Effects of bisphenol A alternatives (BPS and BPAF) on zebrafish (Danio rerio) spermatogenesis ex vivo: meiosis damage and transcriptional deregulation of genes related to spermatogenic processes and epigenetic regulation

Environmental contaminants BPS and BPAF, emerging substitutes for BPA, are raising concerns as endocrine disruptors. This study assessed their effects on zebrafish spermatogenesis using ex vivo testicular explants exposed to 0.5, 5, or 50 µg/L of each compound for 7 days. Both chemicals impaired spermatogenesis by reducing meiotic (Spc<sub>p</sub>) and post-meiotic (Spt) cyst formation, with BPS showing stronger effects. Additionally, they altered the expression of marker genes related to spermatogenesis, steroidogenesis, and epigenetic regulation. Notably, cyp19a1a was upregulated by both, indicating estrogenic activity; however, BPS did not affect estrogen receptor expression, suggesting an indirect antiandrogenic mechanism, while BPAF modulated esr1 and esr2a, indicating direct estrogenic effects. Our findings provide evidence that the dose-response for both compounds was non-monotonic. These results imply that BPS and BPAF can disrupt reproductive and molecular processes, challenging their safety as BPA substitutes and highlighting the need for further investigation and more stringent environmental regulations.