Polyethylene exposure in rainbow trout; suppresses growth and may act as a promoting agent in tissue-based oxidative response, DNA damage and apoptosis

The toxic effects of microplastic (MP) pollution, which is a growing threat to the aquatic ecosystem, are constantly recorded by scientific reports at the organism and cellular levels. Despite this, the action mechanism of MP toxicity remains ambiguous. This research was designed to investigate the interactions with multiple biomarkers in the tissues of Oncorhynchus mykiss exposed to polyethylene microplastics (MPs-PE) under controlled conditions. In this context, fish were fed with MP-PE added feeding at different levels [MP-PE-I (10%) and MP-PE-II (20%)]. It was aimed to elucidate the MP abundance in gills, gastrointestinal system, on growth and hematological indexes in fish, as well as possible oxidative, DNA damage in target tissues (brain, gill, liver and muscle) and a number of biochemical events underlying apoptosis. MPs-PE tested at different concentrations led to changes in growth parameters and hematologic indices in fish. In all tissues targeted for the follow-up of oxidative stress, inhibitions in GSH levels and antioxidant enzyme activities were determined, while MDA, ROS, DNA damage and apoptosis significantly changed the expression profile upwards. MPs-PE significantly inhibited neurotransmission in rainbow trout. In conclusion, the outcomes of this study revealed that MPs-PE induced dose-dependent ROS-mediated apoptotic responses/ DNA damage in rainbow trout. The data are also a first record for rainbow trout and will help unravel different mechanisms with the potential to model for other MPs-PE-based toxicity studies.