Age-related tolerance to paraquat-induced parkinsonism in Drosophila melanogaster.

Paraquat (PQ) is a widely used herbicide that can cross the dopaminergic neuronal membrane, accumulate in mitochondria and damage complex I of the electron transport chain, leading to neuronal death. In Drosophila melanogaster, PQ exposure leads to the development of parkinsonism and is a classical model for studying Parkinson's Disease (PD). Muscle mitochondrial dysfunction, affecting survival and locomotion, is described in familial PD in D. melanogaster mutants. However, no study has shown the effects of PQ-induced parkinsonism in D. melanogaster regarding muscle ultrastructure and locomotor behavior at different ages. Thus, we evaluated survival, locomotion, and morphological parameters of mitochondria and myofibrils using transmission electron microscopy in 2 and 15-day-old D. melanogaster, treated with different PQ doses: control, 10, 50, 100, 150, and 200 mM. PQ100mM presented 100% lethality in 15-day-old D. melanogaster, while in 2-day-old animals PQ150mM produced 20% lethality. Bradykinesia was only observed in 15-day-old D. melanogaster treated with PQ10 mM and PQ50 mM. However, these results are unlikely to be associated with changes to morphology. Taken together, our data indicate pathophysiological differences between PQ-induced parkinsonism and familial parkinsonism in D. melanogaster (resultant from gene mutations), demonstrating for the first time a differential susceptibility to PQ in two developmental stages.