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Caffeine and adenosine
Ribeiro, Joaquim A.; Sebastião, Ana M.© 2010 – IOS Press and the authors. All rights reserved ; Caffeine causes most of its biological effects via antagonizing all types of adenosine receptors (ARs): A1, A2A, A3, and A2B and, as does adenosine, exerts effects on neurons and glial cells of all brain areas. In consequence, caffeine, when acting as an AR antagonist, is doing the opposite of activation of adenosine receptors due to removal of endogeno...
Activation of adenosine A2A receptors induces TrkB translocation and increases ...
Assaife-Lopes, Natália; Sousa, Vasco C.; Pereira, Daniela B.; Ribeiro, Joaquim A.; Chao, Moses V.; Sebastião, Ana M.Copyright © 2010 the authors ; Brain-derived neurotrophic factor (BDNF) signaling is critical for neuronal development and transmission. Recruitment of TrkB receptors to lipid rafts has been hown to be necessary for the activation of specific signaling pathways and modulation of neurotransmitter release by BDNF. Since TrkB receptors are known to be modulated by adenosine A2A receptor activation, we hypothesize...
Adenosine A2A receptor modulation of hippocampal CA3-CA1 synapse plasticity dur...
Fontinha, Bruno M; Delgado-García, José M; Madroñal, Noelia; Ribeiro, Joaquim A; Sebastião, Ana M; Gruart, Agnès© 2009 Nature Publishing Group All rights reserved ; Previous in vitro studies have characterized the electrophysiological and molecular signaling pathways of adenosine tonic modulation on long-lasting synaptic plasticity events, particularly for hippocampal long-term potentiation(LTP). However, it remains to be elucidated whether the long-term changes produced by endogenous adenosine in the efficie...
Adenosine A2A receptors control the extracellular levels of adenosine through m...
Pinto-Duarte, António; Coelho, Joana E.; Cunha, Rodrigo A.; Ribeiro, Joaquim Alexandre; Sebastião, Ana M.Adenosine, a neuromodulator of the CNS, activates inhibitory-A1 receptors and facilitatory-A2A receptors; its synaptic levels are controlled by the activity of bi-directional equilibrative nucleoside transporters. To study the relationship between the extracellular formation/inactivation of adenosine and the activation of adenosine receptors, we investigated how A1 and A2A receptor activation modifies adenosine...
Enhanced adenosine A2A receptor facilitation of synaptic transmission in the hi...
Rebola, Nelson; Sebastião, Ana M.; Mendonça, Alexandre de; Oliveira, Catarina R.; Ribeiro, J. A.; Cunha, Rodrigo A.Adenosine either inhibits or facilitates synaptic transmission through A1 or A2A receptors, respectively. Since A2A receptor density increases in the limbic cortex of aged (24 mo) compared with young adult rats (2 mo), we tested if A2A receptor modulation of synaptic transmission was also increased in aged rats. The A2A receptor agonist, CGS21680 (10 nM), caused a larger facilitation of the field excitatory pos...
Endogenous Adenosine Modulation of 22Na Uptake by Rat Brain Synaptosomes
Ribeiro, Joaquim Alexandre; Lobo, M. Graça B.; Sebastião, Ana M.To evaluate if endogenous extracellular adenosine influences sodium channel activity in nerve terminals, we investigated how manipulations of extracellular adenosine levels influence 22Na uptake by rat brain synaptosomes stimulated with veratridine (VT). To decrease extracellular adenosine levels, adenosine deaminase (ADA) that converts adenosine into an inactive metabolite was used. To increase extracellular a...
Inhibition by ATP of hippocampal synaptic transmission requires localized extra...
Cunha, Rodrigo A.; Sebastião, Ana M.; Ribeiro, J. A.© 1998 Society for Neuroscience ; ATP analogs substituted in the γ-phosphorus (ATPγS, β, γ-imido-ATP, and β, γ-methylene-ATP) were used to probe the involvement of P2 receptors in the modulation of synaptic transmission in the hippocampus, because their extracellular catabolism was virtually not detected in CA1 slices. ATP and γ-substituted analogs were equipotent to inhibit synaptic transmission in CA1 pyrami...
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