Differences of benzo[a]anthracene- and pyrene-induced disruption of craniofacial chondrogenesis in Japanese medaka

Polycyclic aromatic hydrocarbons (PAHs) pose developmental risks, specifically craniofacial malformations in fish. This study assessed the effects of benzo [a]anthracene (BaA) and pyrene (Pyr) exposure on craniofacial chondrogenesis in Japanese medaka (Oryzias latipes) embryos, focusing on the roles of aryl hydrocarbon receptor (AhR) and cytochrome P450 (CYP). To explore the involvements with inhibiting craniofacial chondrogenesis, the CYP inhibitor (piperonyl butoxide [PBO]) and AhR antagonist (CH223191 [CH]) were used. Whole-mount Alcian blue staining of hatching larvae revealed that exposure of fish embryos to BaA partially impaired craniofacial chondrogenesis that was further exacerbated by BaA + PBO co-exposure, indicating synergistic effects of BaA under CYP inhibition. Those impairments were accompanied by the downregulation of collagen type II alpha 1a (Col2a1a) and sex-determining region Y-box9b (Sox9b). In contrast, although Pyr exposure also impaired craniofacial chondrogenesis, these effects were not associated with the downregulation of Col2a1a or Sox9b. Notably, both AhR and CYP inhibitions can attenuate Pyr-induced cartilage defects, suggesting that metabolic activation of Pyr is responsible for craniofacial effects. Overall, this study demonstrates that BaA and Pyr disrupt craniofacial chondrogenesis through different toxicological profiles.