Related Experiment Video
Updated: May 29, 2026
08:03
Treatment of Ligament Constructs with Exercise-conditioned Serum: A Translational Tissue Engineering Model
Published on: June 11, 2017
Androgens affect myogenesis in vitro and increase local IGF-1 expression.
Nick Sculthorpe1, Andrew M Solomon, Andrea C M Sinanan
1Muscle Cellular and Molecular Physiology Research Group, Institute for Sport and Physical Activity Research, University of Bedfordshire, Bedford, United Kingdom. nick.sculthorpe@beds.ac.uk
Medicine and Science in Sports and Exercise
|September 28, 2011
Summary
Anabolic androgens like testosterone (T) and insulin-like growth factor 1 (IGF-1) promote skeletal muscle growth. T increases IGF-1 messenger RNA (mRNA) production, suggesting IGF-1 mediates androgen effects on muscle hypertrophy.
Area of Science:
- Molecular Endocrinology
- Cellular Biology
- Muscle Physiology
Background:
- The precise mechanisms linking anabolic androgens to skeletal muscle hypertrophy are not fully elucidated.
- A potential interaction between androgens and locally produced insulin-like growth factor 1 (IGF-1) is hypothesized to play a role in muscle growth.
- Understanding these pathways is crucial for developing therapeutic strategies for muscle wasting conditions.
Purpose of the Study:
- To investigate whether androgens enhance the differentiation of human muscle precursor cells in vitro.
- To examine the effects of testosterone (T) alone and in combination with IGF-1 on IGF-1 messenger RNA (mRNA) expression.
- To elucidate the role of IGF-1 as a mediator in androgen-induced muscle hypertrophy.
Main Methods:
- Human muscle-derived cells were cultured under low-serum conditions to induce differentiation.
- Cultures were exposed to varying concentrations of testosterone (T) or IGF-1 for 3 or 7 days.
- Immunocytochemistry and real-time polymerase chain reaction (RT-PCR) were employed to assess myogenic commitment, fusion index, and gene expression, including androgen receptor levels.
Main Results:
- After 7 days of exposure, both T and IGF-1 significantly increased the muscle cell fusion index, indicating enhanced differentiation.
- Testosterone (T) treatment led to a significant increase in IGF-1 mRNA expression, while exogenous IGF-1 reduced IGF-1 mRNA transcription.
- The observed effects of T on muscle differentiation were reversible upon treatment with flutamide, an androgen receptor antagonist.
Conclusions:
- Both testosterone (T) and insulin-like growth factor 1 (IGF-1) promote myogenic commitment in human muscle precursor cells after prolonged exposure.
- Testosterone (T) upregulates IGF-1 mRNA, supporting the role of IGF-1 as a key mediator in androgen-driven cellular pathways for muscle hypertrophy.
- This study establishes a novel in vitro model for investigating growth factor involvement in androgen-mediated skeletal muscle development.
Related Concept Videos
01:16TGF - β Signaling Pathway
The TGF-β signaling pathway regulates cell growth, differentiation, adhesion, motility, and development. TGF-β ligands that induce TGF-β signaling are synthesized in their latent form. Several proteases or cell surface receptors such as integrins act upon the latent form, releasing the active ligand. There are three types of mammalian TGF-βs: (TGF-β1, TGF-β2, and TGF-β3) that bind as homodimers or heterodimers to TGF-β receptors. The TGF-β receptors are of three kinds RI, RII, and RIII. The RI...
01:22Target Cell Response to Hormones
Hormones intricately bind to receptors on the surface or within target cells, initiating a cascade of cellular responses.
Notably, the cellular response can be regulated by altering the number of receptors expressed in the cell. For example, prolonged exposure to elevated hormone levels results in a gradual decline or down-regulation in the number of receptors for that specific hormone on the cell surface. Conversely, in response to low hormone levels, cells may use up-regulation, producing an...
Notably, the cellular response can be regulated by altering the number of receptors expressed in the cell. For example, prolonged exposure to elevated hormone levels results in a gradual decline or down-regulation in the number of receptors for that specific hormone on the cell surface. Conversely, in response to low hormone levels, cells may use up-regulation, producing an...
01:26Testosterone: Functions and Regulation
The intricate hormonal interplay essential for male reproductive health begins with the release of gonadotropin-releasing hormone (GnRH) by the hypothalamus. This hormone prompts the pituitary gland to secrete follicle-stimulating hormone (FSH) and luteinizing hormone (LH). LH targets the Leydig cells in the testes, stimulating them to produce and release testosterone. In concert with testosterone, FSH acts on the Sertoli cells within the seminiferous tubules to facilitate the release of...
01:13Formation of Muscle Fibers from Myoblasts
De novo myogenesis, or the formation of muscle fibers, begins during the early embryonic stages. The skeletal muscle is formed from somites– blocks of embryonic cell layers. The somites are further divided into dermatomes, myotomes, sclerotomes, and syndetomes. Among these, the myotomes give rise to muscle fibers.
Muscle progenitor cells (MPCs) are formed from the myotomes. MPCs express genes that encode the transcription factors Pax3 and Pax7. Along with Pax 3/7, other transcription factors...
Muscle progenitor cells (MPCs) are formed from the myotomes. MPCs express genes that encode the transcription factors Pax3 and Pax7. Along with Pax 3/7, other transcription factors...
01:31Hormones of the Adrenal Glands
Adrenal hormones play a pivotal role in maintaining the body's electrolyte balance and orchestrating responses to stress, showcasing the intricate functions of the adrenal cortex and medulla.
The adrenal cortex, a powerhouse of hormone synthesis, generates over two dozen corticosteroid hormones. The zona glomerulosa produces mineralocorticoids, exemplified by aldosterone, influencing the electrolyte composition of body fluids. The synthesis of glucocorticoids such as cortisol and corticosterone...
The adrenal cortex, a powerhouse of hormone synthesis, generates over two dozen corticosteroid hormones. The zona glomerulosa produces mineralocorticoids, exemplified by aldosterone, influencing the electrolyte composition of body fluids. The synthesis of glucocorticoids such as cortisol and corticosterone...
02:38Mitogens and the Cell Cycle
Mitogens and their receptors play a crucial role in controlling the progression of the cell cycle. However, the loss of mitogenic control over cell division leads to tumor formation. Therefore, mitogens and mitogen receptors play an important role in cancer research. For instance, the epidermal growth factor (EGF) - a type of mitogen and its transmembrane receptor (EGFR), decides the fate of the cell's proliferation. When EGF binds to EGFR, a member of the ErbB family of tyrosine kinase...