WorldWideScience

Sample records for adenosine monophosphate-activated protein

  1. Protective effects of inhibition of adenosine monophosphate activated protein kinase activity against cerebral ischemia-reperfusion injury in mice

    补娟

    2013-01-01

    Objective To observe the effect of inhibition of adenosine monophosphate activated protein kinase (AMPK) on shape,function and inflammatory factor of microglia for mice after cerebral ischemia-reperfusion

  2. Metabolic syndrome: adenosine monophosphate-activated protein kinase and malonyl coenzyme A.

    Ruderman, Neil B; Saha, Asish K

    2006-02-01

    The metabolic syndrome can be defined as a state of metabolic dysregulation characterized by insulin resistance, central obesity, and a predisposition to type 2 diabetes, dyslipidemia, premature atherosclerosis, and other diseases. An increasing body of evidence has linked the metabolic syndrome to abnormalities in lipid metabolism that ultimately lead to cellular dysfunction. We review here the hypothesis that, in many instances, the cause of these lipid abnormalities could be a dysregulation of the adenosine monophosphate-activated protein kinase (AMPK)/malonyl coenzyme A (CoA) fuel-sensing and signaling mechanism. Such dysregulation could be reflected by isolated increases in malonyl CoA or by concurrent changes in malonyl CoA and AMPK, both of which would alter intracellular fatty acid partitioning. The possibility is also raised that pharmacological agents and other factors that activate AMPK and/or decrease malonyl CoA could be therapeutic targets.

  3. Effects of adenosine 5’monophosphate-activated protein kinase on europrotection induced by ischemic preconditioning

    Yuan-ru-hua TIAN

    2015-06-01

    Full Text Available Objective To investigate the effects of adenosine 5'-monophosphate-activated protein kinase (AMPK and phosphated AMPK (pAMPK signals in ischemic preconditioning (IPC, and the effect of pharmacological intervention of AMPK on infarct size of the brain. Methods A brief (3min middle cerebral artery occlusion (MCAO was employed to induce IPC in male rat, and another 90-min MCAO was performed 4 or 72h later. The levels of AMPK and pAMPK were assessed after IPC. A pharmacological activator metformin, or inhibitor compound C of AMPK, was used to analyze the correlation of IPC to AMPK signaling in MCAO rats. Results The infarct size of total cerebral hemisphere and cortex was significantly decreased in MCAO animals by IPC for 72h (P0.05, n=6. The AMPK activator metformin can significantly reverse the protective effect of IPC (P<0.05, n=6. Conclusions The signals of AMPK and pAMPK play an important role in neuroprotective effect of IPC on cerebral ischemic injury. The neuroprotective effect of IPC may be associated with the down-regulation of pAMPK. DOI: 10.11855/j.issn.0577-7402.2015.05.07

  4. 5'-adenosine monophosphate-activated protein kinase and the metabolic syndrome.

    Mor, Vijay; Unnikrishnan, M K

    2011-09-01

    Lifestyle changes such as physical inactivity combined with calorie-rich, low-fibre diets have triggered an explosive surge in metabolic syndrome, outlined as a cluster of heart attack risk factors such as insulin resistance, raised fasting plasma glucose, abdominal obesity, high cholesterol and high blood pressure. By acting as a master-switch of energy homeostasis and associated pathophysiological phenomena, 5'-adenosine monophosphate-activated protein kinase (AMPK) appears to orchestrate the adaptive physiology of energy deficit, suggesting that the sedentary modern human could be suffering from chronic suboptimal AMPK activation. Addressing individual targets with potent ligands with high specificity may be inappropriate (it has not yielded any molecule superior to the sixty year old metformin) because this strategy cannot address a cluster of interrelated pathologies. However, spices, dietary supplements and nutraceuticals attenuate the multiple symptoms of metabolic syndrome in a collective and perhaps more holistic fashion with fewer adverse events. Natural selection could have favoured races that developed a taste for spices and dietary supplements, most of which are not only antioxidants but also activators of AMPK. The review will outline the various biochemical mechanisms and pathophysiological consequences of AMPK activation involving the cluster of symptoms that embrace metabolic syndrome and beyond. Recent advances that integrate energy homeostasis with a number of overarching metabolic pathways and physiological phenomena, including inflammatory conditions, cell growth and development, malignancy, life span, and even extending into environmental millieu, as in obesity mediated by gut microflora and others will also be outlined.

  5. Xylazine Activates Adenosine Monophosphate-Activated Protein Kinase Pathway in the Central Nervous System of Rats

    Shi, Xing-Xing; Yin, Bai-Shuang; Yang, Peng; Chen, Hao; Li, Xin; Su, Li-Xue; Fan, Hong-Gang; Wang, Hong-Bin

    2016-01-01

    Xylazine is a potent analgesic extensively used in veterinary and animal experimentation. Evidence exists that the analgesic effect can be inhibited using adenosine 5’-monophosphate activated protein kinase (AMPK) inhibitors. Considering this idea, the aim of this study was to investigate whether the AMPK signaling pathway is involved in the central analgesic mechanism of xylazine in the rat. Xylazine was administrated via the intraperitoneal route. Sprague-Dawley rats were sacrificed and the cerebral cortex, cerebellum, hippocampus, thalamus and brainstem were collected for determination of liver kinase B1 (LKB1) and AMPKα mRNA expression using quantitative real-time polymerase chain reaction (qPCR), and phosphorylated LKB1 and AMPKα levels using western blot. The results of our study showed that compared with the control group, xylazine induced significant increases in AMPK activity in the cerebral cortex, hippocampus, thalamus and cerebellum after rats received xylazine (P < 0.01). Increased AMPK activities were accompanied with increased phosphorylation levels of LKB1 in corresponding regions of rats. The protein levels of phosphorylated LKB1 and AMPKα in these regions returned or tended to return to control group levels. However, in the brainstem, phosphorylated LKB1 and AMPKα protein levels were decreased by xylazine compared with the control (P < 0.05). In conclusion, our data indicates that xylazine alters the activities of LKB1 and AMPK in the central nervous system of rats, which suggests that xylazine affects the regulatory signaling pathway of the analgesic mechanism in the rat brain. PMID:27049320

  6. Beneficial effects of metformin on primary cardiomyocytes via activation of adenosine monophosphate-activated protein kinase

    WANG Xiao-fang; ZHANG Jin-ying; LI Ling; ZHAO Xiao-yan

    2011-01-01

    Background Metformin has become a cornerstone in the treatment of patients with type-2 diabetes. Accumulated evidence suggests that metformin supports direct cardiovascular effects. The present study aimed to investigate if metformin has beneficial effects on primary cardiomyocytes damaged by H2O2, and reveal the potential mechanism of action of metformin.Methods Cardiomyocytes were incubated in the presence of 100 umol/L. H2O2 for 12 hours. Cardiomyocytes were pretreated with metformin at different concentrations and time and with aminoimidazole carboxamide ribonucleotide (AICAR) (500 umol/L), an adenosine monophophate (AMP)-activated protein kinase (AMPK) agonist for 60 minutes before the addition of H2O2. Other cells were preincubated with compound C (an AMPK antagonist, 20 umol/L) for 4 hours. The viability and apoptosis of cells were analyzed. AMPK, endothelial nitric oxide synthase (eNOS), and transforming growth factor (TGF)-β1 were analyzed using immunblotting.Results Metformin had antagonistic effects on the influences of H2O2 on cell viability and attenuated oxidative stress-induced apoptosis. Metformin also increased phosphorylation of AMPK and eNOS, and reduced the expression of TGF-β1, basic fibroblast growth factor (bFGF), and tumor necrosis factor (TNF)-α.Conclusions Metformin has beneficial effects on cardiomyocytes, and this effect involves activation of the AMPK-eNOS pathway. Metformin may be potentially beneficial for the treatment of heart disease.

  7. Adenosine monophosphate-activated protein kinase activation and suppression of inflammatory response by cell stretching in rabbit synovial fibroblasts.

    Kunanusornchai, Wanlop; Muanprasat, Chatchai; Chatsudthipong, Varanuj

    2016-12-01

    Joint mobilization is known to be beneficial in osteoarthritis (OA) patients. This study aimed to investigate the effect of stretching on adenosine monophosphate-activated protein kinase (AMPK) activity and its role in modulating inflammation in rabbit synovial fibroblasts. Uniaxial stretching of isolated rabbit synovial fibroblasts for ten min was performed. Stretching-induced AMPK activation, its underlying mechanism, and its anti-inflammatory effect were investigated using Western blot. Static stretching at 20 % of initial length resulted in AMPK activation characterized by expression of phosphorylated AMPK and phosphorylated acetyl-Co A carboxylase. AMP-activated protein kinase phosphorylation peaked 1 h after stretching and declined toward resting activity. Using cell viability assays, static stretching did not appear to cause cellular damage. Activation of AMPK involves Ca(2+) influx via a mechanosensitive L-type Ca(2+) channel, which subsequently raises intracellular Ca(2+) and activates AMPK via Ca(2+)/calmodulin-dependent protein kinase kinase β (CaMKKβ). Interestingly, stretching suppressed TNFα-induced expression of COX-2, iNOS, and phosphorylated NF-κB. These effects were prevented by pretreatment with compound C, an AMPK inhibitor. These results suggest that mechanical stretching suppressed inflammatory responses in synovial fibroblasts via a L-type Ca(2+)-channel-CaMKKβ-AMPK-dependent pathway which may underlie joint mobilization's ability to alleviate OA symptoms.

  8. Methylene blue induces macroautophagy through 5' adenosine monophosphate-activated protein kinase pathway to protect neurons from serum deprivation.

    Xie, Luokun; Li, Wenjun; Winters, Ali; Yuan, Fang; Jin, Kunlin; Yang, Shaohua

    2013-01-01

    Methylene blue has been shown to be neuroprotective in multiple experimental neurodegenerative disease models. However, the mechanisms underlying the neuroprotective effects have not been fully elucidated. Previous studies have shown that macroautophagy has multiple beneficial roles for maintaining normal cellular homeostasis and that induction of macroautophagy after myocardial ischemia is protective. In the present study we demonstrated that methylene blue could protect HT22 hippocampal cell death induced by serum deprivation, companied by induction of macroautophagy. We also found that methylene blue-mediated neuroprotection was abolished by macroautophagy inhibition. Interestingly, 5' adenosine monophosphate-activated protein kinase (AMPK) signaling, but not inhibition of mammalian target of rapamycin signaling, was activated at 12 and 24 h after methylene blue treatment in a dose-dependent manner. Methylene blue-induced macroautophagy was blocked by AMPK inhibitor. Consistent with in vitro data, macroautophagy was induced in the cortex and hippocampus of mouse brains treated with methylene blue. Our findings suggest that methylene blue-induced neuroprotection is mediated, at least in part, by macroautophagy though activation of AMPK signaling.

  9. Cows are not mice: the role of cyclic AMP, phosphodiesterases, and adenosine monophosphate-activated protein kinase in the maintenance of meiotic arrest in bovine oocytes.

    Bilodeau-Goeseels, Sylvie

    2011-01-01

    Meiotic maturation in mammalian oocytes is initiated during fetal development, and is then arrested at the dictyate stage - possibly for several years. Oocyte meiosis resumes in preovulatory follicles in response to the lutenizing hormone (LH) surge or spontaneously when competent oocytes are removed from follicles and cultured. The mechanisms involved in meiotic arrest and resumption in bovine oocytes are not fully understood, and several studies point to important differences between oocytes from rodent and livestock species. This paper reviews earlier and contemporary studies on the effects of cAMP-elevating agents and phosphodiesterase (PDE) enzyme inhibitors on the maintenance of meiotic arrest in bovine oocytes in vitro. Contrary to results obtained with mouse oocytes, bovine oocyte meiosis is inhibited by activators of the energy sensor adenosine monophosphate-activated protein kinase (AMPK, mammalian gene PRKA), which is activated by AMP, the degradation product of cAMP. It is not clear whether or not the effects were due to AMPK activation, and they may depend on culture conditions. Evidence suggests that other signaling pathways (for example, the cGMP/nitric oxide pathway) are involved in bovine oocyte meiotic arrest, but further studies are needed to understand the interactions between the signaling pathways that lead to maturation promoting factor (MPF) being inactive or active. An improved understanding of the mechanisms involved in the control of bovine oocyte meiosis will facilitate better control of the process in vitro, resulting in increased developmental competence and increased efficiency of in vitro embryo production procedures.

  10. Involvement of adenosine monophosphate-activated protein kinase in the influence of timed high-fat evening diet on the hepatic clock and lipogenic gene expression in mice.

    Huang, Yan; Zhu, Zengyan; Xie, Meilin; Xue, Jie

    2015-09-01

    A high-fat diet may result in changes in hepatic clock gene expression, but potential mechanisms are not yet elucidated. Adenosine monophosphate-activated protein kinase (AMPK) is a serine/threonine protein kinase that is recognized as a key regulator of energy metabolism and certain clock genes. Therefore, we hypothesized that AMPK may be involved in the alteration of hepatic clock gene expression under a high-fat environment. This study aimed to examine the effects of timed high-fat evening diet on the activity of hepatic AMPK, clock genes, and lipogenic genes. Mice with hyperlipidemic fatty livers were induced by orally administering high-fat milk via gavage every evening (19:00-20:00) for 6 weeks. Results showed that timed high-fat diet in the evening not only decreased the hepatic AMPK protein expression and activity but also disturbed its circadian rhythm. Accordingly, the hepatic clock genes, including clock, brain-muscle-Arnt-like 1, cryptochrome 2, and period 2, exhibited prominent changes in their expression rhythms and/or amplitudes. The diurnal rhythms of the messenger RNA expression of peroxisome proliferator-activated receptorα, acetyl-CoA carboxylase 1α, and carnitine palmitoyltransferase 1 were also disrupted; the amplitude of peroxisome proliferator-activated receptorγcoactivator 1α was significantly decreased at 3 time points, and fatty liver was observed. These findings demonstrate that timed high-fat diet at night can change hepatic AMPK protein levels, activity, and circadian rhythm, which may subsequently alter the circadian expression of several hepatic clock genes and finally result in the disorder of hepatic lipogenic gene expression and the formation of fatty liver.

  11. Adenosine monophosphate-activated protein kinase activation enhances embryonic neural stem cell apoptosis in a mouse model of amyotrophic lateral sclerosis

    Yanling Sui; Zichun Zhao; Rong Liu; Bin Cai; Dongsheng Fan

    2014-01-01

    Alterations in embryonic neural stem cells play crucial roles in the pathogenesis of amyotrophic lateral sclerosis. We hypothesized that embryonic neural stem cells from SOD1G93A individuals might be more susceptible to oxidative injury, resulting in a propensity for neurodegeneration at later stages. In this study, embryonic neural stem cells obtained from human superoxide dis-mutase 1 mutant (SOD1G93A) and wild-type (SOD1WT) mouse models were exposed to H2O2. We assayed cell viability with mitochondrial succinic dehydrogenase colorimetric reagent, and measured cell apoptosis by lfow cytometry. Moreover, we evaluated the expression of the adenos-ine monophosphate-activated protein kinase (AMPK)α-subunit, paired box 3 (Pax3) protein, and p53 in western blot analyses. Compared with SOD1WT cells, SOD1G93A embryonic neural stem cells were more likely to undergo H2O2-induced apoptosis. Phosphorylation of AMPKαin SOD1G93A cells was higher than that in SOD1WT cells. Pax3 expression was inversely correlated with the phosphorylation levels of AMPKα. p53 protein levels were also correlated with AMPKαphosphorylation levels. Compound C, an inhibitor of AMPKα, attenuated the effects of H2O2. These results suggest that embryonic neural stem cells from SOD1G93A mice are more susceptible to apoptosis in the presence of oxidative stress compared with those from wild-type controls, and the effects are mainly mediated by Pax3 and p53 in the AMPKα pathway.

  12. Role of adenosine 5'-monophosphate-activated protein kinase subunits in skeletal muscle mammalian target of rapamycin signaling

    Deshmukh, Atul S.; Treebak, Jonas Thue; Long, Yun Chau

    2008-01-01

    AMP-activated protein kinase (AMPK) is an important energy-sensing protein in skeletal muscle. Mammalian target of rapamycin (mTOR) mediates translation initiation and protein synthesis through ribosomal S6 kinase 1 (S6K1) and eukaryotic initiation factor 4E-binding protein 1 (4E-BP1). AMPK...... activation reduces muscle protein synthesis by down-regulating mTOR signaling, whereas insulin mediates mTOR signaling via Akt activation. We hypothesized that AMPK-mediated inhibitory effects on mTOR signaling depend on catalytic alpha2 and regulatory gamma3 subunits. Extensor digitorum longus muscle from...... in extensor digitorum longus muscle from either alpha2 or gamma3 AMPK KO mice, indicating functional alpha2 and gamma3 subunits of AMPK are required for the reduction in mTOR signaling. AICAR alone was without effect on basal phosphorylation of S6K1 (Thr389), ribosomal protein S6 (Ser235/236), and 4E-BP1 (Thr...

  13. A high isoflavone diet decreases 5' adenosine monophosphate-activated protein kinase activation and does not correct selenium-induced elevations in fasting blood glucose in mice.

    Stallings, Michael T; Cardon, Brandon R; Hardman, Jeremy M; Bliss, Tyler A; Brunson, Scott E; Hart, Chris M; Swiss, Maria D; Hepworth, Squire D; Christensen, Merrill J; Hancock, Chad R

    2014-04-01

    Selenium (Se) has been implicated as a micronutrient that decreases adenosine monophosphate-activated protein kinase (AMPK) signaling and may increase diabetes risk by reducing insulin sensitivity. Soy isoflavones (IF) are estrogen-like compounds that have been shown to attenuate insulin resistance, hyperglycemia, adiposity, and increased AMPK activation. We hypothesized that a high IF (HIF) diet would prevent the poor metabolic profile associated with high Se intake. The purpose of this study was to examine changes in basal glucose metabolism and AMPK signaling in response to an HIF diet and/or supplemental Se in a mouse model. Male FVB mice were divided into groups receiving either a control diet with minimal IF (low IF) or an HIF diet. Each dietary group was further subdivided into groups receiving either water or Se at a dose of 3 mg Se/kg body weight daily, as Se-methylselenocysteine (SMSC). After 5 months, mice receiving SMSC had elevated fasting glucose (P < .05) and a tendency for glucose intolerance (P = .08). The increase in dietary IF did not result in improved fasting blood glucose. Interestingly, after 6 months, HIF-fed mice had decreased basal AMPK activation in liver and skeletal muscle tissue (P < .05). Basal glucose metabolism was changed by SMSC supplementation as evidenced by increased fasting blood glucose and glucose intolerance. High dietary IF levels did not protect against aberrant blood glucose. In FVB mice, decreased basal AMPK activation is not the mechanism through which Se exerts its effect. These results suggest that more research must be done to elucidate the role of Se and IF in glucose metabolism.

  14. Adenosine monophosphate-activated protein kinase from the mud crab, Scylla paramamosain: cDNA cloning and profiles under cold stress

    CHENCUI HUANG; KUN YU; HUIYANG HUANG; HAIHUI YE

    2016-12-01

    Adenosine monophosphate-activated protein kinase (AMPK), an important energy sensor, is crucial for organism survival under adverse conditions. In this study, the roles of this gene under cold stress in a warm-water mud crab, Scylla paramamosain was investigated. The full-length cDNA (SpAMPK) was 1884 bp and its open reading frame of 1566 bp was isolated and characterized. The expressions of SpAMPK detected by quantitative real-time PCR (qRT-PCR) in various tissues revealed that the highest expression was in the hepatopancreas. The profiles of SpAMPK gene in the hepatopancreas, chela muscleand gill were detected when the subadult crabs were exposed to the four temperature conditions of 10, 15, 20 and 25◦C. The results showed that the expression patterns of SpAMPK mRNA in the three tissues were significantly higher when crabs were exposed to 15◦C than the other three temperature treatments, while at 10◦C treatment, the SpAMPK mRNA was lowestamong the four temperature treatments. These findings suggested that the high expression of SpAMPK mRNA might initiate ATP-producing pathways to generate energy to cope with cold stress at 15◦C treatment, which was slightly below the range of optimum temperatures; while treatment at 10◦C, far lower than optima, the low expression of SpAMPK mRNA could reduce the energy expenditure and thus induce the crabs into cold anesthesia. The results of SpAMPK in this study might contribute to the understanding of the molecular mechanism of acclimation to cold hardiness in S. paramamosain.

  15. Role of adenosine 5'-monophosphate-activated protein kinase in interleukin-6 release from isolated mouse skeletal muscle

    Glund, Stephan; Treebak, Jonas Thue; Long, Yun Chau;

    2009-01-01

    IL-6 is released from skeletal muscle during exercise and has consequently been implicated to mediate beneficial effects on whole-body metabolism. Using 5-aminoimidazole-4-carboxamide-1-beta-4-ribofuranoside (AICAR), a pharmacological activator of 5'-AMP-activated protein kinase (AMPK), we tested...... the hypothesis that AMPK modulates IL-6 release from isolated muscle. Skeletal muscle from AMPKalpha2 kinase-dead transgenic, AMPKalpha1 knockout (KO) and AMPKgamma3 KO mice and respective wild-type littermates was incubated in vitro, in the absence or presence of 2 mmol/liter AICAR. Skeletal muscle from wild......-type mice was also incubated with the AMPK activator A-769662. Incubation of mouse glycolytic extensor digitorum longus and oxidative soleus muscle for 2 h was associated with profound IL-6 mRNA production and protein release, which was suppressed by AICAR (P

  16. Ablation of adenosine monophosphate-activated protein kinaseα1 in vascular smooth muscle cells promotes diet-induced atherosclerotic calcification in vivo

    CAI Zhe-jun; DING Ye; ZHANG Miao; LU Qiu-lun; WU Sheng-nan; ZHU Huai-ping; SONG Ping; ZOU Ming-hui

    2016-01-01

    AIM:Atherosclerotic calcification is highly linked with plaque instability and cardiovascular events .Adenosine monophosphate-activated protein kinase ( AMPK) has been involved in the pathogenesis of various cardiovascular disease .The contributions of AMPKαsubunits to the development of atherosclerotic calcification in vivo remained unknown .We hypothesized that AMPKαsubunits may play a role in the development of atherosclerotic calcification .METHODS: Atherosclerotic calcification was generated by 24-week fed of western diet in ApoE-/-background mice .Calcification was evaluated in aortic roots and innominate arteries of ApoE-/-mice or in mice with dual deficiencies of ApoE and AMPKαsubunits globally ( AMPKα1 and AMPKα2 ) , or vascular smooth muscle cell ( VSMC)-specific or macrophage-specific knockout of AMPKα1 with atherosclerotic calcification pone diet . The mechanism of AMPKα1 in regulating Runx2 was further explored in human aortic VSMC .RESULTS: Ablation of AMPKα1 but not AMPKα2 in ApoE-/-background promoted atherosclerotic calcification with increased Runt -related transcription factor ( Runx2 ) expression in VSMC compared with ApoE-/-mice.Conversely, chronic administration of metformin, which activated AMPK, markedly reduced ath-erosclerotic calcification and Runx2 expression in ApoE-/-mice but had less effects in ApoE-/-/AMPKα1 -/-mice.Furthermore, VSMC-but not macrophage-specific deficiency of AMPKα1 in ApoE-/-background promoted atherosclerotic calcification in vivo com-pared with the controls .AMPKα1 silencing in human aortic VSMC prevented Runx 2 from proteasome degradation to trigger osteoblastic differentiation of VSMC .Conversely , activation of AMPK led to Runx 2 instability by inducing its small ubiquitin-like modifier modifi-cation (SUMOylation).Protein inhibitor of activated STAT-1 (PIAS1), the SUMO E3-ligase of Runx2, was directly phosphorylated by AMPKα1 at serine 510, to enhance its SUMO E3-ligase activity.Ablation of PIAS1

  17. Expression of adenosine 5'-monophosphate-Activated protein kinase (AMPK) in ovine testis (Ovis aries): In vivo regulation by nutritional state.

    Taibi, N; Dupont, J; Bouguermouh, Z; Froment, P; Ramé, C; Anane, A; Amirat, Z; Khammar, F

    2017-03-01

    In the present study, we identified AMPK and investigated its potential role in steroidogenesis in vivo in the ovine testis in response to variation in nutritional status (fed control vs. restricted). We performed immunoblotting to show that both active and non-active forms of AMPK exist in ovine testis and liver. In testis, we confirmed these results by immunohistochemistry. We found a correlation between ATP (Adenosine-Triphosphate) levels and the expression of AMPK in liver. Also, low and high caloric diets induce isoform-dependent AMPK expression, with an increase in α2, ß1ß2 and γ1 activity levels. Although the restricted group exhibited an increase in lipid balance, only the triglyceride and HC-VLDL (Cholesterol-Very low density lipoprotein) fractions showed significant differences between groups, suggesting an adaptive mechanism. Moreover, the relatively low rate of non-esterified fatty acid released into the circulation implies re-esterification to compensate for the physiological need. In the fed control group, AMPK activates the production of testosterone in Leydig cells; this is, in turn, associated with an increase in the expression of 3ß-HSD (3 beta hydroxy steroid deshydrogenase), p450scc (Cholesterol side-chain cleavage enzyme) and StAR (Steroidogenic acute regulatory protein) proteins induced by decreased MAPK ERK½ (Extracellular signal-regulated kinase -Mitogen-activated protein kinase) phosphorylation. In contrast, in the restricted group, testosterone secretion was reduced but intracellular cholesterol concentration was not. Furthermore, the combination of high levels of lipoproteins and emergence of the p38 MAP kinase pathway suggest the involvement of pro-inflammatory cytokines, as confirmed by transcriptional repression of the StAR protein. Taken together, these results suggest that AMPK expression is tissue dependent.

  18. Globular adiponectin protects human umbilical vein endothelial cells against apoptosis through adiponectin receptor 1/adenosine monophosphate-activated protein kinase pathway

    ZHAO Hong-yu; ZHAO Min; YI Tong-ning; ZHANG Jin

    2011-01-01

    Background Endothelial dysfunction is a key event in the onset and progression of atherosclerosis in diabetic patients.Apoptosis may lead to endothelial dysfunction and contribute to vascular complications. However, no study has addressed apoptosis in human umbilical vein endothelial cells (HUVECs) induced by an intermittent high-glucose media and its association with adiponectin receptor 1 (adipoR1), adipoR2, or adenosine monophosphate (AMP)-activated protein kinase (AMPK).Methods HUVECs were cultured in continuous normal glucose (5.5 mmol/L), continuous high glucose (25 mmol/L),alternating normal and high glucose and mannitol. In the alternating normal and high-glucose media, HUVECs were treated under different conditions. First, cells were transfected with the adipoR1-specific small-interfering RNA (siRNA)and then stimulated with globular adiponectin (gAD). Second, cells were cultured in both gAD and the AMPK activator 5-aminoimidazole-4-carboxamide-1-β-D-ribofuranoside (AICAR). Third, cells were cultured in the AMPK inhibitor adenine-9-β-D-arabino-furanoside (araA), gAD, and in AICAR.Results HUVEC apoptosis increased more significantly in an intermittent high-glucose medium than in a constant high-glucose medium. HUVEC apoptosis induced by an intermittent high-glucose medium was inhibited when the cells were pretreated with 3 μg/ml gAD, which rapidly activated AMPK and adipoR1 in HUVECs. However, adipoR2 was not activated.Conclusions We found that adipoR1, not adipoR2, is involved in mediating intermittent high-concentration glucoseevoked apoptosis in endothelial cells. gAD activated AMPK through adipoR1, leads to the partial inhibition of HUVEC apoptosis. A fluctuating glucose medium is more harmful than a constant high-glucose medium to endothelial cells.

  19. Adenosine Monophosphate-Activated Protein Kinase Abates Hyperglycaemia-Induced Neuronal Injury in Experimental Models of Diabetic Neuropathy: Effects on Mitochondrial Biogenesis, Autophagy and Neuroinflammation.

    Yerra, Veera Ganesh; Kumar, Ashutosh

    2017-04-01

    Impaired adenosine monophosphate kinase (AMPK) signalling under hyperglycaemic conditions is known to cause mitochondrial dysfunction in diabetic sensory neurons. Facilitation of AMPK signalling is previously reported to ameliorate inflammation and induce autophagic response in various complications related to diabetes. The present study assesses the role of AMPK activation on mitochondrial biogenesis, autophagy and neuroinflammation in experimental diabetic neuropathy (DN) using an AMPK activator (A769662). A769662 (15 and 30 mg/kg, i.p) was administered to Sprague-Dawley rats (250-270 g) for 2 weeks after 6 weeks of streptozotocin (STZ) injection (55 mg/kg, i.p.). Behavioural parameters (mechanical/thermal hyperalgesia) and functional characteristics (motor/sensory nerve conduction velocities (MNCV and SNCV) and sciatic nerve blood flow (NBF)) were assessed. For in vitro studies, Neuro2a (N2A) cells were incubated with 25 mM glucose to simulate high glucose condition and then studied for mitochondrial dysfunction and protein expression changes. STZ administration resulted in significant hyperglycaemia (>250 mg/dl) in rats. A769662 treatment significantly improved mechanical/thermal hyperalgesia threshold and enhanced MNCV, SNCV and NBF in diabetic animals. A769662 exposure normalised the mitochondrial superoxide production, membrane depolarisation and markedly increased neurite outgrowth of N2A cells. Further, AMPK activation also abolished the NF-κB-mediated neuroinflammation. A769662 treatment increased Thr-172 phosphorylation of AMPK results in stimulated PGC-1α-directed mitochondrial biogenesis and autophagy induction. Our study supports that compromised AMPK signalling in hyperglycaemic conditions causes defective mitochondrial biogenesis ultimately leading to neuronal dysfunction and associated deficits in DN and activation of AMPK can be developed as an attractive therapeutic strategy for the management of DN.

  20. Post-Meal Responses of Elongation Factor 2 (eEF2 and Adenosine Monophosphate-Activated Protein Kinase (AMPK to Leucine and Carbohydrate Supplements for Regulating Protein Synthesis Duration and Energy Homeostasis in Rat Skeletal Muscle

    Donald K. Layman

    2012-11-01

    Full Text Available Previous research demonstrates that the anabolic response of muscle protein synthesis (MPS to a meal is regulated at the level of translation initiation with signals derived from leucine (Leu and insulin to activate mTORC1 signaling. Recent evidence suggests that the duration of the meal response is limited by energy status of the cell and inhibition of translation elongation factor 2 (eEF2. This study evaluates the potential to extend the anabolic meal response with post-meal supplements of Leu or carbohydrates. Adult (~256 g male Sprague-Dawley rats were food deprived for 12 h, then either euthanized before a standard meal (time 0 or at 90 or 180 min post-meal. At 135 min post-meal, rats received one of five oral supplements: 270 mg leucine (Leu270, 80:40:40 mg leucine, isoleucine, and valine (Leu80, 2.63 g carbohydrates (CHO2.6, 1 g carbohydrates (CHO1.0, or water (Sham control. Following the standard meal, MPS increased at 90 min then declined to pre-meal baseline at 180 min. Rats administered Leu270, Leu80, CHO2.6, or CHO1.0 maintained elevated rates of MPS at 180 min, while Sham controls declined from peak values. Leu80 and CHO1.0 treatments maintained MPS, but with values intermediate between Sham controls and Leu270 and CHO2.6 supplements. Consistent with MPS findings, the supplements maintained elongation activity and cellular energy status by preventing increases in AMP/ATP and phosphorylation of adenosine monophosphate-activated protein kinase (AMPK, acetyl-CoA carboxylase ACC and eEF2. The impact of the supplements on MPS and cellular energy status was in proportion to the energy content within the individual treatments (i.e., Leu270 > Leu80; CHO2.6 > CHO1.0, but the Leu supplements produced a disproportionate anabolic stimulation of MPS, eEF2 and energy status with significantly lower energy content. In summary, the incongruity between MPS and translation initiation at 180 min reflects a block in translation elongation due to

  1. Post-meal responses of elongation factor 2 (eEF2) and adenosine monophosphate-activated protein kinase (AMPK) to leucine and carbohydrate supplements for regulating protein synthesis duration and energy homeostasis in rat skeletal muscle.

    Wilson, Gabriel J; Moulton, Christopher J; Garlick, Peter J; Anthony, Tracy G; Layman, Donald K

    2012-11-13

    Previous research demonstrates that the anabolic response of muscle protein synthesis (MPS) to a meal is regulated at the level of translation initiation with signals derived from leucine (Leu) and insulin to activate mTORC1 signaling. Recent evidence suggests that the duration of the meal response is limited by energy status of the cell and inhibition of translation elongation factor 2 (eEF2). This study evaluates the potential to extend the anabolic meal response with post-meal supplements of Leu or carbohydrates. Adult (~256 g) male Sprague-Dawley rats were food deprived for 12 h, then either euthanized before a standard meal (time 0) or at 90 or 180 min post-meal. At 135 min post-meal, rats received one of five oral supplements: 270 mg leucine (Leu270), 80:40:40 mg leucine, isoleucine, and valine (Leu80), 2.63 g carbohydrates (CHO2.6), 1 g carbohydrates (CHO1.0), or water (Sham control). Following the standard meal, MPS increased at 90 min then declined to pre-meal baseline at 180 min. Rats administered Leu270, Leu80, CHO2.6, or CHO1.0 maintained elevated rates of MPS at 180 min, while Sham controls declined from peak values. Leu80 and CHO1.0 treatments maintained MPS, but with values intermediate between Sham controls and Leu270 and CHO2.6 supplements. Consistent with MPS findings, the supplements maintained elongation activity and cellular energy status by preventing increases in AMP/ATP and phosphorylation of adenosine monophosphate-activated protein kinase (AMPK), acetyl-CoA carboxylase ACC and eEF2. The impact of the supplements on MPS and cellular energy status was in proportion to the energy content within the individual treatments (i.e., Leu270 > Leu80; CHO2.6 > CHO1.0), but the Leu supplements produced a disproportionate anabolic stimulation of MPS, eEF2 and energy status with significantly lower energy content. In summary, the incongruity between MPS and translation initiation at 180 min reflects a block in translation elongation due to reduced

  2. Berberine treatment prevents cardiac dysfunction and remodeling through activation of 5'-adenosine monophosphate-activated protein kinase in type 2 diabetic rats and in palmitate-induced hypertrophic H9c2 cells.

    Chang, Wenguang; Zhang, Ming; Meng, Zhaojie; Yu, Yang; Yao, Fan; Hatch, Grant M; Chen, Li

    2015-12-15

    Diabetic cardiomyopathy is the major cause of death in type 2 diabetic patients. Berberine is an isoquinoline alkaloid extract from traditional chinese herbs and its hypoglycemic and hypolipidemic effects make it a promising drug for treatment of type 2 diabetes. We examined if berberine improved cardiac function and attenuated cardiac hypertrophy and fibrosis in high fat diet and streptozotocin induced-type 2 diabetic rats in vivo and reduced expression of hypertrophy markers in palmitate-induced hypertrophic H9c2 cells in vitro. Treatment of diabetic animals with berberine partially improved cardiac function and restored fasting blood insulin, fasting blood glucose, total cholesterol, and triglyceride levels to that of control. In addition, berberine treatment of diabetic animals increased cardiac 5'-adenosine monophosphate-activated protein kinase (AMPK) and protein kinase B (AKT) activation and reduced glycogen synthase kinase 3 beta (GSK3β) activation compared to control. Palmitate incubation of H9c2 cells resulted in cellular hypertrophy and decreased expression of alpha-myosin heavy chain (α-MHC) and increased expression of beta-myosin heavy chain (β-MHC) compared to controls. Berberine treatment of palmitate-incubated H9c2 cells reduced hypertrophy, increased α-MHC expression and decreased β-MHC expression. In addition, berberine treatment of palmitate-incubated H9c2 cells increased AMPK and AKT activation and reduced GSK3β activation. The presence of the AMPK inhibitor Compound C attenuated the effects of berberine. The results strongly indicate that berberine treatment may be protective against the development of diabetic cardiomyopathy.

  3. Discovery and Preclinical Characterization of 6-Chloro-5-[4-(1-hydroxycyclobutyl)phenyl]-1H-indole-3-carboxylic Acid (PF-06409577), a Direct Activator of Adenosine Monophosphate-activated Protein Kinase (AMPK), for the Potential Treatment of Diabetic Nephropathy.

    Cameron, Kimberly O; Kung, Daniel W; Kalgutkar, Amit S; Kurumbail, Ravi G; Miller, Russell; Salatto, Christopher T; Ward, Jessica; Withka, Jane M; Bhattacharya, Samit K; Boehm, Markus; Borzilleri, Kris A; Brown, Janice A; Calabrese, Matthew; Caspers, Nicole L; Cokorinos, Emily; Conn, Edward L; Dowling, Matthew S; Edmonds, David J; Eng, Heather; Fernando, Dilinie P; Frisbie, Richard; Hepworth, David; Landro, James; Mao, Yuxia; Rajamohan, Francis; Reyes, Allan R; Rose, Colin R; Ryder, Tim; Shavnya, Andre; Smith, Aaron C; Tu, Meihua; Wolford, Angela C; Xiao, Jun

    2016-09-08

    Adenosine monophosphate-activated protein kinase (AMPK) is a protein kinase involved in maintaining energy homeostasis within cells. On the basis of human genetic association data, AMPK activators were pursued for the treatment of diabetic nephropathy. Identification of an indazole amide high throughput screening (HTS) hit followed by truncation to its minimal pharmacophore provided an indazole acid lead compound. Optimization of the core and aryl appendage improved oral absorption and culminated in the identification of indole acid, PF-06409577 (7). Compound 7 was advanced to first-in-human trials for the treatment of diabetic nephropathy.

  4. Metformin inhibits nuclear factor-κB activation and inflammatory cytokines expression induced by high glucose via adenosine monophosphate-activated protein kinase activation in rat glomerular mesangial cells in vitro

    Gu Junfei; Ye Shandong; Wang Shan; Sun Wenjia; Hu Yuanyuan

    2014-01-01

    Background The renoprotective mechanisms of adenosine monophosphate (AMP)-activated protein kinase (AMPK) agonist-metformin have not been stated clearly.We hypothesized that metformin may ameliorate inflammation via AMPK interaction with critical inflammatory cytokines The aim of this study was to observe the effects of metformin on expression of nuclear factor-κB (NF-κB),monocyte chemoattractant protein-1 (MCP-1),intercellular adhesion molecule-1 (ICAM-1) and transforming growth factor-beta 1 (TGF-β1) induced by high glucose (HG) in cultured rat glomerular mesangial cells (MCs).Methods MCs were cultured in the medium with normal concentration glucose (group NG,5.6 mmol/L),high concentration glucose (group HG,25 mmol/L) and different concentrations of metformin (group M1,M2,M3).After 48-hour exposure,the supernatants and MCs were collected.The expression of NF-κB,MCP-1,ICAM-1,and TGF-β1 mRNA was analyzed by real time polymerase chain reaction.Westem blotting was used to detect the expression of AMPK,phospho-Thr-172 AMPK (p-AMPK),NF-κB p65,MCP-1,ICAM-1,and TGF-β1 protein.Results After stimulated by HG,the expression of NF-κB,MCP-1,ICAM-1,TGF-β1 mRNA and protein of MCs in group HG increased significantly compared with group NG (P <0.05).Both genes and protein expression of NF-κB,MCP-1,ICAM-1,TGF-β1 of MCs induced by high glucose were markedly reduced after metformin treatment in a dose-dependent manner (P <0.05).The expression of p-AMPK increased with the rising of metformin concentration,presenting the opposite trend,while the level of total-AMPK protein was unchanged with exposure to HG or metformin.Conlusion Metformin can suppress the expression of NF-κB,MCP-1,ICAM-1 and TGF-β1 of glomerular MCs induced by high glucose via AMPK activation,which may partlv contribute to its reno-protection.

  5. Tissue kallikrein reverses insulin resistance and attenuates nephropathy in diabetic rats by activation of phosphatidylinositol 3-kinase/protein kinase B and adenosine 5'-monophosphate-activated protein kinase signaling pathways.

    Yuan, Gang; Deng, Juanjuan; Wang, Tao; Zhao, Chunxia; Xu, Xizheng; Wang, Peihua; Voltz, James W; Edin, Matthew L; Xiao, Xiao; Chao, Lee; Chao, Julie; Zhang, Xin A; Zeldin, Darryl C; Wang, Dao Wen

    2007-05-01

    We previously reported that iv delivery of the human tissue kallikrein (HK) gene reduced blood pressure and plasma insulin levels in fructose-induced hypertensive rats with insulin resistance. In the current study, we evaluated the potential of a recombinant adeno-associated viral vector expressing the HK cDNA (rAAV-HK) as a sole, long-term therapy to correct insulin resistance and prevent renal damage in streptozotocin-induced type-2 diabetic rats. Administration of streptozotocin in conjunction with a high-fat diet induced systemic hypertension, diabetes, and renal damage in rats. Delivery of rAAV-HK resulted in a long-term reduction in blood pressure, and fasting plasma insulin was significantly lower in the rAAV-HK group than in the control group. The expression of phosphatidylinositol 3-kinase p110 catalytic subunit and the levels of phosphorylation at residue Thr-308 of Akt, insulin receptor B, and AMP-activated protein kinases were significantly decreased in organs from diabetic animals. These changes were significantly attenuated after rAAV-mediated HK gene therapy. Moreover, rAAV-HK significantly decreased urinary microalbumin excretion, improved creatinine clearance, and increased urinary osmolarity. HK gene therapy also attenuated diabetic renal damage as assessed by histology. Together, these findings demonstrate that rAAV-HK delivery can efficiently attenuate hypertension, insulin resistance, and diabetic nephropathy in streptozotocin-induced diabetic rats.

  6. AMPKα2基因克隆及其野生型和突变型真核表达载体的构建%Cloning of activating adenosine monophosphate-activated protein kinase alpha 2 subunit gene and construction of its wild-type and mutant eukaryotic expression vectors

    罗招凡; 李芳萍; 丁鹤林; 程桦

    2009-01-01

    背景:实验表明,通过激活单磷酸腺苷激活的蛋白激酶(AMP-Activated Protein Kinase, AMPK)α2可以增加胰岛素的敏感性和骨骼肌葡萄糖的摄取,其有望成为预防和治疗2型糖尿病的新的生理和药理作用靶点.目的:克隆人的AMPKα2基因,并构建其野生型和突变型真核表达载体.设计:单一样本观察.时间及地点:实验于2007-04/2008-01在中山大学附属第二医院临床分子生物实验室完成.材料:QuikChange Ⅱ Site-Directed Mutagenesis Kit为Stratagene公司产品.真核表达载体pcDNA3.1(+),大肠杆菌DH5α为实验室保存.人骨胳肌组织来源于中山大学附属第二医院手术截肢患者,获患者知情同意,新鲜取材后液氮冷冻.方法:采用反转录一聚合酶链反应技术从人骨骼肌扩增AMPKα2基因,并将其克隆到T载体,通过测序对其进行鉴定.采用Quickchange定点诱变试剂盒对AMPKα2基因进行体外定点诱变,并将其野生和突变的编码基因亚克隆到真核表达载体pcDNA3.1中,通过酶切和测序进行鉴定.主要观察指标:①目的基因的克隆.②定点诱变.③真核表达质粒的构建.结果:成功克隆了AMPKα2基因,大小约1 700 bp,与已发表的AMPKα2同源性为99%,GenBank录入号EF056019.成功将AMPKα2第45位Lysine(AAA)突变为Arginine(AGA),成功构建了野生型和突变型pcDNA-AMPK α2重组质粒.结论:实验成功克隆了AMPKα2基因,构建了其野生型和突变型真核表达载体.%BACKGROUND: The experimental results showed that insulin sensitivity and glucose uptake in skeletal muscle could be improved by activating adenosine monophosphate-activated protein kinase a2 (AMPKα2). AMPKa2 is expected to become a new physiological and pharmacological target for the prevention and treatment of type 2 diabetes mellitus. OBJECTIVE: To clone human AMPKa2 subunit gene and to construct its wild-type and mutant eukaryotic expression vectors. DESIGN: A single sample observation

  7. 辛伐他汀抑制肝星状细胞活化及其对腺苷酸活化蛋白激酶活性的影响%Simvastatin inhibits activation of hepatic stellate cells and promotes activation of adenosine monophosphate activated protein kinase

    曹伟; 闫蕾; 王玮; 赵彩彦

    2012-01-01

    the underlying molecular mechanism ofthe cholesterol-blocking drug,simvastatin,in treating nonalcoholic fatty liver fibrosis.Method A rat model of nonalcoholic fatty liver fibrosis was established by feeding Wistar rats a fat-rich diet.After treatment with simvastatin (4 mg/kg/day),liver histological specimens were stained with hematoxylin-eosin and Masson's trichrome for microscopic analysis.Expression of adenosine monophosphate-activated protein kinase-alpha (AMPKα) was evaluated by reverse transcription-polymerase chain reaction (RT-PCR; for mRNA) and Western blotting (protein).The levels of serum total cholesterol (TC),triglycerides (TG),alanine aminotransferase (ALT),aspartate aminotransferase (AST),and tumor necrosis factor-alpha (TNFa) were measured by standard biochemical assays.The human hepatic stellate cell line,LX-2 (quiescent or activated),was treated with transforming growth factor-beta l (TGF-β1) alone,simvastatin alone,or TGF-β1 +simvastatin.RT-PCR and Western blotting were used to determine changes in AMPKα mRNA and protein expression,respectively.Results In the rat model of nonalcoholic fatty liver fibrosis,the extent of pathological changes in hepatic tissues correlated with severity of disease progression.The levels of serum TC,TG,ALT,AST and TNFα were increased significantly in model rats (vs.healthy controls; all,P< 0.01).AMPKα mRNA expression and activity was significantly decreased in model rats (vs.healthy controls; P< 0.01 and P< 0.05,respectively).Simvastatin,treatment significantly improved all of these parameters in model rats (vs.untreated model rats; all,P< 0.05).In vitro simvastatin treatment of human HSCs significantly increased AMPKα activity (quiescent LX-2:0.93 -0.10 vs.0.72±0.09,activated LX-2:0.72±0.10 vs.0.54±0.10,q=7.00,6.00; all,P<0.01),decreased a-smooth muscle actin expression (mRNA:0.30±0.02 vs.0.36±0.02,protein:0.30±0.03 vs.0.38±0.02,q=11.245,11.216; all,P<0.01),and decreased collagen I expression

  8. Adenosine Monophosphate (AMP)-Activated Protein Kinase: A New Target for Nutraceutical Compounds.

    Marín-Aguilar, Fabiola; Pavillard, Luis E; Giampieri, Francesca; Bullón, Pedro; Cordero, Mario D

    2017-01-29

    Adenosine monophosphate-activated protein kinase (AMPK) is an important energy sensor which is activated by increases in adenosine monophosphate (AMP)/adenosine triphosphate (ATP) ratio and/or adenosine diphosphate (ADP)/ATP ratio, and increases different metabolic pathways such as fatty acid oxidation, glucose transport and mitochondrial biogenesis. In this sense, AMPK maintains cellular energy homeostasis by induction of catabolism and inhibition of ATP-consuming biosynthetic pathways to preserve ATP levels. Several studies indicate a reduction of AMPK sensitivity to cellular stress during aging and this could impair the downstream signaling and the maintenance of the cellular energy balance and the stress resistance. However, several diseases have been related with an AMPK dysfunction. Alterations in AMPK signaling decrease mitochondrial biogenesis, increase cellular stress and induce inflammation, which are typical events of the aging process and have been associated to several pathological processes. In this sense, in the last few years AMPK has been identified as a very interesting target and different nutraceutical compounds are being studied for an interesting potential effect on AMPK induction. In this review, we will evaluate the interaction of the different nutraceutical compounds to induce the AMPK phosphorylation and the applications in diseases such as cancer, type II diabetes, neurodegenerative diseases or cardiovascular diseases.

  9. Stabilizing effects of G protein on the active conformation of adenosine A1 receptor differ depending on G protein type.

    Tateyama, Michihiro; Kubo, Yoshihiro

    2016-10-05

    G protein coupled receptors (GPCRs) trigger various cellular and physiological responses upon the ligand binding. The ligand binding induces conformational change in GPCRs which allows G protein to interact with the receptor. The interaction of G protein also affects the active conformation of GPCRs. In this study, we have investigated the effects of Gαi1, Gαo and chimeric Gαqi5 on the active conformation of the adenosine A1 receptor, as each Gα showed difference in the interaction with adenosine A1 receptor. The conformational changes in the adenosine A1 receptor were detected as the agonist-induced decreases in efficiency of Förster resonance energy transfer (FRET) between fluorescent proteins (FPs) fused at the two intracellular domains of the adenosine A1 receptor. Amplitudes of the agonist-induced FRET decreases were subtle when the FP-tagged adenosine A1 receptor was expressed alone, whereas they were significantly enhanced when co-expressed with Gαi1Gβ1Gγ22 (Gi1) or Gαqi5Gβ1Gγ22 (Gqi5) but not with GαοGβ1Gγ22 (Go). The enhancement of the agonist-induced FRET decrease in the presence of Gqi5 was significantly larger than that of Gi1. Furthermore, the FRET recovery upon the agonist removal in the presence of Gqi5 was significantly slower than that of Gi1. From these results it was revealed that the agonist-bound active conformation of adenosine A1 receptor is unstable without the binding of G protein and that the stabilizing effects of G protein differ depending on the types of G protein.

  10. Does unpaired adenosine-66 from helix II of Escherichia coli 5S RNA bind to protein L18?

    Christiansen, J; Douthwaite, S R; Christensen, A;

    1985-01-01

    Adenosine-66 is unpaired within helix II of Escherichia coli 5S RNA and lies in the binding site of ribosomal protein L18. It has been proposed as a recognition site for protein L18. We have investigated further the structural importance of this nucleotide by deleting it. The 5S RNA gene of the r...

  11. Icariin upregulates phosphorylated cyclic adenosine monophosphate response element binding protein levels in the hippocampus of the senescence- accelerated mouse

    Zhanwei Zhang; Ting Zhang; Keli Dong

    2012-01-01

    At 8 weeks after intragastric administration of icariin to senescence-accelerated mice (P8 strain), Morris water maze results showed that escape latency was shortened, and the number of platform crossings was increased. Immunohistochemical staining and western blot assay detected signifi-cantly increased levels of cyclic adenosine monophosphate response element binding protein. These results suggest that icariin upregulates phosphorylated cyclic adenosine monophosphate response element binding protein levels and improves learning and memory functions in hippo-campus of the senescence-accelerated mouse.

  12. Serum Adenosine deaminase activity and C-reactive protein levels in unstable angina

    Rani Surekha

    2003-01-01

    Full Text Available In unstable angina (USA patients, immunological responses contributing to inflammation play a vital role in plaque rupture and thrombosis causing stroke. In the present study an attempt is made to estimate the levels of adenosine deaminase activity, an immunoenzyme marker and C-reactive protein, a marker of inflammation in USA patients. 45 patients presenting USA and 50 age and sex matched healthy controls were included in the study. Serum ADA activity was measured spectrophotometrically at 630nm and serum C-reactive protein was detected using Avitex CRP kit, which is a rapid latex agglutination test. The Mean ADA levels were 41.15 ± 11.04 in patients and 20.71±5.63 in controls and 66.6% of patients and none of the controls were positive to CRP. The present study observed the importance of ADA as a serum marker in addition to CRP for assessing the immune response in USA patients.

  13. Amplified Peroxidase-Like Activity in Iron Oxide Nanoparticles Using Adenosine Monophosphate: Application to Urinary Protein Sensing.

    Yang, Ya-Chun; Wang, Yen-Ting; Tseng, Wei-Lung

    2017-03-08

    Numerous compounds such as protein and double-stranded DNA have been shown to efficiently inhibit intrinsic peroxidase-mimic activity in Fe3O4 nanoparticles (NP) and other related nanomaterials. However, only a few studies have focused on finding new compounds for enhancing the catalytic activity of Fe3O4 NP-related nanomaterials. Herein, phosphate containing adenosine analogs are reported to enhance the oxidation reaction of hydrogen peroxide (H2O2) and amplex ultrared (AU) for improving the peroxidase-like activity in Fe3O4 NPs. This enhancement is suggested to be a result of the binding of adenosine analogs to Fe(2+)/Fe(3+) sites on the NP surface and from adenosine 5'-monophosphate (AMP) acting as the distal histidine residue of horseradish peroxidase for activating H2O2. Phosphate containing adenosine analogs revealed the following trend for the enhanced activity of Fe3O4 NPs: AMP > adenosine 5'-diphosphate > adenosine 5'-triphosphate. The peroxidase-like activity in the Fe3O4 NPs progressively increased with increasing AMP concentration and polyadenosine length. The Michaelis constant for AMP attached Fe3O4 NPs is 5.3-fold lower and the maximum velocity is 2.7-fold higher than those of the bare Fe3O4 NPs. Furthermore, on the basis of AMP promoted peroxidase mimicking activity in the Fe3O4 NPs and the adsorption of protein on the NP surface, a selective fluorescent turn-off system for the detection of urinary protein is developed.

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

    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.

  15. Facile synthesis of N-6 adenosine modified analogue toward S-adenosyl methionine derived probe for protein arginine methyltransferases

    Wei Hong; James Dowden

    2011-01-01

    Chemically modified cellular co-factors that provide function, such as immobilization or incorporation of fluorescent dyes, are valuable probes of biological activity. A convenient route to obtain S-adenosyl methionine (AdoMet) analogues modified at N-6 adenosine to feature a linker terminating in azide functionality is described herein. Subsequent decoration of such AdoMet analogues with guanidinium terminated linkers leads to novel potential bisubstrate inhibitors for protein arginine methyltransferases, PRMTs.

  16. ADENOSINE DEAMINASE ACTIVITY AND SERUM C-REACTIVE PROTEIN AS PROGNOSTIC MARKERS OF CHAGAS DISEASE SEVERITY

    Iván Darío BRAVO-TOBAR

    2015-10-01

    Full Text Available SUMMARY Chagas disease is a public health problem worldwide. The availability of diagnostic tools to predict the development of chronic Chagas cardiomyopathy is crucial to reduce morbidity and mortality. Here we analyze the prognostic value of adenosine deaminase serum activity (ADA and C-reactive protein serum levels (CRP in chagasic individuals. One hundred and ten individuals, 28 healthy and 82 chagasic patients were divided according to disease severity in phase I (n = 35, II (n = 29, and III (n = 18. A complete medical history, 12-lead electrocardiogram, chest X-ray, and M-mode echocardiogram were performed on each individual. Diagnosis of Chagas disease was confirmed by ELISA and MABA using recombinant antigens; ADA was determined spectrophotometrically and CRP by ELISA. The results have shown that CRP and ADA increased linearly in relation to disease phase, CRP being significantly higher in phase III and ADA at all phases. Also, CRP and ADA were positively correlated with echocardiographic parameters of cardiac remodeling and with electrocardiographic abnormalities, and negatively with ejection fraction. CRP and ADA were higher in patients with cardiothoracic index ≥ 50%, while ADA was higher in patients with ventricular repolarization disturbances. Finally, CRP was positively correlated with ADA. In conclusion, ADA and CRP are prognostic markers of cardiac dysfunction and remodeling in Chagas disease.

  17. ADENOSINE DEAMINASE ACTIVITY AND SERUM C-REACTIVE PROTEIN AS PROGNOSTIC MARKERS OF CHAGAS DISEASE SEVERITY

    BRAVO-TOBAR, Iván Darío; NELLO-PÉREZ, Carlota; FERNÁNDEZ, Alí; MOGOLLÓN, Nora; PÉREZ, Mary Carmen; VERDE, Juan; CONCEPCIÓN, Juan Luis; RODRIGUEZ-BONFANTE, Claudina; BONFANTE-CABARCAS, Rafael

    2015-01-01

    SUMMARY Chagas disease is a public health problem worldwide. The availability of diagnostic tools to predict the development of chronic Chagas cardiomyopathy is crucial to reduce morbidity and mortality. Here we analyze the prognostic value of adenosine deaminase serum activity (ADA) and C-reactive protein serum levels (CRP) in chagasic individuals. One hundred and ten individuals, 28 healthy and 82 chagasic patients were divided according to disease severity in phase I (n = 35), II (n = 29), and III (n = 18). A complete medical history, 12-lead electrocardiogram, chest X-ray, and M-mode echocardiogram were performed on each individual. Diagnosis of Chagas disease was confirmed by ELISA and MABA using recombinant antigens; ADA was determined spectrophotometrically and CRP by ELISA. The results have shown that CRP and ADA increased linearly in relation to disease phase, CRP being significantly higher in phase III and ADA at all phases. Also, CRP and ADA were positively correlated with echocardiographic parameters of cardiac remodeling and with electrocardiographic abnormalities, and negatively with ejection fraction. CRP and ADA were higher in patients with cardiothoracic index ≥ 50%, while ADA was higher in patients with ventricular repolarization disturbances. Finally, CRP was positively correlated with ADA. In conclusion, ADA and CRP are prognostic markers of cardiac dysfunction and remodeling in Chagas disease. PMID:26603224

  18. Adenosine activates ATP-sensitive potassium channels in arterial myocytes via A2 receptors and cAMP-dependent protein kinase.

    Kleppisch, T; Nelson, M T

    1995-01-01

    The mechanism by which the endogenous vasodilator adenosine causes ATP-sensitive potassium (KATP) channels in arterial smooth muscle to open was investigated by the whole-cell patch-clamp technique. Adenosine induced voltage-independent, potassium-selective currents, which were inhibited by glibenclamide, a blocker of KATP currents. Glibenclamide-sensitive currents were also activated by the selective adenosine A2-receptor agonist 2-p-(2-carboxethyl)-phenethylamino-5'-N- ethylcarboxamidoadenosine hydrochloride (CGS-21680), whereas 2-chloro-N6-cyclopentyladenosine (CCPA), a selective adenosine A1-receptor agonist, failed to induce potassium currents. Glibenclamide-sensitive currents induced by adenosine and CGS-21680 were largely reduced by blockers of the cAMP-dependent protein kinase (Rp-cAMP[S], H-89, protein kinase A inhibitor peptide). Therefore, we conclude that adenosine can activate KATP currents in arterial smooth muscle through the following pathway: (i) Adenosine stimulates A2 receptors, which activates adenylyl cyclase; (ii) the resulting increase intracellular cAMP stimulates protein kinase A, which, probably through a phosphorylation step, opens KATP channels. PMID:8618917

  19. Hepatitis C virus core protein induces energy metabolism disorders of hepatocytes by down-regulation of silent mating type information regulation 2 homolog-1 and adenosine monophosphate-acti vated protein kinase signaling pathway

    于建武

    2013-01-01

    Objective To study the role of silent mating type information regulation2homotog-1(SIRT1)-adenosine monophosphate(AMP)-activated protein kinase(AMPK) signaling pathway in hepatitis C virus core protein(HCV-core)induced energy metabolism disorders

  20. cAMP-independent dilation of coronary arterioles to adenosine : role of nitric oxide, G proteins, and K(ATP) channels.

    Hein, T W; Kuo, L

    1999-10-01

    Adenosine is known to play an important role in the regulation of coronary blood flow during metabolic stress. However, there is sparse information on the mechanism of adenosine-induced dilation at the microcirculatory levels. In the present study, we examined the role of endothelial nitric oxide (NO), G proteins, cyclic nucleotides, and potassium channels in coronary arteriolar dilation to adenosine. Pig subepicardial coronary arterioles (50 to 100 microm in diameter) were isolated, cannulated, and pressurized to 60 cm H(2)O without flow for in vitro study. The arterioles developed basal tone and dilated dose dependently to adenosine. Disruption of endothelium, blocking of endothelial ATP-sensitive potassium (K(ATP)) channels by glibenclamide, and inhibition of NO synthase by N(G)-nitro-L-arginine methyl ester and of soluble guanylyl cyclase by 1H-[1,2,4]oxadiazolo[4,3,-a]quinoxalin-1-one produced identical attenuation of vasodilation to adenosine. Combined administration of these inhibitors did not further attenuate the vasodilatory response. Production of NO from coronary arterioles was significantly increased by adenosine. Pertussis toxin, but not cholera toxin, significantly inhibited vasodilation to adenosine, and this inhibitory effect was only evident in vessels with an intact endothelium. Tetraethylammonium, glibenclamide, and a high concentration of extraluminal KCl abolished vasodilation of denuded vessels to adenosine; however, inhibition of calcium-activated potassium channels by iberiotoxin had no effect on this dilation. Rp-8-Br-cAMPS, a cAMP antagonist, inhibited vasodilation to cAMP analog 8-Br-cAMP but failed to block adenosine-induced dilation. Furthermore, vasodilations to 8-Br-cAMP and sodium nitroprusside were not inhibited by glibenclamide, indicating that cAMP- and cGMP-induced dilations are not mediated by the activation of K(ATP) channels. These results suggest that adenosine activates both endothelial and smooth muscle pathways to exert

  1. Modulation of glycogen and breast meat processing ability by nutrition in chickens: effect of crude protein level in 2 chicken genotypes.

    Jlali, M; Gigaud, V; Métayer-Coustard, S; Sellier, N; Tesseraud, S; Le Bihan-Duval, E; Berri, C

    2012-02-01

    The aim of the study was to evaluate the impact of 2 isoenergetic growing diets with different CP (17 vs. 23%) on the performance and breast meat quality of 2 lines of chicken divergently selected for abdominal fatness [i.e., fat and lean (LL) lines]. Growth performance, breast and abdominal fat yields, breast meat quality parameters (pH, color, drip loss), and muscle glycogen storage at death were measured. Increased dietary CP resulted in increased BW, increased breast meat yield, and reduced abdominal fatness at slaughter regardless of genotype (P muscle glycogen (P muscle glycogen content observed in LL receiving the low-CP diet compared with the high-CP diet occurred concomitantly with greater phosphorylation amount for the α-catalytic subunit of adenosine monophosphate-activated protein kinase and glycogen synthase. This was consistent with the reduced muscle glycogen content observed in LL fed the low-CP diet because adenosine monophosphate-activated protein kinase inhibits glycogen synthesis through its action on glycogen synthase. Our results demonstrated that nutrition is an effective means of modulating breast meat properties in the chicken. The results also highlighted the need to take into account interaction with the genetic background of the animal to select nutritional strategies to improve meat quality traits in poultry.

  2. Inhibition of thyrotropin-stimulated adenosine 3',5'-monophosphate formation in rat thyroid cells by an adenosine analog. Evidence that the inhibition is mediated by the putative inhibitory guanine nucleotide regulatory protein.

    Berman, M I; Thomas, C G; Nayfeh, S N

    1986-01-01

    Addition of N6-(L-2-phenylisopropyl)-adenosine (PIA) to cultured FRTL-5 rat thyroid cells led to a concentration-dependent inhibition of TSH-stimulated cAMP formation. Half-maximal inhibition was attained with approximately 0.5 nM PIA. Forskolin and cholera toxin-stimulated cAMP production were also inhibited by PIA. 3-Isobutyl-methylxanthine inhibited the effect of PIA. These results are consistent with the presence of inhibitory adenosine receptors (Ri). Ri-sites were further demonstrated by the binding of 3H-cyclohexyl-adenosine to FRTL-5 plasma membranes. High (Kd = 0.50 +/- 0.07 nM) and low affinity (Kd = 5.95 +/- 2.33 nM) binding sites were observed. Pretreatment of FRTL-5 cells with pertussis, but not cholera, toxin effectively antagonized the inhibitory effects of PIA on cAMP production. ADP-ribosylation of FRTL-5 membranes with [32P]-NAD in the presence of cholera or pertussis toxin specifically labeled a 45,000 and 41,000 Mr species, respectively, which correspond to the alpha subunit of the stimulatory and inhibitory guanine nucleotide regulatory proteins. These results demonstrate that PIA inhibits TSH-stimulated cAMP production via Ri-sites on FRTL-5 thyroid cells. PIA appears to exert its inhibitory effects through the inhibitory guanine nucleotide regulatory protein.

  3. Adenosine receptor neurobiology: overview.

    Chen, Jiang-Fan; Lee, Chien-fei; Chern, Yijuang

    2014-01-01

    Adenosine is a naturally occurring nucleoside that is distributed ubiquitously throughout the body as a metabolic intermediary. In the brain, adenosine functions as an important upstream neuromodulator of a broad spectrum of neurotransmitters, receptors, and signaling pathways. By acting through four G-protein-coupled receptors, adenosine contributes critically to homeostasis and neuromodulatory control of a variety of normal and abnormal brain functions, ranging from synaptic plasticity, to cognition, to sleep, to motor activity to neuroinflammation, and cell death. This review begun with an overview of the gene and genome structure and the expression pattern of adenosine receptors (ARs). We feature several new developments over the past decade in our understanding of AR functions in the brain, with special focus on the identification and characterization of canonical and noncanonical signaling pathways of ARs. We provide an update on functional insights from complementary genetic-knockout and pharmacological studies on the AR control of various brain functions. We also highlight several novel and recent developments of AR neurobiology, including (i) recent breakthrough in high resolution of three-dimension structure of adenosine A2A receptors (A2ARs) in several functional status, (ii) receptor-receptor heterodimerization, (iii) AR function in glial cells, and (iv) the druggability of AR. We concluded the review with the contention that these new developments extend and strengthen the support for A1 and A2ARs in brain as therapeutic targets for neurologic and psychiatric diseases.

  4. Mutations in the human adenosine deaminase gene that affect protein structure and RNA splicing

    Akeson, A.L.; Wiginton, D.A.; States, C.J.; Perme, C.M.; Dusing, M.R.; Hutton, J.J.

    1987-08-01

    Adenosine deaminase deficiency is one cause of the genetic disease severe combined immunodeficiency. To identify mutations responsible for ADA deficiency, the authors synthesized cDNAs to ADA mRNAs from two cell lines, GM2756 and GM2825A, derived from ADA-deficient immunodeficient patients. Sequence analysis of GM2756 cDNA clones revealed a different point mutation in each allele that causes amino acid changes of alanine to valine and arginine to histidine. One allele of GM2825A also has a point mutation that causes an alanine to valine substitution. The other allele of GM2825A was found to produce an mRNA in which exon 4 had been spliced out but had no other detrimental mutations. S1 nuclease mapping of GM2825A mRNA showed equal abundance of the full-length ADA mRNA and the ADA mRNA that was missing exon 4. Several of the ADA cDNA clones extended 5' of the major initiation start site, indicating multiple start sites for ADA transcription. The point mutations in GM2756 and GM2825A and the absence of exon 4 in GM2825A appear to be directly responsible for the ADA deficiency. Comparison of a number of normal and mutant ADA cDNA sequences showed a number of changes in the third base of codons. These change do not affect the amino acid sequence. Analyses of ADA cDNAs from different cell lines detected aberrant RNA species that either included intron 7 or excluded exon 7. Their presence is a result of aberrant splicing of pre-mRNAs and is not related to mutations that cause ADA deficiency.

  5. Phenotype, virulence and immunogenicity of Edwardsiella ictaluri cyclic adenosine 3',5'-monophosphate receptor protein (Crp) mutants in catfish host.

    Santander, Javier; Mitra, Arindam; Curtiss, Roy

    2011-12-01

    Edwardsiella ictaluri is an Enterobacteriaceae that causes lethal enteric septicemia in catfish. Being a mucosal facultative intracellular pathogen, this bacterium is an excellent candidate to develop immersion-oral live attenuated vaccines for the catfish aquaculture industry. Deletion of the cyclic 3',5'-adenosine monophosphate (cAMP) receptor protein (crp) gene in several Enterobacteriaceae has been utilized in live attenuated vaccines for mammals and birds. Here we characterize the crp gene and report the effect of a crp deletion in E. ictaluri. The E. ictaluri crp gene and encoded protein are similar to other Enterobacteriaceae family members, complementing Salmonella enterica Δcrp mutants in a cAMP-dependent fashion. The E. ictaluri Δcrp-10 in-frame deletion mutant demonstrated growth defects, loss of maltose utilization, and lack of flagella synthesis. We found that the E. ictaluri Δcrp-10 mutant was attenuated, colonized lymphoid tissues, and conferred immune protection against E. ictaluri infection to zebrafish (Danio rerio) and catfish (Ictalurus punctatus). Evaluation of the IgM titers indicated that bath immunization with the E. ictaluri Δcrp-10 mutant triggered systemic and skin immune responses in catfish. We propose that deletion of the crp gene in E. ictaluri is an effective strategy to develop immersion live attenuated antibiotic-sensitive vaccines for the catfish aquaculture industry.

  6. Regulation of adenosine levels during cerebral ischemia

    Stephanie CHU; Wei XIONG; Dali ZHANG; Hanifi SOYLU; Chao SUN; Benedict C ALBENSI; Fiona E PARKINSON

    2013-01-01

    Adenosine is a neuromodulator with its level increasing up to 100-fold during ischemic events,and attenuates the excitotoxic neuronal injury.Adenosine is produced both intracellularly and extracellularly,and nucleoside transport proteins transfer adenosine across plasma membranes.Adenosine levels and receptor-mediated effects of adenosine are regulated by intracellular ATP consumption,cellular release of ATP,metabolism of extracellular ATP (and other adenine nucleotides),adenosine influx,adenosine efflux and adenosine metabolism.Recent studies have used genetically modified mice to investigate the relative contributions of intra-and extracellular pathways for adenosine formation.The importance of cortical or hippocampal neurons as a source or a sink of adenosine under basal and hypoxic/ischemic conditions was addressed through the use of transgenic mice expressing human equilibrative nucleoside transporter 1 (hENT1) under the control of a promoter for neuron-specific enolase.From these studies,we conclude that ATP consumption within neurons is the primary source of adenosine in neuronal cultures,but not in hippocampal slices or in vivo mice exposed to ischemic conditions.

  7. Pathologic overproduction: the bad side of adenosine.

    Borea, Pier Andrea; Gessi, Stefania; Merighi, Stefania; Vincenzi, Fabrizio; Varani, Katia

    2017-03-02

    Adenosine is an endogenous ubiquitous purine nucleoside, increased by hypoxia, ischemia and tissue damage that mediates a number of physiopathological effects by interacting with four G-protein-coupled receptors, identified as A1 , A2A , A2B , and A3 . Physiological and acutely-increased adenosine is associated with beneficial effects mostly including vasodilation and decrease of inflammation. In contrast chronic overproduction of adenosine occurs in important pathological states, where long lasting increases in the nucleoside levels are responsible for the bad side of adenosine associated with chronic inflammation, fibrosis and organ damage. In this review we describe and critically discuss the pathologic overproduction of adenosine analysing when, where and how adenosine exerts its detrimental effects through the body.

  8. Sevoflurane effects on cyclic adenosine monophosphate response element binding protein, phosphorylated cyclic adenosine monophosphate response element binding protein, and Livin expression in the cortex and hippocampus of a vascular cognitive impairment rat model

    Bin Wu; Ling Dan; Xianlin Zhu

    2009-01-01

    BACKGROUND: Neuronal necrosis and apoptosis play important roles in the pathophysiology of cerebral ischemia and resulting cognitive impairment. However, inhibition of neuronal necrosis and apoptosis has been shown to attenuate cognitive impairment following cerebral ischemia.OBJECTIVE: To investigate the effects of sevoflurane on cyclic adenosine monophosphate response element binding protein (CREB), phosphorylated CREB (pCREB), and Livin expression in the cortex and hippocampus of a rat model of vascular cognitive impairment.DESIGN, TIME AND SETTING: A randomized, controlled experiment was performed in the Chongqing Key Laboratory of Neurology between June 2007 and July 2008.MATERIALS: Sevoflurane was provided by Abbott Laboratory, UK; Morris water maze was provided by Chinese Academy of Medical Sciences, China; goat anti-rat CREB, goat anti-rat pCREB and goat anti-rat Livin antibodies were provided by Biosource International, USA.METHODS: A total of 42 female, Wistar rats were randomly assigned to the following groups: sham operation, vascular cognitive impairment, and sevoflurane treatment. The vascular cognitive impairment rat model was established by permanent bilateral occlusion of both common carotid arteries, and 1.0 MAC sevoflurane was immediately administered by inhalation for 2 hours.MAIN OUTCOME MEASURES: CREB, pCREB, and Livin expression was measured in the cortex and hippocampus by Western blot and reverse transcription-polymerase chain reaction. Behavior was evaluated with Morris water maze.RESULTS: CREB, pCREB, and Livin expression in the sevoflurane treatment group was significantly greater than the vascular cognitive impairment group (P<0.01). However, expression of CREB and pCREB was significantly less in the sevoflurane treatment and vascular cognitive impairment groups, compared with the sham operation group (P<0.01). Livin expression in the sevoflurane treatment and vascular cognitive impairment groups was significantly greater than the sham

  9. Adenosine and adenosine receptors: Newer therapeutic perspective

    Manjunath S

    2009-01-01

    Full Text Available Adenosine, a purine nucleoside has been described as a ′retaliatory metabolite′ by virtue of its ability to function in an autocrine manner and to modify the activity of a range of cell types, following its extracellular accumulation during cell stress or injury. These effects are largely protective and are triggered by binding of adenosine to any of the four adenosine receptor subtypes namely A1, A2a, A2b, A3, which have been cloned in humans, and are expressed in most of the organs. Each is encoded by a separate gene and has different functions, although overlapping. For instance, both A1 and A2a receptors play a role in regulating myocardial oxygen consumption and coronary blood flow. It is a proven fact that adenosine plays pivotal role in different physiological functions, such as induction of sleep, neuroprotection and protection against oxidative stress. Until now adenosine was used for certain conditions like paroxysmal supraventricular tachycardia (PSVT and Wolff Parkinson White (WPW syndrome. Now there is a growing evidence that adenosine receptors could be promising therapeutic targets in a wide range of conditions including cardiac, pulmonary, immunological and inflammatory disorders. After more than three decades of research in medicinal chemistry, a number of selective agonists and antagonists of adenosine receptors have been discovered and some have been clinically evaluated, although none has yet received regulatory approval. So this review focuses mainly on the newer potential role of adenosine and its receptors in different clinical conditions.

  10. Muscle A-Kinase Anchoring Protein-α is an Injury-Specific Signaling Scaffold Required for Neurotrophic- and Cyclic Adenosine Monophosphate-Mediated Survival

    Yan Wang

    2015-12-01

    Full Text Available Neurotrophic factor and cAMP-dependent signaling promote the survival and neurite outgrowth of retinal ganglion cells (RGCs after injury. However, the mechanisms conferring neuroprotection and neuroregeneration downstream to these signals are unclear. We now reveal that the scaffold protein muscle A-kinase anchoring protein-α (mAKAPα is required for the survival and axon growth of cultured primary RGCs. Although genetic deletion of mAKAPα early in prenatal RGC development did not affect RGC survival into adulthood, nor promoted the death of RGCs in the uninjured adult retina, loss of mAKAPα in the adult increased RGC death after optic nerve crush. Importantly, mAKAPα was required for the neuroprotective effects of brain-derived neurotrophic factor and cyclic adenosine-monophosphate (cAMP after injury. These results identify mAKAPα as a scaffold for signaling in the stressed neuron that is required for RGC neuroprotection after optic nerve injury.

