Avaliação dos efeitos vasculares e renais induzidos pelo Diquat in vivo: potencial efeito vasculo protetor de nanopartículas de ouro

Abstract

Pesticides, widely used in agriculture, have significant toxic potential, impacting various biological and ecological systems. Among them, Diquat, a bipyridyl herbicide, stands out for its ability to induce oxidative stress, promoting the generation of reactive oxygen species (ROS) and damage to multiple organs, such as the kidneys and vascular system. However, the precise mechanisms of its toxicity, especially in in vivo models, remain poorly characterized. This study aimed to investigate the effects of Diquat on vascular reactivity and renal function parameters in mice, as well as to evaluate the protective potential of gold nanoparticles (GNPs) against vascular oxidative stress. C57BL/6J mice were treated with 20 mg/kg diquat and monitored for up to 5 days in a metabolic cage. For some experiments, the animals were also treated with different doses of GNP (0.19, 0.39, 1.97, or 3.94 mg/kg). After the established times, the animals were euthanized, and blood, urine, kidneys, and aorta were collected. Renal function was analyzed by analyzing urinary volume and flow, creatinine, urea, total protein, and γ-GT. Creatinine and urea concentrations, as well as total and differential leukocyte counts, were analyzed in the blood. Vascular function was assessed in the aorta using an isolated organ bath system. Relaxant and contractile responses were evaluated in the aortas of animals treated or not with different doses of GNP. The production of reactive oxygen species (ROS) and NO in the aortic segments was also evaluated by fluorescence microscopy. Treatment with diquat led to oliguric acute renal failure, evidenced by reduced urinary flow, increased creatinine and plasma urea nitrogen (BUN), and a decrease in glomerular filtration rate (GFR). The presence of disproportionate proteinuria, changes in the urinary marker UP/Cr, and an initial elevation of γ-GT reinforce the glomerular and tubular involvement, corroborated by histological data that showed tubular necrosis, interstitial edema, and glomerular injury with a high histopathological score. A systemic inflammatory profile with leukopenia and changes in circulating leukocyte cell populations, such as a reduction in polymorphonuclear cells and an increase in monocytes, were also observed after exposure to diquat. In the vascular context, the animals presented endothelial dysfunction dependent on the exposure time (reduced relaxation after 3 days and increased relaxation after 5 days). Contractile dysfunction marked by hyporesponsiveness to phenylephrine was also observed at all time points evaluated. These findings are associated with a significant elevation of reactive oxygen species (ROS) and compensatory nitric oxide (NO) production after 3 and 24 h of exposure. Treatment of the animals with 0.19 mg/kg GNP partially restored the phenylephrine-induced contraction pattern, reduced ROS levels, but did not reverse the diquat-induced increase in NO. It is concluded that diquat induces a systemic toxic syndrome characterized by acute renal failure and vascular dysfunction associated with oxidative stress. GNPs were able to partially reverse contractile hyporesponsiveness, likely related to their antioxidant effect, which reduces ROS levels.