bluuebunny/crossref_metadata_2025_split huggingface dataset:
Immunological characterization of A2B adenosine receptors in human mast cells
Authors: Feoktistov Igor , Goldstein Anna , Sheller James R. , Schwartz Lawrence B. , Biaggioni Italo 
Published: May 2003

AbstractThere is increasing evidence that adenosine modulates mast cell function. Such an interaction may be particularly important in asthma. Inhaled adenosine provokes bronchoconstriction in asthmatic patients through processes associated with mast cell activation. The adenosine receptor type that mediates these actions has not been identified. For this purpose, we generated antibodies against a 22‐mer peptide corresponding to C‐terminus of the human A2B adenosine receptor. This antibody recognized adenosine A2B receptors on Western blots as a band with an apparent molecular mass of 31kDa, and a smear of immunoreactivity in the region from 60 to 130kDa. Enzymatic deglycosylation of adenosine A2B receptor, or prevention of natural glycosylation with tunicamycin resulted in accumulation of protein with an apparent molecular mass of 29kDa. The specificity of this antibody was confirmed in experiments with HA‐tagged A2B receptor fusion protein. Anti‐HA and anti‐A2B antibodies, used for immunoprecipitation and Western blotting of the fusion protein, labeled the same glycoprotein in membranes of transfected, but not mock‐transfected cells. These antibodies were also found useful in immunocytochemistry, as evidenced by specific staining of cells expressing A2B, but not other subtypes of adenosine receptors. Human lung mast cells obtained from bronchoalveolar lavage fluid of asthmatic patients were identified by specific monoclonal anti‐tryptase antibody. Double immunostaining demonstrated expression of A2B receptors in tryptase‐positive cells. Our results, therefore, demonstrate the presence of A2B receptors in human lung mast cells and support the hypothesis that A2B receptors are involved in activation of mast cells in asthma. Drug Dev. Res. 58:461–471, 2003. © 2003 Wiley‐Liss, Inc.
Intracellular phosphorylation of chloro‐adenosine analogs is a prerequisite for activation of caspase‐3 and induction of apoptosis in human astrocytoma cells
Authors: Ceruti Stefania , Mazzola Alessia , Beltrami Elena , Passera Davide , Piantoni Elena , Cattabeni Flaminio , Abbracchio Maria P. 
Published: May 2003

AbstractWe previously demonstrated that both Cladribine (2‐chloro‐deoxyadenosine) and the related compound 2‐chloroadenosine induce apoptosis of human astrocytoma cells (Ceruti et al. [2000] J Neurosci Res 60:388–400). In the present study we have characterized the role of the most important “effector” caspase (caspase‐3) in the same experimental model and the relationship between the intracellular phosphorylation of the two adenosine analogs and activation of this enzyme. Data show that: 1) both adenosine analogs can activate caspase‐3 in a time‐dependent fashion; 2) significant activation of the enzyme (i.e., 6–7‐fold over control level) can be detected before any appearance of nuclear signs of apoptosis; 3) the degree of caspase‐3 activation is proportional to the percentage of apoptosis at the end of the incubation period, suggesting a causal relationship between enzyme activation and induction of cell death; and 4) both activation of caspase‐3 and induction of cell death can be completely prevented by preexposure of cultures to inhibitors of the intracellular phosphorylation of 2‐chloroadenosine and 2‐chloro‐2′‐deoxyadenosine (namely, 5‐iodotubercidin and 2′‐deoxycytidine, respectively). Adenosine analogs act, therefore, as prodrugs and the toxic species are represented by the corresponding chloro‐nucleotides. The pathways upstream of caspase‐3 activation in human astrocytoma cells still remain to be elucidated. Taken together, these data strongly suggest a possible use of adenosine analogs in the pharmacological treatment of central nervous system tumors and of all tumors characterized by a high activity of nucleoside kinases leading to selective intracellular accumulation of toxic chloro‐nucleotides. Drug Dev. Res. 58:396–404, 2003. © 2003 Wiley‐Liss, Inc.
Dissecting the regulatory mechanisms controlling inhibitory adenosine receptor signaling
Authors: Palmer Timothy M. , Ferguson Gail , Watterson Kenneth R. 
Published: May 2003

