate to ameliorate cardiac inflammation induced by T. cruzi. Although IL-27 has been extensively characterized as a suppressive cytokine that prevents liver immunopathogenesis after T. cruzi infection, the mechanisms underlying its effects on T. cruzi-induced myocarditis remain largely unknown. Here, wild-type (WT) and Ebi3-deficient animals were intraperitoneally infected with trypomastigotes of T. cruzi Y strain and used to evaluate the potential anti-inflammatory properties of Ebi3 during T. cruzi infection. The survival rates of mice were daily recorded, the frequency of inflammatory cells was analyzed by flow cytometry and inflammatory mediators were measured by ELISA, real-time PCR and PCR array. We reported that T. cruzi-induced myocarditis was prevented by Ebi3. Stressors mainly recognized by TLR2 and TLR4 receptors on myeloid cells were essential to trigger IL-27p28 production. In addition, Ebi3 regulated IFN-γ-mediated myocarditis by promoting an anti-inflammatory environment through IL-10, which was most likely produced by Tr1 cells rather than classical regulatory T cells (Tregs), in the heart tissue of T. cruzi-infected animals. Furthermore, in vivo IFN-γ blockade ameliorated the host survival without compromising the parasite control in the bloodstream. In humans, IL-27p28 was correlated with cardiac protection during Chagas disease. Patients with mild clinical forms of the disease produced high levels of IL-27p28, whereas lower levels were found in those with severe forms. In addition, polymorphic sites at Ebi3 gene were associated with severe cardiomyopathy in patients with Chagas disease. Collectively, we

  17. Adenosine: an activity-dependent axonal signal regulating MAP kinase and proliferation in developing Schwann cells

    OpenAIRE

    Stevens, Beth; Ishibashi, Tomoko; Chen, Jiang-Fan; Fields, R. Douglas

    2004-01-01

    Nonsynaptic release of ATP from electrically stimulated dorsal root gangion (DRG) axons inhibits Schwann cell (SC) proliferation and arrests SC development at the premyelinating stage, but the specific types of purinergic receptor(s) and intracellular signaling pathways involved in this form of neuron–glia communication are not known. Recent research shows that adenosine is a neuron–glial transmitter between axons and myelinating glia of the CNS. The present study investigates the possibility...

  18. A comparison of N-methyl-D-aspartate-evoked release of adenosine and [3H]norepinephrine from rat cortical slices

    International Nuclear Information System (INIS)

    Hoehn, K.; Craig, C.G.; White, T.D.

    1990-01-01

    Tetrodotoxin reduced N-methyl-D-aspartate (NMDA)-evoked release of adenosine by 35% but virtually abolished [3H]norepinephrine release. Although [3H]norepinephrine release from rat cortical slices evoked by 500 microM NMDA was abolished by 1.2 mM Mg++, which produces a voltage-sensitive, uncompetitive block of NMDA-channels, adenosine release was increased in the presence of Mg++. Partial depolarization with 12 mM K+ relieved the Mg++ block of 500 microM NMDA-evoked [3H]norepinephrine release but did not affect adenosine release, indicating that a Mg++ requirement for the adenosine release process per se cannot account for this discrepancy. NMDA was 33 times more potent in releasing adenosine than [3H]norepinephrine. At submaximal concentrations of NMDA (10 and 20 microM), adenosine release was augmented in Mg+(+)-free medium. Although a high concentration of the uncompetitive NMDA antagonist MK-801 [(+)-5-methyl-10,11,dihydro-5H-dibenzo[a,d]cyclohepten-5-10-imine maleate] (3 microM) blocked NMDA-evoked release of [3H]norepinephrine and adenosine, a lower concentration (300 nM) decreased NMDA-evoked [3H]norepinephrine release by 66% without affecting adenosine release. These findings suggest that maximal adenosine release occurs when relatively few NMDA receptors are activated, raising the possibility that spare receptors exist for NMDA-evoked adenosine release. Rather than acting as a protectant against excessive NMDA excitation, released adenosine might provide an inhibitory threshold which must be overcome for NMDA-mediated neurotransmission to proceed

  19. Dampened neural activity and abolition of epileptic-like activity in cortical slices by active ingredients of spices

    Science.gov (United States)

    Pezzoli, Maurizio; Elhamdani, Abdeladim; Camacho, Susana; Meystre, Julie; González, Stephanie Michlig; le Coutre, Johannes; Markram, Henry

    2014-01-01

    Active ingredients of spices (AIS) modulate neural response in the peripheral nervous system, mainly through interaction with TRP channel/receptors. The present study explores how different AIS modulate neural response in layer 5 pyramidal neurons of S1 neocortex. The AIS tested are agonists of TRPV1/3, TRPM8 or TRPA1. Our results demonstrate that capsaicin, eugenol, menthol, icilin and cinnamaldehyde, but not AITC dampen the generation of APs in a voltage- and time-dependent manner. This effect was further tested for the TRPM8 ligands in the presence of a TRPM8 blocker (BCTC) and on TRPM8 KO mice. The observable effect was still present. Finally, the influence of the selected AIS was tested on in vitro gabazine-induced seizures. Results coincide with the above observations: except for cinnamaldehyde, the same AIS were able to reduce the number, duration of the AP bursts and increase the concentration of gabazine needed to elicit them. In conclusion, our data suggests that some of these AIS can modulate glutamatergic neurons in the brain through a TRP-independent pathway, regardless of whether the neurons are stimulated intracellularly or by hyperactive microcircuitry. PMID:25359561

  20. Targeting Adenosine Signaling in Parkinson's Disease: From Pharmacological to Non-pharmacological Approaches

    Directory of Open Access Journals (Sweden)

    Luiza R. Nazario

    2017-11-01

    Full Text Available Parkinson's disease (PD is one of the most prevalent neurodegenerative disease displaying negative impacts on both the health and social ability of patients and considerable economical costs. The classical anti-parkinsonian drugs based in dopaminergic replacement are the standard treatment, but several motor side effects emerge during long-term use. This mini-review presents the rationale to several efforts from pre-clinical and clinical studies using adenosine receptor antagonists as a non-dopaminergic therapy. As several studies have indicated that the monotherapy with adenosine receptor antagonists reaches limited efficacy, the usage as a co-adjuvant appeared to be a promising strategy. The formulation of multi-targeted drugs, using adenosine receptor antagonists and other neurotransmitter systems than the dopaminergic one as targets, have been receiving attention since Parkinson's disease presents a complex biological impact. While pharmacological approaches to cure or ameliorate the conditions of PD are the leading strategy in this area, emerging positive aspects have arisen from non-pharmacological approaches and adenosine function inhibition appears to improve both strategies.

  1. Transgenic overexpression of adenosine kinase in brain leads to multiple learning impairments and altered sensitivity to psychomimetic drugs.

    Science.gov (United States)

    Yee, Benjamin K; Singer, Philipp; Chen, Jiang-Fan; Feldon, Joram; Boison, Detlev

    2007-12-01

    The neuromodulator adenosine fulfills a unique role in the brain affecting glutamatergic neurotransmission and dopaminergic signaling via activation of adenosine A1 and A2A receptors, respectively. The adenosine system is thus ideally positioned to integrate glutamatergic and dopaminergic neurotransmission, which in turn could affect behavior and cognition. In the adult brain, adenosine levels are largely regulated by its key metabolic enzyme adenosine kinase (ADK), which may assume the role of an 'upstream regulator' of these two neurotransmitter pathways. To test this hypothesis, transgenic mice with an overexpression of ADK in brain (Adk-tg), and therefore reduced brain adenosine levels, were evaluated in a panel of behavioral and psychopharmacological assays to assess possible glutamatergic and dopaminergic dysfunction. In comparison to non-transgenic control mice, Adk-tg mice are characterized by severe learning deficits in the Morris water maze task and in Pavlovian conditioning. The Adk-tg mice also exhibited reduced locomotor reaction to systemic amphetamine, whereas their reaction to the non-competitive N-methyl-d-aspartate receptor antagonist MK-801 was enhanced. Our results confirmed that ADK overexpression could lead to functional concomitant alterations in dopaminergic and glutamatergic functions, which is in keeping with the hypothesized role of ADK in the balance and integration between glutamatergic and dopaminergic neurotransmission. The present findings are of relevance to current pathophysiological hypotheses of schizophrenia and its pharmacotherapy.

  2. Acute stress increases depolarization-evoked glutamate release in the rat prefrontal/frontal cortex: the dampening action of antidepressants.

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    Laura Musazzi

    2010-01-01

    Full Text Available Behavioral stress is recognized as a main risk factor for neuropsychiatric diseases. Converging evidence suggested that acute stress is associated with increase of excitatory transmission in certain forebrain areas. Aim of this work was to investigate the mechanism whereby acute stress increases glutamate release, and if therapeutic drugs prevent the effect of stress on glutamate release.Rats were chronically treated with vehicle or drugs employed for therapy of mood/anxiety disorders (fluoxetine, desipramine, venlafaxine, agomelatine and then subjected to unpredictable footshock stress. Acute stress induced marked increase in depolarization-evoked release of glutamate from synaptosomes of prefrontal/frontal cortex in superfusion, and the chronic drug treatments prevented the increase of glutamate release. Stress induced rapid increase in the circulating levels of corticosterone in all rats (both vehicle- and drug-treated, and glutamate release increase was blocked by previous administration of selective antagonist of glucocorticoid receptor (RU 486. On the molecular level, stress induced accumulation of presynaptic SNARE complexes in synaptic membranes (both in vehicle- and drug-treated rats. Patch-clamp recordings of pyramidal neurons in the prefrontal cortex revealed that stress increased glutamatergic transmission through both pre- and postsynaptic mechanisms, and that antidepressants may normalize it by reducing release probability.Acute footshock stress up-regulated depolarization-evoked release of glutamate from synaptosomes of prefrontal/frontal cortex. Stress-induced increase of glutamate release was dependent on stimulation of glucocorticoid receptor by corticosterone. Because all drugs employed did not block either elevation of corticosterone or accumulation of SNARE complexes, the dampening action of the drugs on glutamate release must be downstream of these processes. This novel effect of antidepressants on the response to stress

  3. The effect of nucleotides and adenosine on stimulus-evoked glutamate release from rat brain cortical slices

    OpenAIRE

    Bennett, Gillian C; Boarder, Michael R

    2000-01-01

    Evidence has previously been presented that P1 receptors for adenosine, and P2 receptors for nucleotides such as ATP, regulate stimulus-evoked release of biogenic amines from nerve terminals in the brain. Here we investigated whether adenosine and nucleotides exert presynaptic control over depolarisation-elicited glutamate release.Slices of rat brain cortex were perfused and stimulated with pulses of 46 mM K+ in the presence of the glutamate uptake inhibitor L-trans-pyrrolidine-2,4-dicarboxyl...

