Estrogen receptor: A potential linker of estrogenic and dopaminergic pathways in zebrafish larvae following deltamethrin exposure

Deltamethrin (DM), a type II pyrethroid insecticide, is widely used to control agricultural pests. However, its excessive use exerts a detrimental effect on the ecological environment and human health, indicating the need to study its potential risks in detail. In the present study, zebrafish embryos were exposed to varying concentrations of DM (0.1, 1, 10, and 25 μg/L) for 96 h to assess the alterations in the transcript levels of proteins of the estrogenic and dopaminergic pathways. In addition, its effect on zebrafish locomotor activity was studied. The mRNA expression of cyp19a1b, erα, erβ2, fshr, gnrh2, gnrhr3, vtg3, dat, and dr1 significantly changed after exposing the embryos to DM. Deltamethrin at 10 and 25 μg/L significantly reduced the average swimming speed of zebrafish larvae. In addition, embryos injected with zebrafish estrogen receptor α (erα) and β (erβ) morpholinos and co-exposed to 25 μg/L DM for 96 h showed reduced expression of vtg3 mRNA compared to embryos exposed to 25 μg/L DM only. The locomotor activity of erα and erβ knockdown zebrafish following DM exposure was increased significantly when compared with that of larvae exposed to 25 μg/L DM only. Our results demonstrated that DM altered the locomotor activity of zebrafish larvae and the transcript levels of the components of estrogenic and dopaminergic pathways; erα and erβ knockdown weakened these effects.