Fig. 7

Analysis of calpain activity and heat shock protein (Hsp) expression in response to NaOH-Aβ42 and NH4OH-Aβ42 treatment. A Enhanced calpain activity was evident only in cells treated with NaOH-Aβ42 for 4 days, as indicated by the reduction of the full-length spectrin form (~ 255 kDa) to 65.64% (n = 3, p = 0.00039) and parallel elevation of a lower-weight spectrin form (~ 150 kDa) to 120.15% (n = 3, p = 0.01293). B The levels of Hsp70 and Hsp90 showed a consistent increase in response to both NaOH-Aβ42 and NH4OH-Aβ42 treatments, observed in both 2- and 4-day applications (Hsp70: after 2 days of exposure to NaOH-Aβ42 139.73%, n = 3, p = 0.00735, and 169.86%, n = 3, p = 0.00038 after NH4OH-Aβ42 applications, after 4 days of exposure 154.15%, n = 3, p = 0.00104 after NaOH-Aβ42, and 141.05%, n = 3, p = 0.00439 after NH4OH-Aβ42 application; Hsp90: after 2 days of exposure 135.22%, n = 3, p = 0.01930 after NaOH-Aβ42 and 157.83%, n = 3, p = 0.00172 after NH4OH-application, after 4 days of exposure 121,41%, n = 3, p = 0.00489 after NaOH-Aβ42 and 119.44%, n = 3, p = 0.00877 after NH4OH-Aβ42 application). Hsp27, however, was significantly increased only after 4 days of NH4OH-Aβ42 exposure, indicating a specific protective response (174.89%, n = 3, p = 0.00513). Statistical significance level versus untreated samples: *p ≤ 0.05, **p ≤ 0.01, ***p ≤ 0.001