"We first evaluated the extent to which two precursors of NAD+ synthesis, nicotinamide mononucleotide (NMN) and nicotinamide riboside (NR), elevated NAD+ in the neonatal mouse brain. We found that only NR elevated NAD+ levels in the brain of P3 mice when injected intraperitoneally"
https://www.nature.c...467-020-15794-9