Figure 5.

Calpain inhibitors completely blocked the generation of the 17 kDa tau fragment induced by pre-aggregated Aβ in cultured hippocampal neurons. A, B, Western blot analysis of active calpain-1, cleaved spectrin, and 17 kDa tau fragment content in whole-cell extracts prepared from 21-d-in-culture hippocampal neurons treated with either ALLN (A) or MDL 28,170 (B), two calpain inhibitors, 1 h before the treatment with pre-aggregated Aβ (20 μm) for 4 and 8 h using specific antibodies. C-H, Graphs showing changes in the content of active calpain-1 (C, D), calpain-specific cleavage product of spectrin (E, F), and 17 kDa tau fragment (G, H) in hippocampal neurons treated with ALLN (C, E, G) or MDL 28, 170 (D, F, H) before the addition of Aβ. Data were obtained using Molecular Analyst software and normalized using total calpain-1, spectrin, tau, and tubulin as internal controls. Values are expressed as a percentage of untreated controls, considering the values obtained in these neurons as 100%. Each number represents the mean ± SEM from three different experiments. ^*p < 0.05, ^**p < 0.01, different from control.