Abstract
Growing nanoplastics exposure raises concern for neurotoxicity, particularly given recent evidence of plastic accumulation within human brain tissue a highly lipid enriched organ, yet effects on brain lipid metabolism remain poorly understood. Here, we employed high-resolution untargeted lipidomics to map brain lipid perturbations in Drosophila melanogaster chronically exposed to polystyrene nanoplastics (PS- NPs). PS-NPs accumulated in fly brains and induced dose-dependent remodeling of mitochondrial membrane lipids, notably cardiolipins and phosphatidylethanolamines, accompanied by increased diacylglycerols/triacylglycerols and monounsaturated fatty acids and by lipid droplet expansion. Guided by these lipidomic signatures, targeted biochemical assays demonstrated depolarized mitochondrial membrane potential, elevated mitochondrial reactive-oxygen species, inhibition of respiratory-chain complexes I and IV, and a shift in NAD(H) and NADP(H) redox couples toward a reduced state and increasing lipid peroxidation. This redox imbalance was accompanied by decreased tyrosine-hydroxylase expression, dopamine depletion, and impaired locomotor behavior, hallmarks of Parkinson's disease (PD)-like neurodegeneration. Dopaminergic neurochemistry was impaired (tyrosine hydroxylase and dopamine decreased), with concomitant reduction of GABA, and locomotor and circadian deficits emerged. Remarkably, co-treatment with the antioxidant N-acetylcysteine (NAC) restored mitochondrial membrane potential, reduced mitochondrial ROS and lipid peroxidation, normalized neutral lipid and MUFA accumulation, and rescued neurotransmitter levels and behavior. Stable-isotope tracing confirmed disrupted TCA cycle flux after NPs exposure that was rescued by NAC. Collectively, these findings reveal lipidomic remodeling as a critical link between environmental NPs exposure and PD-like pathology, highlighting mitochondrial redox-lipid interactions as early determinants and support redox-directed interventions to mitigate risk.
