Induction of COX‐2 and reactive gliosis by P2Y receptors in rat cortical astrocytes is dependent on ERK1/2 but independent of calcium signalling

• Published in: Journal of neurochemistry 2002-12, Vol.83 (6), p.1285-1296
• Main Authors: Brambilla, Roberta, Neary, Joseph T., Cattabeni, Flaminio, Cottini, Lorenzo, D'Ippolito, Gianluca, Schiller, Paul C., Abbracchio, Maria P.
• Format: Article
• Language: English
• Subjects: Adenosine Triphosphate - analogs & derivatives; Adenosine Triphosphate - pharmacology; Animals; Arachidonate 5-Lipoxygenase - metabolism; Astrocytes - cytology; Astrocytes - drug effects; Astrocytes - metabolism; Biological and medical sciences; Calcium Signaling - drug effects; Calcium Signaling - physiology; Cells, Cultured; Cerebral Cortex - cytology; Cyclooxygenase 2; Enzyme Induction - drug effects; Fundamental and applied biological sciences. Psychology; Gliosis - chemically induced; Gliosis - metabolism; Gliosis - pathology; GTP-Binding Proteins - metabolism; Isoenzymes - metabolism; Isolated neuron and nerve. Neuroglia; Mitogen-Activated Protein Kinase 1 - metabolism; Mitogen-Activated Protein Kinase 3; Mitogen-Activated Protein Kinases - metabolism; neurodegenerative diseases; neuroinflammation; P2Y receptors; Prostaglandin-Endoperoxide Synthases - metabolism; rat cortex; Rats; reactive astrogliosis; Receptors, Purinergic P2 - metabolism; Up-Regulation - drug effects; Vertebrates: nervous system and sense organs
• ISSN: 0022-3042; 1471-4159
• DOI: 10.1046/j.1471-4159.2002.01239.x

The present study has been aimed at characterizing the ATP/P2 receptor (and transductional pathways) responsible for the morphological changes induced in vitro by αβmethyleneATP on rat astrocytes obtained from cerebral cortex, a brain area highly involved in neurodegenerative diseases. Exposure of cells to this purine analogue resulted in elongation of cellular processes, an event reproducing in vitro a major hallmark of in vivo reactive gliosis. αβmethyleneATP‐induced gliosis was prevented by the P2X/P2Y blocker pyridoxalphosphate‐6‐azophenyl‐2′‐4′‐disulfonic acid, but not by the selective P2X antagonist 2′,3′‐O‐(2,4,6‐trinitrophenyl)‐ATP, ruling out a role for ligand‐gated P2X receptors. Conversely, the Gi/Go protein inactivator pertussis toxin completely prevented αβmethyleneATP‐induced effects. No effects were induced by αβmethyleneATP on intracellular calcium concentrations. RT‐PCR and western blot analysis showed that αβmethyleneATP–induced gliosis involves up‐regulation of cyclooxygenase‐2 (but not lipooxygenase). Also this effect was fully prevented by pyridoxalphosphate‐6‐azophenyl‐2′‐4′‐disulfonic acid. Experiments with inhibitors of mitogen‐activated protein kinases (MAPK) suggest that extracellular signal regulated protein kinases (ERK)1/2 mediate both cyclooxygenase‐2 induction and the associated in vitro gliosis. These findings suggest that purine‐induced gliosis involves the activation of a calcium‐independent G‐protein‐coupled P2Y receptor linked to ERK1/2 and cyclooxygenase‐2. Based on the involvement of cyclooxygenase‐2 and inflammation in neurodegenerative diseases, these findings open up new avenues in the identification of novel biological targets for the pharmacological manipulation of neurodegeneration.