No abstract

Studies have demonstrated that nano NiO could induce liver toxicity in rats, but its mechanism remains unclear. This study aimed to explore the role of the NF-κB signaling pathway in rat liver toxicity after nano NiO exposure. Male Wistar rats were exposed to nano NiO (0.015, 0.06 and 0.24 mg per kg b.w.) and micro NiO (0.24 mg per kg b.w.) by intratracheal instillation twice a week for 6 weeks. To investigate the liver toxicity induced by nano NiO, the indicators of liver function and inflammatory response were detected, and the histopathological changes were observed. The levels of NF-κB signaling pathway related gene and protein expression were examined using RT-qPCR and western blot techniques in the liver tissue. The results showed that the activities of alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP) and gamma-glutamyltranspeptidase (GGT) increased after nano NiO exposure. Cellular edema, hepatic sinus disappearance, and neutrophil and lymphocyte infiltration were observed. Nano NiO increased the concentrations of pro-inflammatory cytokines (IL-1β and IL-6), but decreased the levels of anti-inflammatory cytokines (IL-4 and IL-10). It also induced the upregulation of TNF-α, NF-κB-inducible kinase (NIK), IκB kinase alpha (IKK-α) and NF-κB mRNA, while inducing the downregulation of the inhibitor kappa B (IκB) alpha. In addition, we found that the protein content of NIK, IKK-α, p-IKK-α, p-IκB-α and NF-κB was elevated, whereas that of IκB-α was reduced. The results indicated that the NF-κB signaling pathway played an important role in rat liver toxicity induced by nano NiO.

CIS: Cisplatin; GSPE: grape seed procyanidins extract; LH: luteinizing hormone; FSH: follicle-stimulating hormone; STAR: steroidogenic acute regulatory protein; CYP11A1: P450 side chain cleavage enzyme; HSD3B1: 3β-hydroxysteroid dehydrogenase; CYP17A1: 17α-hydroxylase; HSD17B: 17β-hydroxysteroid dehydrogenase; ROS: reactive oxygen species; O2: superoxide anion; HO: hydrogen peroxide; •OH: hydroxyl radicals; SOD: superoxide dismutase; CAT: catalase; GSH-Px: glutathione peroxidase; LPO: lipid peroxidation; 8-OHdG: 8-hydroxy-2-deoxyguanosine; HO-1: heme oxygenase-1; MT-1: metallothionein-1; NO: nitric oxide; ONOO-: peroxynitrite; NOS: nitric oxide synthases; nNOS: neuronal NOS; iNOS: inducible NOS; eNOS: endothelial NOS; MDA: malondialdehyde; GSH: glutathione; T-AOC: total antioxidant capacity; TNOS: total nitric oxide synthases; Lhcgr: luteinizing hormone receptor; Scarb1: lipoprotein-receptor; Cyp19a1: 19α-hydroxylase; ELISA: enzyme linked immunosorbent assay; RT-qPCR: reverse transcription-quantitative polymerase chain reaction; PAS: periodic acid-Schiff; MTs: Metallothioneins; cAMP: cyclic adenosine monophosphate; cDNA: complementary DNA; RIPA: radioimmunoprecipitation buffer; PMSF: phenylmethanesulfonyl fluoride; PVDF: polyvinylidenedifluoride; β-actin: beta-actin.

Nickel oxide nanoparticles (nano NiO) could induce hepatocyte apoptosis, while its potential mechanisms are unclear. This study aimed to explore the role of endoplasmic reticulum (ER) stress pathways in hepatocyte apoptosis induced by nano NiO. Male Wistar rats were administrated with nano NiO (0.015, 0.06, and 0.24 mg/kg b.w.) and micro NiO (0.24 mg/kg b.w.) by intratracheal instillation twice a week for 6 weeks. We measured the hepatocyte apoptosis levels by TdT-mediated dUTP nick-end labeling (TUNEL) staining, ER stress related gene and protein expression levels in rat liver. The results showed that the TUNEL positive cells increased after exposure nano NiO, hinting hepatocyte apoptosis. The up-regulated gene and protein levels of 78 kD glucose regulated protein and CCAAT/enhancer binding protein homologous protein suggested that nano NiO triggered ER stress. Nano NiO exposure contributed to the increased protein contents of inositol-requiring enzyme 1 (IRE-1)α, p-IRE-1α, X box protein-1S, pancreatic ER kinase (PERK), p-PERK, eukaryotic initiation factor-2 alpha (eIF-2α), p-eIF-2α, caspase-12, -9, and -3, implicating that nano NiO can activate the pathways of ER stress-mediated apoptosis. These findings indicate that the ER stress pathways may play an important role in hepatocyte apoptosis induced by nano NiO.