Bioconcentration pattern and induced apoptosis of bisphenol A in zebrafish embryos at environmentally relevant concentrations.

Abstract

Bisphenol A (BPA) is a well-known endocrine-disrupting chemical that is ubiquitously present in the environment. In the present study, 4-h post-fertilization (hpf) zebrafish embryos were exposed to various environmentally relevant concentrations of BPA (0.1, 1, 10, 100, and 1000μg/L) until 72 and 168hpf, and the accumulation pattern of BPA and its potential to induce toxicity through apoptosis were determined. Compared to BPA concentrations in larvae at 168hpf, BPA concentrations in embryos exposed until 72hpf were at relatively higher levels (p<0.05) with higher bioconcentration factor (BCF) values. The nonlinear fitting analysis indicated that the BCF values of BPA in fish embryos/larvae were significantly correlated to the log10-transformed BPA exposure concentrations in water in an inverse concentration-dependent manner. Fish accumulated more BPA as the exposure concentrations increased; however, their accumulation capacity of BPA declined and tended to be saturated in the high exposure groups of BPA. Moreover, caspase-3 activity was significantly induced upon BPA exposure at 0.1, 1, 10, and 100μg/L BPA at 72hpf, and also at 10 and 100μg/L BPA at 168hpf. Correspondingly, exposure to 10 and 100μg/L of BPA significantly increased the DNA fragmentation in the extracted DNA at 168hpf as determined by DNA ladder analysis. In addition, the expression patterns of four genes related to apoptosis including caspase-3, bax, p53, and c-jun were significantly up-regulated (p<0.05) in fish embryos/larvae upon BPA exposure at 72 and 168hpf. Our results revealed that low and environmentally relevant concentrations of BPA could be significantly accumulated in zebrafish and induced apoptosis with involvement of the regulation of caspase-3 and other apoptosis-related genes.