  4. Biochemistry of an olfactory purinergic system: dephosphorylation of excitatory nucleotides and uptake of adenosine

    Energy Technology Data Exchange (ETDEWEB)

    Trapido-Rosenthal, H G; Carr, W E; Gleeson, R A

    1987-10-01

    The olfactory organ of the spiny lobster, Panulirus argus, is composed of chemosensory sensilla containing the dendrites of primary chemosensory neurons. Receptors on these dendrites are activated by the nucleotides AMP, ADP, and ATP but not by the nucleoside adenosine. It is shown here that the lobster chemosensory sensilla contain enzymes that dephosphorylate excitatory nucleotides and an uptake system that internalizes the nonexcitatory dephosphorylated product adenosine. The uptake of (/sup 3/H)-adenosine is saturable with increasing concentration, linear with time for up to 3 h, sodium dependent, insensitive to moderate pH changes and has a Km of 7.1 microM and a Vmax of 5.2 fmol/sensillum/min (573 fmol/micrograms of protein/min). Double-label experiments show that sensilla dephosphorylate nucleotides extracellularly; /sup 3/H from adenine-labeled AMP or ATP is internalized, whereas 32P from phosphate-labeled nucleotides is not. The dephosphorylation of AMP is very rapid; /sup 3/H from AMP is internalized at the same rate as /sup 3/H from adenosine. Sensillar 5'-ectonucleotidase activity is inhibited by ADP and the ADP analog alpha, beta-methylene ADP. Collectively, these results indicate that the enzymes and the uptake system whereby chemosensory sensilla of the lobster inactivate excitatory nucleotides and clear adenosine from extracellular spaces are very similar to those present in the internal tissues of vertebrates, where nucleotides have many neuroactive effects.

  5. Astrocyte-derived adenosine is central to the hypnogenic effect of glucose

    Science.gov (United States)

    Scharbarg, Emeric; Daenens, Marion; Lemaître, Frédéric; Geoffroy, Hélène; Guille-Collignon, Manon; Gallopin, Thierry; Rancillac, Armelle

    2016-01-01

    Sleep has been hypothesised to maintain a close relationship with metabolism. Here we focus on the brain structure that triggers slow-wave sleep, the ventrolateral preoptic nucleus (VLPO), to explore the cellular and molecular signalling pathways recruited by an increase in glucose concentration. We used infrared videomicroscopy on ex vivo brain slices to establish that glucose induces vasodilations specifically in the VLPO via the astrocytic release of adenosine. Real-time detection by in situ purine biosensors further revealed that the adenosine level doubles in response to glucose, and triples during the wakefulness period. Finally, patch-clamp recordings uncovered the depolarizing effect of adenosine and its A2A receptor agonist, CGS-21680, on sleep-promoting VLPO neurons. Altogether, our results provide new insights into the metabolically driven release of adenosine. We hypothesise that adenosine adjusts the local energy supply to local neuronal activity in response to glucose. This pathway could contribute to sleep-wake transition and sleep intensity. PMID:26755200

  6. Artificial oxygen carrier with pharmacologic actions of adenosine-5'-triphosphate, adenosine, and reduced glutathione formulated to treat an array of medical conditions.

    Science.gov (United States)

    Simoni, Jan; Simoni, Grace; Moeller, John F; Feola, Mario; Wesson, Donald E

    2014-08-01

    Effective artificial oxygen carriers may offer a solution to tackling current transfusion medicine challenges such as blood shortages, red blood cell storage lesions, and transmission of emerging pathogens. These products, could provide additional therapeutic benefits besides oxygen delivery for an array of medical conditions. To meet these needs, we developed a hemoglobin (Hb)-based oxygen carrier, HemoTech, which utilizes the concept of pharmacologic cross-linking. It consists of purified bovine Hb cross-linked intramolecularly with open ring adenosine-5'-triphosphate (ATP) and intermolecularly with open ring adenosine, and conjugated with reduced glutathione (GSH). In this composition, ATP prevents Hb dimerization, and adenosine promotes formation of Hb polymers as well as counteracts the vasoconstrictive and pro-inflammatory properties of Hb via stimulation of adenosine receptors. ATP also serves as a regulator of vascular tone through activation of purinergic receptors. GSH blocks Hb's extravasation and glomerular filtration by lowering the isoelectric point, as well as shields heme from nitric oxide and reactive oxygen species. HemoTech and its manufacturing technology have been broadly tested, including viral and prion clearance validation studies and various nonclinical pharmacology, toxicology, genotoxicity, and efficacy tests. The clinical proof-of-concept was carried out in sickle cell anemia subjects. The preclinical and clinical studies indicate that HemoTech works as a physiologic oxygen carrier and has efficacy in treating: (i) acute blood loss anemia by providing a temporary oxygen bridge while stimulating an endogenous erythropoietic response; (ii) sickle cell disease by counteracting vaso-occlusive/inflammatory episodes and anemia; and (iii) ischemic vascular diseases particularly thrombotic and restenotic events. The pharmacologic cross-linking of Hb with ATP, adenosine, and GSH showed usefulness in designing an artificial oxygen carrier for

  7. Anticonvulsant activity of B2, an adenosine analog, on chemical convulsant-induced seizures.

    Directory of Open Access Journals (Sweden)

    Min Li

    Full Text Available Epilepsy is a chronic neurological disorder characterized by recurrent seizures. However, approximately one-third of epilepsy patients still suffer from uncontrolled seizures. Effective treatments for epilepsy are yet to be developed. N (6-(3-methoxyl-4-hydroxybenzyl adenine riboside (B2 is a N(6-substitued adenosine analog. Here we describe an investigation of the effects and mechanisms of B2 on chemical convulsant-induced seizures. Seizures were induced in mice by administration of 4-aminopyridine (4-AP, pentylenetetrazol (PTZ, picrotoxin, kainite acid (KA, or strychnine. B2 has a dose-related anticonvulsant effect in these chemical-induced seizure models. The protective effects of B2 include increased latency of seizure onset, decreased seizure occurrence, shorter seizure duration and reduced mortality rate. Radioligand binding and cAMP accumulation assays indicated that B2 might be a functional ligand for both adenosine A1 and A2A receptors. Furthermore, DPCPX, a selective A1 receptor antagonist, but not SCH58261, a selective A2A receptor antagonist, blocked the anticonvulsant effect of B2 on PTZ-induced seizure. c-Fos is a cellular marker for neuronal activity. Immunohistochemical and western blot analyses indicated that B2 significantly reversed PTZ-induced c-Fos expression in the hippocampus. Together, these results indicate that B2 has significant anticonvulsant effects. The anticonvulsant effects of B2 may be attributed to adenosine A1 receptor activation and reduced neuronal excitability in the hippocampus. These observations also support that the use of adenosine receptor agonist may be a promising approach for the treatment of epilepsy.

  8. Stimulant effects of adenosine antagonists on operant behavior: differential actions of selective A2A and A1 antagonists

    Science.gov (United States)

    Randall, Patrick A.; Nunes, Eric J.; Janniere, Simone L.; Stopper, Colin M.; Farrar, Andrew M.; Sager, Thomas N.; Baqi, Younis; Hockemeyer, Jörg; Müller, Christa E.

    2012-01-01

    Rationale Adenosine A2A antagonists can reverse many of the behavioral effects of dopamine antagonists, including actions on instrumental behavior. However, little is known about the effects of selective adenosine antagonists on operant behavior when these drugs are administered alone. Objective The present studies were undertaken to investigate the potential for rate-dependent stimulant effects of both selective and nonselective adenosine antagonists. Methods Six drugs were tested: two nonselective adenosine antagonists (caffeine and theophylline), two adenosine A1 antagonists (DPCPX and CPT), and two adenosine A2A antagonists (istradefylline (KW6002) and MSX-3). Two schedules of reinforcement were employed; a fixed interval 240-s (FI-240 sec) schedule was used to generate low baseline rates of responding and a fixed ratio 20 (FR20) schedule generated high rates. Results Caffeine and theophylline produced rate-dependent effects on lever pressing, increasing responding on the FI-240 sec schedule but decreasing responding on the FR20 schedule. The A2A antagonists MSX-3 and istradefylline increased FI-240 sec lever pressing but did not suppress FR20 lever pressing in the dose range tested. In fact, there was a tendency for istradefylline to increase FR20 responding at a moderate dose. A1 antagonists failed to increase lever pressing rate, but DPCPX decreased FR20 responding at higher doses. Conclusions These results suggest that adenosine A2A antagonists enhance operant response rates, but A1 antagonists do not. The involvement of adenosine A2A receptors in regulating aspects of instrumental response output and behavioral activation may have implications for the treatment of effort-related psychiatric dysfunctions, such as psychomotor slowing and anergia in depression. PMID:21347642

  9. Molecular Pathways of Disturbed Sleep and Depression: Studies on Adenosine and Gene Expression Patterns

    OpenAIRE

    Gass, Natalia

    2010-01-01

    Background: Adenosine is a potent sleep-promoting substance, and one of its targets is the basal forebrain. Fairly little is known about its mechanism of action in the basal forebrain and about the receptor subtype mediating its regulating effects on sleep homeostasis. Homeostatic deficiency might be one of the causes of the profoundly disturbed sleep pattern in major depressive disorder, which could explain the reduced amounts of delta-activity-rich stages 3 and 4. Since major depression has...

