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Khan RH, Rhodes JS, Girard IA, Schwartz NE, Garland T. Does Behavior Evolve First? Correlated Responses to Selection for Voluntary Wheel-Running Behavior in House Mice. ECOLOGICAL AND EVOLUTIONARY PHYSIOLOGY 2024; 97:97-117. [PMID: 38728689 DOI: 10.1086/730153] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2024]
Abstract
AbstractHow traits at multiple levels of biological organization evolve in a correlated fashion in response to directional selection is poorly understood, but two popular models are the very general "behavior evolves first" (BEF) hypothesis and the more specific "morphology-performance-behavior-fitness" (MPBF) paradigm. Both acknowledge that selection often acts relatively directly on behavior and that when behavior evolves, other traits will as well but most with some lag. However, this proposition is exceedingly difficult to test in nature. Therefore, we studied correlated responses in the high-runner (HR) mouse selection experiment, in which four replicate lines have been bred for voluntary wheel-running behavior and compared with four nonselected control (C) lines. We analyzed a wide range of traits measured at generations 20-24 (with a focus on new data from generation 22), coinciding with the point at which all HR lines were reaching selection limits (plateaus). Significance levels (226 P values) were compared across trait types by ANOVA, and we used the positive false discovery rate to control for multiple comparisons. This meta-analysis showed that, surprisingly, the measures of performance (including maximal oxygen consumption during forced exercise) showed no evidence of having diverged between the HR and C lines, nor did any of the life history traits (e.g., litter size), whereas body mass had responded (decreased) at least as strongly as wheel running. Overall, results suggest that the HR lines of mice had evolved primarily by changes in motivation rather than performance ability at the time they were reaching selection limits. In addition, neither the BEF model nor the MPBF model of hierarchical evolution provides a particularly good fit to the HR mouse selection experiment.
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2
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The metabolic cost of physical activity in mice using a physiology-based model of energy expenditure. Mol Metab 2023; 71:101699. [PMID: 36858190 PMCID: PMC10090438 DOI: 10.1016/j.molmet.2023.101699] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/12/2022] [Revised: 02/14/2023] [Accepted: 02/21/2023] [Indexed: 03/03/2023] Open
Abstract
OBJECTIVE Physical activity is a major component of total energy expenditure (TEE) that exhibits extreme variability in mice. Our objective was to construct a general, physiology-based model of TEE to accurately quantify the energy cost of physical activity. METHODS Spontaneous home cage physical activity, body temperature, TEE, and energy intake were measured with frequent sampling. The energy cost of activity was modeled considering six contributors to TEE (basal metabolic rate, thermic effect of food, body temperature, cold induced thermogenesis, physical activity, and body weight). An ambient temperature of 35 °C was required to remove the contribution from cold induced thermogenesis. Basal metabolic rate was adjusted for body temperature using a Q10 temperature coefficient. RESULTS We developed a TEE model that robustly explains 70-80% of the variance in TEE at 35 °C while fitting only two parameters, the basal metabolic rate and the mass-specific energy cost per unit of physical activity, which averaged 60 cal/km/g body weight. In Ucp1-/- mice the activity cost was elevated by 60%, indicating inefficiency and increased muscle thermogenesis. The diurnal rhythm in TEE was quantitatively explained by the combined diurnal differences in physical activity, body temperature, and energy intake. CONCLUSIONS The physiology-based model of TEE allows quantifying the energy cost of physical activity. While applied here to mice, the model should be generally valid across species. Due to the effect of body temperature, we suggest that basal metabolic rate measurements be corrected to a reference body temperature, including in humans. Having an accurate cost of physical activity allows mechanistic dissection of disorders of energy homeostasis, including obesity.
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3
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Jahn M, Seebacher F. Variations in cost of transport and their ecological consequences: a review. J Exp Biol 2022; 225:276242. [PMID: 35942859 DOI: 10.1242/jeb.243646] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Movement is essential in the ecology of most animals, and it typically consumes a large proportion of individual energy budgets. Environmental conditions modulate the energetic cost of movement (cost of transport, COT), and there are pronounced differences in COT between individuals within species and across species. Differences in morphology affect COT, but the physiological mechanisms underlying variation in COT remain unresolved. Candidates include mitochondrial efficiency and the efficiency of muscle contraction-relaxation dynamics. Animals can offset increased COT behaviourally by adjusting movement rate and habitat selection. Here, we review the theory underlying COT and the impact of environmental changes on COT. Increasing temperatures, in particular, increase COT and its variability between individuals. Thermal acclimation and exercise can affect COT, but this is not consistent across taxa. Anthropogenic pollutants can increase COT, although few chemical pollutants have been investigated. Ecologically, COT may modify the allocation of energy to different fitness-related functions, and thereby influence fitness of individuals, and the dynamics of animal groups and communities. Future research should consider the effects of multiple stressors on COT, including a broader range of pollutants, the underlying mechanisms of COT and experimental quantifications of potential COT-induced allocation trade-offs.
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Affiliation(s)
- Miki Jahn
- School of Life and Environmental Sciences A08, University of Sydney, Sydney, NSW 2006, Australia
| | - Frank Seebacher
- School of Life and Environmental Sciences A08, University of Sydney, Sydney, NSW 2006, Australia
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4
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Wright A, Hall A, Daly T, Fontelonga T, Potter S, Schafer C, Lindsley A, Hung C, Bodamer O, Gussoni E. Lysine methyltransferase 2D regulates muscle fiber size and muscle cell differentiation. FASEB J 2021; 35:e21955. [PMID: 34613626 PMCID: PMC8500524 DOI: 10.1096/fj.202100823r] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2021] [Revised: 08/27/2021] [Accepted: 09/13/2021] [Indexed: 11/16/2022]
Abstract
Kabuki syndrome (KS) is a rare genetic disorder caused primarily by mutations in the histone modifier genes KMT2D and KDM6A. The genes have broad temporal and spatial expression in many organs, resulting in complex phenotypes observed in KS patients. Hypotonia is one of the clinical presentations associated with KS, yet detailed examination of skeletal muscle samples from KS patients has not been reported. We studied the consequences of loss of KMT2D function in both mouse and human muscles. In mice, heterozygous loss of Kmt2d resulted in reduced neuromuscular junction (NMJ) perimeter, decreased muscle cell differentiation in vitro and impaired myofiber regeneration in vivo. Muscle samples from KS patients of different ages showed presence of increased fibrotic tissue interspersed between myofiber fascicles, which was not seen in mouse muscles. Importantly, when Kmt2d‐deficient muscle stem cells were transplanted in vivo in a physiologic non‐Kabuki environment, their differentiation potential is restored to levels undistinguishable from control cells. Thus, the epigenetic changes due to loss of function of KMT2D appear reversible through a change in milieu, opening a potential therapeutic avenue.
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Affiliation(s)
- Alec Wright
- Division of Genetics and Genomics, Boston Children's Hospital, Boston, Massachusetts, USA
| | - Arielle Hall
- Division of Genetics and Genomics, Boston Children's Hospital, Boston, Massachusetts, USA
| | - Tara Daly
- Division of Genetics and Genomics, Boston Children's Hospital, Boston, Massachusetts, USA.,The Roya Kabuki Program, Boston Children's Hospital, Boston, Massachusetts, USA
| | - Tatiana Fontelonga
- Division of Genetics and Genomics, Boston Children's Hospital, Boston, Massachusetts, USA
| | - Sarah Potter
- Division of Allergy and Immunology, Cincinnati Children's Hospital, Cincinnati, Ohio, USA
| | - Caitlin Schafer
- Division of Allergy and Immunology, Cincinnati Children's Hospital, Cincinnati, Ohio, USA
| | - Andrew Lindsley
- Division of Allergy and Immunology, Cincinnati Children's Hospital, Cincinnati, Ohio, USA.,Amgen, Thousand Oaks, California, USA
| | - Christina Hung
- Division of Genetics and Genomics, Boston Children's Hospital, Boston, Massachusetts, USA.,The Roya Kabuki Program, Boston Children's Hospital, Boston, Massachusetts, USA
| | - Olaf Bodamer
- Division of Genetics and Genomics, Boston Children's Hospital, Boston, Massachusetts, USA.,The Roya Kabuki Program, Boston Children's Hospital, Boston, Massachusetts, USA.,Division of Genetics and Genomics, Broad Institute of MIT and Harvard University, Cambridge, Massachusetts, USA
| | - Emanuela Gussoni
- Division of Genetics and Genomics, Boston Children's Hospital, Boston, Massachusetts, USA.,The Roya Kabuki Program, Boston Children's Hospital, Boston, Massachusetts, USA.,The Stem Cell Program, Boston Children's Hospital, Boston, Massachusetts, USA
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5
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Phelps M, Yablonka-Reuveni Z. Female Outperformance in Voluntary Running Persists in Dystrophin-Null and Klotho-Overexpressing Mice. J Neuromuscul Dis 2021; 8:S271-S281. [PMID: 34275905 DOI: 10.3233/jnd-210703] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
BACKGROUND Duchenne muscular dystrophy is a degenerative muscle disease that results from impairment of the dystrophin gene. The disease causes progressive loss in muscle mass and function. OBJECTIVE The anti-aging protein, α-klotho, has been implicated in the regulation of muscle regeneration. We previously discovered that mice harboring reduced α-klotho levels exhibited a decline in muscle strength and running endurance. METHOD To investigate the ability of α-klotho to improve overall endurance in a dystrophin null murine model, we examined the voluntary wheel running performance of dystrophin-null, mdx4cv mice overexpressing an α-klotho transgene. RESULTS As expected, compared to wild type, both male and female dystrophic mice exhibited reduced running ability that was characterized by shorter running duration and longer periods of rest between cycles of activity. While our results did not detect an improvement in running performance with α-klotho overexpression, we identified distinct differences in the running patterns between females and males from all mouse strains analyzed (i.e., mdx4cv, mdx4cv overexpressing α-klotho, α-klotho overexpressing, α-klotho hypomorph, and wild type). For all strains, male mice displayed significantly reduced voluntary running ability compared to females. Further analysis of the mdx4cv strains demonstrated that male mice ran for shorter lengths of time and took longer breaks. However, we did not identify gender-associated differences in the actual speed at which mdx4cv mice ran. CONCLUSION Our data suggest key differences in the running capabilities of female and male mice, which are of particular relevance to studies of dystrophin-null mice.
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Affiliation(s)
- Michael Phelps
- Department of Animal Sciences, Washington State University, Pullman, WA, USA
| | - Zipora Yablonka-Reuveni
- Department of Biological Structure, University of Washington School of Medicine, Seattle, WA, USA
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6
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Schmill MP, Cadney MD, Thompson Z, Hiramatsu L, Albuquerque RL, McNamara MP, Castro AA, Kay JC, Buenaventura DG, Ramirez JL, Rhodes JS, Garland T. Conditioned place preference for cocaine and methylphenidate in female mice from lines selectively bred for high voluntary wheel-running behavior. GENES BRAIN AND BEHAVIOR 2020; 20:e12700. [PMID: 32909333 DOI: 10.1111/gbb.12700] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Revised: 09/06/2020] [Accepted: 09/07/2020] [Indexed: 12/27/2022]
Abstract
Behavioral addictions can come in many forms, including overeating, gambling and overexercising. All addictions share a common mechanism involving activation of the natural reward circuit and reinforcement learning, but the extent to which motivation for natural and drug rewards share similar neurogenetic mechanisms remains unknown. A unique mouse genetic model in which four replicate lines of female mice were selectively bred (>76 generations) for high voluntary wheel running (High Runner or HR lines) alongside four non-selected control (C) lines were used to test the hypothesis that high motivation for exercise is associated with greater reward for cocaine (20 mg/kg) and methylphenidate (10 mg/kg) using the conditioned place preference (CPP) test. HR mice run ~three times as many revolutions/day as C mice, but the extent to which they have increased motivation for other rewards is unknown. Both HR and C mice displayed significant CPP for cocaine and methylphenidate, but with no statistical difference between linetypes for either drug. Taken together, results suggest that selective breeding for increased voluntary running has modified the reward circuit in the brain in a way that increases motivation for running without affecting cocaine or methylphenidate reward.
