Calcium entry induces mitochondrial oxidant stress in vagal neurons at risk in Parkinson’s disease

Mitochondrial oxidant stress is widely viewed as critical to pathogenesis in Parkinson’s disease. But the origins of this stress are poorly defined. One possibility is that it arises from the metabolic demands associated with regenerative activity. To test this hypothesis, neurons in the dorsal motor nucleus of the vagus (DMV), a population cholinergic neurons that shows signs of pathology in the early stages of Parkinson’s disease, were characterized in mouse brain slices. DMV neurons were slow, autonomous pacemakers with broad spikes, leading to calcium entry that was weakly buffered. Using a novel transgenic mouse expressing a redox-sensitive optical probe targeted to the mitochondrial matrix, it was found that calcium entry during pacemaking created a basal mitochondrial oxidant stress. Knocking out DJ-1 – a gene associated with early-onset Parkinson’s disease – exacerbated this stress. These results point to a common mechanism underlying mitochondrial oxidant stress in Parkinson’s disease and a therapeutic strategy to ameliorate it.