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Heemstra LA, Koch LG, Britton SL, Novak CM. Altered skeletal muscle sarco-endoplasmic reticulum Ca 2+-ATPase calcium transport efficiency after a thermogenic stimulus. Am J Physiol Regul Integr Comp Physiol 2022; 323:R628-R637. [PMID: 36094445 PMCID: PMC9602703 DOI: 10.1152/ajpregu.00173.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Revised: 09/01/2022] [Accepted: 09/01/2022] [Indexed: 01/22/2023]
Abstract
Exposure to predator threat induces a rapid and robust increase in skeletal muscle thermogenesis in rats. The central nervous system relays threat information to skeletal muscle through activation of the sympathetic nervous system, but muscle mechanisms mediating this thermogenesis remain unidentified. Given the relevance of sarcolipin-mediated futile calcium cycling through the sarco-endoplasmic reticulum Ca2+-ATPase (SERCA) pump to mammalian muscle nonshivering thermogenesis, we hypothesized that this plays a role in contextually induced muscle thermogenesis as well. This was assessed by measuring enzymatic activity of SERCA and sarcoplasmic reticulum Ca2+ transport, where the apparent coupling ratio (Ca2+ uptake rate divided by ATPase activity rate at a standard Ca2+ concentration) was predicted to decrease in association with muscle thermogenesis. Sprague-Dawley rats exposed to predator (ferret) odor (PO) showed a rapid decrease in the apparent coupling ratio in the soleus muscle, indicating SERCA uncoupling compared with control-odor-exposed rats. A rat model of high aerobic fitness and elevated muscle thermogenesis also demonstrated soleus muscle SERCA uncoupling relative to their obesity-prone, low-fitness counterparts. Both the high- and low-aerobic fitness rats showed soleus SERCA uncoupling with exposure to PO. Finally, no increase in sarcolipin expression in soleus muscle was detected with PO exposure. This dataset implicates muscle uncoupling of SERCA Ca2+ transport and ATP hydrolysis, likely through altered SERCA or sarcolipin function outside of translational regulation, as one contributor to the muscle thermogenesis provoked by exposure to predator threat. These data support the involvement of SERCA uncoupling in both muscle thermogenic induction and enhanced aerobic capacity.
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Affiliation(s)
- Lydia A Heemstra
- Department of Biological Sciences, Kent State University, Kent, Ohio
| | - Lauren G Koch
- Department of Physiology and Pharmacology, The University of Toledo College of Medicine and Life Sciences, Toledo, Ohio
| | - Steven L Britton
- Department of Anesthesiology, University of Michigan, Ann Arbor, Michigan
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan
| | - Colleen M Novak
- Department of Biological Sciences, Kent State University, Kent, Ohio
- School of Biomedical Sciences, Kent State University, Kent, Ohio
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2
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Ito N, Takatsu A, Ito H, Koike Y, Yoshioka K, Kamei Y, Imai SI. Slc12a8 in the lateral hypothalamus maintains energy metabolism and skeletal muscle functions during aging. Cell Rep 2022; 40:111131. [PMID: 35905718 DOI: 10.1016/j.celrep.2022.111131] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2022] [Revised: 05/01/2022] [Accepted: 07/01/2022] [Indexed: 12/20/2022] Open
Abstract
Sarcopenia and frailty are urgent socio-economic problems worldwide. Here we demonstrate a functional connection between the lateral hypothalamus (LH) and skeletal muscle through Slc12a8, a recently identified nicotinamide mononucleotide transporter, and its relationship to sarcopenia and frailty. Slc12a8-expressing cells are mainly localized in the LH. LH-specific knockdown of Slc12a8 in young mice decreases activity-dependent energy and carbohydrate expenditure and skeletal muscle functions, including muscle mass, muscle force, intramuscular glycolysis, and protein synthesis. LH-specific Slc12a8 knockdown also decreases sympathetic nerve signals at neuromuscular junctions and β2-adrenergic receptors in skeletal muscle, indicating the importance of the LH-sympathetic nerve-β2-adrenergic receptor axis. LH-specific overexpression of Slc12a8 in aged mice significantly ameliorates age-associated decreases in energy expenditure and skeletal muscle functions. Our results highlight an important role of Slc12a8 in the LH for regulation of whole-body metabolism and skeletal muscle functions and provide insights into the pathogenesis of sarcopenia and frailty during aging.
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Affiliation(s)
- Naoki Ito
- AMED Frailty Research Laboratory (Teijin), AMED Cyclic Innovation for Clinical Empowerment (CiCLE), Osaka, Japan; Laboratory of Molecular Life Science, Institute of Biomedical Research and Innovation (IBRI), Foundation for Biomedical Research and Innovation (FBRI), Kobe, Japan
| | - Ai Takatsu
- AMED Frailty Research Laboratory (Teijin), AMED Cyclic Innovation for Clinical Empowerment (CiCLE), Osaka, Japan; Laboratory of Molecular Life Science, Institute of Biomedical Research and Innovation (IBRI), Foundation for Biomedical Research and Innovation (FBRI), Kobe, Japan
| | - Hiromi Ito
- AMED Frailty Research Laboratory (Teijin), AMED Cyclic Innovation for Clinical Empowerment (CiCLE), Osaka, Japan; Laboratory of Molecular Life Science, Institute of Biomedical Research and Innovation (IBRI), Foundation for Biomedical Research and Innovation (FBRI), Kobe, Japan
| | - Yuka Koike
- AMED Frailty Research Laboratory (Teijin), AMED Cyclic Innovation for Clinical Empowerment (CiCLE), Osaka, Japan; Laboratory of Molecular Life Science, Institute of Biomedical Research and Innovation (IBRI), Foundation for Biomedical Research and Innovation (FBRI), Kobe, Japan
| | - Kiyoshi Yoshioka
- Institute for Research on Productive Aging (IRPA), Tokyo, Japan; Laboratory of Molecular Nutrition, Graduate School of Life and Environmental Sciences, Kyoto Prefectural University, Kyoto, Japan
| | - Yasutomi Kamei
- Laboratory of Molecular Nutrition, Graduate School of Life and Environmental Sciences, Kyoto Prefectural University, Kyoto, Japan
| | - Shin-Ichiro Imai
- AMED Frailty Research Laboratory (Teijin), AMED Cyclic Innovation for Clinical Empowerment (CiCLE), Osaka, Japan; Laboratory of Molecular Life Science, Institute of Biomedical Research and Innovation (IBRI), Foundation for Biomedical Research and Innovation (FBRI), Kobe, Japan; Department of Developmental Biology, Department of Medicine, Washington University School of Medicine, St. Louis, MO, USA.
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Padilha CS, Figueiredo C, Deminice R, Krüger K, Seelaender M, Rosa‐Neto JC, Lira FS. Costly immunometabolic remodelling in disused muscle buildup through physical exercise. Acta Physiol (Oxf) 2022; 234:e13782. [PMID: 34990078 DOI: 10.1111/apha.13782] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2021] [Revised: 11/12/2021] [Accepted: 01/01/2022] [Indexed: 11/28/2022]
Abstract
The mechanisms underlying the immunometabolic disturbances during skeletal muscle atrophy caused by a plethora of circumstances ranging from hospitalization to spaceflight missions remain unknown. Here, we outline the possible pathways that might be dysregulated in such conditions and assess the potential of physical exercise to mitigate and promote the recovery of muscle morphology, metabolism and function after intervals of disuse. Studies applying exercise to attenuate disuse-induced muscle atrophy have shown a pivotal role of circulating myokines in the activation of anabolic signalling pathways. These muscle-derived factors induce accretion of contractile proteins in the myofibers, and at the same time decrease protein breakdown and loss. Regular exercise plays a crucial role in re-establishing adequate immunometabolism and increasing the migration and presence in the muscle of macrophages with an anti-inflammatory phenotype (M2) and T regulatory cells (Tregs) after disease-induced muscle loss. Additionally, the switch in metabolic pathways (glycolysis to oxidative phosphorylation [OXPHOS]) is important for achieving rapid metabolic homeostasis during muscle regeneration. In this review, we discuss the molecular aspects of the immunometabolic response elicited by exercise during skeletal muscle regeneration. There is not, nevertheless, consensus on a single optimal intensity of exercise required to improve muscle strength, mass and functional capacity owing to the wide range of exercise protocols studied so far. Despite the absence of agreement on the specific strategy, physical exercise appears as a powerful complementary strategy to attenuate the harmful effects of muscle disuse in different scenarios.
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Affiliation(s)
- Camila S. Padilha
- Exercise and Immunometabolism Research Group Post‐graduation Program in Movement Sciences Department of Physical Education Universidade Estadual Paulista (UNESP) Presidente Prudente Brazil
| | - Caique Figueiredo
- Exercise and Immunometabolism Research Group Post‐graduation Program in Movement Sciences Department of Physical Education Universidade Estadual Paulista (UNESP) Presidente Prudente Brazil
| | - Rafael Deminice
- Laboratory of Biochemistry Exercise Department of Physical Education Faculty of Physical Education and Sport State University of Londrina Londrina Brazil
| | - Karsten Krüger
- Institute of Sports Science Department of Exercise Physiology and Sports Therapy University of Giessen Giessen Germany
| | - Marília Seelaender
- Cancer Metabolism Research Group Department of Surgery LIM26‐HC Medical School University of São Paulo São Paulo Brazil
| | - José Cesar Rosa‐Neto
- Department of Cell and Developmental Biology University of São Paulo São Paulo Brazil
| | - Fabio S. Lira
- Exercise and Immunometabolism Research Group Post‐graduation Program in Movement Sciences Department of Physical Education Universidade Estadual Paulista (UNESP) Presidente Prudente Brazil
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4
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Qaisar R, Qayum M, Muhammad T. Reduced sarcoplasmic reticulum Ca 2+ ATPase activity underlies skeletal muscle wasting in asthma. Life Sci 2021; 273:119296. [PMID: 33675897 DOI: 10.1016/j.lfs.2021.119296] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2021] [Revised: 02/10/2021] [Accepted: 02/20/2021] [Indexed: 12/13/2022]
Abstract
AIMS Skeletal muscle mass and strength are reduced in asthma and contribute to compromised functional capacity in asthmatic patients. However, an effective pharmacological intervention remains elusive, partly because molecular mechanisms dictating muscle decline in asthma are not known. MATERIALS We investigated the potential contribution(s) of skeletal muscle sarcoplasmic reticulum Ca2+ ATPase (SERCA) to muscle atrophy and weakness in asthmatic patients. Quadriceps muscle biopsies were taken from 58 to 72 years old male patients with mild and advanced asthma and the SERCA activity was analyzed in association with cellular redox environment and myonuclear domain (MND) size. KEY FINDINGS Maximal SERCA activity was reduced in skeletal muscles of mild and advanced asthmatics and was associated with reduced expression of SERCA2 protein and upregulation of sarcolipin, a SERCA inhibitory lipoprotein. We also found downregulation of Ca2+ release protein calstabin and upregulation of Ca2+ buffer, calsequestrin in skeletal muscles of asthmatic patients. The atrophic single muscle fibers had smaller cytoplasmic domains per myonucleus possibly indicating the reduced transcriptional reserves of individual myonuclei. Plasma periostin and CAF22 levels were significantly elevated in asthmatic patients and showed a strong correlation with hand-grip strength. These changes were accompanied by substantially elevated markers of global oxidative stress including lipid peroxidation and mitochondrial ROS production. CONCLUSION Taken together, our data suggest that muscle weakness and atrophy in asthma is in part driven by SERCA dysfunction and oxidative stress. The data propose SERCA dysfunction as a therapeutic intervention to address muscle decline in asthma.
