Abstract
This study investigated the impact of deltamethrin (DM) toxicity on brown trout (Salmo trutta fario), examining its effects on the immune system, including the white blood cell (WBC), lymphocyte (Lym), total immunoglobulin (T. Ig), and lysozyme levels, as well as its neurotoxic consequences on the brain tissue. The neurotoxic effects encompassed oxidative stress, the activity of the antioxidant enzymes, such as the superoxide dismutase (SOD) and catalase (CAT), acetylcholinesterase (AChE) activity, and DNA damage using 8-hydroxy-2-deoxyguanosine (8-OHdG). The DM exposure led to elevated levels of malondialdehyde (MDA), and 8-OHdG, while concurrently causing a reduction in the AChE activity, protein and lipid content, WBC count, Lym, lysozyme activity, T. Ig levels, as well as the SOD and CAT levels in the brain tissues of groups 2 and 3 when compared to those in group 1. In summary, the findings of this study strongly indicate that DM induces DNA damage, immunotoxicity, and neurotoxicity in the brain tissue of brown trout, primarily due to the excessive production of reactive oxygen species (ROS). Moreover, the observed dose-dependent responses of DM to the environmental concentrations on all the investigated parameters suggest its potential utility in aquaculture risk assessment.