RETRACTED: Environmental Impact of Pharmaceutical Pollutants: Synergistic Toxicity of Ivermectin and Cypermethrin

Abstract

Veterinary antiparasitic pharmaceuticals as well as pesticides have been detected in surface waters, and they may cause several toxic effects in this environmental compartment. In the present study, we evaluated the toxicity after exposure of different concentration of ivermectin (IVM; 50, 100, and 200 μg L^-1) and cypermethrin (CYP; 5, 10, and 25 μg L^-1) and the combination of these two compounds at non-toxic concentration (IVM 100 + CYP 5 μg L^-1) in zebrafish embryos. Combination of IVM at 100 μg L^-1 with CYP at 5 μg L^-1 exposure induced hatching delay and malformations at 96 hpf in zebrafish larvae as well as significant induction of cell death in zebrafish larvae. At the same time, the two single concentrations of IVM and CYP did not show a toxic effect on zebrafish development. In conclusion, our study suggests that IVM and CYP show a synergistic effect at common, ineffective concentrations, promoting malformation and cell death in fish development.

Keywords: Danio rerio; antiparasitic; contaminants.

Figure 1

Chemical structures of ivermectin and cypermethrin.

Figure 2

Optical micrographs control after incubation with IVM and acetone 0.1% for 96 hpf.

Figure 3

Optical micrographs showing physical malformation in comparison with control after incubation with CYP and acetone 0.1% for 96 hpf.

Figure 4

The survival hatching and heart rate of embryos exposed to different concentrations of IVM (A–C) and CYP (D–F), respectively, were determined at the designate time. Values = means ± SD of three independent experiment data: *** at p < 0.001 against CTRL. Photographs are representative of the experimental group’s situation (n = 20).

Figure 5

Effects of single and co-exposure of IVM and CYP on morphological changes in zebrafish larvae at 96 hpf (A). Hatching rate (B) and morphological scoring (C). Values = means ± SD of three independent experimental datapoints: *** at p < 0.001 against IVM+CYP.

Figure 6

TUNEL assays indicated an abnormal apoptotic pattern. TUNEL-positive apoptotic cells (white arrow) in zebrafish embryos treated with IVM and CYP at 96 hpf. CTRL (A), acetone (B), IVM (C), CYP (D), and IVM + CYP (E).

Figure 7

Effects of IVM and CYP on protein levels of iNOS and apoptotic pathway (bax and bcl-2) on larval zebrafish. Western blot analysis (A). Each figure corresponds to a representative replicate from three experiments for iNOS, Bax, and bcl-2 (A–D). Values = means ± SD of three independent experimental datapoints: *** at p < 0.001 against IVM+CYP.