Cadmium potentiates toxicity of cypermethrin in zebrafish

Abstract

Co-occurrence of pesticides such as synthetic pyrethroids and metals in aquatic ecosystems raises concerns over their combined ecological effects. Cypermethrin, 1 of the top 5 synthetic pyrethroids in use, has been extensively detected in surface water. Cadmium (Cd) has been recognized as 1 of the most toxic metals and is a common contaminant in the aquatic system. However, little information is available regarding their joint toxicity. In the present study, combined toxicity of cypermethrin and Cd and the underlying mechanisms were investigated. Zebrafish embryos and adults were exposed to the individual contaminant or binary mixtures. Co-exposure to cypermethrin and Cd produced synergistic effects on the occurrence of crooked body, pericardial edema, and noninflation of swim bladder. The addition of Cd significantly potentiated cypermethrin-induced spasms and caused more oxidative stress in zebrafish larvae. Cypermethrin-mediated induction of transcription levels and catalytic activities of cytochrome P450 (CYP) enzyme were significantly down-regulated by Cd in both zebrafish larvae and adults. Chemical analytical data showed that in vitro elimination of cypermethrin by CYP1A1 was inhibited by Cd. The addition of Cd caused an elevation of in vivo cypermethrin residue levels in the mixture-exposed adult zebrafish. These results suggest that the enhanced toxicity of cypermethrin in the presence of Cd results from the inhibitory effects of Cd on CYP-mediated biotransformation of this pesticide. The authors' findings provide a deeper understanding of the mechanistic basis accounting for the joint toxicity of cypermethrin and Cd.

Effects of metals on enantioselective toxicity and biotransformation of cis‐bifenthrin in zebrafish

“…In agreement with this observation, our recent study showed that Cd inhibited CYP-catalyzed biodegradation of CP in zebrafish [27]. In agreement with this observation, our recent study showed that Cd inhibited CYP-catalyzed biodegradation of CP in zebrafish [27].…”

“…The animals were maintained in the laboratory at optimal conditions for at least 1 wk before exposure experiments, according to the well-established protocols previously described [27]. The animals were maintained in the laboratory at optimal conditions for at least 1 wk before exposure experiments, according to the well-established protocols previously described [27].…”

“…The concentration of RNA was determined at 260 nm using an Infinite M200 plate reader (Tecan USA) [38]. The realtime PCR reactions were set up with SYBR Green PCR mix (Toyobo) on an Mx3000P real-time PCR system (Agilent), as described previously [27,28,40,41]. Real-time polymerase chain reaction (PCR) was employed to identify the relative expression levels of cytochrome P450 enzymes.…”

“…Residual levels of cis-BF enantiomers in the whole-body fish tissues were established using methods described previously [27]. Briefly, the fish were thawed on ice, cut into tiny pieces, and homogenized with a Bio-Gen PRO200 homogenizer (PRO Scientific).…”

“…Co-occurrence of pyrethroids and metals has been detected in aquatic ecosystems, especially the areas surrounding intensive agricultural and industrial sites [19][20][21][22][23][24]. Indeed, coexistence of pyrethroids and metals induced joint toxicity to aquatic organisms [25][26][27]. A previous study showed that the mixtures of copper (Cu) and deltamethrin caused enhanced toxic effects on D. magna [25].…”