Progressive accumulation of α-syn affects presynaptic proteins in ageing animals. (A-C) Expression levels of WT-α-syn-EGFP expressed under the control of pan-neuronal driver nSyb-Gal4 increased at 20 days of age compared with the levels observed in fly brains at 3 days of age; *P = 0.0411, ns—not significant P > 0.05, n = 7–9. Such accumulation was specific for WT-α-syn-EGFP since the control flies expressing EGFP only (A, B) showed no alteration in the expression levels of EGFP. (D, E) The expression levels of the synaptic vesicle protein Synapsin were reduced in flies expressing WT-α-syn-EGFP at Day 3 (**P = 0.0024) and 20 (**P = 0.0056) compared with control flies; n = 3–6. (F, G) The expression levels of Syntaxin, a protein of the presynaptic SNARE complex, also had its levels reduced at Day 20 in fly brain expressing WT-α-syn-EGFP compared with control; *P = 0.0151, ns—not significant P > 0.05, n = 3–6. Mean ± SEM are shown, statistical analyses were performed using unpaired two-tailed t-test. Full uncropped blots are available in Supplementary material.