Synergistic effects of polystyrene microplastics and 17α-methyltestosterone on immune and oxidative stress responses in the gill and liver of Gobiocypris rarus.

This study investigated the individual and combined effects of Polystyrene microplastics (PS) and 17α-methyltestosterone (MT) on the gill and liver of Gobiocypris rarus.Exposure to PS (0.5 mg/L) and MT (50 ng/L) induced significant histopathological alterations and immunotoxicity. Tissues exhibited inflammatory infiltration, nuclear dissolution, and cytoplasmic vacuolation, with the most severe lesions observed under combined exposure. Gene expression analysis revealed significant upregulation of immune and oxidative stress-related genes, including caspase 6 (CASP6), interleukin-1 receptor type I (IL-1RI), NADPH oxidase 1 (NOX1), Toll-like receptor 2 (TLR-2), and C-C motif chemokine receptor 7 (CCR7), while antioxidant enzyme activities and malondialdehyde (MDA) levels were disrupted, indicating enhanced oxidative stress. Transcriptomic analysis of gills further revealed enrichment of ECM-receptor interaction, cell adhesion molecules, and leukocyte transendothelial migration pathways, suggesting that PS and MT may compromise immune function by interfering with extracellular matrix-related signaling, thereby exacerbating tissue damage and posing combined ecological risks in aquatic organisms.