  11. WBC27, an Adenosine Tri-phosphate-binding Cassette Protein, Controls Pollen Wall Formation and Patterning in Arabidopsis

    Xiao-Ying Dou; Ke-Zhen Yang; Yi Zhang; Wei Wang; Xiao-Lei Liu; Li-Qun Chen; Xue-Qin Zhang; De Ye

    2011-01-01

    In flowering plants, the exine components are derived from tapetum. Despite its importance to sexual plant reproduction, little is known about the translocation of exine materials from tapetum to developing microspores. Here we report functional characterization of the arabidopsis WBC27 gene. WBC27 encodes an adenosine tri-phosphate binding cassette (ABC) transporter and is expressed preferentially in tapetum. Mutation of WBC27 disrupted the exine formation. The wbc27 mutant microspores began to degenerate once released from tetrads and most of the microspores collapsed at the uninucleate stage. Only a small number of wbc27-1 microspores could develop into tricellular pollen grains. These survival pollen grains lacked exine and germinated in the anther before anthesis. All of these results suggest that the ABC transporter, WBC27 plays important roles in the formation of arabidopsis exine, possibly by translocation of lipidic precursors of sporopollenin from tapetum to developing microspores.

  12. New ribosome-inactivating proteins with polynucleotide:adenosine glycosidase and antiviral activities from Basella rubra L. and bougainvillea spectabilis Willd.

    Bolognesi, A; Polito, L; Olivieri, F; Valbonesi, P; Barbieri, L; Battelli, M G; Carusi, M V; Benvenuto, E; Del Vecchio Blanco, F; Di Maro, A; Parente, A; Di Loreto, M; Stirpe, F

    1997-12-01

    New single-chain (type 1) ribosome-inactivating proteins (RIPs) were isolated from the seeds of Basella rubra L. (two proteins) and from the leaves of Bougainvillea spectabilis Willd. (one protein). These RIPs inhibit protein synthesis both in a cell-free system, with an IC50 (concentration causing 50% inhibition) in the 10(-10) M range, and by various cell lines, with IC50S in the 10(-8)-10(-6) M range. All three RIPs released adenine not only from rat liver ribosomes but also from Escherichia coli rRNA, polyadenylic acid, herring sperm DNA, and artichoke mottled crinkle virus (AMCV) genomic RNA, thus being polynucleotide:adenosine glycosidases. The proteins from Basella rubra had toxicity to mice similar to that of most type 1 RIPs (Barbieri et al., 1993, Biochim Biophys Acta 1154: 237-282) with an LD50 (concentration that is 50% lethal) Bougainvillea spectabilis had an LD50 > 32 mg.kg-1. The N-terminal sequence of the two RIPs from Basella rubra had 80-93% identity, whereas it differed from the sequence of the RIP from Bougainvillea spectabilis. When tested with antibodies against various RIPs, the RIPs from Basella gave some cross-reactivity with sera against dianthin 32, and weak cross-reactivity with momordin I and momorcochin-S, whilst the RIP from Bougainvillea did not cross-react with any antiserum tested. An RIP from Basella rubra and one from Bougainvillea spectabilis were tested for antiviral activity, and both inhibited infection of Nicotiana benthamiana by AMCV.

  13. Adenosine Diphosphate Ribosylation Factor-GTPaseActivating Protein Stimulates the Transport of AUX1Endosome, Which Relies on Actin Cytoskeletal Organization in Rice Root DevelopmentF

    Cheng Du; Yunyuan XU; Yingdian Wang; Kang Chong

    2011-01-01

    Polar auxin transport,which depends on polarized subcellular distribution of AUXIN RESISTANT 1/LIKE AUX1 (AUX1/LAX) influx carriers and PIN-FORMED (PIN) efflux carriers,mediates various processes of plant growth and development.Endosomal recycling of PIN1 is mediated by an adenosine diphosphate (ADP)ribosylation factor (ARF)-GTPase exchange factor protein,GNOM.However,the mediation of auxin influx carrier recycling is poorly understood.Here,we report that overexpression of OsAGAP,an ARF-GTPase-activating protein in rice,stimulates vesicle transport from the plasma membrane to the Golgi apparatus in protoplasts and transgenic plants and induces the accumulation of early endosomes and AUX1.AUX1 endosomes could partially colocalize with FM4-64 labeled early endosome after actin disruption.Furthermore,OsAGAP is involved in actin cytoskeletal organization,and its overexpression tends to reduce the thickness and bundling of actin filaments.Fluorescence recovery after photobleaching analysis revealed exocytosis of the AUX1 recycling endosome was not affected in the OsAGAP overexpression cells,and was only slightly promoted when the actin filaments were completely disrupted by Lat B.Thus,we propose that AUX1 accumulation in the OsAGAP overexpression and actin disrupted cells may be due to the fact that endocytosis of the auxin influx carrier AUX1 early endosome was greatly promoted by actin cytoskeleton disruption.

  14. Overexpression of human selenoprotein H in neuronal cells enhances mitochondrial biogenesis and function through activation of protein kinase A, protein kinase B, and cyclic adenosine monophosphate response element-binding protein pathway.

    Mehta, Suresh L; Mendelev, Natalia; Kumari, Santosh; Andy Li, P

    2013-03-01

    Mitochondrial biogenesis is activated by nuclear encoded transcription co-activator peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α), which is regulated by several upstream factors including protein kinase A and Akt/protein kinase B. We have previously shown that selenoprotein H enhances the levels of nuclear regulators for mitochondrial biogenesis, increases mitochondrial mass and improves mitochondrial respiratory rate, under physiological condition. Furthermore, overexpression of selenoprotein H protects neuronal HT22 cells from ultraviolet B irradiation-induced cell damage by lowering reactive oxygen species production, and inhibiting activation of caspase-3 and -9, as well as p53. The objective of this study is to identify the cell signaling pathways by which selenoprotein H initiates mitochondrial biogenesis. We first confirmed our previous observation that selenoprotein H transfected HT22 cells increased the protein levels of nuclear-encoded mitochondrial biogenesis factors, peroxisome proliferator-activated receptor γ coactivator-1α, nuclear respiratory factor 1 and mitochondrial transcription factor A. We then observed that total and phosphorylation of protein kinase A, Akt/protein kinase B and cyclic adenosine monophosphate response element-binding protein (CREB) were significantly increased in selenoprotein H transfected cells compared to vector transfected HT22 cells. To verify whether the observed stimulating effects on mitochondrial biogenesis pathways are caused by selenoprotein H and mediated through CREB, we knocked down selenoprotein H mRNA level using siRNA and inhibited CREB with napthol AS-E phosphate in selenoprotein H transfected cells and repeated the measurements of the aforementioned biomarkers. Our results revealed that silencing of selenoprotein H not only decreased the protein levels of PGC-1α, nuclear respiratory factor 1 and mitochondrial transcription factor A, but also decreased the total and

  15. Caffeine, Through Adenosine A3 Receptor-Mediated Actions, Suppresses Amyloid-β Protein Precursor Internalization and Amyloid-β Generation.

    Li, Shanshan; Geiger, Nicholas H; Soliman, Mahmoud L; Hui, Liang; Geiger, Jonathan D; Chen, Xuesong

    2015-01-01

    Intraneuronal accumulation and extracellular deposition of amyloid-β (Aβ) protein continues to be implicated in the pathogenesis of Alzheimer's disease (AD), be it familial in origin or sporadic in nature. Aβ is generated intracellularly following endocytosis of amyloid-β protein precursor (AβPP), and, consequently, factors that suppress AβPP internalization may decrease amyloidogenic processing of AβPP. Here we tested the hypothesis that caffeine decreases Aβ generation by suppressing AβPP internalization in primary cultured neurons. Caffeine concentration-dependently blocked low-density lipoprotein (LDL) cholesterol internalization and a specific adenosine A3 receptor (A3R) antagonist as well as siRNA knockdown of A3Rs mimicked the effects of caffeine on neuronal internalization of LDL cholesterol. Further implicating A3Rs were findings that a specific A3R agonist increased neuronal internalization of LDL cholesterol. In addition, caffeine as well as siRNA knockdown of A3Rs blocked the ability of LDL cholesterol to increase Aβ levels. Furthermore, caffeine blocked LDL cholesterol-induced decreases in AβPP protein levels in neuronal plasma membranes, increased surface expression of AβPP on neurons, and the A3R antagonist as well as siRNA knockdown of A3Rs mimicked the effects of caffeine on AβPP surface expression. Moreover, the A3R agonist decreased neuronal surface expression of AβPP. Our findings suggest that caffeine exerts protective effects against amyloidogenic processing of AβPP at least in part by suppressing A3R-mediated internalization of AβPP.

  16. Scanning mutagenesis in a yeast system delineates the role of the NPxxY(x)(5,6)F motif and helix 8 of the adenosine A(2B) receptor in G protein coupling.

    Liu, Rongfang; Nahon, Dennis; le Roy, Beau; Lenselink, Eelke B; IJzerman, Adriaan P

    2015-06-15

    The adenosine receptor subfamily includes four subtypes: the A1, A2A, A2B and A3 receptors, which all belong to the superfamily of G protein-coupled receptors (GPCRs). The adenosine A2B receptor is the least investigated of the adenosine receptors, and the molecular mechanisms of its activation have hardly been explored. We used a single-GPCR-one-G protein yeast screening method in combination with mutagenesis studies, molecular modeling and bio-informatics to investigate the importance of the different amino acid residues of the NPxxY(x)6F motif and helix 8 in the human adenosine A2B receptor (hA2BR) activation. A scanning mutagenesis protocol was employed, yielding 11 single mutations and one double mutation of the NPxxY(x)6F motif and 16 single mutations of helix 8. The amino acid residues P287(7.50), Y290(7.53), R293(7.56) and I304(8.57) were found to be essential, since mutation of these amino acid residues to alanine led to a complete loss of function. Western blot analysis showed that mutant receptor R293(7.56)A was not expressed, whereas the other proteins were. Amino acid residues that are also important in receptor activation are: N286(7.49), V289(7.52), Y292(7.55), N294(8.47), F297(8.50), R298(8.51), H302(8.55) and R307(8.60). The mutation Y290(7.53)F lost 50% of efficacy, while F297(8.50)A behaved similar to wild type receptor. The double mutation, Y290(7.53)F/F297(8.50)Y, lost around 70% of efficacy and displayed a lower potency for the reference agonist 5'-(N-ethylcarboxamido)adenosine (NECA). This study provides new insight into the molecular interplay and impact of TM7 and helix 8 for hA2B receptor activation, which may be extrapolated to other adenosine receptors and possibly to other GPCRs.

  17. Assay of adenosine 3',5' cyclic monophosphate by stimulation of protein kinase: a method not involving radioactivity

    Handa, A.K.; Bressan, R.A.

    1980-03-01

    In order to meet a need for a cAMP assay which is not subject to interference by compounds in plant extracts, and which is suitable for use on occasions separated by many /sup 32/P half-lives, an assay based on cAMP-dependent protein kinase has been developed which does not require the use of (..gamma..-/sup 32/P)ATP. Instead of measuring the cAMP-stimulated increase in the rate of transfer of (..gamma..-/sup 32/P) phosphate from (..gamma..-/sup 32/P)ATP to protein, the rate of loss of ATP from the reaction mixture is determined. The ATP remaining after the protein kinase reaction is assayed by ATP-dependent chemiluminescence of the firefly luciferin-luciferase system. Under conditions of the protein kinase reaction in which a readily measurable decrease in ATP concentration occurs, the logarithm of the concentration of ATP decreases in proportion to the cAMP concentration, i.e., the reaction can be described by the equation: (ATP) = (ATP)/sub 0/ e/sup -(cAMP)kt/. The assay based on this relationship can detect less than 1 pmol of cAMP. The levels of cAMP found with this assay after partial purification of the cAMP from rat tissue, algal cells, and the media in which the cells were grown agreed with measurements made by the cAMP binding-competition assay of Gilman, and the potein kinase stimulation assay based on transfer of (/sup 32/P) phosphate from (..gamma..-/sup 32/P)ATP to protein. All of the enzymes and chemicals required for the assay of cAMP by protein kinase catalyzed loss of ATP can be stored frozen for months, making the assay suitable for occasional use.

  18. Functional effects of a pathogenic mutation in Cereblon (CRBN) on the regulation of protein synthesis via the AMPK-mTOR cascade.

    Lee, Kwang Min; Yang, Seung-Joo; Choi, Ja-Hyun; Park, Chul-Seung

    2014-08-22

    Initially identified as a protein implicated in human mental deficit, cereblon (CRBN) was recently recognized as a negative regulator of adenosine monophosphate-activated protein kinase (AMPK) in vivo and in vitro. Here, we present results showing that CRBN can effectively regulate new protein synthesis through the mammalian target of rapamycin (mTOR) signaling pathway, a downstream target of AMPK. Whereas deficiency of Crbn repressed protein translation via activation of the AMPK-mTOR cascade in Crbn-knock-out mice, ectopic expression of the wild-type CRBN increased protein synthesis by inhibiting endogenous AMPK. Unlike the wild-type CRBN, a mutant CRBN found in human patients, which lacks the last 24 amino acids, failed to rescue mTOR-dependent repression of protein synthesis in Crbn-deficient mouse fibroblasts. These results provide the first evidence that Crbn can activate the protein synthesis machinery through the mTOR signaling pathway by inhibiting AMPK. In light of the fact that protein synthesis regulated by mTOR is essential for various forms of synaptic plasticity that underlie the cognitive functions of the brain, the results of this study suggest a plausible mechanism for CRBN involvement in higher brain function in humans, and they may help explain how a specific mutation in CRBN can affect the cognitive ability of patients.

  19. Apoptotic effects of extract from Cnidium monnieri (L.) Cusson by adenosine monosphosphate-activated protein kinase-independent pathway in HCT116 colon cancer cells.

    Lim, Eun Gyeong; Kim, Guen Tae; Lee, Se Hee; Kim, Sang-Yong; Kim, Young Min

    2016-06-01

    Colon cancer, a common malignancy, can occur due to poor eating habits and increasing age. Consequently, careful regulation of eating habits may serve as a possible method for preventing the occurrence or progression of colon cancer. Extracts of the fruit of Cnidium monnieri (L.) Cusson are well‑known as an effective herbal medicine for the treatment of pain in female genitalia and carbuncle. However, there have been no studies on the apoptotic effects of Cnidium monnieri (L.) Cusson (CME). Adenosine monophosphate‑activated protein kinase (AMPK), the major regulator of energy metabolism, is activated by metabolic stress, including hypoxia and glucose deprivation. Activation of AMPK inhibits cell proliferation and induces apoptosis through the inhibition of phosphorylated (p)‑Akt and control of B‑cell lymphoma 2 (Bcl‑2) family members. The pro‑apoptotic proteins Bcl‑2‑associated X protein (Bax) and Bcl‑2‑homologous antagonist killer (Bak), are activated by their translocation to mitochondria from the cytosol. Translocation of Bax/Bak induces outer membrane permeabilization and is likely to lead to apoptosis through cytochrome C release and caspase activity. In the present study, the apoptotic effects and influence on mitochondria‑mediated apoptotic proteins of CME in HCT116 cells were assessed. We hypothesized that CME may have an effect on the inhibition of p‑Akt in an AMPK‑independent pathway. The present study demonstrated that CME induced the release of LDH and apoptosis through its inhibition of p‑Akt to control Bcl‑2 and activate Bax and Bak. Co‑treatment with CME and AMPK inhibitors showed that CME‑induced apoptosis does not occurr through a AMPK‑dependent pathway. Therefore, the present study determined, for the first time, that CME induced apoptosis as a result of causing metabolic stresses due to directly regulation of the de‑phosphorylation of Akt, whereas it did not control the AMPK-dependent pathway in HCT116

  20. The Role of Adenosine Signaling in Headache: A Review

    Nathan T. Fried

    2017-03-01

    Full Text Available Migraine is the third most prevalent disease on the planet, yet our understanding of its mechanisms and pathophysiology is surprisingly incomplete. Recent studies have built upon decades of evidence that adenosine, a purine nucleoside that can act as a neuromodulator, is involved in pain transmission and sensitization. Clinical evidence and rodent studies have suggested that adenosine signaling also plays a critical role in migraine headache. This is further supported by the widespread use of caffeine, an adenosine receptor antagonist, in several headache treatments. In this review, we highlight evidence that supports the involvement of adenosine signaling in different forms of headache, headache triggers, and basic headache physiology. This evidence supports adenosine A2A receptors as a critical adenosine receptor subtype involved in headache pain. Adenosine A2A receptor signaling may contribute to headache via the modulation of intracellular Cyclic adenosine monophosphate (cAMP production or 5' AMP-activated protein kinase (AMPK activity in neurons and glia to affect glutamatergic synaptic transmission within the brainstem. This evidence supports the further study of adenosine signaling in headache and potentially illuminates it as a novel therapeutic target for migraine.

  1. Co-targeting Deoxyribonucleic Acid–Dependent Protein Kinase and Poly(Adenosine Diphosphate-Ribose) Polymerase-1 Promotes Accelerated Senescence of Irradiated Cancer Cells

    Azad, Arun, E-mail: arun.azad@bccancer.bc.ca [Division of Cancer Research, Peter MacCallum Cancer Centre, East Melbourne, Victoria (Australia); Department of Pathology, St. Vincent' s Hospital, University of Melbourne, Parkville, Victoria (Australia); Bukczynska, Patricia; Jackson, Susan [Division of Cancer Research, Peter MacCallum Cancer Centre, East Melbourne, Victoria (Australia); Haput, Ygal; Cullinane, Carleen [Division of Cancer Research, Peter MacCallum Cancer Centre, East Melbourne, Victoria (Australia); Sir Peter MacCallum Department of Oncology, University of Melbourne, Parkville, Victoria (Australia); McArthur, Grant A.; Solomon, Benjamin [Division of Cancer Research, Peter MacCallum Cancer Centre, East Melbourne, Victoria (Australia); Division of Cancer Medicine, Peter MacCallum Cancer Centre, East Melbourne, Victoria (Australia); Department of Medicine, St. Vincent' s Hospital, University of Melbourne, Parkville, Victoria (Australia); Sir Peter MacCallum Department of Oncology, University of Melbourne, Parkville, Victoria (Australia)

    2014-02-01

    Purpose: To examine the effects of combined blockade of DNA-dependent protein kinase (DNA-PK) and poly(adenosine diphosphate-ribose) polymerase-1 (PARP-1) on accelerated senescence in irradiated H460 and A549 non-small cell lung cancer cells. Methods and Materials: The effects of KU5788 and AG014699 (inhibitors of DNA-PK and PARP-1, respectively) on clonogenic survival, DNA double-strand breaks (DSBs), apoptosis, mitotic catastrophe, and accelerated senescence in irradiated cells were examined in vitro. For in vivo experiments, H460 xenografts established in athymic nude mice were treated with BEZ235 (a DNA-PK, ATM, and phosphatidylinositol 3-kinase/mammalian target of rapamycin inhibitor) and AG014699 to determine effects on proliferation, DNA DSBs, and accelerated senescence after radiation. Results: Compared with either inhibitor alone, combination treatment with KU57788 and AG014699 reduced postradiation clonogenic survival and significantly increased persistence of Gamma-H2AX (γH2AX) foci in irradiated H460 and A549 cells. Notably, these effects coincided with the induction of accelerated senescence in irradiated cells as reflected by positive β-galactosidase staining, G2-M cell-cycle arrest, enlarged and flattened cellular morphology, increased p21 expression, and senescence-associated cytokine secretion. In irradiated H460 xenografts, concurrent therapy with BEZ235 and AG014699 resulted in sustained Gamma-H2AX (γH2AX) staining and prominent β-galactosidase activity. Conclusion: Combined DNA-PK and PARP-1 blockade increased tumor cell radiosensitivity and enhanced the prosenescent properties of ionizing radiation in vitro and in vivo. These data provide a rationale for further preclinical and clinical testing of this therapeutic combination.

  2. The value of adenosine deaminase, interferon-gamma, and interferon-gamma induced protein of 10kD in the diagnosis of tuberculous pleuritis

    Ya-kun DONG

    2015-07-01

    Full Text Available Objective To explore the value of adenosine deaminase (ADA activity, interferon-gamma (IFN-γ and IFN-γ induced protein of 10kD (IP-10 levels in pleural effusion for the diagnosis of tuberculous pleuritis. Methods ADA activity, IFN-γ and IP-10 levels in pleural effusion were determined in sixty-three patients with tuberculous pleuritis and 50 patients with malignant pleural effusion. Results The mean levels of ADA, IFN-γ and IP-10 in the tuberculous pleural effusion were significantly higher than those in malignant pleural effusion (P<0.01. When 45U/L was regarded as cut off value for ADA, the sensitivity, specificity and diagnostic odds ratio in the diagnosis of tuberculous pleurisy were 71.4%, 94.0% and 39.17 respectively. When 138.5pg/ml was regarded as cut off value for IFN-γ in tuberculous pleural effusion, the sensitivity, specificity and diagnostic odds ratio were 93.7%, 82.0% and 67.19 respectively. When 9.21μg/ml was regarded as cut off value for IP-10 in tuberculous pleural effusion, the sensitivity, specificity and diagnostic odds ratio were 85.7%, 90.0% and 54.00 respectively. The combined determination of the three markers for the diagnosis of tuberculous pleurisy had a sensitivity of 95.2%, specificity of 96.0% and diagnostic odds ratio of 72.16. Conclusion The accuracy of diagnosis for tuberculous pleurisy can be improved by combined determination of ADA, IFN-γ and IP-10. DOI: 10.11855/j.issn.0577-7402.2015.06.07

  3. Modulation and metamodulation of synapses by adenosine.

    Ribeiro, J A; Sebastião, A M

    2010-06-01

    The presence of adenosine in all nervous system cells (neurones and glia) together with its intensive release following insults makes adenosine as a sort of 'regulator' of synaptic communication, leading to the homeostatic coordination of brain function. Besides the direct actions of adenosine on the neurosecretory mechanisms, to tune neurotransmitter release, adenosine receptors interact with other receptors as well as with transporters as part of its attempt to fine-tune synaptic transmission. This review will focus on examples of the different ways adenosine can use to modulate or metamodulate synapses, in other words, to trigger or brake the action of some neurotransmitters and neuromodulators, to cross-talk with other G protein-coupled receptors, with ionotropic receptors and with receptor kinases as well as with transporters. Most of these interactions occur through A2A receptors, which in spite of their low density in some brain areas, such as the hippocampus, may function as amplifiers of the signalling of other mediators at synapses.

  4. Adenosine and sleep

    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/sub 1/ receptors, /sup 3/H-L-PIA binding was measured. The Bmax values for /sup 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 /sup 3/H-L-PIA binding resulted from REM sleep deprivation and not from stress.

  5. Piceatannol Exerts Anti-Obesity Effects in C57BL/6 Mice through Modulating Adipogenic Proteins and Gut Microbiota

    Yen-Chen Tung

    2016-10-01

    Full Text Available Obesity is a global health concern. Piceatannol (Pic, an analog of resveratrol (Res, has many reported biological activities. In this study, we investigated the anti-obesity effect of Pic in a high-fat diet (HFD-induced obese animal model. The results showed that Pic significantly reduced mouse body weight in a dose-dependent manner without affecting food intake. Serum total cholesterol (TC, low-density lipoprotein (LDL, high-density lipoprotein (HDL levels, and blood glucose (GLU were significantly lowered in Pic-treated groups. Pic significantly decreased the weight of liver, spleen, perigonadal and retroperitoneal fat compared with the HFD group. Pic significantly reduced the adipocyte cell size of perigonadal fat and decreased the weight of liver. Pic-treated mice showed higher phosphorylated adenosine 5′-monophosphate-activated protein kinase (pAMPK and phosphorylated acetyl-CoA carboxylase (pACC protein levels and decreased protein levels of CCAAT/enhancer-binding protein C/EBPα, peroxisome proliferator-activated receptor PPARγ and fatty acid synthase (FAS, resulting in decreased lipid accumulation in adipocytes and the liver. Pic altered the composition of the gut microbiota by increasing Firmicutes and Lactobacillus and decreasing Bacteroidetes compared with the HFD group. Collectively, these results suggest that Pic may be a candidate for obesity treatment.

  6. Low-ω3 Fatty Acid and Soy Protein Attenuate Alcohol-Induced Fatty Liver and Injury by Regulating the Opposing Lipid Oxidation and Lipogenic Signaling Pathways

    Karina Reyes-Gordillo

    2016-01-01

    Full Text Available Chronic ethanol-induced downregulation of peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC1α and upregulation of peroxisome proliferator-activated receptor gamma coactivator 1-beta (PGC1β affect hepatic lipid oxidation and lipogenesis, respectively, leading to fatty liver injury. Low-ω3 fatty acid (Low-ω3FA that primarily regulates PGC1α and soy protein (SP that seems to have its major regulatory effect on PGC1β were evaluated for their protective effects against ethanol-induced hepatosteatosis in rats fed with Lieber-deCarli control or ethanol liquid diets with high or low ω3FA fish oil and soy protein. Low-ω3FA and SP opposed the actions of chronic ethanol by reducing serum and liver lipids with concomitant decreased fatty liver. They also prevented the downregulation of hepatic Sirtuin 1 (SIRT1 and PGC1α and their target fatty acid oxidation pathway genes and attenuated the upregulation of hepatic PGC1β and sterol regulatory element-binding protein 1c (SREBP1c and their target lipogenic pathway genes via the phosphorylation of 5′ adenosine monophosphate-activated protein kinase (AMPK. Thus, these two novel modulators attenuate ethanol-induced hepatosteatosis and consequent liver injury potentially by regulating the two opposing lipid oxidation and lipogenic pathways.

  7. Adenosine improves cardiomyocyte respiratory efficiency.

    Babsky, A M; Doliba, M M; Doliba, N M; Osbakken, M D

    1998-01-01

    The role of adenosine on the regulation of mitochondrial function has been studied. In order to evaluate this the following experiments were done in isolated rat cardiomyocites and mitochondria using polarographic techniques. Cardiomyocyte oxygen consumption (MVO2) and mitochondrial respiratory function (State 3 and State 4, respiratory control index, and ADP/O ratio) were evaluated after exposure to adenosine. Cardiomyocyte MVO2 was significantly lower in cells previously exposed to adenosine (10 microM, 15 min or 30 min cell incubation) than in cells not exposed to adenosine (control). Addition of dipyridamole (10 microM) or 8-(p-Sulfophenyl) theophylline (50 microM) to cardiomyocytes before adenosine incubation prevented the adenosine-induced changes in MVO2. Mitochondria obtained from isolated perfused beating heart previously perfused with adenosine (10 microM, 30 min heart perfusion) also resulted in significant increases in ADP/O and respiratory control index compared to matching control. Mitochondria isolated from cardiomyocytes previously exposed to adenosine (10 microM, 15 min or 30 min cell incubation) resulted in a significant increase in mitochondrial ADP/O ratio compared to control. Adenosine-induced decrease in cardiomyocyte MVO2 may be related to an increase in efficiency of mitochondrial oxidative phosphorylation, and more economical use of oxygen, which is necessary for survival under ischemic stress.

  8. Modulation of Cyclins, p53 and Mitogen-Activated Protein Kinases Signaling in Breast Cancer Cell Lines by 4-(3,4,5-Trimethoxyphenoxybenzoic Acid

    Kuan-Han Lee

    2014-01-01

    Full Text Available Despite the advances in cancer therapy and early detection, breast cancer remains a leading cause of cancer-related deaths among females worldwide. The aim of the current study was to investigate the antitumor activity of a novel compound, 4-(3,4,5-trimethoxyphenoxybenzoic acid (TMPBA and its mechanism of action, in breast cancer. Results indicated the relatively high sensitivity of human breast cancer cell-7 and MDA-468 cells towards TMPBA with IC50 values of 5.9 and 7.9 µM, respectively compared to hepatocarcinoma cell line Huh-7, hepatocarcinoma cell line HepG2, and cervical cancer cell line Hela cells. Mechanistically, TMPBA induced apoptotic cell death in MCF-7 cells as indicated by 4',6-diamidino-2-phenylindole (DAPI nuclear staining, cell cycle analysis and the activation of caspase-3. Western blot analysis revealed the ability of TMPBA to target pathways mediated by mitogen-activated protein (MAP kinases, 5' adenosine monophosphate-activated protein kinase (AMPK, and p53, of which the concerted action underlined its antitumor efficacy. In addition, TMPBA induced alteration of cyclin proteins’ expression and consequently modulated the cell cycle. Taken together, the current study underscores evidence that TMPBA induces apoptosis in breast cancer cells via the modulation of cyclins and p53 expression as well as the modulation of AMPK and mitogen-activated protein kinases (MAPK signaling. These findings support TMPBA’s clinical promise as a potential candidate for breast cancer therapy.

  9. D-Pinitol attenuates 7, 12 dimethylbenz [a] anthracene induced hazards through modulating protein bound carbohydrates, adenosine triphosphatases and lysosomal enzymes during experimental mammary carcinogenesis.

    Rengarajan, Thamaraiselvan; Nandakumar, Natarajan; Balasubramanian, Maruthaiveeran Periyasamy

    2012-01-01

    We have reported here that the ameliorative potentials of D-Pinitol during 7, 12-Dimethylbenz [a] anthracene induced experimental breast carcinogenesis. DMBA is a potent organ specific carcinogen which is widely employed to induce mammary carcinoma in rats. D-Pinitol a natural inositol has been reported to found in soybean with many biological functions. The female sprague dawley rats were subjected to carcinogen 7, 12-DMBA and the ameliorative potentials of dietary compound D-Pinitol was investigated with reference to cell surface glycoproteins, lysosomal enzymes and adenosine triphosphatases. Interestingly, administration of D-Pinitol was found to be significantly down regulated the breast tissue glycoproteins and lysosomal enzymes and in contrast the levels of adenosine triphosphatases were remarkably up regulated. Further, the biochemical changes were well reflected and evidenced in the histology of breast and liver tissues. Thus, it can be concluded from the present study that D-Pinitol efficiently attenuates the hazardous consequences of the environmental carcinogen 7,12-DMBA through modulating cell surface glycoproteins, membrane protective role both in lysosomal and ATPase compartment via its antioxidant nature which ultimately results in the findings of future innovative remedies for genotoxin mediated hazards.

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

    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

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

    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.

  12. Metformin directly inhibits ghrelin secretion through AMP-activated protein kinase in rat primary gastric cells.

    Gagnon, J; Sheppard, E; Anini, Y

    2013-03-01

    The antidiabetic drug Metformin causes weight loss in both diabetic and non-diabetic individuals. Metformin treatment is also associated with lower circulating levels of the orexigenic hormone ghrelin. To test whether Metformin directly affects ghrelin cells, rat primary stomach cells were treated with Metformin and the levels of ghrelin secretion, proghrelin gene expression and activation of adenosine monophosphate-activated protein kinase (AMPK) were examined. Metformin significantly reduced ghrelin secretion and proghrelin mRNA production and both these effects were blocked by co-incubation with the AMPK inhibitor compound C. Furthermore, the AMPK activator 5-amino-1-β-D-ribofuranosyl-imidazole-4-carboxamide (AICAR) significantly inhibited ghrelin secretion. Additionally, ghrelin cells were shown to express AMPK. Finally, Metformin treatment caused a significant increase in the level of phosphorylated (active) AMPK. Our results show that Metformin directly inhibits stomach ghrelin production and secretion through AMPK. This reduction in ghrelin secretion may be one of the key components in Metformin's mechanism of weight loss.

  13. Contraction induced secretion of VEGF from skeletal muscle cells is mediated by adenosine

    Høier, Birgitte; Olsen, Karina; Nyberg, Michael Permin

    2010-01-01

    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...... 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....

  14. Oral administration of amino acidic supplements improves protein and energy profiles in skeletal muscle of aged rats: elongation of functional performance and acceleration of mitochondrial recovery in adenosine triphosphate after exhaustive exertion.

    Chen Scarabelli, Carol; McCauley, Roy B; Yuan, Zhaokan; Di Rezze, Justin; Patel, David; Putt, Jeff; Raddino, Riccardo; Allebban, Zuhair; Abboud, John; Scarabelli, Gabriele M; Chilukuri, Karuna; Gardin, Julius; Saravolatz, Louis; Faggian, Giuseppe; Mazzucco, Alessandro; Scarabelli, Tiziano M

    2008-06-02

    Sarcopenia is an inevitable age-related degenerative process chiefly characterized by decreased synthesis of muscle proteins and impaired mitochondrial function, leading to progressive loss of muscle mass. Here, we sought to probe whether long-term administration of oral amino acids (AAs) can increase protein and adenosine triphosphate (ATP) content in the gastrocnemius muscle of aged rats, enhancing functional performance. To this end, 6- and 24-month-old male Fisher 344 rats were divided into 3 groups: group A (6-month-old rats) and group B (24-month-old rats) were used as adult and senescent control group, respectively, while group C (24-month-old rats) was used as senescent treated group and underwent 1-month oral treatment with a mixture of mainly essential AAs. Untreated senescent animals exhibited a 30% reduction in total and fractional protein content, as well as a 50% reduction in ATP content and production, compared with adult control rats (p supplementation with mixed AAs significantly improved protein and high-energy phosphate content, as well as the rate of mitochondrial ATP production, conforming their values to those of adult control animals (p energy substrates in the gastrocnemius muscle of treated aged rats paralleled a significant enhancement in functional performance assessed by swim test, with dramatic elongation of maximal exertion times compared with untreated senescent rats (p supplementation with oral AAs improved protein and energy profiles in the gastrocnemius of treated rats, enhancing functional performance and accelerating high-energy phosphate recovery after exhaustive exertion.

  15. Imaging Adenosine Triphosphate (ATP).

    Rajendran, Megha; Dane, Eric; Conley, Jason; Tantama, Mathew

    2016-08-01

    Adenosine triphosphate (ATP) is a universal mediator of metabolism and signaling across unicellular and multicellular species. There is a fundamental interdependence between the dynamics of ATP and the physiology that occurs inside and outside the cell. Characterizing and understanding ATP dynamics provide valuable mechanistic insight into processes that range from neurotransmission to the chemotaxis of immune cells. Therefore, we require the methodology to interrogate both temporal and spatial components of ATP dynamics from the subcellular to the organismal levels in live specimens. Over the last several decades, a number of molecular probes that are specific to ATP have been developed. These probes have been combined with imaging approaches, particularly optical microscopy, to enable qualitative and quantitative detection of this critical molecule. In this review, we survey current examples of technologies available for visualizing ATP in living cells, and identify areas where new tools and approaches are needed to expand our capabilities.

  16. The A3 adenosine receptor: history and perspectives.

    Borea, Pier Andrea; Varani, Katia; Vincenzi, Fabrizio; Baraldi, Pier Giovanni; Tabrizi, Mojgan Aghazadeh; Merighi, Stefania; Gessi, Stefania

    2015-01-01

    By general consensus, the omnipresent purine nucleoside adenosine is considered a major regulator of local tissue function, especially when energy supply fails to meet cellular energy demand. Adenosine mediation involves activation of a family of four G protein-coupled adenosine receptors (ARs): A(1), A(2)A, A(2)B, and A(3). The A(3) adenosine receptor (A(3)AR) is the only adenosine subtype to be overexpressed in inflammatory and cancer cells, thus making it a potential target for therapy. Originally isolated as an orphan receptor, A(3)AR presented a twofold nature under different pathophysiologic conditions: it appeared to be protective/harmful under ischemic conditions, pro/anti-inflammatory, and pro/antitumoral depending on the systems investigated. Until recently, the greatest and most intriguing challenge has been to understand whether, and in which cases, selective A(3) agonists or antagonists would be the best choice. Today, the choice has been made and A(3)AR agonists are now under clinical development for some disorders including rheumatoid arthritis, psoriasis, glaucoma, and hepatocellular carcinoma. More specifically, the interest and relevance of these new agents derives from clinical data demonstrating that A(3)AR agonists are both effective and safe. Thus, it will become apparent in the present review that purine scientists do seem to be getting closer to their goal: the incorporation of adenosine ligands into drugs with the ability to save lives and improve human health.

  17. [Effects of dopamine and adenosine on regulation of water-electrolyte exchange in Amoeba proteus].

    Bagrov, Ia Iu; Manusova, N B

    2014-01-01

    Dopamine and adenosine both regulate transport of sodium chloride in the renal tubules in mammals. We have studied the effect of dopamine and adenosine on spontaneous activity of contractile vacuole of Amoeba proteous. Both substances stimulated contractile vacuole. The effect of dopamine was suppressed by D2 receptor antagonist, haloperidol, but not by D1 antagonist, SCH 39166. Adenylate cyclase inhibitor, 2.5-dideoxyadenosine, suppressed the effect of dopamine, but not of adenosine. Inhibitor of protein kinase C, staurosporine, in contrast, blocked the effect of adenosine, but not dopamine. Notably, dopamine opposed effect of adenosine and vice versa. These results suggest that similar effects of dopamine and adenosine could be mediated by different intracellulare mechanisms.

  18. Some neural effects of adenosin.

    Haulică, I; Brănişteanu, D D; Petrescu, G H

    1978-01-01

    The possible neural effects of adenosine were investigated by using electrophysiological techniques at the level of some central and peripheral synapses. The evoked potentials in the somatosensorial cerebral cortex are influenced according to both the type of administration and the level of the electrical stimulation. While the local application does not induce significant alterations, the intrathalamic injections and the perfusion of the IIIrd cerebral ventricle do change the distribution of activated units at the level of different cortical layers especially during the peripheral stimulation. The frequency of spontaneous miniature discharges intracellularly recorded in the neuromuscular junction (mepp) is significantly depressed by adenosine. This effect is calcium- and dose-dependent. The end plate potentials (EPP) were also depressed. The statistical binomial analysis of the phenomenon indicated that adenosine induces a decrease if the presynaptic pool of the available transmitter. The data obtained demonstrate a presynaptic inhibitory action of adenosine beside its known vascular and metaholic effects.

  19. Supplementation of chitosan alleviates high-fat diet-enhanced lipogenesis in rats via adenosine monophosphate (AMP)-activated protein kinase activation and inhibition of lipogenesis-associated genes.

    Chiu, Chen-Yuan; Chan, Im-Lam; Yang, Tsung-Han; Liu, Shing-Hwa; Chiang, Meng-Tsan

    2015-03-25

    This study investigated the role of chitosan in lipogenesis in high-fat diet-induced obese rats. The lipogenesis-associated genes and their upstream regulatory proteins were explored. Diet supplementation of chitosan efficiently decreased the increased weights in body, livers, and adipose tissues in high-fat diet-fed rats. Chitosan supplementation significantly raised the lipolysis rate; attenuated the adipocyte hypertrophy, triglyceride accumulation, and lipoprotein lipase activity in epididymal adipose tissues; and decreased hepatic enzyme activities of lipid biosynthesis. Chitosan supplementation significantly activated adenosine monophosphate (AMP)-activated protein kinase (AMPK) phosphorylation and attenuated high-fat diet-induced protein expressions of lipogenic transcription factors (PPAR-γ and SREBP1c) in livers and adipose tissues. Moreover, chitosan supplementation significantly inhibited the expressions of downstream lipogenic genes (FAS, HMGCR, FATP1, and FABP4) in livers and adipose tissues of high-fat diet-fed rats. These results demonstrate for the first time that chitosan supplementation alleviates high-fat diet-enhanced lipogenesis in rats via AMPK activation and lipogenesis-associated gene inhibition.

  20. Green tea catechins enhance norepinephrine-induced lipolysis via a protein kinase A-dependent pathway in adipocytes.

    Chen, Shu; Osaki, Noriko; Shimotoyodome, Akira

    2015-05-22

    Green tea catechins have been shown to attenuate obesity in animals and humans. The catechins activate adenosine monophosphate-activated protein kinase (AMPK), and thereby increase fatty acid oxidation in liver and skeletal muscles. Green tea catechins have also been shown to reduce body fat in humans. However, the effect of the catechins on lipolysis in adipose tissue has not been fully understood. The aim of this study was to clarify the effect of green tea catechins on lipolysis in adipocytes and to elucidate the underlying mechanism. Differentiated mouse adipocyte cell line (3T3-L1) was stimulated with green tea catechins in the presence or absence of norepinephrine. Glycerol and free fatty acids in the media were measured. Phosphorylation of hormone-sensitive lipase (HSL) was determined by Western blotting, and the mRNA expression levels of HSL, adipose triglyceride lipase (ATGL), and perilipin were determined by quantitative RT-PCR. The cells were treated with inhibitors of protein kinase A (PKA), protein kinase C (PKC), protein kinase G (PKG), or mitogen-activated protein kinase (MAPK) to determine the responsible pathway. Treatment of 3T3-L1 adipocytes with green tea catechins increased the level of glycerol and free fatty acids released into the media in the presence, but not absence, of norepinephrine, and increased the level of phosphorylated HSL in the cells. The catechins also increased mRNA and protein levels of HSL and ATGL. PKA inhibitor (H89) attenuated the catechin-induced increase in glycerol release and HSL phosphorylation. The results demonstrate that green tea catechins enhance lipolysis in the presence of norepinephrine via a PKA-dependent pathway in 3T3-L1 adipocytes, providing a potential mechanism by which green tea catechins could reduce body fat.

  1. Regulatory enzymes of mitochondrial beta-oxidation as targets for treatment of the metabolic syndrome

    Schreurs, M.; Kuipers, F.; van der Leij, F. R.

    2010-01-01

    P>Insulin sensitizers like metformin generally act through pathways triggered by adenosine monophosphate-activated protein kinase. Carnitine palmitoyltransferase 1 (CPT1) controls mitochondrial beta-oxidation and is inhibited by malonyl-CoA, the product of acetyl-CoA carboxylase (ACC). The adenosine

  2. In Vivo Phosphoproteomics Analysis Reveals the Cardiac Targets of β-Adrenergic Receptor Signaling

    Lundby, Alicia; Andersen, Martin N; Steffensen, Annette B;

    2013-01-01

    -X-X-pS/T), and integrative analysis of sequence motifs and interaction networks suggested that the kinases AMPK (adenosine 5'-monophosphate-activated protein kinase), Akt, and mTOR (mammalian target of rapamycin) mediate βAR signaling, in addition to the well-established pathways mediated by PKA (cyclic adenosine...

  3. Two chalcones, 4-hydroxyderricin and xanthoangelol, stimulate GLUT4-dependent glucose uptake through the LKB1/AMP-activated protein kinase signaling pathway in 3T3-L1 adipocytes.

    Ohta, Mitsuhiro; Fujinami, Aya; Kobayashi, Norihiro; Amano, Akiko; Ishigami, Akihito; Tokuda, Harukuni; Suzuki, Nobutaka; Ito, Fumitake; Mori, Taisuke; Sawada, Morio; Iwasa, Koichi; Kitawaki, Jo; Ohnishi, Katsunori; Tsujikawa, Muneo; Obayashi, Hiroshi

    2015-07-01

    4-Hydroxyderricin (4HD) and xanthoangelol (XAG) are major components of n-hexane/ethyl acetate (5:1) extract of the yellow-colored stem juice of Angelica keiskei. 4-Hydroxyderricin and XAG have been reported to increase glucose transporter 4 (GLUT4)-dependent glucose uptake in 3T3-L1 adipocytes, but the detailed mechanism of this phenomenon remains unknown. This present study was aimed at clarifying the detailed mechanism by which 4HD and XAG increase GLUT4-dependent glucose uptake in 3T3-L1 adipocytes. Both 4HD and XAG increased glucose uptake and GLUT4 translocation to the plasma membrane. 4-Hydroxyderricin and XAG also stimulated the phosphorylation of 5' adenosine monophosphate-activated protein kinase (AMPK) and its downstream target acetyl-CoA carboxylase. In addition, phosphorylation of liver kinase B1 (LKB1), which acts upstream of AMPK, was also increased by 4HD and XAG treatment. Small interfering RNA knockdown of LKB1 attenuated 4HD- and XAG-stimulated AMPK phosphorylation and suppressed glucose uptake. These findings demonstrate that 4HD and XAG can increase GLUT4-dependent glucose uptake through the LKB1/AMPK signaling pathway in 3T3-L1 adipocytes.

  4. Adenosine Inhibits the Excitatory Synaptic Inputs to Basal Forebrain Cholinergic, GABAergic and Parvalbumin Neurons in mice

    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

  5. The Rickettsia prowazekii invasion gene homolog (invA) encodes a Nudix hydrolase active on adenosine (5')-pentaphospho-(5')-adenosine.

    Gaywee, Jariyanart; Xu, WenLian; Radulovic, Suzana; Bessman, Maurice J; Azad, Abdu F

    2002-03-01

    The genomic sequence of Rickettsia prowazekii, the obligate intracellular bacterium responsible for epidemic typhus, reveals an uncharacterized invasion gene homolog (invA). The deduced protein of 18,752 Da contains a Nudix signature, the specific motif found in the Nudix hydrolase family. To characterize the function of InvA, the gene was cloned and overexpressed in Escherichia coli. The expressed protein was purified to near homogeneity and subsequently tested for its enzymatic activity against a series of nucleoside diphosphate derivatives. The purified InvA exhibits hydrolytic activity toward dinucleoside oligophosphates (Np(n)N; n > or = 5), a group of cellular signaling molecules. At optimal pH 8.5, the enzyme actively degrades adenosine (5')-pentaphospho-(5')-adenosine into ATP and ADP with a K(m) of 0.1 mM and k(cat) of 1.9 s(-1). Guanosine (5')-pentaphospho-(5')-guanosine and adenosine-(5')-hexaphospho (5')-adenosine are also substrates. Similar to other Nudix hydrolases, InvA requires a divalent metal cation, Mg(2+) or Zn(2+), for optimal activity. These data suggest that the rickettsial invasion protein likely plays a role in controlling the concentration of stress-induced dinucleoside oligophosphates following bacterial invasion.

  6. Adenosine Receptors: Expression, Function and Regulation

    Sandeep Sheth

    2014-01-01

    Full Text Available Adenosine receptors (ARs comprise a group of G protein-coupled receptors (GPCR which mediate the physiological actions of adenosine. To date, four AR subtypes have been cloned and identified in different tissues. These receptors have distinct localization, signal transduction pathways and different means of regulation upon exposure to agonists. This review will describe the biochemical characteristics and signaling cascade associated with each receptor and provide insight into how these receptors are regulated in response to agonists. A key property of some of these receptors is their ability to serve as sensors of cellular oxidative stress, which is transmitted by transcription factors, such as nuclear factor (NF-κB, to regulate the expression of ARs. Recent observations of oligomerization of these receptors into homo- and heterodimers will be discussed. In addition, the importance of these receptors in the regulation of normal and pathological processes such as sleep, the development of cancers and in protection against hearing loss will be examined.

  7. Functional Characterization of Cyclic Adenosine Monphosphate (cAMP)Recptor Protein Gene (crp) from Erwinia amylovora%梨火疫菌(Erwinia amylovora)环腺苷酸受体蛋白基因(crp)的功能分析

    刘倩倩; 于洋洋; 宋俊贤; 胡白石; 范加勤; 刘凤权

    2010-01-01

    梨火疫菌(Erwinia amylovora)可引起梨、苹果等蔷薇科(Rosaceae)植物的火疫病.在菊欧文氏菌(Erwinia chrysanthemi)中,由crp基因编码的环腺苷酸受体蛋白(cyclic adenosine monphosphate(cAMP)receptor protein,CRP)对果胶酶基因的表达调控和菌株致病性起着重要的作用.本研究首次鉴定并克隆出梨火疫菌中的crp同源基因,命名为Eacrp,并通过同源重组的方法,构建了梨火疫菌的crp基因突变体Ea△crp以及互补子,进行了致病性、过敏性反应、胞外多糖、鞭毛运动等一系列相关表型的鉴定.结果表明,crp基因影响着梨火疫菌的致病性、胞外多糖、游动性、生长情况等多种生物学特性,然而,Ea△crp仍能引起烟草过敏性反应,并且在过氧化氢敏感度以及沉降性、生物膜和AI-2信号分子的生成方面与野生型菌株相比差异明显.本研究结果说明,梨火疫菌crp基因对病菌的胞外多糖分泌、生长、游动性以及致病性方面具有关键作用.

  8. Role of adenosine A2b receptor overexpression in tumor progression.

    Sepúlveda, Cesar; Palomo, Iván; Fuentes, Eduardo

    2016-12-01

    The adenosine A2b receptor is a G-protein coupled receptor. Its activation occurs with high extracellular adenosine concentration, for example in inflammation or hypoxia. These conditions are generated in the tumor environment. Studies show that A2b receptor is overexpressed in various tumor lines and biopsies from patients with different cancers. This suggests that A2b receptor can be used by tumor cells to promote progression. Thus A2b participates in different events, such as angiogenesis and metastasis, besides exerting immunomodulatory effects that protect tumor cells. Therefore, adenosine A2b receptor appears as an interesting therapeutic target for cancer treatment.

  9. Ribosome-inactivating lectins with polynucleotide:adenosine glycosidase activity.

    Battelli, M G; Barbieri, L; Bolognesi, A; Buonamici, L; Valbonesi, P; Polito, L; Van Damme, E J; Peumans, W J; Stirpe, F

    1997-05-26

    Lectins from Aegopodium podagraria (APA), Bryonia dioica (BDA), Galanthus nivalis (GNA), Iris hybrid (IRA) and Sambucus nigra (SNAI), and a new lectin-related protein from Sambucus nigra (SNLRP) were studied to ascertain whether they had the properties of ribosome-inactivating proteins (RIP). IRA and SNLRP inhibited protein synthesis by a cell-free system and, at much higher concentrations, by cells and had polynucleotide:adenosine glycosidase activity, thus behaving like non-toxic type 2 (two chain) RIP. APA and SNAI had much less activity, and BDA and GNA did not inhibit protein synthesis.

  10. Prognostic value of coexistence of abnormal expression of micro-RNA-200b and cyclic adenosine monophosphate-responsive element-binding protein 1 in human astrocytoma.

    Zhang, Jun-qing; Yao, Qing-he; Kuang, Yong-qin; Ma, Yuan; Yang, Li-bin; Huang, Hai-dong; Cheng, Jing-ming; Yang, Tao; Liu, En-yu; Liang, Liang; Fan, Ke-xia; Zhao, Kai; Xia, Xun; Gu, Jian-wen

    2014-10-01

    Our aim was to investigate the expression of micro-RNA-200b (miR-200b) and cAMP-responsive element-binding protein 1 (CREB-1) in astrocytoma and its efficacy for predicting outcome. Both miR-200b and CREB-1 messenger RNA expression was measured in 122 astrocytomas and 30 nonneoplastic brain specimens by quantitative real-time polymerase chain reaction. Expression of miR-200b was significantly lower in astrocytoma than in nonneoplastic brain (P RNA expression was significantly elevated in the tumors (P < .001). Both miR-200b down-regulation and CREB-1 up-regulation were significantly associated with advanced pathologic grade (P = .002 and P = .006, respectively). Low miR-200b expression correlated negatively with Karnofsky performance score (P = .03), and high CREB-1 expression correlated positively with mean tumor diameter (P = .03). By Kaplan-Meier analysis, low miR-200b, high CREB-1, and coexistence of abnormal miR-200b and CREB-1 expression (low miR-200b/high CREB-1) were predictive of shorter progression-free survival and overall survival in both grade III and grade IV astrocytoma. By multivariate analysis, only low miR-200b/high CREB-1 expression was an independent prognostic factor for poor prognosis in astrocytoma of advanced grade. Both miR-200b and CREB-1 may play important cooperative roles in the progression of human astrocytoma. The efficacy of miR-200b and CREB-1 together as a predictor of prognosis in astrocytoma patients is shown for the first time.

  11. Parathyroid hormone induces transcription of collagenase in rat osteoblastic cells by a mechanism using cyclic adenosine 3',5'-monophosphate and requiring protein synthesis

    Scott, D. K.; Brakenhoff, K. D.; Clohisy, J. C.; Quinn, C. O.; Partridge, N. C.

    1992-01-01

    Collagenase is synthesized and secreted by rat osteoblastic cells in response to PTH. We have previously demonstrated that this effect involves a substantial increase in collagenase mRNA via transcription. Northern blots and nuclear run-on assays were performed to further investigate the induction of collagenase by PTH in the rat osteoblastic cell line UMR 106-01. Detectable amounts of collagenase mRNA were not apparent until 2 h of PTH treatment, showed the greatest abundance at 4 h, and declined to approximately 30% of maximum by 8 h. The changes in the rate of transcription of the collagenase gene in response to PTH paralleled and preceded the changes in the steady state mRNA levels. After an initial lag period of about 1 h, collagenase transcription rates increased from very low levels to a maximal response at 2 h, returning to about 50% of maximum by 10 h. The increased transcriptional rate of the collagenase gene was found to be dependent on the concentration of PTH, with a half-maximal response at approximately 7 x 10(-10) M rat PTH-(1-34) and a maximal effect with a dose of 10(-8) M. The PTH-mediated induction of collagenase transcriptional activity was completely abolished by cycloheximide, while transcription of the beta-actin gene was unaffected by the translation inhibitor. These data suggest that a protein factor(s) is required for PTH-mediated transcriptional induction of collagenase. Since PTH increases intracellular levels of several potential second messengers, agents that mimic these substances were employed to determine which signal transduction pathway is predominant in the PTH-mediated stimulation of collagenase transcription.(ABSTRACT TRUNCATED AT 250 WORDS).

  12. AMP-activated protein kinase inhibits TGF-β-induced fibrogenic responses of hepatic stellate cells by targeting transcriptional coactivator p300.

    Lim, Joong-Yeon; Oh, Min-A; Kim, Won Ho; Sohn, Hee-Young; Park, Sang Ick

    2012-03-01

    Liver fibrosis is a common consequence of various chronic liver injuries, including virus infection and ethanol. Activated hepatic stellate cells (HSCs) contribute to liver fibrosis through the accumulation of extracellular matrix proteins, including type I alpha collagen (COL1A). The activation of adenosine monophosphate-activated protein kinase (AMPK) modulates HSCs activation, but its underlying mechanism remains unclear. Here, we report that AMPK inhibits transforming growth factor (TGF)-β-induced fibrogenic property of HSCs by regulating transcriptional coactivator p300. We treated human (LX-2) and rat (CFSC-2G) HSC lines with TGF-β to induce fibrogenic activation of HSCs. Pharmacological activation of AMPK by treatment with 5-aminoimidazole-4-carboxamide-1-beta-4-ribofuranoside (AICAR), metformin, or adiponectin lowered TGF-β-induced expression of COL1A and myofibroblast marker alpha-smooth muscle actin (α-SMA). Transient transduction of constitutively active AMPKα (caAMPKα) was sufficient to attenuate COL1A and α-SMA expression, whereas an AMPK inhibitor considerably abrogated the inhibitory effect of AICAR on fibrogenic gene expression. Although AMPK significantly suppressed Smad-dependent transcription, it did not affect TGF-β-stimulated phosphorylation, nuclear localization, or DNA-binding activity of Smad2/3. AICAR rather attenuated TGF-β-induced Smad3 interaction with transcriptional coactivator p300 accompanying with reduction of Smad3 acetylation. Moreover, AICAR induced not only physical interaction between AMPK and p300 but also proteasomal degradation of p300 protein. Our data provide substantial evidence that AMPK could be a novel therapeutic target for treatment of liver fibrosis, by demonstrating the underlying mechanism of AMPK-induced antifibrotic function in HSCs.

  13. Adenosine, Energy Metabolism, and Sleep

    Tarja Porkka-Heiskanen

    2003-01-01

    Full Text Available While the exact function of sleep remains unknown, it is evident that sleep was developed early in phylogenesis and represents an ancient and vital strategy for survival. Several pieces of evidence suggest that the function of sleep is associated with energy metabolism, saving of energy, and replenishment of energy stores. Prolonged wakefulness induces signs of energy depletion in the brain, while experimentally induced, local energy depletion induces increase in sleep, similarly as would a period of prolonged wakefulness. The key molecule in the induction of sleep appears to be adenosine, which induces sleep locally in the basal forebrain.

  14. Isoform-specific regulation of the Na+-K+ pump by adenosine in guinea pig ventricular myocytes

    Zhe ZHANG; Hui-cai GUO; Li-nan ZHANG; Yong-li WANG

    2009-01-01

    Aim: The present study investigated the effect of adenosine on Na+-K+ pumps in acutely isolated guinea pig (C, avia sp.) ven-tricular myocytes.Methods: The whole-cell, patch-damp technique was used to record the Na+-K+ pump current (Ip) in acutely isolated guinea pig ventricular myocytes.Results: Adenosine inhibited the high DHO-affinity pump current (Ih) in a concentration-dependent manner, which was blocked by the selective adenosine A1 receptor antagonist DPCPX and the general protein kinase C (PKC) antagonists stau-rosporine, GF 109203X or the specific δ isoform antagonist rottlerin. In addition, the inhibitory action of adenosine was mimicked by a selective A1 receptor agonist CCPA and a specific activator peptide of PKC-δ, PP114. In contrast, the selec-tive A2A receptor agonist CGS21680 and A3 receptor agonist Cl-IB-MECA did not affect lb. Application of the selective A2A receptor antagonist SCH58261 and A3 receptor antagonist MRS1191 also failed to block the effect of adenosine. Further-more, H89, a selective protein kinase A (PKA) antagonist, did not exert any effect on adenosine-induced Ih inhibition.Conclusion: The present study provides the electrophysiological evidence that adenosine can induce significant inhibition of Ih via adenosine A1 receptors and the PKC-δ isoform.

  15. Separation of effects of adenosine on energy metabolism from those on cyclic AMP in rat thymic lymphocytes

    Nordeen, S.K.; Young, D.A.

    1977-08-10

    In rat thymic lymphocytes incubated for 2 h without exogenous energy-providing substrate, adenosine may be substituted for glucose as a means of maximally restoring energy metabolism and those cellular functions whose rates are sensitive to small changes in the energy balance, such as protein synthesis and uridine utilization for RNA synthesis. Since effects of adenosine in thymocytes and other cells have frequently been attributed to changes in cyclic AMP, this report investigates its possible involvement in these glucose-like restorative actions of adenosine. Although the same range of doses of adenosine effective at raising cyclic AMP also elicit roughly parallel stimulations of protein synthesis and uridine utilization, further results dissociate the restorative actions from those on cyclic AMP. (a) Other purine nucleosides mimic the glucose-like actions of adenosine without increasing cyclic AMP; (b) conversely, prostaglandin E/sub 1/ mimics the cyclic AMP response without restoring energy metabolism or energy-dependent functions; and (c) potentiation of the cyclic AMP response, either by inhibiting phosphodiesterase or adenosine deaminase, does not enhance the restorative response to a range of doses of adenosine. Finally, cyclic AMP-mediated glycogenolysis cannot account for the glucose-like effects since addition of adenosine increases, not decreases, levels of glycogen.

  16. Hindbrain lactate regulates preoptic gonadotropin-releasing hormone (GnRH) neuron GnRH-I protein but not AMPK responses to hypoglycemia in the steroid-primed ovariectomized female rat.

    Shrestha, P K; Briski, K P

    2015-07-09

    Steroid positive-feedback activation of the gonadotropin-releasing hormone (GnRH)-pituitary luteinizing hormone (LH) neuroendocrine axis propagates the pre ovulatory LH surge, a crucial component of female reproduction. Our work shows that this key event is restrained by inhibitory metabolic input from hindbrain A2 noradrenergic neurons. GnRH neurons express the ultra-sensitive energy sensor adenosine 5'-monophosphate-activated protein kinase (AMPK); here, we investigated the hypothesis that GnRH nerve cell AMPK and peptide neurotransmitter responses to insulin-induced hypoglycemia are controlled by hindbrain lack of the oxidizable glycolytic end-product L-lactate. Data show that hypoglycemic inhibition of LH release in steroid-primed ovariectomized female rats was reversed by coincident caudal hindbrain lactate infusion. Western blot analyses of laser-microdissected A2 neurons demonstrate hypoglycemic augmentation [Fos, estrogen receptor-beta (ER-β), phosphoAMPK (pAMPK)] and inhibition (dopamine-beta-hydroxylase, GLUT3, MCT2) of protein expression in these cells, responses that were normalized by insulin plus lactate treatment. Hypoglycemia diminished rostral preoptic GnRH nerve cell GnRH-I protein and pAMPK content; the former, but not the latter response was reversed by lactate. Results implicate caudal hindbrain lactoprivic signaling in hypoglycemia-induced suppression of the LH surge, demonstrating that lactate repletion of that site reverses decrements in A2 catecholamine biosynthetic enzyme and GnRH neuropeptide precursor protein expression. Lack of effect of lactate on hypoglycemic patterns of GnRH AMPK activity suggests that this sensor is uninvolved in metabolic-inhibition of positive-feedback-stimulated hypophysiotropic signaling to pituitary gonadotropes.

  17. Characterization of the effects of metformin on porcine oocyte meiosis and on AMP-activated protein kinase activation in oocytes and cumulus cells.

    Bilodeau-Goeseels, Sylvie; Magyara, Nora; Collignon, Coralie

    2014-05-01

    The adenosine monophosphate-activated protein kinase (AMPK) activators 5-aminoimidazole-4-carboxamide 1-β-d-ribofuranoside (AICAR) and metformin (MET) inhibit resumption of meiosis in porcine cumulus-enclosed oocytes. The objective of this study was to characterize the inhibitory effect of MET on porcine oocyte meiosis by: (1) determining the effects of an AMPK inhibitor and of inhibitors of signalling pathways involved in MET-induced AMPK activation in other cell types on MET-mediated meiotic arrest in porcine cumulus-enclosed oocytes; (2) determining whether MET and AICAR treatments lead to increased activation of porcine oocyte and/or cumulus cell AMPK as measured by phosphorylation of its substrate acetyl-CoA carboxylase; and (3) determining the effects of inhibition of the AMPK kinase, Ca2+/calmodulin-dependent protein kinase kinase (CaMKK), and Ca2+ chelation on oocyte meiotic maturation and AMPK activation in porcine oocytes and cumulus cells. The AMPK inhibitor compound C (CC; 1 μM) did not reverse the inhibitory effect of AICAR (1 mM) and MET (2 mM) on porcine oocyte meiosis. Additionally, CC had a significant inhibitory effect on its own. eNOS, c-Src and PI-3 kinase pathway inhibitors did not reverse the effect of metformin on porcine oocyte meiosis. The level of acetyl-CoA carboxylase (ACC) phosphorylation in oocytes and cumulus cells did not change in response to culture in the presence of MET, AICAR, CC, the CaMKK inhibitor STO-609 or the Ca2+ chelator BAPTA-AM for 3 h, but STO-609 increased the percentage of porcine cumulus-enclosed oocytes (CEO) that remained at the germinal vesicle (GV) stage after 24 h of culture. These results indicate that the inhibitory effect of MET and AICAR on porcine oocyte meiosis was probably not mediated through activation of AMPK.

  18. Homeostatic control of synaptic activity by endogenous adenosine is mediated by adenosine kinase.

    Diógenes, Maria José; Neves-Tomé, Raquel; Fucile, Sergio; Martinello, Katiuscia; Scianni, Maria; Theofilas, Panos; Lopatár, Jan; Ribeiro, Joaquim A; Maggi, Laura; Frenguelli, Bruno G; Limatola, Cristina; Boison, Detlev; Sebastião, Ana M

    2014-01-01

    Extracellular adenosine, a key regulator of neuronal excitability, is metabolized by astrocyte-based enzyme adenosine kinase (ADK). We hypothesized that ADK might be an upstream regulator of adenosine-based homeostatic brain functions by simultaneously affecting several downstream pathways. We therefore studied the relationship between ADK expression, levels of extracellular adenosine, synaptic transmission, intrinsic excitability, and brain-derived neurotrophic factor (BDNF)-dependent synaptic actions in transgenic mice underexpressing or overexpressing ADK. We demonstrate that ADK: 1) Critically influences the basal tone of adenosine, evaluated by microelectrode adenosine biosensors, and its release following stimulation; 2) determines the degree of tonic adenosine-dependent synaptic inhibition, which correlates with differential plasticity at hippocampal synapses with low release probability; 3) modulates the age-dependent effects of BDNF on hippocampal synaptic transmission, an action dependent upon co-activation of adenosine A2A receptors; and 4) influences GABAA receptor-mediated currents in CA3 pyramidal neurons. We conclude that ADK provides important upstream regulation of adenosine-based homeostatic function of the brain and that this mechanism is necessary and permissive to synaptic actions of adenosine acting on multiple pathways. These mechanistic studies support previous therapeutic studies and implicate ADK as a promising therapeutic target for upstream control of multiple neuronal signaling pathways crucial for a variety of neurological disorders.

  19. Response of AMP-activated protein kinase and energy metabolism to acute nitrite exposure in the Nile tilapia Oreochromis niloticus.

    Xu, Zhixin; Li, Erchao; Xu, Chang; Gan, Lei; Qin, Jian G; Chen, Liqiao

    2016-08-01

    Adenosine monophosphate-activated protein kinase (AMPK) is a prevalent mammalian energy metabolism sensor, but little is known about its role as an energy sensor in fish experiencing stress. We aimed to study AMPK in Oreochromis niloticus on both the molecular and the physical level. We found that the cDNAs encoding the AMPKα1 and AMPKα2 variants of the O. niloticus catalytic α subunit were 1753bp and 2563 bp long and encoded 571 and 557 amino acids, respectively. Both the AMPKα1 and the AMPKα2 isoform possess structural features similar to mammalian AMPKα, including a phosphorylation site at Thr172 in the N-terminus, and exhibit high homology with other fish and vertebrate AMPKα sequences (81.3%-98.1%). mRNA encoding the AMPKα isoforms was widely expressed in various tissues with distinctive patterns. AMPKα1 and AMPKα2 were primarily expressed in the intestines and brain, respectively. Under acute nitrite challenge, the mRNA encoding the AMPKα isoforms, as well as AMPK activity, changed over time. Its recovery period in freshwater, combined with the fact that it is highly conserved, suggests that fish AMPK, like its mammalian orthologues, acts as an energy metabolism sensor. Furthermore, subsequent decreases in AMPK mRNA levels and activity suggested that its action was transient but efficient. Physically, glucose, lactic acid and TGs in plasma, as well as energy materials in the hepatopancreas and muscle, were significantly altered over time, indicating changes in energy metabolism during the experimental period. These data have enabled us to characterize energy utilization in O. niloticus and further illustrate the role of fish AMPK as an energy sensor. This study provides new insight into energy metabolism and sensing by AMPK in teleost and necessitates further study of the multiple physiologic roles of AMPK in fish.

  20. Cyclic adenosine 3'-5'-monophosphate (cAMP) exerts proliferative and anti-proliferative effects in pituitary cells of different types by activating both cAMP-dependent protein kinase A (PKA) and exchange proteins directly activated by cAMP (Epac).

    Vitali, E; Peverelli, E; Giardino, E; Locatelli, M; Lasio, G B; Beck-Peccoz, P; Spada, A; Lania, A G; Mantovani, G

    2014-03-05

    In the pituitary the activation of cyclic adenosine 3'-5'-monophosphate (cAMP) dependent pathways generates proliferative signals in somatotrophs, whereas in pituitary cells of other lineages its effect remains uncertain. Moreover, the specific role of the two main cAMP effectors, protein kinase A (PKA) and exchange proteins directly activated by cAMP (Epac), has not been defined. Aim of this study was to investigate the effect of cAMP on pituitary adenomatous cells proliferation and to identify PKA and Epac differential involvement. We found that cAMP increased DNA synthesis and cyclin D1 expression in somatotropinomas, whereas it reduced both parameters in prolactinomas and nonfunctioning adenomas, these effects being replicated in corresponding cell lines. Moreover, the divergent cAMP effects were mimicked by Epac and PKA analogs, which activated Rap1 and CREB, respectively. In conclusion, we demonstrated that cAMP exerted opposite effects on different pituitary cell types proliferation, these effects being mediated by both Epac and PKA.

  1. Repeated administration of adenosine increases its cardiovascular effects in rats.

    Vidrio, H; García-Márquez, F; Magos, G A

    1987-01-20

    Hypotensive and negative chronotropic responses to adenosine in anesthetized rats increased after previous administration of the nucleoside. Bradycardia after adenosine in the isolated perfused rat heart was also potentiated after repeated administration at short intervals. This self-potentiation could be due to extracellular accumulation of adenosine and persistent stimulation of receptors caused by saturation or inhibition of cellular uptake of adenosine.

  2. Mast cell adenosine receptors function: a focus on the A3 adenosine receptor and inflammation

    Noam eRudich

    2012-06-01

    Full Text Available Adenosine is a metabolite, which has long been implicated in a variety of inflammatory processes. Inhaled adenosine provokes bronchoconstriction in asthmatics or chronic obstructive pulmonary disease (COPD patients, but not in non-asthmatics. This hyper responsiveness to adenosine appears to be mediated by mast cell activation. These observations have marked the receptor that mediates the bronchoconstrictor effect of adenosine on mast cells, as an attractive drug candidate. Four subtypes (A1, A2a, A2b and A3 of adenosine receptors have been cloned and shown to display distinct tissue distributions and functions. Animal models have firmly established the ultimate role of the A3 adenosine receptor (A3R in mediating hyper responsiveness to adenosine in mast cells, although the influence of the A2b adenosine receptor was confirmed as well. In contrast, studies of the A3R in humans have been controversial. In this review, we summarize data on the role of different adenosine receptors in mast cell regulation of inflammation and pathology, with a focus on the common and distinct functions of the A3R in rodent and human mast cells. The relevance of mouse studies to the human is discussed.

  3. [Adenosine deaminase in experimental trypanosomiasis: future implications].

    Pérez-Aguilar, Mary Carmen; Rondón-Mercado, Rocío

    2015-09-01

    The adenosine deaminase represents a control point in the regulation of extracellular adenosine levels, thus playing a critical role in the modulation of purinergic responses to certain pathophysiological events. Several studies have shown that serum and plasma enzyme levels are elevated in some diseases caused by microorganisms, which may represent a compensatory mechanism due to the elevated levels of adenosine and the release of inflammatory mediators. Recent research indicates that adenosine deaminase activity decreases and affects hematological parameters of infected animals with Trypanosoma evansi, so that such alterations could have implications in the pathogenesis of the disease. In addition, the enzyme has been detected in this parasite; allowing the inference that it could be associated with the vital functions of the same, similar to what occurs in mammals. This knowledge may be useful in the association of chemotherapy with specific inhibitors of the enzyme in future studies.

  4. Profiling hepatic microRNAs in zebrafish: fluoxetine exposure mimics a fasting response that targets AMP-activated protein kinase (AMPK.

    Paul M Craig

    Full Text Available This study examined the similarities in microRNA profiles between fasted and fluoxetine (FLX exposed zebrafish and downstream target transcripts and biological pathways. Using a custom designed microarray targeting 270 zebrafish miRNAs, we identified 9 differentially expressed miRNAs targeting transcripts in biological pathways associated with anabolic metabolism, such as adipogenesis, cholesterol biosynthesis, triacylglycerol synthesis, and insulin signaling. Exposure of female zebrafish to 540 ng/L FLX, an environmentally relevant concentration and a known metabolic repressor, increased specific miRNAs indicating greater inhibition of these pathways in spite of continued feeding. Further examination revealed two specific miRNAs, dre-let-7d and dre-miR-140-5p, were predicted in silico to bind to a primary regulator of metabolism, adenosine monophosphate-activated protein kinase (AMPK, and more specifically the two isoforms of the catalytic subunit, AMPKα1 and α2, respectively. Real-time analysis of the relative transcript abundance of the α1 and α2 mRNAs indicated a significant inverse relationship between specific miRNA and target transcript. This suggests that AMPK-related pathways may be compromised during FLX exposure as a result of increased miRNA abundance. The mechanism by which FLX regulates miRNA abundance is unknown but may be direct at the liver. The serotonin transporter, slc6a4, is the target of FLX and other selective serotonin reuptake inhibitors (SSRI and it was found to be expressed in the liver, although treatment did not alter expression of this transporter. Exposure to FLX disrupts key hepatic metabolic pathways, which may be indicative of reduced overall fitness and these effects may be linked to specific miRNA abundance. This has important implications for the heath of fish because concentrations of SSRIs in aquatic ecosystems are continually increasing.

  5. Caffeine and contraction synergistically stimulate 5'-AMP-activated protein kinase and insulin-independent glucose transport in rat skeletal muscle.

    Tsuda, Satoshi; Egawa, Tatsuro; Kitani, Kazuto; Oshima, Rieko; Ma, Xiao; Hayashi, Tatsuya

    2015-10-01

    5'-Adenosine monophosphate-activated protein kinase (AMPK) has been identified as a key mediator of contraction-stimulated insulin-independent glucose transport in skeletal muscle. Caffeine acutely stimulates AMPK in resting skeletal muscle, but it is unknown whether caffeine affects AMPK in contracting muscle. Isolated rat epitrochlearis muscle was preincubated and then incubated in the absence or presence of 3 mmol/L caffeine for 30 or 120 min. Electrical stimulation (ES) was used to evoke tetanic contractions during the last 10 min of the incubation period. The combination of caffeine plus contraction had additive effects on AMPKα Thr(172) phosphorylation, α-isoform-specific AMPK activity, and 3-O-methylglucose (3MG) transport. In contrast, caffeine inhibited basal and contraction-stimulated Akt Ser(473) phosphorylation. Caffeine significantly delayed muscle fatigue during contraction, and the combination of caffeine and contraction additively decreased ATP and phosphocreatine contents. Caffeine did not affect resting tension. Next, rats were given an intraperitoneal injection of caffeine (60 mg/kg body weight) or saline, and the extensor digitorum longus muscle was dissected 15 min later. ES of the sciatic nerve was performed to evoke tetanic contractions for 5 min before dissection. Similar to the findings from isolated muscles incubated in vitro, the combination of caffeine plus contraction in vivo had additive effects on AMPK phosphorylation, AMPK activity, and 3MG transport. Caffeine also inhibited basal and contraction-stimulated Akt phosphorylation in vivo. These findings suggest that caffeine and contraction synergistically stimulate AMPK activity and insulin-independent glucose transport, at least in part by decreasing muscle fatigue and thereby promoting energy consumption during contraction.

  6. Adenosine modulation of [Ca2+]i in cerebellar granular cells: multiple adenosine receptors involved.

    Vacas, Javier; Fernández, Mercedes; Ros, Manuel; Blanco, Pablo

    2003-12-01

    Elimination of adenosine by addition of adenosine deaminase (ADA) to the media leads to alterations in intracellular free calcium concentration ([Ca(2+)](i)) in cerebellar granular cells. Adenosine deaminase brings about increases or decreases in [Ca(2+)](i) depending on the previous activation state of the cell. These effects are dependent on the catalytic activity of adenosine deaminase, since its previous catalytic inactivation with Hg(2+) prevents the above-mentioned changes in intracellular calcium. Extracellular calcium is required for the increase in [Ca(2+)](i) promoted by ADA. This rise is insensitive to thapsigargin, but sensitive to micromolar concentrations of Ni(2+). Toxins specific for L, N and P/Q calcium channels do not overtly reduce this effect. N(6)-Cyclopentyl adenosine (CPA), an A(1) receptor agonist, produces a partial reversion of ADA effects, while CGS21680, A(2A)/A(2B) receptor agonist, slightly enhances them. Expression of A(1), A(2A), A(2B) and A(3) adenosine receptor mRNAs was detected in cerebellar granular cell cultures. These results suggest that adenosine modulate [Ca(2+)](i) in cerebellar granule cells through different adenosine receptor subtypes which, at least in part, seem to act through R-type calcium channels.