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Affiliation(s)
- Margaret P Schmill
- Neuroscience Graduate Program, University of California, Riverside, California, USA
| | - Marcell D Cadney
- Department of Evolution, Ecology, and Organismal Biology, University of California, Riverside, California, USA
| | - Zoe Thompson
- Neuroscience Graduate Program, University of California, Riverside, California, USA
| | - Layla Hiramatsu
- Department of Evolution, Ecology, and Organismal Biology, University of California, Riverside, California, USA
| | - Ralph L Albuquerque
- Department of Evolution, Ecology, and Organismal Biology, University of California, Riverside, California, USA
| | - Monica P McNamara
- Department of Evolution, Ecology, and Organismal Biology, University of California, Riverside, California, USA
| | - Alberto A Castro
- Department of Evolution, Ecology, and Organismal Biology, University of California, Riverside, California, USA
| | - Jarren C Kay
- Department of Evolution, Ecology, and Organismal Biology, University of California, Riverside, California, USA
| | - Darrius G Buenaventura
- Department of Evolution, Ecology, and Organismal Biology, University of California, Riverside, California, USA
| | - Jocelyn L Ramirez
- Department of Evolution, Ecology, and Organismal Biology, University of California, Riverside, California, USA
| | - Justin S Rhodes
- Beckman Institute for Advanced Science and Technology, Urbana, Illinois, USA.,Center for Nutrition, Learning and Memory, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
| | - Theodore Garland
- Neuroscience Graduate Program, University of California, Riverside, California, USA.,Department of Evolution, Ecology, and Organismal Biology, University of California, Riverside, California, USA
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7
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Swenson S, Blum K, McLaughlin T, Gold MS, Thanos PK. The therapeutic potential of exercise for neuropsychiatric diseases: A review. J Neurol Sci 2020; 412:116763. [PMID: 32305746 DOI: 10.1016/j.jns.2020.116763] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2019] [Revised: 02/14/2020] [Accepted: 02/28/2020] [Indexed: 02/06/2023]
Abstract
Exercise is known to have a myriad of health benefits. There is much to be learned from the effects of exercise and its potential for prevention, attenuation and treatment of multiple neuropsychiatric diseases and behavioral disorders. Furthermore, recent data and research on exercise benefits with respect to major health crises, such as, that of opioid and general substance use disorders, make it very important to better understand and review the mechanisms of exercise and how it could be utilized for effective treatments or adjunct treatments for these diseases. In addition, mechanisms, epigenetics and sex differences are examined and discussed in terms of future research implications.
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Affiliation(s)
- Sabrina Swenson
- Behavioral Neuropharmacology and Neuroimaging Laboratory on Addictions, Clinical Research Institute on Addictions, Department of Pharmacology and Toxicology, Jacobs School of Medicine and Biosciences, State University of New York at Buffalo, Buffalo, NY, USA
| | - Kenneth Blum
- Western Univesity Health Sciences, Graduate College, Pomona, CA, USA
| | | | - Mark S Gold
- Washington University in St. Louis, School of Medicine, St. Louis, MO, USA
| | - Panayotis K Thanos
- Behavioral Neuropharmacology and Neuroimaging Laboratory on Addictions, Clinical Research Institute on Addictions, Department of Pharmacology and Toxicology, Jacobs School of Medicine and Biosciences, State University of New York at Buffalo, Buffalo, NY, USA; Department of Psychology, State University of New York at Buffalo, Buffalo, NY, USA.
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8
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Rhoads TW, Clark JP, Gustafson GE, Miller KN, Conklin MW, DeMuth TM, Berres ME, Eliceiri KW, Vaughan LK, Lary CW, Beasley TM, Colman RJ, Anderson RM. Molecular and Functional Networks Linked to Sarcopenia Prevention by Caloric Restriction in Rhesus Monkeys. Cell Syst 2020; 10:156-168.e5. [PMID: 31982367 PMCID: PMC7047532 DOI: 10.1016/j.cels.2019.12.002] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2019] [Revised: 08/03/2019] [Accepted: 12/11/2019] [Indexed: 12/13/2022]
Abstract
Caloric restriction (CR) improves survival in nonhuman primates and delays the onset of age-related morbidities including sarcopenia, which is characterized by the age-related loss of muscle mass and function. A shift in metabolism anticipates the onset of muscle-aging phenotypes in nonhuman primates, suggesting a potential role for metabolism in the protective effects of CR. Here, we show that CR induced profound changes in muscle composition and the cellular metabolic environment. Bioinformatic analysis linked these adaptations to proteostasis, RNA processing, and lipid synthetic pathways. At the tissue level, CR maintained contractile content and attenuated age-related metabolic shifts among individual fiber types with higher mitochondrial activity, altered redox metabolism, and smaller lipid droplet size. Biometric and metabolic rate data confirm preserved metabolic efficiency in CR animals that correlated with the attenuation of age-related muscle mass and physical activity. These data suggest that CR-induced reprogramming of metabolism plays a role in delayed aging of skeletal muscle in rhesus monkeys.
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Affiliation(s)
- Timothy W Rhoads
- Department of Medicine, University of Wisconsin-Madison, Madison, WI 53705, USA
| | - Josef P Clark
- Department of Medicine, University of Wisconsin-Madison, Madison, WI 53705, USA
| | - Grace E Gustafson
- Department of Medicine, University of Wisconsin-Madison, Madison, WI 53705, USA
| | - Karl N Miller
- Department of Medicine, University of Wisconsin-Madison, Madison, WI 53705, USA
| | - Matthew W Conklin
- Department of Cell and Regenerative Biology, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Tyler M DeMuth
- Department of Medicine, University of Wisconsin-Madison, Madison, WI 53705, USA
| | - Mark E Berres
- Biotechnolgoy Center, University of Wisconsin-Madison, Madison, WI 53705, USA
| | - Kevin W Eliceiri
- Laboratory for Optical and Computational Instrumentation, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Laura K Vaughan
- Department of Biostatistics, University of Alabama-Birmingham, Birmingham, AL 35294, USA
| | - Christine W Lary
- Department of Biostatistics, University of Alabama-Birmingham, Birmingham, AL 35294, USA
| | - T Mark Beasley
- Department of Biostatistics, University of Alabama-Birmingham, Birmingham, AL 35294, USA; Geriatric Research Education and Clinical Center, Birmingham/Atlanta Veterans Administration Hospital, Birmingham, AL 35297, USA
| | - Ricki J Colman
- Department of Cell and Regenerative Biology, University of Wisconsin-Madison, Madison, WI 53706, USA; Wisconsin National Primate Research Center, University of Wisconsin-Madison, Madison, WI 53715, USA
| | - Rozalyn M Anderson
- Department of Medicine, University of Wisconsin-Madison, Madison, WI 53705, USA; Geriatric Research Education and Clinical Center, William S. Middleton Memorial Veterans Hospital, Madison, WI 53705, USA.
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9
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Yamada Y, Kemnitz JW, Weindruch R, Anderson RM, Schoeller DA, Colman RJ. Caloric Restriction and Healthy Life Span: Frail Phenotype of Nonhuman Primates in the Wisconsin National Primate Research Center Caloric Restriction Study. J Gerontol A Biol Sci Med Sci 2019; 73:273-278. [PMID: 28398464 DOI: 10.1093/gerona/glx059] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2017] [Accepted: 03/21/2017] [Indexed: 01/23/2023] Open
Abstract
Calorie restriction without malnutrition increases longevity and delays the onset of age-associated disorders in multiple species. Recently, greater emphasis has been placed on healthy life span and preventing frailty than on longevity. Here, we show the beneficial effect of long-term calorie restriction on frailty in later life in a nonhuman primate. Frail phenotypes were evaluated using metabolic and physical activity data and defined using the Fried index. Shrinking was defined as unintentional weight loss of greater than 5% of body weight. Weakness was indicated by decline in high intensity spontaneous physical activity. Poor endurance or exhaustion was indicated by a reduction in energy efficiency of movements. Slowness was indicated by physical activity counts in the morning. Low physical activity level was measured by total energy expenditure using doubly labeled water divided by sleeping metabolic rate. Weakness, poor endurance, slowness, and low physical activity level were significantly higher in control compared with calorie restriction (p < .05) as was total incidence of frailty (p < .001). In conclusion, we established a novel set of measurable criteria of frailty in nonhuman primates, and using these criteria, showed that calorie restriction reduces the incidence of frailty and increases healthy life span in nonhuman primates.
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Affiliation(s)
- Yosuke Yamada
- Department of Nutritional Science, National Institutes of Biomedical Health, Innovation, and Nutrition, Tokyo, Japan
| | - Joseph W Kemnitz
- Department of Cell and Regenerative Biology, University of Wisconsin-Madison.,Wisconsin National Primate Research Center, Madison
| | | | - Rozalyn M Anderson
- Department of Medicine, University of Wisconsin-Madison.,GRECC, William S Middleton Memorial Veterans Hospital, Madison, Wisconsin
| | | | - Ricki J Colman
- Department of Cell and Regenerative Biology, University of Wisconsin-Madison.,Wisconsin National Primate Research Center, Madison
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10
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Gonzalez NC, Kuwahira I. Systemic Oxygen Transport with Rest, Exercise, and Hypoxia: A Comparison of Humans, Rats, and Mice. Compr Physiol 2018; 8:1537-1573. [PMID: 30215861 DOI: 10.1002/cphy.c170051] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The objective of this article is to compare and contrast the known characteristics of the systemic O2 transport of humans, rats, and mice at rest and during exercise in normoxia and hypoxia. This analysis should help understand when rodent O2 transport findings can-and cannot-be applied to human responses to similar conditions. The O2 -transport system was analyzed as composed of four linked conductances: ventilation, alveolo-capillary diffusion, circulatory convection, and tissue capillary-cell diffusion. While the mechanisms of O2 transport are similar in the three species, the quantitative differences are naturally large. There are abundant data on total O2 consumption and on ventilatory and pulmonary diffusive conductances under resting conditions in the three species; however, there is much less available information on pulmonary gas exchange, circulatory O2 convection, and tissue O2 diffusion in mice. The scarcity of data largely derives from the difficulty of obtaining blood samples in these small animals and highlights the need for additional research in this area. In spite of the large quantitative differences in absolute and mass-specific O2 flux, available evidence indicates that resting alveolar and arterial and venous blood PO2 values under normoxia are similar in the three species. Additionally, at least in rats, alveolar and arterial blood PO2 under hypoxia and exercise remain closer to the resting values than those observed in humans. This is achieved by a greater ventilatory response, coupled with a closer value of arterial to alveolar PO2 , suggesting a greater efficacy of gas exchange in the rats. © 2018 American Physiological Society. Compr Physiol 8:1537-1573, 2018.
