TY - JOUR T1 - NAD<sup>+</sup> Depletion Is Necessary and Sufficient forPoly(ADP-Ribose) Polymerase-1-Mediated Neuronal Death JF - The Journal of Neuroscience JO - J. Neurosci. SP - 2967 LP - 2978 DO - 10.1523/JNEUROSCI.5552-09.2010 VL - 30 IS - 8 AU - Conrad C. Alano AU - Philippe Garnier AU - Weihai Ying AU - Youichirou Higashi AU - Tiina M. Kauppinen AU - Raymond A. Swanson Y1 - 2010/02/24 UR - http://www.jneurosci.org/content/30/8/2967.abstract N2 - Poly(ADP-ribose)-1 (PARP-1) is a key mediator of cell death in excitotoxicity, ischemia, and oxidative stress. PARP-1 activation leads to cytosolic NAD+ depletion and mitochondrial release of apoptosis-inducing factor (AIF), but the causal relationships between these two events have been difficult to resolve. Here, we examined this issue by using extracellular NAD+ to restore neuronal NAD+ levels after PARP-1 activation. Exogenous NAD+ was found to enter neurons through P2X7-gated channels. Restoration of cytosolic NAD+ by this means prevented the glycolytic inhibition, mitochondrial failure, AIF translocation, and neuron death that otherwise results from extensive PARP-1 activation. Bypassing the glycolytic inhibition with the metabolic substrates pyruvate, acetoacetate, or hydroxybutyrate also prevented mitochondrial failure and neuron death. Conversely, depletion of cytosolic NAD+ with NAD+ glycohydrolase produced a block in glycolysis inhibition, mitochondrial depolarization, AIF translocation, and neuron death, independent of PARP-1 activation. These results establish NAD+ depletion as a causal event in PARP-1-mediated cell death and place NAD+ depletion and glycolytic failure upstream of mitochondrial AIF release. ER -