Reversibility of Age-related Oxidized Free NADH Redox States in Alzheimer’s Disease Neurons by Imposed External Cys/CySS Redox Shifts

Imposed extracellular Cys/CySS redox states modulate intracellular NADH levels

Age-associated oxidative stress lowers both total (bound + free) NADH levels^11,18 and free NADH in neurons¹⁵ in varying proportions. To study free NADH in live neurons as a function of age and transgenic AD genotype, we isolated and cultured neurons in a uniform medium from mice at young, middle and old ages, removed from a complicated aging context in vivo including age-related inflammation, hormones and vasculature. To study how the external redox shifts impact intracellular free NADH levels and distributions, we applied a 120 fs pulsed laser excitation for fluorescence lifetime imaging microscopy (FLIM) to distinguish free NADH from bound forms (Fig. 1) at a normal balance of extracellular Cys/CySS (−50 mV), an imposed oxidative state (0 mV, excess CySS) and an imposed reductive treatment…