Oxidative stress markers and antioxidant defense in hibernating common Asian toads, Duttaphrynus melanostictus

Deba Sahoo,Prabhati Patnaik

doi:10.2298/abs190605062s

Abstract

Paper description: In hibernating common Asian toad, in spite of metabolic depression, low body temperature, and slow breathing, oxidative stress was observed. Oxidative stress markers were at higher levels in liver and brain tissues. Increased lipid peroxidation, protein carbonylation and oxidized/reduced glutathione ratio were accompanied by augmented non-enzymatic antioxidant defense which counteracts the oxidative assault in liver and brain tissues during hibernation. Abstract: To assess the oxidative assaults and antioxidant defense, oxidative stress markers, including lipid peroxidation level, protein carbonylation level, GSSG/GSH ratio and nonenzymatic antioxidants such as total glutathione, ascorbic acid and uric acid, in liver and brain tissues of hibernating common Asian toads, Duttaphrynus melanostictus , were compared with toads during active periods. Oxidative stress was found in both liver and brain tissues of hibernating common Asian toads in spite of depressed metabolism and low oxygen consumption. Significantly higher lipid peroxidation, protein carbonylation and an increased GSSG/GSH ratio were found in liver and brain tissues of hibernating toads, indicating oxidative stress. To counteract the stress, ascorbic acid was increased significantly in the liver and brain tissues of hibernating individuals in comparison to individuals during active periods. The uric acid level decreased in both the liver and brain tissues of hibernating toads, which may be due to its decreased rate of synthesis because of low xanthine oxidase activity at low body temperature and hypometabolism. The common Asian toad faced oxidative stress during hibernation, which was counteracted by augmented nonenzymatic antioxidant defense. https://doi.org/10.2298/ABS190605062S Received: June 5, 2019; Revised: August 24, 2019; Accepted: September 9, 2019; Published online: September 25, 2019 How to cite this article: Sahoo DD, Patnaik P. Oxidative stress markers and antioxidant defense in hibernating common Asian toads, Duttaphrynus melanostictus . Arch Biol Sci. 2020;72(1):23-30.

Highlights

In all aerobic organisms, reactive oxygen species(ROS) such as superoxide radicals (O2 ̇-), hydroxyl radicals (OH) and hydrogen peroxide (H2O2) that are produced during cellular metabolism promote the oxidation of biomolecules, and their damaging effects are minimized by antioxidant defenses comprising antioxidant enzymes and nonenzymatic antioxidants
In the present work we examined whether oxidative stress markers increase during hibernation in spite of low oxygen consumption and depressed metabolism, and what happens to the antioxidant defense status, to selected nonenzymatic antioxidants, during hibernation
The decrease in the GSHeq was due to a decrease in GSH, which led to a significant increase (P

Summary

Introduction

Reactive oxygen species(ROS) such as superoxide radicals (O2 ̇-), hydroxyl radicals (OH) and hydrogen peroxide (H2O2) that are produced during cellular metabolism promote the oxidation of biomolecules, and their damaging effects are minimized by antioxidant defenses comprising antioxidant enzymes and nonenzymatic antioxidants. One of them is to minimize the level of oxygen uptake or to deter its conversion to ROS [9] Another way is by evolving an antioxidant defense system to counteract the oxidative stress. This is again either by catalytic removal of ROS by antioxidant enzymes (superoxide dismutase, catalase, glutathione peroxidase), or by scavenging ROS by nonenzymatic antioxidants (α-tocopherol, ascorbic acid, reduced glutathione, uric acid) [10]. GSH is converted into its oxidized form, glutathione disulfide (GSSG), by donation of a reducing equivalent (H++e-) to the ROS

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