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Takaragawa M, Tobina T, Shiose K, Kakigi R, Tsuzuki T, Ichinoseki-Sekine N, Kumagai H, Zempo H, Miyamoto-Mikami E, Kobayashi H, Naito H, Fuku N. Genotype Score for Iron Status Is Associated with Muscle Fiber Composition in Women. Genes (Basel) 2021; 13:genes13010005. [PMID: 35052344 PMCID: PMC8775127 DOI: 10.3390/genes13010005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Revised: 12/16/2021] [Accepted: 12/17/2021] [Indexed: 01/01/2023] Open
Abstract
Human muscle fiber composition is heterogeneous and mainly determined by genetic factors. A previous study reported that experimentally induced iron deficiency in rats increases the proportion of fast-twitch muscle fibers. Iron status has been reported to be affected by genetic factors. As the TMPRSS6 rs855791 T/C and HFE rs1799945 C/G polymorphisms are strongly associated with iron status in humans, we hypothesized that the genotype score (GS) based on these polymorphisms could be associated with the muscle fiber composition in humans. Herein, we examined 214 Japanese individuals, comprising of 107 men and 107 women, for possible associations of the GS for iron status with the proportion of myosin heavy chain (MHC) isoforms (I, IIa, and IIx) as markers of muscle fiber composition. No statistically significant correlations were found between the GS for iron status and the proportion of MHC isoforms in all participants. When the participants were stratified based on sex, women showed positive and negative correlations of the GS with MHC-IIa (age-adjusted p = 0.020) and MHC-IIx (age-adjusted p = 0.011), respectively. In contrast, no correlation was found in men. In women, a 1-point increase in the GS was associated with 2.42% higher MHC-IIa level and 2.72% lower MHC-IIx level. Our results suggest that the GS based on the TMPRSS6 rs855791 T/C and HFE rs1799945 C/G polymorphisms for iron status is associated with muscle fiber composition in women.
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Affiliation(s)
- Mizuki Takaragawa
- Graduate School of Health and Sports Science, Juntendo University, Chiba 270-1695, Japan; (M.T.); (N.I.-S.); (H.K.); (E.M.-M.); (H.K.); (H.N.)
| | - Takuro Tobina
- Faculty of Nursing and Nutrition, University of Nagasaki, Nagasaki 851-2195, Japan;
| | - Keisuke Shiose
- Faculty of Education, University of Miyazaki, Miyazaki 889-2192, Japan;
| | - Ryo Kakigi
- Faculty of Management & Information Science, Josai International University, Chiba 283-8555, Japan;
| | | | - Noriko Ichinoseki-Sekine
- Graduate School of Health and Sports Science, Juntendo University, Chiba 270-1695, Japan; (M.T.); (N.I.-S.); (H.K.); (E.M.-M.); (H.K.); (H.N.)
- Faculty of Liberal Arts, The Open University of Japan, Chiba 261-8586, Japan
| | - Hiroshi Kumagai
- Graduate School of Health and Sports Science, Juntendo University, Chiba 270-1695, Japan; (M.T.); (N.I.-S.); (H.K.); (E.M.-M.); (H.K.); (H.N.)
| | - Hirofumi Zempo
- Faculty of Health and Nutrition, Tokyo Seiei College, Tokyo 124-8530, Japan;
| | - Eri Miyamoto-Mikami
- Graduate School of Health and Sports Science, Juntendo University, Chiba 270-1695, Japan; (M.T.); (N.I.-S.); (H.K.); (E.M.-M.); (H.K.); (H.N.)
| | - Hiroyuki Kobayashi
- Graduate School of Health and Sports Science, Juntendo University, Chiba 270-1695, Japan; (M.T.); (N.I.-S.); (H.K.); (E.M.-M.); (H.K.); (H.N.)
- Mito Medical Center, Tsukuba University Hospital, Ibaraki 310-0015, Japan
| | - Hisashi Naito
- Graduate School of Health and Sports Science, Juntendo University, Chiba 270-1695, Japan; (M.T.); (N.I.-S.); (H.K.); (E.M.-M.); (H.K.); (H.N.)
| | - Noriyuki Fuku
- Graduate School of Health and Sports Science, Juntendo University, Chiba 270-1695, Japan; (M.T.); (N.I.-S.); (H.K.); (E.M.-M.); (H.K.); (H.N.)
