Effects of Guanine Nucleotides on Glutamate-Induced Chemiluminescence in Rat Hippocampal Slices Submitted to Hypoxia |
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Authors: | Regner Andrea Ramirez Galo Belló-Klein Adriane Souza Diogo |
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Institution: | (1) Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil;(2) Departamento de Fisiologia, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil;(3) Centro de Biologia Molecular, (CSIC-UAM), Universidad Autónoma, Cantoblanco, 28049 Madrid, Spain |
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Abstract: | Glutamate significantly increased levels of spontaneous chemiluminescence (CL) in rat hippocampal slices incubated under hypoxic conditions. Although it has been previously shown that guanine nucleotides (GN) displace glutamate from several of its receptors, in our study only GMP, as well as the glutamate antagonist MK-801, was able to reverse the increase in CL provoked by glutamate. On the other hand, not only GTP or Gpp(NH)p failed to reverse the action of glutamate, but they increased CL production like glutamate. This effect of GTP/Gpp(NH)p was also reversed by GMP. We concluded that, under neurotoxic conditions, GMP acted as an antagonist and GTP or Gpp(NH)p acted as agonists of glutamate. These results reinforced the evidence of the existence of extracellular site(s) for GN and indicated a possible role for GN in excitotoxicity. |
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Keywords: | Glutamate excitotoxicity rat hippocampus guanine nucleotides reactive oxygen species chemiluminescence |
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