Abstract

Small plastic particles are considered emerging pollutants, and this has motivated research to establish their ecological and environmental consequences. Currently, the study of the effects of nanoplastics (NPs) in aquatic organisms is still scarce, especially in organisms of higher trophic levels, such as !sh. The Mediterranean Sea is considered a region of high accumulation of plastics, due to the high plastic load from coastal areas and the limited outflow to the Atlantic Ocean. Gilthead sea bream (Sparus aurata) is a common !sh species in the Mediterranean Sea and one of the most cultivated species for human consumption in this area. Due to this, it is highly relevant to investigate the effect that these emerging contaminants may have on this !sh species. The objective of this study was to evaluate the effect of short-term exposure to polymethylmethacrylate (PMMA) NPs on lipid metabolism in S. aurata, using molecular and biochemical endpoints, considering that lipids are important source of energy for !sh. Parameters related with the antioxidant response were also studied as a marker of general toxicity. The mRNA levels of the following transcripts related with the lipid metabolism or antioxidant response were evaluated in the liver of !sh exposed to NPs: peroxisome proliferator-activated receptors (ppara, pparb and pparc), retinoid X receptor (rxr), apolipoproteins (apo) and lipoprotein lipase (lpl), glutathione peroxidase 1 (gpx1), glutathione reductase (gr), superoxide dismutase (sod2), glutathione-S-transferase 3 (gst3) and catalase (cat). Biochemical biomarkers, such as cholesterol, triglycerides, glucose, total oxidative status (TOS) and esterase activity (EA) were measured in fish plasma and liver.