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Affiliation(s)
- Rizwan Qaisar
- Basic Medical Sciences, College of Medicine, University of Sharjah, Sharjah, United Arab Emirates.
| | - Mughal Qayum
- Department of Pharmacy, Kohat University of Science & Technology, Kohat 26000, Pakistan
| | - Tahir Muhammad
- Department of Biochemistry, Gomal Medical College, Dera Ismail Khan, Pakistan
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5
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Restoration of Sarcoplasmic Reticulum Ca 2+ ATPase (SERCA) Activity Prevents Age-Related Muscle Atrophy and Weakness in Mice. Int J Mol Sci 2020; 22:ijms22010037. [PMID: 33375170 PMCID: PMC7792969 DOI: 10.3390/ijms22010037] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2020] [Revised: 12/18/2020] [Accepted: 12/19/2020] [Indexed: 02/08/2023] Open
Abstract
Sarcopenia has a significant negative impact on healthspan in the elderly and effective pharmacologic interventions remain elusive. We have previously demonstrated that sarcopenia is associated with reduced activity of the sarcoplasmic reticulum Ca2+ ATPase (SERCA) pump. We asked whether restoring SERCA activity using pharmacologic activation in aging mice could mitigate the sarcopenia phenotype. We treated 16-month male C57BL/6J mice with vehicle or CDN1163, an allosteric SERCA activator, for 10 months. At 26 months, maximal SERCA activity was reduced 41% in gastrocnemius muscle in vehicle-treated mice but maintained in old CDN1163 treated mice. Reductions in gastrocnemius mass (9%) and in vitro specific force generation in extensor digitorum longus muscle (11%) in 26 versus 16-month-old wild-type mice were also reversed by CDN1163. CDN1163 administered by intra-peritoneal injection also prevented the increase in mitochondrial ROS production in gastrocnemius muscles of aged mice. Transcriptomic analysis revealed that these effects are at least in part mediated by enhanced cellular energetics by activation of PGC1-α, UCP1, HSF1, and APMK and increased regenerative capacity by suppression of MEF2C and p38 MAPK signaling. Together, these exciting findings are the first to support that pharmacological targeting of SERCA can be an effective therapy to counter age-related muscle dysfunction.
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6
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Jannas-Vela S, Brownell S, Petrick HL, Heigenhauser GJF, Spriet LL, Holloway GP. Assessment of Na+/K+ ATPase Activity in Small Rodent and Human Skeletal Muscle Samples. Med Sci Sports Exerc 2020; 51:2403-2409. [PMID: 31634296 DOI: 10.1249/mss.0000000000002063] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
INTRODUCTION In skeletal muscle, the Na/K ATPase (NKA) plays essential roles in processes linked to muscle contraction, fatigue, and energy metabolism; however, very little information exists regarding the regulation of NKA activity. The scarcity of information regarding NKA function in skeletal muscle likely stems from methodological constraints, as NKA contributes minimally to total cellular ATP utilization, and therefore contamination from other ATPases prevents the assessment of NKA activity in muscle homogenates. Here we introduce a method that improves accuracy and feasibility for the determination of NKA activity in small rodent muscle samples (5-10 mg) and in human skeletal muscle. METHODS Skeletal muscle homogenates from mice (n = 6) and humans (n = 3) were used to measure NKA and sarcoplasmic reticulum Ca ATPase (SERCA) activities with the addition of specific ATPase inhibitors to minimize "background noise." RESULTS We observed that myosin ATPase activity was the major interfering factor for estimation of NKA activity in skeletal muscle homogenates, as the addition of 25 μM of blebbistatin, a specific myosin ATPase inhibitor, considerably minimized "background noise" (threefold) and enabled the determination of NKA maximal activity with values three times higher than previously reported. The specificity of the assay was demonstrated after the addition of 2 mM ouabain, which completely inhibited NKA. On the other hand, the addition of blebbistatin did not affect the ability to measure SERCA function. The coefficient of variation for NKA and SERCA assays were 6.2% and 4.4%, respectively. CONCLUSION The present study has improved the methodology to determine NKA activity. We further show the feasibility of measuring NKA and SERCA activities from a common muscle homogenate. This methodology is expected to aid in our long-term understanding of how NKA affects skeletal muscle metabolic homeostasis and contractile function in diverse situations.
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Affiliation(s)
- Sebastian Jannas-Vela
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, CANADA.,Exercise Science Laboratory, Faculty of Medicine, School of Kinesiology, Universidad Finis Terrae, Santiago, CHILE
| | - Stuart Brownell
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, CANADA
| | - Heather L Petrick
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, CANADA
| | | | - Lawrence L Spriet
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, CANADA
| | - Graham P Holloway
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, CANADA
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7
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The β-arrestin-biased β-adrenergic receptor blocker carvedilol enhances skeletal muscle contractility. Proc Natl Acad Sci U S A 2020; 117:12435-12443. [PMID: 32414934 DOI: 10.1073/pnas.1920310117] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
A decrease in skeletal muscle strength and functional exercise capacity due to aging, frailty, and muscle wasting poses major unmet clinical needs. These conditions are associated with numerous adverse clinical outcomes including falls, fractures, and increased hospitalization. Clenbuterol, a β2-adrenergic receptor (β2AR) agonist enhances skeletal muscle strength and hypertrophy; however, its clinical utility is limited by side effects such as cardiac arrhythmias mediated by G protein signaling. We recently reported that clenbuterol-induced increases in contractility and skeletal muscle hypertrophy were lost in β-arrestin 1 knockout mice, implying that arrestins, multifunctional adapter and signaling proteins, play a vital role in mediating the skeletal muscle effects of β2AR agonists. Carvedilol, classically defined as a βAR antagonist, is widely used for the treatment of chronic systolic heart failure and hypertension, and has been demonstrated to function as a β-arrestin-biased ligand for the β2AR, stimulating β-arrestin-dependent but not G protein-dependent signaling. In this study, we investigated whether treatment with carvedilol could enhance skeletal muscle strength via β-arrestin-dependent pathways. In a murine model, we demonstrate chronic treatment with carvedilol, but not other β-blockers, indeed enhances contractile force in skeletal muscle and this is mediated by β-arrestin 1. Interestingly, carvedilol enhanced skeletal muscle contractility despite a lack of effect on skeletal muscle hypertrophy. Our findings suggest a potential unique clinical role of carvedilol to stimulate skeletal muscle contractility while avoiding the adverse effects with βAR agonists. This distinctive signaling profile could present an innovative approach to treating sarcopenia, frailty, and secondary muscle wasting.
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8
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Yoshihara T, Machida S, Tsuzuki T, Kakigi R, Chang SW, Sugiura T, Naito H. Age-related changes in histone modification in rat gastrocnemius muscle. Exp Gerontol 2019; 125:110658. [PMID: 31302168 DOI: 10.1016/j.exger.2019.110658] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2019] [Revised: 06/26/2019] [Accepted: 07/11/2019] [Indexed: 12/28/2022]
Abstract
Changes in histone acetylation and methylation status with aging affect gene expression and phenotype in several tissues; however, age-related changes in histone modification in the skeletal muscle have not been elucidated yet. This study investigated age-related global changes in histone modification in rat gastrocnemius muscle. Male Wistar rats (n = 28) were assigned to one of four age groups (n = 7 per group) corresponding to different life stages: 3 months old (3-mo; young), 6 months old (adult), 12 months old (12-mo; middle-aged), and 24 months old (24-mo; old). The gastrocnemius muscle was removed and global histone modification (acetylation and tri-methylation) at K9 and K27 was evaluated by western blotting. Relative muscle mass decreased in the 12- and 24-mo rats accompanied with reduction in type IIb myosin heavy chain isoforms and Myh4 (MHC IIB) mRNA expression. Histone H3 acetylation decreased in an age-dependent manner, with lower levels in 12- and 24-mo groups than in the 3-mo group. K9 and K27 acetylation decreased with age. Although there was no significant change in K27 tri-methylation, K9 tri-methylation showed an age-dependent decline. Histone modification status (acetylation at K9 and K27 and tri-methylation at K9) was positively associated with relative gastrocnemius muscle weight, the percentage of type IIb myosin heavy chain isoform, myosin heavy chain type IIb protein expression, and the level of Myh4 mRNA. Thus, global histone H3 methylation and acetylation decrease with age, and the latter might be associated with age-related muscle atrophy of rat gastrocnemius muscle.
