Fig 1: Levels of SV2A, GAP43, SNAP25, and SYN1.Quantification of presynaptic proteins in extracts from the cerebral cortex (A–D) and the hippocampus (E–H) from control, diabetic (Db), and Insulin‐treated (Ins). The synaptic proteins SV2A (A, E), GAP43 (B, F), SNAP25 (C, G), and SYN‐1 (D, H) were all measured using ELISA assays and expressed as pg/mg protein. Both in the cerebral cortex and in the hippocampus, the concentration of SV2A was significantly higher in the Db rats compared to the control and Ins groups (p < 0.0001). In any of the two tissues, the SV2A concentration in the animals treated with insulin was not different from the control. None of the other proteins displayed a significant difference between the groups. Values were given as mean ± SD. Comparisons were performed between the control, Db, and Ins group for each target protein by one‐way ANOVA test. (**p < 0.01, *** p < 0.001, **** p < 0.0001).