Assessing hepatotoxicity induced by co-exposure to chlorpyrifos and deltamethrin in hook snout carp (Opsariichthys bidens Günther): A comprehensive analysis biochemical and molecular response analysis.

Chlorpyrifos (CLP) and deltamethrin (DTM) are among the most widely utilized organophosphate and pyrethroid insecticides globally. Their simultaneous presence in aquatic environments poses significant threats to fish health and challenges the sustainability of aquaculture practices. Despite their prevalence, the combined toxic effects of CLP and DTM on hook snout carp (Opsariichthys bidens Günther) remain insufficiently understood. In this study, O. bidens were exposed to waterborne treatments of CLP, DTM, or their combination for 30 days, and the biochemical and molecular responses of the liver tissue were systematically assessed. Acute toxicity tests revealed that the combined exposure to CLP and DTM resulted in synergistic toxicity. Significant alterations in the activities of key enzymes, including superoxide dismutase (SOD), catalase (CAT), caspase-3 (CASP-3), and caspase-9 (CASP-9), relative to the control group, demonstrated that co-exposure induced oxidative stress in O. bidens. Additionally, the elevated transcriptional levels of immune-related genes such as cxcl-c1c, il-8, and il-1 suggested a pronounced inflammatory response triggered by the pesticide mixture. Conversely, the significantly reduced expression of p53 and esr indicated that combined exposure disrupted apoptotic regulation and endocrine system function in the fish. In summary, these findings demonstrated that co-exposure to CLP and DTM induced liver damage in O. bidens by impairing antioxidant enzyme activity, disrupting apoptosis regulation, and altering the transcriptional profiles of genes involved in immune and endocrine pathways. These results provided new insights into the physiological and molecular mechanisms of pesticide-induced hepatotoxicity in fish and offered valuable information for evaluating the ecological risks associated with pesticide mixtures in aquatic environments.