DINCH Exposure Triggers Inflammatory, Oxidative, and Apoptotic Pathways in the Liver of Long-Evans Lactating Rats and Their Offspring

Abstract

1,2-cyclohexane dicarboxylic acid diisononyl ester (DINCH) is a non-phthalate plasticizer used as a replacement of di(2-ethylhexyl) phthalate (DEHP) in daily usage items. It is not known whether continuous exposure to low doses of DINCH can lead to hepatic alterations, the liver being the organ responsible for its metabolism. The aim of this study was to evaluate the activation of inflammatory and apoptotic pathways in the liver of lactating dams after DINCH exposure, and whether these effects may be observed on postnatal day 6 (PND6) offspring. Two doses of DINCH were tested by oral administration to the following three groups of Long-Evans rats: control, DINCH-lower dose (LDINCH, 30 mg/kg b.w./day), and DINCH-high dose (HDINCH, 300 mg/kg b.w./day). Inflammatory mediators (IL-1β, TNF-α, NF-κB), mitochondrial transcriptional factors (PPARγ and PGC-1α), oxidative stress markers (SOD, CAT, GSSG/GSH), and components of the mitochondrial apoptotic pathway (PUMA, BAX, BAD, Bcl-2, Bcl-xL, Cytochrome c, APAF-1, Caspase-3, AIF) were assessed by the gene and protein expression in the liver of lactating dams and offspring. Exposure to LDINCH promoted the release of pro-inflammatory cytokines such as IL-1β and TNF-α and raised oxidative stress levels (GSSG/GSH), as well as increased Caspase-3 levels and reduced anti-apoptotic proteins (Bcl-2 and Bcl-xL), both in lactating dams and PND6 offspring. Thus, constant exposure to lower doses of DINCH can disrupt inflammatory and oxidant/antioxidant homeostasis, leading to hepatic tissue damage in lactating dams and having a perinatal effect in PND6 offspring.