Effects of Exercise On Satellite Cell Activity
Satellite cell activation is measured by the extent of proliferation and differentiation. Typically, satellite cell content is expressed per muscle fiber or as a percentage of total nuclear content, the sum of satellite cell nuclei and myonuclei. While the adaptive response to exercise largely varies on an individual basis on factors such as genetics, age, diet, acclimatization to exercise, and exercise volume, human studies have demonstrated general trends.
It is suggested that exercise triggers the release of signaling molecules including inflammatory substances, cytokines and growth factors from surrounding connective tissues and active skeletal muscles. Notably, HGF, a cytokine, is transferred from the extracellular matrix into muscles through the nitric-oxide dependent pathway. It is thought that HGF activates satellite cells, while insulin growth factor-I (IGF-1) and fibroblast growth factor (FGF) enhance satellite cell proliferation rate following activation. Studies have demonstrated that intense exercise generally increases IGF-1 production, though individual responses vary significantly. More specifically, IGF-1 exists in two isoforms: mechano growth factor (MGF) and IGF-IEa. While the former induces activation and proliferation, the latter causes differentiation of proliferating satellite cells.
Human studies have shown that both high resistance training and endurance training have yielded an increased number of satellite cells. These results suggest that a light, endurance training regimen may be useful to counteract the age-correlated satellite cell decrease. In high-resistance training, activation and proliferation of satellite cells are evidenced by increased cyclinD1 mRNA, and p21 mRNA levels. This is consistent with the fact that cyclinD1 and p21 upregulation correlates to division and differentiation of cells.
Satellite cell activation has also been demonstrated on an ultrastructural level following exercise. Aerobic exercise has been shown to significantly increase granular endoplasmic reticulum, free ribosomes, and mitochondria of the stimulated muscle groups. Additionally, satellite cells have been shown to fuse with muscle fibers, developing new muscle fibers. Other ultrastructural evidence for activated satellite cells include increased concentration of Golgi apparatus and pinocytotic vesicles.
Read more about this topic: Myosatellite Cell
Famous quotes containing the words effects of, effects, exercise, satellite, cell and/or activity:
“Oh that my Pow’r to Saving were confin’d:
Why am I forc’d, like Heav’n, against my mind,
To make Examples of another Kind?
Must I at length the Sword of Justice draw?
Oh curst Effects of necessary Law!
How ill my Fear they by my Mercy scan,
Beware the Fury of a Patient Man.”
—John Dryden (1631–1700)
“Society’s double behavioral standard for women and for men is, in fact, a more effective deterrent than economic discrimination because it is more insidious, less tangible. Economic disadvantages involve ascertainable amounts, but the very nature of societal value judgments makes them harder to define, their effects harder to relate.”
—Anne Tucker (b. 1945)
“I will have no Parsons around me but such as drink deep, ride to Hounds and caress the Wives and Daughters of their Parishioners. A Virtuous Parson does nothing to test or exercise the Faith of his Flock.”
—Aldous Huxley (1894–1963)
“Books are the best things, well used; abused, among the worst. What is the right use? What is the one end, which all means go to effect? They are for nothing but to inspire. I had better never see a book, than to be warped by its attraction clean out of my own orbit, and made a satellite instead of a system.”
—Ralph Waldo Emerson (1803–1882)
“Why inspire in us a horror of our being?... To look upon the universe as a prison cell and all men as criminals about to be executed is the idea of a fanatic.”
—Voltaire [François Marie Arouet] (1694–1778)
“Envy has blackened every page of his history.... The future, in its justice, will number him among those men whom passions and an excess of activity have condemned to unhappiness, through the gift of genius.”
—Eugène Delacroix (1798–1863)