Environmentally relevant concentrations of 6-PPDQ disrupt vitamin D3 adsorption and receptor function in Caenorhabditis elegans

Abstract

As a derivative of the antioxidant of N-(1,3-dimethylbutyl)-N′-phenyl-p-phenylenediamine (6-PPD), 6-PPD quinone (6-PPDQ) is frequently found in environments and the bodies of organisms. Vitamin D3 is an important vitamin that needs to be absorbed from the intestine. In Caenorhabditis elegans, vitamin D3 content was reduced by 0.1–10 μg L⁻¹ of 6-PPDQ. Meanwhile, 6-PPDQ (0.1–10 μg L⁻¹) decreased the expressions of lrp-2, scl-12, scl-13, and ifo-1, and their RNAi decreased the vitamin D3 content in 6-PPDQ-exposed animals. 6-PPDQ (0.1–10 μg L⁻¹) further decreased the nhr-8 expression and increased the daf-12 expression, and the expression of these 2 vitamin D3 receptor genes could be changed by RNAi of lrp-2, scl-12, scl-13, and ifo-1 after 6-PPDQ exposure. The 6-PPDQ toxicity was increased by the RNAi of lrp-2, scl-12, scl-13, ifo-1, and nhr-8 and inhibited by the RNAi of daf-12. Moreover, after 6-PPDQ exposure, SOD-3 and HSP-6 expressions were decreased by nhr-8 RNAi and increased by daf-12 RNAi. Therefore, 6-PPDQ potentially caused damage to the adsorption of vitamin D3 and the function of its receptors, and these effects were related to the toxicity induction of 6-PPDQ.