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Affiliation(s)
- Toshinori Yoshihara
- Graduate School of Health and Sports Science, Juntendo University, 1-1 Hirakagakuendai, Inzai, Chiba 270-1695, Japan.
| | - Shuichi Machida
- Graduate School of Health and Sports Science, Juntendo University, 1-1 Hirakagakuendai, Inzai, Chiba 270-1695, Japan.
| | - Takamasa Tsuzuki
- Faculty of Pharmacy, Meijo University, 150 Yagotoyama, Tempaku-ku, Nagoya, Aichi 468-8503, Japan.
| | - Ryo Kakigi
- Faculty of Medicine, Juntendo University, 2-1-1 Hongo, Bunkyo-ku, Tokyo 113-8421, Japan.
| | - Shuo-Wen Chang
- Graduate School of Health and Sports Science, Juntendo University, 1-1 Hirakagakuendai, Inzai, Chiba 270-1695, Japan.
| | - Takao Sugiura
- Faculty of Education, Yamaguchi University, 1677-1 Yoshida, Yamaguchi 753-8513, Japan.
| | - Hisashi Naito
- Graduate School of Health and Sports Science, Juntendo University, 1-1 Hirakagakuendai, Inzai, Chiba 270-1695, Japan.
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9
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Kim J, Grotegut CA, Wisler JW, Li T, Mao L, Chen M, Chen W, Rosenberg PB, Rockman HA, Lefkowitz RJ. β-arrestin 1 regulates β2-adrenergic receptor-mediated skeletal muscle hypertrophy and contractility. Skelet Muscle 2018; 8:39. [PMID: 30591079 PMCID: PMC6309084 DOI: 10.1186/s13395-018-0184-8] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2018] [Accepted: 11/22/2018] [Indexed: 01/14/2023] Open
Abstract
BACKGROUND β2-adrenergic receptors (β2ARs) are the target of catecholamines and play fundamental roles in cardiovascular, pulmonary, and skeletal muscle physiology. An important action of β2AR stimulation on skeletal muscle is anabolic growth, which has led to the use of agonists such as clenbuterol by athletes to enhance muscle performance. While previous work has demonstrated that β2ARs can engage distinct signaling and functional cascades mediated by either G proteins or the multifunctional adaptor protein, β-arrestin, the precise role of β-arrestin in skeletal muscle physiology is not known. Here, we tested the hypothesis that agonist activation of the β2AR by clenbuterol would engage β-arrestin as a key transducer of anabolic skeletal muscle growth. METHODS The contractile force of isolated extensor digitorum longus muscle (EDL) and calcium signaling in isolated flexor digitorum brevis (FDB) fibers were examined from the wild-type (WT) and β-arrestin 1 knockout mice (βarr1KO) followed by chronic administration of clenbuterol (1 mg/kg/d). Hypertrophic responses including fiber composition and fiber size were examined by immunohistochemical imaging. We performed a targeted phosphoproteomic analysis on clenbuterol stimulated primary cultured myoblasts from WT and βarr1KO mice. Statistical significance was determined by using a two-way analysis with Sidak's or Tukey's multiple comparison test and the Student's t test. RESULTS Chronic administration of clenbuterol to WT mice enhanced the contractile force of EDL muscle and calcium signaling in isolated FDB fibers. In contrast, when administered to βarr1KO mice, the effect of clenbuterol on contractile force and calcium influx was blunted. While clenbuterol-induced hypertrophic responses were observed in WT mice, this response was abrogated in mice lacking β-arrestin 1. In primary cultured myoblasts, clenbuterol-stimulated phosphorylation of multiple pro-hypertrophy proteins required the presence of β-arrestin 1. CONCLUSIONS We have identified a previously unappreciated role for β-arrestin 1 in mediating β2AR-stimulated skeletal muscle growth and strength. We propose these findings could have important implications in the design of future pharmacologic agents aimed at reversing pathological conditions associated with skeletal muscle wasting.
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Affiliation(s)
- Jihee Kim
- Department of Medicine, Duke University Medical Center, Durham, NC, USA
| | - Chad A Grotegut
- Department of Obstetrics and Gynecology, Duke University Medical Center, Durham, NC, USA
| | - James W Wisler
- Department of Medicine, Duke University Medical Center, Durham, NC, USA
| | - Tianyu Li
- Department of Medicine, Duke University Medical Center, Durham, NC, USA
| | - Lan Mao
- Department of Medicine, Division of Cardiology and Duke Cardiovascular Physiology Core, Duke University Medical Center, Durham, NC, USA
| | - Minyong Chen
- Department of Medicine, Duke University Medical Center, Durham, NC, USA
| | - Wei Chen
- Department of Medicine, Duke University Medical Center, Durham, NC, USA
| | - Paul B Rosenberg
- Department of Medicine, Duke University Medical Center, Durham, NC, USA
| | - Howard A Rockman
- Department of Medicine, Duke University Medical Center, Durham, NC, USA.,Department of Cell Biology, Duke University Medical Center, Durham, NC, USA.,Departments of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC, USA
| | - Robert J Lefkowitz
- Department of Medicine, Duke University Medical Center, Durham, NC, USA. .,Department of Biochemistry, Duke University Medical Center, Durham, NC, USA. .,Howard Hughes Medical Institute, Duke University Medical Center, Durham, NC, USA.
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10
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Qaisar R, Bhaskaran S, Premkumar P, Ranjit R, Natarajan KS, Ahn B, Riddle K, Claflin DR, Richardson A, Brooks SV, Van Remmen H. Oxidative stress-induced dysregulation of excitation-contraction coupling contributes to muscle weakness. J Cachexia Sarcopenia Muscle 2018; 9:1003-1017. [PMID: 30073804 PMCID: PMC6204588 DOI: 10.1002/jcsm.12339] [Citation(s) in RCA: 51] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/14/2018] [Accepted: 06/25/2018] [Indexed: 12/20/2022] Open
Abstract
BACKGROUND We have previously shown that the deletion of the superoxide scavenger, CuZn superoxide dismutase, in mice (Sod1-/- mice) results in increased oxidative stress and an accelerated loss of skeletal muscle mass and force that mirror the changes seen in old control mice. The goal of this study is to define the effect of oxidative stress and ageing on muscle weakness and the Excitation Contraction (EC) coupling machinery in age-matched adult (8-10 months) wild-type (WT) and Sod1-/- mice in comparison with old (25-28 months) WT mice. METHODS In vitro contractile assays were used to measure muscle contractile parameters. The activity of the sarcoplasmic reticulum Ca2+ ATPase (SERCA) pump was measured using an NADH-linked enzyme assay. Immunoblotting and immunofluorescence techniques were used to measure protein expression, and real-time reverse transcription PCR was used to measure gene expression. RESULTS The specific force generated by the extensor digitorum longus muscle was reduced in the Sod1-/- and old WT mice compared with young WT mice along with significant prolongation of time to peak force, increased half relaxation time, and disruption of intracellular calcium handling. The maximal activity of the SERCA calcium uptake pump was significantly reduced in gastrocnemius muscle from both old WT (≈14%) and adult Sod1-/- (≈33%) mice compared with young WT mice along with increased expression of sarcolipin, a known inhibitor of SERCA activity. Protein levels of the voltage sensor and calcium uptake channel proteins dihydropyridine receptor α1 and SERCA2 were significantly elevated (≈45% and ≈57%, respectively), while the ratio of calstabin, a channel stabilizing protein, to ryanodine receptor was significantly reduced (≈21%) in Sod1-/- mice compared with young WT mice. The changes in calcium handling were accompanied by substantially elevated levels of global protein carbonylation and lipid peroxidation. CONCLUSIONS Our data suggest that the muscle weakness in Sod1-/- and old WT mice is in part driven by reactive oxygen species-mediated EC uncoupling and supports a role for reduced SERCA pump activity in compromised muscle function. The novel quantitative mechanistic data provided here can lead to potential therapeutic interventions of SERCA dysfunction for sarcopenia and muscle diseases.
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Affiliation(s)
- Rizwan Qaisar
- Aging and Metabolism Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK, USA
| | - Shylesh Bhaskaran
- Aging and Metabolism Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK, USA
| | - Pavithra Premkumar
- Aging and Metabolism Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK, USA
| | - Rojina Ranjit
- Aging and Metabolism Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK, USA
| | | | - Bumsoo Ahn
- Aging and Metabolism Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK, USA
| | - Kaitlyn Riddle
- Aging and Metabolism Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK, USA
| | - Dennis R Claflin
- Department of Surgery, Section of Plastic Surgery, University of Michigan, Ann Arbor, MI, USA.,Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, USA
| | - Arlan Richardson
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, USA.,Oklahoma City VA Medical Center, Oklahoma City, OK, USA.,Department of Geriatric Medicine and the Reynolds Oklahoma Center of Aging, Oklahoma University Health Science Center, Oklahoma City, OK, USA
| | - Susan V Brooks
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, MI, USA
| | - Holly Van Remmen
- Aging and Metabolism Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK, USA.,Oklahoma City VA Medical Center, Oklahoma City, OK, USA
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11
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McBride MJ, Foley KP, D'Souza DM, Li YE, Lau TC, Hawke TJ, Schertzer JD. The NLRP3 inflammasome contributes to sarcopenia and lower muscle glycolytic potential in old mice. Am J Physiol Endocrinol Metab 2017; 313:E222-E232. [PMID: 28536183 PMCID: PMC5582883 DOI: 10.1152/ajpendo.00060.2017] [Citation(s) in RCA: 59] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/21/2017] [Revised: 04/17/2017] [Accepted: 05/18/2017] [Indexed: 01/09/2023]
Abstract
The mechanisms underpinning decreased skeletal muscle strength and slowing of movement during aging are ill-defined. "Inflammaging," increased inflammation with advancing age, may contribute to aspects of sarcopenia, but little is known about the participatory immune components. We discovered that aging was associated with increased caspase-1 activity in mouse skeletal muscle. We hypothesized that the caspase-1-containing NLRP3 inflammasome contributes to sarcopenia in mice. Male C57BL/6J wild-type (WT) and NLRP3-/- mice were aged to 10 (adult) and 24 mo (old). NLRP3-/- mice were protected from decreased muscle mass (relative to body mass) and decreased size of type IIB and IIA myofibers, which occurred between 10 and 24 mo of age in WT mice. Old NLRP3-/- mice also had increased relative muscle strength and endurance and were protected from age-related increases in the number of myopathic fibers. We found no evidence of age-related or NLRP3-dependent changes in markers of systemic inflammation. Increased caspase-1 activity was associated with GAPDH proteolysis and reduced GAPDH enzymatic activity in skeletal muscles from old WT mice. Aging did not alter caspase-1 activity, GAPDH proteolysis, or GAPDH activity in skeletal muscles of NLRP3-/- mice. Our results show that the NLRP3 inflammasome participates in age-related loss of muscle glycolytic potential. Deletion of NLRP3 mitigates both the decline in glycolytic myofiber size and the reduced activity of glycolytic enzymes in muscle during aging. We propose that the etiology of sarcopenia involves direct communication between immune responses and metabolic flux in skeletal muscle.
