Distribution of arsenic and oxidative stress in mice after rice ingestion

Abstract

This study evaluated the effects of rice naturally contaminated with arsenic (As) and the same As-species added as solubilized-salt on the redox state and the As distribution in male mice. The total As amount in the Brazilian polished rice used in this study was 169.81±6.12ngg^-1. Indeed, the concentrations of As species were 40.77ngg^-1 (arsenite, As³⁺), 65.71ngg^-1 (dimethylarsinic acid, DMA), 11.90ngg^-1 (monomethylarsonic acid, MMA), and 25.96ngg^-1 (arsenate, As⁵⁺). In this sense, animals were randomly divided into seven groups with six mice per group: I) control: habitual food; II) rice I: diet containing 10% of rice naturally containing As (4.08μg As³⁺/kg diet, 6.57μg DMA/kg diet, 1.19μg MMA/kg diet, and 2.60μg As⁵⁺/kg diet); III) rice II: diet containing 20% of rice naturally containing As (8.15μg As³⁺/kg diet, 13.14μg DMA/kg diet, 2.38μg MMA/kg diet, and 5.19μg As⁵⁺/kg diet); IV) rice III: diet containing 40% of rice naturally containing As (16.31μg As³⁺/kg diet, 26.28μg DMA/kg diet, 4.76μg MMA/kg diet, and 10.38μg As⁵⁺/kg diet); V) spiked feed I: diet containing As species as solubilized-salt (concentration equivalent to group II); VI) spiked feed II: diet containing As species as solubilized-salt (concentration equivalent to group III); VII) spiked feed III: diet containing As species as solubilized-salt (concentration equivalent to group IV). The time of treatment was 100days. After euthanasia, it was observed an increase in total As concentration in tissue samples of groups treated with diet containing rice naturally contaminated and diet containing As species. For instance, the highest As concentrations (higher than 330ngg^-1) was observed in the bladder of animals belonging to Rice II and III and spiked feed III groups. Furthermore, it was verified the highest As concentrations in bladder > hair > lung > kidney > liver > blood. We also observed the presence of DMA and As⁵⁺ in liver and kidneys. Regarding oxidative stress biomarkers, we observed significant reduction of Glutathione (GSH) concentration in blood of animals belonging to groups IV, V, VI and VII. Besides, the antioxidant enzymes activities, Glutathione Peroxidase (GSH-Px), Catalase (CAT) and superoxide dismutase (SOD), increased significantly in blood of animals belonging to group VII. On the other hand, it was not observed differences in nitric oxide (NO) levels among all the groups used in this study and the control group. Thus, we conclude that some minor effects were found in mice exposed to the diet containing the highest amount of rice naturally contaminated with As species. These findings contribute to evaluate the safety of human dietary consumption.

Keywords: Arsenic species; Chronic exposure; Diet; Oxidative stress; Rice.