Role of Endoplasmic Reticulum Stress in Nano-Selenium Alleviating Prehierarchical Follicular Atresia Induced by Mercury in Laying Hens.

This study investigated that the effect of nano-selenium (nano-Se) addition preventing prehierarchical follicular atresia induced by mercury (Hg) exposure in laying hens. Furthermore, endoplasmic reticulum (ER) stress pathway was explored to reveal the protective mechanism of nano-Se in vitro. The results revealed that Hg could significantly reduce laying performance (P < 0.05) and egg quality (P < 0.05), whereas nano-Se addition partially reversed the reductions. Besides, Hg significantly induced the deposition of Hg in prehierarchical follicles (P < 0.05) and prehierarchical follicular atresia (P < 0.05), whereas nano-Se addition could alleviate these toxicities in vitro. In addition, Hg exposure could significantly reduce cell viability (P < 0.05) and induce pyknotic nucleus in prehierarchical granulosa cells, while nano-Se addition reversed these effects. The levels of follicle-stimulating hormone (P < 0.05), luteinizing hormone (P < 0.05), progesterone (P < 0.05), and estradiol (P < 0.05) were significantly decreased after Hg exposure in vitro. However, nano-Se addition reversed the decreases of sex hormone levels. Furthermore, Hg exposure significantly increased the gene expressions of CHOP (P < 0.05), PERK (P < 0.05), ATF4 (P < 0.05), ATF6 (P < 0.05), ASK1 (P < 0.05), IRE1α (P < 0.05), TRAF2 (P < 0.05), caspase-9 (P < 0.05), caspase-3 (P < 0.05), and Bax/Bcl-2 (P < 0.05), whereas nano-Se addition reversed these increases of gene expressions in vitro. In summary, this study provides that Hg can induce prehierarchical follicular atresia, whereas nano-Se addition can ameliorate it, and elucidates an important role of ER stress in nano-Se alleviating prehierarchical follicular atresia induced by Hg in laying hens.

Protective Effect of Nanoselenium on Renal Oxidative Damage Induced by Mercury in Laying Hens.

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 induce renal oxidative damages, and elucidates an important role of ER stress pathway in nano-Se alleviating renal apoptosis in laying hens.