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Affiliation(s)
- Marin Jane McBride
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Ontario, Canada
| | - Kevin P Foley
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Ontario, Canada
- Farncombe Family Digestive Health Research Institute, McMaster University, Hamilton, Ontario, Canada; and
| | - Donna M D'Souza
- Department of Pathology and Molecular Medicine, McMaster University, Hamilton, Ontario, Canada
| | - Yujin E Li
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Ontario, Canada
| | - Trevor C Lau
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Ontario, Canada
- Farncombe Family Digestive Health Research Institute, McMaster University, Hamilton, Ontario, Canada; and
| | - Thomas J Hawke
- Department of Pathology and Molecular Medicine, McMaster University, Hamilton, Ontario, Canada
| | - Jonathan D Schertzer
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Ontario, Canada;
- Farncombe Family Digestive Health Research Institute, McMaster University, Hamilton, Ontario, Canada; and
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12
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Almundarij TI, Gavini CK, Novak CM. Suppressed sympathetic outflow to skeletal muscle, muscle thermogenesis, and activity energy expenditure with calorie restriction. Physiol Rep 2017; 5:5/4/e13171. [PMID: 28242830 PMCID: PMC5328781 DOI: 10.14814/phy2.13171] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2017] [Accepted: 01/29/2017] [Indexed: 12/21/2022] Open
Abstract
During weight loss, adaptive thermogenesis occurs where energy expenditure (EE) is suppressed beyond that predicted for the smaller body size. Here, we investigated the contributions of resting and nonresting EE to the reduced total EE seen after 3 weeks of 50% calorie restriction (CR) in rats, focusing on activity‐associated EE, muscle thermogenesis, and sympathetic outflow. Prolonged food restriction resulted in a 42% reduction in daily EE, through a 40% decrease in resting EE, and a 48% decline in nonresting EE. These decreases in EE were significant even when the reductions in body weight and lean mass were taken into account. Along with a decreased caloric need for low‐to‐moderate‐intensity treadmill activity with 50% CR, baseline and activity‐related muscle thermogenesis were also suppressed, though the ability to increase muscle thermogenesis above baseline levels was not compromised. When sympathetic drive was measured by assessing norepinephrine turnover (NETO), 50% CR was found to decrease NETO in three of the four muscle groups examined, whereas elevated NETO was found in white adipose tissue of food‐restricted rats. Central activation of melanocortin 4 receptors in the ventromedial hypothalamus stimulated this pathway, enhancing activity EE; this was not compromised by 50% CR. These data suggest that suppressed activity EE contributes to adaptive thermogenesis during energy restriction. This may stem from decreased sympathetic drive to skeletal muscle, increasing locomotor efficiency and reducing skeletal muscle thermogenesis. The capacity to increase activity EE in response to central stimuli is retained, however, presenting a potential target for preventing weight regain.
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Affiliation(s)
- Tariq I Almundarij
- College of Agriculture and Veterinary Medicine, Al Qassim University, Buraydah, Al-Qassim Province, Saudi Arabia.,Department of Biological Sciences, Kent State University, Kent, Ohio
| | - Chaitanya K Gavini
- Department of Cell and Molecular Physiology, Stritch School of Medicine, Loyola University Chicago, Maywood, Illinois.,School of Biomedical Sciences, Kent State University, Kent, Ohio
| | - Colleen M Novak
- Department of Biological Sciences, Kent State University, Kent, Ohio .,School of Biomedical Sciences, Kent State University, Kent, Ohio
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13
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Choi SJ. Age-related functional changes and susceptibility to eccentric contraction-induced damage in skeletal muscle cell. Integr Med Res 2016; 5:171-175. [PMID: 28462114 PMCID: PMC5390413 DOI: 10.1016/j.imr.2016.05.004] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2016] [Revised: 05/12/2016] [Accepted: 05/12/2016] [Indexed: 01/30/2023] Open
Abstract
Depending upon external loading conditions, skeletal muscles can either shorten, lengthen, or remain at a fixed length as they produce force. Fixed-end or isometric contractions stabilize joints and allow muscles to act as active struts during locomotion. Active muscles dissipate energy when they are lengthened by an external force that exceeds their current force producing capacity. These unaccustomed eccentric activities often lead to muscle weakness, soreness, and inflammation. During aging, the ability to produce force under these conditions is reduced and appears to be due to not only reductions in muscle mass but also to alterations in the basic mechanisms of contraction. These alterations include impairments in the excitation–contraction process, and the action of the cross-bridges. Also, it is well known that age-related skeletal muscle atrophy is characterized by a preferential atrophy of fast fibers, and increased susceptibility to fast muscle fiber when aged muscles are exposed to eccentric contraction followed by the impaired recovery process has been reported. Taken together, the selective loss of fast muscle fiber in aged muscle could be affected by eccentric-induced muscle damage, which has significant implication to identify the etiology of the age-related functional changes. Therefore, in this review the alteration of age-related muscle function and its impact to/of eccentric induced muscle damage and recovery will be addressed in detail.
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Affiliation(s)
- Seung-Jun Choi
- Division of Sports and Health Science, College of Art, Kyungsung University, 309 Suyeong-ro, Nam-Gu, Busan 48434, Republic of Korea.
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14
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Davies P, Grace FM, Lewis MP, Sculthorpe N. Observation of Age-Related Decline in the Performance of the Transverse Abdominis Muscle. PM R 2015; 8:45-50. [PMID: 26070806 DOI: 10.1016/j.pmrj.2015.05.023] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2014] [Revised: 05/20/2015] [Accepted: 05/29/2015] [Indexed: 10/23/2022]
Abstract
BACKGROUND Previous research has shown that the performance of skeletal muscle declines with advancing age. Coordination of the transverse abdominis (TrA), a deep postural muscle, has been shown to be reduced in persons with low back pain. No previous research has studied the effect of age on the activation on this muscle. OBJECTIVE To assess the effect of age on TrA activation in response to rapid arm abduction. DESIGN Cross-sectional cohort study. SETTING University exercise physiology laboratory. PARTICIPANTS A total of 18 adult men (aged 27 ± 7.0 years) for the younger group and 11 older adults (5 men and 6 women, aged 59.6 ± 4.0 years) were recruited for this study. METHOD Participants were positioned on a treatment table and performed a series of rapid arm abduction movements with their right arm while the activation of the TrA muscle was recorded using ultrasound imaging. Onset of arm abduction was measured using surface electromyography and synchronized with the ultrasound through the ultrasound unit's electrocardiogram channel. The mean time difference between the 2 events was calculated during post-hoc analysis. MAIN OUTCOME MEASUREMENTS A Mann-Whitney test was performed to test for differences in the onset performance of the TrA muscle between the 2 groups. RESULTS Results showed that the older group was significantly slower than the younger group in engaging their TrA in response to the rapid arm abduction (P = .036). A separate analysis of the older group data showed that no significant differences existed between the male and female participants that could potentially have acted as a confounding factor for the main finding (P = .126). CONCLUSIONS This study shows that older adults were slower than younger adults in activating their TrA muscle in response to rapid arm abduction. This delay has the potential to lead to increased occasions when the low back is unprotected, increasing the likelihood of injury or low back pain.
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Affiliation(s)
- Paul Davies
- University of Wolverhampton, Institute of Sport, Gorway Road, Walsall, West Midlands WS1 3BD, United Kingdom(∗).
| | - Fergal M Grace
- Institute of Clinical Exercise and Health Science, University of the West of Scotland, Hamilton, Scotland(†)
| | - Mark P Lewis
- National Centre for Sport and Exercise Medicine, School of Sport, Exercise and Health Science, Loughborough University, Loughborough, UK(‡)
| | - Nicholas Sculthorpe
- Institute of Clinical Exercise and Health Science, University of the West of Scotland, Hamilton, Scotland(¶)
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15
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Kung TA, Cederna PS, van der Meulen JH, Urbanchek MG, Kuzon WM, Faulkner JA. Motor unit changes seen with skeletal muscle sarcopenia in oldest old rats. J Gerontol A Biol Sci Med Sci 2013; 69:657-65. [PMID: 24077596 DOI: 10.1093/gerona/glt135] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Sarcopenia leads to many changes in skeletal muscle that contribute to atrophy, force deficits, and subsequent frailty. The purpose of this study was to characterize motor unit remodeling related to sarcopenia seen in extreme old age. Whole extensor digitorum longus muscle and motor unit contractile properties were measured in 19 adult (11-13 months) and 12 oldest old (36-37 months) Brown-Norway rats. Compared with adults, oldest old rats had significantly fewer motor units per muscle, smaller muscle cross-sectional area, and lower muscle specific force. However, mean motor unit force generation was similar between the two groups due to an increase in innervation ratio by the oldest old rats. These findings suggest that even in extreme old age both fast- and slow-twitch motor units maintain the ability to undergo motor unit remodeling that offsets some effects of sarcopenia.
