Decline in NAD+ availability is tightly linked to many neurological disorders. Our recent study also revealed age dependences of intracellular NAD+, NADH and total NAD concentrations in healthy human brains. Accumulating evidences have shown that the cellular NAD+ could serve as a therapeutic target for treating metabolic or age-related neurological diseases and promoting longevity. Therefore, to investigate the effect of exogenous NAD+ on intracellular NAD metabolism, the in vivo 31P-MRS NAD imaging assay developed in our lab was applied in normal rat brains at 16.4 T. Significant increases of cerebral α-ATP, total NAD and NAD+ levels were observed after the intra-peritoneal infusion of exogenous NAD+. This study not only demonstrates the feasibility of using exogenous NAD+ to enhance cerebral ATP and NAD metabolisms, but also provides an opportunity to better understand the roles of NAD metabolism in health and age-related disease.