bluuebunny/crossref_metadata_2025_split huggingface dataset:
A3receptors in cortical neurons: Pharmacological aspects and neuroprotection during hypoxia
Authors: Lewerenz A. , Hentschel S. , Vissiennon Z. , Michael S. , Nieber K. 
Published: May 2003

AbstractAdenosine, which is released under pathophysiological conditions such as hypoxia or ischemia, is involved in a variety of regulatory processes related to neuroprotection. Major advances in the research on neuronal adenosine receptors have provided a better understanding of the mechanisms underlying the neuroprotective effects during hypoxia. The therapeutic potential of adenosine was recognized several years ago, but only the development of stable and selective adenosine receptor agonists and antagonists has offered novel approaches for the pharmacological manipulation of the receptor activity. To date, four G protein coupled receptors have been cloned and identified in the central nervous system: A1, A2A, A2B, and A3.The neuroprotective effects of adenosine are mediated primarily by the activation of A1receptors. Knowledge of the physiological role of A3receptors in the brain is still limited. This article focuses on new evidences referring to possible functions of A3receptors in the CNS, especially the role during hypoxia. Electrophysiological investigations on brain slices give us new insights concerning mechanisms of synaptic modulation. The data from pyramidal cells of the rat cingulate cortex show that a high level of endogenous adenosine (occuring during hypoxia) activates A3receptors, which mediates a depression of the synaptic transmission. The A3receptors inhibit the glutamate release additionally to and independently from the A1receptors. The two distinct mechanisms of synaptic modulation contribute to the neuroprotective action of adenosine during hypoxia and offer new approaches for therapeutic strategies. Drug Dev. Res. 58:420–427, 2003. © 2003 Wiley‐Liss, Inc. © 2003 Wiley‐Liss, Inc.
Mechanisms of cardiac protection with Overexpression of A1 adenosine receptors
Authors: Lankford Amy R. , Cerniway Rachael J. , Regan Sara E. , Crawford Marguerite M. , Byford Anne M. , Matherne G. Paul 
Published: May 2003

AbstractMyocardial damage from ischemia/reperfusion injury can be minimized through endogenous protective mechanisms, including activation of A1 adenosine receptors. Transgenic mice with cardiac‐specific A1 adenosine receptor overexpression (A1AR Trans) have demonstrated functional and metabolic tolerance to in vitro and in vivo myocardial ischemia/reperfusion injury. The purpose of this investigation is to examine the role of p38 MAP kinase in A1 receptor‐mediated cardioprotection. Activation of p38 MAPK by A1 adenosine receptor stimulation was evaluated in neonatal rat cardiomyocytes subjected to simulated ischemia. A1 activation by cyclopentyladenosine decreased cell death and simultaneously enhanced p38 phosphorylation by simulated ischemia. The role of p38 MAP kinase activation in cardioprotection with A1 adenosine receptor overexpression was evaluated in isolated perfused hearts from A1AR Trans mice subjected to 20 min ischemia and 30 min reperfusion. Inhibition of p38 MAPK activity with 10 μM SB‐203580 prior to ischemia and during reperfusion decreased postischemic total functional recovery in A1AR Trans hearts from 54 ± 1 to 27±7% of maximal and increased final EDP from 10±3 mmHg to 34±8 mmHg. A1 adenosine receptor‐mediated activation of p38 MAP kinase in cardiomyocytes is involved in the protection of cells from ischemic death. Tolerance to ischemic injury by A1 receptor overexpression is dependent upon activation of p38 MAPK. These findings suggest that adenosine A1 mediated cardioprotection in transgenic mice involves activation of the p38 MAP kinase cascade. Drug Dev. Res. 58:439–446, 2003. © 2003 Wiley‐Liss, Inc.
ATP release and effects in pancreas
Authors: Novak Ivana , Amstrup Jan , Henriksen Katrine L. , Hede Susanne E. , Sørensen Christiane E. 
Published: May 2003

