NAD+ and Sirtuin Signalling: A Researcher's Overview
NAD+ has become one of the most studied molecules in longevity and metabolic research. This overview covers its role as a sirtuin substrate and its relationship with cellular energy metabolism.
Nicotinamide adenine dinucleotide (NAD+) is a coenzyme present in all living cells and central to two of the most studied areas in contemporary biochemical research: cellular energy metabolism and the sirtuin signalling pathway. Over the past decade, interest in NAD+ has intensified significantly, driven by observations of age-associated NAD+ decline and its downstream consequences for metabolic and cellular function.
NAD+ as a Redox Cofactor
NAD+ and its reduced form NADH serve as essential electron carriers in cellular respiration. The NAD+/NADH ratio is a critical indicator of cellular redox state, and dysregulation of this ratio has been associated with metabolic dysfunction in numerous preclinical models. Complex I of the mitochondrial electron transport chain accepts electrons from NADH, converting it back to NAD+ — making the availability of NAD+ central to efficient oxidative phosphorylation and ATP production.
Sirtuin Pathway Research
The sirtuin family of NAD+-dependent deacylases (SIRT1–7) has attracted enormous research interest since the early 2000s. These enzymes consume NAD+ as a substrate during their catalytic activity, linking cellular energy status directly to gene expression regulation, protein modification, and stress response.
SIRT1, the most studied member, has been examined in the context of mitochondrial biogenesis, fatty acid oxidation, gluconeogenesis, and inflammatory pathway modulation. Importantly, SIRT1 activity is directly dependent on NAD+ availability — declining NAD+ levels reduce sirtuin activity regardless of enzyme expression levels. This has made NAD+ supplementation in model systems a key tool for investigating sirtuin-dependent biology.
SIRT3, localised to the mitochondrial matrix, has been studied for its role in acetylation of metabolic enzymes and antioxidant regulation. SIRT5 has attracted interest for its involvement in ammonia detoxification and fatty acid oxidation. Research across the sirtuin family continues to expand understanding of how NAD+ availability shapes cellular metabolic phenotype.
PARP Competition and DNA Repair
NAD+ is also consumed by poly(ADP-ribose) polymerases (PARPs) during DNA damage repair. PARP hyperactivation — which can occur in response to significant genotoxic stress — can deplete cellular NAD+ pools rapidly, creating competition with sirtuin enzymes for substrate. This dynamic has been studied extensively in the context of ageing and age-related disease models, where chronic low-level DNA damage may contribute to progressive NAD+ depletion.
Age-Related Decline
Numerous published studies have documented declining NAD+ levels with age in multiple tissues and species, including humans. This decline has been associated with reduced mitochondrial function, impaired stress responses, and metabolic dysfunction. The mechanisms underlying age-related NAD+ decline remain an area of active investigation, with proposed contributors including increased PARP activity, reduced biosynthetic enzyme expression, and altered NAD+ consumption patterns.
Mercia Research Supply
Mercia Research supplies NAD+ in a 3ml pre-loaded pen cartridge containing 500mg, pre-mixed and ready for laboratory application. Each batch is independently verified to ≥99.0% purity with a lot-matched COA included.
All products supplied by Mercia Research are for laboratory research use only. Not intended for human or animal consumption.