- Correspondence: ; Tel.: +81-476-98-1001 (ext. 9203)
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Hostrup M, Onslev J, Jacobson GA, Wilson R, Bangsbo J. Chronic β 2 -adrenoceptor agonist treatment alters muscle proteome and functional adaptations induced by high intensity training in young men. J Physiol 2017; 596:231-252. [PMID: 28983994 DOI: 10.1113/jp274970] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2017] [Accepted: 09/26/2017] [Indexed: 12/26/2022] Open
Abstract
KEY POINTS While several studies have investigated the effects of exercise training in human skeletal muscle and the chronic effect of β2 -agonist treatment in rodent muscle, their effects on muscle proteome signature with related functional measures in humans are still incompletely understood. Herein we show that daily β2 -agonist treatment attenuates training-induced enhancements in exercise performance and maximal oxygen consumption, and alters muscle proteome signature and phenotype in trained young men. Daily β2 -agonist treatment abolished several of the training-induced enhancements in muscle oxidative capacity and caused a repression of muscle metabolic pathways; furthermore, β2 -agonist treatment induced a slow-to-fast twitch muscle phenotype transition. The present study indicates that chronic β2 -agonist treatment confounds the positive effect of high intensity training on exercise performance and oxidative capacity, which is of interest for the large proportion of persons using inhaled β2 -agonists on a daily basis, including athletes. ABSTRACT Although the effects of training have been studied for decades, data on muscle proteome signature remodelling induced by high intensity training in relation to functional changes in humans remains incomplete. Likewise, β2 -agonists are frequently used to counteract exercise-induced bronchoconstriction, but the effects β2 -agonist treatment on muscle remodelling and adaptations to training are unknown. In a placebo-controlled parallel study, we randomly assigned 21 trained men to 4 weeks of high intensity training with (HIT+β2 A) or without (HIT) daily inhalation of β2 -agonist (terbutaline, 4 mg dose-1 ). Of 486 proteins identified by mass-spectrometry proteomics of muscle biopsies sampled before and after the intervention, 32 and 85 were changing (false discovery rate (FDR) ≤5%) with the intervention in HIT and HIT+β2 A, respectively. Proteome signature changes were different in HIT and HIT+β2 A (P = 0.005), wherein β2 -agonist caused a repression of 25 proteins in HIT+β2 A compared to HIT, and an upregulation of 7 proteins compared to HIT. β2 -Agonist repressed or even downregulated training-induced enrichment of pathways related to oxidative phosphorylation and glycogen metabolism, but upregulated pathways related to histone trimethylation and the nucleosome. Muscle contractile phenotype changed differently in HIT and HIT+β2 A (P ≤ 0.001), with a fast-to-slow twitch transition in HIT and a slow-to-fast twitch transition in HIT+β2 A. β2 -Agonist attenuated training-induced enhancements in maximal oxygen consumption (P ≤ 0.01) and exercise performance (6.1 vs. 11.6%, P ≤ 0.05) in HIT+β2 A compared to HIT. These findings indicate that daily β2 -agonist treatment attenuates the beneficial effects of high intensity training on exercise performance and oxidative capacity, and causes remodelling of muscle proteome signature towards a fast-twitch phenotype.
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Affiliation(s)
- Morten Hostrup
- Department of Nutrition, Exercise and Sports, University of Copenhagen, Copenhagen, Denmark
| | - Johan Onslev
- Department of Nutrition, Exercise and Sports, University of Copenhagen, Copenhagen, Denmark
| | - Glenn A Jacobson
- Division of Pharmacy, School of Medicine, University of Tasmania, Hobart, Australia
| | - Richard Wilson
- Central Science Laboratory, University of Tasmania, Hobart, Australia
| | - Jens Bangsbo
- Department of Nutrition, Exercise and Sports, University of Copenhagen, Copenhagen, Denmark
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Cao X, Zhou C, Chong J, Fu L, Zhang L, Sun D, Hou H, Zhang Y, Li D, Sun H. Estrogen resisted stress-induced cardiomyopathy through increasing the activity of β2AR–Gαs signal pathway in female rats. Int J Cardiol 2015; 187:377-86. [DOI: 10.1016/j.ijcard.2015.02.113] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/21/2014] [Revised: 02/16/2015] [Accepted: 02/21/2015] [Indexed: 02/08/2023]
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Church JE, Trieu J, Sheorey R, Chee AYM, Naim T, Baum DM, Ryall JG, Gregorevic P, Lynch GS. Functional β-adrenoceptors are important for early muscle regeneration in mice through effects on myoblast proliferation and differentiation. PLoS One 2014; 9:e101379. [PMID: 25000590 PMCID: PMC4084885 DOI: 10.1371/journal.pone.0101379] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2014] [Accepted: 06/05/2014] [Indexed: 12/25/2022] Open
Abstract
