Effects of polystyrene microparticles on inflammation, antioxidant enzyme activities, and related gene expression in Nile tilapia (Oreochromis niloticus).

Due to the importance of Nile tilapia in the aquaculture sector, the present study aimed to evaluate the adverse impacts of the polystyrene microparticles (PS-MPs) on inflammation, immune, and antioxidative responses. For this reason, fish were exposed to waterborne PS-MPs at two sizes (9 μm and 0.35 μm) beside the control group for 28 days. Regardless of particle size, the final weight, weight gain, specific growth rate, and feed conversion ratio of Nile tilapia were not influenced by the PS-MPs exposure (P > 0.05). Superoxide dismutase (SOD), glutathione peroxidase (GPX), and malondialdehyde (MDA) levels were significantly increased in the group exposed to 9 μm and followed by those exposed to 0.35 μm while the lowest SOD, GPX, and MDA were in the control group. The expression of catalase (CAT) and lysozyme genes were upregulated in the group of fish exposed to 9 μm (P < 0.05). The expression of the interferon-gamma (IFN-γ) gene was upregulated in fish exposed to 9 μm and 0.35 μm when compared with the control (P < 0.05). The expression of interleukin 8 (IL8), interleukin (IL-1β), and tumor necrosis factor (TNF-α) genes was upregulated in the group of fish exposed to 9 μm (P < 0.05). The hepatic mRNA levels of cytochrome P450 (CYP450) gene were significantly upregulated in the group of fish exposed to 9 μm when compared with the control (P < 0.05) without significant differences with those exposed to 0.35 μm (P > 0.05). The obtained results refer to the adverse effects of PS-MPs on the antioxidative, inflammatory, and detoxification-related genes of Nile tilapia.