  10. receptores

    Directory of Open Access Journals (Sweden)

    Salete Regina Daronco Benetti

    2006-01-01

    Full Text Available Se trata de un estudio etnográfico, que tuvo lo objetivo de interpretar el sistema de conocimiento y del significado atribuidos a la sangre referente a la transfusión sanguínea por los donadores y receptores de un banco de sangre. Para la colecta de las informaciones se observaron los participantes y la entrevista etnográfica se realizó el análisis de dominio, taxonómicos y temáticos. Los dominios culturales fueron: la sangre es vida: fuente de vida y alimento valioso; creencias religiosas: fuentes simbólicas de apoyos; donación sanguínea: un gesto colaborador que exige cuidarse, gratifica y trae felicidad; donación sanguínea: fuente simbólica de inseguridad; estar enfermo es una condición para realizar transfusión sanguínea; transfusión sanguínea: esperanza de vida; Creencias populares: transfusión sanguínea como riesgo para la salud; donadores de sangre: personas benditas; donar y recibir sangre: como significado de felicidad. Temática: “líquido precioso que origina, sostiene, modifica la vida, provoca miedo e inseguridad”.

  11. Adenosine induced ventricular arrhythmias in the emergency room

    NARCIS (Netherlands)

    Tan, H. L.; Spekhorst, H. H.; Peters, R. J.; Wilde, A. A.

    2001-01-01

    While adenosine effectively terminates most supraventricular tachycardias (SVT), rare case reports have demonstrated its proarrhythmic potential, including induction of ventricular tachycardia (VT). The aim of this study was to define the proarrhythmic effects of adenosine in a large, unselected

  12. The free radical scavenger Trolox dampens neuronal hyperexcitability, reinstates synaptic plasticity, and improves hypoxia tolerance in a mouse model of Rett syndrome

    Directory of Open Access Journals (Sweden)

    Oliwia Alicja Janc

    2014-02-01

    Full Text Available Rett syndrome (RS causes severe cognitive impairment, loss of speech, epilepsy, and breathing disturbances with intermittent hypoxia. Also mitochondria are affected; a subunit of respiratory complex III is dysregulated, the inner mitochondrial membrane is leaking protons, and brain ATP levels seem reduced. Our recent assessment of mitochondrial function in MeCP2-deficient mouse (Mecp2-/y hippocampus, confirmed early metabolic alterations, an increased oxidative burden, and a more vulnerable cellular redox balance. As these changes may contribute to the manifestation of symptoms and disease progression, we now evaluated whether free radical scavengers are capable of improving neuronal and mitochondrial function in RS. Acute hippocampal slices of adult mice were incubated with the vitamin E derivative Trolox for 3-5 h. In Mecp2-/y slices this treatment dampened neuronal hyperexcitability, improved short-term plasticity, and fully restored synaptic long-term potentiation. Furthermore, Trolox specifically attenuated the increased hypoxia susceptibility of Mecp2-/y slices. Also, the anticonvulsive effects of Trolox were assessed, but the severity of 4-aminopyridine provoked seizure-like discharges was not significantly affected. Adverse side effects of Trolox on mitochondria can be excluded, but clear indications for an improvement of mitochondrial function were not found. Since several ion-channels and neurotransmitter receptors are redox modulated, the mitochondrial alterations and the associated oxidative burden may contribute to the neuronal dysfunction in RS. We confirmed in Mecp2-/y hippocampus that Trolox dampens neuronal hyperexcitability, reinstates synaptic plasticity, and improves hypoxia tolerance. Therefore, radical scavengers are promising compounds for the treatment of neuronal dysfunction in RS and deserve further detailed evaluation.

  13. Biphasic action of cyclic adenosine 3',5'- monophosphate in gonadotropin-releasing hormone (GnRH) analog-stimulated hormone release from GH3 cells stably transfected with GnRH receptor complementary deoxyribonucleic acid.

    Science.gov (United States)

    Stanislaus, D; Arora, V; Awara, W M; Conn, P M

    1996-03-01

    GH3 cells are a PRL-secreting adenoma cell line derived from pituitary lactotropes. These cells have been stably transfected with rat GnRH receptor complementary DNA to produce four cell lines: GGH(3)1', GGH(3)2', GGH(3)6', and GGH(3)12'. In response to either GnRH or Buserelin (a metabolically stable GnRH agonist), these cell lines synthesize PRL in a cAMP-dependent manner. Only GGH(3)6' cells desensitize in response to persistent treatment with 10(-7) g/ml Buserelin. GGH(3)1', GGH(3)2', and GGH(3)12' cells, however, can be made refractory to Buserelin stimulation by raising cAMP levels either by the addition of (Bu)2cAMP to the medium or by treatment with cholera toxin. In GGH(3) cells, low levels of cAMP fulfill the requirements for a second messenger, whereas higher levels appear to mediate the development of desensitization. The observation that in GGH(3)6' cells, cAMP production persists after the onset of desensitization is consistent with the view that the mechanism responsible for desensitization is distal to the production of cAMP. Moreover, the absence of any significant difference in the amount of cAMP produced per cell in GGH(3)2', GGH(3)6', or GGH(3)12' cells suggests that elevated cAMP production per cell does not explain the development of desensitization in GGH(3)6' cells. We suggest that Buserelin-stimulated PRL synthesis in GGH(3)6' cells is mediated by a different cAMP-dependent protein kinase pool(s) than that in nondesensitizing GGH(3) cells. Such a protein kinase A pool(s) may be more susceptible to degradation via cAMP-mediated mechanisms than the protein kinase pools mediating the Buserelin response in nondesensitizing GGH(3) cells. A similar mechanism has been reported in other systems.

  14. Monoolein-alginate beads as a platform to promote adenosine cutaneous localization and wound healing.

    Science.gov (United States)

    Ng, Wing Y; Migotto, Amanda; Ferreira, Thamyres Soares; Lopes, Luciana B

    2017-09-01

    Alginate beads containing the polar lipid monoolein were developed as a strategy to manage wet wounds by providing improved uptake of excess exudate while releasing adenosine locally for promotion of healing. To obtain monoolein-containing beads, the lipid was mixed with almond oil (2:1w/w), and emulsified within the alginate aqueous dispersion, followed by ionotropic gelation in CaCl 2 solution. Compared to alginate-only, monoolein-alginate systems were 1.44-fold larger, their swelling ability was 1.40-fold higher and adenosine cumulative release was approximately 1.30-fold lower (at 24h). Monoolein-alginate beads were considered safe for topical application as demonstrated by the absence of changes on the viability of reconstructed skin equivalents compared to PBS. Smaller amounts of adenosine were delivered by the beads into and across damaged porcine skin (created by an incisional wound) compared to the drug aqueous solution, and cutaneous localization was favored. More specifically, the beads increased the viable skin layer/receptor phase delivery ratio by approximately 4-fold at 12h post-application. Considering the wide range of adenosine physiological effects and the importance of skin localization for its use in wound healing, these results demonstrate the potential of monoolein-containing beads for localized drug delivery and management of wet wounds. Copyright © 2017 Elsevier B.V. All rights reserved.

  15. Regulation of adenosine deaminase (ADA) on induced mouse experimental autoimmune uveitis (EAU) ‡

    Science.gov (United States)

    Liang, Dongchun; Zuo, Aijun; Zhao, Ronglan; Shao, Hui; Kaplan, Henry J.; Sun, Deming

    2016-01-01

    Adenosine is an important regulator of the immune response and adenosine deaminase (ADA) inhibits this regulatory effect by converting adenosine into functionally inactive molecules. Studies have shown that adenosine receptor (AR) agonists can be either anti- or pro-inflammatory. Clarification of the mechanisms that cause these opposing effects should provide a better guide for therapeutic intervention. In this study, we investigated the effect of ADA on the development of experimental autoimmune uveitis (EAU) induced by immunizing EAU-prone mice with a known uveitogenic peptide, IRBP1–20. Our results showed that the effective time to administer a single dose of ADA to suppress induction of EAU was 8–14 days post-immunization, shortly before EAU expression, but ADA treatment at other time points exacerbated disease. ADA preferentially inhibited Th17 responses and this effect was γδ T cell-dependent. Our results demonstrated that the existing immune status strongly influences the anti- or proinflammatory effects of ADA. Our observations should help improve the design of ADA- and AR-targeted therapies. PMID:26856700

  16. Stimulatory effects of adenosine on prolactin secretion in the pituitary gland of the rat

    Directory of Open Access Journals (Sweden)

    D.L.W. Picanço-Diniz

    2002-07-01

    Full Text Available We investigated the effects of adenosine on prolactin (PRL secretion from rat anterior pituitaries incubated in vitro. The administration of 5-N-methylcarboxamidoadenosine (MECA, an analog agonist that preferentially activates A2 receptors, induced a dose-dependent (1 nM to 1 µM increase in the levels of PRL released, an effect abolished by 1,3-dipropyl-7-methylxanthine, an antagonist of A2 adenosine receptors. In addition, the basal levels of PRL secretion were decreased by the blockade of cyclooxygenase or lipoxygenase pathways, with indomethacin and nordihydroguaiaretic acid (NDGA, respectively. The stimulatory effects of MECA on PRL secretion persisted even after the addition of indomethacin, but not of NDGA, to the medium. MECA was unable to stimulate PRL secretion in the presence of dopamine, the strongest inhibitor of PRL release that works by inducing a decrease in adenylyl cyclase activity. Furthermore, the addition of adenosine (10 nM mimicked the effects of MECA on PRL secretion, an effect that persisted regardless of the presence of LiCl (5 mM. The basal secretion of PRL was significatively reduced by LiCl, and restored by the concomitant addition of both LiCl and myo-inositol. These results indicate that PRL secretion is under a multifactorial regulatory mechanism, with the participation of different enzymes, including adenylyl cyclase, inositol-1-phosphatase, cyclooxygenase, and lipoxygenase. However, the increase in PRL secretion observed in the lactotroph in response to A2 adenosine receptor activation probably was mediated by mechanisms involving regulation of adenylyl cyclase, independent of membrane phosphoinositide synthesis or cyclooxygenase activity and partially dependent on lipoxygenase arachidonic acid-derived substances.

