Manganese is an essential element for many physiological processes. However, in prolonged exposures or at high concentrations it may present toxicity to several organs, which has made it an object of study in pharmacological, behavioral, neurological and environmental research in different organisms. Thus, it was aimed to evaluate the damage caused by acute and chronic exposures to this element, through the histopathological analysis of the zebrafish (Danio rerio) intestine. Samples were embedded in paraffin for further processing in rotating microtome, and the slides were stained with Alcian Blue and hematoxylin for observation and analysis under light microscopy. The results demonstrated the potential of the metal to cause histological changes in this organ, such as fusion of villi (in 0.5 and 4.0 mg L-1), and to increase by more than 50% the number of goblet cells (in 8.0 and 16 mg L-1) in the region analyzed, mainly in the highest concentrations of Manganese Chloride and in chronic exposures, characterizing a possible inflammation of the intestinal epithelium. Thus, the histological analysis of intestines demonstrated to be a reliable alternative for the toxicological evaluation. It is important to monitor the concentrations of this and other metals in the water bodies, given their toxicity.

No abstract

Synthetic estrogen 17α-ethinyl estradiol (EE2) is recognized for its ability to cause endocrine disruption in aquatic organisms and its high resistance to environmental degradation, being found in Brazilian waterbodies up to 100 ng L -1 . Thus, the aim of this study was to evaluate the exploratory behavior and the histological effects on zebrafish gonads, caused by environmentally relevant concentrations of EE2. Females were exposed to nominal concentrations of 25 ng L -1 and 100 ng L -1 EE2 for 21 days. After that, a behavioral and histological analysis of gonads was performed. The EE2 caused the reduction of the exploratory activity of the animals, when observed the behavior, and an acceleration of the maturation process of the oocytes evaluated in the histological analysis. Considering the results obtained after the exposure to EE2, we highlight the concern about the potential risks it may cause to the aquatic biota, alerting to the need to control and monitor these micropollutants present in Brazilian water resources.