Assessment of molecular and biochemical biomarkers in Oreochromis niloticus following acute exposure to the pesticide ZEUS®

The increasing use of pyrethroids and neonicotinoids, such as those present in the commercial formulation ZEUSⓇ (Ihara, Brazil), has raised environmental concerns attributed to enhanced risk of aquatic contamination. Fish are valuable bioindicators due to their ability to bioaccumulate and metabolically respond to contaminants. This study evaluated the acute effects of ZEUSⓇ exposure in Nile tilapia (Oreochromis niloticus) using biochemical and molecular biomarkers. Male juvenile fish (n = 10 per treatment) were exposed for 24 hr to ZEUSⓇ at 0.05, 0.1, or 0.2 mg/L. Hepatic gene transcription of genes related to xenobiotic biotransformation, antioxidant defense, inflammation, and apoptosis was assessed, together with glutathione S-transferase (Gst) and catalase (Cat) activities and lipid peroxidation levels. Lambda-cyhalothrin and dinotefuran were not detected in the muscle tissue. Biomarker responses revealed a significant 4-fold downregulation of carboxylesterase (cbe3) transcription at 0.1 mg/L, and a 40% reduction in Gst activity at 0.2 mg/L. Lipid peroxidation increased approximately 6-fold and 8-fold at 0.05 and 0.2 mg/L, respectively. No significant changes were observed in antioxidant-, inflammatory-, or apoptosis-related gene transcription. These findings indicate that acute ZEUSⓇ exposure alters detoxification processes and induces oxidative lipid damage, indicating the need for longer-term studies evaluating tissue-specific responses and bioaccumulation dynamics.