AbstractThe ability of target cells to respond to rapid changes in extracellular adenosine concentrations that occur in response to ischemia is determined by their complement of adenosine receptors. Four adenosine receptor subtypes, termed A1, A2A, A2B, and A3, have been identified by pharmacological and molecular cloning studies. In addition to displaying distinct pharmacological characteristics, each receptor mediates its intracellular effects by coupling to defined G‐protein families. Our studies have concentrated on applying a combination of molecular biological, biochemical, and cell biological approaches to define the molecular mechanisms by which adenosine receptor‐derived signaling events are regulated. These studies have revealed that the desensitization of closely related adenosine receptors, which bind the same agonist in vivo (i.e., adenosine) and activate the same family of G proteins, is mediated by unique receptor‐specific mechanisms. In this review, the nature of these differences, and how they could potentially be exploited to test novel strategies for enhancing the cardioprotective effects of inhibitory adenosine receptor activation in vivo, will be described. Drug Dev. Res. 58:302–314, 2003. © 2003 Wiley‐Liss, Inc.
Adenosine A3 receptors in the rat hippocampus: Lack of interaction with A1 receptors
Authors: Lopes Luísa V. , Rebola Nelson , Costenla Ana Rita , Halldner Linda , Jacobson Marlene A. , Oliveira Catarina R. , Richardson Peter J. , Fredholm Bertil B. , Ribeiro Joaquim A. , Cunha Rodrigo A. 
Published: May 2003

AbstractAdenosine acts as a neuromodulator in the hippocampus essentially through activation of inhibitory A1 receptors. Using single‐cell PCR analysis, we found that CA1 pyramidal cells coexpress A1 receptor mRNA together with that of another adenosine receptor, the A3 receptor. As occurs for the A1 receptor, Western blot analysis indicated that the A3 receptor is also located in hippocampal nerve terminals. However, activation of A3 receptors with its purportedly selective agonist Cl‐IBMECA (0.1–10 µM) failed to affect hippocampal synaptic transmission or to modify the evoked release of glutamate or GABA. Also, blockade of A3 receptors with MRS 1191 (5 µM) failed to affect either hypoxia‐ or ischemia‐induced depression of hippocampal synaptic transmission. Activation of A3 receptors also failed to control A1 receptor function, as Cl‐IBMECA (100 nM) did not modify the ability of CPA to displace [3H]DPCPX binding to hippocampal membranes or the A1 receptor‐mediated inhibition of hippocampal synaptic transmission. However, ligand binding studies revealed that Cl‐IBMECA displaced the binding of an A1 receptor agonist ([3H]R‐PIA, Ki=47 nM) or antagonist ([3H]DPCPX, Ki=130 nM), which suggests that A3 receptor ligands also act on native A1 receptors. We believe that A3 receptors are expressed in hippocampal neurons and are located in hippocampal nerve terminals, though their function remains elusive. Drug Dev. Res. 58:428–438, 2003. © 2003 Wiley‐Liss, Inc.
Cardioprotection with pre‐ and postischemic adenosine and A3 receptor activation: Differing mechanisms and effects on necrosis versus stunning
Authors: Flood Amanda , Willems Laura , Headrick John P. 
Published: May 2003