AbstractATP and other nucleotides are released from various cells, but the pathway and physiological stimulus for ATP release are often unclear. The focus of our studies is the understanding of ATP release and signaling in rat exocrine pancreas. In acinar suspension mechanical stimulation, hypotonic shock and, most importantly, cholinergic stimulation released 5–20nM ATP into the medium, as monitored by luminescence of the luciferin/luciferase reaction. ATP release was visualized at the single acinus level as luciferin consumption detected by confocal laser scanning microscopy (CLSM). The estimated ATP concentrations were higher, about 10µM, around acinar cells after cholinergic stimulation. Fluorescence of quinacrine and MANT‐ATP indicated that some ATP is stored in secretory granules. Pancreatic acini have transcripts for P2X1, P2X4, P2Y2, and P2Y4 receptors, but measurements of Ca2+ signals in isolated acini using Fura‐2 and CLSM revealed that only about 15% of acini respond to extracellular ATP or UTP. Hence, in acini only a few P2 receptors are functional and the distribution seems heterogenous. In contrast, pancreatic ducts have transcripts for P2Y2, P2Y4, P2X4, and P2X7 receptors that consistently increase intracellular Ca2+. Patch‐clamp studies show that P2Y2/P2Y4 receptors inhibit K+ channels, and thus downregulate secretion. P2X4/P2X7 channels stimulate Na+/Ca2+ influx and may upregulate secretion by yet unknown mechanisms. Taken together, our studies show that pancreatic acini release ATP, primarily in response to cholinergic stimulation, and thus ATP may be a paracrine mediator between pancreatic acini and ducts. Drug Dev. Res. 59:128–135, 2003. © 2003 Wiley‐Liss, Inc.
Expression of multiple P2Y receptors by MDCK‐D1 cells: P2Y1 receptor cloning and signaling
Authors: Hughes Richard J. , Torres Brian , Zambon Alexander , Arthur David , Bohmann Christine , Rump L. Christian , Insel Paul A. 
Published: May 2003

AbstractThe Madin Darby canine kidney (MDCK) cell line, a well‐differentiated renal epithelial cell line, is a useful model to examine P2Y receptor signaling and response. Our studies with MDCK‐D1, a clonal isolate, demonstrate that these cells release ATP in response to mechanical stimulation and activation of certain G‐protein‐coupled receptors. Reverse transcriptase‐polymerase chain reaction (RT‐PCR) studies document that MDCK cells express multiple P2Y receptors, including P2Y1, P2Y2, P2Y6, and P2Y11 receptors. We isolated cDNAs for several of the P2Y receptor genes and expressed these in cells, such as the 1321N1 astrocytoma cell line, that lack native P2Y receptor expression. We report here the molecular cloning of the MDCK P2Y1 receptor, heterologous expression in 1321N1 cells, and the ability of the heterologously expressed receptors to increase intracellular calcium and phosphoinositide hydrolysis. ADP, methylthioATP, and ADPβS are agonists with the greatest potency, while ATP and ATPγS show lower potency and efficacy, and benzoylbenzoylATP, UTP, and UDP lack efficacy at the cloned P2Y1 receptor. Several antagonists, including MRS2179, A3P5PS, suramin, and PPADS blocked response at the cloned P2Y1 receptors. With their ability to respond to ADP and ATP, P2Y1 receptors, along with other P2Y receptors expressed in MDCK cells, contribute to the response of these cells to ATP (or its breakdown product, ADP) released from the cells and to exogenously added nucleotides. Drug Dev. Res. 59:1–7, 2003. © 2003 Wiley‐Liss, Inc.
2,2′‐Nitrophenylisatogen potentiates P2X1 receptor mediated vascular contraction and blood pressure elevation
Authors: Wihlborg Anna‐Karin , Slätt Johnny , Sun Xiangyang , Zhao Xiao‐He , Bergman Jan , Hedner Thomas , Erlinge David 
Published: May 2003

