Compartmentalized oxidative stress in dopaminergic cell death induced by pesticides and complex I inhibitors: Distinct roles of superoxide anion and superoxide dismutases

Abstract

The loss of dopaminergic neurons induced by the parkinsonian toxins paraquat, rotenone and 1-methyl-4-phenylpyridinium (MPP+) is associated with oxidative stress. However, controversial reports exist regarding the source/compartmentalization of reactive oxygen species (ROS) generation and its exact role in cell death. We aimed to determine in detail the role of superoxide anion (O2•−), oxidative stress and their subcellular compartmentalization in dopaminergic cell death induced by parkinsonian toxins. Oxidative stress and ROS formation was determined in the cytosol, intermembrane (IMS) and mitochondrial matrix compartments, using dihydroethidine derivatives, the redox sensor roGFP, as well as electron paramagnetic resonance spectroscopy. Paraquat induced an increase in ROS and oxidative stress in both the cytosol and mitochondrial matrix prior to cell death. MPP+ and rotenone primarily induced an increase in ROS and oxidative stress in the mitochondrial matrix. No oxidative stress was detected at the level of the IMS. In contrast to previous studies, overexpression of manganese superoxide dismutase (MnSOD) or copper/zinc SOD (CuZnSOD) had no effect on ROS steady state levels, lipid peroxidation, loss of mitochondrial membrane potential (ΔΨm) and dopaminergic cell death induced by MPP+ or rotenone. In contrast, paraquat-induced oxidative stress and cell death were selectively reduced by MnSOD overexpression, but not by CuZnSOD or manganese-porphyrins. However, MnSOD also failed to prevent ΔΨm loss. Finally, paraquat, but not MPP+ or rotenone, induced the transcriptional activation the redox-sensitive antioxidant response elements (ARE) and nuclear factor kappa-B (NF-κB). These results demonstrate a selective role of mitochondrial O2•− in dopaminergic cell death induced by paraquat, and show that toxicity induced by the complex I inhibitors rotenone and MPP+ does not depend directly on mitochondrial O2•− formation.

Overexpression of alpha-synuclein at non-toxic levels increases dopaminergic cell death induced by copper exposure via modulation of protein degradation pathways

“…Oxidative stress was determined using dihydroethidine (DHE, 5 μM, Life Technologies/Molecular Probes), which after its oxidization to ethidium intercalates within the DNA and exhibits bright red fluorescence (Franco et al, 2007; Rodriguez-Rocha et al, 2013). Alterations in the redox state of both cytosol and mitochondrial compartments were monitored using the reduction-oxidation sensitive green fluorescent protein (roGFP) sensor as done before (Rodriguez-Rocha et al, 2013).…”

“…Alterations in the redox state of both cytosol and mitochondrial compartments were monitored using the reduction-oxidation sensitive green fluorescent protein (roGFP) sensor as done before (Rodriguez-Rocha et al, 2013). When indicated, changes in GSH content were determined by flow cytometry using monochlorobimane (mBCl, 10 μM, Life Technologies/Molecular Probes).…”

Antioxidant potential of CORM-A1 and resveratrol during TNF-α/cycloheximide-induced oxidative stress and apoptosis in murine intestinal epithelial MODE-K cells

“…The role of NOX-1-dependent ROS generation during proliferation of mouse small intestinal(Jones et al, 2013) and colonic epithelium(Coant et al., 2010) has been recently proposed. Hence, it seems plausible that ROS generation pre-treatment of MODE-K cells with resveratrol before exposure to TNF-α/CHX might have activated the proliferative machinery to defend against the successive stress insult.We suggested that treatment of MODE-K cells with TNF-α/CHX might involve an early phase of mitochondria-derived ROS production inducing a later phase of NOX-derived ROS production as mitochondrial complex inhibitors show a more pronounced decrease in total ROS levels and cell death as compared to the moderate effect of the NOX inhibitor, VAS-2870(Babu et al, 2015).…”

The evaluation of the changes in enzymatic antioxidant reserves and lipid peroxidation in chosen parts of the brain in an animal model of Parkinson disease

“…Those enzymes catalyze the removal of the toxic superoxide radical by converting it into hydrogen peroxide and molecular oxygen. 15 Research indicates that overexpression of SOD and its isoenzymes may protect efficiently against neuronal loss.…”