Muscles can be injured in different ways and the trauma and subsequent loss of function and physical capacity can impact significantly on the lives of patients through physical impairments and compromised quality of life. The relative success of muscle repair after injury will largely determine the extent of functional recovery. Unfortunately, regenerative processes are often slow and incomplete, and so developing novel strategies to enhance muscle regeneration is important. While the capacity to enhance muscle repair by stimulating β2-adrenoceptors (β-ARs) using β2-AR agonists (β2-agonists) has been demonstrated previously, the exact role β-ARs play in regulating the regenerative process remains unclear. To investigate β-AR-mediated signaling in muscle regeneration after myotoxic damage, we examined the regenerative capacity of tibialis anterior and extensor digitorum longus muscles from mice lacking either β1-AR (β1-KO) and/or β2-ARs (β2-KO), testing the hypothesis that muscles from mice lacking the β2-AR would exhibit impaired functional regeneration after damage compared with muscles from β1-KO or β1/β2-AR null (β1/β2-KO) KO mice. At 7 days post-injury, regenerating muscles from β1/β2-KO mice produced less force than those of controls but muscles from β1-KO or β2-KO mice did not exhibit any delay in functional restoration. Compared with controls, β1/β2-KO mice exhibited an enhanced inflammatory response to injury, which delayed early muscle regeneration, but an enhanced myoblast proliferation later during regeneration ensured a similar functional recovery (to controls) by 14 days post-injury. This apparent redundancy in the β-AR signaling pathway was unexpected and may have important implications for manipulating β-AR signaling to improve the rate, extent and efficacy of muscle regeneration to enhance functional recovery after injury.
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MESH Headings
- Animals
- Cell Differentiation
- Cell Proliferation
- Gene Knockout Techniques
- Mice
- Muscle Strength
- Muscle, Skeletal/anatomy & histology
- Muscle, Skeletal/cytology
- Muscle, Skeletal/physiology
- Myoblasts/cytology
- Organ Size
- Receptors, Adrenergic, beta-1/deficiency
- Receptors, Adrenergic, beta-1/genetics
- Receptors, Adrenergic, beta-1/metabolism
- Receptors, Adrenergic, beta-2/deficiency
- Receptors, Adrenergic, beta-2/genetics
- Receptors, Adrenergic, beta-2/metabolism
- Regeneration
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Affiliation(s)
- Jarrod E. Church
- Basic and Clinical Myology Laboratory, Department of Physiology, The University of Melbourne, Victoria, Australia
| | - Jennifer Trieu
- Basic and Clinical Myology Laboratory, Department of Physiology, The University of Melbourne, Victoria, Australia
| | - Radhika Sheorey
- Basic and Clinical Myology Laboratory, Department of Physiology, The University of Melbourne, Victoria, Australia
| | - Annabel Y. -M. Chee
- Basic and Clinical Myology Laboratory, Department of Physiology, The University of Melbourne, Victoria, Australia
| | - Timur Naim
- Basic and Clinical Myology Laboratory, Department of Physiology, The University of Melbourne, Victoria, Australia
| | - Dale M. Baum
- Basic and Clinical Myology Laboratory, Department of Physiology, The University of Melbourne, Victoria, Australia
| | - James G. Ryall
- Basic and Clinical Myology Laboratory, Department of Physiology, The University of Melbourne, Victoria, Australia
| | - Paul Gregorevic
- Laboratory for Muscle Research & Therapeutics Development, Baker IDI Heart and Diabetes Institute, Victoria, Australia
| | - Gordon S. Lynch
- Basic and Clinical Myology Laboratory, Department of Physiology, The University of Melbourne, Victoria, Australia
- * E-mail:
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McDonald FB, Skelly JR, O'Halloran KD. The β2 -adrenoceptor agonist terbutaline recovers rat pharyngeal dilator muscle force decline during severe hypoxia. Oral Dis 2014; 21:e121-7. [PMID: 24725067 DOI: 10.1111/odi.12247] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2014] [Revised: 03/28/2014] [Accepted: 04/08/2014] [Indexed: 11/28/2022]
Abstract
RATIONALE Obstructive sleep apnoea syndrome (OSAS) is a debilitating condition characterized by recurrent occlusions of the pharyngeal airway during sleep accompanied by arterial hypoxaemia. Upper airway muscle dysfunction is implicated in the pathophysiology of OSAS. Pharmacological agents that improve muscle contractile and endurance properties may have therapeutic value. AIM We tested the hypothesis that the β(2) -adrenoceptor agonist terbutaline improves rat sternohyoid muscle performance especially during hypoxic stress. METHODS Isometric contractile and endurance properties were examined ex vivo in Krebs solution at 35°C. Muscles were incubated in tissue baths under hyperoxic (95% O(2) /5% CO(2)) conditions in the absence (control) or presence of the β(2) -adrenoceptor agonist terbutaline (1 μM). In additional experiments under hypoxic (95% N(2) /5% CO(2)) conditions, the effects of terbutaline were examined in the presence of the β-adrenoceptor antagonist propranolol (1 μM). RESULTS Hypoxia significantly impaired sternohyoid force production. Terbutaline completely recovered hypoxic depression of force, an effect that was blocked by co-application with propranolol. CONCLUSION The β(2) -adrenoceptor agonist terbutaline completely recovers hypoxic depression of upper airway muscle force. β(2) -adrenoceptor agonists warrant investigation in animal models of OSAS reporting upper airway and diaphragm muscle dysfunction.
