Methylmercury and Paraquat Induced Toxicity in the Mitochondria of Dopamine Neurons

Abstract

Methylmercury and Paraquat are environmental toxins that affect the central nervous system. Exposure to Paraquat and methylmercury causes movement impairments similar to the symptoms of Parkinson’s disease (PD). The degeneration of dopamine neurons due to mitochondrial dysfunction has been implicated in PD. This study investigates the mechanism of methylmercury and Paraquat induced mitochondrial dysfunction in dopamine neurons. Using in vitro assays, it was found that exposure to methylmercury (0.1-5µM) and Paraquat (300-500µM) inhibited complex I of the electron transport chain in mitochondria. This was associated with an increase in superoxide anion levels, decrease in superoxide dismutase activity, and loss of ATP. All of these factors led to the loss of mitochondrial membrane potential. Similar results were found in co-exposure treatment of 300µM of Paraquat with 0.1µM of methylmercury. These results indicate that methylmercury and Paraquat induce mitochondrial dysfunction causing the death of dopamine neurons.