Cysteinyl-leukotrienes are released from astrocytes and increase astrocyte proliferation and glial fibrillary acidic protein via cys-LT1 receptors and mitogen-activated protein kinase pathway.
Cysteinyl-leukotrienes (cys-LTs), potent mediators in inflammatory diseases, are produced by nervous tissue, but their cellular source and role in the brain are not very well known. In this report we have demonstrated that rat cultured astrocytes express the enzymes (5'-lipoxygenase and LTC(4) synthase) required for cys-LT production, and release cys-LTs in resting condition and, to a greater extent, in response to calcium ionophore A23187, 1 h combined oxygen-glucose deprivation or 2-methyl-thioATP, a selective P2Y(1)/ATP receptor agonist. MK-886, a LT synthesis inhibitor, prevented basal and evoked cys-LT release. In addition, 2-methyl-thioATP-induced cys-LT release was abolished by suramin, a P2 receptor antagonist, or by inhibitors of ATP binding cassette proteins involved in cys-LT release. We also showed that astrocytes express cys-LT(1) and not cys-LT(2) receptors. The stimulation of these receptors by LTD(4) activated the mitogen-activated protein kinase (MAPK) pathway. This effect was: (i) insensitive to inhibitors of receptor-coupled Gi protein (pertussis toxin) or tyrosine kinase receptors (genistein); (ii) abolished by MK-571, a cys-LT(1) selective receptor antagonist, or PD98059, a MAPK inhibitor; (iii) reduced by inhibitors of calcium/calmodulin-dependent kinase II (KN-93), Ca(2+)-dependent and -independent (GF102903X) or Ca(2+)-dependent (Gö6976) protein kinase C isoforms. LTD(4) also increased astrocyte proliferation and glial fibrillary acidic protein content, which are considered hallmarks of reactive astrogliosis. Both effects were counteracted by cell pretreatment with MK-571 or PD98059. Thus, cys-LTs released from astrocytes might play an autocrine role in the induction of reactive astrogliosis that, in brain injuries, contributes to the formation of a reparative glial scar.
Ciccarelli
Renata
R
Department of Biomedical Sciences, Section of Pharmacology, Medical School, G. D'Annunzio University of Chieti, Chieti, Italy. r.ciccarelli@dsb.unich.it
D'Alimonte
Iolanda
I
Santavenere
Clara
C
D'Auro
Mariagrazia
M
Ballerini
Patrizia
P
Nargi
Eleonora
E
Buccella
Silvana
S
Nicosia
Simonetta
S
Folco
Giancarlo
G
Caciagli
Francesco
F
Di Iorio
Patrizia
P
D000255:Adenosine Triphosphate / Q000031:analogs & derivatives* / Q000494:pharmacology; D000818:Animals; D000831:Animals, Newborn; D001253:Astrocytes / Q000378:metabolism*; D015152:Blotting, Northern / Q000379:methods; D015153:Blotting, Western / Q000379:methods; D000001:Calcimycin / Q000494:pharmacology; D002455:Cell Division / Q000502:physiology; D002470:Cell Survival; D002478:Cells, Cultured; D002540:Cerebral Cortex / Q000166:cytology* / Q000378:metabolism; D003545:Cysteine / Q000145:classification / Q000378:metabolism* / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005904:Glial Fibrillary Acidic Protein / Q000378:metabolism*; D005947:Glucose / Q000172:deficiency; D005982:Glutathione Transferase / Q000235:genetics / Q000378:metabolism; D000860:Hypoxia; D007124:Immunoenzyme Techniques / Q000379:methods; D007476:Ionophores / Q000494:pharmacology; D015289:Leukotrienes / Q000145:classification / Q000378:metabolism* / Q000494:pharmacology; D008084:Lipoxygenase / Q000235:genetics / Q000378:metabolism; D008565:Membrane Proteins / Q000502:physiology*; D020928:Mitogen-Activated Protein Kinases / Q000502:physiology*; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D018077:Receptors, Leukotriene / Q000502:physiology*; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D013873:Thionucleotides / Q000494:pharmacology; D013936:Thymidine / Q000378:metabolism; D013997:Time Factors; D014316:Tritium / Q000378:metabolism
D004791:Enzyme Inhibitors; D005904:Glial Fibrillary Acidic Protein; D007476:Ionophores; D015289:Leukotrienes; D008565:Membrane Proteins; D012333:RNA, Messenger; D018077:Receptors, Leukotriene; D013873:Thionucleotides; C112381:cysteinyl-leukotriene; D014316:Tritium; D000001:Calcimycin; D000255:Adenosine Triphosphate; D008084:Lipoxygenase; D005982:Glutathione Transferase; D020928:Mitogen-Activated Protein Kinases; C041116:leukotriene-C4 synthase; D005947:Glucose; D003545:Cysteine; C083169:leukotriene D4 receptor; D013936:Thymidine; C008501:2-methylthio-ATP