  7. The AMPK enzyme-complex: From the regulation of cellular energy homeostasis to a possible new molecular target in the management of chronic inflammatory disorders

    Antonioli, Luca; Colucci, Rocchina; Pellegrini, Carolina; Giustarini, Giulio; Sacco, Deborah; Tirotta, Erika; Caputi, Valentina; Marsilio, Ilaria; Giron, Maria Cecilia; Németh, Zoltán H; Blandizzi, Corrado; Fornai, Matteo

    2016-01-01

    Introduction: Adenosine monophosphate-activated protein kinase (AMPK), known as an enzymatic complex that regulates the energetic metabolism, is emerging as a pivotal enzyme and enzymatic pathway involved in the regulation of immune homeostatic networks. It is also involved in the molecular mechanis

  8. Adenosine stress protocols for myocardial perfusion imaging

    Baškot Branislav

    2008-01-01

    Full Text Available Background/Aim. Treadmill test combined with myocardial perfusion scintigraphy (MPS is a commonly used technique in the assessment of coronary artery disease. There are many patients, however, who may not be able to undergo treadmill test. Such patients would benefit from pharmacological stress procedures combined with MPS. The most commonly used pharmacological agents for cardiac stress are coronary vasodilatators (adenosine, dipyridamol and catecholamines. Concomitant low-level treadmill exercise with adenosine pharmacologic stress (AdenoEX during MPS has become commonly used in recent years. A number of studies have demonstrated a beneficial impact of AdenoEX protocol. The aim of the study was, besides introducing into practice the two types of protocols of pharmatological stress test with adenosine, as a preparation for MPS, to compare and monitor the frequency of their side effects to quality, acquisition, as well as to standardize the onset time of acquisition (diagnostic imaging for both protocols. Methods. A total of 130 patients underwent pharmacological stress test with adenosine (vasodilatator. In 108 of the patients we performed concomitant exercise (AdenoEX of low level (50W by a bicycle ergometar. In 28 of the patients we performed Adenosine abbreviated protocol (AdenoSCAN. Side effects of adenosine were followed and compared between the two kinds of protocols AdenoEX and AdenoSCAN. Also compared were image quality and suggested time of acquisition after the stress test. Results. Numerous side effects were found, but being short-lived they did not require any active interventions. The benefit of AdenoEX versus AdenoSCAN included decreased side effects (62% vs 87%, improved safety and patients tolerance, improved target-to-background ratios because of less subdiaphragmatic activity, earlier acquisition, and improved sensitivity. Conclusion. The safety and efficacy of adenosine pharmacological stress is even better with concomitant

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

    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.

  10. Allosteric modulators affect the internalization of human adenosine A1 receptors.

    Klaasse, E.C.; Hout, G. van den; Roerink, S.F.; Grip, W.J. de; IJzerman, A.P.; Beukers, M.W.

    2005-01-01

    To study the effect of allosteric modulators on the internalization of human adenosine A(1) receptors, the receptor was equipped with a C-terminal yellow fluorescent protein tag. The introduction of this tag did not affect the radioligand binding properties of the receptor. CHO cells stably expressi

  11. Investigation on the diagnosis significance of C reactive protein and adenosine deaminase in cerebrospinal fluid among children with meningitis%脑脊液C反应蛋白和腺苷脱氨酶检测在小儿脑膜炎中的诊断价值探讨

    徐仁荣; 张慧华; 朱华丽

    2015-01-01

    Objective To determine C reactive protein and adenosine deaminase in cerebrospinal fluid,and to investigate the clinical diagnosis significance for tuberculosis meningitis,purulent meningitis and viral meningitis. Methods A total of 31 5 children with meningitis (1 02 cases of tuberculosis meningitis,1 08 cases of purulent meningitis and 1 05 cases of viral meningitis)were enrolled,96 children undergoing operation without meningitis were enrolled as control group,and their cerebrospinal fluid samples were collected.The levels of C reactive protein and adenosine deaminase were determined,and the results were compared.Results C reactive protein and adenosine deaminase in control and viral meningitis groups were significantly lower than those in tuberculosis and purulent meningitis groups (P 0.05 ).C reactive protein in purulent meningitis group was higher than that in tuberculosis meningitis group(P <0.05 ),and adenosine deaminase was lower than that in tuberculosis meningitis group (P <0.05).C reactive protein in purulent meningitis group was positive,and the positive rate was 1 00%.There were 63 positive cases in tuberculosis meningitis group,and the positive rate was 61 .76%.That in viral meningtis was negative.Conclusions In cerebrospinal fluid,C reactive protein and adenosine deaminase determinations have important reference significance for the differential diagnosis of bacterial meningitis (purulent meningitis and tuberculosis meningitis)and viral meningitis.Adenosine deaminase may be a good indicator for the diagnosis of tuberculosis meningitis,in order to provide the reference for the early diagnosis of various types of meningitis.%目的:探讨小儿脑脊液C反应蛋白和腺苷脱氨酶在结核性脑膜炎、化脓性脑膜炎和病毒性脑膜炎早期诊断中的临床意义。方法分别检测315例小儿脑膜炎患儿(包括结核性脑膜炎102例、化脓性脑膜炎108例、病毒性脑膜炎105例)及96例非脑膜炎外科手术

  12. The role of adenosine receptors and endogenous adenosine in citalopram-induced cardiovascular toxicity

    Kubilay Oransay

    2014-01-01

    Full Text Available Aim: We investigated the role of adenosine in citalopram-induced cardiotoxicity. Materials and Methods: Protocol 1: Rats were randomized into four groups. Sodium cromoglycate was administered to rats. Citalopram was infused after the 5% dextrose, 8-Cyclopentyl-1,3-dipropylxanthine (DPCPX; A 1 receptor antagonist, 8-(-3-chlorostyryl-caffeine (CSC; A 2a receptor antagonist, or dimethyl sulfoxide (DMSO administrations. Protocol 2: First group received 5% dextrose intraperitoneally 1 hour prior to citalopram. Other rats were pretreated with erythro-9-(2-hydroxy-3-nonyl adenine (EHNA; inhibitor of adenosine deaminase and S-(4-Nitrobenzyl-6-thioinosine (NBTI; inhibitor of facilitated adenosine transport. After pretreatment, group 2 received 5% dextrose and group 3 received citalopram. Adenosine concentrations, mean arterial pressure (MAP, heart rate (HR,  QRS duration and QT interval were evaluated. Results: In the dextrose group, citalopram infusion caused a significant decrease in MAP and HR and caused a significant prolongation in QRS and QT. DPCPX infusion significantly prevented the prolongation of the QT interval when compared to control. In the second protocol, citalopram infusion did not cause a significant change in plasma adenosine concentrations, but a significant increase observed in EHNA/NBTI groups. In EHNA/NBTI groups, citalopram-induced MAP and HR reductions, QRS and QT prolongations were more significant than the dextrose group. Conclusions: Citalopram may lead to QT prolongation by stimulating adenosine A 1 receptors without affecting the release of adenosine.

  13. 2'-O methylation of internal adenosine by flavivirus NS5 methyltransferase.

    Hongping Dong

    Full Text Available RNA modification plays an important role in modulating host-pathogen interaction. Flavivirus NS5 protein encodes N-7 and 2'-O methyltransferase activities that are required for the formation of 5' type I cap (m(7GpppAm of viral RNA genome. Here we reported, for the first time, that flavivirus NS5 has a novel internal RNA methylation activity. Recombinant NS5 proteins of West Nile virus and Dengue virus (serotype 4; DENV-4 specifically methylates polyA, but not polyG, polyC, or polyU, indicating that the methylation occurs at adenosine residue. RNAs with internal adenosines substituted with 2'-O-methyladenosines are not active substrates for internal methylation, whereas RNAs with adenosines substituted with N⁶-methyladenosines can be efficiently methylated, suggesting that the internal methylation occurs at the 2'-OH position of adenosine. Mass spectroscopic analysis further demonstrated that the internal methylation product is 2'-O-methyladenosine. Importantly, genomic RNA purified from DENV virion contains 2'-O-methyladenosine. The 2'-O methylation of internal adenosine does not require specific RNA sequence since recombinant methyltransferase of DENV-4 can efficiently methylate RNAs spanning different regions of viral genome, host ribosomal RNAs, and polyA. Structure-based mutagenesis results indicate that K61-D146-K181-E217 tetrad of DENV-4 methyltransferase forms the active site of internal methylation activity; in addition, distinct residues within the methyl donor (S-adenosyl-L-methionine pocket, GTP pocket, and RNA-binding site are critical for the internal methylation activity. Functional analysis using flavivirus replicon and genome-length RNAs showed that internal methylation attenuated viral RNA translation and replication. Polymerase assay revealed that internal 2'-O-methyladenosine reduces the efficiency of RNA elongation. Collectively, our results demonstrate that flavivirus NS5 performs 2'-O methylation of internal adenosine of

  14. The role of adenosine in Alzheimer's disease.

    Rahman, Anisur

    2009-09-01

    Alzheimer's disease (AD) is a neurodegenerative disorder of the central nervous system manifested by cognitive and memory deterioration, a variety of neuropsychiatric symptoms, behavioral disturbances, and progressive impairment of daily life activities. Current pharmacotherapies are restricted to symptomatic interventions but do not prevent progressive neuronal degeneration. Therefore, new therapeutic strategies are needed to intervene with these progressive pathological processes. In the past several years adenosine, a ubiquitously released purine ribonucleoside, has become important for its neuromodulating capability and its emerging positive experimental effects in neurodegenerative diseases. Recent research suggests that adenosine receptors play important roles in the modulation of cognitive function. The present paper attempts to review published reports and data from different studies showing the evidence of a relationship between adenosinergic function and AD-related cognitive deficits. Epidemiological studies have found an association between coffee (a nonselective adenosine receptor antagonist) consumption and improved cognitive function in AD patients and in the elderly. Long-term administration of caffeine in transgenic animal models showed a reduced amyloid burden in brain with better cognitive performance. Antagonists of adenosine A2A receptors mimic these beneficial effects of caffeine on cognitive function. Neuronal cell cultures with amyloid beta in the presence of an A2A receptor antagonist completely prevented amyloid beta-induced neurotoxicity. These findings suggest that the adenosinergic system constitutes a new therapeutic target for AD, and caffeine and A2A receptor antagonists may have promise to manage cognitive dysfunction in AD.

  15. Measuring the dynamics of cyclic adenosine monophosphate level in living cells induced by low-level laser irradiation using bioluminescence resonance energy transfer

    Huang, Yimei; Zheng, Liqin; Yang, Hongqin; Chen, Jiangxu; Wang, Yuhua; Li, Hui; Xie, Shusen; Zeng, Haishan

    2015-05-01

    Several studies demonstrated that the cyclic adenosine monophosphate (cAMP), an important second messenger, is involved in the mechanism of low-level laser irradiation (LLLI) treatment. However, most of these studies obtained the cAMP level in cell culture extracts or supernatant. In this study, the cAMP level in living cells was measured with bioluminescence resonance energy transfer (BRET). The effect of LLLI on cAMP level in living cells with adenosine receptors blocked was explored to identify the role of adenosine receptors in LLLI. The results showed that LLLI increased the cAMP level. Moreover, the rise of cAMP level was light dose dependent but wavelength independent for 658-, 785-, and 830-nm laser light. The results also exhibited that the adenosine receptors, a class of G protein-coupled receptor (GPCR), modulated the increase of cAMP level induced by LLLI. The cAMP level increased more significantly when the A3 adenosine receptors (A3R) were blocked by A3R antagonist compared with A1 adenosine receptor or A2a adenosine receptor blocked in HEK293T cells after LLLI, which was in good agreement with the adenosine receptors' expressions. All these results suggested that measuring the cAMP level with BRET could be a useful technique to study the role of GPCRs in living cells under LLLI.

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

    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.

  17. AMP is an adenosine A1 receptor agonist.

    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.

  18. Adenosine: An immune modulator of inflammatory bowel diseases

    Jeff Huaqing Ye; Vazhaikkurichi M Rajendran

    2009-01-01

    Inflammatory bowel disease (IBD) is a common and lifelong disabling gastrointestinal disease. Emerging treatments are being developed to target inflammatory cytokines which initiate and perpetuate the immune response. Adenosine is an important modulator of inflammation and its anti-inflammatory effects have been well established in humans as well as in animal models. High extracellular adenosine suppresses and resolves chronic inflammation in IBD models. High extracellular adenosine levels could be achieved by enhanced adenosine absorption and increased de novo synthesis. Increased adenosine concentration leads to activation of the A2a receptor on the cell surface of immune and epithelial cells that would be a potential therapeutic target for chronic intestinal inflammation. Adenosine is transported via concentrative nucleoside transporter and equilibrative nucleoside transporter transporters that are localized in apical and basolateral membranes of intestinal epithelial cells, respectively. Increased extracellular adenosine levels activate the A2a receptor, which would reduce cytokines responsible for chronic inflammation.

  19. A Cistanches Herba Fraction/β-Sitosterol Causes a Redox-Sensitive Induction of Mitochondrial Uncoupling and Activation of Adenosine Monophosphate-Dependent Protein Kinase/Peroxisome Proliferator-Activated Receptor γ Coactivator-1 in C2C12 Myotubes: A Possible Mechanism Underlying the Weight Reduction Effect

    Hoi Shan Wong

    2015-01-01

    Full Text Available Previous studies have demonstrated that HCF1, a semipurified fraction of Cistanches Herba, causes weight reduction in normal diet- and high fat diet-fed mice. The weight reduction was associated with the induction of mitochondrial uncoupling and changes in metabolic enzyme activities in mouse skeletal muscle. To further investigate the biochemical mechanism underlying the HCF1-induced weight reduction, the effect of HCF1 and its active component, β-sitosterol (BSS, on C2C12 myotubes was examined. Incubation with HCF1/BSS caused a transient increase in mitochondrial membrane potential (MMP, possibly by fluidizing the mitochondrial inner membrane. The increase in MMP was paralleled to an increase in mitochondrial reactive oxygen species (ROS production. Mitochondrial ROS, in turn, triggered a redox-sensitive induction of mitochondrial uncoupling by uncoupling protein 3 (UCP3. Biochemical analysis indicated that HCF1 was capable of activating an adenosine monophosphate-dependent protein kinase/peroxisome proliferator-activated receptor γ coactivator-1 pathway and thereby increased the expression of cytochrome c oxidase and UCP3. Animal studies using mitochondrial recoupler also confirmed the role of mitochondrial uncoupling in the HCF1-induced weight reduction. In conclusion, a HCF1/BSS causes the redox-sensitive induction of mitochondrial uncoupling and activation of AMPK/PGC-1 in C2C12 myotubes, with resultant reductions in body weight and adiposity by increased energy consumption.

  20. Aminopyrimidine derivatives as adenosine antagonists / Janke Kleynhans

    Kleynhans, Janke

    2013-01-01

    Aims of this project - The aim of this study was to design and synthesise novel 2-aminopyrimidine derivatives as potential adenosine A1 and A2A receptor antagonists. Background and rationale - Parkinson’s disease is the second most common neurodegenerative disorder (after Alzheimer’s disease) and is characterised by the selective death of the dopaminergic neurons of the nigro-striatal pathway. Distinctive motor symptoms include bradykinesia, muscle rigidity and tremor, while non-m...

  1. Dynamic Regulation of the Adenosine Kinase Gene during Early Postnatal Brain Development and Maturation

    Kiese, Katharina; Jablonski, Janos; Boison, Detlev; Kobow, Katja

    2016-01-01

    The ubiquitous metabolic intermediary and nucleoside adenosine is a “master regulator” in all living systems. Under baseline conditions adenosine kinase (ADK) is the primary enzyme for the metabolic clearance of adenosine. By regulating the availability of adenosine, ADK is a critical upstream regulator of complex homeostatic and metabolic networks. Not surprisingly, ADK dysfunction is involved in several pathologies, including diabetes, epilepsy, and cancer. ADK protein exists in the two isoforms nuclear ADK-L, and cytoplasmic ADK-S, which are subject to dynamic expression changes during brain development and in response to brain injury; however, gene expression changes of the Adk gene as well as regulatory mechanisms that direct the cell-type and isoform specific expression of ADK have never been investigated. Here we analyzed potential gene regulatory mechanisms that may influence Adk expression including DNA promoter methylation, histone modifications and transcription factor binding. Our data suggest binding of transcription factor SP1 to the Adk promoter influences the regulation of Adk expression. PMID:27812320

  2. Presynaptic inhibition by kainate receptors converges mechanistically with presynaptic inhibition by adenosine and GABAB receptors.

    Partovi, Dara; Frerking, Matthew

    2006-11-01

    Kainate receptors are widely reported to regulate the release of neurotransmitter in the CNS, but the mechanisms involved remain controversial. Previous studies have found that the kainate receptor agonist ATPA, which selectively activates Glu(K5)-containing kainate receptors, depresses glutamate release at Schaffer-collateral synapses in the hippocampus. In the present study, we provide pharmacological evidence that this depressant effect is mediated by Glu(K5)-containing heteromers, but is distinct from a similar depressant effect engaged by the kainate receptor agonist domoate. The depressant effect of ATPA is insensitive to antagonists for GABA(A), GABA(B), and adenosine receptors, and is also unaffected by lowering the release probability by reducing extracellular calcium. However, the effect of ATPA is partly occluded by prior activation of GABA(B) receptors and completely occluded by prior activation of adenosine receptors, suggesting a mechanistic convergence of heteromeric Glu(K5) kainate receptor signaling with GABA(B) receptors and adenosine receptors. The effects of domoate are partially occluded by both adenosine and GABA(B) receptor agonists, indicating at least a partial convergence of Glu(K5)-lacking kainate receptor signaling with these other pathways. The depressant effect of ATPA is not blocked by inhibition of serine/threonine protein kinases. These results suggest that ATPA and domoate inhibit glutamate release through mechanisms that converge with those of classical metabotropic receptor agonists, although they do so through different receptors.

  3. Cancer chemoprevention by an adenosine derivative in a model of cirrhosis-hepatocellular carcinoma induced by diethylnitrosamine in rats.

    Velasco-Loyden, Gabriela; Pérez-Martínez, Lidia; Vidrio-Gómez, Susana; Pérez-Carreón, Julio Isael; Chagoya de Sánchez, Victoria

    2017-02-01

    Hepatocellular carcinoma is one of the most common cancers, and approximately 80% develop from cirrhotic livers. We have previously shown that the aspartate salt of adenosine prevents and reverses carbon tetrachloride-induced liver fibrosis in rats. Considering the hepatoprotective role of this adenosine derivative in fibrogenesis, we were interested in evaluating its effect in a hepatocarcinogenesis model induced by diethylnitrosamine in rats, where multinodular cancer is preceded by cirrhosis. Rats were injected with diethylnitrosamine for 12 weeks to induce cirrhosis and for 16 weeks to induce hepatocarcinogenesis. Groups of rats were treated with aspartate salt of adenosine from the beginning of carcinogen administration for 12 or 18 weeks total, and another group received the compound from weeks 12 to 18. Fibrogenesis was estimated and the proportion of preneoplastic nodules and tumors was measured. The apoptotic and proliferation rates in liver tissues were evaluated, as well as the expression of cell signaling and cell cycle proteins participating in hepatocarcinogenesis. The adenosine derivative treatment reduced diethylnitrosamine-induced collagen expression and decreased the proportion of nodules positive for the tumor marker γ-glutamyl transferase. This compound down-regulated the expression of thymidylate synthase and hepatocyte growth factor, and augmented the protein level of the cell cycle inhibitor p27; these effects could be part of its chemopreventive mechanism. These findings suggest a hepatoprotective role of aspartate salt of adenosine that could be used as a therapeutic compound in the prevention of liver tumorigenesis as described earlier for hepatic fibrosis.

  4. [The involvement of adenosine and adenosine deaminase in experimental myocardial infarct].

    Stratone, A; Busuioc, A; Roşca, V; Bazgan, L; Popa, M; Hăulică, I

    1989-01-01

    By the ligature of the left coronary artery in the rat anesthetized with nembutal (10 mg/100 i.p.) a significant increase of the 5'-nucleotidase activity (Wooton method) was noticed 10 minutes after the left ventricle infarction (from an average value of 1038.5 +/- 187 mU/g tissue to 1537 +/- 225 mU/g fresh tissue). The adenosine desaminase levels spectrophotometrically determined by Denstedt technique, do not appear significantly modified 10 or 30 minutes after the left ventricle infarction. The chromatographically determined adenosine levels, by HPLC technique, decrease from the average value of 11.63 +/- 1.4 micrograms/mg PT to 8.60 +/- 1.0 micrograms/mg PT 30 minutes after infarction. The observed changes are explained by the conditions of hypoxia in the infarcted ventricle which lead to the raise in adenosine levels by activating the 5'-nucleotidase and their depression by a very fast metabolism of the same substance.

  5. Effects of adenosine agonist R-phenylisopropyl-adenosine on halothane anesthesia and antinociception in rats

    Hai-chun MA; Yan-fen WANG; Chun-sheng FENG; Hua ZHAO; Shuji DOHI

    2005-01-01

    Aim: To investigate the antinociceptive effect of adenosine agonist Rphenylisopropyl-adenosine (R-PIA) given to conscious rats by intracerebroventricular (ICV) and intrathecal (IT), and identify the effect of R-PIA on minimum alveolar concentration (MAC) of halothane with pretreatment of A1 receptor an tagonist 8-cyclopentyl-1,3-dipropylxanthine (DPCPX) or K+ channel blocker 4-aminopyridine (4-AP). Methods: Sprague-Dawley rats were implanted with 24 gauge stainless steel guide cannula using stereotaxic apparatus and ICV method, and an IT catheter (PE-10, 8.5 cm) was inserted into the lumbar subarachnoid space, while the rats were under pentobarbital anesthesia. After one week of recovery from surgery, rats were randomly assigned to one of the following protocols: MAC of halothane, or tail-flick latency. All measurements were performed after R-PIA (0.8-2.0 μg) microinjection into ICV and IT with or without pretreatment of DPCPX or 4-AP. Results: Microinjection of adenosine agonist R PIA in doses of 0.8-2.0 μg into ICV and IT produced a significant dose- and time dependent antinociceptive action as reflected by increasing latency times and ICV administration of adenosine agonist R-PIA (0.8 μg) reducing halothane anes thetic requirements (by 29%). The antinociception and reducing halothane requirements effected by adenosine agonist R-PIA was abolished by DPCPX and 4-AP. Conclusion: ICV and IT administration of adenosine agonist R-PIA produced an antinociceptive effect in a dose-dependent manner and decreased hal othane MAC with painful stimulation through activation of A1 receptor subtype, and the underlying mechanism involves K+ channel activation.

  6. Primary adenosine monophosphate (AMP) deaminase deficiency in a hypotonic infant.

    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.

  7. Pretreatment with adenosine and adenosine A1 receptor agonist protects against intestinal ischemia-reperfusion injury in rat

    V Haktan Ozacmak; Hale Sayan

    2007-01-01

    AIM: To examine the effects of adenosine and A1 receptor activation on reperfusion-induced small intestinal injury.METHODS: Rats were randomized into groups with sham operation, ischemia and reperfusion, and systemic treatments with either adenosine or 2-chloro-N6-cyclopentyladenosine, A1 receptor agonist or 8-cyclopentyl-1,3-dipropylxanthine, A1 receptor antagonist, plus adenosine before ischemia. Following reperfusion, contractions of ileum segments in response to KCl, carbachol and substance P were recorded. Tissue myeloperoxidase,malondialdehyde, and reduced glutathione levels were measured.RESULTS: Ischemia significantly decreased both contraction and reduced glutathione level which were ameliorated by adenosine and agonist administration. Treatment also decreased neutrophil infiltration and membrane lipid peroxidation. Beneficial effects of adenosine were abolished by pretreatment with A1 receptor antagonist.CONCLUSION: The data suggest that adenosine and A1 receptor stimulation attenuate ischemic intestinal injury via decreasing oxidative stress, lowering neutrophil infiltration, and increasing reduced glutathione content.

  8. Effects of AMP579 and adenosine on L-type Ca2+ current in isolated rat ventricular myocytes

    Xiong WANG; Bo-wei WU; Dong-mei WU

    2005-01-01

    Aim: To compare the effects of AMP579 and adenosine on L-type Ca2+ current (ICa- L) in rat ventricular myocytes and explore the mechanism by which AMP579 acts on ICa-L. Methods: ICa-L was recorded by patch-clamp technique in whole-cell configuration. Results: Adenosine (10 nmol/L to 50 μmol/L) showed no effect on basal ICa- L, but it inhibited the ICa-L induced by isoproterenol 10 nmol/L in a concen tration-dependent manner with the IC50 of 13.06 μmol/L. Similar to adenosine,AMP579 also showed an inhibitory effect on the ICa-L induced by isoproterenol.AMP579 and adenosine (both in 10 μmol/L) suppressed isoproterenol-induced ICa-L by 11.1% and 5.2%, respectively. In addition, AMP579 had a direct inhibitory effect on basal ICa-L in a concentration-dependent manner with IC50 (1.17 μmol/L).PD116948 (30 μmol/L), an adenosine A1 receptor blocker, showed no action on the inhibitory effect of AMP579 on basal ICa-L. However, GF109203X (0.4 μmol/L), a special protein kinase C (PKC) blocker, could abolish the inhibitory effect of AMP579 on basal ICa-L. So the inhibitory effect of AMP579 on basal ICa-L was induced through activating PKC, but not linked to adenosine A1 receptor. Conclusion:AMP579 shows a stronger inhibitory effect than adenosine on the ICa-L induced by isoproterenol. AMP579 also has a strong inhibitory effect on basal ICa-L in rat ventricular myocytes. Activation of PKC is involved in the inhibitory effect of AMP579 on basal ICa-L at downstream-mechanism.

  9. Mechanism of protection of adenosine from sulphate radical anion and repair of adenosine radicals by caffeic acid in aqueous solution

    M Sudha Swaraga; L Charitha; M Adinarayana

    2005-07-01

    The photooxidation of adenosine in presence of peroxydisulphate (PDS) has been studied by spectrophotometrically measuring the absorbance of adenosine at 260 nm. The rates of oxidation of adenosine by sulphate radical anion have been determined in the presence of different concentrations of caffeic acid. Increase in [caffeic acid] is found to decrease the rate of oxidation of adenosine suggesting that caffeic acid acts as an efficient scavenger of $SO_{4}^{\\bullet-}$ and protects adenosine from it. Sulphate radical anion competes for adenosine as well as for caffeic acid. The quantum yields of photooxidation of adenosine have been calculated from the rates of oxidation of adenosine and the light intensity absorbed by PDS at 254 nm, the wavelength at which PDS is activated to sulphate radical anion. From the results of experimentally determined quantum yields (exptl) and the quantum yields calculated (cal) assuming caffeic acid acting only as a scavenger of $SO_{4}^{\\bullet-}$ show that exptl values are lower than cal values. The ' values, which are experimentally found quantum yield values at each caffeic acid concentration and corrected for $SO_{4}^{\\bullet-}$ scavenging by caffeic acid, are also found to be greater than exptl values. These observations suggest that the transient adenosine radicals are repaired by caffeic acid in addition to scavenging of sulphate radical anions.

  10. Electroacupuncture improves neuropathic pain Adenosine,adenosine 5'-triphosphate disodium and their receptors perhaps change simultaneously

    Wen Ren; Wenzhan Tu; Songhe Jiang; Ruidong Cheng; Yaping Du

    2012-01-01

    Applying a stimulating current to acupoints through acupuncture needles-known as electroacupuncture-has the potential to produce analgesic effects in human subjects and experimental animals.When acupuncture was applied in a rat model,adenosine 5'-triphosphate disodium in the extracellular space was broken down into adenosine,which in turn inhibited pain transmission by means of an adenosine A1 receptor-dependent process.Direct injection of an adenosine A1 receptor agonist enhanced the analgesic effect of acupuncture.The analgesic effect of acupuncture appears to be mediated by activation of A1 receptors located on ascending nerves.In neuropathic pain,there is upregulation of P2X purinoceptor 3(P2X3)receptor expression in dorsal root ganglion neurons.Conversely,the onset of mechanical hyperalgesia was diminished and established hyperalgesia was significantly reversed when P2X3 receptor expression was downregulated.The pathways upon which electroacupuncture appear to act are interwoven with pain pathways,and electroacupuncture stimuli converge with impulses originating from painful areas.Electroacupuncture may act via purinergic A1 and P2X3 receptors simultaneously to induce an analgesic effect on neuropathic pain.

  11. Adenosine as a Multi-Signalling Guardian Angel in Human Diseases: When, Where and How Does it Exert its Protective Effects?

    Borea, Pier Andrea; Gessi, Stefania; Merighi, Stefania; Varani, Katia

    2016-06-01

    The importance of adenosine for human health cannot be overstated. Indeed, this ubiquitous nucleoside is an integral component of ATP, and regulates the function of every tissue and organ in the body. Acting via receptor-dependent and -independent mechanisms [the former mediated via four G-protein-coupled receptors (GPCRs), A1, A2A, A2B, and A3,], it has a significant role in protecting against cell damage in areas of increased tissue metabolism, and combating organ dysfunction in numerous pathological states. Accordingly, raised levels of adenosine have been demonstrated in epilepsy, ischaemia, pain, inflammation, and cancer, in which its behaviour can be likened to that of a guardian angel, even though there are instances in which overproduction of adenosine is pathological. In this review, we condense the current body of knowledge on the issue, highlighting when, where, and how adenosine exerts its protective effects in both the brain and the periphery.

  12. Comorbidities in Neurology: Is Adenosine the Common Link?

    Boison, Detlev; Aronica, Eleonora

    2015-01-01

    Comorbidities in Neurology represent a major conceptual and therapeutic challenge. For example, temporal lobe epilepsy (TLE) is a syndrome comprised of epileptic seizures and comorbid symptoms including memory and psychiatric impairment, depression, and sleep dysfunction. Similarly, Alzheimer’s disease (AD), Parkinson’s disease (PD), and Amyotrophic Lateral Sclerosis (ALS) are accompanied by various degrees of memory dysfunction. Patients with AD have an increased likelihood for seizures, whereas all four conditions share certain aspects of psychosis, depression, and sleep dysfunction. This remarkable overlap suggests common pathophysiological mechanisms, which include synaptic dysfunction and synaptotoxicity, as well as glial activation and astrogliosis. Astrogliosis is linked to synapse function via the tripartite synapse, but astrocytes also control the availability of gliotransmitters and adenosine. Here we will specifically focus on the ‘adenosine hypothesis of comorbidities’ implying that astrocyte activation, via overexpression of adenosine kinase (ADK), induces a deficiency in the homeostatic tone of adenosine. We present evidence from patient-derived samples showing astrogliosis and overexpression of ADK as common pathological hallmark of epilepsy, AD, PD, and ALS. We discuss a transgenic ‘comorbidity model’, in which brain-wide overexpression of ADK and resulting adenosine deficiency produces a comorbid spectrum of seizures, altered dopaminergic function, attentional impairment, and deficits in cognitive domains and sleep regulation. We conclude that dysfunction of adenosine signaling is common in neurological conditions, that adenosine dysfunction can explain comorbid phenotypes, and that therapeutic adenosine augmentation might be effective for the treatment of comorbid symptoms in multiple neurological conditions. PMID:25979489

  13. Endogenous adenosine curtails lipopolysaccharide-stimulated tumour necrosis factor synthesis

    Eigler, A; Greten, T F; Sinha, B; Haslberger, C; Sullivan, G W; Endres, S

    1997-01-01

    Recent studies have demonstrated the inhibitory effect of exogenous adenosine on TNF production. During inflammation endogenous adenosine levels are elevated and may be one of several anti-inflammatory mediators that reduce TNF synthesis. In the present study the authors investigated this role of ad

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

    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.

  15. A Case of Hypogammaglobulinemia with Enteroviral Meningoencephalitis, Associated with Increased Adenosine Deaminase in Cerebrospinal Fluid

    Alborizi Abdolvahab

    2009-06-01

    Full Text Available We describe the development of enterovirus meningoencephalitis associated with increased adenosine deaminase in cerebrospinal fluid of a 12-year-old boy, a known case of hypogamaglobulinemia despite monthly replacement of IVIg.The patient was referred to our center with fever, headache and vomiting for 10 days. CSF analysis was compatible with aseptic meningoencephalitis but high CSF protein (>200mg/dl and high level of adenosine deaminase in CSF (30IU/L were against the diagnosis of simple viral meningoencephalitis. Nested PCR of CSF for entrovirus was positive. Treatment with daily high-dose IVIg was commenced, with significant clinical improvement. For patients with increased ADA and lymphocytic pleocytosis in CSF, differential diagnoses should include enteroviral meningitis. Antibodies, although crucial, cannot on their own prevent enteroviral infection in some hypogamaglbulinemic patients.

  16. A High-Affinity Adenosine Kinase from Anopheles Gambiae

    M Cassera; M Ho; E Merino; E Burgos; A Rinaldo-Matthis; S Almo; V Schramm

    2011-12-31

    Genome analysis revealed a mosquito orthologue of adenosine kinase in Anopheles gambiae (AgAK; the most important vector for the transmission of Plasmodium falciparum in Africa). P. falciparum are purine auxotrophs and do not express an adenosine kinase but rely on their hosts for purines. AgAK was kinetically characterized and found to have the highest affinity for adenosine (K{sub m} = 8.1 nM) of any known adenosine kinase. AgAK is specific for adenosine at the nucleoside site, but several nucleotide triphosphate phosphoryl donors are tolerated. The AgAK crystal structure with a bound bisubstrate analogue Ap{sub 4}A (2.0 {angstrom} resolution) reveals interactions for adenosine and ATP and the geometry for phosphoryl transfer. The polyphosphate charge is partly neutralized by a bound Mg{sup 2+} ion and an ion pair to a catalytic site Arg. The AgAK structure consists of a large catalytic core in a three-layer {alpha}/{beta}/{alpha} sandwich, and a small cap domain in contact with adenosine. The specificity and tight binding for adenosine arise from hydrogen bond interactions of Asn14, Leu16, Leu40, Leu133, Leu168, Phe168, and Thr171 and the backbone of Ile39 and Phe168 with the adenine ring as well as through hydrogen bond interactions between Asp18, Gly64, and Asn68 and the ribosyl 2'- and 3'-hydroxyl groups. The structure is more similar to that of human adenosine kinase (48% identical) than to that of AK from Toxoplasma gondii (31% identical). With this extraordinary affinity for AgAK, adenosine is efficiently captured and converted to AMP at near the diffusion limit, suggesting an important role for this enzyme in the maintenance of the adenine nucleotide pool. mRNA analysis verifies that AgAK transcripts are produced in the adult insects.

  17. Expression of Drosophila adenosine deaminase in immune cells during inflammatory response.

    Novakova, Milena; Dolezal, Tomas

    2011-03-11

    Extra-cellular adenosine is an important regulator of inflammatory responses. It is generated from released ATP by a cascade of ectoenzymes and degraded by adenosine deaminase (ADA). There are two types of enzymes with ADA activity: ADA1 and ADGF/ADA2. ADA2 activity originates from macrophages and dendritic cells and is associated with inflammatory responses in humans and rats. Drosophila possesses a family of six ADGF proteins with ADGF-A being the main regulator of extra-cellular adenosine during larval stages. Herein we present the generation of a GFP reporter for ADGF-A expression by a precise replacement of the ADGF-A coding sequence with GFP using homologous recombination. We show that the reporter is specifically expressed in aggregating hemocytes (Drosophila immune cells) forming melanotic capsules; a characteristic of inflammatory response. Our vital reporter thus confirms ADA expression in sites of inflammation in vivo and demonstrates that the requirement for ADA activity during inflammatory response is evolutionary conserved from insects to vertebrates. Our results also suggest that ADA activity is achieved specifically within sites of inflammation by an uncharacterized post-transcriptional regulation based mechanism. Utilizing various mutants that induce melanotic capsule formation and also a real immune challenge provided by parasitic wasps, we show that the acute expression of the ADGF-A protein is not driven by one specific signaling cascade but is rather associated with the behavior of immune cells during the general inflammatory response. Connecting the exclusive expression of ADGF-A within sites of inflammation, as presented here, with the release of energy stores when the ADGF-A activity is absent, suggests that extra-cellular adenosine may function as a signal for energy allocation during immune response and that ADGF-A/ADA2 expression in such sites of inflammation may regulate this role.

  18. Activation of extracellular signal-regulated kinases, NF-kappa B, and cyclic adenosine 5'-monophosphate response element-binding protein in lung neutrophils occurs by differing mechanisms after hemorrhage or endotoxemia.

    Abraham, E; Arcaroli, J; Shenkar, R

    2001-01-01

    Acute lung injury is frequently associated with sepsis or blood loss and is characterized by a proinflammatory response and infiltration of activated neutrophils into the lungs. Hemorrhage or endotoxemia result in activation of cAMP response element-binding protein (CREB) and NF-kappa B in lung neutrophils as well as increased expression of proinflammatory cytokines, such as TNF-alpha and macrophage-inflammatory peptide-2, by these cells. Activation of the extracellular regulated kinase (ERK) pathway occurs in stress responses and is involved in CREB activation. In the present experiments, hemorrhage or endotoxemia produced increased activation of mitogen-activated protein kinase kinase (MEK)1/2 and ERK2 (p42), but not of ERK1 (p44), in lung neutrophils. ERK1, ERK2, and MEK1/2 were not activated in peripheral blood neutrophils after hemorrhage or endotoxemia. Inhibition of xanthine oxidase led to further increase in the activation of MEK1/2 and ERK2 in lung neutrophils after hemorrhage, but not after endotoxemia. Alpha-adrenergic blockade before hemorrhage resulted in increased activation in lung neutrophils of MEK1/2, ERK1, ERK2, and CREB, but decreased activation of NF-kappa B. In contrast, alpha-adrenergic blockade before endotoxemia was associated with decreased activation of MEK1/2, ERK2, and CREB, but increased activation of NF-kappa B. Beta-adrenergic blockade before hemorrhage did not alter MEK1/2 or ERK1 activation in lung neutrophils, but decreased activation of ERK2 and CREB, while increasing activation of NF-kappa B. Beta-adrenergic inhibition before endotoxemia did not affect activation of MEK1/2, ERK1, ERK2, CREB, or NF-kappa B. These data indicate that the pathways leading to lung neutrophil activation after hemorrhage are different from those induced by endotoxemia.

  19. Effects of pyridoxine on a high-fat diet-induced reduction of cell proliferation and neuroblast differentiation depend on cyclic adenosine monophosphate response element binding protein in the mouse dentate gyrus.

    Yoo, Dae Young; Kim, Woosuk; Yoo, Ki-Yeon; Nam, Sung Min; Chung, Jin Young; Yoon, Yeo Sung; Won, Moo-Ho; Hwang, In Koo

    2012-08-01

    In this study, we challenged pyridoxine to mice fed a high-fat diet (HFD) and investigated the effects of pyridoxine on HFD-induced phenotypes such as blood glucose, reduction of cell proliferation and neuroblast differentiation in the dentate gyrus using Ki67 and doublecortin (DCX), respectively. Mice were fed a commercially available low-fat diet (LFD) as control diet or HFD (60% fat) for 8 weeks. After 5 weeks of LFD or HFD treatment, 350 mg/kg pyridoxine was administered for 3 weeks. The administration of pyridoxine significantly decreased body weight in the HFD-treated group. In addition, there were no significant differences in hepatic histology and pancreatic insulin-immunoreactive (-ir) and glucagon-ir cells of the HFD-treated group after pyridoxine treatment. In the HFD-fed group, Ki67-positive nuclei and DCX-ir neuroblasts were significantly decreased in the dentate gyrus compared with those in the LFD-fed mice. However, the administration of pyridoxine significantly increased Ki67-positive nuclei and DCX-ir neuroblasts in the dentate gyrus in both LFD- and HFD-fed mice. In addition, the administration of pyridoxine significantly increased the protein levels of glutamic acid decarboxylase 67 (GAD67) and brain-derived neurotrophic factor (BDNF) and the immunoreactivity of phosphorylated cyclic AMP response element binding protein (pCREB) compared with the vehicle-treated LFD- and HFD-fed mice. In contrast, the administration of pyridoxine significantly decreased HFD-induced malondialdehyde (MDA) levels in the hippocampus. These results showed that pyridoxine supplement reduced the HFD-induced reduction of cell proliferation and neuroblast differentiation in the dentate gyrus via controlling the levels of GAD67, pCREB, BDNF, and MDA.

  20. Identification of cholinergic and non-cholinergic neurons in the pons expressing phosphorylated cyclic adenosine monophosphate response element-binding protein as a function of rapid eye movement sleep.

    Datta, S; Siwek, D F; Stack, E C

    2009-09-29

    Recent studies have shown that in the pedunculopontine tegmental nucleus (PPT), increased neuronal activity and kainate receptor-mediated activation of intracellular protein kinase A (PKA) are important physiological and molecular steps for the generation of rapid eye movement (REM) sleep. In the present study performed on rats, phosphorylated cyclic AMP response element-binding protein (pCREB) immunostaining was used as a marker for increased intracellular PKA activation and as a reflection of increased neuronal activity. To identify whether activated cells were either cholinergic or noncholinergic, the PPT and laterodorsal tegmental nucleus (LDT) cells were immunostained for choline acetyltransferase (ChAT) in combination with pCREB or c-Fos. The results demonstrated that during high rapid eye movement sleep (HR, approximately 27%), significantly higher numbers of cells expressed pCREB and c-Fos in the PPT, of which 95% of pCREB-expressing cells were ChAT-positive. With HR, the numbers of pCREB-positive cells were also significantly higher in the medial pontine reticular formation (mPRF), pontine reticular nucleus oral (PnO), and dorsal subcoeruleus nucleus (SubCD) but very few in the locus coeruleus (LC) and dorsal raphe nucleus (DRN). Conversely, with low rapid eye movement sleep (LR, approximately 2%), the numbers of pCREB expressing cells were very few in the PPT, mPRF, PnO, and SubCD but significantly higher in the LC and DRN. The results of regression analyses revealed significant positive relationships between the total percentages of REM sleep and numbers of ChAT+/pCREB+ (Rsqr=0.98) cells in the PPT and pCREB+ cells in the mPRF (Rsqr=0.88), PnO (Rsqr=0.87), and SubCD (Rsqr=0.84); whereas significantly negative relationships were associated with the pCREB+ cells in the LC (Rsqr=0.70) and DRN (Rsqr=0.60). These results provide evidence supporting the hypothesis that during REM sleep, the PPT cholinergic neurons are active, whereas the LC and DRN neurons are

  1. Temporal variations of adenosine metabolism in human blood.

    Chagoya de Sánchez, V; Hernández-Muñoz, R; Suárez, J; Vidrio, S; Yáñez, L; Aguilar-Roblero, R; Oksenberg, A; Vega-González, A; Villalobos, L; Rosenthal, L; Fernández-Cancino, F; Drucker-Colín, R; Díaz-Muñoz, M

    1996-08-01

    Eight diurnally active (06:00-23:00 h) subjects were adapted for 2 days to the room conditions where the experiments were performed. Blood sampling for adenosine metabolites and metabolizing enzymes was done hourly during the activity span and every 30 min during sleep. The results showed that adenosine and its catabolites (inosine, hypoxanthine, and uric acid), adenosine synthesizing (S-adenosylhomocysteine hydrolase and 5'-nucleotidase), degrading (adenosine deaminase) and nucleotide-forming (adenosine kinase) enzymes as well as adenine nucleotides (AMP, ADP, and ATP) undergo statistically significant fluctuations (ANOVA) during the 24 h. However, energy charge was invariable. Glucose and lactate chronograms were determined as metabolic indicators. The same data analyzed by the chi-square periodogram and Fourier series indicated ultradian oscillatory periods for all the metabolites and enzymatic activities determined, and 24-h oscillatory components for inosine, hypoxanthine, adenine nucleotides, glucose, and the activities of SAH-hydrolase, 5'-nucleotidase, and adenosine kinase. The single cosinor method showed significant oscillatory components exclusively for lactate. As a whole, these results suggest that adenosine metabolism may play a role as a biological oscillator coordinating and/or modulating the energy homeostasis and physiological status of erythrocytes in vivo and could be an important factor in the distribution of purine rings for the rest of the organism.

  2. Vasoconstrictor and vasodilator effects of adenosine in the kidney

    Hansen, Pernille B; Schnermann, Jurgen

    2003-01-01

    Adenosine is an ATP breakdown product that in most vessels causes vasodilatation and that contributes to the metabolic control of organ perfusion, i.e., to the match between oxygen demand and oxygen delivery. In the renal vasculature, in contrast, adenosine can produce vasoconstriction, a respons...... activation from changes in vascular adenosine concentration, a characteristic that is ideally suited for the role of renal adenosine as a paracrine factor in the control of glomerular function.......Adenosine is an ATP breakdown product that in most vessels causes vasodilatation and that contributes to the metabolic control of organ perfusion, i.e., to the match between oxygen demand and oxygen delivery. In the renal vasculature, in contrast, adenosine can produce vasoconstriction, a response...... that has been suggested to be an organ-specific version of metabolic control designed to restrict organ perfusion when transport work increases. However, the vasoconstriction elicited by an intravenous infusion of adenosine is only short lasting, being replaced within 1-2 min by vasodilatation. It appears...

  3. Adenosine-A1 receptor agonist induced hyperalgesic priming type II.

    Araldi, Dioneia; Ferrari, Luiz F; Levine, Jon D

    2016-03-01

    We have recently shown that repeated exposure of the peripheral terminal of the primary afferent nociceptor to the mu-opioid receptor (MOR) agonist DAMGO ([D-Ala, N-Me-Phe, Gly-ol]-enkephalin acetate salt) induces a model of transition to chronic pain that we have termed type II hyperalgesic priming. Similar to type I hyperalgesic priming, there is a markedly prolonged response to subsequent administration of proalgesic cytokines, prototypically prostaglandin E2 (PGE2). However, type II hyperalgesic priming differs from type I in being rapidly induced, protein kinase A (PKA), rather than PKCε dependent, not reversed by a protein translation inhibitor, occurring in female as well as in male rats, and isolectin B4-negative neuron dependent. We report that, as with the repeated injection of a MOR agonist, the repeated administration of an agonist at the A1-adenosine receptor, also a Gi-protein coupled receptor, N-cyclopentyladenosine (CPA), also produces priming similar to DAMGO-induced type II hyperalgesic priming. In this study, we demonstrate that priming induced by repeated exposure to this A1-adenosine receptor agonist shares the same mechanisms, as MOR-agonist induced priming. However, the prolongation of PGE2 hyperalgesia induced by repeated administration of CPA depends on G-protein αi subunit activation, differently from DAMGO-induced type II priming, in which it depends on the β/γ subunit. These data implicate a novel form of Gi-protein signaling pathway in the type II hyperalgesic priming induced by repeated administration of an agonist at A1-adenosine receptor to the peripheral terminal of the nociceptor.

  4. Increased Cortical Extracellular Adenosine Correlates with Seizure Termination

    Van Gompel, Jamie J.; Bower, Mark R.; Worrell, Gregory A.; Stead, Matt; Chang, Su-Youne; Goerss, Stephan J.; Kim, Inyong; Bennet, Kevin E.; Meyer, Fredric B.; Marsh, W. Richard; Blaha, Charles D.; Lee, Kendall H.

    2014-01-01

    Objective Seizures are currently defined by their electrographic features. However, neuronal networks are intrinsically dependent upon neurotransmitters of which little is known regarding their peri-ictal dynamics. Evidence supports adenosine as having a prominent role in seizure termination, as its administration can terminate and reduce seizures in animal models. Further, microdialysis studies in humans suggest adenosine is elevated peri-ictally, but the relationship to the seizure is obscured by its temporal measurement limitations. Because electrochemical techniques can provide vastly superior temporal resolution, we test the hypothesis that extracellular adenosine concentrations rise during seizure termination in an animal model and humans using electrochemistry. Methods White farm swine (n=45) were used in an acute cortical model of epilepsy and 10 human epilepsy patients were studied during intraoperative electrocorticography (Ecog). Wireless Instantaneous Neurotransmitter Concentration Sensor (WINCS) based fast scan cyclic voltametry (FSCV) and fixed potential amperometry were obtained utilizing an adenosine specific triangular waveform or biosensors respectively. Results Simultaneous Ecog and electrochemistry demonstrated an average adenosine rise of 260% compared to baseline at 7.5 ± 16.9 seconds with amperometry (n=75 events) and 2.6 ± 11.2 seconds with FSCV (n=15 events) prior to electrographic seizure termination. In agreement with these animal data, adenosine elevation prior to seizure termination in a human patient utilizing FSCV was also seen. Significance Simultaneous Ecog and electrochemical recording supports the hypothesis that adenosine rises prior to seizure termination, suggesting that adenosine itself may be responsible for seizure termination. Future work using intraoperative WINCS based FSCV recording may help to elucidate the precise relationship between adenosine and seizure termination. PMID:24483230

  5. Adenosine A1 Receptor Suppresses Tonic GABAA Receptor Currents in Hippocampal Pyramidal Cells and in a Defined Subpopulation of Interneurons.

    Rombo, Diogo M; Dias, Raquel B; Duarte, Sofia T; Ribeiro, Joaquim A; Lamsa, Karri P; Sebastião, Ana M

    2016-03-01

    Adenosine is an endogenous neuromodulator that decreases excitability of hippocampal circuits activating membrane-bound metabotropic A1 receptor (A1R). The presynaptic inhibitory action of adenosine A1R in glutamatergic synapses is well documented, but its influence on inhibitory GABAergic transmission is poorly known. We report that GABAA receptor (GABAAR)-mediated tonic, but not phasic, transmission is suppressed by A1R in hippocampal neurons. Adenosine A1R activation strongly inhibits GABAAR agonist (muscimol)-evoked currents in Cornu Ammonis 1 (CA1) pyramidal neurons and in a specific subpopulation of interneurons expressing axonal cannabinoid receptor type 1. In addition, A1R suppresses tonic GABAAR currents measured in the presence of elevated ambient GABA as well as in naïve slices. The inhibition of GABAergic currents involves both protein kinase A (PKA) and protein kinase C (PKC) signaling pathways and decreases GABAAR δ-subunit expression. On the contrary, no A1R-mediated modulation was detected in phasic inhibitory postsynaptic currents evoked either by afferent electrical stimulation or by spontaneous quantal release. The results show that A1R modulates extrasynaptic rather than synaptic GABAAR-mediated signaling, and that this modulation selectively occurs in hippocampal pyramidal neurons and in a specific subpopulation of inhibitory interneurons. We conclude that modulation of tonic GABAAR signaling by adenosine A1R in specific neuron types may regulate neuronal gain and excitability in the hippocampus.

  6. Evaluation of Adenosine Triphosphate-Binding Cassette Transporter A1 (ABCA1) R219K and C-Reactive Protein Gene (CRP) +1059G/C Gene Polymorphisms in Susceptibility to Coronary Heart Disease.

    Li, Jing-Fang; Peng, Dian-Ying; Ling, Mei; Yin, Yong

    2016-08-25

    BACKGROUND This meta-analysis investigated the correlation of ABCA1 R219K and C-Reactive Protein Gene (CRP) +1059G/C gene polymorphisms with susceptibility to coronary heart disease (CHD). MATERIAL AND METHODS We searched PubMed, Springer link, Wiley, EBSCO, Ovid, Wanfang database, VIP database, and China National Knowledge Infrastructure (CNKI) databases to retrieve published studies by keyword. Searches were filtered using our stringent inclusion and exclusion criteria. Resultant high-quality data collected from the final selected studies were analyzed using Comprehensive Meta-analysis 2.0 software. Eleven case-control studies involving 3053 CHD patients and 3403 healthy controls met our inclusion criteria. Seven studies were conducted in Asian populations, 3 studies were done in Caucasian populations, and 1 was in an African population. RESULTS Our major finding was that ABCA1 R219K polymorphism increased susceptibility to CHD in allele model (OR=0.729, 95% CI=0.559~0.949, P=0.019) and dominant model (OR=0.698, 95% CI=0.507~0.961, P=0.027). By contrast, we were unable to find any significant association between the CRP +1059G/C polymorphism and susceptibility to CHD (allele model: OR=1.170, 95% CI=0.782~1.751, P=0.444; dominant model: OR=1.175, 95% CI=0.768~1.797, P=0.457). CONCLUSIONS This meta-analysis provides convincing evidence that polymorphism of ABCA1 R219K is associated with susceptibility to CHD while the CRP +1059G/C polymorphism appears to have no correlation with susceptibility to CHD.

  7. Adenosine and Preexcitation Variants: Reappraisal of Electrocardiographic Changes.

    Ali, Hussam; Lupo, Pierpaolo; Foresti, Sara; De Ambroggi, Guido; Epicoco, Gianluca; Fundaliotis, Angelica; Cappato, Riccardo

    2016-07-01

    Intravenous adenosine is a short-acting blocker of the atrioventricular node that has been used to unmask subtle or latent preexcitation, and also to enable catheter ablation in selected patients with absent or intermittent preexcitation. Depending on the accessory pathway characteristics, intravenous adenosine may produce specific electrocardiographic changes highly suggestive of the preexcitation variant. Herein, we view different ECG responses to this pharmacological test in various preexcitation patterns that were confirmed by electrophysiological studies. Careful analysis of electrocardiographic changes during adenosine test, with emphasis on P-delta interval, preexcitation degree, and atrioventricular block, can be helpful to diagnose the preexcitation variant/pattern.

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

    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.

  9. Possible mechanism of adenosine protection in carbon tetrachloride acute hepatotoxicity. Role of adenosine by-products and glutathione peroxidase.

    Chagoya de Sánchez, V; Hernández-Muñoz, R; Yáñez, L; Vidrio, S; Díaz-Muñoz, M

    1995-02-01

    Adenosine proved to be an effective hepatoprotector increasing the survival rate of rats receiving lethal doses of CCl4. Searching for the mechanism of action, we found that adenosine transiently prevents the necrotic liver damage associated to an acute CCl4 treatment. The antilipoperoxidative action of the nucleoside was evidenced by a decrease of TBA-reactive products and the diene conjugates elicited by the hepatotoxin. Adenosine's protective effect was demonstrated by reverting the decrease of cytochrome P-450 while preserved intact the activity of the microsomal enzyme glucose-6-phosphatase. CCl4 promoted an increase in the oxidant stress through an enhancement in oxidized glutathione levels. This action was also completely counteracted by the nucleoside. Adenosine was unable to prevent CCl4 activation and, even, increased .CCl3 formation in the presence of PBN in vivo. However, in the presence of the nucleoside, irreversible binding of 14CCl4 to the microsomal lipid fraction of the treated animals was decreased. These results suggest that adenosine protective action might be exerted at the level of the propagation reaction following CCl4 activation. Two possible mechanisms were associated to the nucleoside protection: (1) the peroxide-metabolyzed enzymes, GSH-per, showed a marked increase after 30 minutes of adenosine treatment, which was potentiated by the hepatotoxin, suggesting an important role of this enzyme in the nucleoside's action; (2) the adenosine catabolism induced an increase in uric acid level, and allopurinol, a purine metabolism inhibitor, prevented such elevation as well as the antilipoperoxidative action of adenosine and the increase of GSH-per associated with the nucleoside treatment. These facts strongly suggest that the protective effect elicited by adenosine is not a direct one, but rather is related to its catabolic products, such as uric acid, which has been recognized as a free radical scavenger.

  10. Adenosine kinase inhibition protects against cranial radiation-induced cognitive dysfunction

    Munjal M Acharya

    2016-06-01

    Full Text Available Clinical radiation therapy for the treatment of CNS cancers leads to unintended and debilitating impairments in cognition. Radiation-induced cognitive dysfunction is long lasting, however, the underlying molecular and cellular mechanisms are still not well established. Since ionizing radiation causes microglial and astroglial activation, we hypothesized that maladaptive changes in astrocyte function might be implicated in radiation-induced cognitive dysfunction. Among other gliotransmitters, astrocytes control the availability of adenosine, an endogenous neuroprotectant and modulator of cognition, via metabolic clearance through adenosine kinase (ADK. Adult rats exposed to cranial irradiation (10 Gy showed significant declines in performance of hippocampal-dependent cognitive function tasks (novel place recognition, novel object recognition, and contextual fear conditioning 1 month after exposure to ionizing radiation using a clinically relevant regimen. Irradiated rats spent less time exploring a novel place or object. Cranial irradiation also led to reduction in freezing behavior compared to controls in the fear conditioning task. Importantly, immunohistochemical analyses of irradiated brains showed significant elevation of ADK immunoreactivity in the hippocampus that was related to astrogliosis and increased expression of glial fibrillary acidic protein (GFAP. Conversely, rats treated with the ADK inhibitor 5-iodotubercidin (5-ITU, 3.1 mg/kg, i.p., for 6 days prior to cranial irradiation showed significantly improved behavioral performance in all cognitive tasks 1 month post exposure. Treatment with 5-ITU attenuated radiation-induced astrogliosis and elevated ADK immunoreactivity in the hippocampus. These results confirm an astrocyte-mediated mechanism where preservation of extracellular adenosine can exert neuroprotection also against radiation-induced pathology. These innovative findings link radiation-induced changes in cognition and CNS

  11. Rosuvastatin increases extracellular adenosine formation in humans in vivo: a new perspective on cardiovascular protection.

    Meijer, P; Oyen, W.J.G.; Dekker, D.; Broek, P.H.H. van den; Wouters, C.W.; Boerman, O.C.; Scheffer, G. J.; Smits, P; Rongen, G.A.P.J.M.

    2009-01-01

    OBJECTIVE: Statins may increase extracellular adenosine formation from adenosine monophosphate by enhancing ecto-5'-nucleotidase activity. This theory was tested in humans using dipyridamole-induced vasodilation as a read-out for local adenosine formation. Dipyridamole inhibits the transport of extracellular adenosine into the cytosol resulting in increased extracellular adenosine and subsequent vasodilation. In addition, we studied the effect of statin therapy in a forearm model of ischemia-...

  12. Inhibition of uptake of adenosine into human blood platelets

    Lips, J.P.M.; Sixma, J.J.; Trieschnigg, A.C.

    1980-01-01

    Adenosine transport into human blood platelets is mediated by two independent systems with different affinities. Both systems transport only purine nucleosides and no pyrimidine nucleosides. In experiments with differently substituted purine nucleosides, purines and analogues, differences in carrier

  13. Adenosine Deaminase Deficiency – More Than Just an Immunodeficiency

    Kathryn Victoria Whitmore; Hubert Bobby Gaspar

    2016-01-01

    Adenosine deaminase (ADA) deficiency is best known as a form of severe combined immunodeficiency (SCID) which results from mutations in the gene encoding adenosine deaminase. Affected patients present with clinical and immunological manifestations typical of a severe combined immunodeficiency. Therapies are currently available that can that target these immunological disturbances and treated patients show varying degrees of clinical improvement. However, there is now a growing body of evidenc...

  14. Low-dose adenosine stress echocardiography: Detection of myocardial viability

    Djordjevic-Dikic, Ana; Ostojic, Miodrag; Beleslin, Branko; Nedeljkovic, Ivana; Stepanovic, Jelena; Stojkovic, Sinisa; Petrasinovic, Zorica; Nedeljkovic, Milan; Saponjski, Jovica; Giga, Vojislav

    2003-01-01

    Objective The aim of this study was to evaluate the diagnostic potential of low-dose adenosine stress echocardiography in detection of myocardial viability. Background Vasodilation through low dose dipyridamole infusion may recruit contractile reserve by increasing coronary flow or by increasing levels of endogenous adenosine. Methods Forty-three patients with resting dyssynergy, due to previous myocardial infarction, underwent low-dose adenosine (80, 100, 110 mcg/kg/min in 3 minutes intervals) echocardiography test. Gold standard for myocardial viability was improvement in systolic thickening of dyssinergic segments of ≥ 1 grade at follow-up. Coronary angiography was done in 41 pts. Twenty-seven patients were revascularized and 16 were medically treated. Echocardiographic follow up data (12 ± 2 months) were available in 24 revascularized patients. Results Wall motion score index improved from rest 1.55 ± 0.30 to 1.33 ± 0.26 at low-dose adenosine (p < 0.001). Of the 257 segments with baseline dyssynergy, adenosine echocardiography identified 122 segments as positive for viability, and 135 as necrotic since no improvement of systolic thickening was observed. Follow-up wall motion score index was 1.31 ± 0.30 (p < 0.001 vs. rest). The sensitivity of adenosine echo test for identification of viable segments was 87%, while specificity was 95%, and diagnostic accuracy 90%. Positive and negative predictive values were 97% and 80%, respectively. Conclusion Low-dose adenosine stress echocardiography test has high diagnostic potential for detection of myocardial viability in the group of patients with left ventricle dysfunction due to previous myocardial infarction. Low dose adenosine stress echocardiography may be adequate alternative to low-dose dobutamine test for evaluation of myocardial viability. PMID:12812523

  15. Low-dose adenosine stress echocardiography: Detection of myocardial viability

    Nedeljkovic Milan

    2003-06-01

    Full Text Available Abstract Objective The aim of this study was to evaluate the diagnostic potential of low-dose adenosine stress echocardiography in detection of myocardial viability. Background Vasodilation through low dose dipyridamole infusion may recruit contractile reserve by increasing coronary flow or by increasing levels of endogenous adenosine. Methods Forty-three patients with resting dyssynergy, due to previous myocardial infarction, underwent low-dose adenosine (80, 100, 110 mcg/kg/min in 3 minutes intervals echocardiography test. Gold standard for myocardial viability was improvement in systolic thickening of dyssinergic segments of ≥ 1 grade at follow-up. Coronary angiography was done in 41 pts. Twenty-seven patients were revascularized and 16 were medically treated. Echocardiographic follow up data (12 ± 2 months were available in 24 revascularized patients. Results Wall motion score index improved from rest 1.55 ± 0.30 to 1.33 ± 0.26 at low-dose adenosine (p Conclusion Low-dose adenosine stress echocardiography test has high diagnostic potential for detection of myocardial viability in the group of patients with left ventricle dysfunction due to previous myocardial infarction. Low dose adenosine stress echocardiography may be adequate alternative to low-dose dobutamine test for evaluation of myocardial viability.

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

    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.

  17. 1-(beta-D-Erythrofuranosyl)adenosine.

    Kline, Paul C; Zhao, Hongqiu; Noll, Bruce C; Oliver, Allen G; Serianni, Anthony S

    2010-04-01

    The title compound, also known as beta-erythroadenosine, C(9)H(11)N(5)O(3), (I), a derivative of beta-adenosine, (II), that lacks the C5' exocyclic hydroxymethyl (-CH(2)OH) substituent, crystallizes from hot ethanol with two independent molecules having different conformations, denoted (IA) and (IB). In (IA), the furanose conformation is (O)T(1)-E(1) (C1'-exo, east), with pseudorotational parameters P and tau(m) of 114.4 and 42 degrees, respectively. In contrast, the P and tau(m) values are 170.1 and 46 degrees, respectively, in (IB), consistent with a (2)E-(2)T(3) (C2'-endo, south) conformation. The N-glycoside conformation is syn (+sc) in (IA) and anti (-ac) in (IB). The crystal structure, determined to a resolution of 2.0 A, of a cocrystal of (I) bound to the enzyme 5'-fluorodeoxyadenosine synthase from Streptomyces cattleya shows the furanose ring in a near-ideal (O)E (east) conformation (P = 90 degrees and tau(m) = 42 degrees) and the base in an anti (-ac) conformation.

  18. Metformin-mediated Bambi expression in Hepatic Stellate Cells induces pro-survival Wnt/β-catenin signaling

    Subramaniam, Nanthakumar; Sherman, Mara H.; Rao, Renuka; Wilson, Caroline; Coulter, Sally; Atkins, Annette R.; Evans, Ronald M.; Liddle, Christopher; Downes, Michael

    2012-01-01

    Adenosine monophosphate-activated protein kinase (AMPK) regulates lipid, cholesterol and glucose metabolism in specialized metabolic tissues, such as muscle, liver and adipose tissue. Agents that activate AMPK, such as metformin and AICAR, have beneficial effects on liver glucose and lipid metabolism. Additionally, AMPK activation in proliferating hepatic stellate cells (HSCs) induces growth arrest and inhibits hepatic fibrosis. As metformin and AICAR act in different ways to achieve their ef...

  19. Different efficacy of adenosine and NECA derivatives at the human A3 adenosine receptor: insight into the receptor activation switch.

    Dal Ben, Diego; Buccioni, Michela; Lambertucci, Catia; Kachler, Sonja; Falgner, Nico; Marucci, Gabriella; Thomas, Ajiroghene; Cristalli, Gloria; Volpini, Rosaria; Klotz, Karl-Norbert

    2014-01-15

    A3 Adenosine receptors are promising drug targets for a number of diseases and intense efforts are dedicated to develop selective agonists and antagonists of these receptors. A series of adenosine derivatives with 2-(ar)-alkynyl chains, with high affinity and different degrees of selectivity for human A3 adenosine receptors was tested for the ability to inhibit forskolin-stimulated adenylyl cyclase. All these derivatives are partial agonists at A3 adenosine receptors; their efficacy is not significantly modified by the introduction of small alkyl substituents in the N(6)-position. In contrast, the adenosine-5'-N-ethyluronamide (NECA) analogs of 2-(ar)-alkynyladenosine derivatives are full A3 agonists. Molecular modeling analyses were performed considering both the conformational behavior of the ligands and the impact of 2- and 5'-substituents on ligand-target interaction. The results suggest an explanation for the different agonistic behavior of adenosine and NECA derivatives, respectively. A sub-pocket of the binding site was analyzed as a crucial interaction domain for receptor activation.

  20. Functional expression of adenosine A2A and A3 receptors in the mouse dendritic cell line XS-106.

    Dickenson, John M; Reeder, Steve; Rees, Bob; Alexander, Steve; Kendall, Dave

    2003-08-01

    There is increasing evidence to suggest that adenosine receptors can modulate the function of cells involved in the immune system. For example, human dendritic cells derived from blood monocytes have recently been described to express functional adenosine A1, A2A and A3 receptors. Therefore, in the present study, we have investigated whether the recently established murine dendritic cell line XS-106 expresses functional adenosine receptors. The selective adenosine A3 receptor agonist 1-[2-chloro-6[[(3-iodophenyl)methyl]amino]-9H-purin-9-yl]-1-deoxy-N-methyl-beta-D-ribofuranuronamide (2-Cl-IB-MECA) inhibited forskolin-mediated [3H]cyclic AMP accumulation and stimulated concentration-dependent increases in p42/p44 mitogen-activated protein kinase (MAPK) phosphorylation. The selective adenosine A2A receptor agonist 4-[2-[[-6-amino-9-(N-ethyl-beta-D-ribofuranuronamidosyl)-9H-purin-2-yl]amino]ethyl]benzene-propanoic acid (CGS 21680) stimulated a robust increase in [3H]cyclic AMP accumulation and p42/p44 MAPK phosphorylation. In contrast, the selective adenosine A1 receptor agonist CPA (N6-cyclopentyladenosine) did not inhibit forskolin-mediated [3H]cyclic AMP accumulation or stimulate increases in p42/p44 MAPK phosphorylation. These observations suggest that XS-106 cells express functional adenosine A2A and A3 receptors. The non-selective adenosine receptor agonist 5'-N-ethylcarboxamidoadenosine (NECA) inhibited lipopolysaccharide-induced tumour necrosis factor-alpha (TNF-alpha) release from XS-106 cells in a concentration-dependent fashion. Furthermore, treatment with Cl-IB-MECA (1 microM) or CGS 21680 (1 microM) alone produced a partial inhibition of lipopolysaccharide-induced TNF-alpha release (when compared to NECA), whereas a combination of both agonists resulted in the inhibition of TNF-alpha release comparable to that observed with NECA alone. Treatment of cells with the adenosine A2A receptor selective antagonists 4-(2-[7-amino-2-(2-furyl)[1,2,4]triazolo[2,3-a

  1. Enhanced Diffusion of Molecular Motors in the Presence of Adenosine Triphosphate and External Force

    Shinagawa, Ryota; Sasaki, Kazuo

    2016-06-01

    The diffusion of a molecular motor in the presence of a constant external force is considered on the basis of a simple theoretical model. The motor is represented by a Brownian particle moving in a series of parabolic potentials placed periodically on a line, and the potential is switched stochastically from one parabola to another by a chemical reaction, which corresponds to the hydrolysis or synthesis of adenosine triphosphate (ATP) in motor proteins. It is found that the diffusion coefficient as a function of the force exhibits peaks. The mechanism of this diffusion enhancement and the possibility of observing it in F1-ATPase, a biological rotary motor, are discussed.

  2. Activation and modulation of cardiac poly-adenosine diphosphate ribose polymerase activity in a rat model of brain death.

    Brain, John G; Rostron, Anthony J; Dark, John H; Kirby, John A

    2008-05-15

    DNA damage during transplantation can activate poly-adenosine diphosphate ribose polymerase (PARP) resulting in the generation of polymers of adenosine diphosphate-ribose (PAR). Excessive linkage of PAR to nuclear proteins can induce cell death, thereby limiting the function of transplanted organs. This study uses a rat model of brain death to determine the profile of PARP activation and whether mechanisms that lead to cell death can be ameliorated by appropriate donor resuscitation. The expression of PAR-linked nuclear proteins within cardiac myocytes was greatly increased after the induction of donor brain death. Importantly, infusion of noradrenaline or vasopressin to normalize the chronic hypotension produced by brain death reduced the expression of PAR to a level below baseline. These data suggest that chronic hypotension after donor brain death has the potential to limit cardiac function through the activation of PARP; however, this early cause of graft damage can be mitigated by appropriate donor resuscitation.

  3. Role of A3 adenosine receptor in diabetic neuropathy.

    Yan, Heng; Zhang, Enshui; Feng, Chang; Zhao, Xin

    2016-10-01

    Neuropathy is the most common diabetic complication. Although the A1 and A2A adenosine receptors are important pharmacological targets in alleviating diabetic neuropathy, the role of the A3 adenosine receptor remains unknown. Because the A3 adenosine receptor regulates pain induced by chronic constriction injury or chemotherapy, its stimulation might also attenuate diabetic neuropathy. This study examines the effects of systemic treatment with the A3 adenosine receptor agonist 1-deoxy-1-[6-[[(3-iodophenyl)methyl]amino]-9H-purin-9-yl]-N-methyl-β-d-ribofuranuronamide (IB-MECA) on diabetic neuropathy and explores the putative mechanisms underlying its pharmacological effects. We show that IB-MECA alleviated mechanical hyperalgesia and thermal hypoalgesia in mice 2 weeks but not 4 weeks after streptozocin (STZ) treatment. Furthermore, IB-MECA prevented the reduction in sciatic motor nerve conduction velocity and sensory nerve conduction velocity in diabetic mice 2 weeks but not 4 weeks after STZ treatment. Similarly, IB-MECA inhibited the activation of nuclear factor-κB and decreased the generation of tumor necrosis factor-α in the spinal cord of mice 2 weeks but not 4 weeks after STZ treatment. These phenomena were associated with reduction of A3 adenosine receptor expression in the spinal cord after long-term diabetes. Our results suggest that the A3 adenosine receptor plays a critical role in regulating diabetic neuropathy and that reduction in A3 adenosine receptor expression/function might contribute to the progression of diabetic neuropathy. © 2016 Wiley Periodicals, Inc.

  4. The effects of N-acylhomoserine lactones, β-lactam antibiotics and adenosine on biofilm formation in the multi-β-lactam antibiotic-resistant bacterium Acidovorax sp. strain MR-S7.

    Kusada, Hiroyuki; Hanada, Satoshi; Kamagata, Yoichi; Kimura, Nobutada

    2014-07-01

    Bacteria in the natural ecosystem frequently live as adherent communities called biofilms. Some chemical compounds are known to affect biofilm formation. We investigated the effect of exogenous small molecules, N-acylhomoserine lactones (AHLs), β-lactam antibiotics, and adenosine, on biofilm formation in the β-lactam antibiotic-resistant bacterium Acidovorax sp. strain MR-S7. Biofilm formation was induced by the addition of various types of AHL isomers and β-lactam antibiotics, whereas the addition of adenosine strongly interfered with the biofilm formation. A gene (macP) encoding adenosine deaminase (that converts adenosine to inosine controlling intracellular adenosine concentration) was successfully cloned from MR-S7 genome and heterologously expressed in Escherichia coli. The purified MacP protein clearly catalyzed the deamination of adenosine to produce inosine. A transcriptional analysis revealed that biofilm-inducing molecules, an AHL and a β-lactam antibiotic, strongly induced not only biofilm formation but also adenosine deaminase gene expression, suggesting that an elaborate gene regulation network for biofilm formation is present in the β-lactam antibiotic-resistant bacterium studied here.

  5. ALTERED EXPRESSION AND FUNCTIONALITY OF A2A ADENOSINE RECEPTORS IN HUNTINGTON’S DISEASE AND OTHER POLYGLUTAMINE DISORDERS

    Vincenzi, Fabrizio

    2009-01-01

    Several studies have suggested the possible involvement of A2A adenosine receptors in the pathogenesis of neuronal disorders, including Huntington’s disease. Huntington’s disease is an inherited neurodegenerative disease clinically characterized by motor, cognitive and behavioural impairments. The genetic cause of the disease is the expanded CAG triplet in a gene coding for huntingtin, a protein involved in several physiological processes. Huntington’s disease affects primarly ...

  6. Amplified fluorescence detection of adenosine via catalyzed hairpin assembly and host-guest interactions between β-cyclodextrin polymer and pyrene.

    Huang, Haihua; Yang, Xiaohai; Wang, Kemin; Wang, Qing; Guo, Qiuping; Huang, Jin; Liu, Jianbo; Song, Chunxia

    2016-04-21

    Nowadays, enzyme-free nucleic acid-based signal amplification strategies are frequently utilized in the design of biosensors due to their excellent sensitivity. Developing more extended analytical methods is fundamental for basic studies in the biological and biomedical fields. Herein, we introduce an enzyme-free amplified detection strategy for the small molecule adenosine. The approach is based on adenosine-aptamer binding triggered catalyzed hairpin assembly and host-guest interactions between β-cyclodextrin polymer (β-CDP) and pyrene. Two hairpin probes (probe H1 and probe H2) and an aptamer-trigger/inhibitor duplex probe were employed in the system and the pyrene-labeled probe H1 was chosen as the signal unit. In the absence of adenosine, the aptamer-trigger was inhibited by the inhibitor strand. The hairpin probes were in the closed hairpin formation without activation of the trigger strand. Pyrene labeled at the 5'-termini of the single-stranded stem of probe H1 could be easily trapped in the hydrophobic cavity of β-CDP because of weak steric hindrance, leading to a significant fluorescence enhancement. Once the hairpin assembly was catalyzed by the adenosine-aptamer binding event, a hybridized DNA duplex H1/H2 was created continuously. Pyrene labeled at the 5'-termini of the DNA duplex H1/H2 finds it difficult to enter the cavity of β-CDP due to steric hindrance, leading to a weaker fluorescence signal. Thus, the target could be detected by this simple mix-and-detect amplification method without a need for expensive and perishable protein enzymes. As low as 42 nM of adenosine was detected by this assay, which is comparable to that of some reported colorimetric methods. Meanwhile, the proposed method was further successfully applied to detect adenosine in human serum samples, showing great potential for adenosine detection from complex fluids.

