scholarly journals Effects of Testosterone Supplementation on Skeletal Muscle Fiber Hypertrophy and Satellite Cells in Community-Dwelling Older Men

2006 ◽  
Vol 91 (8) ◽  
pp. 3024-3033 ◽  
Author(s):  
Indrani Sinha-Hikim ◽  
Marcia Cornford ◽  
Hilda Gaytan ◽  
Martin L. Lee ◽  
Shalender Bhasin
Keyword(s):  
Skeletal Muscle ◽  
Satellite Cell ◽  
Muscle Fiber ◽  
Satellite Cells ◽  
Older Men ◽  
Cell Number ◽  
Community Dwelling ◽  
Testosterone Treatment ◽  
Testosterone Administration ◽  
Dose Dependent

Abstract Objective: In this study, we determined the effects of graded doses of testosterone on muscle fiber cross-sectional area (CSA) and satellite cell number and replication in older men. Participants: Healthy men, 60–75 yr old, received a long-acting GnRH agonist to suppress endogenous testosterone production and 25, 50, 125, 300, or 600 mg testosterone enanthate im weekly for 20 wk. Methods: Immunohistochemistry, light and confocal microscopy, and electron microscopy were used to perform fiber typing and quantitate myonuclear and satellite cell number in vastus lateralis biopsies, obtained before and after 20 wk of treatment. Results: Testosterone administration in older men was associated with dose-dependent increases in CSA of both types I and II fibers. Satellite cell number increased dose dependently at the three highest doses (3% at baseline vs. 6.2, 9.2, and 13.0% at 125, 300, and 600 mg doses, P < 0.05). Testosterone administration was associated with an increase in the number of proliferating cell nuclear antigen+ satellite cells (1.8% at baseline vs. 3.9, 7.5, and 13% at 125, 300, and 600 mg doses, P < 0.005). The expression of activated Notch, examined only in the 300-mg group (baseline, 2.3 vs. 9.0% after treatment, P < 0.005), increased in satellite cells after testosterone treatment. The expression of myogenin (baseline, 6.2 vs. 20.7% after treatment, P < 0.005), examined only in the 300-mg group, increased significantly in muscle fiber nuclei after testosterone treatment, but Numb expression did not change. Conclusions: Older men respond to graded doses of testosterone with a dose-dependent increase in muscle fiber CSA and satellite cell number. Testosterone-induced skeletal muscle hypertrophy in older men is associated with increased satellite cell replication and activation.

scholarly journals Depletion of resident muscle stem cells negatively impacts running volume, physical function, and muscle fiber hypertrophy in response to lifelong physical activity

2020 ◽  
Vol 318 (6) ◽  
pp. C1178-C1188 ◽  
Author(s):  
Davis A. Englund ◽  
Kevin A. Murach ◽  
Cory M. Dungan ◽  
Vandré C. Figueiredo ◽  
Ivan J. Vechetti ◽  
...  
Keyword(s):  
Physical Activity ◽  
Skeletal Muscle ◽  
Physical Function ◽  
Satellite Cell ◽  
Muscle Fiber ◽  
Satellite Cells ◽  
Cell Depletion ◽  
Muscle Adaptation ◽  
Adult Skeletal Muscle

To date, studies that have aimed to investigate the role of satellite cells during adult skeletal muscle adaptation and hypertrophy have utilized a nontranslational stimulus and/or have been performed over a relatively short time frame. Although it has been shown that satellite cell depletion throughout adulthood does not drive skeletal muscle loss in sedentary mice, it remains unknown how satellite cells participate in skeletal muscle adaptation to long-term physical activity. The current study was designed to determine whether reduced satellite cell content throughout adulthood would influence the transcriptome-wide response to physical activity and diminish the adaptive response of skeletal muscle. We administered vehicle or tamoxifen to adult Pax7-diphtheria toxin A (DTA) mice to deplete satellite cells and assigned them to sedentary or wheel-running conditions for 13 mo. Satellite cell depletion throughout adulthood reduced balance and coordination, overall running volume, and the size of muscle proprioceptors (spindle fibers). Furthermore, satellite cell participation was necessary for optimal muscle fiber hypertrophy but not adaptations in fiber type distribution in response to lifelong physical activity. Transcriptome-wide analysis of the plantaris and soleus revealed that satellite cell function is muscle type specific; satellite cell-dependent myonuclear accretion was apparent in oxidative muscles, whereas initiation of G protein-coupled receptor (GPCR) signaling in the glycolytic plantaris may require satellite cells to induce optimal adaptations to long-term physical activity. These findings suggest that satellite cells play a role in preserving physical function during aging and influence muscle adaptation during sustained periods of physical activity.

