Effects of Sub-Chronic Exposure to Polystyrene Nanoplastics on Lipid and Antioxidant Metabolism in Sparus aurata.

Nanoplastics (NPs) can cross cellular membranes and affect cellular performance. This study aims to determine the effects of polystyrene NPs (PS-NPs, 44 nm) on gilthead seabream (Sparus aurata) exposed for 14 days to 100 μg/L PS-NPs. The results show that biometric indicators (weight, length, Fulton's condition factor, and hepatosomatic index) were not affected after the experimental exposures. No significant effects were observed on white blood cell count, red blood cell count, mean corpuscular hemoglobin, or platelets compared to the control group. However, there was a significant decrease in hemoglobin concentration, hematocrit values, and mean corpuscular cell volume in fish exposed to PS-NPs. There were no significant effects on plasmatic cholesterol, triglyceride, alkaline phosphatase, or aspartate aminotransferase levels. The histological anatomy of both the gills and the intestine revealed no obvious signs of cellular damage, excessive mucous, or inflammation in the PS-NP group. The expression of transcripts related to lipid metabolism (pparα, pparβ), growth and development (igf1), detoxification (bche), and oxidative stress (sod, gpx1) were significantly downregulated in animals exposed to PS-NPs, indicating a slight impairment in lipid homeostasis and antioxidant response.