  7. Intracoronary adenosine improves myocardial perfusion in late reperfused myocardial infarction

    2008-01-01

    Background Myocardial perfusion associates with clinical syndromes and prognosis.Adenosine could improve myocardial perfusion of acute myocardial infarction within 6 hours,but few data are available on late perfusion of myocardial infarction (MI).This study aimed at quantitatively evaluating the value of intracoronary adenosine improving myocardial perfusion in late reperfused MI with myocardial contrast echocardiography(MCE).Methods Twenty-six patients with anterior wall infarcts were divided randomly into 2 groups:adenosine group(n=12) and normal saline group(n=14).Their history of myocardial infarction was about 3-12 weeks.Adenosine or normalsaline was given when the guiding wire crossed the lesion through percutaneous coronary intervention(PCI),then the balloon was dilated and stent(Cypher/Cypher select)was implanted at the lesion.Contrast pulse sequencing MCE with Sonovue contrast via the coronary route was done before PCI and 30 minutes after PCI.Video densitometry and contrast filled-blank area were calculated with the CUSQ off-line software.Heart function and cardiac events were followed up within 30 days.Results Perfusion in the segments of the criminal occlusive coronary artery in the adenosine group was better than that in the saline group(5.71±0.29 vs 4.95±1.22,P<0.05).Ischemic myocardial segment was deminished significantly afterPCI,but the meliorated area was bigger in the adenosine group than in the saline group((1.56±0.60)cm2 vs(1.02±0.56) cm2,P<0.05).The video densitometry in critical segments was also improved significantly in the adenosine group (5.53±0.36 vs 5.26±0.35,P<0.05).Left ventricular ejection fraction(LVEF)was improved in all patients after PCI,but EF was not significant between the two groups((67±6)% vs(62±7)%,P>0.05).There was no in-hospital or 30-day major adverse cardiac event(MACE)in the adenosine group but 3 MACE in the saline group in 30 days after PCI.Conclusions Adenosine could improve myocardial microvascular

  8. Adenosine A2B receptor-mediated leukemia inhibitory factor release from astrocytes protects cortical neurons against excitotoxicity

    Moidunny Shamsudheen

    2012-08-01

    Full Text Available Abstract Background Neuroprotective and neurotrophic properties of leukemia inhibitory factor (LIF have been widely reported. In the central nervous system (CNS, astrocytes are the major source for LIF, expression of which is enhanced following disturbances leading to neuronal damage. How astrocytic LIF expression is regulated, however, has remained an unanswered question. Since neuronal stress is associated with production of extracellular adenosine, we investigated whether LIF expression in astrocytes was mediated through adenosine receptor signaling. Methods Mouse cortical neuronal and astrocyte cultures from wild-type and adenosine A2B receptor knock-out animals, as well as adenosine receptor agonists/antagonists and various enzymatic inhibitors, were used to study LIF expression and release in astrocytes. When needed, a one-way analysis of variance (ANOVA followed by Bonferroni post-hoc test was used for statistical analysis. Results We show here that glutamate-stressed cortical neurons induce LIF expression through activation of adenosine A2B receptor subtype in cultured astrocytes and require signaling of protein kinase C (PKC, mitogen-activated protein kinases (MAPKs: p38 and ERK1/2, and the nuclear transcription factor (NF-κB. Moreover, LIF concentration in the supernatant in response to 5′-N-ethylcarboxamide (NECA stimulation was directly correlated to de novo protein synthesis, suggesting that LIF release did not occur through a regulated release pathway. Immunocytochemistry experiments show that LIF-containing vesicles co-localize with clathrin and Rab11, but not with pHogrin, Chromogranin (CgA and CgB, suggesting that LIF might be secreted through recycling endosomes. We further show that pre-treatment with supernatants from NECA-treated astrocytes increased survival of cultured cortical neurons against glutamate, which was absent when the supernatants were pre-treated with an anti-LIF neutralizing antibody. Conclusions

  9. Differential adenosine sensitivity of diaphragm and skeletal muscle arterioles.

    Aaker, Aaron; Laughlin, M H

    2002-09-01

    The hyperemic response in exercising skeletal muscle is dependent on muscle fiber-type composition and fiber recruitment patterns, but the vascular control mechanisms producing exercise hyperemia in skeletal muscle remain poorly understood. The purpose of this study was to test the hypothesis that arterioles from white, low-oxidative skeletal muscle are less responsive to adenosine-induced dilation than are arterioles from diaphragm (Dia) and red, high-oxidative skeletal muscle. Second-order arterioles (2As) were isolated from the white portion of gastrocnemius muscle (WG; low-oxidative, fast-twitch muscle tissue) and two types of high-oxidative skeletal muscle [Dia and red portion of gastrocnemius muscle (RG)] of rats. Results reveal that 2As from all three types of muscle dilated in response to the endothelium-dependent dilator acetylcholine (WG: 48 +/- 3%, Dia: 51 +/- 3%, RG: 74 +/- 3%). In contrast, adenosine dilated only 2As from WG (48 +/- 4%) and Dia (46 +/- 5%) but not those from RG (5 +/- 5%). Thus adenosine-induced dilator responses differed among 2As of these different types of muscle tissue. However, the results do not support our hypothesis because 2As from Dia and WG dilated in response to adenosine, whereas 2As from RG did not. We conclude that the adenosine responsiveness of 2As from rat skeletal muscle cannot be predicted only by the fiber-type composition or oxidative capacity of the skeletal muscle tissue wherein the arteriole lies.

  10. Adenosine triphosphate inhibits melatonin synthesis in the rat pineal gland.

    Souza-Teodoro, Luis Henrique; Dargenio-Garcia, Letícia; Petrilli-Lapa, Camila Lopes; Souza, Ewerton da Silva; Fernandes, Pedro A C M; Markus, Regina P; Ferreira, Zulma S

    2016-03-01

    Adenosine triphosphate (ATP) is released onto the pinealocyte, along with noradrenaline, from sympathetic neurons and triggers P2Y1 receptors that enhance β-adrenergic-induced N-acetylserotonin (NAS) synthesis. Nevertheless, the biotransformation of NAS into melatonin, which occurs due to the subsequent methylation by acetylserotonin O-methyltransferase (ASMT; EC 2.1.1.4), has not yet been evaluated in the presence of purinergic stimulation. We therefore evaluated the effects of purinergic signaling on melatonin synthesis induced by β-adrenergic stimulation. ATP increased NAS levels, but, surprisingly, inhibited melatonin synthesis in an inverse, concentration-dependent manner. Our results demonstrate that enhanced NAS levels, which depend on phospholipase C (PLC) activity (but not the induction of gene transcription), are a post-translational effect. By contrast, melatonin reduction is related to an ASMT inhibition of expression at both the gene transcription and protein levels. These results were independent of nuclear factor-kappa B (NF-kB) translocation. Neither the P2Y1 receptor activation nor the PLC-mediated pathway was involved in the decrease in melatonin, indicating that ATP regulates pineal metabolism through different mechanisms. Taken together, our data demonstrate that purinergic signaling differentially modulates NAS and melatonin synthesis and point to a regulatory role for ATP as a cotransmitter in the control of ASMT, the rate-limiting enzyme in melatonin synthesis. The endogenous production of melatonin regulates defense responses; therefore, understanding the mechanisms involving ASMT regulation might provide novel insights into the development and progression of neurological disorders since melatonin presents anti-inflammatory, neuroprotective, and neurogenic effects.

  11. CSF ADENOSINE DEAMINASE (ADA ACTIVITY IN PATIENTS WITH MENINGITIS

    Justin

    2016-05-01

    Full Text Available Meningitis is inflammation of the meninges (pia, arachnoid and dura mater covering the brain and the spinal cord. ADA is an enzyme in the purine salvage pathway which is found in abundance in active T-lymphocytes. Hence, an attempt was made to estimate the CSF ADA level in patients with suspected meningitis and throw light on its use in differentiating the various types of meningitis. AIMS AND OBJECTIVES To estimate the level of CSF adenosine deaminase level in different types of meningitis. To assess its usefulness in differentiating the various types (bacterial, viral and tuberculous of meningitis. MATERIALS AND METHODS The study was conducted at the medical wards of Govt. Rajaji Hospital, Madurai, a prospective analytical study from a period of April 2012 to September 2012. OBSERVATION AND RESULTS Tuberculous meningitis occurred more in the age group of 21–40 years. Bacterial meningitis was seen mainly in patients < 20 years of age. Viral meningitis was seen in all age groups. CSF ADA level was highest in tuberculous meningitis, the mean value being 24.5 U/L. The mean value of ADA in bacterial meningitis was 4.54 U/L and viral meningitis patients had lowest mean ADA value of 2.65 U/L. CONCLUSION In our study, 50 patients with meningitis admitted in Government Rajaji Hospital from April 2012 to September 2012 were evaluated. Meningitis predominantly affected people in the age group of 20-40 years in our study with a male: female ratio of 1.9:1. Cases of tuberculous meningitis constituted 48% of the study group and bacterial and viral meningitis were 26% each. CSF protein values were higher and sugar values lower in patients with tuberculous and bacterial meningitis. CSF cell counts were higher in patients with bacterial meningitis.

  12. GABAB and adenosine receptors mediate enhancement of the K+ current, IAHP, by reducing adenylyl cyclase activity in rat CA3 hippocampal neurons.

    Gerber, U; Gähwiler, B H

    1994-11-01

    1. Gamma-aminobuturic acid-B (GABAB) and adenosine A1 receptors, which are expressed in hippocampal pyramidal cells, are linked to pertussis toxin-sensitive G-proteins known to be coupled negatively to the enzyme adenylyl cyclase. This study investigates the electrophysiological consequences of adenylyl cyclase inhibition in response to stimulation of these receptors. 2. Single-electrode voltage-clamp recordings were obtained from CA3 pyramidal cells in rat hippocampal slice cultures in presence of tetrodotoxin. The calcium-dependent potassium current (IAHP), which is very sensitive to intracellular levels of adenosine 3',5'-cyclic monophosphate (cAMP), was used as an electrophysiological indicator of adenylyl cyclase activity. 3. Application of baclofen (10 microM), a selective agonist at GABAB receptors, or adenosine (50 microM) each resulted in a transient decrease followed by a significant enhancement in the amplitude of evoked IAHP. The initial reduction in amplitude of IAHP probably reflects inadequacies in voltage clamp of electronically distant dendritic sites, due to the shunting caused by concomitant activation of potassium conductance by baclofen/adenosine. Comparable increases in membrane conductance in response to the GABAA agonist, muscimol, caused a similar reduction in IAHP. The enhancement of IAHP is consistent with an inhibition of constitutively active adenylyl cyclase. 4. The receptor mediating the responses to adenosine was identified as belonging to the A1 subtype on the basis of its sensitivity to the selective antagonist 8-cyclopentyl-1,3-dipropylxanthine.(ABSTRACT TRUNCATED AT 250 WORDS)

  13. Topological sub-structural molecular design (TOPS-MODE): a useful tool to explore key fragments of human A3 adenosine receptor ligands.

    Saíz-Urra, Liane; Teijeira, Marta; Rivero-Buceta, Virginia; Helguera, Aliuska Morales; Celeiro, Maria; Terán, Ma Carmen; Besada, Pedro; Borges, Fernanda

    2016-02-01

    Adenosine regulates tissue function by activating four G-protein-coupled adenosine receptors (ARs). Selective agonists and antagonists for A3 ARs have been investigated for the treatment of a variety of immune disorders, cancer, brain, and heart ischemic conditions. We herein present a QSAR study based on a Topological sub-structural molecular design (TOPS-MODE) approach, intended to predict the A3 ARs of a diverse dataset of 124 (94 training set/ 30 prediction set) adenosine derivatives. The final model showed good fit and predictive capability, displaying 85.1 % of the experimental variance. The TOPS-MODE approach afforded a better understanding and interpretation of the developed model based on the useful information extracted from the analysis of the contribution of different molecular fragments to the affinity.

  14. Correlation between blood adenosine metabolism and sleep in humans.

    Díaz-Muñoz, M; Hernández-Muñoz, R; Suárez, J; Vidrio, S; Yááñez, L; Aguilar-Roblero, R; Rosenthal, L; Villalobos, L; Fernández-Cancino, F; Drucker-Colín, R; Chagoya De Sanchez, V

    1999-01-01

    Blood adenosine metabolism, including metabolites and metabolizing enzymes, was studied during the sleep period in human volunteers. Searching for significant correlations among biochemical parameters found: adenosine with state 1 of slow-wave sleep (SWS); activity of 5'-nucleotidase with state 2 of SWS; inosine and AMP with state 3-4 of SWS; and activity of 5'-nucleotidase and lactate with REM sleep. The correlations were detected in all of the subjects that presented normal hypnograms, but not in those who had fragmented sleep the night of the experiment. The data demonstrate that it is possible to obtain information of complex brain operations such as sleep by measuring biochemical parameters in blood. The results strengthen the notion of a role played by adenosine, its metabolites and metabolizing enzymes, during each of the stages that constitute the sleep process in humans.

  15. Moderate exercise training promotes adaptations in coronary blood flow and adenosine production in normotensive rats

    Fernanda R. Roque

    2011-01-01

    Full Text Available OBJECTIVES: Aerobic exercise training prevents cardiovascular risks. Regular exercise promotes functional and structural adaptations that are associated with several cardiovascular benefits. The aim of this study is to investigate the effects of swimming training on coronary blood flow, adenosine production and cardiac capillaries in normotensive rats. METHODS: Wistar rats were randomly divided into two groups: control (C and trained (T. An exercise protocol was performed for 10 weeks and 60 min/day with a tail overload of 5% bodyweight. Coronary blood flow was quantified with a color microsphere technique, and cardiac capillaries were quantified using light microscopy. Adenine nucleotide hydrolysis was evaluated by enzymatic activity, and protein expression was evaluated by western blot. The results are presented as the means ± SEMs (p<0.05. RESULTS: Exercise training increased the coronary blood flow and the myocardial capillary-to-fiber ratio. Moreover, the circulating and cardiac extracellular adenine nucleotide hydrolysis was higher in the trained rats than in the sedentary rats due to the increased activity and protein expression of enzymes, such as E-NTPDase and 59- nucleotidase. CONCLUSIONS: Swimming training increases coronary blood flow, number of cardiac capillaries, and adenine nucleotide hydrolysis. Increased adenosine production may be an important contributor to the enhanced coronary blood flow and angiogenesis that were observed in the exercise-trained rats; collectively, these results suggest improved myocardial perfusion.

  16. Tween 20-stabilized gold nanoparticles combined with adenosine triphosphate-BODIPY conjugates for the fluorescence detection of adenosine with more than 1000-fold selectivity

    Hung, Szu-Ying; Shih, Ya-Chen [Department of Chemistry, National Sun Yat-sen University, Taiwan (China); Tseng, Wei-Lung, E-mail: tsengwl@mail.nsysu.edu.tw [Department of Chemistry, National Sun Yat-sen University, Taiwan (China); School of Pharmacy, College of Pharmacy, Kaohsiung Medical University, Taiwan (China); Center for Nanoscience and Nanotechnology, National Sun Yat-sen University, Taiwan (China); Center for Stem Cell Research, Kaohsiung Medical University, Taiwan (China)

    2015-02-01

    Graphical abstract: A simple, enzyme-free, label-free, sensitive and selective system was developed for detecting adenosine based on the use of Tween 20-stabilized gold nanoparticles as an efficient quencher for boron dipyrromethene-conjugated adenosine 5′-triphosphate and as a recognition element for adenosine. - Highlights: • The proposed method can detect adenosine with more than 1000-fold selectivity. • The analysis of adenosine is rapid (∼6 min) using the proposed method. • This method provided better sensitivity for adenosine as compared to aptamer-based sensors. • This method can be applied for the determination of adenosine in urine. - Abstract: This study describes the development of a simple, enzyme-free, label-free, sensitive, and selective system for detecting adenosine based on the use of Tween 20-stabilized gold nanoparticles (Tween 20-AuNPs) as an efficient fluorescence quencher for boron dipyrromethene-conjugated adenosine 5′-triphosphate (BODIPY-ATP) and as a recognition element for adenosine. BODIPY-ATP can interact with Tween 20-AuNPs through the coordination between the adenine group of BODIPY-ATP and Au atoms on the NP surface, thereby causing the fluorescence quenching of BODIPY-ATP through the nanometal surface energy transfer (NSET) effect. When adenosine attaches to the NP surface, the attached adenosine exhibits additional electrostatic attraction to BODIPY-ATP. As a result, the presence of adenosine enhances the efficiency of AuNPs in fluorescence quenching of BODIPY-ATP. The AuNP-induced fluorescence quenching of BODIPY-ATP progressively increased with an increase in the concentration of adenosine; the detection limit at a signal-to-noise ratio of 3 for adenosine was determined to be 60 nM. The selectivity of the proposed system was more than 1000-fold for adenosine over any adenosine analogs and other nucleotides. The proposed system combined with a phenylboronic acid-containing column was successfully applied to the

  17. Development of coronary vasospasm during adenosine-stress myocardial perfusion CT imaging

    Nam, Jeong Gu; Choi, Seong Hoon; Kang, Byeong Seong; Bang, Min Aeo; Kwon, Woon Jeong [Dept. of Radiology, Ulsan University Hospital, University of Ulsan College of Medicine, Ulsan (Korea, Republic of)

    2015-06-15

    Adenosine is a short-acting coronary vasodilator, and it is widely used during pharmacological stress myocardial perfusion imaging. It has a well-established safety profile, and most of its side effects are known to be mild and transient. Until now, coronary vasospasm has been rarely reported as a side effect of adenosine during or after adenosine stress test. This study reports a case of coronary vasospasm which was documented on stress myocardial perfusion CT imaging during adenosine stress test.

  18. Direct visualisation of internalization of the adenosine A3 receptor and localization with arrestin3 using a fluorescent agonist.

    Stoddart, Leigh A; Vernall, Andrea J; Briddon, Stephen J; Kellam, Barrie; Hill, Stephen J

    2015-11-01

    Fluorescence based probes provide a novel way to study the dynamic internalization process of G protein-coupled receptors (GPCRs). Recent advances in the rational design of fluorescent ligands for GPCRs have been used here to generate new fluorescent agonists containing tripeptide linkers for the adenosine A3 receptor. The fluorescent agonist BY630-X-(D)-A-(D)-A-G-ABEA was found to be a highly potent agonist at the adenosine A3 receptor in both reporter gene (pEC50 = 8.48 ± 0.09) and internalization assays (pEC50 = 7.47 ± 0.11). Confocal imaging studies showed that BY630-X-(D)-A-(D)-A-G-ABEA was internalized with A3 linked to yellow fluorescent protein, which was blocked by the competitive antagonist MRS1220. Internalization of untagged adenosine A3 could also be visualized with BY630-X-(D)-A-(D)-A-G-ABEA treatment. Further, BY630-X-(D)-A-(D)-A-G-ABEA stimulated the formation of receptor-arrestin3 complexes and was found to localize with these intracellular complexes. This highly potent agonist with excellent imaging properties should be a valuable tool to study receptor internalization. This article is part of the Special Issue entitled 'Fluorescent Tools in Neuropharmacology'.

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

    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

  20. Adenosine A(3) receptor-induced CCL2 synthesis in cultured mouse astrocytes

    Wittendorp, MC; Boddeke, HWGM; Biber, K

    2004-01-01

    During neuropathological conditions, high concentrations of adenosine are released, stimulating adenosine receptors in neurons and glial cells. It has recently been shown that stimulation of adenosine receptors in glial cells induces the release of neuroprotective substances such as NGF, S-100beta,

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

    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. Searching Inhibitors of Adenosine Kinase by Simulation Methods

    ZHU Rui-Xin; ZHANG Xing-Long; DONG Xi-Cheng; CHEN Min-Bo

    2006-01-01

    Searching new inhibitors of adenosine kinase (AK) is still drawing attention of experimental scientists. A better and solid model is here proposed by means of simulation methods from different ways, the direct analysis of receptor itself, the conventional 3D-QSAR methods and the integration of docking method and the conventional QSAR analysis.

  3. 21 CFR 864.7040 - Adenosine triphosphate release assay.

    2010-04-01

    ... device that measures the release of adenosine triphosphate (ATP) from platelets following aggregation. This measurement is made on platelet-rich plasma using a photometer and a luminescent firefly extract. Simultaneous measurements of platelet aggregation and ATP release are used to evaluate platelet...

  4. No role of interstitial adenosine in insulin-mediated vasodilation

    Dela, F; Stallknecht, B

    1999-01-01

    The mechanisms behind the vasodilatory effect of insulin are not fully understood, but nitric oxide plays an important role. We have investigated the possibility that insulin mediates vasodilatation in the human skeletal muscle via an increase in extracellular adenosine concentrations. In eight h...

  5. CD39/adenosine pathway is involved in AIDS progression.

    Maria Nikolova

    2011-07-01

    Full Text Available HIV-1 infection is characterized by a chronic activation of the immune system and suppressed function of T lymphocytes. Regulatory CD4+ CD25(high FoxP3+CD127(low T cells (Treg play a key role in both conditions. Here, we show that HIV-1 positive patients have a significant increase of Treg-associated expression of CD39/ENTPD1, an ectoenzyme which in concert with CD73 generates adenosine. We show in vitro that the CD39/adenosine axis is involved in Treg suppression in HIV infection. Treg inhibitory effects are relieved by CD39 down modulation and are reproduced by an adenosine-agonist in accordance with a higher expression of the adenosine A2A receptor on patients' T cells. Notably, the expansion of the Treg CD39+ correlates with the level of immune activation and lower CD4+ counts in HIV-1 infected patients. Finally, in a genetic association study performed in three different cohorts, we identified a CD39 gene polymorphism that was associated with down-modulated CD39 expression and a slower progression to AIDS.

  6. Striatal adenosine-cannabinoid receptor interactions in rats over-expressing adenosine A2A receptors.

    Chiodi, Valentina; Ferrante, Antonella; Ferraro, Luca; Potenza, Rosa Luisa; Armida, Monica; Beggiato, Sarah; Pèzzola, Antonella; Bader, Michael; Fuxe, Kjell; Popoli, Patrizia; Domenici, Maria Rosaria

    2016-03-01

    Adenosine A2A receptors (A2 A Rs) and cannabinoid CB1 receptors (CB1 Rs) are highly expressed in the striatum, where they functionally interact and form A2A /CB1 heteroreceptor complexes. We investigated the effects of CB1 R stimulation in a transgenic rat strain over-expressing A2 A Rs under the control of the neural-specific enolase promoter (NSEA2A rats) and in age-matched wild-type (WT) animals. The effects of the CB1 R agonist WIN 55,212-2 (WIN) were significantly lower in NSEA2A rats than in WT animals, as demonstrated by i) electrophysiological recordings of synaptic transmission in corticostriatal slices; ii) the measurement of glutamate outflow from striatal synaptosomes and iii) in vivo experiments on locomotor activity. Moreover, while the effects of WIN were modulated by both A2 A R agonist (CGS 21680) and antagonists (ZM 241385, KW-6002 and SCH-442416) in WT animals, the A2 A R antagonists failed to influence WIN-mediated effects in NSEA2A rats. The present results demonstrate that in rats with genetic neuronal over-expression of A2 A Rs, the effects mediated by CB1 R activation in the striatum are significantly reduced, suggesting a change in the stoichiometry of A2A and CB1 receptors and providing a strategy to dissect the involvement of A2 A R forming or not forming heteromers in the modulation of striatal functions. These findings add additional evidence for the existence of an interaction between striatal A2 A Rs and CB1 Rs, playing a fundamental role in the regulation of striatal functions. We studied A2A -CB1 receptor interaction in transgenic rats over-expressing adenosine A2A receptors under the control of the neuron-specific enolase promoter (NSEA2A ). In these rats, we demonstrated a reduced effect of the CB1 receptor agonist WIN 55,212-2 in the modulation of corticostriatal synaptic transmission and locomotor activity, while CB1 receptor expression level did not change with respect to WT rats. A reduction in the expression of A2A -CB1

  7. Feed-Forward Inhibition of CD73 and Upregulation of Adenosine Deaminase Contribute to the Loss of Adenosine Neuromodulation in Postinflammatory Ileitis

    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.

  8. Robust aptamer sol-gel solid phase microextraction of very polar adenosine from human plasma.

    Mu, Li; Hu, Xiangang; Wen, Jianping; Zhou, Qixing

    2013-03-01

    Conventional solid phase microextraction (SPME) has a limited capacity to extract very polar analytes, such as adenosine. To solve this problem, aptamer conjugating sol-gel methodology was coupled with an SPME fiber. According to the authors' knowledge, this is the first reported use of aptamer SPME. The fiber of aptamer sol-gel SPME with a mesoporous structure has high porosity, large surface area, and small water contact angle. Rather than employing direct entrapment, covalent immobilization was the dominant method of aptamer loading in sol-gel. Aptamer sol-gel fiber captured a specified analyte from among the analog molecules, thereby, exhibiting an excellent selective property. Compared with commercial SPME fibers, this aptamer fiber was suitable for extracting adenosine, presenting an extraction efficiency higher than 20-fold. The values of repeatability and reproducibility expressed by relative standard deviation were low (9.4%). Interestingly, the sol-gel network enhanced the resistance of aptamer SPME to both nuclease and nonspecific proteins. Furthermore, the aptamer sol-gel fiber was applied in human plasma with LOQ 1.5 μg/L, which is an acceptable level. This fiber also demonstrates durability and regeneration over 20-cycles without significant loss of efficiency. Given the various targets (from metal ions to biomacromolecules and cells) of aptamers, this methodology will extend the multi-domain applications of SPME.

  9. Protein

    ... Food Service Resources Additional Resources About FAQ Contact Protein Protein is found throughout the body—in muscle, ... the heart and respiratory system, and death. All Protein Isn’t Alike Protein is built from building ...

  10. Small-Animal PET Study of Adenosine A(1) Receptors in Rat Brain : Blocking Receptors and Raising Extracellular Adenosine

    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

    2011-01-01

    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-C-11-methyl-3-propyl-xanthine (C-11-MPDX) and PET. This study aims to test whether C-11-MPDX c

  11. Fast-scan Cyclic Voltammetry for the Characterization of Rapid Adenosine Release.

    Nguyen, Michael D; Venton, B Jill

    2015-01-01

    Adenosine is a signaling molecule and downstream product of ATP that acts as a neuromodulator. Adenosine regulates physiological processes, such as neurotransmission and blood flow, on a time scale of minutes to hours. Recent developments in electrochemical techniques, including fast-scan cyclic voltammetry (FSCV), have allowed direct detection of adenosine with sub-second temporal resolution. FSCV studies have revealed a novel mode of rapid signaling that lasts only a few seconds. This rapid release of adenosine can be evoked by electrical or mechanical stimulations or it can be observed spontaneously without stimulation. Adenosine signaling on this time scale is activity dependent; however, the mode of release is not fully understood. Rapid adenosine release modulates oxygen levels and evoked dopamine release, indicating that adenosine may have a rapid modulatory role. In this review, we outline how FSCV can be used to detect adenosine release, compare FSCV with other techniques used to measure adenosine, and present an overview of adenosine signaling that has been characterized using FSCV. These studies point to a rapid mode of adenosine modulation, whose mechanism and function will continue to be characterized in the future.

  12. Intracerebral adenosine infusion improves neurological outcome after transient focal ischemia in rats.

    Kitagawa, Hisashi; Mori, Atsushi; Shimada, Jun; Mitsumoto, Yasuhide; Kikuchi, Tetsuro

    2002-04-01

    Second Institute of New Drug Research, Otsuka Pharmaceutical Co., Ltd., Tokushima, Japan In order to elucidate the role of adenosine in brain ischemia, the possible protective effects of adenosine on ischemic brain injury were investigated in a rat model of brain ischemia both in vitro and in vivo. Exogenous adenosine dose-dependently rescued cortical neuronal cells from injury after glucose deprivation in vitro. Adenosine (1 mM) also significantly reduced hypoglycemia/hypoxia-induced glutamate release from the hippocampal slice. In a rat model of transient middle cerebral artery occlusion (MCAO), extracellular adenosine concentration was increased immediately after occlusion, and then returned to the baseline by 30 min after reperfusion. Adenosine infusion through a microdialysis probe into the ipsilateral striatum (1 mM adenosine, 2 microl min(-1), total 4.5 h from the occlusion to 3 h after reperfusion) showed a significant improvement in the neurological outcome, and about 25% reduction of infarct volume, although the effect did not reach statistical significance, compared with the vehicle-treated group at 20 h after 90 min of MCAO. These results demonstrated the neuroprotective effect of adenosine against ischemic brain injury both in vitro and in vivo, suggesting the possible therapeutic application of adenosine regulating agents, which inhibit adenosine uptake or metabolism to enhance or maintain extracellular endogenous adenosine levels, for stroke treatment.

  13. Adenosine transiently modulates stimulated dopamine release in the caudate-putamen via A1 receptors.

    Ross, Ashley E; Venton, B Jill

    2015-01-01

    Adenosine modulates dopamine in the brain via A1 and A2A receptors, but that modulation has only been characterized on a slow time scale. Recent studies have characterized a rapid signaling mode of adenosine that suggests a possible rapid modulatory role. Here, fast-scan cyclic voltammetry was used to characterize the extent to which transient adenosine changes modulate stimulated dopamine release (5 pulses at 60 Hz) in rat caudate-putamen brain slices. Exogenous adenosine was applied and dopamine concentration monitored. Adenosine only modulated dopamine when it was applied 2 or 5 s before stimulation. Longer time intervals and bath application of 5 μM adenosine did not decrease dopamine release. Mechanical stimulation of endogenous adenosine 2 s before dopamine stimulation also decreased stimulated dopamine release by 41 ± 7%, similar to the 54 ± 6% decrease in dopamine after exogenous adenosine application. Dopamine inhibition by transient adenosine was recovered within 10 min. The A1 receptor antagonist 8-cyclopentyl-1,3-dipropylxanthine blocked the dopamine modulation, whereas dopamine modulation was unaffected by the A2A receptor antagonist SCH 442416. Thus, transient adenosine changes can transiently modulate phasic dopamine release via A1 receptors. These data demonstrate that adenosine has a rapid, but transient, modulatory role in the brain. Here, transient adenosine was shown to modulate phasic dopamine release on the order of seconds by acting at the A1 receptor. However, sustained increases in adenosine did not regulate phasic dopamine release. This study demonstrates for the first time a transient, neuromodulatory function of rapid adenosine to regulate rapid neurotransmitter release.

  14. Sesamin protects against renal ischemia reperfusion injury by promoting CD39-adenosine-A2AR signal pathway in mice.

    Li, Ke; Gong, Xia; Kuang, Ge; Jiang, Rong; Wan, Jingyuan; Wang, Bin

    2016-01-01

    Ischemia reperfusion injury (IRI) is a leading cause of acute kidney injury with high morbidity and mortality due to limited therapy. Here, we examine whether sesamin attenuates renal IRI in an animal model and explore the underlying mechanisms. Male mice were subjected to right renal ischemia for 30 min followed by reperfusion for 24 h with sesamin (100 mg/kg) during which the left kidney was removed. Renal damage and function were assessed subsequently. The results showed that sesamin reduced kidney ischemia reperfusion injury, as assessed by decreased serum creatinine (Scr) and Blood urea nitrogen (BUN), alleviated tubular damage and apoptosis. In addition, sesamin inhibited neutrophils infiltration and pro-inflammatory cytokines tumor necrosis factor (TNF)-α and interleukin (IL)-1β production in IR-preformed kidney. Notably, sesamin promoted the expression of CD39, A2A adenosine receptor (A2AAR), and A2BAR mRNA and protein as well as adenosine production. Furthermore, CD39 inhibitor or A2AR antagonist abolished partly the protection of sesamin in kidney IRI. In conclusion, sesamin could effectively protect kidney from IRI by inhibiting inflammatory responses, which might be associated with promoting the adenosine-CD39-A2AR signaling pathway.

  15. CD73-derived adenosine and tenascin-C control cytokine production by epicardium-derived cells formed after myocardial infarction.

    Hesse, Julia; Leberling, Stella; Boden, Elisabeth; Friebe, Daniela; Schmidt, Timo; Ding, Zhaoping; Dieterich, Peter; Deussen, Andreas; Roderigo, Claudia; Rose, Christine R; Floss, Doreen M; Scheller, Jürgen; Schrader, Jürgen

    2017-03-31

    Epicardium-derived cells (EPDCs) play a fundamental role in embryonic cardiac development and are reactivated in the adult heart in response to myocardial infarction (MI). In this study, EPDCs from post-MI rat hearts highly expressed the ectoenzyme CD73 and secreted the profibrotic matricellular protein tenascin-C (TNC). CD73 on EPDCs extensively generated adenosine from both extracellular ATP and NAD. This in turn stimulated the release of additional nucleotides from a Brefeldin A-sensitive intracellular pool via adenosine-A2BR signaling, forming a positive-feedback loop. A2BR activation in addition strongly promoted the release of major regulatory cytokines, such as IL-6, IL-11, and VEGF. TNC was found to stimulate EPDC migration and, together with ATP-P2X7R signaling, to activate inflammasomes in EPDCs via TLR4. Our results demonstrate that EPDCs are an important source of various proinflammatory factors in the post-MI heart controlled by purinergic and TNC signaling.-Hesse, J., Leberling, S., Boden, E., Friebe, D., Schmidt, T., Ding, Z., Dieterich, P., Deussen, A., Roderigo, C., Rose, C. R., Floss, D. M., Scheller, J., Schrader, J. CD73-derived adenosine and tenascin-C control cytokine production by epicardium-derived cells formed after myocardial infarction.

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

    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.

  17. Adenosine receptor control of cognition in normal and disease.

    Chen, Jiang-Fan

    2014-01-01

    Adenosine and adenosine receptors (ARs) are increasingly recognized as important therapeutic targets for controlling cognition under normal and disease conditions for its dual roles of neuromodulation as well as of homeostatic function in the brain. This chapter first presents the unique ability of adenosine, by acting on the inhibitory A1 and facilitating A2A receptor, to integrate dopamine, glutamate, and BNDF signaling and to modulate synaptic plasticity (e.g., long-term potentiation and long-term depression) in brain regions relevant to learning and memory, providing the molecular and cellular bases for adenosine receptor (AR) control of cognition. This led to the demonstration of AR modulation of social recognition memory, working memory, reference memory, reversal learning, goal-directed behavior/habit formation, Pavlovian fear conditioning, and effort-related behavior. Furthermore, human and animal studies support that AR activity can also, through cognitive enhancement and neuroprotection, reverse cognitive impairments in animal models of Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's disease, and schizophrenia. Lastly, epidemiological evidence indicates that regular human consumption of caffeine, the most widely used psychoactive drug and nonselective AR antagonists, is associated with the reduced cognitive decline in aging and AD patients, and with the reduced risk in developing PD. Thus, there is a convergence of the molecular studies revealing AR as molecular targets for integrating neurotransmitter signaling and controlling synaptic plasticity, with animal studies demonstrating the strong procognitive impact upon AR antagonism in normal and disease brains and with epidemiological and clinical evidences in support of caffeine and AR drugs for therapeutic modulation of cognition. Since some of adenosine A2A receptor antagonists are already in phase III clinical trials for motor benefits in PD patients with remarkable safety profiles

  18. Adenosine gates synaptic plasticity at hippocampal mossy fiber synapses

    Moore, Kimberly A.; Nicoll, Roger A.; Schmitz, Dietmar

    2003-11-01

    The release properties of synapses in the central nervous system vary greatly, not only across anatomically distinct types of synapses but also among the same class of synapse. This variation manifests itself in large part by differences in the probability of transmitter release, which affects such activity-dependent presynaptic forms of plasticity as paired-pulse facilitation and frequency facilitation. This heterogeneity in presynaptic function reflects differences in the intrinsic properties of the synaptic terminal and the activation of presynaptic neurotransmitter receptors. Here we show that the unique presynaptic properties of the hippocampal mossy fiber synapse are largely imparted onto the synapse by the continuous local action of extracellular adenosine at presynaptic A1 adenosine receptors, which maintains a low basal probability of transmitter release.

  19. Expression of human adenosine deaminase in murine hematopoietic cells.

    Belmont, J W; MacGregor, G R; Wager-Smith, K; Fletcher, F A; Moore, K A; Hawkins, D; Villalon, D; Chang, S M; Caskey, C T

    1988-01-01

    Multiple replication-defective retrovirus vectors were tested for their ability to transfer and express human adenosine deaminase in vitro and in vivo in a mouse bone marrow transplantation model. High-titer virus production was obtained from vectors by using both a retrovirus long terminal repeat promoter and internal transcriptional units with human c-fos and herpes virus thymidine kinase promoters. After infection of primary murine bone marrow with one of these vectors, human adenosine deaminase was detected in 60 to 85% of spleen colony-forming units and in the blood of 14 of 14 syngeneic marrow transplant recipients. This system offers the opportunity to assess methods for increasing efficiency of gene transfer, for regulation of expression of foreign genes in hematopoietic progenitors, and for long-term measurement of the stability of expression in these cells. Images PMID:3072474

  20. Evidence for an A1-adenosine receptor in the guinea-pig atrium.

    Collis, M. G.

    1983-01-01

    1 The purpose of this study was to determine whether the adenosine receptor that mediates a decrease in the force of contraction of the guinea-pig atrium is of the A1- or A2-sub-type. 2 Concentration-response curves to adenosine and a number of 5'- and N6-substituted analogues were constructed and the order of potency of the purines was: 5'-N-cyclopropylcarboxamide adenosine (NCPCA) = 5'-N-ethylcarboxamide adenosine (NECA) greater than N6cyclohexyladenosine (CHA) greater than L-N6-phenylisopropyl adenosine (L-PIA) = 2-chloroadenosine- greater than adenosine greater than D-N6-phenylisopropyl adenosine (D-PIA). 3 The difference in potency between the stereoisomers D- and L-PIA was over 100 fold. 4 The adenosine transport inhibitor, dipyridamole, potentiated submaximal responses to adenosine but had no significant effect on those evoked by the other purines. 5 Theophylline antagonized responses evoked by all purines, and with D-PIA revealed a positive inotropic effect that was abolished by atenolol. 6 The results indicate the existence of an adenosine A1-receptor in the guinea-pig atrium. PMID:6297647

  1. Adenosine-mediated modulation of ventral horn interneurons and spinal motoneurons in neonatal mice.

    Witts, Emily C; Nascimento, Filipe; Miles, Gareth B

    2015-10-01

    Neuromodulation allows neural networks to adapt to varying environmental and biomechanical demands. Purinergic signaling is known to be an important modulatory system in many parts of the CNS, including motor control circuitry. We have recently shown that adenosine modulates the output of mammalian spinal locomotor control circuitry (Witts EC, Panetta KM, Miles GB. J Neurophysiol 107: 1925-1934, 2012). Here we investigated the cellular mechanisms underlying this adenosine-mediated modulation. Whole cell patch-clamp recordings were performed on ventral horn interneurons and motoneurons within in vitro mouse spinal cord slice preparations. We found that adenosine hyperpolarized interneurons and reduced the frequency and amplitude of synaptic inputs to interneurons. Both effects were blocked by the A1-type adenosine receptor antagonist DPCPX. Analysis of miniature postsynaptic currents recorded from interneurons revealed that adenosine reduced their frequency but not amplitude, suggesting that adenosine acts on presynaptic receptors to modulate synaptic transmission. In contrast to interneurons, recordings from motoneurons revealed an adenosine-mediated depolarization. The frequency and amplitude of synaptic inputs to motoneurons were again reduced by adenosine, but we saw no effect on miniature postsynaptic currents. Again these effects on motoneurons were blocked by DPCPX. Taken together, these results demonstrate differential effects of adenosine, acting via A1 receptors, in the mouse spinal cord. Adenosine has a general inhibitory action on ventral horn interneurons while potentially maintaining motoneuron excitability. This may allow for adaptation of the locomotor pattern generated by interneuronal networks while helping to ensure the maintenance of overall motor output.

  2. Pharmacology of the Adenosine A3 Receptor in the Vasculature and Essential Hypertension

    Ho, Ming-Fen; Low, Leanne M.; Rose’Meyer, Roselyn B.

    2016-01-01

    Background Essential hypertension is considered to be a multifactorial disorder and its aetiology has yet to be clearly identified. As the adenosine receptors have a significant role in mediating vasodilation, alterations in their structures or signalling pathways may be involved in the development of hypertension. This study aimed to measure the expression of adenosine A3 receptors in a range of cardiovascular tissues and determine whether they could be altered with essential hypertension, and to functionally test responses to adenosine A3 receptor agonists in coronary blood vessels using the isolated perfused heart preparation. Methods mRNA samples from cardiovascular tissues and a range of blood vessels were collected from 10 week old male spontaneously hypertensive rats and age-gender matched Wistar rats (n = 8). The Langendorff heart perfusion preparation was used to characterise adenosine A3 receptor mediated coronary vasodilation in the rat heart. Results Adenosine A3 receptor agonists induced coronary vasodilation. The expression of adenosine A3 receptors in cardiovascular tissues was altered in a tissue-specific pattern. Specifically, down-regulation of adenosine A3 receptor expression occurred in hypertensive hearts, which might be associated with attenuated vasodilator responses observed in coronary vessels to adenosine A3 receptor agonists. Conclusions This study demonstrated alterations in the expression of adenosine A3 receptors occurred in a tissue specific mode, and reduced adenosine A3 receptor mediated coronary vasodilation in hearts from spontaneously hypertensive rats. Our findings with regard to changes in the adenosine A3 receptor in hypertensive hearts suggest that adenosine A3 receptor might play a role in the physiopathology of essential hypertension and potentially open the way to pharmacologic manipulation of vasomotor activity by the use of adenosine A3 receptor agonists. PMID:26907173

  3. Modulation of synaptic transmission by adenosine in layer 2/3 of the rat visual cortex in vitro.

    Bannon, N M; Zhang, P; Ilin, V; Chistiakova, M; Volgushev, M

    2014-02-28

    Adenosine is a wide-spread endogenous neuromodulator. In the central nervous system it activates A1 and A2A receptors (A1Rs and A2ARs) which have differential distributions, different affinities to adenosine, are coupled to different G-proteins, and have opposite effects on synaptic transmission. Although effects of adenosine are studied in detail in several brain areas, such as the hippocampus and striatum, the heterogeneity of the effects of A1R and A2AR activation and their differential distribution preclude generalization over brain areas and cell types. Here we study adenosine's effects on excitatory synaptic transmission to layer 2/3 pyramidal neurons in slices of the rat visual cortex. We measured effects of bath application of adenosine receptor ligands on evoked excitatory postsynaptic potentials (EPSPs), miniature excitatory postsynaptic potentials (mEPSPs), and membrane properties. Adenosine reduced the amplitude of evoked EPSPs and excitatory postsynaptic currents (EPSCs), and reduced frequency of mEPSPs in a concentration-dependent and reversible manner. Concurrent with EPSP/C amplitude reduction was an increase in the paired-pulse ratio. These effects were blocked by application of the selective A1R antagonist DPCPX (8-cyclopentyl-1,3-dipropylxanthine), suggesting that activation of presynaptic A1Rs suppresses excitatory transmission by reducing release probability. Adenosine (20μM) hyperpolarized the cell membrane from -65.3±1.5 to -67.7±1.8mV, and reduced input resistance from 396.5±44.4 to 314.0±36.3MOhm (∼20%). These effects were also abolished by DPCPX, suggesting postsynaptic A1Rs. Application of the selective A2AR antagonist SCH-58261 (2-(2-furanyl)-7-(2-phenylethyl)-7H-pyrazolo[4,3-e][1,2,4]triazolo[1,5-c]pyrimidin-5-a-mine) on the background of high adenosine concentrations revealed an additional decrease in EPSP amplitude. Moreover, application of the A2AR agonist CGS-21680 (4-[2-[[6-amino-9-(N-ethyl-β-d-ribofuranuronamidosyl)-9H

  4. Adenosine receptors and stress : Studies using methylmercury, caffeine and hypoxia

    Björklund, Olga

    2008-01-01

    Brain development is a precisely organized process that can be disturbed by various stress factors present in the diet (e.g. exposure to xenobiotics) as well as insults such as decreased oxygen supply. The consequent adverse changes in nervous system function may not necessarily be apparent until a critical age when neurodevelopmental defects may be unmasked by a subsequent challenge. Adenosine and its receptors (AR) (A1, A2A, A2B and A3) which participate in the brain stres...

  5. Severe combined immunodeficiency due to adenosine deaminase deficiency.

    Hussain, Waqar; Batool, Asma; Ahmed, Tahir Aziz; Bashir, Muhammad Mukarram

    2012-03-01

    Severe Combined Immunodeficiency is the term applied to a group of rare genetic disorders characterised by defective or absent T and B cell functions. Patients usually present in first 6 months of life with respiratory/gastrointestinal tract infections and failure to thrive. Among the various types of severe combined immunodeficiency, enzyme deficiencies are relatively less common. We report the case of a 6 years old girl having severe combined immunodeficiency due to adenosine deaminase deficiency.

  6. An efficient extraction method for quantitation of adenosine triphosphate in mammalian tissues and cells.

    Chida, Junji; Yamane, Kazuhiko; Takei, Tunetomo; Kido, Hiroshi

    2012-05-21

    Firefly bioluminescence is widely used in the measurement of adenosine 5'-triphosphate (ATP) levels in biological materials. For such assays in tissues and cells, ATP must be extracted away from protein in the initial step and extraction efficacy is the main determinant of the assay accuracy. Extraction reagents recommended in the commercially available ATP assay kits are chaotropic reagents, trichloroacetic acid (TCA), perchloric acid (PCA), and ethylene glycol (EG), which extract nucleotides through protein precipitation and/or nucleotidase inactivation. We found that these reagents are particularly useful for measuring ATP levels in materials with relatively low protein concentrations such as blood cells, cultured cells, and bacteria. However, these methods are not suitable for ATP extraction from tissues with high protein concentrations, because some ATP may be co-precipitated with the insolubilized protein during homogenization and extraction, and it could also be precipitated by neutralization in the acid extracts. Here we found that a phenol-based extraction method markedly increased the ATP and other nucleotides extracted from tissues. In addition, phenol extraction does not require neutralization before the luciferin-luciferase assay step. ATP levels analyzed by luciferase assay in various tissues extracted by Tris-EDTA-saturated phenol (phenol-TE) were over 17.8-fold higher than those extracted by TCA and over 550-fold higher than those in EG extracts. Here we report a simple, rapid, and reliable phenol-TE extraction procedure for ATP measurement in tissues and cells by luciferase assay.

  7. Adenosine receptors in post-mortem human brain.

    James, S; Xuereb, J H; Askalan, R; Richardson, P J

    1992-01-01

    1. Adenosine A2-like binding sites were characterized in post-mortem human brain membranes by examining several compounds for their ability to displace [3H]-CGS 21680 (2[p-(2 carboxyethyl)-phenethylamino]-5'-N-ethylcarboxamido adenosine) binding. 2. Two A2-like binding sites were identified in the striatum. 3. The more abundant striatal site was similar to the A2a receptor previously described in rat striatum, both in its pharmacological profile and striatal localization. 4. The less abundant striatal site had a pharmacological profile similar to that of the binding site characterized in the other brain regions examined. This was intermediate in character between A1 and A2 and may represent another adenosine receptor subtype. 5. The co-purification of [3H]-CGS 21680 binding during immunoisolation of human striatal cholinergic membranes was used to assess the possible cholinergic localization of A2-like binding sites in the human striatum. Only the more abundant striatal site co-purified with cholinergic membranes. This suggests that this A2a-like site is present on cholinergic neurones in the human striatum.

  8. Acute hyperammonemia and systemic inflammation is associated with increased extracellular brain adenosine in rats

    Bjerring, Peter Nissen; Dale, Nicholas; Larsen, Fin Stolze

    2015-01-01

    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......) 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...

  9. Crystal Structure of Schistosoma mansoni Adenosine Phosphorylase/5’-Methylthioadenosine Phosphorylase and Its Importance on Adenosine Salvage Pathway

    Torini, Juliana Roberta; Brandão-Neto, José; DeMarco, Ricardo; Pereira, Humberto D'Muniz

    2016-01-01

    Schistosoma mansoni do not have de novo purine pathways and rely on purine salvage for their purine supply. It has been demonstrated that, unlike humans, the S. mansoni is able to produce adenine directly from adenosine, although the enzyme responsible for this activity was unknown. In the present work we show that S. mansoni 5´-deoxy-5´-methylthioadenosine phosphorylase (MTAP, E.C. 2.4.2.28) is capable of use adenosine as a substrate to the production of adenine. Through kinetics assays, we show that the Schistosoma mansoni MTAP (SmMTAP), unlike the mammalian MTAP, uses adenosine substrate with the same efficiency as MTA phosphorolysis, which suggests that this enzyme is part of the purine pathway salvage in S. mansoni and could be a promising target for anti-schistosoma therapies. Here, we present 13 SmMTAP structures from the wild type (WT), including three single and one double mutant, and generate a solid structural framework for structure description. These crystal structures of SmMTAP reveal that the active site contains three substitutions within and near the active site when compared to it mammalian counterpart, thus opening up the possibility of developing specific inhibitors to the parasite MTAP. The structural and kinetic data for 5 substrates reveal the structural basis for this interaction, providing substract for inteligent design of new compounds for block this enzyme activity. PMID:27935959

  10. (/sup 3/H)nitrobenzylthioinosine binding as a probe for the study of adenosine uptake sites in brain

    Marangos, P.J.; Patel, J.; Clark-Rosenberg, R.; Martino, A.M.

    1982-07-01

    The binding of the potent adenosine uptake inhibitor (/sup 3/H)nitrobenzylthioinosine ((/sup 3/H)NBI) to brain membrane fractions was investigated. Reversible, saturable, specific, high-affinity binding was demonstrated in both rat and human brain. The KD in both was 0.15 nM with Bmax values of 140-200 fmol/mg protein. Linear Scatchard plots were routinely obtained, indicating a homogeneous population of binding sites in brain. The highest density of binding sites was found in the caudate and hypothalamus in both species. The binding site was heat labile and trypsin sensitive. Binding was also decreased by incubation of the membranes in 0.05% Triton X-100 and by treatment with dithiothreitol and iodoacetamide. Of the numerous salt and metal ions tested, only copper and zinc had significant effects on (/sup 3/H)NBI binding. The inhibitory potencies of copper and zinc were IC50 . 160 microM and 6 mM, respectively. Subcellular distribution studies revealed a high percentage of the (/sup 3/H)NBI binding sites on synaptosomes, indicating that these sites were present in the synaptic region. A study of the tissue distribution of the (/sup 3/H)NBI sites revealed very high densities of binding in erythrocyte, lung, and testis, with much lower binding densities in brain, kidney, liver, muscle, and heart. The binding affinity in the former group was approximately 1.5 nM, whereas that in the latter group was 0.15 nM, suggesting two types of binding sites. The pharmacologic profile of (/sup 3/H)NBI binding was consistent with its function as the adenosine transport site, distinct from the adenosine receptor, since thiopurines were very potent inhibitors of binding whereas adenosine receptor ligands, such as cyclohexyladenosine and 2-chloroadenosine, were three to four orders of magnitude less potent. (/sup 3/H)NBI binding in brain should provide a useful probe for the study of adenosine transport in the brain.

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

    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

  12. Interaction between Intrathecal Gabapentin and Adenosine in the Formalin Test of Rats

    Yoon, Myung Ha; Choi, Jeong Il; Park, Heon Chang; Bae, Hong Beom

    2004-01-01

    Spinal gabapentin and adenosine have been known to display an antinociceptive effect. We evaluated the nature of the interaction between gabapentin and adenosine in formalin-induced nociception at the spinal level. Male Sprague-Dawley rats were prepared for intrathecal catheterization. Pain was evoked by injection of formalin solution (5%, 50 µL) into the hindpaw. After examination of the effects of gabapentin and adenosine, the resulting interaction was investigated with isobolographic and f...

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

    Felicita Pedata; Anna Maria Pugliese; Elisabetta Coppi; Ilaria Dettori; Giovanna Maraula; Lucrezia Cellai; Alessia Melani

    2014-01-01

    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 ...

  14. Endogenous adenosine and hemorrhagic shock: effects of caffeine administration or caffeine withdrawal.

    Conlay, L A; Evoniuk, G; Wurtman, R.J.

    1988-01-01

    Plasma adenosine concentrations doubled when rats were subjected to 90 min of profound hemorrhagic shock. Administration of caffeine (20 mg per kg of body weight), an adenosine-receptor antagonist, attenuated the hemorrhage-induced decrease in blood pressure. In contrast, chronic caffeine consumption (0.1% in drinking water), followed by a brief period of caffeine withdrawal, amplified the hypotensive response to hemorrhage. These data suggest that endogenous adenosine participates in the hyp...

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

    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.

  16. The Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) Uses its C-Terminus to Regulate the A2B Adenosine Receptor.

    Watson, Michael J; Lee, Shernita L; Marklew, Abigail J; Gilmore, Rodney C; Gentzsch, Martina; Sassano, Maria F; Gray, Michael A; Tarran, Robert

    2016-06-09

    CFTR is an apical membrane anion channel that regulates fluid homeostasis in many organs including the airways, colon, pancreas and sweat glands. In cystic fibrosis, CFTR dysfunction causes significant morbidity/mortality. Whilst CFTR's function as an ion channel has been well described, its ability to regulate other proteins is less understood. We have previously shown that plasma membrane CFTR increases the surface density of the adenosine 2B receptor (A2BR), but not of the β2 adrenergic receptor (β2AR), leading to an enhanced, adenosine-induced cAMP response in the presence of CFTR. In this study, we have found that the C-terminal PDZ-domain of both A2BR and CFTR were crucial for this interaction, and that replacing the C-terminus of A2BR with that of β2AR removed this CFTR-dependency. This observation extended to intact epithelia and disruption of the actin cytoskeleton prevented A2BR-induced but not β2AR-induced airway surface liquid (ASL) secretion. We also found that CFTR expression altered the organization of the actin cytoskeleton and PDZ-binding proteins in both HEK293T cells and in well-differentiated human bronchial epithelia. Furthermore, removal of CFTR's PDZ binding motif (ΔTRL) prevented actin rearrangement, suggesting that CFTR insertion in the plasma membrane results in local reorganization of actin, PDZ binding proteins and certain GPCRs.

  17. Topical adenosine increases the proportion of thick hair in Caucasian men with androgenetic alopecia.

    Iwabuchi, Tokuro; Ideta, Ritsuro; Ehama, Ritsuko; Yamanishi, Haruyo; Iino, Masato; Nakazawa, Yosuke; Kobayashi, Takashi; Ohyama, Manabu; Kishimoto, Jiro

    2016-05-01

    Adenosine is an effective treatment for androgenetic alopecia (AGA) in Japanese men and women. Adenosine exerts its effects by significantly increasing the proportion of thick hair. In this study, we assessed the clinical outcome of adenosine treatment for 6 months in 38 Caucasian men. The change in proportion of thick hair (≥60 μm) compared with baseline in the adenosine group was significantly higher than that in the placebo group (P thick hair in Caucasian men with AGA as well as in Japanese men and women.

  18. Adenosine Modulates the Oocyte Developmental Competence by Exposing Stages and Synthetic Blocking during In Vitro Maturation.

    Cheon, Yong-Pil

    2016-06-01

    Purine metabolism is known factor for nuclear maturation of oocytes through both follicle cells and oocyte itself. However, it is largely unknown the roles of purine metabolism in the oocyte competence for fertilization and early development. In this study, the effects of adenosine in oocyte competence for development were examined using adenosine and its synthetic inhibitors. Adenosine treatment from GV intact stage for 18 hr (fGV) caused of decrease the fertilization rate but of increase the cleavage rate compared from the other stage treatment groups. Hadacidin did not effect on fertilization rate but increased cleavage rate without stage specificity. Adenosine did not block the effects of hadacidin with the exception of fGV group. By the inhibition of purine synthetic pathways the fertilization rate was decreased in the fGV and fGVB groups but increased in the fMII group. Exogenous adenosine caused of decrease fertilization rate in the fGVB group but increase in the fMII group. Cleavage rate was dramatically increased in the adenosine treatment with synthetic inhibitors. It means that the metabolism of purine has stage specific effects on fertilization and cleavage. Exogenous adenosine had only can improve oocyte developmental competence when it treated at GV intact stage. On the other hand, endogenous synthesis in all maturation stage caused of increase the cleavage rate without effects on fertilization. These data suggest that adenosine at GV stage as a paracrine fashion and inhibitions of endogenous adenosine in all stage improve oocyte developmental competence..

  19. Effects of oral adenosine-5′-triphosphate supplementation on athletic performance, skeletal muscle hypertrophy and recovery in resistance-trained men

    Wilson, Jacob M; Joy, Jordan M; Ryan P. Lowery; Roberts, Michael D.; Lockwood, Christopher M; Manninen, Anssi H; Fuller, John C; Souza, Eduardo O.; Baier, Shawn M.; Wilson, Stephanie MC; Rathmacher, John A

    2013-01-01

    Background Currently, there is a lack of studies examining the effects of adenosine-5′-triphosphate (ATP) supplementation utilizing a long-term, periodized resistance-training program (RT) in resistance-trained populations. Therefore, we investigated the effects of 12 weeks of 400 mg per day of oral ATP on muscular adaptations in trained individuals. We also sought to determine the effects of ATP on muscle protein breakdown, cortisol, and performance during an overreaching cycle. Methods The ...

  20. Molecular structure of tetraaqua adenosine 5'-triphosphate aluminium(III) complex: a study involving Raman spectroscopy, theoretical DFT and potentiometry.

    Tenório, Thaís; Silva, Andréa M; Ramos, Joanna Maria; Buarque, Camilla D; Felcman, Judith

    2013-03-15

    The Alzheimer's disease is one of the most common neurodegenerative diseases that affect elderly population, due to the formation of β-amyloid protein aggregate and several symptoms, especially progressive cognitive decline. The result is a decrease in capture of glucose by cells leading to obliteration, meddling in the Krebs cycle, the principal biochemical route to the energy production leading to a decline in the levels of adenosine 5'-triphosphate. Aluminium(III) is connected to Alzheimer's and its ion provides raise fluidity of the plasma membrane, decrease cell viability and aggregation of amyloid plaques. Studies reveal that AlATP complex promotes the formation of reactive fibrils of β-amyloid protein and independent amyloidogenic peptides, suggesting the action of the complex as a chaperone in the role pathogenic process. In this research, one of complexes formed by Al(III) and adenosine 5'-triphosphate in aqueous solution is analyzed by potentiometry, Raman spectroscopy and ab initio calculations. The value of the logK(AlATP) found was 9.21±0.01 and adenosine 5'-triphosphate should act as a bidentate ligand in the complex. Raman spectroscopy and potentiometry indicate that donor atoms are the oxygen of the phosphate β and the oxygen of the phosphate γ, the terminal phosphates. Computational calculations using Density Functional Theory, with hybrid functions B3LYP and 6-311++G(d,p) basis set regarding water solvent effects, have confirmed the results. Frontier molecular orbitals, electrostatic potential contour surface, electrostatic potential mapped and Mulliken charges of the title molecule were also investigated.

  1. Molecular structure of tetraaqua adenosine 5'-triphosphate aluminium(III) complex: A study involving Raman spectroscopy, theoretical DFT and potentiometry

    Tenório, Thaís; Silva, Andréa M.; Ramos, Joanna Maria; Buarque, Camilla D.; Felcman, Judith

    2013-03-01

    The Alzheimer's disease is one of the most common neurodegenerative diseases that affect elderly population, due to the formation of β-amyloid protein aggregate and several symptoms, especially progressive cognitive decline. The result is a decrease in capture of glucose by cells leading to obliteration, meddling in the Krebs cycle, the principal biochemical route to the energy production leading to a decline in the levels of adenosine 5'-triphosphate. Aluminium(III) is connected to Alzheimer's and its ion provides raise fluidity of the plasma membrane, decrease cell viability and aggregation of amyloid plaques. Studies reveal that AlATP complex promotes the formation of reactive fibrils of β-amyloid protein and independent amyloidogenic peptides, suggesting the action of the complex as a chaperone in the role pathogenic process. In this research, one of complexes formed by Al(III) and adenosine 5'-triphosphate in aqueous solution is analyzed by potentiometry, Raman spectroscopy and ab initio calculations. The value of the log KAlATP found was 9.21 ± 0.01 and adenosine 5'-triphosphate should act as a bidentate ligand in the complex. Raman spectroscopy and potentiometry indicate that donor atoms are the oxygen of the phosphate β and the oxygen of the phosphate γ, the terminal phosphates. Computational calculations using Density Functional Theory, with hybrid functions B3LYP and 6-311++G(d,p) basis set regarding water solvent effects, have confirmed the results. Frontier molecular orbitals, electrostatic potential contour surface, electrostatic potential mapped and Mulliken charges of the title molecule were also investigated.

  2. Evidence for an A2/Ra adenosine receptor in the guinea-pig trachea

    Brown, C.M.; Collis, M.G.

    1982-01-01

    1 An attempt was made to determine whether the extracellular adenosine receptor that mediates relaxation in the guinea-pig trachea is of the A1/Ri or A2/Ra subtype. 2 Dose-response curves to adenosine and a number of 5′- and N6-substituted analogues were constructed for the isolated guinea-pig trachea, contracted with carbachol. 3 The 5′-substituted analogues of adenosine were the most potent compounds tested, the order of potency being 5′-N-cyclopropylcarboxamide adenosine (NCPCA) > 5′-N-ethylcarboxamide adenosine (NECA) > 2-chloroadenosine > L-N6-phenylisopropyladenosine (L-PIA) > adenosine > D-N6-phenylisopropyladenosine (D-PIA). 4 The difference in potency between the stereoisomers D- and L-PIA on the isolated trachea was at the most five fold. 5 Responses to low doses of adenosine and its analogues were attenuated after treatment with either theophylline or 8-phenyltheophylline. The responses to 2-chloroadenosine were affected to a lesser extent than were those to the other purines. 6 Adenosine transport inhibitors, dipyridamole and dilazep, potentiated responses to adenosine, did not affect those to NCPCA, NECA, L-PIA and D-PIA but significantly reduced the responses to high doses of 2-chloroadenosine. 7 Relaxations evoked by 9-β-D-xylofuranosyladenosine which can activate intracellular but not extracellular adenosine receptors, were attenuated by dipyridamole but unaffected by 8-phenyltheophylline. 8 The results support the existence of an extracellular A2/Ra subtype of adenosine receptor and an intracellular purine-sensitive site, both of which mediate relaxation. PMID:6286021

  3. Effect of phentolamine on the hyperemic response to adenosine in patients with microvascular disease.

    Aarnoudse, Wilbert; Geven, Maartje; Barbato, Emanuele; Botman, Kees-joost; De Bruyne, Bernard; Pijls, Nico H J

    2005-12-15

    For accurate measurement of the fractional flow reserve (FFR) of the myocardium, the presence of maximum hyperemia is of paramount importance. It has been suggested that the hyperemic effect of the conventionally used hyperemic stimulus, adenosine, could be submaximal in patients who have microvascular dysfunction and that adding alpha-blocking agents could augment the hyperemic response in these patients. We studied the effect of the nonselective alpha-blocking agent phentolamine, which was administered in addition to adenosine after achieving hyperemia, in patients who had microvascular disease and those who did not. Thirty patients who were referred for percutaneous coronary intervention were selected. Of these 30 patients, 15 had strong indications for microvascular disease and 15 did not. FFR was measured using intracoronary adenosine, intravenous adenosine, and intracoronary papaverine before and after intracoronary administration of the nonselective alpha blocker phentolamine. In patients who did not have microvascular disease, no differences in hyperemic response to adenosine were noted, whether or not alpha blockade was given before adenosine administration; FFR levels before and after phentolamine were 0.76 and 0.75, respectively, using intracoronary adenosine (p = 0.10) and 0.75 and 0.74, respectively, using intravenous adenosine (p = 0.20). In contrast, in patients who had microvascular disease, some increase in hyperemic response was observed after administration of phentolamine; FFR levels decreased from 0.74 to 0.70 using intracoronary adenosine (p = 0.003) and from 0.75 to 0.72 using intravenous adenosine (p = 0.04). Although statistically significant, the observed further decrease in microvascular resistance after addition of phentolamine was small and did not affect clinical decision making in any patient. In conclusion, when measuring FFR, routinely adding an alpha-blocking agent to adenosine does not affect clinical decision making.

  4. Characterization of spontaneous, transient adenosine release in the caudate-putamen and prefrontal cortex.

    Nguyen, Michael D; Lee, Scott T; Ross, Ashley E; Ryals, Matthew; Choudhry, Vishesh I; Venton, B Jill

    2014-01-01

    Adenosine is a neuroprotective agent that inhibits neuronal activity and modulates neurotransmission. Previous research has shown adenosine gradually accumulates during pathologies such as stroke and regulates neurotransmission on the minute-to-hour time scale. Our lab developed a method using carbon-fiber microelectrodes to directly measure adenosine changes on a sub-second time scale with fast-scan cyclic voltammetry (FSCV). Recently, adenosine release lasting a couple of seconds has been found in murine spinal cord slices. In this study, we characterized spontaneous, transient adenosine release in vivo, in the caudate-putamen and prefrontal cortex of anesthetized rats. The average concentration of adenosine release was 0.17±0.01 µM in the caudate and 0.19±0.01 µM in the prefrontal cortex, although the range was large, from 0.04 to 3.2 µM. The average duration of spontaneous adenosine release was 2.9±0.1 seconds and 2.8±0.1 seconds in the caudate and prefrontal cortex, respectively. The concentration and number of transients detected do not change over a four hour period, suggesting spontaneous events are not caused by electrode implantation. The frequency of adenosine transients was higher in the prefrontal cortex than the caudate-putamen and was modulated by A1 receptors. The A1 antagonist DPCPX (8-cyclopentyl-1,3-dipropylxanthine, 6 mg/kg i.p.) increased the frequency of spontaneous adenosine release, while the A1 agonist CPA (N(6)-cyclopentyladenosine, 1 mg/kg i.p.) decreased the frequency. These findings are a paradigm shift for understanding the time course of adenosine signaling, demonstrating that there is a rapid mode of adenosine signaling that could cause transient, local neuromodulation.

  5. Adenosine conjugated lipidic nanoparticles for enhanced tumor targeting.

    Swami, Rajan; Singh, Indu; Jeengar, Manish Kumar; Naidu, V G M; Khan, Wahid; Sistla, Ramakrishna

    2015-01-01

    Delivering chemotherapeutics by nanoparticles into tumor is impeded majorly by two factors: nonspecific targeting and inefficient penetration. Targeted delivery of anti-cancer agents solely to tumor cells introduces a smart strategy because it enhances the therapeutic index compared with untargeted drugs. The present study was performed to investigate the efficiency of adenosine (ADN) to target solid lipid nanoparticles (SLN) to over expressing adenosine receptor cell lines such as human breast cancer and prostate cancer (MCF-7 and DU-145 cells), respectively. SLN were prepared by emulsification and solvent evaporation process using docetaxel (DTX) as drug and were characterized by various techniques like dynamic light scattering, differential scanning calorimeter and transmission electron microscopy. DTX loaded SLNs were surface modified with ADN, an adenosine receptors ligand using carbodiimide coupling. Conjugation was confirmed using infrared spectroscopy and quantified using phenol-sulfuric acid method. Conjugated SLN were shown to have sustained drug release as compared to unconjugated nanoparticles and drug suspension. Compared with free DTX and unconjugated SLN, ADN conjugated SLN showed significantly higher cytotoxicity of loaded DTX, as evidenced by in vitro cell experiments. The IC50 was 0.41 μg/ml for native DTX, 0.30 μg/ml for unconjugated SLN formulation, and 0.09 μg/ml for ADN conjugated SLN formulation in MCF-7 cell lines. Whereas, in DU-145, there was 2 fold change in IC50 of ADN-SLN as compared to DTX. IC50 was found to be 0.44 μg/ml for free DTX, 0.39 μg/ml for unconjugated SLN and 0.22 μg/ml for ADN-SLN. Annexin assay and cell cycle analysis assay further substantiated the cell cytotoxicity. Fluorescent cell uptake and competitive ligand-receptor binding assay corroborated the receptor mediated endocytosis pathway indicated role of adenosine receptors in internalization of conjugated particles. Pharmacokinetic studies of lipidic

  6. Adenosine triphosphate (ATP) as a possible indicator of extraterrestrial biology

    Chappelle, E. W.; Picciolo, G. L.

    1974-01-01

    The ubiquity of adenosine triphosphate (ATP) in terrestrial organisms provides the basis for proposing the assay of this vital metabolic intermediate for detecting extraterrestrial biological activity. If an organic carbon chemistry is present on the planets, the occurrence of ATP is possible either from biosynthetic or purely chemical reactions. However, ATP's relative complexity minimizes the probability of abiogenic synthesis. A sensitive technique for the quantitative detection of ATP was developed using the firefly bioluminescent reaction. The procedure was used successfully for the determination of the ATP content of soil and bacteria. This technique is also being investigated from the standpoint of its application in clinical medicine.

  7. Biosynthesis of threonylcarbamoyl adenosine (t6A), a universal tRNA nucleoside.

    Deutsch, Christopher; El Yacoubi, Basma; de Crécy-Lagard, Valérie; Iwata-Reuyl, Dirk

    2012-04-20

    The anticodon stem-loop (ASL) of transfer RNAs (tRNAs) drives decoding by interacting directly with the mRNA through codon/anticodon pairing. Chemically complex nucleoside modifications found in the ASL at positions 34 or 37 are known to be required for accurate decoding. Although over 100 distinct modifications have been structurally characterized in tRNAs, only a few are universally conserved, among them threonylcarbamoyl adenosine (t(6)A), found at position 37 in the anticodon loop of a subset of tRNA. Structural studies predict an important role for t(6)A in translational fidelity, and in vivo work supports this prediction. Although pioneering work in the 1970s identified the fundamental substrates for t(6)A biosynthesis, the enzymes responsible for its biosynthesis have remained an enigma. We report here the discovery that in bacteria four proteins (YgjD, YrdC, YjeE, and YeaZ) are both necessary and sufficient for t(6)A biosynthesis in vitro. Notably, YrdC and YgjD are members of universally conserved families that were ranked among the top 10 proteins of unknown function in need of functional characterization, while YeaZ and YjeE are specific to bacteria. This latter observation, coupled with the essentiality of all four proteins in bacteria, establishes this pathway as a compelling new target for antimicrobial development.

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

    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 A2A receptor (A2AR), has an exceptionally long intracellular C terminus (A2AR-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 A2AR and the role of Ca(2+) in this process. First, we studied the A2AR-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 A2AR-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 A2AR-calmodulin/Ca(2+) complex. Importantly, calmodulin displaced α-actinin 1 from the A2AR-ct in a Ca(2+)-dependent fashion, disrupting the A2AR-α-actinin 1 complex. Finally, we assessed the impact of Ca(2+) on A2AR internalization in living cells, a function operated by the A2AR-α-actinin 1 complex. Interestingly, while Ca(2+) influx did not affect constitutive A2AR endocytosis, it abolished agonist-dependent internalization. In addition, we demonstrated that the A2AR/α-actinin interaction plays a pivotal role in receptor internalization and function. Overall, our results suggest that the interplay of A2AR with calmodulin and α-actinin 1 is fine-tuned by Ca(2+), a fact that might power agonist-mediated receptor internalization and function.

  9. Treatment of paroxysmal supraventricular tachycardia with intravenous injection of adenosine triphosphate.

    Saito, D.; Ueeda, M; Abe, Y.; Tani, H; Nakatsu, T.; Yoshida, H.; Haraoka, S; Nagashima, H

    1986-01-01

    Intravenous adenosine triphosphate rapidly terminated all 11 episodes of paroxysmal supraventricular tachycardia in 10 patients. Eight patients reported side effects but these resolved within 20 seconds and did not require treatment. Adenosine triphosphate is a suitable agent for the rapid termination of paroxysmal supraventricular tachycardia.

  10. The ischemic preconditioning effect of adenosine in patients with ischemic heart disease

    Berglund Margareta

    2009-11-01

    Full Text Available Abstract Introduction In vivo and in vitro evidence suggests that adenosine and its agonists play key roles in the process of ischemic preconditioning. The effects of low-dose adenosine infusion on ischemic preconditioning have not been thoroughly studied in humans. Aims We hypothesised that a low-dose adenosine infusion could reduce the ischemic burden evoked by physical exercise and improve the regional left ventricular (LV systolic function. Materials and methods We studied nine severely symptomatic male patients with severe coronary artery disease. Myocardial ischemia was induced by exercise on two separate occasions and quantified by Tissue Doppler Echocardiography. Prior to the exercise test, intravenous low-dose adenosine or placebo was infused over ten minutes according to a randomized, double blind, cross-over protocol. The LV walls were defined as ischemic if a reduction, no increment, or an increment of Results PSV increased from baseline to maximal exercise in non-ischemic walls both during placebo (P = 0.0001 and low-dose adenosine infusion (P = 0.0009. However, in the ischemic walls, PSV increased only during low-dose adenosine infusion (P = 0.001, while no changes in PSV occurred during placebo infusion (P = NS. Conclusion Low-dose adenosine infusion reduced the ischemic burden and improved LV regional systolic function in the ischemic walls of patients with exercise-induced myocardial ischemia, confirming that adenosine is a potential preconditioning agent in humans.

  11. Genetically Controlled Upregulation of Adenosine A(1) Receptor Expression Enhances the Survival of Primary Cortical Neurons

    Serchov, Tsvetan; Atas, Hasan-Cem; Normann, Claus; van Calker, Dietrich; Biber, Knut

    2012-01-01

    Adenosine has a key endogenous neuroprotective role in the brain, predominantly mediated by the adenosine A(1) receptor (A(1)R). This has been mainly explored using pharmacological tools and/or receptor knockout mice strains. It has long been suggested that the neuroprotective effects of A(1)R are i

  12. Nafion-CNT coated carbon-fiber microelectrodes for enhanced detection of adenosine.

    Ross, Ashley E; Venton, B Jill

    2012-07-07

    Adenosine is a neuromodulator that regulates neurotransmission. Adenosine can be monitored using fast-scan cyclic voltammetry at carbon-fiber microelectrodes and ATP is a possible interferent in vivo because the electroactive moiety, adenine, is the same for both molecules. In this study, we investigated carbon-fiber microelectrodes coated with Nafion and carbon nanotubes (CNTs) to enhance the sensitivity of adenosine and decrease interference by ATP. Electrodes coated in 0.05 mg mL(-1) CNTs in Nafion had a 4.2 ± 0.2 fold increase in current for adenosine, twice as large as for Nafion alone. Nafion-CNT electrodes were 6 times more sensitive to adenosine than ATP. The Nafion-CNT coating did not slow the temporal response of the electrode. Comparing different purine bases shows that the presence of an amine group enhances sensitivity and that purines with carbonyl groups, such as guanine and hypoxanthine, do not have as great an enhancement after Nafion-CNT coating. The ribose group provides additional sensitivity enhancement for adenosine over adenine. The Nafion-CNT modified electrodes exhibited significantly more current for adenosine than ATP in brain slices. Therefore, Nafion-CNT modified electrodes are useful for sensitive, selective detection of adenosine in biological samples.

  13. The effect of circulating adenosine on cerebral haemodynamics and headache generation in healthy subjects

    Birk, S; Petersen, K.A.; Kruuse, Christina Rostrup

    2005-01-01

    been investigated in man and reports regarding the effect of intravenous adenosine on cerebral blood flow are conflicting. Twelve healthy participants received adenosine 80, 120 microg kg(-1) min(-1) and placebo intravenously for 20 min, in a double-blind, three-way, crossover, randomized design...

  14. Different Modulating Effects of Adenosine on Neonatal and Adult Polymorphonuclear Leukocytes

    Pei-Chen Hou

    2012-01-01

    Full Text Available Polymorphonuclear leukocytes (PMNs are the major leukocytes in the circulation and play an important role in host defense. Intact PMN functions include adhesion, migration, phagocytosis, and reactive oxygen species (ROS release. It has been known for a long time that adenosine can function as a modulator of adult PMN functions. Neonatal plasma has a higher adenosine level than that of adults; however, little is known about the modulating effects of adenosine on neonatal PMNs. The aim of this study was to investigate the effects of adenosine on neonatal PMN functions. We found that neonatal PMNs had impaired adhesion, chemotaxis, and ROS production abilities, but not phagocytosis compared to adult PMNs. As with adult PMNs, adenosine could suppress the CD11b expressions of neonatal PMNs, but had no significant suppressive effect on phagocytosis. In contrast to adult PMNs, adenosine did not significantly suppress chemotaxis and ROS production of neonatal PMNs. This may be due to impaired phagocyte reactions and a poor neonatal PMN response to adenosine. Adenosine may not be a good strategy for the treatment of neonatal sepsis because of impaired phagocyte reactions and poor response.

