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)
“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)
“I have never taken any exercise, except sleeping and resting, and I never intend to take any. Exercise is loathsome. And it cannot be any benefit when you are tired; and I was always tired.”
—Mark Twain [Samuel Langhorne Clemens] (1835–1910)
“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)
“What have we achieved in mowing down mountain ranges, harnessing the energy of mighty rivers, or moving whole populations about like chess pieces, if we ourselves remain the same restless, miserable, frustrated creatures we were before? To call such activity progress is utter delusion. We may succeed in altering the face of the earth until it is unrecognizable even to the Creator, but if we are unaffected wherein lies the meaning?”
—Henry Miller (1891–1980)