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Affiliation(s)
- Norberto C Gonzalez
- Department of Molecular and Integrative Physiology, University of Kansas Medical Center, Kansas City, Kansas, USA
| | - Ichiro Kuwahira
- Department of Pulmonary Medicine, Tokai University School of Medicine, Tokai University Tokyo Hospital, Tokyo, Japan
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11
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The exercise sex gap and the impact of the estrous cycle on exercise performance in mice. Sci Rep 2018; 8:10742. [PMID: 30013130 PMCID: PMC6048134 DOI: 10.1038/s41598-018-29050-0] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2018] [Accepted: 06/21/2018] [Indexed: 01/08/2023] Open
Abstract
Exercise physiology is different in males and females. Females are poorly studied due to the complexity of the estrous cycle and this bias has created an exercise sex gap. Here, we evaluated the impact of sexual dimorphism and of the estrous cycle on muscle strength and running power of C57BL/6 mice. Like men, male mice were stronger and more powerful than females. Exercise-induced increase of O2 consumption (\documentclass[12pt]{minimal}
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\begin{document}$$\dot{{\bf{V}}}$$\end{document}V˙O2) and CO2 production (\documentclass[12pt]{minimal}
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\begin{document}$$\dot{{\bf{V}}}$$\end{document}V˙CO2) were equal between sexes, indicating that running economy was higher in males. Thermoregulation was also more efficient in males. In females, proestrus increased exercise \documentclass[12pt]{minimal}
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\begin{document}$$\dot{{\bf{V}}}$$\end{document}V˙O2 and \documentclass[12pt]{minimal}
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\begin{document}$$\dot{{\bf{V}}}$$\end{document}V˙CO2 at low running speeds (30–35% female \documentclass[12pt]{minimal}
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\begin{document}$$\dot{{\bf{V}}}$$\end{document}V˙O2max) and estrus worsened thermoregulation. These differences translated into different absolute and relative workloads on the treadmill, even at equal submaximal \documentclass[12pt]{minimal}
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\begin{document}$$\dot{{\bf{V}}}$$\end{document}V˙O2 and belt speeds. In summary, our results demonstrate the better muscle strength, running power and economy, and exercise-induced thermoregulation of males compared to females. Proestrus and estrus still undermined the running economy and exercise-induced thermoregulation of females, respectively. These results demonstrate an important exercise sex gap in mice.
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12
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Biro PA, Garland T, Beckmann C, Ujvari B, Thomas F, Post JR. Metabolic Scope as a Proximate Constraint on Individual Behavioral Variation: Effects on Personality, Plasticity, and Predictability. Am Nat 2018; 192:142-154. [PMID: 30016170 DOI: 10.1086/697963] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
Behavioral ecologists have hypothesized that among-individual differences in resting metabolic rate (RMR) may predict consistent individual differences in mean values for costly behaviors or for behaviors that affect energy intake rate. This hypothesis has empirical support and presently attracts considerable attention, but, notably, it does not provide predictions for individual differences in (a) behavioral plasticity or (b) unexplained variation (residual variation from mean individual behavior, here termed predictability). We outline how consideration of aerobic maximum metabolic rate (MMR) and particularly aerobic scope (= MMR - RMR) can be used to simultaneously make predictions about mean and among- and within-individual variation in behavior. We predict that while RMR should be proportional to an individual's mean level of sustained behavioral activity (one aspect of its personality), individuals with greater aerobic scope will also have greater scope to express behavioral plasticity and/or greater unpredictability in behavior (=greater residual variation). As a first step toward testing these predictions, we analyze existing activity data from selectively bred lines of mice that differ in both daily activity and aerobic scope. We find that replicate high-scope mice are more active on average and show greater among-individual variation in activity, greater among-individual variation in plasticity, and greater unpredictability. These data provide some tentative first support for our hypothesis, suggesting that further research on this topic would be valuable.
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13
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Ishihara K, Taniguchi H. Fat max as an index of aerobic exercise performance in mice during uphill running. PLoS One 2018; 13:e0193470. [PMID: 29474428 PMCID: PMC5825145 DOI: 10.1371/journal.pone.0193470] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2017] [Accepted: 02/12/2018] [Indexed: 11/22/2022] Open
Abstract
Endurance exercise performance has been used as a representative index in experimental animal models in the field of health sciences, exercise physiology, comparative physiology, food function or nutritional physiology. The objective of the present study was to evaluate the effectiveness of Fatmax (the exercise intensity that elicits maximal fat oxidation) as an additional index of endurance exercise performance that can be measured during running at submaximal exercise intensity in mice. We measured both Fatmax and Vo2 peak of trained ICR mice that voluntary exercised for 8 weeks and compared them with a sedentary group of mice at multiple inclinations of 20, 30, 40, and 50° on a treadmill. The Vo2 at Fatmax of the training group was significantly higher than that of the sedentary group at inclinations of 30 and 40° (P < 0.001). The running speed at Fatmax of the training group was significantly higher than that of the sedentary group at inclinations of 20, 30, and 40° (P < 0.05). Blood lactate levels sharply increased in the sedentary group (7.33 ± 2.58 mM) compared to the training group (3.13 ± 1.00 mM, P < 0.01) when running speeds exceeded the Fatmax of sedentary mice. Vo2 at Fatmax significantly correlated to Vo2 peak, running time to fatigue, and lactic acid level during running (P < 0.05) although the reproducibility of Vo2 peak was higher than that of Vo2 at Fatmax. In conclusion, Fatmax can be used as a functional assessment of the endurance exercise performance of mice during submaximal exercise intensity.
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Affiliation(s)
- Kengo Ishihara
- Faculty of Agriculture, Ryukoku University, Shiga, Japan
- * E-mail:
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14
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The reinforcing value and liking of resistance training and aerobic exercise as predictors of adult's physical activity. Physiol Behav 2017; 179:284-289. [DOI: 10.1016/j.physbeh.2017.06.016] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2017] [Revised: 06/11/2017] [Accepted: 06/25/2017] [Indexed: 12/12/2022]
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15
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Claghorn GC, Thompson Z, Kay JC, Ordonez G, Hampton TG, Garland T. Selective Breeding and Short-Term Access to a Running Wheel Alter Stride Characteristics in House Mice. Physiol Biochem Zool 2017. [DOI: 10.1086/692909] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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16
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Morris JS, Ruff JS, Potts WK, Carrier DR. A disparity between locomotor economy and territory-holding ability in male house mice. J Exp Biol 2017; 220:2521-2528. [PMID: 28468871 PMCID: PMC5536892 DOI: 10.1242/jeb.154823] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2016] [Accepted: 04/25/2017] [Indexed: 01/01/2023]
Abstract
Both economical locomotion and physical fighting are important performance traits to many species because of their direct influence on components of Darwinian fitness. Locomotion represents a substantial portion of the total daily energy budget of many animals. Fighting performance often determines individual reproductive fitness through the means of resource control, social dominance and access to mates. However, phenotypic traits that improve either locomotor economy or fighting ability may diminish performance in the other. Here, we tested for a predicted disparity between locomotor economy and competitive ability in wild-derived house mice (Mus musculus). We used 8 week social competition trials in semi-natural enclosures to directly measure male competitive ability through territorial control and female occupancy within territories. We also measured oxygen consumption during locomotion for each mouse using running trials in an enclosed treadmill and open-flow respirometry. Our results show that territory-holding males have higher absolute and mass-specific oxygen consumption when running (i.e. reduced locomotor economy) compared with males that do not control territories. This relationship was present both before and after 8 week competition trials in semi-natural enclosures. This disparity between physical competitive ability and economical locomotion may impose viability costs on males in species for which competition over mates is common and may constrain the evolution of behavioral and phenotypic diversity, particularly in natural settings with environmental and resource variability.
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Affiliation(s)
- Jeremy S Morris
- Department of Biology, University of Utah, Salt Lake City, UT 84112, USA
| | - James S Ruff
- Department of Biology, University of Utah, Salt Lake City, UT 84112, USA
| | - Wayne K Potts
- Department of Biology, University of Utah, Salt Lake City, UT 84112, USA
| | - David R Carrier
- Department of Biology, University of Utah, Salt Lake City, UT 84112, USA
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17
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Kelly SA, Gomes FR, Kolb EM, Malisch JL, Garland T. Effects of activity, genetic selection, and their interaction on muscle metabolic capacities and organ masses in mice. J Exp Biol 2017; 220:1038-1047. [DOI: 10.1242/jeb.148759] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2016] [Accepted: 12/26/2016] [Indexed: 12/17/2022]
Abstract
Chronic voluntary exercise elevates total daily energy expenditure (DEE) and food consumption, potentially resulting in organ compensation supporting nutrient extraction/utilization. Additionally, species with naturally higher DEE often have larger processing organs, which may represent genetic differences and/or phenotypic plasticity. We tested for possible adaptive changes in organ masses of 4 replicate lines of house mice selected (37 generations) for high running (HR lines) compared with 4 non-selected control (C) lines. Females were housed with or without wheel access for 13-14 weeks beginning at 53-60 days of age. In addition to organ compensation, chronic activity may also require an elevated aerobic capacity. Therefore, we also measured hematocrit and both citrate synthase activity and myoglobin concentration in heart and gastrocnemius. Both selection (HR vs. C) and activity (wheels vs. no wheels) significantly affected morphological and biochemical traits. For example, with body mass as a covariate, mice from HR lines had significantly higher hematocrit and larger ventricles, with more myoglobin. Wheel access lengthened the small intestine, increased relative ventricle and kidney size, and increased skeletal muscle citrate synthase activity and myoglobin concentration. As compared with C lines, HR mice had greater training effects for ventricle mass, hematocrit, large intestine length, and gastrocnemius citrate synthase activity. For ventricle and gastrocnemius citrate synthase activity, the greater training was explainable quantitatively as a result of greater wheel running (i.e., “more pain, more gain”). For hematocrit and large intestine length, differences were not related to amount of wheel running and instead indicate inherently greater adaptive plasticity in HR lines.
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Affiliation(s)
- Scott A. Kelly
- Department of Biology, University of California, Riverside, Riverside, California 92521, USA
- Department of Zoology, Ohio Wesleyan University, Delaware, Ohio 43015, USA
| | - Fernando R. Gomes
- Department of Biology, University of California, Riverside, Riverside, California 92521, USA
- Departamento de Fisiologia, Instituto de Biociências, Universidade de São Paulo, Rua do Matão. Trav.14, 101, 05508-900, São Paulo, SP, Brazil
| | - Erik M. Kolb
- Department of Biology, University of California, Riverside, Riverside, California 92521, USA
- Department of Biological Sciences, University of Southern California, Los Angeles, California 90089, USA
| | - Jessica L. Malisch
- Department of Biology, University of California, Riverside, Riverside, California 92521, USA
- Department of Biology, St. Mary's College of Maryland, St. Mary's City, Maryland 20686, USA
| | - Theodore Garland
- Department of Biology, University of California, Riverside, Riverside, California 92521, USA
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Claghorn GC, Thompson Z, Wi K, Van L, Garland T. Caffeine stimulates voluntary wheel running in mice without increasing aerobic capacity. Physiol Behav 2016; 170:133-140. [PMID: 28039074 DOI: 10.1016/j.physbeh.2016.12.031] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2016] [Revised: 12/23/2016] [Accepted: 12/23/2016] [Indexed: 12/23/2022]
Abstract
The "energy drink" Red Bull and the "sports drink" Gatorade are often marketed to athletes, with claims that they cause performance gains. However, both are high in sugars, and also consumed by non-athletes. Few studies have addressed the effects of these drinks or their biologically active components in rodent exercise models. We used three experiments to test effects on both voluntary exercise behavior and maximal aerobic capacity in lines of mice known to differ in "athletic" traits. Mice from four replicate High Runner (HR) lines have been selectively bred for voluntary running on wheels, and run approximately three times as many revolutions per day as do mice from four non-selected Control (C) lines. HR mice also have higher endurance and maximal oxygen consumption (VO2max) during forced treadmill exercise. In Experiment 1, we tested the hypothesis that Gatorade or Red Bull might cause or allow mice to increase their voluntary wheel running. On days 5 and 6 of 6days of wheel access, as is used to select breeders, HR mice ran 3.3-fold more than C, and females ran 1.2-fold more than males, with no linetype by sex interaction. On day 7, mice were administered Gatorade, Red Bull or tap water. During the subsequent 19-hour period, Gatorade had no statistical effect on running, but Red Bull significantly increased distance run by both sexes and in both HR and C lines. The increase in distance run caused by Red Bull was attributable to time spent running, not an increase in mean (or maximum) speed. As previous studies have found that sucrose alone does not generally increase wheel running, we tested two other active ingredients in Red Bull, caffeine and taurine, in Experiment 2. With a similar testing protocol, caffeine alone and caffeine+taurine increased running by about half the magnitude of Red Bull. In Experiment 3, we tested the hypothesis that Red Bull or caffeine alone can increase physiological performance ability during aerobic exercise, measured as VO2max. In a repeated-measures design spanning 6days, females were housed with water bottles containing Red Bull, caffeine or water in a randomized order, and tested for VO2max twice while receiving each fluid (6 total trials). Neither Red Bull nor caffeine significantly affected either VO2max or a measure of trial cooperativity (rated on a scale of 1-5), but both treatments significantly reduced tiredness (rated on a scale of 1-3) scored at the end of trials for both HR and C lines. Taken together, our results suggest that caffeine increases voluntary exercise levels of mice by delaying fatigue, rather than increasing aerobic capacity.
