title: Guanosine protects glial cells against 6-hydroxydopamine toxicity.
abstract: Increasing body of evidence indicates that neuron-neuroglia interaction may play a key role in determining the progression of neurodegenerative diseases including Parkinson's disease (PD), a chronic pathological condition characterized by selective loss of dopaminergic (DA) neurons in the substantia nigra. We have previously reported that guanosine (GUO) antagonizes MPP(+)-induced cytotoxicity in neuroblastoma cells and exerts neuroprotective effects against 6-hydroxydopamine (6-OHDA) and beta-amyloid-induced apoptosis of SH-SY5Y cells. In the present study we demonstrate that GUO protected C6 glioma cells, taken as a model system for astrocytes, from 6-OHDA-induced neurotoxicity. We show that GUO, either alone or in combination with 6-OHDA activated the cell survival pathways ERK and PI3K/Akt. The involvement of these signaling systems in the mechanism of the nucleoside action was strengthened by a reduction of the protective effect when glial cells were pretreated with U0126 or LY294002, the specific inhibitors of MEK1/2 and PI3K, respectively. Since the protective effect on glial cell death of GUO was not affected by pretreatment with a cocktail of nucleoside transporter blockers, GUO transport and its intracellular accumulation were not at play in our in vitro model of PD. This fits well with our data which pointed to the presence of specific binding sites for GUO on rat brain membranes. On the whole, the results described in the present study, along with our recent evidence showing that GUO when administered to rats via intraperitoneal injection is able to reach the brain and with previous data indicating that it stimulates the release of neurotrophic factors, suggest that GUO, a natural compound, by acting at the glial level could be a promising agent to be tested against neurodegeneration.
authors.affiliation: Department of Experimental and Clinical Sciences, "G. d'Annunzio" University, Chieti-Pescara, 29 via dei Vestini, NPD PalB, 66013, Chieti, Italy.
authors.forename: Patricia
authors.initials: P
authors.lastname: Giuliani
authors.forename: Patrizia
authors.initials: P
authors.lastname: Ballerini
authors.forename: Silvana
authors.initials: S
authors.lastname: Buccella
authors.forename: Renata
authors.initials: R
authors.lastname: Ciccarelli
authors.forename: Michel P
authors.initials: MP
authors.lastname: Rathbone
authors.forename: Silvia
authors.initials: S
authors.lastname: Romano
authors.forename: Iolanda
authors.initials: I
authors.lastname: D'Alimonte
authors.forename: Francesco
authors.initials: F
authors.lastname: Caciagli
authors.forename: Patrizia
authors.initials: P
authors.lastname: Di Iorio
authors.forename: Mieczyslaw
authors.initials: M
authors.lastname: Pokorski
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D001253:Astrocytes / Q000187:drug effects*; D001692:Biological Transport / Q000187:drug effects; D002070:Butadienes / Q000494:pharmacology; D045744:Cell Line, Tumor; D002867:Chromones / Q000494:pharmacology; D053938:DNA Fragmentation / Q000187:drug effects; D004353:Drug Evaluation, Preclinical; D005910:Glioma / Q000473:pathology; D006151:Guanosine / Q000494:pharmacology*; D066298:In Vitro Techniques; D020935:MAP Kinase Signaling System / Q000187:drug effects; D009025:Morpholines / Q000494:pharmacology; D018696:Neuroprotective Agents / Q000494:pharmacology*; D009498:Neurotoxins / Q000037:antagonists & inhibitors* / Q000633:toxicity; D009570:Nitriles / Q000494:pharmacology; D033703:Nucleoside Transport Proteins / Q000037:antagonists & inhibitors; D016627:Oxidopamine / Q000037:antagonists & inhibitors* / Q000633:toxicity; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D051381:Rats; D015398:Signal Transduction / Q000187:drug effects*
chemical_list: D002070:Butadienes; D002867:Chromones; D009025:Morpholines; D018696:Neuroprotective Agents; D009498:Neurotoxins; D009570:Nitriles; D033703:Nucleoside Transport Proteins; D047428:Protein Kinase Inhibitors; C113580:U 0126; D006151:Guanosine; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; D016627:Oxidopamine; D019869:Phosphatidylinositol 3-Kinases; C494920:Akt1 protein, rat; D051057:Proto-Oncogene Proteins c-akt