Figure 1

Imposed external Cys/CySS oxidative and reductive states shift the internal NADH redox state in neurons from NTg and 3xTg-AD female mice. FLIM NADH Intensities were collected from NTg (A–C) and 3xTg-AD (a–c) in young age neurons under 0 mV (oxidative), −50 mV (normal medium as control, no treatment) and −150 mV Cys/CySS (reductive) redox states. (D) Phasor plot of the same NTg and (d) 3xTg-AD young age neurons illustrate the shifts of the intracellular free/bound NADH ratios toward more free NADH at reductive −150mV and to more bound NADH with imposed external oxidative state of 0 mV. Each cluster represents NADH signals from pixels of the corresponding single neuron on the left. The colored arrow indicates the direction of shifts from free to bound NADH with imposed reductive to oxidative states. Corresponding free /bound NADH FLIM color maps of the NTg (E–G) and 3xTg-AD (e–g) of young age neurons demonstrate intracellular NADH shifts to higher free/bound NADH proportions with an external reductive shift showing more cyan-green. In the FLIM fraction colormap, pink-purple regions indicate more bound NADH and green-cyan refers to more free NADH fraction. An imposed oxidative stress to 0 mV shifted the cellular distribution of NADH free/bound ratio toward more red-purple, indicating a shift to a lower free/bound NADH fraction. Similarly, FLIM NADH intensities were collected in old age neurons from NTg (H–J) and 3xTg-AD mouse neurons (h–j) following the indicated redox treatments. Phasor plot of the same NTg (N) and (n) 3xTg-AD old neurons shows the manipulation of intracellular free/bound NADH ratios of neurons in response to the imposed external Cys/CySS oxidative and reductive states. The dashed vertical orange line indicates the G value at the center of NTg young cluster at the −50 mV (normal) Cys/CySS condition for reference. Corresponding free and bound NADH distributions from old neurons of NTg (L–N) and 3xTg-AD (l–n) mice with imposed redox states.