scholarly journals Starring or Supporting Role? Satellite Cells and Skeletal Muscle Fiber Size Regulation

Physiology ◽  
2018 ◽  
Vol 33 (1) ◽  
pp. 26-38 ◽  
Author(s):  
Kevin A. Murach ◽  
Christopher S. Fry ◽  
Tyler J. Kirby ◽  
Janna R. Jackson ◽  
Jonah D. Lee ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Extracellular Matrix ◽  
Satellite Cell ◽  
Muscle Fiber ◽  
Satellite Cells ◽  
Skeletal Muscle Fiber ◽  
Cell Depletion ◽  
Loss Of Function ◽  
Adult Mice ◽  
Fiber Size

Recent loss-of-function studies show that satellite cell depletion does not promote sarcopenia or unloading-induced atrophy, and does not prevent regrowth. Although overload-induced muscle fiber hypertrophy is normally associated with satellite cell-mediated myonuclear accretion, hypertrophic adaptation proceeds in the absence of satellite cells in fully grown adult mice, but not in young growing mice. Emerging evidence also indicates that satellite cells play an important role in remodeling the extracellular matrix during hypertrophy.

Testosterone-induced muscle hypertrophy is associated with an increase in satellite cell number in healthy, young men

2003 ◽  
Vol 285 (1) ◽  
pp. E197-E205 ◽  
Author(s):  
Indrani Sinha-Hikim ◽  
Stephen M. Roth ◽  
Martin I. Lee ◽  
Shalender Bhasin
Keyword(s):  
Satellite Cell ◽  
Muscle Fiber ◽  
Spatial Orientation ◽  
Vastus Lateralis ◽  
Cell Number ◽  
Cell Ultrastructure ◽  
Weekly Dose ◽  
Direct Counting ◽  
Dose Dependent Increase ◽  
Dose Dependent

Testosterone (T) supplementation in men induces muscle fiber hypertrophy. We hypothesized that T-induced increase in muscle fiber size is associated with a dose-dependent increase in satellite cell number. We quantitated satellite cell and myonuclear number by using direct counting and spatial orientation methods in biopsies of vastus lateralis obtained at baseline and after 20 wk of treatment with a gonadotropin-releasing hormone agonist and a 125-, 300-, or 600-mg weekly dose of T enanthate. T administration was associated with a significant increase in myonuclear number in men receiving 300- and 600-mg doses. The posttreatment percent satellite cell number, obtained by direct counting, differed significantly among the three groups (ANCOVA P < 0.000001); the mean posttreatment values (5.0 and 15.0%) in men treated with 300- and 600-mg doses were greater than baseline (2.5 and 2.5%, respectively, P < 0.05 vs. baseline). The absolute satellite cell number measured by spatial orientation at 20 wk (1.5 and 4.0/mm) was significantly greater than baseline (0.3 and 0.6/mm) in men receiving the 300- and 600-mg doses ( P < 0.05). The change in percent satellite cell number correlated with changes in total ( r = 0.548) and free T concentrations ( r = 0.468). Satellite cell and mitochondrial areas were significantly higher and the nuclear-to-cytoplasmic ratio lower after treatment with 300- and 600-mg doses. We conclude that T-induced muscle fiber hypertrophy is associated with an increase in satellite cell number, a proportionate increase in myonuclear number, and changes in satellite cell ultrastructure.

scholarly journals Resident muscle stem cells are not required for testosterone-induced skeletal muscle hypertrophy

