Biotinylated secondary goat anti rabbit or goat anti mouse antibody

For all antigens, antibodies were validated (see Supplementary Table 2) and assessed on human paraffin sections. Sections were deparaffinized in xylene and rehydrated in a series of ethanol, and antigen retrieval was completed. Free-floating rat brain and rehydrated human hippocampal tissue samples were incubated in 0.6% H2O2 for 30 min and blocked in 5% goat serum (0.1% Triton X-100; Sigma-Aldrich, St. Louis, MO, USA) for 1 h at room temperature (RT). Sections were incubated with primary antibodies overnight at 4 °C. Primary antibodies, dilutions and validation information are included in Supplementary Table 2. After overnight incubation, sections were washed and incubated with biotinylated secondary goat anti-rabbit or goat anti-mouse antibody (1:200, Vector Laboratories, Burlingame, CA, USA) at RT for 1 h. Subsequently, avidin–biotin–peroxidase complex (ABC Elite Kit, Vector Laboratories) was applied for 1 h at RT, and then the positive cells were visualized using 3,3′-diaminobenzidine (DAB; Sigma-Aldrich). BioQuant Nova Advanced Image Analysis (R&M Biometric, Nashville, TN, USA) was used for image capture and analysis using a modified stereology method previously described [31 (link)]. Slides were coded for blind quantification. For rats, 3–5 sections of the dorsal DG (bregma from −2.12 to −4.52 mm) were quantified as described previously [9 (link)].