In vivo mitochondrial oxidative state in animals treated with PQ and the antioxidant EchA

Classical models of dopaminergic neurodegeneration often utilize paraquat (PQ), which exerts toxicity through oxidative stress and mitochondrial dysfunction that play a key role in progressive dopaminergic neuron death. We evaluated the effect of PQ on in vivo mitochondrial oxidation using the genetic reporter MitoTimer, a protein that photoconverts from green to red upon oxidation. To determine whether the oxidative impact is cell-type specific, MitoTimer was selectively expressed in dopaminergic neurons (TH-GAL4), pan-neuronal (elav-GAL4), or in glia (Repo-GAL4). We assessed the potential neuroprotective effect of Echinochrome A (EchA), a naturally occurring spinochrome present in the roe of the Patagonian sea urchin Arbacia dufresnii. EchA has protective effects in vitro; however, its action on the in vivo mitochondrial redox state in the nervous system is unclear. Locomotor performance and cognitive response were evaluated by placing individual flies in a novel context and quantifying distance traveled and habituation. EchA was administered orally as part of a roe-derived formulation with a known and standardized EchA concentration, currently used to produce an approved and commercialized dietary supplement for human consumption. Brain tissues were examined using fluorescence microscopy to quantify the red/green fluorescence ratio as a direct readout of mitochondrial oxidation. This approach will provide insight into the potential mitoprotective effects of EchA.