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Affiliation(s)
- Gerald C Claghorn
- Department of Biology, University of California, Riverside, CA 92521, USA
| | - Zoe Thompson
- Department of Biology, University of California, Riverside, CA 92521, USA
| | - Kristianna Wi
- Department of Biology, University of California, Riverside, CA 92521, USA
| | - Lindsay Van
- Department of Biology, University of California, Riverside, CA 92521, USA
| | - Theodore Garland
- Department of Biology, University of California, Riverside, CA 92521, USA.
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White CR, Alton LA, Crispin TS, Halsey LG. Phylogenetic comparisons of pedestrian locomotion costs: confirmations and new insights. Ecol Evol 2016; 6:6712-6720. [PMID: 27777742 PMCID: PMC5058540 DOI: 10.1002/ece3.2267] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2016] [Revised: 05/24/2016] [Accepted: 05/25/2016] [Indexed: 11/11/2022] Open
Abstract
The energetic costs for animals to locomote on land influence many aspects of their ecology. Size accounts for much of the among-species variation in terrestrial transport costs, but species of similar body size can still exhibit severalfold differences in energy expenditure. We compiled measurements of the (mass-specific) minimum cost of pedestrian transport (COTmin, mL/kg/m) for 201 species - by far the largest sample to date - and used phylogenetically informed comparative analyses to investigate possible eco-evolutionary differences in COTmin between various groupings of those species. We investigated number of legs, ectothermy and endothermy, waddling, and nocturnality specifically in lizards. Thus, our study primarily revisited previous theories about variations in COTmin between species, testing them with much more robust analyses. Having accounted for mass, while residual COTmin did not differ between bipedal and other species, specifically waddling bipeds were found to have relatively high COTmin. Furthermore, nocturnal lizards have relatively low COTmin although temperature does not appear to affect COTmin in ectotherms. Previous studies examining across-species variation in COTmin from a biomechanical perspective show that the differences between waddling birds and nonwaddling species, and between nocturnal lizards and other ecotherms, are likely to be attributable to differences in ground reaction forces, posture, and effective limb length.
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Affiliation(s)
- Craig R White
- Centre for Geometric Biology School of Biological Sciences Monash University Melbourne Victoria 3800 Australia; School of Biological Sciences The University of Queensland Brisbane Queensland 4072 Australia
| | - Lesley A Alton
- Centre for Geometric Biology School of Biological Sciences Monash University Melbourne Victoria 3800 Australia; School of Biological Sciences The University of Queensland Brisbane Queensland 4072 Australia
| | - Taryn S Crispin
- School of Biological Sciences The University of Queensland Brisbane Queensland 4072 Australia
| | - Lewis G Halsey
- Department of Life Sciences Centre for Research in Ecology University of Roehampton Holybourne Avenue London SW15 4JD UK
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20
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Wallace IJ, Garland T. Mobility as an emergent property of biological organization: Insights from experimental evolution. Evol Anthropol 2016; 25:98-104. [DOI: 10.1002/evan.21481] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Downs CJ, Brown JL, Wone BWM, Donovan ER, Hayes JP. Speeding up Growth: Selection for Mass-Independent Maximal Metabolic Rate Alters Growth Rates. Am Nat 2016; 187:295-307. [PMID: 26913943 DOI: 10.1086/684837] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Investigations into relationships between life-history traits, such as growth rate and energy metabolism, typically focus on basal metabolic rate (BMR). In contrast, investigators rarely examine maximal metabolic rate (MMR) as a relevant metric of energy metabolism, even though it indicates the maximal capacity to metabolize energy aerobically, and hence it might also be important in trade-offs. We studied the relationship between energy metabolism and growth in mice (Mus musculus domesticus Linnaeus) selected for high mass-independent metabolic rates. Selection for high mass-independent MMR increased maximal growth rate, increased body mass at 20 weeks of age, and generally altered growth patterns in both male and female mice. In contrast, there was little evidence that the correlated response in mass-adjusted BMR altered growth patterns. The relationship between mass-adjusted MMR and growth rate indicates that MMR is an important mediator of life histories. Studies investigating associations between energy metabolism and life histories should consider MMR because it is potentially as important in understanding life history as BMR.
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22
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Sex differences in drug addiction and response to exercise intervention: From human to animal studies. Front Neuroendocrinol 2016; 40:24-41. [PMID: 26182835 PMCID: PMC4712120 DOI: 10.1016/j.yfrne.2015.07.001] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/03/2014] [Revised: 06/08/2015] [Accepted: 07/10/2015] [Indexed: 02/08/2023]
Abstract
Accumulated research supports the idea that exercise could be an option of potential prevention and treatment for drug addiction. During the past few years, there has been increased interest in investigating of sex differences in exercise and drug addiction. This demonstrates that sex-specific exercise intervention strategies may be important for preventing and treating drug addiction in men and women. However, little is known about how and why sex differences are found when doing exercise-induced interventions for drug addiction. In this review, we included both animal and human that pulled subjects from a varied age demographic, as well as neurobiological mechanisms that may highlight the sex-related differences in these potential to assess the impact of sex-specific roles in drug addiction and exercise therapies.
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23
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Homa LD, Burger LL, Cuttitta AJ, Michele DE, Moenter SM. Voluntary Exercise Improves Estrous Cyclicity in Prenatally Androgenized Female Mice Despite Programming Decreased Voluntary Exercise: Implications for Polycystic Ovary Syndrome (PCOS). Endocrinology 2015; 156:4618-28. [PMID: 26360506 PMCID: PMC4655213 DOI: 10.1210/en.2015-1593] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Prenatal androgen (PNA) exposure in mice produces a phenotype resembling lean polycystic ovary syndrome. We studied effects of voluntary exercise on metabolic and reproductive parameters in PNA vs vehicle (VEH)-treated mice. Mice (8 wk of age) were housed individually and estrous cycles monitored. At 10 weeks of age, mice were divided into groups (PNA, PNA-run, VEH, VEH-run, n = 8-9/group); those in the running groups received wheels allowing voluntary running. Unexpectedly, PNA mice ran less distance than VEH mice; ovariectomy eliminated this difference. In ovary-intact mice, there was no difference in glucose tolerance, lower limb muscle fiber types, weight, or body composition among groups after 16 weeks of running, although some mitochondrial proteins were mildly up-regulated by exercise in PNA mice. Before running, estrous cycles in PNA mice were disrupted with most days in diestrus. There was no change in cycles during weeks 1-6 of running (10-15 wk of age). In contrast, from weeks 11 to 16 of running, cycles in PNA mice improved with more days in proestrus and estrus and fewer in diestrus. PNA programs reduced voluntary exercise, perhaps mediated in part by ovarian secretions. Exercise without weight loss improved estrous cycles, which if translated could be important for fertility in and counseling of lean women with polycystic ovary syndrome.
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Affiliation(s)
- Lori D Homa
- Departments of Obstetrics and Gynecology (L.D.H., S.M.M.), Molecular and Integrative Physiology (L.L.B., A.J.C., D.E.M., S.M.M.), and Internal Medicine (D.E.M., S.M.M.), University of Michigan, Ann Arbor, Michigan 48109-5622
| | - Laura L Burger
- Departments of Obstetrics and Gynecology (L.D.H., S.M.M.), Molecular and Integrative Physiology (L.L.B., A.J.C., D.E.M., S.M.M.), and Internal Medicine (D.E.M., S.M.M.), University of Michigan, Ann Arbor, Michigan 48109-5622
| | - Ashley J Cuttitta
- Departments of Obstetrics and Gynecology (L.D.H., S.M.M.), Molecular and Integrative Physiology (L.L.B., A.J.C., D.E.M., S.M.M.), and Internal Medicine (D.E.M., S.M.M.), University of Michigan, Ann Arbor, Michigan 48109-5622
| | - Daniel E Michele
- Departments of Obstetrics and Gynecology (L.D.H., S.M.M.), Molecular and Integrative Physiology (L.L.B., A.J.C., D.E.M., S.M.M.), and Internal Medicine (D.E.M., S.M.M.), University of Michigan, Ann Arbor, Michigan 48109-5622
| | - Suzanne M Moenter
- Departments of Obstetrics and Gynecology (L.D.H., S.M.M.), Molecular and Integrative Physiology (L.L.B., A.J.C., D.E.M., S.M.M.), and Internal Medicine (D.E.M., S.M.M.), University of Michigan, Ann Arbor, Michigan 48109-5622
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24
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Collins PM, Green JA, Warwick‐Evans V, Dodd S, Shaw PJA, Arnould JPY, Halsey LG. Interpreting behaviors from accelerometry: a method combining simplicity and objectivity. Ecol Evol 2015; 5:4642-54. [PMID: 26668729 PMCID: PMC4670056 DOI: 10.1002/ece3.1660] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2015] [Revised: 07/21/2015] [Accepted: 07/22/2015] [Indexed: 11/30/2022] Open
Abstract
Quantifying the behavior of motile, free-ranging animals is difficult. The accelerometry technique offers a method for recording behaviors but interpretation of the data is not straightforward. To date, analysis of such data has either involved subjective, study-specific assignments of behavior to acceleration data or the use of complex analyses based on machine learning. Here, we present a method for automatically classifying acceleration data to represent discrete, coarse-scale behaviors. The method centers on examining the shape of histograms of basic metrics readily derived from acceleration data to objectively determine threshold values by which to separate behaviors. Through application of this method to data collected on two distinct species with greatly differing behavioral repertoires, kittiwakes, and humans, the accuracy of this approach is demonstrated to be very high, comparable to that reported for other automated approaches already published. The method presented offers an alternative to existing methods as it uses biologically grounded arguments to distinguish behaviors, it is objective in determining values by which to separate these behaviors, and it is simple to implement, thus making it potentially widely applicable. The R script coding the method is provided.