AbstractThe importance of pre‐ versus postischemic treatment in adenosine‐mediated cardioprotection is unclear. We characterized effects of pre‐ and postischemic adenosine or A3 adenosine receptor (A3AR) agonism in Langendorff perfused mouse hearts subjected to 20 min global ischemia and 45 min reperfusion. In untreated hearts, diastolic pressure remained elevated at 21±2 mmHg, ventricular pressure development recovered to 75±3 mmHg (50% of pre‐ischemia), and 24±3 IU/ lactate dehydrogenase (LDH) was lost. Adenosine (50 µM) treatment prior to ischemia reduced LDH efflux by 40% (15±2 IU/g) yet exerted only modest effects on recovery of force (83±2 mmHg). Additional treatment during the first 15 min reperfusion was no more effective in reducing LDH efflux (14±2 IU/g) but further limited contractile dysfunction (93±2 mmHg). Continued treatment throughout 45 min reperfusion most effectively limited LDH efflux (10±1 IU/g) and contractile dysfunction (124±6 mmHg). Some protection was also observed with treatment during reperfusion only (16±1 IU/g and 106±3 mmHg). Effects of pre‐ and postischemic adenosine on necrosis and contractile dysfunction were not mimicked by pre‐ and postischemic A3AR agonism with 100 nM 2‐chloro‐N6‐(3‐iodobenzyl)‐adenosine‐5′‐N‐methyluronamide (Cl‐IB‐MECA), or mitochondrial KATP channel activation with 50 µM diazoxide. Protection with Cl‐IB‐MECA and diazoxide was less than with adenosine, maximal with treatment during ischemia alone, and absent with treatment during reperfusion alone. Data indicate antinecrotic effects of adenosine are primarily mediated prior to and during ischemia and are consistent with A3AR and mitochondrial KATP channel activation. In contrast, protection against contractile dysfunction involves other mechanisms and is enhanced with prolonged postischemic treatment. Drug Dev. Res. 58:447–453, 2003. © 2003 Wiley‐Liss, Inc.
Nucleotides and dinucleotides in ocular physiology: New possibilities of nucleotides as therapeutic agents in the eye
Authors: Pintor Jesús , Peral Assumpta , Peláez Teresa , Carracedo Gonzalo , Bautista Alfredo , Hoyle Charles H. V. 
Published: May 2003

AbstractNucleotides and dinucleotides have interesting physiological actions in the eye. The involvement of these naturally occurring substances in processes such as tear secretion, intraocular pressure, corneal wound healing, or retinal detachment is discussed. Nucleotides are present in rabbit and human tears and they exert interesting effects, such as increasing tear secretion and augmenting the rate of re‐epithelialisation. Nucleotides and dinucleotides are present in the aqueous humour, and they can modify the production or drainage of the aqueous humour and therefore affect the intraocular pressure. In the retinal space, nucleotides can modify the activity of both neuronal and glial retinal elements in different ways. Some chemically modified nucleotides and dinucleotides can be more active than the natural ones, opening up the possibility of using them for clinical purposes. In particular, compounds designed for dry eye syndrome, ocular hypertension, and retinal detachment are under study with very promising results. In summary, these compounds are becoming more relevant to the understanding of ocular physiology and also as a novel strategy for the treatment of ocular pathologies. Drug Dev. Res. 59:136–145, 2003. © 2003 Wiley‐Liss, Inc.
Modeling the response of the asthmatic airways to adenosine: Mechanisms and receptors
Authors: Fozard John R. , Tigani Bruno , Wolber Cedric , Williams Iwan , Mazzoni Lazzaro , Hannon Jason P. 
Published: May 2003

