Abstract
Stable suspensions of NiO and Mn3O4 nanoparticles (NPs) with a mean (±s.d.) diameter of 16.7 ± 8.2 and 18.4 ± 5.4 nm, respectively, purposefully prepared by laser ablation of 99.99% pure nickel or manganese in de-ionized water, were repeatedly injected intraperitoneally (IP) to rats at a dose of 2.5 mg/kg 3 times a week up to 18 injections, either alone or in combination. A group of rats was injected with this combination with the background oral administration of a “bio-protective complex” (BPC) comprising pectin, vitamins A, C, E, glutamate, glycine, N-acetylcysteine, selenium, iodide and omega-3 PUFA, this composition having been chosen based on mechanistic considerations and previous experience. After the termination of injections, many functional and biochemical indices and histopathological features (with morphometric assessment) of the liver, spleen, kidneys and brain were evaluated for signs of toxicity. The Ni and Mn content of these organs was measured with the help of the atomic emission and electron paramagnetic resonance spectroscopies. We obtained blood leukocytes for performing the RAPD (Random Amplified Polymorphic DNA) test. Although both metallic NPs proved adversely bio-active in many respects considered in this study, Mn3O4-NPs were somewhat more noxious than NiO-NPs as concerns most of the non-specific toxicity manifestations and they induced more marked damage to neurons in the striatum and the hippocampus, which may be considered an experimental correlate of the manganese-induced Parkinsonism. The comparative solubility of the Mn3O4-NPs and NiO-NPs in a biological medium is discussed as one of the factors underlying the difference in their toxicokinetics and toxicities. The BPC has attenuated both the organ-systemic toxicity and the genotoxicity of Mn3O4-NPs in combination with NiO-NPs.
Highlights
Nanoparticles (NPs) of metal oxides are of special interest for industrial toxicology and for occupational health risk assessment and management because there exists a number of purposefully manufactured NPs of this class and because they constitute a substantial proportion within the particle size distribution of the condensation aerosols generated by arc-welding and various metallurgical technologies
This increase was not present in the group with background bio-protective complex (BPC) administration, and the Ni content of the liver in this group proved 2 times lower (p < 0.05) as compared with the group exposed to NPs of NiO-NPs + Mn3O4-NPs without the BPC
Under the influence of the BPC, the accumulation of manganese in the spleen and nickel in the brain decreased significantly while the same BPC increased nickel accumulation in the kidneys. Both NiO and Mn3O4 were detected with the help of Electron paramagnetic resonance (EPR) spectroscopy in the liver and spleen only, while the EPR signal of the Mn3O4-NPs was too weak for quantification
Summary
Nanoparticles (NPs) of metal oxides are of special interest for industrial toxicology and for occupational health risk assessment and management because there exists a number of purposefully manufactured (engineered) NPs of this class and because they constitute a substantial proportion within the particle size distribution of the condensation aerosols generated by arc-welding and various metallurgical technologies. Such aerosols commonly include, along with chemically similar fine micrometer particles and submicron ones having dimensions >100 nm, the conventional nanoscale fraction (
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