ANALYSIS OF THE BEHAVIORAL EFFECTS OF FREE AND NANOEMULSIFIED QUERCETIN IN AN EXPERIMENTAL MODEL OF PARKINSON'S DISEASE

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INTRODUCTION: Parkinson’s disease (PD) is a neurodegenerative disordercharacterized by the degeneration of dopaminergic neurons. Animal models usingneurotoxins, such as 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), havebeen employed to replicate this condition. Natural compounds, such as quercetin(QU), an antioxidant flavonoid, have been investigated as potential therapeuticalternatives for PD. However, QU exhibits low solubility and bioavailability. Toovercome these limitations, its incorporation into lipid-based nanostructures, such asquercetin-loaded nanoemulsions (NEQU), has been proposed to enhance solubility,stability, and absorption. OBJECTIVES: This study aimed to evaluate the effects inlocomotion of the pretreatment with NEQU and free QU on MPTP-inducedParkinson's disease model in zebrafish larvae. MATERIALS AND METHODS:Embryos were collected one hour after fertilization, and viable specimens wereselected. At 4 days post-fertilization (dpf), larvae were pretreated with QU and NEQUat concentrations of 1 µM and 2.5 µM, and with their respective dilution vehicles. At 5dpf, MPTP was administered, and at 7 dpf, the larvae underwent motor behavioranalysis. An adapted setup was used for the analyses, with a camera connected to adata acquisition system (DanioVision, Noldus) to record movement. Video analysiswas performed using EthoVision XT software (Noldus).Experimental protocols wereapproved by CEUA/FURG, license P015/2022. RESULTS AND CONCLUSION: Theresults showed that exposure to MPTP significantly reduced larval mobility.Treatment with QU did not protect from the neurotoxin-induced effects. The groupstreated with DMSO exhibited mobility similar to the control group, indicating that thesolvent did not interfere with the outcomes. Notably, the groups treated with NEQUdemonstrated a considerable improvement in locomotion compared to the MPTPgroup. These findings suggest that MPTP effectively simulates the motor symptomsof Parkinson’s disease in zebrafish and that NEQU exhibits neuroprotectivepotential, representing a promising alternative for future studies.