The role of NADPH oxidase 1-derived reactive oxygen species in paraquat-mediated dopaminergic cell death.
Oxidative stress is the common downstream effect of a variety of environmental neurotoxins that are strongly implicated in the pathogenesis of Parkinson's disease. We demonstrate here that the activation of NADPH oxidase 1 (Nox1), a specialized superoxide-generating enzyme complex, plays a key role in the oxidative stress and subsequent dopaminergic cell death elicited by paraquat. Paraquat increased the expression of Nox1 in a concentration-dependent manner in rat dopaminergic N27 cells. Rac1, a key component necessary for Nox1-mediated superoxide generation, also was activated by paraquat. Paraquat-induced reactive oxygen species generation and dopaminergic cell death were significantly reduced after pretreatment with apocynin, a putative NADPH oxidase inhibitor, and Nox1 knockdown with siRNA. Male C57BL/6 mice received intraperitoneal (IP) injections of paraquat (10 mg/kg) once every 3 days and showed increased Nox1 levels in the substantia nigra as well as a 35% reduction in tyrosine hydroxylase-positive dopaminergic neurons 5 days after the last injection. Preadministration of apocynin (200 mg/kg, IP) led to a significant decrease in dopaminergic neuronal loss. Our results suggest that Nox1-generated superoxide is implicated in the oxidative stress elicited by paraquat in DA cells, and it can serve as a novel target for pharmacologic intervention.
Cristóvão
Ana Clara
AC
Neurology/Neuroscience Department, Weill Medical College of Cornell University, New York, New York, USA.
Choi
Dong-Hee
DH
Baltazar
Graça
G
Beal
M Flint
MF
Kim
Yoon-Seong
YS
D000818:Animals; D001483:Base Sequence; D015153:Blotting, Western; D016923:Cell Death / Q000187:drug effects*; D002460:Cell Line; D017931:DNA Primers; D004298:Dopamine / Q000378:metabolism*; D007150:Immunohistochemistry; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D009247:NADH, NADPH Oxidoreductases / Q000235:genetics / Q000378:metabolism*; D000074624:NADPH Oxidase 1; D010269:Paraquat / Q000633:toxicity*; D034741:RNA, Small Interfering; D051381:Rats; D017382:Reactive Oxygen Species / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction
D017931:DNA Primers; D034741:RNA, Small Interfering; D017382:Reactive Oxygen Species; D009247:NADH, NADPH Oxidoreductases; D000074624:NADPH Oxidase 1; C000614711:NOX1 protein, mouse; C000614712:NOX1 protein, rat; D010269:Paraquat; D004298:Dopamine