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Apoptosis does not increase with age in rat extraocular muscle
Author(s) -
McMullen Colleen A,
Andrade Francisco H,
DupontVersteegden Esther E
Publication year - 2008
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.22.1_supplement.1163.14
Subject(s) - tunel assay , apoptosis , sarcopenia , hindlimb , extraocular muscles , biology , medicine , endocrinology , mitochondrion , anatomy , microbiology and biotechnology , biochemistry
Sarcopenia decreases quality of life in the elderly. Changes in the structure and function of aging non‐locomotor muscles remain understudied, despite their importance for daily living. The fast and constant activity of the extraocular muscles (EOMs) imposes extreme mechanical and metabolic stresses, and may render EOMs more sensitive to aging. For example, EOMs have a higher incidence of age‐related mitochondrial defects that could result in apoptosis. Apoptosis seems to contribute to sarcopenia in hind limb muscles. Therefore, we hypothesized that apoptosis increases with age in the EOMs. Muscles from 6‐, 18‐, and 30‐mo old male Fisher 344‐Brown Norway rats were used to estimate mean fiber size, to demonstrate apoptosis by TUNEL and ELISA, and to measure caspase‐3, ‐8, ‐9, and ‐12 activity. EOM fiber area decreased 24% from 6 to 30‐mo of age (481±309 to 367±176 sq. μm respectively). TUNEL positive nuclei increased from 6‐mo to 18‐ and 30‐mo (29.41+ 10.95, 40.79+10.68, and 41.28+10.42 percent of fibers to TUNEL positive nuclei respectively). However, mono‐ and oligonucleosomal content was not elevated with age, indicating that TUNEL may have measured DNA damage. Caspase‐3, ‐8, ‐9, and ‐12 activity was not affected by aging. Based on these data, we conclude that in contrast to hind limb muscles, apoptosis does not increase with age in EOM. Other mechanisms must play a role in the age‐related decline in EOM fiber size.