Changes of embryonic development, locomotor activity, and metabolomics in zebrafish co-exposed to chlorpyrifos and...

Organophosphates (OPs) and pyrethroids (PYRs) are extensively used pesticides and often occur in the form of mixture, whereas little was known about their joint toxicities. We aim to investigate the individual and joint effects of OPs and PYRs exposure on zebrafish embryo by employing chlorpyrifos (CPF) and deltamethrin (DM) as representatives. Zebrafish embryos at 2 hours post fertilization (hpf) were exposed to CPF (4.80, 39.06, and 78.13 μg/L), DM exposure (0.06, 1.60, and 3.19 μg/L), and CPF + DM (4.80 + 0.06, 39.06 + 1.60, and 78.13 + 3.19 μg/L) until 144 hpf. Embryonic development, locomotor activity, and metabolomic changes were recorded and examined. Results displayed that individual exposure to CPF and DM significantly increased the mortality and malformation rate of zebrafish embryos, but decreased hatching rate was only found in CPF + DM co-exposure groups (p < .05). Meanwhile, individual CPF exposure had no detrimental effect on locomotor activity, high dose of individual CPF exposure decreased the swimming speed but had adaptability to the conversion from dark to light, whereas high dose of CPF + DM co-exposure exhibited not only significant decline in swimming speed but also no adaptability to the repeated stimulations, suggesting deficit in learning and memory function. In metabolomic analysis, individual CPF exposure mainly influenced the metabolism of glycerophospholipids and amino acids, individual DM exposure mainly influenced glycerophospholipids, and CPF + DM co-exposure mainly influenced glycerophospholipids and amino acids. Taken together, our findings suggested the embryonic toxicities and neurobehavioral changes caused by CPF and/or DM exposure. The disorder metabolomics of glycerophospholipids and amino acids might be involved in the underlying mechanism of those toxicities.