  17. The Use of Noise Dampening Mats to Reduce Heavy-Equipment Noise Exposures in Construction

    Directory of Open Access Journals (Sweden)

    Sabah Saleh

    2017-06-01

    Full Text Available The performance of sound barriers was evaluated to determine their technical effectiveness and practicality in reducing noise exposures to operating engineers in construction. Commercially purchased sound dampening mats (SDMats were installed inside three heavy-equipment engine compartments. Sound pressure levels (SPLs were measured before and after installing the SDMats while the equipment was on idle and full-throttle settings where it normally operates. SPLs inside the heavy-equipment operator cabs were significantly reduced by 5.6–7.6 dBA on the full-throttle setting following installation of the SDMats (p<0.01. The evaluated engineering control intervention was simple to install, affordable, and substantially reduced the engine noise reaching the heavy-equipment operator, potentially reducing reliance on hearing-protection devices to protect construction workers from noise exposures.

  18. Dampening or savoring positive emotions: a dialectical cultural script guides emotion regulation.

    Science.gov (United States)

    Miyamoto, Yuri; Ma, Xiaoming

    2011-12-01

    Four studies examined the hypothesis that, although people may generally want to savor, rather than to dampen, their positive emotions (i.e., hedonic emotion regulation), such a hedonic emotion regulation tendency should be less pronounced for Easterners than for Westerners. Using retrospective memory procedures, Study 1 found that Easterners recalled engaging in hedonic emotion regulation less than Westerners did, even after controlling for their initial emotional reactions. Studies 2-3 showed that cultural differences in emotion regulation were mediated by dialectical beliefs about positive emotions. Study 4 replicated the findings by examining online reports of emotion regulation strategies on the day students received a good grade. Furthermore, there were cultural differences in actual emotion change over time, which was partly explained by dialectical beliefs about positive emotions. These findings highlight the active role cultural scripts play in shaping emotion regulation and emotional experiences. (c) 2011 APA, all rights reserved.

  19. Double throat pressure pulsation dampener for oil-free screw compressors

    Science.gov (United States)

    Lucas, Michael J.

    2005-09-01

    This paper describes a recent invention at Ingersoll-Rand for reducing the pressure pulsations in an oil-free screw compressor. Pressure pulsation is a term used in the air compressor industry to describe the rapid change in pressure with time measured in the downstream piping of the air compressor. The pulsations are due to the rapid opening and closing of the screws as the compressed air is eject from the compressor into the piping system. The pulsations are known to produce excessive noise levels and high levels of vibration in the piping system. Reducing these pulsations is critical to achieving a quiet running compressor. This paper will describe the methodology used to analyze the data and show both computational and experimental results achieved using the pulsation dampener. A patent for this design has been filed with the US patent office.

  20. Microbiota epitope similarity either dampens or enhances the immunogenicity of disease-associated antigenic epitopes.

    Directory of Open Access Journals (Sweden)

    Sebastian Carrasco Pro

    Full Text Available The microbiome influences adaptive immunity and molecular mimicry influences T cell reactivity. Here, we evaluated whether the sequence similarity of various antigens to the microbiota dampens or increases immunogenicity of T cell epitopes. Sets of epitopes and control sequences derived from 38 antigenic categories (infectious pathogens, allergens, autoantigens were retrieved from the Immune Epitope Database (IEDB. Their similarity to microbiome sequences was calculated using the BLOSUM62 matrix. We found that sequence similarity was associated with either dampened (tolerogenic; e.g. most allergens or increased (inflammatory; e.g. Dengue and West Nile viruses likelihood of a peptide being immunogenic as a function of epitope source category. Ten-fold cross-validation and validation using sets of manually curated epitopes and non-epitopes derived from allergens were used to confirm these initial observations. Furthermore, the genus from which the microbiome homologous sequences were derived influenced whether a tolerogenic versus inflammatory modulatory effect was observed, with Fusobacterium most associated with inflammatory influences and Bacteroides most associated with tolerogenic influences. We validated these effects using PBMCs stimulated with various sets of microbiome peptides. "Tolerogenic" microbiome peptides elicited IL-10 production, "inflammatory" peptides elicited mixed IL-10/IFNγ production, while microbiome epitopes homologous to self were completely unreactive for both cytokines. We also tested the sequence similarity of cockroach epitopes to specific microbiome sequences derived from households of cockroach allergic individuals and non-allergic controls. Microbiomes from cockroach allergic households were less likely to contain sequences homologous to previously defined cockroach allergens. These results are compatible with the hypothesis that microbiome sequences may contribute to the tolerization of T cells for allergen

  1. Purinergic Receptors in Ocular Inflammation

    Directory of Open Access Journals (Sweden)

    Ana Guzman-Aranguez

    2014-01-01

    Full Text Available Inflammation is a complex process that implies the interaction between cells and molecular mediators, which, when not properly “tuned,” can lead to disease. When inflammation affects the eye, it can produce severe disorders affecting the superficial and internal parts of the visual organ. The nucleoside adenosine and nucleotides including adenine mononucleotides like ADP and ATP and dinucleotides such as P1,P4-diadenosine tetraphosphate (Ap4A, and P1,P5-diadenosine pentaphosphate (Ap5A are present in different ocular locations and therefore they may contribute/modulate inflammatory processes. Adenosine receptors, in particular A2A adenosine receptors, present anti-inflammatory action in acute and chronic retinal inflammation. Regarding the A3 receptor, selective agonists like N6-(3-iodobenzyl-5′-N-methylcarboxamidoadenosine (CF101 have been used for the treatment of inflammatory ophthalmic diseases such as dry eye and uveoretinitis. Sideways, diverse stimuli (sensory stimulation, large intraocular pressure increases can produce a release of ATP from ocular sensory innervation or after injury to ocular tissues. Then, ATP will activate purinergic P2 receptors present in sensory nerve endings, the iris, the ciliary body, or other tissues surrounding the anterior chamber of the eye to produce uveitis/endophthalmitis. In summary, adenosine and nucleotides can activate receptors in ocular structures susceptible to suffer from inflammatory processes. This involvement suggests the possible use of purinergic agonists and antagonists as therapeutic targets for ocular inflammation.

  2. Severe acute intermittent hypoxia elicits phrenic long-term facilitation by a novel adenosine-dependent mechanism

    Science.gov (United States)

    Nichols, Nicole L.; Dale, Erica A.

    2012-01-01

    Acute intermittent hypoxia [AIH; 3, 5-min episodes; 35–45 mmHg arterial Po2 (PaO2)] elicits serotonin-dependent phrenic long-term facilitation (pLTF), a form of phrenic motor facilitation (pMF) initiated by Gq protein-coupled metabotropic 5-HT2 receptors. An alternate pathway to pMF is induced by Gs protein-coupled metabotropic receptors, including adenosine A2A receptors. AIH-induced pLTF is dominated by the serotonin-dependent pathway and is actually restrained via inhibition from the adenosine-dependent pathway. Here, we hypothesized that severe AIH shifts pLTF from a serotonin-dependent to an adenosine-dependent form of pMF. pLTF induced by severe (25–30 mmHg PaO2) and moderate (45–55 mmHg PaO2) AIH were compared in anesthetized rats, with and without intrathecal (C4) spinal A2A (MSX-3, 130 ng/kg, 12 μl) or 5-HT receptor antagonist (methysergide, 300 μg/kg, 15 μl) injections. During severe, but not moderate AIH, progressive augmentation of the phrenic response during hypoxic episodes was observed. Severe AIH (78% ± 8% 90 min post-AIH, n = 6) elicited greater pLTF vs. moderate AIH (41% ± 12%, n = 8; P MSX-3 (28% ± 6%; n = 6; P 0.05). Thus severe AIH shifts pLTF from a serotonin-dependent to an adenosine-dependent mechanism; the adenosinergic pathway inhibits the serotonergic pathway following moderate AIH. Here we demonstrate a novel adenosine-dependent pathway to pLTF following severe AIH. Shifts in the mechanisms of respiratory plasticity provide the ventilatory control system greater flexibility as challenges that differ in severity are confronted. PMID:22403346

  3. Pharmacokinetic Properties of Adenosine Amine Congener in Cochlear Perilymph after Systemic Administration

    Directory of Open Access Journals (Sweden)

    Hao Chang

    2017-01-01

    Full Text Available Noise-induced hearing loss (NIHL is a global health problem affecting over 5% of the population worldwide. We have shown previously that acute noise-induced cochlear injury can be ameliorated by administration of drugs acting on adenosine receptors in the inner ear, and a selective A1 adenosine receptor agonist adenosine amine congener (ADAC has emerged as a potentially effective treatment for cochlear injury and resulting hearing loss. This study investigated pharmacokinetic properties of ADAC in rat perilymph after systemic (intravenous administration using a newly developed liquid chromatography-tandem mass spectrometry detection method. The method was developed and validated in accordance with the USA FDA guidelines including accuracy, precision, specificity, and linearity. Perilymph was sampled from the apical turn of the cochlea to prevent contamination with the cerebrospinal fluid. ADAC was detected in cochlear perilymph within two minutes following intravenous administration and remained in perilymph above its minimal effective concentration for at least two hours. The pharmacokinetic pattern of ADAC was significantly altered by exposure to noise, suggesting transient changes in permeability of the blood-labyrinth barrier and/or cochlear blood flow. This study supports ADAC development as a potential clinical otological treatment for acute sensorineural hearing loss caused by exposure to traumatic noise.

