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:
“Whereas Freud was for the most part concerned with the morbid effects of unconscious repression, Jung was more interested in the manifestations of unconscious expression, first in the dream and eventually in all the more orderly products of religion and art and morals.”
—Lewis Mumford (1895–1990)
“Upon the whole, necessity is something, that exists in the mind, not in objects; nor is it possible for us ever to form the most distant idea of it, consider’d as a quality in bodies. Either we have no idea of necessity, or necessity is nothing but that determination of thought to pass from cause to effects and effects to causes, according to their experienc’d union.”
—David Hume (1711–1776)
“There is not enough exercise in this way of life. I try to make up by active gymnastics before I dress when I get up, by walking rapidly in the lower hall and the greenhouse after each meal for perhaps five to ten minutes, and a good hand rubbing before going to bed. I eat moderately; drink one cup of coffee at breakfast and one cup of tea at lunch and no other stimulant. My health is now, and usually, excellent.”
—Rutherford Birchard Hayes (1822–1893)
“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)
“There’s not one part of his physical being that’s like that of human beings. From his warped brain down to the tiniest argumentative cell of his huge carcass, he’s unearthly.”
—Willis Cooper. Rowland V. Lee. Wolf von Frankenstein (Basil Rathbone)
“When we say “science” we can either mean any manipulation of the inventive and organizing power of the human intellect: or we can mean such an extremely different thing as the religion of science the vulgarized derivative from this pure activity manipulated by a sort of priestcraft into a great religious and political weapon.”
—Wyndham Lewis (1882–1957)