Avaliação da toxicidade induzida por sulfato de cobre em larvas de peixe-zebra

Abstract

Copper is a metal naturally found in different environmental compartments. Furthermore, it is an important micronutrient for the metabolism of organisms. Concentrations of this metal are strongly influenced by industrial and agricultural activities, due to its biocidal properties. In Brazil, the maximum concentration of copper allowed in potable water is 2 mg/L. However, environmental contamination by this metal represents a serious environmental problem, in addition to being a risk to human health. Due to its chemical property of adopting distinct redox status, one of the proposed toxicity mechanisms is oxidative stress. Aquatic organisms are more susceptible to contamination by heavy metals, such as copper, which has been associated with physiological damage to exposed species. The zebrafish (Danio rerio) is a model organism that stands out in several fields of science, mainly in the toxicology of environmental contaminants. In this perspective, the present work aimed to investigate the toxicity induced by copper sulfate (CuSO4) in zebrafish larvae, evaluating environmentally relevant concentrations, to advance knowledge about impaired biochemical targets. Zebrafish larvae at 72 hours post-fertilization (hpf) were exposed to CuSO4 at concentrations of 1, 2 and 10 μM. The compound toxicity was evaluated in 96 hpf through morphological, behavioral and biochemical parameters. The results showed that CuSO4 impaired larval survival in a dose-dependent and compromising standard development, considering body length, yolk sac absorption and swim bladder inflammation. Through behavioral tests, CuSO4 inferred damage to motor escape response and swimming capacity. Biochemical parameters of oxidative stress showed that the compound increased the levels of reactive oxygen species (ROS) while decreasing the levels of non-protein thiols (NPSH) and compromised the cell viability of the exposed larvae. Thus, CuSO4, even in concentrations permitted by law, was able to change biochemical and behavioral parameters, in addition to impairing larval development. Thus, reinforcing the hypothesis of the involvement of oxidative stress in the toxicity induced by CuSO4.