  4. Decreased extracellular adenosine levels lead to loss of hypoxia-induced neuroprotection after repeated episodes of exposure to hypoxia.

    Directory of Open Access Journals (Sweden)

    Mei Cui

    Full Text Available Achieving a prolonged neuroprotective state following transient ischemic attacks (TIAs is likely to effectively reduce the brain damage and neurological dysfunction associated with recurrent stroke. HPC is a phenomenon in which advanced exposure to mild hypoxia reduces the stroke volume produced by a subsequent TIA. However, this neuroprotection is not long-lasting, with the effects reaching a peak after 3 days. Therefore, in this study, we investigated the use of multiple episodes of hypoxic exposure at different time intervals to induce longer-term protection in a mouse stroke model. C57BL/6 mice were subjected to different hypoxic preconditioning protocols: a single episode of HPC or five identical episodes at intervals of 3 days (E3d HPC or 6 days (E6d HPC. Three days after the last hypoxic exposure, temporary middle cerebral artery occlusion (MCAO was induced. The effects of these HPC protocols on hypoxia-inducible factor (HIF regulated gene mRNA expression were measured by quantitative PCR. Changes in extracellular adenosine concentrations, known to exert neuroprotective effects, were also measured using in vivo microdialysis and high pressure liquid chromatography (HPLC. Neuroprotection was provided by E6d HPC but not E3d HPC. HIF-regulated target gene expression increased significantly following all HPC protocols. However, E3d HPC significantly decreased extracellular adenosine and reduced cerebral blood flow in the ischemic region with upregulated expression of the adenosine transporter, equilibrative nucleoside transporter 1 (ENT1. An ENT1 inhibitor, propentofylline increased the cerebral blood flow and re-established neuroprotection in E3d HPC. Adenosine receptor specific antagonists showed that adenosine mainly through A1 receptor mediates HPC induced neuroprotection. Our data indicate that cooperation of HIF-regulated genes and extracellular adenosine is necessary for HPC-induced neuroprotection.

  5. Cold induced changes of adenosine levels in common eelpout (Zoarces viviparus): a role in modulating cytochrome c oxidase expression.

    Science.gov (United States)

    Eckerle, L G; Lucassen, M; Hirse, T; Pörtner, H O

    2008-04-01

    Exposure of ectothermic organisms to variations in temperatures causes a transient mismatch between energy supply and demand, which needs to be compensated for during acclimation. Adenosine accumulation from ATP breakdown indicates such an imbalance and its reversal reflects a restoration of energy status. We monitored adenosine levels in blood serum and liver of common eelpout (Zoarces viviparus) during cold exposure in vivo. Furthermore, we tested its effect on the pattern of thermal acclimation in hepatocytes isolated from cold- (4 degrees C) versus warm- (11 degrees C) exposed fish. Adenosine levels increased during cold exposure in vivo and reached a transient maximum after 24 h in serum, but remained permanently elevated in liver. Whole animal cold acclimation induced a rise of liver citrate synthase activity by 44+/-15%, but left cytochrome c oxidase activity (COX) and RNA expression of the respective genes unchanged. Cold incubation of hepatocytes from warm-acclimated fish failed to cause an increase of mitochondrial enzyme activities despite increased COX4 mRNA levels. Conversely, warm acclimation of hepatocytes from cold-acclimated fish reduced both enzyme activities and COX2 and COX4 mRNA levels by 26-37%. Adenosine treatment of both warm- and cold-acclimated hepatocytes suppressed COX activities but activated COX mRNA expression. These effects were not receptor mediated. The present findings indicate that adenosine has the potential to regulate mitochondrial functioning in vivo, albeit the pathways resulting in the contrasting effects on expression and activity need to be identified.

  6. Turning lemonade into lemons: Dampening appraisals reduce positive affect and increase negative affect during positive activity scheduling.

    Science.gov (United States)

    Burr, Leigh-Anne; Javiad, Mahmood; Jell, Grace; Werner-Seidler, Aliza; Dunn, Barnaby D

    2017-04-01

    The way individuals appraise positive emotions may modulate affective experience during positive activity scheduling. Individuals may either engage in dampening appraisals (e.g., think "this is too good to last") or amplifying appraisals (e.g., think "I deserve this"). A cross-over randomized design was used to examine the consequences of these appraisal styles. Participants (N = 43) rated positive affect (PA) and negative affect (NA) during four daily walks in pleasant locations, whilst following dampening, emotion-focus amplifying (focusing on how good one feels), self-focus amplifying (focusing on positive self qualities), or control instructions. There was no difference between the two amplifying and control conditions, which all increased PA and reduced NA during the walks. However, the dampening condition significantly differed from all other conditions, reducing PA and increasing NA during the walk. Individual differences in anhedonia symptoms did not significantly moderate the pattern of findings. This evidence supports the view that dampening appraisals may be one mechanism driving anhedonia and may account for why positive activity scheduling can sometimes backfire when utilized in the clinic. Copyright © 2017 Elsevier Ltd. All rights reserved.

  7. Increased activity of vascular adenosine deaminase in atherosclerosis and therapeutic potential of its inhibition.

    Science.gov (United States)

    Kutryb-Zajac, Barbara; Mateuszuk, Lukasz; Zukowska, Paulina; Jasztal, Agnieszka; Zabielska, Magdalena A; Toczek, Marta; Jablonska, Patrycja; Zakrzewska, Agnieszka; Sitek, Barbara; Rogowski, Jan; Lango, Romuald; Slominska, Ewa M; Chlopicki, Stefan; Smolenski, Ryszard T

    2016-11-01

    Extracellular nucleotides and adenosine that are formed or degraded by membrane-bound ecto-enzymes could affect atherosclerosis by regulating the inflammation and thrombosis. This study aimed to evaluate a relation between ecto-enzymes that convert extracellular adenosine triphosphate to adenine dinucleotide phosphate, adenosine monophosphate, adenosine, and inosine on the surface of the vessel wall with the severity or progression of experimental and clinical atherosclerosis. Furthermore, we tested whether the inhibition of adenosine deaminase will block the development of experimental atherosclerosis. Vascular activities of ecto-nucleoside triphosphate diphosphohydrolase 1, ecto-5'-nucleotidase, and ecto-adenosine deaminase (eADA) were measured in aortas of apolipoprotein E-/- low density lipoprotein receptor (ApoE-/-LDLR-/-) and wild-type mice as well as in human aortas. Plaques were analysed in the entire aorta, aortic root, and brachiocephalic artery by Oil-Red O and Orcein Martius Scarlet Blue staining and vascular accumulation of macrophages. The cellular location of ecto-enzymes was analysed by immunofluorescence. The effect of eADA inhibition on atherosclerosis progression was studied by a 2-month deoxycoformycin treatment of ApoE-/-LDLR-/- mice. The vascular eADA activity prominently increased in ApoE-/-LDLR-/- mice when compared with wild type already at the age of 1 month and progressed along atherosclerosis development, reaching a 10-fold difference at 10 months. The activity of eADA correlated with atherosclerotic changes in human aortas. High abundance of eADA in atherosclerotic vessels originated from activated endothelial cells and macrophages. There were no changes in ecto-nucleoside triphosphate diphosphohydrolase 1 activity, whereas ecto-5'-nucleotidase was moderately decreased in ApoE-/-LDLR-/- mice. Deoxycoformycin treatment attenuated plaque development in aortic root and brachiocephalic artery of ApoE-/-LDLR-/- mice, suppressed vascular

  8. Interaction of renin-angiotensin system and adenosine monophosphate-activated protein kinase signaling pathway in renal carcinogenesis of uninephrectomized rats.

    Science.gov (United States)

    Yang, Ke-Ke; Sui, Yi; Zhou, Hui-Rong; Zhao, Hai-Lu

    2017-05-01

    Renin-angiotensin system and adenosine monophosphate-activated protein kinase signaling pathway both play important roles in carcinogenesis, but the interplay of renin-angiotensin system and adenosine monophosphate-activated protein kinase in carcinogenesis is not clear. In this study, we researched the interaction of renin-angiotensin system and adenosine monophosphate-activated protein kinase in renal carcinogenesis of uninephrectomized rats. A total of 96 rats were stratified into four groups: sham, uninephrectomized, and uninephrectomized treated with angiotensin-converting enzyme inhibitor or angiotensin receptor blocker. Renal adenosine monophosphate-activated protein kinase and its downstream molecule acetyl coenzyme A carboxylase were detected by immunohistochemistry and western blot at 10 months after uninephrectomy. Meanwhile, we examined renal carcinogenesis by histological transformation and expressions of Ki67 and mutant p53. During the study, fasting lipid profiles were detected dynamically at 3, 6, 8, and 10 months. The results indicated that adenosine monophosphate-activated protein kinase expression in uninephrectomized rats showed 36.8% reduction by immunohistochemistry and 89.73% reduction by western blot. Inversely, acetyl coenzyme A carboxylase expression increased 83.3% and 19.07% in parallel to hyperlipidemia at 6, 8, and 10 months. The histopathology of carcinogenesis in remnant kidneys was manifested by atypical proliferation and carcinoma in situ, as well as increased expressions of Ki67 and mutant p53. Intervention with angiotensin-converting enzyme inhibitor or angiotensin receptor blocker significantly prevented the inhibition of adenosine monophosphate-activated protein kinase signaling pathway and renal carcinogenesis in uninephrectomized rats. In conclusion, the novel findings suggest that uninephrectomy-induced disturbance in adenosine monophosphate-activated protein kinase signaling pathway resulted in hyperlipidemia and

  9. Low, but not high, dose caffeine is a readily available probe for adenosine actions.

    Science.gov (United States)

    Fredholm, Bertil B; Yang, Jiangning; Wang, Yingqing

    2017-06-01

    Caffeine is very widely used and knowledge of its mode of action can be used to gain an understanding of basal physiological regulation. This review makes the point that caffeine is - in low doses - an antagonist of adenosine acting at A 1 , A 2A and A 2B receptors. We use published and unpublished data to make the point that high dose effects of caffeine are not only qualitatively different but have a different underlying mechanism. Therefore one must be careful in only using epidemiological or experimental data where rather low doses of caffeine are used to draw conclusions about the physiology and pathophysiology of adenosine. Copyright © 2016 Elsevier Ltd. All rights reserved.