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Affiliation(s)
| | | | - Jack H van der Meulen
- The Institute of Gerontology, University of Michigan, University of Michigan Health System, Ann Arbor
| | | | | | - John A Faulkner
- The Institute of Gerontology, University of Michigan, University of Michigan Health System, Ann Arbor
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16
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Murphy KT, Ham DJ, Church JE, Naim T, Trieu J, Williams DA, Lynch GS. Parvalbumin gene transfer impairs skeletal muscle contractility in old mice. Hum Gene Ther 2012; 23:824-36. [PMID: 22455364 DOI: 10.1089/hum.2011.210] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Sarcopenia is the progressive age-related loss of skeletal muscle mass associated with functional impairments that reduce mobility and quality of life. Overt muscle wasting with sarcopenia is usually preceded by a slowing of the rate of relaxation and a reduction in maximum force production. Parvalbumin (PV) is a cytosolic Ca(2+) buffer thought to facilitate relaxation in muscle. We tested the hypothesis that restoration of PV levels in muscles of old mice would increase the magnitude and hasten relaxation of submaximal and maximal force responses. The tibialis anterior (TA) muscles of young (6 month), adult (13 month), and old (26 month) C57BL/6 mice received electroporation-assisted gene transfer of plasmid encoding PV or empty plasmid (pcDNA3.1). Contractile properties of TA muscles were assessed in situ 14 days after transfer. In old mice, muscles with increased PV expression had a 40% slower rate of tetanic force development (p<0.01), and maximum twitch and tetanic force were 22% and 16% lower than control values, respectively (p<0.05). Muscles with increased PV expression from old mice had an 18% lower maximum specific (normalized) force than controls, and absolute force was `26% lower at higher stimulation frequencies (150-300 Hz, p<0.05). In contrast, there was no effect of increased PV expression on TA muscle contractile properties in young and adult mice. The impairments in skeletal muscle function in old mice argue against PV overexpression as a therapeutic strategy for ameliorating aspects of contractile dysfunction with sarcopenia and help clarify directions for therapeutic interventions for age-related changes in skeletal muscle structure and function.
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Affiliation(s)
- Kate T Murphy
- Basic and Clinical Myology Laboratory, The University of Melbourne, Melbourne, VIC 3010, Australia
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17
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Hsp72 preserves muscle function and slows progression of severe muscular dystrophy. Nature 2012; 484:394-8. [PMID: 22495301 DOI: 10.1038/nature10980] [Citation(s) in RCA: 204] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2012] [Accepted: 02/21/2012] [Indexed: 11/08/2022]
Abstract
Duchenne muscular dystrophy (DMD) is a severe and progressive muscle wasting disorder caused by mutations in the dystrophin gene that result in the absence of the membrane-stabilizing protein dystrophin. Dystrophin-deficient muscle fibres are fragile and susceptible to an influx of Ca(2+), which activates inflammatory and muscle degenerative pathways. At present there is no cure for DMD, and existing therapies are ineffective. Here we show that increasing the expression of intramuscular heat shock protein 72 (Hsp72) preserves muscle strength and ameliorates the dystrophic pathology in two mouse models of muscular dystrophy. Treatment with BGP-15 (a pharmacological inducer of Hsp72 currently in clinical trials for diabetes) improved muscle architecture, strength and contractile function in severely affected diaphragm muscles in mdx dystrophic mice. In dko mice, a phenocopy of DMD that results in severe spinal curvature (kyphosis), muscle weakness and premature death, BGP-15 decreased kyphosis, improved the dystrophic pathophysiology in limb and diaphragm muscles and extended lifespan. We found that the sarcoplasmic/endoplasmic reticulum Ca(2+)-ATPase (SERCA, the main protein responsible for the removal of intracellular Ca(2+)) is dysfunctional in severely affected muscles of mdx and dko mice, and that Hsp72 interacts with SERCA to preserve its function under conditions of stress, ultimately contributing to the decreased muscle degeneration seen with Hsp72 upregulation. Treatment with BGP-15 similarly increased SERCA activity in dystrophic skeletal muscles. Our results provide evidence that increasing the expression of Hsp72 in muscle (through the administration of BGP-15) has significant therapeutic potential for DMD and related conditions, either as a self-contained therapy or as an adjuvant with other potential treatments, including gene, cell and pharmacological therapies.
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18
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Russ DW, Grandy JS, Toma K, Ward CW. Ageing, but not yet senescent, rats exhibit reduced muscle quality and sarcoplasmic reticulum function. Acta Physiol (Oxf) 2011; 201:391-403. [PMID: 20874807 DOI: 10.1111/j.1748-1716.2010.02191.x] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
AIM Reduced muscle force greater than expected from loss of muscle mass has been reported in ageing muscles. Impaired sarcoplasmic reticulum (SR) Ca(2+) release has been implicated as a possible mechanism, and attributed to several factors, including loss of ryanodine receptor (RYR) expression and protein binding. The aim of this study was to evaluate muscle quality and SR Ca(2+) release in ageing rats that were not so old that major atrophy had occurred. METHODS We collected in situ force data from the plantarflexor muscle group and muscle mass from the constituent muscles to determine muscle quality (force/mass) in adult (6-8 months) and ageing (24 months) rats (n=8/group). We evaluated SR Ca(2+) uptake and release, and determined expression of key proteins associated with Ca(2+) release [RYR and FK506 binding protein (FKBP)] and uptake (SERCA, parvalbumin, calsequestrin). RESULTS Plantarflexor force and muscle quality were reduced with ageing (approx. 28 and 34%, respectively), but atrophy was limited, and significant only in the medial gastrocnemius (approx. 15%). The fast phase of SR Ca(2+) release was reduced with ageing in both gastrocnemii, as was FKBP expression and FKBP-RYR binding, but RYR expression was not affected. Similar, but non-significant changes were present in the plantaris, but the soleus muscle generally showed no ageing-related changes. CONCLUSION These data suggest a possible role for impaired SR Ca(2+) release in ageing-related loss of muscle quality, although not through loss of RYR expression.
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Affiliation(s)
- D W Russ
- Laboratory for Integrative Muscle Biology, School of Physical Therapy, Ohio University, Athens, OH 45701, USA.
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19
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Hall JK, Banks GB, Chamberlain JS, Olwin BB. Prevention of muscle aging by myofiber-associated satellite cell transplantation. Sci Transl Med 2011; 2:57ra83. [PMID: 21068442 DOI: 10.1126/scitranslmed.3001081] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Skeletal muscle is dynamic, adapting to environmental needs, continuously maintained, and capable of extensive regeneration. These hallmarks diminish with age, resulting in a loss of muscle mass, reduced regenerative capacity, and decreased functionality. Although the mechanisms responsible for this decline are unclear, complex changes within the local and systemic environment that lead to a reduction in regenerative capacity of skeletal muscle stem cells, termed satellite cells, are believed to be responsible. We demonstrate that engraftment of myofiber-associated satellite cells, coupled with an induced muscle injury, markedly alters the environment of young adult host muscle, eliciting a near-lifelong enhancement in muscle mass, stem cell number, and force generation. The abrogation of age-related atrophy appears to arise from an increased regenerative capacity of the donor stem cells, which expand to occupy both myonuclei in myofibers and the satellite cell niche. Further, these cells have extensive self-renewal capabilities, as demonstrated by serial transplantation. These near-lifelong, physiological changes suggest an approach for the amelioration of muscle atrophy and diminished function that arise with aging through myofiber-associated satellite cell transplantation.
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Affiliation(s)
- John K Hall
- Department of Molecular, Cellular and Developmental Biology, University of Colorado, Boulder, CO 80309, USA
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20
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Hinkle RT, Lefever FR, Dolan ET, Reichart DL, Zwolshen JM, Oneill TP, Maloney KG, Mattson JP, Ferreira LF, Musch TI, Poole DC, Isfort RJ. Treatment with a corticotrophin releasing factor 2 receptor agonist modulates skeletal muscle mass and force production in aged and chronically ill animals. BMC Musculoskelet Disord 2011; 12:15. [PMID: 21235761 PMCID: PMC3025927 DOI: 10.1186/1471-2474-12-15] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/21/2009] [Accepted: 01/14/2011] [Indexed: 11/17/2022] Open
Abstract
Background Muscle weakness is associated with a variety of chronic disorders such as emphysema (EMP) and congestive heart failure (CHF) as well as aging. Therapies to treat muscle weakness associated with chronic disease or aging are lacking. Corticotrophin releasing factor 2 receptor (CRF2R) agonists have been shown to maintain skeletal muscle mass and force production in a variety of acute conditions that lead to skeletal muscle wasting. Hypothesis We hypothesize that treating animals with a CRF2R agonist will maintain skeletal muscle mass and force production in animals with chronic disease and in aged animals. Methods We utilized animal models of aging, CHF and EMP to evaluate the potential of CRF2R agonist treatment to maintain skeletal muscle mass and force production in aged animals and animals with CHF and EMP. Results In aged rats, we demonstrate that treatment with a CRF2R agonist for up to 3 months results in greater extensor digitorum longus (EDL) force production, EDL mass, soleus mass and soleus force production compared to age matched untreated animals. In the hamster EMP model, we demonstrate that treatment with a CRF2R agonist for up to 5 months results in greater EDL force production in EMP hamsters when compared to vehicle treated EMP hamsters and greater EDL mass and force in normal hamsters when compared to vehicle treated normal hamsters. In the rat CHF model, we demonstrate that treatment with a CRF2R agonist for up to 3 months results in greater EDL and soleus muscle mass and force production in CHF rats and normal rats when compared to the corresponding vehicle treated animals. Conclusions These data demonstrate that the underlying physiological conditions associated with chronic diseases such as CHF and emphysema in addition to aging do not reduce the potential of CRF2R agonists to maintain skeletal muscle mass and force production.
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21
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Thomas MM, Vigna C, Betik AC, Tupling AR, Hepple RT. Initiating treadmill training in late middle age offers modest adaptations in Ca2+ handling but enhances oxidative damage in senescent rat skeletal muscle. Am J Physiol Regul Integr Comp Physiol 2010; 298:R1269-78. [PMID: 20200131 DOI: 10.1152/ajpregu.00663.2009] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Aging skeletal muscle shows an increased time to peak force and relaxation and a decreased specific force, all of which could relate to changes in muscle Ca(2+) handling. The purpose of this study was to determine if Ca(2+)-handling protein content and function are decreased in senescent gastrocnemius muscle and if initiating a training program in late middle age (LMA, 29 mo old) could improve function in senescent (34- to 36-mo-old) muscle. LMA male Fischer 344 x Brown-Norway rats underwent 5-7 mo of treadmill training. Aging resulted in a decrease in maximal sarco(endo)plasmic reticulum Ca(2+)-ATPase (SERCA) activity and a decrease in Ca(2+) release rate but no change in Ca(2+) uptake rate. Efficiency of the Ca(2+) pump was increased with age, as was the content of SERCA2a. Training caused a further increase in SERCA2a content. Aging also caused an increase in protein carbonyl and reactive nitrogen species damage accumulation, and both further increased with training. Consistent with the increase in oxidative damage, heat shock protein 70 content was increased with age and further increased with training. Together, these results suggest that while initiating exercise training in LMA augments the age-related increase in expression of heat shock protein 70 and the more efficient SERCA2a isoform, it did not prevent the decrease in SERCA activity and exacerbated oxidative damage in senescent gastrocnemius muscle.
