Fig. 4.

Insulin reduces intracellular levels of Aβ in N2a cells. Cells were treated for 4 or 16 hr with or without 1 μm insulin and lysed in SDS. a, b, Intracellular Aβ was detected by immunoprecipitation with 4G8, followed by SDS-PAGE and Western blotting, using 6E10 monoclonal antibody, which recognizes only Aβ1–40/42. a, Representative autoradiographic analysis of intracellular Aβ after 16 hr of treatment in the absence or presence of 1 μminsulin. b, Quantitative analysis of intracellular Aβ after treatment with insulin for 4 or 16 hr. Data represent means ± SD; n = 5. *p < 0.05 versus control. c, IP–MS analysis of intracellular Aβ40/42 levels after 4 hr of treatment with 1 μm insulin.d, e, Western blot analysis for full-length βAPP (d) and the PS-1 N-terminal fragment (e) after 16 hr of treatment with 1 μm insulin.