  15. Adenosine signaling and the energetic costs of induced immunity.

    Brian P Lazzaro

    2015-04-01

    Full Text Available Life history theory predicts that trait evolution should be constrained by competing physiological demands on an organism. Immune defense provides a classic example in which immune responses are presumed to be costly and therefore come at the expense of other traits related to fitness. One strategy for mitigating the costs of expensive traits is to render them inducible, such that the cost is paid only when the trait is utilized. In the current issue of PLOS Biology, Bajgar and colleagues elegantly demonstrate the energetic and life history cost of the immune response that Drosophila melanogaster larvae induce after infection by the parasitoid wasp Leptopilina boulardi. These authors show that infection-induced proliferation of defensive blood cells commands a diversion of dietary carbon away from somatic growth and development, with simple sugars instead being shunted to the hematopoetic organ for rapid conversion into the raw energy required for cell proliferation. This metabolic shift results in a 15% delay in the development of the infected larva and is mediated by adenosine signaling between the hematopoietic organ and the central metabolic control organ of the host fly. The adenosine signal thus allows D. melanogaster to rapidly marshal the energy needed for effective defense and to pay the cost of immunity only when infected.

  16. Adenosine Deaminase Deficiency - More Than Just an Immunodeficiency

    Kathryn Victoria Whitmore

    2016-08-01

    Full Text Available Adenosine deaminase (ADA deficiency is best known as a form of severe combined immunodeficiency (SCID which results from mutations in the gene encoding adenosine deaminase. Affected patients present with clinical and immunological manifestations typical of a severe combined immunodeficiency. Therapies are currently available that can that target these immunological disturbances and treated patients show varying degrees of clinical improvement. However, there is now a growing body of evidence that deficiency of ADA has significant impact on non-immunological organ systems. This review will outline the impact of ADA deficiency on various organ systems, starting with the well understood immunological abnormalities. We will discuss possible pathogenic mechanisms and also highlight ways in which current treatments could be improved. In doing so, we aim to present ADA deficiency as more than an immunodeficiency and suggest that it should be recognized as a systemic metabolic disorder that affects multiple organ systems. Only by fully understanding ADA deficiency and its manifestations in all organ systems can we aim to deliver therapies that will correct all the clinical consequences.

  17. Methylthioadenosine reprograms macrophage activation through adenosine receptor stimulation.

    Peter A Keyel

    Full Text Available Regulation of inflammation is necessary to balance sufficient pathogen clearance with excessive tissue damage. Central to regulating inflammation is the switch from a pro-inflammatory pathway to an anti-inflammatory pathway. Macrophages are well-positioned to initiate this switch, and as such are the target of multiple therapeutics. One such potential therapeutic is methylthioadenosine (MTA, which inhibits TNFα production following LPS stimulation. We found that MTA could block TNFα production by multiple TLR ligands. Further, it prevented surface expression of CD69 and CD86 and reduced NF-KB signaling. We then determined that the mechanism of this action by MTA is signaling through adenosine A2 receptors. A2 receptors and TLR receptors synergized to promote an anti-inflammatory phenotype, as MTA enhanced LPS tolerance. In contrast, IL-1β production and processing was not affected by MTA exposure. Taken together, these data demonstrate that MTA reprograms TLR activation pathways via adenosine receptors to promote resolution of inflammation.

  18. Novel trypanocidal analogs of 5'-(methylthio)-adenosine.

    Sufrin, Janice R; Spiess, Arthur J; Marasco, Canio J; Rattendi, Donna; Bacchi, Cyrus J

    2008-01-01

    The purine nucleoside 5'-deoxy-5'-(hydroxyethylthio)-adenosine (HETA) is an analog of the polyamine pathway metabolite 5'-deoxy-5'-(methylthio)-adenosine (MTA). HETA is a lead structure for the ongoing development of selectively targeted trypanocidal agents. Thirteen novel HETA analogs were synthesized and examined for their in vitro trypanocidal activities against bloodstream forms of Trypanosoma brucei brucei LAB 110 EATRO and at least one drug-resistant Trypanosoma brucei rhodesiense clinical isolate. New compounds were also assessed in a cell-free assay for their activities as substrates of trypanosome MTA phosphorylase. The most potent analog in this group was 5'-deoxy-5'-(hydroxyethylthio)-tubercidin, whose in vitro cytotoxicity (50% inhibitory concentration [IC50], 10 nM) is 45 times greater than that of HETA (IC50, 450 nM) against pentamidine-resistant clinical isolate KETRI 269. Structure-activity analyses indicate that the enzymatic cleavage of HETA analogs by trypanosome MTA phosphorylase is not an absolute requirement for trypanocidal activity. This suggests that additional biochemical mechanisms are associated with the trypanocidal effects of HETA and its analogs.

  19. Adenosine Amine Congener as a Cochlear Rescue Agent

    Srdjan M. Vlajkovic

    2014-01-01

    Full Text Available We have previously shown that adenosine amine congener (ADAC, a selective A1 adenosine receptor agonist, can ameliorate noise- and cisplatin-induced cochlear injury. Here we demonstrate the dose-dependent rescue effects of ADAC on noise-induced cochlear injury in a rat model and establish the time window for treatment. Methods. ADAC (25–300 μg/kg was administered intraperitoneally to Wistar rats (8–10 weeks old at intervals (6–72 hours after exposure to traumatic noise (8–16 kHz, 110 dB sound pressure level, 2 hours. Hearing sensitivity was assessed using auditory brainstem responses (ABR before and 12 days after noise exposure. Pharmacokinetic studies investigated ADAC concentrations in plasma after systemic (intravenous administration. Results. ADAC was most effective in the first 24 hours after noise exposure at doses >50 μg/kg, providing up to 21 dB protection (averaged across 8–28 kHz. Pharmacokinetic studies demonstrated a short (5 min half-life of ADAC in plasma after intravenous administration without detection of degradation products. Conclusion. Our data show that ADAC mitigates noise-induced hearing loss in a dose- and time-dependent manner, but further studies are required to establish its translation as a clinical otological treatment.

  20. Reconstruction of the adenosine system by bone marrow-derived mesenchymal stem cell transplantation

    Huicong Kang; Qi Hu; Xiaoyan Liu; Yinhe Liu; Feng Xu; Xiang Li; Suiqiang Zhu

    2012-01-01

    In the present study, we transplanted bone marrow-derived mesenchymal stem cells into the CA3 area of the hippocampus of chronic epilepsy rats kindled by lithium chloride-pilocarpine. Immunofluorescence and western blotting revealed an increase in adenosine A1 receptor expression and a decrease in adenosine A2a receptor expression in the brain tissues of epileptic rats 3 months after transplantation. Moreover, the imbalance in the A1 adenosine receptor/A2a adenosine receptor ratio was improved. Electroencephalograms showed that frequency and amplitude of spikes in the hippocampus and frontal lobe were reduced. These results suggested that mesenchymal stem cell transplantation can reconstruct the normal function of the adenosine system in the brain and greatly improve epileptiform discharges.

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

    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...... of A2A receptors or injection of lentiviral vectors expressing the A2A receptor into white fat induces brown-like cells-so-called beige adipocytes. Importantly, mice fed a high-fat diet and treated with an A2A agonist are leaner with improved glucose tolerance. Taken together, our results demonstrate...... that adenosine-A2A signalling plays an unexpected physiological role in sympathetic BAT activation and protects mice from diet-induced obesity. Those findings reveal new possibilities for developing novel obesity therapies....

  2. Comparison of exogenous adenosine and voluntary exercise on human skeletal muscle perfusion and perfusion heterogeneity

    Heinonen, Ilkka H.A.; Kemppainen, Jukka; Kaskinoro, Kimmo;

    2010-01-01

    femoral artery infusion of adenosine (1 mg * min(-1) * litre thigh volume(-1)), which has previously been shown to induce maximal whole thigh blood flow of ~8 L/min. This response was compared to the blood flow induced by moderate-high intensity one-leg dynamic knee extension exercise. Adenosine increased...... muscle. Additionally, it remains to be determined what proportion of adenosine-induced flow elevation is specifically directed to muscle only. In the present study we measured thigh muscle capillary nutritive blood flow in nine healthy young men using positron emission tomography at rest and during...... muscle blood flow on average to 40 +/- 7 ml. min(-1) per 100g(-1) of muscle and an aggregate value of 2.3 +/- 0.6 L * min(-1) for the whole thigh musculature. Adenosine also induced a substantial change in blood flow distribution within individuals. Muscle blood flow during adenosine infusion...

  3. Interstitial and plasma adenosine stimulate nitric oxide and prostacyclin formation in human skeletal muscle

    Nyberg, Michael Permin; Mortensen, Stefan Peter; Thaning, Pia;

    2010-01-01

    One major unresolved issue in muscle blood flow regulation is that of the role of circulating versus interstitial vasodilatory compounds. The present study determined adenosine-induced formation of NO and prostacyclin in the human muscle interstitium versus in femoral venous plasma to elucidate....... In young healthy humans, microdialysate was collected at rest, during arterial infusion of adenosine, and during interstitial infusion of adenosine through microdialysis probes inserted into musculus vastus lateralis. Muscle interstitial NO and prostacyclin increased with arterial and interstitial infusion...... levels. These findings provide novel insight into the role of adenosine in skeletal muscle blood flow regulation and vascular function by revealing that both interstitial and plasma adenosine have a stimulatory effect on NO and prostacyclin formation. In addition, both skeletal muscle and microvascular...

  4. 2-(1-Hexyn-1-yl)adenosine-induced intraocular hypertension is mediated via K+ channel opening through adenosine A2A receptor in rabbits.

    Konno, Takashi; Uchibori, Takehiro; Nagai, Akihiko; Kogi, Kentaro; Nakahata, Norimichi

    2005-08-22

    The present study was performed to clarify the mechanism of change in intraocular pressure by 2-(1-hexyn-1-yl)adenosine (2-H-Ado), a selective adenosine A2 receptor agonist, in rabbits. 2-H-Ado (0.1%, 50 microl)-induced ocular hypertension (E(max): 7.7 mm Hg) was inhibited by an adenosine A2A receptor antagonist 1,3,7-trimethyl-8-(3-chlorostyryl)xanthine, ATP-sensitive K+ channel blocker glibenclamide or 5-hydroxydecanoic acid, but not by an adenosine A1 receptor antagonist 8-cyclopentyl-1,3-dipropylxanthine, an adenosine A2B receptor antagonist alloxazine or a cyclooxygenase inhibitor indomethacin. The outflow facility induced by 2-H-Ado seems to be independent of increase in intraocular pressure or ATP-sensitive K+ channel. In contrast, the recovery rate in intraocular pressure decreased by hypertonic saline was accelerated by 2-H-Ado, and this response was dependent on ATP-sensitive K+ channel. These results suggest that 2-H-Ado-induced ocular hypertension is mediated via K+ channel opening through adenosine A2A receptor, and this is probably due to aqueous formation, but independent of change in outflow facility or prostaglandin production.

  5. Autophagy occurs within an hour of adenosine triphosphate treatment after nerve cell damage:the neuroprotective effects of adenosine triphosphate against apoptosis

    Na Lu; Baoying Wang; Xiaohui Deng; Honggang Zhao; Yong Wang; Dongliang Li

    2014-01-01

    After hypoxia, ischemia, or inlfammatory injuries to the central nervous system, the damaged cells release a large amount of adenosine triphosphate, which may cause secondary neuronal death. Autophagy is a form of cell death that also has neuroprotective effects. Cell Counting Kit assay, monodansylcadaverine staining, lfow cytometry, western blotting, and real-time PCR were used to determine the effects of exogenous adenosine triphosphate treatment at different concentrations (2, 4, 6, 8, 10 mmol/L) over time (1, 2, 3, and 6 hours) on the apoptosis and autophagy of SH-SY5Y cells. High concentrations of extracellular adenosine triphosphate induced autophagy and apoptosis of SH-SY5Y cells. The enhanced autophagy ifrst appeared, and peaked at 1 hour after treatment with adenosine triphosphate. Cell apoptosis peaked at 3 hours, and persisted through 6 hours. With prolonged exposure to the adenosine triphosphate treatment, the fraction of apoptotic cells increased. These data suggest that the SH-SY5Y neural cells initiated autophagy against apoptosis within an hour of adenosine triphosphate treatment to protect themselves against injury.

  6. Role of Adenosine Receptor(s) in the Control of Vascular Tone in the Mouse Pudendal Artery.

    Labazi, Hicham; Tilley, Stephen L; Ledent, Catherine; Mustafa, S Jamal

    2016-03-01

    Activation of adenosine receptors (ARs) has been implicated in the modulation of renal and cardiovascular systems, as well as erectile functions. Recent studies suggest that adenosine-mediated regulation of erectile function is mainly mediated through A2BAR activation. However, no studies have been conducted to determine the contribution of AR subtype in the regulation of the vascular tone of the pudendal artery (PA), the major artery supplying and controlling blood flow to the penis. Our aim was to characterize the contribution of AR subtypes and identify signaling mechanisms involved in adenosine-mediated vascular tone regulation in the PA. We used a DMT wire myograph for muscle tension measurements in isolated PAs from wild-type, A2AAR knockout, A2BAR knockout, and A2A/A2BAR double-knockout mice. Real-time reverse transcription-polymerase chain reaction was used to determine the expression of the AR subtypes. Data from our pharmacologic and genetic approaches suggest that AR activation-mediated vasodilation in the PA is mediated by both the A2AAR and A2BAR, whereas neither the A1AR nor A3AR play a role in vascular tone regulation of the PA. In addition, we showed that A2AAR- and A2BAR-mediated vasorelaxation requires activation of nitric oxide and potassium channels; however, only the A2AAR-mediated response requires protein kinase A activation. Our data are complemented by mRNA expression showing the expression of all AR subtypes with the exception of the A3AR. AR signaling in the PA may play an important role in mediating erection and represent a promising therapeutic option for the treatment of erectile dysfunction.

  7. Involvement of adenosine A2a receptor in intraocular pressure decrease induced by 2-(1-octyn-1-yl)adenosine or 2-(6-cyano-1-hexyn-1-yl)adenosine.

    Konno, Takashi; Murakami, Akira; Uchibori, Takehiro; Nagai, Akihiko; Kogi, Kentaro; Nakahata, Norimichi

    2005-04-01

    The aim of the present study is to clarify the mechanism for the decrease in intraocular pressure by 2-alkynyladenosine derivatives in rabbits. The receptor binding analysis revealed that 2-(1-octyn-1-yl)adenosine (2-O-Ado) and 2-(6-cyano-1-hexyn-1-yl)adenosine (2-CN-Ado) selectively bound to the A(2a) receptor with a high affinity. Ocular hypotensive responses to 2-O-Ado and 2-CN-Ado were inhibited by the adenosine A(2a)-receptor antagonist 1,3,7-trimethyl-8-(3-chlorostyryl)xanthine (CSC), but not by the adenosine A(1)-receptor antagonist 8-cyclopentyl-1,3-dipropylxanthine (DPCPX) or the adenosine A(2b)-receptor antagonist alloxazine. In addition, 2-O-Ado and 2-CN-Ado caused an increase in outflow facility, which was inhibited by CSC, but not by DPCPX or alloxazine. Moreover, 2-O-Ado and 2-CN-Ado increased cAMP in the aqueous humor, and the 2-O-Ado-induced an increase in cAMP was inhibited by CSC. These results suggest that 2-O-Ado and 2-CN-Ado reduced intraocular pressure via an increase in outflow facility. The ocular hypotension may be mainly mediated through the activation of adenosine A(2a) receptor, although a possible involvement of adenosine A(1) receptor cannot be completely ruled out. 2-O-Ado and 2-CN-Ado are useful lead compounds for the treatment of glaucoma.

  8. Neuroleptics up-regulate adenosine A2a receptors in rat striatum: implications for the mechanism and the treatment of tardive dyskinesia.

    Parsons, B; Togasaki, D M; Kassir, S; Przedborski, S

    1995-11-01

    Neuroleptics, which are potent dopamine receptor antagonists, are used to treat psychosis. In the striatum, dopamine subtype-2 (D2) receptors interact with high-affinity adenosine subtype-2 (A2a) receptors. To examine the effect of various neuroleptics on the major subtypes of striatal dopamine and adenosine receptors, rats received 28 daily intraperitoneal injections of these drugs. Haloperidol (1.5 mg/kg/day) increased the density of striatal D2 receptors by 24% without changing their affinity for [3H]sulpiride. Haloperidol increased the density of striatal A2a receptors by 33% (control, 522.4 +/- 20.7 fmol/mg of protein; haloperidol, 694.6 +/- 23.6 fmol/mg of protein; p sulpiride (100 mg/kg/day) and clozapine (20 mg/kg/day) did not (control, 290.3 +/- 8.7 fmol/mg of protein; haloperidol, 358.1 +/- 6.9 fmol/mg of protein; fluphenazine, 381.3 +/- 13.6 fmol/mg of protein; sulpiride, 319.8 +/- 18.9 fmol/mg of protein; clozapine, 309.2 +/- 13.7 fmol/mg of protein).(ABSTRACT TRUNCATED AT 250 WORDS)

  9. Inhibition by adenosine of histamine and leukotriene release from human basophils.

    Peachell, P T; Lichtenstein, L M; Schleimer, R P

    1989-06-01

    Adenosine inhibited the release of histamine and leukotriene C4 (LTC4) from immunologically-activated basophils in a dose-dependent manner. Structural congeners of adenosine also attenuated the elaboration of these two mediators from stimulated basophils and a rank order of potency for the inhibition was observed following the sequence 2-chloroadenosine greater than or equal to N-ethylcarboxamidoadenosine (NECA) greater than adenosine greater than or equal to R-phenylisopropyladenosine (R-PIA) greater than or equal to S-PIA. These same nucleosides modulated the generation of LTC4 more potently than the release of histamine. A number of methylxanthines, which are antagonists of cell surface adenosine receptors, reversed the inhibition by adenosine and its congeners of the release of both histamine and LTC4 to varying extents. Dipyridamole and nitrobenzylthioinosine (NBTI), agents that block the intracellular uptake of adenosine, antagonized the inhibition of histamine release by adenosine (and 2-chloroadenosine) but failed to reverse the attenuation of LTC4 generation by the nucleoside. These same uptake blockers were unable to antagonize the inhibitory effects of NECA on either histamine or LTC4 release. In purified basophils, NECA and R-PIA, and in that order of decreasing reactivity, increased total cell cyclic adenosine monophosphate (cAMP) levels and inhibited the stimulated release of mediators. In total, these results suggest that the basophil possesses a cell surface adenosine receptor which, on the basis of both pharmacological and biochemical criteria, most closely conforms to an A2/Ra-like receptor. However, in addition to an interaction at the cell surface, studies with agents that block the intracellular uptake of adenosine suggest that the nucleoside may also exert intracellular effects when countering the release of histamine (but not LTC4).

  10. Sawhorse waveform voltammetry for selective detection of adenosine, ATP, and hydrogen peroxide.

    Ross, Ashley E; Venton, B Jill

    2014-08-05

    Fast-scan cyclic voltammetry (FSCV) is an electrochemistry technique which allows subsecond detection of neurotransmitters in vivo. Adenosine detection using FSCV has become increasingly popular but can be difficult because of interfering agents which oxidize at or near the same potential as adenosine. Triangle shaped waveforms are traditionally used for FSCV, but modified waveforms have been introduced to maximize analyte sensitivity and provide stability at high scan rates. Here, a modified sawhorse waveform was used to maximize the time for adenosine oxidation and to manipulate the shapes of cyclic voltammograms (CVs) of analytes which oxidize at the switching potential. The optimized waveform consists of scanning at 400 V/s from -0.4 to 1.35 V and holding briefly for 1.0 ms followed by a ramp back down to -0.4 V. This waveform allows the use of a lower switching potential for adenosine detection. Hydrogen peroxide and ATP also oxidize at the switching potential and can interfere with adenosine measurements in vivo; however, their CVs were altered with the sawhorse waveform and they could be distinguished from adenosine. Principal component analysis (PCA) was used to determine that the sawhorse waveform was better than the triangle waveform at discriminating between adenosine, hydrogen peroxide, and ATP. In slices, mechanically evoked adenosine was identified with PCA and changes in the ratio of ATP to adenosine were observed after manipulation of ATP metabolism by POM-1. The sawhorse waveform is useful for adenosine, hydrogen peroxide, and ATP discrimination and will facilitate more confident measurements of these analytes in vivo.

  11. 75 FR 8981 - Prospective Grant of Exclusive License: Treatment of Glaucoma by Administration of Adenosine A3...

    2010-02-26

    ... Glaucoma by Administration of Adenosine A3 Antagonists AGENCY: National Institutes of Health, Public Health.../092,292, entitled ``A3 Adenosine Receptor Antagonists,'' filed July 10, 1998 , PCT Application PCT/US99/ 15562, entitled''A3 Adenosine Receptor Antagonists,'' filed July 2, 1999 , U.S. Patent...

  12. Cyclic adenosine 3',5'-monophosphate and germination of sporangiospores from the fungus Mucor.

    Orlowski, M

    1980-06-01

    Cyclic adenosine 3',5'-monophosphate (cAMP) metabolism was examined in germinating sporangiospores of Mucor genevensis and Mucor mucedo. Exogenous cAMP prevented normal hyphal development from sporangiospores. Internal pools of cAMP fluctuated profoundly during development. Spherical growth of the spores was characterized by large pools of cAMP whereas germ tube emergence and hyphal elongation were characterized by small pools of cAMP. These observations suggest a possible role for cAMP in sporangiospore germination. Adenylate cyclase activities fluctuated significantly during germination with maximum values attained during spherical growth. In contrast, cAMP phosphodiesterase activities remained constant throughout germination. Internal cAMP levels may therefore be regulated by adjustment of adenylate cyclase activities. The binding of cAMP by soluble cell proteins was measured. cAMP-binding activity changed greatly during germination. Dormant and spherically growing spores possessed the highest activities. Developing hyphae contained the lowest activities. Use of the photoaffinity label, 8-azido-[32P]cAMP, in conjunction with sodium dodecyl sulfate-polyacrylamide-gel electrophoresis allowed the identification of a small population of morphogenetic-stage-specific proteins which bind cAMP and may be of regulatory significance to development.

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

    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.

  14. Evidence for evoked release of adenosine and glutamate from cultured cerebellar granule cells

    Schousboe, A.; Frandsen, A.; Drejer, J. (Univ. of Copenhagen (Denmark))

    1989-09-01

    Evoked release of ({sup 3}H)-D-aspartate which labels the neurotransmitter glutamate pool in cultured cerebellar granule cells was compared with evoked release of adenosine from similar cultures. It was found that both adenosine and (3H)-D-aspartate could be released from the neurons in a calcium dependent manner after depolarization of the cells with either 10-100 microM glutamate or 50 mM KCl. Cultures of cerebellar granule cells treated with 50 microM kainate to eliminate GABAergic neurons behaved in the same way. This together with the observation that cultured astrocytes did not exhibit a calcium dependent, potassium stimulated adenosine release strongly suggest that cerebellar granule cells release adenosine in a neurotransmitter-like fashion together with glutamate which is the classical neurotransmitter of these neurons. Studies of the metabolism of adenosine showed that in the granule cells adenosine is rapidly metabolized to ATP, ADP, and AMP, but in spite of this, adenosine was found to be released preferential to ATP.

  15. Role of adenosine signalling and metabolism in β-cell regeneration

    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?.

  16. The A2B adenosine receptor impairs the maturation and immunogenicity of dendritic cells.

    Wilson, Jeffrey M; Ross, William G; Agbai, Oma N; Frazier, Renea; Figler, Robert A; Rieger, Jayson; Linden, Joel; Ernst, Peter B

    2009-04-15

    The endogenous purine nucleoside adenosine is an important antiinflammatory mediator that contributes to the control of CD4(+) T cell responses. While adenosine clearly has direct effects on CD4(+) T cells, it remains to be determined whether actions on APC such as dendritic cells (DC) are also important. In this report we characterize DC maturation and function in BMDC stimulated with LPS in the presence or absence of the nonselective adenosine receptor agonist NECA (5'-N-ethylcarboxamidoadenosine). We found that NECA inhibited TNF-alpha and IL-12 in a concentration-dependent manner, whereas IL-10 production was increased. NECA-treated BMDC also expressed reduced levels of MHC class II and CD86 and were less effective at stimulating CD4(+) T cell proliferation and IL-2 production compared with BMDC exposed to vehicle control. Based on real-time RT-PCR, the A(2A) adenosine receptor (A(2A)AR) and A(2B)AR were the predominant adenosine receptors expressed in BMDC. Using adenosine receptor subtype selective antagonists and BMDC derived from A(2A)AR(-/-) and A(2B)AR(-/-)mice, it was shown that NECA modulates TNF-alpha, IL-12, IL-10, and CD86 responses predominantly via A(2B)AR. These data indicate that engagement of A(2B)AR modifies murine BMDC maturation and suggest that adenosine regulates CD4(+) T cell responses by selecting for DC with impaired immunogencity.

  17. Adenosine Monophosphate-Based Detection of Bacterial Spores

    Kern, Roger G.; Chen, Fei; Venkateswaran, Kasthuri; Hattori, Nori; Suzuki, Shigeya

    2009-01-01

    A method of rapid detection of bacterial spores is based on the discovery that a heat shock consisting of exposure to a temperature of 100 C for 10 minutes causes the complete release of adenosine monophosphate (AMP) from the spores. This method could be an alternative to the method described in the immediately preceding article. Unlike that method and related prior methods, the present method does not involve germination and cultivation; this feature is an important advantage because in cases in which the spores are those of pathogens, delays involved in germination and cultivation could increase risks of infection. Also, in comparison with other prior methods that do not involve germination, the present method affords greater sensitivity. At present, the method is embodied in a laboratory procedure, though it would be desirable to implement the method by means of a miniaturized apparatus in order to make it convenient and economical enough to encourage widespread use.

  18. Late-onset adenosine deaminase deficiency presenting with Heck's disease.

    Artac, Hasibe; Göktürk, Bahar; Bozdemir, Sefika Elmas; Toy, Hatice; van der Burg, Mirjam; Santisteban, Ines; Hershfield, Michael; Reisli, Ismail

    2010-08-01

    Focal epithelial hyperplasia, also known as Heck's disease, is a rare but distinctive entity of viral etiology with characteristic clinical and histopathological features. It is a benign, asymptomatic disease of the oral mucosa caused by human papilloma viruses (HPV). Previous studies postulated an association between these lesions and immunodeficiency. Genetic deficiency of adenosine deaminase (ADA) results in varying degrees of immunodeficiency, including neonatal onset severe combined immunodeficiency (ADA-SCID), and milder, later onset immunodeficiency. We report a 12-year-old girl with the late onset-ADA deficiency presenting with Heck's disease. Our case report should draw attention to the possibility of immunodeficiency in patients with HPV-induced focal epithelial hyperplasia.

  19. Adenosine-5'-phosphosulfate kinase is essential for Arabidopsis viability.

    Mugford, Sarah G; Matthewman, Colette A; Hill, Lionel; Kopriva, Stanislav

    2010-01-04

    In Arabidopsis thaliana, adenosine-5'-phosphosulfate kinase (APK) provides activated sulfate for sulfation of secondary metabolites, including the glucosinolates. We have successfully isolated three of the four possible triple homozygous mutant combinations of this family. The APK1 isoform alone was sufficient to maintain WT levels of growth and development. Analysis of apk1 apk2 apk3 and apk1 apk3 apk4 mutants suggests that APK3 and APK4 are functionally redundant, despite being located in cytosol and plastids, respectively. We were, however, unable to isolate apk1 apk3 apk4 mutants, most probably because the apk1 apk3 apk4 triple mutant combination is pollen lethal. Therefore, we conclude that APS kinase is essential for plant reproduction and viability.

  20. Crystallization and preliminary X-ray crystallographic analysis of the tRNA-specific adenosine deaminase from Streptococcus pyogenes

    Ku, Min-Je [Functional Proteomics Center, Korea Institute of Science and Technology, 39-1 Hawolgok-dong, Seongbuk-gu, Seoul 136-791 (Korea, Republic of); Lee, Won-Ho [Functional Proteomics Center, Korea Institute of Science and Technology, 39-1 Hawolgok-dong, Seongbuk-gu, Seoul 136-791 (Korea, Republic of); Biotechnology and Genetic Engineering, Korea University, Seoul 136-701 (Korea, Republic of); Nam, Ki-hyun; Rhee, Kyeong-hee [Biomedical Research Center, Life Science Division, Korea Institute of Science and Technology, 39-1 Hawolgok-dong, Seongbuk-gu, Seoul 136-791 (Korea, Republic of); Lee, Ki-Seog [Biotechnology and Genetic Engineering, Korea University, Seoul 136-701 (Korea, Republic of); Kim, Eunice EunKyung [Biomedical Research Center, Life Science Division, Korea Institute of Science and Technology, 39-1 Hawolgok-dong, Seongbuk-gu, Seoul 136-791 (Korea, Republic of); Yu, Myung-Hee [Functional Proteomics Center, Korea Institute of Science and Technology, 39-1 Hawolgok-dong, Seongbuk-gu, Seoul 136-791 (Korea, Republic of); Hwang, Kwang Yeon, E-mail: hwangky@kist.re.kr [Biomedical Research Center, Life Science Division, Korea Institute of Science and Technology, 39-1 Hawolgok-dong, Seongbuk-gu, Seoul 136-791 (Korea, Republic of); Functional Proteomics Center, Korea Institute of Science and Technology, 39-1 Hawolgok-dong, Seongbuk-gu, Seoul 136-791 (Korea, Republic of)

    2005-04-01

    The tRNA-specific adenosine deaminase from the pathogenic bacteria S. pyogenes has been overexpressed and crystallized. The tRNA-specific adenosine deaminase from the pathogenic bacteria Streptococcus pyogenes (spTAD) has been overexpressed in Escherichia coli and crystallized in the presence of Zn{sup 2+} ion at 295 K using ammonium sulfate as a precipitant. Flash-cooled crystals of spTAD diffracted to 2.0 Å using 30%(v/v) glycerol as a cryoprotectant. X-ray diffraction data have been collected to 2.0 Å using synchrotron radiation. The crystal belongs to the tetragonal space group P4{sub 2}2{sub 1}2, with unit-cell parameters a = b = 81.042, c = 81.270 Å. The asymmetric unit contains one subunit of spTAD, with a corresponding crystal volume per protein weight (V{sub M}) of 3.3 Å{sup 3} Da{sup −1} and a solvent content of 62.7%.

  1. Vasodilator effects of adenosine on retinal arterioles in streptozotocin-induced diabetic rats.

    Nakazawa, Taisuke; Mori, Asami; Saito, Maki; Sakamoto, Kenji; Nakahara, Tsutomu; Ishii, Kunio

    2008-02-01

    Adenosine is a potent vasodilator of retinal blood vessels and is implicated to be a major regulator of retinal blood flow during metabolic stress, but little is known about the impact of diabetes on the role of adenosine in regulation of retinal hemodynamics. Therefore, we examined how diabetes affects adenosine-induced vasodilation of retinal arterioles. Male Wistar rats were treated with streptozotocin (80 mg/kg, intraperitoneally), and experiments were performed 6-8 weeks later. Rats were treated with tetrodotoxin (50 microg/kg, intravenously [i.v.]) to eliminate any nerve activity and prevent movement of the eye and infused with methoxamine continuously to maintain adequate systemic circulation. Fundus images were captured with a digital camera that was equipped with a special objective lens, and diameters of retinal arterioles were measured. Adenosine increased diameters of retinal arterioles and decreased systemic blood pressure. These responses were significantly attenuated by the nitric oxide synthase inhibitor N(G)-nitro-L-arginine methyl ester (30 mg/kg, i.v.) and the adenosine triphosphate-dependent K+ (K(ATP)) channel blocker glibenclamide (20 mg/kg, i.v.). The depressor responses to adenosine were reduced in diabetic rats, whereas diabetes did not alter vasodilation of retinal arterioles to adenosine. In contrast, both depressor response and vasodilation of retinal arteriole to acetylcholine were reduced in diabetic rats. The retinal vasodilator responses to adenosine and acetylcholine observed in diabetic rats were diminished by N(G)-nitro-L-arginine methyl ester. There were no differences in the responses to pinacidil, a K(ATP) channel opener, between the diabetic and nondiabetic rats. These results suggest that both the activation of nitric oxide synthase and opening of K(ATP) channels contribute to the vasodilator effects of adenosine in rats in vivo. However, diabetes has no significant impact on the vasodilation mediated by these mechanisms in

  2. Severe hemorrhage attenuates cardiopulmonary chemoreflex control of regional sympathetic outputs via NTS adenosine receptors.

    Minic, Zeljka; Li, Cailian; O'Leary, Donal S; Scislo, Tadeusz J

    2014-09-15

    Selective stimulation of inhibitory A1 and facilitatory A2a adenosine receptor subtypes located in the nucleus of the solitary tract (NTS) powerfully inhibits cardiopulmonary chemoreflex (CCR) control of regional sympathetic outputs via different mechanisms: direct inhibition of glutamate release and facilitation of an inhibitory neurotransmitter release, respectively. However, it remains unknown whether adenosine naturally released into the NTS has similar inhibitory effects on the CCR as the exogenous agonists do. Our previous study showed that adenosine is released into the NTS during severe hemorrhage and contributes to reciprocal changes of renal (decreases) and adrenal (increases) sympathetic nerve activity observed in this setting. Both A1 and A2a adenosine receptors are involved. Therefore, we tested the hypothesis that, during severe hemorrhage, CCR control of the two sympathetic outputs is attenuated by adenosine naturally released into the NTS. We compared renal and adrenal sympathoinhibitory responses evoked by right atrial injections of 5HT3 receptor agonist phenylbiguanide (2-8 μg/kg) under control conditions, during hemorrhage, and during hemorrhage preceded by blockade of NTS adenosine receptors with bilateral microinjections of 8-(p-sulfophenyl) theophylline (1 nmol/100 nl) in urethane/chloralose anesthetized rats. CCR-mediated inhibition of renal and adrenal sympathetic activity was significantly attenuated during severe hemorrhage despite reciprocal changes in the baseline activity levels, and this attenuation was removed by bilateral blockade of adenosine receptors in the caudal NTS. This confirmed that adenosine endogenously released into the NTS has a similar modulatory effect on integration of cardiovascular reflexes as stimulation of NTS adenosine receptors with exogenous agonists.

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

    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− chann...

  4. Adenine arabinoside inhibition of adenovirus replication enhanced by an adenosine deaminase inhibitor.

    Wigand, R

    1979-01-01

    The inhibition of adenovirus multiplication by adenine arabinoside was determined by yield reduction in one-step multiplication cycle. Inhibition was greatly enhanced by an adenosine deaminase inhibitor (2-deoxycoformycin) in concentrations down to 10 ng/ml. Adenovirus types from four subgroups showed similar results. However, the enhancing effect of adenosine deaminase inhibitor was great in HeLa cells, moderate in human fibroblasts, and negligible in Vero cells. This difference could be explained by different concentrations of adenosine deaminase found in cell homogenates.

  5. An STS in the human adenosine deaminase gene (located 20q12-q13. 11)

    Freeman, B.C.; States, J.C. (Wayne State Univ., Detroit, MI (United States))

    1991-09-25

    The human adenosine deaminase gene has been characterized in detail. The adenosine gene product, as part of the purine catabolic pathway, catalyzes the irreversible deamination of adenosine and deoxyadenosine. Deficiency of this activity in humans is associated with an autosomal recessive form of severe combined immunodeficiency disease. Recently, this genetic deficiency disease has been targeted for the first attempts at gene therapy in humans. Using the polymerase chain reaction (PCR), a fragment of the expected size (160 bp) was amplified from human genomic DNA.

  6. Adenosine A2A receptor binding profile of two antagonists, ST1535 and KW6002: consideration on the presence of atypical adenosine A2A binding sites

    Teresa Riccioni

    2010-08-01

    Full Text Available Adenosine A2A receptors seem to exist in typical (more in striatum and atypical (more in hippocampus and cortex subtypes. In the present study, we investigated the affinity of two adenosine A2A receptor antagonists, ST1535 [2 butyl -9-methyl-8-(2H-1,2,3-triazol 2-yl-9H-purin-6-xylamine] and KW6002 [(E-1,3-diethyl-8-(3,4-dimethoxystyryl-7-methyl-3,7-dihydro-1H-purine-2,6,dione] to the “typical” and “atypical” A2A binding sites. Affinity was determined by radioligand competition experiments in membranes from rat striatum and hippocampus. Displacement of the adenosine analog [3H]CGS21680 [2-p-(2-carboxyethylphenethyl-amino-5’-N-ethylcarbox-amidoadenosine] was evaluated in the absence or in the presence of either CSC [8-(3-chlorostyryl-caffeine], an adenosine A2A antagonist that pharmacologically isolates atypical binding sites, or DPCPX (8-cyclopentyl-1,3-dipropylxanthine, an adenosine A1 receptor antagonist that pharmacologically isolates typical binding site. ZM241385 [84-(2-[7-amino-2-(2-furyl [1,2,4]-triazol[2,3-a][1,3,5]triazin-5-yl amino]ethyl phenol] and SCH58261 [(5-amino-7-(β-phenylethyl-2-(8-furylpyrazolo(4,3-e-1,2,4-triazolo(1,5-c pyrimidine], two other adenosine A2A receptor antagonists, which were reported to differently bind to atypical and typical A2A receptors, were used as reference compounds. ST1535, KW6002, ZM241385 and SCH58261 displaced [3H]CGS21680 with higher affinity in striatum than in hippocampus. In hippocampus, no typical adenosine A2A binding was detected, and ST1535 was the only compound that occupied atypical A2A adenosine receptors. Present data are explained in terms of heteromeric association among adenosine A2A, A2B and A1 receptors, rather than with the presence of atypical A2A receptor subtype.

  7. The role of muscarinic receptors in the beneficial effects of adenosine against myocardial reperfusion injury in rats.

    Lei Sun

    Full Text Available Adenosine, a catabolite of ATP, displays a wide variety of effects in the heart including regulation of cardiac response to myocardial ischemia and reperfusion injury. Nonetheless, the precise mechanism of adenosine-induced cardioprotection is still elusive. Isolated Sprague-Dawley rat hearts underwent 30 min global ischemia and 120 min reperfusion using a Langendorff apparatus. Both adenosine and acetylcholine treatment recovered the post-reperfusion cardiac function associated with adenosine and muscarinic receptors activation. Simultaneous administration of adenosine and acetylcholine failed to exert any additive protective effect, suggesting a shared mechanism between the two. Our data further revealed a cross-talk between the adenosine and acetylcholine receptor signaling in reperfused rat hearts. Interestingly, the selective M(2 muscarinic acetylcholine receptor antagonist methoctramine significantly attenuated the cardioprotective effect of adenosine. In addition, treatment with adenosine upregulated the expression and the maximal binding capacity of muscarinic acetylcholine receptor, which were inhibited by the selective A(1 adenosine receptor antagonist 8-Cyclopentyl-1,3-dipropylxanthine (DPCPX and the nitric oxide synthase inhibitor N(ω-nitro-L-arginine methyl ester (L-NAME. These data suggested a possible functional coupling between the adenosine and muscarinic receptors behind the observed cardioprotection. Furthermore, nitric oxide was found involved in triggering the response to each of the two receptor agonist. In summary, there may be a cross-talk between the adenosine and muscarinic receptors in ischemic/reperfused myocardium with nitric oxide synthase might serve as the distal converging point. In addition, adenosine contributes to the invigorating effect of adenosine on muscarinic receptor thereby prompting to regulation of cardiac function. These findings argue for a potentially novel mechanism behind the adenosine

  8. Adenosine A2A receptor and ecto-5'-nucleotidase/CD73 are upregulated in hippocampal astrocytes of human patients with mesial temporal lobe epilepsy (MTLE).

    Barros-Barbosa, Aurora R; Ferreirinha, Fátima; Oliveira, Ângela; Mendes, Marina; Lobo, M Graça; Santos, Agostinho; Rangel, Rui; Pelletier, Julie; Sévigny, Jean; Cordeiro, J Miguel; Correia-de-Sá, Paulo

    2016-12-01

    Refractoriness to existing medications of up to 80 % of the patients with mesial temporal lobe epilepsy (MTLE) prompts for finding new antiepileptic drug targets. The adenosine A2A receptor emerges as an interesting pharmacological target since its excitatory nature partially counteracts the dominant antiepileptic role of endogenous adenosine acting via inhibitory A1 receptors. Gain of function of the excitatory A2A receptor has been implicated in a significant number of brain pathologies commonly characterized by neuronal excitotoxicity. Here, we investigated changes in the expression and cellular localization of the A2A receptor and of the adenosine-generating enzyme, ecto-5'-nucleotidase/CD73, in the hippocampus of control individuals and MTLE human patients. Western blot analysis indicates that the A2A receptor is more abundant in the hippocampus of MTLE patients compared to control individuals. Immunoreactivity against the A2A receptor predominates in astrocytes staining positively for the glial fibrillary acidic protein (GFAP). No co-localization was observed between the A2A receptor and neuronal cell markers, like synaptotagmin 1/2 (nerve terminals) and neurofilament 200 (axon fibers). Hippocampal astrogliosis observed in MTLE patients was accompanied by a proportionate increase in A2A receptor and ecto-5'-nucleotidase/CD73 immunoreactivities. Given our data, we hypothesize that selective blockade of excessive activation of astrocytic A2A receptors and/or inhibition of surplus adenosine formation by membrane-bound ecto-5'-nucleotidase/CD73 may reduce neuronal excitability, thus providing a novel therapeutic target for drug-refractory seizures in MTLE patients.

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

    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.

  10. Elevated erythrocyte adenosine deaminase activity in a patient with primary acquired sideroblastic anemia.

    Kanno, H; Fujii, H; Tani, K; Morisaki, T; Takahashi, K; Horiuchi, N; Kizaki, M; Ogawa, T; Miwa, S

    1988-03-01

    We report a case of primary acquired sideroblastic anemia (PASA) associated with elevated erythrocyte adenosine deaminase (ADA) activity. The patient was an 85-year-old Japanese male. Analysis of the peripheral blood revealed pancytopenia, and the bone marrow findings showed marked ringed sideroblasts and chromosomal deletion (46XY, 11q-). The erythrocyte ADA activity was 17 times higher than that of normal control, the leukocyte ADA activity was within the normal range, and the plasma ADA activity was 2 times higher than the normal mean. The adenine nucleotides in the patient's erythrocytes were within normal range. According to starch gel electrophoresis, ADA isozyme of the patient was ADA 1. Western blotting showed an increased amount of ADA protein in the patient's erythrocytes. Southern blotting revealed no gene amplification or large structural change. Dot blot analysis of the reticulocyte mRNA showed no increase in the amount of ADA mRNA in the patient's reticulocytes compared with those of reticulocyte-rich controls. We considered that the mechanism of elevated ADA activity in this acquired defect was similar to that found in hereditary hemolytic anemia associated with ADA overproduction.

  11. Roles and mechanisms of the CD38/cyclic adenosine diphosphate ribose/Ca2+ signaling pathway

    Wenjie; Wei; Richard; Graeff; Jianbo; Yue

    2014-01-01

    Mobilization of intracellular Ca2+ stores is involved inmany diverse cell functions, including: cell proliferation;differentiation; fertilization; muscle contraction; secre-tion of neurotransmitters, hormones and enzymes;and lymphocyte activation and proliferation. Cyclic ad-enosine diphosphate ribose(cADPR) is an endogenousCa2+ mobilizing nucleotide present in many cell typesand species, from plants to animals. cADPR is formedby ADP-ribosyl cyclases from nicotinamide adenine di-nucleotide. The main ADP-ribosyl cyclase in mammalsis CD38, a multi-functional enzyme and a type Ⅱ mem-brane protein. It has been shown that many extracel-lular stimuli can induce cADPR production that leadsto calcium release or influx, establishing cADPR as asecond messenger. cADPR has been linked to a widevariety of cellular processes, but the molecular mecha-nisms regarding cADPR signaling remain elusive. Theaim of this review is to summarize the CD38/cADPR/Ca2+ signaling pathway, focusing on the recent advanc-es involving the mechanism and physiological functionsof cADPR-mediated Ca2+ mobilization.

  12. Fine mapping and functional activity of the adenosine deaminase origin in murine embryonic fibroblasts.

    Sibani, Sahar; Rampakakis, Emmanouil; Di Paola, Domenic; Zannis-Hadjopoulos, Maria

    2008-06-01

    DNA replication initiates at origins within the genome. The late-firing murine adenosine deaminase (mAdA) origin is located within a 2 kb fragment of DNA, making it difficult to examine by realtime technology. In this study, fine mapping of the mAdA region by measuring the abundance of nascent strand DNA identified two origins, mAdA-1 and mAdA-C, located 397 bp apart from each other. Both origins conferred autonomous replication to plasmids transfected in murine embryonic fibroblasts (MEFs), and exhibited similar activities in vivo and in vitro. Furthermore, both were able to recruit the DNA replication initiator proteins Cdc6 and Ku in vitro, similar to other bona fide replication origins. When tested in a murine Ku80(-/-) cell line, both origins exhibited replication activities comparable to those observed in wildtype cells, as did the hypoxanthine-guanine phosphoribosyltransferase (HPRT) and c-myc origins. This contrasts with previously published studies using Ku80-deficient human cells lines and suggests differences in the mechanism of initiation of DNA replication between the murine and human systems.

  13. Site-directed mutagenesis and bacterial expression of human adenosine deaminase

    Danton, M.J.; Leonardo, J.; Riley, L.; Coleman, M.S.

    1987-05-01

    Adenosine deaminase (ADA) is a purine salvage pathway enzyme, the absence of which is associated with severe combined immunodeficiency disease. Time-resolved fluorescence studies, in the presence of enzyme inhibitors, indicate that at least one of the four tryptophans present in the protein molecule is close to (or in) the active site. To investigate the role of these tryptophan residues in enzyme function, they have cloned ADA cDNA into a vector in which expression is directed by the lambda P/sub R/ promoter. E. coli cells deficient in ADA were transformed with the vector construct and were shown to synthesize catalytically active human ADA. Site directed mutagenesis, coupled with a uracil selection technique for generating mutants with high efficiency, was used to construct mutant alleles of the cloned ADA. Eight mutants were obtained with base substitutions converting each of the four tryptophans to arginine or glycine. The correlation between these specific mutations and the functional expression of ADA has been examined in the ADA deficient bacterial host.

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

    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

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

    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

  16. Evidence that the positive inotropic effects of the alkylxanthines are not due to adenosine receptor blockade.

    Collis, M. G.; Keddie, J. R.; Torr, S. R.

    1984-01-01

    We investigated the possibility that the positive inotropic effects of the alkylxanthines are due to adenosine receptor blockade. The potency of 8-phenyltheophylline, theophylline and enprofylline as adenosine antagonists was assessed in vitro, using the guinea-pig isolated atrium, and in vivo, using the anaesthetized dog. The order of potency of the alkylxanthines as antagonists of the negative inotropic response to 2-chloroadenosine in vitro, and of the hypotensive response to adenosine in vivo was 8-phenyltheophylline greater than theophylline greater than enprofylline. The order of potency of the alkylxanthines as positive inotropic and chronotropic agents in the anaesthetized dog was enprofylline greater than theophylline greater than 8-phenyltheophylline. The results of this study indicate that the inotropic effects of the alkylxanthines in the anaesthetized dog are not due to adenosine receptor blockade. PMID:6322898

  17. ALLERGEN-INDUCED CHANGES IN ADENOSINE 5'-MONOPHOSPHATE BRONCHIAL RESPONSIVENESS - EFFECT OF NEDOCROMIL SODIUM

    AALBERS, R; KAUFMAN, HF; GROEN, H; KOETER, GH; DEMONCHY, JGR

    1992-01-01

    Bronchial hyperresponsiveness to adenosine 5'-monophosphate (AMP) was studied after allergen challenge in allergic asthmatic patients. Measurements were made with and without nedocromil sodium pretreatment. Nedocromil sodium inhibited both the early and late asthmatic reactions (P <.01). After aller

  18. Targeting the inflammasome and adenosine type-3 receptors improves outcome of antibiotic therapy in murine anthrax

    Popov, Serguei G.; Popova, Taissia G.; Kashanchi, Fatah; Bailey, Charles

    2011-01-01

    AIM: To establish whether activation of adenosine type-3 receptors (A3Rs) and inhibition of interleukin-1β-induced inflammation is beneficial in combination with antibiotic therapy to increase survival of mice challenged with anthrax spores.

  19. Role of adenosine in regulating the heterogeneity of skeletal muscle blood flow during exercise in humans

    Heinonen, Ilkka; Nesterov, Sergey V; Kemppainen, Jukka;

    2007-01-01

    ) muscles during exercise, measured using positron emission tomography. In six healthy young women, BF was measured at rest and then during three incremental low and moderate intermittent isometric one-legged knee-extension exercise intensities without and with theophylline-induced nonselective adenosine...... exercise intensity in the QF muscle group. Adenosine seems to play a role in muscle BF heterogeneity even in the absence of changes in bulk BF at low and moderate one-leg intermittent isometric exercise intensities.......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...

  20. Effect of insulin and glucose on adenosine metabolizing enzymes in human B lymphocytes.

    Kocbuch, Katarzyna; Sakowicz-Burkiewicz, Monika; Grden, Marzena; Szutowicz, Andrzej; Pawelczyk, Tadeusz

    2009-01-01

    In diabetes several aspects of immunity are altered, including the immunomodulatory action of adenosine. Our study was undertaken to investigate the effect of different glucose and insulin concentrations on activities of adenosine metabolizing enzymes in human B lymphocytes line SKW 6.4. The activity of adenosine deaminase in the cytosolic fraction was very low and was not affected by different glucose concentration, but in the membrane fraction of cells cultured with 25 mM glucose it was decreased by about 35% comparing to the activity in cells maintained in 5 mM glucose, irrespective of insulin concentration. The activities of 5'-nucleotidase (5'-NT) and ecto-5'-NT in SKW 6.4 cells depended on insulin concentration, but not on glucose. Cells cultured with 10(-8) M insulin displayed an about 60% lower activity of cytosolic 5'-NT comparing to cells maintained at 10(-11) M insulin. The activity of ecto-5'-NT was decreased by about 70% in cells cultured with 10(-8) M insulin comparing to cells grown in 10(-11) M insulin. Neither insulin nor glucose had an effect on adenosine kinase (AK) activity in SKW 6.4 cells or in human B cells isolated from peripheral blood. The extracellular level of adenosine and inosine during accelerated catabolism of cellular ATP depended on glucose, but not on insulin concentration. Concluding, our study demonstrates that glucose and insulin differentially affect the activities of adenosine metabolizing enzymes in human B lymphocytes, but changes in those activities do not correlate with the adenosine level in cell media during accelerated ATP catabolism, implying that nucleoside transport is the primary factor determining the extracellular level of adenosine.

  1. Role of adenosine A1 and A2A receptors in the alcohol withdrawal syndrome.

    Kaplan, G B; Bharmal, N H; Leite-Morris, K A; Adams, W R

    1999-10-01

    The role of adenosine receptor-mediated signaling was examined in the alcohol withdrawal syndrome. CD-1 mice received a liquid diet containing ethanol (6.7%, v/v) or a control liquid diet that were abruptly discontinued after 14 days of treatment. Mice consuming ethanol showed a progressive increase in signs of intoxication throughout the drinking period. Following abrupt discontinuation of ethanol diet, mice demonstrated reversible signs of handling-induced hyperexcitability that were maximal between 5-8 h. Withdrawing mice received treatment with adenosine receptor agonists at the onset of peak withdrawal (5.5 h) and withdrawal signs were blindly rated (during withdrawal hours 6 and 7). Adenosine A1-receptor agonist R-N6(phenylisopropyl)adenosine (0.15 and 0.3 mg/ kg) reduced withdrawal signs 0.5 and 1.5 h after drug administration in a dose-dependent fashion. Adenosine A2A-selective agonist 2-p-(2-carboxyethyl)phenylethyl-amino-5'-N-ethylcarboxamidoadenosine (0.3 mg/kg) reduced withdrawal signs at both time points. In ethanol-withdrawing mice, there were significant decreases in adenosine transporter sites in striatum without changes in cortex or cerebellum. In ethanol-withdrawing mice, there were no changes in adenosine A1 and A2A receptor concentrations in cortex, striatum, or cerebellum. There appears to be a role for adenosine A1 and A2A receptors in the treatment of the ethanol withdrawal syndrome. Published by Elsevier Science Inc.

  2. Sitagliptin attenuates sympathetic innervation via modulating reactive oxygen species and interstitial adenosine in infarcted rat hearts.

    Lee, Tsung-Ming; Chen, Wei-Ting; Yang, Chen-Chia; Lin, Shinn-Zong; Chang, Nen-Chung

    2015-02-01

    We investigated whether sitagliptin, a dipeptidyl peptidase-4 (DPP-4) inhibitor, attenuates arrhythmias through inhibiting nerve growth factor (NGF) expression in post-infarcted normoglycemic rats, focusing on adenosine and reactive oxygen species production. DPP-4 bound adenosine deaminase has been shown to catalyse extracellular adenosine to inosine. DPP-4 inhibitors increased adenosine levels by inhibiting the complex formation. Normoglycemic male Wistar rats were subjected to coronary ligation and then randomized to either saline or sitagliptin in in vivo and ex vivo studies. Post-infarction was associated with increased oxidative stress, as measured by myocardial superoxide, nitrotyrosine and dihydroethidium fluorescent staining. Measurement of myocardial norepinephrine levels revealed a significant elevation in vehicle-treated infarcted rats compared with sham. Compared with vehicle, infarcted rats treated with sitagliptin significantly increased interstitial adenosine levels and attenuated oxidative stress. Sympathetic hyperinnervation was blunted after administering sitagliptin, as assessed by immunofluorescent analysis and western blotting and real-time quantitative RT-PCR of NGF. Arrhythmic scores in the sitagliptin-treated infarcted rats were significantly lower than those in vehicle. Ex vivo studies showed a similar effect of erythro-9-(2-hydroxy-3-nonyl) adenine (an adenosine deaminase inhibitor) to sitagliptin on attenuated levels of superoxide and NGF. Furthermore, the beneficial effects of sitagliptin on superoxide anion production and NGF levels can be reversed by 8-cyclopentyl-1,3-dipropulxanthine (adenosine A1 receptor antagonist) and exogenous hypoxanthine. Sitagliptin protects ventricular arrhythmias by attenuating sympathetic innervation via adenosine A1 receptor and xanthine oxidase-dependent pathways, which converge through the attenuated formation of superoxide in the non-diabetic infarcted rats.

  3. Adenosine actions on CA1 pyramidal neurones in rat hippocampal slices.

    Greene, R W; Haas, H L

    1985-09-01

    Intracellular recordings with a bridge amplifier of CA1 pyramidal neurones in vitro were employed to study the mechanisms of action of exogenously applied adenosine in the hippocampal slice preparation of the rat. Adenosine enhanced the calcium-dependent, long-duration after-hyperpolarization (a.h.p.) at least in part by a reduction in the rate of decay of the a.h.p. Both the reduced rate of decay and that of the control can be described with a single exponential. Antagonism of the calcium-dependent potassium current (and as a result, the a.h.p.) by bath application of CdCl2 or intracellular injection of EGTA (ethyleneglycolbis-(beta-aminoethyl ether)N,N'-tetraacetic acid) did not reduce the adenosine-evoked hyperpolarization or decrease in input resistance. Similarly, TEA (tetraethylammonium), which antagonizes both the voltage- and calcium-sensitive, delayed, outward rectification, had no effect on the adenosine-evoked changes in resting membrane properties. Adenosine did not affect the early, transient, outward rectification. During exposure to 4-aminopyridine (4-AP) in concentrations sufficient to antagonize this early rectification, the changes in resting membrane properties evoked by adenosine were unaffected. We conclude that the enhancement of the a.h.p. and accommodation by adenosine may be mediated by a change in the regulation of intracellular calcium. However, the mechanism responsible for the hyperpolarization and decrease in input resistance evoked by adenosine is both calcium and voltage insensitive. Thus, it appears distinct from that mediating the enhancement of the a.h.p. and accommodation.

  4. Online cleanup of accelerated solvent extractions for determination of adenosine 5'-triphosphate (ATP), adenosine 5'-diphosphate (ADP), and adenosine 5'-monophosphate (AMP) in royal jelly using high-performance liquid chromatography.

    Xue, Xiaofeng; Wang, Feng; Zhou, Jinhui; Chen, Fang; Li, Yi; Zhao, Jing

    2009-06-10

    Determination of the levels of adenosine 5'-triphosphate (ATP), adenosine 5'-diphosphate (ADP), and adenosine 5'-monophosphate (AMP) in royal jelly is important for the study of its pharmacological activities, health benefits, and adenosine phosphate degradation. In this study was developed a novel method to determine ATP, ADP, and AMP levels in royal jelly using accelerated solvent extraction (ASE) followed by online cleanup and high-performance liquid chromatography (HPLC) with diode array detection (DAD). The optimum extraction conditions were obtained using an 11 mL ASE cell, ethanol/water (5:5 v/v) as the extraction solvent, 1500 psi, 80 degrees C, a 5 min static time, and a 60% flush volume. Optimum separation of the three compounds was achieved in AMP levels in 15 samples of royal jelly of different origins was performed. Sample results indicated that the AMP concentration was 24.2-2214.4 mg kg(-1), whereas ATP and ADP were not detectable or present only at low levels.

  5. In vivo effects of adenosine 5´-triphosphate on rat preneoplastic liver

    Ana V. Frontini

    2011-04-01

    Full Text Available The utilization of adenosine 5´-triphosphate (ATP infusions to inhibit the growth of some human and animals tumors was based on the anticancer activity observed in in vitro and in vivo experiments, but contradictory results make the use of ATP in clinical practice rather controversial. Moreover, there is no literature regarding the use of ATP infusions to treat hepatocarcinomas. The purpose of this study was to investigate whether ATP prevents in vivo oncogenesis in very-early-stage cancer cells in a well characterized two-stage model of hepatocarcinogenesis in the rat. As we could not preclude the possible effect due to the intrinsic properties of adenosine, a known tumorigenic product of ATP hydrolysis, the effect of the administration of adenosine was also studied. Animals were divided in groups: rats submitted to the two stage preneoplasia initiation/promotion model of hepatocarcinogenesis, rats treated with intraperitoneal ATP or adenosine during the two phases of the model and appropriate control groups. The number and volume of preneoplastic foci per liver identified by the expression of glutathione S-transferase placental type and the number of proliferating nuclear antigen positive cells significantly increased in ATP and adenosine treated groups. Taken together, these results indicate that in this preneoplastic liver model, ATP as well as adenosine disturb the balance between apoptosis and proliferation contributing to malignant transformation.

  6. Serum adenosine deaminase as oxidative stress marker in type 2 diabetes mellitus

    Shashikala Magadi Dasegowda

    2015-05-01

    Results: The study observed an increased level of serum adenosine deaminase, malondialdehyde and decreased levels of total antioxidant capacity in type 2 diabetes mellitus compared to controls. Serum adenosine deaminase levels in type 2 diabetics were 50.77 +/- 6.95 and in controls was 17.86 +/- 4.04. Serum Malondialdehyde levels in type 2 diabetics was 512.13 +/- 70.15 and in controls was 239.32 +/- 23.97. Serum total antioxidant levels in type 2 diabetics was 0.39+/-0.15 and in controls was 1.66+/-0.25. Positive correlation was seen between serum adenosine deaminase and malondialdehyde and it was statistically significant. Statistically significant negative correlation was seen between serum adenosine deaminase and total antioxidant capacity. Conclusion: Adenosine deaminase can be used as oxidative stress marker. Their increased levels indicate oxidative stress in type 2 diabetes mellitus. Therefore, estimation of serum adenosine deaminase levels help in early prediction and prevention of long term complications occurring due to oxidative stress in diabetics, thereby decreasing the mortality and morbidity in them. [Int J Res Med Sci 2015; 3(5.000: 1195-1198

  7. Adenosine concentrations in the interstitium of resting and contracting human skeletal muscle

    Hellsten, Ylva; Maclean, D.; Rådegran, G.

    1998-01-01

    BACKGROUND: Adenosine has been proposed to be a locally produced regulator of blood flow in skeletal muscle. However, the fundamental questions of to what extent adenosine is formed in skeletal muscle tissue of humans, whether it is present in the interstitium, and where it exerts its vasodilator...... and demonstrates that adenosine and its precursors increase in the exercising muscle interstitium, at a rate associated with intensity of muscle contraction and the magnitude of muscle blood flow.......BACKGROUND: Adenosine has been proposed to be a locally produced regulator of blood flow in skeletal muscle. However, the fundamental questions of to what extent adenosine is formed in skeletal muscle tissue of humans, whether it is present in the interstitium, and where it exerts its vasodilatory...... effect remain unanswered. METHODS AND RESULTS: The interstitial adenosine concentration was determined in the vastus lateralis muscle of healthy humans via dialysis probes inserted in the muscle. The probes were perfused with buffer, and the dialysate samples were collected at rest and during graded knee...

  8. Localization of Adenosine Triphosphatase Activity on the Chloroplast Envelope in Tendrils of Pisum sativum1

    Sabnis, Dinkar D.; Gordon, Mildred; Galston, Arthur W.

    1970-01-01

    When samples of pea tendril tissue were incubated in the Wachstein-Meisel medium for the demonstration of adenosine triphosphatases, deposits of lead reaction product were localized between the membranes of the chloroplast envelope. The presence of Mg2+ was necessary for adenosine triphosphatase activity, and Ca2+ could not substitute for this requirement. Varying the pH of incubation to 5.5 or 9.4 inhibited enzyme activity, as did the addition of p-chloromercuribenzoic acid or N-ethylmaleimide. The adenosine triphosphatase was apparently inactivated or degraded when the plants were grown in the dark for 24 hours prior to incubation. The enzyme was substrate-specific for adenosine triphosphate; no reaction was obtained with adenosine diphosphate, uridine triphosphate, inosine triphosphate, p-nitrophenyl phosphate, and sodium β-glycerophosphate. Sites of nonspecific depositions of lead are described. The adenosine triphosphatase on the chloroplast envelope may be involved in the light-induced contraction of this organelle. Images PMID:4245003

  9. Striatal adenosine signaling regulates EAAT2 and astrocytic AQP4 expression and alcohol drinking in mice.

    Lee, Moonnoh R; Ruby, Christina L; Hinton, David J; Choi, Sun; Adams, Chelsea A; Young Kang, Na; Choi, Doo-Sup

    2013-02-01

    Adenosine signaling is implicated in several neuropsychiatric disorders, including alcoholism. Among its diverse functions in the brain, adenosine regulates glutamate release and has an essential role in ethanol sensitivity and preference. However, the molecular mechanisms underlying adenosine-mediated glutamate signaling in neuroglial interaction remain elusive. We have previously shown that mice lacking the ethanol-sensitive adenosine transporter, type 1 equilibrative nucleoside transporter (ENT1), drink more ethanol compared with wild-type mice and have elevated striatal glutamate levels. In addition, ENT1 inhibition or knockdown reduces glutamate transporter expression in cultured astrocytes. Here, we examined how adenosine signaling in astrocytes contributes to ethanol drinking. Inhibition or deletion of ENT1 reduced the expression of type 2 excitatory amino-acid transporter (EAAT2) and the astrocyte-specific water channel, aquaporin 4 (AQP4). EAAT2 and AQP4 colocalization was also reduced in the striatum of ENT1 null mice. Ceftriaxone, an antibiotic compound known to increase EAAT2 expression and function, elevated not only EAAT2 but also AQP4 expression in the striatum. Furthermore, ceftriaxone reduced ethanol drinking, suggesting that ENT1-mediated downregulation of EAAT2 and AQP4 expression contributes to excessive ethanol consumption in our mouse model. Overall, our findings indicate that adenosine signaling regulates EAAT2 and astrocytic AQP4 expressions, which control ethanol drinking in mice.

  10. Functional proteomics of adenosine triphosphatase system in the rat striatum during aging

    Roberto Federico Villa; Federica Ferrari; Antonella Gorini

    2012-01-01

    The maximum rates of adenosine triphosphatase (ATPase) systems related to energy consumption were systematically evaluated in synaptic plasma membranes isolated from the striata of male Wistar rats aged 2, 6, 12, 18, and 24 months, because of their key role in presynaptic nerve ending homeostasis. The following enzyme activities were evaluated: sodium-potassium-magnesium adenosine triphosphatase (Na+, K+, Mg2+-ATPase); ouabain-insensitive magnesium adenosine triphosphatase (Mg2+-ATPase); sodium-potassium adenosine triphosphatase (Na+, K+-ATPase); direct magnesium adenosine triphosphatase (Mg2+-ATPase); calcium-magnesium adenosine triphosphatase (Ca2+, Mg2+-ATPase); and acetylcholinesterase. The results showed that Na+, K+-ATPase decreased at 18 and 24 months, Ca2+, Mg2+-ATPase and acetylcholinesterase decreased from 6 months, while Mg2+-ATPase was unmodified. Therefore, ATPases vary independently during aging, suggesting that the ATPase enzyme systems are of neuropathological and pharmacological importance. This could be considered as an experimental model to study regeneration processes, because of the age-dependent modifications of specific synaptic plasma membranes. ATPases cause selective changes in some cerebral functions, especially bioenergetic systems. This could be of physiopathological significance, particularly in many central nervous system diseases, where, during regenerative processes, energy availability is essential.

  11. Suppression of adenosine-activated chloride transport by ethanol in airway epithelia.

    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.

  12. Liraglutide, a long-acting GLP-1 mimetic, and its metabolite attenuate inflammation after intracerebral hemorrhage

    Hou, Jack; Manaenko, Anatol; Hakon, Jakob;

    2012-01-01

    receptor (GLP-1R), mechanisms in the brain remain unclear. We investigated the effect of a long-acting GLP-1 analog, liraglutide, and its truncated metabolite, GLP-1(9-36)a from dipeptidyl peptidase-4 (DPP-4) cleavage in ICH-induced brain injury. Primary outcomes were cerebral edema formation......, neurobehavior, and inflammatory parameters. GLP-1(9-36)a, GLP-1R inhibitor, adenosine monophosphate-activated protein kinase (AMPK) phosphorylation inhibitor and DPP-4 inhibitor were administered to examine the mechanisms of action. Liraglutide suppressed neuroinflammation, prevented brain edema and neurologic...

  13. Update on Berberine in Nonalcoholic Fatty Liver Disease

    Yang Liu

    2013-01-01

    Full Text Available Berberine (BBR, an active ingredient from nature plants, has demonstrated multiple biological activities and pharmacological effects in a series of metabolic diseases including nonalcoholic fatty liver disease (NAFLD. The recent literature points out that BBR may be a potential drug for NAFLD in both experimental models and clinical trials. This review highlights important discoveries of BBR in this increasing disease and addresses the relevant targets of BBR on NAFLD which links to insulin pathway, adenosine monophosphate-activated protein kinase (AMPK signaling, gut environment, hepatic lipid transportation, among others. Developing nuanced understanding of the mechanisms will help to optimize more targeted and effective clinical application of BBR for NAFLD.

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

    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.

  15. Adenosine triphosphate-binding cassette member A3 gene mutation in children from one family from Saudi Arabia

    Gawahir Mohamed Ahmed Mukhtar

    2016-01-01

    Full Text Available Mutation in ABCA3, which is adenosine triphosphate-binding cassette member A3, a member of protein transporter family for phospholipids into the lamellar bodies during synthesis of surfactant, can cause lung disease related to surfactant dysfunction with autosomal recessive pattern. We reported three cases from same family with ABCA3 mutation, their gene, clinical course, and outcomes mentioning that one patient had successful lung transplantation, one started the process of the lung transplantation while the third one died during infancy. We concluded that the patients with ABCA3 gene mutations are increasing in numbers may be due to the availability of the genetic testing and high index of suspicion among physicians. Lung transplantation is the definitive treatment, but availability is limited in our region.

  16. Arginine 199 and leucine 208 have key roles in the control of adenosine A2A receptor signalling function.

    Nicolas Bertheleme

    Full Text Available One successful approach to obtaining high-resolution crystal structures of G-protein coupled receptors is the introduction of thermostabilising mutations within the receptor. This technique allows the generation of receptor constructs stabilised into different conformations suitable for structural studies. Previously, we functionally characterised a number of mutants of the adenosine A2A receptor, thermostabilised either in an agonist or antagonist conformation, using a yeast cell growth assay and demonstrated that there is a correlation between thermostability and loss of constitutive activity. Here we report the functional characterisation of 30 mutants intermediate between the Rag23 (agonist conformation mutant and the wild-type receptor using the same yeast signalling assay with the aim of gaining greater insight into the role individual amino acids have in receptor function. The data showed that R199 and L208 have important roles in receptor function; substituting either of these residues for alanine abolishes constitutive activity. In addition, the R199A mutation markedly reduces receptor potency while L208A reduces receptor efficacy. A184L and L272A mutations also reduce constitutive activity and potency although to a lesser extent than the R199A and L208A. In contrast, the F79A mutation increases constitutive activity, potency and efficacy of the receptor. These findings shed new light on the role individual residues have on stability of the receptor and also provide some clues as to the regions of the protein responsible for constitutive activity. Furthermore, the available adenosine A2A receptor structures have allowed us to put our findings into a structural context.

  17. Lipopolysaccharide-induced serotonin transporter up-regulation involves PKG-I and p38MAPK activation partially through A3 adenosine receptor.

    Zhao, Rui; Wang, Shoubao; Huang, Zhonglin; Zhang, Li; Yang, Xiuying; Bai, Xiaoyu; Zhou, Dan; Qin, Zhizhen; Du, Guanhua

    2015-12-01

    Serotonin transporter (SERT) is a critical determinant of synaptic serotonin (5-hydroxytryptamine, 5-HT) inactivation which plays a critical role in the pathology of depression and other mood disorders. Lipopolysaccharide (LPS), a potent activator of the inflammatory system, has been reported to cause depression symptoms by the modulation of SERT in vivo and in vitro. This study is aimed to investigate the underlying mechanism of LPS-induced SERT modulation. The 4-(4-(dimethylamino) styryl)-N-methylpyridinium iodide (ASP) assay was used to detect dynamic 5-HT uptake as read out of SERT activities in RBL-2H3 cells, and cytosol Ca(2+) concentrations ([Ca(2+)]i) and nitric oxide (NO) were examined. Using specific cyclic GMP-dependent protein kinase type I (PKG-I), p38 mitogen-activated protein kinases (p38MAPK) and A3 adenosine receptor (A3AR) inhibitors, SERT expression was evaluated by western blot and immunofluorescence analysis. Results showed that 24 h treatment with LPS stimulated 5-HT transport and up-regulate plasma membrane distribution of SERT in RBL-2H3 cells. LPS treatment increased NO and [Ca(2+)]i, and led to significant increases in levels of phosphorylated calcium/calmodulin-dependent protein kinase type II (CaMK-II), inducible NOS (iNOS) and PKG-I as well as active p38 MAPK. Moreover, PKG-I inhibitor KT5823 or p38MAPK inhibitor SB203580 respectively impaired SERT activation and transposition to plasma membrane by LPS. Notably, A3 adenosine receptor inhibitor MRS1191 also hindered SERT stimulation by LPS. In conclusion, LPS-induced 5-HT uptake and transposition to plasma membrane of SERT in RBL-2H3 cells involves CaMK-II/iNOS/PKG-I and p38 MAPK activation, which may be partially mediated by A3 adenosine receptor activation. This finding provides a novel insight into the interrelationship between LPS and depression.

  18. An adenosine nucleoside analogue NITD008 inhibits EV71 proliferation.

    Shang, Luqing; Wang, Yaxin; Qing, Jie; Shu, Bo; Cao, Lin; Lou, Zhiyong; Gong, Peng; Sun, Yuna; Yin, Zheng

    2014-12-01

    Enterovirus 71 (EV71), one of the major causative agents of Hand-Foot-Mouth Disease (HFMD), causes severe pandemics and hundreds of deaths in the Asia-Pacific region annually and is an enormous public health threat. However, effective therapeutic antiviral drugs against EV71 are rare. Nucleoside analogues have been successfully used in the clinic for the treatment of various viral infections. We evaluated a total of 27 nucleoside analogues and discovered that an adenosine nucleoside analogue NITD008, which has been reported to be an antiviral reagent that specifically inhibits flaviviruses, effectively suppressed the propagation of different strains of EV71 in RD, 293T and Vero cells with a relatively high selectivity index. Triphosphorylated NITD008 (ppp-NITD008) functions as a chain terminator to directly inhibit the RNA-dependent RNA polymerase activity of EV71, and it does not affect the EV71 VPg uridylylation process. A significant synergistic anti-EV71 effect of NITD008 with rupintrivir (AG7088) (a protease inhibitor) was documented, supporting the potential combination therapy of NITD008 with other inhibitors for the treatment of EV71 infections.

  19. Intracellular Adenosine Triphosphate Deprivation through Lanthanide-Doped Nanoparticles.

    Tian, Jing; Zeng, Xiao; Xie, Xiaoji; Han, Sanyang; Liew, Oi-Wah; Chen, Yei-Tsung; Wang, Lianhui; Liu, Xiaogang

    2015-05-27

    Growing interest in lanthanide-doped nanoparticles for biological and medical uses has brought particular attention to their safety concerns. However, the intrinsic toxicity of this new class of optical nanomaterials in biological systems has not been fully evaluated. In this work, we systematically evaluate the long-term cytotoxicity of lanthanide-doped nanoparticles (NaGdF4 and NaYF4) to HeLa cells by monitoring cell viability (mitochondrial activity), adenosine triphosphate (ATP) level, and cell membrane integrity (lactate dehydrogenase release), respectively. Importantly, we find that ligand-free lanthanide-doped nanoparticles induce intracellular ATP deprivation of HeLa cells, resulting in a significant decrease in cell viability after exposure for 7 days. We attribute the particle-induced cell death to two distinct cell death pathways, autophagy and apoptosis, which are primarily mediated via the interaction between the nanoparticle and the phosphate group of cellular ATP. The understanding gained from the investigation of cytotoxicity associated with lanthanide-doped nanoparticles provides keen insights into the safe use of these nanoparticles in biological systems.

  20. In Vitro Functional Study of Rice Adenosine 5'-Phosphosulfate Kinase

    WANG De-zhen; CHEN Guo-guo; LU Lu-jia; JIANG Zhao-jun; RAO Yu-chun; SUN Mei-hao

    2016-01-01

    Sulfate can be activated by ATP sulfurylase and adenosine 5'-phosphosulfate kinase (APSK)in vivo. Recent studies suggested that APSK inArabidopsis thaliana regulated the partition between APS reduction and phosphorylation and its activity can be modulated by cellular redox status. In order to study regulation of APSK in rice (OsAPSK),OsAPSK1 gene was cloned and its activity was analyzed. OsAPSK1 C36 and C69 were found to be the conserved counterparts of C86 and C119, which involved in disulfide formation in AtAPSK.C36A/C69A OsAPSK1 double mutation was made by site directed mutagenesis. OsAPSK1 and its mutant were prokaryotically over-expressed and purified, and then assayed for APS phosphorylation activity. OsAPSK1 activity was depressed by oxidized glutathione, while the activity of its mutantwas not. Further studies in the case that oxidative stress will fluctuatein vivo3'-phosphoadenosine-5'-phosphosulfate content, and all APSK isoenzymes have similar regulation patterns are necessary to be performed.