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Affiliation(s)
- Philip M. Collins
- School of Life SciencesUniversity of RoehamptonHolybourne AvenueLondonSW15 4JDUnited Kingdom
| | - Jonathan A. Green
- School of Environmental SciencesUniversity of LiverpoolLiverpoolL69 3GPUnited Kingdom
| | | | - Stephen Dodd
- Royal Society for the Protection of BirdsNorth Wales OfficeBangorLL57 4FDUnited Kingdom
| | - Peter J. A. Shaw
- School of Life SciencesUniversity of RoehamptonHolybourne AvenueLondonSW15 4JDUnited Kingdom
| | - John P. Y. Arnould
- School of Life and Environmental SciencesDeakin UniversityMelbourneVictoria3125Australia
| | - Lewis G. Halsey
- School of Life SciencesUniversity of RoehamptonHolybourne AvenueLondonSW15 4JDUnited Kingdom
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Halsey LG, Matthews PGD, Rezende EL, Chauvaud L, Robson AA. The interactions between temperature and activity levels in driving metabolic rate: theory, with empirical validation from contrasting ectotherms. Oecologia 2015; 177:1117-29. [PMID: 25575673 DOI: 10.1007/s00442-014-3190-5] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2014] [Accepted: 12/10/2014] [Indexed: 11/27/2022]
Abstract
The rate of change in resting metabolic rate (RMR) as a result of a temperature increase of 10 °C is termed the temperature coefficient (Q10), which is often used to predict how an organism's total MR will change with temperature. However, this method neglects a potentially key component of MR; changes in activity level (and thus activity MR; AMR) with temperature may significantly alter the relationship between MR and temperature. The present study seeks to describe how thermal effects on total MR estimated from RMR-temperature measurements can be misleading when the contribution of activity to total MR is neglected. A simple conceptual framework illustrates that since the relationship between activity levels and temperature can be different to the relationship between RMR and temperature, a consistent relationship between RMR and total MR cannot be assumed. Thus the thermal effect on total MR can be considerably different to the thermal effect on RMR. Simultaneously measured MR and activity from three ectotherm species with differing behavioural and physiological ecologies were used to empirically examine how changes in temperature drive changes in RMR, activity level, AMR and the Q10 of MR. These species exhibited varied activity- and MR-temperature relationships, underlining the difficulty in predicting thermal influences on activity levels and total MR. These data support a model showing that thermal effects on total MR will deviate from predictions based solely on RMR; this deviation will depend upon the difference in Q10 between AMR and RMR, and the relative contribution of AMR to total MR. To develop mechanistic, predictive models for species' metabolic responses to temperature changes, empirical information about the relationships between activity levels, MR and temperature, such as reported here, is required. This will supersede predictions based on RMR alone.
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Affiliation(s)
- L G Halsey
- Department of Life Sciences, Centre for Research in Ecology, University of Roehampton, Holybourne Avenue, London, SW15 4JD, UK,
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26
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Fonseca I, Passos R, Araujo F, Lima M, Lacerda D, Pires W, Soares D, Young R, Rodrigues L. Exercising for food: bringing the laboratory closer to nature. J Exp Biol 2014; 217:3274-82. [DOI: 10.1242/jeb.108191] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Abstract
Traditionally, exercise physiology experiments have borne little resemblance to how animals express physical activity in the wild. In this experiment, 15 adult male rats were divided into three equal-sized groups: exercise contingent (CON), non-exercise contingent (NON) and sedentary (SED). The CON group was placed in a cage with a running wheel, where the acquisition of food was contingent upon the distance run. Every three days the distance required to run to maintain food intake at free feeding levels was increased by 90% in comparison to the previous 3 days. The NON group were housed identically to the CON group, but food acquisition was not dependent upon running in the wheel. Finally, the SED group were kept in small cages with no opportunity to perform exercise. A two-way ANOVA with repeated measures was used to determine significant differences in responses between the experimental phases and treatment groups and ANCOVA to analyse growth and tissue mass variables with body length and body mass used separately as covariates. A post hoc Tukey's test was used to indicate significant differences. A Pearson's correlation was used to test the relationship between the distance travelled by the animal and the distance/food ratio. The level of significance was set at p<0.05 for all tests. The CON group showed the hypothesized correlation between distance required to run to obtain food and their mean distance travelled (p<0.001), during 45 days in contingency phase. The CON group showed a decrease in body mass, rather than an increase as shown by NON and SED groups. The CON group had a significantly lower body temperature (p<0.05) and adiposity (p<0.05) when compared to the other two groups for the same body size. The present experimental model based on animals choosing the characteristics of their physical exercise to acquire food (i.e., distance travelled, speed and duration) clearly induced physiological effects (body characteristics and internal temperature), which are useful for investigating relevant topics in exercise physiology such as the link between exercise, food and body weight.
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Affiliation(s)
| | | | | | | | | | | | | | - Robert Young
- UCMG, Brazil; University of Salford, United Kingdom
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27
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Meek TH, Eisenmann JC, Keeney BK, Hannon RM, Dlugosz EM, Garland T. Effects of early-life exposure to Western diet and wheel access on metabolic syndrome profiles in mice bred for high voluntary exercise. GENES BRAIN AND BEHAVIOR 2013; 13:322-32. [PMID: 24256423 DOI: 10.1111/gbb.12098] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/18/2013] [Revised: 08/16/2013] [Accepted: 10/21/2013] [Indexed: 01/24/2023]
Abstract
Experimental studies manipulating diet and exercise have shown varying effects on metabolic syndrome components in both humans and rodents. To examine the potential interactive effects of diet, exercise and genetic background, we studied mice from four replicate lines bred (52 generations) for high voluntary wheel running (HR lines) and four unselected control lines (C). At weaning, animals were housed for 60 days with or without wheels and fed either a standard chow or Western diet (WD, 42% kcal from fat). Four serial (three juvenile and one adult) blood samples were taken to measure fasting total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), triglycerides and glucose. Western diet was obesogenic for all mice, even after accounting for the amount of wheel running and kilojoules consumed. Western diet significantly raised glucose as well as TC and HDL-C concentrations. At the level of individual variation (repeatability), there was a modest correlation (r = 0.3-0.5) of blood lipids over time, which was reduced with wheel access and/or WD. Neither genetic selection history nor wheel access had a statistically significant effect on blood lipids. However, HR and C mice had divergent ontogenetic trajectories for body mass and caloric intake. HR mice also had lower adiposity, an effect that was dependent on wheel access. The environmental factors of diet and wheel access had pronounced effects on body mass, food consumption and fasting glucose concentrations, interacting with each other and/or with genetic strain. These data underscore the importance (and often unpredictable nature) of genotype-by-environment and environment-by-environment interactions when studying body weight regulation.
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Affiliation(s)
- T H Meek
- Department of Biology, University of California, Riverside, Riverside, CA; Present address: Diabetes and Obesity Center of Excellence, University of Washington, Seattle, Seattle, WA, USA
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28
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Kelly SA, Rezende EL, Chappell MA, Gomes FR, Kolb EM, Malisch JL, Rhodes JS, Mitchell GS, Garland T. Exercise training effects on hypoxic and hypercapnic ventilatory responses in mice selected for increased voluntary wheel running. Exp Physiol 2013; 99:403-13. [PMID: 24142456 DOI: 10.1113/expphysiol.2013.076018] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
NEW FINDINGS What is the central question of this study? We used experimental evolution to determine how selective breeding for high voluntary wheel running and exercise training (7-11 weeks) affect ventilatory chemoreflexes of laboratory mice at rest. What is the main finding and its importance? Selective breeding, although significantly affecting some traits, did not systematically alter ventilation across gas concentrations. As with most human studies, our findings support the idea that endurance training attenuates resting ventilation. However, little evidence was found for a correlation between ventilatory chemoreflexes and the amount of individual voluntary wheel running. We conclude that exercise 'training' alters respiratory behaviours, but these changes may not be necessary to achieve high levels of wheel running. Ventilatory control is affected by genetics, the environment and gene-environment and gene-gene interactions. Here, we used an experimental evolution approach to test whether 37 generations of selective breeding for high voluntary wheel running (genetic effects) and/or long-term (7-11 weeks) wheel access (training effects) alter acute respiratory behaviour of mice resting in normoxic, hypoxic and hypercapnic conditions. As the four replicate high-runner (HR) lines run much more than the four non-selected control (C) lines, we also examined whether the amount of exercise among individual mice was a quantitative predictor of ventilatory chemoreflexes at rest. Selective breeding and/or wheel access significantly affected several traits. In normoxia, HR mice tended to have lower mass-adjusted rates of oxygen consumption and carbon dioxide production. Chronic wheel access increased oxygen consumption and carbon dioxide production in both HR and C mice during hypercapnia. Breathing frequency and minute ventilation were significantly reduced by chronic wheel access in both HR and C mice during hypoxia. Selection history, while significantly affecting some traits, did not systematically alter ventilation across all gas concentrations. As with most human studies, our findings support the idea that endurance training (access to wheel running) attenuates resting ventilation. However, little evidence was found for a correlation at the level of the individual variation between ventilatory chemoreflexes and performance (amount of individual voluntary wheel running). We tentatively conclude that exercise 'training' alters respiratory behaviours, but these changes may not be necessary to achieve high levels of wheel running.
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Affiliation(s)
- Scott A Kelly
- * Ohio Wesleyan University, Schimmel/Conrades Science Center #346, 61 S. Sandusky Street, Delaware, OH 43015, USA.
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Guidotti S, Jónás I, Schubert KA, Garland T, Meijer HAJ, Scheurink AJW, van Dijk G. High-saturated fat-sucrose feeding affects lactation energetics in control mice and mice selectively bred for high wheel-running behavior. Am J Physiol Regul Integr Comp Physiol 2013; 305:R1433-40. [PMID: 24089382 DOI: 10.1152/ajpregu.00251.2013] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Feeding a diet high in fat and sucrose (HFS) during pregnancy and lactation is known to increase susceptibility to develop metabolic derangements later in life. A trait for increased behavioral activity may oppose these effects, since this would drain energy from milk produced to be made available to the offspring. To investigate these interactions, we assessed several components of behavioral energetics during lactation in control mice (C) and in mice of two lines selectively bred for high wheel-running activity (S1, S2) subjected to a HFS diet or a low-fat (LF) diet. Energy intake, litter growth, and milk energy output at peak lactation (MEO; assessed by subtracting maternal metabolic rate from energy intake) were elevated in HFS-feeding dams across all lines compared with the LF condition, an effect that was particularly evident in the S dams. This effect was not preceded by improved lactation behaviors assessed between postnatal days 1 and 7 (PND 1-7). In fact, S1 dams had less high-quality nursing, and S2 dams showed poorer pup retrieval than C dams during PND 1-7, and S dams had generally higher levels of physical activity at peak lactation. These data demonstrate that HFS feeding increases MEO underlying increased litter and pup growth, particularly in mice with a trait for increased behavioral physical activity.
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Affiliation(s)
- Stefano Guidotti
- Center for Behavior and Neurosciences (CBN), Unit Neuroendocrinology, University of Groningen, The Netherlands
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Dlugosz EM, Schutz H, Meek TH, Acosta W, Downs CJ, Platzer EG, Chappell MA, Garland T. Immune response to a Trichinella spiralis infection in house mice from lines selectively bred for high voluntary wheel running. ACTA ACUST UNITED AC 2013; 216:4212-21. [PMID: 23948476 DOI: 10.1242/jeb.087361] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Four lines of mice bred for high voluntary wheel running (HR lines) have high baseline circulating corticosterone levels and increased daily energy expenditure as compared with four non-selected control (C) lines. High corticosterone may suppress immune function and competing energy demands may limit ability to mount an immune response. We hypothesized that HR mice have a reduced immune response and therefore a decreased ability to fight an infection by Trichinella spiralis, an ecologically relevant nematode common in mammals. Infections have an acute, intestinal phase while the nematode is migrating, reproducing and traveling throughout the bloodstream, followed by a chronic phase with larvae encysted in muscles. Adult males (generation 55 of the selection experiment) were sham-infected or infected by oral gavage with ~300 J1 T. spiralis larvae. During the chronic phase of infection, mice were given wheel access for 6 days, followed by 2 days of maximum aerobic performance trials. Two weeks post-infection, infected HR had significantly lower circulating immunoglobulin E levels compared with infected C mice. However, we found no statistical difference between infected HR and C mice in numbers of encysted larvae within the diaphragm. As expected, both voluntary running and maximum aerobic performance were significantly higher in HR mice and lower in infected mice, with no line type-by-infection interactions. Results complement those of previous studies suggesting decreased locomotor abilities during the chronic phase of T. spiralis infection. However, despite reduced antibody production, breeding for high voluntary wheel exercise does not appear to have a substantial negative impact on general humoral function.