  10. Impaired cerebral microcirculation induced by ammonium chloride in rats is due to cortical adenosine release

    DEFF Research Database (Denmark)

    Bjerring, Peter Nissen; Bjerrum, Esben Jannik; Larsen, Fin Stolze

    2018-01-01

    BACKGROUND: Liver failure results in hyperammonaemia, impaired regulation of cerebral microcirculation, encephalopathy and death. However, the key mediator that alters cerebral microcirculation remains unidentified. In this study we show that topical ammonium significantly increases periarteriolar......: In patients with liver failure disturbances in the brain function is caused in part by ammonia toxicity. In our project we have studied how ammonia, through adenosine release, affects the blood flow in the brain of rats. In our experimental model we demonstrated that the detrimental effect of ammonia on blood...... flow regulation was counteracted by blocking the adenosine receptors in the brain. With this observation we have identified a novel potential treatment target. If we can confirm our findings in a future clinical study it might help patients suffering from liver failure and the severe condition called...

  11. Role of adenosine in regulating the heterogeneity of skeletal muscle blood flow during exercise in humans

    DEFF Research Database (Denmark)

    Heinonen, Ilkka; Nesterov, Sergey V; Kemppainen, Jukka

    2007-01-01

    receptor blockade. BF heterogeneity within muscles was calculated from 16-mm(3) voxels in BF images and heterogeneity among the muscles from the mean values of the four QF compartments. Mean BF in the whole QF and its four parts increased, and heterogeneity decreased with workload both without......Evidence from both animal and human studies suggests that adenosine plays a role in the regulation of exercise hyperemia in skeletal muscle. We tested whether adenosine also plays a role in the regulation of blood flow (BF) distribution and heterogeneity among and within quadriceps femoris (QF...... and with theophylline (P heterogeneity among the QF muscles, yet blockade increased within-muscle BF heterogeneity in all four QF muscles (P = 0.03). Taken together, these results show that BF becomes less heterogeneous with increasing...

  12. Novel ligands for the human adenosine A1 receptor

    NARCIS (Netherlands)

    Chang, Lisa Chung Wai

    2005-01-01

    This research describes the quest to create 'super-caffeines', substances that only produce the desired effects of caffeine, and unlike caffeine, substances that should only have to be taken in measured, minute, controlled amounts to achieve these effects. Unless particular steps are taken to avoid

  13. Role of dopamine and adenosine receptors in tumor cell recognition

    Czech Academy of Sciences Publication Activity Database

    Fišerová, Anna; Vannucci, L.; Kovářů, H.; Kuldová, M.; Matějková, O.; Horváth, Ondřej; Starec, M.; Pospíšil, Miloslav

    2000-01-01

    Roč. 6, Suppl 1 (2000), s. 59 ISSN 1107-3756. [World Congress on Advances in Oncology /5./. 19.10.2000-21.10.2000, Hersonissos] R&D Projects: GA ČR GA310/98/0347; GA ČR GV312/98/K034 Subject RIV: EC - Immunology

  14. Adenosine deaminase activity of erythrocytes in hyperuricemia

    International Nuclear Information System (INIS)

    Krueger, W.; Richter, V.; Beenken, O.; Weinhold, D.; Hirschberg, K.; Rotzsch, W.; Akademie der Wissenschaften der DDR, Leipzig. Zentralinstitut fuer Isotopen- und Strahlenforschung)

    1982-01-01

    Erythrocytic adenosine deaminase (ADA) activity was determined in 55 patients with primary hyperuricemia and in 37 healthy control persons. Unlike the controls, the ADA activity in the patient group showed a two-peak response. Hyperuricemia patients with high ADA activity also exhibited increased uric acid excretion and elevated 15 N incorporation into uric acid. High activity values of erythrocytic ADA can be interpreted as an uric acid overproduction, giving hints for a therapeutic plan. (author)

  15. Increased orbitofrontal brain activation after administration of a selective adenosine A2A antagonist in cocaine dependent subjects

    Directory of Open Access Journals (Sweden)

    F. Gerard eMoeller

    2012-05-01

    Full Text Available Background: Positron Emission Tomography imaging studies provide evidence of reduced dopamine function in cocaine dependent subjects in the striatum, which is correlated with prefrontal cortical glucose metabolism, particularly in the orbitofrontal cortex. However, whether enhancement of dopamine in the striatum in cocaine dependent subjects would be associated with changes in prefrontal cortical brain activation is unknown. One novel class of medications that enhance dopamine function via heteromer formation with dopamine receptors in the striatum is the selective adenosine A2A receptor antagonists. This study sought to determine the effects administration of the selective adenosine A2A receptor antagonist SYN115 on brain function in cocaine dependent subjects. Methodology/Principle Findings: Twelve cocaine dependent subjects underwent two fMRI scans (one after a dose of placebo and one after a dose of 100 mg of SYN115 while performing a working memory task with 3 levels of difficulty (3, 5, and 7 digits. fMRI results showed that for 7-digit working memory activation there was significantly greater activation from SYN115 compared to placebo in portions of left (L lateral orbitofrontal cortex, L insula, and L superior and middle temporal pole. Conclusion/Significance: These findings are consistent with enhanced dopamine function in the striatum in cocaine dependent subjects via blockade of adenosine A2A receptors producing increased brain activation in the orbitofrontal cortex and other cortical regions. This suggests that at least some of the changes in brain activation in prefrontal cortical regions in cocaine dependent subjects may be related to altered striatal dopamine function, and that enhancement of dopamine function via adenosine A2A receptor blockade could be explored further for amelioration of neurobehavioral deficits associated with chronic cocaine use.

  16. Measurement of plasma adenosine concentration: methodological and physiological considerations

    International Nuclear Information System (INIS)

    Gewirtz, H.; Brown, P.; Most, A.S.

    1987-01-01

    This study tested the hypothesis that measurements of plasma adenosine concentration made on samples of blood obtained in dipyridamole and EHNA (i.e., stopping solution) may be falsely elevated as a result of ongoing in vitro production and accumulation of adenosine during sample processing. Studies were performed with samples of anticoagulated blood obtained from anesthesized domestic swine. Adenosine concentration of ultra filtrated plasma was determined by HPLC. The following parameters were evaluated: (i) rate of clearance of [ 3 H]adenosine added to plasma, (ii) endogenous adenosine concentration of matched blood samples obtained in stopping solution alone, stopping solution plus EDTA, and perchloric acid (PCA), (iii) plasma and erythrocyte endogenous adenosine concentration in nonhemolyzed samples, and (iv) plasma adenosine concentration of samples hemolyzed in the presence of stopping solution alone or stopping solution plus EDTA. We observed that (i) greater than or equal to 95% of [ 3 H]adenosine added to plasma is removed from it by formed elements of the blood in less than 20 s, (ii) plasma adenosine concentration of samples obtained in stopping solution alone is generally 10-fold greater than that of matched samples obtained in stopping solution plus EDTA, (iii) deliberate mechanical hemolysis of blood samples obtained in stopping solution alone resulted in substantial augmentation of plasma adenosine levels in comparison with matched nonhemolyzed specimens--addition of EDTA to stopping solution prevented this, and (iv) adenosine content of blood samples obtained in PCA agreed closely with the sum of plasma and erythrocyte adenosine content of samples obtained in stopping solution plus EDTA

  17. Turnover of adenosine in plasma of human and dog blood

    International Nuclear Information System (INIS)

    Moeser, G.H.S.; Schrader, J.; Deussen, A.

    1989-01-01

    To determine half-life and turnover of plasma adenosine, heparinized blood from healthy volunteers was incubated with radiolabeled adenosine in the physiological concentration range of 0.1-1 microM. Plasma levels of adenosine in vitro were 82 +/- 14 nM and were similar to those determined immediately after blood collection with a ''stopping solution.'' Dipyridamole (83 microM) and erythro-9(2-hydroxynon-3yl)-adenine (EHNA) (8 microM) did not measurably alter basal adenosine levels but completely blocked the uptake of added adenosine. Inhibition of ecto-5'-nucleotidase with 100 microM alpha, beta-methyleneadenosine 5'-diphosphate (AOPCP) reduced plasma adenosine to 22 +/- 6 nM. For the determination of adenosine turnover, the decrease in specific radioactivity of added [ 3 H]adenosine was measured using a dipyridamole-containing stopping solution. Without altering basal adenosine levels, the half-life was estimated to be 0.6 s. Similar experiments were carried out with washed erythrocytes or in the presence of AOPCP, yielding half-lives of 0.7 and 0.9 s, respectively. When the initial adenosine concentration was 1 microM, its specific activity decreased by only 11% within 5 s, whereas total plasma adenosine exponentially decreased with a half-life of 1.5 s. Venous plasma concentrations were measured after relief of a 3-min forearm ischemia. Changes in plasma adenosine did not correlate well with changes in blood flow but were augmented in the presence of dipyridamole

  18. Dead-blow hammer design applied to a calibration target mechanism to dampen excessive rebound

    Science.gov (United States)

    Lim, Brian Y.

