Nicotinamide Adenine Dinucleotide (NAD + ) Repletion Attenuates Bupivacaine-Induced Neurotoxicity

Bupivacaine is one of the most toxic local anesthetics but the mechanisms underlying its neurotoxicity are still unclear. Intracellular nicotinamide adenine dinucleotide (NAD+) depletion has been demonstrated to play an essential role in neuronal injury. In the present study, we investigated whether intracellular NAD+ depletion contributes to bupivacaine-induced neuronal injury and whether NAD+ repletion attenuates the injury in SH-SY5Y cells. First, we evaluated the intracellular NAD+ content after bupivacaine exposure. We also examined the cellular NAD+ level after pretreatment with exogenous NAD+. We next determined cell viability and the apoptosis rate after bupivacaine treatment in the presence or absence of NAD+ incubation. Finally, cell injuries such as nuclear injury, reactive oxygen species (ROS) production, and mitochondrial depolarization were detected after bupivacaine treatment with or without NAD+ pretreatment. Bupivacaine caused intracellular NAD+ depletion in a time- and concentration-dependent manner. Cellular NAD+ replenishment prevented cell death and apoptosis induced by bupivacaine. Importantly, exogenous NAD+ attenuated bupivacaine-induced nuclear injury, ROS production, and mitochondrial depolarization. Our results suggest that NAD+ depletion is necessary for bupivacaine-induced neuronal necrosis and apoptosis, and that NAD+ repletion attenuates neurotoxicity resulting from bupivacaine-treatment.