Exposure to cadmium alters metabolic pathways in the hepatic proteome of a neotropical catfish

Cadmium (Cd) is a non-essential metal known for its potential to biomagnify and bioaccumulate in organisms, raising concerns about the toxic effects on aquatic environments and human beings. However, Cd toxicity effects seem variable across species, and its mechanisms of toxicity remain poorly understood, particularly in native Neotropical fish species. This study aimed to evaluate proteomic alterations in the livers of male Rhamdia quelen exposed to environmentally relevant concentrations of Cd. For this, fish were maintained in 60 L tanks under laboratory conditions and exposed to different CdCl₂ concentrations: 0.1, 1, 10, and 100 μg/L for 15 days. Fish were anesthetized and after euthania their livers were samples for subsequent proteomic analysis using the UniProtKB database, which is most suitable for this species. From the initial 1366-expressed protein, 117 were statistically significant, with most belonging to the group of animals exposed to 10 μg/L. These differentially expressed proteins were mainly related to metabolic pathways concerning energy production, carbohydrate metabolism, protein synthesis and degradation, immune responses, and detoxification. Nonetheless, the concentration of 10 μg/L exhibited the most pronounced changes and holds major biological relevance, given that this concentration is commonly detected in freshwater ecosystems and can affect several metabolic processes. This study provides crucial information about the mechanism of Cd toxicity in the R. quelen catfish liver, highlighting protein targets affected after exposure. Furthermore, the study supports a protocol standardization for proteomic analysis in this native species with ecotoxicological relevance.