AbstractWe describe a new experimental animal model which mimics closely the bronchoconstrictor effects of adenosine in asthmatics. Brown Norway (BN) rats were sensitized to ovalbumin (OA). Subsequent challenge with OA induced a marked and selective airway hyperresponsiveness to adenosine. The augmented response to adenosine was blocked selectively by disodium cromoglycate, methysergide, and theophylline and associated with increases in the plasma concentrations of histamine and 5‐HT and degranulation of airway mast cells. The broad‐spectrum adenosine receptor agonist, NECA, also induced bronchoconstriction in actively sensitized (AS), OA‐challenged animals, whereas agonists selective for A1, A2A, and A3 receptors induced minimal effects. MRS 1754, which has similar affinity for rat A2B and A1 receptors, failed to block the response to adenosine, despite blocking the A1 receptor‐mediated bradycardia‐induced by NECA. 8‐SPT and CGS 15943, antagonists at A1, A2A, and A2B but not A3 receptors, inhibited the bronchoconstrictor response to adenosine by 3‐fold but only at doses yielding plasma concentrations 139 and 21 times greater than their respective KB values at the rat A2B receptor. Adenosine and NECA, but not CPA, CGS 21680, or 2‐Cl‐IB‐MECA, induced contraction of parenchymal strip preparations from AS, OA‐challenged animals. Responses to adenosine could not be antagonized by 8‐SPT or MRS 1754 at concentrations≥50 times their affinities at the rat A2B receptor. Upregulation by allergic activation, mast cell dependency, and selective blockade by theophylline represent striking similarities between the bronchoconstrictor response to adenosine in the BN rat and that on the airways of asthmatics. However, the receptor mediating the response in the rat cannot be categorized as one of the four recognized adenosine receptor subtypes. Drug Dev. Res. 59:23–29, 2003. © 2003 Wiley‐Liss, Inc.
P2Y receptors: New subtypes, new functions
Authors: Boeynaems Jean‐Marie , Wilkin Françoise , Marteau Frédéric , Duhant Xavier , Savi Pierre , Suarez Gonzalez Nathalie , Robaye Bernard , Communi Didier 
Published: May 2003

AbstractThe orphan receptor GPR86 was recently identified as a new ADP receptor coupled to Gi and named P2Y13. This brings to eight the number of genuine P2Y receptors. On the basis of sequence homology, they can be subdivided into two subgroups: P2Y1, P2Y2, P2Y4, P2Y6, and P2Y11; and P2Y12, P2Y13, and the UDP‐glucose receptor that should be renamed P2Y14. Some pharmacological properties of the P2Y13 receptor are significantly different from those of the P2Y12 receptor:• ATP and 2MeSATP behaved as weak partial agonists.• Potency of 2MeSADP was greater than or equal to that of ADP, depending on the expressing cell line and signaling pathway studied.• AR‐C67085MX behaved as an antagonist, but only with a µM potency as compared to nM at the P2Y12 receptor.• The active metabolite of clopidogrel had no effect.Expression of P2Y13 mRNA was highest in brain, spleen, and various types of leukocytes, in particular dendritic cells. Recent results underscore the role of other P2Y receptors, especially P2Y11, in dendritic cell biology. Indeed, ATP and other nucleotides have multiple effects on human dendritic cells: potentiation of maturation, potentiation, or inhibition of IL‐12p40 secretion (depending on the level of stimulation), inhibition of IL‐12p70 production, potentiation of IL‐10 secretion, and modulation of the repertoire of expressed chemokines and chemokine receptors. These actions are mediated by a rise in cAMP and the rank order of potency of various nucleotides is consistent with the involvement of the P2Y11 receptor. On the other hand, several nucleotides inhibit the proliferation of human CD4+ T‐cells and their secretion of cytokines: these actions also involve a rise in cAMP, apparently mediated by a receptor other than P2Y11. These actions are reminiscent of those of PGE2 and might represent a protective mechanism operating during an exaggerated inflammatory response, when large amounts of nucleotides are released from damaged and dying cells. Drug Dev. Res. 59:30–35, 2003. © 2003 Wiley‐Liss, Inc.
Signalling pathways and ion channel regulations of P2Y receptors
Authors: Barnard Eric A. , Simon Joseph , Tsim Karl W.K. , Filippov Alexander K. , Brown David A. 
Published: May 2003