  1. Cyclic adenosine monophosphate signal pathway in targeted therapy of lymphoma

    DOU Ai-xia; WANG Xin

    2010-01-01

    Objective To review the role of cyclic adenosine monophosphate (cAMP) signal pathway in the pathogenesis oflymphoma and explore a potential lymphoma therapy targeted on this signaling pathway.Data sources The data cited in this review were mainly obtained from the articles listed in Medline and PubMed,published from January 1995 to June 2009. The search terms were "cAMP" and "lymphoma".Study selection Articles regarding the role of the cAMP pathway in apoptosis of lymphoma and associated cells and itspotential role in targeted therapy of lymphoma.Results In the transformation of lymphocytic malignancies, several signal pathways are involved. Among of them, thecAMP pathway has attracted increasing attention because of its apoptosis-inducing role in several lymphoma cells. cAMPpathway impairment is found to influence the prognosis of lymphoma. Targeted therapy to the cAMP pathway seems tobe a new direction for lymphoma treatment, aiming at restoring the cAMP function.Conclusions cAMP signal pathway has different effects on various lymphoma cells. cAMP analogues andphosphodiesterase 4B (PDE4B) inhibitors have potential clinical significance. However, many challenges remain inunderstanding the various roles of such agents.

  2. A tail of two signals: the C terminus of the A(2A)-adenosine receptor recruits alternative signaling pathways.

    Gsandtner, Ingrid; Freissmuth, Michael

    2006-08-01

    G protein-coupled receptors are endowed with carboxyl termini that vary greatly in length and sequence. In most instances, the distal portion of the C terminus is dispensable for G protein coupling. This is also true for the A(2A)-adenosine receptor, where the last 100 amino acids are of very modest relevance to G(s) coupling. The C terminus was originally viewed mainly as the docking site for regulatory proteins of the beta-arrestin family. These beta-arrestins bind to residues that have been phosphorylated by specialized kinases (G protein-coupled receptor kinases) and thereby initiate receptor desensitization and endocytosis. More recently, it has become clear that many additional "accessory" proteins bind to C termini of G protein-coupled receptors. The article by Sun et al. in the current issue of Molecular Pharmacology identifies translin-associated protein-X as yet another interaction partner of the A(2A) receptor; translin-associated protein allows the A(2A) receptor to impinge on the signaling mechanisms by which p53 regulates neuronal differentiation, but the underlying signaling pathways are uncharted territory. With a list of five known interaction partners, the C terminus of the A(2A) receptor becomes a crowded place. Hence, there must be rules that regulate the interaction. This allows the C terminus to act as coincidence detector and as signal integrator. Despite our ignorance about the precise mechanisms, the article has exciting implications: the gene encoding for translin-associated protein-X maps to a locus implicated in some forms of schizophrenia; A(2A) receptor agonists are candidate drugs for the treatment of schizophrenic symptoms. It is of obvious interest to explore a possible link.

  3. The role of renal adenosine 3',5'-monophosphate in the control of erythropoietin production.

    Rodgers, G M; Fisher, J W; George, W J

    1975-01-01

    A regulatory role for adenosine 3',5'-monophosphate (cyclic AMP) in the production of the renal hormone rythropoietin following erythropoietic stimulation with cobaltous chloride hexahydrate is proposed. Studies in rates reveal a temporal relationship between renal cyclic AMP levels and plasma titers of erythropoietin. In addition, cobalt increases the activity of an erythropoietin-generating enzyme (renal erythropoietic factor) with maximal enzyme activity occurring after the rise in cyclic AMP levels but before the increase in erythropoietin titers. This increase in renal cyclic AMP is localized to the renal cortex. Cobalt stimulates renal cortical adenylate cyclase but has no effect on renal cyclic nucleotide phosphodiesterase. The addition of cyclic AMP (3 time 10-6 M) and a partially purified cyclic AMP-dependent protein kinase from rat kidney to an inactive preparation of renal erythropoietic factor increases the ability of renal erythropoietic factor to generate erythropoietin. Data from the polycythemic mouse assay, a bioassay used to quantitate erythropoietic activity of test substances, indicate that dibutyryl cyclic AMP is erythropoietically active with respect to its ability to increase radioactive-labelled iron (59Fe) incorporation into heme of newly formed red blood cells. Theophylline, which by itself is erythropoietically inactive, potentiated the erythropoietic effect of cobalt in polycythemic mice. These results suggest that cyclic AMP plays a significant role in the renal production of erythropoietin following cobalt administration. It is postulated that cobalt stimulates renal cortical adenyoate cyclase, thus increasing renal cyclic AMP levels. Cyclic AMP then activates a protein kinase which subsequently stimulates renal erythropoietic factor to generate erythropoietin. A similar cyclic AMP mechanism may be operative after erythropoietic stimulation by exposure to hypoxia or prostaglandin treatment.

  4. Inhibition of Salmonella enterica biofilm formation using small-molecule adenosine mimetics.

    Koopman, Jacob A; Marshall, Joanna M; Bhatiya, Aditi; Eguale, Tadesse; Kwiek, Jesse J; Gunn, John S

    2015-01-01

    Biofilms have been widely implicated in chronic infections and environmental persistence of Salmonella enterica, facilitating enhanced colonization of surfaces and increasing the ability of the bacteria to be transmitted to new hosts. Salmonella enterica serovar Typhi biofilm formation on gallstones from humans and mice enhances gallbladder colonization and bacterial shedding, while Salmonella enterica serovar Typhimurium biofilms facilitate long-term persistence in a number of environments important to food, medical, and farming industries. Salmonella regulates expression of many virulence- and biofilm-related processes using kinase-driven pathways. Kinases play pivotal roles in phosphorylation and energy transfer in cellular processes and possess an ATP-binding pocket required for their functions. Many other cellular proteins also require ATP for their activity. Here we test the hypothesis that pharmacological interference with ATP-requiring enzymes utilizing adenosine mimetic compounds would decrease or inhibit bacterial biofilm formation. Through the screening of a 3,000-member ATP mimetic library, we identified a single compound (compound 7955004) capable of significantly reducing biofilm formation by S. Typhimurium and S. Typhi. The compound was not bactericidal or bacteriostatic toward S. Typhimurium or cytotoxic to mammalian cells. An ATP-Sepharose affinity matrix technique was used to discover potential protein-binding targets of the compound and identified GroEL and DeoD. Compound 7955004 was screened against other known biofilm-forming bacterial species and was found to potently inhibit biofilms of Acinetobacter baumannii as well. The identification of a lead compound with biofilm-inhibiting capabilities toward Salmonella provides a potential new avenue of therapeutic intervention against Salmonella biofilm formation, with applicability to biofilms of other bacterial pathogens.

  5. Feasibility and safety of high-dose adenosine perfusion cardiovascular magnetic resonance

    Holloway Cameron J

    2010-11-01

    Full Text Available Abstract Introduction Adenosine is the most widely used vasodilator stress agent for Cardiovascular Magnetic Resonance (CMR perfusion studies. With the standard dose of 140 mcg/kg/min some patients fail to demonstrate characteristic haemodynamic changes: a significant increase in heart rate (HR and mild decrease in systolic blood pressure (SBP. Whether an increase in the rate of adenosine infusion would improve peripheral and, likely, coronary vasodilatation in those patients is unknown. The aim of the present study was to assess the tolerance and safety of a high-dose adenosine protocol in patients with inadequate haemodynamic response to the standard adenosine protocol when undergoing CMR perfusion imaging. Methods 98 consecutive patients with known or suspected coronary artery disease (CAD underwent CMR perfusion imaging at 1.5 Tesla. Subjects were screened for contraindications to adenosine, and an electrocardiogram was performed prior to the scan. All patients initially received the standard adenosine protocol (140 mcg/kg/min for at least 3 minutes. If the haemodynamic response was inadequate (HR increase Results All patients successfully completed the CMR scan. Of a total of 98 patients, 18 (18% did not demonstrate evidence of a significant increase in HR or decrease in SBP under the standard adenosine infusion rate. Following the increase in the rate of infusion, 16 out of those 18 patients showed an adequate haemodynamic response. One patient of the standard infusion group and two patients of the high-dose group developed transient advanced AV block. Significantly more patients complained of chest pain in the high-dose group (61% vs. 29%, p = 0.009. On multivariate analysis, age > 65 years and ejection fraction Conclusions A substantial number of patients do not show adequate peripheral haemodynamic response to standard-dose adenosine stress during perfusion CMR imaging. Age and reduced ejection fraction are predictors of inadequate

  6. Adenosine Deaminase Inhibition Prevents Clostridium difficile Toxin A-Induced Enteritis in Mice ▿

    de Araújo Junqueira, Ana Flávia Torquato; Dias, Adriana Abalen Martins; Vale, Mariana Lima; Spilborghs, Graziela Machado Gruner Turco; Bossa, Aline Siqueira; Lima, Bruno Bezerra; Carvalho, Alex Fiorini; Guerrant, Richard Littleton; Ribeiro, Ronaldo Albuquerque; Brito, Gerly Anne

    2011-01-01

    Toxin A (TxA) is able to induce most of the classical features of Clostridium difficile-associated disease in animal models. The objective of this study was to determine the effect of an inhibitor of adenosine deaminase, EHNA [erythro-9-(2-hydroxy-3-nonyl)-adenine], on TxA-induced enteritis in C57BL6 mice and on the gene expression of adenosine receptors. EHNA (90 μmol/kg) or phosphate-buffered saline (PBS) was injected intraperitoneally (i.p.) 30 min prior to TxA (50 μg) or PBS injection into the ileal loop. A2A adenosine receptor agonist (ATL313; 5 nM) was injected in the ileal loop immediately before TxA (50 μg) in mice pretreated with EHNA. The animals were euthanized 3 h later. The changes in the tissue were assessed by the evaluation of ileal loop weight/length and secretion volume/length ratios, histological analysis, myeloperoxidase assay (MPO), the local expression of inducible nitric oxide synthase (NOS2), pentraxin 3 (PTX3), NF-κB, tumor necrosis factor alpha (TNF-α), and interleukin-1β (IL-1β) by immunohistochemistry and/or quantitative reverse transcription-PCR (qRT-PCR). The gene expression profiles of A1, A2A, A2B, and A3 adenosine receptors also were evaluated by qRT-PCR. Adenosine deaminase inhibition, by EHNA, reduced tissue injury, neutrophil infiltration, and the levels of proinflammatory cytokines (TNF-α and IL-1β) as well as the expression of NOS2, NF-κB, and PTX3 in the ileum of mice injected with TxA. ATL313 had no additional effect on EHNA action. TxA increased the gene expression of A1 and A2A adenosine receptors. Our findings show that the inhibition of adenosine deaminase by EHNA can prevent Clostridium difficile TxA-induced damage and inflammation possibly through the A2A adenosine receptor, suggesting that the modulation of adenosine/adenosine deaminase represents an important tool in the management of C. difficile-induced disease. PMID:21115723

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

    Rikard Dammen

    Full Text Available OBJECTIVE: 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. DESIGN: 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. RESULTS: 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. CONCLUSION: 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

  8. Adenosine elicits an eNOS-independent reduction in arterial blood pressure in conscious mice that involves adenosine A(2A) receptors

    Andersen, Henrik; Jaff, Mohammad G; Høgh, Ditte;

    2011-01-01

    Aims:  Adenosine plays an important role in the regulation of heart rate and vascular reactivity. However, the mechanisms underlying the acute effect of adenosine on arterial blood pressure in conscious mice are unclear. Therefore, the present study investigated the effect of the nucleoside on mean...... arterial blood pressure (MAP) and heart rate (HR) in conscious mice. Methods:  Chronic indwelling catheters were placed in C57Bl/6J (WT) and endothelial nitric oxide synthase knock-out (eNOS(-/-) ) mice for continuous measurements of MAP and HR. Using PCR and myograph analysis involment of adenosine...... receptors was investigated in human and mouse renal blood vessels Results:  Bolus infusion of 0.5 mg/kg adenosine elicited significant transient decreases in MAP (99.3±2.3 to 70.4±4.5 mmHg) and HR (603.2±18.3 to 364.3±49.2 min(-1) ) which were inhibited by the A(2A) receptor antagonist ZM 241385. Activation...

  9. Sleep-wake sensitive mechanisms of adenosine release in the basal forebrain of rodents: an in vitro study.

    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.

  10. Exercise-induced increase in interstitial bradykinin and adenosine concentrations in skeletal muscle and peritendinous tissue in humans

    Langberg, H; Bjørn, C; Boushel, Robert Christopher

    2002-01-01

    increased both in muscle (from 0.48 +/- 0.07 micromol l(-1) to 1.59 +/- 0.35 micromol l(-1); P muscular activity increases the interstitial concentrations...... of bradykinin and adenosine in both skeletal muscle and the connective tissue around its adjacent tendon. These findings support a role for bradykinin and adenosine in exercise-induced hyperaemia in skeletal muscle and suggest that bradykinin and adenosine are potential regulators of blood flow in peritendinous...

  11. In vivo adenosine A(2B) receptor desensitization in guinea-pig airway smooth muscle: implications for asthma.

    Breschi, Maria Cristina; Blandizzi, Corrado; Fogli, Stefano; Martinelli, Cinzia; Adinolfi, Barbara; Calderone, Vincenzo; Camici, Marcella; Martinotti, Enrica; Nieri, Paola

    2007-12-01

    This study was aimed at characterizing the role of adenosine receptor subtypes in the contractility modulation of guinea-pig airway smooth muscle in normal and pathological settings. In vitro and in vivo experiments were performed by testing selective agonists and antagonists on isolated tracheal smooth muscle preparations and pulmonary inflation pressure, respectively, under normal conditions or following ovalbumin-induced allergic sensitization. In normal and sensitized animals, the adenosine A(2A)/A(2B) receptor agonist, NECA, evoked relaxing responses of isolated tracheal preparations precontracted with histamine, and such an effect was reversed by the adenosine A(2B) antagonist, MRS 1706, in the presence or in the absence of epithelium. The expression of mRNA coding for adenosine A(2B) receptors was demonstrated in tracheal specimens. In vitro desensitization with 100 microM NECA markedly reduced the relaxing effect of the agonist. In vivo NECA or adenosine administration to normal animals inhibited histamine-mediated bronchoconstriction, while these inhibitory effects no longer occurred in sensitized guinea-pigs. Adenosine plasma levels were significantly higher in sensitized than normal animals. In conclusion, our data demonstrate that: (i) adenosine A(2B) receptors are responsible for the relaxing effects of adenosine on guinea-pig airways; (ii) these receptors can undergo rapid adaptive changes that may affect airway smooth muscle responsiveness to adenosine; (iii) ovalbumin-induced sensitization promotes a reversible inactivation of adenosine A(2B) receptors which can be ascribed to homologous desensitization. These findings can be relevant to better understand adenosine functions in airways as well as mechanisms of action of asthma therapies targeting the adenosine system.

  12. Bradykinin and adenosine receptors mediate desflurane induced postconditioning in human myocardium: role of reactive oxygen species

    Gérard Jean-Louis

    2010-07-01

    Full Text Available Abstract Background Desflurane during early reperfusion has been shown to postcondition human myocardium, in vitro. We investigated the role of adenosine and bradykinin receptors, and generation of radical oxygen species in desflurane-induced postconditioning in human myocardium. Methods We recorded isometric contraction of human right atrial trabeculae hanged in an oxygenated Tyrode's solution (34 degrees Celsius, stimulation frequency 1 Hz. After a 30-min hypoxic period, desflurane 6% was administered during the first 5 min of reoxygenation. Desflurane was administered alone or with pretreatment of N-mercaptopropionylglycine, a reactive oxygen species scavenger, 8-(p-Sulfophenyltheophylline, an adenosine receptor antagonist, HOE140, a selective B2 bradykinin receptor antagonist. In separate groups, adenosine and bradykinin were administered during the first minutes of reoxygenation alone or in presence of N-mercaptopropionylglycine. The force of contraction of trabeculae was recorded continuously. Developed force at the end of a 60-min reoxygenation period was compared (mean ± standard deviation between the groups by a variance analysis and post hoc test. Results Desflurane 6% (84 ± 6% of baseline enhanced the recovery of force after 60-min of reoxygenation as compared to control group (51 ± 8% of baseline, P N-mercaptopropionylglycine (54 ± 3% of baseline, 8-(p-Sulfophenyltheophylline (62 ± 9% of baseline, HOE140 (58 ± 6% of baseline abolished desflurane-induced postconditioning. Adenosine (80 ± 9% of baseline and bradykinin (83 ± 4% of baseline induced postconditioning (P vs control, N-mercaptopropionylglycine abolished the beneficial effects of adenosine and bradykinin (54 ± 8 and 58 ± 5% of baseline, respectively. Conclusions In vitro, desflurane-induced postconditioning depends on reactive oxygen species production, activation of adenosine and bradykinin B2 receptors. And, the cardioprotective effect of adenosine and bradykinin

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

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

    2012-01-01

    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. Ameliorative effect of adenosine on hypoxia-reoxygenation injury in LLC-PK1, a porcine kidney cell line.

    Yonehana, T; Gemba, M

    1999-06-01

    We studied the effects of adenosine on injury caused by hypoxia and reoxygenation in LLC-PK1 cells. Lactate dehydrogenase and gamma-glutamyltranspeptidase were released from cells exposed to hypoxia for 6 hr and then reoxygenation for 1 hr. The addition of adenosine at 100 microM to the medium before hypoxia began significantly decreased enzyme leakage into medium during both hypoxia and reoxygenation. The adenosine A1-receptor agonist, R(-)-N6-(2-phenylisopropyl)adenosine (R-PIA), at the concentration of 100 microM, did not affect enzyme release, but the adenosine A2-receptor agonist 2-p-[2-car-boxyethyl]phenethyl-amino-5'-N-ethylcarboxamido-adenosi ne hydrochloride (CGS 21680) at the concentration of 100 nM, suppressed the injury caused by hypoxia and reoxygenation. There were decreases in cAMP contents and ATP levels in LLC-PK1 cells injured by hypoxia and reoxygenation. Adenosine (100 microM) restored ATP levels in the cells during reoxygenation. With adenosine, the intracellular cAMP level was increased prominently during reoxygenation. These results suggest that adenosine protects LLC-PK1 cells from injury caused by hypoxia and reoxygenation by increasing the intracellular cAMP level via adenosine A2 receptor.

  15. Adenosine A(2A receptor up-regulates retinal wave frequency via starburst amacrine cells in the developing rat retina.

    Pin-Chien Huang

    Full Text Available BACKGROUND: Developing retinas display retinal waves, the patterned spontaneous activity essential for circuit refinement. During the first postnatal week in rodents, retinal waves are mediated by synaptic transmission between starburst amacrine cells (SACs and retinal ganglion cells (RGCs. The neuromodulator adenosine is essential for the generation of retinal waves. However, the cellular basis underlying adenosine's regulation of retinal waves remains elusive. Here, we investigated whether and how the adenosine A(2A receptor (A(2AR regulates retinal waves and whether A(2AR regulation of retinal waves acts via presynaptic SACs. METHODOLOGY/PRINCIPAL FINDINGS: We showed that A(2AR was expressed in the inner plexiform layer and ganglion cell layer of the developing rat retina. Knockdown of A(2AR decreased the frequency of spontaneous Ca²⁺ transients, suggesting that endogenous A(2AR may up-regulate wave frequency. To investigate whether A(2AR acts via presynaptic SACs, we targeted gene expression to SACs by the metabotropic glutamate receptor type II promoter. Ca²⁺ transient frequency was increased by expressing wild-type A(2AR (A2AR-WT in SACs, suggesting that A(2AR may up-regulate retinal waves via presynaptic SACs. Subsequent patch-clamp recordings on RGCs revealed that presynaptic A(2AR-WT increased the frequency of wave-associated postsynaptic currents (PSCs or depolarizations compared to the control, without changing the RGC's excitability, membrane potentials, or PSC charge. These findings suggest that presynaptic A(2AR may not affect the membrane properties of postsynaptic RGCs. In contrast, by expressing the C-terminal truncated A(2AR mutant (A(2AR-ΔC in SACs, the wave frequency was reduced compared to the A(2AR-WT, but was similar to the control, suggesting that the full-length A(2AR in SACs is required for A(2AR up-regulation of retinal waves. CONCLUSIONS/SIGNIFICANCE: A(2AR up-regulates the frequency of retinal waves via

  16. Equilibrium and kinetic selectivity profiling on the human adenosine receptors.

    Guo, Dong; Dijksteel, Gabrielle S; van Duijl, Tirsa; Heezen, Maxime; Heitman, Laura H; IJzerman, Adriaan P

    2016-04-01

    Classical evaluation of target selectivity is usually undertaken by measuring the binding affinity of lead compounds against a number of potential targets under equilibrium conditions, without considering the kinetics of the ligand-receptor interaction. In the present study we propose a combined strategy including both equilibrium- and kinetics-based selectivity profiling. The adenosine receptor (AR) was chosen as a prototypical drug target. Six in-house AR antagonists were evaluated in a radioligand displacement assay for their affinity and in a competition association assay for their binding kinetics on three AR subtypes. One of the compounds with a promising kinetic selectivity profile was also examined in a [(35)S]-GTPγS binding assay for functional activity. We found that XAC and LUF5964 were kinetically more selective for the A1R and A3R, respectively, although they are non-selective in terms of their affinity. In comparison, LUF5967 displayed a strong equilibrium-based selectivity for the A1R over the A2AR, yet its kinetic selectivity thereon was less pronounced. In a GTPγS assay, LUF5964 exhibited insurmountable antagonism on the A3R while having a surmountable effect on the A1R, consistent with its kinetic selectivity profile. This study provides evidence that equilibrium and kinetic selectivity profiling can both be important in the early phases of the drug discovery process. Our proposed combinational strategy could be considered for future medicinal chemistry efforts and aid the design and discovery of different or even better leads for clinical applications.

  17. Behavior and stability of adenosine triphosphate (ATP) during chlorine disinfection.

    Nescerecka, Alina; Juhna, Talis; Hammes, Frederik

    2016-09-15

    Adenosine triphosphate (ATP) analysis is a cultivation-independent alternative method for the determination of bacterial viability in both chlorinated and non-chlorinated water. Here we investigated the behavior and stability of ATP during chlorination in detail. Different sodium hypochlorite doses (0-22.4 mg-Cl2 L(-1); 5 min exposure) were applied to an Escherichia coli pure culture suspended in filtered river water. We observed decreasing intracellular ATP with increasing chlorine concentrations, but extracellular ATP concentrations only increased when the chlorine dose exceeded 0.35 mg L(-1). The release of ATP from chlorine-damaged bacteria coincided with severe membrane damage detected with flow cytometry (FCM). The stability of extracellular ATP was subsequently studied in different water matrixes, and we found that extracellular ATP was stable in sterile deionized water and also in chlorinated water until extremely high chlorine doses (≤11.2 mg-Cl2 L(-1); 5 min exposure). In contrast, ATP decreased relatively slowly (k = 0.145 h(-1)) in 0.1 μm filtered river water, presumably due to degradation by either extracellular enzymes or the fraction of bacteria that were able to pass through the filter. Extracellular ATP decreased considerably faster (k = 0.368 h(-1)) during batch growth of a river water bacterial community. A series of growth potential tests showed that extracellular ATP molecules were utilized as a phosphorus source during bacteria proliferation. From the combined data we conclude that ATP released from bacteria at high chlorine doses could promote bacteria regrowth, contributing to biological instability in drinking water distribution systems.

  18. Opiorphin-dependent up-regulation of CD73 (a key enzyme in the adenosine signaling pathway) in corporal smooth muscle cells exposed to hypoxic conditions and in corporal tissue in pre-priapic sickle cell mice

    Fu, Shibo; Davies, Kelvin P.

    2015-01-01

    The precise molecular mechanisms underlying priapism associated with sickle cell disease remain to be defined. However, there is increasing evidence that up-regulated activity of the opiorphin and adenosine pathways in corporal tissue, resulting in heighted relaxation of smooth muscle, play an important role in development of priapism. A key enzyme in the adenosine pathway is CD73, an ecto-5-prime-nucleotidase (5-prime-ribonucleotide phosphohydrolase; EC 3.1.3.5) which catalyzes the conversion of adenosine mononucleotides to adenosine. In the present study we investigated how sickle cell disease and hypoxia regulate the interplay between opiorphin and CD73. In the corpora of sickle cell mice we observed significantly elevated expression of both the mouse opiorphin homologue mSmr3a (14-fold) and CD73 (2.2-fold) relative to non-sickle cell controls at a life-stage prior to the exhibition of priapism. Sickle cell disease has a pronounced hypoxic component, therefore we determined if CD73 was also modulated in in vitro corporal smooth muscle (CSM) models of hypoxia. Hypoxia significantly increased CD73 protein and mRNA expression by 1.5-fold and 2-fold, respectively. We previously demonstrated that expression of another component of the adenosine signaling pathway, the adensosine 2B receptor, can be regulated by sialorphin (the rat opiorphin homolologue), and we demonstrate that sialorphin also regulates CD73 expression in a dose and time dependent fashion. Using siRNA to knock-down sialorphin mRNA expression in CSM cells in vitro, we demonstrate that the hypoxic up-regulation of CD73 is dependent on the up-regulation of sialorphin. Overall our data provides further evidence to support a role for opiorphin in CSM in regulating the cellular response regulating response to hypoxia or sickle cell disease by activating smooth muscle relaxant pathways. PMID:25833166

  19. Aberrant bone density in aging mice lacking the adenosine transporter ENT1.

    David J Hinton

    Full Text Available Adenosine is known to regulate bone production and resorption in humans and mice. Type 1 equilibrative nucleoside transporter (ENT1 is responsible for the majority of adenosine transport across the plasma membrane and is ubiquitously expressed in both humans and mice. However, the contribution of ENT1-mediated adenosine levels has not been studied in bone remodeling. With the recent identification of the importance of adenosine signaling in bone homeostasis, it is essential to understand the role of ENT1 to develop novel therapeutic compounds for bone disorders. Here we examined the effect of ENT1 deletion on bone density using X-ray, dual energy X-ray absorptiometry and micro-computerized tomography analysis. Our results show that bone density and bone mineral density is reduced in the lower thoracic and lumbar spine as well as the femur of old ENT1 null mice (>7 months compared to wild-type littermates. Furthermore, we found increased mRNA expression of tartrate-resistant acid phosphatase (TRAP, an osteoclast marker, in isolated long bones from 10 month old ENT1 null mice compared to wild-type mice. In addition, aged ENT1 null mice displayed severe deficit in motor coordination and locomotor activity, which might be attributed to dysregulated bone density. Overall, our study suggests that ENT1-regulated adenosine signaling plays an essential role in lumbar spine and femur bone density.

  20. Pulmonary Vascular Capacitance as a Predictor of Vasoreactivity in Idiopathic Pulmonary Arterial Hypertension Tested by Adenosine

    Shafie

    2015-09-01

    Full Text Available Background Acute pulmonary vasoreactivity testing has been recommended in the diagnostic work-up of patients with idiopathic pulmonary arterial hypertension (IPAH. Pulmonary arteriolar capacitance (Cp approximated by stroke volume divided by pulmonary pulse pressure (SV/PP is considered as an independent predictor of mortality in patients with IPAH. Objectives We sought to evaluate any differences in baseline and adenosine Cp between vasoreactive and non-vasoreactive IPAH patients tested with adenosine. Patients and Methods Fourteen patients with IPAH and a vasoreactive adenosine vasoreactivity testing according to the ESC guidelines were compared with 24 IPAH patients with nonreactive adenosine test results. Results There were no statistical significant differences between the two groups regarding NYHA class, body surface area, heart rate, and systemic blood pressure during right heart catheterization. Hemodynamic study showed no statistical significant differences in cardiac output/Index, mean pulmonary artery pressure, pulmonary vascular resistance, and baseline Cp between the two groups. There was a statistical significant but weak increase in adenosine Cp in vasoreactive group compared to non-reactive group (P = 0.04. Multivariable analysis showed an association between Cp and vasoreactivity (Beta = 2, P = 0.04, OR = 0.05 (95%CI = 0.003 - 0.9. Conclusions Cp could be considered as an index for the prediction of vasoreactivity in patients with IPAH. Prediction of long-term response to calcium channel blockers in patients with IPAH and a positive vasoreactive test by this index should be addressed in further studies.

  1. Squalenoyl adenosine nanoparticles provide neuroprotection after stroke and spinal cord injury

    Gaudin, Alice; Yemisci, Müge; Eroglu, Hakan; Lepetre-Mouelhi, Sinda; Turkoglu, Omer Faruk; Dönmez-Demir, Buket; Caban, Seçil; Sargon, Mustafa Fevzi; Garcia-Argote, Sébastien; Pieters, Grégory; Loreau, Olivier; Rousseau, Bernard; Tagit, Oya; Hildebrandt, Niko; Le Dantec, Yannick; Mougin, Julie; Valetti, Sabrina; Chacun, Hélène; Nicolas, Valérie; Desmaële, Didier; Andrieux, Karine; Capan, Yilmaz; Dalkara, Turgay; Couvreur, Patrick

    2014-12-01

    There is an urgent need to develop new therapeutic approaches for the treatment of severe neurological trauma, such as stroke and spinal cord injuries. However, many drugs with potential neuropharmacological activity, such as adenosine, are inefficient upon systemic administration because of their fast metabolization and rapid clearance from the bloodstream. Here, we show that conjugation of adenosine to the lipid squalene and the subsequent formation of nanoassemblies allows prolonged circulation of this nucleoside, providing neuroprotection in mouse stroke and rat spinal cord injury models. The animals receiving systemic administration of squalenoyl adenosine nanoassemblies showed a significant improvement of their neurologic deficit score in the case of cerebral ischaemia, and an early motor recovery of the hindlimbs in the case of spinal cord injury. Moreover, in vitro and in vivo studies demonstrated that the nanoassemblies were able to extend adenosine circulation and its interaction with the neurovascular unit. This Article shows, for the first time, that a hydrophilic and rapidly metabolized molecule such as adenosine may become pharmacologically efficient owing to a single conjugation with the lipid squalene.

  2. Circadian variations of adenosine level in blood and liver and its possible physiological significance.

    Chagoya de Sánchez, V; Hernández-Muñoz, R; Díaz-Muñoz, M; Villalobos, R; Glender, W; Vidrio, S; Suárez, J; Yañez, L

    1983-09-12

    The role of adenosine as a possible physiological modulator was explored by measuring its concentration in different tissues during a 24-hour period. Initially the circadian variations of adenosine and other purine compounds such as inosine, hypoxanthine, uric acid and adenine nucleotides were studied in the rat blood. A daily cyclic response was observed, with low levels of adenosine from 08.00 - 20.00 h, followed by an increase from this time on. Inosine and hypoxanthine levels were elevated during the day and low at night. The uric acid changes observed indicate that the decrease in purine catabolism coincides with a decrease in inosine and hypoxanthine levels and an increase in adenosine. The blood adenine nucleotides, energy charge and phosphorylation potential remained constant during the day and showed oscillatory changes during the night. Similar studies were made in the liver, a primary source of circulating purines. Liver adenosine was high during the night while inosine and hypoxanthine remained low along the 24 hours. The results suggest that liver purine metabolism might participate in the maintenance and renewal of the blood purine pool and in the energy state of erythrocytes in vivo.

  3. Role of nitric oxide and adenosine in the onset of vasodilation during dynamic forearm exercise.

    Casey, Darren P; Mohamed, Essa A; Joyner, Michael J

    2013-02-01

    We tested the hypothesis that nitric oxide (NO) and adenosine contribute to the onset of vasodilation during dynamic forearm exercise. Twenty-two subjects performed rhythmic forearm exercise (20 % of maximum) during control and NO synthase (NOS) inhibition (N (G)-monomethyl-L-arginine; L-NMMA) trials. A subset of subjects performed a third trial of forearm exercise during combined inhibition of NOS and adenosine (aminophylline; n = 9). Additionally, a separate group of subjects (n = 7) performed rhythmic forearm exercise during control, inhibition of adenosine alone and combined inhibition of adenosine and NOS. Forearm vascular conductance (FVC; ml min(-1) · 100 mmHg(-1)) was calculated from blood flow and mean arterial pressure (mmHg). The onset of vasodilation was assessed by calculating the slope of the FVC response for every duty cycle between baseline and steady state, and the number of duty cycles (1-s contraction/2-s relaxation) to reach steady state. NOS inhibition blunted vasodilation at the onset of exercise (11.1 ± 0.8 vs. 8.5 ± 0.6 FVC units/duty cycle; P Vasodilation was blunted further with combined inhibition of NOS and adenosine (7.5 ± 0.6 vs. 6.2 ± 0.8 FVC units/duty cycle; P vasodilation during dynamic forearm exercise.

  4. Predictors and Diagnostic Significance of the Adenosine Related Side Effects on Myocardial Perfusion SPECT/CT Imaging

    Nilüfer Yıldırım Poyraz

    2014-10-01

    Full Text Available Objective: The aim of this study was to investigate the relationship between patient characteristics and adenosine-related side-effects during stress myocard perfusion imaging (MPI. The effect of presence of adenosine-related side-effects on the diagnostic value of MPI with integrated SPECT/CT system for coronary artery disease (CAD, was also assessed in this study. Methods: Total of 281 patients (109 M, 172 F; mean age:62.6±10 who underwent standard adenosine stress protocol for MPI, were included in this study. All symptoms during adenosine infusion were scored according to the severity and duration. For the estimation of diagnostic value of adenosine MPI with integrated SPECT/CT system, coronary angiography (CAG or clinical follow-up were used as gold standard. Results: Total of 173 patients (61.6% experienced adenosine-related side-effects (group 1; flushing, dyspnea, and chest pain were the most common. Other 108 patients completed pharmacologic stress (PS test without any side-effects (group 2. Test tolerability were similar in the patients with cardiovascular or airway disease to others, however dyspnea were observed significantly more common in patients with mild airway disease. Body mass index (BMI ≥30 kg/m2 and age ≤45 years were independent predictors of side-effects. The diagnostic value of MPI was similar in both groups. Sensitivity of adenosine MPI SPECT/CT was calculated to be 86%, specificity was 94% and diagnostic accuracy was 92% for diagnosis of CAD. Conclusion: Adenosine MPI is a feasible and well tolerated method in patients who are not suitable for exercise stress test as well as patients with cardiopulmonary disease. However age ≤45 years and BMI ≥30 kg/m2 are the positive predictors of adenosine-related side-effects, the diagnostic value of adenosine MPI SPECT/CT is not affected by the presence of adenosine related side-effects.

  5. Regulation of insulin-like growth factor I transcription by cyclic adenosine 3',5'-monophosphate (cAMP) in fetal rat bone cells through an element within exon 1: protein kinase A-dependent control without a consensus AMP response element

    McCarthy, T. L.; Thomas, M. J.; Centrella, M.; Rotwein, P.

    1995-01-01

    Insulin-like growth factor I (IGF-I) is a locally synthesized anabolic growth factor for bone. IGF-I synthesis by primary fetal rat osteoblasts (Ob) is stimulated by agents that increase the intracellular cAMP concentration, including prostaglandin E2 (PGE2). Previous studies with Ob cultures demonstrated that PGE2 enhanced IGF-I transcription through selective use of IGF-I promoter 1, with little effect on IGF-I messenger RNA half-life. Transient transfection of Ob cultures with an array of promoter 1-luciferase reporter fusion constructs has now allowed localization of a potential cis-acting promoter element(s) responsible for cAMP-stimulated gene expression to the 5'-untranslated region (5'-UTR) of IGF-I exon 1, within a segment lacking a consensus cAMP response element. Our evidence derives from three principal observations: 1) a transfection construct containing only 122 nucleotides (nt) of promoter 1 and 328 nt of the 5'-UTR retained full PGE2-stimulated reporter expression; 2) maximal PGE2-driven reporter expression required the presence of nt 196 to 328 of exon 1 when tested within the context of IGF-I promoter 1; 3) cotransfection of IGF-I promoter-luciferase-reporter constructs with a plasmid encoding the alpha-isoform of the catalytic subunit of murine cAMP-dependent protein kinase (PKA) produced results comparable to those seen with PGE2 treatment, whereas cotransfection with a plasmid encoding a mutant regulatory subunit of PKA that cannot bind cAMP blocked PGE2-induced reporter expression. Deoxyribonuclease I footprinting of the 5'-UTR of exon 1 demonstrated protected sequences at HS3A, HS3B, and HS3D, three of six DNA-protein binding sites previously characterized with rat liver nuclear extracts. Of these three regions, only the HS3D binding site is located within the functionally identified hormonally responsive segment of IGF-I exon 1. These results directly implicate PKA in the control of IGF-I gene transcription by PGE2 and identify a segment of

  6. Membrane omega-3 fatty acids modulate the oligomerisation kinetics of adenosine A2A and dopamine D2 receptors

    Guixà-González, Ramon; Javanainen, Matti; Gómez-Soler, Maricel; Cordobilla, Begoña; Domingo, Joan Carles; Sanz, Ferran; Pastor, Manuel; Ciruela, Francisco; Martinez-Seara, Hector; Selent, Jana

    2016-01-01

    Membrane levels of docosahexaenoic acid (DHA), an essential omega-3 polyunsaturated fatty acid (ω-3 PUFA), are decreased in common neuropsychiatric disorders. DHA modulates key cell membrane properties like fluidity, thereby affecting the behaviour of transmembrane proteins like G protein-coupled receptors (GPCRs). These receptors, which have special relevance for major neuropsychiatric disorders have recently been shown to form dimers or higher order oligomers, and evidence suggests that DHA levels affect GPCR function by modulating oligomerisation. In this study, we assessed the effect of membrane DHA content on the formation of a class of protein complexes with particular relevance for brain disease: adenosine A2A and dopamine D2 receptor oligomers. Using extensive multiscale computer modelling, we find a marked propensity of DHA for interaction with both A2A and D2 receptors, which leads to an increased rate of receptor oligomerisation. Bioluminescence resonance energy transfer (BRET) experiments performed on living cells suggest that this DHA effect on the oligomerisation of A2A and D2 receptors is purely kinetic. This work reveals for the first time that membrane ω-3 PUFAs play a key role in GPCR oligomerisation kinetics, which may have important implications for neuropsychiatric conditions like schizophrenia or Parkinson’s disease.

  7. Downregulation of adenosine and P2X receptor-mediated cardiovascular responses in heart failure rats

    Zhao, Xin; Sun, X Y; Erlinge, D;

    2000-01-01

    Neurohormonal changes in congestive heart failure (CHF) include an enhanced peripheral sympathetic nerve activity which results in increased release of noradrenaline, neuropeptide Y and ATP. To examine if such changes in CHF would modulate peripheral pre- and postsynaptic receptors of ATP and its...... effects mediated by the endothelial P2Y receptors are unaffected in CHF. Moreover, the adenosine-mediated inhibitory effects on heart rate and blood pressure were also attenuated in the CHF rats. The most important changes in adenosine and P2-receptor function induced by ischaemic CHF were the reduced...... pressor effect mediated by the P2X receptor and the increased heart rate due to an attenuated inhibitory effect of adenosine....

  8. Role of adenosine in the antiepileptic effects of deep brain stimulation

    Miranda, Maisa F.; Hamani, Clement; de Almeida, Antônio-Carlos G.; Amorim, Beatriz O.; Macedo, Carlos E.; Fernandes, Maria José S.; Nobrega, José N.; Aarão, Mayra C.; Madureira, Ana Paula; Rodrigues, Antônio M.; Andersen, Monica L.; Tufik, Sergio; Mello, Luiz E.; Covolan, Luciene

    2014-01-01

    Despite the effectiveness of anterior thalamic nucleus (AN) deep brain stimulation (DBS) for the treatment of epilepsy, mechanisms responsible for the antiepileptic effects of this therapy remain elusive. As adenosine modulates neuronal excitability and seizure activity in animal models, we hypothesized that this nucleoside could be one of the substrates involved in the effects of AN DBS. We applied 5 days of stimulation to rats rendered chronically epileptic by pilocarpine injections and recorded epileptiform activity in hippocampal slices. We found that slices from animals given DBS had reduced hippocampal excitability and were less susceptible to develop ictal activity. In live animals, AN DBS significantly increased adenosine levels in the hippocampus as measured by microdialysis. The reduced excitability of DBS in vitro was completely abolished in animals pre-treated with A1 receptor antagonists and was strongly potentiated by A1 receptor agonists. We conclude that some of the antiepileptic effects of DBS may be mediated by adenosine. PMID:25324724

  9. Autoradiographic localization of adenosine receptors in rat brain using (/sup 3/H)cyclohexyladenosine

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

    1982-09-01

    Adenosine (A1) receptor binding sites have been localized in rat brain by an in vitro light microscopic autoradiographic method. The binding of (/sup 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.

  10. Adenosine A3 receptor activation is neuroprotective against retinal neurodegeneration.

    Galvao, Joana; Elvas, Filipe; Martins, Tiago; Cordeiro, M Francesca; Ambrósio, António Francisco; Santiago, Ana Raquel

    2015-11-01

    Death of retinal neural cells, namely retinal ganglion cells (RGCs), is a characteristic of several retinal neurodegenerative diseases. Although the role of adenosine A3 receptor (A3R) in neuroprotection is controversial, A3R activation has been reported to afford protection against several brain insults, with few studies in the retina. In vitro models (retinal neural and organotypic cultures) and animal models [ischemia-reperfusion (I-R) and partial optic nerve transection (pONT)] were used to study the neuroprotective properties of A3R activation against retinal neurodegeneration. The A3R selective agonist (2-Cl-IB-MECA, 1 μM) prevented apoptosis (TUNEL(+)-cells) induced by kainate and cyclothiazide (KA + CTZ) in retinal neural cultures (86.5 ± 7.4 and 37.2 ± 6.1 TUNEL(+)-cells/field, in KA + CTZ and KA + CTZ + 2-Cl-IB-MECA, respectively). In retinal organotypic cultures, 2-Cl-IB-MECA attenuated NMDA-induced cell death, assessed by TUNEL (17.3 ± 2.3 and 8.3 ± 1.2 TUNEL(+)-cells/mm(2) in NMDA and NMDA+2-Cl-IB-MECA, respectively) and PI incorporation (ratio DIV4/DIV2 3.3 ± 0.3 and 1.3 ± 0.1 in NMDA and NMDA+2-Cl-IB-MECA, respectively) assays. Intravitreal 2-Cl-IB-MECA administration afforded protection against I-R injury decreasing the number of TUNEL(+) cells by 72%, and increased RGC survival by 57%. Also, intravitreal administration of 2-Cl-IB-MECA inhibited apoptosis (from 449.4 ± 37.8 to 207.6 ± 48.9 annexin-V(+)-cells) and RGC loss (from 1.2 ± 0.6 to 8.1 ± 1.7 cells/mm) induced by pONT. This study demonstrates that 2-Cl-IB-MECA is neuroprotective to the retina, both in vitro and in vivo. Activation of A3R may have great potential in the management of retinal neurodegenerative diseases characterized by RGC death, as glaucoma and diabetic retinopathy, and ischemic diseases.

  11. Magnetically assisted fluorescence ratiometric assays for adenosine deaminase using water-soluble conjusated polymers

    HE Fang; YU MingHui; WANG Shu

    2009-01-01

    A magnetically assisted fluorescence ratiometric technique has been developed for adenosine deami-nase assays with high sensitivity using water-soluble cationic conjugated polymers (CCPs).The assay contains three elements:a biotin-labeled aptamer of adenosine (biotin-aptamer),a signaling probe single-stranded DNA-tagged fiuorescein at terminus (ssDNA-FI) and a CCP.The specific binding of adenosine to biotin-aptamer makes biotin-aptamer and ssDNA-FI unhybridized,and the ssDNA-FI is washed out after streptavidin-coated magnetic beads are added and separated from the assay solution under magnetic field.In this case,after the addition of CCP to the magnetic beads solution,the fluo-rescence resonance energy transfer (FRET) from CCP to fluorescein is inefficient.Upon adding adenosine deaminase,the adenosine is converted into inosine,and the biotin-aptamer is hybridized with ssDNA-FI to form doubled stranded DNA (biotin-dsDNA-FI).The ssONA-FI is attached to the mag-netic beads at the separation step,and the addition of CCP to the magnetic beads solution leads to efficient FRET from CCP to fluorescein.Thus the adenosine deaminase activity can be monitored by fluorescence spectra in view of the intensity decrease of CCP emission or the increase of fluorescein emission in aqueous solutions.The assay integrates surface-functionalized magnetic particles with significant amplification of detection signal of water-soluble cationic conjugated polymers.

  12. Adenosine receptor antagonists alter the stability of human epileptic GABAA receptors

    Roseti, Cristina; Martinello, Katiuscia; Fucile, Sergio; Piccari, Vanessa; Mascia, Addolorata; Di Gennaro, Giancarlo; Quarato, Pier Paolo; Manfredi, Mario; Esposito, Vincenzo; Cantore, Gianpaolo; Arcella, Antonella; Simonato, Michele; Fredholm, Bertil B.; Limatola, Cristina; Miledi, Ricardo; Eusebi, Fabrizio

    2008-01-01

    We examined how the endogenous anticonvulsant adenosine might influence γ-aminobutyric acid type A (GABAA) receptor stability and which adenosine receptors (ARs) were involved. Upon repetitive activation (GABA 500 μM), GABAA receptors, microtransplanted into Xenopus oocytes from neurosurgically resected epileptic human nervous tissues, exhibited an obvious GABAA-current (IGABA) run-down, which was consistently and significantly reduced by treatment with the nonselective adenosine receptor antagonist CGS15943 (100 nM) or with adenosine deaminase (ADA) (1 units/ml), that inactivates adenosine. It was also found that selective antagonists of A2B (MRS1706, 10 nM) or A3 (MRS1334, 30 nM) receptors reduced IGABA run-down, whereas treatment with the specific A1 receptor antagonist DPCPX (10 nM) was ineffective. The selective A2A receptor antagonist SCH58261 (10 nM) reduced or potentiated IGABA run-down in ≈40% and ≈20% of tested oocytes, respectively. The ADA-resistant, AR agonist 2-chloroadenosine (2-CA) (10 μM) potentiated IGABA run-down but only in ≈20% of tested oocytes. CGS15943 administration again decreased IGABA run-down in patch-clamped neurons from either human or rat neocortex slices. IGABA run-down in pyramidal neurons was equivalent in A1 receptor-deficient and wt neurons but much larger in neurons from A2A receptor-deficient mice, indicating that, in mouse cortex, GABAA-receptor stability is tonically influenced by A2A but not by A1 receptors. IGABA run-down from wt mice was not affected by 2-CA, suggesting maximal ARs activity by endogenous adenosine. Our findings strongly suggest that cortical A2–A3 receptors alter the stability of GABAA receptors, which could offer therapeutic opportunities. PMID:18809912

  13. Adenosine transport systems on dissociated brain cells from mouse, guinea-pig, and rat

    Johnston, M.E.; Geiger, J.D. (Univ. of Manitoba, Winnipeg (Canada))

    1990-09-01

    The kinetics and sodium dependence of adenosine transport were determined using an inhibitor-stop method on dissociated cell body preparations obtained from mouse, guinea-pig and rat brain. Transport affinity (KT) values for the high affinity adenosine transport systems KT(H) were significantly different between these three species; mean +/- SEM values were 0.34 +/- 0.1 in mouse, 0.9 +/- 0.2 in rat, and 1.5 +/- 0.5 microM in guinea-pig. The KT values for the low affinity transport system KT(L) were not different between the three species. Brain cells from rat displayed a significantly greater maximal capacity to accumulate (3H)adenosine (Vmax) than did mouse or guinea-pig for the high affinity system, or than did mouse for the low affinity system. When sodium chloride was replaced in the transport medium with choline chloride, the KT(H) values for guinea-pig and rat were both increased by approximately 100%; only in rat did the change reach statistical significance. The sodium-dependence of adenosine transport in mouse brain was clearly absent. The differences between KT(H) values in mouse and those in guinea-pig or rat were accentuated in the absence of sodium. The differences in kinetic values, ionic requirements, and pharmacological characteristics between adenosine transporters in CNS tissues of mouse, guinea-pig and rat may help account for some of the variability noted among species in terms of their physiological responses to adenosine.

  14. Plasma concentrations of the cyclic nucleotides, adenosine 3',5'-monophosphate and guanosine 3'.5'-monophosphate, in healthy adults treated with theophylline

    Fenger, M; Eriksen, P B; Andersen, O;

    1982-01-01

    Plasma concentrations of cyclic adenosine monophosphate and cyclic guanosine monophosphate were measured in 10 health adults before, during and after periods of theophylline administration. Cyclic adenosine monophosphate concentrations did not change significantly, but cyclic guanosine monophosph...

  15. Caffeine intake inverts the effect of adenosine on myocardial perfusion during stress as measured by T1 mapping

    Kuijpers, Dirkjan; Prakken, Niek H.; Vliegenthart, Rozemarijn; van Dijkman, Paul R. M.; van der Harst, Pim; Oudkerk, Matthijs

    2016-01-01

    Caffeine intake before adenosine stress myocardial perfusion imaging may cause false negative findings. We hypothesized that the antagonistic effect of caffeine can be measured by T1 relaxation times in rest and adenosine stress cardiac magnetic resonance imaging (CMR), as T1 mapping techniques are

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

    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.

  17. NTS adenosine A2a receptors inhibit the cardiopulmonary chemoreflex control of regional sympathetic outputs via a GABAergic mechanism.

    Minic, Zeljka; O'Leary, Donal S; Scislo, Tadeusz J

    2015-07-01

    Adenosine is a powerful central neuromodulator acting via opposing A1 (inhibitor) and A2a (activator) receptors. However, in the nucleus of the solitary tract (NTS), both adenosine receptor subtypes attenuate cardiopulmonary chemoreflex (CCR) sympathoinhibition of renal, adrenal, and lumbar sympathetic nerve activity and attenuate reflex decreases in arterial pressure and heart rate. Adenosine A1 receptors inhibit glutamatergic transmission in the CCR pathway, whereas adenosine A2a receptors most likely facilitate release of an unknown inhibitory neurotransmitter, which, in turn, inhibits the CCR. We hypothesized that adenosine A2a receptors inhibit the CCR via facilitation of GABA release in the NTS. In urethane-chloralose-anesthetized rats (n = 51), we compared regional sympathetic responses evoked by stimulation of the CCR with right atrial injections of the 5-HT3 receptor agonist phenylbiguanide (1-8 μg/kg) before and after selective stimulation of NTS adenosine A2a receptors [microinjections into the NTS of CGS-21680 (20 pmol/50 nl)] preceded by blockade of GABAA or GABAB receptors in the NTS [bicuculline (10 pmol/100 nl) or SCH-50911 (1 nmol/100 nl)]. Blockade of GABAA receptors virtually abolished adenosine A2a receptor-mediated inhibition of the CCR. GABAB receptors had much weaker but significant effects. These effects were similar for the different sympathetic outputs. We conclude that stimulation of NTS adenosine A2a receptors inhibits CCR-evoked hemodynamic and regional sympathetic reflex responses via a GABA-ergic mechanism.

  18. Adenosine as a signaling molecule in the retina: biochemical and developmental aspects

    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

  19. Investigation of the Interaction between Adenosine and Human Serum Albumin by Fluorescent Spectroscopy and Molecular Modeling

    CUI Feng-Ling; WANG Jun-Li; LI Fang; FAN Jing; QU Gui-Rong; YAO Xiao-Jun; LEI Bei-Lei

    2008-01-01

    The binding interaction of adenosine with human serum albumin (HSA) was investigated under simulative physiological conditions by fluorescence spectroscopy in combination with a molecular modeling method. A strong fluorescence quenching reaction of adenosine to HSA was observed and the quenching mechanism was suggested as static quenching according to the Stern-Volmer equation. The binding constants (K) at different temperatures as well as thermodynamic parameters, enthalpy change (ΔH) and entropy change (ΔS), were calculated according to relevant fluorescent data and Vant'Hoff equation. The hydrophobic interaction was a predominant intermolecular force in order to stabilize the complex, which was in agreement with the results of molecular modeling study.

  20. Extracellular adenosine regulates colitis through effects on lymphoid and nonlymphoid cells

    Kurtz, Courtney C.; Drygiannakis, Ioannis; Naganuma, Makoto; Feldman, Sanford; Bekiaris, Vasileios; Linden, Joel; Ware, Carl F.; Ernst, Peter B.

    2014-01-01

    Adenosine is a purine metabolite that can mediate anti-inflammatory responses in the digestive tract through the A2A adenosine receptor (A2AAR). We examined the role of this receptor in the control of inflammation in the adoptive transfer model of colitis. Infection of A2AAR−/− mice with Helicobacter hepaticus increased colonic inflammation scores compared with uninfected A2AAR controls. Comparison of T cell subsets in wild-type and A2AAR−/− mice revealed differences in markers associated wit...

  1. Dielectric spectra broadening as a signature for dipole-matrix interaction. III. Water in adenosine monophosphate/adenosine-5'-triphosphate solutions.

    Puzenko, Alexander; Levy, Evgeniya; Shendrik, Andrey; Talary, Mark S; Caduff, Andreas; Feldman, Yuri

    2012-11-21

    In this, the third part of our series on the dielectric spectrum symmetrical broadening of water, we consider the nucleotide aqueous solutions. Where in Parts I [E. Levy et al., J. Chem. Phys. 136, 114502 (2012)] and II [E. Levy et al., J. Chem. Phys. 136, 114503 (2012)], the dipole-dipole or ion-dipole interaction had a dominant feature, now the interplay between these two types of dipole-matrix interactions will be considered. We present the results of high frequency dielectric measurements of different concentrations of adenosine monophosphate/adenosine-5'-triphosphate aqueous solutions. We observed the Cole-Cole broadening of the main relaxation peak of the solvent in the solutions. Moreover, depending on the nucleotide concentration, we observed both types of dipole-matrix interaction. The 3D trajectory approach (described in detail in Part I) is applied in order to highlight the differences between the two types of interaction.

  2. 原花色素降血脂机制研究进展%The Hypolipidemic Mechanism of Proanthocyanidins

    张妤; 李澜奇; 龚辉; 陈士国; 叶兴乾

    2016-01-01

    Proanthocyanidins are a class of polyphenols that consist of flavan-3-ols as their basic unit and exist in various types of plants. In this review, the regulation of proanthocyanidins on the key proteins of the metabolism pathways of triglycerides and cholesterol is summarized. Also, how proanthocyanidins regulate body weight, energy intake and energy expenditure through adenosine 5’-monophosphate-activated protein kinase (AMPK) pathway to exert their hypolipidemic effects is demonstrated with details as well.%原花色素是以黄烷-3-醇为基本单元,在自然界中广泛存在的多酚类物质,具有多种生物活性。本文综述了原花色素如何调节甘油三酯和胆固醇代谢过程中的关键蛋白从而控制体内主要脂类的含量;此外,还总结了原花色素如何调节体质量、能量摄入以及通过调节AMP依赖蛋白激酶(adenosine 5’-monophosphate-activated protein kinase,AMPK)信号通路影响能量消耗,进而综合调控体内血脂的含量,达到降低血脂的功能。

  3. Repetitive systemic morphine alters activity-dependent plasticity of Schaffer-collateral-CA1 pyramidal cell synapses: involvement of adenosine A1 receptors and adenosine deaminase.

    Sadegh, Mehdi; Fathollahi, Yaghoub

    2014-10-01

    The effectiveness of O-pulse stimulation (TPS) for the reversal of O-pattern primed bursts (PB)-induced long-term potentiation (LTP) were examined at the Schaffer-collateral-CA1 pyramidal cell synapses of hippocampal slices derived from rats chronically treated with morphine (M-T). The results showed that slices derived from both control and M-T rats had normal field excitatory postsynaptic potential (fEPSP)-LTP, whereas PS-LTP in slices from M-T rats was significantly greater than that from control slices. When morphine was applied in vitro to slices derived from rats chronically treated with morphine, the augmentation of PS-LTP was not seen. TPS given 30 min after LTP induction failed to reverse the fEPSP- or PS-LTP in both groups of slices. However, TPS delivered in the presence of long-term in vitro morphine caused the PS-LTP reversal. This effect was blocked by the adenosine A1 receptor (A1R) antagonist CPX (200 nM) and furthermore was enhanced by the adenosine deaminase (ADA) inhibitor EHNA (10 μM). Interestingly, TPS given 30 min after LTP induction in the presence of EHNA (10 μM) can reverse LTP in morphine-exposed control slices in vitro. These results suggest adaptive changes in the hippocampus area CA1 in particular in adenosine system following repetitive systemic morphine. Chronic in vivo morphine increases A1R and reduces ADA activity in the hippocampus. Consequently, adenosine can accumulate because of a stimulus train-induced activity pattern in CA1 area and takes the opportunity to work as an inhibitory neuromodulator and also to enable CA1 to cope with chronic morphine. In addition, adaptive mechanisms are differentially working in the dendrite layer rather than the somatic layer of hippocampal CA1.

  4. Adenosine A(1) Receptors in the Central Nervous System : Their Functions in Health and Disease, and Possible Elucidation by PET Imaging

    Paul, S.; Elsinga, P. H.; Ishiwata, K.; Dierckx, R. A. J. O.; van Waarde, A.

    2011-01-01

    Adenosine is a neuromodulator with several functions in the central nervous system (CNS), such as inhibition of neuronal activity in many signaling pathways. Most of the sedating, anxiolytic, seizure-inhibiting and protective actions of adenosine are mediated by adenosine A(1) receptors (A(1)R) on t

  5. The Safety of an Adenosine A(1)-Receptor Antagonist, Rolofylline, in Patients with Acute Heart Failure and Renal Impairment Findings from PROTECT

    Teerlink, John R.; Iragui, Vicente J.; Mohr, Jay P.; Carson, Peter E.; Hauptman, Paul J.; Lovett, David H.; Miller, Alan B.; Pina, Ileana L.; Thomson, Scott; Varosy, Paul D.; Zile, Michael R.; Cleland, John G. F.; Givertz, Michael M.; Metra, Marco; Ponikowski, Piotr; Voors, Adriaan A.; Davison, Beth A.; Cotter, Gad; Wolko, Denise; DeLucca, Paul; Salerno, Christina M.; Mansoor, George A.; Dittrich, Howard; O'Connor, Christopher M.; Massi, Barry M.

    2012-01-01

    Background: Adenosine exerts actions in multiple organ systems, and adenosine receptors are a therapeutic target in many development programmes. Objective: The aim of this analysis was to evaluate the safety of rolofylline, an adenosine A(1)-receptor antagonist, in patients with acute heart failure.

  6. Production of adenosine from extracellular ATP at the striatal cholinergic synapse.

    James, S; Richardson, P J

    1993-01-01

    The components of the ectonucleotidase pathway at the immunoaffinity-purified striatal cholinergic synapse have been studied. The ecto-ATPase (EC 3.6.1.15) had a Km of 131 microM, whereas the ecto-ADPase (EC 3.6.1.6) had a Km of 58 microM, was Ca(2+)-dependent, and was inhibited by the ATP analogue 5'-adenylylimidodiphosphate (AMPPNP). The ecto-5'-nucleotidase (EC 3.1.3.5) had a Km of 21 microM, was inhibited by AMPPNP and alpha,beta-methylene ADP, and by a specific antiserum. The Vmax values of the ATPase, ADPase, and 5'-nucleotidase enzymes present at this synapse were in a ratio of 30:14:1. Very little ecto-adenylate kinase activity was detected on these purified synapses. The intraterminal 5'-nucleotidase enzyme, which amounted to 40% of the total 5'-nucleotidase activity, was inhibited by AMPPNP, alpha,beta-methylene ADP, and the antiserum, and also had the same kinetic properties as the ectoenzyme. The time course of ATP degradation to adenosine outside the nerve terminals showed a delay, followed by a period of sustained adenosine production. The delay in adenosine production was proportional to the initial ATP concentration, was a consequence of feedforward inhibition of the ADPase and 5'-nucleotidase, and was inversely proportional to the ecto-5'-nucleotidase activity. The function and characteristics of this pathway and the central role of 5'-nucleotidase in the regulation of extraterminal adenosine concentrations are discussed.

  7. Pyrazolo Derivatives as Potent Adenosine Receptor Antagonists: An Overview on the Structure-Activity Relationships

    Siew Lee Cheong

    2011-01-01

    Full Text Available In the past few decades, medicinal chemistry research towards potent and selective antagonists of human adenosine receptors (namely, A1, A2A, A2B, and A3 has been evolving rapidly. These antagonists are deemed therapeutically beneficial in several pathological conditions including neurological and renal disorders, cancer, inflammation, and glaucoma. Up to this point, many classes of compounds have been successfully synthesized and identified as potent human adenosine receptor antagonists. In this paper, an overview of the structure-activity relationship (SAR profiles of promising nonxanthine pyrazolo derivatives is reported and discussed. We have emphasized the SAR for some representative structures such as pyrazolo-[4,3-e]-1,2,4-triazolo-[1,5-c]pyrimidines; pyrazolo-[3,4-c] or -[4,3-c]quinolines; pyrazolo-[4,3-d]pyrimidinones; pyrazolo-[3,4-d]pyrimidines and pyrazolo-[1,5-a]pyridines. This overview not only clarifies the structural requirements deemed essential for affinity towards individual adenosine receptor subtypes, but it also sheds light on the rational design and optimization of existing structural templates to allow us to conceive new, more potent adenosine receptor antagonists.

  8. Identification of A3 adenosine receptor agonists as novel non-narcotic analgesics.

    Janes, K; Symons-Liguori, A M; Jacobson, K A; Salvemini, D

    2016-04-01

    Chronic pain negatively impacts the quality of life in a variety of patient populations. The current therapeutic repertoire is inadequate in managing patient pain and warrants the development of new therapeutics. Adenosine and its four cognate receptors (A1 , A2A , A2B and A3 ) have important roles in physiological and pathophysiological states, including chronic pain. Preclinical and clinical studies have revealed that while adenosine and agonists of the A1 and A2A receptors have antinociceptive properties, their therapeutic utility is limited by adverse cardiovascular side effects. In contrast, our understanding of the A3 receptor is only in its infancy, but exciting preclinical observations of A3 receptor antinociception, which have been bolstered by clinical trials of A3 receptor agonists in other disease states, suggest pain relief without cardiovascular side effects and with sufficient tolerability. Our goal herein is to briefly discuss adenosine and its receptors in the context of pathological pain and to consider the current data regarding A3 receptor-mediated antinociception. We will highlight recent findings regarding the impact of the A3 receptor on pain pathways and examine the current state of selective A3 receptor agonists used for these studies. The adenosine-to-A3 receptor pathway represents an important endogenous system that can be targeted to provide safe, effective pain relief from chronic pain.

  9. A3 Adenosine receptors mediate oligodendrocyte death and ischemic damage to optic nerve.

    González-Fernández, Estíbaliz; Sánchez-Gómez, María Victoria; Pérez-Samartín, Alberto; Arellano, Rogelio O; Matute, Carlos

    2014-02-01

    Adenosine receptor activation is involved in myelination and in apoptotic pathways linked to neurodegenerative diseases. In this study, we investigated the effects of adenosine receptor activation in the viability of oligodendrocytes of the rat optic nerve. Selective activation of A3 receptors in pure cultures of oligodendrocytes caused concentration-dependent apoptotic and necrotic death which was preceded by oxidative stress and mitochondrial membrane depolarization. Oligodendrocyte apoptosis induced by A3 receptor activation was caspase-dependent and caspase-independent. In addition to dissociated cultures, incubation of optic nerves ex vivo with adenosine and the A3 receptor agonist 2-CI-IB-MECA(1-[2-Chloro-6-[[(3-iodophenyl)methyl]amino]-9H-purin-9-yl]-1-deoxy-N-methyl-b-D-ribofuranuronamide)-induced caspase-3 activation, oligodendrocyte damage, and myelin loss, effects which were prevented by the presence of caffeine and the A3 receptor antagonist MRS 1220 (N-[9-Chloro-2-(2-furanyl)[1,2,4]-triazolo [1,5-c]quinazolin-5-yl]benzene acetamide). Finally, ischemia-induced injury and functional loss to the optic nerve was attenuated by blocking A3 receptors. Together, these results indicate that adenosine may trigger oligodendrocyte death via activation of A3 receptors and suggest that this mechanism contributes to optic nerve and white matter ischemic damage.

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

    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) re...

  11. Outcome of hematopoietic stem cell transplantation for adenosine deaminase-deficient severe combined immunodeficiency

    Hassan, Amel; Booth, Claire; Brightwell, Alex; Allwood, Zoe; Veys, Paul; Rao, Kanchan; Hoenig, Manfred; Friedrich, Wilhelm; Gennery, Andrew; Slatter, Mary; Bredius, Robbert; Finocchi, Andrea; Cancrini, Caterina; Aiuti, Alessandro; Porta, Fulvio; Lanfranchi, Arnalda; Ridella, Michela; Steward, Colin; Filipovich, Alexandra; Marsh, Rebecca; Bordon, Victoria; Al-Muhsen, Saleh; Al-Mousa, Hamoud; Alsum, Zobaida; Al-Dhekri, Hasan; Al Ghonaium, Abdulaziz; Speckmann, Carsten; Fischer, Alain; Mahlaoui, Nizar; Nichols, Kim E.; Grunebaum, Eyal; Al Zahrani, Daifulah; Roifman, Chaim M.; Boelens, Jaap; Davies, E. Graham; Cavazzana-Calvo, Marina; Notarangelo, Luigi; Gaspar, H. Bobby

    2012-01-01

    Deficiency of the purine salvage enzyme adenosine deaminase leads to SCID (ADA-SCID). Hematopoietic cell transplantation (HCT) can lead to a permanent cure of SCID; however, little data are available on outcome of HCT for ADA-SCID in particular. In this multicenter retrospective study, we analyzed o

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

    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.

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

    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 Alz

  14. REPRODUCTIVE CONDITION, GLOMERULAR ADENOSINE DIPHOSPHATASE ACTIVITY, AND PLATELET-AGGREGATION IN THE RAT - EFFECT OF ENDOTOXIN

    VISSCHER, CA; FAAS, MM; BAKKER, WW; SCHUILING, GA

    1993-01-01

    In experiment A, the activity of the glomerular antithrombotic enzyme adenosine diphosphatase (ADPase) and the sensitivity of this enzyme for endotoxin (1.0 mug/kg BW) in various reproductive conditions of female rats were studied through use of enzyme histochemical methods. In experiment B, the eff

  15. Determination of Adenosine Triphosphate on Marine Particulates:Synthesis of Methods for Use on OTEC Samples

    Jones, Anthony T.; Hartwig, Eric O.

    1982-08-01

    Adenosine triphosphate (ATP) is an indicator of living biomass in marine particulates. This report details the method used by Lawrence Berkeley Laboratory to analyze particulate ATP in samples taken from oligotrophic, tropical ocean waters. It represents a synthesis of previously published methods.

  16. Determination of adenosine triphosphate on marine particulates: synthesis of methods for use on OTEC samples

    Jones, A.T.; Hartwig, E.O.

    1982-08-01

    Adenosine triphosphate (ATP) is an indicator of living biomass in marine particulates. This report details the method used by Lawrence Berkeley Laboratory to analyze particulate ATP in samples taken from oligotrophic, tropical ocean waters. It represents a synthesis of previously published methods.

  17. Ischemic nucleotide breakdown increases during cardiac development due to drop in adenosine anabolism/catabolism ratio

    J.W. de Jong (Jan Willem); E. Keijzer (Elisabeth); T. Huizer (Tom); B. Schoutsen

    1990-01-01

    markdownabstractAbstract Our earlier work on reperfusion showed that adult rat hearts released almost twice as much purine nucleosides and oxypurines as newborn hearts did [Am J Physiol 254 (1988) H1091]. A change in the ratio anabolism/catabolism of adenosine could be responsible for this effect.

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

    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 (

  19. The effect of ticlopidine administration to humans on the binding of adenosine diphosphate to blood platelets

    Lips, J.P.M.; Sixma, J.J.; Schiphorst, M.E.

    1980-01-01

    Administration of Ticlopidine to human volunteers resulted in a prolonged bleeding time and decreased or absent aggregation of platelets with collagen and epinephrine. Adenosine diphosphate (ADP) induced platelet aggregation was initiated by a normal shape change, but the rate of the first wave of a

  20. High fetal plasma adenosine concentration: a role for the fetus in preeclampsia?

    Espinoza, Jimmy

    2012-02-01

    OBJECTIVE: Clinical observations suggest a role for the fetus in the maternal manifestations of preeclampsia, but the possible signaling mechanisms remain unclear. This study compares the fetal plasma concentrations of adenosine from normal pregnancies with those from preeclampsia. STUDY DESIGN: This secondary data analysis included normal pregnancies (n = 27) and patients with preeclampsia (n = 39). Patients with preeclampsia were subclassified into patients with (n = 25) and without (n = 14) abnormal uterine artery Doppler velocimetry (UADV). RESULTS: Fetal plasma concentrations of adenosine were significantly higher in patients with preeclampsia (1.35 +\\/- 0.09 mumol\\/L) than in normal pregnancies (0.52 +\\/- 0.06 mumol\\/L; P < .0001). Fetal plasma concentrations of adenosine in patients with preeclampsia with abnormal UADV (1.78 +\\/- 0.15 mumol\\/L), but not with normal UADV (0.58 +\\/- 0.14 mumol\\/L), were significantly higher than in normal pregnancies (P < .0001). CONCLUSION: Patients with preeclampsia with sonographic evidence of chronic uteroplacental ischemia have high fetal plasma concentrations of adenosine.

  1. Unexpected Discovery of Dichloroacetate Derived Adenosine Triphosphate Competitors Targeting Pyruvate Dehydrogenase Kinase To Inhibit Cancer Proliferation.

    Zhang, Shao-Lin; Hu, Xiaohui; Zhang, Wen; Tam, Kin Yip

    2016-04-14

    Pyruvate dehydrogenase kinases (PDKs) have recently emerged as an attractive target for cancer therapy. Herein, we prepared a series of compounds derived from dichloroacetate (DCA) which inhibited cancer cells proliferation. For the first time, we have successfully developed DCA derived inhibitors that preferentially bind to the adenosine triphosphate (ATP) pocket of PDK isoform 1 (PDK1).

  2. B-cell development and functions and therapeutic options in adenosine deaminase-deficient patients

    I. Brigida (Immacolata); A.V. Sauer (Aisha); F. Ferrua (Francesca); S. Giannelli (Stefania); S. Scaramuzza (Samantha); V. Pistoia (Valentina); M.C. Castiello (Maria Carmina); B.H. Barendregt (Barbara); M.P. Cicalese (Maria Pia); F. Casiraghi (Federica); C. Brombin (Chiara); J. Puck (Jennifer); K. Muller (Karin); L.D. Notarangelo (Luigi Daniele); D. Montin (Davide); J.M. van Montfrans (Joris); M.G. Roncarolo (Maria Grazia); E. Traggiai (Elisabetta); J.J.M. van Dongen (Jacques); M. van der Burg (Mirjam); A. Aiuti (Alessandro)

    2014-01-01

    textabstractBackground Adenosine deaminase (ADA) deficiency causes severe cellular and humoral immune defects and dysregulation because of metabolic toxicity. Alterations in B-cell development and function have been poorly studied. Enzyme replacement therapy (ERT) and hematopoietic stem cell (HSC) g

  3. Erythrocytes retain hypoxic adenosine response for faster acclimatization upon re-ascent

    Song, Anren; Zhang, Yujin; Han, Leng; Yegutkin, Gennady G.; Liu, Hong; Sun, Kaiqi; D'Alessandro, Angelo; Li, Jessica; Karmouty-Quintana, Harry; Iriyama, Takayuki; Weng, Tingting; Zhao, Shushan; Wang, Wei; Wu, Hongyu; Nemkov, Travis; Subudhi, Andrew W.; Jameson-Van Houten, Sonja; Julian, Colleen G.; Lovering, Andrew T.; Hansen, Kirk C.; Zhang, Hong; Bogdanov, Mikhail; Dowhan, William; Jin, Jianping; Kellems, Rodney E.; Eltzschig, Holger K.; Blackburn, Michael; Roach, Robert C.; Xia, Yang

    2017-01-01

    Faster acclimatization to high altitude upon re-ascent is seen in humans; however, the molecular basis for this enhanced adaptive response is unknown. We report that in healthy lowlanders, plasma adenosine levels are rapidly induced by initial ascent to high altitude and achieved even higher levels upon re-ascent, a feature that is positively associated with quicker acclimatization. Erythrocyte equilibrative nucleoside transporter 1 (eENT1) levels are reduced in humans at high altitude and in mice under hypoxia. eENT1 deletion allows rapid accumulation of plasma adenosine to counteract hypoxic tissue damage in mice. Adenosine signalling via erythrocyte ADORA2B induces PKA phosphorylation, ubiquitination and proteasomal degradation of eENT1. Reduced eENT1 resulting from initial hypoxia is maintained upon re-ascent in humans or re-exposure to hypoxia in mice and accounts for erythrocyte hypoxic memory and faster acclimatization. Our findings suggest that targeting identified purinergic-signalling network would enhance the hypoxia adenosine response to counteract hypoxia-induced maladaptation. PMID:28169986

  4. Adenosine A2 receptor activation ameliorates mitochondrial oxidative stress upon reperfusion through the posttranslational modification of NDUFV2 subunit of complex I in the heart.

    Xu, Jingman; Bian, Xiyun; Liu, Yuan; Hong, Lan; Teng, Tianming; Sun, Yuemin; Xu, Zhelong

    2017-02-20

    While it is well known that adenosine receptor activation protects the heart from ischemia/reperfusion injury, the precise mitochondrial mechanism responsible for the action remains unknown. This study probed the mitochondrial events associated with the cardioprotective effect of 5'-(N-ethylcarboxamido) adenosine (NECA), an adenosine A2 receptor agonist. Isolated rat hearts were subjected to 30min ischemia followed by 10min of reperfusion, whereas H9c2 cells experienced 20min ischemia and 10min reperfusion. NECA prevented mitochondrial structural damage, decreases in respiratory control ratio (RCR), and collapse of mitochondrial membrane potential (ΔΨm). Both the adenosine A2A receptor antagonist SCH58261 and A2B receptor antagonist MRS1706 inhibited the action of NECA. NECA reduced mitochondrial proteins carbonylation, H2O2, and superoxide generation at reperfusion, but did not change superoxide dismutase (SOD) activity. In support, the protective effects of NECA and Peg-SOD on ΔΨm upon reperfusion were additive, implying that NECA's protection is attributable to the reduced superoxide generation but not to the enhancement of the superoxide-scavenging capacity. NECA increased the mitochondrial Src tyrosine kinase activity and suppressed complex I activity at reperfusion in a Src-dependent manner. NECA also reduced mitochondrial superoxide through Src tyrosine kinase. Studies with liquid chromatography-mass spectrometer (LC-MS) identified Tyr118 of the NDUFV2 subunit of complex 1 as a likely site of the tyrosine phosphorylation. Furthermore, the complex I activity of cells transfected with the Y118F mutant was increased, suggesting that this site might be a negative regulator of complex I activity. In support, NECA failed to suppress complex I activity at reperfusion in cells transfected with the Y118F mutant of NDUFV2. In conclusion, NECA prevents mitochondrial oxidative stress by decreasing mitochondrial superoxide generation through inhibition of complex I

  5. Inhibition of adenosine deaminase attenuates endotoxin-induced release of cytokines in vivo in rats.

    Tofovic, S P; Zacharia, L; Carcillo, J A; Jackson, E K

    2001-09-01

    The purpose of this study was to investigate in vivo the effects of modulating the adenosine system on endotoxin-induced release of cytokines and changes in heart performance and neurohumoral status in early, profound endotoxemia in rats. Time/pressure variables of heart performance and blood pressure were recorded continuously, and plasma levels of tumor necrosis factor alpha (TNFalpha), interleukin 1-beta (IL-1beta), plasma renin activity (PRA), and catecholamines were determined before and 90 min after administration of endotoxin (30 mg/kg of lipopolysaccharide, i.v.). Erythro-9[2-hydroxyl-3-nonyl] adenine (EHNA; an adenosine deaminase inhibitor) had no effects on measured time-pressure variables of heart performance under baseline conditions and during endotoxemia, yet significantly attenuated endotoxin-induced release of cytokines and PRA. Pretreatment with the non-selective adenosine receptor antagonist DPSPX not only prevented the effects of EHNA but also increased the basal release of cytokines and augmented PRA. At baseline, caffeine (a non-selective adenosine receptor antagonist) increased HR, +dP/dtmax, heart rate x ventricular pressure product (HR x VPSP) and +dP/dtmax normalized by pressure (+dP/dtmax/VPSP), and these changes persisted during endotoxemia. Caffeine attenuated endotoxin-induced release of cytokines and augmented endotoxin-induced increases in plasma catecholamines and PRA. Pretreatment with propranolol abolished the effects of caffeine on heart performance and neurohumoral activation during the early phase of endotoxemia. 6N-cyclopentyladenosine (CPA; selective A1 adenosine receptor agonist) induced bradicardia and negative inotropic effects, reduced work load (i.e., decreased HR, VPSP, +dP/dtmax, +dP/dtmax/VPSP and HR x VPSP) and inhibited endotoxin-induced tachycardia and renin release. CGS 21680 (selective A2A adenosine receptor agonist) decreased blood pressure under basal condition but did not potentiate decreases in blood pressure

  6. Long-term administration of Delta9-tetrahydrocannabinol desensitizes CB1-, adenosine A1-, and GABAB-mediated inhibition of adenylyl cyclase in mouse cerebellum.

