NAD+ (Nasal)

Unlike a classic ligand-receptor peptide, NAD+ functions chiefly as an enzymatic cofactor rather than acting on a single surface receptor. Research suggests its primary binding targets are intracellular enzymes that consume or recycle it, including sirtuins, PARPs, and the CD38/CD157 ecto-enzymes, while cell-surface purinergic (P2) receptors are studied as potential responders to extracellular NAD+ and its metabolites. Intranasal delivery is investigated as a route that may favor uptake along the nasal mucosa and olfactory pathway.

In study models, NAD+ availability is associated with activation of NAD+-dependent sirtuin deacylases (notably SIRT1 and SIRT3), which are linked to deacetylation of transcriptional regulators such as PGC-1alpha and FOXO. Research suggests downstream effects on mitochondrial biogenesis signaling, the AMPK energy-sensing axis, and DNA-repair enzymes (PARPs) that draw on the NAD+ pool. These pathways are studied for their connection to cellular stress resilience and metabolic homeostasis.

Because the intranasal route is studied partly for access toward the central nervous system, research explores whether NAD+ may influence neuronal energy metabolism and redox status. In study models, NAD+ precursors are associated with support of mitochondrial function in neural tissue and with pathways relevant to neuronal maintenance, though direct receptor-mediated neural signaling is not the primary described mechanism. Findings in this area remain preliminary and continue to be investigated.

Systemically, NAD+ is central to redox reactions (the NAD+/NADH couple) that drive glycolysis, the citric acid cycle, and oxidative phosphorylation, linking it to whole-body energy metabolism. Research associates NAD+-consuming enzymes such as CD38 and the sirtuins with immune signaling, circadian regulation, and metabolic flexibility. In study models, maintaining the NAD+ pool is explored for its relationship to cellular aging markers and adaptive stress responses.