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Affiliation(s)
- F B McDonald
- School of Medicine and Medical Science, University College Dublin, Dublin, Ireland
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6
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Sobrian SK, Walters E. Enhanced Satellite Cell Activity in Aging Skeletal Muscle after Manual Acupuncture-Induced Injury. Chin Med 2014. [DOI: 10.4236/cm.2014.51004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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Koopman R, Ryall JG, Church JE, Lynch GS. The role of beta-adrenoceptor signaling in skeletal muscle: therapeutic implications for muscle wasting disorders. Curr Opin Clin Nutr Metab Care 2009; 12:601-6. [PMID: 19741516 DOI: 10.1097/mco.0b013e3283318a25] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
PURPOSE OF REVIEW The beta-adrenergic signaling pathway represents a novel therapeutic target for skeletal muscle wasting disorders due to its roles in regulating protein synthesis and degradation. beta-Adrenoceptor agonists (beta-agonists) have therapeutic potential for attenuating muscle wasting associated with sarcopenia (age-related muscle wasting), cancer cachexia, sepsis, disuse, burns, HIV-AIDS, chronic kidney or heart failure, and neuromuscular diseases such as the muscular dystrophies. This review describes the role of beta-adrenergic signaling in the mechanisms controlling muscle wasting due to its effects on protein synthesis, protein degradation, and muscle fiber phenotype. RECENT FINDINGS Stimulation of the beta-adrenergic signaling pathway with beta-agonists has therapeutic potential for muscle wasting since administration can elicit an anabolic response in skeletal muscle. As a consequence of their potent muscle anabolic actions, the effects of beta-agonist administration have been examined in several animal models and human conditions of muscle wasting in the hope of discovering a new therapeutic. The repartitioning characteristics of beta-agonists (increasing muscle mass and decreasing fat mass) have also made them attractive anabolic agents for use in livestock and by some athletes. However, potentially deleterious cardiovascular side-effects of beta-agonists have been identified and these will need to be obviated in order for the therapeutic potential of beta-agonists to be realized. SUMMARY Multiple studies have identified anticachectic effects of beta-agonists and their therapeutic potential for pathologic states when muscle protein hypercatabolism is indicated. Future studies examining beta-agonist administration for muscle wasting conditions need to separate beneficial effects on skeletal muscle from potentially deleterious effects on the heart and cardiovascular system.
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Affiliation(s)
- René Koopman
- Basic and Clinical Myology Laboratory, Department of Physiology, The University of Melbourne, Victoria, Australia
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8
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Lynch GS, Ryall JG. Role of beta-adrenoceptor signaling in skeletal muscle: implications for muscle wasting and disease. Physiol Rev 2008; 88:729-67. [PMID: 18391178 DOI: 10.1152/physrev.00028.2007] [Citation(s) in RCA: 295] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
The importance of beta-adrenergic signaling in the heart has been well documented, but it is only more recently that we have begun to understand the importance of this signaling pathway in skeletal muscle. There is considerable evidence regarding the stimulation of the beta-adrenergic system with beta-adrenoceptor agonists (beta-agonists). Although traditionally used for treating bronchospasm, it became apparent that some beta-agonists could increase skeletal muscle mass and decrease body fat. These so-called "repartitioning effects" proved desirable for the livestock industry trying to improve feed efficiency and meat quality. Studying beta-agonist effects on skeletal muscle has identified potential therapeutic applications for muscle wasting conditions such as sarcopenia, cancer cachexia, denervation, and neuromuscular diseases, aiming to attenuate (or potentially reverse) the muscle wasting and associated muscle weakness, and to enhance muscle growth and repair after injury. Some undesirable cardiovascular side effects of beta-agonists have so far limited their therapeutic potential. This review describes the physiological significance of beta-adrenergic signaling in skeletal muscle and examines the effects of beta-agonists on skeletal muscle structure and function. In addition, we examine the proposed beneficial effects of beta-agonist administration on skeletal muscle along with some of the less desirable cardiovascular effects. Understanding beta-adrenergic signaling in skeletal muscle is important for identifying new therapeutic targets and identifying novel approaches to attenuate the muscle wasting concomitant with many diseases.