    Selley, Dana E; Cassidy, Michael P; Martin, Billy R; Sim-Selley, Laura J

    2004-11-01

    Cannabinoid CB(1) receptors in the cerebellum mediate the inhibitory effects of Delta(9)-tetrahydrocannabinol (THC) on motor coordination. Intracellular effects of CB(1) receptors include inhibition of adenylyl cyclase via activation of G(i/o) proteins. There is evidence for the convergence of other neuronal receptors, such as adenosine A(1) and GABA(B), with the cannabinoid system on this signaling pathway to influence motor function. Previous studies have shown that brain CB(1) receptors are desensitized and down-regulated by long-term THC treatment, but few studies have examined the effects of long-term THC treatment on downstream effector activity in brain. Therefore, these studies examined the relationship between CB(1), adenosine A(1), and GABA(B) receptors in cerebella of mice undergoing prolonged treatment with vehicle or THC at the level of G protein activation and adenylyl cyclase inhibition. In control cerebella, CB(1) receptors produced less than additive inhibition of adenylyl cyclase with GABA(B) and A(1) receptors, indicating that these receptors are localized on overlapping populations of cells. Long-term THC treatment produced CB(1) receptor down-regulation and desensitization of both cannabinoid agonist-stimulated G protein activation and inhibition of forskolin-stimulated adenylyl cyclase. However, G protein activation by GABA(B) or A(1) receptors was unaffected. It is noteworthy that heterologous attenuation of GABA(B) and A(1) receptor-mediated inhibition of adenylyl cyclase was observed, even though absolute levels of basal and forskolin- or G(s)-stimulated activity were unchanged. These results indicate that long-term THC administration produces a disruption of inhibitory receptor control of cerebellar adenylyl cyclase and suggest a potential mechanism of cross-tolerance to the motor incoordinating effects of cannabinoid, GABA(B), and A(1) agonists.

  7. Modulatory effect of adenosine receptors on the ascending and descending neural reflex responses of rat ileum

    Schusdziarra Volker

    2002-12-01

    Full Text Available Abstract Background Adenosine is known to act as a neuromodulator by suppressing synaptic transmission in the central and peripheral nervous system. Both the release of adenosine within the small intestine and the presence of adenosine receptors on enteric neurons have been demonstrated. The aim of the present study was to characterize a possible involvement of adenosine receptors in the modulation of the myenteric reflex. The experiments were carried out on ileum segments 10 cm in length incubated in an single chambered organ bath, and the reflex response was initiated by electrical stimulation (ES. Results ES caused an ascending contraction and a descending relaxation followed by a contraction. All motility responses to ES were completely blocked by tetrodotoxin, indicating that they are mediated by neural mechanisms. Atropine blocked the contractile effects, whereas the descending relaxation was significantly increased. The A1 receptor agonist N6-cyclopentyladenosine increased the ascending contraction, whereas the ascending contraction was reduced by the A1 receptor antagonist 8-cyclopentyl-1,3-dipropylxanthine. Activation of the A1 receptor further reduced the descending relaxation and the latency of the peristaltic reflex. The A2B receptor antagonist alloxazine increased ascending contraction, whereas descending relaxation remained unchanged. For A2A and A3 receptors, we found contradictory effects of the agonists and antagonists, thus there is no clear physiological role for these receptors at this time. Conclusions This study suggests that the myenteric ascending and descending reflex response of the rat small intestine is modulated by release of endogenous adenosine via A1 receptors.

  8. Cloning of two adenosine receptor subtypes from mouse bone marrow-derived mast cells.

    Marquardt, D L; Walker, L L; Heinemann, S

    1994-05-01

    Adenosine potentiates the stimulated release of mast cell mediators. Pharmacologic studies suggest the presence of two adenosine receptors, one positively coupled to adenylate cyclase and the other coupled to phospholipase C activation. To identify mast cell adenosine receptor subtypes, cDNAs for the A1 and A2a adenosine receptors were obtained by screening a mouse brain cDNA library with the use of PCR-derived probes. Mouse bone marrow-derived mast cell cDNA libraries were constructed and screened with the use of A1 and A2a cDNA probes, which revealed the presence of A2a, but not A1, receptor clones. A putative A2b receptor was identified by using low stringency mast cell library screening. Northern blotting of mast cell poly(A)+ RNA with the use of receptor subtype probes labeled single mRNA bands of 2.4 kb and 1.8 kb for the A2a and A2b receptors, respectively. In situ cells. An A2a receptor-specific agonist failed to enhance mast cell mediator release, which suggests that the secretory process is modulated through the A2b and/or another receptor subtype. By using RNase protection assays, we found that mast cells that had been cultured in the presence of N-ethylcarboxamidoadenosine for 24 h exhibited a decrease in both A2a and A2b receptor RNA levels. Cells that had been cultured for 1 to 2 days in the presence of dexamethasone demonstrated increased amounts of A2a receptor mRNA, but no identifiable change in A2b receptor mRNA. Mast cells possess at least two adenosine receptor subtypes that may be differentially regulated.

  9. Adenosine, caffeine, and performance: from cognitive neuroscience of sleep to sleep pharmacogenetics.

    Urry, Emily; Landolt, Hans-Peter

    2015-01-01

    An intricate interplay between circadian and sleep-wake homeostatic processes regulate cognitive performance on specific tasks, and individual differences in circadian preference and sleep pressure may contribute to individual differences in distinct neurocognitive functions. Attentional performance appears to be particularly sensitive to time of day modulations and the effects of sleep deprivation. Consistent with the notion that the neuromodulator, adenosine , plays an important role in regulating sleep pressure, pharmacologic and genetic data in animals and humans demonstrate that differences in adenosinergic tone affect sleepiness, arousal and vigilant attention in rested and sleep-deprived states. Caffeine--the most often consumed stimulant in the world--blocks adenosine receptors and normally attenuates the consequences of sleep deprivation on arousal, vigilance, and attention. Nevertheless, caffeine cannot substitute for sleep, and is virtually ineffective in mitigating the impact of severe sleep loss on higher-order cognitive functions. Thus, the available evidence suggests that adenosinergic mechanisms, in particular adenosine A2A receptor-mediated signal transduction, contribute to waking-induced impairments of attentional processes, whereas additional mechanisms must be involved in higher-order cognitive consequences of sleep deprivation. Future investigations should further clarify the exact types of cognitive processes affected by inappropriate sleep. This research will aid in the quest to better understand the role of different brain systems (e.g., adenosine and adenosine receptors) in regulating sleep, and sleep-related subjective state, and cognitive processes. Furthermore, it will provide more detail on the underlying mechanisms of the detrimental effects of extended wakefulness, as well as lead to the development of effective, evidence-based countermeasures against the health consequences of circadian misalignment and chronic sleep restriction.

  10. Value of adenosine infusion for infarct size determination using real-time myocardial contrast echocardiography

    da Luz Protásio

    2006-02-01

    Full Text Available Abstract Background Myocardial contrast echocardiography has been used for determination of infarct size (IS in experimental models. However, with intermittent harmonic imaging, IS seems to be underestimated immediately after reperfusion due to areas with preserved, yet dysfunctional, microvasculature. The use of exogenous vasodilators showed to be useful to unmask these infarcted areas with depressed coronary flow reserve. This study was undertaken to assess the value of adenosine for IS determination in an open-chest canine model of coronary occlusion and reperfusion, using real-time myocardial contrast echocardiography (RTMCE. Methods Nine dogs underwent 180 minutes of coronary occlusion followed by reperfusion. PESDA (Perfluorocarbon-Exposed Sonicated Dextrose Albumin was used as contrast agent. IS was determined by RTMCE before and during adenosine infusion at a rate of 140 mcg·Kg-1·min-1. Post-mortem necrotic area was determined by triphenyl-tetrazolium chloride (TTC staining. Results IS determined by RTMCE was 1.98 ± 1.30 cm2 and increased to 2.58 ± 1.53 cm2 during adenosine infusion (p = 0.004, with good correlation between measurements (r = 0.91; p 2 and showed no significant difference with IS determined by RTMCE before or during hyperemia. A slight better correlation between RTMCE and TTC measurements was observed during adenosine (r = 0.99; p Conclusion RTMCE can accurately determine IS in immediate period after acute myocardial infarction. Adenosine infusion results in a slight better detection of actual size of myocardial damage.

  11. Molecular characterization of adenosine 5'-monophosphate deaminase--the key enzyme responsible for the umami taste of nori (Porphyra yezoensis Ueda, Rhodophyta).

    Minami, Seiko; Sato, Minoru; Shiraiwa, Yoshihiro; Iwamoto, Koji

    2011-12-01

    The enzyme adenosine 5'-monophosphate deaminase (AMPD, EC 3.5.4.6) catalyzes the conversion of adenosine 5'-monophosphate to inosine 5'-mononucleotide (IMP). IMP is generally known as the compound responsible for the umami taste of the edible red alga Porphyra yezoensis Ueda that is known in Japan as nori. Therefore, we suspect that AMPD plays a key role in providing a favorable nori taste. In this study, we undertake the molecular characterization of nori-derived AMPD. The nori AMPD protein has a molecular mass of 55 kDa as estimated from both gel filtration and sodium dodecyl sulfate polyacrylamide gel electrophoresis. The calculated molecular mass from the amino acid sequence deduced from cDNA is 57.1 kDa. The isoelectric point is 5.71. The coding region of AMPD consists of 1,566 bp encoding 522 amino acids and possesses a transmembrane domain and two N-glycosylation sites. The sequence identity of nori AMPD in human and yeast AMPDs was found to be less than 50% and 20% in DNA and amino acid sequences, respectively. Proline in the conserved motif of [SA]-[LIVM]-[NGS]-[STA]-D-D-P was found to be converted to glutamate. These results indicate that nori AMPD is a novel type of AMPD.

  12. Role of Adenosine A2A Receptors in Modulating Synaptic Functions and Brain Levels of BDNF: a Possible Key Mechanism in the Pathophysiology of Huntington's Disease

    Maria Teresa Tebano

    2010-01-01

    Full Text Available In the last few years, accumulating evidence has shown the existence of an important cross-talk between adenosine A2A receptors (A2ARs and brain-derived neurotrophic factor (BDNF. Not only are A2ARs involved in the mechanism of transactivation of BDNF receptor TrkB, they also modulate the effect of BDNF on synaptic transmission, playing a facilitatory and permissive role. The cAMP-PKA pathway, the main transduction system operated by A2ARs, is involved in such effects. Furthermore, a basal tonus of A2ARs is required to allow the regulation of BDNF physiological levels in the brain, as demonstrated by the reduced protein levels measured in A2ARs KO mice. The crucial role of adenosine A2ARs in the maintenance of synaptic functions and BDNF levels will be reviewed here and discussed in the light of possible implications for Huntington's disease therapy, in which a joint impairment of BDNF and A2ARs seems to play a pathogenetic role.

  13. Electroacupuncture Attenuates CFA-induced Inflammatory Pain by suppressing Nav1.8 through S100B, TRPV1, Opioid, and Adenosine Pathways in Mice

    Liao, Hsien-Yin; Hsieh, Ching-Liang; Huang, Chun-Ping; Lin, Yi-Wen

    2017-01-01

    Pain is associated with several conditions, such as inflammation, that result from altered peripheral nerve properties. Electroacupuncture (EA) is a common Chinese clinical medical technology used for pain management. Using an inflammatory pain mouse model, we investigated the effects of EA on the regulation of neurons, microglia, and related molecules. Complete Freund’s adjuvant (CFA) injections produced a significant mechanical and thermal hyperalgesia that was reversed by EA or a transient receptor potential V1 (TRPV1) gene deletion. The expression of the astrocytic marker glial fibrillary acidic protein (GFAP), the microglial marker Iba-1, S100B, receptor for advanced glycation end-products (RAGE), TRPV1, and other related molecules was dramatically increased in the dorsal root ganglion (DRG) and spinal cord dorsal horn (SCDH) of CFA-treated mice. This effect was reversed by EA and TRPV1 gene deletion. In addition, endomorphin (EM) and N6-cyclopentyladenosine (CPA) administration reliably reduced mechanical and thermal hyperalgesia, thereby suggesting the involvement of opioid and adenosine receptors. Furthermore, blocking of opioid and adenosine A1 receptors reversed the analgesic effects of EA. Our study illustrates the substantial therapeutic effects of EA against inflammatory pain and provides a novel and detailed mechanism underlying EA-mediated analgesia via neuronal and non-neuronal pathways. PMID:28211895

  14. Adenosine stimulates the migration of human endothelial progenitor cells. Role of CXCR4 and microRNA-150.

    Magali Rolland-Turner

    Full Text Available BACKGROUND: Administration of endothelial progenitor cells (EPC represents a promising option to regenerate the heart after myocardial infarction, but is limited because of low recruitment and engraftment in the myocardium. Mobilization and migration of EPC are mainly controlled by stromal cell-derived factor 1α (SDF-1α and its receptor CXCR4. We hypothesized that adenosine, a cardioprotective molecule, may improve the recruitment of EPC to the heart. METHODS: EPC were obtained from peripheral blood mononuclear cells of healthy volunteers. Expression of chemokines and their receptors was evaluated using microarrays, quantitative PCR, and flow cytometry. A Boyden chamber assay was used to assess chemotaxis. Recruitment of EPC to the infarcted heart was evaluated in rats after permanent occlusion of the left anterior descending coronary artery. RESULTS: Microarray analysis revealed that adenosine modulates the expression of several members of the chemokine family in EPC. Among these, CXCR4 was up-regulated by adenosine, and this result was confirmed by quantitative PCR (3-fold increase, P<0.001. CXCR4 expression at the cell surface was also increased. This effect involved the A(2B receptor. Pretreatment of EPC with adenosine amplified their migration towards recombinant SDF-1α or conditioned medium from cardiac fibroblasts. Both effects were abolished by CXCR4 blocking antibodies. Adenosine also increased CXCR4 under ischemic conditions, and decreased miR-150 expression. Binding of miR-150 to the 3' untranslated region of CXCR4 was verified by luciferase assay. Addition of pre-miR-150 blunted the effect of adenosine on CXCR4. Administration of adenosine to rats after induction of myocardial infarction stimulated EPC recruitment to the heart and enhanced angiogenesis. CONCLUSION: Adenosine increases the migration of EPC. The mechanism involves A(2B receptor activation, decreased expression of miR-150 and increased expression of CXCR4. These

  15. Adenosine triphosphate-dependent copper transport in human liver

    vandenBerg, GJ; Wolters, H; Veld, GI; Slooff, MJH; Heymans, GSA; Kuipers, F; Vonk, RJ

    1996-01-01

    Background/Aim: The recent cloning and sequencing of the Wilson disease gene indicates that hepatic copper (Cu) transport is mediated by a P-type ATPase. The location of this Cu-transporting protein within the hepatocyte is not known; in view of its proposed function and current concepts of hepatic

  16. Growth inhibitory effect and apoptosis induced by extracellular ATP and adenosine on human gastric carcinoma cells: involvement of intracellular uptake of adenosine

    Ming-xia WANG; Lei-ming REN

    2006-01-01

    Aim: To study the growth inhibitory and apoptotic effects of adenosine triphosphate (ATP) and adenosine (ADO) on human gastric carcinoma (HGC)-27 cells in vitro and the mechanisms related to the actions of ATP and ADO. Methods: MTT assay was used to determine the reduction of cell viability. The morphological changes of HGC-27 cells induced by ATP or ADO were observed under fluorescence light microscope by acridine orange/ethidium bromide double-stained cells. The internucleosomal fragmentation of genomic DNA was detected by agarose gel electrophoresis. The apoptotic rate and cell-cycle analysis after treatment with ATP or ADO was determined by flow cytometry. Results: ATP, ADO and the intermediate metabolites, ADP and AMP, and the agonist of purinergic receptors, reduced cell viability of HGC-27 cells at doses of 0.3 and 1.0 mmol·L-1. The distribution of cell cycle phase and proliferation index (PI) value of HGC-27 cells changed when exposed to ATP or ADO at the concentrations of 0.1,0.3 and 1 mmol/L for 48 h. ATP and ADO both altered the distribution of cell cycle phase via Go/G1-phase arrest and significantly decreased PI value. Under light microscope, the tumor cells exposed to 0.3 mmol·L-1 ATP or ADO displayed morphological changes of apoptosis; a ladder-like pattern of DNA fragmentation obtained from HGC-27 cells treated with 0.1-1 mmol·L-1 ATP or ADO appeared in agarose gel electrophoresis; ATP and ADO induced the apoptosis of HGC-27 cells in a dose-dependent manner at concentrations between 0.03-1 mmol·L-1. The maximum apoptotic rate of HGC-27 cells exposed to ATP or ADO for 48 h was 13.53% or 15.9%, respectively. HGC-27 cell death induced by ATP or ADO was significantly inhibited by dipy-ridamole (10 mmol·L-1), an inhibitor of adenosine transporter, but was not affected by aminophylline, a broad inhibitor of PI receptors and pyridoxal-phosphate-6-azophenyl-2, 4-disulphonic acid tetrasodium salt (30 nmol·L-1), a non-selective antagonist of P2

  17. Glucocorticoid Regulation of Rat Renal Sodium Potassium Adenosine Triphosphatase

    1990-03-29

    response is not mediated by de novo protein synthesis but is secondary to enhanced sodium influx. The osmotic diuresis seen in uncontrolled...mediated increase in renal NaK-ATPase activity. The administration of anti-insulin serum caused a brisk natriuresis in control rat kidneys while having...hydrocortisone on water diuresis and renal function in man. J. Clin. Invest. 36: 767-779, 1957. Rane, S. and A. Aperia. Ontogeny of Na-K-ATPase

  18. Seed specific expression and analysis of recombinant human adenosine deaminase (hADA) in three host plant species.

    Doshi, Ketan M; Loukanina, Natalia N; Polowick, Patricia L; Holbrook, Larry A

    2016-10-01

    The plant seed is a leading platform amongst plant-based storage systems for the production of recombinant proteins. In this study, we compared the activity of human adenosine deaminase (hADA) expressed in transgenic seeds of three different plant species: pea (Pisum sativum L.), Nicotiana benthamiana L. and tarwi (Lupinus mutabilis Sweet). All three species were transformed with the same expression vector containing the hADA gene driven by the seed-specific promoter LegA2 with an apoplast targeting pinII signal peptide. During the study, several independent transgenic lines were generated and screened from each plant species and only lines with a single copy of the gene of interest were used for hADA expression analysis. A stable transgenic canola line expressing the ADA protein, under the control of 35S constitutive promoter was used as both as a positive control and for comparative study with the seed specific promoter. Significant differences were detected in the expression of hADA. The highest activity of the hADA enzyme (Units/g seed) was reported in tarwi (4.26 U/g) followed by pea (3.23 U/g) and Nicotiana benthamiana (1.69 U/g). The expression of mouse ADA in canola was very low in both seed and leaf tissue compared to other host plants, confirming higher activity of seed specific promoter. Altogether, these results suggest that tarwi could be an excellent candidate for the production of valuable recombinant proteins.

  19. Large-scale functional expression of WT and truncated human adenosine A2A receptor in Pichia pastoris bioreactor cultures

    Strange Philip G

    2008-10-01

    Full Text Available Abstract Background The large-scale production of G-protein coupled receptors (GPCRs for functional and structural studies remains a challenge. Recent successes have been made in the expression of a range of GPCRs using Pichia pastoris as an expression host. P. pastoris has a number of advantages over other expression systems including ability to post-translationally modify expressed proteins, relative low cost for production and ability to grow to very high cell densities. Several previous studies have described the expression of GPCRs in P. pastoris using shaker flasks, which allow culturing of small volumes (500 ml with moderate cell densities (OD600 ~15. The use of bioreactors, which allow straightforward culturing of large volumes, together with optimal control of growth parameters including pH and dissolved oxygen to maximise cell densities and expression of the target receptors, are an attractive alternative. The aim of this study was to compare the levels of expression of the human Adenosine 2A receptor (A2AR in P. pastoris under control of a methanol-inducible promoter in both flask and bioreactor cultures. Results Bioreactor cultures yielded an approximately five times increase in cell density (OD600 ~75 compared to flask cultures prior to induction and a doubling in functional expression level per mg of membrane protein, representing a significant optimisation. Furthermore, analysis of a C-terminally truncated A2AR, terminating at residue V334 yielded the highest levels (200 pmol/mg so far reported for expression of this receptor in P. pastoris. This truncated form of the receptor was also revealed to be resistant to C-terminal degradation in contrast to the WT A2AR, and therefore more suitable for further functional and structural studies. Conclusion Large-scale expression of the A2AR in P. pastoris bioreactor cultures results in significant increases in functional expression compared to traditional flask cultures.

  20. Limits of ligand selectivity from docking to models: in silico screening for A(1 adenosine receptor antagonists.

    Peter Kolb

    Full Text Available G protein-coupled receptors (GPCRs are attractive targets for pharmaceutical research. With the recent determination of several GPCR X-ray structures, the applicability of structure-based computational methods for ligand identification, such as docking, has increased. Yet, as only about 1% of GPCRs have a known structure, receptor homology modeling remains necessary. In order to investigate the usability of homology models and the inherent selectivity of a particular model in relation to close homologs, we constructed multiple homology models for the A(1 adenosine receptor (A(1AR and docked ∼2.2 M lead-like compounds. High-ranking molecules were tested on the A(1AR as well as the close homologs A(2AAR and A(3AR. While the screen yielded numerous potent and novel ligands (hit rate 21% and highest affinity of 400 nM, it delivered few selective compounds. Moreover, most compounds appeared in the top ranks of only one model. These findings have implications for future screens.

  1. The A3 adenosine receptor (A3AR): therapeutic target and predictive biological marker in rheumatoid arthritis.

    Fishman, Pnina; Cohen, Shira

    2016-09-01

    The Gi protein-associated A3 adenosine receptor (A3AR) is over-expressed in inflammatory cells, and this high expression is also reflected in the peripheral blood mononuclear cells of patients with autoimmune inflammatory diseases such as rheumatoid arthritis, psoriasis, and Crohn's disease. CF101, a selective agonist with high affinity to the A3AR, is known to induce robust anti-inflammatory effect in experimental animal models of adjuvant-, collagen-, and tropomyosin-induced arthritis. The effect is mediated via a definitive molecular mechanism entailing deregulation of the nuclear factor-κB (NF-κB) and the Wnt signal transduction pathways resulting in apoptosis of inflammatory cells. CF101 was found to be safe and well tolerated in all preclinical, phase I, and phase II human clinical studies. In two phase II clinical studies where CF101 was administered to rheumatoid arthritis (RA) patients as a stand-alone drug, a significant anti-rheumatic effect and a direct significant correlation were found between receptor expression at baseline and patients' response to the drug, suggesting that A3AR may be utilized as a predictive biomarker. The A3AR is a promising therapeutic target in rheumatoid arthritis and can be used also as a biological marker to predict patients' response to CF101. This is a unique type of a personalized medicine approach which may pave the way for a safe and efficacious treatment for this patient population.

  2. Ratiometric bioluminescence indicators for monitoring cyclic adenosine 3',5'-monophosphate in live cells based on luciferase-fragment complementation.

    Takeuchi, Masaki; Nagaoka, Yasutaka; Yamada, Toshimichi; Takakura, Hideo; Ozawa, Takeaki

    2010-11-15

    Bioluminescent indicators for cyclic 3',5'-monophosphate AMP (cAMP) are powerful tools for noninvasive detection with high sensitivity. However, the absolute photon counts are affected substantially by adenosine 5'-triphosphate (ATP) and d-luciferin concentrations, limiting temporal analysis in live cells. This report describes a genetically encoded bioluminescent indicator for detecting intracellular cAMP based on complementation of split fragments of two-color luciferase mutants originated from click beetles. A cAMP binding domain of protein kinase A was connected with an engineered carboxy-terminal fragment of luciferase, of which ends were connected with amino-terminal fragments of green luciferase and red luciferase. We demonstrated that the ratio of green to red bioluminescence intensities was less influenced by the changes of ATP and d-luciferin concentrations. We also showed an applicability of the bioluminescent indicator for time-course and quantitative assessments of intracellular cAMP in living cells and mice. The bioluminescent indicator will enable quantitative analysis and imaging of spatiotemporal dynamics of cAMP in opaque and autofluorescent living subjects.

  3. Comparison of adenosine stress and dobutamine stress by real-time myocardial contrast echocardiography in detecting myocardium ischemia in dogs

    XING Yan-qiu; HOU Bo-wen; ZHANG Yun; LIU Xiang-qun; GAO Hai-qing

    2009-01-01

    spectively. Conclusions Even small distal infarcts can be detected by RTPI; peri-infarct ischemia can be accurately recognized by RTPI during stress; adenosine and dobutamine stress appear equally reliable in the RTPI evaluation of peri-infarct ischemia.

  4. Regulation of adenosine triphosphate-sensitive potassium channels suppresses the toxic effects of amyloid-beta peptide (25-35)

    Min Kong; Maowen Ba; Hui Liang; Peng Shao; Tianxia Yu; Ying Wang

    2013-01-01

    In this study, we treated PC12 cells with 0-20 μM amyloid-β peptide (25-35) for 24 hours to induce cytotoxicity, and found that 5-20 μM amyloid-β peptide (25-35) decreased PC12 cell viability, but adenosine triphosphate-sensitive potassium channel activator diazoxide suppressed the decrease reactive oxygen species levels. These protective effects were reversed by the selective mitochondrial adenosine triphosphate-sensitive potassium channel blocker 5-hydroxydecanoate. An inducible nitric oxide synthase inhibitor, Nω-nitro-L-arginine, also protected PC12 cells from intracellular reactive oxygen species levels. However, the H2O2-degrading enzyme catalase could that the increases in both mitochondrial membrane potential and reactive oxygen species levels adenosine triphosphate-sensitive potassium channels and nitric oxide. Regulation of adenosine triphosphate-sensitive potassium channels suppresses PC12 cell cytotoxicity induced by amyloid-β

  5. Ischemic preconditioning protects post-ischemic renal function in anesthetized dogs: role of adenosine and adenine nucleotides

    Fan-zhu LI; Shoji KIMURA; Akira NISHIYAMA; Matlubur RAHMAN; Guo-xing ZHANG; Youichi ABE

    2005-01-01

    Aim: To investigate the effects of renal ischemic preconditioning (IPC) on both renal hemodynamics and the renal interstitial concentrations of adenosine and adenine nucleotides induced by ischemia-reperfusion injury.Methods: Renal hemodynamics responses to ischemia-reperfusion injury in mongrel dog models were determined with or without multiple brief renal ischemic preconditioning treatments, as well as the adenosine A1 receptor antagonist (KW-3902),respectively.The renal interstitial concentrations of adenosine and adenine nucleotides in response to ischemia-reperfusion injury, either following 1-3 cycles of IPC or not, were measured simultaneously using microdialysis sampling technology.Results: One 10-min IPC, adenosine A1 receptor antagonist (KW3902) also shortened the recovery time of renal blood flow (RBF) and urine flow (UF), as well as mean blood pressure (BP).Advanced renal IPC attenuated the increment of adenosine and adenine nucleotides, as well as recovery time during the 60-min reperfusion which followed the 60-min renal ischemia.All of these recovery times were dependent on the cycles of 10-min IPC.The renal interstitial concentrations of adenosine and adenine nucleotides increased and decreased during renal ischemia and reperfusion, respectively.Conclusion: A significant relativity in dog models exists between the cycles of 10-min renal IPC and the recovery time of BP, UF, and RBF during the 60-min renal reperfusion following 60-min renal ischemia, respectively.Renal IPC can protect against ischemiareperfusion injury and the predominant effect of endogenous adenosine induced by prolonged renal ischemia; renal adenosine A1 receptor activation during the renal ischemia-reperfusion injury is detrimental to renal function.

  6. Activation of NTS A(1) adenosine receptors inhibits regional sympathetic responses evoked by activation of cardiopulmonary chemoreflex.

    Ichinose, Tomoko K; Minic, Zeljka; Li, Cailian; O'Leary, Donal S; Scislo, Tadeusz J

    2012-09-01

    Previously we have shown that adenosine operating via the A(1) receptor subtype may inhibit glutamatergic transmission in the baroreflex arc within the nucleus of the solitary tract (NTS) and differentially increase renal (RSNA), preganglionic adrenal (pre-ASNA), and lumbar (LSNA) sympathetic nerve activity (ASNA>RSNA≥LSNA). Since the cardiopulmonary chemoreflex and the arterial baroreflex are mediated via similar medullary pathways, and glutamate is a primary transmitter in both pathways, it is likely that adenosine operating via A(1) receptors in the NTS may differentially inhibit regional sympathetic responses evoked by activation of cardiopulmonary chemoreceptors. Therefore, in urethane-chloralose-anesthetized rats (n = 37) we compared regional sympathoinhibition evoked by the cardiopulmonary chemoreflex (activated with right atrial injections of serotonin 5HT(3) receptor agonist phenylbiguanide, PBG, 1-8 μg/kg) before and after selective stimulation of NTS A(1) adenosine receptors [microinjections of N(6)-cyclopentyl adenosine (CPA), 0.033-330 pmol/50 nl]. Activation of cardiopulmonary chemoreceptors evoked differential, dose-dependent sympathoinhibition (RSNA>ASNA>LSNA), and decreases in arterial pressure and heart rate. These differential sympathetic responses were uniformly attenuated in dose-dependent manner by microinjections of CPA into the NTS. Volume control (n = 11) and blockade of adenosine receptor subtypes in the NTS via 8-(p-sulfophenyl)theophylline (8-SPT, 1 nmol in 100 nl) (n = 9) did not affect the reflex responses. We conclude that activation of NTS A(1) adenosine receptors uniformly inhibits neural and cardiovascular cardiopulmonary chemoreflex responses. A(1) adenosine receptors have no tonic modulatory effect on this reflex under normal conditions. However, when adenosine is released into the NTS (i.e., during stress or severe hypotension/ischemia), it may serve as negative feedback regulator for depressor and sympathoinhibitory reflexes

  7. Sleep-Wake Regulation and Its Impact on Working Memory Performance: The Role of Adenosine

    Carolin Franziska Reichert

    2016-02-01

    Full Text Available The sleep-wake cycle is regulated by a fine-tuned interplay between sleep-homeostatic and circadian mechanisms. Compelling evidence suggests that adenosine plays an important role in mediating the increase of homeostatic sleep pressure during time spent awake and its decrease during sleep. Here, we summarize evidence that adenosinergic mechanisms regulate not only the dynamic of sleep pressure, but are also implicated in the interaction of homeostatic and circadian processes. We review how this interaction becomes evident at several levels, including electrophysiological data, neuroimaging studies and behavioral observations. Regarding complex human behavior, we particularly focus on sleep-wake regulatory influences on working memory performance and underlying brain activity, with a specific emphasis on the role of adenosine in this interplay. We conclude that a change in adenosinergic mechanisms, whether exogenous or endogenous, does not only impact on sleep-homeostatic processes, but also interferes with the circadian timing system.

  8. Synthesis and Pharmacological Evaluation of Modified Adenosines Joined to Mono-Functional Platinum Moieties

    Stefano D'Errico

    2014-07-01

    Full Text Available The synthesis of four novel platinum complexes, bearing N6-(6-amino-hexyladenosine or a 1,6-di(adenosin-N6-yl-hexane respectively, as ligands of mono-functional cisplatin or monochloro(ethylendiamineplatinum(II, is reported. The chemistry exploits the high affinity of the charged platinum centres towards the N7 position of the adenosine base system and a primary amine of an alkyl chain installed on the C6 position of the purine. The cytotoxic behaviour of the synthesized complexes has been studied in A549 adenocarcinomic human alveolar basal epithelial and MCF7 human breast adenocarcinomic cancer cell lines, in order to investigate their effects on cell viability and proliferation.

  9. Platelet aggregation and serum adenosine deaminase (ADA) activity in pregnancy associated with diabetes, hypertension and HIV.

    Leal, Claudio A M; Leal, Daniela B R; Adefegha, Stephen A; Morsch, Vera M; da Silva, José E P; Rezer, João F P; Schrekker, Clarissa M L; Abdalla, Faida H; Schetinger, Maria R C

    2016-07-01

    Platelet aggregation and adenosine deaminase (ADA) activity were evaluated in pregnant women living with some disease conditions including hypertension, diabetes mellitus and human immunodeficiency virus infection. The subject population is consisted of 15 non-pregnant healthy women [control group (CG)], 15 women with normal pregnancy (NP), 7 women with hypertensive pregnancy (HP), 10 women with gestational diabetes mellitus (GDM) and 12 women with human immunodeficiency virus-infected pregnancy (HIP) groups. The aggregation of platelets was checked using an optical aggregometer, and serum ADA activity was determined using the colorimetric method. After the addition of 5 µM of agonist adenosine diphosphate, the percentage of platelet aggregation was significantly (p pregnancy and pregnancy-associated diseases suggest that platelet aggregation and ADA activity could serve as peripheral markers for the development of effective therapy in the maintenance of homeostasis and some inflammatory process in these pathophysiological conditions. Copyright © 2016 John Wiley & Sons, Ltd.

  10. CD73-Generated Adenosine: Orchestrating the Tumor-Stroma Interplay to Promote Cancer Growth

    Bertrand Allard

    2012-01-01

    Full Text Available Despite the coming of age of cancer immunotherapy, clinical benefits are still modest. An important barrier to successful cancer immunotherapy is that tumors employ a number of mechanisms to facilitate immune escape, including the production of anti-inflammatory cytokines, the recruitment of regulatory immune subsets, and the production of immunosuppressive metabolites. Significant therapeutic opportunity exists in targeting these immunosuppressive pathways. One such immunosuppressive pathway is the production of extracellular adenosine by CD73, an ectonucleotidase overexpressed in various types of cancer. We hereafter review the biology of CD73 and its role in cancer progression and metastasis. We describe the role of extracellular adenosine in promoting tumor growth through paracrine and autocrine action on tumor cells, endothelial cells, and immune cells.

  11. Interaction of Divalent Metal Ions with the Adenosine Triphosphate Measured Using Nuclear Magnetic Resonance

    2000-01-01

    The interaction of adenosine triphosphate with divalent metal ions is important in biochemical functions. The effects of pH and metal ions Mg2+, Ca2+, Zn2+, Mn2+, and Co2+ on the chemical shift of the phosphate group of ATP have been studied using Nuclear Magnetic Resonance. The chemical shift of the β-phosphate of ATP is the most sensitive to pH. Ca2+ and Mg2+ bind with the α- and β-phosphate groups of ATP. Zn2+ binds to the adenosine ring hydrogen as well as to phosphate. The paramagnetic ions Mn2+ and Co2+ do not cause chemical shifts of the phosphate or proton peak. Mn2+ and Co2+ broaden the resonance peak only.

  12. Adenosine kinase deficiency with neurodevelopemental delay and recurrent hepatic dysfunction: A case report

    Shakiba, Marjan; Mahjoub, Fatemeh; Fazilaty, Hassan; Rezagholizadeh, Fereshteh; Shakiba, Arghavan; Ziadlou, Maryam; Gahl, William A.; Behnam, Babak

    2016-01-01

    Hypermethioninemia may be benign, present as a nonspecific sign of nongenetic conditions such as liver failure and prematurity, or a severe, progressive inborn error of metabolism. Genetic causes of hypermethioninemia include mitochondrial depletion syndromes caused by mutations in the MPV17 and DGUOK genes and deficiencies of cystathionine β-synthase, methionine adenosyltransferase types I and III, glycine N-methyltransferase, S-adenosylhomocysteine hydrolase, citrin, fumarylacetoacetate hydrolase, and adenosine kinase. Here we present a 3-year old girl with a history of poor feeding, irritability, respiratory infections, cholestasis, congenital heart disease, neurodevelopmental delay, hypotonia, sparse hair, facial dysmorphisms, liver dysfunction, severe hypermethioninemia and mild homocystinemia. Genetic analysis of the adenosine kinase (ADK) gene revealed a previously unreported variant (c.479–480 GA>TG) resulting in a stop codon (p.E160X) in ADK. A methionine-restricted diet normalized the liver function test results and improved her hypotonia. PMID:27500280

  13. Differential effects of the adenosine A1 receptor agonist adenosine amine congener on renal, femoral and carotid vascular conductance in preterm fetal sheep.

    Booth, Lindsea C; Tummers, Leonie; Jensen, Ellen C; Barrett, Carolyn J; Malpas, Simon C; Gunn, Alistair J; Bennet, Laura

    2008-11-01

    1. Adenosine A(1) receptor activation is critical for endogenous neuroprotection from hypoxia-ischaemia, raising the possibility that treatment with A(1) receptor agonists may be an effective physiological protection strategy for vulnerable preterm infants. However, the A(1) receptor can mediate unwanted systemic effects, including vasoconstriction of the afferent glomerular arteriole. There is limited information on whether this occurs at doses that improve cerebral perfusion in the immature brain. 2. Therefore, in the present study, we examined whether infusion of the selective A(1) receptor agonist adenosine amine congener (ADAC) is associated with reduced renal perfusion in chronically instrumented preterm (0.7 gestation) fetal sheep. In the present study, ADAC was given in successive doses of 2.5, 5.0 and 15.0 microg, 45 min apart. 3. Treatment with ADAC was associated with a marked reduction in renal vascular conductance (and blood flow), whereas carotid conductance was increased and there was no significant effect on femoral conductance. In contrast with the stable effects of increasing ADAC dose on vascular conductance, there was a significant dose-related fall in fetal heart rate and blood pressure. 4. In conclusion, these short-term data support the concern that A(1) receptor agonist infusion can selectively impair renal perfusion, even at low doses.

  14. Efficient retrovirus-mediated transfer and expression of a human adenosine deaminase gene in diploid skin fibroblasts from an adenosine deaminase-deficient human

    Palmer, T.D.; Hock, R.A.; Osborne, W.R.A.; Miller, A.D.

    1987-02-01

    Skin fibroblasts might be considered suitable recipients for therapeutic genes to cure several human genetic diseases; however, these cells are resistant to gene transfer by most methods. The authors studied the ability of retroviral vectors to transfer genes into normal human diploid skin fibroblasts. Retroviruses carrying genes for neomycin or hygromycin B resistance conferred drug resistance to greater than 50% of the human fibroblasts after a single exposure to virus-containing medium. This represents at least a 500-fold increase in efficiency over other methods. Transfer was achieved in the absence of helper virus by using amphotropic retrovirus-packaging cells. A retrovirus vector containing a human adenosine deaminase (ADA) cDNA was constructed and used to infect ADA/sup -/ fibroblasts from a patient with ADA deficiency. The infected cells produced 12-fold more ADA enzyme than fibroblasts from normal individuals and were able to rapidly metabolize exogenous deoxyadenosine and adenosine, metabolites that accumulate in plasma in ADA-deficient patients and are responsible for the severe combined immunodeficiency in these patients. These experiments indicate the potential of retrovirus-mediated gene transfer into human fibroblasts for gene therapy.

  15. An enzyme-free strategy for ultrasensitive detection of adenosine using a multipurpose aptamer probe and malachite green.

    Zhao, Hui; Wang, Yong-Sheng; Tang, Xian; Zhou, Bin; Xue, Jin-Hua; Liu, Hui; Liu, Shan-Du; Cao, Jin-Xiu; Li, Ming-Hui; Chen, Si-Han

    2015-08-01

    We report on an enzyme-free and label-free strategy for the ultrasensitive determination of adenosine. A novel multipurpose adenosine aptamer (MAAP) is designed, which serves as an effective target recognition probe and a capture probe for malachite green. In the presence of adenosine, the conformation of the MAAP is converted from a hairpin structure to a G-quadruplex. Upon addition of malachite green into this solution, a noticeable enhancement of resonance light scattering was observed. The signal response is directly proportional to the concentration of adenosine ranging from 75 pM to 2.2 nM with a detection limit of 23 pM, which was 100-10,000 folds lower than those obtained by previous reported methods. Moreover, this strategy has been applied successfully for detecting adenosine in human urine and blood samples, further proving its reliability. The mechanism of adenosine inducing MAAP to form a G-quadruplex was demonstrated by a series of control experiments. Such a MAAP probe can also be used to other strategies such as fluorescence or spectrophotometric ones. We suppose that this strategy can be expanded to develop a universal analytical platform for various target molecules in the biomedical field and clinical diagnosis.

  16. Effect of 2-(6-cyano-1-hexyn-1-yl)adenosine on ocular blood flow in rabbits.

    Konno, Takashi; Uchibori, Takehiro; Nagai, Akihiko; Kogi, Kentaro; Nakahata, Norimichi

    2007-02-27

    Previously, we reported that a relatively selective adenosine A(2A) receptor agonist 2-(6-cyano-1-hexyn-1-yl)adenosine (2-CN-Ado) elicited ocular hypotension in rabbits (Journal of Pharmacological Sciences 2005;97:501-509). In the present study, we investigated the effect of 2-CN-Ado on ocular blood flow in rabbit eyes. An intravitreal injection of 2-CN-Ado increased ocular blood flow, measured by a non-contact laser flowmeter. 2-CN-Ado-induced increase in ocular blood flow was accompanied with the retinal vasodilation. The increase in ocular blood flow was inhibited by an adenosine A(2A) receptor antagonist 1,3,7-trimethyl-8-(3-chlorostyryl)xanthine, but not by an adenosine A(2B) receptor antagonist alloxazine or an adenosine A(1) receptor antagonist 8-cyclopentyl-1,3-dipropylxanthine. The repetitive applications of topical 2-CN-Ado twice a day for 7 days produced a persistent increase in ocular blood flow with ocular hypotension. These results suggest that 2-CN-Ado increases the ocular blood flow mainly via adenosine A(2A) receptor, and that the topical application of 2-CN-Ado for several days not only increases the ocular blood flow but also prolong ocular hypotension, indicating that 2-CN-Ado may be a useful lead compound for the treatment of ischemic retinal diseases such as glaucoma.

  17. Value of the adenosine test for diagnosis of dual AV nodal physiology in patients with AV nodal reentrant tachycardia

    周斌全; 胡申江; 鲁端; 王建安

    2002-01-01

    Objectives: This study was aimed at assessing the value of the adenosine test for noninvasive diagnosis of dual AV nodal physiology(DAVNP) in patients with AV nodal reentrant tachycardia (AVNRT). Methods: 53 patients with paroxysmal supraventricular tachycardia (PSVT) were given incremental doses of adenosine intravenously during sinus rhythm before electrophysiological study. The adenosine test was repeated on a subset of 18 patients with AVNRT after radiofrequency catheter ablation. Results: Sudden increments of PR interval of more than 60 msec between two consecutive beats were observed in 26(83.9%) of 31 patients with typical AVNRT and 2 (9.1%) of 22 patients with AVRT and AT (P<0.01). The maximal PR increment between 2 consecutive beats in the AVNRT group(105±45ms) was significantly greater than that in the AVRT and AT group (20±13ms) (P<0.01).In postablation adenosine test, DAVNP was eliminated in all 8 patients who underwent slow pathway abolition that EPS showed the slow pathway disappeared and 4 of 10 patients who underwent slow pathway modification that EPS showed the slow pathway persisted. Six of 10 patients who exhibited persistent duality showed a marked reduction in the number of beats conducted in the slow pathway after adenosine injection(P<0.01).Conclusions: Administration of adenosine during sinus rhythm may be a useful bedside test for diagnosis of DAVNP in high percentage of patients with typical AVNRT and additionally for evaluating the effects of radiofrequency ablation.

  18. Microcontroller-assisted compensation of adenosine triphosphate levels: instrument and method development.

    Hu, Jie-Bi; Chen, Ting-Ru; Chen, Yu-Chie; Urban, Pawel L

    2015-01-30

    In order to ascertain optimum conditions for biocatalytic processes carried out in vitro, we have designed a bio-opto-electronic system which ensures real-time compensation for depletion of adenosine triphosphate (ATP) in reactions involving transfer of phosphate groups. The system covers ATP concentration range of 2-48 μM. The report demonstrates feasibility of the device operation using apyrase as the ATP-depleting enzyme.

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

    2008-11-01

    not temperate, conditions after administration of a dopamine reuptake inhib- itor in humans (52) and improved thermoregulation in rats after...acute nutritional adenosine antagonist (caffeine and quercetin) administration on endurance exercise performance in the heat. An underlying assumption...both achieved with a small (0.6 mg/kg) intracerebroventricular dose of caffeine, while the same intraperitoneal dose had no effects. It remains

  20. [Concentration of prostaglandins and cyclic adenosine-3',5'-monophosphate in the tissues of rats].

    Komissarenko, V P; Slavnov, V N; Epsheĭn, E V; Malinkovich, V D

    1977-04-01

    The content of prostaglandines (PG) and cyclic 3',5'-adenosine monphosphate (cAMP) was investigated in rat tissues by the radioisotopic method of competitive binding. Maximum quantities of both PG and cAMP were revealed in the same most actively functioning organs: the brain, incretory glands, small intestine. Fatty tissue showed minimum quantities of these substances. Results indicate a close functional relationship between the PG synthesis and adenylatecyclase activity in the body tissues.

  1. Development of gene therapy: potential in severe combined immunodeficiency due to adenosine deaminase deficiency.

    Montiel-Equihua, C. A.; Thrasher, A. J.; Gaspar, H B

    2009-01-01

    The history of stem cell gene therapy is strongly linked to the development of gene therapy for severe combined immunodeficiencies (SCID) and especially adenosine deaminase (ADA)-deficient SCID. Here we discuss the developments achieved in over two decades of clinical and laboratory research that led to the establishment of a protocol for the autologous transplant of retroviral vector-mediated gene-modified hematopoietic stem cells, which has proved to be both successful and, to date, safe. P...

  2. Adenosine Preconditioning versus Ischemic Preconditioning in Patients undergoing Off-Pump Coronary Artery Bypass (OPCAB

    SeyedKhalil Forouzannia

    2015-10-01

    Full Text Available Background: During off-pump coronary artery bypass (OPCAB, the heart is subjected to ischemic and reperfusion injury. Preconditioning is a mechanism that permits the heart to tolerate myocardial ischemia. The aim of this study was to compare the effects of Adenosine preconditioning with ischemic preconditioning on the global ejection fraction (EF in patients undergoing OPCAB.Methods: In this single-blind, randomized controlled trial, sixty patients undergoing OPCAB were allocated into three equally-numbered groups through simple randomization: Adenosine group, ischemic group, and control group. The patients in the Adenosine group received an infusion of Adenosine. In the ischemic group, ischemic preconditioning was induced by the temporary occlusion of the left anterior descending coronary artery twice for a 2-minute period, followed by 3-minute reperfusion before bypass grafting of the first coronary vessel. The control group received an intravenous infusion of 0.9% saline. Blood samples at different times were sent for the measurement of creatine kinase isoenzyme MB (CK-MB and cardiac troponin I (cTnI. We also recorded electrocardiographic indices and clinical parameters, including postoperative use of inotropic drugs and preoperative and postoperative EF.Results: History of myocardial infarction, hyperlipidemia, diabetes mellitus, kidney disease, preoperative arrhythmias, and utilization of postoperative inotrope was the same between the three groups. The incidence of postoperative arrhythmias was not significant between the three groups. Also, there were no significant differences in preoperative and postoperative EF and the serum levels of enzymes (cTnI and CK-MB between the groups.Conclusion: Based on the findings of this study, there was no significant difference in the postoperative EF between the groups. Although the incidence of arrhythmias was higher in the ischemic preconditioning group than in the other groups, the difference

  3. Role of Adenosine Receptor A2A in Traumatic Optic Neuropathies

    2015-02-01

    functional and histological changes asso ciated with diabetic nephropathy in wild type diabetic mice but not in the A2AAR−/− diabetic mice (Awad et al...the beginning of streptozotocin induced diabetes at the age of eight weeks. This treatment , previously demonstrated to increase free adenosine levels in...and it was not affected by ABT 702 treatment Blood glucose levels were higher in diabetic mice compared with non diabetic groups and they were not

  4. Synthesis and characterization of chemically anchored adenosine with PHEMA grafted gold nanoparticles

    Bach, Long Giang; Islam, Md. Rafiqul; Jeong, Yeon Tae; Gal, Yeong Soon; Lim, Kwon Taek

    2012-01-01

    The synthesis of chemically anchored adenosine with biocompatible poly(2-hydroxylethyl methacrylate) grafted gold nanoparticles (Ado-i-PHEMA-g-AuNPs) was realized by employing a simple strategy. Disulfide-containing poly(2-hydroxylethyl methacrylate) (DT-PHEMA) was initially synthesized by atom transfer radical polymerization (ATRP). The formation of DT-PHEMA was confirmed by 1H-NMR and FT-IR. The molecular weight and molecular weight distribution were found to be 9.6 kg/mol and 1.40 from GPC analysis. DT-PHEMA was subsequently used for the synthesis of PHEMA-g-AuNPs by a grafting to protocol. The grafting of DT-PHEMA on the surface of AuNPs was confirmed by FT-IR, TGA, XPS, and EDX analyses. The particle size of the PHEMA-g-AuNPs was found to be ca. 5.0 nm from HR-TEM analysis. Boronic acid was used for functionalization of PHEMA-g-AuNPs, which was then subjected for covalent immobilization with adenosine via strong interaction between free hydroxyl groups of adenosine and boronic acid. Characterization and properties of the Ado-i-PHEMA-g-AuNPs were investigated by taking advantage from FT-IR, XPS, EDX, and UV-visible spectroscopy. The Ado-i-PHEMA-g-AuNPs nanocomposite exhibits a surface plasmon resonance peak at 586 nm which is red shifted from AuNPs (521 nm), indicating significant changes of surface property upon PHEMA-adenosine immobilization onto the surface of AuNPs.

  5. Gene therapy for severe combined immunodeficiency due to adenosine deaminase deficiency.

    Montiel-Equihua, Claudia A; Thrasher, Adrian J; Gaspar, H Bobby

    2012-02-01

    The severe combined immunodeficiency caused by the absence of adenosine deaminase (SCID-ADA) was the first monogenic disorder for which gene therapy was developed. Over 30 patients have been treated worldwide using the current protocols, and most of them have experienced clinical benefit; importantly, in the absence of any vector-related complications. In this document, we review the progress made so far in the development and establishment of gene therapy as an alternative form of treatment for ADA-SCID patients.

  6. Effects of an induced adenosine deaminase deficiency on T-cell differentiation in the rat

    Barton, R.W.

    1985-10-15

    Inherited deficiency of the enzyme adenosine deaminase (ADA) has been found in a significant proportion of patients with severe combined immunodeficiency disease and inherited defect generally characterized by a deficiency of both B and T cells. Two questions are central to understanding the pathophysiology of this disease: (1) at what stage or stages in lymphocyte development are the effects of the enzyme deficiency manifested; (2) what are the biochemical mechanisms responsible for the selective pathogenicity of the lymphoid system. We have examined the stage or stages of rat T-cell development in vivo which are affected by an induced adenosine deaminase deficiency using the ADA inhibitors, erythro-9-(2-hydroxy-3-nonyl)adenine (EHNA) and 2'-deoxycoformycin (DCF). In normal rats given daily administration of an ADA inhibitor, cortical thymocytes were markedly depleted; peripheral lymphocytes and pluripotent hemopoietic stem cells (CFU-S) all were relatively unaffected. Since a deficiency of ADA affects lymphocyte development, the regeneration of cortical and medullary thymocytes and their precursors after sublethal irradiation was used as a model of lymphoid development. By Day 5 after irradiation the thymus was reduced to 0.10-0.5% of its normal size; whereas at Days 9 and 14 the thymus was 20-40% and 60-80% regenerated, respectively. When irradiated rats were given daily parenteral injections of the ADA inhibitor plus adenosine or deoxyadenosine, thymus regeneration at Days 9 and 14 was markedly inhibited, whereas the regeneration of thymocyte precursors was essentially unaffected. Thymus regeneration was at least 40-fold lower than in rats given adenosine or deoxyadenosine alone. Virtually identical results were obtained with both ADA inhibitors, EHNA and DCF.

  7. P2X receptors regulate adenosine diphosphate release from hepatic cells.

    Chatterjee, Cynthia; Sparks, Daniel L

    2014-12-01

    Extracellular nucleotides act as paracrine regulators of cellular signaling and metabolic pathways. Adenosine polyphosphate (adenosine triphosphate (ATP) and adenosine diphosphate (ADP)) release and metabolism by human hepatic carcinoma cells was therefore evaluated. Hepatic cells maintain static nanomolar concentrations of extracellular ATP and ADP levels until stress or nutrient deprivation stimulates a rapid burst of nucleotide release. Reducing the levels of media serum or glucose has no effect on ATP levels, but stimulates ADP release by up to 10-fold. Extracellular ADP is then metabolized or degraded and media ADP levels fall to basal levels within 2-4 h. Nucleotide release from hepatic cells is stimulated by the Ca(2+) ionophore, ionomycin, and by the P2 receptor agonist, 2'3'-O-(4-benzoyl-benzoyl)-adenosine 5'-triphosphate (BzATP). Ionomycin (10 μM) has a minimal effect on ATP release, but doubles media ADP levels at 5 min. In contrast, BzATP (10-100 μM) increases both ATP and ADP levels by over 100-fold at 5 min. Ion channel purinergic receptor P2X7 and P2X4 gene silencing with small interference RNA (siRNA) and treatment with the P2X inhibitor, A438079 (100 μM), decrease ADP release from hepatic cells, but have no effect on ATP. P2X inhibitors and siRNA have no effect on BzATP-stimulated nucleotide release. ADP release from human hepatic carcinoma cells is therefore regulated by P2X receptors and intracellular Ca(2+) levels. Extracellular ADP levels increase as a consequence of a cellular stress response resulting from serum or glucose deprivation.

  8. Spectroscopy and computational studies on the interaction of octyl, dodecyl, and hexadecyl derivatives of anionic and cationic surfactants with adenosine deaminase.

    Ajloo, Davood; Mahmoodabadi, Najmeh; Ghadamgahi, Maryam; Saboury, Ali Akbar

    2016-07-01

    Effects of sodium (octyl, dodecyl, hexadecyl) sulfate and their cationic analogous on the structure of adenosine deaminase (ADA) were investigated by fluorescence and circular dichroism spectroscopy as well as molecular dynamics simulation and docking calculation. Root-mean-square derivations, radius of gyration, solvent accessible surface area, and radial distribution function were obtained. The results showed that anionic and cationic surfactants reduce protein stability. Cationic surfactants have more effect on the ADA structure in comparison with anionic surfactants. More concentration and longer surfactants are parallel to higher denaturation. Furthermore, aggregation in the presence of anionic surfactants is more than cationic surfactants. Docking data showed that longer surfactants have more interaction energy and smaller ones bound to the active site.

  9. Antihyperglycemic, antihyperlipidemic, anti-inflammatory and adenosine deaminase–lowering effects of garlic in patients with type 2 diabetes mellitus with obesity

    Kumar R

    2013-01-01

    Full Text Available Rahat Kumar,1 Simran Chhatwal,1 Sahiba Arora,2 Sita Sharma,3 Jaswinder Singh,1 Narinder Singh,1 Vikram Bhandari,1 Ashok Khurana41Department of Pharmacology, 2Department of Biochemistry, 3Department of Obstetrics and Gynecology, 4Department of Medicine, Sri Guru Ram Das Institute of Medical Sciences and Research, Amritsar, IndiaIntroduction: Type 2 diabetes mellitus is a chronic disorder characterized by chronic hyperglycemia, with long term macrovascular and microvascular complications. The treatment is lifestyle management, exercise, weight control, and antihyperglycemic drugs such as sulfonylureas, biguanides, alpha-glucosidase inhibitors, thiazolidinediones, and meglitinide. Recently, a direct association between high levels of C-reactive protein and serum adenosine deaminase levels in patients with uncontrolled diabetes with long-term complications has been seen. This study was conducted to assess the antihyperglycemic, lipid-lowering, anti-inflammatory, and improving glycemic control of garlic in type 2 diabetes patients with obesity.Materials and methods: This was an open-label, prospective, comparative study, conducted on 60 patients having type 2 diabetes mellitus and obesity. The patients were divided into two groups of 30 each, of either sex. Group 1 was given metformin tablets, 500 mg twice a day (BD/three times a day (TDS, after meals, and group 2 was given metformin tablets, 500 mg BD/TDS, after meals, along with garlic (Allium sativum capsules, 250 mg BD. Patients were routinely investigated for fasting and postprandial blood glucose, glycosylated hemoglobin (HbA1c, serum adenosine deaminase levels and lipid profile (serum cholesterol, high-density lipoprotein cholesterol, triglycerides and low-density lipoprotein cholesterol at the start of the study. Patients were followed up for 12 weeks, with monitoring of fasting and postprandial blood glucose at 2 week intervals, and monitoring of the other parameters at the end of study

  10. Electrophysiologic effects of adenosine triphosphate on rabbit sinoatrial node pace maker cells via P1 receptors

    RENLei-Ming; LIJun-Xia; SHIChen-Xia; ZHAODing

    2003-01-01

    AIM: To study the electrophysiologic effects of adenosine triphosphate (ATP) on rabbit sinoatrial node pacemakercells and the receptors related with the action of ATP. METHODS: Intracellular microelectrode method was usedto record the parameters of action potential (AP) in the rabbit sinoatrial nodes. RESULTS: ATP (0.1-3 mmol/L)decreased the rate of pacemaker firing (RPF) by 16 %-43 % and velocity of diastolic depolarization (VDD) by 33 %-67 %, increased the amplitude of AP (APA) by 6 %-9 % and maximal rate of depolarization (Vmax) by 30 %-76 %,shortened APD50 by 7 %-12 % and APD90 by 6.3 %-9 %, concentration-dependently. The effects of ATP, adenos-ine (Ado), and adenosine diphosphate at the same concentration on AP were not different from each other significantly.Neither uridine triphosphate nor, α,β-methylene ATP had significant electrophysiologic effects on the sinoatrialnode of rabbits. Both the electrophysiologic effects of ATP and Ado on pacemaker cells were inhibited by P1receptor antagonist aminophylline 0.1 mmol/L (P0.05). CONCLUSION: There are nofunctional P2X1 and P2Y2 receptors on pacemaker cells of the rabbit sinoatrial nodes, and the electrophysiologiceffects of ATP in the rabbit sinoatrial node pacemaker cells are mediated via P1 receptors by Ado degraded fromATP.

  11. Effect of caffeine and adenosine on G2 repair: mitotic delay and chromosome damage.

    González-Fernández, A; Hernández, P; López-Sáez, J F

    1985-04-01

    Proliferating plant cells treated during the late S period with 5-aminouracil (AU), give the typical response that DNA-damaging agents induce, characterized by: an important mitotic delay, and a potentiation of the chromosome damage by caffeine post-treatment. The study of labelled prophases, after a tritiated thymidine pulse, allowed evaluation of the mitotic delay induced by AU as well as its reversion by caffeine, while chromosome damage was estimated by the percentage of anaphases and telophases showing chromosomal aberrations. Post-treatment with adenosine alone has shown no effect on mitotic delay or chromosomal damage. However, when cells after AU were incubated in caffeine plus adenosine, the chromosome damage potentiation was abolished without affecting the caffeine action on mitotic delay. As a consequence, we postulate that caffeine could have two effects on G2 cells with damaged DNA: the first, to cancel their mitotic delay and the second to inhibit some DNA-repair pathway(s). Only this last effect could be reversed by adenosine.

  12. Identification and function of adenosine A3 receptor in afferent arterioles.

    Lu, Yan; Zhang, Rui; Ge, Ying; Carlstrom, Mattias; Wang, Shaohui; Fu, Yiling; Cheng, Liang; Wei, Jin; Roman, Richard J; Wang, Lei; Gao, Xichun; Liu, Ruisheng

    2015-05-01

    Adenosine plays an important role in regulation of renal microcirculation. All receptors of adenosine, A1, A2A, A2B, and A3, have been found in the kidney. However, little is known about the location and function of the A3 receptor in the kidney. The present study determined the expression and role of A3 receptors in mediating the afferent arteriole (Af-Art) response and studied the interaction of A3 receptors with angiotensin II (ANG II), A1 and A2 receptors on the Af-Art. We found that the A3 receptor expressed in microdissected isolated Af-Art and the mRNA levels of A3 receptor were 59% of A1. In the isolated microperfused Af-Art, A3 receptor agonist IB-MECA did not have a constrictive effect. Activation of A3 receptor dilated the preconstricted Af-Art by norepinephrine and blunted the vasoconstrictive effect of both adenosine A1 receptor activation and ANG II on the Af-Art, respectively. Selective A2 receptor antagonist (both A2A and A2B) had no effect on A3 receptor agonist-induced vasodilation, indicating that the dilatory effect of A3 receptor activation is not mediated by activation of A2 receptor. We conclude that the A3 receptor is expressed in the Af-Art, and activation of the A3 receptor dilates the Af-Art.

  13. N-ethyl-carboxamide adenosine inhibits perioral dyskinesias induced by sulpiride + SKF 38393 in rabbits.

    Caporali, M G; Scotti de Carolis, A; Popoli, P

    1992-11-13

    A pattern of perioral dyskinesia was induced in adult male rabbits by concomitant stimulation of dopamine D1 receptors (SKF 38393) and blockade of dopamine D2 receptors (sulpiride). Rabbits treated with sulpiride (6 and 12.5 mg/kg i.v.) then, 90 min thereafter, with SKF 38393 (0.1, 1 and 10 mg/kg i.v.) showed a pattern of perioral dyskinesia characterized by compulsive and repetitive sniffing, licking and vacuous chewing. These effects were completely prevented by the administration of N-ethylcarboxamide adenosine (NECA), an A2 > A1 adenosine receptor agonist. The present results confirm that perioral dyskinesia is dependent on the activation of dopamine D1 receptors. They also show that, in order to induce perioral dyskinesia in rabbits, a concomitant blockade of dopamine D2 receptors is required. Finally, the antagonistic effect of NECA on the appearance of perioral movements confirms that adenosine receptors play a key role in the control of dopamine-mediated effects.

  14. Role of nitric oxide in adenosine-induced vasodilation in humans

    Costa, F.; Biaggioni, I.; Robertson, D. (Principal Investigator)

    1998-01-01

    Vasodilation is one of the most prominent effects of adenosine and one of the first to be recognized, but its mechanism of action is not completely understood. In particular, there is conflicting information about the potential contribution of endothelial factors. The purpose of this study was to explore the role of nitric oxide in the vasodilatory effect of adenosine. Forearm blood flow responses to intrabrachial adenosine infusion (125 microg/min) were assessed with venous occlusion plethysmography during intrabrachial infusion of saline or the nitric oxide synthase inhibitor NG-monomethyl-L-arginine (L-NMMA) (12.5 mg/min). Intrabrachial infusions of acetylcholine (50 microg/min) and nitroprusside (3 microg/min) were used as a positive and negative control, respectively. These doses were chosen to produce comparable levels of vasodilation. In a separate study, a second saline infusion was administered instead of L-NMMA to rule out time-related effects. As expected, pretreatment with L-NMMA reduced acetylcholine-induced vasodilation; 50 microg/min acetylcholine increased forearm blood flow by 150+/-43% and 51+/-12% during saline and L-NMMA infusion, respectively (Pvasodilation is not mediated by nitric oxide in the human forearm.

  15. How do ADARs bind RNA? New protein-RNA structures illuminate substrate recognition by the RNA editing ADARs.

    Thomas, Justin M; Beal, Peter A

    2017-02-20

    Deamination of adenosine in RNA to form inosine has wide ranging consequences on RNA function including amino acid substitution to give proteins not encoded in the genome. What determines which adenosines in an mRNA are subject to this modification reaction? The answer lies in an understanding of the mechanism and substrate recognition properties of adenosine deaminases that act on RNA (ADARs). Our recent publication of X-ray crystal structures of the human ADAR2 deaminase domain bound to RNA editing substrates shed considerable light on how the catalytic domains of these enzymes bind RNA and promote adenosine deamination. Here we review in detail the deaminase domain-RNA contact surfaces and present models of how full length ADARs, bearing double stranded RNA-binding domains (dsRBDs) and deaminase domains, could process naturally occurring substrate RNAs.

  16. DNA binding of the cell cycle transcriptional regulator GcrA depends on N6-adenosine methylation in Caulobacter crescentus and other Alphaproteobacteria.

    Fioravanti, Antonella; Fumeaux, Coralie; Mohapatra, Saswat S; Bompard, Coralie; Brilli, Matteo; Frandi, Antonio; Castric, Vincent; Villeret, Vincent; Viollier, Patrick H; Biondi, Emanuele G

    2013-05-01

    Several regulators are involved in the control of cell cycle progression in the bacterial model system Caulobacter crescentus, which divides asymmetrically into a vegetative G1-phase (swarmer) cell and a replicative S-phase (stalked) cell. Here we report a novel functional interaction between the enigmatic cell cycle regulator GcrA and the N6-adenosine methyltransferase CcrM, both highly conserved proteins among Alphaproteobacteria, that are activated early and at the end of S-phase, respectively. As no direct biochemical and regulatory relationship between GcrA and CcrM were known, we used a combination of ChIP (chromatin-immunoprecipitation), biochemical and biophysical experimentation, and genetics to show that GcrA is a dimeric DNA-binding protein that preferentially targets promoters harbouring CcrM methylation sites. After tracing CcrM-dependent N6-methyl-adenosine promoter marks at a genome-wide scale, we show that these marks recruit GcrA in vitro and in vivo. Moreover, we found that, in the presence of a methylated target, GcrA recruits the RNA polymerase to the promoter, consistent with its role in transcriptional activation. Since methylation-dependent DNA binding is also observed with GcrA orthologs from other Alphaproteobacteria, we conclude that GcrA is the founding member of a new and conserved class of transcriptional regulators that function as molecular effectors of a methylation-dependent (non-heritable) epigenetic switch that regulates gene expression during the cell cycle.

  17. DNA binding of the cell cycle transcriptional regulator GcrA depends on N6-adenosine methylation in Caulobacter crescentus and other Alphaproteobacteria.

    Antonella Fioravanti

    2013-05-01

    Full Text Available Several regulators are involved in the control of cell cycle progression in the bacterial model system Caulobacter crescentus, which divides asymmetrically into a vegetative G1-phase (swarmer cell and a replicative S-phase (stalked cell. Here we report a novel functional interaction between the enigmatic cell cycle regulator GcrA and the N6-adenosine methyltransferase CcrM, both highly conserved proteins among Alphaproteobacteria, that are activated early and at the end of S-phase, respectively. As no direct biochemical and regulatory relationship between GcrA and CcrM were known, we used a combination of ChIP (chromatin-immunoprecipitation, biochemical and biophysical experimentation, and genetics to show that GcrA is a dimeric DNA-binding protein that preferentially targets promoters harbouring CcrM methylation sites. After tracing CcrM-dependent N6-methyl-adenosine promoter marks at a genome-wide scale, we show that these marks recruit GcrA in vitro and in vivo. Moreover, we found that, in the presence of a methylated target, GcrA recruits the RNA polymerase to the promoter, consistent with its role in transcriptional activation. Since methylation-dependent DNA binding is also observed with GcrA orthologs from other Alphaproteobacteria, we conclude that GcrA is the founding member of a new and conserved class of transcriptional regulators that function as molecular effectors of a methylation-dependent (non-heritable epigenetic switch that regulates gene expression during the cell cycle.

  18. Adenosine A2A receptor deficiency up-regulates cystatin F expression in white matter lesions induced by chronic cerebral hypoperfusion.

    Duan, Wei; Ran, Hong; Zhou, Zhujuan; He, Qifen; Zheng, Jian

    2012-01-01

    In previous studies, we have shown that the inactivation of the adenosine A2A receptor exacerbates chronic cerebral hypoperfusion-induced white matter lesions (WMLs) by enhancing neuroinflammatory responses. However, the molecular mechanism underlying the effect of the adenosine A2A receptor remains unknown. Recent studies have demonstrated that cystatin F, a potent endogenous cysteine protease inhibitor, is selectively expressed in immune cells in association with inflammatory demyelination in central nervous system diseases. To understand the expression of cystatin F and its potential role in the effect of A2A receptor on WMLs induced through chronic cerebral hypoperfusion, we investigated cystatin F expression in the WMLs of A2A receptor gene knockout mice, the littermate wild-type mice and wild-type mice treated daily with the A2A receptor agonist CGS21680 or both CGS21680 and A2A receptor antagonist SCH58261 after chronic cerebral hypoperfusion. The results of quantitative-PCR and western blot analysis revealed that cystatin F mRNA and protein expression were significantly up-regulated in the WMLs after chronic cerebral hypoperfusion. In addition, cystatin F expression in the corpus callosum was significantly increased in A2A receptor gene knockout mice and markedly decreased in mice treated with CGS21680 on both the mRNA and protein levels. Additionally, SCH58261 counteracted the attenuation of cystatin F expression produced by CGS21680 after chronic cerebral hypoperfusion. Moreover, double immunofluorescence staining revealed that cystatin F was co-localized with the activated microglia marker CD11b. In conclusion, the cystatin F expression in the activated microglia is closely associated with the effect of the A2A receptors, which may be related to the neuroinflammatory responses occurring during the pathological process.

  19. Adenosine A2A receptor deficiency up-regulates cystatin F expression in white matter lesions induced by chronic cerebral hypoperfusion.

    Wei Duan

    Full Text Available In previous studies, we have shown that the inactivation of the adenosine A2A receptor exacerbates chronic cerebral hypoperfusion-induced white matter lesions (WMLs by enhancing neuroinflammatory responses. However, the molecular mechanism underlying the effect of the adenosine A2A receptor remains unknown. Recent studies have demonstrated that cystatin F, a potent endogenous cysteine protease inhibitor, is selectively expressed in immune cells in association with inflammatory demyelination in central nervous system diseases. To understand the expression of cystatin F and its potential role in the effect of A2A receptor on WMLs induced through chronic cerebral hypoperfusion, we investigated cystatin F expression in the WMLs of A2A receptor gene knockout mice, the littermate wild-type mice and wild-type mice treated daily with the A2A receptor agonist CGS21680 or both CGS21680 and A2A receptor antagonist SCH58261 after chronic cerebral hypoperfusion. The results of quantitative-PCR and western blot analysis revealed that cystatin F mRNA and protein expression were significantly up-regulated in the WMLs after chronic cerebral hypoperfusion. In addition, cystatin F expression in the corpus callosum was significantly increased in A2A receptor gene knockout mice and markedly decreased in mice treated with CGS21680 on both the mRNA and protein levels. Additionally, SCH58261 counteracted the attenuation of cystatin F expression produced by CGS21680 after chronic cerebral hypoperfusion. Moreover, double immunofluorescence staining revealed that cystatin F was co-localized with the activated microglia marker CD11b. In conclusion, the cystatin F expression in the activated microglia is closely associated with the effect of the A2A receptors, which may be related to the neuroinflammatory responses occurring during the pathological process.

  20. A2B adenosine receptors stimulate IL-6 production in primary murine microglia through p38 MAPK kinase pathway.

    Merighi, Stefania; Bencivenni, Serena; Vincenzi, Fabrizio; Varani, Katia; Borea, Pier Andrea; Gessi, Stefania

    2017-03-01

    The hallmark of neuroinflammation is the activation of microglia, the immunocompetent cells of the CNS, releasing a number of proinflammatory mediators implicated in the pathogenesis of neuronal diseases. Adenosine is an ubiquitous autacoid regulating several microglia functions through four receptor subtypes named A1, A2A, A2B and A3 (ARs), that represent good targets to suppress inflammation occurring in CNS. Here we investigated the potential role of ARs in the modulation of IL-6 secretion and cell proliferation in primary microglial cells. The A2BAR agonist 2-[[6-Amino-3,5-dicyano-4-[4-(cyclopropylmethoxy)phenyl]-2-pyridinyl]thio]-acetamide (BAY60-6583) stimulated IL-6 increase under normoxia and hypoxia, in a dose- and time-dependent way. In cells incubated with the blockers of phospholipase C (PLC), protein kinase C epsilon (PKC-ε) and PKC delta (PKC-δ) the IL-6 increase due to A2BAR activation was strongly reduced, whilst it was not affected by the inhibitor of adenylyl cyclase (AC). Investigation of cellular signalling involved in the A2BAR effect revealed that only the inhibitor of p38 mitogen activated protein kinase (MAPK) was able to block the agonist's effect on IL-6 secretion, whilst inhibitors of pERK1/2, JNK1/2 MAPKs and Akt were not. Stimulation of p38 by BAY60-6583 was A2BAR-dependent, through a pathway affecting PLC, PKC-ε and PKC-δ but not AC, in both normoxia and hypoxia. Finally, BAY60-6583 increased microglial cell proliferation involving A2BAR, PLC, PKC-ε, PKC-δ and p38 signalling. In conclusion, A2BARs activation increased IL-6 secretion and cell proliferation in murine primary microglial cells, through PLC, PKC-ε, PKC-δ and p38 pathways, thus suggesting their involvement in microglial activation and neuroinflammation.

  1. Adenosine Triphosphate (ATP Is a Candidate Signaling Molecule in the Mitochondria-to-Nucleus Retrograde Response Pathway

    Zhengchang Liu

    2013-03-01

    Full Text Available Intracellular communication from the mitochondria to the nucleus is achieved via the retrograde response. In budding yeast, the retrograde response, also known as the RTG pathway, is regulated positively by Rtg1, Rtg2, Rtg3 and Grr1 and negatively by Mks1, Lst8 and two 14-3-3 proteins, Bmh1/2. Activation of retrograde signaling leads to activation of Rtg1/3, two basic helix-loop-helix leucine zipper transcription factors. Rtg1/3 activation requires Rtg2, a cytoplasmic protein with an N-terminal adenosine triphosphate (ATP binding domain belonging to the actin/Hsp70/sugar kinase superfamily. The critical regulatory step of the retrograde response is the interaction between Rtg2 and Mks1. Rtg2 binds to and inactivates Mks1, allowing for activation of Rtg1/3 and the RTG pathway. When the pathway is inactive, Mks1 has dissociated from Rtg2 and bound to Bmh1/2, preventing activation of Rtg1/3. What signals association or disassociation of Mks1 and Rtg2 is unknown. Here, we show that ATP at physiological concentrations dissociates Mks1 from Rtg2 in a highly cooperative fashion. We report that ATP-mediated dissociation of Mks1 from Rtg2 is conserved in two other fungal species, K. lactis and K. waltii. Activation of Rtg1/3 upregulates expression of genes encoding enzymes catalyzing the first three reactions of the Krebs cycle, which is coupled to ATP synthesis through oxidative phosphorylation. Therefore, we propose that the retrograde response is an ATP homeostasis pathway coupling ATP production with ATP-mediated repression of the retrograde response by releasing Mks1 from Rtg2.

