Fig. 4. GS promote NAD+-dependent SIRT1 activation in cardiomyocytes and neurons . (A) The NAD+ levels in H9c2 and neurons treated with different concentrations of GS for 48 h were measured by a luminescence -based kit. (B) The NAD level in control and GS-treated H9c2 cells was analyzed by the LC-MS/MS method. (C) After GS treatment for 8 h, SIRT1 and PGC-1α mRNA levels in H9c2 cells and primary neurons were analyzed by qPCR analysis. β-Actin is used as internal control.(D-E) The levels of SIRT1, PGC-1α, Nrf1, and Nrf2 in H9c2 and PC12 cells pretreated with different concentrations of GS for 48 h were examined by Western blot analysis. β-Actin is loading control. Semi-quantitative analysis of relative expression for each protein is shown on the right. Ctrl: control group. *P < 0.05, **P < 0.01, and ***P < 0.001versus Ctrl group.