Microplastics (MPs), defined as plastic particles smaller than 5 mm in size, are considered a global environmental and human health problem, due to their ubiquity and persistence in the aquatic ecosystems. Considering the problematic of MPs, the present study aimed to assess the toxicological effects of MPs and copper (Cu) in zebrafish brain. Polyethylene (PE) and polystyrene (PS) MPs were selected because of their extensive commercial use and high accumulation in aquatic environments. For this purpose, zebrafish were exposed for 21 days to Cu (25μg/L), PE and PS (1mg/L) and their mixtures (PE-Cu and PS-Cu). After 21 days, fish behavior was assessed, followed by their euthanasia with an overdose of buffered tricaine methanesulfonate, and excision of the whole brain for the biomarker’s evaluation. The biochemical parameters related to oxidative stress Reactive oxygen species, lipid peroxidation; antioxidant activity superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione reductase (GR), reduced (GSH) and oxidized states (GSSG) of glutathione levels; and detoxification (glutathione-S-transferase) were assessed. Data showed that the exploratory/locomotor, anxiety-related, and social behaviors were not significantly affected by Cu, PE, PS, and the respective mixtures. Considering the biochemical parameters, the GPx activity was significantly decreased in PE-Cu, in relation to the control group. Considering our findings, the long-term behavioral and biochemical alterations in response to heavy metals and MPs, and its implications in fish population fitness still need to be clarified.

This work is supported by National Funds by FCT - Portuguese Foundation for Science and Technology, under the project UIDB/04033/2020.