The study contained three groups of Sprague-Dawley male rats – two groups of aging animals (22-24 months) separated based on performance in spatial reference memory task; and the third, control group of young animals () not separated by behavioural testing. The synaptosome – enriched membrane fraction of the dentate gyrus was isolated from nine randomly chosen individuals per group and analysed by tandem mass tag (TMT) labelling and mass spectrometry (MS)-based quantitative proteomics. The proteomic experiment was performed in three TMT10plex sets, with each set containing samples from three biological replicates per group and one TMT 126 reference channel reserved to directly compare the protein intensities across the entire study. The peptides were analysed in two parallel MS runs representing two technical replicates per biological sample. The total number of 6513 protein entries was identified of which 471 showed a significantly changed level (p<0.05) in any of the three animal groups. The comparison between aged and young animals revealed 293 significantly changed proteins (p<0.05) in aged good performers vs young rats, and 310 significant proteins (p < 0.05) in aged bad performers vs young ones. The proteomic differences between aged good vs bad performers were represented by 78 significantly changed proteins (p < 0.05).