Oxidative changes in brain pyridine nucleotides and neuroprotection using nicotinamide

Area of Science:

• Neuroscience
• Biochemistry
• Cell Biology

Background:

• Pyridine nucleotides (NAD+, NADH, NADP+, NADPH) are vital for cellular redox balance and energy metabolism.
• Oxidative stress disrupts these critical functions, impacting brain health.
• Understanding nucleotide dynamics during oxidative stress is crucial for neuroprotection.

Purpose of the Study:

• To investigate changes in pyridine nucleotide levels in six mouse brain regions following t-butyl hydroperoxide (t-BuOOH) induced oxidative stress.
• To explore the relationship between NAD+ depletion and DNA fragmentation.
• To evaluate the neuroprotective potential of nicotinamide in mitigating oxidative stress-induced brain damage.

Main Methods:

• Intracerebroventricular injection of t-BuOOH to induce oxidative stress in mice.
• Measurement of pyridine nucleotide levels (NAD+, NADH, NADP+, NADPH) in brain homogenates.
• Assessment of DNA fragmentation as a marker of cell death.
• Administration of nicotinamide to assess its effects on nucleotide levels and DNA damage.

Main Results:

• t-BuOOH rapidly oxidized NADPH and slowly depleted NAD+ in most brain regions, with a slight NADH increase in five regions.
• NAD+ depletion correlated with increased DNA fragmentation, suggesting poly(ADP-ribose) polymerase (PARP) activation and a cell death cascade.
• Nicotinamide administration increased brain NAD+ levels, preventing DNA fragmentation in some regions and upregulating other pyridine nucleotides.

Conclusions:

• Oxidative stress significantly alters brain pyridine nucleotide metabolism, leading to NAD+ depletion and DNA damage.
• Nicotinamide, by replenishing NAD+ stores, demonstrates neuroprotective effects against oxidative stress.
• Nicotinamide represents a promising therapeutic avenue for neurodegenerative conditions characterized by oxidative stress.