AbstractThe objective of this research was to examine the effects of chemical compounds with possible P2 receptor modulating effects and to characterize the potentiating effects of 2,2′‐nitrophenylisatogen (NPI) on P2X1 receptors in vitro and in vivo. Chemical compounds were tested in an in vitro pharmacological assay using vascular segments from the rat mesenteric artery stimulated by P2 receptor‐specific agonists. Contractions were expressed as a percentage of 60 mM K+‐induced contractions. Blood pressure was evaluated in pithed rats. NPI (30 μM) added 15 min before addition of the P2X1 receptor‐specific agonist αβ‐MeATP increased the maximum vasoconstriction from 23% to 49% (an increase of 113%). Furthermore, NPI prevented the desensitization of repeated αβ‐MeATP contractions. Related compounds were examined, and 2‐(3‐methoxy‐phenyl)‐1‐oxy‐indol‐3‐one (MPI) had similar effects as NPI, but several others lacked effect. NPI had no effect on ADPβS (P2Y1) or acetylcholine‐mediated vasodilatation, nor on UTP (P2Y2/4), UDP (P2Y6), or noradrenaline‐mediated contractions. In pithed rats, the blood pressure response to 50 nmol/kg‐infusion of αβ‐MeATP was increased from 50±6 to 63±5 mmHg (P<0.05), but had no effect on basal blood pressure or on the cardiovascular response to preganglionic nerve stimulation. In conclusion, NPI and MPI potentiates P2X1 receptor vascular contractions in vitro and (NPI) blood pressure effects in vivo. It is possible that the effect is mediated by an inhibition of P2X1 receptor desensitization. Drug Dev. Res. 59:82–87, 2003. © 2003 Wiley‐Liss, Inc.
Neurone‐to‐astrocyte communication by endogenous ATP in mixed culture of rat hippocampal neurones and astrocytes
Authors: Koizumi Schuichi , Fujishita Kayoko , Tsuda Makoto , Inoue Kazuhide 
Published: May 2003

AbstractATP is recognized as an important intercellular signaling molecule in the peripheral and CNS. Glutamate is reported to be an important neurone‐to‐glia mediator being released from neurones and astrocytes that activates astrocytic and neuronal Ca2+ responses, respectively. We demonstrate here that endogenous ATP could be an extracellular molecule for neurone‐to‐astrocyte communication in cocultured rat hippocampal neurones and astrocytes. Hippocampal neurones reveal synchronized Ca2+ oscillation, which was due to glutamatergic synaptic transmission. When analyzed in a fura‐2 method, a slight and very slow increase in intracellular Ca2+ concentration ([Ca2+]i) elevation was observed in some population of astrocytes. Such astrocytic [Ca2+]i elevation was dramatically inhibited by apyrase, though apyrase itself had no effect on neuronal Ca2+ oscillation. For a detail analysis, we investigated changes in [Ca2+]i in cells using a confocal microscopy. When cocultured hippocampal neurones and astrocytes were depolarized electronically in the presence of glutamate‐receptor antagonists, a transient elevation in [Ca2+]i was observed in neurones, which was followed by a slowly initiated and small rise in [Ca2+]i in astrocytes. Apyrase or P2 receptor antagonists almost abolished the [Ca2+]i rises in astrocytes, suggesting that depolarization‐evoked ATP release from neurones should produce astrocytic [Ca2+]i elevation via P2 receptors. Using a luciferin–luciferase bioluminescence assay, we found that neurones could release ATP in an activity‐dependent manner. These findings suggest that endogenous ATP should be an important intercellular mediator between neurones and astrocytes and that functions of these cells should be fine‐tuned by endogenously released ATP in situ. Drug Dev. Res. 59:88–94, 2003. © 2003 Wiley‐Liss, Inc.
Expression and function of A2B adenosine receptors in the U87MG tumor cells
Authors: Zeng Dewan , Maa Tenning , Wang Uerica , Feoktistov Igor , Biaggioni Italo , Belardinelli Luiz 
Published: May 2003