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Affiliation(s)
- Elizabeth M Dlugosz
- Department of Biology and Graduate Program in Evolution, Ecology and Organismal Biology, University of California, Riverside, Riverside, CA 92521, USA
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31
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Yamada Y, Colman RJ, Kemnitz JW, Baum ST, Anderson RM, Weindruch R, Schoeller DA. Long-term calorie restriction decreases metabolic cost of movement and prevents decrease of physical activity during aging in rhesus monkeys. Exp Gerontol 2013; 48:1226-35. [PMID: 23954367 DOI: 10.1016/j.exger.2013.08.002] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2013] [Revised: 07/18/2013] [Accepted: 08/05/2013] [Indexed: 12/19/2022]
Abstract
BACKGROUND Short-term (<1 year) calorie restriction (CR) has been reported to decrease physical activity and metabolic rate in humans and non-human primate models; however, studies examining the very long-term (>10 year) effect of CR on these parameters are lacking. OBJECTIVE The objective of this study was to examine metabolic and behavioral adaptations to long-term CR longitudinally in rhesus macaques. DESIGN Eighteen (10 male, 8 female) control (C) and 24 (14 male, 10 female) age matched CR rhesus monkeys between 19.6 and 31.9 years old were examined after 13 and 18 years of moderate adult-onset CR. Energy expenditure (EE) was examined by doubly labeled water (DLW; TEE) and respiratory chamber (24 h EE). Physical activity was assessed both by metabolic equivalent (MET) in a respiratory chamber and by an accelerometer. Metabolic cost of movements during 24 h was also calculated. Age and fat-free mass were included as covariates. RESULTS Adjusted total and 24 h EE were not different between C and CR. Sleeping metabolic rate was significantly lower, and physical activity level was higher in CR than in C independent from the CR-induced changes in body composition. The duration of physical activity above 1.6 METs was significantly higher in CR than in C, and CR had significantly higher accelerometer activity counts than C. Metabolic cost of movements during 24 h was significantly lower in CR than in C. The accelerometer activity counts were significantly decreased after seven years in C animals, but not in CR animals. CONCLUSIONS The results suggest that long-term CR decreases basal metabolic rate, but maintains higher physical activity with lower metabolic cost of movements compared with C.
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Affiliation(s)
- Yosuke Yamada
- Nutritional Sciences, University of Wisconsin-Madison, United States.
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Kolb EM, Rezende EL, Holness L, Radtke A, Lee SK, Obenaus A, Garland T. Mice selectively bred for high voluntary wheel running have larger midbrains: support for the mosaic model of brain evolution. ACTA ACUST UNITED AC 2013; 216:515-23. [PMID: 23325861 DOI: 10.1242/jeb.076000] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Increased brain size, relative to body mass, is a primary characteristic distinguishing the mammalian lineage. This greater encephalization has come with increased behavioral complexity and, accordingly, it has been suggested that selection on behavioral traits has been a significant factor leading to the evolution of larger whole-brain mass. In addition, brains may evolve in a mosaic fashion, with functional components having some freedom to evolve independently from other components, irrespective of, or in addition to, changes in size of the whole brain. We tested whether long-term selective breeding for high voluntary wheel running in laboratory house mice results in changes in brain size, and whether those changes have occurred in a concerted or mosaic fashion. We measured wet and dry brain mass via dissections and brain volume with ex vivo magnetic resonance imaging of brains that distinguished the caudate-putamen, hippocampus, midbrain, cerebellum and forebrain. Adjusting for body mass as a covariate, mice from the four replicate high-runner (HR) lines had statistically larger non-cerebellar wet and dry brain masses than those from four non-selected control lines, with no differences in cerebellum wet or dry mass or volume. Moreover, the midbrain volume in HR mice was ~13% larger (P<0.05), while volumes of the caudate-putamen, hippocampus, cerebellum and forebrain did not differ statistically between HR and control lines. We hypothesize that the enlarged midbrain of HR mice is related to altered neurophysiological function in their dopaminergic system. To our knowledge, this is the first example in which selection for a particular mammalian behavior has been shown to result in a change in size of a specific brain region.
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Affiliation(s)
- E M Kolb
- Department of Biology, University of California, Riverside, Riverside, CA 92521, USA
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Chappell MA, Szafrańska PA, Zub K, Konarzewski M. The energy cost of voluntary running in the weasel Mustela nivalis. ACTA ACUST UNITED AC 2012; 216:578-86. [PMID: 23125341 DOI: 10.1242/jeb.079186] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The small size and elongate shape of weasels (Mustela nivalis) probably evolved to facilitate movement within the burrow systems of prey species, but result in high energy costs of thermoregulation. In this study we measured metabolic rates of weasels during voluntary locomotion to determine whether energy costs of transport are also high in these unusually shaped mammals. In addition, we measured the lower and upper limits of aerobic metabolism [resting metabolic rate (RMR) and maximal oxygen consumption in forced exercise (V(O(2),max))], and used the wide size range of adult weasels to investigate the intraspecific scaling of energy metabolism. Finally, we combined measurements of energy use during running with radiotracking and doubly labeled water data from free-living weasels to estimate the importance of locomotor costs in daily energy budgets. We found that weasels have higher than predicted costs of running, largely because of an elevated intercept of the speed versus metabolic rate relationship. Running costs were strongly affected by the approximately fourfold range of body size in adults. As reported in other studies, the RMR of weasels was considerably higher than predicted from body mass. Maximal oxygen consumption was also higher than predicted, but factorial aerobic scope (V(O(2),max)/RMR) was within the normal range for mammals. Intraspecific mass scaling of RMR and V(O(2),max) did not differ from typical interspecific mammalian allometries. In wild weasels, locomotor costs comprised roughly 5% of daily energy expenditures; this low value was primarily a result of short travel times and distances.
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Affiliation(s)
- Mark A Chappell
- Biology Department, University of California, Riverside, Riverside, CA 92521, USA.
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Dlugosz EM, Harris BN, Saltzman W, Chappell MA. Glucocorticoids, aerobic physiology, and locomotor behavior in California mice. Physiol Biochem Zool 2012; 85:671-83. [PMID: 23099464 DOI: 10.1086/667809] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
The glucocorticoid hormones corticosterone (CORT) and cortisol influence numerous physiological, morphological, and behavioral functions. However, few studies have addressed possible relationships between individual differences in glucocorticoid concentrations and whole-animal performance or metabolism. Because CORT is important in glucose regulation and energy metabolism and can influence activity levels, we hypothesized that individual variation in baseline circulating CORT levels would correlate with individual differences in energy expenditure (routine and maximal), aerobic physiology, voluntary exercise on wheels, and organ masses. We tested this hypothesis in the California mouse (Peromyscus californicus). We collected data from 54 adult, colony-bred mice on baseline CORT levels (measured near both the circadian peak and the circadian trough), voluntary wheel running and its energetic costs, maximal oxygen consumption during forced treadmill exercise ([Formula: see text]), basal metabolic rate, and relative organ masses. We found surprisingly few statistically significant relationships among CORT, energy metabolism, behavior, and organ masses, and these relationships appeared to differ between males and females. These findings suggest that individual differences in baseline CORT levels are not an important determinant of voluntary activity levels or aerobic performance in California mice.
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Affiliation(s)
- Elizabeth M Dlugosz
- Department of Biology and Graduate Program in Evolution, Ecology, and Organismal Biology, University of California, Riverside, California 92521, USA.
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Konarzewski M, Książek A. Determinants of intra-specific variation in basal metabolic rate. J Comp Physiol B 2012; 183:27-41. [PMID: 22847501 PMCID: PMC3536993 DOI: 10.1007/s00360-012-0698-z] [Citation(s) in RCA: 118] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2011] [Revised: 06/10/2012] [Accepted: 07/13/2012] [Indexed: 12/02/2022]
Abstract
Basal metabolic rate (BMR) provides a widely accepted benchmark of metabolic expenditure for endotherms under laboratory and natural conditions. While most studies examining BMR have concentrated on inter-specific variation, relatively less attention has been paid to the determinants of within-species variation. Even fewer studies have analysed the determinants of within-species BMR variation corrected for the strong influence of body mass by appropriate means (e.g. ANCOVA). Here, we review recent advancements in studies on the quantitative genetics of BMR and organ mass variation, along with their molecular genetics. Next, we decompose BMR variation at the organ, tissue and molecular level. We conclude that within-species variation in BMR and its components have a clear genetic signature, and are functionally linked to key metabolic process at all levels of biological organization. We highlight the need to integrate molecular genetics with conventional metabolic field studies to reveal the adaptive significance of metabolic variation. Since comparing gene expressions inter-specifically is problematic, within-species studies are more likely to inform us about the genetic underpinnings of BMR. We also urge for better integration of animal and medical research on BMR; the latter is quickly advancing thanks to the application of imaging technologies and ‘omics’ studies. We also suggest that much insight on the biochemical and molecular underpinnings of BMR variation can be gained from integrating studies on the mammalian target of rapamycin (mTOR), which appears to be the major regulatory pathway influencing the key molecular components of BMR.
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Templeman NM, Schutz H, Garland T, McClelland GB. Do mice bred selectively for high locomotor activity have a greater reliance on lipids to power submaximal aerobic exercise? Am J Physiol Regul Integr Comp Physiol 2012; 303:R101-11. [PMID: 22573104 DOI: 10.1152/ajpregu.00511.2011] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Patterns of fuel use during locomotion are determined by exercise intensity and duration, and are remarkably similar across many mammalian taxa. However, as lipids have a high yield of ATP per mole and are stored in large quantities, their use should be favored in endurance-adapted animals. To examine the capacity for alteration or differential regulation of fuel-use patterns, we studied two lines of mice that had been selectively bred for high voluntary wheel running (HR), including one characterized by small hindlimb muscles (HR(mini)) and one without this phenotype (HR(normal)), as well as a nonselected control line. We evaluated: 1) maximal aerobic capacity (Vo(2 max)); 2) whole body fuel use during exercise by indirect calorimetry; 3) cardiac properties; and 4) many factors involved in regulating lipid use. HR mice achieved an increased Vo(2 max) compared with control mice, potentially in part due to HR cardiac capacities for metabolic fuel oxidation and the larger relative heart size of HR(mini) mice. HR mice also exhibited enhanced whole body lipid oxidation rates at 66% Vo(2 max), but HR(mini), HR(normal), and control mice did not differ in the proportional mix of fuels sustaining exercise (% total Vo(2)). However, HR(mini) gastrocnemius muscle had elevated fatty acid translocase (FAT/CD36) sarcolemmal protein and cellular mRNA, fatty acid binding protein (H-FABP) cytosolic protein, peroxisome proliferator-activated receptor (PPAR) α mRNA, and mass-specific activities of citrate synthase, β-hydroxyacyl-CoA dehydrogenase, and hexokinase. Therefore, high-running mouse lines had whole body fuel oxidation rates commensurate with maximal aerobic capacity, despite notable differences in skeletal muscle metabolic phenotypes.
