Deltamethrin affects the expression of voltage-gated calcium channel α1 subunits and the locomotion, egg-laying, foraging behavior of Caenorhabditis elegans

Deltamethrin belongs to the class of synthetic pyrethroids, which are being widely used as insecticides in agricultural practices. Voltage-gated sodium channels (VGSCs) are the primary targets of these chemicals for toxicity to insects. Caenorhabditis elegans (C. elegans) does not have VGSCs but is susceptible to deltamethrin. Recent findings have suggested that pyrethroids can affect voltage-gated calcium channels (VGCCs). However, it remains elusive whether deltamethrin induces toxicity to C. elegans via modulating the activity of VGCCs. To identify the potential target of deltamethrin, we exposed C. elegans to different concentrations of deltamethrin and Ca2+ channel blockers for different times, characterized the behavioral toxicity of deltamethrin on C. elegans, and determined the expression of egl-19, unc-2, and cca-1, which encode the alpha 1-subunit of the L-, R/N/P/Q-, and T-type VGCC, respectively. We found that deltamethrin inhibited the locomotion, egg-laying and foraging ability of C. elegans in a concentration dependent manner. We also showed that body length of worms on agar plates containing 200 mg L-1 deltamethrin for 12 h was not significantly different from controls, whereas the cholinesterase inhibitor carbofuran caused hypercontraction which is a characteristic of organophosphates and carbamates, suggesting that deltamethrin's mode of action is distinct from those nematicides. In addition, unc-2 was significantly up-regulated following 0.05 mg L(-1)deltamethrin exposure for 24 h; while egl-19 and cca-1 were significantly up-regulated following 5 and 50 mg L-1 deltamethrin exposure for 24 h. Further tests of worms' sensitivity and expression of three alpha 1-subunits of VGCC to Ca2+ channel blockers indicate that deltamethrin may induce toxic behavior C. elegans via modulation of the expression of the alpha 1-subunits of VGCC. This study provides insights into the linkage between deltamethrin-induced toxic behavior and the regulation of alpha 1-subunits of VGCC in C. elegans. (C) 2017 Elsevier Inc. All rights reserved.