title: Cross-training in birds: cold and exercise training produce similar changes in maximal metabolic output, muscle masses and myostatin expression in house sparrows (Passer domesticus).
abstract: Maximal metabolic outputs for exercise and thermogenesis in birds presumably influence fitness through effects on flight and shivering performance. Because both summit (Msum, maximum thermoregulatory metabolic rate) and maximum (MMR, maximum exercise metabolic rate) metabolic rates are functions of skeletal muscle activity, correlations between these measurements and their mechanistic underpinnings might occur. To examine whether such correlations occur, we measured the effects of experimental cold and exercise training protocols for 3 weeks on body (Mb) and muscle (Mpec) masses, basal metabolic rate (BMR), Msum, MMR, pectoralis mRNA and protein expression for myostatin, and mRNA expression of TLL-1 and TLL-2 (metalloproteinase activators of myostatin) in house sparrows (Passer domesticus). Both training protocols increased Msum, MMR, Mb and Mpec, but BMR increased with cold training and decreased with exercise training. No significant differences occurred for pectoralis myostatin mRNA expression, but cold and exercise increased the expression of TLL-1 and TLL-2. Pectoralis myostatin protein levels were generally reduced for both training groups. These data clearly demonstrate cross-training effects of cold and exercise in birds, and are consistent with a role for myostatin in increasing pectoralis muscle mass and driving organismal increases in metabolic capacities.
authors.affiliation: Department of Biology, University of South Dakota, Vermillion, SD 57069, USA yufeng.zhang@usd.edu.
authors.forename: Yufeng
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Basic Biomedical Sciences, Sanford School of Medicine, University of South Dakota, Vermillion, SD 57105, USA.
authors.forename: Kathleen
authors.initials: K
authors.lastname: Eyster
authors.affiliation: School of Life and Environmental Sciences, Wenzhou University, Wenzhou 325035, China.
authors.forename: Jin-Song
authors.initials: JS
authors.lastname: Liu
authors.affiliation: Department of Biology, University of South Dakota, Vermillion, SD 57069, USA.
authors.forename: David L
authors.initials: DL
authors.lastname: Swanson
mesh_terms: D000222:Adaptation, Physiological; D000818:Animals; D001481:Basal Metabolism; D003080:Cold Temperature; D004734:Energy Metabolism; D015870:Gene Expression; D050356:Lipid Metabolism; D055435:Myostatin / Q000378:metabolism*; D009929:Organ Size; D010369:Pectoralis Muscles / Q000033:anatomy & histology / Q000378:metabolism*; D010805:Physical Conditioning, Animal; D012333:RNA, Messenger / Q000378:metabolism; D046370:Sparrows / Q000502:physiology*; D022722:Thermogenesis; D055394:Tolloid-Like Metalloproteinases / Q000378:metabolism
chemical_list: D055435:Myostatin; D012333:RNA, Messenger; D055394:Tolloid-Like Metalloproteinases
keywords: BMR; Birds; Cold training; Exercise training; MMR; Msum; Myostatin; Pectoralis; Phenotypic flexibility