title: Establishing zebrafish as a novel exercise model: swimming economy, swimming-enhanced growth and muscle growth marker gene expression.
abstract: BACKGROUND
  Zebrafish has been largely accepted as a vertebrate multidisciplinary model but its usefulness as a model for exercise physiology has been hampered by the scarce knowledge on its swimming economy, optimal swimming speeds and cost of transport. Therefore, we have performed individual and group-wise swimming experiments to quantify swimming economy and to demonstrate the exercise effects on growth in adult zebrafish.
  
  
  RESULTS
  Individual zebrafish (n = 10) were able to swim at a critical swimming speed (U(crit)) of 0.548±0.007 m s(-1) or 18.0 standard body lengths (BL) s(-1). The optimal swimming speed (U(opt)) at which energetic efficiency is highest was 0.396±0.019 m s(-1) (13.0 BL s(-1)) corresponding to 72.26±0.29% of U(crit). The cost of transport at optimal swimming speed (COT(opt)) was 25.23±4.03 µmol g(-1) m(-1). A group-wise experiment was conducted with zebrafish (n = 83) swimming at U(opt) for 6 h day(-1) for 5 days week(-1) for 4 weeks vs. zebrafish (n = 84) that rested during this period. Swimming zebrafish increased their total body length by 5.6% and body weight by 41.1% as compared to resting fish. For the first time, a highly significant exercise-induced growth is demonstrated in adult zebrafish. Expression analysis of a set of muscle growth marker genes revealed clear regulatory roles in relation to swimming-enhanced growth for genes such as growth hormone receptor b (ghrb), insulin-like growth factor 1 receptor a (igf1ra), troponin C (stnnc), slow myosin heavy chain 1 (smyhc1), troponin I2 (tnni2), myosin heavy polypeptide 2 (myhz2) and myostatin (mstnb).
  
  
  CONCLUSIONS
  From the results of our study we can conclude that zebrafish can be used as an exercise model for enhanced growth, with implications in basic, biomedical and applied sciences, such as aquaculture.
authors.affiliation: Departament de Fisiologia, Facultat de Biologia, Institut de Biomedicina de la Universitat de Barcelona, Universitat de Barcelona, Barcelona, Spain. palstra@ub.edu
authors.forename: Arjan P
authors.initials: AP
authors.lastname: Palstra
authors.forename: Christian
authors.initials: C
authors.lastname: Tudorache
authors.forename: Mireia
authors.initials: M
authors.lastname: Rovira
authors.forename: Sebastiaan A
authors.initials: SA
authors.lastname: Brittijn
authors.forename: Erik
authors.initials: E
authors.lastname: Burgerhout
authors.forename: Guido E E J M
authors.initials: GE
authors.lastname: van den Thillart
authors.forename: Herman P
authors.initials: HP
authors.lastname: Spaink
authors.forename: Josep V
authors.initials: JV
authors.lastname: Planas
mesh_terms: D000818:Animals; D001483:Base Sequence; D017931:DNA Primers / Q000235:genetics; D004734:Energy Metabolism / Q000235:genetics; D023421:Models, Animal; D008954:Models, Biological; D008969:Molecular Sequence Data; D009132:Muscles / Q000378:metabolism*; D010101:Oxygen Consumption; D010805:Physical Conditioning, Animal; D016133:Polymerase Chain Reaction / Q000379:methods; D013550:Swimming / Q000502:physiology*; D015027:Zebrafish
chemical_list: D017931:DNA Primers