Abstract

Objective: The present research examined the changes in oxidative stress biomarkers and mitochondrial functions of differentiated SH-SY5Y neuronal cells under hypoxia. Methods: SH-SY5Y cells that were differentiated were placed in 1% oxygen over 6, 12 or 24 h (n = 6). Cell viability, lactate dehydrogenase release, catalase activity, caspase-3 activity, intracellular Reactive Oxygen Species (ROS), malondialdehyde (MDA), protein carbonyls, glutathione status, superoxide dismutase and catalase activity, mitochondrial membrane potential (∆PSm), ATP production, mitochondrial superoxide, oxygen consumption rate, and respiratory Complex I/IV activity were measured. Findings: Hypoxia contributed to the progressive stabilization of HIF-1, high levels of ROS, oxidation of lipids and proteins, loss of glutathione stores, and loss of antioxidant enzyme activity. Mitochondrial abnormalities included the loss of ∆PSm, reduction in the production of ATP, a decline in oxygen consumption, deterioration of Complex I/IV activity, and an increase in mitochondrial superoxide. Close relationships between oxidative stress and bioenergetic failure were detected as there were strong negative correlations between ROS and ∆Ψm (r = -0.94) and between MDA and cell viability (r = -0.93). Conclusion: Persistent hypoxia induces an orchestrated oxidative stress and mitochondrial dysfunction which ultimately leads to neuronal apoptosis, making integrated redox and mitochondrial biomarkers useful tools in
mechanistic studies and neuroprotective drug discovery.

Keywords: Hypoxia, Oxidative stress, Reactive oxygen species, Mitochondrial dysfunction, Glutathione, Neuronal apoptosis