RESUMO
The turnover of the oxidized form of nicotinamide adenine dinucleotide (NAD+) has attracted interest in regard to longevity. Thus, compounds that can rapidly increase the cellular NAD+ concentration have been surveyed by many researchers. Of those, ß-nicotinamide mononucleotide (ß-NMN) has been focused on. Studies on the biosynthesis of NAD+ from ß-NMN have been reported at the cellular level, but not at the whole animal level. In the present study, we investigated whether ß-NMN is superior to nicotinamide (Nam) as a precursor of NAD+ in whole animal experiments. To this end we compared the NAD+ concentration in the blood and the urinary excretion amounts of NAD+ catabolites. Rats were intraperitoneally injected with ß-NMN or Nam. After the injection, blood samples and urine samples were collected at 3-h intervals. The concentration of blood total NAD (NAD11NADH) in each sample showed no significant differences between the two groups. The urinary excretion amounts of NAD+ catabolites in the urine samples collected at 3-6 h after the injection were lower in the ß-NMN group than in the Nam group. These results suggest that ß-NMN is retained in the body for longer than Nam.