Jiannan Ding, Shanshan Zhang, Roger Mamitiana Razanajatovo, Hua Zou, Wenbin Zhu,

Accumulation, tissue distribution, and biochemical effects of polystyrene microplastics in the freshwater fish red tilapia (Oreochromis niloticus),
Environmental Pollution, Volume 238, July 2018, Pages 1-9, ISSN 0269-7491,

Abstract:

While the presence of microplastics (MPs) in marine environments has been detected worldwide, the importance of MPs pollution in freshwater environments has also been emphasized in recent years. However, the body of knowledge regarding the biological effects of MPs on freshwater organisms is still much more limited than on marine organisms.
The aim of the present study was to evaluate the accumulation and tissue distribution of MPs in the freshwater fish red tilapia (Oreochromis niloticus), as well as the biochemical effects of MPs on O. niloticus.
During 14 days of exposure to 0.1 μm polystyrene-MPs at concentrations of 1, 10, and 100 μg L−1, the MPs concentrations in various tissues of O. niloticus generally increased over time following the  order gut > gills > liver ≈ brain.
Moreover, the acetylcholinesterase (AChE) activity in the fish brain was inhibited by MPs exposure, with a maximum
inhibition rate of 37.7%, suggesting the potential neurotoxicity of MPs to freshwater fish. The activities of cytochrome P450 (CYP) enzymes [7-ethoxyresorufin O-deethylase (EROD) and 7-benzyloxy-4-trifluoromethyl-coumarin O-dibenzyloxylase (BFCOD)] in the fish liver exhibited clear temporal variabilities, with significant
decreases followed by elevations compared to the control. The alterations of the EROD and BFCOD activities indicate the potential involvement of CYP enzymes for the metabolism of MPs. The activity of antioxidative enzyme superoxide dismutase (SOD) in the liver was significantly induced throughout the exposure period, while the
malondialdehyde (MDA) content did not vary with MPs exposure, suggesting that the antioxidative enzymatic system in O. niloticus could prevent oxidative damage.
These results highlight the ingestion and accumulation of MPs in different tissues of freshwater fish, which lead to
perturbations in fish biological systems and should be considered in environmental risk assessment.

https://drive.google.com/open?id=14VQmb-JuSwVXvpObAffYWLlo2tECdaZh
https://doi.org/10.1016/j.envpol.2018.03.001.(https://www.sciencedirect.com/science/article/pii/S0269749117342355)