NAD+ replenishment can restore ATP levels and rescue premature aging in Cockayne syndrome mice. However, there has been no mechanistic study regarding the effects of NAD+ and NADH on intracellular ATP levels under basal conditions. In our current study, we used BV2 microglia to test our hypothesis that NAD+ and NADH can increase intracellular ATP levels under basal conditions. We found that both NAD+ and NADH significantly increased the intracellular ATP levels of BV2 microglia, which were attenuated by SIRT2 siRNA, the SIRT2 inhibitor AGK2, and the phosphatidylinositol 3-kinase/Akt inhibitor LY294002. Our study has also suggested that SIRT2 mediates the NAD+-induced and NADH-induced increase in Akt phosphorylation in BV2 microglia. Collectively, our study has suggested that SIRT2 mediates both NAD+-induced and NADH-induced increases in the intracellular ATP levels of BV2 microglia by modulating Akt phosphorylation.