Sodium 2-mercaptobenzothiazole induces vascular developmental toxicity in zebrafish (Danio rerio) involving Kdr/PI3K/Akt signaling

Sodium 2-mercaptobenzothiazole (MBTNa) is a water-soluble benzothiazole compound widely used in industrial applications, yet its potential vascular developmental toxicity remains insufficiently understood. In this study, zebrafish embryos were used to evaluate the cardiovascular and vascular developmental effects of MBTNa and to explore the possible molecular mechanisms involved. Embryos were exposed to 0.001–1 μM MBTNa from 4 to 72 hpf, and cardiovascular morphology, vascular development, apoptosis-related signals, network toxicology prediction, molecular docking, Western blot analysis, and PTK787-based rescue experiments were performed. MBTNa exposure induced selective cardiovascular and vascular defects, including pericardial edema, bradycardia, impaired intersegmental vessel development, common cardinal vein dilation, and ectopic subintestinal vessel sprouting. Network toxicology and molecular docking identified Kdr/PI3K/Akt-associated signaling as a potential pathway involved in MBTNa-induced vascular abnormalities. RT-qPCR analysis showed altered expression of PI3K/Akt/GSK3β-related and apoptosis-related genes, and Western blot analysis further showed increased relative levels of p-AKT and p-GSK3β after MBTNa exposure. In addition, PTK787 co-treatment partially attenuated MBTNa-induced vascular abnormalities and reversed selected transcriptional alterations. These findings suggest that Kdr/PI3K/Akt-associated signaling is involved in MBTNa-induced vascular developmental toxicity and highlight the need to include vascular endpoints in the risk assessment of benzothiazole-related contaminants.