Anales RANF

S12-01 GUANOSINE-INDUCED NEUROPROTECTION: A ROLE FOR ADENOSINE RECEPTOR OLIGOMERS? Fernández-Dueñas V 1,2 , Lanznaster D 3 , Massari C 3 , Marková V 1,2 , Šimková T 1,2 , Duroux R 4 , Jacobson KA 4 , Tasca CI 3,5 and Ciruela F 1,2 1 Unitat de Farmacologia, Departament de Patologia i Terapèutica Experimental, Facultat de Medicina, IDIBELL, Universitat de Barcelona, L’Hospitalet de Llobregat, Barcelona, Spain. 2 Institut de Neurociències, Universitat de Barcelona, Spain. 3 Programa de Pós-graduação em Neurociências, Centro de Ciências Biológicas, Universidade Federal de Santa Catarina, Florianópolis, Brazil. 4 Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, USA. 5 Departamento de Bioquímica, Centro de Ciências Biológicas, Universidade Federal de Santa Catarina, Florianópolis, Brazil. Guanosine is a guanine-based purine nucleoside with important trophic functions and promising neuroprotective properties. In line with this, we recently proposed a potential therapeutic role for guanosine in Parkinson’s disease treatment 1 . In animal models of parkinsonism (catalepsy, tremor, hemiparkinsonism), guanosine was effective not only for reversing parkinsonian motor impairments but also for reducing L-DOPA-induced dyskinesia 1 . Despite these promising effects, the exact mechanism of action and molecular targets for guanosine are still unknown. Here, we aimed to elucidate a role for adenosine receptors (AR), which could be involved in mediating guanosine effects. To this end, we first investigated the neuroprotective role of guanosine in hippocampal slices from wild-type and A 2A R-deficient mice subjected to oxygen/glucose deprivation. Our results pointed to a crucial role of A 2A R expression in guanosine-mediated neuroprotective effects. Accordingly, we next aimed to assess possible guanosine binding and functional activation of A 2A R. We synthesized a new fluorescent selective A 2A R antagonist (MRS7396) 2 , which could engage a Bioluminiscence Resonance Energy Transfer process with NanoLuc-tagged A 2A R, and evaluated guanosine ability to block A 2A R ligand binding. Interestingly, we assessed guanosine effects in cells transfected with A 2A R alone or together with the A 1 R, which may form functional oligomers. Guanosine partially displaced MRS7396 binding only in cells co-expressing A 1 R/A 2A R. Similarly, we also observed that guanosine exerted inhibitory effects on functional activation of A 2A R (cAMP and label-free recording) in A 1 R/A 2A R-expressing cells. Overall, our results suggest that A 2A R expression is crucial for guanosine neuroprotective effects and that the A 1 R/A 2A R oligomer may be relevant for such guanosine-AR interaction. References 1 Massari CM et al . Antiparkinsonian efficacy of guanosine in rodent models of movement disorder. Frontiers in Pharmacology 2017; 8 . doi:10.3389/fphar.2017.00700. 2 Duroux R et al. Bitopic fluorescent antagonists of the A2A adenosine receptor based on pyrazolo[4,3-: E] [1,2,4]triazolo[1,5- c] pyrimidin-5-amine functionalized congeners. MedChemComm 2017; 8 . doi:10.1039/c7md00247e.