AbstractThe P2Y receptors form a particularly diverse family of nucleotide receptors, whose current status is briefly reviewed here. A recent addition, the P2Y12 receptor, is of particular interest for its significance for blood coagulation and for some unusual behaviour of its ligand potencies. Strong antagonists for it in the platelet can become strong agonists in its recombinant expression. We have cloned it also from a capillary endothelial cell line, again with similar variation from the behaviour in the platelet. The P2Y receptors are shown to couple to several types of ion channels, as significant new transductions for them. Comparison between subtypes in these properties is illuminating. The downstream signalling of the P2Y1 receptor has been studied and these properties are considered, with an approach to comparing native and recombinant transduction behaviours. Evidence for a role of the P2Y1 receptor in synaptogenesis is also presented, with actions at the level of gene transcription. Drug Dev. Res. 59:36–48, 2003. © 2003 Wiley‐Liss, Inc.
ATP induced three types of pain behaviors, including allodynia
Authors: Inoue Kazuhide , Tsuda Makoto , Koizumi Schuichi 
Published: May 2003

AbstractATP excites dorsal root ganglion (DRG) neurons in the nociceptive signaling pathway via ATP‐gated cation channels (P2X receptors). ATP and its analog α,β‐methylene ATP (αβmeATP) activated two types of inward currents; one is a rapidly desensitizing current which is observed in capsaicin (CAP)‐sensitive DRG neurons and in C6BU‐1 cells expressing homomeric P2X3 receptors. The other is a slowly desensitizing current which is seen in CAP‐insensitive medium‐sized DRG neurons and in C6BU‐1 expressing heteromeric P2X2/3 receptors. These findings suggest that P2X3 and P2X2/3 are involved in the generation or modulation of pain. To clarify this hypothesis, we investigated the effects of agonists for P2X receptors on pain sensitivities using a behavioral approach. Activation of P2X receptors at a peripheral site by the injection of ATP or αβmeATP into the hindpaw produced three distinct types of pain‐related behaviors (nocifensive behavior, thermal hyperalgesia, and mechanical allodynia). Nocifensive behavior and thermal hyperalgesia were blocked by pretreatment with PPADS and were not observed in neonatal CAP‐treated adult rats that had selectively lost CAP‐sensitive neurons. The αβmeATP‐induced allodynia was sensitive to PPADS, was a relatively long‐lasting response, and remained in neonatal CAP‐treated adult rats. Furthermore, while pretreatment by P2X3 antisense oligodeoxynucleotide (ODN) diminished all three pain responses, P2X2 antisense ODN inhibited only the mechanical allodynia. These findings suggests that activation of homomeric P2X3 receptors in peripheral terminals of CAP‐sensitive primary afferent fibers plays a role in the induction of nocifensive behavior and thermal hyperalgesia and that activation of heteromeric P2X2/3 receptors in CAP‐insensitive fibers leads to the induction of mechanical allodynia. Drug Dev. Res. 59:56–63, 2003. © 2003 Wiley‐Liss, Inc.
Flavonoids — novel lead compounds for the development of P2Y2 receptor antagonists
Authors: Kaulich Marko , Streicher Franziska , Mayer Ralf , Müller Ingrid , Müller Christa E. 
Published: May 2003

AbstractA series of 40 flavonoids were investigated as antagonists at P2Y2 receptors expressed in NG108‐15 cells (mouse neuroblastoma×rat glioma hybrid cell line) in a functional assay measuring the inhibition of UTP‐stimulated intracellular calcium release. Several flavonoids were identified as potent antagonists at P2Y2 receptors with IC50 values in the low micromolar concentration range; they were similarly potent or more potent than the standard P2Y2 antagonists Reactive Blue 2 and suramin. Flavone derivatives proved to be more potent than flavanones. The flavone derivatives catechin and epicatechin were inactive. However, a bicyclic benzopyranone ring system was found to be not an absolute prerequisite for P2Y2 antagonism, since the chalcone derivative β‐oxo‐aurentiacin (14) was also relatively potent (IC50 19 µM). Investigated flavone glycosides were completely inactive. The most potent P2Y2 receptor antagonists of the present series were kaempferol (19), heptamethoxyflavon (29), and tangeretin (25), with IC50 values between 6–19 µM. Increased lipophilicity by introducing (additional) methyl groups did not generally increase antagonistic potency. Structure–activity relationships proved to be complex. Concentration–response curves for the P2Y2 agonist UTP were not shifted to the right in the presence of increasing concentrations of tangeretin (25), and EC50 values for UTP were not affected by the antagonist, but the amplitude of the response was reduced, indicating allosteric antagonism. In conclusion, we have identified flavonoids as novel lead structures for the development of noncompetitive antagonists at P2Y2 receptors, which may be of interest as potential antiinflammatory drugs. Drug Dev. Res. 59:72–81, 2003. © 2003 Wiley‐Liss, Inc.
P2X7 Receptor‐induced generation of reactive oxygen species in rat mesangial cells
Authors: Harada H. , Tsukimoto M. , Ikari A. , Takagi K. , Suketa Y. 
Published: May 2003

