Background: The enriched environment (EE) is a laboratory housing model that emerged from efforts to minimize the impact of environmental conditions on laboratory animals. Recently, we showed that EE promoted positive effects on behavior and cortisol levels in zebrafish submitted to the unpredictable chronic stress (UCS) protocol. Here, we expanded the characterization of the effects of UCS protocol by assessing parameters of oxidative status in the zebrafish brain and reveal that EE protects against the oxidative stress induced by chronic stress.Methods: Zebrafish were exposed to EE (21 or 28 days) or standard housing conditions and subjected to the UCS protocol for seven days. Oxidative stress parameters (lipid peroxidation (TBARS), reactive oxygen species (ROS) levels, non-protein thiol (NPSH) and total thiol (SH) levels, superoxide dismutase (SOD) and catalase (CAT) activities were measured in brain homogenate.Results: Our results revealed that UCS increased lipid peroxidation and ROS levels, while decreased NPSH levels and SOD activity, suggesting oxidative damage. EE for 28 days prevented all changes induced by the UCS protocol, and EE for 21 days prevented the alterations on NPSH levels, lipid peroxidation and ROS levels. Both EE for 21 or 28 days increased CAT activity.Discussion: Our findings reinforce the idea that EE exerts neuromodulatory effects in the zebrafish brain. EE promoted positive effects as it helped maintain the redox homeostasis, which may reduce the susceptibility to stress and its oxidative impact.

Cynara scolymus L., Asteraceae, are traditionally used to treat dyspepsia. This study evaluated the hypolipidemic and antiatherogenic effects of an aqueous extract prepared from the leaves of C. scolymus in rat's model. Hypercholesterolemic rats (1% cholesterol and 0.5% cholic acid for 15 days) were treated (0.5ml/200g) with extract of C. scolymus (150, 300, or 600mg/kg p.o.; n=6) or simvastatin (4mg/kg p.o.; n=6) once per day for 30 days along with hypercaloric diet. A control group (C) was given water (0.5ml/200g; n=6). A high-cholesterol diet was maintained throughout the treatment period. Rats treated with extract of C. scolymus (150, 300, or 600mg/kg) and simvastatin showed significant decreases in serum levels of total cholesterol (−46.9%, −51.9%, −44%, and −41.9%, respectively) and low-density lipoprotein-cholesterol (LDL-C; −52.1%, −54.8%, −51.9%, and −46.7%, respectively), compared with group C (p<0.005). Biochemical analyses revealed significant decrease in the concentration of IL-1, IL-6, TNF-α, IFN-γ, C-reactive protein, oxidized-LDL, and antioxidized-LDL in rats treated with extract of C. scolymus (150, 300, or 600mg/kg). There were no differences in serum ALT enzyme activity between the groups. Our results suggest that hypolipidemic and antiatherogenic effects could be related with the presence of polar substances present in aqueous extract of C. scolymus

The occurrence of ractopamine (RAC) hydrochloride in water bodies is of significant concern due to its ecological impacts and toxicity to humans. RAC hydrochloride is a β-adrenergic agonist drug used as a feed additive to (1) improve feed efficiency, (2) rate of weight gain, and (3) increase carcass leanness in animals raised for their meat. This drug is excreted by animals in urine and introduced into the environment affecting nontarget organisms including fish. In wastewater released from farms, RAC concentrations were detected from 0.124 µg/L to 30.1 µg/L, and in levels ranging from 1.3 × 10⁻⁵ to 5.4 × 10⁻⁴ μg/L in watersheds. The aim of this study was to examine the effects of exposure to RAC at 0.1, 0.2, 0.85, 8.5, or 85 µg/L dissolved in water on behavior and oxidative status in adult zebrafish. At 0.85 µg/L, RAC treatment increased exploratory behavior of zebrafish; while at 8.5 µg/L, decreased locomotor and exploratory activities were noted. With respect to oxidative stress biomarkers, results showed that RAC at 0.2 µg/L induced lipid peroxidation and elevated total thiol content in zebrafish brain. All drug tested concentrations produced a fall in nonprotein thiol content. Finally, RAC at 0.85, 8.5, or 85 µg/L increased catalase enzyme activity. Our results demonstrated that the exposure to RAC induced behavioral alterations and oxidative stress in zebrafish.