Endurance exercise differentially stimulates heart and axial muscle development in zebrafish (Danio rerio)

• Published in: American journal of physiology. Regulatory, integrative and comparative physiology integrative and comparative physiology, 2006-10, Vol.291 (4), p.R1040-R1048
• Main Authors: van der Meulen, T, Schipper, H, van den Boogaart, J. G. M, Huising, M. O, Kranenbarg, S, van Leeuwen, J. L
• Format: Article
• Language: English
• Subjects: Animals; Behavior, Animal - physiology; Body Size - physiology; brachydanio-rerio; Cell Division - genetics; Conditioning (Psychology) - physiology; Energy Metabolism - genetics; erythropoietin; Erythropoietin - genetics; expression; Female; fibers; Gene Expression Profiling; Gene Expression Regulation, Developmental; growth; Heart - growth & development; Heart - physiology; Male; Muscle, Skeletal - cytology; Muscle, Skeletal - growth & development; Muscle, Skeletal - physiology; Myocardium - cytology; Myoglobin - genetics; oncorhynchus-mykiss; ontogeny; Oxygen - metabolism; Physical Conditioning, Animal - physiology; Physical Endurance - physiology; rainbow-trout; Swimming - physiology; teleost fish; Weight-Bearing - physiology; Zebrafish
• ISSN: 0363-6119; 1522-1490
• DOI: 10.1152/ajpregu.00116.2006

1 Experimental Zoology Group, Wageningen University, Wageningen; and 2 Department of Animal Physiology, Radboud University Nijmegen, Nijmegen, The Netherlands Submitted 15 February 2006 ; accepted in final form 16 May 2006 Mechanical load is an important factor in the differentiation of cells and tissues. To investigate the effects of increased mechanical load on development of muscle and bone, zebrafish were subjected to endurance swim training for 6 h/day for 10 wk starting at 14 days after fertilization. During the first 3 wk of training, trained fish showed transiently increased growth compared with untrained (control) fish. Increased expression of proliferating cell nuclear antigen suggests that this growth is realized in part through increased cell proliferation. Red and white axial muscle fiber diameter was not affected. Total cross-sectional area of red fibers, however, was increased. An improvement in aerobic muscle performance was supported by an increase in myoglobin expression. At the end of 10 wk of training, heart and axial muscle showed increased expression of the muscle growth factor myogenin and proliferating cell nuclear antigen, but there were major differences between cardiac and axial muscle. In axial muscle, expression of the "slow" types of myosin and troponin C was increased, together with expression of erythropoietin and myoglobin, which enhance oxygen transport, indicating a shift toward a slow aerobic phenotype. In contrast, the heart muscle shifts to a faster phenotype but does not become more aerobic. This suggests that endurance training differentially affects heart and axial muscle. endurance exercise; mechanical load; aerobic muscle development Address for reprint requests and other correspondence: T. van der Meulen, Wageningen Univ., Experimental Zoology Group, Marijkeweg 40, 6709 PG Wageningen, The Netherlands (e-mail: tvanderm{at}sciences.sdsu.edu )