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Apoptosis in skeletal muscle with aging
Amie Dirks1, Christiaan Leeuwenburgh
1University of Florida, Biochemistry of Aging Laboratory, College of Health and Human Performance, Center for Exercise Science, College of Medicine, Gainesville, Florida 32611, USA.
Summary
Aging muscle loss (sarcopenia) may involve programmed cell death (apoptosis). This study found increased apoptosis in aged rat gastrocnemius muscle, suggesting subtle apoptotic changes contribute to sarcopenia.
Area of Science:
- Muscle physiology
- Cellular biology
- Aging research
Background:
- Sarcopenia, age-related muscle mass loss, is a significant health concern.
- Apoptosis, or programmed cell death, is a potential contributor to fiber loss in sarcopenia.
- The mitochondria-mediated apoptosis pathway in skeletal muscle aging is not fully understood.
Purpose of the Study:
- To investigate age-related changes in the mitochondria-mediated apoptosis pathway in rat gastrocnemius muscle.
- To determine the role of apoptosis in the development of sarcopenia.
Main Methods:
- Comparison of gastrocnemius muscle from young (6-mo) and old (24-mo) male Fisher 344 rats.
- Assay of apoptosis markers (mono- and oligonucleosome fragmentation).
- Measurement of apoptotic regulatory proteins (cytochrome c, caspase-3, Bcl-2, Bax) and in vitro caspase cascade activation.
Main Results:
- Apoptosis was significantly increased (50%) in old rats compared to young rats.
- A correlation was found between cytosolic cytochrome c and caspase-3 activity, but neither increased with age.
- Caspase-3 activity correlated with apoptosis markers in aged rats, and procaspase-9 activation may limit the caspase cascade.
Conclusions:
- Subtle alterations in apoptosis are involved in age-related muscle loss (sarcopenia).
- The mitochondria-mediated apoptosis pathway plays a role in sarcopenia.
- Further research into caspase cascade regulation in skeletal muscle aging is warranted.