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Affiliation(s)
- Melissa M Thomas
- Muscle and Aging Laboratory, Faculty of Kinesiology, University of Calgary, 2500 University Dr. NW, Calgary, Alberta, Canada
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22
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Dong Y, Zhang M, Liang B, Xie Z, Zhao Z, Asfa S, Choi HC, Zou MH. Reduction of AMP-activated protein kinase alpha2 increases endoplasmic reticulum stress and atherosclerosis in vivo. Circulation 2010; 121:792-803. [PMID: 20124121 DOI: 10.1161/circulationaha.109.900928] [Citation(s) in RCA: 228] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Aberrant endoplasmic reticulum (ER) stress is associated with several cardiovascular diseases, including atherosclerosis. The mechanism by which aberrant ER stress develops is poorly understood. This study investigated whether dysfunction of AMP-activated protein kinase (AMPK) causes aberrant ER stress and atherosclerosis in vivo. METHODS AND RESULTS Human umbilical vein endothelial cells and mouse aortic endothelial cells from AMPK-deficient mice were used to assess the level of ER stress with Western blotting. Reduction of AMPKalpha2 expression significantly increased the level of ER stress in human umbilical vein endothelial cells. In addition, mouse aortic endothelial cells from AMPKalpha2 knockout (AMPKalpha2(-/-)) mice had higher expression of markers of ER stress and increased levels of intracellular Ca2+. These phenotypes were abolished by adenovirally overexpressing constitutively active AMPK mutants (Ad-AMPK-CA) or by transfecting sarcoendoplasmic reticulum calcium ATPase (SERCA). Inhibition of SERCA induced ER stress in endothelial cells. Furthermore, reduction of AMPKalpha expression suppressed SERCA activity. In addition, SERCA activity was significantly reduced concomitantly with increased oxidation of SERCA in mouse aortic endothelial cells from AMPKalpha2(-/-) mice. Both of these phenotypes were abolished by adenovirally overexpressing Ad-AMPK-CA. Furthermore, Tempol, which restored SERCA activity and decreased oxidized SERCA levels, markedly reduced the level of ER stress in mouse aortic endothelial cells from AMPKalpha2(-/-) mice. Finally, oral administration of tauroursodeoxycholic acid, a chemical chaperone that inhibits ER stress, significantly reduced both ER stress and aortic lesion development in low-density lipoprotein receptor- and AMPKalpha2-deficient mice. CONCLUSIONS These results suggest that AMPK functions as a physiological suppressor of ER stress by maintaining SERCA activity and intracellular Ca2+ homeostasis.
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Affiliation(s)
- Yunzhou Dong
- Department of Medicine and Endocrinology, University of Oklahoma Health Science Center, Oklahoma City, OK 73104, USA
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23
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Puzianowska-Kuznicka M, Kuznicki J. The ER and ageing II: calcium homeostasis. Ageing Res Rev 2009; 8:160-72. [PMID: 19427411 DOI: 10.1016/j.arr.2009.05.002] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2009] [Revised: 04/30/2009] [Accepted: 05/01/2009] [Indexed: 11/29/2022]
Abstract
Increase in intracellular Ca(2+) concentration occurs by Ca(2+) influx through the plasma membrane and by Ca(2+) release from intracellular stores. The ER is the most important Ca(2+) store. Its stress, characterized by the impairment of Ca(2+) homeostasis and by the accumulation of misfolded proteins, can be induced by different factors. In turn, it induces defense mechanisms such as unfolded protein response, and when it is severe and prolonged, activation of the apoptotic pathway. Damage to the ER, impairment of its function, and a decreased level of its Ca(2+)-handling proteins might all play a role in physiological ageing by handicapping the ER stress response. Thus, healthy ageing is accompanied by subtle alterations of Ca(2+) homeostasis and signaling, including alterations in the ER Ca(2+) load and release. The expression and/or function of ryanodine receptors, IP3 receptors, and SERCA Ca(2+) pumps located in the ER membrane, and Ca(2+)-binding proteins within ER lumen all seem to be affected in aged cells. Data are presented on age-dependent, tissue-specific changes in ER-related Ca(2+) homeostasis in skeletal, cardiac and smooth muscles, as well as in the nervous and immune systems. Disturbances of Ca(2+) homeostasis and of signaling are potential targets for intervention in aged humans.
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Ryall JG, Lynch GS. The potential and the pitfalls of β-adrenoceptor agonists for the management of skeletal muscle wasting. Pharmacol Ther 2008; 120:219-32. [DOI: 10.1016/j.pharmthera.2008.06.003] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2008] [Accepted: 06/04/2008] [Indexed: 01/08/2023]
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25
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Gehrig SM, Ryall JG, Schertzer JD, Lynch GS. Insulin-like growth factor-I analogue protects muscles of dystrophicmdxmice from contraction-mediated damage. Exp Physiol 2008; 93:1190-8. [DOI: 10.1113/expphysiol.2008.042838] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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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: 298] [Impact Index Per Article: 18.6] [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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Ryall JG, Schertzer JD, Alabakis TM, Gehrig SM, Plant DR, Lynch GS. Intramuscular beta2-agonist administration enhances early regeneration and functional repair in rat skeletal muscle after myotoxic injury. J Appl Physiol (1985) 2008; 105:165-72. [PMID: 18436698 DOI: 10.1152/japplphysiol.00317.2007] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Systemic administration of beta(2)-adrenoceptor agonists (beta(2)-agonists) can improve skeletal muscle regeneration after injury. However, therapeutic application of beta(2)-agonists for muscle injury has been limited by detrimental cardiovascular side effects. Intramuscular administration may obviate some of these side effects. To test this hypothesis, the right extensor digitorum longus (EDL) muscle from rats was injected with bupivacaine hydrochloride to cause complete muscle fiber degeneration. Five days after injury, half of the injured muscles received an intramuscular injection of formoterol (100 mug). Muscle function was assessed at 7, 10, and 14 days after injury. A single intramuscular injection of formoterol increased muscle mass and force-producing capacity at day 7 by 17 and 91%, respectively, but this effect was transient because these values were not different from control levels at day 10. A second intramuscular injection of formoterol at day 7 prolonged the increase in muscle mass and force-producing capacity. Importantly, single or multiple intramuscular injections of formoterol did not elicit cardiac hypertrophy. To characterize any potential cardiovascular effects of intramuscular formoterol administration, we instrumented a separate group of rats with indwelling radio telemeters. Following an intramuscular injection of formoterol, heart rate increased by 18%, whereas systolic and diastolic blood pressure decreased by 31 and 44%, respectively. These results indicate that intramuscular injection can enhance functional muscle recovery after injury without causing cardiac hypertrophy. Therefore, if the transient cardiovascular effects associated with intramuscular formoterol administration can be minimized, this form of treatment may have significant therapeutic potential for muscle-wasting conditions.
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Affiliation(s)
- James G Ryall
- Basic and Clinical Myology Laboratory, Department of Physiology, The University of Melbourne, Victoria, 3010 Australia
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Ryall JG, Schertzer JD, Murphy KT, Allen AM, Lynch GS. Chronic beta2-adrenoceptor stimulation impairs cardiac relaxation via reduced SR Ca2+-ATPase protein and activity. Am J Physiol Heart Circ Physiol 2008; 294:H2587-95. [PMID: 18408128 DOI: 10.1152/ajpheart.00985.2007] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We determined the cardiovascular effects of chronic beta2-adrenoceptor (beta2-AR) stimulation in vivo and examined the mechanism for the previously observed prolonged diastolic relaxation. Rats (3 mo old; n = 6), instrumented with implantable radiotelemeters, received the selective beta2-AR agonist formoterol (25 microg.kg(-1).day(-1) ip) for 4 wk, with selected cardiovascular parameters measured daily throughout this period, and for a further 7 days after cessation of treatment. Chronic beta2-AR stimulation was associated with an increase in heart rate (HR) of 17% (days 1-14) and 5% (days 15-28); a 11% (days 1-14) and 6% (days 15-28) decrease in mean arterial blood pressure; and a 24% (days 1-14) increase in the rate of cardiac relaxation (-dP/dt) compared with initial values (P < 0.05). Cessation of beta2-AR stimulation resulted in an 8% decrease in HR and a 7% decrease in -dP/dt, compared with initial values (P < 0.05). The prolonged cardiac relaxation with chronic beta2-AR stimulation was associated with a 30% decrease in the maximal rate (Vmax) of sarco(endo)plasmic reticulum Ca2+ -ATPase (SERCA) activity, likely attributed to a 50% decrease in SERCA2a protein (P < 0.05). glycogen synthase kinase-3beta (GSK-3beta) has been implicated as a negative regulator of SERCA2 gene transcription, and we observed a approximately 60% decrease (P < 0.05) in phosphorylated GSK-3beta protein after chronic beta2-AR stimulation. Finally, we found a 40% decrease (P < 0.05) in the mRNA expression of the novel A kinase anchoring protein AKAP18, also implicated in beta2-AR-mediated cardiac relaxation. These findings highlight some detrimental cardiovascular effects of chronic beta2-AR agonist administration and identify concerns for their current and future use for treating asthma or for conditions where muscle wasting and weakness are indicated.