AbstractAdenosine is released in increased amounts during hypoxic conditions and is a potential mediator of angiogenesis. The aims of this study were to determine the effect of adenosine on the release of angiogenic factors from the glioblastoma cell line U87MG and the subtypes of adenosine receptors that mediate this effect of adenosine. The adenosine analog NECA increased the release of IL‐8 to 160±13% of control at 24 h. As a positive control, cobalt (100 µM), a metal ion capable of inducing hypoxia‐like effects, increased the release of IL‐8 to 362±99% of control at 24 h. Using real‐time RT‐PCR, it was found that U87MG cells expressed mRNA transcripts of the A1, A2A, and A2B adenosine receptors. The functional presence of A2B adenosine receptors in this cell line was confirmed using pharmacological approaches. NECA stimulated cAMP accumulations with an EC50 value of 2.93±0.91 µM and this effect of NECA was inhibited by the selective A2B antagonist IPDX. In addition, NECA also caused an increase in the intracellular calcium concentration. Furthermore, cobalt increased the level of A2B mRNA to 187±16% and 259±37% of the vehicle control at 5 h and 24 h, respectively. In conclusion, these results suggest that A2B adenosine receptors are upregulated during hypoxia and may play an important role in mediating the effect of adenosine to increase the release of angiogenic factor IL‐8 by tumor cells. Drug Dev. Res. 58:405–411, 2003. © 2003 Wiley‐Liss, Inc.
P2Y receptors in brain astroglial cells: Identification of a gliotic P2Y receptor coupled to activation of a calcium‐independent ras/ERK1/2 pathway
Authors: Brambilla Roberta , Neary Joseph T. , Fumagalli Marta , Cottini Lorenzo , Cattabeni Flaminio , Schiller Paul R. , Abbracchio Maria P. 
Published: May 2003

AbstractExposure of rat cortical astrocytes to αβmethyleneATP results in features of reactive astrogliosis via activation of a novel P2Y receptor linked to cyclooxygenase‐2 (COX‐2) upregulation [Brambilla et al., J Neurochem 2002, 83:1285–1296]. Here, we have investigated the role of extracellular signal‐regulated kinases (ERK1/2) in αβmethyleneATP‐induced gliosis. Challenge of cultures with αβmethyleneATP resulted in early (5–10 min) and marked time‐dependent ERK1/2 activation. Pertussis toxin completely abolished this effect. ERK1/2 activation was also completely prevented by the selective ERK1/2 inhibitor PD 098059 and by the P2 antagonist pyridoxalphosphate‐6‐azophenyl‐2′‐4′‐disulphonic acid. Because αβmethyleneATP induced no changes of intracellular calcium concentrations “Brambilla et al., 2002”, a role for phosphoinositide‐specific phospholipase C was ruled out. Conversely, D609, an inhibitor of phosphatidylcholine‐PLC (PC‐PLC) and PLD, fully abolished both αβmethyleneATP‐induced ERK1/2 activation and the associated gliosis. The Ras inhibitor FTI‐277 could also partially abolish ERK1/2 activation. Exposure of cells to αβmethyleneATP resulted in a time‐dependent increase in the DNA binding activity of AP‐1 and NF‐κB, two transcription factors known to be phosphorylated by ERKs and involved in COX‐2 gene transcription. We conclude that stimulation of a gliotic P2Y receptor leads to ERK1/2 activation via multiple parallel signaling pathways involving Gi/o‐dependent and calcium‐independent stimulation of PC‐PLC and/or PLD, and consequent activation of the Ras/Raf systems. We are currently trying to clone this receptor from these cells. Its molecular identification may lead to the development of a new class of antineurodegenerative agents, which, by counteracting excessive gliosis and COX‐2 upregulation, may prove useful in neurological disorders characterized by astrogliosis and inflammation. Drug Dev. Res. 59:161–170, 2003. © 2003 Wiley‐Liss, Inc.
CD40‐dependent and ‐independent activation of human tonsil B cells by CpG oligodeoxynucleotides
Authors: Gantner Florian , Hermann Patrice , Nakashima Kosuke , Matsukawa Satoko , Sakai Katsuya , Bacon Kevin B. 
Published: May 2003

