SIRT1 inhibitor nicotinamide partly attenuated resveratrol’s protection against Aβ_25–35.

<p>To further determine the role of SIRT1 in resveratrol’s protection of PC12 cells, nicotinamide was added into culture medium in the resveratrol protection group. The growth of PC12 cells was observed under phase contrast microscope (A–C), and cell apoptosis was detected by Hoechst 33342 (blue) and PI (red) double staining (D–F) and observed under Zeiss LSM 780 laser cofocal microscope. Nicotinamide (C and F) attenuated the protection of resveratrol (B and E) on PC12 cells. A and D were the Aβ_25–35 injury group. MTT assay (G) and cell apoptosis analysis (H) were preformed. Data were presented as mean ± S.E.M. **<i>p</i> < 0.01, compared with the Aβ_25–35 injury group; ^##<i>p</i> < 0.01, compared with the nicotinamide group by Student’s <i>t</i>-test (n = 9). Scale bars: A-C, 50 µm; D-F, 50 µm.