• Ya-Ching Hsieh, Ross B Mounsey, and Peter Teismann.
• School of Medical Sciences, College of Life Sciences and Medicine, University of Aberdeen, Aberdeen, Scotland, UK.
• Naunyn Schmiedebergs Arch. Pharmacol. 2011 Aug 1; 384 (2): 157-67.

AbstractAccumulating evidence suggests that endogenous dopamine may act as a neurotoxin and thereby participate in the pathophysiology of Parkinson's disease (PD). Cyclooxygenase-2 (COX-2) has been implicated in the pathogenesis of PD due to its ability to generate reactive oxygen species (ROS). Inhibition of COX-2 leads to neuroprotection by preventing the formation of dopamine-quinone. In this study, we examined whether dopamine mediates 1-methyl-4-phenylpyridinium (MPP(+))-induced toxicity in primary ventral mesencephalic (VM) neurons, an in vitro model of PD, and if so, whether the protective effects of COX-2 inhibitors on dopamine mediated MPP(+)-induced VM neurotoxicity and VM dopaminergic cell apoptosis result from the reduction of ROS. Reserpine, a dopamine-depleting agent, significantly reduced VM neurotoxicity induced by MPP(+), whereas dopamine had an additive effect on MPP(+)-induced VM neurotoxicity and VM dopaminergic cell apoptosis. However, inhibition of COX-2 by a selective COX-2 inhibitor (DFU) or ibuprofen significantly attenuated MPP(+)-induced VM cell toxicity and VM dopaminergic cell apoptosis, which was accompanied by a decrease in ROS production in VM dopaminergic neurons. These results suggest that dopamine itself mediates MPP(+)-induced VM neurotoxicity and VM dopaminergic cell apoptosis in the presence of COX-2.

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