Abstract

This study investigated the effects of dietary nanoselenium (nano-Se) supplementation protecting from renal oxidative damages induced by mercury (Hg) exposure in laying hens. Furthermore, endoplasmic reticulum (ER) stress pathway was explored to reveal the protective mechanism of nano-Se. A total of 576 40-week-old Hyline-White laying hens were randomly allocated to 4 groups with 6 pens per group and 24 hens per pen. The experimental groups were as follows: control (basal diet), control + 27.0 mg/kg Hg, control + 5.0 mg/kg nano-Se, and Hg27.0 + 5.0 mg/kg nano-Se. The results revealed that dietary Hg exposure significantly reduced laying performance ( P  < 0.05) and egg quality ( P  < 0.05), whereas nano-Se supplementation partially reversed the reductions. Besides, dietary Hg exposure could induce histopathology damages and apoptosis in kidney, whereas nano-Se addition could alleviate these toxicities effectively. After Hg exposure, the activities and gene expressions of superoxidative dismutase (SOD) ( P  < 0.05), catalase (CAT) ( P  < 0.01), glutathione reductase (GR) ( P  < 0.05) and glutathione peroxidase (GSH-Px) ( P  < 0.05), and glutathione (GSH) content ( P  < 0.05) were significantly decreased, while the malondialdehyde (MDA) level was significantly increased ( P  < 0.05) in kidney. However, nano-Se supplementation partially reversed the levels and gene expressions of these antioxidant biomarkers in kidney. Furthermore, dietary Hg exposure significantly increased the gene expressions of PERK ( P  < 0.05), ATF4 ( P  < 0.05), CHOP ( P  < 0.05), IRE1α ( P  < 0.05), TRAF2 ( P  < 0.05), ASK1 ( P  < 0.05), Caspase-9 ( P  < 0.05), Caspase-8 ( P  < 0.05), Caspase-3 ( P  < 0.05), and Bax/Bcl-2 ( P  < 0.05), whereas nano-Se supplementation partially reversed these increases of gene expressions. In summary, this study provides evidence that dietary Hg exposure can induc