    1991-01-01

    An existing rotary electromagnetic driver was specified to be used to deploy and restow a blackbody calibration target inside of a spacecraft infrared science instrument. However, this target was much more massive than any other previously inherited design applications. The target experienced unacceptable bounce when reaching its stops. Without any design modification, the momentum generated by the driver caused the target to bounce back to its starting position. Initially, elastomeric dampers were used between the driver and the target. However, this design could not prevent the bounce, and it compromised the positional accuracy of the calibration target. A design that successfully met all the requirements incorporated a sealed pocket 85 percent full of 0.75 mm diameter stainless steel balls in the back of the target to provide the effect of a dead-blow hammer. The energy dissipation resulting from the collision of balls in the pocket successfully dampened the excess momentum generated during the target deployment. The disastrous effects of new requirements on a design with a successful flight history, the modifications that were necessary to make the device work, and the tests performed to verify its functionality are described.

  19. Intranasal Oxytocin Administration Dampens Amygdala Reactivity towards Emotional Faces in Male and Female PTSD Patients.

    Science.gov (United States)

    Koch, Saskia Bj; van Zuiden, Mirjam; Nawijn, Laura; Frijling, Jessie L; Veltman, Dick J; Olff, Miranda

    2016-05-01

    Post-traumatic stress disorder (PTSD) is a disabling psychiatric disorder. As a substantial part of PTSD patients responds poorly to currently available psychotherapies, pharmacological interventions boosting treatment response are needed. Because of its anxiolytic and pro-social properties, the neuropeptide oxytocin (OT) has been proposed as promising strategy for treatment augmentation in PTSD. As a first step to investigate the therapeutic potential of OT in PTSD, we conducted a double-blind, placebo-controlled, cross-over functional MRI study examining OT administration effects (40 IU) on amygdala reactivity toward emotional faces in unmedicated male and female police officers with (n=37, 21 males) and without (n=40, 20 males) PTSD. Trauma-exposed controls were matched to PTSD patients based on age, sex, years of service and educational level. Under placebo, the expected valence-dependent amygdala reactivity (ie, greater activity toward fearful-angry faces compared with happy-neutral faces) was absent in PTSD patients. OT administration dampened amygdala reactivity toward all emotional faces in male and female PTSD patients, but enhanced amygdala reactivity in healthy male and female trauma-exposed controls, independent of sex and stimulus valence. In PTSD patients, greater anxiety prior to scanning and amygdala reactivity during the placebo session were associated with greater reduction of amygdala reactivity after OT administration. Taken together, our results indicate presumably beneficial neurobiological effects of OT administration in male and female PTSD patients. Future studies should investigate OT administration in clinical settings to fully appreciate its therapeutic potential.

  20. Primary adenosine monophosphate (AMP) deaminase deficiency in a hypotonic infant.

    Science.gov (United States)

    Castro-Gago, Manuel; Gómez-Lado, Carmen; Pérez-Gay, Laura; Eirís-Puñal, Jesús; Martínez, Elena Pintos; García-Consuegra, Inés; Martín, Miguel Angel

    2011-06-01

    The spectrum of the adenosine monophosphate (AMP) deaminase deficiency ranges from asymptomatic carriers to patients who manifest exercise-induced muscle pain, occasionally rhabdomyolysis, and idiopathic hyperCKemia. However, previous to the introduction of molecular techniques, rare cases with congenital weakness and hypotonia have also been reported. We report a 6-month-old girl with the association of congenital muscle weakness and hypotonia, muscle deficiency of adenosine monophosphate deaminase, and the homozygous C to T mutation at nucleotide 34 of the adenosine monophosphate deaminase-1 gene. This observation indicates the possible existence of a primary adenosine monophosphate deaminase deficiency manifested by congenital muscle weakness and hypotonia.

  1. Effects of high doses of intracoronary adenosine on the assessment of fractional flow reserve

    Directory of Open Access Journals (Sweden)

    Ahmed Khashaba

    2014-03-01

    Conclusions: Intracoronary adenosine, at doses higher than currently suggested, lows obtaining FFR values similar to IV adenosine. Intravenous adenosine, which remains the gold standard, might thus be reserved for those lesions with equivocal FFR values.

  2. Granulocyte colony-stimulating factor and drugs elevating extracellular adenosine synergize to enhance haematopoietic reconstitution in irradiated mice

    Energy Technology Data Exchange (ETDEWEB)

    Pospisil, M.; Hofer, M.; Netikova, J.; Hola, J.; Vacek, A. [Academy of Sciences of the Czech Republic, Inst. of Biophysics, Brno (Czech Republic); Znojil, V.; Vacha, J. [Masaryk Univ., Medical Faculty, Brno (Czech Republic)

    1998-03-01

    The activation of adenosine receptors has recently been demonstrated to stimulate haematopoiesis. In the present study, we investigated the ability of drugs elevating extracellular adenosine to influence curative effects of granulocyte colony-stimulating factor (G-CSF) in mice exposed to a sublethal dose of 4 Gy of {sup 60}Co radiation. Elevation of extracellular adenosine in mice was induced by the combined administration of dipyridamole, a drug inhibiting the cellular uptake of adenosine, and adenosine monophosphate (AMP), an adenosine prodrug. The effects of dipyridamole plus AMP, and G-CSF, administered either alone or in combination, were evaluated. The drugs were injected to mice in a 4-d treatment regimen starting on d 3 after irradiation and the haematopoietic response was evaluated on d 7, 10, 14, 18 and 24 after irradiation. While the effects of G-CSF on the late maturation stages of blood cells, appearing shortly after the completion of the treatment, were not influenced by dipyridamole plus AMP, positive effects of the combination therapy occurred in the post-irradiation recovery phase which is dependent on the repopulation of haematopoietic stem cells. This was indicated by the significant elevation of counts of granulocyte-macrophage progenitor cells (GM-CFC) and granulocytic cells in the bone marrow (d 14), of GM-CFC (d 14), granulocytic and erythroid cells (d 14 and 18) in the spleen, and of neutrophils (d 18), monocytes (d 14 and 18) and platelets (d 18) in the peripheral blood. These effects suggest that the repopulation potential of the combination therapy lies in a common multi-lineage cell population. The results of this study implicate the promising possibility to enhance the curative effects of G-CSF under conditions of myelosuppressive state induced by radiation exposure. (au) 43 refs.

  3. Granulocyte colony-stimulating factor and drugs elevating extracellular adenosine synergize to enhance haematopoietic reconstitution in irradiated mice

    International Nuclear Information System (INIS)

    Pospisil, M.; Hofer, M.; Netikova, J.; Hola, J.; Vacek, A.; Znojil, V.; Vacha, J.

    1998-01-01

    The activation of adenosine receptors has recently been demonstrated to stimulate haematopoiesis. In the present study, we investigated the ability of drugs elevating extracellular adenosine to influence curative effects of granulocyte colony-stimulating factor (G-CSF) in mice exposed to a sublethal dose of 4 Gy of 60 Co radiation. Elevation of extracellular adenosine in mice was induced by the combined administration of dipyridamole, a drug inhibiting the cellular uptake of adenosine, and adenosine monophosphate (AMP), an adenosine prodrug. The effects of dipyridamole plus AMP, and G-CSF, administered either alone or in combination, were evaluated. The drugs were injected to mice in a 4-d treatment regimen starting on d 3 after irradiation and the haematopoietic response was evaluated on d 7, 10, 14, 18 and 24 after irradiation. While the effects of G-CSF on the late maturation stages of blood cells, appearing shortly after the completion of the treatment, were not influenced by dipyridamole plus AMP, positive effects of the combination therapy occurred in the post-irradiation recovery phase which is dependent on the repopulation of haematopoietic stem cells. This was indicated by the significant elevation of counts of granulocyte-macrophage progenitor cells (GM-CFC) and granulocytic cells in the bone marrow (d 14), of GM-CFC (d 14), granulocytic and erythroid cells (d 14 and 18) in the spleen, and of neutrophils (d 18), monocytes (d 14 and 18) and platelets (d 18) in the peripheral blood. These effects suggest that the repopulation potential of the combination therapy lies in a common multi-lineage cell population. The results of this study implicate the promising possibility to enhance the curative effects of G-CSF under conditions of myelosuppressive state induced by radiation exposure. (au)

  4. Adenosine deaminase-related growth factors stimulate cell proliferation in Drosophila by depleting extracellular adenosine

    Czech Academy of Sciences Publication Activity Database

    Žurovec, Michal; Doležal, Tomáš; Gaži, Michal; Pavlová, Eva; Bryant, P. J.

