title: Platelet activating factor (PAF) antagonists on cytokine induction of iNOS and sPLA2 in immortalized astrocytes (DITNC).
abstract: Platelet-activating factor (PAF, 1-O-alkyl-2-acetyl-sn-glycero-3-phosphocholine) and its receptor are known to play important roles in modulating neuronal plasticity and inflammatory responses, particularly during neuronal injury. PAF receptors are widespread in different brain regions and are present on the cell surface as well as in intracellular membrane compartments. Astrocytes are immune active cells and are responsive to cytokines, which stimulate signaling cascades leading to transcriptional activation of genes and protein synthesis. Our recent studies indicate the ability of cytokines, e.g., tumor necrosis factor-alpha (TNFalpha), interleukin-1beta (IL-1beta) and interferon-gamma (IFNgamma), to induce the inducible nitric oxide (iNOS) and secretory phospholipase A2 (sPLA2) genes in immortalized astrocytes (DITNC) (Li et al., J. Interferon and Cytokine Res. 19: 121-127. 1999). The main objective for this study is to examine the effects of PAF antagonists on cytokine induction of iNOS and sPLA2 in these cells. Results show that BN50730, a synthetic PAF antagonist, but not BN52021, a natural PAF antagonist (ginkolide B) can dose-dependently inhibit cytokine induction of NO production and sPLA2 release. Inhibition of NO production by BN50730 corroborated well with the decrease in iNOS protein and mRNA levels as well as binding of NF-kappaB STAT- 1 to DNA, suggesting that BN50730 action is upstream of the transcriptional process. These results are in agreement with the role of intracellular PAF in regulating the cytokine signaling cascade in astrocytes and further suggest the possible use of BN50730 as a therapeutic agent for suppressing the inflammatory pathways elicited by cytokines.
authors.affiliation: Biochemistry Department, University of Missouri, Columbia 65212, USA.
authors.forename: J H
authors.initials: JH
authors.lastname: Wang
authors.forename: G Y
authors.initials: GY
authors.lastname: Sun
mesh_terms: D000818:Animals; D001253:Astrocytes / Q000187:drug effects* / Q000201:enzymology*; D001381:Azepines / Q000494:pharmacology*; D002461:Cell Line, Transformed; D016207:Cytokines / Q000494:pharmacology*; D004224:Diterpenes; D004790:Enzyme Induction; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects*; D046934:Ginkgolides; D054501:Group II Phospholipases A2; D007371:Interferon-gamma / Q000494:pharmacology; D007375:Interleukin-1 / Q000494:pharmacology; D007783:Lactones / Q000494:pharmacology*; D019001:Nitric Oxide Synthase / Q000096:biosynthesis / Q000235:genetics*; D052247:Nitric Oxide Synthase Type II; D010741:Phospholipases A / Q000096:biosynthesis / Q000235:genetics*; D054467:Phospholipases A2; D010972:Platelet Activating Factor / Q000037:antagonists & inhibitors; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D058924:Thienopyridines; D014230:Triazoles / Q000494:pharmacology*; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
chemical_list: D001381:Azepines; D016207:Cytokines; D004224:Diterpenes; D046934:Ginkgolides; D007375:Interleukin-1; D007783:Lactones; D010972:Platelet Activating Factor; D058924:Thienopyridines; D014230:Triazoles; D014409:Tumor Necrosis Factor-alpha; C066686:BN 50730; D007371:Interferon-gamma; C045856:ginkgolide B; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; D010741:Phospholipases A; D054501:Group II Phospholipases A2; D054467:Phospholipases A2