Strenuous Acute Exercise Induces Slow and Fast Twitch-Dependent NADPH Oxidase Expression in Rat Skeletal Muscle.

Juliana Osório Alves,Vânia Marilande Ceccatto,Leonardo Matta Pereira,Crystianne Calado Lima,Adriano Cesar Carneiro Loureiro,Igor Cabral Coutinho Do Rêgo Monteiro,José Henrique Leal-Cardoso,Luiz Henrique Pontes Dos Santos,Denise Pires Carvalho,Rodrigo Soares Fortunato,Alex Soares Marreiros Ferraz

doi:10.3390/antiox9010057

Abstract

The enzymatic complex Nicotinamide Adenine Dinucleotide Phosphate (NADPH) oxidase (NOx) may be the principal source of reactive oxygen species (ROS). The NOX2 and NOX4 isoforms are tissue-dependent and are differentially expressed in slow-twitch fibers (type I fibers) and fast-twitch fibers (type II fibers) of skeletal muscle, making them different markers of ROS metabolism induced by physical exercise. The aim of this study was to investigate NOx signaling, as a non-adaptive and non-cumulative response, in the predominant fiber types of rat skeletal muscles 24 h after one strenuous treadmill exercise session. The levels of mRNA, reduced glycogen, thiol content, NOx, superoxide dismutase, catalase, glutathione peroxidase activity, and PPARGC1α and SLC2A4 gene expression were measured in the white gastrocnemius (WG) portion, the red gastrocnemius (RG) portion, and the soleus muscle (SOL). NOx activity showed higher values in the SOL muscle compared to the RG and WG portions. The same was true of the NOX2 and NOX4 mRNA levels, antioxidant enzymatic activities, glycogen content. Twenty-four hours after the strenuous exercise session, NOx expression increased in slow-twitch oxidative fibers. The acute strenuous exercise condition showed an attenuation of oxidative stress and an upregulation of antioxidant activity through PPARGC1α gene activity, antioxidant defense adaptations, and differential gene expression according to the predominant fiber type. The most prominent location of detoxification (indicated by NOX4 activation) in the slow-twitch oxidative SOL muscle was the mitochondria, while the fast-twitch oxidative RG portion showed a more cytosolic location. Glycolytic metabolism in the WG portion suggested possible NOX2/NOX4 non-regulation, indicating other possible ROS regulation pathways.

Highlights

Physical exercise activity increases by approximately 20 times the volume of total oxygen consumed (VO2 ) and by 100 times the VO2 in the active muscle fibers, generating reactive oxygen species (ROS)in skeletal muscle fibers [1]
The results indicated a significant increase in superoxide dismutase-1 (SOD1) in the exercise group in the red portion of the gastrocnemius and a significant reduction in the white portion
Our study has shown that red gastrocnemius (RG) muscle, with increased antioxidant defense (SOD2, CAT, and glutathione peroxidase (GPX)), is predominantly fast-twitch oxidative in a tissue-dependent way

Summary

Introduction

Physical exercise activity increases by approximately 20 times the volume of total oxygen consumed (VO2 ) and by 100 times the VO2 in the active muscle fibers, generating reactive oxygen species (ROS)in skeletal muscle fibers [1]. Nicotinamide Adenine Dinucleotide Phosphate (NADPH) oxidase complex effects are predominant above mitochondrial function. In this way, the NADPH oxidase—and not mitochondria—is the principal source of superoxide generation during short-term contractile activity. The NADPH oxidase produces superoxide by intracellular NADPH electron transfer through the membrane, docking them to molecular oxygen, which leads to ROS formation [3]. These enzymes present isoforms, which can be differentiated by local expression and by the cofactors used for their activation [4]. Phagocytic cells express six proteins, denoted as NOX1, NOX3, NOX 4 and NOX

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