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Affiliation(s)
- Gordon S Lynch
- Basic and Clinical Myology Laboratory, Department of Physiology, The University of Melbourne, Victoria, Australia.
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Burniston JG, Tan LB, Goldspink DF. Relative myotoxic and haemodynamic effects of the beta-agonists fenoterol and clenbuterol measured in conscious unrestrained rats. Exp Physiol 2006; 91:1041-9. [PMID: 16973691 PMCID: PMC1828613 DOI: 10.1113/expphysiol.2006.035014] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The beta(2)-adrenoceptor (beta(2)-AR) agonists clenbuterol and fenoterol have similar beneficial effects in animal models of heart failure. However, large doses of clenbuterol can induce cardiomyocyte death, and it is not known which of these agents has the most favourable therapeutic profile. We have investigated the cardiotoxicity of clenbuterol and fenoterol alongside that of isoprenaline, and compared their haemodynamic effects. Wistar rats (n = 6 per group) were subcutaneously injected with each beta-agonist (0.003-3 mmol kg(-1)) or saline, and cardiomyocyte apoptosis was detected by caspase 3 immunohistochemistry. In a separate experiment, rats (n = 4) were given equivalent doses to those used in the myotoxicity studies, in a randomized cross-over design, and their blood pressure recorded via radiotelemetry. Injection of 0.3 mmol kg(-1) fenoterol or isoprenaline, but not clenbuterol, induced significant cardiomyocyte apoptosis (0.4 +/- 0.05%; P < 0.05). At 3 mmol kg(-1), all agonists induced apoptosis (fenoterol, 1.1 +/- 0.1%; isoprenaline, 0.9 +/- 0.8%; and clenbuterol, 0.4 +/- 0.07%; P < 0.05). beta(1)-Adrenoceptor antagonism (10 mg kg(-1) bisoprolol) prevented 92% (P < 0.05) of apoptosis induced by all three agonists, but clenbuterol-induced apoptosis could also be prevented by 96% (P < 0.05) by beta(2)-AR antagonism (10 mg kg(-1) ICI 118 551). Clenbuterol decreased diastolic (1.3- to 1.6-fold; P < 0.05) and systolic blood pressure (1.3-fold; P < 0.05), and doses > 0.3 mmol kg(-1) increased heart rate (1.4-fold; P < 0.05). Fenoterol increased heart rate (1.2- to 1.4-fold; P < 0.05), and doses > 0.3 mmol kg(-1) decreased diastolic blood pressure (1.3-fold; P < 0.05). In conclusion, the cardiotoxicity of fenoterol was similar to isoprenaline and greater than clenbuterol, and fenoterol had less desirable haemodynamic effects.
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Affiliation(s)
- Jatin G Burniston
- Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Webster Street, Liverpool L3 2ET, UK.
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Baker DJ, Betik AC, Krause DJ, Hepple RT. No decline in skeletal muscle oxidative capacity with aging in long-term calorically restricted rats: effects are independent of mitochondrial DNA integrity. J Gerontol A Biol Sci Med Sci 2006; 61:675-84. [PMID: 16870628 DOI: 10.1093/gerona/61.7.675] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We investigated if calorie restriction (CR) preserved skeletal muscle oxidative capacity with aging after accounting for life span extension by CR, and determined if mitochondrial content, mitochondrial DNA integrity, and peroxisome proliferator-activated receptor gamma coactivator-1alpha (PGC-1alpha) were involved. Ad libitum-fed (AL) and CR animals representing young adult, late middle age, and senescence were studied. Whereas citrate synthase and complex IV activities were lower in plantaris and gastrocnemius muscle of young adult CR animals, in contrast to the 15%-40% decline in senescent AL animals, there was no decline with aging in CR animals. There was no decline in citrate synthase protein in gastrocnemius with aging in either group, suggesting that CR preserves oxidative capacity with aging by protecting mitochondrial function rather than content. This protection was independent of mitochondrial DNA damage between groups. However, there was a slower decline in PGC-1alpha gene expression with aging in CR versus AL animals, suggesting a better maintenance of mitochondrial biogenesis with aging in CR animals.
