Biochemical Analysis of Amyloid-Beta Levels

Biochemical analysis of Aβ levels was performed as previously described [18 (link)]. Briefly, soluble protein was extracted from the right frontal cortex using PBS with complete protease and phosphatase inhibitor (Pierce Biotechnology). After centrifugation, the supernatant was labeled the “soluble” extract, and the pellet was homogenized in 70% formic acid. After centrifugation and neutralization with 1 M Tris-HCl, the supernatant was labeled the “insoluble” extract. Protein concentrations were determined using the BCA protein assay kit (Pierce Biotechnology). The Meso-Scale Discovery multiplex ELISA system was used to measure Aβ1–38, Aβ1–40, and Aβ1–42 levels in the soluble and insoluble extracts (V-PLEX Aβ Peptide Panel 1 (6E10) Kit; MSD).