Influence of CYP1A and AhR modulation on polycyclic aromatic hydrocarbon-induced developmental defects in Japanese medaka

Polycyclic aromatic hydrocarbons (PAHs) are known to induce developmental malformations in fish embryos. However, the interaction between aryl hydrocarbon receptor (AhR) and cytochrome P450 (CYP) in PAH-induced development defects remains unclear. Therefore, we investigated the effects of the CYP1A inhibitor piperonylbutoxide (PBO) and the AhR antagonist CH223191 (CH) on the development of Japanese medaka (Oryzias Latipes) embryos exposed to different PAHs. Japanese medaka embryos were exposed to three conditions: PAH alone, PAH and PBO, and PAH and CH. Microscopic observations were performed to examine the presence of developmental defects. Although neither phenanthrene (Phe) nor fluoranthene (Flu) induced morphological malformations in larvae, benzo(a)anthracene (BaA) exposure induced craniofacial deformities in the larvae. Additionally, BaA and PBO co-exposure significantly increased the rate and severity of malformations. Pyrene (Pyr) exposure induced craniofacial defects, cardiac hypertrophy, pericardial edema, and spinal curvature, which were attenuated by exposure to either CH or PBO. Collectively, these findings suggest that structurally different PAHs exert their toxic effects via distinct mechanisms during fish development.