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Affiliation(s)
- David J Baker
- Faculty of Medicine, University of Calgary, Calgary, AB, T2N 1N4, Canada
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Baker DJ, Constantin-Teodosiu D, Jones SW, Timmons JA, Greenhaff PL. Chronic treatment with the beta(2)-adrenoceptor agonist prodrug BRL-47672 impairs rat skeletal muscle function by inducing a comprehensive shift to a faster muscle phenotype. J Pharmacol Exp Ther 2006; 319:439-46. [PMID: 16844843 DOI: 10.1124/jpet.106.107045] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Discovering approaches to maintain or improve muscle function (fatigue resistance) in patients with cachexia, postoperative weakness, and sarcopenia is of clinical importance. beta(2)-Agonist treatment increases muscle mass, yet it alters fiber proportions such that the net consequences on muscle function remain unclear. In the present study, we focus on the contractile and metabolic consequences of chronic treatment with the beta(2)-agonist prodrug BRL-47672 (BRL). Gastrocnemius-plantaris-soleus (GPS) muscles were harvested at rest and studied for fatigue characteristics during 4 and 20 s of isometric stimulation (30 Hz; 10 V; 200 ms) using the perfused hind limb model. BRL treatment increased GPS mass by 21% (P < 0.05), whereas greater fatigue occurred during 20 s of contraction (45% less work; P < 0.05). Phenotypically, BRL resulted in 17% more type IIb myosin heavy chain protein expression (P < 0.001) and greater adenine nucleotide catabolism during 20 s of contraction (P < 0.05). Chronic BRL treatment impaired maximal lipid oxidation capacity by 30% (P < 0.05) and reduced glutamate dehydrogenase activity by 15% (P < 0.05). We conclude that beta(2)-agonist induced muscle hypertrophy may be clinically limited as impaired energy metabolism and function occur, presumably as a consequence of the shift in muscle phenotype.
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Affiliation(s)
- David J Baker
- Centre for Integrated Systems Biology and Medicine, School of Biomedical Science, University of Nottingham, Nottingham, United Kingdom.
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McDaneld TG, Hannon K, Moody DE. Ankyrin repeat and SOCS box protein 15 regulates protein synthesis in skeletal muscle. Am J Physiol Regul Integr Comp Physiol 2006; 290:R1672-82. [PMID: 16424087 DOI: 10.1152/ajpregu.00239.2005] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Ankyrin repeat and SOCS box protein 15 (ASB15) is an Asb family member expressed predominantly in skeletal muscle. We have previously reported that ASB15 mRNA abundance decreases after administration of β-adrenergic receptor agonists. Because β-adrenergic receptor agonists are known to stimulate muscle hypertrophy, the objective of this study was to determine whether ASB15 regulates cellular processes that contribute to muscle growth. Stable myoblast C2C12 cells expressing full-length ASB15 (ASB15-FL) and ASB15 lacking the ankyrin repeat (ASB15-Ank) or SOCS box (ASB15-SOCS) motifs were evaluated for changes in proliferation, differentiation, protein synthesis, and protein degradation. Expression of ASB15-FL caused a delay in differentiation, followed by an increase in protein synthesis of ∼34% ( P < 0.05). A consistent effect of ASB15 overexpression was observed in vivo, where ectopic expression of ASB15 increased skeletal muscle fiber area ( P < 0.0001) after 9 days. Expression of ASB15-SOCS altered differentiation of myoblasts, resulting in detachment of cells from culture plates. Expression of ASB15-Ank increased protein degradation by 84 h of differentiation ( P < 0.05), and in vivo ectopic expression of an ASB15 construct lacking both the ankyrin repeat and SOCS box motifs decreased skeletal muscle fiber area ( P < 0.0001). Together, these results suggest ASB15 participates in the regulation of protein turnover and muscle cell development by stimulating protein synthesis and regulating differentiation of muscle cells. This is the first study to demonstrate a role for an Asb family member in skeletal muscle growth.
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Affiliation(s)
- T G McDaneld
- Department of Animal Sciences, Purdue University, West Lafayette, IN, USA
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