Effect of polyethylene microplastics on oxidative stress and histopathology damages in Litopenaeus vannamei

There has been a significant increase in the microplastic (MP) polluting the ocean in recent time which is regarded as toxic for living organisms. In this study, Fluorescent red polyethylene microspheres (FRPE) were administered intramuscularly to Litopenaeus vannamei juveniles at the concentration of 0.1, 0.2, 0.5 and 1.0 μg (g shrimp)^-1, and the survival rate was recorded. Analysis of the hepatopancreas for antioxidant enzyme activity and gene expression were done after seven days. Further tissue morphology and accumulation of FRPE was analysed. The results showed that FRPE at 0.5 and 1.0 μg (g shrimp)^-1 reduce the survival rate of L. vannamei. FRPE at 0.5 and 1.0 μg (g shrimp)^-1 reduced superoxide dismutase (SOD) activity; FRPE at different concentrations reduced catalase (CAT) activity; FRPE at 0.2, 0.5 and 1.0 μg (g shrimp)^-1 increased the lipid peroxide thiobarbituric acid (TBARS) content. FRPE at 0.1, 0.2, and 0.5 μg (g shrimp)^-1 significantly affect the performance of SOD and CAT genes; FRPE at 0.2 and 0.5 μg (g shrimp)^-1 significantly improves GPx gene performance; FRPE at 1.0 μg (g shrimp)^-1 significantly reduced the expression of GPx genes. Analysis of tissue morphology shows that FRPE cause muscle, midgut gland, and hepatopancreas, and gill damage at different concentrations. In the results of accumulation of microplastic, FRPE accumulated in gill tissue at 0.2 and 0.5 μg (g shrimp)^-1; FRPE accumulated in gill, muscle and hepatopancreas tissue at 1.0 μg (g shrimp)^-1. Based on the above results, FRPE at 0.5 and 1.0 μg (g shrimp)^-1 can regulate the antioxidant enzymes of L. vannamei, increase lipid peroxide content, cause tissue damage by accumulating in the tissues. The rate of survival decreased in L. vannamei, and the impact of FRPE at 1.0 μg (g shrimp)^-1 was significant.