AbstractApoptosis of mesangial cells is an important mode of cell death that maintains normal morphology and function within the glomerulus during development and in normal cell turnover; it is also important in pathological processes. Stimulation of rat mesangial cells via P2X7 receptors can induce apoptotic cell death. However, the signaling pathways are not well understood. Recently, Suh et al. reported P2X7 receptor‐mediated generation of reactive oxygen species (ROS). Generations of ROS have been linked to induction of apoptosis. In this study, we characterized the P2X7 receptor‐induced ROS generation in rat mesangial cells. P2X7 agonist, 2′ and 3′‐O‐(4‐benzoyl) benzoyl‐ATP (BzATP) evoked ROS generation in a concentration‐dependent manner. The profile of ROS generation in response to BzATP was characteristic of the activation of NADPH oxidase. We could also detect BzATP‐induced production of peroxynitrite. These results suggested that the superoxide anion was generated primarily, and then it rapidly reacted with endogenous nitric oxide, yielding peroxynitrite. The generation of ROS in rat mesangial cells may contribute to P2X7 receptor‐induced apoptotic cell death. Drug Dev. Res. 59: 112–117, 2003. © 2003 Wiley‐Liss, Inc.
Involvement of P2X2 and P2X3 receptors in neuropathic pain in a mouse model of chronic constriction injury
Authors: Ueno Shinya , Moriyama Tomoko , Honda Kenji , Kamiya Hiro‐o , Sakurada Tsukasa , Katsuragi Takeshi 
Published: May 2003

AbstractIn the present study, we examined the involvement of P2X receptors in neuropathic pain using the chronic constriction injury (CCI) model. The thermal and mechanical nociceptive thresholds were evaluated using the paw withdrawal test and a von Frey test, respectively. Also, the expression of P2X receptors in the dorsal root ganglia (DRG) was analyzed using quantitative real‐time RT‐PCR. In the acute stage of CCI (3–30 days after injury), thermal hyperalgesia and mechanical allodynia had developed and mRNA of P2X2 and P2X3 was upregulated in the ipsilateral DRG. The thermal hyperalgesia at 7 days was inhibited by intrathecal (i.t.) administration of P2X antagonists, pyridoxal‐phosphate‐6‐azophenyl‐2′,4′‐disulfonate (PPADS), 2′‐O‐(trinitrophenyl)adenosine 5′‐triphosphate, trisodium salt (TNP‐ATP) and diinosine pentaphosphate (IP5I). In contrast, mechanical allodynia (7 days) was inhibited by the i.t. administration of PPADS and TNP‐ATP but not IP5I. These pharmacological and gene expression data suggest that upregulated homomeric P2X3 and heteromeric P2X2 and P2X3 (P2X2/3) receptors augmented thermal hyperalgesia and mechanical allodynia, respectively, at the spinal level in acute stage of CCI. In the chronic stage (>40 days), thermal hyperalgesia disappeared but the mechanical allodynia persisted. Only P2X3 mRNA was downregulated. PPADS and TNP‐ATP failed to restore the mechanical threshold to the normal level. These data suggest that the involvement of P2X receptors changed in the chronic stage of CCI. Drug Dev. Res. 59:104–111, 2003. © 2003 Wiley‐Liss, Inc.