Enriched environment prevents oxidative stress in zebrafish submitted to unpredictable chronic stress.

Matheus Marcon,Ana P Herrmann,Angelo Piato,Anna M Siebel,Ricieri Mocelin,Adrieli Sachett

doi:10.7717/peerj.5136

Abstract

BackgroundThe 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.MethodsZebrafish 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.ResultsOur 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.DiscussionOur 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.

Highlights

The issue of housing condition of animals in the laboratory is widely acknowledged in scientific discussions (Kempermann, Kuhn & Gage, 1997; National Research Council (US) Committee for the Update of the Guide for the Care and Use of Laboratory Animals, 2011; Kim et al, 2017). Sherwin (2004), for example, reviewed theHow to cite this article Marcon et al (2018), Enriched environment prevents oxidative stress in zebrafish submitted to unpredictable chronic stress
In this study we tested the effects of EE in zebrafish submitted to unpredictable chronic stress (UCS) on a range of oxidative stress parameters including lipid peroxidation (TBARS), reactive oxygen species (ROS), non-protein thiol (NPSH) levels, total thiol (SH) levels, superoxide dismutase (SOD) activity, and catalase (CAT) activity
Regarding thiobarbituric acid reactive substances (TBARS) (Fig. 3A), two-way ANOVA revealed that UCS interacted with EE: stress only increased TBARS levels when fish were housed in barren tanks, but not when they were housed for 21 or 28 days of EE

Summary

Introduction

The issue of housing condition of animals in the laboratory is widely acknowledged in scientific discussions (Kempermann, Kuhn & Gage, 1997; National Research Council (US) Committee for the Update of the Guide for the Care and Use of Laboratory Animals, 2011; Kim et al, 2017). Sherwin (2004), for example, reviewed theHow to cite this article Marcon et al (2018), Enriched environment prevents oxidative stress in zebrafish submitted to unpredictable chronic stress. The standard laboratory condition for this species consists of housing the animal in shoals in barren tanks only with a recirculation system, heater thermostat (temperature control), and water in ideal conditions including physical, chemical and biological characteristics (pH, salinity, alkalinity, hardness, dissolved oxygen and nitrogen residues) (Lawrence & Mason, 2012). This housing environment is very far from the natural habitat conditions to zebrafish, that lives in shallow water with aquatic vegetation and gravel substrates (Arunachalam et al, 2013). EE promoted positive effects as it helped maintain the redox homeostasis, which may reduce the susceptibility to stress and its oxidative impact

Methods

Results

Discussion

Conclusion