Toxic effects of four cardiovascular drugs on the development and epigenetics of zebrafish (Danio rerio)

Due to the prevalence of cardiovascular diseases, therapeutic drugs such as atenolol (ATE), metoprolol (MET), atorvastatin (ATO), and bezafibrate (BZB) have been widely used and thus frequently detected in surface water at ng·L−1–μg·L−1 level. In this study, the developmental toxicity of these drugs (0.5 μg·L−1–500 μg·L−1) to zebrafish, an aquatic model organism, was investigated; and the epigenetic toxicity of BZB was also explored. For all four drugs, the results showed that the drugs exposure could cause sublethal toxic effects on zebrafish larvae, such as decreases in hatching rate, body length, and heart rate. ATO also induced the swelling of the eyes of larvae by 5 %–15 %. Yolk sac edema, pericardial edema, bent spine, and tail malformation were observed in larvae exposed to the drugs, and yolk sac edema was the most common malformation. In addition, the spontaneous movement and free-swimming activity could be inhibited by the drugs. Combined with RNA-seq results, the adverse development of larvae in exposure groups may be caused by the disruption of lipid and carbohydrate metabolism, and the development and function of eye and nervous system. After a 30-day uptake period, the accumulation of BZB and the decrease of global DNA methylation level were observed in the liver, kidneys, gut, gills, and brain of adult zebrafish (4-month-old) exposed to 0.5 μg·L−1 to 500 μg·L−1 BZB. The liver was the main organ for BZB accumulation and the occurrence of DNA hypomethylation. In the liver, overexpression (1.5–7.6 times) of genes related to lipid metabolism (PPARα), DNA methylation (Dnmt1), and apoptosis (p53) was also observed. The results of the current study suggest that long-term exposure to low-concentrations of cardiovascular drugs may pose significant threats to aquatic ecosystems.