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Benrick A, Wallenius V, Asterholm IW. Interleukin-6 mediates exercise-induced increase in insulin sensitivity in mice. Exp Physiol 2012; 97:1224-35. [PMID: 22523382 DOI: 10.1113/expphysiol.2012.065508] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Interleukin-6 (IL-6) is released from working skeletal muscle during exercise. We investigated the acute and the long-term beneficial effects of IL-6 on exercise-induced glucose uptake in skeletal muscle and insulin sensitivity. The acute effect on exercise-induced glucose uptake was measured in IL-6-deficient (IL-6(-/-)) mice and wild-type control animals using a tracer technique. There was no difference in serum disappearance of (3)[H]2-deoxyglucose after a single bout of exercise between IL-6(-/-) and wild-type mice (13565 ± 426 versus 14343 ± 1309 d.p.m. min ml(-1), P = 0.5). The glucose uptake rate in the extensor digitorum longus muscle was, however, lower in IL-6(-/-) compared with wild-type mice (398 ± 44 versus 657 ± 41 nmol g(-1) min(-1), P < 0.01). In a long-term study, we monitored insulin sensitivity, serum retinol-binding protein-4 (RBP-4) levels, running activity, food intake, body weight and body composition in IL-6(-/-) and wild-type mice on a high-fat diet (HFD), with or without access to running wheels. In sedentary IL-6(-/-) and wild-type mice, the HFD decreased insulin sensitivity (glucose area under the concentration-time curve increased about 20% during an insulin tolerance test, P < 0.05 for both genotypes versus baseline) and led to a 30% increase in serum RBP-4 levels (P < 0.01 for both genotypes versus baseline). Wild-type mice with access to running wheels were protected against these effects of the HFD and maintained their baseline insulin sensitivity and serum RBP-4 levels. In contrast, IL-6(-/-) mice did not benefit from running to the same extent as wild-type animals. The IL-6(-/-) mice with access to running wheels had a similar decrease in insulin sensitivity to their sedentary littermates (glucose area under the concentration-time curve during an insulin tolerance test in runners versus sedentary IL-6(-/-) HFD mice, 312 ± 14 versus 340 ± 22 mmol min l(-1), P = 0.4) and displayed a 14% increase in serum RBP-4 compared with baseline levels (P < 0.01). Our results indicate that endogenous IL-6 contributes to the exercise-induced increase in insulin sensitivity, but plays only a minor role for glucose uptake into skeletal muscle during exercise.
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Affiliation(s)
- Anna Benrick
- Institute of Neuroscience and Physiology/ Endocrinology, The Sahlgrenska Academy at the University of Gothenburg, Medicinaregatan 11, SE-405 30 Gothenburg, Sweden
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Novak CM, Burghardt PR, Levine JA. The use of a running wheel to measure activity in rodents: relationship to energy balance, general activity, and reward. Neurosci Biobehav Rev 2012; 36:1001-1014. [PMID: 22230703 DOI: 10.1016/j.neubiorev.2011.12.012] [Citation(s) in RCA: 218] [Impact Index Per Article: 18.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2011] [Revised: 12/07/2011] [Accepted: 12/22/2011] [Indexed: 12/21/2022]
Abstract
Running wheels are commonly employed to measure rodent physical activity in a variety of contexts, including studies of energy balance and obesity. There is no consensus on the nature of wheel-running activity or its underlying causes, however. Here, we will begin by systematically reviewing how running wheel availability affects physical activity and other aspects of energy balance in laboratory rodents. While wheel running and physical activity in the absence of a wheel commonly correlate in a general sense, in many specific aspects the two do not correspond. In fact, the presence of running wheels alters several aspects of energy balance, including body weight and composition, food intake, and energy expenditure of activity. We contend that wheel-running activity should be considered a behavior in and of itself, reflecting several underlying behavioral processes in addition to a rodent's general, spontaneous activity. These behavioral processes include defensive behavior, predatory aggression, and depression- and anxiety-like behaviors. As it relates to energy balance, wheel running engages several brain systems-including those related to the stress response, mood, and reward, and those responsive to growth factors-that influence energy balance indirectly. We contend that wheel-running behavior represents factors in addition to rodents' tendency to be physically active, engaging additional neural and physiological mechanisms which can then independently alter energy balance and behavior. Given the impact of wheel-running behavior on numerous overlapping systems that influence behavior and physiology, this review outlines the need for careful design and interpretation of studies that utilize running wheels as a means for exercise or as a measurement of general physical activity.
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Affiliation(s)
- Colleen M Novak
- Department of Biological Sciences, Kent State University, PO Box 5190, 222 Cunningham Hall, Kent, OH 44242, United States
| | | | - James A Levine
- Mayo Clinic, Endocrine Research Unit, Rochester, MN 55905, United States
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Kaliman P, Párrizas M, Lalanza JF, Camins A, Escorihuela RM, Pallàs M. Neurophysiological and epigenetic effects of physical exercise on the aging process. Ageing Res Rev 2011; 10:475-86. [PMID: 21624506 DOI: 10.1016/j.arr.2011.05.002] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2011] [Revised: 04/29/2011] [Accepted: 05/13/2011] [Indexed: 10/18/2022]
Abstract
Aging is a gradual process during which molecular and cellular processes deteriorate progressively, often leading to such pathological conditions as vascular and metabolic disorders and cognitive decline. Although the mechanisms of aging are not yet fully understood, inflammation, oxidative damage, mitochondrial dysfunction, functional alterations in specific neuronal circuits and a restricted degree of apoptosis are involved. Physical exercise improves the efficiency of the capillary system and increases the oxygen supply to the brain, thus enhancing metabolic activity and oxygen intake in neurons, and increases neurotrophin levels and resistance to stress. Regular exercise and an active lifestyle during adulthood have been associated with reduced risk and protective effects for mild cognitive impairment and Alzheimer's disease. Similarly, studies in animal models show that physical activity has positive physiological and cognitive effects that correlate with changes in transcriptional profiles. According to numerous studies, epigenetic events that include changes in DNA methylation patterns, histone modification and alterations in microRNA profiles seem to be a signature of aging. Hence, insight into the epigenetic mechanisms involved in the aging process and their modulation through lifestyle interventions such as physical exercise might open new avenues for the development of preventive and therapeutic strategies to treat aging-related diseases.
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Hannon RM, Meek TH, Acosta W, Maciel RC, Schutz H, Garland T. Sex-specific heterosis in line crosses of mice selectively bred for high locomotor activity. Behav Genet 2011; 41:615-24. [PMID: 21184162 PMCID: PMC3121942 DOI: 10.1007/s10519-010-9432-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2010] [Accepted: 12/08/2010] [Indexed: 01/23/2023]
Abstract
When populations with similar histories of directional selection are crossed, their offspring may differ in mean phenotype as compared with the average for the parental populations, often exhibiting enhancement of the mean phenotype (termed heterosis or hybrid vigor). We tested for heterosis in a cross of two replicate lines of mice selectively bred for high voluntary wheel running for 53 generations. Mice were paired to produce four sets of F1 offspring: two purebred High Runner (HR) lines and the hybrid reciprocal crosses. The purebred HR showed statistically significant, sex-dependent differences in body mass, wheel revolutions, running duration, mean running speed, and (controlling for body mass) organ masses (heart ventricles, liver, spleen, triceps surae muscle). Hybrid males ran significantly more revolutions than the purebred males, mainly via increased running speeds, but hybrid females ran intermediate distances, durations, and speeds, as compared with the purebred females. In both sexes, ventricles were relatively smaller in hybrids as compared with purebred HR. Overall, our results demonstrate differential and sex-specific responses to selection in the two HR lines tested, implying divergent genetic architectures underlying high voluntary exercise.
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Affiliation(s)
- Robert M. Hannon
- Department of Biology, University of California, Riverside, CA 92521 USA
| | - Thomas H. Meek
- Department of Biology, University of California, Riverside, CA 92521 USA
| | - Wendy Acosta
- Department of Biology, University of California, Riverside, CA 92521 USA
| | - Robert C. Maciel
- Department of Biology, University of California, Riverside, CA 92521 USA
| | - Heidi Schutz
- Department of Biology, University of California, Riverside, CA 92521 USA
| | - Theodore Garland
- Department of Biology, University of California, Riverside, CA 92521 USA
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Garland T, Kelly SA, Malisch JL, Kolb EM, Hannon RM, Keeney BK, Van Cleave SL, Middleton KM. How to run far: multiple solutions and sex-specific responses to selective breeding for high voluntary activity levels. Proc Biol Sci 2011; 278:574-81. [PMID: 20810439 PMCID: PMC3025687 DOI: 10.1098/rspb.2010.1584] [Citation(s) in RCA: 83] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2010] [Accepted: 08/09/2010] [Indexed: 11/12/2022] Open
Abstract
The response to uniform selection may occur in alternate ways that result in similar performance. We tested for multiple adaptive solutions during artificial selection for high voluntary wheel running in laboratory mice. At generation 43, the four replicate high runner (HR) lines averaged 2.85-fold more revolutions per day as compared with four non-selected control (C) lines, and females ran 1.11-fold more than males, with no sex-by-linetype interaction. Analysis of variance indicated significant differences among C lines but not among HR for revolutions per day. By contrast, average speed varied significantly among HR lines, but not among C, and showed a sex-by-linetype interaction, with the HR/C ratio being 2.02 for males and 2.45 for females. Time spent running varied among both HR and C lines, and showed a sex-by-linetype interaction, with the HR/C ratio being 1.52 for males but only 1.17 for females. Thus, females (speed) and males (speed, but also time) evolved differently, as did the replicate selected lines. Speed and time showed a trade-off among HR but not among C lines. These results demonstrate that uniform selection on a complex trait can cause consistent responses in the trait under direct selection while promoting divergence in the lower-level components of that trait.
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Affiliation(s)
- Theodore Garland
- Department of Biology, University of California, , Riverside, CA 92521, USA.
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Jung AP, Curtis TS, Turner MJ, Lightfoot JT. Physical activity and food consumption in high- and low-active inbred mouse strains. Med Sci Sports Exerc 2011; 42:1826-33. [PMID: 20216465 DOI: 10.1249/mss.0b013e3181daf5e8] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
PURPOSE To determine the effect of innate activity level and running wheel access on food consumption in high-active (SWR/J) low-active (DBA/2J) mice. METHODS Two strains of inbred mice were used in this study owing to their high activity level (SWR/J) and low activity level (DBA/2J). Mice were housed in individual cages, and half of the mice in each strain had free access to running wheels in their cages, whereas the other half received no running wheel. All mice consumed standard chow and water ad libitum for 13 wk during the study period. Running wheel activity (daily), food consumption (biweekly), and body mass (weekly) were recorded. RESULTS SWR/J runners consumed more food (6.0 ± 0.4 g·d)(-1) than SWR/J nonrunners (4.7 ± 0.2 g·d(-1), P = 0.03), DBA/2J runners (4.6 ± 0.2 g·d(-1), P = 0.02), and DBA/2J nonrunners (4.2 ± 0.2 g·d(-1), P = 0.006). SWR/J nonrunners consumed more food than DBA/2J nonrunners (P = 0.03). Average daily distance and duration were significantly greater for the SWR/J runners (6.4 ± 0.7 km·d(-1) and 333.6 ± 40.5 min·d(-1), respectively) compared with those for the DBA/2J runners (1.6 ± 0.4 km·d(-1) and 91.3 ± 23.0 min·d(-1), respectively). There was a significant correlation between food consumption and distance (r = 0.74, P < 0.001), duration (r = 0.68, P < 0.001), and speed (r = 0.58, P < 0.001), respectively, in all mice. However, when considering the individuals strains, the relationship between running wheel activity and food consumption was only statistically significant for the SWR/J mice. CONCLUSIONS Higher running wheel activity in mice was associated with increased food consumption in the SWR/J mice but not in the DBA/2J mice. In DBA/2J mice, addition of a running wheel did not result in increased food consumption, suggesting that energy expenditure of nonwheel cage activity in the control DBA/2J mice was similar to the energy expenditure of the wheel activity because body mass was similar between the two groups.
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Affiliation(s)
- Alan P Jung
- Department of Exercise Science and Sports Medicine, Samford University, Birmingham, AL 35229, USA.
