Hepatic Biotransformation in Climbing Perch <scp><i>Anabas testudineus</i></scp> Exposed to Polystyrene Microplastics at Environmentally Relevant Concentrations

Polystyrene microplastics (PS-MPs) are an emerging environmental pollutant posing significant risks to aquatic organisms. This study investigates the hepatic biotransformation responses and histopathological changes in the liver tissues of Anabas testudineus exposed to environmentally relevant concentrations of PS-MPs (13.6 and 23.6 mg L^-1) over durations of 1, 7, 15, 30, and 60 days, followed by a 60-day depuration phase. The study assessed the activities of key phase I and phase II detoxification enzymes in cytosolic and microsomal fractions, including ethoxyresorufin-O-deethylase (EROD), pentoxyresorufin O-dealkylase (PROD), flavin-containing monooxygenase (FMO), NADPH-cytochrome P450 reductase (CPR), sulfotransferase (SULT), UDP-glucuronosyltransferase (UGT), and glutathione S-transferase (GST), alongside mRNA expression analysis of Cyp1a1 and Ugt. Results indicated significant induction of phase I enzymes, particularly EROD, and a subsequent alterations in phase II enzyme activities, reflecting an adaptive detoxification response. Histopathological examination revealed persistent lesions, necrosis, vacuolization, and melanomacrophage aggregation, even after the depuration period, indicating liver tissue damage. The findings highlight the adverse effects of A. testudineus to MP exposure and suggest potential risks to other aquatic organisms, emphasizing the importance of mitigating plastic pollution in aquatic environments.