Non‐phagocytic NADPH oxidase is present in dopaminergic neurons

Abstract

Oxidative stress is a key contributor to the pathogenesis of Parkinson's disease. NADPH oxidase is a membrane enzyme responsible for the oxidative burst in activated phagocytes. NADPH oxidase also exists in many types of non‐phagocytic cells including vascular cells and neurons, with a wide distribution throughout the brain. Although the microglial NADPH oxidase is known to participate in dopaminergic neurotoxicity, whether NADPH oxidase also exists in the dopamine neurons in the substantia nigra pars compacta (SNpc) and whether it contributes to the ROS generation has not been explored. We have examined the role of NADPH oxidase in MPP+ induced oxyradical production in immortalized dopaminergic cell line (N27). MPP+ dose dependently led to upregulation of ROS in N27 cells, which was attenuated by 40% with treatment with NADPH oxidase inhibitors. N27 cells were observed to express mRNA for all the necessary components of the NADPH oxidase, Nox2, p22, p40, p47 and p67, as well as Nox1 and Nox4. SiRNA‐mediated knockdown of p22, a critical stabilizing subunit of the NADPH oxidase, reduced the amount of ROS generated. Immunocytochemical examination of mouse dopaminergic neurons in sections of the SNpc revealed that these neurons express Nox2, p47 and p67. While our results suggest that NADPH oxidase is a contributor to ROS generation in dopaminergic neurons, the functional role of this process remains to be defined. Supported by NIH AA016654 and The Neuroscience Program at the UCD.