title: Neuroprotection Promoted by Guanosine Depends on Glutamine Synthetase and Glutamate Transporters Activity in Hippocampal Slices Subjected to Oxygen/Glucose Deprivation.
abstract: Guanosine (GUO) has been shown to act as a neuroprotective agent against glutamatergic excitotoxicity by increasing glutamate uptake and decreasing its release. In this study, a putative effect of GUO action on glutamate transporters activity modulation was assessed in hippocampal slices subjected to oxygen and glucose deprivation (OGD), an in vitro model of brain ischemia. Slices subjected to OGD showed increased excitatory amino acids release (measured by D-[(3)H]aspartate release) that was prevented in the presence of GUO (100 µM). The glutamate transporter blockers, DL-TBOA (10 µM), DHK (100 µM, selective inhibitor of GLT-1), and sulfasalazine (SAS, 250 µM, Xc(-) system inhibitor) decreased OGD-induced D-aspartate release. Interestingly, DHK or DL-TBOA blocked the decrease in glutamate release induced by GUO, whereas SAS did not modify the GUO effect. GUO protected hippocampal slices from cellular damage by modulation of glutamate transporters, however selective blockade of GLT-1 or Xc- system only did not affect this protective action of GUO. OGD decreased hippocampal glutamine synthetase (GS) activity and GUO recovered GS activity to control levels without altering the kinetic parameters of GS activity, thus suggesting GUO does not directly interact with GS. Additionally, the pharmacological inhibition of GS activity with methionine sulfoximine abolished the effect of GUO in reducing D-aspartate release and cellular damage evoked by OGD. Altogether, results in hippocampal slices subjected to OGD show that GUO counteracts the release of excitatory amino acids, stimulates the activity of GS, and decreases the cellular damage by modulation of glutamate transporters activity.
authors: Departamento de Bioquímica, Centro de Ciências Biológicas, Universidade Federal de Santa Catarina, Trindade, Florianópolis, SC, 88040-900, Brazil.|Programa de pós-graduação em Neurociências, Centro de Ciências Biológicas, Universidade Federal de Santa Catarina, Florianópolis, SC, Brazil.
authors: Tharine
authors: T
authors: Dal-Cim
authors: Departamento de Bioquímica, Centro de Ciências Biológicas, Universidade Federal de Santa Catarina, Trindade, Florianópolis, SC, 88040-900, Brazil.|Programa de pós-graduação em Neurociências, Centro de Ciências Biológicas, Universidade Federal de Santa Catarina, Florianópolis, SC, Brazil.
authors: Wagner C
authors: WC
authors: Martins
authors: Departamento de Bioquímica, Centro de Ciências Biológicas, Universidade Federal de Santa Catarina, Trindade, Florianópolis, SC, 88040-900, Brazil.|Programa de pós-graduação em Bioquímica, Centro de Ciências Biológicas, Universidade Federal de Santa Catarina, Florianópolis, SC, Brazil.
authors: Daniel T
authors: DT
authors: Thomaz
authors: Departamento de Bioquímica, Centro de Ciências Biológicas, Universidade Federal de Santa Catarina, Trindade, Florianópolis, SC, 88040-900, Brazil.
authors: Victor
authors: V
authors: Coelho
authors: Departamento de Bioquímica, Centro de Ciências Biológicas, Universidade Federal de Santa Catarina, Trindade, Florianópolis, SC, 88040-900, Brazil.
authors: Gabriela Godoy
authors: GG
authors: Poluceno
authors: Departamento de Bioquímica, Centro de Ciências Biológicas, Universidade Federal de Santa Catarina, Trindade, Florianópolis, SC, 88040-900, Brazil.|Programa de pós-graduação em Neurociências, Centro de Ciências Biológicas, Universidade Federal de Santa Catarina, Florianópolis, SC, Brazil.
authors: Débora
authors: D
authors: Lanznaster
authors: Departamento de Ciências Básicas em Saúde, Faculdade de Medicina, Universidade Federal de Mato Grosso, Cuiabá, MT, Brazil.
authors: Samuel
authors: S
authors: Vandresen-Filho
authors: Departamento de Bioquímica, Centro de Ciências Biológicas, Universidade Federal de Santa Catarina, Trindade, Florianópolis, SC, 88040-900, Brazil. carla.tasca@ufsc.br.|Programa de pós-graduação em Neurociências, Centro de Ciências Biológicas, Universidade Federal de Santa Catarina, Florianópolis, SC, Brazil. carla.tasca@ufsc.br.|Programa de pós-graduação em Bioquímica, Centro de Ciências Biológicas, Universidade Federal de Santa Catarina, Florianópolis, SC, Brazil. carla.tasca@ufsc.br.
authors: Carla I
authors: CI
authors: Tasca
mesh_terms: D027322:Amino Acid Transport System X-AG / Q000378:metabolism*; D000704:Analysis of Variance; D000818:Animals; D001224:Aspartic Acid / Q000493:pharmacokinetics; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005786:Gene Expression Regulation / Q000187:drug effects; D005947:Glucose / Q000172:deficiency*; D005974:Glutamate-Ammonia Ligase / Q000378:metabolism*; D005973:Glutamine / Q000494:pharmacology; D006151:Guanosine / Q000494:pharmacology*; D006624:Hippocampus / Q000187:drug effects*; D000860:Hypoxia / Q000473:pathology*; D066298:In Vitro Techniques; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D014316:Tritium / Q000493:pharmacokinetics
chemical_list: D027322:Amino Acid Transport System X-AG; D004791:Enzyme Inhibitors; D005973:Glutamine; D014316:Tritium; D006151:Guanosine; D001224:Aspartic Acid; D005974:Glutamate-Ammonia Ligase; D005947:Glucose
keywords: Glutamate release; Glutamine synthetase activity; Guanosine; Oxygen/glucose deprivation