2019 ◽  
Vol 317 (4) ◽  
pp. C719-C724 ◽  
Author(s):  
Davis A. Englund ◽  
Bailey D. Peck ◽  
Kevin A. Murach ◽  
Ally C. Neal ◽  
Hannah A. Caldwell ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Stem Cells ◽  
Satellite Cell ◽  
Muscle Fiber ◽  
Muscle Hypertrophy ◽  
Cross Sectional ◽  
Muscle Stem Cells ◽  
Cell Abundance ◽  
Skeletal Muscle Hypertrophy ◽  
Testosterone Administration

It is postulated that testosterone-induced skeletal muscle hypertrophy is driven by myonuclear accretion as the result of satellite cell fusion. To directly test this hypothesis, we utilized the Pax7-DTA mouse model to deplete satellite cells in skeletal muscle followed by testosterone administration. Pax7-DTA mice (6 mo of age) were treated for 5 days with either vehicle [satellite cell replete (SC+)] or tamoxifen [satellite cell depleted (SC-)]. Following a washout period, a testosterone propionate or sham pellet was implanted for 21 days. Testosterone administration caused a significant increase in muscle fiber cross-sectional area in SC+ and SC- mice in both oxidative (soleus) and glycolytic (plantaris and extensor digitorum longus) muscles. In SC+ mice treated with testosterone, there was a significant increase in both satellite cell abundance and myonuclei that was completely absent in testosterone-treated SC- mice. These findings provide direct evidence that testosterone-induced muscle fiber hypertrophy does not require an increase in satellite cell abundance or myonuclear accretion. Listen to a podcast about this Rapid Report with senior author E. E. Dupont-Versteegden ( https://ajpcell.podbean.com/e/podcast-on-paper-that-shows-testosterone-induced-skeletal-muscle-hypertrophy-does-not-need-muscle-stem-cells /).

scholarly journals Rb1 Gene Inactivation Expands Satellite Cell and Postnatal Myoblast Pools

2011 ◽  
Vol 286 (22) ◽  
pp. 19556-19564 ◽  
Author(s):  
Tohru Hosoyama ◽  
Koichi Nishijo ◽  
Suresh I. Prajapati ◽  
Guangheng Li ◽  
Charles Keller
Keyword(s):  
Cell Cycle ◽  
Stem Cell ◽  
Satellite Cell ◽  
Muscle Fiber ◽  
Satellite Cells ◽  
Cell Activation ◽  
Cell Lineage ◽  
Cell Number ◽  
Fiber Formation

Satellite cells are well known as a postnatal skeletal muscle stem cell reservoir that under injury conditions participate in repair. However, mechanisms controlling satellite cell quiescence and activation are the topic of ongoing inquiry by many laboratories. In this study, we investigated whether loss of the cell cycle regulatory factor, pRb, is associated with the re-entry of quiescent satellite cells into replication and subsequent stem cell expansion. By ablation of Rb1 using a Pax7CreER,Rb1 conditional mouse line, satellite cell number was increased 5-fold over 6 months. Furthermore, myoblasts originating from satellite cells lacking Rb1 were also increased 3-fold over 6 months, while terminal differentiation was greatly diminished. Similarly, Pax7CreER,Rb1 mice exhibited muscle fiber hypotrophy in vivo under steady state conditions as well as a delay of muscle regeneration following cardiotoxin-mediated injury. These results suggest that cell cycle re-entry of quiescent satellite cells is accelerated by lack of Rb1, resulting in the expansion of both satellite cells and their progeny in adolescent muscle. Conversely, that sustained Rb1 loss in the satellite cell lineage causes a deficit of muscle fiber formation. However, we also show that pharmacological inhibition of protein phosphatase 1 activity, which will result in pRb inactivation accelerates satellite cell activation and/or expansion in a transient manner. Together, our results raise the possibility that reversible pRb inactivation in satellite cells and inhibition of protein phosphorylation may provide a new therapeutic tool for muscle atrophy by short term expansion of the muscle stem cells and myoblast pool.

scholarly journals Depletion of resident muscle stem cells inhibits muscle fiber hypertrophy induced by lifelong physical activity

