Toxicity and related molecular mechanisms of Sb(V) in the embryos and larvae of zebrafish (Danio rerio)

Owing to the extensive application of antimony across various industries, antimony pollution poses significant threats to human health and ecosystems. However, its aquatic ecotoxicological and mechanisms remain poorly understood. This study aimed to decipher the toxic effects and molecular mechanisms of antimony(V) [Sb(V)] in zebrafish embryos/larvae. The results demonstrated that Sb(V) accumulated in larvae in a concentration-dependent manner. Although no significant lethal or teratogenic effects were observed, normal growth and development were perturbed. Exposure to 100 mg/L Sb(V) increased reactive oxygen species (ROS) levels in larvae while increasing catalase (CAT) and superoxide dismutase (SOD) activities and reducing lipid peroxidation levels, with no significant effect on apoptosis. Correlation analysis of toxic endpoints revealed complex network associations among the antioxidant system (CAT/SOD), oxidative stress markers (ROS/MDA), and developmental parameters (body length, heart rate, and nonteratogenic rate). The antioxidant functions of CAT/SOD may indirectly influence growth and teratogenic phenotypes by modulating the extent of oxidative damage, whereas the glutathione redox balance (GSH/GSSG ratio) has bidirectional regulatory potential for apoptosis. Oxidative stress indicators (CAT, SOD, ROS, and MDA), apoptosis markers (whole-body and abdominal apoptosis), and developmental metrics were identified as highly sensitive toxic endpoints. Transcriptomic analysis revealed that Sb(V) upregulated immune-related signaling pathways and significantly affected the expression of genes involved in immune defense responses in zebrafish larvae, suggesting potential interference with immune system functions. This study provides critical data for enhancing the understanding of Sb(V) aquatic ecotoxicology and offers new perspectives for assessing the potential ecological health risks of Sb(V).