    2002-01-01

    Roč. 99, č. 7 (2002), s. 4403-4408 ISSN 0027-8424 R&D Projects: GA ČR GA204/01/1022; GA AV ČR IAA5007107 Institutional research plan: CEZ:AV0Z5007907 Keywords : adenosine daminase * minimal medium Subject RIV: CE - Biochemistry Impact factor: 10.701, year: 2002

  5. Prostatic acid phosphatase is an ectonucleotidase and suppresses pain by generating adenosine

    Science.gov (United States)

    Zylka, Mark J.; Sowa, Nathaniel A.; Taylor-Blake, Bonnie; Twomey, Margaret A.; Herrala, Annakaisa; Voikar, Vootele; Vihko, Pirkko

    2008-01-01

    SUMMARY Thiamine monophosphatase (TMPase, also known as Fluoride-Resistant Acid Phosphatase) is a classic histochemical marker of small-diameter dorsal root ganglia neurons. The molecular identity of TMPase is currently unknown. We found that TMPase is identical to the transmembrane isoform of Prostatic Acid Phosphatase (PAP), an enzyme with unknown molecular and physiological functions. We then found that PAP knockout mice have normal acute pain sensitivity but enhanced sensitivity in chronic inflammatory and neuropathic pain models. In gain-of-function studies, intraspinal injection of PAP protein has potent anti-nociceptive, anti-hyperalgesic and anti-allodynic effects that last longer than the opioid analgesic morphine. PAP suppresses pain by functioning as an ecto-5’-nucleotidase. Specifically, PAP dephosphorylates extracellular adenosine monophosphate (AMP) to adenosine and activates A1-adenosine receptors in dorsal spinal cord. Our studies reveal molecular and physiological functions for PAP in purine nucleotide metabolism and nociception and suggest a novel use for PAP in the treatment of chronic pain. PMID:18940592

  6. A defect in KCa3.1 channel activity limits the ability of CD8+ T cells from cancer patients to infiltrate an adenosine-rich microenvironment.

    Science.gov (United States)

    Chimote, Ameet A; Balajthy, Andras; Arnold, Michael J; Newton, Hannah S; Hajdu, Peter; Qualtieri, Julianne; Wise-Draper, Trisha; Conforti, Laura

    2018-04-24

    The limited ability of cytotoxic T cells to infiltrate solid tumors hampers immune surveillance and the efficacy of immunotherapies in cancer. Adenosine accumulates in solid tumors and inhibits tumor-specific T cells. Adenosine inhibits T cell motility through the A 2A receptor (A 2A R) and suppression of KCa3.1 channels. We conducted three-dimensional chemotaxis experiments to elucidate the effect of adenosine on the migration of peripheral blood CD8 + T cells from head and neck squamous cell carcinoma (HNSCC) patients. The chemotaxis of HNSCC CD8 + T cells was reduced in the presence of adenosine, and the effect was greater on HNSCC CD8 + T cells than on healthy donor (HD) CD8 + T cells. This response correlated with the inability of CD8 + T cells to infiltrate tumors. The effect of adenosine was mimicked by an A 2A R agonist and prevented by an A 2A R antagonist. We found no differences in A 2A R expression, 3',5'-cyclic adenosine monophosphate abundance, or protein kinase A type 1 activity between HNSCC and HD CD8 + T cells. We instead detected a decrease in KCa3.1 channel activity, but not expression, in HNSCC CD8 + T cells. Activation of KCa3.1 channels by 1-EBIO restored the ability of HNSCC CD8 + T cells to chemotax in the presence of adenosine. Our data highlight the mechanism underlying the increased sensitivity of HNSCC CD8 + T cells to adenosine and the potential therapeutic benefit of KCa3.1 channel activators, which could increase infiltration of these T cells into tumors. Copyright © 2018 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.

  7. Effects of 2 adenosine antagonists, quercetin and caffeine, on vigilance and mood.

    Science.gov (United States)

    Olson, Craig A; Thornton, Jennifer A; Adam, Gina E; Lieberman, Harris R

    2010-10-01

    Quercetin, a phenolic flavonoid found in small quantities in some fruits and vegetables, is an adenosine receptor antagonist in vitro marketed as a dietary supplement for purported caffeine-like effects. A double-blind, placebo-controlled, between-subjects study was conducted to compare the behavioral effects of quercetin to a central adenosine receptor antagonist, caffeine. Fifty-seven volunteers received either 2000 mg of quercetin dihydrate (a dose estimated based on in vitro receptor binding to be equivalent in potency to 200 mg of caffeine), placebo, or 200 mg of caffeine. One hour later, a 45-minute visual vigilance task was administered. The Profile of Mood States questionnaire was completed before treatment and immediately after vigilance testing. On the vigilance task, caffeine increased the number of stimuli detected (P mood disturbance Profile of Mood States scores compared with placebo. Quercetin did not significantly alter any parameter, but values were typically intermediate between caffeine and placebo on those tests affected by caffeine. Quercetin is unlikely to have any effects when consumed by humans in quantities present in the diet or in dietary supplements. Caffeine (200 mg) administration resulted in the expected effects on vigilance and mood.

  8. The dampening effect of employees' future orientation on cyberloafing behaviors: the mediating role of self-control.

    Science.gov (United States)

    Zhang, Heyun; Zhao, Huanhuan; Liu, Jingxuan; Xu, Yan; Lu, Hui

    2015-01-01

    Previous studies on reducing employees' cyberloafing behaviors have primarily examined the external control factors but seldomly taken individual internal subjective factors into consideration. Future orientation, an important individual factor, is defined as the extent to which one plans for future time and considers future consequences of one's current behavior. To explore further whether and how employees' future orientation can dampen their cyberloafing behaviors, two studies were conducted to examine the relationship between employees' future orientation and cyberloafing behaviors. The mediation effect of employees' objective and subjective self-control between them was also examined. In Study 1, a set of questionnaires was completed, and the results revealed that the relationship between employees' future orientation and cyberloafing behaviors was negative, and objective self-control mediated the relationship. Next, we conducted a priming experiment (Study 2) to examine the causal relationship and psychological mechanism between employees' future orientation and cyberloafing behaviors. The results demonstrated that employees' future-orientation dampened their attitudes and intentions to engage in cyberloafing, and subjective self-control mediated this dampening effect. Theoretical and practical implications of these findings are also discussed.

  9. The dampening effect of employees’ future orientation on cyberloafing behaviors: the mediating role of self-control

    Science.gov (United States)

    Zhang, Heyun; Zhao, Huanhuan; Liu, Jingxuan; Xu, Yan; Lu, Hui

    2015-01-01

    Previous studies on reducing employees’ cyberloafing behaviors have primarily examined the external control factors but seldomly taken individual internal subjective factors into consideration. Future orientation, an important individual factor, is defined as the extent to which one plans for future time and considers future consequences of one’s current behavior. To explore further whether and how employees’ future orientation can dampen their cyberloafing behaviors, two studies were conducted to examine the relationship between employees’ future orientation and cyberloafing behaviors. The mediation effect of employees’ objective and subjective self-control between them was also examined. In Study 1, a set of questionnaires was completed, and the results revealed that the relationship between employees’ future orientation and cyberloafing behaviors was negative, and objective self-control mediated the relationship. Next, we conducted a priming experiment (Study 2) to examine the causal relationship and psychological mechanism between employees’ future orientation and cyberloafing behaviors. The results demonstrated that employees’ future-orientation dampened their attitudes and intentions to engage in cyberloafing, and subjective self-control mediated this dampening effect. Theoretical and practical implications of these findings are also discussed. PMID:26483735

  10. The dampening effect of employees’ future orientation on cyberloafing behaviors: The mediating role of self-control

    Directory of Open Access Journals (Sweden)

    Heyun eZhang

    2015-09-01

    Full Text Available Previous studies on reducing employees’ cyberloafing behaviors have primarily examined the external control factors but seldomly taken individual internal subjective factors into consideration. Future orientation, an important individual factor, is defined as the extent to which one plans for future time and considers future consequences of one’s current behavior. To explore further whether and how employees’ future orientation can dampen their cyberloafing behaviors, two studies were conducted to examine the relationship between employees’ future orientation and cyberloafing behaviors. The mediation effect of employees’ objective and subjective self-control between them was also examined. In Study 1, a set of questionnaires was completed, and the results revealed that the relationship between employees’ future orientation and cyberloafing behaviors was negative, and objective self-control mediated the relationship. Next, we conducted a priming experiment (Study 2 to examine the causal relationship and psychological mechanism between employees’ future orientation and cyberloafing behaviors. The results demonstrated that employees’ future-orientation dampened their attitudes and intentions to engage in cyberloafing, and subjective self-control mediated this dampening effect. Theoretical and practical implications of these findings are also discussed.

  11. Amplification and dampening of soil respiration by changes in temperature variability

    Directory of Open Access Journals (Sweden)

    C. A. Sierra

    2011-04-01

    Full Text Available Accelerated release of carbon from soils is one of the most important feedbacks related to anthropogenically induced climate change. Studies addressing the mechanisms for soil carbon release through organic matter decomposition have focused on the effect of changes in the average temperature, with little attention to changes in temperature variability. Anthropogenic activities are likely to modify both the average state and the variability of the climatic system; therefore, the effects of future warming on decomposition should not only focus on trends in the average temperature, but also variability expressed as a change of the probability distribution of temperature. Using analytical and numerical analyses we tested common relationships between temperature and respiration and found that the variability of temperature plays an important role determining respiration rates of soil organic matter. Changes in temperature variability, without changes in the average temperature, can affect the amount of carbon released through respiration over the long-term. Furthermore, simultaneous changes in the average and variance of temperature can either amplify or dampen the release of carbon through soil respiration as climate regimes change. These effects depend on the degree of convexity of the relationship between temperature and respiration and the magnitude of the change in temperature variance. A potential consequence of this effect of variability would be higher respiration in regions where both the mean and variance of temperature are expected to increase, such as in some low latitude regions; and lower amounts of respiration where the average temperature is expected to increase and the variance to decrease, such as in northern high latitudes.

  12. Dietary modification dampens liver inflammation and fibrosis in obesity-related fatty liver disease.

    Science.gov (United States)

    Larter, Claire Z; Yeh, Matthew M; Haigh, W Geoffrey; Van Rooyen, Derrick M; Brooling, John; Heydet, Deborah; Nolan, Christophe