The Vitamin A Derivative All-Trans Retinoic Acid Repairs Amyloid-β-Induced Double-Strand Breaks in Neural Cells and in the Murine Neocortex
Aβ effects on the apoptotic cascade, on DSBs, and on cell viability in presence of the caspase-3 inhibitor z-VAD or RA. (a) Pictures of phase contrast microscopy with SH-SY5Y cells treated with 20 μM Aβ and/or 50 μM z-VAD did not show cell death, whereas treatment with 100 nM staurosporine resulted in apoptotic cell death after 24 h, not after 30 min. Scale bar = 200 μm. (b) Measures of caspase-3/caspase-7 (CaspaseGlo assay) after 30 min and 24 h treatment with Aβ and/or z-VAD or staurosporine (STA). Caspases were activated in the control cell cultures (Ø = without treatment) and in presence of Aβ after 30 min and 24 h but were not able to induce cell death. A nonsignificant increase of caspases between 30 min and 24 h resulted in cell death (a). (c) Box plot of mean comet tail lengths after treatments with Aβ and/or z-VAD shows that Aβ-induced DSBs in SH-SY5Y are not related to apoptotic DSBs after 30 min, whereas they are related to apoptotic DSBs at 24 h (number of cells measured: ). (d) Measures of viability (Glomax assay) of astrocytic DI TNC1 cells treated for 30 min with RA (5 μM) and/or Aβ (20 μM) or digitonin (3.3 mM) (). A similar result was observed with SH-SY5Y cells, that is, no alteration of viability despite RA and/or Aβ treatments. (e) Measures of viability (Glomax assay) of cells from cortical tissue of young (dark gray; 4 months; ) and aged mice (light gray; 16 months; ) after treatments with RA and/or Aβ or digitonin during 30 min. Viability is less significantly decreased in presence of RA. ANOVA with Bonferroni correction: ; ns = not significant; Ø = without treatment for 30 min.