Chronic exposure of tilapia (Oreochromis niloticus) to iron oxide nanoparticles: Effects of particle morphology on accumulation, elimination, hematology and immune responses

Abstract

Effects of chronic exposure to alpha and gamma iron oxide nanoparticles (α-Fe2O3 and γ-Fe2O3 NPs) were investigated through exposure of tilapia (Oreochromis niloticus) to 0.1, 0.5 and 1.0 mg/L (9.2×10−4, 4.6×10−3 and 9.2×10−3 mM) aqueous suspensions for 60 days. Fish were then transferred to NP-free freshwater and allowed to eliminate ingested NPs for 30 days. The organs, including gills, liver, kidney, intestine, brain, spleen, and muscle tissue of the fish were analyzed to determine the accumulation, physiological distribution and elimination of the Fe2O3 NPs. Largest accumulation occurred in spleen followed by intestine, kidney, liver, gills, brain and muscle tissue. Fish exposed to γ-Fe2O3 NPs possessed significantly higher Fe in all organs. Accumulation in spleen was fast and independent of NP concentration reaching to maximum levels by the end of the first sampling period (30th day). Dissolved Fe levels in water were very negligible ranging at 4–6 μg/L for α-Fe2O3 and 17–21 μg/L for γ-Fe2O3 NPs (for 1 mg/L suspensions). Despite that, Fe levels in gills and brain reflect more dissolved Fe accumulation from metastable γ-Fe2O3 polymorph. Ingested NPs cleared from the organs completely within 30-day elimination period, except the liver and spleen. Liver contained about 31% of α- and 46% of γ-Fe2O3, while spleen retained about 62% of α- and 35% of the γ-polymorph. No significant disturbances were observed in hematological parameters, including hemoglobin, hematocrit, red blood cell and white blood cell counts (p > 0.05). Serum glucose (GLU) levels decreased in treatments exposed to 1.0 mg/L of γ-Fe2O3 NPs at day 30 (p < 0.05). In contrast, GLU levels increased during the elimination period for 1.0 mg/L α-Fe2O3 NPs treatments (p < 0.05). Transient increases occurred in glutamic oxaloacetic transaminase (GOT), glutamic pyruvic transaminase (GPT), and lactate dehydrogenase (LDH). Serum Fe levels did not change during exposure (p > 0.05), but increased significantly within elimination period due to mobilization of ingested NPs from liver and spleen to blood. Though respiratory burst activity was not affected (p > 0.05), lysozyme activity (LA) was suppressed suggesting an immunosuppressive effects from both Fe2O3 NPs (p < 0.05). In contrast, myeloperoxidase (MPO) levels increased significantly in treatments exposed to α-Fe2O3 NPs (p < 0.05), and the effect from γ-polymorph was marginal (p ≥ 0.05). The results indicate that morphological differences of Fe2O3 NPs could induce differential uptake, assimilation and immunotoxic effects on O. niloticus under chronic exposure.

The Toxicity Assessment of Iron Oxide (Fe3O4) Nanoparticles on Physical and Biochemical Quality of Rainbow Trout Spermatozoon

“…In this respect, the results are also similar to situations such as reproductive disorders and the deterioration of biological activities in rainbow trout spermatozoon. In addition, our results are supported by the data of other researchers [12,19,20,45,46].…”

“…While the level of serum glucose (GLU) decreased, the levels of glutamic oxaloacetic transaminase (GOT), glutamic pyruvic transaminase (GPT), and lactate dehydrogenase (LDH) increased. Finally, they determined that Fe 2 O 3 NPs can induce differential uptake, assimilation, and immunotoxic effects on O. Niloticus under chronic exposure [12].…”

“…Furthermore, the potential ecotoxicological impacts in aquatic environments have aroused increasing attention. For example, over the last five years, there have been some studies about the ecotoxicology of iron-based NPs in aquatic animals such as an Indian major carp fish ( Labeo rohita ) [11], tilapia ( Oreochromis niloticus ) [12], Chinook salmon ( Oncorhynchus tshawytscha ) [13], zebrafish ( Danio rerio ) [14,15,16], Mytilus galloprovincialis [17], Daphnia magna [18], Artemia salina [19,20], and rotifer ( Brachionus rotundiformis ) [21].…”

Health concerns of various nanoparticles: A review of their in vitro and in vivo toxicity

“…The reticuloendothelial system (RES) is generally effective on the biological distribution of NPs and their accumulation in the spleen. NPs stay for a long time, up to 100 days, in the spleen [153].…”

EFEITOS DE NANOPARTÍCULAS COMERCIAIS DE ÓXIDO DE FERRO (Fe2O3): CITOTOXICIDADE, GENOTOXICIDADE E ESTRESSE OXIDATIVO

“…Além da desintoxicação, o fígado também está envolvido no processo de filtração como o baço e o rim e, neste sentido, é um órgão alvo em peixes expostos a NPs. 51 Ademais, a atividade aumentada da CAT demonstra também uma resposta adaptativa dos diferentes órgãos às NPs, na tentativa de neutralizar as EROs. De acordo com Hermes-Lima, 52 maiores atividades da CAT são observadas quando há elevação da peroxidação lipídica.…”