Nrf2 axis and endoplasmic reticulum stress mediated autophagy activation is involved in molybdenum and cadmium co-induced hepatotoxicity in ducks

Excessive molybdenum (Mo) and cadmium (Cd) have toxic effects on animals. However, hepatotoxicity co-induced by Mo and Cd in ducks is still unclear. To evaluate the effects of Cd and Mo co-exposure on autophagy by nuclear factor erythroid 2-related factor 2 (Nrf2)-mediated antioxidant defense and endoplasmic reticulum stress (ERS) in duck livers, 40 healthy 7-day-old ducks were randomly assigned to 4 groups and fed diets containing different doses of Mo and/or Cd for 16 weeks, respectively. The results verified that Mo and/or Cd induced oxidative stress via decreasing glutathione peroxidase (GSH-Px), catalase (CAT), and total-superoxide dismutase (T-SOD) activities and increasing hydrogen peroxide (H 2 O 2 ) and malondialdehyde (MDA) concentrations; inhibited Nrf2 axis by downregulating the pathway-related genes and proteins expression levels , and activated ERS through upregulating the protein kinase RNA-like endoplasmic reticulum kinase (PERK)/eukaryotic initiation factor 2a (eIF2a), inositol-requiring enzyme 1 (IRE1) and activating transcription factor 6 (ATF6) pathway-related genes and proteins expression levels, which triggered autophagy via increasing autophagosomes , light chain 3 (LC3) puncta, LC3A, LC3B, autophagy-related gene 5 (Atg5), Bcl-2-interacting protein (Beclin-1) mRNA levels and Beclin-1, microtubule-associated protein light chain 3 II/I (LC3II/LC3I) protein levels, decreasing Dynein, p62 , mammalian target of rapamycin (mTOR) mRNA levels and p62 protein level. Additionally, the changes in Mo and Cd group were the most obvious. Briefly, our study reveals that autophagy induced by Mo and/or Cd may be associated with the activation of crosstalk between Nrf2-mediated antioxidant defense response and ERS in duck livers. Mo and Cd may aggravate toxic damage to the liver.