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Affiliation(s)
- James G Ryall
- Basic and Clinical Myology Laboratory, Department of Physiology, University of Melbourne, Victoria, Australia
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Cellular and molecular mechanisms underlying age-related skeletal muscle wasting and weakness. Biogerontology 2008; 9:213-28. [PMID: 18299960 DOI: 10.1007/s10522-008-9131-0] [Citation(s) in RCA: 277] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2007] [Accepted: 02/06/2008] [Indexed: 01/02/2023]
Abstract
Some of the most serious consequences of ageing are its effects on skeletal muscle. The term 'sarcopenia' describes the slow but progressive loss of muscle mass with advancing age and is characterised by a deterioration of muscle quantity and quality leading to a gradual slowing of movement and a decline in strength. The loss of muscle mass and strength is thought to be attributed to the progressive atrophy and loss of individual muscle fibres associated with the loss of motor units, and a concomitant reduction in muscle 'quality' due to the infiltration of fat and other non-contractile material. These age-related changes in skeletal muscle can be largely attributed to the complex interaction of factors affecting neuromuscular transmission, muscle architecture, fibre composition, excitation-contraction coupling, and metabolism. Given the magnitude of the growing public health problems associated with sarcopenia, there is considerable interest in the development and evaluation of therapeutic strategies to attenuate, prevent, or ultimately reverse age-related muscle wasting and weakness. The aim is to review our current understanding of some of the cellular and molecular mechanisms responsible for age-related changes in skeletal muscle.
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Beitzel F, Sillence MN, Lynch GS. beta-Adrenoceptor signaling in regenerating skeletal muscle after beta-agonist administration. Am J Physiol Endocrinol Metab 2007; 293:E932-40. [PMID: 17623752 DOI: 10.1152/ajpendo.00175.2007] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Stimulating the beta-adrenoceptor (beta-AR) signaling pathway can enhance the functional repair of skeletal muscle after injury, but long-term use of beta-AR agonists causes beta-AR downregulation, which may limit their therapeutic effectiveness. The aim was to examine beta-AR signaling during early regeneration in rat fast-twitch [extensor digitorum longus (EDL)] and slow-twitch (soleus) muscles after bupivacaine injury and test the hypothesis that, during regeneration, beta-agonist administration does not cause beta-AR desensitization. Rats received either the beta-AR agonist fenoterol (1.4 mgxkg(-1)xday(-1) ip) or saline for 7 days postinjury. Fenoterol reduced beta-AR density in regenerating soleus muscles by 42%. Regenerating EDL muscles showed a threefold increase in beta-AR density, and, again, these values were 43% lower with fenoterol treatment. An amplified adenylate cyclase (AC) response to isoproterenol was observed in cell membrane fragments from EDL and soleus muscles 7 days postinjury. Fenoterol attenuated this increase in regenerating EDL muscles but not soleus muscles. beta-AR signaling mechanisms were assessed using AC stimulants (NaF, forskolin, and Mn(2+)). Although beta-agonist treatment reduces beta-AR density in regenerating muscles, these muscles can produce large cAMP responses relative to healthy (uninjured) muscles. Desensitization of beta-AR signaling in regenerating muscles is prevented by altered rates of beta-AR synthesis and/or degradation, changes in G protein populations and coupling efficiency, and altered AC activity. These mechanisms have important therapeutic implications for modulating beta-AR signaling to enhance muscle repair after injury.
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MESH Headings
- Adenylyl Cyclases/metabolism
- Adrenergic beta-Agonists/pharmacology
- Animals
- GTP-Binding Proteins/metabolism
- Muscle, Skeletal/drug effects
- Muscle, Skeletal/metabolism
- Muscle, Skeletal/physiology
- RNA, Messenger/metabolism
- Rats
- Rats, Inbred F344
- Receptors, Adrenergic, beta/genetics
- Receptors, Adrenergic, beta/metabolism
- Receptors, Adrenergic, beta/physiology
- Regeneration/drug effects
- Signal Transduction/drug effects
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Affiliation(s)
- Felice Beitzel
- Basic and Clinical Myology Laboratory, Dept. of Physiology, The Univ. of Melbourne, Victoria, 3010 Australia
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31
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Chen G, Xiong Y, Kong B, Newman M, Thompson K, Metts L, Webster C. Microbiological and Physicochemical Properties of Red Claw Crayfish (Cherax quadricarinatus) Stored in Different Package Systems at 2 °C. J Food Sci 2007; 72:E442-9. [DOI: 10.1111/j.1750-3841.2007.00482.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Ryall JG, Schertzer JD, Lynch GS. Attenuation of age-related muscle wasting and weakness in rats after formoterol treatment: therapeutic implications for sarcopenia. J Gerontol A Biol Sci Med Sci 2007; 62:813-23. [PMID: 17702871 DOI: 10.1093/gerona/62.8.813] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We investigated the potential of the beta(2)-adrenoceptor agonist formoterol to increase mass and force-producing capacity of extensor digitorum longus (EDL) and soleus muscles from young, adult, and old rats. In addition, we examined the result of formoterol withdrawal. Young (3 month), adult (16 month), and old (27 month) F344 rats were treated with either formoterol (25 microg/kg/day, i.p.) or saline vehicle for 4 weeks. Another group of rats (for each age) was similarly treated with formoterol, followed by a withdrawal period of 4 weeks. Formoterol treatment increased EDL muscle mass and the force-producing capacity of both EDL and soleus muscles, without a concomitant increase in heart mass in adult and old rats. The hypertrophy and increased force-producing capacity of EDL muscles persisted 4 weeks after withdrawal of treatment. The findings have major implications for potential clinical trials utilizing beta(2)-agonists for sarcopenia.
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Affiliation(s)
- James G Ryall
- Basic and Clinical Myology Laboratory, Department of Physiology, The University of Melbourne, Melbourne, Victoria, 3010 Australia
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Schertzer JD, Gehrig SM, Ryall JG, Lynch GS. Modulation of insulin-like growth factor (IGF)-I and IGF-binding protein interactions enhances skeletal muscle regeneration and ameliorates the dystrophic pathology in mdx mice. THE AMERICAN JOURNAL OF PATHOLOGY 2007; 171:1180-8. [PMID: 17823291 PMCID: PMC1988868 DOI: 10.2353/ajpath.2007.070292] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Administration of recombinant human insulin-like growth factor-I (rhIGF-I) has beneficial effects in animal models of muscle injury and muscular dystrophy. However, the results of these studies may have been confounded by interactions of rhIGF-I with endogenous IGF-binding proteins (IGFBPs). To date, no study has examined whether inhibiting IGFBP interactions with endogenous IGF-I can improve muscle fiber regeneration or muscular pathologies. We tested the hypothesis that reducing IGFBP interactions with endogenous IGF-I would enhance muscle regeneration after myotoxic injury and improve the dystrophic pathology in mdx mice. We administered an IGF-I aptamer (NBI-31772; 6 mg/kg per day, continuous infusion) to C57BL/10 mice undergoing regeneration after myotoxic injury or to mdx dystrophic mice. NBI-31772 binds all six IGFBPs with high affinity and releases "free" endogenous IGF-I. NBI-31772 treatment increased the rate of functional repair in fast-twitch tibialis anterior muscles after notexin-induced injury as evidenced by an increase in maximum force producing capacity (P(o)) at 10 days after injury. In contrast, NBI-31772 administration for 28 days did not alter P(o) of extensor digitorum longus (EDL) and soleus muscles or normalized force of diaphragm muscle strips from mdx mice. Although IGFBP inhibition reduced the susceptibility of the fast-twitch EDL and the diaphragm muscle to contraction-mediated damage, it increased muscle fatigability during repeated maximal contractions. Although the results in the myotoxic injury model suggest IGF-I signaling is important in this model, the results in the mdx model are mixed.
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Affiliation(s)
- Jonathan D Schertzer
- Department of Physiology, The University of Melbourne, Melbourne, VIC, 3010, Australia.
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Lynch GS, Schertzer JD, Ryall JG. Therapeutic approaches for muscle wasting disorders. Pharmacol Ther 2007; 113:461-87. [PMID: 17258813 DOI: 10.1016/j.pharmthera.2006.11.004] [Citation(s) in RCA: 100] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2006] [Revised: 11/10/2006] [Accepted: 11/10/2006] [Indexed: 12/12/2022]
Abstract
Muscle wasting and weakness are common in many disease states and conditions including aging, cancer cachexia, sepsis, denervation, disuse, inactivity, burns, HIV-acquired immunodeficiency syndrome (AIDS), chronic kidney or heart failure, unloading/microgravity, and muscular dystrophies. Although the maintenance of muscle mass is generally regarded as a simple balance between protein synthesis and protein degradation, these mechanisms are not strictly independent, but in fact they are coordinated by a number of different and sometimes complementary signaling pathways. Clearer details are now emerging about these different molecular pathways and the extent to which these pathways contribute to the etiology of various muscle wasting disorders. Therapeutic strategies for attenuating muscle wasting and improving muscle function vary in efficacy. Exercise and nutritional interventions have merit for slowing the rate of muscle atrophy in some muscle wasting conditions, but in most cases they cannot halt or reverse the wasting process. Hormonal and/or other drug strategies that can target key steps in the molecular pathways that regulate protein synthesis and protein degradation are needed. This review describes the signaling pathways that maintain muscle mass and provides an overview of some of the major conditions where muscle wasting and weakness are indicated. The review provides details on some therapeutic strategies that could potentially attenuate muscle atrophy, promote muscle growth, and ultimately improve muscle function. The emphasis is on therapies that can increase muscle mass and improve functional outcomes that will ultimately lead to improvement in the quality of life for affected patients.
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Affiliation(s)
- Gordon S Lynch
- Basic and Clinical Myology Laboratory, Department of Physiology, The University of Melbourne, Victoria 3010, Australia.