  2. Adenosine A1 receptor-mediated transactivation of the EGF receptor produces a neuroprotective effect on cortical neurons in vitro

    Ke-qiang XIE; Li-min ZHANG; Yan CAO; Jun ZHU; Lin-yin FENG

    2009-01-01

    Aim:To understand the mechanism of the transactivation of the epidermal growth factor receptor (EGFR) mediated by the adenosine A1 receptor (A1R).Methods:Primary cultured rat cortical neurons subjected to oxygen-glucose deprivation (OGD) and HEK293/A1R cells were treated with the A1R-specific agonist N6-cyclopentyladenosine (CPA).Phospho-EGFR,Akt,and ERK1/2 were observed by Western blot.An interaction between EGFR and AIR was detected using immunoprecipitation and immunocytochemistry.Results:The A1R agonist CPA causes protein kinase B (Akt) activation and protects primary cortical neurons from oxygen-glucose deprivation (OGD) insult.A1R and EGFR co-localize in the membranes of neurons and form an immunocomplex.A1R stimulation induces significant EGFR phosphorylation via a P13K and Src kinase signaling pathway;this stimulation provides a neuroprotective effect in cortical neurons.CPA leads to sustained phosphorylation of extracellularly regulated kinases 1 and 2 (ERK1/2) in cortical neurons,but only to transient phosphorylation in HEK 293/A1R cells.The response to the AtR agonist is mediated primarily through EGFR trans-activation that is dependent on pertussis toxin (PTX)-sensitive G1 protein and metalloproteases in HEK 293/A1R.Conclusion:A1R-mediated EGFR transactivation confers a neuroprotective effect in primary cortical neurons.P13 kinase and Src kinase play pivotal roles in this response.

  3. Mycobacterium tuberculosis ESAT6 and CPF10 Induce Adenosine Deaminase 2 mRNA Expression in Monocyte-Derived Macrophages

    Bae, Mi Jung; Ryu, Suyeon; Kim, Ha-Jeong; Cha, Seung Ick

    2017-01-01

    Background Delayed hypersensitivity plays a large role in the pathogenesis of tuberculous pleural effusion (TPE). Macrophages infected with live Mycobacterium tuberculosis (MTB) increase the levels of adenosine deaminase2 (ADA2) in the pleural fluid of TPE patients. However, it is as yet unclear whether ADA2 can be produced by macrophages when challenged with MTB antigens alone. This study therefore evaluated the levels of ADA2 mRNA expression, using monocyte-derived macrophages (MDMs) stimulated with MTB antigens. Methods Purified monocytes from the peripheral blood mononuclear cells of healthy volunteers were differentiated into macrophages using granulocyte-macrophage colony-stimulating factor (GM-CSF) or macrophage colony-stimulating factor (M-CSF). The MDMs were stimulated with early secretory antigenic target protein 6 (ESAT6) and culture filtrate protein 10 (CFP10). The mRNA expression levels for the cat eye syndrome chromosome region, candidate 1 (CECR1) gene encoding ADA2 were then measured. Results CECR1 mRNA expression levels were significantly higher in MDMs stimulated with ESAT6 and CFP10, than in the unstimulated MDMs. When stimulated with ESAT6, M-CSF-treated MDMs showed more pronounced CECR1 mRNA expression than GM-CSF-treated MDMs. Interferon-γ decreased the ESAT6- and CFP10-induced CECR1 mRNA expression in MDMs. CECR1 mRNA expression levels were positively correlated with mRNA expression of tumor necrosis factor α and interleukin 10, respectively. Conclusion ADA2 mRNA expression increased when MDMs were stimulated with MTB antigens alone. This partly indicates that pleural fluid ADA levels could increase in patients with culture-negative TPE. Our results may be helpful in improving the understanding of TPE pathogenesis.

  4. Regulation of epithelial sodium channel a-subunit expression by adenosine receptor A2a in alveolar epithelial cells

    DENG Wang; WANG Dao-xin; ZHANG Wei; LI Chang-yi

    2011-01-01

    Background The amiloride-sensitive epithelial sodium channel a-subunit (a-ENaC) is an important factor for alveolar fluid clearance during acute lung injury. The relationship between adenosine receptor A2a (A2aAR) expressed in alveolar epithelial cells and aα-ENaC is poorly understood. We targeted the A2aAR in this study to investigate its role in the expression of αa-ENaC and in acute lung injury.Methods A549 cells were incubated with different concentrations of A2aAR agonist CGS-21680 and with 100 μmol/L CGS-21680 for various times. Rats were treated with lipopolysaccharide (LPS) after CGS-21680 was injected. Animals were sacrificed and tissue was harvested for evaluation of lung injury by analysis of the lung wet-to-dry weight ratio, lung permeability and myeloperoxidase activity. RT-PCR and Western blotting were used to determine the mRNA and protein expression levels of α-ENaC in A549 cells and alveolar type II epithelial cells.Results Both mRNA and protein levels of α-ENaC were markedly higher from 4 hours to 24 hours after exposure to 100μmol/L CGS-21680. There were significant changes from 0.1 umol/L to 100 μmol/L CGS-21680, with a positive correlation between increased concentrations of CGS-21680 and expression of α-ENaC. Treatment with CGS-21680during LPS induced lung injury protected the lung and promoted α-ENaC expression in the alveolar epithelial cells.Conclusion Activation of A2aAR has a protective effect during the lung injury, which may be beneficial to the prognosis of acute lung injury.

  5. Caffeine acts via A1 adenosine receptors to disrupt embryonic cardiac function.

    Daniela L Buscariollo

    Full Text Available BACKGROUND: Evidence suggests that adenosine acts via cardiac A1 adenosine receptors (A1ARs to protect embryos against hypoxia. During embryogenesis, A1ARs are the dominant regulator of heart rate, and A1AR activation reduces heart rate. Adenosine action is inhibited by caffeine, which is widely consumed during pregnancy. In this study, we tested the hypothesis that caffeine influences developing embryos by altering cardiac function. METHODOLOGY/PRINCIPAL FINDINGS: Effects of caffeine and adenosine receptor-selective antagonists on heart rate were studied in vitro using whole murine embryos at E9.5 and isolated hearts at E12.5. Embryos were examined in room air (21% O(2 or hypoxic (2% O(2 conditions. Hypoxia decreased heart rates of E9.5 embryos by 15.8% and in E12.5 isolated hearts by 27.1%. In room air, caffeine (200 µM had no effect on E9.5 heart rates; however, caffeine increased heart rates at E12.5 by 37.7%. Caffeine abolished hypoxia-mediated bradycardia at E9.5 and blunted hypoxia-mediated bradycardia at E12.5. Real-time PCR analysis of RNA from isolated E9.5 and E12.5 hearts showed that A1AR and A2aAR genes were expressed at both ages. Treatment with adenosine receptor-selective antagonists revealed that SCH-58261 (A2aAR-specific antagonist had no affects on heart function, whereas DPCPX (A1AR-specific antagonist had effects similar to caffeine treatment at E9.5 and E12.5. At E12.5, embryonic hearts lacking A1AR expression (A1AR-/- had elevated heart rates compared to A1AR+/- littermates, A1AR-/- heart rates failed to decrease to levels comparable to those of controls. Caffeine did not significantly affect heart rates of A1AR-/- embryos. CONCLUSIONS/SIGNIFICANCE: These data show that caffeine alters embryonic cardiac function and disrupts the normal cardiac response to hypoxia through blockade of A1AR action. Our results raise concern for caffeine exposure during embryogenesis, particularly in pregnancies with increased risk of

  6. A-to-I editing of protein coding and noncoding RNAs.

    Mallela, Arka; Nishikura, Kazuko

    2012-01-01

    Adenosine deaminase acting on RNA (ADAR) catalyzes the hydrolytic deamination of adenosine to inosine in double-stranded RNA (dsRNA) substrates. Inosine pairs preferentially with cytidine, as opposed to uridine; therefore, ADAR editing alters the sequence and base pairing properties of both protein-coding and non-coding RNA. Editing can directly alter the sequence of protein-coding transcripts and modify splicing, or affect a variety of non-coding targets, including microRNA, small interfering RNA, viral transcripts, and repeat elements such as Alu and LINE. Such editing has a wide range of physiological effects, including modification of targets in the brain and in disease states.

  7. Pooled comparison of regadenoson versus adenosine for measuring fractional flow reserve and coronary flow in the catheterization laboratory

    Stolker, Joshua M., E-mail: jstolker@yahoo.com [Mercy Heart and Vascular, 901 Patients First Drive, Washington, MO 63090 (United States); Saint Louis University, 3635 Vista Ave, St. Louis, MO 63110 (United States); Lim, Michael J., E-mail: limmj@slu.edu [Saint Louis University, 3635 Vista Ave, St. Louis, MO 63110 (United States); Shavelle, David M., E-mail: david.shavelle@med.usc.edu [University of Southern California, 1510 San Pablo St, Suite 322, Los Angeles, CA 90033 (United States); Morris, D. Lynn, E-mail: morrisdl@einstein.edu [Albert Einstein Medical Center, 5501 Old York Rd, Philadelphia, PA 19141 (United States); Angiolillo, Dominick J., E-mail: dominick.angiolillo@jax.ufl.edu [University of Florida Health-Jacksonville, 655 West 8th St, Jacksonville, FL 32209 (United States); Guzman, Luis A., E-mail: luis.guzman@jax.ufl.edu [University of Florida Health-Jacksonville, 655 West 8th St, Jacksonville, FL 32209 (United States); Kennedy, Kevin F., E-mail: kfkennedy@saint-lukes.org [Saint Luke' s Mid America Heart Institute, 4401 Wornall Road, Kansas City, MO 64111 (United States); Weber, Elizabeth, E-mail: eweber1@slu.edu [Saint Louis University, 3635 Vista Ave, St. Louis, MO 63110 (United States); Zareh, Meena, E-mail: meena.zareh@med.usc.edu [University of Southern California, 1510 San Pablo St, Suite 322, Los Angeles, CA 90033 (United States); Neumayr, Robert H., E-mail: robneumayr@gmail.com [Mercy Heart and Vascular, 901 Patients First Drive, Washington, MO 63090 (United States); Saint Louis University, 3635 Vista Ave, St. Louis, MO 63110 (United States); Zenni, Martin M., E-mail: martin.zenni@jax.ufl.edu [University of Florida Health-Jacksonville, 655 West 8th St, Jacksonville, FL 32209 (United States)

    2015-07-15

    Background: Adenosine is the gold standard for augmenting coronary flow during fractional flow reserve (FFR) testing of intermediate coronary stenoses. However, intravenous infusion is time-consuming and intracoronary injection is subject to variability. Regadenoson is a newer adenosine alternative administered as a single intravenous bolus during nuclear stress testing, but its efficacy and safety during FFR testing have been evaluated only in small, single-center studies. Methods: We pooled data from 5 academic hospitals, in which patients undergoing clinically-indicated FFR prospectively underwent comparison of intravenous adenosine infusion (140–175 mcg/kg/min) versus regadenoson bolus (400 mcg). Hemodynamics and symptoms with adenosine were recorded until maximal hyperemia occurred, and after returning to baseline hemodynamics, regadenoson was administered and monitoring was repeated. In a subset of patients with coronary flow data, average peak velocity (APV) at the distal flow sensor was recorded. Results: Of 149 patients enrolled, mean age was 59 ± 9 years, 76% were male, and 54% underwent testing of the left anterior descending artery. Mean adenosine-FFR and regadenoson-FFR were identical (0.82 ± 0.10) with excellent correlation of individual values (r = 0.96, p < 0.001) and no difference in patient-reported symptoms. Four patients (2.6%) had discrepancies between the 2 drugs for the clinical decision-making cutoff of FFR ≤ 0.80. Coronary flow responses to adenosine and regadenoson were similar (APV at maximal hyperemia 36 cm/s for both, p = 0.81). Conclusions: Regadenoson single-bolus administration has comparable FFR, symptoms, and coronary flow augmentation when compared with standard intravenous adenosine infusion. With its greater ease of administration, regadenoson may be a more “user-friendly” option for invasive ischemic testing.

  8. The effect of cannabidiol on ischemia/reperfusion-induced ventricular arrhythmias: the role of adenosine A1 receptors.

    Gonca, Ersöz; Darıcı, Faruk

    2015-01-01

    Cannabidiol (CBD) is a nonpsychoactive phytocannabinoid with anti-inflammatory activity mediated by enhancing adenosine signaling. As the adenosine A1 receptor activation confers protection against ischemia/reperfusion (I/R)-induced ventricular arrhythmias, we hypothesized that CBD may have antiarrhythmic effect through the activation of adenosine A1 receptor. Cannabidiol has recently been shown to suppress ischemia-induced ventricular arrhythmias. We aimed to research the effect of CBD on the incidence and the duration of I/R-induced ventricular arrhythmias and to investigate the role of adenosine A1 receptor activation in the possible antiarrhythmic effect of CBD. Myocardial ischemia and reperfusion was induced in anesthetized male rats by ligating the left anterior descending coronary artery for 6 minutes and by loosening the bond at the coronary artery, respectively. Cannabidiol alone was given in a dose of 50 µg/kg, 10 minutes prior to coronary artery occlusion and coadministrated with adenosine A1 receptor antagonist 8-cyclopentyl-1,3-dipropylxanthine (DPCPX) in a dose of 100 µg/kg, 15 minutes prior to coronary artery occlusion to investigate whether the antiarrhythmic effect of CBD is modified by the activation of adenosine A1 receptors. The experimental groups were as follows: (1) vehicle control (n = 10), (2) CBD (n = 9), (3) DPCPX (n = 7), and (4) CBD + DPCPX group (n = 7). Cannabidiol treatment significantly decreased the incidence and the duration of ventricular tachycardia, total length of arrhythmias, and the arrhythmia scores compared to control during the reperfusion period. The DPCPX treatment alone did not affect the incidence and the duration of any type of arrhythmias. However, DPCPX aborted the antiarrhythmic effect of CBD when it was combined with it. The present results demonstrated that CBD has an antiarrhythmic effect against I/R-induced arrhythmias, and the antiarrhythmic effect of CBD may be mediated through the activation of adenosine

  9. Adenosine derived from Staphylococcus aureus-engulfed macrophages functions as a potent stimulant for the induction of inflammatory cytokines in mast cells

    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...

  10. A prospective cross-screening study on G-protein-coupled receptors: lessons learned in virtual compound library design.

    Sanders, M.P.A.; Roumen, L.; Horst, E. van der; Lane, J.R.; Vischer, H.F.; Offenbeek, J. van; Vries, H. de; Verhoeven, S.; Chow, K.Y.; Verkaar, F.; Beukers, M.W.; McGuire, R.; Leurs, R.; IJzerman, A.P.; Vlieg, J. de; Esch, I.J. de; Zaman, G.J.; Klomp, J.P.G.; Bender, A.; Graaf, C. de

    2012-01-01

    We present the systematic prospective evaluation of a protein-based and a ligand-based virtual screening platform against a set of three G-protein-coupled receptors (GPCRs): the beta-2 adrenoreceptor (ADRB2), the adenosine A(2A) receptor (AA2AR), and the sphingosine 1-phosphate receptor (S1PR1). Nov

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

    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.

    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.

  12. Projections of nucleus accumbens adenosine A2A receptor neurons in the mouse brain and their implications in mediating sleep-wake regulation

    Jianping eZhang

    2013-12-01

    Full Text Available Adenosine A2A receptors (A2ARs in the nucleus accumbens (Acb have been demonstrated to play an important role in the arousal effect of adenosine receptor antagonist caffeine, and may be involved in physiological sleep. To better understand the functions of these receptors in sleep, projections of A2AR neurons were mapped utilizing adeno-associated virus (AAV encoding humanized Renilla green fluorescent protein (hrGFP as a tracer for long axonal pathways. The Cre-dependent AAV was injected into the core (AcbC and shell (AcbSh of the Acb in A2AR-Cre mice. Immunohistochemistry was then used to visualize hrGFP, highlighting the perikarya of the A2AR neurons in the injection sites, and their axons in projection regions. The data revealed that A2AR neurons exhibit medium-sized and either round or elliptic perikarya with their processes within the Acb. Moreover, the projections from the Acb distributed to nuclei in the forebrain, diencephalon, and brainstem. In the forebrain, A2AR neurons from all Acb sub-regions jointly projected to the ventral pallidum, the nucleus of the diagonal band, and the substantia innominata. Heavy projections from the AcbC and the ventral AcbSh, and weaker projections from the medial AcbSh, were observed in the lateral hypothalamus and lateral preoptic area. In the brainstem, the Acb projections were found in the ventral tegmental area, while AcbC and ventral AcbSh also projected to the median raphe nucleus, the dorsal raphe nucleus, and the ventrolateral periaqueductal gray. The results supply a solid base for understanding the roles of the A2AR and A2AR neurons in the Acb, especially in the regulation of sleep.

  13. Caffeine reduces 11β-hydroxysteroid dehydrogenase type 2 expression in human trophoblast cells through the adenosine A(2B receptor.

    Saina Sharmin

    Full Text Available Maternal caffeine consumption is associated with reduced fetal growth, but the underlying molecular mechanisms are unknown. Since there is evidence that decreased placental 11β-hydroxysteroid dehydrogenase type 2 (11β-HSD2 is linked to fetal growth restriction, we hypothesized that caffeine may inhibit fetal growth partly through down regulating placental 11β-HSD2. As a first step in examining this hypothesis, we studied the effects of caffeine on placental 11β-HSD2 activity and expression using our established primary human trophoblast cells as an in vitro model system. Given that maternal serum concentrations of paraxanthine (the primary metabolite of caffeine were greater in women who gave birth to small-for-gestational age infants than to appropriately grown infants, we also studied the effects of paraxanthine. Our main findings were: (1 both caffeine and paraxanthine decreased placental 11β-HSD2 activity, protein and mRNA in a concentration-dependent manner; (2 this inhibitory effect was mediated by the adenosine A(2B receptor, since siRNA-mediated knockdown of this receptor prevented caffeine- and paraxanthine-induced inhibition of placental 11β-HSD2; and (3 forskolin (an activator of adenyl cyclase and a known stimulator of 11β-HSD2 abrogated the inhibitory effects of both caffeine and paraxanthine, which provides evidence for a functional link between exposure to caffeine and paraxanthine, decreased intracellular levels of cAMP and reduced placental 11β-HSD2. Taken together, these findings reveal that placental 11β-HSD2 is a novel molecular target through which caffeine may adversely affect fetal growth. They also uncover a previously unappreciated role for the adenosine A(2B receptor signaling in regulating placental 11β-HSD2, and consequently fetal development.

  14. Effect of adenosine on the supramolecular architecture and activity of 5-fluorouracil

    Singh, Udai P.; Kashyap, Sujata; Singh, Hari Ji; Mishra, Bhupesh Kumar; Roy, Partha; Chakraborty, Ajanta

    2012-04-01

    The reactions of adenosine (Ad) with 5-halouracils (5XU where X = F for 1, Cl for 2, Br for 3 and I for 4) resulted in the formation of co-crystals 1-4 in monoclinic with P21 space group. Despite of great variation in the halo substituent at the 5th position of the uracil, each structure contains the same number and same type of non-covalent interactions i.e., primary N-H⋯N, N-H⋯O, O-H⋯N, O-H⋯O hydrogen bonds and secondary C-H⋯O and X⋯O interactions within these motifs as well as with neighboring molecules. As compared to Ad the size of cavity increases in co-crystal 1 to accommodate the 5FU as a guest. With the variation of halogen from fluoro to iodo on the uracil, the orientation of the molecules remains the same with a slight difference in the dihedral angle in all the co-crystals 1-4. This study demonstrates that hydrogen-bonded interactions between adenosine and halouracils provide a supramolecular assembly to these co-crystals. Computational studies illustrate that the size of the halo substituents on uracil has no effect on the hydrogen bond interaction energy. It further reveals that the orientation of molecules remain same in both solid phase as well as in the gaseous phase. The antitumor and DNA cleavage activity studies show that the antitumor activity of 5-fluorouracil against MCF-7 breast cancer decreases in the presence of adenosine.

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

    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.)

  16. Adenosine receptors as markers of brain iron deficiency: Implications for Restless Legs Syndrome.

    Quiroz, César; Gulyani, Seema; Ruiqian, Wan; Bonaventura, Jordi; Cutler, Roy; Pearson, Virginia; Allen, Richard P; Earley, Christopher J; Mattson, Mark P; Ferré, Sergi

    2016-12-01

    Deficits of sensorimotor integration with periodic limb movements during sleep (PLMS) and hyperarousal and sleep disturbances in Restless Legs Syndrome (RLS) constitute two pathophysiologically distinct but interrelated clinical phenomena, which seem to depend mostly on alterations in dopaminergic and glutamatergic neurotransmission, respectively. Brain iron deficiency is considered as a main pathogenetic mechanism in RLS. Rodents with brain iron deficiency represent a valuable pathophysiological model of RLS, although they do not display motor disturbances. Nevertheless, they develop the main neurochemical dopaminergic changes found in RLS, such as decrease in striatal dopamine D2 receptor density. On the other hand, brain iron deficient mice exhibit the characteristic pattern of hyperarousal in RLS, providing a tool to find the link between brain iron deficiency and sleep disturbances in RLS. The present study provides evidence for a role of the endogenous sleep-promoting factor adenosine. Three different experimental preparations, long-term (22 weeks) severe or moderate iron-deficient (ID) diets (3- or 7-ppm iron diet) in mice and short-term (3 weeks) severe ID diet (3-ppm iron diet) in rats, demonstrated a significant downregulation (Western blotting in mouse and radioligand binding saturation experiments in rat brain tissue) of adenosine A1 receptors (A1R) in the cortex and striatum, concomitant to striatal D2R downregulation. On the other hand, the previously reported upregulation of adenosine A2A receptors (A2AR) was only observed with severe ID in both mice and rats. The results suggest a key role for A1R downregulation in the PLMS and hyperarousal in RLS.

  17. Endogenous activation of adenosine A1 receptors promotes post-ischemic electrocortical burst suppression

    Ilie, A; Ciocan, D; Constantinescu, A O

    2009-01-01

    . Several lines of evidence suggest that BS reflects an impairment of neocortical connectivity. Here we tested in vivo whether synaptic depression by adenosine A1 receptor (A1R) activation contributes to BS patterns following GCI. Male Wistar rats were subjected to 1, 5 or 10 min of GCI using a "four...... of post-ischemic BS patterns following brief ischemic episodes. It is likely that synaptic depression by post-ischemic A1R activation functionally disrupts the connectivity within the cortical networks to an extent that promotes BS patterns....

  18. Estimation of adenosine triphosphate utilization of rat mast cells during and after anaphylactic histamine secretion

    Johansen, Torben

    1990-01-01

    Determination of the cellular content of adenosine triphosphate (ATP) and the rate of ATP-synthesis were used to estimate the cellular utilization of ATP in relation to anaphylactic histamine secretion. There was an increased rate of oxidative ATP-synthesis and a decreased cellular ATP content...... during the time period of histamine secretion and immediately after its completion. During secretion the additional ATP-utilization above the basal level of ATP-synthesis was 0.51 pmol/10(3) cells. 2.5 min after cell activation, the rate of additional ATP-utilization was 0.30 pmol/10(3) cells...

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

    2014-01-01

    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...

  20. Diagnostic Value of Adenosine Deaminase and Its Isoforms in Type II Diabetes Mellitus

    Bagher Larijani; Ramin Heshmat; Mina Ebrahimi-Rad; Shohreh Khatami; Shirin Valadbeigi; Reza Saghiri

    2016-01-01

    Background and Aims. In the present study, we have investigated the activity of adenosine deaminase (ADA) as a diagnostic marker in type 2 (or II) diabetes mellitus (T2DM). Design and Methods. The deaminase activity of ADA1 and ADA2 was determined in serum from 33 patients with type 2 (or II) diabetes mellitus and 35 healthy controls. We also determined the proportion of glycated hemoglobin (HbA1c). Results. Our results showed significant differences between total serum ADA (tADA) and ADA2 ac...

  1. [An adenosine triphosphate bioluminescence assay for detecting the number of living cells].

    Liu, S; Peng, Z; Wang, H; Lou, J; He, B; Tang, Q; Qiu, D

    2000-06-01

    The method for detecting the number of living cells was studied. Using an adenosine triphosphate (ATP) bioluminescence assay, the present authors reported a perfect linear relationship between lg ATP concentrations and lg luminescence counts (r = 0.9963) as well as a relationship between lg number of cells and lg ATP luminescence counts (r = 0.9922). The detectable cells ranged from 10(2) to 10(6) cells/ml, the coefficients of variation 1-3%. This method is simple, accurate and sensitive and has a high reproducibility.

  2. Thiamine diphosphate adenylyl transferase from E. coli: functional characterization of the enzyme synthesizing adenosine thiamine triphosphate

    Brans Alain; Makarchikov Alexander F; Bettendorff Lucien

    2007-01-01

    Abstract Background We have recently identified a new thiamine derivative, adenosine thiamine triphosphate (AThTP), in E. coli. In intact bacteria, this nucleotide is synthesized only in the absence of a metabolizable carbon source and quickly disappears as soon as the cells receive a carbon source such as glucose. Thus, we hypothesized that AThTP may be a signal produced in response to carbon starvation. Results Here we show that, in bacterial extracts, the biosynthesis of AThTP is carried o...

  3. Dyspnea and Wheezing after Adenosine Injection in a Patient with Eosinophilic Bronchitis

    Rodrigo Cartin-Ceba

    2009-01-01

    Full Text Available A 58-year-old nonsmoker female was referred for evaluation of chronic cough of 13 months duration. After an initial work-up, the patient was diagnosed to have chronic cough due to eosinophilic bronchitis. The diagnostic work-up for eosinophilic bronchitis and bronchial biopsy is discussed. Eosinophilic bronchitis is differentiated from asthma. In addition, the patient developed dyspnea, flushing, and wheezing after the administration of adenosine during a cardiac stress test in spite of a negative methacholine challenge. This indirect stimulus of airway hyperresponsiveness suggests the possible involvement of mast cells in eosinophilic bronchitis.

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

    Novak, Ivana; Hede, Susanne; Hansen, Mette

    2007-01-01

    these could be involved in secretory processes, which involve cystic fibrosis transmembrane regulator (CFTR) Cl(-) channels or Ca(2+)-activated Cl(-) channels and [Formula: see text] transporters. Reverse transcriptase polymerase chain reaction analysis on rat pancreatic ducts and human duct cell......, 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...

  5. Stimulation of NTS A1 adenosine receptors differentially resets baroreflex control of regional sympathetic outputs.

    Scislo, Tadeusz J; Ichinose, Tomoko K; O'Leary, Donal S

    2008-01-01

    Previously we showed that pressor and differential regional sympathoexcitatory responses (adrenal > renal >/= lumbar) evoked by stimulation of A(1) adenosine receptors located in the nucleus of the solitary tract (NTS) were attenuated/abolished by baroreceptor denervation or blockade of glutamatergic transmission in the NTS, suggesting A(1) receptor-elicited inhibition of glutamatergic transmission in baroreflex pathways. Therefore we tested the hypothesis that stimulation of NTS A(1) adenosine receptors differentially inhibits/resets baroreflex responses of preganglionic adrenal (pre-ASNA), renal (RSNA), and lumbar (LSNA) sympathetic nerve activity. In urethane-chloralose-anesthetized male Sprague-Dawley rats (n = 65) we compared baroreflex-response curves (iv nitroprusside and phenylephrine) evoked before and after bilateral microinjections into the NTS of A(1) adenosine receptor agonist (N(6)-cyclopentyladenosine, CPA; 0.033-330 pmol/50 nl). CPA evoked typical dose-dependent pressor and differential sympathoexcitatory responses and similarly shifted baroreflex curves for pre-ASNA, RSNA, and LSNA toward higher mean arterial pressure (MAP) in a dose-dependent manner; the maximal shifts were 52.6 +/- 2.8, 48.0 +/- 3.6, and 56.8 +/- 6.7 mmHg for pre-ASNA, RSNA, and LSNA, respectively. These shifts were not a result of simple baroreceptor resetting because they were two to three times greater than respective increases in baseline MAP evoked by CPA. Baroreflex curves for pre-ASNA were additionally shifted upward: the maximal increases of upper and lower plateaus were 41.8 +/- 16.4% and 45.3 +/- 8.7%, respectively. Maximal gain (%/mmHg) measured before vs. after CPA increased for pre-ASNA (3.0 +/- 0.6 vs. 4.9 +/- 1.3), decreased for RSNA (4.1 +/- 0.6 vs. 2.3 +/- 0.3), and remained unaltered for LSNA (2.1 +/- 0.2 vs. 2.0 +/- 0.1). Vehicle control did not alter the baroreflex curves. We conclude that the activation of NTS A(1) adenosine receptors differentially inhibits

  6. Adenosine A2A receptor antagonists exert motor and neuroprotective effects by distinct cellular mechanisms

    Yu, Liqun; Shen, Hai-Ying; Coelho, Joana E.; Araújo, Inês M.; HUANG, QING-YUAN; Day, Yuan-Ji; Rebola, Nelson; Canas, Paula M.; Rapp, Erica Kirsten; Ferrara, Jarrod; Taylor, Darcie; Müller, Christa E.; Linden, Joel; Cunha, Rodrigo A.; Chen, Jiang-Fan

    2008-01-01

    To investigate whether the motor and neuroprotective effects of adenosine A2A receptor (A2AR) antagonists are mediated by distinct cell types in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) model of Parkinson's disease.We used the forebrain A2AR knock-out mice coupled with flow cytometric analyses and intracerebroventricular injection to determine the contribution of A2ARs in forebrain neurons and glial cells to A2AR antagonist-mediated motor and neuroprotective effects.The selecti...

  7. Cordycepin and N6-(2-Hydroxyethyl)-Adenosine from Cordyceps pruinosa and Their Interaction with Human Serum Albumin

    Meng, Zebin; Kang, Jichuan; Wen, Tingchi; Lei, Bangxing; Hyde, Kevin David

    2015-01-01

    Cordyceps pruinosa (CP) is often used as Traditional Chinese Medicine, but the substance basis of its medicinal properties is unclear. In this study, two compounds were isolated from CP cultures by column chromatography, and identified as cordycepin and N6-(2-hydroxyethyl)-adenosine (HEA) by Nuclear Magnetic Resonance. In order to understand the efficacy of these two substances as potential therapeutic agents, it is necessary to explore their binding with proteins. The molecular mechanisms of interaction between cordycepin, HEA and human serum albumin (HSA) were studied using UV and fluorescence spectroscopy. The bingding constants between HSA and cordycepin were 4.227, 3.573 and 3.076 × 103·at 17, 27 and 37°C respectively, and that of HSA and HEA were 27.102, 19.409 and 13.002 × 103·at the three tempretures respectively. Both cordycepin and HEA can quench the intrinsic fluorescence of HSA via static quenching, and they can bind with HSA to form complexes with a single binding site. The interaction forces between cordycepin and HSA were determined as electrostatic and hydrophobic, and those of HEA and HSA were hydrogen bonding and van der Waals forces. Using Foster's equation, the distance between fluorophores of cordycepin and HSA, and HEA and HSA are estimated to be 5.31 nm and 4.98 nm, respectively. In this study, cordycepin was isolated for the first time from CP, and will provide a new source of cordycepin and expand the use of this taxon. The interaction mechanisms between cordycepin and HSA was studied for the first time, which will provide a useful guide for the clinical application of cordycepin. The pharmacological importance of this study is to understand the interaction of HSA with cordycepin and HEA, which will be essential for the future designing of drugs based on the two compounds. PMID:25811172

  8. Cordycepin and N6-(2-hydroxyethyl-adenosine from Cordyceps pruinosa and their interaction with human serum albumin.

    Zebin Meng

    Full Text Available Cordyceps pruinosa (CP is often used as Traditional Chinese Medicine, but the substance basis of its medicinal properties is unclear. In this study, two compounds were isolated from CP cultures by column chromatography, and identified as cordycepin and N6-(2-hydroxyethyl-adenosine (HEA by Nuclear Magnetic Resonance. In order to understand the efficacy of these two substances as potential therapeutic agents, it is necessary to explore their binding with proteins. The molecular mechanisms of interaction between cordycepin, HEA and human serum albumin (HSA were studied using UV and fluorescence spectroscopy. The bingding constants between HSA and cordycepin were 4.227, 3.573 and 3.076 × 10(3·at 17, 27 and 37°C respectively, and that of HSA and HEA were 27.102, 19.409 and 13.002 × 10(3·at the three tempretures respectively. Both cordycepin and HEA can quench the intrinsic fluorescence of HSA via static quenching, and they can bind with HSA to form complexes with a single binding site. The interaction forces between cordycepin and HSA were determined as electrostatic and hydrophobic, and those of HEA and HSA were hydrogen bonding and van der Waals forces. Using Foster's equation, the distance between fluorophores of cordycepin and HSA, and HEA and HSA are estimated to be 5.31 nm and 4.98 nm, respectively. In this study, cordycepin was isolated for the first time from CP, and will provide a new source of cordycepin and expand the use of this taxon. The interaction mechanisms between cordycepin and HSA was studied for the first time, which will provide a useful guide for the clinical application of cordycepin. The pharmacological importance of this study is to understand the interaction of HSA with cordycepin and HEA, which will be essential for the future designing of drugs based on the two compounds.

  9. Utility of adenosine deaminase (ADA, PCR & thoracoscopy in differentiating tuberculous & non-tuberculous pleural effusion complicating chronic kidney disease

    Sravan Kumar

    2015-01-01

    Full Text Available Background & objectives: Pleural effusion is a common occurrence in patients with late-stage chronic kidney disease (CKD. In developing countries, many effusions remain undiagnosed after pleural fluid analysis (PFA and patients are empirically treated with antitubercular therapy. The aim of this study was to evaluate the role of adenosine deaminase (ADA, nucleic acid amplification tests (NAAT and medical thoracoscopy in distinguishing tubercular and non-tubercular aetiologies in exudative pleural effusions complicating CKD. Methods: Consecutive stage 4 and 5 CKD patients with pleural effusions underwent PFA including ADA and PCR [65 kDa gene; multiplex (IS6110, protein antigen b, MPB64]. Patients with exudative pleural effusion undiagnosed after PFA underwent medical thoracoscopy. Results: All 107 patients underwent thoracocentesis with 45 and 62 patients diagnosed as transudative and exudative pleural effusions, respectively. Twenty six of the 62 patients underwent medical thoracoscopy. Tuberculous pleurisy was diagnosed in six while uraemic pleuritis was diagnosed in 20 subjects. The sensitivity and specificity of pleural fluid ADA, 65 kDa gene PCR, and multiplex PCR were 66.7 and 90 per cent, 100 and 50 per cent, and 100 and 100 per cent, respectively. Thoracoscopy was associated with five complications in three patients. Interpretation & conclusions: Uraemia remains the most common cause of pleural effusion in CKD even in high TB prevalence country. Multiplex PCR and thoracoscopy are useful investigations in the diagnostic work-up of pleural effusions complicating CKD while the sensitivity and/or specificity of ADA and 65 kDa gene PCR is poor.

  10. Nitrite-induced methemoglobinaemia affects blood ionized and total magnesium level by hydrolysis of plasma adenosine triphosphate in rat.

    Rahman, Md Mizanur; Kim, Shang-Jin; Kim, Gi-Beum; Hong, Chul-Un; Lee, Young-Up; Kim, Sung-Zoo; Kim, Jin-Shang; Kang, Hyung-Sub

    2009-11-01

    The objective of this study was to evaluate the effects of sodium nitrite (NaNO(2))-induced methemoglobinaemia on plasma ATP (adenosine triphosphate) and corresponding changes of blood-ionized magnesium (iMg(2+)) as well as total magnesium (tMg(2+)) in a time-dependent manner. This study was performed on male Sprague-Dawley rats to which NaNO(2) was injected (10 mg/kg i.p.) to induce methemoglobinaemia. Methemoglobin (MetHb) in blood was measured before (0 min.) and after 10, 30, 60 and 120 min. of NaNO(2) injection. At respective time points, the tMg(2+), blood ions and gases were measured by atomic absorption spectrometry and ion selective electrode, respectively. Haematological parameters were checked by automatic blood cell count, and blood films were observed under light microscope. Plasma ATP was measured by bioluminescence assay using a luminometer, and plasma proteins were measured by an automatic analyser. Blood cell count (RBC, WBC and platelet), haematocrit, and haemoglobin were found to be decreased with the advancement of MetHb concentration. With the gradual increase of MetHb concentration, the plasma ATP decreased and blood iMg(2+) and plasma tMg(2+) increased significantly as time passed by in comparison with the pre-drug values. A significant decrease of the ratio of ionized calcium to iMg(2+), Na(+) and increase of K(+) was observed. In conclusion, NaNO(2)-induced methemoglobinaemia is a cause of hydrolysis of plasma ATP which is responsible for the increase of blood iMg(2+) and plasma tMg(2+) in rats.

  11. Effect of electromagnetic field on cyclic adenosine monophosphate (cAMP) in a human mu-opioid receptor cell model.

    Ross, Christina L; Teli, Thaleia; Harrison, Benjamin S

    2016-01-01

    During the cell communication process, endogenous and exogenous signaling affect normal as well as pathological developmental conditions. Exogenous influences such as extra-low-frequency electromagnetic field (EMF) have been shown to effect pain and inflammation by modulating G-protein receptors, down-regulating cyclooxygenase-2 activity, and affecting the calcium/calmodulin/nitric oxide pathway. Investigators have reported changes in opioid receptors and second messengers, such as cyclic adenosine monophosphate (cAMP), in opiate tolerance and dependence by showing how repeated exposure to morphine decreases adenylate cyclase activity causing cAMP to return to control levels in the tolerant state, and increase above control levels during withdrawal. Resonance responses to biological systems using exogenous EMF signals suggest that frequency response characteristics of the target can determine the EMF biological response. In our past research we found significant down regulation of inflammatory markers tumor necrosis factor alpha (TNF-α) and nuclear factor kappa B (NFκB) using 5 Hz EMF frequency. In this study cAMP was stimulated in Chinese Hamster Ovary (CHO) cells transfected with human mu-opioid receptors, then exposed to 5 Hz EMF, and outcomes were compared with morphine treatment. Results showed a 23% greater inhibition of cAMP-treating cells with EMF than with morphine. In order to test our results for frequency specific effects, we ran identical experiments using 13 Hz EMF, which produced results similar to controls. This study suggests the use of EMF as a complementary or alternative treatment to morphine that could both reduce pain and enhance patient quality of life without the side-effects of opiates.

  12. Novel treatment strategies in triple-negative breast cancer: specific role of poly(adenosine diphosphate-ribose polymerase inhibition

    Audeh MW

    2014-10-01

    Full Text Available M William Audeh Division of Medical Oncology, Samuel Oschin Cancer Institute, Cedars-Sinai Medical Center, Los Angeles, CA, USA Abstract: Inhibitors of the poly(adenosine triphosphate-ribose polymerase (PARP-1 enzyme induce synthetic lethality in cancers with ineffective DNA (DNA repair or homologous repair deficiency, and have shown promising clinical activity in cancers deficient in DNA repair due to germ-line mutation in BRCA1 and BRCA2. The majority of breast cancers arising in carriers of BRCA1 germ-line mutations, as well as half of those in BRCA2 carriers, are classified as triple-negative breast cancer (TNBC. TNBC is a biologically heterogeneous group of breast cancers characterized by the lack of immunohistochemical expression of the ER, PR, or HER2 proteins, and for which the current standard of care in systemic therapy is cytotoxic chemotherapy. Many “sporadic” cases of TNBC appear to have indicators of DNA repair dysfunction similar to those in BRCA-mutation carriers, suggesting the possible utility of PARP inhibitors in a subset of TNBC. Significant genetic heterogeneity has been observed within the TNBC cohort, creating challenges for interpretation of prior clinical trial data, and for the design of future clinical trials. Several PARP inhibitors are currently in clinical development in BRCA-mutated breast cancer. The use of PARP inhibitors in TNBC without BRCA mutation will require biomarkers that identify cancers with homologous repair deficiency in order to select patients likely to respond. Beyond mutations in the BRCA genes, dysfunction in other genes that interact with the homologous repair pathway may offer opportunities to induce synthetic lethality when combined with PARP inhibition. Keywords: PARP, triple negative breast cancer, PARP inhibitors

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

    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.

  14. Effects of oral adenosine 5'-triphosphate and adenosine in enteric-coated capsules on indomethacin-induced permeability changes in the human small intestine: a randomized cross-over study

    Bours Martijn JL

    2007-06-01

    Full Text Available Abstract Background It is well-known that nonsteroidal anti-inflammatory drugs (NSAIDs can cause damage to the small bowel associated with disruption of mucosal barrier function. In healthy human volunteers, we showed previously that topical administration of adenosine 5'-triphosphate (ATP by naso-intestinal tube attenuated a rise in small intestinal permeability induced by short-term challenge with the NSAID indomethacin. This finding suggested that ATP may be involved in the preservation of intestinal barrier function. Our current objective was to corroborate the favourable effect of ATP on indomethacin-induced permeability changes in healthy human volunteers when ATP is administered via enteric-coated capsules, which is a more practically feasible mode of administration. Since ATP effects may have been partly mediated through its breakdown to adenosine, effects of encapsulated adenosine were tested also. Methods By ingesting a test drink containing 5 g lactulose and 0.5 g L-rhamnose followed by five-hour collection of total urine, small intestinal permeability was assessed in 33 healthy human volunteers by measuring the urinary lactulose/rhamnose excretion ratio. Urinary excretion of lactulose and L-rhamnose was determined by fluorescent detection high-pressure liquid chromatography (HPLC. Basal permeability of the small intestine was assessed as a control condition (no indomethacin, no ATP/adenosine. As a model of increased small intestinal permeability, two dosages of indomethacin were ingested at 10 h (75 mg and 1 h (50 mg before ingesting the lactulose/rhamnose test drink. At 1.5 h before indomethacin ingestion, two dosages of placebo, ATP (2 g per dosage or adenosine (1 g per dosage were administered via enteric-coated hydroxypropyl methylcellulose (HPMC capsules with Eudragit© L30D-55. Results Median urinary lactulose/rhamnose excretion ratio (g/g in the control condition was 0.032 (interquartile range: 0.022–0.044. Compared to the

  15. High-frequency Electrocardiogram Analysis in the Ability to Predict Reversible Perfusion Defects during Adenosine Myocardial Perfusion Imaging

    Tragardh, Elin; Schlegel, Todd T.; Carlsson, Marcus; Pettersson, Jonas; Nilsson, Klas; Pahlm, Olle

    2007-01-01

    Background: A previous study has shown that analysis of high-frequency QRS components (HF-QRS) is highly sensitive and reasonably specific for detecting reversible perfusion defects on myocardial perfusion imaging (MPI) scans during adenosine. The purpose of the present study was to try to reproduce those findings. Methods: 12-lead high-resolution electrocardiogram recordings were obtained from 100 patients before (baseline) and during adenosine Tc-99m-tetrofosmin MPI tests. HF-QRS were analyzed regarding morphology and changes in root mean square (RMS) voltages from before the adenosine infusion to peak infusion. Results: The best area under the curve (AUC) was found in supine patients (AUC=0.736) in a combination of morphology and RMS changes. None of the measurements, however, were statistically better than tossing a coin (AUC=0.5). Conclusion: Analysis of HF-QRS was not significantly better than tossing a coin for determining reversible perfusion defects on MPI scans.

  16. Down-regulation of the A3 adenosine receptor in human mast cells upregulates mediators of angiogenesis and remodeling.

    Rudich, Noam; Dekel, Ornit; Sagi-Eisenberg, Ronit

    2015-05-01

    Adenosine activated mast cells have been long implicated in allergic asthma and studies in rodent mast cells have assigned the A3 adenosine receptor (A3R) a primary role in mediating adenosine responses. Here we analyzed the functional impact of A3R activation on genes that are implicated in tissue remodeling in severe asthma in the human mast cell line HMC-1 that shares similarities with lung derived human mast cells. Quantitative real time PCR demonstrated upregulation of IL6, IL8, VEGF, amphiregulin and osteopontin. Moreover, further upregulation of these genes was noted upon the addition of dexamethasone. Unexpectedly, activated A3R down regulated its own expression and knockdown of the receptor replicated the pattern of agonist induced gene upregulation. This study therefore identifies the human mast cell A3R as regulator of tissue remodeling gene expression in human mast cells and demonstrates a heretofore-unrecognized mode of feedback regulation that is exerted by this receptor.

  17. Decreased extracellular adenosine levels lead to loss of hypoxia-induced neuroprotection after repeated episodes of exposure to hypoxia.

    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.

  18. Granulocyte colony-stimulating factor and drugs elevating extracellular adenosine synergize to enhance haematopoietic reconstitution in irradiated mice

    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.

  19. Non-additive modulation of synaptic transmission by serotonin, adenosine, and cholinergic modulators in the sensory thalamus

    Ya-Chin eYang

    2015-03-01

    Full Text Available The thalamus relays sensory information to the cortex. Oscillatory activities of the thalamocortical network are modulated by monoamines, acetylcholine, and adenosine, and could be the key features characteristic of different vigilance states. Although the thalamus is almost always subjective to the actions of more than just one neuromodulator, reports on the modulatory effect of coexisting neuromodulators on thalamic synaptic transmission are unexpectedly scarce. We found that either monoamine or adenosine decreases retinothalamic synaptic strength and short-term depression, whereas cholinergic modulators generally enhance postsynaptic response to presynaptic activity. However, combinations of different modulators tend to produce non-additive effect, not predictable based on the action of one single modulator. Acetylcholine, acting via nicotinic receptors, can interact with either serotonin or adenosine to abolish most short-term synaptic depression. Moreover, the coexistence of adenosine and monoamine, with or without acetylcholine, results in robustly decreased synaptic strength and transforms short-term synaptic depression to facilitation. These findings are consistent with a view that acetylcholine is essential for an enriched sensory flow through the thalamus, and the flow is trimmed down by concomitant monoamine or adenosine (presumably for the wakefulness and rapid-eye movement, or REM, sleep state, respectively. In contrast, concomitant adenosine and monoamine would lead to a markedly deprived (and high-pass filtered sensory flow, and thus the dramatic decrease of monoamine may constitute the essential demarcation between non-REM and REM sleep. The collective actions of different neuromodulators on thalamic synaptic transmission thus could be essential for the understanding of network responsiveness in different vigilance states.

  20. Synergistic myoprotection of L-arginine and adenosine in a canine model of global myocardial ischaemic reperfusion injury

    DU Lei; DIAN Ke; CHEN Hui-jiao; AN Qi; JIA Meng-xing; YANG Ping-liang; WANG Wei; DENG Shuo-zeng; LIU Jin

    2007-01-01

    Background Endogenous nitric oxide and adenosine increase simultaneously to keep the balance of energy demand and supply when the oxygen supply is insufficient, which suggests that nitric oxide and adenosine might exert a synergistic myoprotection during tissue hypoxia. In this study, we tested this hypothesis utilizing a canine model of prolonged global myocardial ischaemic reperfusion injury.Methods In this double blind, controlled study, the hearts of 24 anaesthetized mongrel dogs were arrested for 2 hours with aortic cross clamping and blood cardioplegia. The treatment groups were those supplemented with 2 mmol/L L-arginine (ARG), supplemented with 1 mmol/L adenosine (ADO), ARG + ADO supplemented with both, and no supplementation (control) (n=6 in each group). Haemodynamics, biochemical indices, adenosine triphosphate (ATP) content and myeloperoxidase activities of myocardium were determined to evaluate myocardial injury. Statistical comparison was performed by two way ANOVA.Results Although the requirements for inotropic supports were higher, the cardiac outputs were lower in control group than in ARG, ADO and the combination groups. Plasma cardiac troponin I levels were higher and the areas of hydropic changes were larger in control group than in ARG and ADO groups. Combination of arginine and adenosine provided further myoprotection with respect to better cardiac performance, lower release of cardiac troponin I, and smaller areas of hydropic changes compared with ARG and ADO groups. ATP content was higher, but myeloperoxidase activities of myocardium were significantly lower in the combination group than in control, ARG and ADO groups (P<0.05).Conclusions Combination of L-arginine and adenosine provides synergistic myoprotection in a canine model of global myocardial ischaemia. Thus, the combination is recommended when the heart is exposed to a prolonged ischaemia during cardiac surgery.

  1. Value of the adenosine test for diagnosis of dual AV nodal physiology in patients with AV nodal reentrant tachycardia

    周斌全; 胡申江; 等

    2002-01-01

    Objectives:This study was aimed at assessing the value of the adenosine test for noninvasive diagnosis of dual AV nodal physiology(DAVNP) in patients with AV nodal reentrant tachycardia(VANRT).Methods:53 patients with paroxysmal supraventricular tachycardia(PSVT) were given incremental doses of adenosine intravenously during sinus rhythm before electrophysiological study.The adenosine test was repeated on a subset of 18 patients with AVNRT after radiofrequency catheter ablation.Results:Sudden increments of PR interval of more than 60 msec between two consecutive beats were observed in 26(83.9%) of 31 patients with typical AVNRT and 2(9.1%) of 22 patients with AVRT and AT(P<0.01),The maximal PR increment between 2 consecutive beats in the AVNRT group(105±45ms) was significantly greater than that in the AVRT and AT group[(20±13ms) (P<0.01),In postablation adenosine test,DAVNP was eliminated in all 8 patients who underwent slow pathway abolition that EPS showed the slow pathway disappeared and 4 of 10 patients who underwent slow pathway modification that EPS showed the slow pathway disappeared and 4 of 10 patients who underwent slow pathway modification that EPS whosed the slow pathway persisted.Six of 10 patients whw exhibited persistent duality showed a marked reduction in the number of beats conducted in the slow pathway after adenosine injection(P<0.01),COnclusions:Administration of adenosine during sinus rhythm may be a useful bedside test for diagnosis of DAVNP in high percentage of patients with typical AVNRT and additionally for evaluating the effects of radiofrequency ablation.

  2. Selected C8 two-chain linkers enhance the adenosine A1/A2A receptor affinity and selectivity of caffeine.

    van der Walt, M M; Terre'Blanche, G

    2017-01-05

    Recent research exploring C8 substitution on the caffeine core identified 8-(2-phenylethyl)-1,3,7-trimethylxanthine as a non-selective adenosine receptor antagonist. To elaborate further, we included various C8 two-chain-length linkers to enhance adenosine receptor affinity. The results indicated that the unsubstituted benzyloxy linker (1e A1Ki = 1.52 μM) displayed the highest affinity for the A1 adenosine receptor and the para-chloro-substituted phenoxymethyl (1d A2AKi = 1.33 μM) linker the best A2A adenosine receptor affinity. The position of the oxygen revealed that the phenoxymethyl linker favoured A1 adenosine receptor selectivity over the benzyloxy linker and, by introducing a para-chloro substituent, A2A adenosine receptor selectivity was obtained. Selected compounds (1c, 1e) behaved as A1 adenosine receptor antagonists in GTP shift assays and therefore represent selective and non-selective A1 and A2A adenosine receptor antagonists that may have potential for treating neurological disorders.

  3. PET imaging to measure therapy-related occupancy and disease-induced changes of expression of adenosine A1 receptors in the rodent brain

    Paul, Souman

    2014-01-01

    Rol van adenosine A1 receptor in de vroege fase van encefalitis Adenosine A1 receptoren (A1R) spelen een belangrijke rol bij de bescherming van hersencellen tijdens de vroege fase van hersenontsteking (encefalitis) bij ratten en mogelijk ook bij mensen. Dat concludeert Souman Paul in zijn proefschri

  4. Circulating adenosine increases during human experimental endotoxemia but blockade of its receptor does not influence the immune response and subsequent organ injury

    Ramakers, B.P.C.; Riksen, N.P.; Broek, P.H.H. van den; Franke, B.; Peters, W.H.M.; Hoeven, J.G. van der; Smits, P.; Pickkers, P.

    2011-01-01

    INTRODUCTION: Preclinical studies have shown that the endogenous nucleoside adenosine prevents excessive tissue injury during systemic inflammation. We aimed to study whether endogenous adenosine also limits tissue injury in a human in vivo model of systemic inflammation. In addition, we studied whe

  5. The Quintiles Prize Lecture 2004: The identification of the adenosine A2B receptor as a novel therapeutic target in asthma

    Holgate, Stephen T

    2005-01-01

    Adenosine is a powerful bronchoconstrictor of asthmatic, but not normal, airways. In vitro studies on isolated human mast cells and basophils revealed that adenosine and selective analogues augmented inflammatory mediator release from mast cells by stimulating A2 receptors. Pharmacological blockade of mast cell mediator release in vivo also attenuated adenosine-induced bronchoconstriction, as did theophylline, by adenosine A2 receptor antagonism. Further in vitro studies revealed that the asthmatic response to adenosine is likely to be mediated via the A2B subtype which is selectively antagonised by enprofylline. Studies in animal models, especially mice, have shown a close synergistic interaction between adenosine, Th2 and airway remodelling responses. The recent description of A2B receptors on human airway smooth muscle cells that mediate cytokine and chemokine release and induce differentiation of fibroblasts into myofibroblasts strengthens the view that adenosine maybe more than an inflammatory mediator in asthma but also participates in airway wall remodelling in this disease. These data have provided a firm basis for developing adenosine A2B receptor antagonists as a new therapeutic approach to this disease. PMID:15980878

  6. The Quintiles Prize Lecture 2004. The identification of the adenosine A2B receptor as a novel therapeutic target in asthma.

    Holgate, Stephen T

    2005-08-01

    Adenosine is a powerful bronchoconstrictor of asthmatic, but not normal, airways. In vitro studies on isolated human mast cells and basophils revealed that adenosine and selective analogues augmented inflammatory mediator release from mast cells by stimulating A(2) receptors. Pharmacological blockade of mast cell mediator release in vivo also attenuated adenosine-induced bronchoconstriction, as did theophylline, by adenosine A(2) receptor antagonism. Further in vitro studies revealed that the asthmatic response to adenosine is likely to be mediated via the A(2B) subtype which is selectively antagonised by enprofylline. Studies in animal models, especially mice, have shown a close synergistic interaction between adenosine, Th2 and airway remodelling responses. The recent description of A(2B) receptors on human airway smooth muscle cells that mediate cytokine and chemokine release and induce differentiation of fibroblasts into myofibroblasts strengthens the view that adenosine maybe more than an inflammatory mediator in asthma but also participates in airway wall remodelling in this disease. These data have provided a firm basis for developing adenosine A(2B) receptor antagonists as a new therapeutic approach to this disease.

  7. Adenosine receptors located in the NTS contribute to renal sympathoinhibition during hypotensive phase of severe hemorrhage in anesthetized rats.

    Scislo, Tadeusz J; O'Leary, Donal S

    2006-11-01

    Stimulation of nucleus of the solitary tract (NTS) A(2a)-adenosine receptors elicits cardiovascular responses quite similar to those observed with rapid, severe hemorrhage, including bradycardia, hypotension, and inhibition of renal but activation of preganglionic adrenal sympathetic nerve activity (RSNA and pre-ASNA, respectively). Because adenosine levels in the central nervous system increase during severe hemorrhage, we investigated to what extent these responses to hemorrhage may be due to activation of NTS adenosine receptors. In urethane- and alpha-chloralose-anesthetized male Sprague-Dawley rats, rapid hemorrhage was performed before and after bilateral nonselective or selective blockade of NTS adenosine-receptor subtypes [A(1)- and A(2a)-adenosine-receptor antagonist 8-(p-sulfophenyl)theophylline (1 nmol/100 nl) and A(2a)-receptor antagonist ZM-241385 (40 pmol/100 nl)]. The nonselective blockade reversed the response in RSNA (-21.0 +/- 9.6 Delta% vs. +7.3 +/- 5.7 Delta%) (where Delta% is averaged percent change from baseline) and attenuated the average heart rate response (change of -14.8 +/- 4.8 vs. -4.4 +/- 3.4 beats/min). The selective blockade attenuated the RSNA response (-30.4 +/- 5.2 Delta% vs. -11.1 +/- 7.7 Delta%) and tended to attenuate heart rate response (change of -27.5 +/- 5.3 vs. -15.8 +/- 8.2 beats/min). Microinjection of vehicle (100 nl) had no significant effect on the responses. The hemorrhage-induced increases in pre-ASNA remained unchanged with either adenosine-receptor antagonist. We conclude that adenosine operating in the NTS via A(2a) and possibly A(1) receptors may contribute to posthemorrhagic sympathoinhibition of RSNA but not to the sympathoactivation of pre-ASNA. The differential effects of NTS adenosine receptors on RSNA vs. pre-ASNA responses to hemorrhage supports the hypothesis that these receptors are differentially located/expressed on NTS neurons/synaptic terminals controlling different sympathetic outputs.

  8. The synthesis of a series of adenosine A3 receptor agonists.

    Broadley, Kenneth J; Burnell, Erica; Davies, Robin H; Lee, Alan T L; Snee, Stephen; Thomas, Eric J

    2016-04-12

    A series of 1'-(6-aminopurin-9-yl)-1'-deoxy-N-methyl-β-d-ribofuranuronamides that were characterised by 2-dialkylamino-7-methyloxazolo[4,5-b]pyridin-5-ylmethyl substituents on N6 of interest for screening as selective adenosine A3 receptor agonists, have been synthesised. This work involved the synthesis of 2-dialkylamino-5-aminomethyl-7-methyloxazolo[4,5-b]pyridines and analogues that were coupled with the known 1'-(6-chloropurin-9-yl)-1'-deoxy-N-methyl-β-d-ribofuranuronamide. The oxazolo[4,5-b]pyridines were synthesized by regioselective functionalisation of 2,4-dimethylpyridine N-oxides. The regioselectivities of these reactions were found to depend upon the nature of the heterocycle with 2-dimethylamino-5,7-dimethyloxazolo[4,5-b]pyridine-N-oxide undergoing regioselective functionalisation at the 7-methyl group on reaction with trifluoroacetic anhydride in contrast to the reaction of 4,6-dimethyl-3-hydroxypyridine-N-oxide with acetic anhydride that resulted in functionalisation of the 6-methyl group. To optimise selectivity for the A3 receptor, 5-aminomethyl-7-bromo-2-dimethylamino-4-[(3-methylisoxazol-5-yl)methoxy]benzo[d]oxazole was synthesised and coupled with the 1'-(6-chloropurin-9-yl)-1'-deoxy-N-methyl-β-d-ribofuranuronamide. The products were active as selective adenosine A3 agonists.

  9. Adenosine A3 Receptor: A promising therapeutic target in cardiovascular disease.

    Nishat, Shamama; Khan, Luqman A; Ansari, Zafar M; Basir, Seemi F

    2016-01-01

    Cardiovascular complications are one of the major factors for early mortality in the present worldwide scenario and have become a major challenge in both developing and developed nations. It has thus become of immense importance to look for different therapeutic possibilities and treatments for the growing burden of cardiovascular diseases. Recent advancements in research have opened various means for better understanding of the complication and treatment of the disease. Adenosine receptors have become tool of choice in understanding the signaling mechanism which might lead to the cardiovascular complications. Adenosine A3 receptor is one of the important receptor which is extensively studied as a therapeutic target in cardiovascular disorder. Recent studies have shown that A3AR is involved in the amelioration of cardiovascular complications by altering the expression of A3R. This review focuses towards the therapeutic potential of A3AR involved in cardiovascular disease and it might help in better understanding of mechanism by which this receptor may prove useful in improving the complications arising due to various cardiovascular diseases. Understanding of A3AR signaling may also help to develop newer agonists and antagonists which might be prove helpful in the treatment of cardiovascular disorder.

  10. How We Manage Adenosine Deaminase-Deficient Severe Combined Immune Deficiency (ADA SCID).

    Kohn, Donald B; Gaspar, H Bobby

    2017-02-14

    Adenosine deaminase-deficient severe combined immune deficiency (ADA SCID) accounts for 10-15% of cases of human SCID. From what was once a uniformly fatal disease, the prognosis for infants with ADA SCID has improved greatly based on the development of multiple therapeutic options, coupled with more frequent early diagnosis due to implementation of newborn screening for SCID. We review the various treatment approaches for ADA SCID including allogeneic hematopoietic stem cell transplantation (HSCT) from a human leukocyte antigen-matched sibling or family member or from a matched unrelated donor or a haplo-identical donor, autologous HSCT with gene correction of the hematopoietic stem cells (gene therapy-GT), and enzyme replacement therapy (ERT) with polyethylene glycol-conjugated adenosine deaminase. Based on growing evidence of safety and efficacy from GT, we propose a treatment algorithm for patients with ADA SCID that recommends HSCT from a matched family donor, when available, as a first choice, followed by GT as the next option, with allogeneic HSCT from an unrelated or haplo-identical donor or long-term ERT as other options.

  11. Adenosine deaminase activity in serum and lymphocytes of rats infected with Sporothrix schenckii.

    Castro, Verônica S P; Pimentel, Victor C; Da Silva, Aleksandro S; Thomé, Gustavo R; Wolkmer, Patrícia; Castro, Jorge L C; Costa, Márcio M; da Silva, Cássia B; Oliveira, Daniele C; Alves, Sydney H; Schetinger, Maria R C; Lopes, Sonia T A; Mazzanti, Cinthia M

    2012-07-01

    Sporotrichosis is a fungal infection of subcutaneous or chronic evolution, inflammatory lesions characterized by their pyogranulomatous aspect, caused by the dimorphic fungus Sporothrix schenckii. Adenosine deaminase (ADA) is a "key" enzyme in the purine metabolism, promoting the deamination of adenosine, an important anti-inflammatory molecule. The increase in ADA activity has been demonstrated in several inflammatory conditions; however, there are no data in the literature associated with this fungal infection. The objective of this study was to evaluate the activity of serum ADA (S-ADA) and lymphocytes (L-ADA) of rats infected with S. schenckii. We used seventy-eight rats divided into two groups. In the first experiment, rats were infected subcutaneously and in the second experiment, infected intraperitoneally. Blood samples for hematologic evaluation and activities of S-ADA and L-ADA were performed at days 15, 30, and 40 post-infection (PI) to assess disease progression. In the second experiment, it was observed an acute decrease in activity of S-ADA and L-ADA (P schenckii alters the activities of S-ADA in experimentally infected rats, demonstrating the involvement of this enzyme in the pathogenesis of sporotrichosis.

  12. The effects of caffeine on sleep in Drosophila require PKA activity, but not the adenosine receptor.

    Wu, Mark N; Ho, Karen; Crocker, Amanda; Yue, Zhifeng; Koh, Kyunghee; Sehgal, Amita

    2009-09-02

    Caffeine is one of the most widely consumed stimulants in the world and has been proposed to promote wakefulness by antagonizing function of the adenosine A2A receptor. Here, we show that chronic administration of caffeine reduces and fragments sleep in Drosophila and also lengthens circadian period. To identify the mechanisms underlying these effects of caffeine, we first generated mutants of the only known adenosine receptor in flies (dAdoR), which by sequence is most similar to the mammalian A2A receptor. Mutants lacking dAdoR have normal amounts of baseline sleep, as well as normal homeostatic responses to sleep deprivation. Surprisingly, these mutants respond normally to caffeine. On the other hand, the effects of caffeine on sleep and circadian rhythms are mimicked by a potent phosphodiesterase inhibitor, IBMX (3-isobutyl-1-methylxanthine). Using in vivo fluorescence resonance energy transfer imaging, we find that caffeine induces widespread increase in cAMP levels throughout the brain. Finally, the effects of caffeine on sleep are blocked in flies that have reduced neuronal PKA activity. We suggest that chronic administration of caffeine promotes wakefulness in Drosophila, at least in part, by inhibiting cAMP phosphodiesterase activity.

  13. The A2B adenosine receptor protects against inflammation and excessive vascular adhesion

    Yang, Dan; Zhang, Ying; Nguyen, Hao G.; Koupenova, Milka; Chauhan, Anil K.; Makitalo, Maria; Jones, Matthew R.; Hilaire, Cynthia St.; Seldin, David C.; Toselli, Paul; Lamperti, Edward; Schreiber, Barbara M.; Gavras, Haralambos; Wagner, Denisa D.; Ravid, Katya

    2006-01-01

    Adenosine has been described as playing a role in the control of inflammation, but it has not been certain which of its receptors mediate this effect. Here, we generated an A2B adenosine receptor–knockout/reporter gene–knock-in (A2BAR-knockout/reporter gene–knock-in) mouse model and showed receptor gene expression in the vasculature and macrophages, the ablation of which causes low-grade inflammation compared with age-, sex-, and strain-matched control mice. Augmentation of proinflammatory cytokines, such as TNF-α, and a consequent downregulation of IκB-α are the underlying mechanisms for an observed upregulation of adhesion molecules in the vasculature of these A2BAR-null mice. Intriguingly, leukocyte adhesion to the vasculature is significantly increased in the A2BAR-knockout mice. Exposure to an endotoxin results in augmented proinflammatory cytokine levels in A2BAR-null mice compared with control mice. Bone marrow transplantations indicated that bone marrow (and to a lesser extent vascular) A2BARs regulate these processes. Hence, we identify the A2BAR as a new critical regulator of inflammation and vascular adhesion primarily via signals from hematopoietic cells to the vasculature, focusing attention on the receptor as a therapeutic target. PMID:16823489

  14. Modulatory effect of iron chelators on adenosine deaminase activity and gene expression in Trichomonas vaginalis.

    Primon-Barros, Muriel; Rigo, Graziela Vargas; Frasson, Amanda Piccoli; Santos, Odelta dos; Smiderle, Lisiane; Almeida, Silvana; Macedo, Alexandre José; Tasca, Tiana

    2015-11-01

    Trichomonas vaginalis is a flagellate protozoan that parasitises the urogenital human tract and causes trichomoniasis. During the infection, the acquisition of nutrients, such as iron and purine and pyrimidine nucleosides, is essential for the survival of the parasite. The enzymes for purinergic signalling, including adenosine deaminase (ADA), which degrades adenosine to inosine, have been characterised in T. vaginalis. In the evaluation of the ADA profile in different T. vaginalis isolates treated with different iron sources or with limited iron availability, a decrease in activity and an increase in ADA gene expression after iron limitation by 2,2-bipyridyl and ferrozine chelators were observed. This supported the hypothesis that iron can modulate the activity of the enzymes involved in purinergic signalling. Under bovine serum limitation conditions, no significant differences were observed. The results obtained in this study allow for the assessment of important aspects of ADA and contribute to a better understanding of the purinergic system in T. vaginalis and the role of iron in establishing infection and parasite survival.

  15. Development of gene therapy: potential in severe combined immunodeficiency due to adenosine deaminase deficiency

    Claudia A Montiel-Equihua

    2009-12-01

    Full Text Available Claudia A Montiel-Equihua, Adrian J Thrasher, H Bobby GasparCentre for Immunodeficiency, Molecular Immunology Unit, UCL Institute of Child Health, London, UKAbstract: The history of stem cell gene therapy is strongly linked to the development of gene therapy for severe combined immunodeficiencies (SCID and especially adenosine deaminase (ADA-deficient SCID. Here we discuss the developments achieved in over two decades of clinical and laboratory research that led to the establishment of a protocol for the autologous transplant of retroviral vector-mediated gene-modified hematopoietic stem cells, which has proved to be both successful and, to date, safe. Patients in trials in three different countries have shown long-term immunological and metabolic correction. Nevertheless, improvements to the safety profile of viral vectors are underway and will undoubtedly reinforce the position of stem cell gene therapy as a treatment option for ADA-SCID.Keywords: adenosine deaminase, severe combined immunodeficiency, gene therapy, hematopoietic stem cell, retrovirus, clinical trial

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

    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.

  17. Role of 5-hydroxytryptamine in mediating adenosine-induced airway contraction.

    Matera, M G; De Santis, D; D'Agostino, B; Pallotta, M; Vacca, C; Cazzola, M; Rossi, F

    1995-02-01

    We have investigated the role of 5-hydroxytryptamine (5-HT) on adenosine-induced guinea-pig trachea contraction. R-N6-phenylisopropyladenosine (R-PIA), an A1 receptor subtype agonist, induced a concentration-dependent contraction of tracheal rings. The pD2 values were 7.43 +/- 0.26. A 30-min pretreatment with 1,3-dipropyl-8-amino-4-clorophenylxantine (PACPX), a selective A1 receptor antagonist, shifted to the right the R-PIA concentration effect curves. Ketanserin (1 microM), a 5-HT2 receptor antagonist, also caused a rightward shift of the R-PIA concentration-effect curves. The changes for the pD2 values comparing the controls and the tissues incubated with ketanserin were statistically significant (P diphenydramine (1 microM), nor indomethacin (5 microM) showed any effects. The challenge of R-PIA (1 microM) with said substances induced a release of 5-HT (4.8 +/- 0.20 fmol/ml) from guinea-pig trachea in presence or in absence of epithelium; in the same experimental conditions, this effect did not occur in the controls. Our data support the hypothesis that 5-HT plays a role in adenosine-induced airway contraction.

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

    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. Transport of A1 adenosine receptor agonist tecadenoson by human and mouse nucleoside transporters: evidence for blood-brain barrier transport by murine equilibrative nucleoside transporter 1 mENT1.

    Lepist, Eve-Irene; Damaraju, Vijaya L; Zhang, Jing; Gati, Wendy P; Yao, Sylvia Y M; Smith, Kyla M; Karpinski, Edward; Young, James D; Leung, Kwan H; Cass, Carol E

    2013-04-01

    The high density of A1 adenosine receptors in the brain results in significant potential for central nervous system (CNS)-related adverse effects with A1 agonists. Tecadenoson is a selective A1 adenosine receptor agonist with close similarity to adenosine. We studied the binding and transmembrane transport of tecadenoson by recombinant human equilibrative nucleoside transporters (hENTs) hENT1 and hENT2, and human concentrative nucleoside transporters (hCNTs) hCNT1, hCNT2, and hCNT3 in vitro and by mouse mENT1 in vivo. Binding affinities of the five recombinant human nucleoside transporters for tecadenoson differed (hENT1 > hCNT1 > hCNT3 > hENT2 > hCNT2), and tecadenoson was transported largely by hENT1. Pretreatment of mice with a phosphorylated prodrug of nitrobenzylmercaptopurine riboside, an inhibitor of mENT1, significantly decreased brain exposure to tecadenoson compared with that of the untreated (control) group, suggesting involvement of mENT1 in transport of tecadenoson across the blood-brain barrier (BBB). In summary, ENT1 was shown to mediate the transport of tecadenoson in vitro with recombinant and native human protein and in vivo with mice. The micromolar apparent Km value of tecadenoson for transport by native hENT1 in cultured cells suggests that hENT1 will not be saturated at clinically relevant (i.e., nanomolar) concentrations of tecadenoson, and that hENT1-mediated passage across the BBB may contribute to the adverse CNS effects observed in clinical trials. In contrast, in cases in which a CNS effect is desired, the present results illustrate that synthetic A1 agonists that are transported by hENT1 could be used to target CNS disorders because of enhanced delivery to the brain.

  20. Tachy-Brady Arrhythmias: The Critical Role of Adenosine-induced Sino-Atrial Conduction Block in Post-Tachycardia Pauses

    Lou, Qing; Glukhov, Alexey V.; Hansen, Brian; Hage, Lori; Vargas-Pinto, Pedro; Billman, George E.; Carnes, Cynthia A.; Fedorov, Vadim V.

    2012-01-01

    Background In patients with sinoatrial nodal (SAN) dysfunction, atrial pauses lasting several seconds may follow rapid atrial pacing or paroxysmal tachycardia (tachy-brady arrhythmias). Clinical studies suggest that adenosine may play an important role in SAN dysfunction, but the mechanism remains unclear. Objective To define the mechanism of SAN dysfunction induced by the combination of adenosine and tachycardia. Methods We studied the mechanism of SAN dysfunction produced by a combination of adenosine and rapid atrial pacing in isolated coronary-perfused canine atrial preparations using high-resolution optical mapping (n=9). Sinus cycle length (SCL) and sinoatrial conduction time (SACT) were measured during adenosine (1–100μM) and 1μM DPCPX (A1 receptor antagonist, n=7) perfusion. Sinoatrial node recovery time was measured after one minute of “slow” pacing (3.3Hz) or tachypacing (7–9Hz). Results Adenosine significantly increased SCL (477±62 vs. 778±114 ms, p<0.01), and SACT during sinus rhythm (41±11 vs. 86±16 ms, p<0.01) dose-dependently. Adenosine dramatically affected SACT of the first SAN beat after tachypacing (41±5 vs. 221±98ms, p<0.01). Moreover, at high concentrations of adenosine (10–100μM), termination of tachypacing or atrial flutter/fibrillation produced atrial pauses of 4.2±3.4 seconds (n=5) due to conduction block between the SAN and atria, despite a stable SAN intrinsic rate. Conduction block was preferentially related to depressed excitability in SAN conduction pathways. Adenosine-induced changes were reversible upon washout or DPCPX treatment. Conclusions These data directly demonstrate that adenosine contributes to post-tachycardia atrial pauses through SAN exit block rather than slowed pacemaker automaticity. Thus, these data suggest an important modulatory role of adenosine in tachy-brady syndrome. PMID:22985657

  1. Evaluation of coronary artery disease using myocardial thallium-201 imaging with single photon emission computed tomography during adenosine induced coronary vasodilation

    Abe, Shinya; Takeishi, Yasuchika; Chiba, Junya; Tonooka, Ichiro; Tomoike, Hitonobu (Yamagata Univ. (Japan). School of Medicine)

    1993-02-01

    Adenosine-loaded Tl-201 myocardial SPECT was performed in consecutive 55 patients with suspected ischemic heart disease. Among these patients, 22 had cuncurrently exercise Tl-201 myocardial SPECT imaging for comparison. Adenosine was intravenously injected at a dose of 0.14 mg/kg/min continuously for 6 min, and 3 min after the stard of injection Tl-201 was injected via the different vein. Myocardial SPECT images were acquired at 5 min and 3 hr after the completion of intravenous injection of adenosine. Perfusion defect and the presence or absence of redistribution (RD) were visually interpreted from the short- and long-axial tomograms. Relative Tl-201 regional uptake ratios were quantitatively determined. Decreased systolic arterial pressure, increased heart rate, and slightly increased rate-pressure product were observed with adenosine injection. Chest pain (13 patients), head-ache (7), ST depression (17), and A-V block II were also seen; however, these symptoms rapidly disappeared with the withdrawal of adenosine. The findings by adenosine loading were concordent with those by exercise loading (91% for perfusion defect and 86% for presence or absence of RD). According to segments, both loading tests were concordent in 90% for persusion and 89% for RD. Both adenosine- and exercise-loaded imagings correlated well with regional Tl uptake by segements, the lowest value of Tl-201 defect, and extent score of Tl-201 defect. Adenosine-loaded imaging had a sensitivity of 100%, a specificity of 88%, and an accuracy of 97% for detecting parenchymal coronary lesions in evaluable 39 patients. In evaluable 22 patient