Dehydroascorbic acid impairs neurite growth through RIPK1-associated caspase activation

Axonal and neurite loss is a common event in neurodegenerative diseases, such as Alzheimer's disease or amyotrophic lateral sclerosis, which are enhanced by oxidative damage and reactive oxygen species (ROS) production. In the central nervous system, vitamin C can be found as ascorbic acid (AA), its reduced form, or dehydroascorbic acid (DHA), its oxidized form. Vitamin C mainly acts as an antioxidant agent, and homeostasis in the brain is maintained through its recycling between neurons and astrocytes. However, DHA accumulation under pathophysiological conditions has been associated with changes in neuronal metabolism and necroptotic cell death through RIPK1 activation. Furthermore, recent studies show that DHA accumulation induces significant neurite loss; however, it is unknown whether this effect is associated with RIPK1 activation. Here, we show that DHA treatment on neurospheres (NE) in vitro induces significant neurite shortening and reduced branching, effects associated with early RIPK1 activation and inhibited through Necrostatin-1s and zVAD-FMK treatment, suggesting the activation of apoptotic mechanisms. Finally, we propose DHA, the oxidized form of vitamin C, impairs neurite growth through ripk1-associated caspase activation.