AbstractImmunostimulatory CpG oligodeoxynucleotide (CpG‐ODN) sequences are known to directly activate B cells. We investigated the expression of the CpG receptor, Toll‐like receptor 9 (TLR9), in humantonsil B cells, and determined functional responses following stimulation by a well‐characterized stimulatory CpG‐containing ODN sequence in the human immune system, ODN 2006. Tonsil B cells were found to express high amounts of TLR9 mRNA and protein, and exposure of B cells to CpG‐ODN but not to an inactive control ODN induced a concentration‐ and time‐dependent up‐regulation of the activation markers CD23, CD25, CD40, CD54, CD80, CD86 and HLA‐DR. However, significant induction of proliferation and the release of IL‐6, IL‐10, IgG and IgM were only noted when B cells were co‐incubated with irradiated CD40L‐expressing CHO cells. Endogenous IL‐10 was identified as a critical mediator of Ig production, whereas all activating effects were independent of IL‐6. Further, CpG‐ODN counteracted IgE production induced by IL‐4. Collectively, these findings suggest a synergistic role of the TLR9/CD40 system and a critical role for the immunomodulatory cytokine IL‐10 in the orchestration of CpG‐ODN‐induced responses in B lymphocytes.
Deficiency of CD26 results in a change of cytokine and immunoglobulin secretion after stimulation by pokeweed mitogen
Authors: Yan Shuling , Marguet Didier , Dobers Jörg , Reutter Werner , Fan Hua 
Published: May 2003

AbstractTo investigate the role of CD26 in the immune system, CD26 gene knockout mice with C57BL/6 background were used to study the immune response after stimulation with PWM. CD26–/– mice display an apparently normal phenotype. However, in their spleen lymphocyte population the percentage of CD4+ T cells is lower, and that of NK cells is higher, than that in CD26+/+ mice. In their peripheral blood, CD26–/– mice present a conspicuously decreased proportion of CD4+ NKT lymphocytes. In vitro, the PWM‐stimulated IL‐4 production was decreased by 60–80% in the supernatants of spleen lymphocytes of CD26–/– mice compared to that of CD26+/+ mice, whereas levels of IL‐10 and IFN‐γ were increased. No significant differences were found in the production of IL‐2, IL‐5, IL‐6 and IL‐13 between knockout and wild‐type mice. After immunization of mice with PWM in vivo, serum levels of total IgG, IgG1, IgG2a and IgE were markedly lower in CD26–/– mice than those in CD26+/+ mice, while no difference was found in IgM production. Further analysis of cytokine levels in vivo revealed a reduced IL‐4, IL‐2 and delayed IFN‐γ production in sera of CD26–/– mice upon immunization with PWM. These results indicate that CD26 contributes to the regulation of development, maturation and migration of CD4+ T, NK and NKT cells, cytokine secretion, T cell‐dependent antibody production and immunoglobulin isotype switching of B cells.
Unique T cell proliferation associated with PKCμ activation and impaired ZAP‐70 phosphorylation in recognition of overexpressed HLA/partially agonistic peptide complexes
Authors: Irie Atsushi , Chen Yu‐Zhen , Tsukamoto Hirotake , Jotsuka Toko , Masuda Masako , Nishimura Yasuharu 
Published: May 2003

