Introduction 1 2 3 4 6 7 8 7 9 10 11 12 13 14 15 16 17 18 19 + 17 + 5 + 20 16 21 22 23 24 + 25 23 26 27 29 30 5 31 32 33 34 33 34 35 37 38 + + after + Materials and methods Tissue culture and treatment of human SH-SY5Y neuroblastoma cells 2 + + 2 + pre-treatment + co-treatment) + (post-treatment 1 + post-treatment + + 1 post-treatment + + 1 Fig. 1 + + post-treatment + + + post-treatment + + + + Materials and methods  H 50 H 50 Evaluation of cell death and DNA fragmentation 4 + PLUS 39 + 34 g Determination of caspase-3 activity 7 g N N p p 8 8 Measurement of α-synuclein protein concentration by ELISA 4 2 7 3 4 g Statistical analysis + 3 6 1 + 4 + 5 p Table 1 Effect of selected inhibitors of cell survival pathways on the anti-apoptotic effect of guanosine in SH-SY5Y cells Treatment DNA fragmentation (% of positive control) No inhibitor LY294002 10 μM PD98059 10 μM Control 10.1 ± 1.3 16.3 ± 3.1 24.0 ± 4.7 + a – – Guanosine pre-treatment 15.9 ± 4.8 b b Guanosine co-treatment 11.0 ± 0.7 b n.s. Guanosine post-treatment 12.4 ± 1.8 c n.s. + + pre-treatment + co-treatment + post-treatment 1 n pre-treated co-treated post-treated pre-treated co-treated or post-treated a p b p c p n.s. Results + + + 2 2 + p p 2 + Fig. 2 + + Materials and methods n + p p  + + + p 3 + p + 3 Fig. 3 + + + + Materials and methods n + p + + p  + + + + 1 post-treatment + 4 + p p 4 4 Pre-treatment + p 4 co-treatment + + p 4 + post-treatment at 24 h + post-treatment at 48 h + p 4 pre-treatment co-treatment + + post-treatment Fig. 4 + + + pre-treatment + co-treatment + post-treatment 1 + Materials and methods n + p p Pre-treatment co-treatment + + p Post-treatment + + p  + + 23 26 + + pre-treatment, co-treatment or post-treatment 5 5 + p 5 Pre-treatment + + p 5 co-treated + p 5 Post-treatment with guanosine at 24 h 1 + p 5 + post-treatment at 48 h + 5 pre-treatment, co-treatment post-treatment at 24 h + + Fig. 5 + + + pre-treatment + co-treatment + post-treatment 1 Materials and methods N p 8 n + p Pre-treatment co-treatment + + p Post-treatment + + p +  + + 27 29 + + + + + + + + Pertussis toxin abolishes the anti-apoptotic effect of guanosine 35 36 37 40 + + pre-treatment, co-treatment or post-treatment at 24 h + 6 Pre-treatment, co-treatment or post-treatment at 24 h + + p 6 + 6 + Fig. 6 + + pre-treatment + co-treatment + post-treatment 1 pre-treatment co-treatment post-treatment n + p Pre-treatment, or co-treatment post-treatment + + § p pre-treatment co-treatment post-treatment # p +  + 34 + + pre-treatment, co-treatment or post-treatment at 24 h 1 + 1 pre-treatment, or co-treatment or post-treatment at 24 h + + + p pre-treatment co-treatment p post-treatment at 24 h 1 pre-treatment + p 1 + co-treated post-treated at 24 + 1 + + + Discussion 33 34 + + + 23 29 + 2 + 2 + c + c 2 41 42 + 2 17 + 23 25 + + + 29 + 28 27 43 44 45 30 pre-treatment co-treatment 35 37 + 46 47 48 49 56 50 40 33 34 51 56 57 60 60 61 7 54 61 62 c 63 64 54 55 56 65 66 67 55 59 57 68 56 + pre-treatment co-treatment + + after post-treatment 38 38 + 69 71 + 27 72 73 after + 11 12 74 75 74 + post-treatment + 8 10 76 77 78 80 + 5 31 + + after