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Schertzer JD, Ryall JG, Lynch GS. Systemic administration of IGF-I enhances oxidative status and reduces contraction-induced injury in skeletal muscles of mdx dystrophic mice. Am J Physiol Endocrinol Metab 2006; 291:E499-505. [PMID: 16621899 DOI: 10.1152/ajpendo.00101.2006] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The absence of dystrophin and resultant disruption of the dystrophin glycoprotein complex renders skeletal muscles of dystrophic patients and dystrophic mdx mice susceptible to contraction-induced injury. Strategies to reduce contraction-induced injury are of critical importance, because this mode of damage contributes to the etiology of myofiber breakdown in the dystrophic pathology. Transgenic overexpression of insulin-like growth factor-I (IGF-I) causes myofiber hypertrophy, increases force production, and can improve the dystrophic pathology in mdx mice. In contrast, the predominant effect of continuous exogenous administration of IGF-I to mdx mice at a low dose (1.0-1.5 mg.kg(-1).day(-1)) is a shift in muscle phenotype from fast glycolytic toward a more oxidative, fatigue-resistant, slow muscle without alterations in myofiber cross-sectional area, muscle mass, or maximum force-producing capacity. We found that exogenous administration of IGF-I to mdx mice increased myofiber succinate dehydrogenase activity, shifted the overall myosin heavy chain isoform composition toward a slower phenotype, and, most importantly, reduced contraction-induced damage in tibialis anterior muscles. The deficit in force-producing capacity after two damaging lengthening contractions was reduced significantly in tibialis anterior muscles of IGF-I-treated (53 +/- 4%) compared with untreated mdx mice (70 +/- 5%, P < 0.05). The results provide further evidence that IGF-I administration can enhance the functional properties of dystrophic skeletal muscle and, compared with results in transgenic mice or virus-mediated overexpression, highlight the disparities in different models of endocrine factor delivery.
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MESH Headings
- Animals
- Gene Expression/drug effects
- Insulin-Like Growth Factor I/pharmacology
- Male
- Mice
- Mice, Inbred C57BL
- Mice, Inbred mdx
- Muscle Contraction/drug effects
- Muscle Contraction/physiology
- Muscle Fibers, Skeletal/drug effects
- Muscle Fibers, Skeletal/metabolism
- Muscle, Skeletal/drug effects
- Muscle, Skeletal/injuries
- Muscle, Skeletal/physiopathology
- Muscular Dystrophy, Animal/genetics
- Muscular Dystrophy, Animal/metabolism
- Muscular Dystrophy, Animal/physiopathology
- Myosin Heavy Chains/genetics
- Myosin Heavy Chains/metabolism
- Protein Isoforms/genetics
- Protein Isoforms/metabolism
- Succinate Dehydrogenase/metabolism
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Schertzer JD, Lynch GS. Comparative evaluation of IGF-I gene transfer and IGF-I protein administration for enhancing skeletal muscle regeneration after injury. Gene Ther 2006; 13:1657-64. [PMID: 16871234 DOI: 10.1038/sj.gt.3302817] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Developing methodologies to enhance skeletal muscle regeneration and hasten the restoration of muscle function has important implications for minimizing disability after injury and for treating muscle diseases such as Duchenne muscular dystrophy. Although delivery of various growth factors, such as insulin-like growth factor-I (IGF-I), have proved successful in promoting skeletal muscle regeneration after injury, no study has compared the efficacy of different delivery methods directly. We compared the efficacy of systemic delivery of recombinant IGF-I protein via mini-osmotic pump (approximately 1.5 mg/kg/day) with a single electrotransfer-assisted plasmid-based gene transfer, to hasten functional repair of mouse tibialis anterior muscles after myotoxic injury. The relative efficacy of each method was assessed at 7, 21 and 28 days post-injury. Our findings indicate that IGF-I hastened functional recovery, regardless of the route of IGF-I administration. However, gene transfer of IGF-I was superior to systemic protein administration because in the regenerating muscle, this delivery method increased IGF-I levels, activated intracellular signals (Akt phosphorylation), induced a greater magnitude of myofiber hypertrophy and hastened functional recovery at an earlier time point (14 days) after injury than did protein administration (21 days). Thus, the relative efficacy of different modes of delivery is an important consideration when assessing the therapeutic potential of various proteins for treating muscle injuries and skeletal muscle diseases.
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Affiliation(s)
- J D Schertzer
- Basic and Clinical Myology Laboratory, Department of Physiology, The University of Melbourne, Grattan Street, Victoria 3010, Australia
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Zhang BX, Ma X, Zhang W, Yeh CK, Lin A, Luo J, Sprague EA, Swerdlow RH, Katz MS. Polyunsaturated fatty acids mobilize intracellular Ca2+in NT2 human teratocarcinoma cells by causing release of Ca2+from mitochondria. Am J Physiol Cell Physiol 2006; 290:C1321-33. [PMID: 16601147 DOI: 10.1152/ajpcell.00335.2005] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In a variety of disorders, overaccumulation of lipid in nonadipose tissues, including the heart, skeletal muscle, kidney, and liver, is associated with deterioration of normal organ function, and is accompanied by excessive plasma and cellular levels of free fatty acids (FA). Increased concentrations of FA may lead to defects in mitochondrial function found in diverse diseases. One of the most important regulators of mitochondrial function is mitochondrial Ca2+([Ca2+]m), which fluctuates in coordination with intracellular Ca2+([Ca2+]i). Polyunsaturated FA (PUFA) have been shown to cause [Ca2+]imobilization albeit by unknown mechanisms. We have found that PUFA but not monounsaturated or saturated FA cause [Ca2+]imobilization in NT2 human teratocarcinoma cells. Unlike the [Ca2+]iresponse to the muscarinic G protein-coupled receptor agonist carbachol, PUFA-mediated [Ca2+]imobilization in NT2 cells is independent of phospholipase C and inositol-1,4,5-trisphospate (IP3) receptor activation, as well as IP3-sensitive internal Ca2+stores. Furthermore, PUFA-mediated [Ca2+]imobilization is inhibited by the mitochondria uncoupler carboxyl cyanide m-chlorophenylhydrozone. Direct measurements of [Ca2+]mwith X-rhod-1 and45Ca2+indicate that PUFA induce Ca2+efflux from mitochondria. Further studies show that ruthenium red, an inhibitor of the mitochondrial Ca2+uniporter, blocks PUFA-induced Ca2+efflux from mitochondria, whereas inhibitors of the mitochondrial permeability transition pore cyclosporin A and bongkrekic acid have no effect. Thus PUFA-gated Ca2+release from mitochondria, possibly via the Ca2+uniporter, appears to be the underlying mechanism for PUFA-induced [Ca2+]imobilization in NT2 cells.
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Affiliation(s)
- Bin-Xian Zhang
- Geriatric Research, Education and Clinical Center (182), South Texas Veterans Health Care System, Audie L. Murphy Division, 7400 Merton Minter Blvd., San Antonio, TX 78229, USA.
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Schertzer JD, Plant DR, Lynch GS. Optimizing plasmid-based gene transfer for investigating skeletal muscle structure and function. Mol Ther 2005; 13:795-803. [PMID: 16309967 DOI: 10.1016/j.ymthe.2005.09.019] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2005] [Revised: 08/22/2005] [Accepted: 09/04/2005] [Indexed: 11/22/2022] Open
Abstract
Intramuscular injection of naked plasmid DNA is a less cytotoxic alternative to viral vectors for delivering genetic material to skeletal muscle in vivo. However, the low efficiency of plasmid-based gene transfer limits its potential therapeutic efficacy and/or its use for many experimental applications. Current strategies to enhance transfection efficiency (i.e., electroporation) can cause significant muscle damage, confounding physiological assessments such as muscle contractility. Optimizing protocols to limit damage is critical for accurate physiological, biochemical, and molecular measurements. Following extensive testing, we developed an electroporation protocol that enhances transfection efficiency in skeletal muscles without causing muscle damage. Pretreating mouse tibialis anterior muscles with hyaluronidase and electroporation at 75 V/cm (using 50% vol/vol saline as a vehicle for plasmid DNA) resulted in 22 +/- 5% of the muscle fibers expressing a reporter gene. This protocol did not compromise contractile function of skeletal muscles assessed at both the intact (whole) muscle and the cellular (single fiber) level. Furthermore, ectopic expression of insulin-like growth factor I to levels that induced muscle fiber hypertrophy without causing tissue damage or compromising muscle function highlights the therapeutic potential of these methods for myopathies, muscle wasting disorders, and other pathophysiologic conditions.
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Affiliation(s)
- Jonathan D Schertzer
- Department of Physiology, The University of Melbourne, Melbourne, VIC 3010, Australia
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Du M, Shen QW, Zhu MJ. Role of beta-adrenoceptor signaling and AMP-activated protein kinase in glycolysis of postmortem skeletal muscle. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2005; 53:3235-3239. [PMID: 15826083 DOI: 10.1021/jf047913n] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Postmortem glycolysis is directly linked to the incidences of PSE (pale, soft, and exudative) and DFD (dark, firm, and dry) meats, which cause significant economic loss to the meat industry. However, mechanisms controlling postmortem glycolysis are unclear. The objective of this study was to determine the role of beta-adrenoceptor signaling and AMP-activated protein kinase (AMPK) in postmortem glycolysis. Eighteen 2 month old C57BL/6J female mice were randomly separated into three groups. Group I received an intraperitoneal injection of saline solution only and served as the control; group II received a saline injection and then were forced to swim for 1 min; and group III received an injection of propranolol (1 mg/kg) in saline. In addition, six C57BL/6J female AMPK knockout mice were assigned to group IV, which received a saline injection and were forced to swim for 1 min. The longissimus dorsi muscle was sampled at 0, 1, and 24 h postmortem for pH and enzyme activity measurements. The objective is to elucidate the roles of beta-adrenoceptor signaling and AMPK in the glycolysis of postmortem muscle. Results showed that AMPK activity had a major role in determining the ultimate muscle pH, with an ultimate pH for control mice of 6.16 and AMPK knockout mice of 6.48. The beta-adrenoceptor signaling is essential for initial rapid glycolysis. Blocking beta-adrenoceptor signaling prevented the initial pH decline induced by stress. Activation of beta-adrenoceptor signaling due to preslaughter stress activates glycogen phosphorylase, resulting in a rapid glycolysis shortly after slaughter. On the other hand, the activation of AMPK is important for maintaining the activity of glycogen phosphorylase and pyruvate kinase, leading to a sustained glycolysis and a low ultimate pH.
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Affiliation(s)
- Min Du
- Department of Animal Science, University of Wyoming, Laramie, Wyoming 82071, USA.
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