AbstractAltered peptide ligands (APL) induce T cell responses different from those induced by the original agonistic peptide. As shown for CD4+ T cells, partial agonists induce partial T cellactivation without proliferation because of lower affinities and higher off rates to TCR than those of agonists. To determine whether overexpression of partially agonistic TCR ligands on antigen‐presenting cells provides high‐avidity TCR ligands, we generated L cell transfectants expressing various numbers of HLA‐DR4 covalently linked with APL derived from a streptococcal peptide and observed responses of the cognate T cells. Some overexpressed HLA‐DR4/partially agonistic APL complexes induced T cell proliferation in a density‐dependent manner. However, tyrosine phosphorylation of zeta‐associated protein‐70 (ZAP‐70) and linker for activation of T cells and kinase activity of ZAP‐70 were not detectable. T cell proliferation stimulated with L cell transfectants was sensitive to thePKC inhibitor Gö6976, but to a lesser extent to Gö6983, suggesting the involvement of μ isotype of PKC (PKCμ). In vitro kinase assays revealed that PKCμ activity was up‐regulated only in T cells stimulated with L cell transfectants that induced T cell proliferation. Our data suggest the presence of a unique signaling pathway coupling TCR ligation with T cell proliferation associated with PKCμ activation and impaired ZAP‐70 activation.
Neutropenia alters lung cytokine production in mice and reduces their susceptibility to pulmonary cryptococcosis
Authors: Mednick Aron J. , Feldmesser Marta , Rivera Johanna , Casadevall Arturo 
Published: May 2003

AbstractNeutrophils are generally considered to contribute to host defense through their potent microbicidal activity. However, there is accumulating evidence that neutrophils also have an important regulatory role in establishing the balance of Th1 and Th2 responses. This study investigated the role of neutrophils in defense against pulmonary Cryptococcus neoformans infection using neutrophil‐depleted BALB/c mice generated by administering mAb RB6–8C5. Neutropenic mice with pulmonary infection survived significantly longer than control mice, but there was no difference between groups infected intravenously. On day 1 of infection, neutropenic mice had significantly smaller fungal burdens than control mice. On day 7, neutropenic mice had significantly higher lung concentrations of IL‐10, TNF‐α, IL‐4, and IL‐12 than control mice, but there was no difference in IFN‐γ and MCP‐1 levels. Neutrophils influenced the outcome of cryptococcal infection in mice through mechanisms that did not involve a reduction in early fungal burden. The absence of neutrophils in lung tissue during the initial stages of infection appeared to alter the inflammatory response in a manner thatwas subsequently beneficial to the host. Higher levels of Th1‐ and Th2‐associated cytokines in neutropenic mice could have simultaneously promoted a strong cellular response while reducing inflammatory damage to the lung. Our results support the emerging concept that neutrophils play an important function in modulating the development of the immune response.
B cell apoptosis accelerates the onset of murine lupus
Authors: Trébéden‐Nègre Hélène , Weill Bernard , Fournier Catherine , Batteux Frédéric 
Published: May 2003

AbstractTo investigate whether the increased rate of lymphocyte apoptosis in systemic lupus erythematosus is involved in the onset of the disease, apoptotic or necrotic T or B lymphocytes from variouscell lines were injected intraperitoneally into pre‐autoimmune (NZB×NZW)F1 mice (BW) and non‐autoimmune BALB/c mice. The intraperitoneal production of cytokines and chemokines, the specific T cell response in the spleen, and the production of anti‐histone and anti‐dsDNA Ab were investigated. The onset of the disease was characterized by creatinine levels and evaluation of glomerular IgG deposits. In BW, but not in BALB/c mice, injection of apoptotic and not necrotic cells up‐regulated IL‐6 and IL‐10 in resident macrophages. Administration of apoptotic cells augmented the number of Th2 and B lymphocytes recruited in the peritoneal cavity. Only the treatment with apoptotic B cells promoted a systemic Th2 autoimmune response to H2 histones, associated with earlier occurrence of high levels of anti‐dsDNA autoantibodies, higher creatinine levels and more numerous glomerular IgG deposits than in BW controls not injected with apoptotic B cells. In genetically susceptible mice exposure to apoptotic of B, but not T, lymphocytes can elicit a Th2 response to H2 histones that helps B cell production of anti‐dsDNA Ab and finally triggers the onset of lupus.