Enzyme-linked immunosorbent assay (ELISA)

Aβ and sAPPα concentrations of the hippocampal samples were measured using four ELISA kits: Human amyloid β (1–42) Assay Kit (IBL, Hokkaido, Japan, 27,711), human amyloid β (1–40) Assay Kit (IBL, 27,713), human sAPPα high sensitive ELISA (IBL, JP27734), and Mouse/Rat sAPPα (highly sensitive) ELISA (IBL, JP27419). The procedures were performed according to the kit instructions. ELISA for mouse and human sAPPα were performed on the soluble fraction (as prepared for western blotting), and ELISA for human Aβ (1–42) and (1–40) were performed in both the soluble and insoluble fractions. Despite its ability to detect recombinant human sAPPα samples, the human sAPPα kit was not able to detect either native or virus-mediated sAPPα expression in the Tg mice, and thus we could not determine degree of up-regulation of sAPPα levels in the tissue. Therefore copGFP expression was used as the marker of successful transduction in the hippocampus.