2019 ◽  
Author(s):  
Davis A. Englund ◽  
Kevin A. Murach ◽  
Cory M. Dungan ◽  
Vandré C. Figueiredo ◽  
Ivan J. Vechetti ◽  
...  
Keyword(s):  
Physical Activity ◽  
Skeletal Muscle ◽  
Physical Function ◽  
Satellite Cell ◽  
Muscle Fiber ◽  
Satellite Cells ◽  
Muscle Growth ◽  
Free Access ◽  
Running Wheel ◽  
Hypertrophic Growth

AbstractBackgroundA reduction in skeletal muscle stem cell (satellite cell) content with advancing age is thought to directly contribute to the progressive loss of skeletal muscle mass and function with aging (sarcopenia). However, we reported that the depletion of satellite cells throughout adulthood did not affect the onset or degree of sarcopenia observed in sedentary old mice. The current study was designed to determine if lifelong physical activity would alter the requirements for satellite cells during aging.MethodsWe administered vehicle or tamoxifen to adult (5 months old) female Pax7-DTA mice for 5 consecutive days to effectively deplete satellite cells. Following a 2-month washout period, mice were assigned to physically active (free access to a running wheel) or sedentary (locked running wheel) conditions. Thirteen months later, at a mean age of 20 months, mice were sacrificed for subsequent analysis.ResultsSatellite cell depletion throughout adulthood negatively impacted physical function and limited muscle fiber hypertrophy in response to lifelong physical activity. To further interrogate these findings, we performed transcriptome-wide analyses on the hind limb muscles that experienced hypertrophic growth (plantaris and soleus) in response to lifelong physical activity. Our findings demonstrate that satellite cell function is muscle type-specific; fusion with fibers is apparent in oxidative muscles, while initiation of Gαi2 signaling appears to require satellite cells in glycolytic muscles to induce muscle growth..ConclusionsThese findings suggest that satellite cells, or their secretory products, are viable therapeutic targets to preserve physical function with aging and promote muscle growth in older adults who regularly engage in physical activity.

scholarly journals miR-21-5p Regulates the Proliferation and Differentiation of Skeletal Muscle Satellite Cells by Targeting KLF3 in Chicken

Genes ◽  
2021 ◽  
Vol 12 (6) ◽  
pp. 814
Author(s):  
Donghao Zhang ◽  
Jinshan Ran ◽  
Jingjing Li ◽  
Chunlin Yu ◽  
Zhifu Cui ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Satellite Cells ◽  
Muscle Development ◽  
Target Genes ◽  
Cell Number ◽  
Sequencing Data ◽  
Proliferation Markers ◽  
Muscle Satellite Cells ◽  
Skeletal Muscle Satellite Cells ◽  
Proliferation And Differentiation

The proliferation and differentiation of skeletal muscle satellite cells (SMSCs) play an important role in the development of skeletal muscle. Our previous sequencing data showed that miR-21-5p is one of the most abundant miRNAs in chicken skeletal muscle. Therefore, in this study, the spatiotemporal expression of miR-21-5p and its effects on skeletal muscle development of chickens were explored using in vitro cultured SMSCs as a model. The results in this study showed that miR-21-5p was highly expressed in the skeletal muscle of chickens. The overexpression of miR-21-5p promoted the proliferation of SMSCs as evidenced by increased cell viability, increased cell number in the proliferative phase, and increased mRNA and protein expression of proliferation markers including PCNA, CDK2, and CCND1. Moreover, it was revealed that miR-21-5p promotes the formation of myotubes by modulating the expression of myogenic markers including MyoG, MyoD, and MyHC, whereas knockdown of miR-21-5p showed the opposite result. Gene prediction and dual fluorescence analysis confirmed that KLF3 was one of the direct target genes of miR-21-5p. We confirmed that, contrary to the function of miR-21-5p, KLF3 plays a negative role in the proliferation and differentiation of SMSCs. Si-KLF3 promotes cell number and proliferation activity, as well as the cell differentiation processes. Our results demonstrated that miR-21-5p promotes the proliferation and differentiation of SMSCs by targeting KLF3. Collectively, the results obtained in this study laid a foundation for exploring the mechanism through which miR-21-5p regulates SMSCs.

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