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Jung AP, Luthin DR. Wheel access does not attenuate weight gain in mice fed high-fat or high-CHO diets. Med Sci Sports Exerc 2010; 42:355-60. [PMID: 19927024 DOI: 10.1249/mss.0b013e3181a6d88f] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
PURPOSE To determine the effect of a high-fat or high-carbohydrate diet and running wheel activity on body composition, body mass, and caloric intake in C57Bl/6 mice. METHODS At 4 wk of age, five groups of C57Bl/6 mice were housed individually. Two groups had running wheels, whereas the other three groups did not. Within the running wheel groups, FAT-W consumed a high-fat diet (60.3% fat) and CHO-W consumed a high-carbohydrate diet (70.4% carbohydrate). Within the nonrunning groups, FAT consumed the high-fat diet, CHO consumed the high-carbohydrate diet, and the fifth group consumed standard chow. All groups consumed food ad libitum and were exposed to their respective conditions for 12 wk. Wheel activity, food consumption, body mass (BM), and percentage of body fat (%BF) were recorded. RESULTS There was no significant difference in %BF or BM at the end of 12 wk between FAT-W and FAT or between CHO-W and CHO (P > 0.05). %BF was significantly higher in both FAT-W (42.9% +/- 0.6%) and FAT (45.9% +/- 0.8%) compared with CHO-W (30.8% +/- 1.4%) or CHO (33.4% +/- 1.0%; P < 0.001). BM was significantly higher in both FAT-W (42.8 +/- 0.7 g) and FAT (44.7 +/- 1.2 g) compared with either CHO-W (32.8 +/- 1.6 g) or CHO (37.1 +/- 0.8; P < 0.01). There was no difference in wheel activity between FAT-W and CHO-W (P > 0.05). Daily caloric intake was higher in both FAT-W (17.0 +/- 0.8 kcal) and FAT (15.9 +/- 0.9 kcal) compared with that in CHO-W (13.9 +/- 0.7 kcal) and CHO (13.6 +/- 0.5 kcal; P < 0.01). CONCLUSIONS Access to a running wheel had no protective effect on BM or %BF in C57Bl/6 mice that consumed either a high-fat or a high-carbohydrate diet during a 12-wk period. Access to a running wheel did not affect caloric intake; however, average daily caloric intake was higher in mice on high-fat diets compared with that in mice on a high-carbohydrate diet.
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Affiliation(s)
- Alan P Jung
- Samford University, Birmingham, AL 35229, USA.
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Kolb EM, Kelly SA, Middleton KM, Sermsakdi LS, Chappell MA, Garland T. Erythropoietin elevates VO2,max but not voluntary wheel running in mice. ACTA ACUST UNITED AC 2010; 213:510-9. [PMID: 20086137 DOI: 10.1242/jeb.029074] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Voluntary activity is a complex trait, comprising both behavioral (motivation, reward) and anatomical/physiological (ability) elements. In the present study, oxygen transport was investigated as a possible limitation to further increases in running by four replicate lines of mice that have been selectively bred for high voluntary wheel running and have reached an apparent selection limit. To increase oxygen transport capacity, erythrocyte density was elevated by the administration of an erythropoietin (EPO) analogue. Mice were given two EPO injections, two days apart, at one of two dose levels (100 or 300 microg kg(-1)). Hemoglobin concentration ([Hb]), maximal aerobic capacity during forced treadmill exercise (VO2,max) and voluntary wheel running were measured. [Hb] did not differ between high runner (HR) and non-selected control (C) lines without EPO treatment. Both doses of EPO significantly (P<0.0001) increased [Hb] as compared with sham-injected animals, with no difference in [Hb] between the 100 microg kg(-1) and 300 microg kg(-1) dose levels (overall mean of 4.5 g dl(-1) increase). EPO treatment significantly increased VO2,max by approximately 5% in both the HR and C lines, with no dosexline type interaction. However, wheel running (revolutions per day) did not increase with EPO treatment in either the HR or C lines, and in fact significantly decreased at the higher dose in both line types. These results suggest that neither [Hb] per se nor VO2,max is limiting voluntary wheel running in the HR lines. Moreover, we hypothesize that the decrease in wheel running at the higher dose of EPO may reflect direct action on the reward pathway of the brain.
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Affiliation(s)
- E M Kolb
- Department of Biology, University of California, Riverside, CA 92521, USA
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Knab AM, Lightfoot JT. Does the difference between physically active and couch potato lie in the dopamine system? Int J Biol Sci 2010; 6:133-50. [PMID: 20224735 PMCID: PMC2836544 DOI: 10.7150/ijbs.6.133] [Citation(s) in RCA: 103] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2009] [Accepted: 03/02/2010] [Indexed: 01/04/2023] Open
Abstract
Obesity and other inactivity related diseases are increasing at an alarming rate especially
in Western societies. Because of this, it is important to understand the regulating mechanisms
involved in physical activity behavior. Much research has been done in regard to the
psychological determinants of physical activity behavior; however, little is known about the
underlying genetic and biological factors that may contribute to regulation of this complex
trait. It is true that a significant portion of any trait is regulated by genetic and
biological factors. In the case of voluntary physical activity behavior, these regulating
mechanisms appear to be concentrated in the central nervous system. In particular, the dopamine
system has been shown to regulate motor movement, as well as motivation and reward behavior.
The pattern of regulation of voluntary physical activity by the dopamine system is yet to be
fully elucidated. This review will summarize what is known about the dopamine system and
regulation of physical activity, and will present a hypothesis of how this signaling pathway is
mechanistically involved in regulating voluntary physical activity behavior. Future research in
this area will aid in developing personalized strategies to prevent inactivity related
diseases.
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Affiliation(s)
- Amy M Knab
- Department of Kinesiology, University of North Carolina, Charlotte, NC, USA.
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Vaanholt L, Daan S, Garland Jr. T, Visser G. Exercising for Life? Energy Metabolism, Body Composition, and Longevity in Mice Exercising at Different Intensities. Physiol Biochem Zool 2010; 83:239-51. [DOI: 10.1086/648434] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Rezende EL, Gomes FR, Chappell MA, Garland T. Running behavior and its energy cost in mice selectively bred for high voluntary locomotor activity. Physiol Biochem Zool 2010; 82:662-79. [PMID: 19799520 DOI: 10.1086/605917] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Locomotion is central to behavior and intrinsic to many fitness-critical activities (e.g., migration, foraging), and it competes with other life-history components for energy. However, detailed analyses of how changes in locomotor activity and running behavior affect energy budgets are scarce. We quantified these effects in four replicate lines of house mice that have been selectively bred for high voluntary wheel running (S lines) and in their four nonselected control lines (C lines). We monitored wheel speeds and oxygen consumption for 24-48 h to determine daily energy expenditure (DEE), resting metabolic rate (RMR), locomotor costs, and running behavior (bout characteristics). Daily running distances increased roughly 50%-90% in S lines in response to selection. After we controlled for body mass effects, selection resulted in a 23% increase in DEE in males and a 6% increase in females. Total activity costs (DEE - RMR) accounted for 50%-60% of DEE in both S and C lines and were 29% higher in S males and 5% higher in S females compared with their C counterparts. Energetic costs of increased daily running distances differed between sexes because S females evolved higher running distances by running faster with little change in time spent running, while S males also spent 40% more time running than C males. This increase in time spent running impinged on high energy costs because the majority of running costs stemmed from "postural costs" (the difference between RMR and the zero-speed intercept of the speed vs. metabolic rate relationship). No statistical differences in these traits were detected between S and C females, suggesting that large changes in locomotor behavior do not necessarily effect overall energy budgets. Running behavior also differed between sexes: within S lines, males ran with more but shorter bouts than females. Our results indicate that selection effects on energy budgets can differ dramatically between sexes and that energetic constraints in S males might partly explain the apparent selection limit for wheel running observed for over 15 generations.
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Affiliation(s)
- Enrico L Rezende
- Department of Biology, University of California, Riverside, California 92521, USA.
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Middleton KM, Goldstein BD, Guduru PR, Waters JF, Kelly SA, Swartz SM, Garland T. Variation in within-bone stiffness measured by nanoindentation in mice bred for high levels of voluntary wheel running. J Anat 2010; 216:121-31. [PMID: 20402827 PMCID: PMC2807980 DOI: 10.1111/j.1469-7580.2009.01175.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/16/2009] [Indexed: 12/17/2022] Open
Abstract
The hierarchical structure of bone, involving micro-scale organization and interaction of material components, is a critical determinant of macro-scale mechanics. Changes in whole-bone morphology in response to the actions of individual genes, physiological loading during life, or evolutionary processes, may be accompanied by alterations in underlying mineralization or architecture. Here, we used nanoindentation to precisely measure compressive stiffness in the femoral mid-diaphysis of mice that had experienced 37 generations of selective breeding for high levels of voluntary wheel running (HR). Mice (n = 48 total), half from HR lines and half from non-selected control (C) lines, were divided into two experimental groups, one with 13-14 weeks of access to a running wheel and one housed without wheels (n = 12 in each group). At the end of the experiment, gross and micro-computed tomography (microCT)-based morphometric traits were measured, and reduced elastic modulus (E(r)) was estimated separately for four anatomical quadrants of the femoral cortex: anterior, posterior, lateral, and medial. Two-way, mixed-model analysis of covariance (ancova) showed that body mass was a highly significant predictor of all morphometric traits and that structural change is more apparent at the microCT level than in conventional morphometrics of whole bones. Both line type (HR vs. C) and presence of the mini-muscle phenotype (caused by a Mendelian recessive allele and characterized by a approximately 50% reduction in mass of the gastrocnemius muscle complex) were significant predictors of femoral cortical cross-sectional anatomy. Measurement of reduced modulus obtained by nanoindentation was repeatable within a single quadrant and sensitive enough to detect inter-individual differences. Although we found no significant effects of line type (HR vs. C) or physical activity (wheel vs. no wheel) on mean stiffness, anterior and posterior quadrants were significantly stiffer (P < 0.0001) than medial and lateral quadrants (32.67 and 33.09 GPa vs. 29.78 and 30.46 GPa, respectively). Our findings of no significant difference in compressive stiffness in the anterior and posterior quadrants agree with previous results for mice, but differ from those for large mammals. Integrating these results with others from ongoing research on these mice, we hypothesize that the skeletons of female HR mice may be less sensitive to the effects of chronic exercise, due to decreased circulating leptin levels and potentially altered endocannabinoid signaling.
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Affiliation(s)
- Kevin M Middleton
- Department of Ecology and Evolutionary Biology, Brown University, Providence, RI, USA.
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Meek TH, Lonquich BP, Hannon RM, Garland T. Endurance capacity of mice selectively bred for high voluntary wheel running. ACTA ACUST UNITED AC 2009; 212:2908-17. [PMID: 19717672 DOI: 10.1242/jeb.028886] [Citation(s) in RCA: 79] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Mice from four lines bred for high voluntary wheel activity run approximately 3-fold more revolutions per day and have elevated maximal oxygen consumption during forced treadmill exercise, as compared with four unselected control (C) lines. We hypothesized that these high runner (HR) lines would have greater treadmill endurance-running capacity. Ninety-six mice from generation 49 were familiarized with running on a motorized treadmill for 3 days. On days 4 and 5, mice were given an incremental speed test (starting at 20 m min(-1), increased 1.5 m min(-1) every 2 min) and endurance was measured as the total time or distance run to exhaustion. Blood samples were taken to measure glucose and lactate concentrations at rest during the photophase, during peak nightly wheel running, and immediately following the second endurance test. Individual differences in endurance time were highly repeatable between days (r=0.79), and mice tended to run longer on the second day (paired t-test, P<0.0001). Blood glucose following the treadmill test was low for all animals ( approximately 53 mg dl(-1)) and lactate was high ( approximately 6.5 mmol l(-1)), suggesting that exhaustion occurred. The HR lines had significantly higher endurance than the C lines (1-tailed P<0.05), whether or not body mass was used as a covariate in the analysis. The relationship between line means for wheel running and treadmill endurance differed between the sexes, reinforcing previous studies that indicate sex-specific responses to selective breeding. HR mice appear to have a higher endurance capacity than reported in the literature for inbred strains of mice or transgenics intended to enhance endurance.
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Affiliation(s)
- Thomas H Meek
- University of California Riverside, Riverside, CA 92521, USA
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