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Oxidative Medicine and Cellular Longevity
Volume 2016 (2016), Article ID 9345970, 8 pages
http://dx.doi.org/10.1155/2016/9345970
Research Article

Characteristics of Skeletal Muscle Fibers of SOD1 Knockout Mice

1Biological Sciences, Graduate School of Medicine, Yamaguchi University, Yamaguchi, Yamaguchi Perfecture 753-8515, Japan
2Biological Chemistry, Faculty of Agriculture, Yamaguchi University, Yamaguchi, Yamaguchi Perfecture 753-8515, Japan
3Department of Biochemistry and Molecular Biology, Graduate School of Medical Science, Yamagata University, Yamagata, Yamagata Perfecture 990-9585, Japan

Received 7 August 2015; Accepted 21 September 2015

Academic Editor: Paola Venditti

Copyright © 2016 Hiroshi Nagahisa et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Cu/Zn superoxide dismutase (SOD1) knockout (KO) mice are known as an aging model in some aspects, but the damage and regeneration process of each fiber type have not been sufficiently studied. In this study, we investigated the damage and satellite cell state of the gastrocnemius muscle in SOD1 KO mice (6 months old) using immunohistochemical staining and real-time RT-PCR. The proportion of central nuclei-containing Type IIx/b fibers in the deep and superficial portions of the gastrocnemius muscle was significantly higher in SOD1 KO than control mice. The number of satellite cells per muscle fiber decreased in all muscle fiber types in the deep portion of the gastrocnemius muscle in SOD1 KO mice. In addition, the mRNA expression levels of Pax7 and myogenin, which are expressed in satellite cells in the activation, proliferation, and differentiation states, significantly increased in the gastrocnemius muscle of SOD1 KO mice. Furthermore, mRNA of myosin heavy chain-embryonic, which is expressed in the early phase of muscle regeneration, significantly increased in SOD1 KO mice. It was suggested that muscle is damaged by reactive oxygen species produced in the mitochondrial intermembrane space in Type IIxb fibers, accelerating the proliferation and differentiation of satellite cells through growth factors in SOD1 KO mice.